干法浸渍过程模型的激波理论解及实验研究

本文探讨了干法浸渍过程中达到吸附平衡时，催化剂前体在球形截体内的浓度分布。对单组分浸渍于渗透－吸附模型提出了具有一般意义的边界条件，应用激波理论得到了浓度分布的解析解。实验测定了硝酸铜溶液－硅胶体系和模型参数及φ5毫米载体内的浓度分布。理论计算与实际分布基本吻合。     

Culturable and Total Fungi in Dust Accumulated in Air Ducts in Single-Family Houses

Abstract Fungal spore content in dust accumulated in air ducts was investigated in 24 mechanically ventilated single-family houses of which 15 had also a central air heating system. Dust was collected from the ducts simultaneously with cleaning of the ventilation systems. Besides spore concentrations and flora of culturable fungi, total fungal spore concentrations were determined in dust samples by the aqueous two-phase technique and spore counting with epifluorescence microscopy. Culturable spore concentrations in the dust varied from 10⁴ to 10⁷ CFU/g and total spore concentrations from 107 to 108 spores/g. Total spore concentrations in the duct dust were significantly higher in the air heated houses than in the other mechanically ventilated houses. The difference resulted mainly from a higher proportion of recirculation air and a higher age of the air heated houses. Cladosporium, Penicillium, Aspergillus and yeasts consisted of >90% of fungal flora in the dust. Although total spore concentrations were at the same level both in the exhaust and in the supply ducts in both types of house, culturable fungal spore concentrations were slightly higher in the exhaust ducts than in the supply ducts. The proportion of culturable spores was <5% of total spores in dust accumulated in the ducts.     

Coworker exchange: Relationships between coworkers, leader-member exchange, and work attitudes.

The study of leadership exchanges is extended by studying both leader-member exchanges (LMXs) and, coworker exchanges (CWXs). Data from 110 coworker dyads were used to examine relationships between LMXs and CWXs and between exchange relationships and work attitudes. As predicted, the interaction between 2 coworkers' LMX scores predicted CWX quality for the coworker dyad. Also, after controlling for LMX, greater diversity in a worker's CWX relationships was negatively related to his or her organizational commitment but not job satisfaction. The quality of a worker's CWX relationships, however, did not moderate the relationship between CWX diversity and work attitudes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Collaborating with computers

Abstract The main body of the article explores three questions concerning the collaborative use of computers in classrooms. The first looks at the opinions of the powerful as evidenced by the recent spate of publications concerning the National Curriculum; the second explores the extent to which there exists research evidence to support the position the curriculum makers have taken up; the third reviews the literature for indications as to how teachers are likely to react to their proposals. A fourth question niggles: how does the ‘subjective’ computer fit into the classroom? The article ends in speculationperhaps we need to take a fresh look as to why exactly many teachers remain uneasy in the presence of computers?     

A procedure to prepare cross-sectional samples for TEM

Cross-sectional transmission electron microscopy (XTEM) is an imaging technique particularly suited to the study of layered structures. For integrated electronic devices it has become a common practice to use XTEM to assess the shape and crystallinity of component layers as well as defect structures introduced by processing. A procedure for preparing samples to be viewed by XTEM is described.     

A two-stage preparation of mesophase pitch from the vacuum residue of FCC decant oil

The preparation of mesophase pitch as a precursor for the high-performance carbon fiber from a vacuum residue of FCC-decant oil (FCC-DOVR) was studied, applying a two-stage heat treatment to improve the pitch yield as well as its liquid crystal properties. The present two-stage preparation consisted of the pressurized heat treatment (1–5 MP) of the first stage at 430–480°C and the successive heat treatment under 13–260 Pa at 430°C. Such a two-stage preparation increased the yield of the spinnable mesophase pitch of 100% domain texture with lower softening point to 45% from 22% by the single-stage one from the same feedstock. Spinning properties of the mesophase pitch were excellent to allow smooth spinning for longer than 15 min and random orientation of mesogen molecules in the tranverse section of the fiber perpendicular to the fiber axis. The chemistry of the two-stage preparation for the higher yield and better properties as the fiber precursor is briefly discussed.     

Characterization of Lead Scandium Tantalate Ceramics Prepared by Precipitation Method

Precipitation and coating techniques that proved successful for lead scandium niobate were tried with lead scandium tantalate. The Ta₂O₅ did not prove to be a useful substrate for the precipitating carbonates, but the resulting fine-particle-size powder lowered the sintering temperature to 1375° with only 0.4 wt% PbO loss. Annealed samples showed shifts in the dielectric response and sharpening of infrared and X-ray diffraction patterns, but little development of super lattice.     

提高配电网架空线路供电可靠性的探讨

对影响配电网架空线路供电可靠性的因素进行分析,包括雷击灾害、故障点查找困难等,从防雷的措施及其优缺点、快速复电和故障隔离的新设备新技术应用、带电作业的推广应用等3个方面进行剖析,提出通过综合应用科学的防雷措施和快速复电、故障隔离技术,并大力开展带电作业,可大大提高配电网架空线路的供电可靠性.