INVITED SPEAKERS
Electrochemical Properties of Two-Dimensional Atomic Layers
Electrochemical Properties of Two-Dimensional Atomic Layers
Leela Mohana Reddy Arava
Department of Mechanical Engineering
Wayne State University,
Detroit, Michigan. USA
Two-dimensional (2D) atomic layered materials like graphene have gained tremendous research attention due to their unique properties, such as high surface area, ballistic conductivity, high elasticity, very high mechanical strength, rapid heterogeneous electron transfer, tunable physical and chemical properties. In particular, electronic properties of these materials are usually different from the bulk due to confinement of electrons on edges/surface and hence attract researchers in the field of “electrochemistry”. As electrochemical reactions occur on the surface of the material/electrode, charge density and chemical nature at the surface of the material plays a key role in determining overall electrochemical properties. Due to intrinsic properties of 2D materials, especially tunable surface properties blossomed the electrochemistry related applications such as sensing, catalysis, energy storage etc. This talk will focus on large-scale synthesis of 2D materials by exfoliation method and their application in electrochemical energy storage. Structure-property relation driven by synthesis parameters of 2D materials on electrochemical reaction kinetics, charge storage capacity and cycle life will be discussed.
Magnetic Nanostructures by Template Assisted Deposition Techniques:
From Antidot Thin Films to Multisegmented Nanowires and Metallic Nanotubes
Víctor M. Prida
Department of Physics, University of Oviedo, Calvo Sotelo s/n, 33007-Oviedo, Asturias, Spain.
Ordered arrays of nanostructured ferromagnetic materials have attracted huge interest of the research community due to their singular magnetic properties and their potential applications in high-density recording media, magnetic sensors or energy conversion and microwave devices [1]. The growth of nanostructured materials by means of different deposition methods employing nanoporous anodic aluminum oxide (AAO) membranes as patterned templates has been widely used during last years due to the outstanding features exhibited by these nanoporous templates. The highly self-ordered hexagonal symmetry of the pores arrangement exhibited by the AAO templates displays narrow pore size distributions having well-defined interpore distances. Furthermore, advanced deposition techniques suitable for conformal coating of 3D structured substrates, such as atomic layer deposition (ALD), allow for additional control of the morphological parameters of AAO membranes, enabling independent control of pores diameter, while keeping constant the interpore distances. The spatial and periodic pores arrangement of the AAO templates, together with the confined growth of the magnetic material at the nanoscale deposited in the nanoporous alumina template, translate into the appearing of cooperative phenomena in the nanostructed materials, which in turn lead to tailor novel functional properties that differ from that of 3D bulk and 2D thin film systems [2, 3]. The synthesis, morphology, structural properties and magnetic behavior of ordered arrays of ferromagnetic nanowires made of Fe, Ni, Co, and their alloys by means of electrochemical deposition methods, together with magnetic nanotubes grown via ALD deposition technique inside the nanopores of the AAO templates, and ferromagnetic thin films with ordered nanoholes (antidots), designed by replicating the nanoporous arrangement of the AAO substrate on which the metallic layer is deposited by vacuum thermal evaporation technique, will be presented. The main features of the peculiar magnetic properties exhibited by these novel nanostructured materials will be discussed.
References:
[1] Y. P. Ivanov, A. Chuvilin, S. Lopatin, J. Kosel, ACS Nano, 10, 5326 (2016).
Department of Mechanical Engineering
Wayne State University,
Detroit, Michigan. USA
Two-dimensional (2D) atomic layered materials like graphene have gained tremendous research attention due to their unique properties, such as high surface area, ballistic conductivity, high elasticity, very high mechanical strength, rapid heterogeneous electron transfer, tunable physical and chemical properties. In particular, electronic properties of these materials are usually different from the bulk due to confinement of electrons on edges/surface and hence attract researchers in the field of “electrochemistry”. As electrochemical reactions occur on the surface of the material/electrode, charge density and chemical nature at the surface of the material plays a key role in determining overall electrochemical properties. Due to intrinsic properties of 2D materials, especially tunable surface properties blossomed the electrochemistry related applications such as sensing, catalysis, energy storage etc. This talk will focus on large-scale synthesis of 2D materials by exfoliation method and their application in electrochemical energy storage. Structure-property relation driven by synthesis parameters of 2D materials on electrochemical reaction kinetics, charge storage capacity and cycle life will be discussed.Magnetic Nanostructures by Template Assisted Deposition Techniques:
From Antidot Thin Films to Multisegmented Nanowires and Metallic Nanotubes
Ordered arrays of nanostructured ferromagnetic materials have attracted huge interest of the research community due to their singular magnetic properties and their potential applications in high-density recording media, magnetic sensors or energy conversion and microwave devices [1]. The growth of nanostructured materials by means of different deposition methods employing nanoporous anodic aluminum oxide (AAO) membranes as patterned templates has been widely used during last years due to the outstanding features exhibited by these nanoporous templates. The highly self-ordered hexagonal symmetry of the pores arrangement exhibited by the AAO templates displays narrow pore size distributions having well-defined interpore distances. Furthermore, advanced deposition techniques suitable for conformal coating of 3D structured substrates, such as atomic layer deposition (ALD), allow for additional control of the morphological parameters of AAO membranes, enabling independent control of pores diameter, while keeping constant the interpore distances. The spatial and periodic pores arrangement of the AAO templates, together with the confined growth of the magnetic material at the nanoscale deposited in the nanoporous alumina template, translate into the appearing of cooperative phenomena in the nanostructed materials, which in turn lead to tailor novel functional properties that differ from that of 3D bulk and 2D thin film systems [2, 3]. The synthesis, morphology, structural properties and magnetic behavior of ordered arrays of ferromagnetic nanowires made of Fe, Ni, Co, and their alloys by means of electrochemical deposition methods, together with magnetic nanotubes grown via ALD deposition technique inside the nanopores of the AAO templates, and ferromagnetic thin films with ordered nanoholes (antidots), designed by replicating the nanoporous arrangement of the AAO substrate on which the metallic layer is deposited by vacuum thermal evaporation technique, will be presented. The main features of the peculiar magnetic properties exhibited by these novel nanostructured materials will be discussed.
References:
[1] Y. P. Ivanov, A. Chuvilin, S. Lopatin, J. Kosel, ACS Nano, 10, 5326 (2016).
[2] V. M Prida, et al, Nanoscale Research Letters, 8, 263 (2013).
[3] J. García et al, Journal of Materials Chemistry C 3 (18), 4688 (2015).
Study and Characterization on Materials with Low Dimensionality
by Transmission Electron Microscopy
Enrique Díaz Barriga Castro
Centro de Investigación en Química Aplicada (CIQA)
Saltillo, Coahuila, Mexico.
The study and knowledge of the physical and mechanical properties of nanomaterials depends on the ability of tools and methodologies for measuring, detecting, manufacture and manipulate matter at the nanoscale. Electron microscopy has advantages over other characterization techniques, for example, images of objects that are directly related to the structure, morphology and composition are descriptive. Today the technological and scientific development is of great interest due to the correlation with atomic arrangements properties offered by its size and high surface-volume ratio. The rapid development of nanotechnology and nanomaterials has led to the need to make structural changes and phases present by in-situ experiments on materials in scale of a few nanometers.
Transmission electron microscopy is a powerful technique to study and characterize the morphology, structure and chemical composition of condensed matter. In the field of nanoscience and nanotechnology, there are various techniques that can provide spatial resolution producing structural changes due to external stimuli in real time, including the in-situ electron microscopy is probably the most versatile technique is found. Today, almost every aspect of discovery in nano-scale can benefit from this technique (TEM in-situ), which is responsible for the discovery of new phenomena of transformations in systems such as groups of atoms, nanoparticles, nanotubes, nanowires, sheets graphene and in some polymers, which are difficult to examine by other characterization techniques. This talk will focus, in an overview of the transmission electron microscopy and its implications for the study and characterization on materials with low dimensionality.
Plasma surface modification of nanoparticles to prepare polymer composites with improved properties
M. G. Neira Velázquez1, G. Soria Argüello1, E. Hernández Hernández1, C. A. Avila Orta1, S. G. Solís Rosales1, M. Rosales Navarro1, G. Mendez Padilla1
In the last decade, we had worked at CIQA with plasma modification of different types of nanoparticles such as carbon nanofibers, carbon nanotubes, graphene, graphite, copper, silver, silica, etc. Particles had been plasma modified in a simple RF (13.56 MHz) plasma reactor, varying power and time of treatment mainly. The process to perform the treatment of nanoparticles had been mainly plasma polymerization, where a thin coating of polymer is deposited at the surface of the particle. Nanoparticles had been modified mainly to increase their chemical compatibility towards different polymers, since polymers and particles are generally of different chemical nature, and it is necessary to carry out the surface modification of particles in order to improve the compatibility between the two phases.
References
Study and Characterization on Materials with Low Dimensionality
by Transmission Electron Microscopy
by Transmission Electron Microscopy
Enrique Díaz Barriga Castro
Centro de Investigación en Química Aplicada (CIQA)
Saltillo, Coahuila, Mexico.
The study and knowledge of the physical and mechanical properties of nanomaterials depends on the ability of tools and methodologies for measuring, detecting, manufacture and manipulate matter at the nanoscale. Electron microscopy has advantages over other characterization techniques, for example, images of objects that are directly related to the structure, morphology and composition are descriptive. Today the technological and scientific development is of great interest due to the correlation with atomic arrangements properties offered by its size and high surface-volume ratio. The rapid development of nanotechnology and nanomaterials has led to the need to make structural changes and phases present by in-situ experiments on materials in scale of a few nanometers.
Transmission electron microscopy is a powerful technique to study and characterize the morphology, structure and chemical composition of condensed matter. In the field of nanoscience and nanotechnology, there are various techniques that can provide spatial resolution producing structural changes due to external stimuli in real time, including the in-situ electron microscopy is probably the most versatile technique is found. Today, almost every aspect of discovery in nano-scale can benefit from this technique (TEM in-situ), which is responsible for the discovery of new phenomena of transformations in systems such as groups of atoms, nanoparticles, nanotubes, nanowires, sheets graphene and in some polymers, which are difficult to examine by other characterization techniques. This talk will focus, in an overview of the transmission electron microscopy and its implications for the study and characterization on materials with low dimensionality.
Plasma surface modification of nanoparticles to prepare polymer composites with improved properties
M. G. Neira Velázquez1, G. Soria Argüello1, E. Hernández Hernández1, C. A. Avila Orta1, S. G. Solís Rosales1, M. Rosales Navarro1, G. Mendez Padilla1
1 Centro de Investigación en Química Aplicada, Saltillo, Coahuila, México.
In the last decade, we had worked at CIQA with plasma modification of different types of nanoparticles such as carbon nanofibers, carbon nanotubes, graphene, graphite, copper, silver, silica, etc. Particles had been plasma modified in a simple RF (13.56 MHz) plasma reactor, varying power and time of treatment mainly. The process to perform the treatment of nanoparticles had been mainly plasma polymerization, where a thin coating of polymer is deposited at the surface of the particle. Nanoparticles had been modified mainly to increase their chemical compatibility towards different polymers, since polymers and particles are generally of different chemical nature, and it is necessary to carry out the surface modification of particles in order to improve the compatibility between the two phases.
The polymer nanocomposites obtained after mixing the modified particles with different polymers by melt mixing or in situ polymerization. The polymer composites obtained, had been analyzed by thermal analysis (DSC and TGA), crystallinity was evaluated by x-Ray Diffraction and the mechanical properties of the composites had also been obtained, mainly Young modulus and in some cases antimicrobial properties had also been evaluated. In general had been observed that polymers containing modified particles or nanoparticles present better properties than those containing pristine particles. Plasma treatment improves the compatibility between polymer and particles and the properties of the composites are enhanced.
References
[1] M. G. Neira-Velázquez, J. J. Borjas-Ramos, E. Hernández-Hernández, C. G. Hernández-Ramos, R. I. Narro-Céspedes. Plasma Processes and Polymers, 2015, 12, 477-485.
[2] Ernesto Hernández-Hernández, María G. Neira-Velázquez, Hilda Guerrero-Alvarado, José F. Hernández-Gámez, Pablo González-Morones, Carlos A. Ávila-Orta, Yibran A. Perera-Mercado, José J. Borjas-Ramos, Marissa Pérez Álvarez, Anna D. Iliná, Pascual Bartolo-Pérez, Plasma Chemistry and Plasma Processing, 2015.
[3] P. Gonzalez Morones, C. A. Avila, D. Navarro, and M. G. Neira Velazquez, Afinidad LXX, 563, 201-205, 2013.
(Video-conferences)
On the Application of First Order Reversal Curve method for Magnetic Nanostructures Characterization
Javier García
Leibniz Institute for Solid State and Materials Research Dresden, Germany.
The continuous growth of the nanotechnological applications makes necessary the well understanding of nature behaviors at such a low range of dimensionality. The characterization of their intrinsic properties remains, in general, complicated because of the low signal or the amount of material accessible by the preparation route. Magnetic nanowires grown into the pores of anodic alumina templates are of great interest due to the massive production of different nanostructures, by means of low cost procedures. However, magnetic characterization of single nanowires, although possible, is complicated and requires highly sophisticated equipment. This fact makes necessary the measurement of magnetic properties when the nanowires are still embedded into the pores of the alumina membrane, in order to have signal enoughwhen many nanowires are equally contributing to the total magnetic signal [1]. However, when the nanowires are still arranged, they are very close to each other, fact that allows them to interact through magnetostatic interactions [2]. The First Order Reversal Curve (FORC) method has been widely employed for the evaluation of individual properties of ferromagnetic nanoentities as extracted from macroscopic measurements of magnetic nanowire arrays [3,4]. This method is based on the assumption that in this kind of system the major magnetic hysteresis loop corresponds to the superposition of several magnetization reversal processes that may be attributed to the contribution of each nanowire into the array. In this sense, the magnetic switching processes of the nanowires into the array can be studied and evaluated in order to obtain the switching field distribution of the magnetic nanowire array and their mean field interaction. In this work, an overview of such technique is presented. Furthermore, different types of heterogeneous nanostructures, based on transition metal alloys, have been evaluated by this technique in order to stablish its range of applicability and usefulness.
References:
[1] V. M Prida et al, Nanoscale Research Letters, 8(1), 263 (2013).
[2] L. Clime et al. Journal of Magnetism and Magnetic Materials, 297, 60–70 (2006).
[3] C.-I. Dobrota and A. Stancu Journal of Applied Physics, 113(4), 043928 (2013).
[4] P. Sergelius et al, J. Phys. D: Appl. Phys. 49, 14500 (2016).
Ion beam obtained rutile TiO2 nanostructures: photocatalytic and biocompatible properties
Ruy Sanz González
Instituto de Microelectrónica de Madrid (CSIC), Tres Cantos, Madrid.Spain
In this contribution I will present recent results on the enhanced photo-activity yield and bio-response of crystalline nanospikes created on rutile TiO2 single crystals and thermally grown polycrystalline rutile TiO2 surfaces. The method for generating these nanospikes is based on high energy ion beam irradiation and a subsequent chemical HF etching [1], which previously has been employed for modifying the TiO2 response to biomolecules [2]. Although the created nanospikes preserved the rutile structure, they contain damage in their crystal lattice. We have experimentally studied the structural, compositional, and optical variations of the nanostructures and relate this to changes in efficiency of UV photo-degradation of organic molecules [3,4] and nanostructure recognition of two types of cells: human mesenchymal stem cells [5] and aortic vascular smooth muscle cells.
The present work highlights the complexity involved in understanding the photoactivity and bioresponse of nanostructures, where many factors – optics, reactivity and effective exposed surface – have to be taken into account when comparing the efficiency of TiO2 nanostructures with flat surfaces.
References:
[1] R. Sanz et al Nano Lett. 2006, 6, 1065–1068.
[5] D. Gallach Pérez et al Colloids and surfaces. B: Biointerfaces 2014 126, 146 – 153.
Fabrication of New Class of Intermetallic Nanowires by a New Synthesis Method
Karoline O. Mora1, Luiz A. S. de Oliveira2, Priscila F. S. Rosa1, Fanny Beron1, Pascoal G. Pagliuso1, Kleber R. Pirota1
1Instituto de Física ''Gleb Wataghin'', UNICAMP, Campinas-SP, Brasil. 2Núcleo Multidisciplinar de Pesquisa, UFRJ- Campus Xérem, Duque de Caixias-RJ, Brasil
Nanowires belong to a new class of quasi-1D materials that have been attracting great interest in the last few years due to their numerous multidisciplinary potential applications. Among the several procedures developed, the template-assisted fabrication methods have been widely used for the fabrication of magnetic nanowire arrays produced by electrochemical deposition due its simple, efficient and low cost implementation. However, the nanowires obtained by this method generally present poor crystallinity and are restricted to metallic alloys. In this context, it is highly desirable to develop alternative techniques to synthesize a wide range of high quality crystalline nanowires. Recently, the novel metallic-flux nanonucleation (MFNN) technique has been successfully developed to nucleate crystalline nanowires inside alumina membrane pores [1,2]. The nanoporous template presents several advantages, such as excellent pore size control over large areas and highly regular pattern of the pores. Thus, by using the alumina template during a metallic flux growth, the MFNN technique is able to confine the crystalline compounds into a quasi-1D shape opening the opportunity for fabricating novel intermetallic compounds.
In this work we present the magnetic characterization of the Fe3Ga4 intermetallic compound synthesized by the MFNN technique in both bulk and nanowire forms. The compound presents a complex base-centered monoclinic structure and exhibits an intricate magnetic behavior. At low magnetic fields, a ferromagnetic (FM) state develops below T1 = 50 K, while at higher temperatures, antiferromagnetism (AFM) takes place with a Néel temperature T2 = 390 K. This magnetic behavior has been explained by Moriya and Usami's theory that predicts coexistence of FM and AFM states in itinerant electron systems. In this regard, we report the dimensionality effects on the Fe3Ga4 magnetic phase diagram H-T, which was constructed for both bulk and nanowire systems using magnetization, specific heat and electrical resistivity measurements. The results are discussed in the framework of the Moriya and Usami's theory on magnetic phase transitions in itinerant-electron systems. We strongly believe that the possibility of growing intermetallic compounds in the nanowire form will open an interesting branch in the understanding of fundamental properties as well as to control the nanowire characteristics for a desired applications.
[1] Pirota K. R., Béron F., Oliveira L. A. S. de, Moura K. O., Knobel M., Pagliuso P. G., Garifezi T. M., Jesus C. B. R. de, Rettori C., Adriano C., Rosa P. F. S., Urbano R. R., Iwamoto W. A., Arzuza L. C. C., Carvalho P. G. (2014). Processo de produção de nanofios monocristalinos intermetálicos. BR patent 10 2014 019794 0.
[2] Rosa P. F. S., Oliveira L. A. S. de, Jesus C. B. R. de, Moura K. O., Adriano C., Iwamoto W., Garizeti, T. M., Granado E., Saleta M. E., Pirota K. R. and Pagliuso P. G. (2014). Exploring the effects of dimensionality on the magnetic properties of intermetallic nanowires. Solid State Communications, 14.
Magnetite nanoparticles with bulk-like properties
Magnetic nanoparticles (NP) systems have long been subject to study finite-size and surface effects. The thermal decomposition of an organic iron precursor in an organic medium allows the preparation of highly crystalline iron oxide NP with excellent magnetic parameters in contrast with the co-precipitation method [1]. Saturation magnetization was size independent in the 5-20 nm range and almost reached the expected value for bulk magnetite at low temperatures, higher in those NP with oleic acid covalently bonded to the surface. In 5 nm particles the surface contribution to magnetic anisotropy could be established analytically using the Tln(t/t0) scaling, confirming that surface anisotropy causes the broadening of their energy barrier distribution [2]. X-ray absorption spectra suggested charge transfer from the NP to the covalent bonded surfactant. X-ray magnetic circular dichroism confirmed the dependence of the magnetic moment on the synthesis method, including surface bond, and suggested that the orbital momentum is more effectively quenched in covalently bonded NPs. The low-temperature <Sz> = 3.63 μB/f.u. obtained in the latter case, is very close to those reported for bulk samples (3.90-3.95 μB/f.u.). High resolution transmission electron microscopy combined with electron energy loss spectroscopy/electron magnetic chiral dichroism on individual nanoparticles confirmed that the foregoing is related to the crystal quality of the NP. Density functional theory calculations showed that the covalent bond at the particles’ surfaces would enhance the magnetization of the surface in an equivalent of 1 μB per surface unit cell [3]. Application of these high-magnetization magnetite nanoparticles enabled magnetic resonance imaging of brain and liver in mice, and easy quantification of the biodistribution with magnetization measurements [4]. Coating the particles with silica enabled to control their aggregation state. An optimum aggregation point was observed in NMR experiments, and it was accounted for in first approximation using a simple liner chain model.
Acknowledgements
[1] X. Batlle et al., J. Appl. Phys. 109, 07B524 (2011)
(Video-conferences)
On the Application of First Order Reversal Curve method for Magnetic Nanostructures Characterization
Javier García
Leibniz Institute for Solid State and Materials Research Dresden, Germany.
The continuous growth of the nanotechnological applications makes necessary the well understanding of nature behaviors at such a low range of dimensionality. The characterization of their intrinsic properties remains, in general, complicated because of the low signal or the amount of material accessible by the preparation route. Magnetic nanowires grown into the pores of anodic alumina templates are of great interest due to the massive production of different nanostructures, by means of low cost procedures. However, magnetic characterization of single nanowires, although possible, is complicated and requires highly sophisticated equipment. This fact makes necessary the measurement of magnetic properties when the nanowires are still embedded into the pores of the alumina membrane, in order to have signal enoughwhen many nanowires are equally contributing to the total magnetic signal [1]. However, when the nanowires are still arranged, they are very close to each other, fact that allows them to interact through magnetostatic interactions [2]. The First Order Reversal Curve (FORC) method has been widely employed for the evaluation of individual properties of ferromagnetic nanoentities as extracted from macroscopic measurements of magnetic nanowire arrays [3,4]. This method is based on the assumption that in this kind of system the major magnetic hysteresis loop corresponds to the superposition of several magnetization reversal processes that may be attributed to the contribution of each nanowire into the array. In this sense, the magnetic switching processes of the nanowires into the array can be studied and evaluated in order to obtain the switching field distribution of the magnetic nanowire array and their mean field interaction. In this work, an overview of such technique is presented. Furthermore, different types of heterogeneous nanostructures, based on transition metal alloys, have been evaluated by this technique in order to stablish its range of applicability and usefulness.
References:
[1] V. M Prida et al, Nanoscale Research Letters, 8(1), 263 (2013).
[1] V. M Prida et al, Nanoscale Research Letters, 8(1), 263 (2013).
[2] L. Clime et al. Journal of Magnetism and Magnetic Materials, 297, 60–70 (2006).
[3] C.-I. Dobrota and A. Stancu Journal of Applied Physics, 113(4), 043928 (2013).
[4] P. Sergelius et al, J. Phys. D: Appl. Phys. 49, 14500 (2016).
In this contribution I will present recent results on the enhanced photo-activity yield and bio-response of crystalline nanospikes created on rutile TiO2 single crystals and thermally grown polycrystalline rutile TiO2 surfaces. The method for generating these nanospikes is based on high energy ion beam irradiation and a subsequent chemical HF etching [1], which previously has been employed for modifying the TiO2 response to biomolecules [2]. Although the created nanospikes preserved the rutile structure, they contain damage in their crystal lattice. We have experimentally studied the structural, compositional, and optical variations of the nanostructures and relate this to changes in efficiency of UV photo-degradation of organic molecules [3,4] and nanostructure recognition of two types of cells: human mesenchymal stem cells [5] and aortic vascular smooth muscle cells.
The present work highlights the complexity involved in understanding the photoactivity and bioresponse of nanostructures, where many factors – optics, reactivity and effective exposed surface – have to be taken into account when comparing the efficiency of TiO2 nanostructures with flat surfaces.
Ion beam obtained rutile TiO2 nanostructures: photocatalytic and biocompatible properties
Ruy Sanz González
Instituto de Microelectrónica de Madrid (CSIC), Tres Cantos, Madrid.Spain
CNR-IMM, Catania, Italy
References:
[1] R. Sanz et al Nano Lett. 2006, 6, 1065–1068.
[1] R. Sanz et al Nano Lett. 2006, 6, 1065–1068.
[2] J. V. Pérez-Girón et al. Nuclear Inst.and Methods in Physics Res.B 2014, 379, 67-74.
[3] ISO 10678:2010(E). International Organization for Standardization (2010). Switzerland.
[4] R. Sanz; et al. J. App. Phys. 2015. 117 - 7, 074903.
[5] D. Gallach Pérez et al Colloids and surfaces. B: Biointerfaces 2014 126, 146 – 153.
Magnetic nanoparticles (NP) systems have long been subject to study finite-size and surface effects. The thermal decomposition of an organic iron precursor in an organic medium allows the preparation of highly crystalline iron oxide NP with excellent magnetic parameters in contrast with the co-precipitation method [1]. Saturation magnetization was size independent in the 5-20 nm range and almost reached the expected value for bulk magnetite at low temperatures, higher in those NP with oleic acid covalently bonded to the surface. In 5 nm particles the surface contribution to magnetic anisotropy could be established analytically using the Tln(t/t0) scaling, confirming that surface anisotropy causes the broadening of their energy barrier distribution [2]. X-ray absorption spectra suggested charge transfer from the NP to the covalent bonded surfactant. X-ray magnetic circular dichroism confirmed the dependence of the magnetic moment on the synthesis method, including surface bond, and suggested that the orbital momentum is more effectively quenched in covalently bonded NPs. The low-temperature <Sz> = 3.63 μB/f.u. obtained in the latter case, is very close to those reported for bulk samples (3.90-3.95 μB/f.u.). High resolution transmission electron microscopy combined with electron energy loss spectroscopy/electron magnetic chiral dichroism on individual nanoparticles confirmed that the foregoing is related to the crystal quality of the NP. Density functional theory calculations showed that the covalent bond at the particles’ surfaces would enhance the magnetization of the surface in an equivalent of 1 μB per surface unit cell [3]. Application of these high-magnetization magnetite nanoparticles enabled magnetic resonance imaging of brain and liver in mice, and easy quantification of the biodistribution with magnetization measurements [4]. Coating the particles with silica enabled to control their aggregation state. An optimum aggregation point was observed in NMR experiments, and it was accounted for in first approximation using a simple liner chain model.
[5] D. Gallach Pérez et al Colloids and surfaces. B: Biointerfaces 2014 126, 146 – 153.
Fabrication of New Class of Intermetallic Nanowires by a New Synthesis Method
Karoline O. Mora1, Luiz A. S. de Oliveira2, Priscila F. S. Rosa1, Fanny Beron1, Pascoal G. Pagliuso1, Kleber R. Pirota1
1Instituto de Física ''Gleb Wataghin'', UNICAMP, Campinas-SP, Brasil. 2Núcleo Multidisciplinar de Pesquisa, UFRJ- Campus Xérem, Duque de Caixias-RJ, Brasil
Nanowires belong to a new class of quasi-1D materials that have been attracting great interest in the last few years due to their numerous multidisciplinary potential applications. Among the several procedures developed, the template-assisted fabrication methods have been widely used for the fabrication of magnetic nanowire arrays produced by electrochemical deposition due its simple, efficient and low cost implementation. However, the nanowires obtained by this method generally present poor crystallinity and are restricted to metallic alloys. In this context, it is highly desirable to develop alternative techniques to synthesize a wide range of high quality crystalline nanowires. Recently, the novel metallic-flux nanonucleation (MFNN) technique has been successfully developed to nucleate crystalline nanowires inside alumina membrane pores [1,2]. The nanoporous template presents several advantages, such as excellent pore size control over large areas and highly regular pattern of the pores. Thus, by using the alumina template during a metallic flux growth, the MFNN technique is able to confine the crystalline compounds into a quasi-1D shape opening the opportunity for fabricating novel intermetallic compounds.
In this work we present the magnetic characterization of the Fe3Ga4 intermetallic compound synthesized by the MFNN technique in both bulk and nanowire forms. The compound presents a complex base-centered monoclinic structure and exhibits an intricate magnetic behavior. At low magnetic fields, a ferromagnetic (FM) state develops below T1 = 50 K, while at higher temperatures, antiferromagnetism (AFM) takes place with a Néel temperature T2 = 390 K. This magnetic behavior has been explained by Moriya and Usami's theory that predicts coexistence of FM and AFM states in itinerant electron systems. In this regard, we report the dimensionality effects on the Fe3Ga4 magnetic phase diagram H-T, which was constructed for both bulk and nanowire systems using magnetization, specific heat and electrical resistivity measurements. The results are discussed in the framework of the Moriya and Usami's theory on magnetic phase transitions in itinerant-electron systems. We strongly believe that the possibility of growing intermetallic compounds in the nanowire form will open an interesting branch in the understanding of fundamental properties as well as to control the nanowire characteristics for a desired applications.
References:
[1] Pirota K. R., Béron F., Oliveira L. A. S. de, Moura K. O., Knobel M., Pagliuso P. G., Garifezi T. M., Jesus C. B. R. de, Rettori C., Adriano C., Rosa P. F. S., Urbano R. R., Iwamoto W. A., Arzuza L. C. C., Carvalho P. G. (2014). Processo de produção de nanofios monocristalinos intermetálicos. BR patent 10 2014 019794 0.
[2] Rosa P. F. S., Oliveira L. A. S. de, Jesus C. B. R. de, Moura K. O., Adriano C., Iwamoto W., Garizeti, T. M., Granado E., Saleta M. E., Pirota K. R. and Pagliuso P. G. (2014). Exploring the effects of dimensionality on the magnetic properties of intermetallic nanowires. Solid State Communications, 14.
[2] Rosa P. F. S., Oliveira L. A. S. de, Jesus C. B. R. de, Moura K. O., Adriano C., Iwamoto W., Garizeti, T. M., Granado E., Saleta M. E., Pirota K. R. and Pagliuso P. G. (2014). Exploring the effects of dimensionality on the magnetic properties of intermetallic nanowires. Solid State Communications, 14.
Magnetite nanoparticles with bulk-like properties
N. Pérez *1,2, A. Labarta 2 and X. Batlle 2
1 Institute for Metallic Materials, IFW-Dresden, Helmholtzstrasse 20, 01069 Dresden. 2 Dept. Física Fonamental and Insitut de Nanociència i Nanotecnología IN2UB, U. Barcelona, Martí i Franqués 1, 08028 Barcelona, Spain
Magnetic nanoparticles (NP) systems have long been subject to study finite-size and surface effects. The thermal decomposition of an organic iron precursor in an organic medium allows the preparation of highly crystalline iron oxide NP with excellent magnetic parameters in contrast with the co-precipitation method [1]. Saturation magnetization was size independent in the 5-20 nm range and almost reached the expected value for bulk magnetite at low temperatures, higher in those NP with oleic acid covalently bonded to the surface. In 5 nm particles the surface contribution to magnetic anisotropy could be established analytically using the Tln(t/t0) scaling, confirming that surface anisotropy causes the broadening of their energy barrier distribution [2]. X-ray absorption spectra suggested charge transfer from the NP to the covalent bonded surfactant. X-ray magnetic circular dichroism confirmed the dependence of the magnetic moment on the synthesis method, including surface bond, and suggested that the orbital momentum is more effectively quenched in covalently bonded NPs. The low-temperature <Sz> = 3.63 μB/f.u. obtained in the latter case, is very close to those reported for bulk samples (3.90-3.95 μB/f.u.). High resolution transmission electron microscopy combined with electron energy loss spectroscopy/electron magnetic chiral dichroism on individual nanoparticles confirmed that the foregoing is related to the crystal quality of the NP. Density functional theory calculations showed that the covalent bond at the particles’ surfaces would enhance the magnetization of the surface in an equivalent of 1 μB per surface unit cell [3]. Application of these high-magnetization magnetite nanoparticles enabled magnetic resonance imaging of brain and liver in mice, and easy quantification of the biodistribution with magnetization measurements [4]. Coating the particles with silica enabled to control their aggregation state. An optimum aggregation point was observed in NMR experiments, and it was accounted for in first approximation using a simple liner chain model.
Acknowledgements
MEC (NAN2004- 08805-CO4-02, NAN2004-08805-CO4-01, CONSOLIDER CSD2006-12, MAT2005–02454 and MAT2006-03999), Generalitat de Catalunya (2005SGR00969)
[1] X. Batlle et al., J. Appl. Phys. 109, 07B524 (2011)
[2] N. Pérez et al., Nanotechnology 19, 475704 (2008)
[3] J. Salafranca et al., Nano Lett. 12, 2499 (2012)
[4] R. Mejías et al., Nanomedicine 5, 397 (2010)
SPEAKERS
Design and Fabrication of a nanodevice for bio-sensor applications featuring Nano-Electromechanical Systems (NEMS)
M. A. García-Ramírez1, B. Cortese2, P. Navarro-Santos3 and R. Selvas-Aguilar4
1Facultad de Ingeniería Mecánica y Eléctrica. Universidad Autónoma de Nuevo León. San Nicolás de los Garza, Nuevo León, Mexico. 2Soft and Living matter lab Istituto di Nanotecnologia, CNR-Nanotec. Rome, Italia. 3CONACYT-Universidad Michoacana de San Nicolás de Hidalgo. Morelia. Mexico. 4Facultad de Ciencias Físico Matemáticas. Universidad Autónoma de Nuevo León. San Nicolás de los Garza, Nuevo León. Mexico.
In this paper we present a numerical analysis of a biosensor nano-structure. The nano- structure features the co-integration between the nano-electromechanical systems (NEMS) with the well known metal-oxide-semiconductor (MOS) technology. The hybrid structure uses a double-clamped functionalised beam that is doubly isolated from the readout element (MOSFET) by a thin oxide layer and an air-gap. A 3D finite element analysis is performed to study the behaviour of the pull-in/pull-out when short-range forces such as the Casimir and van der Waals forces are acting on the nano-device. The analysis is complemented with a preliminary fabrication process to feedback info into the numerical analysis.
Oxygen Adsorption on Boron-Nitride Nanoribbons Atomically Functionalized with Carbon
F. Villanueva Mejía1, R. Herrera-Bucio1, J. L. Rivera1, M. García Ramírez2, P. Navarro-Santos3
1Instituto de Investigaciones Químico Biológicas. Universidad Michoacana de San Nicolás de Hidalgo. Morelia, Mexico. 2Facultad de Ingeniería Química, Universidad Michoacana de San Nicolas de Hidalgo. Morelia, Mexico. 3Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León, México. 4CONACYT-Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mexico.
In this work, first principle calculations based on the density functional theory are employed to predict the oxygen adsorption on pristine and carbon doped boron nitride nanoribbons (BNNRs) with armchair topology. The physisorption and chemisorption states are found in the studied complexes and their binding energies as well as the charge density difference of the complexes are discussed. The C-doped BNNRs have very different O2 adsorption properties compared with the pristine BNNR. In order to characterize the surfaces, reactivity descriptors such as, the Molecular Electrostatic Potential and the Fukui functions are presented. Overall, these properties suggest that the C-doped BNNRs may be useful as a gas sensor or as a catalyst in the oxygen reduction reactions.
Characterization of blueberries compounds (Vegetables Dyes) removed by inorganic adsorbents based on potassium titanates
M. A. Aguilar González1, C. N. Aguilar2, E. Díaz Barriga3, A. A. Zaldívar-Cadena4
1Centro de Investigación y Estudios Avanzados del I.P.N (Unidad Saltillo), Saltillo-Ramos Arizpe, Coahuila, México. 2 Departamento de Ciencia y Tecnología en alimentos, Facultad de Ciencias Químicas, Universidad Autónoma de Coahuila, Saltillo, Coahuila, México. 3Centro de Investigación en Química Aplicada (CIQA), Saltillo, Coahuila, México.4Universidad Autónoma de Nuevo León, Av. Universidad s/n, Facultad de Ingeniería Civil, San Nicolás de los Garza, Nuevo León.
Blueberry organic compounds were removed by adsorbents based on potassium titanates (Potassium Tetratitanate – Potassium Hexatitanate). Inorganic-ceramic adsorbents were obtained by Lux flood processes (Molten Salts and Heat Treatment). The techniques of liquid chromatography in high resolution, chemical analysis, X-ray diffraction, transmission and scanning electron microscopy and Fourier transform infrared spectroscopy were used in order to investigate the nano-structural characterization of blueberries compounds. Blueberries extracts were obtained directly from aqueous solutions containing 30 g of fruit per each 100ml of ethanol.
Characterization of the solutions containing polyphenols was performed by FTIR spectroscopy and mass spectrometry. Some parameters were estimated based on the registered spectra as well as bond energy and type and mode of the bond.
The transmission and scanning electron microscopy (SEM) images showed some morphological aspects of the organic compounds. Ethanolic solutions in a mixture of water: ethanol = 10:1 were prepared. Polyphenols are known by having a wide range of biological and biotechnological effects as well as several features for functionalization.
The extract of fruits was used as a source of polyphenols (PF) and organic compounds. The amount of the incorporated polyphenols was estimated by UV–VIS measurements. The possible application could be as ion exchangers in solar cells and catalytic systems.
References:
[1] Zhu H, Zeng H, Subramanian V, Masarapu C, Hung K and Wei B, Anthocyanin-sensitized solar cells using carbon nanotube films as counter electrodes. Nanotechnology, 19, (2008) 465204 (5pp).
Effect of temperature in structural stability of hafnia (HFO2) and cerium doped hafnia (Ce-HFO2 ) by transmission electron microscopy
E. M. Saucedo-Salazar1, L.A. Cerda-García1, E. Mendoza-Mendoza1, E. Díaz Barriga-Castro1,
M.A. Ceniceros-Reyes1, R. Orsua-Gaona1,2
1 Centro de Investigación en Química Aplicada, Saltillo, Coahuila, México.
Hafnium oxide materials have a great field of applications such as catalyst supports and semiconductor devices among others. These are related to their physicochemical properties, and therefore to their structure.
References:
[1] S.Gálvez-Barboza, L.A. González, B.A. Puente-Urbina, E.M. Saucedo-Salazar, L.A. García Cerda. Preparation and Characterization of Ce-doped HfO2 nanoparticles. J.Alloys Comp, 643 (2015) S62–S66
[5] L. Pereira, P. Barquinha, E. Fortunato, R. Martins. Low temperature processed hafnium oxide: Structural and electrical properties. Materials Science in Semiconductor Processing 9 (2006) 1125–1132.
Superhydrophobic materials
for portland cement based products
Ismael Flores-Vivian1, Marina Kozhukhova2, Konstantin Sobolev2,
Michael Nosonovsky2
1Universidad Autónoma de Nuevo León, Nuevo León, Mexico.
2Civil and Environmental Engineering, University of Wisconsin-Milwaukee, Milwaukee, USA
Concrete is normally a hydrophilic material, which significantly reduces the durability of concrete structures and pavements, especially in areas exposed to harsh environments. One main factor leading to the early deterioration of concrete is related to the infiltration of water into the porous structure of the concrete matrix. This presentation will explain the developed of two technologies for enhancing concrete durability: a) an admixture for manufacturing concrete with internal hydrophobic and superhydrophobic properties and b) a superhydrophobic coating for concrete surfaces.
On the first approach, by incorporating a hydrophobic admixture within the concrete mix, water is restricted to enter the capillary voids and porous. Results demonstrate the improved durability in fiber reinforced cementitious materials by creating a 3-dimensional hydrophobization to reduce the water absorption and permeability as well as to improve the freeze–thaw performance by a hydrophobic air voids evenly distributed throughout the cementitious matrix. As a superhydrophobic coating, siloxane admixtures were applied to portland cement based surfaces rendering them hydrophobicity, superhydrophobicity and icephobicity. Characterization of the coating properties included the water contact angle (CA), roll-off angle, efflorescence resistance and ice adhesion. Results of coated surfaces demonstrated hydrophobic and superhydrophobic performance due to a hierarchical roughness, higher efflorescence resistance and low force of ice adhesion.
Industrial Synthesis and Characterization of Nanophotocatalysts Materials: Case Titania
Norma A Ramos-Delgado1, Miguel Á Gracia-Pinilla2, Ramalinga Viswanathan Mangalaraja3, Kevin O´Shea4, Dionysios D Dionysiou4
1Instituto Tecnológico de Nuevo León (Catedras Conacyt), 2Universidad Autónoma de Nuevo León, 3Universidad de Concepción, 4Florida International University, Cincinnati University.
Despite the recent synthesis and identification of a diverse set of new nanophotocatalysts that has exploded recently, titanium dioxide (TiO2) remains among the most promising photocatalysts because it is inexpensive, non-corrosive, environmentally friendly, and stable under a wide range of conditions. TiO2 has shown excellent promise for solar cell applications and for remediation of chemical pollutants and toxins. Over the past few decades, there has been a tremendous development of nanophotocatalysts for a variety of industrial applications (i.e. for water purification and reuse, disinfection of water matrices, air purification, deodorization, sterilization of soils). This paper details traditional and new industrial routes for the preparation of nanophotocatalysts and the characterization techniques used to understand the physical chemical properties of them, like surface area, ζ potential, crystal size, and phase crystallographic, morphology, and optical transparency. Finally we present some applications of the industrial nanophotocatalysts.
Nanometric Iron Oxides trough bacterial culture from water wells in Mexico
A. Gómez Treviño1, J. Silva Mendoza1, R. Mendoza-Reséndez2, C. Luna2, M. Cantú Cárdenas1 and X. Zárate Kalfópulos1
1Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León. Nuevo León, Mexico. 2Facultad de Ciencias Físico Matemáticas,
Iron oxides in nanometirc scale are more necessary every passing day because of a wide field of applications and their importance in development of new technologies and modern devices. Magnetic inks, mineral fluids for contrast in diagnostics, drug delivery systems and countless applications in communication procedures are just a few examples. In concert with the stocks of these compounds, cleaner processes and greener chemical synthesis methods are mandatory to attain [1, 2]. Some bacterial groups in nature are able to mineralize iron oxides as result of a cellular physical and chemical process known as biomineralization [3]. We have accomplished isolation of Gram (+) and Gram (-) bacteria growing in MSGM culture media (Magnetospirillum Growing Media) from water wells in Mexico. MET, X-ray diffraction and EDS analysis confirm the presence of Iron Oxide crystals with 20 nm (avg.) in size associated with bacterial cells.
References:
[1] Zanella. R., 2012.
[3] Pérez-González T., et al., 2004.
Classical plasmonics: wave propagation control at nanoscale
Eduardo Pisano1, Victor Coello2, Cesar E. Garcia-Ortiz2,3
1División de Física Aplicada, Centro de Investigación Científica y de Educación Superior de Ensenada, Carretera Ensenada-Tijuana No. 3918, Ensenada, BC 22860, Mexico. 2Unidad Monterrey, Centro de Investigación Científica y de Educación Superior de Ensenada, Alianza Centro 504, Apodaca, NL, 66629, Mexico. 3CONACYT – CICESE, Unidad Monterrey, Alianza Centro 504, Apodaca, NL, 66629, Mexico.
Since the loss compensation in propagating surface plasmon polaritons (SPP) is far from being a trivial problem, the search for novel plasmonic waveguide configurations, that might be better suited (than already developed ones) for particular applications, is still an open problem. In this work, leakage radiation microscopy is employed in the characterization of random nanostructure plasmonic channel waveguides, as well as on the study of light to SPP coupling under different excitation conditions. The characterized waveguides are composed of scattering free channels formed inside random arrays of gold nanostructures, located on a metallic thin film. The interaction between SPP and these random arrays, results in an inhibition of the SPP propagation due to multiple scattering inside the array, this allows a manipulation of its propagation by a confinement inside scatter free regions. This study covers the detailed determination of the SPP localization and scattering parameters inside the random arrays of nanostructures, the analysis of propagation losses and effective refractive index dispersion on straight channels, as well as the transmission and bending losses in S-bend and Y-splitter channels. We also report on the experimental study of effects in SPP excitation under oblique light incidence. Theoretical predictions suggest an improvement of light to SPP coupling efficiency under a highly oblique incidence of light on the coupling structure. For this reason, we determine the light to SPP coupling efficiency achieved under a variation of the incidence angle of excitation light over rectangular ridge nanostructures. Moreover, due to the nonexistence of a proper SPP propagation profile model that considers the excitation light features on the local SPP coupling, a fitting for the determination of the SPP beam propagation, through the characterization of the excitation and SPP beam relationship, is proposed.
Bi-dimensional measurement of dielectric constant of inhomogeneous thin metallic films using Kretschmann configuration
Rodolfo Cortés1, César García1 and Víctor Coello1
Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE). Unidad Monterrey, Alianza Sur No.105, Nueva Carretera Aeropuerto Km 9.5 Parque de Investigación e Innovación Tecnológica (PIIT), Apodaca, C. P. 66629, N. L. México
Optical constants of a thin film describe the manner in which an electromagnetic wave progresses through the material. Traditionally, they can be determined using polarimetric techniques. An excellent alternative is the Kretschmann geometry. The metal film is evaporated on top of a glass prism or transparent substrate. Photons from a laser beam (P-polarized) impinging from the glass side at an angle greater than the critical angle of total internal reflection, tunnel through the metal film and excite the natural frequency of metal surface electrons (surface plasmon polaritons) at the metal/air interface. The scattered light can be observed in the plane of incidence. In this work, we propose a technique based on the enhanced electric field intensity to determine the optical constants of inhomogeneous metallic thin films using Kretschmann geometry. Our experimental set up consists of a right angle prism with a thin metallic film, an image-forming optical system, and a CCD camera (1024x768 pixels). An image is produced for each angle of incidence. Plots of the enhanced field intensity versus angle of incidence are obtained and fitted using the transfer-matrix method. The film optical properties are calculated for each pixel, obtaining a bidimensionally map of the optical constants. This technique can be used as a method to evaluate the quality of the thin film after post processing.
Fine tunning of the opto-electronical properties of AZO thin-films and
experimental characterization of plasmonic response
Ana Lizbeth Villarreal Ríos1, Víctor Coello1, Ricardo Rangel Segura1,
Manuel García Mendez1
1Facultad de Ciencias Físico
Matemáticas. Universidad Autónoma de Nuevo León. San Nicolás de los Garza,
Nuevo León. Mexico
In this work,
we will show some recent results about how to adjusting depositions conditions,
by using reactive magnetron-sputtering RF technique, become possible the fine
tunning of the plasmon frecuency resonance at the THz frequencies, near to 1.5 mm, which makes
aluminium-doped zinc oxide films (AZO) a very promising material to be used in
plasmonic applications. Experimental results such as UV-Vis-IR spectroscopy,
XPS as well as optical models to obtain optoelectronical parameters of films,
will be presented.
Less-common
carbon nanostructures: Nanobuds and nanotori
Oxana
Kharissova 1, Patsy
Arquieta 1, Boris Kharisov 2
Synthesis, properties, structural peculiarities, and applications of
nanobuds and related nanostructures are discussed. Such carbon allotropes as
carbon nanotubes (CNTs) and fullerenes (Fs) are known from the last decades of
XX century, but their combination, called “nanobuds” (NBs) and possessing
unique properties superior to CNTs and Fs alone, were discovered relatively
recently. This structure seems like fusion of a cylinder with a sphere; there
is a covalent bond between outer sidewalls of the nanotube and the fullerene.
In this material, fullerenes are covalently bonded to the outer sidewalls of
the underlying nanotube. NBs exhibit properties of both carbon nanotubes and
fullerenes. According to observed properties and those predicted by DFT
calculations, the nanobuds are semiconducting and stable in normal conditions,
can accept atoms and molecules. They contain a relatively chemically inert
carbon nanotubes and more active fullerene species and can be compatible with a
variety of other materials, in particular polymers. In addition to nanobuds for
SWCNTs, the nanobuds with graphene, small fullerenes or metal nanobud-like
structures are also known. Nanotori
cyclic structures are also discussed.
Numerical Approximation of a High-Speed
Si-based Opto-Electronic Modulator by using a Mach-Zehnder Interferometer
M. A. García-Ramírez1, M. A. Gurrola-Navarro2, C. A.
Bonilla-Barragán2, P. Navarro-Santos3 and R.
Selvas-Aguilar4
1Facultad de Ingeniería Mecánica y
Eléctrica. Universidad Autónoma de Nuevo León. San Nicolás de los
Garza, Nuevo León, Mexico. 2Centro
Universitario de Ciencias Exactas e Ingenieras, Universidad de Guadalajara,
Guadalajara, Jalisco, Mexico, 3CONACYT-Universidad
Michoacana de San Nicolás de Hidalgo. Morelia. Mexico. 4Facultad
de Ciencias Físico Matemáticas. Universidad Autónoma de Nuevo León, Nuevo
León, Mexico.
An electro-optic modulator based on a
Mach-Zehnder Interferometer is numerically analyzed. The modulator features a
coplanar waveguide Si-based that confines charge carriers as well as the
optical beam. The analysis is performed through the finite element method that
allows to analyze the electric field distribution as well as the distribution
along the coplanar waveguide. The numerical analysis is based on the
Kramers-Kronig dispersion relations. As a result of the analysis, it was found
that by using a Si-based coplanar waveguide doped 1019, we can
control the phase by a range from 0 up to π while 10 V are applied at a
wavelegnth of 1550 nm.
Functionalization
of carbon nanotubes by green-chemistry
Beatriz
Ortega1, Oxana
Kharissova1, Servando Aguirre T.2
1Universidad
Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas. 2CIMAV-Monterrey
In this work, nanoforests of multiwall carbon nanotubes (MWCNTs) were
functionalized using two different methods.
The first method is usually some aggressive treatment, e.g. (i)
oxidation in refluxing conc. HNO3 (yields carboxyl groups).This method is
impossible for biological application. We study applicate of Lupyrox, how green
methods for obtained COOH- groups. Characterization was made by Raman
spectroscopy, Transmission Electron Microscopy (TEM), among other methods; the
antibacterial property was measured using method of dilution and plating. The
presence of the carboxyl groups was proved by FT-IR measurements. The formed nanocomposites
could be used as water-purifying materials in water filters.
Design and Fabrication of a nanodevice for bio-sensor applications featuring Nano-Electromechanical Systems (NEMS)
M. A. García-Ramírez1, B. Cortese2, P. Navarro-Santos3 and R. Selvas-Aguilar4
1Facultad de Ingeniería Mecánica y Eléctrica. Universidad Autónoma de Nuevo León. San Nicolás de los Garza, Nuevo León, Mexico. 2Soft and Living matter lab Istituto di Nanotecnologia, CNR-Nanotec. Rome, Italia. 3CONACYT-Universidad Michoacana de San Nicolás de Hidalgo. Morelia. Mexico. 4Facultad de Ciencias Físico Matemáticas. Universidad Autónoma de Nuevo León. San Nicolás de los Garza, Nuevo León. Mexico.
In this paper we present a numerical analysis of a biosensor nano-structure. The nano- structure features the co-integration between the nano-electromechanical systems (NEMS) with the well known metal-oxide-semiconductor (MOS) technology. The hybrid structure uses a double-clamped functionalised beam that is doubly isolated from the readout element (MOSFET) by a thin oxide layer and an air-gap. A 3D finite element analysis is performed to study the behaviour of the pull-in/pull-out when short-range forces such as the Casimir and van der Waals forces are acting on the nano-device. The analysis is complemented with a preliminary fabrication process to feedback info into the numerical analysis.
Oxygen Adsorption on Boron-Nitride Nanoribbons Atomically Functionalized with Carbon
F. Villanueva Mejía1, R. Herrera-Bucio1, J. L. Rivera1, M. García Ramírez2, P. Navarro-Santos3
1Instituto de Investigaciones Químico Biológicas. Universidad Michoacana de San Nicolás de Hidalgo. Morelia, Mexico. 2Facultad de Ingeniería Química, Universidad Michoacana de San Nicolas de Hidalgo. Morelia, Mexico. 3Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León, México. 4CONACYT-Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mexico.
In this work, first principle calculations based on the density functional theory are employed to predict the oxygen adsorption on pristine and carbon doped boron nitride nanoribbons (BNNRs) with armchair topology. The physisorption and chemisorption states are found in the studied complexes and their binding energies as well as the charge density difference of the complexes are discussed. The C-doped BNNRs have very different O2 adsorption properties compared with the pristine BNNR. In order to characterize the surfaces, reactivity descriptors such as, the Molecular Electrostatic Potential and the Fukui functions are presented. Overall, these properties suggest that the C-doped BNNRs may be useful as a gas sensor or as a catalyst in the oxygen reduction reactions.
Characterization of blueberries compounds (Vegetables Dyes) removed by inorganic adsorbents based on potassium titanates
M. A. Aguilar González1, C. N. Aguilar2, E. Díaz Barriga3, A. A. Zaldívar-Cadena4
1Centro de Investigación y Estudios Avanzados del I.P.N (Unidad Saltillo), Saltillo-Ramos Arizpe, Coahuila, México. 2 Departamento de Ciencia y Tecnología en alimentos, Facultad de Ciencias Químicas, Universidad Autónoma de Coahuila, Saltillo, Coahuila, México. 3Centro de Investigación en Química Aplicada (CIQA), Saltillo, Coahuila, México.4Universidad Autónoma de Nuevo León, Av. Universidad s/n, Facultad de Ingeniería Civil, San Nicolás de los Garza, Nuevo León.
Blueberry organic compounds were removed by adsorbents based on potassium titanates (Potassium Tetratitanate – Potassium Hexatitanate). Inorganic-ceramic adsorbents were obtained by Lux flood processes (Molten Salts and Heat Treatment). The techniques of liquid chromatography in high resolution, chemical analysis, X-ray diffraction, transmission and scanning electron microscopy and Fourier transform infrared spectroscopy were used in order to investigate the nano-structural characterization of blueberries compounds. Blueberries extracts were obtained directly from aqueous solutions containing 30 g of fruit per each 100ml of ethanol.
Characterization of the solutions containing polyphenols was performed by FTIR spectroscopy and mass spectrometry. Some parameters were estimated based on the registered spectra as well as bond energy and type and mode of the bond.
The transmission and scanning electron microscopy (SEM) images showed some morphological aspects of the organic compounds. Ethanolic solutions in a mixture of water: ethanol = 10:1 were prepared. Polyphenols are known by having a wide range of biological and biotechnological effects as well as several features for functionalization.
The extract of fruits was used as a source of polyphenols (PF) and organic compounds. The amount of the incorporated polyphenols was estimated by UV–VIS measurements. The possible application could be as ion exchangers in solar cells and catalytic systems.
References:
[1] Zhu H, Zeng H, Subramanian V, Masarapu C, Hung K and Wei B, Anthocyanin-sensitized solar cells using carbon nanotube films as counter electrodes. Nanotechnology, 19, (2008) 465204 (5pp).
[1] Zhu H, Zeng H, Subramanian V, Masarapu C, Hung K and Wei B, Anthocyanin-sensitized solar cells using carbon nanotube films as counter electrodes. Nanotechnology, 19, (2008) 465204 (5pp).
[2] Park N. G, Perovskite solar cells: an emerging photovoltaic technology, Materials Today, 18, 2, (2015).
[3] Lee J. W , Son D. Y , Ahn T. K, Shin H. W , Kim I. Y, Hwang S. J, Ko M.J, Sul S, Han H and Park N.G, Quantum-Dot-Sensitized Solar Cell with Unprecedentedly High Photocurrent, Scientific Reports 3, (2013) 1-8.
Effect of temperature in structural stability of hafnia (HFO2) and cerium doped hafnia (Ce-HFO2 ) by transmission electron microscopy
E. M. Saucedo-Salazar1, L.A. Cerda-García1, E. Mendoza-Mendoza1, E. Díaz Barriga-Castro1,
M.A. Ceniceros-Reyes1, R. Orsua-Gaona1,2
M.A. Ceniceros-Reyes1, R. Orsua-Gaona1,2
1 Centro de Investigación en Química Aplicada, Saltillo, Coahuila, México.
2 Instituto Tecnológico de Saltillo, Tecnológico, Saltillo, Coahuila, México.
The effect of temperature on structural evolution of pure hafnia (HFO2) and Cerium doped hafnia (Ce-HFO2) was studied by electron diffraction at high temperatures (up to 1000°C) using a MEMS based system of in situ heating transmission electron microscopy. These materials were prepared by a modified sol-gel method. At room temperature Ce-HFO2 shows a cubic structure, while pure HFO2 has a monoclinic structure. High resolution images and diffraction patterns were used to evaluate the structure and morphology transformation of these materials as a function of heating kinetics.
References:
[1] S.Gálvez-Barboza, L.A. González, B.A. Puente-Urbina, E.M. Saucedo-Salazar, L.A. García Cerda. Preparation and Characterization of Ce-doped HfO2 nanoparticles. J.Alloys Comp, 643 (2015) S62–S66
[1] S.Gálvez-Barboza, L.A. González, B.A. Puente-Urbina, E.M. Saucedo-Salazar, L.A. García Cerda. Preparation and Characterization of Ce-doped HfO2 nanoparticles. J.Alloys Comp, 643 (2015) S62–S66
[2] H.Saka, T. Kamino, S. Arai, K. Sasaki. In situ heating transmission electron mmicroscopy. MRS Bull, 2008, Vol 33 93-100
[3] Z.L.Wang. Transmission electron microscopy of shape-controlled nanocrystals and their assemblies. J.Phys. Chem B, 2000, 104, 1153-1175.
[4] N.Petkov. In situ Real time TEM reveals growth transformation and function in one-dimiensional nanostructured materials: from a nanotechonology perspective. ISRN Nanotechnology, 2013. Art ID. 893060
[5] L. Pereira, P. Barquinha, E. Fortunato, R. Martins. Low temperature processed hafnium oxide: Structural and electrical properties. Materials Science in Semiconductor Processing 9 (2006) 1125–1132.
[5] L. Pereira, P. Barquinha, E. Fortunato, R. Martins. Low temperature processed hafnium oxide: Structural and electrical properties. Materials Science in Semiconductor Processing 9 (2006) 1125–1132.
Superhydrophobic materials
for portland cement based products
Ismael Flores-Vivian1, Marina Kozhukhova2, Konstantin Sobolev2,
Michael Nosonovsky2
1Universidad Autónoma de Nuevo León, Nuevo León, Mexico.
2Civil and Environmental Engineering, University of Wisconsin-Milwaukee, Milwaukee, USA
2Civil and Environmental Engineering, University of Wisconsin-Milwaukee, Milwaukee, USA
Concrete is normally a hydrophilic material, which significantly reduces the durability of concrete structures and pavements, especially in areas exposed to harsh environments. One main factor leading to the early deterioration of concrete is related to the infiltration of water into the porous structure of the concrete matrix. This presentation will explain the developed of two technologies for enhancing concrete durability: a) an admixture for manufacturing concrete with internal hydrophobic and superhydrophobic properties and b) a superhydrophobic coating for concrete surfaces.
On the first approach, by incorporating a hydrophobic admixture within the concrete mix, water is restricted to enter the capillary voids and porous. Results demonstrate the improved durability in fiber reinforced cementitious materials by creating a 3-dimensional hydrophobization to reduce the water absorption and permeability as well as to improve the freeze–thaw performance by a hydrophobic air voids evenly distributed throughout the cementitious matrix. As a superhydrophobic coating, siloxane admixtures were applied to portland cement based surfaces rendering them hydrophobicity, superhydrophobicity and icephobicity. Characterization of the coating properties included the water contact angle (CA), roll-off angle, efflorescence resistance and ice adhesion. Results of coated surfaces demonstrated hydrophobic and superhydrophobic performance due to a hierarchical roughness, higher efflorescence resistance and low force of ice adhesion.
Industrial Synthesis and Characterization of Nanophotocatalysts Materials: Case Titania
Norma A Ramos-Delgado1, Miguel Á Gracia-Pinilla2, Ramalinga Viswanathan Mangalaraja3, Kevin O´Shea4, Dionysios D Dionysiou4
1Instituto Tecnológico de Nuevo León (Catedras Conacyt), 2Universidad Autónoma de Nuevo León, 3Universidad de Concepción, 4Florida International University, Cincinnati University.
Despite the recent synthesis and identification of a diverse set of new nanophotocatalysts that has exploded recently, titanium dioxide (TiO2) remains among the most promising photocatalysts because it is inexpensive, non-corrosive, environmentally friendly, and stable under a wide range of conditions. TiO2 has shown excellent promise for solar cell applications and for remediation of chemical pollutants and toxins. Over the past few decades, there has been a tremendous development of nanophotocatalysts for a variety of industrial applications (i.e. for water purification and reuse, disinfection of water matrices, air purification, deodorization, sterilization of soils). This paper details traditional and new industrial routes for the preparation of nanophotocatalysts and the characterization techniques used to understand the physical chemical properties of them, like surface area, ζ potential, crystal size, and phase crystallographic, morphology, and optical transparency. Finally we present some applications of the industrial nanophotocatalysts.
Nanometric Iron Oxides trough bacterial culture from water wells in Mexico
A. Gómez Treviño1, J. Silva Mendoza1, R. Mendoza-Reséndez2, C. Luna2, M. Cantú Cárdenas1 and X. Zárate Kalfópulos1
1Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León. Nuevo León, Mexico. 2Facultad de Ciencias Físico Matemáticas,
Iron oxides in nanometirc scale are more necessary every passing day because of a wide field of applications and their importance in development of new technologies and modern devices. Magnetic inks, mineral fluids for contrast in diagnostics, drug delivery systems and countless applications in communication procedures are just a few examples. In concert with the stocks of these compounds, cleaner processes and greener chemical synthesis methods are mandatory to attain [1, 2]. Some bacterial groups in nature are able to mineralize iron oxides as result of a cellular physical and chemical process known as biomineralization [3]. We have accomplished isolation of Gram (+) and Gram (-) bacteria growing in MSGM culture media (Magnetospirillum Growing Media) from water wells in Mexico. MET, X-ray diffraction and EDS analysis confirm the presence of Iron Oxide crystals with 20 nm (avg.) in size associated with bacterial cells.
References:
[1] Zanella. R., 2012.
[2] Mazo-Zuluaga, 2011
[3] Pérez-González T., et al., 2004.
[3] Pérez-González T., et al., 2004.
Classical plasmonics: wave propagation control at nanoscale
Eduardo Pisano1, Victor Coello2, Cesar E. Garcia-Ortiz2,3
1División de Física Aplicada, Centro de Investigación Científica y de Educación Superior de Ensenada, Carretera Ensenada-Tijuana No. 3918, Ensenada, BC 22860, Mexico. 2Unidad Monterrey, Centro de Investigación Científica y de Educación Superior de Ensenada, Alianza Centro 504, Apodaca, NL, 66629, Mexico. 3CONACYT – CICESE, Unidad Monterrey, Alianza Centro 504, Apodaca, NL, 66629, Mexico.
Since the loss compensation in propagating surface plasmon polaritons (SPP) is far from being a trivial problem, the search for novel plasmonic waveguide configurations, that might be better suited (than already developed ones) for particular applications, is still an open problem. In this work, leakage radiation microscopy is employed in the characterization of random nanostructure plasmonic channel waveguides, as well as on the study of light to SPP coupling under different excitation conditions. The characterized waveguides are composed of scattering free channels formed inside random arrays of gold nanostructures, located on a metallic thin film. The interaction between SPP and these random arrays, results in an inhibition of the SPP propagation due to multiple scattering inside the array, this allows a manipulation of its propagation by a confinement inside scatter free regions. This study covers the detailed determination of the SPP localization and scattering parameters inside the random arrays of nanostructures, the analysis of propagation losses and effective refractive index dispersion on straight channels, as well as the transmission and bending losses in S-bend and Y-splitter channels. We also report on the experimental study of effects in SPP excitation under oblique light incidence. Theoretical predictions suggest an improvement of light to SPP coupling efficiency under a highly oblique incidence of light on the coupling structure. For this reason, we determine the light to SPP coupling efficiency achieved under a variation of the incidence angle of excitation light over rectangular ridge nanostructures. Moreover, due to the nonexistence of a proper SPP propagation profile model that considers the excitation light features on the local SPP coupling, a fitting for the determination of the SPP beam propagation, through the characterization of the excitation and SPP beam relationship, is proposed.
Bi-dimensional measurement of dielectric constant of inhomogeneous thin metallic films using Kretschmann configuration
Rodolfo Cortés1, César García1 and Víctor Coello1
Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE). Unidad Monterrey, Alianza Sur No.105, Nueva Carretera Aeropuerto Km 9.5 Parque de Investigación e Innovación Tecnológica (PIIT), Apodaca, C. P. 66629, N. L. México
Optical constants of a thin film describe the manner in which an electromagnetic wave progresses through the material. Traditionally, they can be determined using polarimetric techniques. An excellent alternative is the Kretschmann geometry. The metal film is evaporated on top of a glass prism or transparent substrate. Photons from a laser beam (P-polarized) impinging from the glass side at an angle greater than the critical angle of total internal reflection, tunnel through the metal film and excite the natural frequency of metal surface electrons (surface plasmon polaritons) at the metal/air interface. The scattered light can be observed in the plane of incidence. In this work, we propose a technique based on the enhanced electric field intensity to determine the optical constants of inhomogeneous metallic thin films using Kretschmann geometry. Our experimental set up consists of a right angle prism with a thin metallic film, an image-forming optical system, and a CCD camera (1024x768 pixels). An image is produced for each angle of incidence. Plots of the enhanced field intensity versus angle of incidence are obtained and fitted using the transfer-matrix method. The film optical properties are calculated for each pixel, obtaining a bidimensionally map of the optical constants. This technique can be used as a method to evaluate the quality of the thin film after post processing.
Fine tunning of the opto-electronical properties of AZO thin-films and
experimental characterization of plasmonic response
Ana Lizbeth Villarreal Ríos1, Víctor Coello1, Ricardo Rangel Segura1,
Manuel García Mendez1
1Facultad de Ciencias Físico
Matemáticas. Universidad Autónoma de Nuevo León. San Nicolás de los Garza,
Nuevo León. Mexico
Less-common
carbon nanostructures: Nanobuds and nanotori
Oxana
Kharissova 1, Patsy
Arquieta 1, Boris Kharisov 2
1Universidad Autónoma de Nuevo León, Facultad de
Ciencias Físico-Matemáticas. 2 Universidad Autónoma de Nuevo León,
Facultad de Ciencias Físico-Químicas
Synthesis, properties, structural peculiarities, and applications of
nanobuds and related nanostructures are discussed. Such carbon allotropes as
carbon nanotubes (CNTs) and fullerenes (Fs) are known from the last decades of
XX century, but their combination, called “nanobuds” (NBs) and possessing
unique properties superior to CNTs and Fs alone, were discovered relatively
recently. This structure seems like fusion of a cylinder with a sphere; there
is a covalent bond between outer sidewalls of the nanotube and the fullerene.
In this material, fullerenes are covalently bonded to the outer sidewalls of
the underlying nanotube. NBs exhibit properties of both carbon nanotubes and
fullerenes. According to observed properties and those predicted by DFT
calculations, the nanobuds are semiconducting and stable in normal conditions,
can accept atoms and molecules. They contain a relatively chemically inert
carbon nanotubes and more active fullerene species and can be compatible with a
variety of other materials, in particular polymers. In addition to nanobuds for
SWCNTs, the nanobuds with graphene, small fullerenes or metal nanobud-like
structures are also known. Nanotori
cyclic structures are also discussed.
Numerical Approximation of a High-Speed
Si-based Opto-Electronic Modulator by using a Mach-Zehnder Interferometer
M. A. García-Ramírez1, M. A. Gurrola-Navarro2, C. A.
Bonilla-Barragán2, P. Navarro-Santos3 and R.
Selvas-Aguilar4
1Facultad de Ingeniería Mecánica y
Eléctrica. Universidad Autónoma de Nuevo León. San Nicolás de los
Garza, Nuevo León, Mexico. 2Centro
Universitario de Ciencias Exactas e Ingenieras, Universidad de Guadalajara,
Guadalajara, Jalisco, Mexico, 3CONACYT-Universidad
Michoacana de San Nicolás de Hidalgo. Morelia. Mexico. 4Facultad
de Ciencias Físico Matemáticas. Universidad Autónoma de Nuevo León, Nuevo
León, Mexico.
An electro-optic modulator based on a
Mach-Zehnder Interferometer is numerically analyzed. The modulator features a
coplanar waveguide Si-based that confines charge carriers as well as the
optical beam. The analysis is performed through the finite element method that
allows to analyze the electric field distribution as well as the distribution
along the coplanar waveguide. The numerical analysis is based on the
Kramers-Kronig dispersion relations. As a result of the analysis, it was found
that by using a Si-based coplanar waveguide doped 1019, we can
control the phase by a range from 0 up to π while 10 V are applied at a
wavelegnth of 1550 nm.
Functionalization
of carbon nanotubes by green-chemistry
Beatriz
Ortega1, Oxana
Kharissova1, Servando Aguirre T.2
1Universidad
Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas. 2CIMAV-Monterrey
In this work, nanoforests of multiwall carbon nanotubes (MWCNTs) were
functionalized using two different methods.
The first method is usually some aggressive treatment, e.g. (i)
oxidation in refluxing conc. HNO3 (yields carboxyl groups).This method is
impossible for biological application. We study applicate of Lupyrox, how green
methods for obtained COOH- groups. Characterization was made by Raman
spectroscopy, Transmission Electron Microscopy (TEM), among other methods; the
antibacterial property was measured using method of dilution and plating. The
presence of the carboxyl groups was proved by FT-IR measurements. The formed nanocomposites
could be used as water-purifying materials in water filters.
Synthesis of Nylon-6/graphene composites by
microwave-assisted polymerization and effect of plasma treatment on their electrical
properties
M. Navarro Rosales1, M. G.
Neira Velázquez1, C. A. Ávila Orta1, G. Soria Agüello1,
M.G. Olayo González1, G. Cruz Cruz1, P. González Morones1,
E. Hernández1, E. Hernández1, J.A. Valdez-Garza1.
1Centro de Investigación en Química Aplicada, Saltillo, Coahuila, México.Boulevard Enrique Reyna Hermosillo No. 140
In the present work we synthesized Nylon-6/graphene composites (NyGO) by
microwave polymerization of ɛ–caprolactam, 6 aminocaproic acid and graphite
oxide powder (GO). Graphite oxide was synthesized by the Hummers method using
graphite powder. Microwave energy can produce the reduction and exfoliation of
GO followed by the polymerization of monomers. The exfoliation process can
generated the homogeneous dispersion of graphene on the polymerization reaction
process resulting in homogeneous composites of Nylon (NyGO) and enhanced their electrical
conductivity. Subsequently, the composites were treated
with hydrogen peroxide and air plasma in order to etch their surfaces and improve
their electrical properties. Samples were characterized by
thermogravimetrical analysis (TGA), X-ray diffraction (XRD), infrared analysis
(FTIR), transmission electron microscopy (TEM) and the electrical conductivity
of nanocomposites were calculated from resistivity. FTIR and XRD analysis
confirmed the Nylon-6 production and the reduction of graphite oxide. Results
of this work showed that microwave-assisted polymerization is a fast and
environmental friendly process to prepare electrically conductive
nanocomposites.
POSTER PRESENTATIONS
Confinement and Surface Effects on the Physical Properties
of Rhombohedral-Shape Hematite (a-Fe2O3) Nanocrystals
Aída D. Cuan-Guerra1, Enrique D. Barriga-Castro2, Nuria O. Núñez3, Raquel Mendoza-Reséndez1, Carlos Luna1.
1Universidad Autónoma de Nuevo León. San Nicolás de los Garza, Nuevo León, Mexico. 2Centro de Investigación en Química Aplicada. Saltillo, Coahuila, Mexico. 3 Instituto de Ciencia de Materiales de Sevilla, CSIC-US. Isla de la Cartuja, Sevilla, Spain.
Morphological, microstructural and vibrational properties of hematite (a-Fe2O3) nanocrystals with a rhombohedral shape and rounded edges, obtained by forced hydrolysis of iron(III) solutions under a fast nucleation, have been investigated in detail as a function of aging time. These studies allowed us to propose a detailed formation mechanism and revealed that these nanocrystals are composed of four {104} side facets, two {110} faces at the edges of the long diagonal of the nanocrystals and two {-441} facets as the top and bottom faces. Also, the presence of nanoscopic pores and fissures was evidenced. The vibrational bands of such nanocrystals were shifted to lower frequencies in comparison with bulk hematite ones as the nanocrystal size was reduced due to phonon confinement effects. Also, the indirect and direct transition band gaps displayed interesting dependences on the aging time arising from quantum confinement and surface effect.
Evaluation of Delivery and Encapsulation System of Vincristine Sulphate Gold Nanoparticles/Chitosan Conjugates
Edelin Posada Briceño1, Diana Ginette Zárate Triviño1, Moises Ármides Franco Molina1, Cristina Rodríguez Padilla1
1Laboratorio de Inmunología y virología. Facultad de Ciencias Biológicas.
Universidad Autónoma de Nuevo León. San Nicolás de los Garza, Nuevo León, Mexico.
Constant resistance, short half-live and side effects are the main problems of anticancer treatments, on the current search for alternative treatments to decrease these obstacles, nanotechnology came up as a possible solution [1].
Nanostructures such as liposomes, dendrimers and nanoparticles [2] have been used in the pharmaceutic industry for cover and delivery drugs searching to improve pharmacodynamic and pharmacokinetic properties[3]. The aim of this work is to create a vincristine sulphate (Vc) delivery system blend metallic and polymeric nanoparticles for obtain a hybrid nanoparticle based on conjugates of drug-gold nanoparticle coated with chitosan (QTS).
Gold nanoparticles (AuNPs) were synthesized by Tukevich modificated method using chitosan as reductor agent and were characterized the size, surface charge, resonance plasmon by light dynamic scattering (DLS), Z potential and UV-visible spectroscopy. The size average of AuNPs were 3 to 5 nm with a Z potential of 16.4 mV and a maximum absorption at 519-522 nm of wavelength. The conjugate of Vc and gold nanoparticles was coated by ionic gelation using chitosan with sodium tripolyphosphate (TPP), and evaluated by DLS, UV-vis and fourier transform infrared (FT-IR) spectroscopy. A calibration curve was made to evaluate the release of Vc by UV-vis spectroscopy resulting in a 0.99 R2, with a sensibility from 0.1 to 0.0099 mg/ml.
Two systems were evaluated as treatments: Gold nanoparticles and vincristine complex (CVcAu) and gold nanoparticles and vincristine coated with chitosan (CVcAu-QTS) were culture with hepatocarcinoma Hep G2 and lymphoma L5178Y-R cells, preliminary results showed that conjugates were more effectivity than Vc and gold nanoparticles at same concentrations at 24 hours.
References:
[1] Mohanraj VJ and Chen Y (2006) Nanoparticles: a review, Trop J Pharm Res, 5(1):561-573. http://www.tjpr.freehosting.net.
[2] Yah CS, Simate G and Sunny I (2012) Nanoparticles toxicity and their routes of exposures, Pak. J. Pharm. Sci., 25(2):477-491.
[3] Manmode SA, Sakarkar M and Mahajan M (2009) Nanoparticles-tremendous therapeutic potential: a review, International Journal of PharmTech Research 1(4):1020-1027.
Cytotoxic effect of gold nanoparticles coated with chitosan evaluated in cell line of mouse lymphoma L5178Y-R “in vitro” and a murine model “in vivo”
Gonzalo Del Bosque Pérez1, Diana Ginette Zárate Triviño1, Ana Carolina Martínez Torres1, Cristina Rodríguez Padilla1
1Laboratorio de Inmunología y virología. Facultad de Ciencias Biológicas.
Universidad Autónoma de Nuevo León. San Nicolás de los Garza, Nuevo León, Mexico.
The mayor disadvantage of current cancer treatments is the collateral effects and in some cases low efficacy [1], for this reason is necessary to study new alternative of antineoplastic agents. Gold nanoparticles are capable of generate cytotoxicity in several cancer cell lines [2]. Also, they can be synthesized using natural polymers like chitosan which is biocompatible and has properties of inmunoestimulation and antitumoral activity [3].
The aim of this project was to synthetize and characterize gold nanoparticles coated with chitosan for evaluate their cytotoxic effect in the cell line L5178Y-R using in vitro and in vivo assays. For characterization was used light dynamic scattering (LDS), scanning electron microscopy (SEM), spectrophotometry ultraviolet-visible (UV-vis). The cytotoxic effect in vitro was made by flow citometry after 24 hours with annexin/PI. A solid tumor was induced in BALB/C mice for the evaluation of the in vivo effect and was measured the tumor volume and survival rate to determinate the efficacy of treatments.
Gold nanoparticles size was between 3 and 7nm with an average of 3.6 nm and a plasmon resonance of 531 nm which is characteristic of nanometric gold. In the in vitro assay, we observed a significant cytotoxic effect in concentrations above 30 µM. And in vivo, the group of mice treated with 6.2 mg/kg of gold nanoparticles show 20% less tumor volume (similar to the positive control Vincristine), the treatment of AuNP’s and vincristine together showed 31.68% less tumor volume compared with the group without treatment. These 3 groups show an increase in the survival rate.
In conclusion, gold nanoparticles coated with chitosan show a significant cytotoxic effect in a dose-depend manner in vitro, and in vivo a reduction of tumor volume with an increase of survival rate.
[1] Groopman JE, Itri LM (Oct 1999). "Chemotherapy-induced anemia in adults: incidence and treatment".Journal of the National Cancer Institute 91 (19): 1616–34
External Application of Silicon-Based Nanoparticles During the Curing Process
in Hardened Portland Cement-Based Materials
D. Cruz-Moreno1, G. Fajardo1, I. Flores-Vivian1, A. Cruz-López1, P. Valdez1
1Facultad de Ingeniería Civil, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, Mexico.
Corrosion of steel reinforcement is one of the main problems that beset the reinforced concrete structures (RCS) because of the porous nature of the hydrated portland cement products. Therefore, this paper studies the use of silicon-based nanoparticles (SBN) applied during the external curing and its microestructural effects in the treated samples. Portland cement-based mortar specimens were treated at an early age with SBN by two different methods: a) sprinkling SBN or b) by a film of SBN with thickness 20mm. The effect of the treatment was characterized from assaying electrical resistivity, N2 physisorption, SEM-EDS and accelerated tests carbonation and chlorides. Results demonstrated a reduction of CO2 penetration and Cl- levels up to 95% over the reference improving microstructural properties. Results regarding electrical resistivity, N2 physisorption, SEM-EDS is observed a decrease in the permeability in mortars, therefore prevents the passage to aggressive agents present in the medium. As a result, the application of SBN can improve external curing process and increase its durability and slow the corrosion process in the RCS.
Reversible self-assembly of thiol-stabilized gold nanocrystals into supremolecular face-centered cubic supercrystals: microstructural and plasmonic studies
Diana Castañeda-Rodríguez,1 Enrique Díaz Barriga-Castro,2 Nuria O. Núñez,3 Raquel Mendoza-Reséndez1, Carlos Luna1
1Universidad Autónoma de Nuevo León. San Nicolás de los Garza, Nuevo León, Mexico. 2Centro de Investigación en Química Aplicada. Saltillo, Coahuila, Mexico. 3 Instituto de Ciencia de Materiales de Sevilla, CSIC-US. Isla de la Cartuja, Sevilla, Spain.
The synthesis of gold nanoparticles into the reverse micelles of didodecyldimethylammonium bromide (DDAB) has been revisited, finding synthetic conditions that yield to the direct formation of very uniform gold flattened nanocrystals (AuNCs) with lower polydispersity degree than samples obtained by this method in previous works. Such AuNCs are also homogeneous in their exposed crystalline faces, composed of six side facets (four {111} faces and two {002} faces) and two {110} facets as the top and bottom faces. In addition, the spontaneous aggregation of these AuNCs into supramolecular structures with compacted packing, induced by the functionalization of the AuNCs with thiols, has been investigated. This self-organization process was reversible under heating treatments. This fact allowed us to examine the dependence of the plasmonic properties of AuNCs on their aggregation state under controlled conditions.
1Centro de Investigación en Química Aplicada, Saltillo, Coahuila, México.Boulevard Enrique Reyna Hermosillo No. 140
In the present work we synthesized Nylon-6/graphene composites (NyGO) by
microwave polymerization of ɛ–caprolactam, 6 aminocaproic acid and graphite
oxide powder (GO). Graphite oxide was synthesized by the Hummers method using
graphite powder. Microwave energy can produce the reduction and exfoliation of
GO followed by the polymerization of monomers. The exfoliation process can
generated the homogeneous dispersion of graphene on the polymerization reaction
process resulting in homogeneous composites of Nylon (NyGO) and enhanced their electrical
conductivity. Subsequently, the composites were treated
with hydrogen peroxide and air plasma in order to etch their surfaces and improve
their electrical properties. Samples were characterized by
thermogravimetrical analysis (TGA), X-ray diffraction (XRD), infrared analysis
(FTIR), transmission electron microscopy (TEM) and the electrical conductivity
of nanocomposites were calculated from resistivity. FTIR and XRD analysis
confirmed the Nylon-6 production and the reduction of graphite oxide. Results
of this work showed that microwave-assisted polymerization is a fast and
environmental friendly process to prepare electrically conductive
nanocomposites.
References:
[1] Song, Y., Luo, Y., Zhu. C. Recent Advances in
Electrochemical Biosensors based on Graphene Two-Dimensional Nanomaterials. Biosensors
and Bioelectronics 76, 195–212 (2015).
[2] Botas, C. Álvarez, P. Blanco, P. Graphene
materials with different structures prepared from the same graphite by
theHummers and Brodie methods. Carbon 65, 156–164 (2013).
[3] Navarro-Rosales, M., Ávila-Orta C.A., Neira-Velázquez,
M.G., Ortega-Ortiz H. Effect of plasma modification of copper nanoparticles on
their antibacterial properties. Plasma Process. Polym. 11, 685–693 (2014).
POSTER PRESENTATIONS
Confinement and Surface Effects on the Physical Properties
of Rhombohedral-Shape Hematite (a-Fe2O3) Nanocrystals
Aída D. Cuan-Guerra1, Enrique D. Barriga-Castro2, Nuria O. Núñez3, Raquel Mendoza-Reséndez1, Carlos Luna1.
1Universidad Autónoma de Nuevo León. San Nicolás de los Garza, Nuevo León, Mexico. 2Centro de Investigación en Química Aplicada. Saltillo, Coahuila, Mexico. 3 Instituto de Ciencia de Materiales de Sevilla, CSIC-US. Isla de la Cartuja, Sevilla, Spain.
Morphological, microstructural and vibrational properties of hematite (a-Fe2O3) nanocrystals with a rhombohedral shape and rounded edges, obtained by forced hydrolysis of iron(III) solutions under a fast nucleation, have been investigated in detail as a function of aging time. These studies allowed us to propose a detailed formation mechanism and revealed that these nanocrystals are composed of four {104} side facets, two {110} faces at the edges of the long diagonal of the nanocrystals and two {-441} facets as the top and bottom faces. Also, the presence of nanoscopic pores and fissures was evidenced. The vibrational bands of such nanocrystals were shifted to lower frequencies in comparison with bulk hematite ones as the nanocrystal size was reduced due to phonon confinement effects. Also, the indirect and direct transition band gaps displayed interesting dependences on the aging time arising from quantum confinement and surface effect.
Evaluation of Delivery and Encapsulation System of Vincristine Sulphate Gold Nanoparticles/Chitosan Conjugates
Edelin Posada Briceño1, Diana Ginette Zárate Triviño1, Moises Ármides Franco Molina1, Cristina Rodríguez Padilla1
1Laboratorio de Inmunología y virología. Facultad de Ciencias Biológicas.
Universidad Autónoma de Nuevo León. San Nicolás de los Garza, Nuevo León, Mexico.
Nanostructures such as liposomes, dendrimers and nanoparticles [2] have been used in the pharmaceutic industry for cover and delivery drugs searching to improve pharmacodynamic and pharmacokinetic properties[3]. The aim of this work is to create a vincristine sulphate (Vc) delivery system blend metallic and polymeric nanoparticles for obtain a hybrid nanoparticle based on conjugates of drug-gold nanoparticle coated with chitosan (QTS).
Gold nanoparticles (AuNPs) were synthesized by Tukevich modificated method using chitosan as reductor agent and were characterized the size, surface charge, resonance plasmon by light dynamic scattering (DLS), Z potential and UV-visible spectroscopy. The size average of AuNPs were 3 to 5 nm with a Z potential of 16.4 mV and a maximum absorption at 519-522 nm of wavelength. The conjugate of Vc and gold nanoparticles was coated by ionic gelation using chitosan with sodium tripolyphosphate (TPP), and evaluated by DLS, UV-vis and fourier transform infrared (FT-IR) spectroscopy. A calibration curve was made to evaluate the release of Vc by UV-vis spectroscopy resulting in a 0.99 R2, with a sensibility from 0.1 to 0.0099 mg/ml.
Two systems were evaluated as treatments: Gold nanoparticles and vincristine complex (CVcAu) and gold nanoparticles and vincristine coated with chitosan (CVcAu-QTS) were culture with hepatocarcinoma Hep G2 and lymphoma L5178Y-R cells, preliminary results showed that conjugates were more effectivity than Vc and gold nanoparticles at same concentrations at 24 hours.
References:
[1] Mohanraj VJ and Chen Y (2006) Nanoparticles: a review, Trop J Pharm Res, 5(1):561-573. http://www.tjpr.freehosting.net.
[1] Mohanraj VJ and Chen Y (2006) Nanoparticles: a review, Trop J Pharm Res, 5(1):561-573. http://www.tjpr.freehosting.net.
[2] Yah CS, Simate G and Sunny I (2012) Nanoparticles toxicity and their routes of exposures, Pak. J. Pharm. Sci., 25(2):477-491.
[3] Manmode SA, Sakarkar M and Mahajan M (2009) Nanoparticles-tremendous therapeutic potential: a review, International Journal of PharmTech Research 1(4):1020-1027.
The synthesis of gold nanoparticles into the reverse micelles of didodecyldimethylammonium bromide (DDAB) has been revisited, finding synthetic conditions that yield to the direct formation of very uniform gold flattened nanocrystals (AuNCs) with lower polydispersity degree than samples obtained by this method in previous works. Such AuNCs are also homogeneous in their exposed crystalline faces, composed of six side facets (four {111} faces and two {002} faces) and two {110} facets as the top and bottom faces. In addition, the spontaneous aggregation of these AuNCs into supramolecular structures with compacted packing, induced by the functionalization of the AuNCs with thiols, has been investigated. This self-organization process was reversible under heating treatments. This fact allowed us to examine the dependence of the plasmonic properties of AuNCs on their aggregation state under controlled conditions.
[3] Manmode SA, Sakarkar M and Mahajan M (2009) Nanoparticles-tremendous therapeutic potential: a review, International Journal of PharmTech Research 1(4):1020-1027.
Cytotoxic effect of gold nanoparticles coated with chitosan evaluated in cell line of mouse lymphoma L5178Y-R “in vitro” and a murine model “in vivo”
Gonzalo Del Bosque Pérez1, Diana Ginette Zárate Triviño1, Ana Carolina Martínez Torres1, Cristina Rodríguez Padilla1
1Laboratorio de Inmunología y virología. Facultad de Ciencias Biológicas.
Universidad Autónoma de Nuevo León. San Nicolás de los Garza, Nuevo León, Mexico.
The mayor disadvantage of current cancer treatments is the collateral effects and in some cases low efficacy [1], for this reason is necessary to study new alternative of antineoplastic agents. Gold nanoparticles are capable of generate cytotoxicity in several cancer cell lines [2]. Also, they can be synthesized using natural polymers like chitosan which is biocompatible and has properties of inmunoestimulation and antitumoral activity [3].
The aim of this project was to synthetize and characterize gold nanoparticles coated with chitosan for evaluate their cytotoxic effect in the cell line L5178Y-R using in vitro and in vivo assays. For characterization was used light dynamic scattering (LDS), scanning electron microscopy (SEM), spectrophotometry ultraviolet-visible (UV-vis). The cytotoxic effect in vitro was made by flow citometry after 24 hours with annexin/PI. A solid tumor was induced in BALB/C mice for the evaluation of the in vivo effect and was measured the tumor volume and survival rate to determinate the efficacy of treatments.
Gold nanoparticles size was between 3 and 7nm with an average of 3.6 nm and a plasmon resonance of 531 nm which is characteristic of nanometric gold. In the in vitro assay, we observed a significant cytotoxic effect in concentrations above 30 µM. And in vivo, the group of mice treated with 6.2 mg/kg of gold nanoparticles show 20% less tumor volume (similar to the positive control Vincristine), the treatment of AuNP’s and vincristine together showed 31.68% less tumor volume compared with the group without treatment. These 3 groups show an increase in the survival rate.
In conclusion, gold nanoparticles coated with chitosan show a significant cytotoxic effect in a dose-depend manner in vitro, and in vivo a reduction of tumor volume with an increase of survival rate.
References:
[1] Groopman JE, Itri LM (Oct 1999). "Chemotherapy-induced anemia in adults: incidence and treatment".Journal of the National Cancer Institute 91 (19): 1616–34
[1] Groopman JE, Itri LM (Oct 1999). "Chemotherapy-induced anemia in adults: incidence and treatment".Journal of the National Cancer Institute 91 (19): 1616–34
[2] Resham Bhattacharya, Priyabrata Mukherjee (2008). Biological properties of “naked” metal nanoparticles. Advanced Drug Delivery Reviews.
[3] Maeda M, Murakami H, Tajima M. (1992). Stimulation of igM production in human-hybridoma HB4C5 cells by chitoan. BiosciBiochem; 56:427-431
External Application of Silicon-Based Nanoparticles During the Curing Process
in Hardened Portland Cement-Based Materials
in Hardened Portland Cement-Based Materials
D. Cruz-Moreno1, G. Fajardo1, I. Flores-Vivian1, A. Cruz-López1, P. Valdez1
1Facultad de Ingeniería Civil, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, Mexico.
Corrosion of steel reinforcement is one of the main problems that beset the reinforced concrete structures (RCS) because of the porous nature of the hydrated portland cement products. Therefore, this paper studies the use of silicon-based nanoparticles (SBN) applied during the external curing and its microestructural effects in the treated samples. Portland cement-based mortar specimens were treated at an early age with SBN by two different methods: a) sprinkling SBN or b) by a film of SBN with thickness 20mm. The effect of the treatment was characterized from assaying electrical resistivity, N2 physisorption, SEM-EDS and accelerated tests carbonation and chlorides. Results demonstrated a reduction of CO2 penetration and Cl- levels up to 95% over the reference improving microstructural properties. Results regarding electrical resistivity, N2 physisorption, SEM-EDS is observed a decrease in the permeability in mortars, therefore prevents the passage to aggressive agents present in the medium. As a result, the application of SBN can improve external curing process and increase its durability and slow the corrosion process in the RCS.
Reversible self-assembly of thiol-stabilized gold nanocrystals into supremolecular face-centered cubic supercrystals: microstructural and plasmonic studies
Diana Castañeda-Rodríguez,1 Enrique Díaz Barriga-Castro,2 Nuria O. Núñez,3 Raquel Mendoza-Reséndez1, Carlos Luna1
1Universidad Autónoma de Nuevo León. San Nicolás de los Garza, Nuevo León, Mexico. 2Centro de Investigación en Química Aplicada. Saltillo, Coahuila, Mexico. 3 Instituto de Ciencia de Materiales de Sevilla, CSIC-US. Isla de la Cartuja, Sevilla, Spain.
The synthesis of gold nanoparticles into the reverse micelles of didodecyldimethylammonium bromide (DDAB) has been revisited, finding synthetic conditions that yield to the direct formation of very uniform gold flattened nanocrystals (AuNCs) with lower polydispersity degree than samples obtained by this method in previous works. Such AuNCs are also homogeneous in their exposed crystalline faces, composed of six side facets (four {111} faces and two {002} faces) and two {110} facets as the top and bottom faces. In addition, the spontaneous aggregation of these AuNCs into supramolecular structures with compacted packing, induced by the functionalization of the AuNCs with thiols, has been investigated. This self-organization process was reversible under heating treatments. This fact allowed us to examine the dependence of the plasmonic properties of AuNCs on their aggregation state under controlled conditions.
Chitosan capped-gold nanoparticles induces selective cancer cell death
Zugeeissy De León-Chávez1, Martín García-Juárez1, Carolina Rodríguez-Abrego1, Diana Zárate-Triviño1, Ana Carolina Martínez-Torres1, Cristina Rodríguez-Padilla1
1Laboratorio de Inmunología y Virología, Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León, Ciudad Universitaria, Nuevo León, México.
Zugeeissy De León-Chávez1, Martín García-Juárez1, Carolina Rodríguez-Abrego1, Diana Zárate-Triviño1, Ana Carolina Martínez-Torres1, Cristina Rodríguez-Padilla1
1Laboratorio de Inmunología y Virología, Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León, Ciudad Universitaria, Nuevo León, México.
Cancer represents a serious health problem around the world. It is known that first-line therapies are frequently characterized by affecting normal cells, moreover deregulations in tumor cells, such as their capacity to evade cell death, promote treatment-resistance. This is why, the development of new therapies that can be specific of cancer cells and that can overcome cell death resistance is necessary. Recent studies show that gold nanoparticles (Aunp’s) and chitosan possess interesting biological activities including potential antitumor effects; hence, in this study we synthetized chitosan-capped gold nanoparticles and analyzed their cell-death effect in two leukemia cell lines K562 and Jurkat, breast cancer cells, MCF-7 and cervical cancer cells, HeLa, we use peripheral blood mononuclear cells (PBMC) as a control. We evaluated metabolic activity, cell membrane permeabilization, phosphatidylserine exposure, response to caspase inhibitors, production of reactive oxygen species, mitochondrial membrane potential, effects on cell cycle, nucleus cell morphology and apoptosis protein expression. Our data shows that chitosan-capped AuNPs are cytotoxic in a dose-dependent way in leukemia cells, MCF-7 cells and HeLa cells, while they show low toxicity on PBMC. Altogether our results improve the knowledge of Aunp’s and chitosan as selective cytotoxic agents, and open the way to the design of new pharmacological strategies that includes these agents against cancer.
In-situ ferrite to autenite phase transformation by transmission electron microscopy during continuous heating of low carbon steels
R. Orsua-Gaona1,2, M.A. Ceniceros-Reyes1, E.M. Saucedo-Salazar1, A. Medina-Flores3, M.A. Aguilar-González4, E. Gutierrez-Castañeda5,6 and E. Díaz Barriga-Castro1
1Centro de Investigación en Química Aplicada (CIQA) Saltillo, Coahuila, Mexico. 2Instituto Tecnológico de Saltillo (ITS), Saltillo, Coahuila, Mexico. 3Instituto de Investigaciones Metalúrgicas (IIM), UMSNH. Morelia, Michoacán, Mexico. 4Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Av. Industria Metalúrgica No. 1062, Parque Saltillo-Ramos Arizpe, Ramos Arizpe, 31109, Coahuila, Mexico. 5Instituto de Metalurgía (IM), UASLP. San Luis Potosí, Mexico. 6Catedrático CONACYT. Cd. de México, Mexico.
The critical transformation temperatures on continuous heating of low-carbon steels containing as alloys elements 0.06% C, O.4% Si, 0.2% Al and 0.6% Mn (wt. %), were determined in the present research. Experiments were carried out by transmission electron microscopy to investigate the in-situ ferrite to austenite phase transformation on heating. To this end, sample were heating at rate of 1 °C/s from 25 °C (room temperature) up to 1200 °C. The holding time was 30 min followed by cooling at rate of 1 °C/s.
References:
Sample preparation for In-Situ TEM heating experiments by Dual Beam Systems
M. A. Ceniceros- Reyes1, E. Díaz Barriga-Castro1 E. M. Saucedo-Salazar1 and R. Orsua- Gaona1,2
1Centro de Investigación en Química Aplicada (CIQA), Blvd. Enrique Reyna Hermosillo No. 140, Saltillo, 25294, Coahuila, Mexico. 2Instituto Tecnológico de Saltillo (ITS), Blvd. Venustiano Carranza No. 2400, Tecnológico, Saltillo, 25280, Coahuila, Mexico.
Temperature is one of the most important causes affecting the behavior of materials [1]. Heating experiments carried out by transmission electron microscopy (TEM) provide the information for understanding such temperature effects. Nowadays TEM samples such as semiconductor devices and solar batteries are often prepared on special chips using dual beam systems (SEM/FIB) tools. This SEM/FIB sample preparation technique is easier and more versatile than conventional mechanical polishing techniques, however including preparation for heating experiments can be challenging and several steps are involved [2].
Solar Cells Devices with CTS Nanoparticles (CuxSnySz) as an Absorbent Material, Improved with TiO2 Nanorods
Diego Acero Fandiño1, Miguel Á Gracia-Pinilla1,
Wen Zhi Li2
1Universidad Autónoma de Nuevo León, 2Florida International University.
CTS compound have been synthesized by microwave synthesis technique using the monowave 300 (Anton-Parr reactor), we find synthetized three different stoichiometric Cu2SnS 3 (Mohite), Cu3SnS 4 (Kuramite) and Cu4SnS4. Ours samples will be characterized by X-ray diffraction, scanning electron microscope SEM, Transmission electron microscopy TEM, Atomic Force Microscope AFM, UV-Vis Transmittance and Raman Spectroscopy to determine morphological, structural and crystallographic properties (particle shape and size, crystalline phases and band gap), finally we choose at optimal conditions for grown the CTS on monophase (absorbent material) and with strict size control to use like absorbent material in a the solar cells device, we will include TiO2 nanorods to harvest the generated electrons inside the cell, then we will test its efficiency.
High Lumminiscense CdTe Quantum Dots with Different Emissions Obtained by Microwave Irradiation
M. A. Ruíz-Robles1, L.G. Silva1, F. Reyna1, F. Solis-Pomar1, C. D. Gutiérrez-Lazos1 and E. Pérez-Tijerina1
1Facultad de Ciencias Físico Matemáticas, Universidad Autónoma de Nuevo León, Av. Universidad s/n. Ciudad Universitaria, 66451 San Nicolás de los Garza, Nuevo León, México
The present work reports the colloidal synthesis of highly luminescent cadmium telluride (CdTe) quantum dots assisted by microwave irradiation. The method of preparation of quantum dots consists in a one-pot synthesis and the subsequent heating of sample by microwave irradiation. We found that the most important parameters for the preparation of samples were the temperature, heating time, and pH. Likewise, we present a study of the effect of this parameters in the optical properties of CdTe quantum dots. Some important aspects of this method is the use of a Monowave 300 equipment to heating the sample, which allow the control temperature and the heating time as well the vapor pressure, comparing with the traditional method, whereby the precursors are mixed in a flask and the solution is heated by reflux system; where the solution temperature depends on the heat transfer from the walls of flask, creating a temperature gradient. Therefore, the method presented in our work allows the preparation of a luminescent sample with a minor heating time. Changing the heating time, temperature and pH of solution, we obtain a different size of CdTe quantum dots with different optical properties. The analysis of the X-Ray diffraction shows the presence of CdTe with the cubical-FCC structure. The optical characterization of CdTe quantum dots was made by UV-VIS absorbance spectroscopy, DLS and photoluminescence. We can observe that the conditions of synthesis play an important role in the size and optical properties of the quantum dots.
Influence of Molar Ratio (Precursor / Water) in the Characteristics of a Biomaterial Obtained by the Sol Gel Technique
Rodolfo González Guerrero1, Lucía Guadalupe Cantú Cardenas1, Ma. Aracely Hernández Ramírez1, Patricia Cristina Esquivel Ferriño1.
1Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León, Av. Universidad s/n. Ciudad Universitaria, 66451 San Nicolás de los Garza, Nuevo León, México
Nowadays there is a trend in the development of new pharmaceutical forms using biodegradable and biocompatible materials as a matrix or support for the active ingredients. The development of these forms can be made by preparation of some biomaterials, which can be of different nature and synthesized by various techniques. The objective of this study is to obtain materials capable of incorporating an active ingredient in order to achieve a modified release, which can reduce the times of administration for the patient. Two materials were synthesized by the sol gel technique, which uses precursors such as Tetraethoxysilane (TEOS) to prepare SiO2. The gelation mechanism of TEOS when is mixed with ethanol, water and a small amount of acid (catalyst), consist of two steps: hydrolysis and condensation, obtaining a structural frame of Si-O-Si that expands three-dimensionally to obtain transparent wet gels in the beginning producing powders after drying and calcination processes. Moreover, this material can be obtained with an ordered mesostructure, using some surfactants such as Pluronic P-123, giving to the material uniform morphology to achieve a modified release. In this work TEOS was used as SiO2 precursor, and Pluronic P-123 as surfactant; also two different molar ratio of precursor/water (1:6 y 1:8) were used to evaluate their effect in the morphology, composition and structure of the material. Each material was analyzed by Scanning Electron Microscopy (SEM)-Energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and X- ray diffraction (XRD) technique. The obtained materials were compared to determine the best candidate to incorporate an antibiotic (gentamicin) to develop a modified release pharmaceutical form.
References:
Synthesis of Silver-Palladium Nanoparticles by Inert Gas Condensation
María Martínez-Carreón1, Francisco Solís-Pomar1, Eduardo Pérez-Tijerina1
1Universidad Autónoma de Nuevo León, CICFIM-FCFM. Av. Universidad S/N, Ciudad Universitaria, 66451 San Nicolás de Los Garza, NL.
Nanoparticles (NPs) are defined as nanomaterials with dimensions between 1 to 100 nm at least on one of three dimensions. Given that small size, NPs possess an elevated superficial area to volume ratio, high number of surface atoms and ability to exhibit quantum effects. These nanoparticles properties cannot be predicted by a simple extrapolation of their bulk properties [1].
The synthesis of bimetallic nanoparticles is an interesting topic because the interactions among them increases the properties that individual metal components exhibit. The performance obtained by addition of another metal can be attribute to structure and/or electronic effects [2-3].
The metals distribution defined the bimetallic NPs structures. When both metals are in a random distribution, structure is called an alloy. If one of the metal is in the center and the another forms a capsule around the nucleus, is named a core-shell structure. To form structures of clusters in clusters, groups of species over another group, or deposits layer by layer, are required tighter synthesis controls. The atomic ratio of the constituent metals also influence the NPs structures [4].
Nanoparticles were synthetized by Inert Gas Condensation. This technique consists of a high-pressure magnetron DC-sputtering that generates a metallic atomic vapor supersaturated from target to erode. The NPs size can be adjust by three parameters: aggregation area, power erosion and gas flow.
References:
[4] Nanoalloys: From Theory to Applications of Alloy Clusters and Nanoparticles. Ferrando, R., Jellinek, J. & Johnston, R. Chemical Reviews, 2008, Vol. 108, pp. 845-910.
Deposition and characterization of ultra-thin low-emissive heteroestructures
Carlos Enrique Bender-Pérez1, Claudio Davet Gutiérrez-Lazos1, Francisco-José Solís-Pomar1
and Eduardo Gerardo Pérez Tijerina1.
1Centro de Investigación en Ciencias Físico Matemáticas, Facultad de Ciencias Físico Matemáticas, Universidad Autónoma de Nuevo León, Av. Universidad s/n. Ciudad Universitaria, 66451 San Nicolás de los Garza, Nuevo León, Mexico.
We report the deposition by reactive sputtering technique and the optical characterization by transmittance of ultrathin low-emissive coatings. We considered two proposals for the heterostructures were optical transmittance and reflectance properties were previously simulated in order to determine the required thickness of each layer. The first heterostructure consisted of a 7-layer coating based on 6 different materials whose transmittance had a maximum of 84% at 550 nm, slightly higher than the determined by simulation, and with a low transmittance at near-infrared region. The second heterostructure was reduced to 4 layers based on 3 different materials (Si3N4/Ag /Si3N4) with a transmittance greater than 86% and a low transmittance at the infrared region. For these samples, it was found that the bandwidth of transmittance and the position of the maximum of transmittance have a dependence on the Si3N4 layers thickness. Specifically, the thickness of the first Si3N4 layer allows adjust the bandwidth of transmittance, and the thickness of the second layer allows the adjust of the maximum position.
Development ceramic materials for drug delivery systems in powders and films synthesized via sol-gel
Cynthia Guadalupe González Carvajal1, Ma. Aracely Hernández Ramírez1, Lucía Guadalupe Cantú Cárdenas1
1Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, Laboratorio de Biofarmacia. Pedro de Alba s/n, San Nicolás de los Garza, México.
In recent years, research in the field of ceramic materials has grown, due to the variety of applications, including medical uses such as the development of drug delivery systems. Ceramic materials of silica represent a good alternative as drug release systems making possible to incorporate large amounts of drugs in the pores. The mesopore structure which consists of a network of siloxane bridges and silanol free groups can be made these materials suitable as matrix for adsorption and controlled release of molecules with therapeutic activity. The aim of this work was to prepare SiO2 materials by sol-gel method as powders and films to determine the best candidate for incorporate a drug. The materials were prepared at acidic conditions and Tetraethyl orthosilicate (TEOS) in a molar ratio of 1:6 (alcoxide/water) was used. Furthermore, we evaluated the effect of surfactant Pluronic 123 on the morphology of the obtained materials. The synthesis of silica films was performed by dip coating technique; the deposition began after 24 h of sol formation on glass slide as substrate. The process was repeated to obtain thin films and then, the material was calcined at 400°C during 4 h between each deposition. To compare the materials properties, they were characterized by different techniques such as Fourier transform infrared spectroscopy (FTIR), Scanning Electronic Microscopy - Energy Dispersive X-ray Spectroscopy (SEM-EDS) and X-ray diffraction (XRD).
References:
[3] López, R., Perez, I., et.al. (2014). Efecto de la temperatura de calcinación sobre la concentración de grupos silanoles en superficies de SiO2 (SBA–15). Avances en Química, 9(1), 21-28.
Synthesis and
characterization of graphene oxide by Tour´s method: Solution properties
studied by SAXS
Mariana
I. Camargo García1, Perla J. Hernández Belmares2, Silvia
G. Solís Rosales2, Salvador Fernández Tavizón2, Edgar de
Casas Ortiz2, José M. Mata Padilla2, Pablo Gonzalez
Morones2, Filemón Monzalvo Licona1, Ernesto Hernández
Hernández2
1 Instituto
Tecnológico Nacional de México, Instituto Tecnológico de Pachuca. Av. Felipe
Ángeles km 84.5, venta prieta, C.P. 42083, Pachuca de Soto, Hgo, México.
With the aim objective to obtained environmental friendly and more
stable graphene oxides, in the present we use the Tour´s method [1] to
synthetized it and different technics of characterization were used to
determinate the structural, morphological and thermal properties. We are
focused in solution properties at different concentrations (1:20, 1:40, 1:50
GO/H2O wt/wt) studied by small angle X ray scattering (SAXS).
Infrared spectrum showed the typical band of carbonyl, hydroxyl and epoxy
groups of the samples. About 40 wt% of functional groups containing on graphene
oxide were determinate by thermogravimetrical analysis. Also, typical laminar
morphology was observed by transmission electron microscopy. X ray diffraction
indicate a signal at 10 º in 2 theta associated to the interlaminar distance of
approximately 0.88 Å. According to the SAXS results, a direct dependence of the
water concentration on the interlaminar separation of interlayer of graphene
oxide obtaining a values of 9.33 and 13.59 nm at ratios GO/H2O 1:20,
1:40, respectively. At ratio of GO/H2O 1:50 no signal of SAXS was
observed indicating that exfoliated layers were obtained at this concentration.
These results could be useful in different applications were the samples
require to be solved in water or other solvents.
References:
Formation of graphene from graphite by non-standard route
Jared Rodríguez1, Oxana Kharissova1 , Boris Kharisov 2
1 Universidad Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas. 2Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas
Graphene sheets were formed in water as a result of dispersion and destruction of graphite in mild conditions using a water-soluble cobalt octacarboxyphthalocyanine derivative theraphthal (TP) together with ascorbic acid (AA) in ultrasonic treatment conditions. The synthesis was carried out using different amounts of graphite, AA and TP, which were ultrasonicated in 30 mL flasks with DI water for 5 h in ultrasonic cleaner. The fact of graphite decomposition in these conditions is out of conventional concepts on classic p-p stacking interactions and/or -bonding between macrocycles and carbon phases. Destruction of graphite forming oxidized graphene is explained by free radical processes in the system TP-AA in strong cavitation conditions. Characterization of samples was made by Raman spectroscopy, Transmission Electron Microscopy (TEM) end IR.
Non-conventional synthesis of carbon nano-ribbons by the low-temperature unfolding of MWCNTs
Andrés Solis 1, Alberto Castillo 1, Oxana Kharissova 1
1Universidad Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas
The treatment of MWCNTs with the water-soluble cobalt octacarboxyphthalocyanine derivative theraphthal (TP, a cancer therapy drug) under ultrasonic conditions in the presence of ascorbic acid (AA) led to the dispersion and unfolding of MWCNTs, producing ribbon-like nanostructures (NRs) at low temperatures .The synthesis was carried out using different amounts of slightly magnetic MWCNTs, AA and TP, which were ultrasonicated in 30 mL flasks with DI water for 5 h in ultrasonic cleaner at 42-45oC. In these conditions, even at low intensity ultrasound in cleaners (20-40 kHz), partial destruction of TP slowly takes place and it is known to be accompanied by formation of Reactive Oxygen Species (ROS). TP can be first coordinated to CNT surface via p-p-stacking through aromatic supramolecular ring or covalently through COO- group(s) of the TP molecule. Unfolding of MWCNTs in the conditions of TP/AA addition can be explained by the in situ formation of ROS in TP solutions under ultrasonic treatment and their further attack on MWCNTs surface, destroying and unfolding them forming graphene sheets and ribbons. The obtained results differ from the conventional concepts of classic p-p- stacking interactions and/or -bonding between macrocycles and carbon nanotubes. Characterization of samples was made by Raman spectroscopy, Transmission Electron Microscopy (TEM) end IR.
Fabrications of carbon nanoparticles vía spray pyrolysis method using metal phthalocyanines as catalyst precursors
Antonio Alanis1, Beatriz Ortega1, Oxana Kharissova1, Hugo Galindo 1
1Universidad Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas
In this work, the synthesis of carbon nanoparticles was carried out vía spray pyrolysis using toluene solution with suspended zinc, copper, nickel or magnesium phthalocyanines as precursors of metallic particles serving as catalysts for carbon phase formation. The process was conducted in a range of temperatures in a nitrogen atmosphere in a quartz tube, containing borosilicate glass supports, onto which surface the nanometric layers of nanoparticles were deposited. The samples were analyzed by SEM, TEM and IR-specroscopy; their condusctivity was measured vía Kelvin technique. The properties of formed nanolayers were analyzed according to metal nature in the phthalocyanine, temperature, carrier gas speed, and other process parameters. Possible MEMS applications of thus fabricated nanolayers are discussed.
Processing
of Micro and Nano Cellulose from soybean hulls by ultrasound method
Blanca I. Montes Mejia1, Oxana V.
Kharissova1, Boris I. Kharisov1
1Universidad
Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas. 2Universidad
Autónoma de Nuevo León, Facultad de Ciencias Químicas
In this research the results for the production of micro and
nanocellulose from husk of soy are presented by ultrasound, using methods
alkaline collection consisting of basic solution (NaOH 10% w / w), and breeding
method acid, consisting of acidic solution of HNO3 at 65% w / w, washing,
filtering and drying, and thus achieve applications husk soy which is a
byproduct of the process of obtaining soybean oil which contains about 40 %
fiber in order to develop polymeric materials with properties and applications
in the paper industry with the potential capacity to replace the cellulose from
trees and reducing the use of it and contribute to the environmental impact
decreasing cutting trees.
Synthesis and
Bactericide Activity of Ultrafine Silver Nuclei Embedded into an Ascorbic Acid
Matrix
1Universidad Autónoma de Nuevo León (UANL), Av.
Universidad S/N, San Nicolás de los Garza, Nuevo León 66450, Mexico. 2Centro de Investigación en Química
Aplicada (CIQA), Blvd. Enrique Reyna Hermosillo No. 140, Saltillo, 25294
Coahuila, Mexico
Silver nanostructured
materials have stimulated huge interest due to their interesting and
multifunctional plasmonic, surface enhancement Raman scattering (SERS) and
catalytic properties, and due to their unique biological activities, being
broad-spectrum antimicrobials [1-3]. Usually, these materials are obtained by
reduction of Ag+ ions in solution from a metal salt, typically silver nitrate,
using a reducing agent such as sodium borohydride, acid ascorbic acid or
natural plant extracts [4-6], among others. Usually these methods result in polydisperse
nanoparticles with sizes around or larger than 10 nm because silver particles with
smaller sizes exhibit a strong tendency to grow by secondary growth mechanisms
such as Ostwald ripening, irreversible aggregation and coalescence [6].
Cancer represents a serious health problem around the world. It is known that first-line therapies are frequently characterized by affecting normal cells, moreover deregulations in tumor cells, such as their capacity to evade cell death, promote treatment-resistance. This is why, the development of new therapies that can be specific of cancer cells and that can overcome cell death resistance is necessary. Recent studies show that gold nanoparticles (Aunp’s) and chitosan possess interesting biological activities including potential antitumor effects; hence, in this study we synthetized chitosan-capped gold nanoparticles and analyzed their cell-death effect in two leukemia cell lines K562 and Jurkat, breast cancer cells, MCF-7 and cervical cancer cells, HeLa, we use peripheral blood mononuclear cells (PBMC) as a control. We evaluated metabolic activity, cell membrane permeabilization, phosphatidylserine exposure, response to caspase inhibitors, production of reactive oxygen species, mitochondrial membrane potential, effects on cell cycle, nucleus cell morphology and apoptosis protein expression. Our data shows that chitosan-capped AuNPs are cytotoxic in a dose-dependent way in leukemia cells, MCF-7 cells and HeLa cells, while they show low toxicity on PBMC. Altogether our results improve the knowledge of Aunp’s and chitosan as selective cytotoxic agents, and open the way to the design of new pharmacological strategies that includes these agents against cancer.
[2] Instituto Nacional del Cáncer (NIH). http://www.cancer.gov/ (consultado (visitado) el 15 de Septiembre de 2015).
[3] Lárez- Velásquez, C. Avances en Química, 2006. 1(2), 15-21.
[4] Elmore, S. Toxicol Pathol. 2007, 35(4), 495-516.
[5] Liang, Ye., Yan, C., Schor, N.F. Oncogene. 2001, 20, 6570-6578.
[6] Eruslanov, E., Kusmartsev, S. Advanced Protocols in Oxidative Stress II. 2010. 57-72.
In-situ ferrite to autenite phase transformation by transmission electron microscopy during continuous heating of low carbon steels
R. Orsua-Gaona1,2, M.A. Ceniceros-Reyes1, E.M. Saucedo-Salazar1, A. Medina-Flores3, M.A. Aguilar-González4, E. Gutierrez-Castañeda5,6 and E. Díaz Barriga-Castro1
1Centro de Investigación en Química Aplicada (CIQA) Saltillo, Coahuila, Mexico. 2Instituto Tecnológico de Saltillo (ITS), Saltillo, Coahuila, Mexico. 3Instituto de Investigaciones Metalúrgicas (IIM), UMSNH. Morelia, Michoacán, Mexico. 4Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Av. Industria Metalúrgica No. 1062, Parque Saltillo-Ramos Arizpe, Ramos Arizpe, 31109, Coahuila, Mexico. 5Instituto de Metalurgía (IM), UASLP. San Luis Potosí, Mexico. 6Catedrático CONACYT. Cd. de México, Mexico.
The critical transformation temperatures on continuous heating of low-carbon steels containing as alloys elements 0.06% C, O.4% Si, 0.2% Al and 0.6% Mn (wt. %), were determined in the present research. Experiments were carried out by transmission electron microscopy to investigate the in-situ ferrite to austenite phase transformation on heating. To this end, sample were heating at rate of 1 °C/s from 25 °C (room temperature) up to 1200 °C. The holding time was 30 min followed by cooling at rate of 1 °C/s.
Three main components were used to carry out the thermal cycles that allow the study of the in-situ phase transformation: 1) the MEMS heating chip, 2) a low drift TEM holder with electrical connections, and 3) a computer controlled heating system. Finally, the transformation temperatures were estimated from the crystallographic changes based on diffraction patterns (SAED) and HRTEM images that are directly related to changes in the BCC to FCC structure during the ferrite to austenite transformation.
References:
[1] Díaz Barriga-Castro E., Salinas-Rodríguez A. & Nava-Vázquez E. Austenite-Ferrite Transformation in Non-Oriented Electrical Steels. Materials Science Forum, 560, 85-89 (2007).
[2] Nikolay Petkov. In Situ Real-Time TEM Reveals Growth, Transformation and Function in One-Dimensional Nanoscale Materials: From a Nanotechnology Perspective. Nanotechnology, 2013, Article ID 893060, (2013).
[3] Dlouhya A., Khalil-Allafib J. & Eggelerb G. Multiple-step Martensitic Transformations in Ni-rich NiTi Alloys--an In-situ Transmission Electron Microscopy Investigation. Philosophical Magazine, 83 (3), 339-363 (2010).
Sample preparation for In-Situ TEM heating experiments by Dual Beam Systems
M. A. Ceniceros- Reyes1, E. Díaz Barriga-Castro1 E. M. Saucedo-Salazar1 and R. Orsua- Gaona1,2
1Centro de Investigación en Química Aplicada (CIQA), Blvd. Enrique Reyna Hermosillo No. 140, Saltillo, 25294, Coahuila, Mexico. 2Instituto Tecnológico de Saltillo (ITS), Blvd. Venustiano Carranza No. 2400, Tecnológico, Saltillo, 25280, Coahuila, Mexico.
Temperature is one of the most important causes affecting the behavior of materials [1]. Heating experiments carried out by transmission electron microscopy (TEM) provide the information for understanding such temperature effects. Nowadays TEM samples such as semiconductor devices and solar batteries are often prepared on special chips using dual beam systems (SEM/FIB) tools. This SEM/FIB sample preparation technique is easier and more versatile than conventional mechanical polishing techniques, however including preparation for heating experiments can be challenging and several steps are involved [2].
The aim of this work is to describe the procedure of sample preparation for In-situ TEM heating experiments. The experiments were carried out in a dual beam workstation FEI QUANTA 200 3D and the chips used were MEMS Microheaters for NanoExTM-i/v holder, highly recommended for heating experiments on nanoparticles and FIB lamella. A few samples were obtained from low carbon steel and the results illustrate that the adjustments of several techniques in order to obtain the lamella attached to the chip were successful for this equipment.
References:
[1] In Situ Heating Transmission Electron Microscopy, Hiroyasu Saka, Takeo Kamino, Shigeo Arai and Katsuhiro Sasaki. MRS Bulletin, Vol 33, 2008.
[2] FIB Sample Preparation – Techniques for sample preparation on E-chips
Solar Cells Devices with CTS Nanoparticles (CuxSnySz) as an Absorbent Material, Improved with TiO2 Nanorods
Diego Acero Fandiño1, Miguel Á Gracia-Pinilla1,
Wen Zhi Li2
1Universidad Autónoma de Nuevo León, 2Florida International University.
CTS compound have been synthesized by microwave synthesis technique using the monowave 300 (Anton-Parr reactor), we find synthetized three different stoichiometric Cu2SnS 3 (Mohite), Cu3SnS 4 (Kuramite) and Cu4SnS4. Ours samples will be characterized by X-ray diffraction, scanning electron microscope SEM, Transmission electron microscopy TEM, Atomic Force Microscope AFM, UV-Vis Transmittance and Raman Spectroscopy to determine morphological, structural and crystallographic properties (particle shape and size, crystalline phases and band gap), finally we choose at optimal conditions for grown the CTS on monophase (absorbent material) and with strict size control to use like absorbent material in a the solar cells device, we will include TiO2 nanorods to harvest the generated electrons inside the cell, then we will test its efficiency.
The present work reports the colloidal synthesis of highly luminescent cadmium telluride (CdTe) quantum dots assisted by microwave irradiation. The method of preparation of quantum dots consists in a one-pot synthesis and the subsequent heating of sample by microwave irradiation. We found that the most important parameters for the preparation of samples were the temperature, heating time, and pH. Likewise, we present a study of the effect of this parameters in the optical properties of CdTe quantum dots. Some important aspects of this method is the use of a Monowave 300 equipment to heating the sample, which allow the control temperature and the heating time as well the vapor pressure, comparing with the traditional method, whereby the precursors are mixed in a flask and the solution is heated by reflux system; where the solution temperature depends on the heat transfer from the walls of flask, creating a temperature gradient. Therefore, the method presented in our work allows the preparation of a luminescent sample with a minor heating time. Changing the heating time, temperature and pH of solution, we obtain a different size of CdTe quantum dots with different optical properties. The analysis of the X-Ray diffraction shows the presence of CdTe with the cubical-FCC structure. The optical characterization of CdTe quantum dots was made by UV-VIS absorbance spectroscopy, DLS and photoluminescence. We can observe that the conditions of synthesis play an important role in the size and optical properties of the quantum dots.
High Lumminiscense CdTe Quantum Dots with Different Emissions Obtained by Microwave Irradiation
M. A. Ruíz-Robles1, L.G. Silva1, F. Reyna1, F. Solis-Pomar1, C. D. Gutiérrez-Lazos1 and E. Pérez-Tijerina1
1Facultad de Ciencias Físico Matemáticas, Universidad Autónoma de Nuevo León, Av. Universidad s/n. Ciudad Universitaria, 66451 San Nicolás de los Garza, Nuevo León, México
The present work reports the colloidal synthesis of highly luminescent cadmium telluride (CdTe) quantum dots assisted by microwave irradiation. The method of preparation of quantum dots consists in a one-pot synthesis and the subsequent heating of sample by microwave irradiation. We found that the most important parameters for the preparation of samples were the temperature, heating time, and pH. Likewise, we present a study of the effect of this parameters in the optical properties of CdTe quantum dots. Some important aspects of this method is the use of a Monowave 300 equipment to heating the sample, which allow the control temperature and the heating time as well the vapor pressure, comparing with the traditional method, whereby the precursors are mixed in a flask and the solution is heated by reflux system; where the solution temperature depends on the heat transfer from the walls of flask, creating a temperature gradient. Therefore, the method presented in our work allows the preparation of a luminescent sample with a minor heating time. Changing the heating time, temperature and pH of solution, we obtain a different size of CdTe quantum dots with different optical properties. The analysis of the X-Ray diffraction shows the presence of CdTe with the cubical-FCC structure. The optical characterization of CdTe quantum dots was made by UV-VIS absorbance spectroscopy, DLS and photoluminescence. We can observe that the conditions of synthesis play an important role in the size and optical properties of the quantum dots.
Influence of Molar Ratio (Precursor / Water) in the Characteristics of a Biomaterial Obtained by the Sol Gel Technique
Rodolfo González Guerrero1, Lucía Guadalupe Cantú Cardenas1, Ma. Aracely Hernández Ramírez1, Patricia Cristina Esquivel Ferriño1.
1Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León, Av. Universidad s/n. Ciudad Universitaria, 66451 San Nicolás de los Garza, Nuevo León, México
Nowadays there is a trend in the development of new pharmaceutical forms using biodegradable and biocompatible materials as a matrix or support for the active ingredients. The development of these forms can be made by preparation of some biomaterials, which can be of different nature and synthesized by various techniques. The objective of this study is to obtain materials capable of incorporating an active ingredient in order to achieve a modified release, which can reduce the times of administration for the patient. Two materials were synthesized by the sol gel technique, which uses precursors such as Tetraethoxysilane (TEOS) to prepare SiO2. The gelation mechanism of TEOS when is mixed with ethanol, water and a small amount of acid (catalyst), consist of two steps: hydrolysis and condensation, obtaining a structural frame of Si-O-Si that expands three-dimensionally to obtain transparent wet gels in the beginning producing powders after drying and calcination processes. Moreover, this material can be obtained with an ordered mesostructure, using some surfactants such as Pluronic P-123, giving to the material uniform morphology to achieve a modified release. In this work TEOS was used as SiO2 precursor, and Pluronic P-123 as surfactant; also two different molar ratio of precursor/water (1:6 y 1:8) were used to evaluate their effect in the morphology, composition and structure of the material. Each material was analyzed by Scanning Electron Microscopy (SEM)-Energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and X- ray diffraction (XRD) technique. The obtained materials were compared to determine the best candidate to incorporate an antibiotic (gentamicin) to develop a modified release pharmaceutical form.
References:
[1] Thakur, V. K., & Thakur, M. K. (2015). Handbook of polymers for pharmaceutical technologies. Vol 2: Processing and Applications. Chichester: John Wiley.
[2] Keservani, R. K., Sharma, A. K., & Kesharwani, R. K. (2016). Novel approaches for drug delivery. IGI Global.
Synthesis of Silver-Palladium Nanoparticles by Inert Gas Condensation
María Martínez-Carreón1, Francisco Solís-Pomar1, Eduardo Pérez-Tijerina1
1Universidad Autónoma de Nuevo León, CICFIM-FCFM. Av. Universidad S/N, Ciudad Universitaria, 66451 San Nicolás de Los Garza, NL.
Nanoparticles (NPs) are defined as nanomaterials with dimensions between 1 to 100 nm at least on one of three dimensions. Given that small size, NPs possess an elevated superficial area to volume ratio, high number of surface atoms and ability to exhibit quantum effects. These nanoparticles properties cannot be predicted by a simple extrapolation of their bulk properties [1].
The synthesis of bimetallic nanoparticles is an interesting topic because the interactions among them increases the properties that individual metal components exhibit. The performance obtained by addition of another metal can be attribute to structure and/or electronic effects [2-3].
The metals distribution defined the bimetallic NPs structures. When both metals are in a random distribution, structure is called an alloy. If one of the metal is in the center and the another forms a capsule around the nucleus, is named a core-shell structure. To form structures of clusters in clusters, groups of species over another group, or deposits layer by layer, are required tighter synthesis controls. The atomic ratio of the constituent metals also influence the NPs structures [4].
Nanoparticles were synthetized by Inert Gas Condensation. This technique consists of a high-pressure magnetron DC-sputtering that generates a metallic atomic vapor supersaturated from target to erode. The NPs size can be adjust by three parameters: aggregation area, power erosion and gas flow.
References:
[1] Nagarajan, R. & Hatton, T. Nanoparticles: Synthesis, Stabilization, Passivation, and Functionalization. Washington, DC. ACS, 2008.
[2] Gold in Bimetallic Catalysts. Schwank, J. Gold Bulletin, 1985, Vol. 18, pp. 2-10.
[3] Bimetallic nanoparticles novel materials for chemical and physical applications. Toshima, N. & Yonezawa, T. New Journal of Chemistry, 1998, Vol. 22, pp. 1179-1201.
[4] Nanoalloys: From Theory to Applications of Alloy Clusters and Nanoparticles. Ferrando, R., Jellinek, J. & Johnston, R. Chemical Reviews, 2008, Vol. 108, pp. 845-910.
We report the deposition by reactive sputtering technique and the optical characterization by transmittance of ultrathin low-emissive coatings. We considered two proposals for the heterostructures were optical transmittance and reflectance properties were previously simulated in order to determine the required thickness of each layer. The first heterostructure consisted of a 7-layer coating based on 6 different materials whose transmittance had a maximum of 84% at 550 nm, slightly higher than the determined by simulation, and with a low transmittance at near-infrared region. The second heterostructure was reduced to 4 layers based on 3 different materials (Si3N4/Ag /Si3N4) with a transmittance greater than 86% and a low transmittance at the infrared region. For these samples, it was found that the bandwidth of transmittance and the position of the maximum of transmittance have a dependence on the Si3N4 layers thickness. Specifically, the thickness of the first Si3N4 layer allows adjust the bandwidth of transmittance, and the thickness of the second layer allows the adjust of the maximum position.
In recent years, research in the field of ceramic materials has grown, due to the variety of applications, including medical uses such as the development of drug delivery systems. Ceramic materials of silica represent a good alternative as drug release systems making possible to incorporate large amounts of drugs in the pores. The mesopore structure which consists of a network of siloxane bridges and silanol free groups can be made these materials suitable as matrix for adsorption and controlled release of molecules with therapeutic activity. The aim of this work was to prepare SiO2 materials by sol-gel method as powders and films to determine the best candidate for incorporate a drug. The materials were prepared at acidic conditions and Tetraethyl orthosilicate (TEOS) in a molar ratio of 1:6 (alcoxide/water) was used. Furthermore, we evaluated the effect of surfactant Pluronic 123 on the morphology of the obtained materials. The synthesis of silica films was performed by dip coating technique; the deposition began after 24 h of sol formation on glass slide as substrate. The process was repeated to obtain thin films and then, the material was calcined at 400°C during 4 h between each deposition. To compare the materials properties, they were characterized by different techniques such as Fourier transform infrared spectroscopy (FTIR), Scanning Electronic Microscopy - Energy Dispersive X-ray Spectroscopy (SEM-EDS) and X-ray diffraction (XRD).
Deposition and characterization of ultra-thin low-emissive heteroestructures
Carlos Enrique Bender-Pérez1, Claudio Davet Gutiérrez-Lazos1, Francisco-José Solís-Pomar1
and Eduardo Gerardo Pérez Tijerina1.
and Eduardo Gerardo Pérez Tijerina1.
1Centro de Investigación en Ciencias Físico Matemáticas, Facultad de Ciencias Físico Matemáticas, Universidad Autónoma de Nuevo León, Av. Universidad s/n. Ciudad Universitaria, 66451 San Nicolás de los Garza, Nuevo León, Mexico.
We report the deposition by reactive sputtering technique and the optical characterization by transmittance of ultrathin low-emissive coatings. We considered two proposals for the heterostructures were optical transmittance and reflectance properties were previously simulated in order to determine the required thickness of each layer. The first heterostructure consisted of a 7-layer coating based on 6 different materials whose transmittance had a maximum of 84% at 550 nm, slightly higher than the determined by simulation, and with a low transmittance at near-infrared region. The second heterostructure was reduced to 4 layers based on 3 different materials (Si3N4/Ag /Si3N4) with a transmittance greater than 86% and a low transmittance at the infrared region. For these samples, it was found that the bandwidth of transmittance and the position of the maximum of transmittance have a dependence on the Si3N4 layers thickness. Specifically, the thickness of the first Si3N4 layer allows adjust the bandwidth of transmittance, and the thickness of the second layer allows the adjust of the maximum position.
Development ceramic materials for drug delivery systems in powders and films synthesized via sol-gel
Cynthia Guadalupe González Carvajal1, Ma. Aracely Hernández Ramírez1, Lucía Guadalupe Cantú Cárdenas1
1Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, Laboratorio de Biofarmacia. Pedro de Alba s/n, San Nicolás de los Garza, México.
In recent years, research in the field of ceramic materials has grown, due to the variety of applications, including medical uses such as the development of drug delivery systems. Ceramic materials of silica represent a good alternative as drug release systems making possible to incorporate large amounts of drugs in the pores. The mesopore structure which consists of a network of siloxane bridges and silanol free groups can be made these materials suitable as matrix for adsorption and controlled release of molecules with therapeutic activity. The aim of this work was to prepare SiO2 materials by sol-gel method as powders and films to determine the best candidate for incorporate a drug. The materials were prepared at acidic conditions and Tetraethyl orthosilicate (TEOS) in a molar ratio of 1:6 (alcoxide/water) was used. Furthermore, we evaluated the effect of surfactant Pluronic 123 on the morphology of the obtained materials. The synthesis of silica films was performed by dip coating technique; the deposition began after 24 h of sol formation on glass slide as substrate. The process was repeated to obtain thin films and then, the material was calcined at 400°C during 4 h between each deposition. To compare the materials properties, they were characterized by different techniques such as Fourier transform infrared spectroscopy (FTIR), Scanning Electronic Microscopy - Energy Dispersive X-ray Spectroscopy (SEM-EDS) and X-ray diffraction (XRD).
References:
[1] López, T., López, M., et.al. (2013). Obtaining of Sol-Gel Ketorolac-Silica Nanoparticles: Characterization and Drug Release Kinetics. Journal of Nanomaterials
[2] Hernández, A., Esquivel, P., et.al. (2007). Effect of the Sol-Gel Synthesis Parameters on the Incorporation of an Anti-inflammatory Drug in a Ceramic Material. MRS Proceeding.
[3] López, R., Perez, I., et.al. (2014). Efecto de la temperatura de calcinación sobre la concentración de grupos silanoles en superficies de SiO2 (SBA–15). Avances en Química, 9(1), 21-28.
With the aim objective to obtained environmental friendly and more
stable graphene oxides, in the present we use the Tour´s method [1] to
synthetized it and different technics of characterization were used to
determinate the structural, morphological and thermal properties. We are
focused in solution properties at different concentrations (1:20, 1:40, 1:50
GO/H2O wt/wt) studied by small angle X ray scattering (SAXS).
Infrared spectrum showed the typical band of carbonyl, hydroxyl and epoxy
groups of the samples. About 40 wt% of functional groups containing on graphene
oxide were determinate by thermogravimetrical analysis. Also, typical laminar
morphology was observed by transmission electron microscopy. X ray diffraction
indicate a signal at 10 º in 2 theta associated to the interlaminar distance of
approximately 0.88 Å. According to the SAXS results, a direct dependence of the
water concentration on the interlaminar separation of interlayer of graphene
oxide obtaining a values of 9.33 and 13.59 nm at ratios GO/H2O 1:20,
1:40, respectively. At ratio of GO/H2O 1:50 no signal of SAXS was
observed indicating that exfoliated layers were obtained at this concentration.
These results could be useful in different applications were the samples
require to be solved in water or other solvents.
Silver nanostructured
materials have stimulated huge interest due to their interesting and
multifunctional plasmonic, surface enhancement Raman scattering (SERS) and
catalytic properties, and due to their unique biological activities, being
broad-spectrum antimicrobials [1-3]. Usually, these materials are obtained by
reduction of Ag+ ions in solution from a metal salt, typically silver nitrate,
using a reducing agent such as sodium borohydride, acid ascorbic acid or
natural plant extracts [4-6], among others. Usually these methods result in polydisperse
nanoparticles with sizes around or larger than 10 nm because silver particles with
smaller sizes exhibit a strong tendency to grow by secondary growth mechanisms
such as Ostwald ripening, irreversible aggregation and coalescence [6].
Synthesis and
characterization of graphene oxide by Tour´s method: Solution properties
studied by SAXS
Mariana
I. Camargo García1, Perla J. Hernández Belmares2, Silvia
G. Solís Rosales2, Salvador Fernández Tavizón2, Edgar de
Casas Ortiz2, José M. Mata Padilla2, Pablo Gonzalez
Morones2, Filemón Monzalvo Licona1, Ernesto Hernández
Hernández2
1 Instituto
Tecnológico Nacional de México, Instituto Tecnológico de Pachuca. Av. Felipe
Ángeles km 84.5, venta prieta, C.P. 42083, Pachuca de Soto, Hgo, México.
2 Centro
de Investigación en Química Aplicada, Blvd. Enrique Reyna H. 140 C.P. 25294,
Saltillo, Coah. México.
With the aim objective to obtained environmental friendly and more
stable graphene oxides, in the present we use the Tour´s method [1] to
synthetized it and different technics of characterization were used to
determinate the structural, morphological and thermal properties. We are
focused in solution properties at different concentrations (1:20, 1:40, 1:50
GO/H2O wt/wt) studied by small angle X ray scattering (SAXS).
Infrared spectrum showed the typical band of carbonyl, hydroxyl and epoxy
groups of the samples. About 40 wt% of functional groups containing on graphene
oxide were determinate by thermogravimetrical analysis. Also, typical laminar
morphology was observed by transmission electron microscopy. X ray diffraction
indicate a signal at 10 º in 2 theta associated to the interlaminar distance of
approximately 0.88 Å. According to the SAXS results, a direct dependence of the
water concentration on the interlaminar separation of interlayer of graphene
oxide obtaining a values of 9.33 and 13.59 nm at ratios GO/H2O 1:20,
1:40, respectively. At ratio of GO/H2O 1:50 no signal of SAXS was
observed indicating that exfoliated layers were obtained at this concentration.
These results could be useful in different applications were the samples
require to be solved in water or other solvents.
References:
[1] Daniela C. Marcano, Dmitry V.
Kosynkin, Jacob M. Berlin, Alexander Sinitskii, Zhengzong Sun, Alexander
Slesarev, Lawrence B. Alemany, Wei Lu and James M. Tour. ACS Nano, 2010, 4 (8),
pp 4806–4814
[2] Park, S., Ruoff, R.; "Chemical
methods for the production of graphenes", Nature Nanotechnology. Vol 4.
2009.
Graphene sheets were formed in water as a result of dispersion and destruction of graphite in mild conditions using a water-soluble cobalt octacarboxyphthalocyanine derivative theraphthal (TP) together with ascorbic acid (AA) in ultrasonic treatment conditions. The synthesis was carried out using different amounts of graphite, AA and TP, which were ultrasonicated in 30 mL flasks with DI water for 5 h in ultrasonic cleaner. The fact of graphite decomposition in these conditions is out of conventional concepts on classic p-p stacking interactions and/or -bonding between macrocycles and carbon phases. Destruction of graphite forming oxidized graphene is explained by free radical processes in the system TP-AA in strong cavitation conditions. Characterization of samples was made by Raman spectroscopy, Transmission Electron Microscopy (TEM) end IR.
Formation of graphene from graphite by non-standard route
Jared Rodríguez1, Oxana Kharissova1 , Boris Kharisov 2
1 Universidad Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas. 2Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas
Graphene sheets were formed in water as a result of dispersion and destruction of graphite in mild conditions using a water-soluble cobalt octacarboxyphthalocyanine derivative theraphthal (TP) together with ascorbic acid (AA) in ultrasonic treatment conditions. The synthesis was carried out using different amounts of graphite, AA and TP, which were ultrasonicated in 30 mL flasks with DI water for 5 h in ultrasonic cleaner. The fact of graphite decomposition in these conditions is out of conventional concepts on classic p-p stacking interactions and/or -bonding between macrocycles and carbon phases. Destruction of graphite forming oxidized graphene is explained by free radical processes in the system TP-AA in strong cavitation conditions. Characterization of samples was made by Raman spectroscopy, Transmission Electron Microscopy (TEM) end IR.
Non-conventional synthesis of carbon nano-ribbons by the low-temperature unfolding of MWCNTs
Andrés Solis 1, Alberto Castillo 1, Oxana Kharissova 1
1Universidad Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas
The treatment of MWCNTs with the water-soluble cobalt octacarboxyphthalocyanine derivative theraphthal (TP, a cancer therapy drug) under ultrasonic conditions in the presence of ascorbic acid (AA) led to the dispersion and unfolding of MWCNTs, producing ribbon-like nanostructures (NRs) at low temperatures .The synthesis was carried out using different amounts of slightly magnetic MWCNTs, AA and TP, which were ultrasonicated in 30 mL flasks with DI water for 5 h in ultrasonic cleaner at 42-45oC. In these conditions, even at low intensity ultrasound in cleaners (20-40 kHz), partial destruction of TP slowly takes place and it is known to be accompanied by formation of Reactive Oxygen Species (ROS). TP can be first coordinated to CNT surface via p-p-stacking through aromatic supramolecular ring or covalently through COO- group(s) of the TP molecule. Unfolding of MWCNTs in the conditions of TP/AA addition can be explained by the in situ formation of ROS in TP solutions under ultrasonic treatment and their further attack on MWCNTs surface, destroying and unfolding them forming graphene sheets and ribbons. The obtained results differ from the conventional concepts of classic p-p- stacking interactions and/or -bonding between macrocycles and carbon nanotubes. Characterization of samples was made by Raman spectroscopy, Transmission Electron Microscopy (TEM) end IR.
-bonding between macrocycles and carbon nanotubes. Characterization of samples was made by Raman spectroscopy, Transmission Electron Microscopy (TEM) end IR.
Fabrications of carbon nanoparticles vía spray pyrolysis method using metal phthalocyanines as catalyst precursors
Antonio Alanis1, Beatriz Ortega1, Oxana Kharissova1, Hugo Galindo 1
1Universidad Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas
In this work, the synthesis of carbon nanoparticles was carried out vía spray pyrolysis using toluene solution with suspended zinc, copper, nickel or magnesium phthalocyanines as precursors of metallic particles serving as catalysts for carbon phase formation. The process was conducted in a range of temperatures in a nitrogen atmosphere in a quartz tube, containing borosilicate glass supports, onto which surface the nanometric layers of nanoparticles were deposited. The samples were analyzed by SEM, TEM and IR-specroscopy; their condusctivity was measured vía Kelvin technique. The properties of formed nanolayers were analyzed according to metal nature in the phthalocyanine, temperature, carrier gas speed, and other process parameters. Possible MEMS applications of thus fabricated nanolayers are discussed.
Processing
of Micro and Nano Cellulose from soybean hulls by ultrasound method
Blanca I. Montes Mejia1, Oxana V.
Kharissova1, Boris I. Kharisov1
1Universidad
Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas. 2Universidad
Autónoma de Nuevo León, Facultad de Ciencias Químicas
In this research the results for the production of micro and
nanocellulose from husk of soy are presented by ultrasound, using methods
alkaline collection consisting of basic solution (NaOH 10% w / w), and breeding
method acid, consisting of acidic solution of HNO3 at 65% w / w, washing,
filtering and drying, and thus achieve applications husk soy which is a
byproduct of the process of obtaining soybean oil which contains about 40 %
fiber in order to develop polymeric materials with properties and applications
in the paper industry with the potential capacity to replace the cellulose from
trees and reducing the use of it and contribute to the environmental impact
decreasing cutting trees.
The samples obtained were characterized by infrared
espectoscopy(IR) and scanning electron microscopy (SEM).
Synthesis and
Bactericide Activity of Ultrafine Silver Nuclei Embedded into an Ascorbic Acid
Matrix
Guillermo Cruz-Martínez1, Enrique D. Barriga-Castro2,
Raquel Mendoza-Reséndez1,
Alberto Gómez-Treviño1, Carlos Luna1
1Universidad Autónoma de Nuevo León (UANL), Av.
Universidad S/N, San Nicolás de los Garza, Nuevo León 66450, Mexico. 2Centro de Investigación en Química
Aplicada (CIQA), Blvd. Enrique Reyna Hermosillo No. 140, Saltillo, 25294
Coahuila, Mexico
Silver nanostructured
materials have stimulated huge interest due to their interesting and
multifunctional plasmonic, surface enhancement Raman scattering (SERS) and
catalytic properties, and due to their unique biological activities, being
broad-spectrum antimicrobials [1-3]. Usually, these materials are obtained by
reduction of Ag+ ions in solution from a metal salt, typically silver nitrate,
using a reducing agent such as sodium borohydride, acid ascorbic acid or
natural plant extracts [4-6], among others. Usually these methods result in polydisperse
nanoparticles with sizes around or larger than 10 nm because silver particles with
smaller sizes exhibit a strong tendency to grow by secondary growth mechanisms
such as Ostwald ripening, irreversible aggregation and coalescence [6].
In the present investigation, we
report a facile, greener and one-pot synthesis of colloidal complexes composed
of uniform ultrafine silver nanoparticles with diameters less than 5 nm
embedded into an ascorbic acid matrix that exhibits enhanced antimicrobial
activities.
[1]
Z.-J. Jiang, et al., J. Phys. Chem. B 109 (2005) 1730–1735.
[2] S.
Link, et al., J. Phys. Chem. B 103 (1999) 3529–3533.
[3] S.
Pal, et al., Appl. Environ. Microbiol. 73 (2007) 1712–1720.
[4] S. Solomon, et al. Journal of Chemical Education, 84, 322
[5] Y. Qin, et al. Colloids
and Surfaces A: Physicochemical and Engineering Aspects, 372(1),
172-176.
[6] Luna, C., et al. Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy, 141, 43-50.
Doped penta-graphene and hydrogenation of
its related structures: a structural and electronic DFT-D study
1CICFIM-Facultad
de Ciencias Fı́sico-Matemáticas, Universidad Autónoma de Nuevo León, San
Nicolás de los Garza, NL 66450.
The structure of penta-graphene (penta-C), an irregular pentagonal
two-dimensional (2D) structure, has been predicted recently. In this work we
carried out a dispersion-corrected density functional theory (DFT-D) study of
the penta-C doped with Si, Ge and Sn atoms and its related hydrogenated penta-C
structures (H–penta-C–X). We predict various new structures as thermally stable
based on Born–Oppenheimer molecular dynamics (BOMD) calculations. Moreover,
their dynamical stability is attested by phonon dispersions spectra. In
general, we found that the bandgap value of doped structures reduces, while
H–penta-C–X show large bandgap values. This feature can be exploited for
potential uses of hydrogenated doped-penta-C structures as dielectric layers in
electronic devices.
Chiral phosphorus nanotubes: structure, bonding,and electronic
properties
H.
N. Fernández-Escamilla1, J. J. Quijano-Briones1 and A.
Tlahuice-Flores1
The study of black phosphorus nanotubes (PNTs) had been devoted to
zigzag and armchair structures, with no consideration of chiral structures to
date. In this work, we studied the structural and electronic (band structure)
properties of chiral nanotubes using a periodic plane wave-pseudopotential
approach. We found that some chiral nanotubes display similar bandgaps and
binding energies per atom (BEA) as armchair PNTs and Born–Oppenheimer molecular
dynamics (BOMD) calculations attest their thermal stability. Interestingly, we
determined that the bandgap is tuned by varying the PNTs chirality and it is not
related to their diameters. This feature can be exploited in optical and
electronic applications wherein a direct and sizable bandgap is required.
Electrically
influenced band gap in arsenene layered systems
Víctor H.
Chávez1, Edgar
Martínez-Guerra1
1CICFM-Facultad
de Ciencias Fı́sico-Matemáticas, Universidad Autónoma de Nuevo León, San
Nicolás de los Garza, NL 66450.
With the emergence of new 2D materials, more
recently phosphorene, arsenene appears
as a new candidate to be explored for electronic devices. We have studied the stability of arsenene pristine
and the effect of a transversal electric
field on its electronic properties. The calculations were performed using the Quantum Espresso code, with the GGA
exchange-correlation functional in the PBE form. We have used numerical atomic orbitals as the basis set for the
valence wavefunctions employing a
double $\zeta $-polarized basis. We use the Perdew-Becke pseudopotential for an As atom that includes the scalar-relativistic effect and
Troullier-Martins parametrization. We adopt the Monkhorst-Pack scheme for k-point sampling of Brillouin zone integrations with 25X25X1 and 25X25X1 for the
buckled/planar and puckered systems, respectively. We found that buckled and
puckered arsenene are stable and posses direct and indirect gap respectively.
The effect of the electric field on the electronic structure of the buckled arsenene is the modulation of gap,
while in puckered arsenene the gap showed to be uninfluenced by the
field.
References:
[4] Resta, R., and K. Kunc.
"Self-consistent theory of electronic states and dielectric response in
semiconductors." Physical Review B 34, no. 10 (1986): 7146.
Doped penta-graphene and hydrogenation of
its related structures: a structural and electronic DFT-D study
J. J. Quijano-Briones1, H. N.
Fernández-Escamilla1 and A. Tlahuice-Flores1
1CICFIM-Facultad
de Ciencias Fı́sico-Matemáticas, Universidad Autónoma de Nuevo León, San
Nicolás de los Garza, NL 66450.
The structure of penta-graphene (penta-C), an irregular pentagonal
two-dimensional (2D) structure, has been predicted recently. In this work we
carried out a dispersion-corrected density functional theory (DFT-D) study of
the penta-C doped with Si, Ge and Sn atoms and its related hydrogenated penta-C
structures (H–penta-C–X). We predict various new structures as thermally stable
based on Born–Oppenheimer molecular dynamics (BOMD) calculations. Moreover,
their dynamical stability is attested by phonon dispersions spectra. In
general, we found that the bandgap value of doped structures reduces, while
H–penta-C–X show large bandgap values. This feature can be exploited for
potential uses of hydrogenated doped-penta-C structures as dielectric layers in
electronic devices.
Chiral phosphorus nanotubes: structure, bonding,and electronic
properties
H.
N. Fernández-Escamilla1, J. J. Quijano-Briones1 and A.
Tlahuice-Flores1
1CICFIM-Facultad
de Ciencias Fı́sico-Matemáticas, Universidad Autónoma de Nuevo León, San
Nicolás de los Garza, NL 66450.
The study of black phosphorus nanotubes (PNTs) had been devoted to
zigzag and armchair structures, with no consideration of chiral structures to
date. In this work, we studied the structural and electronic (band structure)
properties of chiral nanotubes using a periodic plane wave-pseudopotential
approach. We found that some chiral nanotubes display similar bandgaps and
binding energies per atom (BEA) as armchair PNTs and Born–Oppenheimer molecular
dynamics (BOMD) calculations attest their thermal stability. Interestingly, we
determined that the bandgap is tuned by varying the PNTs chirality and it is not
related to their diameters. This feature can be exploited in optical and
electronic applications wherein a direct and sizable bandgap is required.
With the emergence of new 2D materials, more
recently phosphorene, arsenene appears
as a new candidate to be explored for electronic devices. We have studied the stability of arsenene pristine
and the effect of a transversal electric
field on its electronic properties. The calculations were performed using the Quantum Espresso code, with the GGA
exchange-correlation functional in the PBE form. We have used numerical atomic orbitals as the basis set for the
valence wavefunctions employing a
double $\zeta $-polarized basis. We use the Perdew-Becke pseudopotential for an As atom that includes the scalar-relativistic effect and
Troullier-Martins parametrization. We adopt the Monkhorst-Pack scheme for k-point sampling of Brillouin zone integrations with 25X25X1 and 25X25X1 for the
buckled/planar and puckered systems, respectively. We found that buckled and
puckered arsenene are stable and posses direct and indirect gap respectively.
The effect of the electric field on the electronic structure of the buckled arsenene is the modulation of gap,
while in puckered arsenene the gap showed to be uninfluenced by the
field.
Electrically
influenced band gap in arsenene layered systems
Víctor H.
Chávez1, Edgar
Martínez-Guerra1
1CICFM-Facultad
de Ciencias Fı́sico-Matemáticas, Universidad Autónoma de Nuevo León, San
Nicolás de los Garza, NL 66450.
With the emergence of new 2D materials, more
recently phosphorene, arsenene appears
as a new candidate to be explored for electronic devices. We have studied the stability of arsenene pristine
and the effect of a transversal electric
field on its electronic properties. The calculations were performed using the Quantum Espresso code, with the GGA
exchange-correlation functional in the PBE form. We have used numerical atomic orbitals as the basis set for the
valence wavefunctions employing a
double $\zeta $-polarized basis. We use the Perdew-Becke pseudopotential for an As atom that includes the scalar-relativistic effect and
Troullier-Martins parametrization. We adopt the Monkhorst-Pack scheme for k-point sampling of Brillouin zone integrations with 25X25X1 and 25X25X1 for the
buckled/planar and puckered systems, respectively. We found that buckled and
puckered arsenene are stable and posses direct and indirect gap respectively.
The effect of the electric field on the electronic structure of the buckled arsenene is the modulation of gap,
while in puckered arsenene the gap showed to be uninfluenced by the
field.
References:
[1] Kamal, C., and Motohiko Ezawa.
"Arsenene: Two-dimensional buckled and puckered honeycomb arsenic
systems." Physical Review B 91, no. 8 (2015): 085423.
[2] Drummond, N. D., Viktor Zolyomi, and V. I.
Fal’Ko. "Electrically tunable band gap in silicene." Physical Review
B 85, no. 7 (2012): 075423.
[3] Cao, Huawei, Zhongyuan Yu, and Pengfei Lu.
"Electronic properties of monolayer and bilayer arsenene under in-plain
biaxial strains." Superlattices and Microstructures 86 (2015): 501-507.
[4] Resta, R., and K. Kunc.
"Self-consistent theory of electronic states and dielectric response in
semiconductors." Physical Review B 34, no. 10 (1986): 7146.
Attendance
Dr.
Manuel García Méndez
Facultad de Ciencias Físico
Matemáticas.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
José
Raúl Rangel López
Facultad de Ciencias Biológicas.
Nuevo León, Mexico.
Helen
Lorenzo Anota
Facultad de Ciencias Biológicas.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Jacob Johny
Facultad de Ingeniería Mecánica y
Eléctrica.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Rogelio Isaí Soto Ibarra
Facultad de Ingeniería Civil.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Andrea
Ávila Ávila
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Carolina
Rodríguez Abrego
Facultad de Ciencias Biológicas.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Margarita
Idalia Hernández Villegas
Facultad de Ciencias Biológicas.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
David
Alejandro Rubio Alcántar
Facultad de Ciencias Físico
Matemáticas.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Alejandro
Melo Pineda
Facultad de Ciencias Físico
Matemáticas.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Diego Sebastián Díaz
Bocanegra
Facultad de Agronomía.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Guillermo Sáenz González
Facultad de Ciencias Físico
Matemáticas.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Verónica Berenice Martínez Olvera
Facultad de Ciencias Químicas.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Diego Armando Ramírez Rios
Facultad de Ciencias Físico
Matemáticas.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Rosa María Estrada Martínez
Facultad de Ciencias Físico
Matemáticas.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Luz Hypatia Verástegui Domínguez
Facultad de Ciencias Físico
Matemáticas.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Nallaly
Berenice Mata Carrizal
Facultad de Ciencias Físico
Matemáticas.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Enrique
Valbuena Ordóñez
Facultad de Ciencias Físico
Matemáticas.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Fernando
Guerrero Vélez
Facultad de Ciencias Físico
Matemáticas.
Universidad Autónoma de Nuevo León.
Nuevo León, Mexico.
Nuevo León, Mexico.
Marlhem Georgette Uresti
Flores
Facultad
de Ciencias Físico Matemáticas.
Universidad
Autónoma de Nuevo León.
Nuevo
León, Mexico
Claudia Marisol
Velazquez Martinez
Facultad
de Ciencias Físico Matemáticas.
Universidad
Autónoma de Nuevo León.
Nuevo
León, Mexico
