Crystallization Processes in Composite Biomaterials

The crystallization processes in composite biomaterials containing fluorapatite (FA) and gel glasses (GG) have been investigated. Using the sol-gel method three gel-glasses have been synthesized: ZnO·SiO₂, ZnO·Al₂O₃·2SiO₂ and ZnO·CaO·2SiO₂. The composites have been prepared from GG and FA in different mole ratios and each of them treated at 950°C, 1050°C, 1150°C and 1250°C. From the XRD analysis of the composites it has been established that fluorapatite is present as a major crystalline phase. The XRD patterns and the IR spectra of the pure GG systems have been studied at 200°C, 600°C and 800°C. The surface of the samples has been analyzed before and after the in vitro experiments using SEM. An amorphous layer has been observed on the surface of each of the treated samples. The element concentration and the solubility of the samples have been analyzed after the in vitro experiments by Atomic Absorption Spectroscopy (AAS).     

激光探针电感耦合等离子体质谱分析全岩碱融玻璃的微量元素

建立了一种利用激光探针电感耦合等离子体质谱直接分析岩石碱融玻璃的微量元素分析方法；选用＾５５Ｍｎ作内标，分别以ＧＳＲ－１和ＧＳＲ－３为外标测定ＪＧ－１ａ和ＪＢ－３中的３３个微量元素；该分析方法的检出限为１ｎｇ／ｇ－１２０μｇ／ｇ。单点分析结果显示，除Ｓｃ，Ｎｉ，Ｇａ，Ｎｂ，Ｈｆ，Ｔａ及Ｇｄ，Ｔｍ，Ｌｕ等重稀土元素２人余元素的分析精度均好于１０％，准确度在±１０％以内；９次测量的平均值中，绝大多数的     

Thermal properties of oxide

To evaluate the thermal stability of oxide glasses, various criteria have been used. Not only the simple parameters, as characteristic temperatures and values of activation energy and enthalpy changes, but also the combined criteria E/RTp and kf(T) have been taken into account. Three glasses with the composition of Li₂O·2SiO₂ (a), Li₂O_·2SiO₂·0.03TiO₂ (b) and Li₂O·2SiO₂·0.1TiO₂ (c) were prepared and the validity of the criteria was tested by applying them to these glasses. The results indicate that the sequence thermal stability of the studied glass system vs. crystallization depends not only on their composition but also on the used criteria. This revised version was published online in August 2006 with corrections to the Cover Date.     

Relaxation behavior of selenium based glasses

Summary Relaxation behavior of Ge_ySe_100-y (y=8 and 10) glasses related to the viscosity behavior was studied by dilatometry. The method of two consecutive temperature jumps was applied to study the volume relaxation. The relaxation response can be described by Tool-Narayanaswamy-Moynihan model and the parameters of this model h*, , x, A were determined using curve fitting method and characteristic times method. Viscosities of studied materials in the range of 10⁸-10¹³ Pas were measured by penetration method. The calculated values of activation energies of viscous flow E are close to the values of effective activation energies of relaxation h* for studied chalcogenide materials.     

The influence of the concentration of surface boron atoms on the properties of column packings with bonded C18 groups,prepared from controlled-porosity glasses II. Liquid chromatography

Summary In the preparation of C₁₈-bonded phases higher coverage densities were obtained using dimethylaminodimethyl-n-octadecylsilane than chlorodimethyl-n-octadecylsilane as the reagents. The HPLC results show the very high hydrophobicity of the materials obtained. The elution mechanism has been found to be independent of the coverage density on the boron-enriched glass surface in the range 2.3–4.0 mol/m².Originally presented at the 15th International Symposium on Chromatography, October 1–5, 1984, Nürnberg     

人工控制液相金属纳米粒子的组装

液相中金属纳米粒子或团簇粒子的研究是现代化学和物理学的一个重要方面, 是对气相和真空中纳米粒子研究的补充。由于受到介质的强烈影响, 体系更为复杂, 然而却有了人工控制纳米粒子的大小和结构的可能性。本文介绍利用电离辐射或光化学方法还原金属离子在液相中制备金属纳米粒子, 通过调节介质的组成及介质的性质(如pH 值等) ,可以有效地控制其颗粒度大小, 并有可能最终控制纳米粒子的结构。该方法还具有颗粒度分布均匀、无须添加化学还原剂以及可以制备纳米合金粒子等优点。利用脉冲式辐照(脉冲辐解技术) 可以对液相中金属纳米粒子形成的化学反应机理进行深入的基础研究。     

碘化亚铜微晶掺杂硅酸盐玻璃的制备及其光学性质

采用可分相的Na2O－Al2O3－B2O3－SiO2系为基础玻璃，以CuO／SnO、NaI为原料分别引入Cu＋、I－，成功地制备出CuI激晶掺杂硅酸盐玻璃．通过X射线粉末衍射（XRD）和高分辨透射电镜（HRTEM）分析观察到玻璃中的晶相和微晶的分布情况；由玻璃的室温透射光谱研究了玻璃的热处理条件与光吸收性的关系．实验发现，该玻璃对Nd：YAG激光器腔内自由振荡具有脉定压缩效应．     

Preparation and Optical Characterization of Organoeuropium-Doped Silica Gels

Gels have been investigated as potential matrices for rare earth luminescence. The use of complexing ligands in the sol-gel synthesis of the rare-earth doped glasses has been suggested to improve the rare earth ion luminescence properties in these matrices due to the changes in the local environment experienced by the rare earth ion. In this work, transparent Eu3+-doped gels were prepared from Si(OCH3)4 and fluorinated and/or complex-forming Eu3+ precursors (Eu(fod)3, (CF3 SO3)3Eu, (CF3CO2)Eu · 3H2O, Eu(thd)3 and Eu(acac)3). Results of emission, fluorescence line narrowing and lifetimes studies of Eu3+-doped gels derived from Si(OCH3)4 and fluorinated/chelate Eu3+ precursors are presented. The results were interpreted in terms of the evolution of the Eu3+ fluorescence in systems varying from solutions to the gels densified to 800°C. Analysis of the fluorescence decays of the 5D0 state suggests that the use of the fluorinated Eu3+ precursors reduces the hydrophobic content in the silica gels matrices. FLN studies indicate that Eu3+ clustering occurred in all densified samples.     

The slow molecular mobility in amorphous trehalose.

The molecular mobility in amorphous trehalose is studied by thermally stimulated depolarisation currents (TSDC). The effect of aging on the sub-T(g) motional processes was analysed during annealing at a given aging temperature, some degrees below the calorimetric glass transition temperature T(g)=115 degrees C. The features of different motional components of the secondary relaxation are monitored as a function of time as the glass structurally relaxes on aging. The faster components of the secondary relaxation are negligibly dependent on aging and may be ascribed to intramolecular modes of motion, while the slower motional modes show a significant dependence on aging consisting of some kind of local motions with some intermolecular nature. The dielectric strength of this relaxation decreases with increasing aging time, and there is no evidence for any modification with aging of the relaxation time of this local mobility. The TSDC study of the molecular mobility of amorphous trehalose in the temperature region of the glass transformation provides the unexpected result that no glass transition signal is observable in this temperature region.     

Color Centers in Alkali Borate Glasses Containing Cobalt,Nickel, or Copper

The absorption spectra and the magnetic moments of Co²⁺, Ni²⁺, and Cu²⁺ in alkali borate glasses of various compositions and in halide-containing glasses have been explained from the point of view of the ligand field theory. Spectra and magnetic moments are highly dependent on the composition of the base glass; this must be ascribed to the change in the coordination of the transition-metal ions. There are far-reaching analogies with corresponding complexes in solution or in the crystalline state.