Synthesis of terbium doped calcium phosphate nanocrystalline powders by citric acid sol–gel combustion method

Terbium doped calcium phosphate (Tb-doped CaP) nanocrystalline powders were synthesized by the citric acid sol–gel combustion method. The phase composition, morphology and luminescent property of Tb-doped CaP nanocrystalline powders were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, fluorescence spectrophotometer and fluorescence microscopy. At 700 °C, Tb-doped CaP nanocrystalline powders are composed of HAP (main phase) and β-TCP (minor phase) with Tb doping content of 0.5–4%. SEM and TEM observations show that the 4% Tb-doped CaP nanocrystalline powders are about 50–150 nm spherical particles. The 4% Tb-doped CaP nanocrystalline powders exhibit the strongest emission at 548 nm (λ_excitation = 240 nm) and show strong green fluorescence under fluorescence microscopy.     

Selective synthesis of isobutanol by means of the Guerbet reaction: Part 2. Reaction of methanol/ethanol and methanol/ethanol/n-propanol mixtures over copper based/MeONa catalytic systems

The synthesis of isobutanol via the Guerbet condensation between methanol and ethanol was studied by using sodium methoxide (MeONa) as soluble basic component and copper-based catalysts as heterogeneous dehydrogenating/hydrogenating metal species. The effect of the nature of the catalyst and the relative amount of its individual components with respect to the reacting alcohols as well as of temperature on productivity and selectivity of the process was investigated. The collected data indicated that the copper chromite/MeONa was more active than Cu-Raney/MeONa system. The reaction was shown to proceed with the formation only of n-propanol and isobutanol. Ethanol conversion up to 61% with selectivity to isobutanol up to 98.4% was obtained. The same catalytic systems were also employed in the reaction of the methanol/ethanol/n-propanol ternary mixture. Again copper chromite/MeONa resulted more active than the Cu-Raney/MeONa system. Finally, experiments were carried out on methanol/n-propanol mixtures in the presence of the copper chromite/MeONa catalytic system by recycling both the recovered solid copper component and the liquid reaction mixture for evidencing eventual copper leaching by MeONa. On the basis of the obtained results it was concluded that in the Guerbet reaction copper chromite works as heterogeneous catalyst.     

Adsorption of hydrogen on reduced copper chromite

Temperature programmed desorption and volumetric methods in static conditions were used to study hydrogen adsorption on the surface of metallic copper particles produced by the partial reduction of copper chromite CuCr₂O₄ with hydrogen. In the temperature range 300-573 K and in the range of medium surface coverages by hydrogen, the main state of adsorbed hydrogen reveals the heat of adsorption q= 78 kJ/mol and activation energy of adsorption E _a = 69 kJ/mol. In the temperature range 77-300 K, an adsorption state with lower heat and activation energy was found, indicating a non-uniformity of the copper surface within ca. 8% of the total number of surface sites. This revised version was published online in June 2006 with corrections to the Cover Date.     

糖蛋白/胆红素钙水溶性复合物的形成及光谱研究

采用傅立叶变换红外光谱(FT-IR)，结合减法、二阶导、退卷积和曲线拟合等先进光谱技术，紫外可见光谱，ICP-AES分析方法，对不同质量比的α-酸性糖蛋白(AGP)和胆红素钙(CaBR)反应后的滤液进行了研究。结果表明，AGP和CaBR之间存在着较强的相互作用，导致AGP二级结构的有序性增加，CaBR的水溶性增大，两者形成了可溶性的AGP/CaBR复合物。     

不同结构的磷酸盐对凝胶体系中草酸钙晶体物相和相组成的影响

泌尿系结石的形成是一种病理性生物矿化过程，不同地区的结石发病率在3％～15％之间。且50％(美国)至80％(中国)的人会复发。结石中约70％以上为草酸钙(CaC2O4)结石。CaC2O4结石的形成与其热力学(过饱和度)和动力学(成核、生长和聚集)因素有关。由于结石患者尿液和正常人尿液中     

肾小管上皮细胞损伤及其诱导草酸钙晶体成核

肾上皮细胞损伤可促进肾结石形成.本文采用过氧化氢(H2O2)对人类肾小管上皮细胞(HKC)进行了氧化损伤,采用扫描电子显微镜(SEM)、X射线衍射分析(XRD)和倒置显微镜观察了HKC损伤前后的形态变化及其调控草酸钙(CaOxa)晶体成核、生长的差异;采用zeta电位分析仪检测了损伤前后HKC表面的zeta电位变化.结果表明,H2O2能明显地损伤HKC,降低细胞活性,且在H2O2浓度范围0.1～0.5mmol/L、作用时间0.5～1.5h内具有明显的剂量和时间的依赖性;使用0.5mmol/LH2O2作用1.5h可使HKC损伤达到饱和状态.HKC损伤程度增加后,其诱导的晶体数量显著增加,但晶体尺寸增加不明显(P0.05),表明损伤细胞诱导尿石症形成主要是增加晶体的成核位点而非促进晶体的生长.本文所建立的HKC氧化损伤的模型有助于进一步阐明CaOxa结石形成的细胞机制.     

重金属湿法冶金过程中钙镁结晶的工业现状及相关相图研究进展

首先介绍湿法冶金和材料制备过程中钙镁结晶危害的工业现状及其对溶液化学和结晶相化学基础研究的要求,然后系统地评述相关体系溶液化学和相化学基础研究的进展.接着在作者的系统工作及文献结果分析基础上指出:钙在重金属硫酸盐体系高温溶解度的实验研究、能描述硫酸盐离子缔合的合理热力学预测模型、硫酸盐水溶液结构的光谱和量子化学研究、以及硫酸盐水溶液高温下水的活度测定等是未来研究工作的重点.这些研究工作将加深对重金属湿法冶金过程中钙镁结晶危害行为及规律的认识,为廉价、环保地避免钙镁结晶危害的新工艺开发奠定了重要基础.     

TRPC3 cation channel plays an important role in proliferation and differentiation of skeletal muscle myoblasts

During membrane depolarization associated with skeletal excitation-contraction (EC) coupling, dihydropyridine receptor [DHPR, a L-type Ca²⁺ channel in the transverse (t)-tubule membrane] undergoes conformational changes that are transmitted to ryanodine receptor 1 [RyR1, an internal Ca²⁺-release channel in the sarcoplasmic reticulum (SR) membrane] causing Ca²⁺ release from the SR. Canonical-type transient receptor potential cation channel 3 (TRPC3), an extracellular Ca²⁺-entry channel in the t-tubule and plasma membrane, is required for full-gain of skeletal EC coupling. To examine additional role(s) for TRPC3 in skeletal muscle other than mediation of EC coupling, in the present study, we created a stable myoblast line with reduced TRPC3 expression and without α1_SDHPR (MDG/TRPC3 KD myoblast) by knock-down of TRPC3 in α1_SDHPR-null muscular dysgenic (MDG) myoblasts using retrovirus-delivered small interference RNAs in order to eliminate any DHPR-associated EC coupling-related events. Unlike wild-type or α1_SDHPR-null MDG myoblasts, MDG/TRPC3 KD myoblasts exhibited dramatic changes in cellular morphology (e.g., unusual expansion of both cell volume and the plasma membrane, and multi-nuclei) and failed to differentiate into myotubes possibly due to increased Ca²⁺ content in the SR. These results suggest that TRPC3 plays an important role in the maintenance of skeletal muscle myoblasts and myotubes.     

Relativistic correlating basis sets for 57La and 89Ac

Developed and reported are compact yet efficient correlating basis sets for the ₅₇La and ₈₉Ac atoms, missing in the literature. Good performance of these correlating sets is exemplified in molecular applications to diatomic oxides and fluorides. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

Temperature dependence of structure and dynamics of the hydrated Ca2+ ion according to ab initio quantum mechanical charge field and classical molecular dynamics

Simulations using ab initio quantum mechanical charge field molecular dynamics (QMCF MD) and classical molecular dynamics using two‐body and three‐body potentials were performed to investigate the hydration of the Ca²⁺ ion at different temperatures. Results from the simulations demonstrate significant effects of temperature on solution dynamics and the corresponding composition and structure of hydrated Ca²⁺. Substantial increase in ligand exchange events was observed in going from 273.15 K to 368.15 K, resulting in a redistribution of coordination numbers to lower values. The effect of temperature is also visible in a red‐shift of the ion‐oxygen stretching frequencies, reflecting weakened ligand binding. Even the moderate increase from ambient to body temperature leads to significant changes in the properties of Ca²⁺ in aqueous environment. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010