Understanding silica-supported metal catalysts: Pd/silica as a case study

Supported metal catalysts, particularly noble metals supported on SiO₂, have attracted considerable attention due to the importance of the silica–metal interface in heterogeneous catalysis and in electronic device fabrication. Several important issues, e.g., the stability of the metal–oxide interface at working temperatures and pressures, are not well-understood. In this review, the present status of our understanding of the metal–silica interface is reviewed. Recent results of model studies in our laboratories on Pd/SiO₂/Mo(1 1 2) using LEED, AES and STM are reported. In this work, epitaxial, ultrathin, well-ordered SiO₂ films were grown on a Mo(1 1 2) substrate to circumvent complications that frequently arise from the silica–silicon interface present in silica thin films grown on silicon.     

Inhibition of microbial growth in ready‐to‐eat food stored at ambient temperature by modified atmosphere packaging

This study was undertaken to develop a modified atmosphere package to control microbial growth in ready‐to‐eat (RTE) products stored at ambient temperature. Ethanol and/or limonene associated with modified atmosphere (CO₂ : O₂ : N₂ = 30% : 5% : 65%) was used to inhibit the growth of total air‐borne microorganisms and Escherichia coli in RTE products stored at 25°C. The results indicated that 0.05% ethanol vapour in the headspace was effective to inhibit the growth of air‐borne microorganisms and E. coli at 25°C for 72 h in a model study, and the effectiveness was related to ethanol content. Both 73 ppm limonene and 0.05% ethanol vapour enhanced the bacteriostatic effect of modified atmosphere in RTE sushi roll products, and no off‐flavour was detected using this formulated gas; however, no significant inhibitory effect was observed for RTE cold noodle products. This study concludes that combinations of carbon dioxide, ethanol or limonene vapours are effective to inhibit microbial growth in RTE food at ambient temperature, and the outcome may be due to the hurdle effect. Copyright © 2003 John Wiley & Sons, Ltd.     

ca油田稠油油藏系统保护油气层研究

针对ca油田多层状砂泥薄互层稠油油藏的特点,开展了热采和非热采条件下储层变化特征研究、钻井和固井过程入井液的研究、采油工艺技术等系统保护油气层研究,了解各种变化的作用过程和原因,有效地预防现场施工中可能发生的储层伤害,从而达到储层保护、提高采收率的目的。     

深圳市大型商场空气品质的测试与分析

本文根据对位于深圳市不同片区的五家大型商场进行室内空气品质现场检测所得的数据,分析了这些商场的室内空气品质状况,各商场不同楼层、不同售货区的空气品质参数分布规律,以及周末、平日、不同时段室内空气品质参数的变化规律,并结合现场实际情况对其原因进行了分析。     

Synthesis of amphiphilic magnetic microspheres by dispersion copolymerization of styrene and poly(ethylene oxide) macromonomer

Amphiphilic magnetic microspheres ranging in diameter from 5 to 100 µm were prepared by dispersion copolymerization of styrene and poly(ethylene oxide) vinylbenzyl (PEO‐VB) macromonomer (MPEO) in the presence of Fe₃O₄ magnetic fluid. The effects of various polymerization parameters on the average particle size were systematically investigated. The average particle size was found to increase with increasing styrene concentration and initiator concentration. It also increased with decreasing stabilizer concentration and molecular weight of MPEO. The content of the hydroxyl groups localized in the microspheres ranged from 0.01 to 0.2 mmol g^?1. © 2003 Society of Chemical Industry     

石蜡基原油对环烷基原油润滑油馏分低温性能的敏感性分析

为了便于开采和集输环烷基原油,需要在其中混入一定量的石蜡基原油。加工环烷基原油的轻质和中质润滑油产品低温性能对石蜡基原油的混入非常敏感。为了保持产品的低温性能,对按不同比例混入石蜡原油的环烷基原油的影响程度进行了实验,对不同比例的混合油进行实沸点蒸馏得到的轻质和中质馏分的物理性质进行了测试分析,确定了混入量对环烷基原油产品的影响程度。     

北部湾盆地福山凹陷CO2气成因探讨

北部湾盆地福山凹陷油气钻探中发现了高含CO₂气的天然气气藏。对CO₂气稳定碳同位素、伴生稀有气体氦和氩同位素进行了分析研究，结果显示，福山凹陷CO₂气稳定碳同位素偏重，(13C_CO2为-5.01～-10.08‰，绝大多数样品大于-7.0‰，为无机成因CO₂气特征；伴生稀有气体氦同位素³He/⁴He值为(4.74~5.03)×10^-6，R/Ra值为3.38～3.59；伴生稀有气体氩同位素⁴⁰Ar/³⁶Ar值为1881～2190，也显示出幔源或壳幔混合CO₂气的特征。综合判定认为，福山凹陷CO₂为壳幔混合成因。始新统流沙港组岩浆岩体分布特征与CO₂气藏分布范围基本一致，也表明幔源-岩浆可能是福山凹陷CO₂气的主要来源。与南海北部边缘盆地其它地区如珠江口盆地西部、琼东南盆地东部CO₂气成因一致，都为幔源-岩浆来源，或壳幔混合来源。     

A new detection algorithm (NDA) based on fuzzy cellular neural networks for white blood cell detection.

White blood cell detection is one of the most basic and key steps in the automatic recognition system of white blood cells in microscopic blood images. Its accuracy and stability greatly affect the operating speed and recognition accuracy of the whole system. But there are only a few methods available for cell detection or segmentation due to the complexity of the microscopic images. This paper focuses on this issue. Based on the detailed analysis of the existing two methods--threshold segmentation followed by mathematical morphology (TSMM), and the fuzzy logic method--a new detection algorithm (NDA) based on fuzzy cellular neural networks is proposed. NDA combines the advantages of TSMM and the fuzzy logic method, and overcomes their drawbacks. With NDA, we can detect almost all white blood cells, and the contour of each detected cell is nearly complete. Its adaptability is strong and the running speed is expected to be comparatively high due to the easy hardware implementation of FCN. Experimental results show good performance.