Fabrication of 2D based pn junctions with improved performance by selective laser annealing

There is a growing body of research on transistors based on nanomaterials such as 2D transition metal dichalcogenides (TMDs) (WS2, MoS2, etc.) and carbon nanotubes (CNTs). Here we co-deposited MoS2 and WS2 as PN junctions. The deposition could be performed on a PCB (printed circuit board) with Cu electrodes. The current-voltage characteristics were obtained using an Arduino board. The effect of laser irradiation could be investigated by studying the IV curves and light sensitivity for the same kind of devices in which one of the Cu electrodes was modified by a laser. The IV curves from the devices with and without laser treatment could be compared to quantify the changes in performance

Producción verde de un poliéster alifático

En este trabajo de investigación se realizó la preparación, caracterización y evaluación del poliéster 2-metil-2,4-pentano-etanodioico. La discusión se centra en variables de síntesis como el tiempo, temperatura y composición. Se utilizó un ácido dicarboxílico y un glicol para llevar a cabo una reacción de esterificación y obtener el poliéster. Los tiempos de reacción por calentamiento convencional son elevados, aproximadamente 2 horas. Por ende, se procedió a optimizar la reacción empleando las microondas como energía alternativa, utilizando los principios de la Química Verde que tiene como fundamento minimizar el impacto ambiental de ciertas reacciones empleando formas de energía más eficiente que el calentamiento convencional o reduciendo el uso de reactivos peligrosos buscando diversos sustitutos. Lo anterior permitió que la reacción en estudio se llevará a cabo en un tiempo de 13 minutos, en este proceso se utiliza vacío a 0.3 kgf/cm² para evitar el uso de un medio desecante, la identificación del poliéster se realizó mediante Espectroscopia de Resonancia Magnética Nuclear (RMN) y de Espectroscopia Infrarrojo por Transformada de Fourier (FTIR). Los resultados obtenidos permitieron conocer la influencia de las propiedades del polímero y la relación que existe entre la relación molar y el peso molecular del polímero.In this research the preparation, characterization and evaluation of polyester 2-methyl-2,4-pentane-ethanedioic was performed. The discussion focuses on synthesis variables such as time, temperature and composition. a dicarboxylic acid and a glycol was used to carry out an esterification reaction and obtain the polyester. Reaction times by conventional heating are high, approximately 2 hours. Therefore, we proceeded to optimize the reaction using microwaves as alternative energy, using the principles of Green Chemistry whose foundation minimize the environmental impact of certain reactions using forms of energy more efficient than conventional heating or reducing the use of reagents dangerous looking various substitutes. This allowed the reaction study will take place in a time of 13 minutes in this process is used empty to 0.3 kgf/cm² to avoid the use of a drying medium identification polyester was performed by Magnetic Resonance Spectroscopy (MRI) and Infrared Spectroscopy Fourier Transform (FTIR). The results obtained allowed to determine the influence of the properties of the polymer and the relationship between the molar ratio and the molecular weight of the polymer

Use of the System S2o3 (2-) -O2 for the Leaching of Precious Metals Contained in a Mineral From Molango in the State of Hidalgo, Mexico

The newer tendencies of research, related with the leaching of precious metals, involves the use of non toxic reagents that allows the leaching of a mineral of sedimentary origin using the system S2 - O3 2- - O2. Prior to thisprocess, the mineral was characterized by Scanning Electron Microscopy (SEM) in conjunction with Energy Dispersive Spectrometry of X – rays (EDS), X- ray mapping. Finally, the chemical composition was executed by Inductively Coupled Plasma Spectrometry (ICP). According to the results obtained, it was possible to determine that the mineral studied has adequate contents of gold, palladium, silver, and platinum. And after the leaching process, it could be possible to leach the gold and palladium that it contains, getting recoveries of 90% and 85 %, respectively. In the case of silver, a redissolution or precipitation could occur during the first minutes of reaction

Static and Dynamic Critical Phenomena at a Second Order QCD Phase Transition

In QCD with two flavors of massless quarks, the chiral phase transition is plausibly in the same universality class as the classical four component Heisenberg antiferromagnet. Therefore, renormalization group techniques developed in the study of phase transitions can be applied to calculate the critical exponents which characterize the scaling behaviour of universal quantities near the critical point. This approach to the QCD phase transition has implications both for lattice gauge theory and for heavy ion collisions. Future lattice simulations with longer correlation lengths will be able to measure the various exponents and the equation of state for the order parameter as a function of temperature and quark mass which we describe. In a heavy ion collision, the consequence of a long correlation length would be large fluctuations in the number ratio of neutral to charged pions. Unfortunately, we show that this phenomenon will not occur if the plasma stays close to equilibrium as it cools. If the transition is far out of equilibrium and can be modelled as a quench, it is possible that large volumes of the plasma with the pion field correlated will develop, with dramatic phenomenological consequences. }Comment: phyzzx, 41 pages, 4 figures available as a postscript file from K.R., PUPT-1347, IASSNS-HEP-92/6

DISEÑO METODOLÓGICO PARA LA HABITABILIDAD URBANA DESDE LOS ESPACIOS PÚBLICOS DE ESTANCIA

Las ciudades actuales con una alta concentración de población, herencia de un planteamiento urbano funcionalista que modificó la morfología urbana con un detrimento de los espacios públicos y áreas verdes, originó problemas de habitabilidad. Por consiguiente, el dimensionamiento de los espacios públicos de estancia y de su componente verde recobró importancia desde finales del siglo XX, debido a los beneficios que sus funciones otorgan a las condiciones de vida de los habitantes y de las urbes. Pese a ello, hay escasez de trabajos y metodologías sobre el estudio de la habitabilidad urbana. Por lo tanto, se propone un diseño metodológico que define al verde público como elemento determinante de los espacios públicos de estancia para la habitabilidad urbana de áreas consolidadas

Nonconventional Large Deviations Theorems

We obtain large deviations theorems for nonconventional sums with underlying process being a Markov process satisfying the Doeblin condition or a dynamical system such as subshift of finite type or hyperbolic or expanding transformation

The 6-GHz multibeam maser survey III: comparison between the MMB and HOPS

We have compared the occurrence of 6.7-GHz and 12.2-GHz methanol masers with 22-GHz water masers and 6035-MHz excited-state OH masers in the 100 square degree region of the southern Galactic plane common to the Methanol Multibeam (MMB) and H2O southern Galactic Plane surveys (HOPS). We find the most populous star formation species to be 6.7-GHz methanol, followed by water, then 12.2-GHz and, finally, excited-state OH masers. We present association statistics, flux density (and luminosity where appropriate) and velocity range distributions across the largest, fully surveyed portion of the Galactic plane for four of the most common types of masers found in the vicinity of star formation regions. Comparison of the occurrence of the four maser types with far-infrared dust temperatures shows that sources exhibiting excited-state OH maser emission are warmer than sources showing any of the other three maser types. We further find that sources exhibiting both 6.7-GHz and 12.2-GHz methanol masers are warmer than sources exhibiting just 6.7-GHz methanol maser emission. These findings are consistent with previously made suggestions that both OH and 12.2-GHz methanol masers generally trace a later stage of star formation compared to other common maser types

Percepções dos alunos de Enfermagem sobre flipped classroom e avaliação contínua na sala de aula de Gestão de Enfermagem

Introduction: Although the training of nurses in administration and leadership has an important repercussion on the present and the future of the profession, teaching methods are still traditional in many cases. Flipped classroom is a widely used method in nursing education but studies about its application to Nursing Administration and Management are limited. Method: Qualitative study by means of anonymous survey (dichotomous and open questions). Results: 92 % of students were shown to be satisfied with the teaching methodology and 92.9 % with the assessment. Only 31.5 % had used it previously but 83 % would like to use it in more subjects. The students showed that the methodology used had improved their opinion about the content and had increased their perception its usefulness. Conclusion: The participating students have been shown to be satisfied with flipped method and continuous assessment. These teaching strategies can help motivate nursing students towards the subject of Nursing Administration and Management, which can encourage them to pursue postgraduate training and professional practice in this area.Introducción: Si bien la formación de enfermeros en Administración y Gestión tiene una importante repercusión en el presente y el futuro de la profesión, los métodos de enseñanza siguen siendo tradicionales en muchos casos. El aula invertida es un método ampliamente utilizado en la educación de enfermería, pero los estudios sobre su aplicación a la administración y gestión de enfermería son limitados. Método: Estudio cualitativo mediante cuestionario anónimo (preguntas dicotómicas y abiertas). Resultados: El 92 % de los estudiantes se mostró satisfecho con la metodología de enseñanza y el 92,9 % con la evaluación. Solo el 31,5 % lo había usado anteriormente, pero al 83 % le gustaría usarlo en más sujetos. Los estudiantes demostraron que la metodología utilizada había mejorado su opinión sobre el contenido y había aumentado su percepción útil del mismo. Conclusión: Los estudiantes participantes han demostrado estar satisfechos con el método de aula invertida. Estas estrategias de enseñanza pueden ayudar a motivar a los estudiantes de enfermería hacia la asignatura de Administración y Gestión de los Servicios de Enfermería, lo que puede animarlos a realizar una formación de posgrado y una práctica profesional en esta área.Introdução: Embora a educação de Enfermagem em Administração e Gestão tenha um grande impacto no presente e futuro da profissão, os métodos de ensino continuam a ser tradicionais em muitos casos. A sala de aula invertida é um método amplamente utilizado na educação em Enfermagem, mas os estudos sobre a sua aplicação à Administração e Gestão de Enfermagem são limitados. Método: Estudo qualitativo utilizando um questionário anônimo (perguntas dicotômicas e abertas). Resultados: 92% dos estudantes ficaram satisfeitos com a metodologia de ensino e 92,9% com a avaliação. Apenas 31,5% já o tinha utilizado antes, mas 83% gostariam de  utilizá-lo em mais assuntos. Os estudantes mostraram que a metodologia utilizada havia melhorado a sua opinião sobre o conteúdo e aumentado a sua percepção útil do conteúdo. Conclusão: Os estudantes participantes mostraram-se satisfeitos com o método invertido e com a avaliação contínua. Estas estratégias de ensino podem ajudar a motivar os estudantes de Enfermagem para a disciplina de Administração e Gestão de Enfermagem, o que pode encorajá-los a empreender uma educação de pós-graduação e prática profissional nesta área

Glycemic Index Trends and Clinical Implications: Where Are We Going?

Glycemic index (GI) is currently consideredas an alternative system thatclassifies food according to the carbohydratequality (CHO), measuring its absorption speed;meanwhile, glycemic load GL is a more recent termthat relates the quality and quantity of the CHO pergram of the usual consumption portion. Glycemic indexand glycemic load reduce the post-prandial glycemicimpact without the total restriction of CHO in thediet. Initially, GI was used only in patients with diabetes,currently it is also considered as a risk indicator inother pathologies. However, there is great controversydue to an inaccurate interpretation of the knowledgeabout the methodology used for its determination.The aim of this review is to elucidate this currentdebate and to expand the relationship between the GIand the risk of diabetes and other chronic diseases;thus, highlighting new prospects for its applicability inthe dietary intervention for diabetic athletes and in theproduction of functional food designed for patients withdiabetes. There is strong evidence that this indicatorhas become an innovative system for various multidisciplinaryhealth programs