检索结果-南通市图书馆

Equilibrium Crystallization Temperature of Syndiotactic Polystyrene γ Form

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2018年第6期36卷 749-755页

作者： Hai Wang Chun-Ji Wu Dong-Mei Cui yong-feng Men State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of Sciences

The crystallization behavior of syndiotactic polystyrene（s PS） γ form undergoing annealing at various temperatures was investigated using the thermodynamic phase diagram based on Strobl＇s crystallization theory. On the basis of the differential scanning calorimetric results, it was observed that γ form melt-recrystallization occurred at a higher temperature with the increasing lamellar thickness, which resulted from the pre-annealing at the elevating temperature after acetone induced crystallization. Further temperature dependent small-angle X-ray scattering（SAXS） measurement revealed the evolution of the γ form lamellae upon heating until phase transition, involving three different regimes： lamellae stable region（25-90 °C）, melt-recrystallization region（90-185 °C） and pre-phase transition region（185-195 °C）. As a result, recrystallization line, equilibrium recrystallization line and melting line were developed for the s PS γ form crystallization process. Since the melt of γ form involved a γ-to-α/β form phase transition, the melting line was also denoted as the phase transition line in this special case. Therefore, the equilibrium crystallization temperature and melting（phase transition） temperatures were determined at around 390 and 220 °C on the basis of the thermodynamic phase diagram of the s PS γ form.

关键词： Syndiotactic polystyrene γ form Crystallization behavior Equilibrium crystallization temperature Equilibrium melting temperature

Isolation and Partial Characterization of a Novel Pollen-specific cDNA with Multiple Polyadenylation Sites from Wheat

在线全文

学校读者我要写书评

暂无评论

Acta Biochimica et Biophysica Sinica 2004年第7期36卷 467-476页

作者： yong-feng JIN* and Teng-Fei BIANInstitute of Biochemistry, Zhejiang University, Hangzhou 310029, China Institute of Biochemistry Zhejiang UniversityHangzhou 310029 China

A novel pollen-specific full-length cDNA clone PSG076 was isolated using suppression subtractive hybridization and 5’/3’ RACE techniques. PSG076 was shown to exhibit multi-site polyadenylation by sequencing the 3’ ends of the cDNAs. At least six transcripts with different length were produced from the single gene based on different poly(A) tail attachment sites. However, polyadenylation consensus sequence AAUAAA was not seen at the 3’-untranslated sequence. PSG076 contained a 299 bp 5’ untranslated region and an open reading frame of 663 bp encoding a 221 amino acid peptide with pI of 4.31. A blast search revealed that this sequence did not show a significant similarity to any genes deposited in the public database. Southern blot indicated that PSG076 was a single copy gene. Northern blot and RT-PCR analysis indicated that PSG076 transcripts showed specific expression in mature pollen, and weak or undetectable signals in uninucleate microspore, immature seed, stem, young leave, root and ovary. Further analysis of the expression pattern in gametophyte showed that PSG076 transcripts were undetectable in uninucleate, binucleate microspore and pollen at early stage, and were first detectable and increased rapidly at middle and late stages of pollen development with the maximum level in mature pollen and also expressed in germinating pollen in vivo, suggesting that PSG076might play a role in pollen germination and pollen tube growthin addition to its function in maturation. The evidences gathered in this work indicated that the six different transcripts from the single gene were differentially expressed during pollen development.

关键词： wheat (Triticum aestivum L.) pollen-specific cDNA suppression subtractive hybridization multiple-site polyadenylation differential expression

Effect of basicity and Al2O3 on viscosity of ferronickel smelting slag

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2020年第12期27卷 1400-1406页

作者： yong-feng Chen Xue-ming Lv Zheng-de Pang Xue-wei Lv Wuhu Xinxing Ductile Iron Pipes Co. Ltd.Wuhu 241000AnhuiChina Pangang Group Research Institute Co. Ltd.Panzhihua 617000SichuanChina Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and New Materials Chongqing UniversityChongqing 400044China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China

The effect of the Al2O3 content and basicity (the molar ratio of MgO to SiO2) on the viscosity of a SiO2-MgO-FeOAl2O3-CaO slag was studied to fully understand the smelting process of the ferronickel alloy. Experimental results show that the slag is a mixture of liquid and solid phases at the experimental temperature. The viscosity decreased as the basicity increased and increased as the Al2O3 content increased. To determine the effect of the Al2O3 content and basicity on the structure of the molten slag, Raman spectroscopy was performed on the slag sample, which was quenched from the high temperature with water. The Raman spectra showed that the fractions of the polymerization structural units decreased significantly as the basicity of the slag increased, resulting in a decrease in the apparent viscosity. However, Al2O3 acts as a network former in the slag system, thereby making the slag structure further polymerized and increasing the viscosity.

关键词： Nickel laterite ore Slag structure Viscosity Basicity Ferronickel smelting slag

A New Type of Submerged-Arc Flux-Cored Wire Used for Hardfacing Continuous Casting Rolls

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

Journal of Iron and Steel Research International 2011年第11期18卷 74-79页

作者： YANG Ke ZHANG Zhi-xi HU Wang-qin BAO Ye-feng JIANG yong-feng College of Mechanical and Electrical Engineering Hohai University Changzhou 213022 Jiangsu China

It is expected that the welding hardfacing of continuous casting rolls has better welding performance and higher wear resistance. A new type of submerged-arc hardfacing flux-cored wire has been developed through nitrogen replacing part of carbon and addition of the nitrogen-fixing elements of niobium and titanium. And microstructure, degree of hardness and high-temperature wear resistance of its deposited metal samples were also investigated. It is found that the microstructure is martensite, residual austenite and carbonitride precipitates. As a result, the hardfacing metal with homogeneous distribution of very fine carbonitride particles had high hardness and excellent wear-re- sisting property during high-temperature wear, which could significantly extend the service life of continuous casting rolls.

关键词： submerged-arc flux-cored wire hardfacing high-temperature wear resistance continuous casting roll

Band offsets and electronic properties of the Ga_(2)O_(3)/FTO heterojunction via transfer of free-standing Ga_(2)O_(3) onto FTO/glass

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2021年第11期30卷 385-388页

作者： Xia Wang Wei-Fang Gu yong-feng Qiao Zhi-yong feng Yue-Hua An Shao-Hui Zhang Zeng Liu Department of Electrical Engineering and Automation Shanxi Institute of TechnologyYangquan 045000China School of Optoelectronic Engineering Guangdong Polytechnic Normal UniversityGuangzhou 510665China Shenzhen Engineering Laboratory of Phosphorene and Optoelectronics International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of EducationCollege of Optoelectronic EngineeringShenzhen UniversityShenzhen 518060China College of Electronic and Optical Engineering&College of Microelectronics Nanjing University of Posts and TelecommunicationsNanjing 210023China National and Local Joint Engineering Laboratory for RF Integration and Micro-Packing Technologies Nanjing University of Posts and TelecommunicationsNanjing 210023China

The determination of band offsets is crucial in the optimization of Ga_(2)O_(3)-based devices,since the band alignment types could determine the operations of devices due to the restriction of carrier transport across the heterogeneous *** this work,the band offsets of the Ga_(2)O_(3)/FTO heterojunction are studied using x-ray photoelectron spectroscopy(XPS)based on Kraut’s method,which suggests a staggered type-II alignment with a conduction band offset(DEC)of 1.66 eV and a valence band offset(DEV)of􀀀2.41 ***,the electronic properties of the Ga_(2)O_(3)/FTO heterostructure are also measured,both in the dark and under ultraviolet(UV)illuminated conditions(254 nm UV light).Overall,this work can provide meaningful guidance for the design and construction of oxide hetero-structured devices based on wide-bandgap semiconducting Ga_(2)O_(3).

关键词： Ga_(2)O_(3)/FTO heterojunction band alignment magnetron sputtering free-standing

Molecular Dynamics Simulation Studies on the Micromorphology and Proton Transport of Nafion/Ti_(3)C_(2)T_(x) Composite Membrane

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第3期42卷 373-387,I0009页

作者： Zhi-Yue Han Su-Peng Pei Chun-Yang Yu yong-feng Zhou School of Chemical and Environmental Engineering Shanghai Institute of TechnologyShanghai 201418China School of Chemistry&Chemical Engineering Frontiers Science Center for Transformative MoleculesShanghai Key Laboratory of Electrical Insulation and Thermal AgingShanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of Green and High-end Utilization of Salt Lake Resources Chinese Academy of SciencesXining 810008China

The perfluorosulfonic acid(PFSA) membrane doped with two-dimensional conductive filler Ti_(3)C_(2)T_(x) is a fuel cell proton exchange membrane with high application potential. Experimental studies showed that the proton conductivity of Nafion/Ti_(3)C_(2)T_(x) composite membrane is improved significantly compared with that in pure Nafion. However, the microscopic mechanism of doping on the enhancement of membrane performance is remain unclear now. In this work, molecular dynamics simulation was used to investigate the microscopic morphology and proton transport behaviors of Nafion/Ti_(3)C_(2)T_(x) composite membrane at the molecular level. The results shown that there were significant differences about the diffusion kinetics of water molecules and hydroxium ions in Nafion/Ti_(3)C_(2)T_(x) at low and high hydration levels in the nanoscale *** the increase of water content, Ti_(3)C_(2)T_(x) in membrane was gradually surrounded by ambient water molecules to form a hydration layer, and forming a relatively continuous proton transport channel between Nafion polymer and Ti_(3)C_(2)T_(x) monomer. The continuous proton transport channel could increase the number of binding sites of proton and thus achieving high proton conductivity and high mobility of water molecules at higher hydration level. The current work can provide a theoretical guidance for designing new type of Nafion composite membranes.

关键词： Nafion/Ti_(3)C_(2)T_(x)composite membrane Proton transport Molecular dynamics simulation

A GPU-Accelerated In-Memory Metadata Management Scheme forLarge-Scale Parallel File Systems

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2021年第1期36卷 44-55页

作者： Zhi-Guang Chen Yu-Bo Liu yong-feng Wang Yu-Tong Lu School of Computer Science and Engineering Sun Yat-sen UniversityGuangzhou 510006China

Driven by the increasing requirements of high-performance computing applications,supercomputers are prone to containing more and more computing *** running on such a large-scale computing system are likely to spawn millions of parallel processes,which usually generate a burst of I/O requests,introducing a great challenge into the metadata management of underlying parallel file *** traditional method used to overcome such a challenge is adopting multiple metadata servers in the scale-out manner,which will inevitably confront with serious network and consistence *** work instead pursues to enhance the metadata performance in the scale-up ***,we propose to improve the performance of each individual metadata server by employing GPU to handle metadata requests in *** proposal designs a novel metadata server architecture,which employs CPU to interact with file system clients,while offloading the computing tasks about metadata into *** take full advantages of the parallelism existing in GPU,we redesign the in-memory data structure for the name space of file *** new data structure can perfectly fit to the memory architecture of GPU,and thus helps to exploit the large number of parallel threads within GPU to serve the bursty metadata requests *** implement a prototype based on BeeGFS and conduct extensive experiments to evaluate our proposal,and the experimental results demonstrate that our GPU-based solution outperforms the CPU-based scheme by more than 50%under typical metadata *** superiority is strengthened further on high concurrent scenarios,e.g.,the high-performance computing systems supporting millions of parallel threads.

关键词： GPU-accelerated in-memory metadata management parallel file system

Comprehensive Evaluation of Tobacco Ecological Suitability of Henan Province Based on GIS

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

Agricultural Sciences in China 2010年第4期9卷 583-592页

作者： CHEN Hai-sheng LIU Guo-shun YANG yong-feng YE Xie-feng SHI Zhou National Tobacco Cultivation and Physiological and Biochemical Center Henan Agricultural University Zhengzhou 450002 P.R. China Zhejiang Tongji Science and Technology Vocational College Hangzhou 311231 P.R.China Institute of Agricultural Remote Sensing and Information Technology College of Environment and Resource Science Zhejiang University Hangzhou 310029 P.R.China

The growth of tobacco is sensitive to environment conditions. The tobacco production is strictly restricted by regional cultivated land. Based on the principal of hiberarchy analysis and fuzzy mathematics and the technique of geographic information system （GIS）, the comprehensive evaluation of tobacco ecology suitability were studied according to the actual circumstances of the whole Henan tobacco planting regions, China. The evaluation index system of tobacco ecology suitability of Henan tobacco planting regions was established by choosing 17 evaluation indexes from 3 respects of climate, soil and landform with Delphi method. Furthermore, the membership function was set up according to the effects of each ecology factors on the growth and quality of tobacco suitability. And the analytical hierarchy process （AHP） was used to determine the weight of indexes by using quantitative analysis. Then the tobacco ecology suitability map of Henan tobacco plantation was drawn with GIS software mapGIS. It is found that the most areas of the western and southern parts of Henan Province, China, are the highly suitable regions, accounting for 22.52% of Henan tobacco planting areas. It is because that there are medium air temperature, sunshine and rainfall, medium soil pH value, and high contents of soil organic matter in the regions. Moreover, the topography is hill and massif, and the height above sea level is between 150-800 m there. Some areas of the southern and middle parts of Henan Province are the suitable ones, accounting for 34.99% of Henan tobacco planting areas. It is because that there are enough rainfall, medium air temperature, high contents of available N and available K in the soil in these regions. There are less suitable regions in the northern and eastern parts of the investigated regions because of drought, too high pH value and CI in the soil and irrigation water, accounting for 35.54% of the whole areas. It can be conducted rapidly and correctly by combining

关键词： GIS flue-cured tobacco evaluation factors AHP ecology suitability

Giant Magnetic Tunneling Effect in 81NiFe/Al_(2)O_(3)/Fe Junction

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1997年第3期14卷 213-216页

作者： CHEN Hui-yu feng yong-jia SU Chang Department of Physics University of Science and Technology of ChinaHefei 230026

A new effect,spin-polarized magnetovoltage(MV)effect,is observed in an 81NiFe/Al_(2)O_(3)/Fe junctions with cross-strip-electrode *** one ferromagnetic electrode carries current,a voltage can be found between the ends of the other ferromagnetic electrode,and it varies with the magnetization process of the two ferromagnetic *** MV ratio,which is much larger than the magnetoresistance ratio for the same junction,has reached 53% at room temperature.

关键词： ferromagnetic electrode Tunnel