Compressibility measurements of β- and β″ -alumina

The compressibilities of the a- and c-axes for sodium - and -aluminas were determined up to 10 GPa from the pressure dependence of powder X-ray diffraction measured at room temperature using synchrotron radiation as an X-ray source. Powders of sodium - and -aluminas which were prepared from grinding synthesized single crystals were used as the specimens for X-ray diffraction. The compressibilities of - and -aluminas are 1.5 ± 0.2 ×10^–12 and 1.7 ± 0.2 × 10^–12 Pa^–1 for the a-axis and 2.9 ± 0.2x10^–12 and 1.6 ± 0.2 ×10^–12 Pa^–1 for the c-axis, respectively. For the c-axis, the compressibility of -alumina is larger than that of -alumina. This experimental fact is explained by the different stacking of oxygen layers and the different content in sodium ion between - and -aluminas.     

Thermodynamic Properties of β-Sialon

The thermodynamic properties of -sialon were evaluated from the partial thermodynamic characteristics of the chemical bonds existing in the solid solution and were used to assess the temperature stability limit of -sialon and its phase boundary in the Si₃N₄–Al₂O₃ system. The results agree well with the reported experimental data.     

Thermal decomposition of β-FeOOH

β-FeOOH particles were prepared by a forced hydrolysis of the 0.1 M FeCl₃ + 5·10⁻³ M HCl solution, whereas sulfated β-FeOOH particles were prepared by forced hydrolysis of the 0.1 M FeCl₃ solution containing 5·10⁻³ M quinine hydrogen sulfate (QHS). β-FeOOH particles, as well as sulfated β-FeOOH particles, were thermally treated up to 600 °C. The samples were characterized using DTA, XRD, FT-IR and TEM. β-FeOOH particles showed a cigar-type morphology, whereas bundles of β-FeOOH needles were obtained in the presence of QHS. Heating of β-FeOOH particles at 300 °C and above yielded α-Fe₂O₃ particles. Specific adsorption of sulfate groups showed a strong effect on the thermal decomposition of β-FeOOH particles. Upon heating of sulfated particles between 300 and 500 °C the formation of an amorphous phase and a small fraction of α-Fe₂O₃ were observed. Needle-like morphology of amorphous particles in these samples was preserved. At 600 °C, α-Fe₂O₃ particles were obtained; however, they were much smaller than those obtained by heating a pure β-FeOOH.     

Preparation of β-Wollastonite Glass-Ceramics

-Wollastonite glass-ceramics was prepared by using automobile waste glass and waste shell. We solved an environmental problem using automobile waste glass and waste shell. Two different powder mixtures, automobile waste glass and waste shell, were mechanically ground in a disk-type ball mill for 4 h. After milling, the mixtures were pressed into a disk 10 mm in diameter without using binder and then heated to 850°C, 950°C, and 1050°C at a rate of 5°C/min for 1 h, respectively. Crystallinity, morphological properties, and chemical composition were observed by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), and dispersive X-ray spectrometer (EDX). -Wollastonite and sodium calcium silicate were investigated by XRD. From the results of analysis, at 1050°C for 1 h, -wollastonite crystals were significantly observed, so we knew that formation of the highest crystallized -wollastonite crystal is dependent on suitable heat-treated temperature. Mechanical property investigations were carried out on -wollastonite glass-ceramics.     

Fourth-order elastic constants of β-brass

Combinations of the fourth-order elastic constants of -brass were calculated using the measured second-order and third-order elastic constants and the expressions for the effective elastic constants of a cubic crystal obtained from finite-strain theory. The present calculations show that the Cauchy relations for the fourth-order elastic constants in -brass are not satisfied. This implies that noncentral or many-body forces occur in this material. We consider two alloys. The higher-Zn alloy shows lower magnitudes of the fourth-order elastic constants and a larger Cauchy discrepancy.Visiting scientist on leave from the Department of Physics, Indian Institute of Technology, Madras-600036, India.     

Synthesis of β-Sialon from Coal Gangue

It is worth to study the synthesis of β-Sialon from coal gangue,because coal gangue is a waste of cola production and is a high qualit kaolin contained carbon which is a perfect rasw material of contained reducer itself for synthesis of β-Sialon,The study showed that a high conversion rate of 95% from coal gangue to β-Sialon could be obtained by using process of carbothermal reuction nitridation when strictly controlled the thermodynamic conditions of synthesis,For controlling the synthesis conditions easy ,the details of the effects of pco,Po2 and T on the conversion rate of β-Sialon were discussed detailedly and the phase diagrams of oxygen pressure vs composition for Si3N4-AlN-Al2o3-SiO2 system at 1350,1500,and 1600 ℃ were constructed in the paper.     

Dielectric behaviour of thin films of β-PVDF/PZT and β-PVDF/BaTiO3 composites

Thin films of the composites formed between poly(vinylidene fluoride) (PVDF) and lead zirconium titanate (PZT) and also barium titanate with 0–3 connectivity, have been obtained by dispersion of the ceramic powder in a solution of PVDF in dimethylacetamide DMA. Evaporation of the solvent at 65 °C allowed crystallization of PVDF predominantly in the polar phase, regardless of the amount of PZT or BaTiO₃ powder added upto 40 vol %. The relative permittivity and loss index values were determined for the pure components and for the composites with different ceramic contents, in the frequency range of 100 Hz to 13 MHz. An increase in PZT or BaTiO₃ content resulted in an increase in the relative permittivity of the composites, and the experimental results are shown to be in good agreement with those calculated from the theoretical expression of Yamada et al. [1]. The de electrical conductivity of composites with different compositions was also determined.     

Preparation and characterization of β-elemene-loaded microemulsion

Intravenously injectable emulsion of β-elemene was studied in detail. Both blank and β-elemene-loaded microemulsions were prepared using a simple water titration method. The pseudoternary phase diagram was constructed for the optimization of microemulsion. The loading capacity test, dilutability test, and especially the influence of antioxidants were conducted for further optimization of β-elemene-loaded microemulsion. Transmission electron microscope showed intact and spherical microemulsion droplets. Conductivity and viscosity measurements were used to study the phase behaviors of β-elemene-loaded microemulsions, providing convincing explanation. In vitro release study showed that β-elemene was steadily released until 12?h, which most fitted the first order.     

Gas pressure sintering of β-silicon nitride

The sintering behaviour of -Si₃N₄ powder was investigated in 980 kPa (10 atm) nitrogen at 1800–2000 °C. It is shown that -Si₃N₄ has a higher sinterability than the finer -Si₃N₄. The solution of small grains and reprecipitation on large grains occurred during sintering at >1600 °C. The rate-determining step in the liquid-phase sintering is believed to be the diffusion of material through the liquid phase at grain boundaries. There was no abnormal grain growth during gas pressure sintering of -Si₃N₄. The microstructures of gas pressure sintered materials from -Si₃N₄ were more uniform than those from -Si₃N₄. The densification mechanism of -Si₃N₄ is discussed in relation to that of -Si₃N₄.     

Top-down study of β2-microglobulin deamidation

Although differentiation of the isomeric Asn deamidation products (Asp and isoAsp) at the peptide level by electron capture dissociation (ECD) has been well-established, isoAsp identification at the intact protein level remains a challenging task. Here, a comprehensive top-down deamidation study is presented using the protein beta2-microglobulin (β(2)M) as the model system. Of the three deamidation sites identified in the aged β(2)M, isoAsp formation was detected at only one site by the top-down ECD analysis. The absence of diagnostic ions likely resulted from an increased number of competing fragmentation channels and a decreased likelihood of product ion separation in ECD of proteins. To overcome this difficulty, an MS(3) approach was applied where a protein ion was first fragmented by collisionally activated dissociation (CAD) and the resulting product ion was isolated and further analyzed by ECD. IsoAsp formation at all three deamidation sites was successfully identified by this CAD-ECD approach. Furthermore, the abundance of the isoAsp diagnostic ion was found to increase linearly with the extent of deamidation. These results demonstrated the potential of ECD in the detection and quantitative analysis of isoAsp formation using the top-down approach.     

Inclusion Complexation of Nimesulide with β-Cyclodextrins

Nimesulide (NM), a nonsteroidal anti-inflammatory drug (NSAID) has poor aqueous solubility. The present study describes the complexation of NM with β-cyclodextrin (β-CD) and its derivative hydroxypropyl β-cyclodextrin (HPβ-CD). The complexation was studied by phase solubility method, Fourier transformed infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). The complexes were prepared by a freeze-drying technique. The in vitro dissolution rate of drug–HPβ-CD complex was faster compared to the drug–β-CD complex and drug alone.     

Sintering and mechanical properties of β-wollastonite

Detailed microstructural studies have been carried out on porous -wollastonite (CaSiO₃) ceramics with 40–60% of the theoretical density. Xonotlite (Ca₆Si₆O₁₇(OH)₂) was used as starting material, and the reaction and sintering behaviour were systematically examined in the range 800–1200 °C in air. Analysis of the mechanical properties showed that the strength degradation of -wollastonite ceramics was certainly induced by the change of microstructure. Isothermal annealing at 1100 °C, however, did not preferentially affect the microstructure or the mechanical properties of sintered -wollastonite. These observations lead to the conclusion that the measured bending strength and Vickers hardness of porous -wollastonite ceramics can be substantially modified and improved by controlling the microstructure, in particular due to the shape of randomly oriented grains in the matrix.     

Diffraction studies of β″-magnesium sialon

The compositions of high magnesium content -magnesium sialon crystals within the 3M/4X plane of the Mg-Si-Al-O-N system indicate some form of metal atom ordering wihtin the structure. Although it is not possible using X-ray diffraction to detect weak additional reflections arising from the ordering between magnesium, aluminium, and silicon atoms, such weak reflections are revealed on electron diffraction photographs for a phase, resulting in a tripling of the hexagonal latticec-dimension. These show to have a structure very similar to rhombohedral willemite (Zn₂SiO₄), with the (Mg, Al) metal atoms ordered with respect to the silicon atoms in a 21 ratio. However, there are some additional weak diffraction spots with indices not obeying the rhombohedral condition of –h+k+l=3n. It is proposed that the structure of this is identical to that of willemite and the extra spots are a result of some form of twinning, which implies the existence of ordered microdomains.     

The effect of titanium additions onM s of β-CuZn

The effect of titanium additions to binary -CuZn alloys was investigated: the concentration range of at high temperatures (860° C), solid solution hardening of this phase, and the change in martensite temperature,M _s. Titanium in solution produces considerable solid solution hardening, both by replacing copper or zinc. Only replacement of zinc leads to a constant or increasingM _s, while replacing copper decreases it. Ageing of the -phase causes strong hardening and a decrease inM _s. The results have been interpreted considering the role of thermodynamic and mechanical properties in determiningM _s.     

Combined infra-red and X-ray studies of β-silicon nitride and β′-sialons

Previous investigations of the replacement of silicon by aluminium and nitrogen by oxygen in -silicon nitride have been based primarily on X-ray powder diffraction studies. In the present work this technique is coupled with parallel infra-red studies. X-ray analyses of sialons over a wide composition range confirm previous observations that increasing substitution of aluminium for silicon and nitrogen for oxygen in -silicon nitride is accompanied by an increase in cell size, with no evidence of any other structural modification. Parallel infra-red analyses show shifts in certain of the infra-red absorption bands to lower wavenumbers as the degree of substitution increases. Changes in the infrared spectra at the composition Si₂Al₄N₄O₄ indicate structural modifications which are not apparent from the X-ray investigations. It is suggested that these changes are a result of the ordering of the different atom types at this composition.     

Effects of amines on the formation of β-ferric oxide hydroxide

Colloidal particles of -ferric oxide hydroxide (-FeOOH) were prepared by ageing an FeCl₃ solution at 100°C in the presence of various amines with different numbers of nitrogen atoms. The particle and crystallite sizes of the formed -FeOOH decreased with increasing concentration of amines, but the particles produced contained no amine. The influence of triethanolamine on the growth of -FeOOH particles was more marked than those of ethylenediamine, diethylenetriamine and triaminotriethylamine. The adsorption isotherms of nitrogen and water on the formed particles of different size were measured and surface fractal analysis was performed.