Influence of compositionally induced defects on the vibrational properties of device grade Cu2ZnSnSe4 absorbers for kesterite based solar cells

This work presents a detailed analysis of the impact of compositionally induced defects on the vibrational properties of Cu2ZnSnSe4 absorbers for kesterite based solar cells. Systematic changes in the intensity of the E and B modes located around the 170, 220, and 250 cm-1 frequency regions, which involve mostly cation vibrations, were observed and analyzed in relation to the occurrence of different kinds of defect clusters involving VCu, ZnCu, ZnSn, CuZn, and SnZn point defects. Additional changes are also interpreted in terms of the appearance of SnSe, ZnSe, and CuSe-like contributions at the 185 and 250 cm-1 spectral regions, respectively. The sensitivity of the Raman measurements to the presence of these kinds of defects corroborates the potential of Raman scattering for point defect assessment in these systems. © 2015 AIP Publishing LLCPeer ReviewedPostprint (published version

El proceso de atención psicopedagógica personalizada en el programa de tutoría académica en la UAPCI de la UAEM

Es una revista electrónica internacionalmente reconocida http://atlante.eumed.net/proceso-atencion-psicopedagogica-personalizada/ Lo que se hace constar en Málaga a 03 de abril de 2013.La investigación que se presenta tiene gran importancia en la transformación que se requiere en la educación superior mexicana, al hacer referencia al proceso de tutoría. A partir de la experiencia de la investigadora como coordinadora del programa de tutoría de la Unidad Académica Profesional de Cuautitlán Izcalli en la Universidad Autónoma del Estado de México y por el intercambio con los diferentes involucrados se determinaron algunas limitaciones, que dieron lugar a plantear como problema ¿Cómo favorecer la atención psicopedagógica personalizada de los estudiantes de la UAPCI en la UAEM, a través del programa de tutoría académica, que permita generar mayor sentido de pertenencia y por tanto genere un mejor desempeño en su aprendizaje? Para resolver este problema se trazó como objetivo general establecer un manual de procedimientos, que sustentado en una concepción pedagógica, favorezca el desarrollo del proceso de atención psicopedagógica personalizada que se ha hecho referencia. Para el desarrollo de la investigación considerada como mixta, donde desde lo cuantitativo se utilizará la investigación descriptiva, donde están presentes los métodos empíricos que permitirán reflejar las características observables y generales sobre el proceso investigado. Desde lo cualitativo predomina el método de Investigación-Acción (I-A), porque se pretende producir cambios en la realidad estudiada, es decir, lo que se desea es fundamentalmente perfeccionar la práctica pedagógica que se investiga. A través del método histórico-lógico se determinan los antecedentes históricos sobre la tutoría académica. Por medio del análisis y síntesis se establecen los referentes teóricos sobre la atención psicopedagógica personalizada de los estudiantes y la tutoría académica. Para diagnosticar la situación actual del problema se utiliza una encuesta a estudiantes de satisfacción de tutoría, así como la entrevista a profundidad a tutorados y tutores, donde a partir de los resultados a través del método inductivo-deductivo se llega a generalizaciones. El enfoque de sistema se utiliza en la argumentación de la concepción teórica propuesta y el establecimiento del manual de procedimientos que se propone. Finalmente para valorar los resultados alcanzados en la aplicación del manual de procedimientos se utiliza el criterio de expertos a través de una encuesta. Palabras clave: atención-psicopedagógica-personalizada-diferenciada. Clasificación JEL: A22, A29.SIE

Effect of Precipitation on Cryogenic Toughness of N-Containing Austenitic Stainless Steels After Aging

This chapter shows the effect of intergranular precipitation on the cryogenic toughness of N-containing austenitic stainless steels in comparison to that for 316-type austenitic stainless steels. First part of the chapter deals with the thermodynamic stability and growth kinetics of the precipitated phases in the austenite matrix based on Thermo-Calc software. To continue, the experimental evolution of precipitation for N-containing steels is compared to that of 316-type steel and the difference between them are explained based on the Thermo-Calc PRISMA-calculated results. Finally, the effect of intergranular precipitation on the cryogenic fracture toughness is also analyzed using Charpy V‐Notch impact test results. The fracture mode is also related to the precipitation characteristics

PLAN DE GESTIÓN Y MANEJO DE LOS RESIDUOS SÓLIDOS DEL DISTRITO DE LA VICTORIA, PROVINCIA DE CHICLAYO, DEPARTAMENTO DE LAMBAYEQUE 2018

Esta investigación tiene como objetivo fortalecer la gestión y manejo del servicio de limpieza pública en el distrito de la victoria para mejorar la calidad del ambiente urbano, rural y paisajístico. La metodología que se aplicó consistió en cuatro etapas: La primera etapa fue la caracterización de los residuos sólidos (trabajo en campo), la segunda fue el diagnóstico actual de la G.I.R.S (trabajo de campo). En la tercera fase se realizaron los cálculos y resultados y finalmente se desarrolló la propuesta del plan de Gestión y Manejo de los residuos sólidos del distrito de la Victoria. Los resultados obtenidos determinaron que la generación per cápita de residuos sólidos en el Distrito de la Victoria es de 0.64 kg./hab./día (15.184 ton/día), La densidad obtenida para los residuos sólidos domiciliarios del Distrito es de 205.99 kg/m3. Mientras que la generación total de los residuos no domiciliarios es de 16.572 Tn /día. Se identificó que el componente con mayor porcentaje de los residuos sólidos en toda el área de estudio fue los residuos tipo A (restos de alimentos, excremento de animales domésticos y restos de jardín) con (69.78%), seguido de los residuos tipo B (papel y cartón) con (7.21%) y los residuos de tipo C (plástico, vidrio y metal) con 21.10% Consecuentemente la Propuesta del Plan de Manejo y Gestión de Residuos Sólidos del Distrito de la Victoria, incluye Programas de reforzamiento institucional, Programas de recolección, Programas de transporte, Programas de tratamiento y disposición final, programas de capacitación y educación ambiental.Tesi

Application of Phase-Field Method to the Analysis of Phase Decomposition of Alloys

This chapter is focused on the application of the phase-field method to the analysis of phase decomposition during the isothermal aging of alloys. The phase-field method is based on a numerical solution of either the nonlinear Cahn-Hilliard equation or the Cahn-Allen equation. These partial differential equations can be solved using the finite difference method among other numerical methods. The phase-field method has been applied to analyze different types of phase transformations in alloys, such as phase decomposition, precipitation, recrystallization, grain growth, solidification of pure metals and alloys, martensitic transformation, ordering reactions, and so on. One of the main advantages of phase-field method is that this method permits to follow the microstructure evolution in two or three dimensions as the time of phase transformations progresses. Thus, the morphology, size, and size distribution could be determined to follow their corresponding growth kinetics. Additionally, the evolution of chemical composition can also be followed during the phase transformations. Furthermore, both Allen-Cahn and Cahn-Hilliard equations can be solved simultaneously to analyze the presence of ordered phases or magnetic domains in alloys

Over 10% efficient wide bandgap CIGSe solar cells on transparent substrate with Na predeposition treatment

With the recent rise of new photovoltaic applications, it has become necessary to develop specific optoelectronic properties for thin-film technologies such as Cu(In,Ga)Se2 and to take advantage of their high degree of tunability. The feasibility of efficient wide bandgap absorbers on transparent conductive oxide substrates is, in that context, of critical importance. Using an original approach based on a predeposition sodium treatment, Cu(In,Ga)Se2 absorbers fabricated by sputtering and reactive annealing with a Ga to (Ga + In) content over 0.7 and an optical bandgap above 1.4 eV are deposited on transparent fluorine-doped tin oxide films, with the insertion of an ultrathin MoSe2 layer preserving the contact's ohmicity. Different material characterizations are carried out, and a thorough Raman analysis of the absorber reveals that the sodium pretreatment significantly enhances the Ga incorporation into the chalcopyrite matrix, along with markedly improving the film's morphology and crystalline quality. This translates to a spectacular boost of the photovoltaic performance for the resulting solar cell as compared with a reference device without Na, specifically in the voltage and fill factor. Eventually, an efficiency exceeding 10% is obtained without antireflection coating, a record value bridging the gap with the state of the art on nontransparent substrates.Peer ReviewedPostprint (author's final draft

Influence of compositionally induced defects on the vibrational properties of device grade Cu2ZnSnSe4 absorbers for kesterite based solar cells

This work presents a detailed analysis of the impact of compositionally induced defects on the vibrational properties of Cu2ZnSnSe4 absorbers for kesterite based solar cells. Systematic changes in the intensity of the E and B modes located around the 170, 220, and 250 cm 1 frequency regions, which involve mostly cation vibrations, were observed and analyzed in relation to the occurrence of different kinds of defect clusters involving VCu, ZnCu, ZnSn, CuZn, and SnZn point defects. Additional changes are also interpreted in terms of the appearance of SnSe, ZnSe, and CuSe-like contributions at the 185 and 250 cm 1 spectral regions, respectively. The sensitivity of the Raman measurements to the presence of these kinds of defects corroborates the potential of Raman scattering for point defect assessment in these systems

The use of sweeteners in pregnancy: an analysis of products available in Brazil

Sweeteners are frequently used by women of reproductive age. This is a narrative review about the sweeteners currently sold in the Brazilian commerce. There is a few information on the use of saccharin and cyclamates in pregnancy and their effects on the fetus. Due to the limited information available and their carcinogenic potential in animal species, saccharin and cyclamates should be avoided during pregnancy (risk C). Aspartame has been extensively studied in animals and it is considered safe for use during pregnancy (risk B), except by women homozygous for phenylketonuria (risk C). Sucralose and acessulfame-K are not toxic, carcinogenic or mutagenic in animals, but there are no controlled studies in humans. However, since these two sweeteners are not metabolized, it is unlikely that their use during pregnancy could be harmful (risk B). Stevia, a substance extracted from a native Brazilian plant, is innocuous in animal pregnancies, but there are no controlled studies in humans (risk B). Body agents found in the composition of artificial sweeteners (mannitol, sorbitol, xylitol, erithrol, lactilol, isomalt, maltilol, lactose, fructose, maltodextrin, dextrin, and inverted sugar) are substances generally regarded as safe for human consumption. In conclusion, according to the currently available evidence, aspartame, sucralose, acessulfame-K and stevia can be safely used during pregnancy.Os adoçantes são freqüentemente utilizados por mulheres em idade reprodutiva. Esta é uma revisão narrativa da literatura a respeito dos adoçantes atualmente comercializados no mercado brasileiro. Existem poucas informações sobre o uso da sacarina e ciclamato na gestação, e seus efeitos sobre o feto. Devido às limitadas informações disponíveis e ao seu potencial carcinogênico em animais, a sacarina e o ciclamato devem ser evitados durante a gestação (risco C). O aspartame tem sido extensivamente estudado em animais, sendo considerado seguro para uso na gestação (risco B), exceto para mulheres homozigóticas para fenilcetonúria (risco C). A sucralose e o acessulfame-K não são tóxicos, carcinogênico ou mutagênicos em animais, mas não existem estudos controlados em humanos. Porém, como esses dois adoçantes não são metabolizados, parece improvável que seu uso durante a gestação possa ser prejudicial (risco B). A estévia, substância derivada de uma planta nativa brasileira, não produz efeitos adversos sobre a gestação em animais, porém não existem estudos em humanos (risco B). Os agentes de corpo usados na formulação dos adoçantes (manitol, sorbitol, xilitol, eritrol, lactilol, isomalte, maltilol, lactose, frutose, maltodextrina, dextrina e açúcar invertido) são substâncias consideradas seguras para o consumo humano. Concluindo, segundo as evidências atualmente disponíveis, o aspartame, a sucralose, o acessulfame e a estévia podem ser utilizados com segurança durante a gestação.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de ObstetríciaUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de EndocrinologiaUNIFESP, EPM, Depto. de ObstetríciaUNIFESP, EPM, Depto. de EndocrinologiaSciEL