Specific Inhibitors of the Breast Cancer Resistance Protein (BCRP)

A new class of specific breast cancer resistance protein (BCRP) inhibitors was identified, showing no inhibition of the ATP binding cassette (ABC) transporters P‐gp and MRP1. Some of these modulators inhibit BCRP with high potency; they are only slightly less potent than Ko143 and could serve as promising lead structures for the design of novel effective BCRP inhibitors. These inhibitors are structurally related to tariquidar (XR9576) and belong to a library of multidrug‐resistance modulators synthesized by our research group. The absence of the tetrahydroisoquinoline substructure appears to play a crucial role for specificity; we found that the presence of this substructure is not essential for interaction with BCRP. To determine the type of interaction between pheophorbide A and compounds with and without the tetrahydroisoquinoline substructure, various substrate pheophorbide A concentrations were used in enzyme kinetics assays. The resulting data show that these compounds share a noncompetitive‐type interaction with pheophorbide A. Experiments with imatinib and pheophorbide A revealed a mixed‐type interaction. The combination of imatinib and compounds with and without the tetrahydroisoquinoline substructure resulted in a positive cooperative effect, indicating that imatinib engages a binding site distinct from that of the new compounds on one side and distinct from that of pheophorbide A on the other side as well. The results of this study suggest that the category of BCRP‐specific inhibitors, which includes only fumitremorgin C, Ko143 and analogues, and novobiocin needs to be extended by this new class of inhibitors, which possess three key characteristics: specificity, potency, and low toxicity.     

硅烷膏体浸渍剂在保护混凝土中的实际应用

渗透型有机硅成功用于保护混凝土在国外已有数十年的历史。用于保护钢筋混凝土，它可防止水分及氯离子的渗透，从而对于防止混凝土的腐蚀与破坏起到关键的作用。这种浸渍剂一般都由硅烷或硅氧烷组成。通常情况下，由于这些低粘度的液体非常容易挥发。尤其在桥梁底面及立面施工时，有效成分大量流失。为了避免出现这种情况，德国瓦克化学有限公司成功开发了一种新型的硅烷乳膏状产品。这种材料施工简单，只需一步完成，具有很高的遮盖率，由于不流淌，活性组分不会损失。与混凝土表面接触时间长，保证了在高等级混凝土中的渗透深度，而且在其表面不会残留任何痕迹。     

Automated fixture configuration using projective geometry approach

The geometric and topological specification of a workpiece boundary is usually represented in a specific data format in a CAD database. To retrieve a set of workpiece data, to analyse its shape in addition to the machining requirements, and to determine the proper fixture configuration accordingly, are not trivial tasks when a part has a complicated shape. The real challenge is to recognise and synthesise the shape of a workpiece from its data representation. Consequently, the decision for fixturing can be made when the shape of a workpiece and the relationship of the shape and the fixturing configuration can be derived by a systematic methodology. In this paper, a projective spatial occupancy enumeration (PSOE) approach is applied as a representational and manipulating scheme for developing algorithms in automatic fixture configuration. The workpiece is projected onto the working plane of the fixture baseplate. A 2D projection is defined as a matrix of cells which can represent a workpiece with an arbitrary shape. Using a discrete search based upon the matrix of cells, the fixture types and their locations are generated according to a set of heuristic algorithms. This work is a generalisation and extension of previous works for prismatic parts. The same methodology is equally applicable in general robot grasping.     

Opto-electronic high-frequency cross-correlation using avalanche photodiodes

Correlation analysis has become an important research tool in the investigation of signals and systems behaviour. We report on a special opto-electronic cross-correlator in which a silicon avalanche photodiode is used as the main component. The internal gain of this photodiode is pulse-modulated with 330 ps FWHM at 126 MHz repetition rate, or is modulated sinusoidally at frequencies of up to 882 MHz, respectively. In the pulsed mode, very weak repetitive optical pulses can be detected with 3 × 10⁻³ photons per pulse sensitivity, and with 10 ps timing accuracy. The second mode offers time-selective signal rejection capabilities with 3 ps time resolution. The opto-electronic cross-correlator can be used in displacement and distance measurement, robotics, time dispersion analysis in optical fibres, transient absorption spectroscopy, fluorescence decay measurement, lifetime-selective fluorescence detection, and in fluorescence signal suppression in Raman spectroscopy.     

Spaltung von 1,2,4-Thiadiazol-3-onen mit Triphenylphosphan: Triphenylphosphonio-thioimidazolate und ihre Folgereaktionen

Fission of 1,2,4-Thiadiazol-3-ones by Triphenylphosphane: gewidinet Triphenylphosphonio Thioimidazolates and Their Consecutive Reactions Treatment of benzimidazo[1,2-d][1,2,4]thiadiazol-3(2H)-ones ( 1 ) and imidazo[1,2-d]-[1,2,4]thiadiazol-3(2H)-ones ( 17 ) with triphenylphosphan leads to the liberation of isocyanate and the formation of triphenylphosphonio-thiobenzimidazolat ( 4 ) and triphenylphosphonio-thioimidazolat ( 18 ), respectively. 2,4-Diphenyl-5-phenylimino-1,2,4-thiadiazol-3-one ( 23 ) is desulfurized with Ph₃P and decomposed into phenyl isocyanate and diphenylcarbodiimide whereas the N-unsubstituted imino-thiadiazol-3-one ( 25 ) is attacked at the exocyclic imino group by Ph₃P to give the N-phosphoranylidene thiourea ( 26 ). The structure of 4 can be rationalized as a dynamic system between polar and apolar valence isomeres. Reactions of 1 and 17 with cyanates, isocyanates, carbon disulfide, acetic anhydride, amines, benzyl chloride, grignard compounds, and CH acidic compounds are described.     

Computer security policy: Important issues

A key success factor in implementing computer security is the much discussed and important issue of management commitment. Management commitment is demonstrated through the effective fostering of a computer security policy within the organization. Many textbooks provide guidelines on what to include or exclude in compiling a computer security policy. However, little is said about issues such as accountability, responsibility and the actual scope of computer security. This paper will address various issues of critical importance in compiling a computer security policy.     

Differential Scanning Calorimetry Studies on the Crystallinity of Ageing Wheat Starch Gels

The ageing of wheat starch gels stored at 4°C, 21°C and 30°C was examined by differential scanning calorimetry. Kinetics of the crystallisation process were studied using the Avrami model where it was found that the experimental data fitted the model more satisfactorily when the Avrami exponent was less than unity. At higher storage temperature the starch crystals appeared more symmetrically perfect. Addition of wheat flour pentosans to 50% starch gels did not significantly affect the kinetics of ageing. The extent of crystallisation during the ageing process depends on the moisture content of the starch gel. Crystallinity of the starch gel, measured in the temperature range 306–346°K does not occur if the solids content is below 10% or above 80% and a bell shaped curve is obtained. Reduction of the moisture content of the starch fraction of baked goods either directly or indirectly using materials competing for water, might therefore reduce the staling problem.     

Studies on the Retrogradation of Starch in Starchy Foods. Part 3. Effect of the Addition of Sucrose Fatty Acid Ester on the Retrogradation of Corn Starch

A model of retrograded starch molecules was proposed in our previous paper. The effect of the addition of n-butyl alcohol or sucrose fatty acid on the retrogradation of starch was studied in this paper. The samples were prepared by repeating freeze-thaw cycles with or without addition of complex forming agents. The samples were treated with 16% sulfuric acid as by Nägeli amylodextrin preparation or a mixture of β-amylase-pullulanase. The residues of the acid or enzyme treatment were chromatographed. From the results of iodine titration, degree of gelatinization, X-ray diffraction, and chain length distribution, it is discussed how the helix forming angents react with fractions of starch and prevent the retrogradation. A schematic model of the retrograded starch with helix forming agents are also proposed.