检索结果-南通市图书馆

The unique structural and functional features of CXCL12

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Cellular & Molecular Immunology 2018年第4期15卷 299-311页

作者： Rik Janssens Sofie Struyf paul Proost Department of Microbiology and Immunology Rega Institute for Medical ResearchLaboratory of Molecular ImmunologyKU LeuvenUniversity of LeuvenLeuven B-3000Belgium

The CXC chemokine CXCL12 is an important factor in physiological and pathological processes, includingembryogenesis, hematopoiesis, angiogenesis and inflammation, because it activates and/or induces migration ofhematopoietic progenitor and stem cells, endothelial cells and most leukocytes. Therefore, CXCL12 activity istightly regulated at multiple levels. CXCL12 has the unique property of existing in six splice variants in humans,each having a specific tissue distribution and in vivo activity. Controlled splice variant transcription and mRNAstability determine the CXCL12 expression profile. CXCL12 fulfills its functions in homeostatic and pathologicalconditions by interacting with its receptors CXC chemokine receptor 4 (CXCR4) and atypical chemokine receptor 3(ACKR3) and by binding to glycosaminoglycans (GAGs) in tissues and on the endothelium to allow a properpresentation to passing leukocytes. Homodimerizaton and heterodimerization of CXCL12 and its receptors can altertheir signaling activity, as exemplified by the synergy between CXCL12 and other chemokines in leukocyte migrationassays. Receptor binding may also initiate CXCL12 internalization and its subsequent removal from theenvironment. Furthermore, CXCL12 activity is regulated by posttranslational modifications. Proteolytic removal ofNH2- or COOH-terminal amino acids, citrullination of arginine residues by peptidyl arginine deiminases or nitrationof tyrosine residues reduce CXCL12 activity. This review summarizes the interactions of CXCL12 with the cellularenvironment and discusses the different levels of CXCL12 activity regulation.

关键词： ACKR3 chemokine CXCL12 CXCR4 regulation

Effects of wood species and retention levels on removal of copper,chromium,and arsenic from CCA-treated wood using sodium hypochlorite

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 Forestry Research 2016年第2期27卷 433-442页

作者： Engin Derya Gezer paul A.Cooper Department of Forest Industry Engineering Karadeniz Technical University61080 TrabzonTurkey Faculty of Forestry University of Toronto33 Willcocks St.TorontoON M5S 3B3Canada

Chemical extraction, bioremediation, and electrodialytic processes have been extensively studied for removal of copper, chromium, and arsenic from wood treated with chromated copper arsenate （CCA）. However, one problem has not been addressed： the effects of wood species and retention levels on remediation efficiency. The objectives of this study were to investigate the effects of wood species and retention levels on removal of copper, chromium, and arsenic from CCA-treated wood samples using sodium hypochlorite. Our results showed that sodium hypochlorite （NaOC1） was very effective for removal of copper, chromium, and arsenic from CCA-C treated milled wood samples for all three species used in this study. The Cu, Cr, and As extraction efficiencies for red pine were 95 % Cu, 97 % Cr and 94 % As, for maple were 95 % Cu, 97 % Cr, and 98 % As at 4.0 kg m-3 retention levels, and for aspen were 95 % Cu, 92% Cr, and 91% As at 9.6 kg m-3 retention level, respectively. However, the results showed that wood species and initial retention levels of CCA-treated wood products played very impor- tant roles in terms of removal of Cu, Cr, and As.

关键词： Chromated copper arsenate (CCA) Remediation Remediation efficiency Wood species Retention level

Morphological and electrical properties of SrTiO3/TiO2/SrTiO3 sandwich structures prepared by plasma sputtering

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2017年第1期26卷 156-159页

作者： Saqib Jabbar Riaz Ahmad paul K Chu Government College University Lahore 54000 Pakistan Department of Physics and Materials Science City University of Hong Kong Kowloon Hong Kong China

SrTiO3（STO） and TiO2 are insulating materials with large dielectric constants and opposite signs of the quadratic coefficient of voltage（α）. Insertion of a TiO2 thin film between STO layers increases the linearity of the capacitance in response to an applied voltage, to meet the increasing demand of large-capacitance-density dynamic random access memory capacitors. Both STO and TiO2 suffer from the problem of high leakage current owing to their almost equivalent and low bandgap energies. To overcome this, the thickness of the thin TiO2 film sandwiched between the STO films was varied. A magnetron sputtering system equipped with radio frequency and direct current power supply was employed for depositing the thin films. Ti N was deposited as the top and bottom metal electrodes to form a metal–insulator metal（MIM） structure,which exhibited a very large linear capacitance density of 21 fF/um-2 that decreased by increasing the thickness of the TiO2 film. The leakage current decreased with an increase in the thickness of TiO2, and for a 27-nm-thick film, the measured leakage current was 2.0 × 10^-10 A. X-ray diffraction and Raman spectroscopy revealed that Ti N, STO, and TiO2 films are crystalline and TiO2 has a dominant anatese phase structure.

关键词： strontium titanate Raman spectroscopy plasma deposition MIM capacitor

Influence of inter-grain cementation stiffness on the effective elastic properties of porous Bentheim sandstone

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2023年第3期15卷 573-583页

作者： Bin Chen Jiansheng Xiang John-paul Latham Department of Earth Science and Engineering Faculty of EngineeringImperial College LondonLondonSW72BXUK

Effective elastic properties of porous media are known to be significantly influenced by *** this paper,we investigated the influence of another critical factor,the inter-grain cementation stiffness,on the effective elastic properties of a granular porous rock(Bentheim sandstone)using an advanced numerical workflow with realistic rock microstructure and a theoretical ***,the disparity between the experimentally tested elastic properties of Bentheim sandstone and the effective elastic properties predicted by empirical equations was ***,a micro-computed tomography(CT)-scan based approach was implemented with digital imaging software AVIZO to construct the 3D(three-dimensional)realistic microstructure of Bentheim *** microstructural model was imported to a mechanics solver based on the 3D finite element model with inter-grain boundaries modelled by cohesive *** simulations were run to test the effective elastic properties for different shear and normal intergrain cementation ***,a relation between the macroscale Young’s modulus and inter-grain cementation stiffness was derived with a theoretical model which can also account for porosity *** the numerical and theoretical results indicate the influence of the inter-grain cementation stiffness,on the effective elastic properties is significant for porous *** calibrated normal and shear stiffnesses at the inter-grain boundaries are 1.2×10^(5) and 4×10^(4) GPa/m,respectively.

关键词： Porous sandstone Cohesive finite element model Grain-based model Rock microstructure Micro-computed tomography(CT)

The Clean Development Mechanism and Sustainable Development in China's Electricity Sector

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 Population,Resources and Environment 2005年第2期3卷 3-13页

作者： paul A.Steenhof Department of Geography and Environmental Studies Carleton University Ottawa OntarioK1S 5B6 Canada2 Climate Change Specialist SNC Lavalin Environment Inc. Montreal Quebec H2Z 1Z3Canada

The Clean Development Mechanism,a flexibility mechanism contained in the KyotoProtocol, offers China an important tool to attractinvestment in clean energy technology and processesinto its electricity sector. The Chinese electricitysector places centrally in the country’s economy andenvironment, being a significant contributor to theacid rain and air pollution problems that plague manyof China’s cities and regions, and therefore a focusof many related energy and environmental ***’s electricity sector has also been the subjectof a number of economic analyses that have showedthat it contains the highest potential for clean energyinvestment through the Clean DevelopmentMechanism of any economic sector in China. Thismechanism, through the active participation frominvestors in more industrialized countries, can helpalleviate the environmental problems attributable toelectricity generation in China through advancingsuch technology as wind electricity generation, cleancoal technology, high efficient natural gas electricitygeneration, or utilization of coal mine methane. Inthis context, the Clean Development Mechanismalso compliments a range of environmental and energypolicies which are strategizing to encourage thesustainable development of China’s economy.

关键词： Clean Development Mechanism(CDM) greenhouse gas emissions climate policy China’s electricity sector

Challenges to quantitative applications of Landsat observations for the urban thermal environment

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2017年第9期29卷 80-88页

作者： Feng Chen Song Yang Kai Yin paul Chan School of Atmospheric Sciences Sun Yat-sen UniversityZhuhai 519082China Institute of Earth Climate and Environment System Sun Yat-sen UniversityOuangzhou 510275China Fujian Key Laboratory of Sensing and Computing.for Smart City Xiarnen UniversityXiarnen 361005China Institute of Remote Sensing and Digital Earth Chinese Academy of SciencesBeijing 10094China Climate Decision LLC BethesdaMDUSA

Since the launch of its first satellite in 1972, the Landsat program has operated continuously for more than forty years. A large data archive collected by the Landsat program significantly benefits both the academic community and society. Thermal imagery from Landsat sensors, provided with relatively high spatial resolution, is suitable for monitoring urban thermal environment. Growing use of Landsat data in monitoring urban thermal environment is demonstrated by increasing publications on this subject, especially over the last decade. Urban thermal environment is usually delineated by land surface temperature（LST）. However, the quantitative and accurate estimation of LST from Landsat data is still a challenge, especially for urban areas. This paper will discuss the main challenges for urban LST retrieval, including urban surface emissivity, atmospheric correction, radiometric calibration, and validation. In addition, we will discuss general challenges confronting the continuity of quantitative applications of Landsat observations. These challenges arise mainly from the scan line corrector failure of the Landsat 7 ETM ＋ and channel differences among sensors. Based on these investigations, the concerns are to：（1） show general users the limitation and possible uncertainty of the retrieved urban LST from the single thermal channel of Landsat sensors;（2） emphasize efforts which should be done for the quantitative applications of Landsat data; and（3） understand the potential challenges for the continuity of Landsat observation（i.e., thermal infrared） for global change monitoring, while several climate data record programs being in progress.

关键词： Remote sensing Radiometric calibration SLC-off Surface temperature Data consistency

A PERISHABLE INVENTORY SYSTEM WITH SERVICE FACILITIES, MAP ARRIVALS AND PH- SERVICE TIMES

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2007年第1期16卷 62-73页

作者： paul MANUEL B. SIVAKUMAR G. ARIVARIGNAN Department of Information Science Kuwait University Kuwait. Department of Applied Mathematics and Statistics School of Mathematics Madurai Kamaraj University Madurai Tamilnadu India

We consider a continuous review perishable （s,S） inventory system with a service facility consisting of a waiting hall of finite capacity and a single server. We assume two types of customers, ordinary and negative, arrive according to a Markovian Arrival Process （MAP）. An ordinary customer joins the queue and a negative customer instead of joining the queue removes one ordinary customer from the queue. The removal rule adopted in this paper is RCE （removal of a customer from the end）. The individual customer＇s unit demand is satisfied after a random time of service which is assumed to have a phase-type distribution. The life time of each item and the lead time of the reorders have been assumed to be independent exponential distributions. The joint probability distribution of the number of customers in the system and the inventory level is obtained for the steady state case. Various stationary system performance measures are computed and the total expected cost rate is calculated. The results are illustrated numerically.

关键词： Stochastic inventory Markovian demands service facility positive lead time negative customers

Designing multilayer diamond like carbon coatings for improved mechanical properties

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 Materials Science & Technology 2021年第6期65卷 108-117页

作者： Mohammad Sharear Kabir Zhifeng Zhou Zonghan Xie paul Munroe School of Materials Science and Engineering University of New South WalesSydneyNSW.2052Australia mineAlloy Institute for Frontier MaterialsDeakin UniversityWaum PondsVIC3217Australia Advanced Coatings Applied Research Laboratory Department of Mechanical and Biomedical EngineeringCity University of Hong Kong.KowloonHong KongChina School of Mechanical Engineering University of AdelaideSA5005Australia School of Engineering Edith Cowan University.WA6027Australia

New multilayer coatings were produced by incorporating alternating soft and hard DLC layers enabled by varying the bias voltage during deposition process while maintaining a constant hard-to-soft layer thickness *** coatings were deposited onto a Cr/Cr Cxgraded layer by closed field unbalanced magnetron sputtering(CFUBMS).The cross-sectional analysis of the coatings showed that the multilayer coatings possess sharp interfaces between the soft and hard layers with the hard to soft layer thickness ratio(1:1.33)constant in all the *** analysis uncovered the increasing sp^(3)character of the DLC coatings as a result of decreasing ID/IGratio and increasing full width at half maximum(FWHM)values of the G band peak induced supposedly by an increase in bias voltage during hard layer *** tests showed an increase in hardness of the DLC coatings which can be correlated with the increase in the sp^(3)content of the coatings as well as decreasing sp^(2)-C cluster size,as calculated from the ID/***,the coatings exhibited excellent plastic deformation resistance and adhesion strength upon microindentation and scratch testing,*** further investigations are required to assess coating durability,the multilayer design could offer the DLC coatings with a rare opportunity to combine the high hardness with damage resistance with a constant bilayer thickness and without the need to introduce complex multilayer system.

关键词： Diamond like carbon(DLC) Closed field unbalanced magnetron sputtering(CFUBMS) sp^(3)Character Nanoindentation Plastic deformation resistance Scratch adhesion behaviour

Oxidation behaviors of Co-Al-W-0.1B superalloys in a long-term isothermal exposure at 900~?C

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2018年第11期34卷 2212-2217页

作者： Yuzhi Li Florian Pyczak Jonathan paul Zekun Yao School of Materials Science and Engineering Northwestern Polytechnical UniversityXi'an 710072China Institute of Materials Research Helmholtz-Zentrum Geesthacht21502 GeesthachtGermany

Co-Al-W-0.1B superalloys have been isothermally oxidized at 900℃ for 1000,5000 and 10000 h in order to investigate their oxidation *** oxide layers and morphologies were characterized by X-ray diffraction and scanning electron microscopy combined with energy-dispersive ***1000 h exposure,a Co3W/γ zone,an Al2O3layer,a mixture of Co,Al,W oxides layer and a CoO layer are established on the substrate *** extended oxidation,a discontinuous Al2O3layer in Co-9Al-8W-0.1B and Co-9Al-9W-0.1B alloys leads to an additional mixed oxide layer on the substrate instead of the Co3W/γ *** oxide layers that form on the Co-9Al-8W-0.1B and Co-9Al-9W-0.1B alloys are much thicker than those on the Co-9Al-11W-0.1B alloy,and continuously thicken during *** higher content of W is beneficial to improving the oxidation resistance as it facilitates a faster formation of Co3Was well as Al2O3.

关键词： Isothermal oxidation CoO layer Al2O3 layer Co3W/γ