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Numerical investigation on damping coefficient of the integral squeeze film damper

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High Technology Letters 2022年第3期28卷 317-327页

作者： li Geng HE lidong JIA Xingyun ZHANG Yipeng WANG Jian Engineering Research Center of Chemical Safety Ministry of Education Beijing University of Chemical TechnologyBeijing 100029P.R.China

The elimination of rotor vibration is usually achieved by applying additional damping to the *** film dampers are widely used in various aerospace and turbine *** research is carried out on flow characteristics in the integral squeeze film dampers(ISFDs).The dynamic response to the operation condition is investigated through the computational fluid dynamics(CFD) model of *** to the large pressure loss at the oil inlet,the oil film force only changes slightly with the increase of oil supply pressure,and the damping increases *** vibration amplitude only affects the film force,but has no effect on the *** oil film force and damping show an upward tendency with the decrease of thickness of the end seal clearance.

关键词： integral squeeze film damper(ISFD) numerical method oil film force damping coefficient

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我国流通产业与国民经济的协同演进分析

财贸经济 2014年第1期35卷 105-114页

作者：李丽北京工商大学经济学院

经过30多年的快速稳步发展,我国流通产业在国民经济中的基础性及先导性地位已逐步确立。本文基于协同学理论,针对我国流通产业与国民经济的协同关系加以验证,纵览流通产业的成长历程,设计协同度评价模型,揭示我国流通产业与国民经济协... 详细信息

经过30多年的快速稳步发展,我国流通产业在国民经济中的基础性及先导性地位已逐步确立。本文基于协同学理论,针对我国流通产业与国民经济的协同关系加以验证,纵览流通产业的成长历程,设计协同度评价模型,揭示我国流通产业与国民经济协同演进的一般规律。研究发现,我国流通产业与国民经济的发展不够协调,流通产业对国民经济平稳运行的推进效应大于抑制效应,流通产业与国民经济整体协调程度还有较大的提升空间。

关键词：流通产业国民经济协同演进协同学

Synthesis of hexagonal boron nitrides by chemical vapor deposition and their use as single photon emitters

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Nano Materials Science 2021年第3期3卷 291-312页

作者： Hongwei liu Chae Young You Jingwei li Patrick Ryan Galligan Jiawen You Zhenjing liu Yuting Cai Zhengtang Luo Department of Chemical and Biological Engineering the Hong Kong University of Science and TechnologyClear Water BayKowloon999077Hong Kong

Two-dimensional(2D)hexagonal boron nitride(hBN),due to its extraordinary thermal,chemical,and optical properties,has arisen as an enticing material for the research community to explore for various applications,including the use of site defects in hBN as single photon emitters(SPEs).In this review,we systematically summarize recent advanced strategies towards the controllable synthesis of 2D hBN using chemical vapor deposition,towards a full control of the domain size,orientation,morphology,layer number,and stacking order,***,we review the underlying mechanisms for single photon emission(SPE)in hBN and methods to selectively generate and tune the ***(e.g.,carbon substituted defects)are discussed for the potential use as emission *** finally give an outlook of future challenges and opportunities on desirable hBN synthesis and further investigation of SPEs in hBN,targeting to utilize hBN as single photon emitters in an industrial scale.

关键词： hBN CVD Controllable synthesis Single photon emission

Underlying slip/twinning activities of Mg-xGd alloys investigated by modified lattice rotation analysis

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Journal of Magnesium and Alloys 2023年第3期11卷 998-1015页

作者： Biaobiao Yang Chenying Shi Xianjue Ye Jianwei Teng Ruilin Lai Yujie Cui Dikai Guan Hongwei Cui Yunping li Akihiko Chiba State Key Lab for Powder Metallurgy Central South UniversityChangsha 410083China Institute for Materials Research Tohoku UniversitySendai 980-8577Japan Department of Materials Science and Engineering University of SheffieldMappin StreetSheffield S13JDUnited Kingdom School of Materials Science and Engineering Shandong University of TechnologyZibo 255000China

The inconsistencies regarding the fundamental correlation between Gd content and slip(twinning)activities of Mg alloys appeal further ***,the traditional slip dislocations analysis by TEM is time-consuming,and that by SEM/EBSD cannot recognize the partial slip *** urge a more efficient and comprehensive approach to easily distinguish all potential slip modes occurred concurrently in alloy *** we report a modified lattice rotation analysis that can distinguish all slip systems and provide statistical results for slip activities in Mg alloy *** this method,the high ductility of Mg-Gd alloy ascribed to the enhanced non-basal slips,cross-slip,and postponed twinning activities by Gd addition is quantitatively clarified.

关键词： Mg-Gd alloy Non-basal slips Postponed twinning Grain boundary segregation Modified lattice rotation analysis

Preparation and Performance of Pueraria lobata Root Powder/Polylactic Acid Composite Films

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Journal of Renewable Materials 2023年第6期11卷 2531-2553页

作者： Shuang Zhao Shenglan Chen Shuan Ren Gang li Ke Song Jie Guo Shima liu Jian He Xianwu Zhou Key Laboratory of Hunan Forest Products and Chemical Industry Engineering Jishou UniversityZhangjiajie427000China Central South Inventory and Planning Institute of National Forestry and Grassland Administration Changsha410000China School of Civil Engineering and Architecture Jishou UniversityZhangjiajie427000China College of Chemistry and Chemical Engineering Jishou UniversityJishou416000China

Petroleum-based materials,such as plastic,are characterized by adverse environmental pollution;as a result,researchers have sought alternative degradable plastics that are environmentally friendly,such as polylactic acid(PLA).PLA has shown great potential to replace petroleum-based *** this study,seven different samples of unmodified Pueraria lobata root powder(PRP)with different contents(i.e.,0,5,10,15,20,25,and 30 wt%)and three different modified PRPs(i.e.,treated with NaOH,NaOH-KH-550,and Formic)were used to reinforce polylactic acid(PLA)via solution casting *** prepared PRP/PLA composite films were characterized using SEM,FTIR,UV-visible spectra analysis,TG,DSC,weight loss measurement(wt%),and mechanical *** results showed that the PRP modified with KH-550(PRPK)intensified the interaction in the interface region between the PRP and the PLA matrix,thus increasing the tensile strength(54.5 MPa),elongation at break(2.8%),and Young’s modulus(3310 MPa)of the PRPK/PLA *** angle measurement showed that the PRP treatments contributed to the hydrophobicity of *** transparency of PRP-10/PLA film atλ_(800)was 11.09%,and its UVA and UVB transmittance were 3.28 and 1.16,*** blending PLA with PRP,the PRP/PLA composite films exhibited excellent *** summary,PRPK improved the mechanical properties of PLA and prevented the films from ultraviolet light,suggesting that PRPK-5/PLA film could be used as packaging materials.

关键词： Pueraria lobata root powder polylactic acid biocomposite films properties

Electrocatalytic generation of hydrogen peroxide on cobalt nanoparticles embedded in nitrogen-doped carbon

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Chinese Journal of Catalysis 2021年第12期42卷 2296-2305页

作者： Basil Sabri Rawah Wenzhen li Chemical and Biological Engineering Department Biorenewables Research LaboratoryIowa State UniversityAmesIA 50011USA Chemical and Biological Engineering Department University of JeddahJeddah 23890Saudi Arabia

Electrocatalytic reduction of oxygen is a growing synthetic technique for the sustainable production of hydrogen peroxide(H_(2)O_(2)).The current challenges concern seeking low-cost,highly active,and selective ***-nitrogen-doped carbon containing catalytically active cobalt-nitrogen(Co-N_(x))sites is an emerging class of materials that can promote the electrochemical generation of H_(2)O_(2).Here,we report a straightforward method for the preparation of cobalt-nitrogen-doped carbon composed of a number of Co-N_(x)moieties using low-energy dry-state ball milling,followed by controlled *** scalable method uses inexpensive materials containing cobalt acetate,2-methylimidazole,and Ketjenblack EC-600jd as the metal,nitrogen,and carbon precursors,*** measurements in an acidic medium show the present material exhibits a significant increase in the oxygen reduction reaction current density,accompanied by shifting the onset potential into the positive *** current catalyst has also demonstrated an approximate 90%selectivity towards H_(2)O_(2)across a wide range of *** H_(2)O_(2)production rate,as measured by H_(2)O_(2)bulk electrolysis,has reached 100 mmol g_(cat).^(–1)h^(–1)with high H_(2)O_(2)faradaic efficiency close to 85%(for 2 h at 0.3 V ***).Lastly,the catalyst durability has been tested(for 6 h at 0.3 V ***).The catalyst has shown relatively consistent performance,while the overall faradic efficiency reaches approximate 85%throughout the test cycle indicating the promising catalyst durability for practical *** formed Co-N_(x)moieties,along with other parameters,including the acidic environment and the applied potential,likely are the primary reasons for such high activity and selectivity to H_(2)O_(2)production.

关键词： Hydrogen peroxide Two-electron oxygen reduction Carbon catalyst Electrocatalysis

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Peripheral Blood Mitochondrial DNA Copy Number and Hypertension Combined with Albuminuria in Chinese Coal Miners

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Biomedical and Environmental Sciences 2021年第7期34卷 567-571页

作者： ZHANG Wen Ping ZHANG Yi Fan ZHANG Ying Ying HAN Zhi Chao GAO Yuan Yuan GUO Jian Yong SHI Xiu Jing HU Xiao Qin MU li Na ZHOU Yun LEI li Jian Department of Toxicology Shanxi Medical UniversityTaiyuan 030001ShanxiChina Department of Epidemiology School of Public HealthShanxi Medical UniversityTaiyuan 030001ShanxiChina School of Public Health and Health Professions State University of New York at buffaloBuffalo 14214NYUSA Department of Nephrology Shanxi Provincial People's HospitalTaiyuan 030001ShanxiChina

Hypertension is an increasingly prevalent chronic disease that affects approximately 1 billion people *** blood pressure inflicts longterm damage to various organs,including the *** aggravates the clinical course of chronic kidney disease,and promotes progression toward end-stage renal *** the cases of end-stage renal disease,30%are directly attributable to *** the molecular mechanism responsible for renal injury remains largely unknown,elucidating this mechanism is critical to preventing these deleterious complications.

关键词： Blood organs kidney

Fabrication of Pd-based metal-acid-alkali multifunctional catalysts for one-pot synthesis of MIBK

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Chinese Journal of Catalysis 2018年第8期39卷 1384-1394页

作者： Rui Ma Yunpeng li Guandong Wu Yufei He Junting Feng Yingying Zhao Dianqing li State Key Laboratory of Chemical Engineering Beijing University of Chemical TechnologyBeijing100029China Beijing Engineering Center for Hierarchical Catalysts Beijing University of Chemical TechnologyBeijing100029China

The one-pot synthesis of methyl isobutyl ketone（MIBK） from acetone using multifunctional catalysts is an important sustainable organic synthesis method with high atom and energy ***. we report a series of Pd supported on mixed metal oxide（MMO） catalysts with controllable acidic/basic/metallic sites on the surface. We study the relationship between the nature, synergy,and proximity of active sites and the catalytic performance of the multifunctional catalyst in the tandem reaction, in detail. In the existence of Lewis acid and base sites, the catalysts with medium-strength acidic/basic sites show preferred activity and/or MIBK selectivity. For multifunctional catalysts, the catalytic properties are more than just a collection of active sites, and the Pd/Mg_3Al-MMO catalyst possessing 0.1% Pd loading and ~0.4 acid/base molar ratio exhibits the optimal 42.1% acetone conversion and 37.2% MIBK yield, which is among the best reported so far for this tandem reaction under similar conditions. Moreover, the proximity test indicates that the intimate distance between acidic/basic/metallic sites can greatly shorten the diffusion time of the intermediate species from each active site, leading to an enhancement in the catalytic performance.

关键词： One‐pot synthesisof methyl isobutyl ketone Multifunctional catalyst PdMg3Al mixedmetal oxide Synergy effect Proximity

Bt-cry1ie毒素对中华蜜蜂中肠细菌多样性无影响

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Bt-cry1ie毒素对中华蜜蜂中肠细菌多样性无影响