纳米Ce0.9Cu0.1O2-δ 固溶体的制备、表征和CO低温氧化性能

采用改进的柠檬酸溶胶-凝胶法(即前驱体先在N₂气氛下高温预处理)制备了高比表面积纳米Ce_0.9^Cu_0.1O_2-δ固溶体。采用XRD、TEM和Raman等对催化剂进行表征，并考察了它们的低温CO氧化性能。研究结果表明，改进的柠檬酸溶胶 凝胶法可以制得晶相比较完整的Ce_0.9^Cu_0.1O_2-δ 固溶体，晶粒小于10 nm，明显小于常规方法制得的样品。随着样品焙烧温度的提高，表征氧缺位的600 cm^－1左右Raman峰的位置向高波数方向迁移。采用改进方法制得的Ce_0.9^Cu_0.1O_2-δ 固溶体具有更高的CO氧化活性，其原因归结为晶粒的减小，容易形成氧缺位和表面高分散CuO的增加，从而促进了CO的氧化。     

Theoretical approach to cell-impedance-controlled lithium transport through Li1 − δMn2O4 film electrode with partially inactive fractal surface by analyses of potentiostatic current transient and linear sweep voltammogram

Lithium transport through the partially inactive fractal Li_1 − δMn₂O₄ film electrode under the cell-impedance-controlled constraint was theoretically investigated by using the kinetic Monte Carlo method based upon random walk approach. Under the cell-impedance-controlled constraint, all the potentiostatic current transients calculated from the totally active and partially inactive fractal electrodes hardly exhibited the generalised Cottrell behaviour and they were significantly affected in shape by the interfacial charge-transfer kinetics. In the case of the linear sweep voltammogram determined from the totally active and partially inactive fractal electrodes, all the power dependence of the peak current on the scan rate above the characteristic scan rate deviated from the generalised Randles-Sev?ik behaviour. From the analyses of the current transients and the linear sweep voltammograms simulated with various values of the simulation parameters, it was further recognised that the cell-impedance-controlled lithium transport through the partially inactive fractal Li_1 − δMn₂O₄ film electrode strongly deviates from the generalised diffusion-controlled transport behaviour of the electrode with the totally active surface, which is attributed to the impeded interfacial charge-transfer kinetics governed by the surface inhomogeneities including the fractal dimension of the surface and the surface coverage by active sites and by the kinetic parameters including the internal cell resistance.     

新型70 m3全流通夹套PVC聚合釜的开发与应用

基于原有70 m3PVC聚合釜的传热性能和搅拌性能的测试和分析,提出了新型全流通半圆管夹套结构,夹套的传热面积增加14 m2,通过现场传热测试,在聚合釜容积不变的条件下,单釜的生产能力可提高30%以上。     

Studies on copolymers of acrylonitrile with resins of furfuryl alcohol: 1. Preparation and thermal properties

Copolymers of acrylonitrile with a furfuryl alcohol resin have been prepared by a free radical reaction, and have been characterized by n.m.r. and i.r. spectroscopy. Their t.g.a. has been performed in air and in a nitrogen atmosphere, to permit the recognition of a number of stages in the weight loss process. D.s.c., also in air and in nitrogen, has identified a number of exothermic and one endothermic process in the copolymers. Solid state cross-polarization/magic angle spinning ¹³C n.m.r. spectroscopy and i.r. spectroscopy has been used to obtain some insight into the chemistry of the various chemical changes, which in air are completed by combustion and in nitrogen leave a carbon.     

Response of The Lacewing Chrysopa cognata to Pheromones of its Aphid Prey

The lacewing Chrysopa cognata, one of the principal predators of aphids in Korea, was tested for responses to the aphid sex pheromone components (4aS,7S,7aR)-nepetalactone and (1R,4aS,7S,7aR)-nepetalactol and the aphid alarm pheromone (E)--farnesene. Electroantennogram responses were obtained to the sex pheromone components but not to (E)--farnesene. The sex pheromone components were attractive in a Y-tube olfactometer assay and in field trials with water traps, but no attraction was observed to (E)--farnesene.     

Properties of biogenic magnetite nanoparticles in the radula of chiton <Emphasis Type="Italic">Acanthochiton rubrolineatus</Emphasis> lischke

The properties of biogenic magnetite(Fe 3 O 4 )nanoparticles in chiton acanthochiton rubrolineatus lischke were characterized by selected electron diffractometry,high resolution transmission electron microscopy,Fourier transform infrared spectroscopy,M·ssbauer spectroscopy and magnetization measurements.Results showed that the magnetite nanoparticles presented crystalline appearance,exhibiting strong absorptions at 595,1 463,3 467 cm-1 and weak adsorptions at 1 697,1 113,1 048,848,445 cm-1 in FT-IR,two partially overlapping sextets in M·ssbauer spectrum,and the area ratio of the sextets was 1.08.Also,the particles exhibited ferromagnetic behavior,and had 82 A·m2/kg saturation magnetization,1.4·104 A/m coercive force and 4.0 A·m2/kg remnant magnetization,respectively.The investigation indicates that the biogenic magnetite nanoparticles mineralized in the chiton are impure in composition and non-stoichiometric.     

Effects of adhesive type and polystyrene concentration on the shear strength of bonded polystyrene/high-density polyethylene blends

The lap-shear strengths of adhesively bonded polystyrene (PS), high-density polyethylene (HDPE), and their blends, were studied as a function of adhesive type and blend composition. The performance of virgin and recycled polymer systems was examined. The lap-shear strength depended strongly on the amount of PS in the blend and the type of adhesive, and the acrylic adhesives demonstrated the best performance for all compositions. Bonded strengths of HDPE increased by approximately 50% when HDPE was blended with 34% PS, the co-continuous composition. The results indicate that structural elements made from PS/HDPE immiscible blends may be effectively bonded with adhesives without expensive surface treatments.     

Self-diffusion of poly(ethylene oxide) in aqueous dextran solutions measured using FT-pulsed field gradient n.m.r.

Transport in ternary polymer₁, polymer₂, solvent systems has been investigated using an n.m.r. spin-echo technique. The dependence of the self-diffusion coefficient of poly(ethylene oxide) polymers on the concentration and molecular size of dextran in aqueous solution has been measured. Monodisperse poly(ethylene oxide) fractions ($\text{M}\text{?}{}_{\mathrm{w}}\text{=7.3×10}{}^4$, 2.8·10⁵ and 1.2·10⁶) and dextrans ($\text{M}\text{?}{}_{\mathrm{w}}\text{=2·10}{}^4$, 1·10⁵ and 5·10⁵) have been employed over a range of concentration up to the miscibility limit in each system. It is found that when the molecular size of the diffusant is commensurate with or exceeds that of the matrix polymer, a relationship of the form: $\text{(}\text{D}\text{D}{}_0\text{)}{}_{\mathrm{<mtext>PEO</mtext>}}\text{=}\text{exp}\text{?k(C[η])}$ is applicable, where C[η] refers to the dextran component and is considered to describe the extent of coil overlap in concentrated solution. ($\text{D}\text{D}{}_0$) is independent of the molecular size of the poly(ethylene oxide), at least in the range studied (M_w<300 000).     

Acetone conversion to isobutene in high selectivity using zeolite β catalyst

The catalytic activity of the proton forms of zeolite and ZSM-5 are compared for the conversion of acetone. Zeolite demonstrates markedly enhanced selectivity to isobutene and selectivities of >80% can be achieved for conversions up to 65%. In contrast high selectivities to isobutene with ZSM-5 can be attained only at very low conversions (5%).     

有理曲线的最优参数

该文介绍一种对有理曲线重新参数化的方法.此重新参数化的方法是从一个能量极小的准则出发,通过有理线性参数变换,确定曲线的最优参数.通过推导,最优参数是全局存在的,该文对有理2次曲线(圆锥曲线)进行了最优参数的计算,结果表明此方法简单、可行,具有一定的应用价值.