538 research outputs found

    Empirical Study on Consumer Perceived On-line Payment Risk

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    This paper takes the potential release of online transaction market size as the starting point of research, and discusses how Chinese consumer perceived risks influence online payment willingness. This study divides consumer perceived risks of online payment into eight dimensions: Economic risk, Functional risk, Private risk, Security risk, Time risk, Service risk, Psychological risk and Social risk. Furthermore, it explores the influence of multi-dimensional perceived risks on the willingness of consumers’ online payment on the basis of 616 samples from Shanghai. The empirical results show that there is a significant negative correlation between perceived economic risks and the willingness to pay online; perceived security risks and some other risks have significant positive effect on payment willingness, which shows that certain perceived risks are becoming systemic risks in accordance with the principle of finance. So, the paper imply that both Private and Government third payment platforms shall take certain measures to reduce consumers’ specific perceived risk for promoting the development of online transaction market in China

    What Differs on the Enzymatic Acetylation Mechanisms for Arylamines and Arylhydrazines Substrates? A Theoretical Study

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    The acetylation mechanisms of several selected typical substrates from experiments, including arylamines and arylhydrazines, are investigated with the density functional theory in this paper. The results indicate that all the transition states are characterized by a four-membered ring structure, and hydralazine (HDZ) is the most potent substrate. The bioactivity for all the compounds is increased in a sequence of PABA ≈ 4-AS < 4-MA < 5-AS ≈ INH < HDZ. The conjunction effect and the delocalization of the lone pairs of N atom play a key role in the reaction. All the results are consistent with the experimental data

    Ceramic particles reinforced copper matrix composites manufactured by advanced powder metallurgy: Preparation, performance, and mechanisms

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    Copper matrix composites doped with ceramic particles are known to effectively enhance the mechanical properties, thermal expansion behavior and high-temperature stability of copper while maintaining high thermal and electrical conductivity. This greatly expands the applications of copper as a functional material in thermal and conductive components, including electronic packaging materials and heat sinks, brushes, integrated circuit lead frames. So far, endeavors have been focusing on how to choose suitable ceramic components and fully exert strengthening effect of ceramic particles in the copper matrix. This article reviews and analyzes the effects of preparation techniques and the characteristics of ceramic particles, including ceramic particle content, size, morphology and interfacial bonding, on the diathermancy, electrical conductivity and mechanical behavior of copper matrix composites. The corresponding models and influencing mechanisms are also elaborated in depth. This review contributes to a deep understanding of the strengthening mechanisms and microstructural regulation of ceramic particle reinforced copper matrix composites. By more precise design and manipulation of composite microstructure, the comprehensive properties could be further improved to meet the growing demands of copper matrix composites in a wide range of application fields

    Genetic variation analysis of reemerging porcine epidemic diarrhea virus prevailing in central China from 2010 to 2011

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    Porcine epidemic diarrhea has re-emerged with devastating impact in central China since October 2010. To investigate and analyze the reason of this outbreak, the M and ORF3 genes of 15 porcine epidemic diarrhea viruses (PEDV), which were collected from different areas of central China during October 2010 and December 2011, were amplified by reverse transcriptase polymerase chain reaction, cloned, sequenced, and analyzed. Sequence analyses showed that the nucleotides and amino acids were changed at some sites in the M and ORF3 genes of the 15 PEDV strains compared with those genes of CV777 reference strain. Based on the phylogenetic analyses, PEDVs in central China and reference strains could be separated into three groups: G1, G2, and G3. The 15 PEDV strains belonged to G3 group and showed a close relationship with Korean strains (2007), Thai strains (2007–2008), and partial other Chinese strains (2010–2011), but differed genetically from European strains (Br1/87) and the vaccine strain (CV777 vs) being used in China. Furthermore, all 15 PEDV strains from central China and some other isolates in China from 2003 to 2007 (LJB-03, QH, and LZC) belonged to different group. Therefore, PEDV exhibits rapid variation and genetic evolution, and the currently prevailing PEDV strains in central China are a new genotype
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