MHD Effects on Non-Darcy Forced Convection Boundary Layer Flow past a Permeable Wedge in a Porous Medium with Uniform Heat Flux

The steady two-dimensional laminar forced flow and heat transfer of a viscous incompressible electrically conducting and heat-generating fluid past a permeable wedge embedded in non-Darcy high-porosity ambient medium with uniform surface heat flux has been studied. The governing equations are derived using the usual boundary layer and Bossinesq approximations and accounting for the applied magnetic filed, permeability of porous medium, variable porosity, inertia and heat generation effects. These equations and boundary conditions are non-dimenstionalized and transformed using non-similarity transformation. The resulting non-linear partial differential equations are then solved numerically subject to the transformed boundary conditions by a finite difference method. Comparisons with previously published works are performed and the results are found to be in excellent agreement. Numerical and graphical results for the velocity and temperature profiles as well as the skin friction and Nusselt number are presented and discussed for various parametric conditions

Annealing Effects on Structural and Optical Properties of Ge10Sb30Se60 Thin Film

The optical constants of as-prepared and thermally annealed Ge10Sb30Se60thin films were determined. Effect of heat treatment on the structure and optical properties of Ge10Sb30Se60 thin films in the range between the glass transition and crystallization temperature have been investigated. The glass transition and crystallization temperature of the synthesized sample was measured by non- isothermal DSC measurements. The microstructure and optical properties of these films were characterized by UV-VIS spectrum, scanning electron microscope (SEM) and X-ray diffraction (XRD). The optical band gap for as-prepared and annealed films have been calculated using Taucs low from the optical transmission and reflection spectra. The results indicate that the optical band gap Eopt increases when the annealing temperature (Ta) is lower than the glass transition temperature (Tg), while decreases with further increase of Ta. The XRD studies show that the as-prepared film is amorphous in nature, but the crystalline improved with increasing the annealing temperature. Furthermore the particle size and crystalline increases while the dislocation and strains decreases with increasing the annealing temperature. Thermal annealing was found to be accompanied by structural effects, which in turn, lead to change in the optical constants. The obtained results were explained in terms of the Mott and Davis model for amorphous materials and amorphous to crystalline structure transformations

Sobriety and Localic Compactness in Categories of L

The notions of L-sobriety and L-spatiality are introduced for the category L-BiTop of L-bitopological spaces. Such notions are used to extend the known adjunction between the category L-Top of L-topological spaces and the category Loc of locals to one between the category L-BiTop and BiLoc. Also, the concepts of localic regularity and localic compactness are introduced in the mentioned category

Fuzzy neighborhood structures on partially ordered groups

Ahsanullah (1988) showed the compatibility between group structures and I-fuzzy neighborhood systems. In this paper, we require not only that the I-fuzzy neighborhood systems be compatible with the group structures, but also compatible with the order relation, in one sense or another

Global overview of the management of acute cholecystitis during the COVID-19 pandemic (CHOLECOVID study)

Background: This study provides a global overview of the management of patients with acute cholecystitis during the initial phase of the COVID-19 pandemic. Methods: CHOLECOVID is an international, multicentre, observational comparative study of patients admitted to hospital with acute cholecystitis during the COVID-19 pandemic. Data on management were collected for a 2-month study interval coincident with the WHO declaration of the SARS-CoV-2 pandemic and compared with an equivalent pre-pandemic time interval. Mediation analysis examined the influence of SARS-COV-2 infection on 30-day mortality. Results: This study collected data on 9783 patients with acute cholecystitis admitted to 247 hospitals across the world. The pandemic was associated with reduced availability of surgical workforce and operating facilities globally, a significant shift to worse severity of disease, and increased use of conservative management. There was a reduction (both absolute and proportionate) in the number of patients undergoing cholecystectomy from 3095 patients (56.2 per cent) pre-pandemic to 1998 patients (46.2 per cent) during the pandemic but there was no difference in 30-day all-cause mortality after cholecystectomy comparing the pre-pandemic interval with the pandemic (13 patients (0.4 per cent) pre-pandemic to 13 patients (0.6 per cent) pandemic; P = 0.355). In mediation analysis, an admission with acute cholecystitis during the pandemic was associated with a non-significant increased risk of death (OR 1.29, 95 per cent c.i. 0.93 to 1.79, P = 0.121). Conclusion: CHOLECOVID provides a unique overview of the treatment of patients with cholecystitis across the globe during the first months of the SARS-CoV-2 pandemic. The study highlights the need for system resilience in retention of elective surgical activity. Cholecystectomy was associated with a low risk of mortality and deferral of treatment results in an increase in avoidable morbidity that represents the non-COVID cost of this pandemic

Determination of Optical Band Gap and Optical Constants of GexSb40-xSe60 Thin Films

GexSb40-xSe60 (where 10≤ x≤ 30 at %) thin films were prepared on glass substrates by thermal evaporation technique. X-ray diffraction analysis for as – deposited films showed that they have amorphous structure. The optical constants of the as- deposited films were calculated from optical transmittance and reflectance data in wavelength range from 400 to1200 nm. We found that both refractive index, n and extinction coefficient, k increased with increasing photon energy. Optical band gap was determined from absorption coefficient data using Tauc procedure and from the energetic distribution of the absorption coefficient. The optical absorption data indicate that the absorption mechanism is due to indirect transition. The optical gap of the as- deposited films was found to decrease monotonically with increasing Sb content , a result was interpreted on the basis of the chemical- bond approach. The dispersion of the refractive index is analyzed in terms of Wemple- DiDomenico single oscillator model. The optical dispersion parameters E0 and Ed were determined according to this model. The characteristic Urbachs parameters such as steepness parameter, σ and Urbachs energy have been determined. The real and imaginary parts of the dielectric constant in addition to the dissipation factor tan δ and the optical conductivity were also determined

Magnetohydrodynamic mixed convection of TiO2–Cu/water between the double lid-driven cavity and a central heat source surrounding by a wavy tilted domain of porous medium under local thermal non-equilibrium

Article Highlights The flow shear at the proposed model is more feasible for the heat and mass transfer than the buoyancy force. Local thermal non-equilibrium case creates inaccessible regions that disapprove the harmony in the flow behavior. The ratio of natural to forced convection is the most pertinent to the thermal nonequilibrium scenario

Global overview of the management of acute cholecystitis during the COVID-19 pandemic (CHOLECOVID study)

Background: This study provides a global overview of the management of patients with acute cholecystitis during the initial phase of the COVID-19 pandemic. Methods: CHOLECOVID is an international, multicentre, observational comparative study of patients admitted to hospital with acute cholecystitis during the COVID-19 pandemic. Data on management were collected for a 2-month study interval coincident with the WHO declaration of the SARS-CoV-2 pandemic and compared with an equivalent pre-pandemic time interval. Mediation analysis examined the influence of SARS-COV-2 infection on 30-day mortality. Results: This study collected data on 9783 patients with acute cholecystitis admitted to 247 hospitals across the world. The pandemic was associated with reduced availability of surgical workforce and operating facilities globally, a significant shift to worse severity of disease, and increased use of conservative management. There was a reduction (both absolute and proportionate) in the number of patients undergoing cholecystectomy from 3095 patients (56.2 per cent) pre-pandemic to 1998 patients (46.2 per cent) during the pandemic but there was no difference in 30-day all-cause mortality after cholecystectomy comparing the pre-pandemic interval with the pandemic (13 patients (0.4 per cent) pre-pandemic to 13 patients (0.6 per cent) pandemic; P = 0.355). In mediation analysis, an admission with acute cholecystitis during the pandemic was associated with a non-significant increased risk of death (OR 1.29, 95 per cent c.i. 0.93 to 1.79, P = 0.121). Conclusion: CHOLECOVID provides a unique overview of the treatment of patients with cholecystitis across the globe during the first months of the SARS-CoV-2 pandemic. The study highlights the need for system resilience in retention of elective surgical activity. Cholecystectomy was associated with a low risk of mortality and deferral of treatment results in an increase in avoidable morbidity that represents the non-COVID cost of this pandemic