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51.
52.
Ram Devanathan William J. Weber 《JOM Journal of the Minerals, Metals and Materials Society》2007,59(4):32-35
The safe immobilization of nuclear waste in geological repositories is one of the major scientific challenges facing humanity
today. Crystalline ceramics hold the promise of locking up actinides from nuclear fuel and excess weapons plutonium in their
structure thereby isolating them from the environment. This paper presents the atomistic details of radiation damage in a
model ceramic, zircon. 相似文献
53.
Dorn R. Baumgartner A. Goth A. Gutu-Nelle A. Koppenborg J. Rehm W. Schneider R. Schneider S. von Wirth J. Weber D. 《Lightwave Technology, Journal of》1991,9(6):709-714
Mechanically shaped preforms (MSP) have been demonstrated to combine economic non-CVD (chemical vapor deposition) processing and low loss, with a published value of 0.63 dB/km and a size of 30 fkm/preform. Improved processing is proposed which results in a minimum loss of 0.27 dB/km at 1550 nm. Preforms capable of yielding 150 fkm have been produced. Reboiling during preform stretching and fiber pulling is identified as the last remaining problem of the process 相似文献
54.
55.
56.
W Blaas M Kellert L Krull M Schramm R Weber 《Zeitschrift für Lebensmittel-Untersuchung und -Forschung》1985,180(3):230-233
A method for the determination of 5-methoxypsoralene in suntan-cosmetics is described. After liquid chromatographic clean-up, the final extract is screened by twodimensional thin layer chromatography. For positive extracts 5-methoxypsoralene is analysed quantitatively by capillary gas chromatography, using 5-alpha-cholestane as an internal standard and flame ionization detection (FID). The results were confirmed by gas chromatography-mass spectrometry (GC-MS). The recoveries for suntan-cosmetics of emulsion type were 70% and for tanning oils 90%. Detection limits of the method were 0,1 to 0,5 mg/kg, depending on the sample type. By application of this method 5-methoxypsoralene was detected in 6 of the 21 cosmetic products at levels up to 28 mg/kg. 相似文献
57.
PS Frenette S Subbarao IB Mazo UH von Andrian DD Wagner 《Canadian Metallurgical Quarterly》1998,95(24):14423-14428
The adhesive mechanisms allowing hematopoietic progenitor cells (HPC) homing to the bone marrow (BM) after BM transplantation are poorly understood. We investigated the role of endothelial selectins and vascular cell adhesion molecule-1 (VCAM-1) in this process. Lethally irradiated recipient mice deficient in both P-and E-selectins (P/E-/-), reconstituted with minimal numbers (=5 x 10(4)) of wild-type BM cells, poorly survived the procedure compared with wild-type recipients. Excess mortality in P/E-/- mice, after a lethal dose of irradiation, was likely caused by a defect of HPC homing. Indeed, we observed that the recruitment of HPC to the BM was reduced in P/E-/- animals, either splenectomized or spleen-intact. Homing into the BM of P/E-/- recipient mice was further compromised when a function-blocking VCAM-1 antibody was administered. Circulating HPC, 14 hr after transplantation, were greatly increased in P/E-/- mice treated with anti-VCAM-1 compared with P/E-/- mice treated with just IgG or wild-type mice treated with either anti-VCAM-1 or IgG. Our results indicate that endothelial selectins play an important role in HPC homing to the BM. Optimal recruitment of HPC after lethal doses of irradiation requires the combined action of both selectins and VCAM-1 expressed on endothelium of the BM. 相似文献
58.
Semiconductor laser amplifier as optical switching gate 总被引:3,自引:0,他引:3
Ehrhardt A. Eiselt M. Grossopf G. Kuller L. Ludwig R. Pieper W. Schnabel R. Weber H.G. 《Lightwave Technology, Journal of》1993,11(8):1287-1295
The properties of a semiconductor laser amplifier as optical switching gate are investigated. Particular attention is paid to gain, contrast ratio, and switching time of the device. These properties are studied experimentally and theoretically with respect to the injection current, optical input power, and cavity resonances. The experimental arrangements and the theoretical method are described. As an example of the various applications of semiconductor laser amplifier gates, packet switching experiments with self-routing, employing cascaded switching gates, are reported. In a theoretical analysis the restrictions that the properties of semiconductor laser amplifier gates impose on a larger switching system consisting of many such gates are investigated 相似文献
59.
Wang K. Bryant C. Carlson M. Elmer T. Harris A. Garcia M. Hui C.S. Leong C.K. Reynolds B. Tang R. Weber L. Wenzel J. Wilson G. Becker M. 《Micro, IEEE》1995,15(2):44-49
The MPC105 peripheral component interconnection bridge/memory controller provides a platform-specification-compliant bridge between Power PC microprocessors and the PCI bus. With it, designers can create systems using peripherals already designed for a variety of standard PC interfaces. This bridge chip also integrates a secondary cache controller and high-performance memory controller that supports DRAM or synchronous DRAM and ROM or flash ROM 相似文献
60.
Fibre-reinforced plastics (FRPs) are candidate materials for the insulation of superconducting magnet coils in future fusion reactors. This paper reports on a test programme performed to assess the mechanical properties of these materials and to obtain information on the damage and fracture mechanisms. Different types of FRPs (epoxies and poly- and bismaleimides as resins; two- and three-dimensional E-, S- or T-glass fabrics as reinforcements) were irradiated at room temperature by 2 MeV electrons and 60Co-gamma rays up to 1.8 × 108 Gy and by different reactor spectra up to a neutron fluence of 1 × 1023 m−2 (E > 0.1 MeV) at room temperature, 80 K or 5 K. Mechanical tests in tension as well as in the intralaminar crack opening and shear mode were carried out on the irradiated samples at 77 K. After low temperature irradiation, half of the samples were subjected to a warm-up cycle to room temperature before testing at 77 K. Results on the influence of different radiation sources and annealing cycles on the mechanical properties of these materials will be discussed. 相似文献