1999年15种电路板的缺陷分析

本介绍在欧洲和北美15家PCBA制造商的生产数据调查结果。数据末自X射线系统的自动检测结果和维修部门的附加信息。本报告可能是最完整的一份调查，因为它包括了来自不同制造商的566种各种电路板型号的，约329000块印制电路板和超过10亿个焊点的检测，以及焊接缺陷的分布资料。本首先描述数据收集处理的方法学，数据收集的时间，以及参与调查的公司综合介绍。统计结果表示分不同的公司、不同复杂程度的板、不同类型的公司和不同地理区域的缺陷水平。此外，还介绍了失效的分布图，并且对某些令人惊奇的结果作出了尽可能的解释。     

Evaporation from a Three‐Phase Emulsion

The evaporation path was determined for the emulsion system water, linalool and 5% Laureth 4, (L4), from the phase diagram of the components. The initial part of the evaporation took place in a two‐phase region of the emulsion and the path, expressed as fractions of the compounds, was non‐linear reflecting the changed vapour pressure of the linalool. The latter part of the evaporation, on the other hand, occurred through a three‐phase region and the path now formed a straight line. The recently introduced algebraic approach to extracting information from phase diagrams enabled presenting quantitative changes in composition, phase fractions and total content of the emulsion, as well as the vapour pressure versus different variables; including time.     

Inhibition of Human DHODH by 4‐Hydroxycoumarins,Fenamic Acids,and N‐(Alkylcarbonyl)anthranilic Acids Identified by Structure‐Guided Fragment Selection

A strategy that combines virtual screening and structure‐guided selection of fragments was used to identify three unexplored classes of human DHODH inhibitor compounds: 4‐hydroxycoumarins, fenamic acids, and N‐(alkylcarbonyl)anthranilic acids. Structure‐guided selection of fragments targeting the inner subsite of the DHODH ubiquinone binding site made these findings possible with screening of fewer than 300 fragments in a DHODH assay. Fragments from the three inhibitor classes identified were subsequently chemically expanded to target an additional subsite of hydrophobic character. All three classes were found to exhibit distinct structure–activity relationships upon expansion. The novel N‐(alkylcarbonyl)anthranilic acid class shows the most promising potency against human DHODH, with IC₅₀ values in the low nanomolar range. The structure of human DHODH in complex with an inhibitor of this class is presented.     

采用新技术改善涂布纸板机的竞争能力

由于价格低廉的商品从亚洲、拉丁美洲和东欧新兴市场进入西欧和北美的当地市场,西欧和北美的纸板生产厂家可以通过纸机的改造来改善质量,从而保持竞争能力和长期的效益.     

Anode slimes treatment: The boliden experience

There are numerous approaches to the treatment of both copper and lead anode slimes. Although the chemistry and metallurgy has been described and discussed by many authors, few, if any, have described the environmental impact of these activities. Dust and especially selenium emissions are a problem both in the internal working environment as well as in the external environment. For more information, contact B.M. Ludvigsson, Boliden Contech AB, P.O. Box 745 Skelleftea 93127, Sweden; e-mail bjorn.ludvigsson@contech.boliden.se.     

Transport priorities,risk perception and worry associated with mode use and preferences among Norwegian commuters

There is currently scant research on the role of transport priorities, risk perception and worry for travel mode use and preferences. The present study aims to examine these factors in relation to mode use and preferences among Norwegian commuters. A web-based survey was conducted in a randomly obtained representative sample of daily commuters in the extended greater Oslo area (n = 690). The results showed that those who prioritized efficiency and flexibility tended to commute by car, while those who prioritized safety and comfort used public (e.g. metro, tram, and train) or active (e.g. walking and cycling) transport. In a free choice scenario, the respondents who prioritized flexibility reported a preference for using a car, whereas those who prioritized safety and comfort preferred public and active transport for their commuter travels. Risk perception of high impact events, such as terrorism and major accidents, as well as risk perception related to personal impact risks (theft, violence etc.) were related to car use on commuter travels. Transport-related worry exerted weak influences on mode use and preferences. Increased speed on rail transport and more frequent departures may be effective in reducing car use on commuter travels. Risk communication should focus on highlighting the low risk of experiencing security and safety issues in the public transport sector, and this message should be complemented by efforts to reduce the probability of negative events affecting public transport.     

Periodic solutions in systems of piecewise- linear differential equations

Motivated by the periodic behaviour of regulatory networks within cell biology and neurology, we have studied the periodic solutions of piecewise-linear, first- order differential equations with identical relative decay rates. The flow of the solution trajectories can be represented qualitatively by a directed graph. By examining the cycles in this graph and solving the eigenvalue problem for corresponding mapping matrices, all closed, period-1 orbits can be found by analytical means. Theorems about their exist- ence, stabiiiiy and uniqueness are derived. For three-dimensional systems, the basins of attraction of the limit cycles can be explicitly determined and it is shown that higher periodic and chaotic solutions do not exist.     

The effect ofn-decanol on solubilization of water-in-oil microemulsions and stability of lamellar liquid crystals of alkylphenol ethoxylates

Addition of n-decanol at appropriate concentrations is beneficial to increasing the solubilization amount of water in a water-in-oil microemulsion in the system of nonylphenol ethoxylate/olive oil/water, but it destabilized the lamellar liquid crystal and reduced the solubilization of olive oil in the lamellar liquid crystal.     

Nuclear microscopy in biomedical analysis with special emphasis on clinical metal biology

Nuclear microscopy based upon developments in high energy ion beam techniques is by now an accepted technique in many fields of research. The advancements into the biomedical field have, however, been slower than expected. A major factor explaining this tendency is the availability of nuclear microscopy. This paper reviews briefly the biomedical work using nuclear microscopy that has been carried out since the 4^th International Conference on Nuclear Microprobe Technology and Applications held in Shanghai. Nuclear microscopy of isolated individual blood cells from patients adversely affected by metal exposure from dental amalgam has been performed both before and after removal of the metallic fillings. The elemental profile of blood cells was more or less normalised after treatment. Some of these results will be presented to illustrate a medical application. Results from bulk analysis by ICP-MS of erythrocytes and plasma before and after treatment will also be presented to illustrate the difference in information content between these two approaches as well as the need for complementary information in solving biomedical problems. As part of a larger study of acute porphyria, nuclear microscopy of blood cells was included among the 78 laboratory tests. The approach in this study was unbiased in the sense that no hypothesis was formulated as to which laboratory parameters would be the most explanatory for health or disease. Multivariate discriminant analysis was applied to the large amounts of data acquired. This approach led to the hypothesis that oxidative stress increased the synthesis of manganese-dependent superoxide dismutase in the mitochondria of polymorphonuclear leukocytes, explaining the increase of manganese in these cells. Antioxidant therapy was therefore applied to a couple of patients with porphyria, however, without clinical success.