Synthesis of Ni Carbide Nanoparticles with Ni 3 C-Type Structure in Polyol Solution Containing Dispersant

Nanoparticles of Ni carbide of about 50 nm in diameter were synthesized by the reduction of Ni salt in a polyol solution in the presence of polyvinylpyrrolidone (PVP). It was found that the aggregation of nanoparticles was suppressed when PVP was added to the polyol solution during synthesis. Diffraction peaks of the fcc and hexagonal structures were observed for the specimen synthesized without PVP. On the other hand, no peaks assigned to the fcc structure and no spontaneous magnetization were observed for the specimen synthesized with 50 g/L PVP, although pure bulk Ni are fcc structure and ferromagnetic at room temperature. Additionally, small peaks were observed in the X-ray diffraction pattern at 2ª = 26.2, 35.7 and 47.8°, originated not from the impurity phase but from the hexagonal phase. The specimen synthesized with 50 g/L PVP was fundamentally identified as Ni carbide with a Ni 3 C-type structure, as small peaks mentioned above were assigned to superlattice peaks. The structure parameters of the Ni carbide were refined by Rietveld analysis. It is concluded that the formation of the Ni carbide nanoparticles with Ni 3 C-type structure in the polyol solution is enhanced by the addition of PVP

A comprehensive understanding of structure and site occupancy of Y in Y-doped BaZrO_3

Y-doped BaZrO_3 (BZY) is of the perovskite structure (ABO_3), and is promising as an electrolyte in protonic ceramic fuel cells (PCFCs). However, factors limiting its protonic conductivity have not been clarified entirely, such as the unclear site occupancy of Y. In this work, X-ray diffraction patterns were collected utilizing synchrotron radiation with an incident energy close to the energy of the Y K absorption edge. Therefore, precise Rietveld refinement was performed to determine the site occupancy of Y by the anomalous dispersion effect. The results revealed that for the stoichiometric sample of BaZr_{0.8}Y_{0.2}O_{3−δ}, Y only occupied the B-site. But in the Ba-deficient sample of Ba_{0.9}Zr_{0.8}Y_{0.2}O_{3−δ}, two perovskite phases with different compositions were observed. In the Y-poor phase, all Y occupied the B-site, while in the other greatly Y-rich and Ba-deficient phase, Y was found to occupy both A and B-sites. These results clearly indicate the tendency towards A-site occupation of Y with an increasing Ba-deficiency

X-Ray Analysis Literatures 2012

2012年に出版されたX線分析に関連する文献および情報について，X線分析技術の発展に寄与し重要であると編集委員が選抜した文献を総説としてまとめた．調査対象はe-ジャーナル，webマガジンを含む学術誌18誌，制定された規格およびX線関連メーカーの新技術情報である．各雑誌について全体的な傾向および選抜したいくつかの論文に対して論評を記した．The selected literatures about advances in X-ray analysis and X-ray analysis-related information published in 2012 were reviewed on the basis of analytical chemistry, physics, techniques, optics, instrumentation and so forth. The 18 kinds of academic journals including web-magazines, Japanese Industrial Standard (JIS), and websites of companies related with X-ray tools and/or X-ray apparatus were researched. The trend of publications related to X-ray analysis for each journal was overviewed, and some of noticeable literatures were commented

X-Ray Analysis Literatures 2011

2011年に出版されたX線分析関連文献，X線に関連した情報のなかで，編集委員がX線分析技術の発展に寄与し重要であると選抜した文献を総説としてまとめた．調査対象はe-ジャーナル，web マガジンを含む学術誌20誌，制定された規格およびX線関連メーカーの新技術情報である．各雑誌について，全体的な論評，X線分析に関する傾向から，いくつかの論文について論評を記した．The selected literatures about advances in X-ray analysis and X-ray analysis-related informations published in 2011 were reviewed on the basis of analytical chemistry, physics, techniques, optics, instrumentation and so forth. The 20 kinds of academic journals including web-magagines, Japanease Industrial Standard (JIS), and websites of companies related with X-ray tools and/or X-ray apparatus were researched. The trend of publications related to X-ray analysis for each journal was overviewed, and some of noticeable literatures were commented

Stimulation of synaptic vesicle exocytosis by the mental disease gene DISC1 is mediated by N-Type voltage-gated calcium channels

Lesions and mutations of the DISC1 (Disrupted-in-schizophrenia-1) gene have been linked to major depression, schizophrenia, bipolar disorder and autism, but the influence of DISC1 on synaptic transmission remains poorly understood. Using two independent genetic approaches-RNAi and a DISC1 KO mouse-we examined the impact of DISC1 on the synaptic vesicle (SV) cycle by population imaging of the synaptic tracer vGpH in hippocampal neurons. DISC1 loss-of-function resulted in a marked decrease in SV exocytic rates during neuronal stimulation and was associated with reduced Ca(2+) transients at nerve terminals. Impaired SV release was efficiently rescued by elevation of extracellular Ca(2+), hinting at a link between DISC1 and voltage-gated Ca(2+) channels. Accordingly, blockade of N-type Cav2.2 channels mimics and occludes the effect of DISC1 inactivation on SV exocytosis, and overexpression of DISC1 in a heterologous system increases Cav2.2 currents. Collectively, these results show that DISC1-dependent enhancement of SV exocytosis is mediated by Cav2.2 and point to aberrant glutamate release as a probable endophenotype of major psychiatric disorders

Akt1 in Osteoblasts and Osteoclasts Controls Bone Remodeling

Bone mass and turnover are maintained by the coordinated balance between bone formation by osteoblasts and bone resorption by osteoclasts, under regulation of many systemic and local factors. Phosphoinositide-dependent serine-threonine protein kinase Akt is one of the key players in the signaling of potent bone anabolic factors. This study initially showed that the disruption of Akt1, a major Akt in osteoblasts and osteoclasts, in mice led to low-turnover osteopenia through dysfunctions of both cells. Ex vivo cell culture analyses revealed that the osteoblast dysfunction was traced to the increased susceptibility to the mitochondria-dependent apoptosis and the decreased transcriptional activity of runt-related transcription factor 2 (Runx2), a master regulator of osteoblast differentiation. Notably, our findings revealed a novel role of Akt1/forkhead box class O (FoxO) 3a/Bim axis in the apoptosis of osteoblasts: Akt1 phosphorylates the transcription factor FoxO3a to prevent its nuclear localization, leading to impaired transactivation of its target gene Bim which was also shown to be a potent proapoptotic molecule in osteoblasts. The osteoclast dysfunction was attributed to the cell autonomous defects of differentiation and survival in osteoclasts and the decreased expression of receptor activator of nuclear factor-κB ligand (RANKL), a major determinant of osteoclastogenesis, in osteoblasts. Akt1 was established as a crucial regulator of osteoblasts and osteoclasts by promoting their differentiation and survival to maintain bone mass and turnover. The molecular network found in this study will provide a basis for rational therapeutic targets for bone disorders

Dopant Site Occupancy and Chemical Expansion in Rare Earth-Doped Barium Zirconate

Rare earth-doped BaZrO[3] is a very attractive material in electrochemical applications due to its proton conductive property. In this work, powder X-ray diffraction patterns of BaZr[0.8]M[0.2]O[3−δ] (M = Sc, Eu, Sm, Dy) were collected using synchrotron radiation, and also using characteristic X-ray of CuKα in dry and wet atmospheres at high temperature. Then, a combined interpretation of the diffraction patterns was established by using Rietveld refinement. The results revealed that an obvious lattice expansion was observed for BaZr[0.8]M[0.2]O[3−δ] (M = Sc, Eu, Sm, Dy) in wet O2compared with the case in dry condition, indicating a chemical expansion effect on lattice volume by incorporating water into lattice. Eu, Sm, and Dy cations occupied both A- and B-sites of BaZrO[3] crystalline lattice, whereas Sc cations were determined to occupy B-site only. These results indicate clearly an increasing tendency toward A-site occupation for the rare earth cations in BaZrO[3] with an increasing radius