137 resultados para AK40-4323


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Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-06-04T08:36:34Z No. of bitstreams: 1 dspace.cfg: 33388 bytes, checksum: ac9630d3fdb36a155287a049e8b34eb7 (MD5)

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本文介绍了现场总线的概念、协议模型和相关标准,分析和总结了工业过程控制系统通信网络要求和电气控制系统的功能要求,提出基于现场总线技术实现电气系统和过程控制系统的集成的解决方案,该方案是控制系统现场网络的发展方向。

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The crystal structures of EtEDTB.1.4C(2)H(5)OH.5H(2)O 1 and H4EtEDTB(ClO4)(4).C2H5OH 2 (EtEDTB = N, N,N',N'-tetrakis[2-(1-ethylbenzimidazolyl)methyl]-1,2-ethanediamine) have been determined by single-crystal X-ray diffraction method. Compound 1 crystallizes in the space group P(1) over bar with a = 11.489(2), b = 11.866(3), c = 12.002(3) Angstrom, alpha = 97.47(2), beta = 114.564(13), gamma = 114.11(2)degrees, V = 1266.6(5) Angstrom(3), Z = 1, M-r = 847.48, D-c = 1.111 g/cm(3), F(000) = 456 and mu(MoKalpha) = 0.076 mm(-1). A total of 5207 reflections were measured for 1, of which 4323 were independent. The structure of 1 was solved by direct methods and refined by full-matrix least-squares technique to the final R = 0.0706 and wR = 0.1802 for 1318 observed reflections with I > 2sigma(I). In the structure of 1, centrosymmetric EtEDTB molecules are linked by hydrogen bonds through water and ethanol to form 2-dimensional network. Compound 2 crystallizes in the space group C2/c with a = 24.260(5), b = 13.040(3), c = 17.680(4) Angstrom, beta = 97.50(3)degrees, V = 5545.2(2) Angstrom(3), Z = 4, M-r = 1140.80, D-c = 1.366 g/cm(3), F(000) = 2384 and mu(MoKalpha) = 0.289 mm(-1).

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Three kinds of surfactants as stabilizer were applied to the preparation of electrocatalysts for direct methanol fuel cell (DMFC). The catalysts have been characterized by examining their catalytic activities, morphologies and particle sizes by means of cyclic voltammetry, chronoamperometry, X-ray diffraction and transmission electron microscopy (TEM). It is found that the surfactants with different structures have a significantly influence on the catalyst shape and activity. The catalysts prepared with non-ionic surfactants as the stabilizer show higher activity for direct oxidation of methanol. The structure-activity relationship (SAR) analysis has been explored and the effect of hydrophile-lipophile balance (HLB value) has also been discussed.

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Thymic graft-versus-host disease (tGVHD) can contribute to profound T cell deficiency and repertoire restriction after allogeneic BM transplantation (allo-BMT). However, the cellular mechanisms of tGVHD and interactions between donor alloreactive T cells and thymic tissues remain poorly defined. Using clinically relevant murine allo-BMT models, we show here that even minimal numbers of donor alloreactive T cells, which caused mild nonlethal systemic graft-versus-host disease, were sufficient to damage the thymus, delay T lineage reconstitution, and compromise donor peripheral T cell function. Furthermore, to mediate tGVHD, donor alloreactive T cells required trafficking molecules, including CCR9, L selectin, P selectin glycoprotein ligand-1, the integrin subunits alphaE and beta7, CCR2, and CXCR3, and costimulatory/inhibitory molecules, including Ox40 and carcinoembryonic antigen-associated cell adhesion molecule 1. We found that radiation in BMT conditioning regimens upregulated expression of the death receptors Fas and death receptor 5 (DR5) on thymic stromal cells (especially epithelium), while decreasing expression of the antiapoptotic regulator cellular caspase-8-like inhibitory protein. Donor alloreactive T cells used the cognate proteins FasL and TNF-related apoptosis-inducing ligand (TRAIL) (but not TNF or perforin) to mediate tGVHD, thereby damaging thymic stromal cells, cytoarchitecture, and function. Strategies that interfere with Fas/FasL and TRAIL/DR5 interactions may therefore represent a means to attenuate tGVHD and improve T cell reconstitution in allo-BMT recipients.

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Density functional calculations, using B3LPY/6-31G(d) methods, have been used to investigate the conformations and vibrational (Raman) spectra of three short-chain fatty acid methyl esters (FAMEs) with the formula CnH2nO2 (n = 3-5). In all three FAMEs, the lowest energy conformer has a simple 'all-trans' structure but there are other conformers, with different torsions about the backbone, which lie reasonably close in energy to the global minimum. One result of this is that the solid samples we studied do not appear to consist entirely of the lowest energy conformer. Indeed, to account for the 'extra' bands that were observed in the Raman data but were not predicted for the all-trans conformer, it was necessary to add-in contributions from other conformers before a complete set of vibrational assignments could be made. Provided this was done, the agreement between experimental Raman frequencies and 6-31G(d) values (after scaling) was excellent, RSD = 12.6 cm(-1). However, the agreement between predicted and observed intensities was much less satisfactory. To confirm the validity of the approach followed by the 6-3 1 G(d) basis set, we used a larger basis set, Sadlej pVTZ, and found that these calculations gave accurate Raman intensities and simulated spectra (summed from two different conformers) that were in quantitative agreement with experiment. In addition, the unscaled Sadlej pVTZ, and the scaled 6-3 1 G(d) calculations gave the same vibrational mode assignments for all bands in the experimental data. This work provides the foundation for calculations on longer-chain FAMEs (which are closer to those found as triglycerides in edible fats and oils) because it shows that scaled 6-3 1 G(d) calculations give equally accurate frequency predictions, and the same vibrational mode assignments, as the much more CPU-expensive Sadlej pVTZ basis set calculations.

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Existing empirical evidence on substance use among young people living in residential state care during adolescence is comparatively limited. This paper reports on substance use trends of young people living in residential state care during three annual data-sweeps when aged 14, 15 and 16 years. A repeated cross-sectional research design was utilised in the research. The findings suggest some similarities for lifetime prevalence rates for tobacco and alcohol use for those living in residential state care with a group of same-age young people not living in residential state care who participated in the research. However, solvent abuse and cannabis use was higher among those living in care. More frequent substance use was reported by the residential care sample for all substances at each stage of the study. These findings suggest that young people living in state care continue to merit higher levels of vigilance from researchers and policy-makers in order to fully understand this behaviour and develop appropriate prevention initiatives to meet their needs regarding potential drug problems.