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  • 1
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Changes in the extent of P700 oxidation (P700+) were investigated after chilling of barley, rice, pumpkin, and cucumber leaf segments at 4°C for 1 h under light with various photon flux densities. At 50 µmol photons m−2 s−1, the decrease in P700+ was observed only in cucumber, but at 150 µmol photons m−2 s−1, it was found in all plants except barley, revealing their expected chilling sensitivities. However, the decrease in P700+ by this short-term chilling was reversible in the presence of 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea or methyl viologen, and it did not show any causal relationship with the decrease in the electron transfer rate nor with the down-regulation of photosystem II through the accumulation of zeaxanthin and the development of non-photochemical quenching. These results led to the suggestion that photosystem I (PSI) acceptor side limitation is a prerequisite for the decrease of P700+. Furthermore, PSI acceptor side limitation could be mainly due to limitation of electron-sink pathways such as CO2 assimilation and ascorbate–glutathione cycle, because treatment with glycolaldehyde which inhibits the former pathway, and with KCN which inhibits both pathways, decreased P700+ by 20–30% in barley leaves after chilling in the light.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Telecommunication systems 14 (2000), S. 31-45 
    ISSN: 1572-9451
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper, we investigate the performance of convolutional coded DS/CDMA with noncoherent M-ary orthogonal modulation operating in a multi-user environment over a slow and frequency nonselective Nakagami-m fading channel with additive white Gaussian noise (AWGN). An expression for the pairwise error probability that can be used to compute the upper bound of coded system is first derived. Performance of the DS/CDMA system with and without the convolutional codes is then presented. We have observed that convolutional codes can compensate for the degradation quite well in multi-user situations over Nakagami fading channels with AWGN. For the case of an extreme fading, however, it has been seen that the convolutional code reaches its limit to improve the overall system performance as the number of users increase.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: We have developed a large area, flat panel detector for general applications to digitalradiology. This paper presents the x-ray detection characteristics with various semiconductorradiation detectors (HgI2, PbI2, PbO, CdTe) derived by a novel wet coating process for large areadeposition. The wet coating process could easily be made from large area films with printing pastemixed with semiconductor and binder material at room temperature. X-ray performance data such asdark current, sensitivity and signal to noise ratio (SNR) were evaluated. The HgI2 semiconductor wasshown in much lower dark current than the others, and also has the best sensitivity. In this paper,reactivity and combination characters of semiconductor and binder material that affect electrical andx-ray detection properties would be verified through our experimental results
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: In this paper, we present the imaging parameters and compare both mercuric iodide (HgI2)and amorphous selenium (a-Se) films. Using MCNPX code, we designed the film structure and itsthickness for the optimized detector in the diagnostic x-ray range. The mercuric iodide film wasformed by a wet binder process, while the amorphous selenium film was deposited by physical vapordeposition (PVD). These deposition methods are capable of being scaled up to sizes required indiagnostic imaging applications. The electronic properties are investigated using dark current, x-raysensitivity and signal to noise ratio (SNR). From our results, the developed HgI2 film as an alternativeto a-Se photoconductor, which is in practical use in flat panel x-ray imaging detector, will prove itsusefulness in the future design and the optimization for various diagnostic modalities
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 510-511 (Mar. 2006), p. 490-493 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Flow patterns and mixing behaviors in a gas stirred steelmaking ladle with a slag layer were discussed using a water model experiment as well as a numerical simulation. While the water model experiment was performed to investigate the effect of slag on the mixing behavior in ladle, the numerical simulation was carried out to figure out the flow pattern in ladle with a slag layer. Slag viscosity and its thickness in ladle were considered as major variables. It was found that a slag layer made a great change in the flow pattern in ladle, which, in turn, affected on the mixingbehavior in ladle. A flow pattern without a slag layer showed that rising bubbles eventually made a recirculation loop at the central area of the ladle and this flow pattern was regarded as a favorable flow pattern for the better mixing behavior. However, a flow pattern with a slag layer showed distorted and localized recirculating loop near side wall below slag layer. This eventually gave alonger mixing time in ladle with a slag layer. Moreover, as the gas flow rate increases, slag existing on top of the ladle was found to be entrained into the melt. Slag viscosity and its thickness were found to be major variables affecting the behavior of slag entrainment. Lower the slag viscosity and thicker the slag layer, much more slag on top of the melt was entrained into the melt
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 510-511 (Mar. 2006), p. 494-497 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: It is generally well known that a steelmaking ladle operation plays an important role inthe production of clean steel. A turbulent mixing of melt with Ar gas bubbling from the ladle bottom can homogenize a melt temperature and can control precisely chemical compositions of steel. In order to figure out these phenomena, a quantitative analysis of fluid flow behavior of gas and melt during a ladle operation is required and special concerns should be focused on effects of operating parameters on the perfect mixing time of melt. In this study, as a basic approach, effects of operating parameters such as a melt depth (aspect ratio) and a nozzle type (one-hole or porous plug) on the mixing behavior in ladle operation are investigated. Water model experiments are carried out to simulate these melt behaviors in steelmaking ladle. As a result, it was found that there exist an optimized melt depth and a nozzle type at a given gas flow rate, which affect significantly on the mixing behavior of melt
    Type of Medium: Electronic Resource
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