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Self-similar conductance patterns in graphene Cantor-like structures

ISAAC RODRIGUEZ VARGAS (2017)

Graphene has proven to be an ideal system for exotic transport phenomena. In this work, we report

another exotic characteristic of the electron transport in graphene. Namely, we show that the linearregime

conductance can present self-similar patterns with well-defined scaling rules, once the graphene

sheet is subjected to Cantor-like nanostructuring. As far as we know the mentioned system is one of the

few in which a self-similar structure produces self-similar patterns on a physical property. These patterns

are analysed quantitatively, by obtaining the scaling rules that underlie them. It is worth noting that

the transport properties are an average of the dispersion channels, which makes the existence of scale

factors quite surprising. In addition, that self-similarity be manifested in the conductance opens an

excellent opportunity to test this fundamental property experimentally.

Producción Científica de la Universidad Autónoma de Zacatecas UAZ

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA electron transport in graphene conductance patterns

Electron transport in AlxGa1 xAs d-MIGFETs: Conductivity enhancement induced by magnetic field effects

ISAAC RODRIGUEZ VARGAS (2016)

The electronic structure and the transport phenomena of d-MIGFETs have been studied in

an AlxGa1 xAs host matrix. The subband structure and mobility calculations were performed

within the effective mass approximation and relative mobility formula, respectively.

Both the electronic structure and the transport properties are calculated as

dependent on the applied magnetic field (B), the aluminum molar fraction (x) and the

contact voltage in one of the gates (VC1). It was found that the mobility and conductivity

are enhanced by increasing the magnetic field for appropriate aluminum molar fraction

and contact voltage. In particular, the mobility (conductivity) is improved almost 26% (32%)

for VC1 ¼ 900 meV (850 meV), x ¼ 0.2, and B ¼ 20 T.

Producción Científica de la Universidad Autónoma de Zacatecas UAZ

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA Electron transport Mobility Conductivity AlxGa1 xAs d-MIGFET

Asymmetrical external effects on transmission, conductance and giant tunneling magnetoresistance in silicene

ISAAC RODRIGUEZ VARGAS (2018)

Electron transport in a silicene structure, composed of a pair of magnetic gates, is studied

in a ferromagnetic and antiferromagnetic configuration. The transport properties are

investigated for asymmetrical external effects like an electrostatic potential, a magnetic

field and for asymmetrical geometric structure. This theoretical study, has been done using

the matrix transfer method to calculate the transmission, the conductance for parallel and

antiparallel magnetic alignment and the tunneling magnetoresistance (TMR). In Particular,

we have found that the transmission, conductance and magnetoresistance oscillate as a

function of the width of barriers. It is also found that a best control and high values of TMR

spectrum are achieved by an asymmetrical application of the contact voltage. Besides, we

have shown that the TMR is enhanced several orders of magnitude by the combined

asymmetrical magnetization effect with an adequate applied electrostatic potential.

Whereby, the asymmetrical external effects play an important role to improve TMR than

symmetrical ones. Finally, the giant TMR can be flexibly modulated by incident energy and

a specific asymmetrical application of control voltage. These results could be useful to

design filters and digital nanodevices.

Producción Científica de la Universidad Autónoma de Zacatecas UAZ

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA Tunneling magnetoresistance Silicene Asymmetrical effects Conductance Electron transport

Photoanodes modified with reduced graphene oxide to enhance photoelectrocatalytic performance of B-TiO2 under visible light

Fotoánodos modificados con óxido de grafeno reducido para mejorar el rendimiento fotoelectrocatalítico de B-TiO2 bajo luz visible

Angel M Meléndez VICENTE RODRIGUEZ GONZALEZ (2015)

"The effect of reduced graphene oxide (rGO) content in boron-modified TiO2 nanocrystalline films on their photocatalytic activity in phenol oxidation is investigated. Visible-light-active TiO2 modified photoanodes were prepared by incorporating graphene sheets into the sol-gel reaction of B-TiO2, followed by depositing the reaction products on 304 stainless steel plates by dip-coating technique. Thin films obtained by in situ sol-gel synthesis were characterized by FESEM, GIXRD and UV–vis diffuse reflectance spectroscopy. FESEM examination showed cracked films due to the tensile stress generated by solvent evaporation. GIXRD results showed that boron in the films inhibits the growth of crystallites. Comparing to unmodified TiO2, B-TiO2/rGO showed a red shift in the band gap. The potentiodynamic anodic polarization measurements showed that graphene incorporation improved the photogenerated electron transport within the film, hence increasing the photocurrent. These enhancements are explained on the basis of the ability of graphene in promoting the charge carrier separation by transferring the photogenerated electrons from the illuminated photoanode to the substrate. The film B-TiO2/rGO obtained from the sol solution containing 0.03 wt/v% boron and 3 wt/v% graphene exhibited the highest photocurrent, which was 30 times larger compared with the photocurrent of TiO2 film."

"Se investiga el efecto del contenido de óxido de grafeno reducido (rGO) en películas de TiO2 modificadas con boro sobre su actividad fotocatalítica en la oxidación de fenol. Fotoánodos modificados de TiO2 activos a la luz visible fueron preparados incorporando hojas de grafeno en la reacción sol-gel de B-TiO2, seguido por el depósito de los productos de la reacción sobre láminas de acero inoxidable 304 por la técnica dip-coating. Las películas delgadas obtenidas por síntesis sol-gel in-situ fueron caracterizadas por FESEM, GIXRD y espectroscopia de reflectancia difusa UV-vis. La observación por FESEM mostró películas agrietadas debido al estrés mecánico generado por la evaporación del solvente. Los resultados de GIXRD mostraron que el boro en las películas inhibe el tamaño de los cristalitos. Comparando con el TiO2, el dióxido de titanio modificado presentó un desplazamiento de la banda de energía prohibida hacia el rojo. Las mediciones de polarización anódica potenciodinámica mostraron que la incorporación de grafeno mejora el transporte de electrones fotogenerados dentro de las películas compuestas incrementando así la fotocorriente. Estas mejoras se explican en base a la habilidad del grafeno para facilitar la separación de portadores de carga, transfiriendo los electrones fotogenerados desde la película iluminada de B-TiO2 hasta el sustrato. La película compuesta B-TiO2/rGO obtenida a partir de la solución con 0.03 % p/v de boro y 3 % p/v de grafeno presentó la fotocorriente más alta, la cual fue 30 veces mayor comparada con la fotocorriente de la película de TiO2."

Article

Composite thin films Modified TiO2 photoelectrode Graphene Electron transport Photoelectrocatalytic oxidation BIOLOGÍA Y QUÍMICA QUÍMICA

Plants’ Challenges in a Salinized World: The Case of Capsicum

Emanuel Bojorquez Quintal ILEANA DE LA CARIDAD ECHEVARRIA MACHADO MARIA DE FATIMA MEDINA LARA MANUEL MARTINEZ ESTEVEZ (2012)

Plants are sessile and are exposed to many environmental factors and are therefore under stress. In soils used for agriculture, salinity is a major abiotic factor that affects the growth, yield and quality of crops worldwide, mainly by the accumulation of Na+ in plant tissues and resulting loss of water. Crop peppers of the genus Capsicum have a high sensitivity to stress induced by high concentrations of salts. Throughout their entire ontogeny, pepper plants are susceptible to salt stress, but damage to the seedling is more serious and results in growth retardation and even death of the seedling. Because of the economic importance of peppers, improved tolerance to salinity stress should be the primary target of research for different pepper species. For this reason, we examined the current state of research with regard to the effect of salt stress on plants of the genus Capsicum. Pants’ Challenges in a Salinized World: The Case of Capsicum.

Article

CAPSICUM SALINITY STRESS SODIUM PEPPER TRANSPORT BIOLOGÍA Y QUÍMICA

electroactivity of few-layered graphene/polyaniline composites

ERASTO ARMANDO ZARAGOZA CONTRERAS ALEJANDRO VEGA RIOS CLAUDIA ALEJANDRA HERNANDEZ ESCOBAR FLOR YANHIRA RENTERIA BALTIERREZ (2012)

In this study, we used the dual functionality of anilinium dodecyl sulfate (DS-AN) both to exfoliate expanded graphite (EG) and to produce grapehene/polyaniline composites, in a two-step method. On the one hand, DS-AN performs the common functions of a surfactant, and on the other hand, the salt is a monomer to propagate polyaniline, that is, DS-AN is a reactive surfactant (or surfmer).

Conference proceedings

Graphene BIOLOGÍA Y QUÍMICA QUÍMICA QUÍMICA FÍSICA OTRAS

Design of a logistic model to have opportunities for improvement in the distribution of the supply chains of some organizations of the Mexico State, from the inference of good practices

Celia Nanci Torres Ángeles Atanacio Villalba Garcia Gabriela Gaviño Ortiz JUAN CARLOS BALTAZAR ESCALONA (2019)

posicionarse muy bien en el mercado. La logística es una herramienta muy importante para las organizaciones porque a través de la distribución de la cadena de suministro que controlan, los movimientos, los tiempos, los productos, el almacenamiento y la entrega del producto al cliente. El motivo de realizar este trabajo es diseñar un modelo logístico alternativo desde la ruta más corta hasta la optimización de la red como soporte en las organizaciones, para reducir los costos y el tiempo de espera del producto o servicio para sus clientes. En este análisis puede encontrar una síntesis del desarrollo histórico de los principales conceptos de logística, así como sus similitudes y diferencias principales de los sistemas 3PL y 4PL, haciendo una revisión de la propuesta desde puntos de vista de una ubicación a varios destinos. en el mismo estado y buscando la ruta más corta de una manera viable y eficiente de las variables propuestas de rutas establecidas. Luego implantar en las organizaciones del estado con estrato logístico 1PL y 2PL. Donde pueden aumentar su nivel de logística a 3PL o posteriormente a 4PL, utilizando un modelo de ruta más corto con el algoritmo de Dijkstra en su cadena de suministro.

At present, international companies have a 3PL and 4PL logistics system, where thanks to these systems they have been able to position themselves very well in the market. Logistics is a very important tool for organizations because through the distribution of the supply chain they control, the movements, times, preserves, storage and delivery of the product to the customer. The reason for conducting this chapter is to have an alternative logistic model from the shortest route through network optimization as support in organizations, to reduce costs and waiting time for the product or service to its customers. In this analysis you can find a synthesis of the historical development of the main concepts of logistics, as well as their similarities and main differences of the 3PL and 4PL systems, making a review of the proposal from points of view of a location to several destinations in the same state and looking for the shortest route in a feasible and efficient way. To then implant in the organizations of the state with 1PL and 2PL logistic stratum. Where they can increase their logistics level to 3PL or later to 4PL, using a shorter route model with Dijkstra's algorithm in their supply chain.

SIEA UAEM

Article

logistics shortest route Dijkstra algorithm optimization transport distribution CIENCIAS SOCIALES

Synthesis of carbon nano-onions doped with nitrogen using spray pyrolisis

EDUARDO TOVAR MARTINEZ JOSE ADAN MORENO TORRES JORGE VALENTIN CABRERA SALAZAR MARISOL REYES REYES Luis Felipe Cházaro Ruiz ROMAN LOPEZ SANDOVAL (2018)

"In this work, we have synthesized carbon nano-onions (CNOs) doped with nitrogen and iron carbide core. These nanostructures were synthesized pyrolysing various alcohol-benzylamine reaction mixtures. These CNOs showed a certain degree of functionalization of their surfaces, depending of the solvent, as well as n-type doping due to the inclusion of N atoms in the graphene layers. Ratios of O atoms to C atoms as well as to N atoms of the pyrolyzed solution play an important role in the morphology of the CNOs and on the phase of the iron core. Differences in the morphology of the samples have an important effect on their electrical conductivity as well as in their electrochemical properties. Synthesized samples showing well-defined CNOs, the sintering between them is negligible, have a low conductivity and higher capacitance, while those samples showing the best conductivities and lower capacitances, the CNOs in samples are connected between them by turbostratic graphite ribbons, in similar way to the CNOs synthesized from carbon nanodiamond annealed in argon atmosphere."

Article

Electrochemical performance Raman-spectroscopy Oxygen Nanotubes Reduction Nanodiamond Nanoparticles Graphene Soot Microscopy BIOLOGÍA Y QUÍMICA QUÍMICA QUÍMICA

Study of the optical properties of dielectric-graphene-dielectric multilayer quasi-periodic structures: Thue-Morse case

IRERI AYDEE SUSTAITA TORRES ISAAC RODRIGUEZ VARGAS JESUS MADRIGAL MELCHOR (2017)

Potential applications in optoelectronics had generated a great interest on the study of graphene optical properties. Along with this, graphene has exceptional properties such as high mobility and optical transparency, flexibility, mechanical robustness, etc. Due to these properties, graphene could be used in different devices such as transparent conductors, organic light-emitting diodes, photodetectors, touch screens, saturable absorbers and ultrafast lasers. A transfer-matrix method is used in order to calculate graphene optical properties, such as transmission, and absorption in the infrared region. The quasi-periodic structure consists in intercalated graphene sheets between two consecutives dielectrics. The dielectric materials follow the Thue-Morse sequence (ThMo). The graphene sheets are described by the optical conductivity considering interband and intraband transitions. The structure of the spectra depends strongly on the number of sequence generation, width of the different dielectrics and dielectric permittivity. In our case, the infrared region corresponds to a chemical potential greater than kT. In the calculated spectra, the geometrical properties of the Thue-Morse sequence can be observed. We obtain absorption bands well defined.

En este estudio se usó el método de Matriz de Transferencia para calcular las propiedades ópticas de Transformación y Absorción en la región infrarroja. La estructura estudiada consiste en un arreglo cuasi-periódico intercalando láminas de grafeno entre dos dieléctricos consecutivos. Los materiales dieléctricos siguen una secuencia Thue-Morse (ThMo). Las láminas de grafeno son descritas por medio de su conductividad óptica considerando las transiciones interbanda e intrabanda. La estructura de los espectros depende fuertemente del número de generación, espesor de los diferentes dieléctricos y de la permitividad de los dieléctricos. En nuestro caso, en la región infrarroja corresponde a una región donde el potencial químico del grafeno es mucho mayor que kT. En los espectros obtenidos, las propiedades geométricas de la secuencia Thue-Morse puede ser observada. Nosotros obtenemos bandas de absorción bien definidas.

Producción Científica de la Universidad Autónoma de Zacatecas UAZ

Article

INGENIERÍA Y TECNOLOGÍA Multilayer system Graphene Quasi-regular Thue-Morse