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71.
A path-based timing optimization algorithm for buffer insertion and simultaneous sizing is proposed. Firstly, candidate buffer insertion location and buffer size for each branch in a given routing path were obtained via localized timing optimization. Then, through evaluating each potential insertion against design objectives, potential optimal buffer insertion locations and sizes for the whole routing tree were determined. At last, by removing redundant buffer insertion operations which do not maximize S ( so ), given timing requirements are finally fulfilled through minimum number of buffers. 相似文献
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HU Tao YANG Weiwei WANG Cheng BU Yali JIN Feng ZHANG Dongwen GU Min LIU Wenhui LIANG Qinghua LIU Ruiqing FENG Xiaomiao MA Yanwen 《高等学校化学研究》2021,37(2):286-292
Sodiumion batteries(SIBs)have attracted intensive attention as promising alternative to lithium-ionbatteries(LIBs)for large scale energy storage systems because of low cost of sodium,similar energy storage mechanism and the reasonable performance.However,it is still a great challenge to search and design a robust structure of anode materials with excellent cycling stability and high rate capability for SIBs.Herein,multilayer porous vanadium nitride(VN)microsheets are synthesized through a facile and scalable hydrothermal synthesis-nitrogenization strategy as an effective anode material for SIBs.The multilayer porous VN microsheets not only offer more active sites for fast Na+insertion/extraction process and short diffusion pathway,but also effectively buffer the volume change of anode due to more space in the multilayer porous structure.The large proportions of capacitive behavior imply that the Na+charge storage depends on the intercalation pseudocapacitive mechanism.The multilayer porous VN microsheets electrodes manifest excellent cycling stability and rate capability,delivering a discharge capacity of 156.1 mA·h/g at 200 mA/g after 100 cycles,and a discharge capacity of 111.9 mA·h/g at 1.0 A/g even after 2300 cycles with the Coulombic efficiency of nearly 100%. 相似文献
73.
本文采用XRD、XPS、及H_2—TPD技术对不同Cu/Co比的几个RaneyCu-Co催化剂进行了表征.并与反应醇选择性进行了关联.结果表明:RaneyCu-Co催化剂均由不同Cu/Co比的两个Cu-Co固溶体相组成,还原(H_2,563K,2h)前,表面除有Cu ̄0和Co ̄0外,尚有少量Cu ̄(+1)和显著量的Co ̄(+2)存在,还原后,Cu ̄(+1)几乎消失,Co ̄(+2)仍有一定量存在,在反应温度下(563K),CO和CO_2均能使表面Co ̄0部分氧化,且CO_2氧化能力大于CO,而合成气(H_2/CO=2)表现为还原的性质。三种气氛对Cu ̄0无明显影响。催化剂表面Cu/Co比高于体相Cu/Co比,表面Cu富集显著.RaneyCu-Co催化剂表面有四种吸氢中心:Cu(弱吸氢中心),高配位Co(弱吸氢中心),低配位Co(活化吸氢中心),及强吸氢中心;对不同催化剂,表面低配位Co中心的比例与醇选择性有一致的变化规律。基于上述结果,就CO播入中心进行了讨论。 相似文献
74.
近年来,人们对二次锂电池的正极进行了不少研究。许多过渡金属氧化物或硫化物,如V_6O(13),Li_(1+x)V_3O_8,TiS_2,MoS_2等被认为是较好的正极材料。Pistoia等研究了Li_(1+x)V_3O_8钒青铜的电化学性能得出,当Li浓度高时,由于电子定域作用使电荷屏蔽效应 相似文献
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76.
(NH_4)_2SiF_6预处理改善SBA-15介孔材料的水热稳定性 总被引:1,自引:0,他引:1
(NH4)2SiF6 预处理可对 SBA-15 介孔材料的表面缺陷进行补硅修正以及表面疏水化, 从而明显改善 SBA-15 材料的水热稳定性. 结果表明, 用摩尔分数为 5% 的 (NH4)2SiF6 水溶液, 按引入 1% 的 SiO2 计量对 SBA-15 进行处理后, 其水热稳定性明显改善, 在 100 ?C 沸水中处理 14 d, 或在 800 ?C 下用 100% 水蒸气处理 12 h 后, 均保持较好的介观有序度、形貌及六方孔道结构, 比表面积分别高达 310 和 213 m2/g, 但 (NH4)2SiF6 处理量过高, SBA-15 水热稳定性反而下降. 相似文献
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Flavin-containing monooxygenase (FMO), like cytochrome P450 (CYP), is a monooxygenase that uses the reducing equivalents of NADPH to reduce one atom of molecular oxygen to water, while the other atom is used to oxidize the substrate. Recently, it was shown that some CYP isoforms have been subject to positive selection. However, it is unknown whether the highly conserved phase I detoxification enzyme, FMO, has undergone similar positive Darwinian selection. We used maximum-likelihood models of codon substitution, evolutionary fingerprinting, and cross species comparison to investigate the occurrence of adaptive evolution in FMO sequences. We used recent genomic data from a range of species, including vertebrates and invertebrates. We present the evidence for the occurrence of adaptive evolution in mammalian FMO 3, 4, 5, and fugu FMOs but not in mammalian FMO 1, FMO 2, frog FMOs, other fish FMOs and invertebrate FMOs. The sites under adaptive evolution were significantly associated with the insertion domain in mammalian FMO 5. We identified specific amino acid sites in FMOs 3–5 that are likely targets for selection based on the patterns of parallel amino acid change. The most likely role of adaptive evolution is the repair of mutations that permitted optimal NADP+ binding and improved catalytic efficiency. The occurrence of positive selection during the evolution of phase I detoxification enzymes such as FMOs 3–5 and fugu FMO suggests the occurrence of both high selection pressure acting on species within their unique habitats and significant changes in intensity and direction (forms of xenobiotics and drugs) resulting from changes in microhabitat and food. 相似文献
80.
SOFM神经网络已经成功应用到TSP问题中,但是该算法存在一些缺点,随着学习速度逐步降低,会导致一些城市无法通过。针对这些缺点,尝试在SOFM神经网络中引入最近插入法形成混合算法。通过实验,并与SOFM神经网络该算法对比,结果表明,该算法能够很好地完善该问题。 相似文献