Isotherm Theoretical Study of the AlxGa1-xAsySb1-y Quaternary Alloy Using the Regular Solution Approximation for Its Possible Growth via Liquid-Phase Epitaxy at Low Temperatures.

This work presents the theoretical calculation of isotherm diagrams for quaternary alloys of III-V semiconductor compounds with the form IIIxIII1-xVyV1-y. In particular, the isotherm diagrams for the AlxGa1-xAsySb1-y quaternary alloy at low temperatures were calculated (500 °C, 450 °C, 400 °C, and 350 °C). The AlxGa1-xAsySb1-y quaternary alloy was formed from four binary compounds such as GaAs, AlAs, AlSb, and GaSb, all with direct bandgaps. The regular solution approximation was used to find the quaternary isotherm diagrams, represented in four linearly independent equations, which were solved using Parametric Technology Corporation Mathcad 14.0 software for different arsenic and antimony atomic fractions. The results support the possible growth of layers via liquid-phase epitaxy in a range of temperatures from 500 °C to 350 °C, where the crystalline quality could be improved at low temperatures. These semiconductor layers could have applications for optoelectronic devices in photonic communications, thermophotovoltaic systems, and microwave devices with good crystalline quality.

Environmental radiological baseline in unconventional oil and gas areas of Mexico.

Environmental radioactivity study was performed in unconventional hydrocarbons areas for the first time in Mexico, where four unconventional hydrocarbon exploratory wells (UHEW) are planned. This study assesses natural radiological conditions in areas around UHEW. Equivalent dose rate distribution displayed in Geographic Information System (GIS) had a maximum of 1.83 mSv a-1 and minimum of 0.04 mSv a-1, GIS was also used for introducing land usage, water resources and population occupancy. Measurements of gross alpha and gross beta in water were below the national permissible limits for drinking water 0.5 and 1.0 Bq L-1 respectively, even though samples do not correspond to drinking water. Evaluation of 238U and 226Ra in groundwater were below minimum detectable concentration 1.3 and 1.0 Bq L-1, respectively. This study provides a radiological baseline for the impact of future industrial activities, especially if exploitation of unconventional hydrocarbons produces naturally occurring radioactive material.

Obtaining of Mg-Zn Co-Doped GaN Powders via Nitridation of the Ga-Mg-Zn Metallic Solution and Their Structural and Optical Properties.

Mg-Zn co-dopedGaN powders via the nitridation of a Ga-Mg-Zn metallic solution at 1000 °C for 2 h in ammonia flow were obtained. XRD patterns for the Mg-Zn co-dopedGaN powders showed a crystal size average of 46.88 nm. Scanning electron microscopy micrographs had an irregular shape, with a ribbon-like structure and a length of 8.63 µm. Energy-dispersive spectroscopy showed the incorporation of Zn (Lα 1.012 eV) and Mg (Kα 1.253 eV), while XPS measurements showed the elemental contributions of magnesium and zinc as co-dopant elements quantified in 49.31 eV and 1019.49 eV, respectively. The photoluminescence spectrum showed a fundamental emission located at 3.40 eV(364.70 nm), which was related to band-to-band transition, besides a second emission found in a range from 2.80 eV to 2.90 eV (442.85-427.58 nm), which was related to a characteristic of Mg-doped GaN and Zn-doped GaN powders. Furthermore, Raman scattering demonstrated a shoulder at 648.05 cm-1, which could indicate the incorporation of the Mg and Zn co-dopants atoms into the GaN structure. It is expected that one of the main applications of Mg-Zn co-doped GaN powders is in obtaining thin films for SARS-CoV-2 biosensors.

Remuneração de três planos odontológicos da cidade de Maceió-AL em comparação à tabela VRPO-CFO / Remuneration of three dental plans from the city of Maceio-Al in comparison to the table VRPO-CFO

Objetivo: Investigar se o valor médio geral de remuneração ofertado por três planos odontológicos da cidade de Maceió-AL possuem defasagem, coerência ou ágio em relação ao estabelecido na tabela VRPO-CFO. Materiais e Métodos: foram utilizados três planos odontológicos da cidade de Maceió-AL,acreditando ser esses os de maior procura por parte dos profissionais, para uma comparação entre suas categorias de serviço e as da tabela VRPO, sendo calculado o valor percentual de acréscimo ou defasagem. Resultados: Nota-se que em todas as categorias de serviço, o plano que melhor remunerou foi o plano A, tendo as categorias prevenção, Endodontia, Radiologia e Dentística o menor percentual de defasagem, sendo eles 22%, 26%, 30% e 40%, respectivamente, as demais categorias apresentaram índice acima de 50%. O plano odontológico que pior remunerou, de acordo com a presente pesquisa, foio plano C, com média de defasagem geral de 65%, possuindo a categoria Diagnóstico como o serviço com maior defasagem (83%). Conclusão: Conclui-se que a remuneração dos procedimentos odontológicos,que envolvem todas as especialidades, oferecida por planos odontológicos de Maceió-AL aos Cirurgiões-Dentistas, estão abaixo dos valores determinados na tabela do VRPO-CFO.

Objective: To investigate whe ther the overall average amount of remuneration offered by three dental plans from the city of Maceió-AL have a discrepancy, consistency or goodwill in relation to the established VRPO-CFO table. Materials and Methods: three dental plans from the city of Maceió- ALwere used, believing that these are the most demanded by professionals, for a comparison betweentheir service categories and VRPO table, therefore calculating their increasement percentage valueor lag. Results: We notice that in all service categories, the plan that best remunerated was plan A,having the categories Prevention, Endodontics, Radiology and Dentistry the lowest percentage oflag, namely 22%, 26%, 30% and 40% respectively, the other categories had an index above 50%.The dental plan that pays worse, according to this research, was plan C, with an overall discrepancy average of 65%. Having the Diagnosis service category with the largest lag (83%). Conclusion: We conclude that the remuneration for dental procedures, involving all specialties offered by dental plans in Maceió (AL) to dentists, are lower than the ones determined on the VRPO-CFO table.