The silicon clathrate compound Ba 8 Si 46 shows superconductivity below the critical temperature ͑T c ͒ of 8 K, and the T c decreases monotonically with doping Ag. In order to reveal effects of Ag doping on the electronic states, we have applied soft x-ray photoemission spectroscopy to Ag-doped silicon clathrate compounds Ba 8 Ag x Si 46−x ͑x =0,1,3,6͒. The valence band photoemission spectra show that a Ba 5d-derived state at the Fermi level ͑E F ͒, which is prominently observed in Ba 8 Si 46 , decreases with increasing Ag content. The reduction in the peak intensity at E F with increasing Ag content is therefore in accord with the decrease of T c in Ba 8 Ag x Si 46−x. Band structure calculation using local-density approximation reproduces the observed valence band spectra of x = 0 and 6. The Si 2p and Ba 4d core-level photoemission spectra demonstrate that the valence electron of Si is attracted to the Ag site in x = 1 and the 5d electron of Ba inside the Si 24 cage is further donated to Ag in x ജ 3. Hence, Ag doping leads to the reduction of the peak at E F .
The transient receptor potential vanilloid 4 (TRPV4) cation channel, a member of the TRP vanilloid subfamily, is expressed in a broad range of tissues where it participates in the generation of Ca2+ signals and/or depolarization of the membrane potential. Regulation of TRPV4 abundance at the cell surface is critical for osmo- and mechanotransduction. Defects in TRPV4 are the cause of several human diseases, including brachyolmia type 3 (MIM:113500) (also known as brachyrachia or spondylometaphyseal dysplasia Kozlowski type [MIM:118452]), and metatropic dysplasia (MIM:156530) (also called metatropic dwarfism or parastremmatic dwarfism [MIM:168400]). These bone dysplasia mutants are characterized by severe dwarfism, kyphoscoliosis, distortion and bowing of the extremities, and contractures of the large joints. These diseases are characterized by a combination of decreased bone density, bowing of the long bones, platyspondyly, and striking irregularities of endochondral ossification with areas of calcific stippling and streaking in radiolucent epiphyses, metaphyses, and apophyses. In this review, we discuss the potential effect of the mutation on the regulation of TRPV4 functions, which are related to human diseases through deviated function. In particular, we emphasize how the constitutive active TRPV4 mutant affects endochondral ossification with a reduced number of hypertrophic chondrocytes and the presence of cartilage islands within the zone of primary mineralization. In addition, we summarize current knowledge about the role of TRPV4 in the pathogenesis of several diseases.
The purpose of this study was to understand the career motivation of secondary students in science, technology, engineering, and mathematics (STEM) by comparing Korean and Indonesian students. Effects of gender and educational level on students' STEM career motivation were also examined. To test for differences, we used Rasch analysis, 3-way ANOVA, correlation analysis, and multiple group path analysis. STEM career motivation was found to be significantly affected by interactions between country, gender, and educational level. Overall, Indonesian students had more STEM career motivation than Korean students. Korean students showed larger gender differences in STEM career motivation than Indonesian students. Resumen. Motivación de los estudiantes de secundaria para la carrera en STEM: Estudio transcultural entre Corea e Indonesia. El propósito de este estudio fue entender la motivación de los estudiantes de secundaria para la carrera en Ciencias, Tecnología, Ingeniería y Matemáticas (STEM) comparando estudiantes de Corea e Indonesia. También se examinaron los efectos de género y nivel educativo sobre la motivación de los estudiantes para la carrera en STEM. Para probar las diferencias se usó el análisis Rasch, el 3 vias ANOVA, el análisis correlacional y el análisis de ruta en grupo múltiple. La motivación para la carrera en STEM se encontró significativamente afectada por las interacciones entre país, género y nivel educativo. En general, los estudiantes indonesios tenían más motivación para la carrera en STEM que los estudiantes coreanos. Los estudiantes coreanos mostraron mayores diferencias de género en las motivaciones para la carrera en STEM que los estudiantes indonesios. Résumé
A total of nine solid-solution Zintl phases in the Ca 2−x RE x CdSb 2 (RE = Yb, Eu; 0.11(1) ≤ x ≤ 1.36(2)) system with two types of cationic mixtures have been synthesized by the Pb metal-flux method, and their crystal structures have been characterized by powder and single-crystal X-ray diffraction (PXRD and SXRD) measurements. In particular, a series of solid-solution Ca 2−x Yb x CdSb 2 (0.43(2) ≤ x ≤ 1.36(2)) compounds showed a phase-transition from the Ca 2 CdSb 2 -type to the Yb 2 CdSb 2 -type structure depending upon the Ca 2+ /Yb 2+ mixedratio. These two structure types contained nearly identical anionic structural moieties, but their spatial arrangements were distinctive. On the other hand, the three compounds in the Ca 2−x Eu x CdSb 2 (0.11(1) ≤ x ≤ 1.04(2)) system crystallized only in the Yb 2 CdSb 2type phase regardless of the Eu amounts. The observed phase-transition in the Ca 2−x Yb x CdSb 2 system can be attributed to the two kinds of stacking sequence of the octahedral [(Ca/Yb)Sb 6 ] building block and the resultant interatomic interactions between two neighboring Ca 2+ /Yb 2+ mixed-sites in two distinctive title structure types. Moreover, according to SXRD refinements, two types of mixed-cations of Ca 2+ /Yb 2+ or Ca 2+ /Eu 2+ showed noticeable site-preferences between two available atomic sites. To understand the driving force for this phase-transition and the origin of the cationic site-preference, a series of DFT calculations using the TB-LMTO-ASA method were conducted, and the resultant DOS, COHP, and ELF diagrams were thoroughly interrogated. In particular, the COHP analysis successfully supported that the observed phase-transition was triggered by the energetically unfavorable shorter (Ca/Yb)1−(Ca/Yb)1 interaction in the Yb-rich Ca 2 CdSb 2 -type phase. Moreover, the cationic site-preference in the Ca 2−x Yb x CdSb 2 system can be interpreted by the electronic-factor criterion based on the Q value of each site, whereas that in the Ca 2−x Eu x CdSb 2 system can be justified by the size-factor criterion on the basis of the size of cationic elements. The chemical compositions and the appearance of selected single-crystals were analyzed by EDS and SEM, and the thermal stability of a sample was also checked by TGA analysis.
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