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Parameter estimation for whole-body kinetic model of FDG metabolism

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Progress in Natural science:Materials International 2006年第11期16卷 1164-1170页

作者： CUI Yunfeng~1, BAI Jing~1**, CHEN Yingmao~2.and TIAN Jiahe~2.1. Department of Biomedical engineering, Tsinghua University, {3. 100084,{2. 2. Department of Nuclear Medicine, General Hospital of PLA, {3. 100853.{2.) [a]Department of Biomedical engineering Tsinghua University Beijing China [b]Department of Nuclear Medicine General Hospital of PLA Beijing China

Based on the radioactive tracer [ ~ 18 F]2.fluoro-2.deoxy-D-glucose （FDG）, positron emission tomography （PET）, and compartment model, the tracer kinetic study has become an important method to investigate the glucose metabolic kinetics in human body. In this work, the kinetic parameters of three-compartment and four-parameter model for the FDG metabolism in the tissues of myocardium, lung, liver, stomach, spleen, pancreas, and marrow were estimated through some dynamic FDG-PET experiments. Together with published brain and skeletal muscle parameters, a relatively complete whole-body model was presented. In the liver model, the dual blood supply from the hepatic artery and the portal vein to the liver was considered for parameter estimation, and the more accurate results were obtained using the dual-input rather than the single arterial-input. The established whole-body model provides the functional information of FDG metabolism in human body. It can be used to further investigate the glucose metabolism, and also be used for the simulation and visualization of FDG metabolic process in human body.

关键词： compartment model FDG PET parameter estimation.

Simulation of Thermodynamics and Kinetics for KR Desulphurization

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Journal of Iron and Steel Research International 2011年第S2期18卷 98-106页

作者： XU An-jun1, ZHANG Mao-lin2. ZHANG Hui-ning1, LI An-dong3.(1. School of Metallurgical and Ecological engineering, University of science and Technology {2., {2. 100083.china 2. Steel-Making and Continuous Casting engineering Institute, Capital engineering and Research Incorporation Limited, {2. 100176,china 3. Stainless Steel Company, Baosteel Group, Shanghai 2.1900,china) Univ Sci & Technol beijing Sch Met & Ecol Engn Beijing 100083 Peoples R China Capital Engn & Res Inc Ltd Steel Making & Continuous Casting Engn Inst Beijing 100176 Peoples R China Stainless Steel Co Baosteel Grp Shanghai 201900 Peoples R China

This paper seeks to optimize parameters, reduce the cost of desulphurization and the consumption of operation about KR pretreatment of hot metal at the Stainless Steel Company, Baosteel Group. Based on the theoretical analysis of physical chemistry in metallurgy, simulation experiments of the KR desulphurization of hot metal were conducted in a laboratory and the composition of the desulphurization was optimized, by means of chemical analysis, DSC, SEM and EDS. The water modeling displays the fluid flow characteristics of KR desulphurization. Combination of the techniques and production at the Stainless Steel Company, Baosteel Group, the optimized parameters of the process are put forward.

关键词： desulphurization of hot metal KR, desulphurization thermodynamics water model

Approaches to improving critical current density of YBCO superconducting thick films deposited by electrophoresis

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science china(Physics,{2. & Astronomy) 2004年第2期47卷 165-172页

作者： ZHU Yabin1,2. ZHOU Yueliang2. LIU Zhen2. WANG Shufang2. CHEN Zhenghao2. L?Huibin2. YANG Guozhen2. XIAO Ling3. REN Hongtao3. JIAO Yulei3.& ZHENG Minghui3.1. Department of Physics, College of science, beijing Jiaotong University, beijing 100044,{3. 2. Laboratory of Optical Physics, Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of sciences, beijing 100080,{3. 3. General Research Institute for Nonferrous Metals, beijing 100088,{3. Correspondence should be addressed to Zhu Yabin (email: ybzhu@***) 1. Department of Physics College of Science Beijing Jiaotong University 100044 Beijing China 2. Laboratory of Optical Physics Institute of Physics and Center for Condensed Matter Physics Chinese Academy of Sciences 100080 Beijing China 3. General Research Institute for Nonferrous Metals 100088 Beijing China

Fabrication of YBCO superconducting thick films by electrophoresis has been widely reported. However, the value of critical current density (J c) is far from what the practical application requires. The superconducting thick films are obtained using top-seeded melt growth method with different proportional Y2.aCuO5 (Y2.1) addition. High-pressure oxygen has been used in the annealing process to improve the uniformity of the oxygen content in the superconducting thick films. When 40mol% Y2.1 powder is added to the YBa2.u3.7–5 (Y12.) powder,J c for the superconducting thick film by approaches described above reaches 7.008×103.A/cm2.(77 K, 0 T), which is greater than the value ever reported.

关键词： YBCO thick films, electrophoretic deposition, melt-textured.

A new orthogonality relationship for orthotropic thin plate theory and its variational principle

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science china(Physics,{2. & Astronomy) 2005年第3期48卷 371-380页

作者： LUO Jianhui 1 , LONG Yuqiu 2.& LIU Guangdong 1 1. College of Civil engineering, Hunan University, Changsha 410082.{3. 2. Department of Civil engineering, Tsinghua University, {3. 100084,{3. 1. College of Civil engineering Hunan University 410082 Changsha China 2. Department of Civil engineering Tsinghua University 100084 Beijing China

The thought how dual vectors are constructed in a new orthogonality relationship for theory of elasticity is generalized into orthotropic thin plate bending problems by using the analogy theory between plane elasticity problems and plate bending problems. Dual differential equations are directly obtained by using a mixed variables method. A dual differential matrix to be derived possesses a peculiarity of which principal diagonal sub-matrixes are zero matrixes. Two independently and symmetrically orthogonality sub-relationships are discovered. By using the integral form for elastic bending theory of orthotropic thin plate the orthogonality relationship is demonstrated. By selecting felicitous dual vectors a new orthogonality relationship for theory of elasticity can be generalized into elastic bending theory of orthotropic thin plate. By using the integral form a variational principle which is relative to differential form and a whole function expression are proposed.

关键词： theory of elasticity, thin plate theory, dual vectors, orthogonality relationship, orthotropic, variational principle.

Polycistronic strategy for cyanobacterial expression vector construction: Co-transcription of a human gene and a selective marker gene

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Progress in Natural science:Materials International 2005年第9期15卷 798-803页

作者： ZHANG Yukun1, SHI Dingji2. ZHAO Feifei1, YU Meimin1 and RU Binggen1(1. College of Life science, Peking University, beijing 100871,{2. 2. College of Marine sciences & engineering, Tianjin University of science & Technology, Tianjin 3.0450,{2.) College of Life science Peking University Beijing 100871 China. College of Marine sciences & engineering Tianjin University of Science & Technology Tianjin 300450 China

A polycistronic expression vector, pKGA-NTF1, was constructed for the cyanobacterium. Within this vector, the spectinomycin/streptomycin resistance gene (aadA) facilitated the selection of transformants when co-transcribed with favorite genes. A natural glnA gene was selected as the platform to introduce the plasmid into a neutral site of the Synechococcus sp. PCC 7002.chromosome. Function of the vector was demonstrated by the insertion of a modified human Trefoil factor 3.gene (NTF1) to upstream of the aadA gene and by the analyses of the transformed strains. Antibiotics resistance assays showed that the dicistronic expression cassette conferred high spectinomycin resistance to both the E. coli cells and the Synechococcus cells. PCR analysis and Western-blot analysis were carried out to confirm the integration and expression of the NTF1 gene, respectively. Through simple molecular manipulations, the artificial polycistronic structure described here can be conveniently used to express other favorable genes or operons in cyanobacteria, and to study the cyanobacterial gene expression as well.

关键词： cyanobacterial transformation human Trefoil factor 3 polycistronic expression Synechococcus sp. PCC 7002 vector construction.

Size-dependent hydroxyl radicals generation induced by SiO_2.ultra-fine particles: The role of surface iron

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science china Chemistry 2009年第7期52卷 1033-1041页

作者： SHANG Yu1, ZHU Tong1, LI Yi1,2.& ZHAO JinCai3.1 College of Environmental sciences and engineering, Peking University,{2.,{3. 2.Chinese Academy of Meteorological sciences,{2.,{3. 3.Institute of Chemistry, Chinese Academy of sciences,{2.,{3. 1. College of Environmental sciences and engineering Peking University Beijing 100871 China 2. Chinese Academy of Meteorological sciences Beijing 100871 China 3. Institute of Chemistry Chinese Academy of Sciences Beijing 100871 China

Oxidative stress and hydroxyl radicals (·OH) play important roles in adverse health effects caused by inhalable ambient air particles (PM10). The ultra-fine fraction of PM10 has been hypothesized as one of the critical contributors to ·OH generation. Both in vivo and in vitro studies have shown that ultra-fine particles (UFPs) or nano-particles generate more ·OH than larger particles with identical mass and composition. Both the surface area and surface-adsorbed redox-active metals have been suggested as factors to determine the oxidative capacity of UFPs. In this study, the ·OH-generating capability of dif-ferent sizes of SiO2.particles was investigated in order to determine which factor influences particle-induced ·OH generation. The amount of ·OH generated in both acellular and cellular systems was quantified using a capillary electrophoresis method following exposure to SiO2.particles with diameters of 14, 100, and 500 nm. The amount of ·OH was strongly dependent on particle size, and a significant enhancement was observed only with 14 nm particles. Further studies indicated a close association between ·OH and iron ion concentration (R2.= 0.812. p2.particles is presented as a possible mechanism of UPFs-induced ·OH generation. The SiO2.acted as an inert substrate, and the surface of ultra-fine SiO2.particles acted as a carrier for iron.

关键词： ultra-fine particles nano-particles ·OH oxidative stress size-effect

Critical slope gradient for compulsory abandonment of farmland on the hilly Loess Plateau

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Chinese science Bulletin 1998年第5期43卷 409-412页

作者： TANG Keli+1, ZHANG Keli 1,2.and LEI Aling 1,3.1. Institute of Soil and Water Conservation, Chinese Academy of sciences, Yangling 712.00,{3. 2. Department of Hydraulic {2., Tsinghua University, {3. 100084,{3. 3. Water Resources C Institute of Soil and Water Conservation Chinese Academy of Sciences Yangling China Department of Hydraulic engineering Tsinghua University Beijing China Water Resources Conservation Bureau of Yangtze River Ministry of Water Resources Wuhan China

Scientific evidence for the upper limit of farmland is proposed. Shallow gully erosion is one of erosion types distributed extensively on sloping farmland in the hilly regions of the Loess Plateau. Field observation and aerial photos interpretation, as well as laboratory experiments show that the shallow gully erosion occurring on the steeper farmland in the hilly regions of the Loess Plateau is an important factor leading to intensive erosion on slope, because of its extensive distribution and intensive runoff collection. The data on the formation, development and distribution of shallow gullies on sloping farmland indicate that critical slope gradient for shallow gully initiation ranges from 15 to 2. degrees with an average of 18.2.degrees. Therefore, it is suggested that critical slope gradient for compulsory abandonment of farmland on the hilly Loess Plateau should be kept within the critical slope gradient for shallow gully initiation to prevent shallow gully formation in order to control soil loss more effectively. But as the first step, the cultivation on the slopes with slope larger than 2. degrees where the maximum erosion occurs should be strictly forbidden.

关键词： hilly region of Loess Plateau upper limitation for farmland shallow gully erosion erosion dynamic.

A land surface model incorporated with soil freeze/thaw and its application in GAME/Tibet

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science china Earth sciences 2006年第12期49卷 1311-1322页

作者： HU Heping1, YE Baisheng2. ZHOU Yuhua3.& TIAN Fuqiang1 1. Department of Hydraulic engineering, Tsinghua University, beijing 100084,{2. 2. Cold and Arid Regions Environmental and engineering Research Institute, Chinese Academy of sciences, Lanzhou 73.000,{2. 3. Department of Civil engineering, Massachusetts Institute of Technology, USA 1. Department of Hydraulic engineering Tsinghua University Beijing 100084 China 2. Cold and Arid Regions Environmental and engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China 3. Department of Civil engineering Massachusetts Institute of Technology USA

Land surface process is of great importance in global climate change, moisture and heat exchange in the interface of the earth and atmosphere, human impacts on the environment and eco- system, etc. Soil freeze/thaw plays an important role in cold land surface processes. In this work the diurnal freeze/thaw effects on energy partition in the context of GAME/Tibet are studied. A sophisti- cated land surface model is developed, the particular aspect of which is its physical consideration of soil freeze/thaw and vapor flux. The simultaneous water and heat transfer soil sub-model not only reflects the water flow from unfrozen zone to frozen fringe in freezing/thawing soil, but also demon- strates the change of moisture and temperature field induced by vapor flux from high temperature zone to low temperature zone, which makes the model applicable for various circumstances. The modified Picard numerical method is employed to help with the water balance and convergence of the numerical scheme. Finally, the model is applied to analyze the diurnal energy and water cycle char- acteristics over the Tibetan Plateau using the Game/Tibet datasets observed in May and July of 1998. Heat and energy transfer simulation shows that: (i) There exists a negative feedback mechanism between soil freeze/thaw and soil temperature/ground heat flux; (ii) during freezing period all three heat fluxes do not vary apparently, in spite of the fact that the negative soil temperature is higher than that not considering soil freeze; (iii) during thawing period, ground heat flux increases, and sensible heat flux decreases, but latent heat flux does not change much; and (iv) during freezing period, soil temperature decreases, though ground heat flux increases.

关键词： land surface model,soil freeze/thaw,GAME/Tibet,simultaneous liquid,vapor and heat transfer.

IL-8-induced L-selectin shedding regulates its binding kinetics to PSGL-1

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Chinese science Bulletin 2009年第16期54卷 2786-2793页

作者： JIA XiaoLing1,2.3. CHEN Juan1,2.& LONG Mian1,2.1 National Microgravity Laboratory, Institute of {3., Chinese Academy of sciences, {2. 100190,{3. 2.Center of Bio{3. and Bioengineering, Institute of {3., Chinese Academy of sciences, {2. 100190,{3. 3.School of Biological science and Medical engineering, Beihang University, {2. 100083.{3. National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China Center of Biomechanics and Bioengineering Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China School of Biological science and Medical engineering Beihang University Beijing 100083 China

L-selectin plays a crucial role in inflammation cascade by initiating the tethering and rolling of leukocytes on endothelium wall. While many L-selectin molecules are rapidly shed from the cell surface upon activation, the remaining membrane-anchored L-selectin may still play an important role in regulating leukocyte rolling and adhesion with different binding kinetics. Here we developed an in vitro model to activate Jurkat cells via interlukin-8 (IL-8) and quantified the two-dimensional (2.) binding kinetics, using a micropipette aspiration assay, of membrane-anchored L-selectin to P-selectin glycoprotein ligand 1 (PSGL-1) ligand coupled onto human red blood cells (RBCs). The data indicated that L-selectin shedding reduced the amount of membrane-anchored L-selectin and lowered both its reverse and forward rates. These results suggested that the rolling dynamics of activated leukocytes was determined by two opposite impacts: reducing the surface presentation would enhance the rolling but lowering the kinetic rates would decrease the rolling. This finding provides a new insight into under-standing how L-selectin shedding regulates leukocyte rolling and adhesion.

关键词：结合动力学选择素配体白细胞介素8 Jurkat细胞诱导细胞表面微管吸吮