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Removal Behaviors of Different SiC Ceramics during Polishing

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Journal of Materials Science & technology 2010年第2期26卷 125-130页

作者： Guiling Liu, Zhengren Huang , Xuejian Liu and Dongliang Jiang Structural Ceramics center, shanghai Institute of Ceramics, Chinese Academy of Sciences, shanghai 200050, china [a] Structural Ceramics center shanghai Institute of Ceramics Chinese Academy of Sciences shanghai 200050 china

Comparative experiments were conducted to reveal the removal behaviors of three kinds of silicon carbide （SIC） ceramics during polishing and the effects of ceramic microstructure on the surface quality were also reported. Experimental results show that the second phase in SiC ceramics plays an important role in the surface quality when its size is large enough. The surface quality is enslaved to the formation of steps at interfaces between second phase and SiC matrix that results from different elastic modulus and hardness between two phases. Under 3 μm abrasive grains polishing condition, different SiC ceramics show different removal mechanisms. With decreasing abrasive grain size, all of different SiC ceramics exhibit a ductile removal mode, which decreases surface roughness efficiently.

关键词： SiC Surface quality Removal behavior Polishing

A LINEAR DYNAMIC MODEL DESCRIBING LYMPH CIRCULATION

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Journal of Hydrodynamics 2009年第1期21卷 118-123页

作者： YAO Wei WANG Sheng-zhang DING Guang-hong SHEN Xue-yong Department of Mechanics and Engineering Science Fudan University Shanghai 200433 China shanghai Research center of Acupuncture and Meridian Shanghai 201203 China Acupuncture Department of shanghai University of Traditional Chinese Medicine Shanghai 200032 China

The lymph circulation plays an important role in interstitial fluid balance, protein transport, and immune system. However, its mechanism is poorly understood, and associated pathologies are mostly untreatable. By following Sungawa＇s method of discussing the heart output, a hemodynamic model of lymph circulation was set up. The model was used to demonstrate how the lymphatic fluid formation, investigate the relationship between the lymph flow rate QL and physiological parameters, and explore how local massage influences QL Computer simulation results show that QL is linearly proportional to the interstitial fluid pressure P~, which is similar to experimental observations. Comparing the simulated value of QL during the massage of different frequency with the experimental data from Ikomi shows that they are identical, which indicates that the presented model is rational to explain the mechanism of massage treatment in traditional Chinese medicine （TCM）.

关键词： lymph circulation pressure-volume circle equivalent elastance massage treatment in TCM

Organic Solvents Mediate Self-assembly of GAV-9 Peptide on Mica Surface

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Acta Biochimica et Biophysica Sinica 2007年第4期39卷 285-289页

作者： Hai LI~(1,3) Feng ZHANG~1 Yi ZHANG~1* Jianhua HE~1 Jun HU~(1,2) 1 shanghai Institute of Applied Physics,Chinese Academy of Sciences,shanghai 201800,china 2 Bio-X Life Sciences Research center.College of Life Science and Biotechnology,shanghai Jiaotong University,shanghai 200030,china 3 Graduate School of the Chinese Academy of Sciences,Beijing 100049,china shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800 China Graduate School of the Chinese Academy of SciencesBeijing 100049 China Bio-X Life Sciences Research center College of Life Science and Biotechnology Shanghai Jiaotong UniversityShanghai 200030 China

Self-assembly of peptides into fibrils and other morphologies has attracted much attention inmany fields,especially in nanofabrication,pathology and *** this paper,self-assembly of GAV-9peptide in organic solvents,ethanol and acetone,was investigated using atomic force microscopy(AFM)and attenuated total reflectance-Fourier transform infrared spectroscopy(ATR-FTIR).The results indicatedthat GAV-9 self-assembled into various nanostructures in both solvents after deposited and evaporated *** with β-sheet conformation were observed in both solvents when the peptide concentrationwas higher than 280 μ***,ordered fibrils with β-sheet conformation were formed in ethanol,butnot in acetone,with a peptide concentration ranging from 7 μM to 28 μ*** attribute the formation ofvarious nanostructures to the different physicochemical properties of the polar organic solvents on the self-assembly of GAV-9 peptide.

关键词： self-assembly GAV-9 peptide organic solvents ATR-FTIR AFM

formation and migration of space charge packet in low density polyethylene

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Science china(Technological Sciences) 2005年第3期48卷 354-360页

作者： ZHENG Feihu 1 , ZHANG Yewen 1 , GONG Bin 1 , ZHU Jianwei 1 & WU Changshun 2 1. Pohl Institute of Solid State Physics, Tongji University, shanghai 200092, china 2. china National center for Quality Supervision and Test of Electric Ware and Cable, shanghai 200093, china 1. Pohl Institute of Solid State Physics Tongji University 200092 Shanghai China 2. china National center for Quality Supervision and Test of Electric Ware and Cable 200093 Shanghai China

Pressure wave propagation (PWP) method was utilized to observe the space charges packet-like behavior in sheet samples of low-density polyethylene (LDPE) under the relative low electric field. The experimental results show that space charge packets are always generated at the anode and move across the sample to the cathode regardless of the polarity of DC voltage. This paper discusses the migration of space charge packets at 30–40°C, the possible charge resource of space charge packets carriers and trap level of the space charge.

关键词： solid dielectric,low-density polyethylene,space charge packet,trap.

Strain Softening and Hardening Behavior in AZ61 Magnesium Alloy

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Journal of Materials Science & technology 2004年第6期20卷 691-693页

作者： Haitao ZHOU, Liufa LIU, Qudong WANG, Da LU, Xiaoqin ZENG and Wenjiang DINGNational Engineering Research center of Light Alloys Net Forming, School of Materials Science and Engineering, shanghai Jiao Tong University, shanghai 200030, china Ctr. of Light Alloys Net Forming Sch. of Mat. Sci. and Eng. Shanghai Jiaotong Univ. Shanghai 200030 China

The deformation behavior of AZ61 Mg alloy during hot deformation has been investigated in wide temperature and strain rate range by a Gleeble simulator. Specimens are deformed in compression in the temperature range of 523-673 K and at strain rates of 0.001-1 s-1. It is found that the flow curves exhibit a peak and then decrease towards steady-state of classical DRX, which decrease with rising temperature and decreasing strain rate. The deformation behavior of the specimens can be attributed to the occurrence of strain hardening and softening. As stress decreases, the strain hardening rate declines at a fast rate when temperature rises or strain rate decreases. The shapes of θ-σ curves indicate some important features such as subgrain formation, the criticai stress, the peak stress and steady stress. The onset of DRX can be determined by the point of inflection on θ-σ or Inθ-σ curves.

关键词： AZ61 Mg alloy Recrystallization Strain hardening and softening

Differential expression analysis and regulatory network reconstruction for genes associated with muscle growth and adipose deposition in obese and lean pigs

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Progress in Natural Science:Materials International 2008年第4期18卷 387-399页

作者： Mingzhou Li a, Xuewei Li a, Li Zhu a, Xiaokun Tengb, Huasheng Xiao b, Surong Shuaia, Lei Chen a, Qiang Li a, Yujiao Guo a a Laboratory of Pork Quality, College of Animal Science and technology, Sichuan Agricultural University, Ya’an 625014, china b National Engineering center for Biochip at shanghai, shanghai 201203, china Laboratory of Pork Quality College of Animal Science and Technology Sichuan Agricultural University Ya’an 625014 China National Engineering center for Biochip at shanghai Shanghai 201203 China

During the growth and development of skeletal muscle cells and adipose cells, the regulatory mechanism of micro-effect polygenes determines porcine meat quality, carcass characteristics and other relative quantitative traits. Obese and lean type pig breeds show obvi- ous differences in muscle growth and adipose deposition; however, the molecular mechanism underlying this phenotypic variation remains unknown. We used pathway-focused oligo microarray studies to examine the expression changes of 140 genes associated with muscle growth and adipose deposition in longissimus dorsi muscle at six growth stages (birth, 1, 2, 3, 4 and 5 months) of Landrace (a leaner, Western breed) and Taihu pigs (a fatty, indigenous, Chinese breed). Variance analysis (ANOVA) revealed that differences in the expression of 18 genes in Landrace pigs and three genes in Taihu pigs were very significant (FDR-adjusted permutation, P formation and fatty acid biogenesis and genes that strongly down-regulated were mainly associated with the inhibition of cell proliferation and positive regulation of fatty acid b-oxidation. Based on a dynamic Bayesian network (DBN) model, gene regulatory networks (GRNs) were reconstructed from time-series data for each pig breed. These two GRNs initially revealed the distinct differences in physiological and biochemical aspects of muscle growth and adipose deposition between the two pig breeds; from these results, some potential key genes could be identified. Quantitative real-time RT-PCR (QRT-PCR) was used to verify the microarray data for five modulated genes, and a good correlation betwee

关键词： Pig Muscle growth Adipose deposition Pathway-focused microarray Differential gene expression Gene regulatory network (GRN)

Sequence analysis of mRNA polyadenylation signals of rice genes

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Chinese Science Bulletin 2006年第9期51卷 1069-1077页

作者： LU Ying1, 2, GAO Chenxi1,2,3 & HAN Bin1,3,41. National center for Gene Research, shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, shanghai 200233, china 2. Graduate School of the Chinese Academy of Sciences, Beijing 100039, china 3. Institute of Plant Physiology and Ecology, shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, shanghai 200032, china National center for Gene Research Shanghai Institutes for Biological Sciences Chinese Academy of Sciences Shanghai 200233 China Graduate School of the Chinese Academy of Sciences Beijing 100039 China Institute of Plant Physiology and Ecology Shanghai Institutes for Biological Sciences Chinese Academy of Sciences Shanghai 200032 China

The formation of eukaryotic mRNAs involves the cleavage and polyadenylation of pre- mRNAs. To investigate the sequence requirement of putative polyadenylation signals (PASs), poly(A) sites and downstream elements (DUEs) in 3′-end-pro- cessing in rice, we compared expressed sequences tags (ESTs) with poly(A) extremity to full-length cDNA sequences and constructed a database of 12969 pre- mRNA sequences in ?40―+40 nt surrounding the poly(A) sites, which were from 9953 genes. The al- ternative poly(A) sites were revealed in approxi- mately 25% of mRNAs. Nearly 80% of pre-mRNAs showed stringent requirement of the YA (CA or UA) at poly (A) sites for polyadenylation. About 7.9% had the AAUAAA signals on ?40―?1 nt upstream of the poly(A) sites. Over 60% of mRNAs probably used the one- or two-base variants of AAUAAA hexamers as their PASs in 3′ fragments. The single-base variants of AAUGAA revealed the high frequency in 11.5% of 3′ fragments. The DUEs were detected in 90% of pre- mRNAs, especially more than half of the pre-mRNAs with multi-base variants of AAUAAA had the DUEs surrounding the poly(A) site. The location of DUE is also important for defining the cleavage site. Al- though most of the rice pre-mRNAs did not contain AAUAAA signal, the existence of downstream ele- ments ensured the efficiency of cleavage-polyade-

关键词：多聚腺苷酸序列分析 mRNA 水稻基因工程

The precipitation strengthening behavior of Cu-rich phase in Nb contained advanced Fe-Cr-Ni type austenitic heat resistant steel for USC power plant application

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Progress in Natural Science:Materials International 2012年第3期22卷 175-185页

作者： Cheng-yu Chi a, Hong-yao Yu b, Jian-xin Dong b, Wen-qing Liu c, Shi-chang Cheng d, Zheng-dong Liu d, Xi-shan Xie b a School of Metallurgical and Ecological Engineering, University of Science & technology Beijing, Beijing 100083, china b School of Materials Science and Engineering, University of Science & technology Beijing, Beijing 100083, china c Instrumental Analysis & Research center, shanghai University, shanghai 200444, china d Central Iron and Steel Research Institute, Beijing 100081, china [a] School of Metallurgical and Ecological Engineering University of Science & Technology Beijing Beijing 100083 China [b] School of Materials Science and Engineering University of Science & Technology Beijing Beijing 100083 China [c] Instrumental Analysis & Research center Shanghai University Shanghai 200444 China [d] Central Iron and Steel Research Institute Beijing 100081 China

Copper has been used as a strengthening element in newly developed Fe-Cr-Ni type austenitic heat resistant steel for inducing Cu-rich phase precipitation to meet high temperature strength requirement for 600 ℃ Ultra Super-Critical (USC) coal fired power plants for many years. However, the precipitation behavior and strengthening mechanism of Cu-rich phase in these advanced austenitic heat resistant steels is still unclear. In order to understand the precipitation strengthening behavior of Cu-rich phase and to promote high strength austenitic heat resistant steel development, 18 Cr9 NiCuNb steel which is a Cu-added Nb contained advanced Fe-Cr-Ni type austenitic heat resistant steel has been selected for this study to be aged at 650 ℃ till to 10,000 h. Micro-hardness and room temperature tensile test were conducted after long-time aging. SEM, TEM, HRTEM and three dimensional atom probe (3DAP) technology accompanying with thermodynamic calculation have been used to investigate the Cu-rich phase precipitation behavior during 650 ℃ aging. The experimental results showed that Cu atoms can quickly concentrate in clusters at very early precipitation stage to form the fine nano-size Cu-rich "segregation areas" within less than 1 h at 650 ℃. With increasing aging time at 650 ℃ Cu atoms continuously concentrate to Cu-rich segregation areas (clusters) and simultaneously other kinds of atoms such as Fe, Cr and Ni diffuse away from Cu-rich segregation areas to austenitic matrix, and finally to complete the transformation from Cu-rich segregation areas to Cu-rich phase. However, there is only Cu atoms concentration but not crystallographic transformation from early stage of Cu-rich clusters forming to the final Cu-rich phase formation. Even the Cu atom becomes the main composed element after 500 h aging at 650 ℃ the Cu-rich phase still keeps coherent relationship with austenitic matrix. According the experimental results in this study, Cu-rich phase precipitation sequence which st

关键词： USC power plant Austenitic heat resistant steel Microstructure Cu-rich phase TEM 3DAP

Highly active Au/CeO2 nanocubes for the low temperature oxidation of carbon monoxide

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Highly active Au/CeO2 nanocubes for the low temperature oxid...