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Political changes in the Central European countries since 1989 have led to a radical shake-up in the electronics industry in the region. This article shows how the former state monoliths in the region have been broken up or sold off, and profiles the emergence of new market-oriented companies. The low wage rates for assembly workers in the Czech Republic, Hungary and Poland make them a potential location for low-cost production close to the European Union. There is already clear evidence that German electronics companies are moving lower value-added activities to their Eastern neighbours 相似文献
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Darrell J. Bennett Robert P. Burford Thomas P. Davis Heath J. Tilley 《Polymer International》1995,36(3):219-226
A series of microemulsions have been formulated, with 2-hydroxyethyl methacrylate (HEMA) or HEMA/water/propanol mixtures as the continuous phase and methylcyclohexane as the discontinuous phase. The effect of surfactant type was investigated with the utilization of both anionic and nonionic surfactants. The microemulsion continuous phase was polymerized by UV radiation and a thermal post-cure. The resultant polymers were extracted to remove the discontinuous phase and the surfactant. On swelling, the majority of the polymers became opaque, although transparent PHEMA hydrogels were synthesized with an improved equilibrium water content (EWC). The cause of opacity was shown by field emission scanning electron microscopy (FESEM). The breakdown in the microemulsion on polymerization is caused by unfavourable interactions between the PHEMA and the stabilizing surfactants causing agglomerization of the discontinuous phase. All the hydrogels were found to have higher water retention than PHEMA, with EWCs of up to 70%. The modified polymers also demonstrated an increased rate of water diffusion into the matrix. A preliminary study of oxygen permability revealed that a significant improvement had been made over standard PHEMA membranes. The porous structure of the PHEMA gels has been shown to be dependent on the type of surfactant used during synthesis. 相似文献
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The role of androgens and the androgen receptor (AR) in the development and progression of breast cancer is poorly understood. To further define a potential model for androgen action in breast cancer, MDA-MB-453 cells, which express AR in the absence of oestrogen receptors and progesterone receptors, were further characterised in terms of AR expression and androgen responsiveness. High level expression of AR was confirmed by northern blot analysis, radioligand binding and immunocytochemistry, and could not be accounted for by AR gene amplification. Three endogenous androgen-responsive genes (fatty acid synthetase, gross cystic disease fluid protein of 15 kDa and prolactin receptor) and a transfected reporter gene, containing an androgen-responsive element, were induced following androgen administration. A synthetic androgen, mibolerone, induced moderate (27% above control) stimulation of MDA-MB-453 cell proliferation, which was abrogated by the simultaneous administration of the synthetic androgen antagonist, anandron, demonstrating that the effect was AR-mediated. In summary, MDA-MB-453 cells express high levels of functional AR, and thus provide a valuable in vitro model for further studies on androgen regulation of gene expression, and perhaps cell proliferation in breast cancer. 相似文献
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The preparation of glasses in the CoO-Fe2O3-B2O3 system is described and it is shown that the magnetic spinel cobalt ferrite (CoFe2O4) can be obtained in precipitate when the glasses are heat-treated. The identity of the crystalline phase is established by means of Mössbauer spectroscopy. It is shown that the magnetic properties of the glass-ceramics can be controlled by means of the heat-treatment schedule and intrinsic coercivities as high as 1900 Oe are recorded. The magnetic properties of the as-cast and heat-treated material are discussed generally in terms of superparamagnetic, single domain and multi-domain behaviour. The highest values of the intrinsic coercivity and remanence are compared to those calculated for an assembly of non-interacting single domain particles with positive cubic magnetocrystalline anisotropy. 相似文献
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The nature of the complexes formed between Cu(II) and LIX 65N (H2L) in ethanol has been studied by UV-visible spectrophotometry and the kinetics of the reaction between Cu(II) and H2L by stopped-flow spectrophotometry at 25°C. The major complex, Cu(HL)2, has a formation constant β2 = [Cu(HL)2]/[Cu][HL?]2 of log β2 = 26.5 l2 mol?2 in 0.04 M NaClO4. An additional complex, probably Cu(HL)+, can be detected in the absence of added NaClO4. A third complex, identified as Cu2(HL)22+, was observed at higher copper concentrations with formation constant Kd = [Cu2(HL)2]/[Cu(HL)2][Cu] 1.7 × 104 l mol?1 in 0.04 M NaCIO4. The rate of reaction of Cu(II) with H2L to form Cu(HL)2 obeys the rate equation, d[Cu(HL)2]/d t = Krate[Cu]1[H2L]1[H+]0 where Krate has the value of 2.9 × 104 l mol?1 s-1 in the absence of added electrolytes. 相似文献