反射涂料时代已经来临

介绍了ALTIRIS(R)颜料的特性,它能赋予任何颜色的涂料或聚合物产品反射太阳光的能力.添加ALTIRIS9R)的热反射涂料能使涂层表面温度降低15～20℃.对于黑色涂料而言,加入ALTIRIS(R)后总太阳能反射率可以接近40％,相对于传统黑色涂料吸收大部分太阳能并反射5％～8％的能量来说是一个实质的进步.     

Fluorogenic peptide-based substrates for monitoring thrombin activity

The synthesis of a series of peptides containing C‐terminal 7‐amino‐4‐methylcoumarin (AMC) for use in the thrombin generation test (TGT) is described. The lead structure in this project was H‐Gly‐Gly‐Arg‐AMC, of which the water solubility and kinetic parameters (K_M and k_cat) are greatly improved over those of the substrate in current use in the TGT: Cbz‐Gly‐Gly‐Arg‐AMC. A series of N‐terminally substituted Gly‐Gly‐Arg‐AMC derivatives were synthesized, as well as implementation of structural changes at either the P₂ or P₃ position of the peptide backbone. Furthermore, two substrates were synthesized that have structural similarities to the chromogenic thrombin substrate SQ68 or that contain a 1,2,3‐triazole moiety in the peptide chain, mimicking an amide bond. To determine the applicability of newly synthesized fluorogenic substrates for monitoring continuous thrombin generation, the K_M and k_cat values of the conversion of these fluorogenic substrates by thrombin (FIIa) and factor Xa (FXa) were quantified. An initial selection was made on basis of these data, and suitable substrates were further evaluated as substrates in the thrombin generation assay. Assessment of the acquired data showed that several substrates, including the SQ68 derivative Et‐malonate‐Gly‐Arg‐AMC and N‐functionalized Gly‐Gly‐Arg‐AMC derivatives, are suitable candidates for replacement of the substrate currently in use.     

Modelling bacterial water quality in streams draining pastoral land

A model has been developed to predict concentrations of the faecal bacteria indicator E. coli in streams draining grazed hill-country in New Zealand. The long-term aim of the modelling is to assess effects of land management upon faecal contamination and, in the short term, to provide a framework for field-based research. A daily record of grazing livestock is used to estimate E. coli inputs to a catchment, and transport of bacteria to the stream network is simulated within surface and subsurface flows. Deposition of E. coli directly to streams is incorporated where cattle have access to them, and areas of permanent saturation ('seepage zones') are also represented. Bacteria are routed down the stream network and in-stream processes of deposition and entrainment are simulated. Die-off, both on land and in water, is simulated as a function of temperature and solar radiation. The model broadly reproduces observed E. coli concentrations in a hill-country catchment grazed by sheep and beef cattle, although uncertainty exists with a number of the processes represented. The model is sensitive to the distance over which surface runoff delivers bacteria to a stream and the amount of excretion direct to streams and onto seepage zones. Scenario analysis suggests that riparian buffer strips may improve bacterial water quality both by eliminating livestock defaecation in and near streams, and by trapping of bacteria by the riparian vegetation.     

Book reviews

Urban Policy Evaluation: Challenge and Change. R. Hambleton & H. Thomas (Eds). Liverpool, Paul Chapman, 1995, 258 pp., £17.95 ISBN 1–85396–271–6

Environmental Strategy and Sustainable Development. R. Welford. Routledge, London, 1995, 217 pp, £12.99, ISBN 0–415–10552–8

Urban Agriculture in Zimbabwe. B. Mbiba. Ashgate, Aldershot, UK and Brookfield, VT, 1995, £35.00, ISBN 185628 857 9

Housing Women. Rose Gilroy & Roberta Woods (Eds.). London, Routledge, 1994, 304 pp., £14.99, ISBN 0–415–09463–1

Census User's Handbook. S. Openshaw (Ed.). Longmans, 1995, 454 pp., £19.95, ISBN 0–470234–814

Reconstituting Rurality. J. Murdoch & T. Marsden. London, UCL Press, 1994, 272 pp., £40.00, ISBN 1–85728–041–5

Development and Administration of Prague. M. Barlow, P. Dostal, & M. Hampl (Eds). Amsterdam, Instituut voor Sociale Geographie, Universiteit van Amsterdam, 1994, 170 pp., 35DG, ISBN 9–06993–086‐Z

Local Development, Restructuring, Locality and Local Initiative in Portugal. S. Syrett. Aldershot, Avebury, 1995, 371 pp., £40.00, ISBN 1 85628 484 0     

Removal of THM precursors by coagulation or ion exchange

The removal of natural organic matter (NOM) from drinking water supplies can be achieved by different processes, among them coagulation and adsorption. Synthetic waters made from concentrates of humic substances from reservoir and river waters were tested in the laboratory for ease of removal of NOM by coagulation with cationic organic polymers and with alum, and by adsorption on anion exchangers. For polymers such as high molecular weight polydiallyldimethylammonium chloride (polyDADMAC) and cationic polyacrylamides of high charge, performance was nearly as effective as alum, with colour removals 86–100% of those obtained for alum. Ion exchange using the best commercially available resins designed for this purpose, a gel polystyrene and a macroporous acrylic resin, was more effective than alum treatment for two of the natural waters studied, but inferior for a third. The resins were overall superior to cationic polymers.

The NOM was separated into four fractions based on hydrophobic and hydrophilic properties. Alum was not as effective as ion exchange for the elimination of individual ionic NOM fractions. It was better than cationic polymers for removal of humic and fulvic acids, although polyDADMAC was as good for one water. For the removal of charged compounds alum then polyDADMAC were the best performers for that water. Unequivocal evidence was obtained that coagulants remove material that is not adsorbed by resins, and vice versa. A combination of coagulation with a cationic polymer and adsorption by an anion exchanger removed essentially all of the NOM. The preference of the coagulants was for the larger, more hydrophobic molecules, and of resins for smaller highly charged hydrophilic molecules. Each fraction had trihalomethane formation potentials in the range 11–24 μg/mg, except for one water that was more reactive. Hence, the actual amount of each fraction in the original water becomes a crucial factor.     

Multivalent carbohydrate recognition on a glycodendrimer-functionalized flow-through chip

Dendrimers were fitted out with up to eight mannose moieties by "click" chemistry. They were subsequently attached to aluminum oxide chips via a spacer that was linked to the dendrimer core; this resulted in a microarray of glycodendrimers. Binding of the glycodendrimers to the fluorescent lectins ConA and GNA was observable in real time. In a single experiment it was possible to observe the multivalency enhancement or cluster effect in the binding event. This effect was small for ConA, in agreement with its widely spaced binding sites, whereas it was large for GNA, with its twelve much more closely spaced binding sites. The dendrimer-fitted chip represents a valuable screening tool for multivalency effects. Furthermore kinetic and thermodynamic data on binding events can be deduced. Inhibition experiments are also possible with the system as was shown for ConA with alpha-methyl mannose as the inhibitor.     

Peak Oil and Transition Towns

If economic growth is only possible with the availability of cheap energy, what happens as production of oil peaks, and petroleum extraction declines? Rob Hopkins , an activist behind the Transition movement, argues for a new bottom-up approach to economic development that is also more localised and nourishing. Shifting the emphasis from sustainability towards resilience, he seeks a rethinking of the way local communities feed, house and power themselves.     

Ball localization and tracking in a highly dynamic table soccer environment

This article presents the development of a ball localization and tracking algorithm, that is to be applied in a highly dynamic table soccer environment. The described approach is based on an earlier survey paper on object tracking, where a general selection procedure on object detection and tracking techniques was proposed. Although the survey paper presents a variety of state estimation techniques for tracking, this article describes why these are not well suited for our specific application. For this reason, an IMM estimation technique is adopted that has not been applied in this highly dynamic context before. To evaluate the IMM estimator, it is compared to the well-known and commonly used Kalman filter, that has been optimally tuned for this specific application.