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 .

No abstract

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.

Six rare-earth (RE) metal-doped n-type Zintl-phase thermoelectric (TE) compounds in the Ca 5−x−y Yb x RE y Al 2 Sb 6 (RE = Pr, Nd, and Sm; 1.26 ≤ x ≤ 3.03; 0.15 ≤ y ≤ 0.45) system have been prepared using arc melting followed by the post-heat treatment, and the isotypic and homotypic crystal structures were carefully determined by the powder and single-crystal analyses. Six title compounds adopted either the Ca 5 Al 2 Bi 6 -type or Ca 5 Ga 2 As 6 -type phase in the orthorhombic Pbam space group (Z = 2, Pearson code oP26) with seven crystallographically independent atomic sites. Interestingly, the Yb-rich compounds originally crystallized in the Ca 5 Al 2 Bi 6 -type phase and maintained their structure type even after the post-heat treatment. On the other hand, the Ca-rich compounds with particular compositions adopted the Ca 5 Al 2 Bi 6 -type phase first and then underwent phase transition to the Ca 5 Ga 2 As 6 -type phase after the post-heat treatment at the high temperature. Moreover, this single-crystal to single-crystal phase transition also brought the p-type to n-type conversion of electrical transport property for the two Ca 5 Ga 2 As 6 -type title compoundsCa 3.46 Yb 1.35 Pr 0.19 Al 2 Sb 6 and Ca 3.30 Yb 1.50 Sm 0.20 Al 2 Sb 6 according to Seebeck coefficient measurements. As far as we understand, this study is the first example of producing novel n-type Zintl TE compounds by the "bypass" method through the p-type to n-type conversion of identical Zintl compounds in the A 5 M 2 Pn 6 (A = Ca, Sr, Eu, and Yb; M = Al, Ga, In; Pn = As, Sb, and Bi) system. Theoretical calculations conducted for the three hypothetical models rationalized the specific site preference of RE and the overall electronic structures. Hall effect measurements proved the n-type carrier, and the carrier concentration and carrier mobility of this Ca 5 Ga 2 As 6 -type Ca 3.46 Yb 1.35 Pr 0.19 Al 2 Sb 6 were also evaluated.

Motivation to learn is an essential element in science learning. In this study, the role of career motivation in science learning was examined. In particular, first, a science motivation model that focused on career motivation was tested. Second, the role of career motivation as a predictor of STEM track choice was examined. Third, the effect of gender and academic year on science motivation was explored. The participants of the study were 626 highschool students. We used the Rasch analysis, structural equation modeling, logistic regression, MANOVA for the statistical analyses. It was found that career motivation has direct influences on several motivational factors in science learning, such as grade motivation, need for learning, self-determination, and self-efficacy. Moreover, career motivation was found to be a predictor of students' STEM track choice. Finally, there were substantial differences in science motivation across gender and academic years. Generally, females and students in higher academic years exhibited a lower level of science motivation. Female students especially showed a low level of career motivation. The findings suggest that it is important to facilitate students' career motivations to improve their science motivation and promote long-term scientific achievement.

Three Zintl phase compounds belonging to the CaYb4Al2Sb6–x Ge x (x = 0.2, 0.5, 0.7; nominal compositions) system with various Ge-doping contents were successfully synthesized by arc-melting and were initially crystallized in the Ba5Al2Bi6-type phase (space group Pbam, Pearson codes oP26). However, after post-heat treatment at an elevated temperature, the originally obtained crystal structure was transformed into the homeotypic Ca5Ga2Sb6-type structure according to powder and single-crystal X-ray diffraction analyses. Two types of crystal structures share some isotypic structural moieties, such as the one-dimensional anionic chains formed by ∞ 1[Al2Sb8] and the void-filling Ca2+/Yb2+ mixed cations, but the slightly different spatial arrangements in each unit cell make these two structural types distinguishable. This series of title compounds is originally investigated to examine whether anionic p-type doping using Ge can successfully enhance thermoelectric (TE) properties of the Yb-rich CaYb4Al2Sb6–x Ge x series even after the phase transition from the Ba5Al2Bi6-type to the Ca5Ga2Sb6-type phase. More interestingly, we also reveal that the given structural transformation is triggered by the particularly different site-preference of Ca2+ and Yb2+ among three available cationic sites in each structure type, which is significantly affected by thermodynamic conditions of this system. Band structure and density of states analyses calculated by density functional theory using the tight-binding linear muffin-tin orbital method also prove that the Ge-doping actually increases band degeneracies and the number of resonant peaks near the Fermi level resulting in the improvement of Seebeck coefficients. Electron localization function analyses for the (0 1 0) sliced-plane and the 3D isosurface nicely illustrates the distortion of the paired-electron densities due to the introduction of Ge. The systematic TE property measurements imply that the attempted anionic p-type doping is indeed effective to improve the TE characteristics of the title CaYb4Al2Sb6–y Ge y system.