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Formation and tribology properties of polyfluoroal-kylmethacrylate film on the magnetic head surface

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Science Bulletin 2005年第20期 131-136页

作者： HU Xiaoli, ZHANG Chenhui, LUO Jianbin & WEN Shizhu State key laboratory of Tribology, tsinghua university, beijing100084, {5.

A polyfluoroalkylmethacrylate (PFAM) film has been coated on the surface of the magnetic head by a dipping coating method to modify the surface properties. The films were characterized by means of a time-of-flight secon- dary ion mass spectrometer (TOF-SIMS), contact angle measurement and atomic force microscopy (AFM). The re- sults indicate that the concentration of the solution is the main factor affecting the thickness, contact angle and surface topography of the film. The magnetic head with the PFAM film at a concentration of 5.0 ppm exhibits the best tribology properties, and the stiction between the magnetic head and the disk is no more than 2.4 g after 20000 contact start stop (CSS) cycles. Therefore, a fully covered PFAM film with few defects helps improve the tribology properties of the mag- netic head, and decrease the adsorbed contaminant on the magnetic head surface.

关键词： diamond like carbon (DLC) polyfluoroalkylmethacrylate (PFAM) film morphology tribology properties.

Analysis of genome-wide gene expression in root of wheat hybrid and its parents using Barleyl GeneChip

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Progress in Natural Science:Materials International 2006年第7期16卷 712-720页

作者： ZHANG Yinhong, NI Zhongfu, YAO Yingyin, ZHAO Jun and SUN Qixin (Department of Plant Genetics & Breeding and State key laboratory for Agrobiotechnology, key laboratory of Crop Genomics and Genetic Improvement, Ministry of Agriculture / beijing key laboratory of Crop Genetic Improvement, china Agricultural university, beijing 100094, china) china Agr Univ Dept Genet & Plant Breeding Beijing 100094 Peoples R China china Agr Univ Minist AgrBeijing Key Lab Crop Genet Improvement State Key Lab Agrobiotechnol Key Lab Crop Genom & Genet Improvement Beijing 100094 Peoples R China

Previous studies indicated that differential gene expression between hybrids and their parents is responsible for the hct-crosis. In this paper, we report genome-wide gene expression analysis in roots of a highly heterotic inter-specific hybrid 3338/2463 and its parental inbreds using Barley GeneChip. A total of 1187 genes displayed difference in gene expressions between hybrid 3338/2463 and its parents, and they can be clustered into eight differential expression patterns. Further analysis revealed that among these 1187 genes, 975.genes showed high sequence similarity to the GenBank entries, and represented diverse functional categories, such as metabolism, cell growth and maintenance, signal transduction, response to stress, transcription regulation and others. Fourteen genes were selected for RT-PCR analysis and expression patterns of 9 (64. 29% ) genes were confirmed. Remarkably, 380 differentially expressed genes could be mapped on the Chinese Spring deletion bins, and with the number of genes in seven homoeologous groups being 15., 148, 121, 140, 132, 94 and 127 respectively. It is concluded that a combination of systematic identification of differentially expressed genes with comparative mapping would provide further insight into understanding of molecular basis of heterosis.

关键词： GeneChip gene expression heterosis hybrid wheat.

Some interesting CH_2CH_3 spin systems in several diethyl malonate indene derivatives studied with NMR and molecular modeling

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Science china Chemistry 2009年第7期52卷 937-942页

作者： ZHANG Long1, HE WeiWei1, LIANG YongMin2 & CUI YuXin1 1 State key laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking university, beijing 100191, china 2 State key laboratory of Applied Organic Chemistry, Lanzhou university, Lanzhou 730000, china State key laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Beijing China State key laboratory of Applied Organic Chemistry Lanzhou University Lanzhou China

While studying the electrophilic cyclization of acetylenic malonates in synthesizing malonate indene derivatives with high regio and stereo-selectivity, we found that the CH2 and CH3 protons of two COOCH2CH3 groups in some diethyl malonate indene derivatives showed very interesting spin-spin coupling and signal multiplicity. To explain those phenomena, we synthesized several diethyl malonate indene derivatives, and then used 1H NMR spectra and molecular modeling to investigate the CH2CH3 spin system of these two COOCH2CH3 groups in detail. The results showed that the spin systems of CH3CH2 of the two COOCH2CH3 groups in those compounds may exist in different froms (AMX3, ABX3 and A2X3), and the effect of the aromatic ring induced by the phenyl group at the end of the triple bond is the main reason responsible for those phenomena.

关键词： electrophilic cyclization spin-spin coupling signal multiplicity molecular modeling spin system aromatic ring

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EFFECT OF molecular WEIGHT OF PEO ON THE STRUCTURE AND PROPERTIES OF PDMAEMA/PEO HYDROGELS

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Chinese Journal of Polymer Science 2006年第1期24卷 35-40页

作者： Zhu-gen Liu Min Yi Mao-lin Zhai and Hong-fei Ha Department of Applied Chemistry and The key laboratory of Polymer Chemistry and Physics of Ministry of Education,College of Chemistry & molecular Engineering,Peking university,beijing 100871,{5. Department of Applied Chemistry and The key laboratory of Polymer Chemistry and Physics of Ministry of Education College of Chemistry & Molecular Engineering Peking University Beijing 100871

A new kind of binary hydrogels composed of poly（dimethylaminoethylmethacrylate）（PDMAEMA） and poly（ethylene oxide）（PEO） with varying weight average molecular weights （M^-w = 5.× 10^4, 1 × 10^5.and 2.5.× 10^6） were prepared by У-irradiation technology. The properties of PDMAEMA/PEO hydrogels obtained were evaluated in terms of gel fraction, gel strength, thermal characterization and swelling behavior. The gel strength and swelling degree of the hydrogels could be improved obviously after adding PEO into the PDMAEMA system, while the degree of improvement decreased with increasing M^-w of PEO. The temperature sensitivity of PDMAEMA/PEO was retained only in the sample with PEO of M^-w = 5.× 10^4, and the pH sensitivity was retained in samples with PEO of M^-w = 5.× 10^4 and 1 × 10^5. When DMAEMA/PEO mixtures containing PEO of M^-w = 5.× 10^4 were irradiated, the main reaction could be the cross-linking of DMAEMA, and the linear PEO molecular chains could penetrate into the cross-linked network of PDMAEMA. With increasing M^-w of PEO, some side reactions were induced, such as grafting of DMAEMA onto PEO molecules, the scission or cross-linking of PEO.

关键词： Poly(dimethylaminoethylmethacrylate) Poly(ethylene oxide) molecular weight Binary hydrogels Irradiation.

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Electronic structure and magnetism of R(Fe,Si)_(12) (R=Y,Nd)

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Science china(Physics,Mechanics & Astronomy) 2006年第2期49卷 195-202页

作者： SUN Guang’ai1, CHEN Bo1, DU Honglin2, FAN Zhijian1, GAO Tao3 & QI Xinhua31. Institute of Nuclear Physics and Chemistry, china Academy of Engineering Physics, Mianyang 621900, china 2. Department of physics, Peking university, beijing 100871, china 3. Institute of {5. and molecular Physics, Sichuan university, Chengdu 610065. china Institute of Nuclear Physics and Chemistry China Academy of Engineering Physics Mianyang China Department of physics Peking university Beijing China Institute of atomic and molecular Physics Sichuan University Chengdu China

The newly developed full-potential linearized augmented plane wave (LAPW) and local orbitals (lo) based on standard APW methods are briefly introduced, and the structure and magnetic properties of R(Fe, Si)12 compounds (R = Y, Nd) are calculated using the method. The distribution of Si at different sites is analyzed based on total energy of one crystal unit with structure having been optimized. The characters of magnetic mo-ments, total density of states (TDOS) and partial density of states (PDOS) for different crystal sites Si occupies are obtained and analyzed. The results show that the total mag-netic moments of RFe10Si2 (R = Y, Nd) are larger than those of RFe10M2 (M = Ti, V, Cr, Mn, Mo and W) and the hybridization mechanism is seen as follows. Si(8j) reduce the mag-netic moments of Fe at three sites, however, Si(8f) mainly reduce the magnetic moments of Fe(8i) and Fe(8j) atoms. The Curie temperature is markedly enhanced by the introduc-tion of Si atoms according to spin fluctuation of DOS at Fermi level.

关键词： (L)APW+lo method R(Fe Si)12(R = Y Nd) magnetic moment Density of state.

atomic stick-slip friction between commensurate self-assembled monolayers

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Progress in Natural Science:Materials International 2002年第7期 23-27页

作者： ZHANG Tao, ZHANG Jing, WANG Hui and HU Yuanzhong(The State key laboratory of Tribology, tsinghua university, beijing 100084, china) The State key laboratory of Tribology Tsinghua University Beijing 100084 China

The classical molecular dynamics simulations have been used to examine the compression and friction between commensurate selt-assembled monolayers (SAMs) on Au (111) . The friction force changes in a period corresponding to the geometric structure of sliding surfaces. The simulations reveal an ordered atomic stick-slip motion and discontinuous movements of diverse monomers, mainly head and tail groups. All of the head groups of the static film have 2 - 3 metastable positions (MPs). They oscillate around one of the MPs in stick phases and jump simultaneously to a new MP in slip phases. The tail groups of the sliding film are pulled forward together with opposite ones while sticking and jump forward half of the lattice constant relative to opposite ones while slipping. A complete vision of the motion of SAM chains is thereby built up and compared with the molecule behavior predicted by the Tomlinson model.

关键词： molecular dynamics simulation self-assembled monolayers sliding friction stick-slip.

Genetic polymorphisms of milk epithelial mucin of yaks

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Progress in Natural Science:Materials International 2006年第11期16卷 1222-1226页

作者： ZHENG Yucai~1, ZHAO Xingbo~2**, JIN Suyu~1, PENG Xianwen~1 and BAI Wenlin~1 (1. College of Life Science and Technology, Southwest university for Nationalities, Chengdu 610041, china 2. State key laboratory for Agrobiotechnology and Ministry of Agriculture key laboratory of Animal Genetics, Breeding and Reproduction, china Agricultural university, beijing 100094, china) College of Life Science and Technology Southwest University for Nationalities Chengdu 610041 China State key laboratory for Agrobiotechnology and Ministry of Agriculture key laboratory of Animal Genetics Breeding and Reproduction China Agricultural University Beijing 100094 China

Milk epithelial mucin (MUC1) of yaks was separated by SDS-polyacrylamide gel electrophoresis. A total of nine types of MUC1 were revealed in 427 yaks from five yak breeds including Maiwa yak, Jiulong yak, Tianzhu white yak, Qinghai yak and Tibetan yak. The molecular weights of MUC1 are from 163 kD to 208 kD, most of which are larger than those of bovine. Population genetic analysis shows that the gene frequency and genotype frequency of yak MUC1 differ among breeds, with relatively high gene heterozygosity. The five yak breeds studied fall into two groups according to their milk MUC1 gene frequency, suggesting that milk MUC1 exhibits specificities for local yak groups.

关键词： yak milk genetic polymorphism MUC1.

Direct Detection of Explosives on Solid Surfaces by Mass Spectrometry with Ambient Ion Source Based on Dielectric Barrier Discharge

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Direct Detection of Explosives on Solid Surfaces by Mass Spe...

Effects of chlorogenic acid, an active compound activating calcineurin, purified from Flos Lonicerae on macrophage

第三十五届国际光谱会议

作者： N.Na~1 S.C.Zhang~(1*) C.D.Yang~1 X.R.Zhang~(1*) Department of Chemistry key laboratory for atomic and molecular nanosciences of the Education Ministry {5. university beijing 100084 china

＜正＞Sensitive and specific detection of explosives is an important analytical issue,there is a high demand for developing highly sensitive methods for the real-time detection of explosives and explosive-related compounds with a low false alarm rate[1].Recently,a family of new ion source has been proposed allowing ions to be created under ambient conditions and then collected and analyzed by MS,which are intended to be used for

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Acta Pharmacologica Sinica 2004年第12期25卷 119-123页

作者： He-zhen WU, Jing LUO, Yan-xia YIN, Qun WEI2 Department of Biochemistry and molecular Biology, beijing Normal university, beijing 100875. china Department of Biochemistry and molecular Biology Beijing Normal University

AIM: To investigate the activation of chlorogenic acid (CHA) purified from Flos Lonicerae to calcineurin and its effects on macrophage functions in vivo and in vitro. METHODS: According to the screening results that Flos Lonicerae could activate calcineurin, the active component which could activate calcineurin was purified from Flos Lonicerae by column chromatography on silica gel and identified as CHA. The activation of CHA on calcineurin had been validated with both p-NPP and P-labeled RII peptide as the substrates. The clearance of charcoal particles in 32 normal mice and the cytotoxicity of U937 to MCF-7 were used together to determine the effects of CHA on macrophage functions. RESULTS: CHA could activate calcineurin, and the concentration of CHA on maximal activating calcineurin was 282.5.μmol/L. CHA administration (10 mg/kg, ig×7 d) significantly enhanced the mac- rophage functions in normal mice. CHA (70.6, 141.2, and 282.5.μmol/L) obviously increased the cytotoxicity of U937 to MCF-7. CONCLUSION: CHA could activate calcineurin and enhance the macrophage functions in vivo and in vitro, and its functions in vivo may be realized via the signal pathways of calcineurin.

关键词： calcineurin macrophage chlorogenic acid Flos Lonicerae