ZrO2增韧Al2O3／SiCnano复合陶瓷的力学性能及微结构

本文对Al_2O_3/SiC nano ZrO_2(3Y)复相陶瓷的力学性能和微结构进行了研究,探讨了ZrO_2(t)应力诱导相交增韧机制和纳米粒子增韧机制相互迭加的可能性。结果表明:适量的第二相纳米粒子ZrO_2(3Y)加入对材料的微结构有很大影响,同时对材料的力学性能的提高作出贡献。     

Kinetics of CO hydrogenation over coprecipitated cobalt–alumina

The kinetics of CO hydrogenation over coprecipitated 36 wt% Co/Al₂O₃ was studied in a fixed-bed microreactor at atmospheric pressure. Intrinsic kinetic data were obtained in the initial rate region using four different CO concentrations and two different H₂/CO ratios over the 473–523 K temperature range. The surface carbide mechanism with dissociative adsorption of hydrogen as the rate controlling step gives the most plausible kinetic model among the eight different models tested. C₁–C₄ production rates are found to be strongly influenced by temperature, and optimum C₁–C₄ hydrocarbon selectivity is obtained at 508 K. The activation energy for CO consumption and CH₄ formation are calculated as 74±2 kJ mol⁻¹ and 84±2 kJ mol⁻¹ respectively. ©1997 SCI     

微孔无机膜反应器研究

主要介绍了无机膜在化学反应中的应用－－膜反应器研究，对膜反应器的特点、类型、应用、影响因素以及与其它反应器的比较进行了评述，并对其应用前景进行了展望。     

AQ-1型触媒在1000轴径向氨合成塔中的应用

在不改变任何设备、只部分换用AQ - 1型氨合成触媒的情况下 ,使合成氨生产能力提高了 10 % ,吨氨电耗和能耗均有所下降 ,取得了令人满意的效果。     

等离子体技术在环境保护中的应用（上）

介绍了等离子体的有关概念及其降解污染的基本原理,并分别阐述了高温等离子体和低温等离子体技术在环境污染治理中的应用研究,提出了今后的发展方向。     

可充碱锰电池用化学二氧化锰的制备

温度控制在 85～ 95℃ ,在HNO3介质中 ,用KMnO4氧化MnCl2 和Bi(NO3) 3的混合溶液 ,可制得具有良好可充性能的掺铋二氧化锰 (Bi MnO2 ) ,该样品在 9mol/LKOH溶液中有稳定的循环伏安曲线且经X射线衍射分析测得其在不同放电深度均无Mn3O4生成 ,这表明在MnO2 中添加铋可阻止不具有电化学活性的Mn3O4生成 ;用该样品做成的模拟电池做连续充放电实验 ,电极的循环次数由原来的 5～ 6次 ,提高到 60次以上。     

Within-plant variation in concentrations of amino acids,sugar, and sinigrin in phloem sap of black mustard,Brassica nigra (L.) Koch (Cruciferae)

Although within-plant variation in the nutrient and allelochemical composition of phloem sap has been invoked to explain patterns of host use by phloem-feeding insects, little is known about within-plant variation in phloem chemistry. Here I describe a new technique in which I use the green peach aphid,Myzus persicae Sulz., to investigate within-plant variation in the concentrations of chemicals in the phloem sap of black mustard,Brassica nigra (L.) Koch (Cruciferae). Relationships between the concentrations of chemicals in aphid diets and honeydew were established using honeydew from aphids fed on artificial diets with known concentrations of amino acids, sucrose, and sinigrin. These relationships were applied to honeydew from aphids fed on different aged leaves of black mustard to estimate the concentrations of the chemicals in phloem sap. Sinigrin concentration was estimated to be high (>10 mM) in phloem sap in young leaves, calling into question the prevailing opinion that phloem sap contains only low concentrations of allelochemicals. High concentrations may function as defenses against sap-feeding herbivores. Within-plant variation in phloem sap composition was high: (1) young leaves had high concentrations of nutrients (216 mM amino acids, 26% sugar) and sinigrin (>10 mM); (2) mature and presenescent leaves had lower concentrations of nutrients (77–83 mM amino acids, 19–20% sugar) and low concentrations of sinigrin (1–2 mM); and (3) senescing leaves had high concentrations of nutrients (199 mM amino acids, 25% sugar) and low concentrations of sinigrin (3 mM).     

Fuel properties and emissions of soybean oil esters as diesel fuel

The effects of using blends of methyl and isopropyl esters of soybean oil with No. 2 diesel fuel were studied at several steady-state operating conditions in a four-cylinder turbocharged diesel engine. Fuel blends that contained 20, 50, and 70% methyl soyate and 20 and 50% isopropyl soyate were tested. Fuel properties, such as cetane number, also were investigated. Both methyl and isopropyl esters provided significant reductions in particulate emissions compared with No. 2 diesel fuel. A blend of 50% methyl ester and 50% No. 2 diesel fuel provided a reduction of 37% in the carbon portion of the particulates and 25% in the total particulates. The 50% blend of isopropyl ester and 50% No. 2 diesel fuel gave a 55% reduction in carbon and a 28% reduction in total particulate emissions. Emissions of carbon monoxide and unburned hydrocarbons also were reduced significantly. Oxides of nitrogen increased by 12%.     

X-ray electron spectroscopic investigation of the structure of double lead silicate glasses

The method of x-ray electron spectroscopy is used to investigate lead silicatexPbO(1 -x) · SiO₂ (x - 0.3, 0.4, 0.5, 0.55, 0.667) glasses. The concentration dependences of the spectra of inner Pb4f, Si2p, and Ols levels led to the conclusion that for low contents of PbO, lead is present in the glass in the form of modifying ions, whereas in high concentrations, it plays the role of glass former. Restructuring in the glass occurs for about 50% molar concentration of PbO. The Pb - O bond in the glass is more ionic than in PbO. With an increase in the PbO content in the glass, the Pb - O bond becomes closer to that of lead monoxide, i.e., is more covalent.     

Antioxidative effect of ethanol tea extracts on oxidation of canola oil

There is an increasing interest in the biological effects of natural antioxidants present in teas on formation ofin vivo free radicals, carcinogenesis, and atherogenesis. Teas are traditionally classified into six major groups, namely, green, yellow, white, black, dark-green, and oolong teas. The present study examined the antioxidative activity of ethanol extracts from these six major groups of teas against oxidation of heated canola oil. The oxidation was conducted at 100°C by monitoring oxygen consumption and changes in linoleic and linolenic acids in canola oil. The ethanol extracts of green, yellow, and white teas strongly inhibited oxidation of canola oil compared to butylated hydroxytoluene, probably due to the presence of natural polyphenols. In contrast, oolong teas examined exhibited only moderate antioxidative activity because of the partial destruction of natural polyphenols by semifermentation. The ethanol extracts of black, dark-green, and ginseng teas studied showed little or no protection to canola oil from lipid oxidation, probably due to the complete destruction of natural polyphenols by fermentation during manufacturing processes.