This article describes the results and discussion performed to analyze the bandgap, optoelectronic properties, and complex dielectric function of Bi2Te3 thermoelectric material, using Valence ...Electron Energy Loss Spectroscopy. A key aspect of the report presented in this article is that the properties described above have not been analyzed and reported using the Valence Electron Energy Loss Spectroscopy technique. The material’s structure was analyzed using Rietveld and High-Resolution Transmission Electron Microscopy techniques. The band gap obtained value is 0.91 eV by Valence Electron Energy Loss Spectroscopy. Whereas, values obtained by other techniques are between 0.26 and 0.92 eV for Bi2Te3. The real part (ε1) and imaginary part (ε2) of the complex dielectric function (ε * ) were measured. For ε1, the principal peak at 1.03 eV and a second peak at 1.4 eV were observed. Furthermore, the optical dielectric constant is 8.6 for (ε0 = 0 eV), which is related to electronic contributions and is given by the refractive index squared (n2).
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•The bandgap of Bi2Te3 thermoelectric material obtained value was 0.91 eV using VEELS.•Crystal structure analysis was performed by Rietveld analysis and HRTEM.•Complex dielectric function of Bi2Te3 thermoelectric was determined by VEELS.•The optical dielectric constant is 8.6 for (ε0 = 0 eV), and is given by the refractive index squared (n2).
El seudoaneurisma aórtico con infección de prótesis en aorta ascendente (PIPAA) tras cirugía cardíaca es una entidad infrecuente (0,9-2%) pero grave (mortalidad intrahospitalaria > 40%). El ...tratamiento más extendido es la cirugía con recambio protésico y terapia antibiótica adecuada a antibiograma; pero el recambio protésico en ocasiones es técnicamente inviable e incluso puede aumentar la mortalidad perioperatoria. Existen casos en los que se ha preservado la prótesis infectada con éxito terapéutico, realizándose limpieza/reparación quirúrgica local apoyada con omentoplastia. No existe consenso en la duración de la terapia médica, y el tratamiento «supresor a largo plazo» en ocasiones se complica por efectos adversos de los antibióticos.
Aportar dos nuevos casos y evaluar el tratamiento realizado tras un seguimiento a largo plazo.
Análisis descriptivo de aspectos microbiológicos, farmacológicos y resultados de la terapia realizada, en dos casos de PIPAA de pacientes intervenidos por disección de aorta (prótesis de dacrón en posición supracoronariana) y por insuficiencia y anuloectasia aórtica (tubo valvulado). Se realiza tratamiento quirúrgico conservador de la prótesis aórtica (limpieza quirúrgica, reparación del seudoaneurisma y omentoplastia), asociándose terapia antibiótica prolongada ajustada a antibiograma.
Ambos casos presentan, tras más de 1 año de seguimiento, según criterios clínicos, microbiológicos y pruebas de imagen, ausencia de signos de recidiva infecciosa, resultando la terapia adecuada. Aun sin poder establecer tiempo óptimo de tratamiento, serían razonables 6 semanas de tratamiento endovenoso seguidas de 24 semanas de terapia supresora, a ser posible oral, y valorar su retirada siempre que no existan signos de recidiva.
Biodiesel from different sources were synthetized according to transesterification method. Actually, there are different methods to characterize these fuels, but majority are physicochemical ...techniques, some of they, like water content by Karl-Fischer method are really complex. Because electrochemical techniques offer fast and accurate results, an electrochemical cell was designed and built to measure these biodiesels, in particular electrolytic conductivity, which is an important parameter that characterizes solutions in different fields of research and industry. Biodiesel obtained from castor oil present the lowest electrolytic conductivity from four evaluated.
A technique for determining the susceptibility to ganciclovir of cytomegalovirus (CMV) strains isolated in clinical samples is described. The inoculum was composed of a partially infected suspension ...of cells from a young positive culture (< 10 days), usually the first passage of the primary culture. The appropriate dilution of the cell suspension to provide a suitable inoculum was based on a previous study of five strains grown in different dilutions which provided a countable number of plaques and avoided titration of each of the isolated strains. Fifty-three strains were studied at three different dilutions. Five from patients on maintenance ganciclovir therapy with poor clinical response had a 50% inhibitory dose (ID50) between 21.46 and 13.35 μM and the remainder an ID50 between 2.31 and 10.5 μM, comparable to results obtained by other authors using susceptibility techniques with a sonicated inoculum. Three of these strains were studied by both methods using sonicated inoculum and cell suspension inoculum. The mean time which elapsed between seeding the specimen and obtaining sensitivity was 39.00 and 27.66 days, respectively. The technique reduces significantly the time involved since relatively young cultures can be studied and previous titration is not required.
Metformin is widely used in the treatment of type 2 diabetes (T2D), but its mechanism of action is poorly defined. Recent evidence implicates the gut microbiota as a site of metformin action. In a ...double-blind study, we randomized individuals with treatment-naive T2D to placebo or metformin for 4 months and showed that metformin had strong effects on the gut microbiome. These results were verified in a subset of the placebo group that switched to metformin 6 months after the start of the trial. Transfer of fecal samples (obtained before and 4 months after treatment) from metformin-treated donors to germ-free mice showed that glucose tolerance was improved in mice that received metformin-altered microbiota. By directly investigating metformin-microbiota interactions in a gut simulator, we showed that metformin affected pathways with common biological functions in species from two different phyla, and many of the metformin-regulated genes in these species encoded metalloproteins or metal transporters. Our findings provide support for the notion that altered gut microbiota mediates some of metformin's antidiabetic effects.
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