RESUMEN
The change in composition and pressure, both of which lead to new desired properties by altering the structure, is particularly important for improving device performance. Given this, we focused here on the mechanical, elastic, and optoelectronic characteristics of the Cd0.75Zn0.25Se alloy using density functional theory at various pressures from 0 GPa to 20 GPa. It is found that the bulk modulus of the material rises with increasing pressure and exhibits mechanical stability as well as cubic symmetry. In addition, the increased pressure leads to a rise in the direct bandgap energy of the material from 2.03 eV to 2.48 eV. The absorption coefficient of the alloy also increases as the pressure increases, where the effective range of absorption covers the broad spectrum of light in the visible range from orange to cyan. This is due to the electronic transitions caused by the altered pressure. The optical parameters, including optical conductivity, extinction coefficient, reflection, and refractive index, are also analyzed under the influence of pressure. Based on this research, effective applications of the Cd substituted Zn-chalcogenides (CdZnSe) alloys in the fields of optoelectronics and photovoltaics are outlined, especially concerning fabricating solar cells, photonic devices, and pressure sensors for space technology.
RESUMEN
This study explores the nuclear magnetic shielding, chemical shifts, and the optoelectronic properties of the BiMnVO5 compound using the full-potential linearized augmented plane wave method within the generalized gradient approximation by employing the Hubbard model (GGA + U). The 209Bi and 51V chemical shifts and bandgap values of the BiMnVO5 compound in a triclinic crystal structure are found to be directly related to Hubbard potential. The relationship between the isotropic nuclear magnetic shielding σiso and chemical shift δiso is obtained with a slope of 1.0231 and - 0.00188 for 209Bi and 51V atoms, respectively. It is also observed that the bandgap, isotropic nuclear magnetic shielding, and chemical shifts increase with the change in Hubbard potentials (U) of 3, 4, 5, 6, and 7.
RESUMEN
[This corrects the article DOI: 10.1039/D2RA03850A.].
RESUMEN
The structural and optoelectronic characteristics of Zn1-x Cd x S (x = 0, 0.25, 0.50, 0.75, 1) semiconductors are reported using density functional theory within GGA, EV-GGA, and mBJ functionals. These semiconductors are observed in cubic symmetry at all Cd-concentrations and the lattice constant increases linearly with Cd-concentration while the bulk modulus shows a reverse behavior. These materials are direct bandgap semiconductors at all Cd-concentrations and their bandgap energy decreases from 3.67 eV to 2.59 eV. The isotropic optical properties of these direct bandgap semiconductors vary with Cd concentration as well, with absorption coefficients decreasing and absorbed near-UV light converting to visible blue light. Optical properties like refractive index, dielectric constant, conductivity, extinction coefficient, and reflectance are also displayed and discussed. These results provide useful theoretical understanding for the application of CdZnS semiconductors in photonic, photovoltaic, and optoelectronic devices.
RESUMEN
Actualmente una indefinida proporción de comunidad conoce sobre la existencia de la terapia de reemplazo renal. No obstante, a pesar de que la mayoría de los pacientes institucionales tiene acceso a ella, un gran número de los llamados "clasificados económicos" no pueden ser admitido en estos programas, con la consecuente mortalidad implicada. Emprendimos el presente estudio con el objeto de cuantificar con mayor exactitud las dimensiones de este fenómeno. Entre febrero y mayo de 1992, evaluamos prospectivamente todos los pacientes con insuficiencia renal crónica que consultaron HUSVP a quienes fue imposible ofrecerles este tratamiento. Encontramos 35 casos, 23 hombres (66 por ciento), con una edad promedio de 31+-2 años (rango 13 a 63), 17 (49 por ciento) procedían de Medellín y su área metropolitana, 23 (66 por ciento) eran casados, 24 (69 por ciento) provenían del área urbana, y 19 (54 por ciento) carecían de empleo. La etiología de la falla renal fue desconocida en 23 casos (66 por ciento). Las pruebas de función renal al momento de la evaluación fueron : nitrógeno ureico 137.4+-2.2 mg/dL (rango 60-200) y creatinina 16.3+-0.3 mg/dL (5.2-27.8). En todos los casos, la razón fundamental para no ser admitidos a diálisis o traspalnte renal fue su precaria situación socioeconómica; durante el período del estudio fueron recibidos dos enfermos en el programa de reemplazo renal, representando una satisfacción de la demanda de uno por cada 18.5 casos. En conclusión, aunque en nuestra Unidad realizamos 70 a 90 trasplantes y 6.000 a 7.000 diálisis por año, este trabajo demuestra la pobre satisfacción de la demanda de terapia de reemplazo renal en los enfermos sin seguridad social y la magnitud del problema que no logramos resolver.