检索结果-南通市图书馆

Temperature-Dependent Photoluminescence of Silicon Nanoporous Pillar Array

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2014年第4期31卷 170-173页

作者： li yong wang Xiao-Bo FAN zhi-Qiang li Xin-jian Department of Physics and Laboratory of Material Physics Zhengzhou University Zhengzhou 450052 Department of Pt2ysies and Solar Energy Research Center Pingdingshan University Pingdingshau 467000 Department of Physics Anyang Normal University Anyang 455000

Silicon nanoporous pillar array （Si-NPA） is a micron-nanometer hierarchical structure which might be used as functional substrates for constructing optoelectronic nanodevices. This makes understanding the photolumines- cence （PL） from Si-NPA important. We measure the PL of Si-NPA in the range of 11-300K. By analyzing the evolution of the peak energy and intensity with temperature, the ultraviolet, blue, orange and red PL bands from Si-NPA are attributed to the radiative recombination through the deep-levels in silicon oxide, oxygen-related defect states in silicon nanocrystallites （nc-Si）, band-to-band transition within nc-Si, and surface/interface states of nc-Si or between nc-Si and SiOx, respectively. At least two non-radiative recombination processes, which are activated at different temperature ranges, are proposed for the PL intensity variation with temperature. These results might provide strong foundations for designing and constructing optoelectronic devices based on silicon nanostruetures.

关键词： PHOTOLUMINESCENCE NANOPOROUS materials NANOSIliCON OPTOELECTRONIC devices FIELD emission cathodes

Glass-forming ability and corrosion performance of Mn-doped Mg-Zn-Ca amorphous alloys for biomedical applications

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2018年第7期37卷 579-586页

作者： jian-li wang Yin Wan zhi-Jun Ma yong-Chun Guo Zhong Yang Ping wang jian-Ping li School of Materials and Chemical Engineering Xi'an Technological University

In the present work, ribbon and 2-mm rod samples of Mg-Zn-Ca-Mn alloys were prepared by meltspinning and copper mold injection methods, respectively. Effects of Mn doping on glass-forming ability and corrosion performance in simulated body fluid of Mg65Zn30Ca5 alloy were studied through X-ray diffraction, scanning electron microscopy, differential scanning calorimeter, and electrochemical and immersion tests. Results show that with the Mn addition increasing, all the ribbon samples are completely in amorphous state. However, the microstructure of 2-mm rod samples transfers from fully amorphous for the Mn-free alloy to almost polycrystalline state with precipitated Mg, Mn, and MgZn phases. Glass-forming ability of Mg65Zn30Ca5 alloy is decreased by Mn addition. Results of electrochemical and immersion tests demon- strate that the Mn-doped samples exhibit more negative corrosion potential and larger corrosion current density, suggesting that the corrosion resistance decreases with doping amount of Mn element increasing.

关键词： Mg-Zn-Ca amorphous alloys Mn doping Glass-forming ability Corrosion performance

Seismic responses of the steel-strip reinforced soil retaining wall with full-height rigid facing from shaking table test

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2018年第5期15卷 1137-1152页

作者： CAO li-cong FU Xiao wang zhi-jia zhou yong-yi liU Fei-cheng ZHANG jian-jing Key Laboratory of Transportation Tunnel Engineering Ministry of Education School of Civil Engineering Southwest Jiaotong University Department of Geotechnical Engineering School of Civil Engineering Southwest Jiaotong University Department of Civil Engineering and Architecture Hainan University

To investigate the seismic response of the steel-strip reinforced soil retaining wall with fullheight rigid facing in terms of the acceleration in the backfill, dynamic earth pressure in the backfill, the displacements on the facing and the dynamic reinforcement strain distribution under different peak acceleration, a large 1-g shaking table test was performed on a reduced-scale reinforced-earth retaining wall model. It was observed that the acceleration response in non-strip region is greater than that in potential fracture region which is similar with the stability region under small earthquake,while the acceleration response in potential fracture region is greater than that in stability region in middle-upper of the wall under moderately strong earthquakes. The potential failure model of the rigid wall is rotating around the wall toe. It also was discovered that the Fourier spectra produced by the inputting white noises after seismic wave presents double peaks, rather than original single peak, and the frequency of the second peak trends to increase with increasing the PGA(peak ground amplitude) of the excitation which is greater than 0.4 g. Additionally,the non-liner distribution of strip strain along the strips was observed, and the distribution trend was not constant in different row. Soil pressure peak value in stability region is larger than that in potential fracture region. The wall was effective under 0.1 g-0.3 g seismic wave according to the analyses of the facing displacement and relative density. Also, it was discovered that the potential failure surface is corresponds to that in design code, but the area is larger. The results from the study can provide guidance for a more rational design of reinforced earth retaining walls with full-height rigid facing in the earthquake zone.

关键词： Reinforced soil retaining walls Potentialfailure surface Full-height rigid facing Steel strip Seismic behaviors 1-g shaking table test

Cangumycins A-F, six new angucyclinone analogues with immunosuppressive activity from Streptomyces

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Natural Medicines 2019年第12期17卷 982-987页

作者： wang Lei wang li zhou zhi wang yong-jiang HUANG jian-Ping MA Ya-Tuan liU Yang HUANG Sheng-Xiong State Key Laboratory of Phytochemistry and Plant Resources in West China and CAS Center for Excellence in Molecular Plant SciencesKunming Institute of BotanyChinese Academy of SciencesKunming 650201China College of Chemistry and Pharmacy Northwest Agriculture and Forestry UniversityYangling 712100China Research Center Chengdu Medical CollegeChengdu 610500China Savaid Medical School University of Chinese Academy of SciencesBeijing 100049China

Cangumycins A-F(1–6), six new angucyclinone analogues, together with two known ones(7 and 8), were isolated from the fermentation broth of a soil-derived Streptomyces sp. KIB-M10. Structures of these compounds were elucidated via a joint use of spectroscopic analyses and single-crystal X-ray diffractions. Among them, cangumycins E(5) and F(6) share a C-ring cleaved backbone, and cangumycins B(2) and E(5) exhibit potent immunosuppressive activity(IC50 8.1 and 2.7 μmol·L^-1, respectively) against human T cell proliferation at a non-cytotoxic concentration.

关键词： Streptomyces Angucyclinones Benz[a]anthracenes Natural products Immunosuppressive activity

Hydrogen embrittlement of a microalloyed bainitic forging steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2019年第9期26卷 1011-1021页

作者： Wei-jun Hui Zhan-hua wang zhi-bao Xu yong-jian Zhang Xiao-li Zhao Materials Science and Engineering Research Center School of MechanicalElectronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Yantai Branch of China North Industries Group Corporation No. 52 Institute Co. Ltd.Yantai 264003ShandongChina

The hydrogen embrittlement (HE) of a novel microalloyed bainitic forging steel with a strength level of 1100 MPa was evaluated using electrochemical charging and slow strain rate tensile test method with notched round bar specimens. The results show that the susceptibility to HE of the as-forged bainitic forging steel is notably higher than that of the quenched and tempered (Q&T) steel at same strength level, which is ascribed primarily to the presence of a relatively high amount of large blocky martensite/austenite (M/A) constituents of the former. It was found that low-temperature tempering treatment at 200 C could significantly alleviate the susceptibility to HE by a relative decrease of * 35% of the as-forged bainitic forging steel at no expense of strength and ductility, though its resistance to HE is still a little lower than that of the Q&T steel. Thus, it is suggested that efforts concerning refining of the large blocky M/A through optimizing chemical composition and processing route could help to further alleviate the susceptibility to HE of the tested bainitic forging steel.

关键词： Hydrogen embrittlement Bainitic forging steel Microstructure Granular bainite M/A constituent

Co-evolution of paleo-environment and bio-precursors in a Permian alkaline lake,Mahu mega-oil province,Junggar Basin:Implications for oil sources

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2022年第3期65卷 462-476页

作者： liuwen XIA jian CAO lizeng BIAN Wenxuan HU Tingting wang Dongming zhi yong TANG Erting li Department of Earth Sciences Nanjing UniversityNanjing 210023China PetroChina Xinjiang Oilfield Company Karamay 834000China

The co-evolution of paleo-environment and bio-precursors in alkaline lakes is of significance to understand the extreme environment system and associated enigmatic hydrocarbon *** we used organic petrology and biomarker geochemistry to investigate the bio-precursors in a Permian alkaline paleo-lake in the Mahu mega-oil province within about a hundred miles of the Mahu Sag,Junggar Basin,China,and its effect on oil generation and *** general,the bioprecursors in the alkaline lacustrine source rocks of the Fengcheng Formation were mainly bacteria and algae,with a low abundance of higher ***,these source rocks were mainly prone to oil *** distinctive hydrocarbongenerating bio-precursors—Dunaliella-like algae and cyanobacteria—were *** addition to fossil evidence for these bio-precursors,the former results in a high C_(28)/C_(29)sterane ratio andβ-carotane abundance,and the latter results in the formation of medium-chain monomethyl alkanes in terms of *** nature of the bio-precursors varied with the sedimentary paleo-environment,and was controlled by the salinity and stratification of the ***-type source rocks were deposited in the central area of the alkaline lake,and cyanobacteria-type source rocks were formed around the lake *** crude oils in different parts of the Mahu mega-oil province within about a hundred miles have different *** bio-precursors in the saline lacustrine source rocks were jointly controlled by the age and water salinity of the source *** physiological synthesis of carotenoids and sterols by haloalkaliphilic green algae may have affected the evolution of ancient green algae.

关键词： Green algae Dunaliella Cyanobacteria Bio-precursors Saline lacustrine basin Terrestrial petroleum Mahu Sag

Preliminary Studies on Species and Distribution of Citrus Viroids in China

在线全文

学校读者我要写书评

暂无评论

Agricultural Sciences in China 2008年第9期7卷 1097-1103页

作者： wang Xue-feng zhou Chang-yong TANG Ke-zhi LAN jian-qiang zhou Yan li Zhong-an Citrus Research Institute Chinese Academy of Agricultural Sciences Chongqing 400712 P.R.China Key Laboratory of Agricultural Biodiversity for Plant Disease Management Ministry of Education Yunnan Agricultural University Kunming 650201 P.R.China

Citrus viroids are the small but economically important RNA pathogens. For investigating their occurrence and distribution in China, 65 viroid samples collected from 8 major citrus cultivated regions were evaluated using one-step or multiplex onestep RT-PCR and biological indexing for specifically detection of Citrus exocortis viroid （CEVd）, Citrus bent leaf viroid （CBLVd）, Hop stunt viroid （HSVd）, Citrus viroid-Ⅲ （CVd-Ⅲ） and Citrus viroid-Ⅳ （CVd-Ⅳ）. The results showed that there were at least 4 kinds of citrus viroids （CEVd, CBLVd, HSVd, and CVd-Ⅲ） on citrus trees in China. Most of the infected citrus plants harbored more than one viroid species, and two plants were infected with up to 4 citrus viroids. Sweet orange was more frequently infected by viroids than other citrus varieties. It is the preliminary report on the species and distribution of citrus viroids in China.

关键词： citrus viroids exocortis cachexia multiplex one-step RT-PCR

OSL chronology of a Palaeolithic site in a humid subtropical mountainous area of southeast China

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2021年第8期18卷 2012-2023页

作者： JIN jian-hui wang Xiao-yang zhou Zhen-yu HUANG Yun-ming FAN Xue-chun ZUO Xin-xin liNG zhi-yong REN yong-qing li Shu-tong School of Geographical Sciences Fujian Normal UniversityFuzhou350007China Center for Southeast environmental archaeology Fujian Normal UniversityFuzhou350007China Fujian Institute of Archaeology Fuzhou350001China The institute of Archaeology Chinese Academy of Social SciencesBeijing100710China School of Humanities Minjiang UniversityMinhou350108China Pingtan International Institute of Austronesian Archaeology Pingtan350400China Qinghai Institute of Salt Lakes Chinese Academy of SciencesXi’ning810008China

The timing of Palaeolithic human activities in South China is still controversial because of the lack of a reliable chronology of archaeological *** Longdengshan Palaeolithic site(LPS),located close to the Wuyi Mountain of South China,represents the first discovered and scientifically excavated Middle Palaeolithic site in the Fujian *** site is of considerable significance for studying the diffusion and cultural connotation of early Homo sapiens in southern *** this study,we present optically stimulated luminescence(OSL)ages obtained from medium-grained quartz collected at the *** single-aliquot regenerative-dose measurements of red soil deposits collected at the same site yielded internally and stratigraphically consistent ages and similar errors,indicating a potential ability of the technique,and also reflecting the influence of various sedimentary facies on the test *** results indicate that the 38–63µm quartz grains were generally partially-bleached and had large values of over-dispersion in the palaeo-reticulated laterites of west *** samples yielded unsatisfactory results,suggesting that the degree of bleaching of diluvial and alluvial deposits should be properly assessed before *** did not detect any enrichment/depletion of U,Th and radioactive *** effect of chemical weathering on the dose rate estimation was ***,we used a central age model and the maximum age model to calculate the age of two samples,respectively,and the minimum age model to calculate the ages of the rest of the *** OSL ages of the samples ranged from 27.09±2.30 ka to 54.65±7.39 ka for the 38–63µm quartz size fraction,and roughly corresponded to the Marine Isotope Stage *** addition,three ages out of five are based on the calculation of minimum ages in this research,which needs to be further verified by other dating methods.

关键词： OSL dating Palaeolithic site chronology Southeast China

Picotesla-sensitivity microcavity optomechanical magnetometry

在线全文

学校读者我要写书评

暂无评论

light(Science & Applications) 2024年第11期13卷 2835-2846页

作者： zhi-Gang Hu Yi-Meng Gao jian-Fei liu Hao Yang Min wang Yuechen Lei Xin zhou Jincheng li Xuening Cao Jinjing liang Chao-Qun Hu zhilin li yong-Chang Lau jian-wang Cai Bei-Bei li Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China School of Physics Beihang UniversityBeijing 100191China Songshan Lake Materials Laboratory Dongguan 523808 GuangdongChina

Cavity optomechanical systems have enabled precision sensing of magnetic fields,by leveraging the optical resonance-enhanced readout and mechanical resonance-enhanced *** studies have successfully achieved mass-produced and reproducible microcavity optomechanical magnetometry(MCOM)by incorporating Terfenol-D thin films into high-quality(Q)factor whispering gallery mode(WGM)***,the sensitivity was limited to 585 pT Hz^(−1/2),over 20 times inferior to those using Terfenol-D *** this work,we propose and demonstrate a high-sensitivity and mass-produced MCOM approach by sputtering a FeGaB thin film onto a high-Q SiO2 WGM *** studies are conducted to explore the magnetic actuation constant and noise-limited sensitivity by varying the parameters of the FeGaB film and SiO2 *** magnetometers with different radii are fabricated and *** utilizing a microdisk with a radius of 355μm and a thickness of 1μm,along with a FeGaB film with a radius of 330μm and a thickness of 1.3μm,we have achieved a remarkable peak sensitivity of 1.68 pT Hz^(−1/2)at 9.52 *** represents a significant improvement of over two orders of magnitude compared with previous studies employing sputtered Terfenol-D ***,the magnetometer operates without a bias magnetic field,thanks to the remarkable soft magnetic properties of the FeGaB ***,as a proof of concept,we have demonstrated the real-time measurement of a pulsed magnetic field simulating the corona current in a high-voltage transmission line using our developed *** high-sensitivity magnetometers hold great potential for various applications,such as magnetic induction tomography and corona current monitoring.

关键词： particles. magnetometer film