Band-gap Shift In Cds Semiconductor By Photoacoustic Spectroscopy: Evidence Of A Cubic To Hexagonal Lattice Transition

The band-gap energies of the CdS semiconductor are obtained by a photoacoustic spectroscopy (PAS) technique over a range of temperature of thermal annealing (TTA), in which the evolution of the sample structure is characterized by x-ray diffraction patterns. The PAS experiment gives a set of data for the band-gap shift in the region of the fundamental absorption edge. With increasing TTA the band-gap shift increases up to a critical TTA when its slope decreases in a roughly symmetrical way. It is suggested that at this temperature a cubic to hexagonal-lattice transition occurs.64329129

Optical and Electrical Properties of Thin Films of CuS Nanodisks Ensembles Annealed in a Vacuum and Their Photocatalytic Activity

Effects on the optical, electrical, and photocatalytic properties of undoped CuS thin films nanodisks vacuum annealed at different temperatures were investigated. The chemical bath prepared CuS thin films were obtained at 40°C on glass substrates. The grain size of 13.5±3.5 nm was computed directly from high-resolution transmission electron microscopy (HRTEM) images. The electrical properties were measured by means of both Hall effect at room temperature and dark resistivity as a function of the absolute temperature 100–330 K. The activation energy values were calculated as 0.007, 0.013, and 0.013 eV for 100, 150, and 200°C, respectively. The energy band gap of the films varied in the range of 1.98 up to 2.34 eV. The photocatalytic activity of the CuS thin film was evaluated by employing the degradation of aqueous methylene blue solution in the presence of hydrogen peroxide. The CuS sample thin film annealed in vacuum at 150°C exhibited the highest photocatalytic activity in presence of hydrogen peroxide

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Thermoreflectance studies in CdNiTe nanocrystalline films

CdNiTe ternary semiconductor thin films were deposited using the cathodic erosion by radiofrequency technique (r.f. sputtering), on 7059 Corning glass substrates. Cd1-xNixTe targets with different Ni compositions in the range 0 < x < 0. 15 were used. Structural analysis in these samples using SEM and X-ray diffraction have shown that films are polycrystalline with grain sizes between 26 and 35 n

Photoluminiscence response of nanocrystalline GaAs thin films grown by R.F. magnetron sputtering in the blue-violet region

Using the transmission electron microscopy (TEM) photographs we were able to obtain the mean grain sizes in GaAs nanocrystalline films grown by the r.f. sputtering deposition technique, which were in the range between about 17 and 19 Å. The photoacoustic (PA) technique was used to measure the absorption spectra in these films. In the spectra obtained by PA spectroscopy it was possible to distinguish clearly the bands due to transitions between quantized levels. From these PA measurements and the photoluminescence emission in the films it was possible to observe a high blue shift of the absorption edge, due to the quantum confinement effects. We have for explain the behavior of shift of the absorption edge with the nanocrystals size the parabolic bands mode

Actividad fotocatalítica con luz visible de películas de TiO2 crecidas por R.F sputtering reactivo

El TiO2 es un semiconductor de energía de banda prohibida ancha con propiedades fotocatalíti-cas bien conocidas, las cuales tienen enorme potencial en procesos de control de contaminación de la fase líquida y gaseosa bajo la irradiación de luz ultravioleta. Dicha potencialidad aumentaría si el proceso fotocatalítico se pudiera dar con la presencia de luz visible. En este trabajo se reporta el crecimiento de películas delgadas de TiO2 usando sputtering reactivo de radio frecuencia (r.f.), variando la presión par-cial (O2/Ar/N) de N, con el fin de incorporar un bajo contenido de este en las mismas. La disminución del ancho de banda de energía prohibida de las películas con el contenido de N, fue obtenida usando un es-pectrofotómetro UV-Vis. La actividad fotocatalítica fue evaluada por la decoloración de una solución de azul de metileno en agua, en la cual fue inmersa cada película expuesta a la radiación de luz blanca pro-veniente de una lámpara de Xenón. La eficiencia de las películas bajo la acción de luz visible fue caracte-rizada midiendo con espectrofotómetro, la solución luego del proceso