Synthesis and Thermal Stability of Aluminum Titanate Solid Solutions

Aluminum titanate solid solutions with empirical formulas of Al₂Ti_1-xZr_xO₅, Al_6(2-x)(6+x)Si_6x/(6+x)□_6x/(6+x)TiO₅, and Al_2(1-x)Mg_xTi_1+xO₅ were synthesized by reaction sintering and annealed at 900° to 1300°C in air to evaluate the thermal stability. Substitution of Al in Al₂TiO₅ by Si and 2Al by Mg and Ti ions to form solid solutions such as AI_{6(2-x)/(6+x)l-Si}6x/(6+x)□_6x/(6+x)TiO₅, and Al_2(1-x)Mg_xTi_1+xO₅ was effective in controlling the thermal decomposition, but substitution of Ti by Zr had little effect.     

Oolong tea extract as a substitute for uranyl acetate in staining of ultrathin sections

In conventional transmission electron microscopy, uranyl acetate staining is used to enhance the cellular components. However, uranyl acetate is considered a radioactive material that is very toxic if ingested or inhaled and subject to restrictions in many countries. In an attempt to introduce a substitute for uranyl acetate, we evaluated oolong tea extract (OTE) for staining of ultrathin sections. Tissue sections from normal rat liver representing an ideal model organ were processed according to a routine electron microscopic fixation and embedding procedure. Serial ultrathin sections were cut and processed with either routine double electron staining or 0.2% OTE staining for 30–40 min at room temperature followed by lead citrate staining (OTE staining method). Transmission electron microscopy observations revealed that all sub‐cellular structures in hepatocytes were clearly visible with OTE staining and the quality of staining was highly compatible with those of routine double staining methods. It is suggested that OTE could be used as a non‐radioactive and hazard‐free substitute for uranyl acetate in transmission electron microscopy staining.     

Experiments on highly efficient operation of the auto-resonant peniotron oscillator

The auto-resonant peniotron has been theoretically expected to have a very high conversion efficiency (nearly 100%) for an ideal electron beam with an appropriate value for the velocity ratio interacting in a suitable circuit with an electromagnetic wave whose phase velocity is equal to the velocity of light in free space. This paper presents experimental results showing more than 70% electronic efficiency obtained from an auto-resonant peniotron oscillator with a magnetron type cavity.     

抗晶间腐蚀奥氏体不锈钢的晶界工程

Sensitization by chromium depletion due to chromium carbide precipitation at grain boundaries in austenitic stainless steels can not be prevented perfectly only by previous conventional techniques, such as reduction of carbon content, stabilization-treatment, local solution-heat-treatment, etc. Recent studies on grain boundary structure have revealed that the sensitization depends strongly on grain boundary character and atomic structure, and that low energy grain boundaries such a~ coincidence-site-lattice (CSL) boundaries have strong resistance to intergranular corrosion. The concept of grain boundary design and control has been developed as grain boundary engineering (GBE). GBEed materials are characterized by high frequencies of CSL boundaries which are resistant to intergranular deterioration of materials, such as intergranular corrosion. A thermomechanical treatment was tried to improve the resistance to the sensitization by GBE. A type 304 austenitic stainless steel was cold-rolled and solution-heat-treated, and then sensitization-heat-treated. The grain boundary character distribution was examined by orientation imaging microscopy (OIM). The intergranular corrosion resistance was evaluated by electrochemical potentiokinetic reactivation (EPR) and ferric sulfate-sulfuric acid tests. The sensitivity to intergranular corrosion was reduced by the thermomechanical treatment and indicated a minimum at a small roll-reduction The frequency of CSL boundaries indicated a maximum at the small reduction. The ferric sulfate-sulfuric acid test showed much smaller corrosion rate in the thermomechanical-treated specimen than in the base material. A high density of annealing twins were observed in the thermomechanical-treated specimen. The results suggdst that the therrmomechanical treatment can introduce low energy segments in the grain boundary network by annealing twins and can arrest the percolation of intergranular corrosion from the surface. The effects of carbon content and other minor elements on optimization in grain boundary character distribution (GBCD) and thermomechanical parameters were also examined during GBE.     

玫瑰花型氧化锌的软溶液合成及其发光特性

以硝酸锌和HMT为原料、乙二醇为分散剂、三乙醇胺为表面活性剂合成球形氧化锌晶粒,然后将其引入0.02mol·L-1的HMT溶液里,95℃的条件下进行长达3天的表面修饰,成功地制备出具有独特结构的玫瑰花形氧化锌晶粒。XRD、SEM以及荧光分光光度计的分析结果表明:经修饰获得的玫瑰花型氧化锌呈典型的纤锌矿结构,其直径是球形的近三倍(从600nm增长到1700nm),晶粒质量更为完善,且具有优秀的光致发光性能,仅在388nm处显示尖锐的紫外峰。此外,基于两类晶粒的形貌结构特征及反应过程,对其形成机理进行了初步推断。     

Some Functional Properties under Heating of the Globin Prepared by Carboxymethyl Cellulose Procedure

Conditions for gel formation of heated globin and inhibition of thermocoagulation of ovalbumin and bovine serum albumin by globin were investigated. Globin was highly soluble even when heated at 100°C at pH below 5. Globin also considerably inhibited thermocoagulation of ovalbumin and serum albumin near their isoelectric point. A great increase of viscosity was observed when 1% globin solution was heated at above 80°C in the narrow pH range between pH 5.2 and 5.4. Heated globin formed a transparent gel at concentration above 3% under well controlled heat conditions.     

端铣中工具进给速度的最佳化

This paper deals with the tool feed rate optimization for smoothening of cutting force in end milling of workpiece with corner and straight parts. There is a difference between the cutting force in a corner part cutting and that in a straight part cutting. The cause of this is due to the difference in the instantaneous depths of cut in both cuttings. The scheme of this study is to prevent the generation of excessive cutting force in the corner part machining by comparison with the straight part machining. By dividing the NC (Numerical Control) cutting path of the corner part and changing the tool feed rate in each division, the cutting force in the corner part has been controlled. Furthermore, the possibility of realization of a shortening in machining time has been examined.