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N^2-(1-Methoxycarbonylethyl)guanosine,a new nucleoside coupled with an amino acid derivative from Amanita exitialis

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chinese Chemical Letters 2009年第7期20卷 830-832页

作者： yu Lang chi Hui Ye Zhang jing Hua Xue jing Hao Mei Fang Liu Xiao Yi Wei South china Botanical Garden Chinese Academy of Sciences Guangzhou 510650 China Graduate School of chinese Academy of Sciences Beijing 100049 China

A new purine nucleoside coupled with an amino acid derivative, N^2-（l-methoxycarbonylethyl）guanosine 1, along with β- carboline and russulaceramide was isolated from the fruiting bodies of Amanita exitialis, a newly described poisonous mushroom. Its structure was elucidated by spectroscopic methods. This is the first report of naturally occurring nucleosides in which an a-amino acid derivative is bonded through its a-amino nitrogen to a nucleobase aglycone by a C-N bond. The new compound was found to be toxic in brine shrimp lethality test （BST）. C 2009 Published by Elsevier B.V. on behalf of chinese Chemical Society.

关键词： N^2-(1-Methoxycarbonylethyl)guanosine Guanosine Purine alkaloid Nucleoside Amanita Amanita exitialis

Efficient photocatalytic reduction of chromium(Ⅵ) using photoreduced graphene oxide as photocatalyst under visible light irradiation

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Journal of Materials Science & Technology 2021年第32期91卷 17-27页

作者： Mei yu jing Shang yu Kuang Department of Environment and Health State Key Joint Laboratory of Environmental Simulation and Pollution ControlCollege of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China

Graphene oxide(GO),a new and promising material,has been widely used as a co-catalyst in photocatalytic reactions;however,its capacity as a sole photocatalyst has rarely been *** this study,ultraviolet(UV) light irradiation was used as a modification method to obtain reduced GO(rGO) *** samples were used as photocatalysts to examine their visible light photocatalytic activity toward hexavalent chromium(Cr(Ⅵ)) *** force microscopy(AFM),X-ray diffraction(XRD),UV-vis spectrophotometry,Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),and electron spin resonance(ESR) spectroscopy were applied to interpret the surface and structure changes with UV *** oxygen-containing functional groups(OFGs) on the GO surface were reduced to defective carbons andπ-conjugated C=C(sp^(2) domains) under UV light;this led to a decrease in the interlayer distance between GO sheets,GO fragmentation,and increased disorder on the GO *** restoration of sp^(2) domains led to a narrower band gap of GO,which favored the rGO excitation by visible light to generate electron-hole *** rGO pre-irradiated with UV for 1 h(rGO-1),possessing the highest defect density and electron generation efficiency,exhibited the best Cr(Ⅵ) reduction efficiency,which was about three times that of the GO sample;moreover,it outperformed most of the reported GO-based *** addition,low pH and the addition of citric acid as a hole scavenger could further improve the photocatalytic *** study proves that GO or rGO can be used as a sole photocatalyst under visible light to remove environmental pollutants such as heavy-metal ions,and it paves the way for the development of this kind of material and its UV-irradiation modification for further applications.

关键词： Graphene oxide Chromium(Ⅵ) Defect density UV-irradiation modification Photocatalytic reduction

Nanozyme-mediated elemental biogeochemical cycling and environmental effects

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Science china Earth Sciences 2021年第7期64卷 1015-1025页

作者： Zhi-Lai chi Guang-Hui yu Institute of Surface-Earth System Science School of Earth System ScienceTianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai RimBohai Coastal Critical Zone National Observation and Research StationTianjin UniversityTianjin 300072China College of Resources&Environmental Sciences Nanjing Agricultural UniversityNanjing 210095China

In Earth systems,thousands of terragrams(Tg)(1 Tg=10^(12) g)of mineral nanoparticles move around *** mineral nanoparticles have exhibited unexpected intrinsic enzyme-like characteristics(so called“mineral nanozymes”),and are ubiquitously distributed in natural ecosystems such as the atmosphere,oceans,waters,and *** with natural enzymes,these mineral nanozymes have several advantages such as tunable catalytic efficiency and robustness to harsh conditions,e.g.,heat,acid,and alkaline *** mineral nanozymes are new products of multidisciplinary cross-cutting,they have been widely applied in various *** review,for the first time,systematically introduces the species and properties of mineral nanozymes in Earth systems,discusses the critical roles played by nanozymes in environmental biogeochemical cycles,compiles the interfacial processes and mechanisms of mineral nanozymes,and provides an overview of the future prospects of mineral nanozymes.

关键词： Nanozymes Peroxidase Nanominerals Reactive oxygen species Biogeochemical cycles

Isolation and identification of a marine killer yeast strain YF07b and cloning of the gene encoding killer toxin from the yeast

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Acta Oceanologica Sinica 2007年第6期26卷 101-108页

作者： WANG Xianghong chi Zhenming LI jing UNESCO chinese Center of Marine Biotechnology Ocean University of China Qingdao 266003 China

It was found that the marine yeast strain YF07b could secrete a large amount of killer toxin against a pathogenic yeast strain WCY which could cause milky disease in Portunus trituberculcttus. The marine yeast strain YF07b was identified to be Pichia anomala according to the results of routine yeast identification and 18S rDNA and ITS sequences. The gene encoding killer toxin in the marine yeast strain YF07b was amplified by PCR technology. After sequencing, the results show that an open reading frame, consisting of 1 281 bp, encoded a presumed protein of 427 amino acids. The sequence of the cloned gene was found to have 99% match with that of the gene encoding killer toxin in Pichia anomalas strain K. A signal peptide including 17 amino acids appeared in the N-terminal domain of the killer toxin. Therefore, the mature protein consisted of 410 amino acids, its molecular mass was estimated to be 47.4 ku and its isoelctronic point was 4.5.

关键词： pathogenic yeast crab marine killer yeast identification killer toxin gene cloning

Resonant Heating of Ions by Parallel Propagating Alfvén Waves in Solar Coronal Holes

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chinese Journal of Astronomy and Astrophysics 2005年第3期5卷 285-294页

作者： Tian-XiZhang jing-XiuWang chi-JieXiao NationalAstronomicalObservatories ChineseAcademyofSciencesBeijing100012／／CenterforSpacePlasmaandAeronomicResearchTheUniversityofAlabamainHuntsvilleHuntsvilleAL35899USA NationalAstronomicalObservatories ChineseAcademyofSciencesBeijing100012

Resonant heating of H, O+5, and Mg+9 by parallel propagating ion cyclotron Alfven waves in solar coronal holes at a heliocentric distance is studied using the heating rate derived from the quasilinear theory. It is shown that the particle-AlfVen-wave interaction is a significant microscopic process. The temperatures of the ions are rapidly increased up to the observed order in only microseconds, which implies that simply inserting the quasilinear heating rate into the fluid/MHD energy equation to calculate the radial dependence of ion temperatures may cause errors as the time scales do not match. Different species ions are heated by Alfven waves with a power law spectrum in approximately a mass order. To heat O+5 over Mg+9 as measured by the Ultraviolet Coronagraph Spectrometer (UVCS) in the solar coronal hole at a region ≥ 1.9.R, the energy density of Alfven waves with a frequency close to the O+5-cyclotron frequency must be at least double of that at the Mg+9-cyclotron frequency. With an appropriate wave-energy spectrum, the heating of H, O+5 and Mg+9 can be consistent with the UVCS measurements in solar coronal holes at a heliocentric distance.

关键词： acceleration of particles - plasmas - waves - solar wind - Sun: corona

Network Coding-based Reliable Broadcast Transmission in Wireless Networks

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china Communications 2010年第2期7卷 71-77页

作者： Wang jing chi Kaikai Wang Xinmei School of Information Engineering Chang an University Xi an 710064 China College of Computer Science and Technology Zhejiang University of Technology Hangzhou 310023 China State Key Lab. of Integrated Service Networks Xidian University Xi an 710071 China

Recently, network coding has been applied to the loss recovery of reliable broadcast transmission in wireless networks. Since it was proved that fi nding the optimal set of lost packets for XOR-ing is a complex NP-complete problem, the available time-based retransmission scheme and its enhanced retransmission scheme have exponential computational complexity and thus are not scalable to large networks. In this paper, we present an efficient heuristic scheme based on hypergraph coloring and also its enhanced heuristic scheme to improve the transmission efficiency. Basically, our proposed schemes fi rst create a hypergraph according to the packet-loss matrix. Then our schemes solve the problem of generating XORed packets by coloring the edges of hypergraph. Extensive simulation results demonstrate that, the heuristic scheme based on hypergraph coloring and its enhanced scheme can achieve almost the same transmission efficiency as the available ones, but have much lower computational complexity, which is very important for the wireless devices without high computation capacity.

关键词： network coding reliable broadcast wireless networks transmission bandwidth computational complexity

siRNA-mediated DNA methylation and H3K9 dimethylation in plants

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Protein & Cell 2013年第9期4卷 656-663页

作者： chi Xu jing Tian Beixin Mo College of Life Science Shenzhen Key Laboratory of Microbial Genetic EngineeringShenzhen UniversityShenzhen 518060China College of Life Science Shenzhen Key Laboratory of Marine Biological Resources and Ecological EnvironmentShenzhen UniversityShenzhen 518060China

Heterochromatic siRNAs regulate transcriptional gene silencing by inducing DNA methylation and histone H3K9 *** advances have revealed the distinct phases involved in siRNA mediated silencing pathway,although the precise functions of a number of factors remain undesignated,putative mechanisms for the con-nection between DNA and histone methylation have been investigated,and much effort has been invested to understand the biological functions of siRNA-mediated epigenetic modifi *** this review,we summarize the mechanism of siRNA-mediated epigenetic modification,which involves the production of siRNA and the recruit-ments of DNA and histone methytransferases to the target sequences assisted by complementary pairing between 24-nt siRNAs and nascent scaffold RNAs,the roles of siRNA-mediated epigenetic modifi cation in maintaining genome stability and regulating gene expression have been dis-cussed,newly identified players of the siRNA mediated silencing pathway have also been introduced.

关键词： epigenetic DNA methylation histone meth-ylation heterochromatic siRNA argonaute

MULTI-SCALES RELAXATION PROCESSES OF SHORT FIBER OF NEMATIC LIQUID CRYSTALLINE COPOLYMER IN POLYCARBONATE MATRIX

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chinese Journal of Polymer Science 2008年第1期26卷 99-104页

作者： yu, Ruo-bing yu, Wei Zhou, chi-xing E china Univ Sci & Technol Sch Mat Sci & Engn Shanghai 200237 Peoples R China Shanghai Jiao Tong Univ Dept Polymer Sci & Engn Shanghai 200240 Peoples R China

Multi-scales relaxation processes of short fiber of a nematic liquid crystalline copolymer(LCP)in polycarbonate matrix were ***,the structure relaxation of LCP was studied by *** relaxation spectrum of the nematic liquid crystalline copolymer at 295℃was calculated from the combined dynamic *** are three kinds of relaxation mechanisms for nematic liquid crystalline copotymer:the relaxation of chain orientation,the relaxation of deformed polydomains and the coalescence of pol...

关键词： Liquid crystalline copolymer Multi-scales Relaxation processes

Complex field network-coded cooperation based on multi-user detection in wireless networks

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Journal of Systems Engineering and Electronics 2013年第2期24卷 215-221页

作者： jing Wang Xiangyang Liu Kaikai chi Xiangmo Zhao School of Information Engineering Chang'an University State Key Laboratory of Integrated Service Networks Xidian University Department of Network Management Xi'an Communication College College of Computer Science and Technology Zhejiang University of Technology

Cooperative communication can achieve spatial diversity gains,and consequently combats signal fading due to multipath propagation in wireless networks powerfully.A novel complex field network-coded cooperation（CFNCC） scheme based on multi-user detection for the multiple unicast transmission is *** analysis and simulation results demonstrate that,compared with the conventional cooperation（CC） scheme and network-coded cooperation（NCC） scheme,CFNCC would obtain higher network throughput and consumes less time ***,a further investigation is made for the symbol error probability（SEP） performance of CFNCC scheme,and SEPs of CFNCC scheme are compared with those of NCC scheme in various scenarios for different signal to noise ratio（SNR） values.

关键词： network coding complex field wireless network cooperative communication multi-user detection