Pressure-Driven Band Gap Narrowing in Rb₂AgPdCl₅: Toward the Shockley–Queisser Limit of Lead-free Double Perovskites

Hydrostatic pressure is an effective tool that can give rise to novel crystal structures and physical properties. This study presents the structural, electronic, and optical properties of electronically one-dimensional (1D) double perovskite Rb2AgPdCl5 (A2BB′X5) under hydrostatic pressure. At ambient pressure, Rb2AgPdCl5 shows a band gap of 2.20 eV (0.65 eV) at the HSE06 + SOC (PBE) level of theory, and effective carrier masses are 0.44 and 0.64 mo (where mo is the rest mass of an electron) for electrons and holes, respectively. Upon applying the hydrostatic pressure, we observe band gap narrowing, accompanied by piezochromism, and a reduction in effective carrier masses. At a relatively low pressure of 9 GPa, Rb2AgPdCl5 achieves the optimum band gap of 1.36 eV, which is close to the optimal value of the Shockley–Queisser limit. The band gap reduction is attributed to the contraction of the metal-halide bond length and the increase in the overlap of atomic orbitals. The decrease in effective carrier masses is attributed to the increase in the width of conduction and valence bands, indicating improved transport of carriers with external pressure. This work elucidates the effects of hydrostatic pressure on the sensitive tuning of the electronic and optical properties of this perovskite family for vivid optoelectronic applications

Pseudoxanthoma elasticum: A rare cause of gastrointestinal bleed

Causes of obscure gastrointestinal (GI) bleed are diverse and rare. The most common cause for GI bleeding of small bowel origin is angiodysplasia, followed by tumors of the small intestine, and various other causes, including small bowel ulcers and aortienteric fistulas. Pseudoxanthoma elasticum (PXE) is a rare cause of GI bleed. It is an inherited elastic tissue disorder with degeneration of elastic fibers involving mainly skin, eyes and the cardiovascular system. Upper GI hemorrhage occurs in 13% of cases and is often resistant to nonsurgical methods of treatment. Presented herein is a case of GI bleed in a 65-year-old woman who had PXE and hyperplastic polyps in the stomach

Microbial Composition of a Traditional Fermented Wheat Preparation—Nishasta and Its Role in the Amelioration of Retinoic Acid-Induced Osteoporosis in Rats

Fermented foods have a long history of human use. The purpose of this study was to characterize the microbial composition of a traditional fermented wheat preparation—Nishasta— and to explore its effect in retinoic acid-induced osteoporosis in Wistar rats. The sample was suspended in sterile water (10% w/v), mixed thoroughly, filtered, and gradually diluted. Aliquots of dilutions were cultured in MRS (DeMan–Rogosa–Sharpe) medium, and colonies with similar morphologies were subjected to DNA extraction. The 16S rRNA gene of the isolates was amplified by polymerase chain reaction, checked by agarose gel electrophoresis, and finally identified by sequencing. Anti-osteoporosis screening of Nishasta was carried out in female Wistar rats using retinoic acid as an inducer (70 mg/kg, p.o. once a day for 14 days). Its effect on bone health parameters was determined. The bone metabolism markers such as hydroxyproline (HOP), tartrate-resistant acid phosphatase (TRACP), and alkaline phosphatase (ALP) were evaluated. The results of microbial characterization revealed the presence of ten clones of Lactobacillus plantarum in the fermented preparation with L. plantarum NF3 as the predominant strain. The average microbial count was 2.4 × 103 CFU/g. Retinoic acid administration led to a marked disorder of various bone health markers in rats. It also increased the levels of urine calcium and phosphorus, indicating increased bone destruction. Treatment with fermented wheat (at 200, 100, and 50 mg/kg doses, p.o. daily for 42 days after the induction of osteoporosis) improved bone mineral density in a dose-dependent manner. It also improved the bone microstructure and reduced the levels of ALP, TRACP, and HOP. Micro-CT revealed that it reduced trabecular separation and increased the percent bone volume, trabecular numbers, trabecular thickness, and bone mineral density in the rats. The results showed that the fermented wheat promoted bone formation and prevented bone resorption. Our findings clearly established the effectiveness of Nishasta against osteoporosis in Wistar rats that can be partly attributed to the improved gut calcium absorption and microbiota composition

Static and Dynamical Properties of heavy actinide Monopnictides of Lutetium

In this work, density functional theory within the framework of generalized gradient approximation has been used to investigate the structural, elastic, mechanical, and phonon properties of lutetium monopnictides in rock-salt crystal structure. The spin orbit coupling and Hubbard-U corrections are included to correctly predict the essential properties of these compounds. The elastic constants, Young's modulus E, Poisson's ratio v, shear modulus G, anisotropy factor A and Pugh's ratio are computed. We found that all lutetium monopnictides are anisotropic and show brittle character. From the wave velocities along [100], [110] and [111] directions, melting temperature of lutetium monopnictides are predicted. Dynamical stability of these monopnictides has been studied by density functional perturbation theory

Epidermal growth factor receptor (<it>EGFR</it>) mutations and expression in squamous cell carcinoma of the esophagus in central Asia

<p>Abstract</p> <p>Background</p> <p>Esophageal squamous cell carcinoma (ESCC) shows geographic variations in incidence, with high incidences (>50/10⁵ person-years) in central Asia, including North Eastern Iran (Golestan) and Northern India (Kashmir). In contrast to Western countries, smoking does not appear to be a significant risk factor for ESCC in central Asia. In lung adenocarcinoma, activating mutations in the gene encoding epidermal growth factor receptor (<it>EGFR</it>) are frequent in tumors of never smokers of Asian origin, predicting therapeutic sensitivity to <it>Egfr</it>-targeting drugs.</p> <p>Methods</p> <p>In this study 152 cases of histologically confirmed ESCC from Iran (Tehran and Golestan Province) and North India (Kashmir Valley) have been analyzed for <it>EGFR</it> mutation by direct sequencing of exons 18–21. <it>Egfr</it> protein expression was evaluated by immunohistochemistry in 34 samples from Tehran and <it>HER2</it> mutations were analyzed in 54 cases from Kashmir.</p> <p>Results</p> <p>A total of 14 (9.2%) <it>EGFR</it> variations were detected, including seven variations in exons. Among those, four (2.6%) were already documented in lung cancers, two were reported as polymorphisms and one was a potentially new activating mutation. All but one variation in introns were previously identified as polymorphisms. Over-expression of <it>Egfr</it> was detected in 22/34 (65%) of tested cases whereas no <it>HER2</it> mutation was found in 54 cases from Kashmir.</p> <p>Conclusion</p> <p>Overall, <it>EGFR</it> mutations appear to be a rare event in ESCC in high incidence areas of central Asia, although a very small proportion of cases may harbor mutations predicting sensitivity to anti-<it>Egfr</it> drugs.</p