大功率CO_2激光器非平衡态合成WO_3／Fe_2O_3新型陶瓷催化剂──Ⅱ．WO_3／Fe_2O_3烯烃歧化反应催化剂的催化活性

用大功率ＣＯ２激光器熔制ＷＯ３／Ｆｅ２Ｏ３新型烯烃歧化反应催化剂。考查了催化剂组成、激光功率及熔炼时间与丙烯歧化反应催化活性之间的关系。     

Xylose-lysine model systems: The effect of pH on the volatile reaction products

Aqueous molal solutions of xylose and lysine (initial pH 4–9) were refluxed either with control of the pH at 5–0 or without pH control (final pH 2–6). Analysis by gas chromatography (GC) and GC-mass spectrometry resulted in the identification of 58 and 28 compounds, respectively, from the two systems. Furans were the main reaction products in both systems and 2-furfural alone comprised 522 and 999 g kg^?1 of the volatiles, respectively, from the systems with final pH values of 5–0 and 2–6. Maintaining the pH at 5–0 resulted in a higher yield and greater numbers of nitrogen-containing compounds, and monocyclic pyrroles, pyridines and 2,3-dihydro-l H-pyrrolizines were identified only in that system. Aliphatic compounds, alicyclic compounds, benzene derivatives. l-(2–furfuryl)pyrroles and pyrazines were also identified. This investigation is the first report of the formation of 2.3-dihydro-l H-pyrrolizines in a model system containing lysine as the amino compound; a possible mechanism is proposed.     

Probing the early stages of polymerization of ethylene on a model chromium/silica catalyst by Fourier transform infrared spectroscopy

The nature of the interaction of monomer, and the early stages of growth of oligomers of ethylene on a rather more uniform surface of Cr/SiO₂ catalyst than hitherto studied has been investigated by differenceFTIR spectroscopy using C₂D₄ and C₂H₄ as reactants both with and without subsequent treatment of the catalyst with CO andTHF. The active catalyst was prepared by reaction of vapour phase CrO₂Cl₂ with the vicinal hydroxyls of the silica surface. Three distinct kinds of methylene groups were detected. Arguments are given for assigning the peaks at 2935 and 2860 cm^–1 to CH₂ groups directly bound to the active site and those at 2920 and 2850 to CH₂s in the growing chain well removed from the Cr. The peaks at 2160 and 2165 cm^–1 are attributed to CD₂ groups hydrogen bonded to surface hydroxyls.     

珠江三角洲土坝和堤围震害初步预测

本项预测采用概率方法,即首先根据广东省水利部门提出的55座土坝和59个重点的座标(见附图),进行概率地震危险性分析,给出它们在一定预测年限T(取50年和100年)的地震烈度Ⅰ的超越概率;其次根据近年我国发生的几次强震时处于不同烈度区内的土坝和堤防的震害资料,形成表示土坝和土堤地震易损性的震害概率矩阵;然后,根据上述两方面结果用概率公式评价各土坝和堤围点在预测年限内各震害等级的超越概率,并取10％超越概率为标准,估计震害等级。结果表明,珠江三角洲土工构筑物的地震危害性南部高于北部。     

Li2O在保护渣中的作用

采用在不同玻璃性的两种基渣中加入Ｌｉ２Ｏ为研究Ｌｉ２Ｏ对保护渣粘度，熔化温度及玻璃性能的影响，并对Ｌｉ２Ｏ改善保护渣玻璃性的机理进行了探讨，提出了寻找高速连铸保护渣中Ｌｉ２Ｏ的代用物的一种方法。     

Studies on the interactions of metal oxides and Na2 SO4 at 1100 and 1200 K in oxygen

The interaction of different metal oxides such as Co₃O₄, NiO, Al₂O₃, Cr₂O₃, Fe₂O₃ and SiO₂ with Na₂SO₄ at a temperature of 1100 and 1200 K in flowing oxygen has been studied. The thermogravimetric studies for each system were carried out as a function of Na₂SO₄ in the mixture. The presence of different constituents in the reaction products were identified by X-ray diffraction analysis and the morphologies of the reaction products were characterized using metallography and scanning electron microscopy (SEM). The formation of products was also investigated by thermodynamic computation of free energies of the reactions and the study of relevant equilibrium phase diagrams. The soluble species in the aqueous solutions of the reaction products were determined quantitatively using atomic absorption spectrophotometry. The high temperature interaction products usually contain a 3-phase structure namely, Na₂O·M₂O _x , M₂O _x and metal sulphide and/or metal sulphate. The formation of Na₂O·M₂O _x depends upon the solid state solubility of metal oxide in the molten salt at high temperatures. Under limited solubility conditions Na₂O·M₂O _x is invariably formed, but as soon as this condition is relaxed the oxide. M₂O _x , precipitates and forms a separate phase.     

超薄SiO2层的热生长

隧道小孔中超薄ＳｉＯ２的生长是ＥＥＰＲＯＭ电路制造的关键工艺之一。采用ＳＵＰＲＥＭ－Ⅲ工艺模拟程序对超薄ＳｉＯ２的热生长进行了工艺模拟，经过大量的工艺实验及优化，确定了超薄ＳｉＯ２的最佳生长条件，生长出的ＳｉＯ２性能良好，完全可满足ＥＥＰＲＯＭ研制的要求。     

Modified atmosphere packaging of a mixed prepared vegetable salad dish

The aim of this study was to design a modified atmosphere package for a mixed vegetable salad consisting of 75 g of cut carrot, 55 g of cut cucumber, 20 g of sliced garlic and 50 g of whole green pepper. Respiration data of all the components were combined with film permeability data to predict package atmospheres and design optimal packages for experimental testing for improved shelf-life of the produce. The optimal package avoided minimum O₂ and maximum CO₂ tolerance limits, and chilling injury temperatures for any component. A pouch form package made of 27 mm low density polyethylene developed a modified atmosphere of 2.0–2.1% O₂ and 5.5–5.7% CO₂, which was beneficial for all components and provided better quality retention than other test packages.     

The As-prepared surfaces of C-axis-oriented Nd1Ba2Cu3Oy thin films characterized using scanning probe microscopes

Recently, superconducting Nd₁Ba₂Cu₃O_y (Ndl23) thin films with high superconducting transition temperature (T _c) have been successfully fabricated at our institute employing the standard laser ablation method. In this paper, we report the results of surface characterization of the Nd123 thin films using an ultrahigh vacuum scanning tunneling microscope/spectroscopy (UHV-STM/STS) and an atomic force microscope (AFM) system operated in air. Clear spiral pattern is observed on the surfaces of Nd123 thin films by STM and AFM, suggesting that films are formed by two-dimensional island growth mode. Contour plots of the spirals show that the step heights of the spirals are not always the integer or half-integer number of thec-axis parameter of the structure. This implies that the surface natural termination layer of the films may not be unique. This result is supported byI-V STS measurements. The surface morphology of the Nd123 thin films is compared with that of thec-axis-oriented Y₁Ba₂Cu₃S_y thin films. Surface atomic images of the as-prepared Nd123 thin films are obtained employing both STM and AFM. STS measurements show that most of the surfaces are semiconductive. The results of STS measurements together with the fact that we are able to see the surface atomic images using scanning probe microscopes suggest that exposure to air does not cause serious degradation to the as-prepared surfaces of Nd123 thin films.