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21.
A novel GaAs logic family, pseudodynamic latched logic (PDLL), is presented in this paper. It is composed of a dynamic circuit where the logic is performed and a static latch whose function is to permanently refresh the stored data on a dynamic node. Because of this hybrid structure, PDLL takes advantage of both static and dynamic families and thus, permits implementation of very complex structures with good speed-area power tradeoff. Moreover, the inclusion of the latch permits this class of logic family to be highly efficient for pipelined systems working even at high temperature without loss of data due to leakage currents. Barrel-shifters, programmable logic arrays (PLA's), and carry lookahead adders (CLA's) were verified by simulations demonstrating its feasibility for the development of high-performance very large scale integration (VLSI) systems  相似文献   
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Aqueous extracts of the coralline red algaeBossiella orbigniana have been shown to catalyze the enzymatic oxidation of arachidonic acid to a previously unreported ω6 eicosapentaenoic acid product. This unique fatty acid contains a conjugated tetraene with absorption maxima at 293, 306, and 321 nm, and was identified by spectral methods as 5(Z),8(Z),10(E),12(E),14(Z)-eicosapentaenoic acid. The compound was given the trivial name bosseopentaenoic acid. Under experimental conditions, production of bosseopentaenoic acid was linear up to 2 hr and dioxygen was consumed. Bosseopentaenoic acid, along with several other conjugated tetraenes, was also present in the algae endogenously as revealed by a comparison of the ultraviolet (UV) spectra and the high-performance liquid chromatographic (HPLC) pattern of the purified product and the organic extract ofBossiella.  相似文献   
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The interaction of ammonium stearate (AS) and γ-aminopropyltriethoxysilane (APS) treatments with a magnesium hydroxide flame retardant filler and their effects on its use in an ethylene vinyl acetate copolymer compound have been investigated. The work has shown clear evidence of changes in the structure of the surface layers formed on the filler as the amount of additive is increased and the levels at which these occur can be correlated with theoretical monolayer quantities. Infrared (IR) spectroscopy data suggest that the stearate coating changes from a half salt to a full salt as the coating level is increased and that the APS coating on the filler initially has a significant bicarbonate content, presumably due to reaction with atmospheric carbon dioxide. The effect of coating level on the melt flow rate, insoluble matrix content, crystallisation behaviour, tensile properties, limiting oxygen index, and ageing of the filled compound has been studied. Distinct trends have been observed, many of which can be correlated with the structure of the filler surface layers. Of particular importance is the observation that, unlike APS, excess stearate appears to promote detrimental ageing effects.  相似文献   
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Short staffing and insufficient technical and business knowledge among staff members can hinder information centers from meeting the needs of end users. Establishing groups of selected users with special skills improves end-user computing by opening communication channels, influencing training objectives, and fostering better user morale. This article explains the types of user groups that an information center can establish and the benefits to be derived from them.  相似文献   
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Two different techniques that allow the implementation of embedded ROMs using a conventional GaAs MESFET technology are presented. The first approach is based on a novel circuit structure named low leakage current FET circuit (L2FC), which reduces significantly subthreshold currents. The second approach is based on pseudo current mode logic (PCML) which is by far the best choice in terms of noise margin levels. This characteristic is found to be the key factor when implementing GaAs ROM's because of its degradation as the number of word lines is increased. A 5-Kb ROM and a 2-Kb ROM were designed giving delays in the order of 2 ns and less than 1 ns, respectively. The results demonstrate the effectiveness of these techniques and their significance toward improving the noise margin  相似文献   
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Low temperature heat capacity measurements have been made on hot isostatically pressed Nb3Sn and arc cast, homogenized, and A15 transformation annealed V-23.3 at. pct Ga and V-18.1 at. pct Ga. The heat capacity measurements display the superconducting transition temperature (T c), and have been used to evaluate the effects of plastic deformation on theT c range. Plastic deformation to the extent of 15 pct compression at 1525 and 1650 °C does not alter the superconducting transition in polycrystalline Nb3Sn. Plastic deformation to the extent of 15 pct compression at 1050 and 1200 °C does not alter the superconducting transition in polycrystalline V-23.3Ga, transformed to A15 structure with a fifty-hour 1150 °C anneal. The same statement can be made for A15 V-18.1Ga, deformed at 1050 °C after a fifty-hour, 1150 °C anneal. With onlyfive hours annealing at 1150 °C, A15 V-23.2Ga displays a lowering and broadening of theT c range upon 1050 and 1200 °C plastic deformation. With onlyfive hours annealing at 1150 °C, A15 V-18.1Ga displays a broad, but increasedT c range after plastic deformation at 1050 °C.  相似文献   
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