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刘翔  陈学  H.  HOMMA  Y.  HATANO  M.  MATSUYAMA 《等离子体科学和技术》2006,8(6):741-744
A non-destructive and in-situ technique for the measurement of tritium in materials, namely β-ray-induced X-ray spectrometry (BIXS), has been developed recently. In the present study a V-4Cr-4Ti alloy was pre-heated at 1000℃ for 2 h to form a recrystallization structure before the tritium absorption experiments were conducted. Firstly the hydrogen isotope gas was charazterized by means of a quadrupole mass spectrometer (QMS) and a small-sized ionization chamber. Then hydrogen isotope absorption tests of V-4Cr-4Ti alloy were performed at 400 ℃ and the atomic concentration of hydrogen isotope in V-4Cr-4Ti alloy was estimated as 0.17% with a tritium content of approximately 2.5 ppm. Experimental results indicate that BIXS is a quite useful tool for quantitatively measuring the tritium content and tritium distribution in the surface layers of vanadium alloys and no strong trapping effects of tritium exist in the pre-heated V-4Cr-4Ti alloy.  相似文献   
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This paper presents a novel prototype of a single‐stage zero voltage soft‐switching pulse‐width modulation ‐controlled ac‐ac converter with a silicon carbide (SiC)‐MOSFET/SiC‐SBD power module for high‐frequency (HF) induction heating (IH) applications. The newly developed ac‐ac converter can achieve higher efficiency than a Si‐IGBT/Si‐PN diode power module‐based prototype due to a low ON‐resistance of SiC‐MOSFET and a low forward voltage of SiC‐SBD under the condition of HF switching. The performances of the new prototype converter are evaluated by experiment with a single‐phase IH utensil of ferromagnetic stainless metal, after which the high‐efficiency and low switching noise characteristics due to the all SiC power module are actually demonstrated.  相似文献   
3.
A five‐element multiplex resonant (LLCLC) full‐bridge DC‐DC converter controlled by pulse frequency modulation (PFM) is proposed in this paper. The high frequency (HF)‐link resonant DC‐DC converter proposed herein can perform wide‐range output power and voltage regulation with a narrow frequency range due to an antiresonant tank that works effectively as a wide‐range variable inductor. The advantageous characteristics of the antiresonant tank provide overcurrent protection in the case of the short‐circuited load condition as well as in the startup interval. Thus, the technical challenges of a conventional LLC DC‐DC converter can be overcome, and the reliability of the relevant switch‐mode power supplies can be improved. The operating principle of the LLCLC DC‐DC converter is described, after which its performance is evaluated in an experimental setup based on the 2.5 kW prototype. Finally, the feasibility of the proposed DC‐DC converter is discussed from a practical point of view.  相似文献   
4.
Various biochemical parameters measured in sockeye salmon, Oncorhynchus nerka, feeding in the Gulf of Alaska in July during the maturation process were contrasted with those obtained from mature sockeye salmon in Steep Creek, a small salmon stream near Juneau, Alaska. Degenerative changes in muscles, such as decrease in total lipid and protein contents in mature salmon were attributed both to the progressed activation of lipid hydrolytic enzymes and to autolytic activity, in addition to the inactivation of lipid and protein syntheses in muscle and liver. The depletion of lipid is associated with the energy utilization for migration and gonadal maturation as a result of the cessation of feeding.  相似文献   
5.
Microscopes in vacuum ultraviolet and soft X-ray regions using a normal incidence type of Schwarzschild objective are reviewed. The objective consists of a concave mirror and a convex mirror coated with a high reflectance multilayer, having a large numerical aperture comparing with other objectives. The microscopes have been used to diagnose inertia-confinement-fusion plasmas, and to investigate small samples or microstructures of inorganic and organic materials by imaging them using laboratory light sources. Synchrotron radiation has been also used to obtain a microbeam for a photoelectron scanning microscope with a spatial resolution of 0.1 μm. The structure and performance of two laboratory microscopes developed at Tohoku University are demonstrated. One of them is a soft X-ray emission imaging microscope, An image of an artificial pattern made of W and SiO2 on Si wafer by focusing Si L emission was presented, The other is an ultraviolet photoelectron scanning microscope using a He (helium) gas discharge lamp. The valence band spectra of a microcrystal of FeWO4 were presented, Furthermore other applications such as demagnifying optics for lithography and optics to gather fluorescence for emission spectroscopy are introduced.  相似文献   
6.
Multilayer polarization elements and their applications to polarimetric studies in 20~400 eV region are mainly reviewed.General principle of selecting material combinations to get high linear polarizance multilayers of reflection type is given with practical examples,with periodic or non-periodic layer structures depending on the usage.Transmission type is introduced as linear polarizer and phase shifter.Their applications include polarization diagnosis of laboratory optical systems and synchrotron radiation beamlines of linear and circular polarization,magnetic rotation experiments such as Faraday rotation and magnetic Kerr rotation on magnetic films and multilayers,and ellipsometry to measure optical constants of thin films precisely.Polarization analysis of soft X-ray fluorescence using multilayer-coated grating is also mentioned.Finally this review is summarized with outlook of further developments.  相似文献   
7.
A nondestructive textural quality measurement technique that uses an acoustic property was studied for apples and watermelons. By means of digital Fourier analysis, the natural frequencies of intact fruits are obtained from the sound which is produced by hitting them with a wooden ball pendulum. The reliability of this method was confirmed. This method requires simpler instrumentation than the sonic vibrating resonance method.  相似文献   
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Phosphatidylethanolamine (PE), which contains highly unsaturated fatty acid (HUFA) specifically in sn -2 position, was synthesized by porcine pancreatic phospholipase A2-catalysed esterification of lysophosphatidylethanolamine with HUFA. the use of glycerol containing only a little water as solvent was the important key to this reaction. A 27% yield of up to 94.5% sn -2 eicosapentaenoic acid (EPA)-containing PE was obtained using >99% EPA as a substrate HUFA.  相似文献   
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