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Now showing items 129 - 144 of 175

  • Pyrosequencing analysis revealed complex endogenetic microorganism community from natural DongChong XiaCao and its microhabitat

    Xia, Fei   Liu, Yan   Guo, Meng-Yuan   Shen, Guang-Rong  

    Background: Ophiocordyceps sinensis (DongChong XiaCao (DCXC) in Chinese), a fungal parasite of caterpillars, is a traditional Chinese medicine. Bioactive components isolated from natural DCXC possess a wide range of pharmacological actions. Many efforts have been directed towards isolating the fungi based on culture-dependent methods for investigation of fungal diversity in order to determine the anamorph of natural DCXC and find new medicinal fungi resources, and the results have been varied.Results: In the present study, a total of 44,588 bacterial and 51,584 fungal sequences corresponding to 11,694 and 9297 putative operational taxonomic units (OTU) were respectively identified by a Roche/454-based, high throughput sequence analysis of 16S rRNA genes and ITS regions. The main bacterial groups were Proteobacteria, Acidobacteria, Bacteroidetes, Actinobacteria and Firmicutes, while the Ascomycota, Basidiomycota and Zygomycota were the main fungal phyla. Proteobacteria presented 68.4, 49.5, 38.9 and 35.6 % of all bacteria in the sclerotia, stromata, external mycelial cortices and soil, respectively. As the main fungi phyla, Ascomycota presented 21.0, 45.6 26.4 and 59.3 % in the sclerotia, stromata, external mycelial cortices and soil, respectively. Bacterial and fungal communities were more diverse in the environmental sample than in the natural DCXC sample. Microbial communities were obviously distinct in each sample. Several novel unclassifiable bacterial (10.41 %) and fungal (37.92 %) species were also detected.Conclusions: This study revealed an abundant endogenetic fungal and bacterial resources and a variety of genetic information in natural DCXC by high-throughput 454 sequencing technology. Microorganism that had been discovered in natural DCXC will provide sources for screening the new bioactive metabolites and its biotechnological application.
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  • Combination of transition metal Rh-catalysis and tautomeric catalysis through a bi-functional ligand for one-pot tandem methoxycarbonylation-aminolysis of olefins towards primary amides

    Wang, Peng   Liu, Lei   Luo, Zhoujie   Zhou, Qing   Lu, Yong   Xia, Fei   Liu, Ye  

    Combination of transition metal catalysis with organocatalysis in ways of synergetic catalysis, cooperative catalysis, or/and sequential catalysis has been emerged as a powerful strategy to promote organic transformations that cannot be achieved by each individual independently. Herein, a new protocol for the synthesis of primary amides from olefins, CO and NH3 through one-pot tandem methoxycarbonylation-aminolys was presented over a bi-functional ligand (Li) based rhodium catalyst with functions of co-catalysis. Li is composed of the phosphino-fragment and the amino-/imino-tautomeric moiety. Then Ll-based Rh-catalytic system demonstrated a combination of Rh-P transition metal catalysis and the tautomeric catalysis. In this tandem methoxycarbonylation-aminolysis, NH3 also served as a ligand to work together with the phosphino-fragment to synergetically modify the performance of Rh-catalyst responsible for the first-step methoxycarbonylation of olefin to generate the esters, and the Rh-tailed tautomeric catalyst was in charge of the subsequent aminolysis to generate the targeted primary amides. (C) 2018 Elsevier Inc. All rights reserved.
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  • Density functional study of protonation of deoxynucleosides: Electrophilic active sites and proton affinities RID G-3335-2010

    Xia, Fei   Xie, Hujun   Cao, Zexing  

    Possible low-energy tautomers and their interconversions, electrophilic active sites, and proton affinities of deoxyribonucleosides have been studied by the density functional theory. The calculated results indicate that the protonation features of deoxyribonucleosides are less changed as compared with their corresponding bases. Proton affinities of 2'-deoxyriboguanosine (dG), 2'-deoxyribocytidine (dC), 2'-deoxyriboadenosine (dA), and 2'-deoxyribothymidine (dT) at the most favored sites are 240.6 kcal mol(-1) (N7), 238.5 kcal mol(-1) (N3), 233.4 kcal mol(-1) (N1), and 217.9 kcal mol(-1) (O4), respectively. Predicted tautomerization barriers are substantially high and exclude the coexistence possibility of their low-energy tautomers at room temperatures. Calculations show good agreement with experiments and provide a basis for description of structures and energetics of neutral and protonated deoxyribonucleosides. (C) 2007 Wiley Periodicals, Inc.
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  • Microscopic sensors using optical wireless integrated circuits

    Cortese, Alejandro J.   Smart, Conrad L.   Wang, Tianyu   Reynolds, Michael F.   Norris, Samantha L.   Ji, Yanxin   Lee, Sunwoo   Mok, Aaron   Wu, Chunyan   Xia, Fei   Ellis, Nathan I.   Molnar, Alyosha C.   Xu, Chris   McEuen, Paul L.  

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  • Magnetic field induced band formation and crystal orientation in directionally solidified Cu-20 wt.% Sn peritectic alloys

    Xia, Fei   Lu, Zhenyuan   Gagnoud, Annie   Fautrelle, Yves   Moreau, Rene   Li, Xi  

    The influence of a weak transverse magnetic field on the microstructure in directionally solidified Cu-20 wt.% Sn peritectic alloys at low speeds (0.8-1.2 mu m/s) was investigated. Experimental results indicated that the magnetic field caused the evolution of the two-phase microstructure from coupled growth to band. Moreover, it was also found that the magnetic field induced the crystal orientation of the primary phase. The above results may be attributed to the effect of the magnetic field on the mass and heat transfer during directional solidification. Copyright (C) EPLA, 2018
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  • The Mineral Chemistry of Chlorites and Its Relationship with Uranium Mineralization from Huangsha Uranium Mining Area in the Middle Nanling Range, SE China

    Wu, Dehai   Pan, Jiayong   Xia, Fei   Huang, Guangwen   Lai, Jing  

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  • Highly Regioselective Radical Transformation of N -Sulfonyl-1,2,3-triazoles in Air

    Li, Zi   Wei, Qinghua   Song, Longlong   Han, Wangyujing   Wu, Xiang   Zhao, Yun   Xia, Fei   Liu, Shunying  

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  • Modular Approach to Multi-resource Arbiter Design

    Yakovlev, Alex   Mokhov, Andrey   Xia, Fei   Shang, Delong   Golubcovs, Stanislavs  

    When circuits need to be constructed out of several self timed parts that access shared resources, asynchronous arbitration is often required. We consider the creation of the general purpose arbiter delegating M resources to N clients for the cases when the resources can be either active or passive participants of the arbitration. Firstly, the problem is solved for the case of two active resources being offered to two clients. Then a general problem solution is provided. Finally, on the basis of the 2x2 arbiter designed, it is shown how it can be used to create a scalable multi-resource arbiter for passive resources.
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  • Efficient Synthesis of 2,5-Dicyanofuran from Biomass-Derived 2,5-Diformylfuran via an Oximation-Dehydration Strategy

    Xu, Yongming   Jia, Xiuquan   Ma, Jiping   Gao, Jin   Xia, Fei   Li, Xiaofang   Xu, Jie  

    Aromatic dinitriles show promise as a pivotal building block in polymer and pharmaceutical chemistry, and their production from biomass-based alcohols or aldehydes is highly desirable. In this work, for the first time, 2,5-dicyanofuran was efficiently synthesized from biomass-derived 2,5-diformylfuran via a two-step procedure. 2,5-Diformylfuran was first converted to 2,5-diformylfuran dioxime with 90% isolated yield in water. Hydroxylamine instead of ammonia used as nitrogen source is the key to this strategy, which avoids the polymerization reaction of intermediate aldimine. The subsequent dehydration reaction of 2,5-diformylfuran dioxime afforded 2,5-dicyanofuran in 82% isolated yield over an effective and recyclable solid acid catalyst Amberlyst-15. This approach demonstrates the feasibility of synthesis of reactive dinitriles from dialdehydes without using toxic cyanides or halides.
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  • Thermal aging characteristics of CrNxOy solar selective absorber coating for flat plate solar thermal collector applications

    Wu, Liang   Gao, Junhua   Liu, Zhimin   Liang, Lingyan   Xia, Fei   Cao, Hongtao  

    A solar selective absorber coating of CrNxOy/SiO2 was prepared on Cu (Si) substrate using DC reactive magnetron sputtering technique. The coating exhibits a high absorptivity (a) of 0.947 and a low emissivity (e) of 0.05 at 80 C. The spectral selectivity (ale) of the coating on Cu substrate is stable (0.930/0.073) even after heat-treatment at 278 degrees C in air for 300 h, but decreased (0.904/0.135) at 278 degrees C for 600 h. The determinants to govern the thermal stability were investigated by micro-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) measurements, which reveal that the element diffusion whether throughout all the stacked layers or near the interface region, the chemical interactions adjacent to the interface, and the interface width broadening are the Achilles' heel for the solar thermal coatings to sustain high thermal stability. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.
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  • Advances in catalytic conversion of lignocellulose to chemicals and liquid fuels

    Ma, Jiping   Shi, Song   Jia, Xiuquan   Xia, Fei   Ma, Hong   Gao, Jin   Xu, Jie  

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  • Cloning, Expression, and Epitope Identification of Myosin Light Chain 1: An Allergen in Mud Crab

    Li, Meng-Si   Xia, Fei   Liu, Meng   He, Xin-Rong   Chen, Yi-Yu   Bai, Tian-Liang   Chen, Gui-Xia   Wang, Li   Cao, Min-Jie   Liu, Guang-Ming  

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  • Performance Comparison of Systematic Methods for Rigorous Definition of Coarse-Grained Sites of Large Biomolecules

    Zhang, Yuwei   Cao, Zexing   Zhang, John Zenghui   Xia, Fei  

    Construction of coarse-grained (CG) models for large biomolecules used for multiscale simulations demands a rigorous definition of CG sites for them. Several coarse-graining methods such as the simulated annealing and steepest descent (SASD) based on the essential dynamics coarse-graining (ED-CG) or the stepwise local iterative optimization (SLIO) based on the fluctuation maximization coarse-graining (FM-CG), were developed to do it. However, the practical applications of these methods such as SASD based on ED-CG are subject to limitations because they are too expensive. In this work, we extend the applicability of ED-CG by combining it with the SLIO algorithm. A comprehensive comparison of optimized results and accuracy of various algorithms based on ED-CG show that SLIO is the fastest as well as the most accurate algorithm among them. ED-CG combined with SLIO could give converged results as the number of CG sites increases, which demonstrates that it is another efficient method for coarse-graining large biomolecules. The construction of CG sites for Ras protein by using MD fluctuations demonstrates that the CG sites derived from FM-CG can reflect the fluctuation properties of secondary structures in Ras accurately.
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  • MR elastography for the assessment of hepatic fibrosis in patients with chronic hepatitis B infection: does histologic necroinflammation influence the measurement of hepatic stiffness?

    Shi, Yu   Guo, Qiyong   Xia, Fei   Dzyubak, Bogdan   Glaser, Kevin J   Li, Qiuju   Li, Jiahui   Ehman, Richard L  

    PURPOSE: To determine the diagnostic performance of magnetic resonance (MR) elastography for the staging of hepatic fibrosis and to evaluate the influence of necroinflammation on hepatic stiffness in patients with chronic hepatitis B virus (HBV) infection by using histopathologic findings as the reference standard.; MATERIALS AND METHODS: One hundred thirteen consecutive patients with chronic HBV infection were recruited prospectively in this institutional review board-approved study after providing written informed consent between March 2012 and October 2013. The stiffness measurements were obtained by using two-dimensional gradient-echo MR elastography with a 3.0-T MR system. The METAVIR scoring system was used for the assessment of fibrosis ("F" stage) and necroinflammation ("A" grade). The predictive ability of MR elastography was evaluated by using the receiver operating characteristic (ROC) curve and the area under the ROC curve (AUC). Multiple linear regression analyses were conducted to determine the relationship between hepatic stiffness and the variables that showed a significant association in the univariate analysis or those that were of interest for comparison with earlier work (histologic scores, sex, age, aspartate aminotransferase level, and aspartate aminotransferase/alanine aminotransferase ratio).; RESULTS: MR elastography showed excellent performance for characterization of =E2=89=A5 F1, =E2=89=A5 F2, =E2=89=A5 F3, and F4 findings, with AUC values of 0.961, 0.986, 1.000, and 0.998, respectively. It showed a moderate capability for evaluation of necroinflammatory activity of =E2=89=A5 A1, =E2=89=A5 A2, and A3 (AUC =3D 0.806, 0.834, and 0.906, respectively). Multiple linear regression analysis showed that fibrosis, necroinflammation, and sex were independently associated with hepatic stiffness (beta =3D 0.799, 0.277, and 0.070, respectively; P < .05). For pairwise comparisons, log-transformed hepatic stiffness showed no difference between (a) groups F0/A2-3 and F1/A0-1 and (b) groups F1/A2-3 and F2/A0-1 (P > .99 and P =3D .486, respectively).; CONCLUSION: MR elastography demonstrated excellent performance for distinguishing the stages of hepatic fibrosis in patients with chronic HBV infection. For hepatic tissue with =E2=89=A4 F2 fibrosis, necroinflammation can account for a substantial fraction of the increase in hepatic stiffness. =C2=A9 RSNA, 2014.
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  • A Novel Power Delivery Method for Asynchronous Loads in Energy Harvesting Systems

    Zhang, Xuefu   Shang, Delong   Xia, Fei   Yakovlev, Alex  

    For systems depending on power harvesting, a fundamental contradiction in the power delivery chain has existed between conventional synchronous computational loads requiring relatively stable Vdd and power harvesters unable to supply it. DC/DC conversion has therefore been an integral part of such systems to resolve this contradiction. On the other hand, asynchronous computational loads, in addition to their potential power-saving capabilities, can be made tolerant to a much wider range of Vdd variance. This may open up opportunities for much more energy efficient methods of power delivery. This article presents in-depth investigations into the behavior and performance of different on-chip power delivery methods driving both asynchronous and synchronous loads directly from a harvester source. A novel power delivery method, which employs a capacitor bank for adaptively storing the energy from power harvesters depending on load and source conditions, is developed. Its advantages, especially when driving asynchronous loads, are demonstrated through comprehensive comparative analysis.
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  • Preparation of hydroxypropyl methyl cellulose phthalate nanoparticles with mixed solvent using supercritical antisolvent process and its application in co-precipitation of insulin

    Jin, He Yang   Xia, Fei   Zhao, Ya Ping  

    To obtain hydroxypropyl methyl cellulose phthalate (HPMCP)/insulin nanospheres by supercritical anti-solvent process, the formation of HPMCP nanoparticles was first investigated. The effects of ratio of the mixed solvent, pressure, temperature, concentration, flow rate of CO2 and solution on forming HPMCP nanoparticles are discussed. It was found that different morphologies of HPMCP could be produced by varying the ratio of DMSO to acetone in the solvent. The operating parameters were optimized for making HPMCP nanoparticles. Formation of HPMCP/insulin nanospheres was further inspected. The nanospheres with the size ranging from 138 nm to 342 nm were obtained. The loading of insulin in the nanospheres ranged from 10.76% to 16.04% and the encapsulation efficiency reached 100%. The release of insulin is also discussed. (C) 2011 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.
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