检索结果-南通市图书馆

Electron Beam-Physical Vapor Deposited TiAl-based Laminated Composite Sheet with Nb Layer Toughening

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2006年第B12期19卷 5-8页

作者： ZHANG De-ming chen Gui-qing HAN Jie-cai MENG Song-he Center for Composite Materials Harbin Institute of Technology Harbin 150080 China

The TiAl-based laminated composite sheet of 150 mm × 100 mm × 0.2 mm, with 24 TiAl layers and 23 Nb layers laid alternately one on another, was successfully fabricated using the electron beam-physical vapor deposition （EB-PVD） method. The microstructure and properties of the sheet were investigated on an atomic force microscope （AFM）, a scanning electron microscope （SEM） and a tensile testing machine. The results indicate that the evenly distributed Nb layers are well joined with the TiAl layers, and the interfaces between layers are transparent, and every interlayer spacing is of about 8μm. The fractures appear to be a mixture of intergranular fractures and somewhat ductile quasi-cleavage ones. Despite its slight influence on ultimate tensile strength, the inserts of Nb layers efficiently increase the room temperature ductility of TiAl-based alloys due to the crack deflection effect.

关键词： EB-PVD TiAl-based alloys sheet TiAl/Nb laminated composites microstructure and properties

Preparation and Characterization of Polymeric Microspheres Having Isotactic Poly(methacrylic acid) on Their Surfaces

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2002年第1期18卷 61-64页

作者： chen ming-qing LIU Xiao-ya YANG cheng AKASHI Mitsuru School of Chemical and Material Engineering Southern Yangtze UniversityWuxi 214036P.R.China Department of Applied Chemistry and Chemical Engineering Faculty of EngineeringKagoshima UniversityKagoshima 890-0065Japan

A poly（ tert -butyl methacrylate）（PBMA） macromonomer was synthesized by anionic polymerization with bis（2,6-di- t -butyl phenoxy） methyl aluminum [MeAl（ODBP）2] as the initiator and trimethylsilylmethacrylate（TMSMA） as the end capping agent in dry THF. Then, a poly（methacrylic acid）（PMAA） macromonomer was obtained by means of hydrolysis reaction from the PBMA macromonomer in the presence of hydrochloric acid. The structures of the PBMA macromonomer were characterized by using 1H NMR. It was found that the resulted PBMA macromonomer has highly isotactic properties and the PMAA macromonomer has an end vinyl group on per polymer chain. The monodisperse polymeric microspheres, which consisted of polystyrene cores and PMAA branches on their surfaces, were prepared by the dispersion copolymerization of styrene with the PMAA macromonomer in an ethanol/water mixed solvent. It was found that the concentration of the PMAA macromonomer would affect the microsphere formation, the morphology and its size in the copolymerization system.

关键词： Macromonomer Isotactic structure Dispersion copolymerization Microsphere

EPDM增韧PP/HDPE共混物的组织及增韧机制

在线全文

学校读者我要写书评

暂无评论

塑料科技 2024年第5期52卷 23-27页

作者：付明宇姜凤阳俞慧冀迪惠海峰陈明情弓合兴王俊勃西安工程大学材料工程学院陕西西安710048 福建冠泓工业有限公司福建石狮362700

为提高聚丙烯(PP)增韧效率并研究其增韧机制,以PP/高密度聚乙烯(HDPE)共混物为基体,三元乙丙橡胶(EPDM)为增韧改性剂,通过熔融共混法制备PP/HDPE/EPDM共混物。结果表明:EPDM与HDPE形成核壳结构分散在基体中,并增强了与基体之间相互作用... 详细信息

为提高聚丙烯(PP)增韧效率并研究其增韧机制,以PP/高密度聚乙烯(HDPE)共混物为基体,三元乙丙橡胶(EPDM)为增韧改性剂,通过熔融共混法制备PP/HDPE/EPDM共混物。结果表明:EPDM与HDPE形成核壳结构分散在基体中,并增强了与基体之间相互作用力。EPDM对PP的结晶具有促进作用,但对HDPE的结晶起到抑制作用,进而细化核壳结构分散相。随着EPDM含量的增加(4%~12%),PP/HDPE/EPDM共混物抗冲击强度增强,EPDM能够在增韧PP的同时延缓PP拉伸强度的快速下降。当EPDM含量为16%时,共混物的抗冲击强度达到11.18 kJ/m2,较PP/HDPE的抗冲击强度分别提高了158%。PP/HDPE/EPDM共混物的增韧机制为EPDM壳和HDPE核结构的空穴化作用,从而提升其能量的吸收。

关键词：聚丙烯高密度聚乙烯三元乙丙橡胶抗冲击强度增韧机制

Thermosensitive Particles with Unusual Morphology Prepared by Dispersion Copolymerization

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2005年第6期21卷 740-742页

作者： chen ming-qing YUAN Yan-hua LIU Xiao-ya YANG cheng KANEKO Tatsuo AKASHI Mitsuru School of Chemical and Material Engineering Southern Yangtze University Wuxi 214036P. R. China Department of Molecular Chemistry Graduate School of EngineeringOsaka University 2-1 Yamadaoka Suita 565-0871 Japan

The monodispersed polymeric particles with an unusual structure were prepared by the dispersion copolymerization of acrylonitrile/styrene（AN/St） in mixed solvents of ethanol/water by using the poly（N-isopropylacrylamide）（PNIPAAm） macromonomer as a reaction stabilizer. It was found that the AN monomer plays a key role in the formation of the particles with special morphology analyzed via scanning electron microscopy （SEM）. The reaction parameters have remarkable influences on the particle size and morphology. The particles possess a thermosensitive property according to the result of laser light scattering（LLS）.

关键词： PNIPAAm macromonomer Acrylonitrile/styrene Dispersion copolymerization Morphology

Unsuccessful treatment of four patients with acute graft-vs-host disease after liver transplantation

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2012年第1期18卷 84-89页

作者： Xiao-Bo chen Jie Yang ming-qing Xu Tian-Fu Wen Lu-Nan Yan Department of Liver and Vascular Surgery WestChina Hospital Sichuan University Chengdu 610041 SichuanProvince China

AIM: To investigate appropriate therapeutic strategies for graft-vs-host disease (GVHD) following liver transplantation. METHODS: Four patients who developed GVHD after liver transplantation in West China Hospital were included in this study. Therapeutic strategies with augmentation or withdrawal of immunosuppressants combined with supportive therapy were investigated in these patients. In addition, a literature review of patients who developed GVHD after liver transplantation was performed. RESULTS: Although a transient response to initial treatment was detected, all four patients died of complications from GVHD: one from sepsis with multiple organ failure, one from gastrointestinal bleeding, and the other two from sepsis with gastrointestinal bleeding. Few consensuses for the treatment of GVHD after liver transplantation have been ***: New and effective treatments are re-quired for GVHD after liver transplantation to improve the prognosis of patients with this diagnosis.

关键词： Graft-vs-host disease Immunosuppressant Immunosuppression Liver transplantation Treatment

Synthesis and Drug Release Properties of Thermosensitive Poly(N-vinylacetamide-co-vinylacetate) Hydrogels

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2011年第2期27卷 334-338页

作者： YANG Li-he CHU Hong chen ming-qing HU Na ZHAO Yi-fan School of Chemical and Material Engineering Jiangnan University Wuxi 214122 P. R. China

Thermosensitive poly[N-vinylacetamide-co-vinylacetate][P（NVA-co-VAc）] hydrogels were prepared via free radical copolymerization from hydrophilic NVA and hydrophobic VAc in the presence of butylenes-bis （N-vinylacetamide）（Bis-NVA） as crosslinker. Scanning electron microscopy（SEM） images reveal that the as-prepared hydrogels were of three-dimensional network with irregular cave structure. The prepared hydrogels with more NVA in the feed swelled faster and the swelling ratio of the hydrogels gradually decreased with temperature increasing from 10 °C to 60 °C. The dynamic swelling studies indicate that the swelling process of the hydrogels was controlled by diffusion of water molecules considered as Fickian-controlled case. The adsorption amount of model drug, sodium salicylate（SS） was higher in the hydrogels containing more NVA units, whose corresponding release could reach equilibrium in about 6 h.

关键词： Poly(N-vinylacetamide-co-vinylacetate) Therrnosensitive hydrogel Drug release

Thermal stability of permafrost under U-shaped crushed rock embankment of the qinghai-Tibet Railway

在线全文

学校读者我要写书评

暂无评论

Advances in Climate Change Research 2024年第1期15卷 158-169页

作者： Kun-ming XU Guan-Li JIANG Ji chen qing-Bai WU State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China Beiluhe Observation Station of Frozen Soil Environment and Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou730000China

The U-shaped crushed rock embankment(UCRE),of which widely utilized in the permafrost regions along the qinghai-Tibet Railway,has the capability to rapidly reduce the ground temperature of the underlying ***,there remains uncertainty regarding the adaptation of UCRE to climate change and its long-term cooling *** study focuses on nine UCRE monitoring sites along the qinghai-Tibet Railway to analyze the dynamic variations of the ground temperature underlying permafrost from 2006 to *** efficiency of UCRE in stabilizing permafrost temperature in different permafrost zones is evaluated by considering the permafrost table,ground temperature,and MAGT,as well as the temperature difference between the top and bottom of the crushed rock layer and the ground temperature variation index(GTVI).The results show that UCRE is suitable for application in extremely unstable warm permafrost regions where the MAGT is higher than-0.5℃.Moreover,UCRE effectively diminishes the disparity in permafrost thermal stability between the sunny and shaded shoulders of the *** short-term and long-term effect of cooling permafrost is experiencing a change related with permafrost ***,in stable cold permafrost regions with MAGT lower than-1.5℃,the long-term cooling effect of UCRE on permafrost seems to gradually di-minishes,but UCRE continues to fulfill the role of stabilizing the underlying permafrost thermal state over the *** results show that UCRE can quickly restore and stabilize the thermal state of permafrost in the early stages of construction,and adapt to the influence of future climate *** findings provide important guidance for understanding the variations of permafrost thermal stability beneath the embankment in permafrost regions,as well as for improving the embankment stability and operational safety of the qinghai-Tibet Railway.

关键词： qinghai-Tibet Railway U-shaped crushed rock embankment Climate change Permafrost zone Ground temperature variation index Long-term coolingrole

Possibility of reaching the predicted center of the“island of stability”via the radioactive beam-induced fusion reactions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第9期35卷 186-195页

作者： ming-Hao Zhang Ying Zou Mei-chen Wang Gen Zhang qing-Lin Niu Feng-Shou Zhang The Key Laboratory of Beam Technology of Ministry of Education School of Physics and AstronomyBeijing Normal UniversityBeijing 100875China Institute of Radiation Technology Beijing Academy of Science and TechnologyBeijing 100875China School of Physical Science and Technology Guangxi UniversityNanning 530004China Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator of LanzhouLanzhou 730000China

Based on the dinuclear system model,the synthesis of the predicted double-magic nuclei^(298)Fl and 304120 was investigated via neutron-rich radioactive beam-induced fusion *** reaction^(58)Ca+^(244)Pu is predicted to be favorable for producing^(298)Fl with a maximal ER cross section of 0.301 *** of the entrance channel effect reveal that the^(244)Pu target is more promising for synthesizing^(298)Fl than the neutron-rich targets^(248)Cm and^(249)Bk,because of the influence of the Coulomb *** the synthesis of 304120,the maximal ER cross section of 0.046 fb emerges in the reaction^(58)V+^(249)Bk,indicating the need for further advancements in both experimental facilities and reaction mechanisms.

关键词： Superheavy nuclei Dinuclear system model Fusion reaction Double-magic nucleus Radioactive beam

On the half-quantized Hall conductance of massive surface electrons in magnetic topological insulator films

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(Physics,Mechanics & Astronomy) 2024年第6期67卷 127-136页

作者： Rui chen Shun-qing Shen Department of Physics The University of Hong KongHong Kong 999077China Department of Physics Hubei UniversityWuhan 430062China

In topological insulators,massive surface states resulting from local symmetry breaking were thought to exhibit a half-quantized Hall conductance,obtained from the low-energy effective model in an infinite Brillouin *** a lattice model,the surface band is composed of a combination of surface states and bulk *** massive surface states alone may not be enough to support an exact one-half quantized surface Hall conductance in a finite Brillouin zone and the whole surface band always gives an integer quantized Hall conductance as enforced by the TKNN *** explore this,we investigate the band structures of a lattice model describing the magnetic topological insulator film that supports the axion insulator,Chern insulator,and semi-magnetic topological insulator *** reveal that the gapped and gapless surface bands in the three phases are characterized by an integer-quantized Hall conductance and a half-quantized Hall conductance,*** propose an effective model to describe the three phases and show that the low-energy dispersion of the surface bands inherits from the surface Dirac *** gapped surface band manifests a nearly half-quantized Hall conductance at low energy near the center of Brillouin zone,but is compensated by another nearly half-quantized Hall conductance at high energy near the boundary of Brillouin zone because a single band can only have an integer-quantized Hall *** gapless band hosts a zero Hall conductance at low energy but is compensated by another half-quantized Hall conductance at high energy,and thus the half-quantized Hall conductance can only originate from the gapless ***,we calculate the layer-resolved Hall conductance of the *** conclusion suggests that the individual gapped surface band alone does not support the half-quantized surface Hall effect in a lattice model.

关键词： magnetic topological insulator Dirac equation half-quantized Hall conductance