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Journal of Magnesium and Alloys 2022年第10期10卷 2833-2846页

作者： Jae Won cha Sang-Cheol Jin Jae-Gil Jung Sung Hyuk Park School of Materials Science and Engineering Kyungpook National University80 DaehakroDaegu 41566Republic of Korea Advanced Metals Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea

This study investigates the effects of billet homogenization temperature on the dynamic recrystallization behavior during high-speed extrusion and resultant microstructure and tensile properties of the Mg–5Bi–3Al(BA53,wt%)*** billets homogenized at 350 and450℃(350H and 450H billets)are extruded at a high speed of 69 m/*** 350H billet has a relatively smaller grain size and a higher abundance of fine Mg3Bi2particles compared to the 450H *** extrusion of the 350H billet,enhanced dynamic recrystallization occurs as a result of its finer grains and abundance of particles,while the growth of recrystallized grains is suppressed by the grain-boundary pinning effect of ***,the extruded 350H material is characterized by smaller grains,relatively greater number of Mg3Bi2particles,and a higher internal strain energy than the extruded 450H *** tensile strength of the extruded 350H material is higher than that of the extruded 450H material owing to stronger grain-boundary hardening,particle hardening,and strain hardening *** extruded 350H material also exhibits a higher tensile elongation as its smaller grains inhibit the formation of crack-inducing undesirable twins during *** results from this study demonstrate that a decrease in the homogenization temperature from 450 to 350℃leads to improved strength and ductility in the high-speed-extruded BA53 material.

关键词： Mg–Bi–Al alloy High-speed extrusion Homogenization Dynamic recrystallization Tensile properties

河北省肉牛养殖高质量发展评价体系构建及测度

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河北农业科学 2024年第2期28卷 87-94页

作者：王宇航魏子昊崔姹河北农业大学经济管理学院河北保定071000

为了科学设计指标体系评价及测度肉牛养殖高质量发展水平,从养殖高效、生产安全、绿色发展及福利提升4个维度,构建了肉牛养殖高质量发展评价指标体系;并基于河北省肉牛养殖微观调研数据,采用熵权法对其发展程度进行了研究。结果表明:(1)... 详细信息

为了科学设计指标体系评价及测度肉牛养殖高质量发展水平,从养殖高效、生产安全、绿色发展及福利提升4个维度,构建了肉牛养殖高质量发展评价指标体系;并基于河北省肉牛养殖微观调研数据,采用熵权法对其发展程度进行了研究。结果表明:(1)2019-2022年河北省肉牛养殖高质量发展水平波动上升,且内部发展不平衡。养殖高效维度、生产安全维度是综合得分提升的主要驱动力;福利提升维度是阻碍因素。(2)不同规模养殖户肉牛养殖高质量发展水平差异较大,大规模养殖户的肉牛养殖高质量综合得分最高,小规模养殖户的肉牛养殖高质量综合得分最低。散养、小规模养殖户肉牛养殖高质量发展的主要驱动因素为绿色发展和养殖高效;中规模、大规模养殖户肉牛养殖高质量发展的主要驱动因素为养殖高效和生产安全。(3)劳动生产率、机械化水平与出栏率是养殖高效维度提升的主要驱动力,发病率与死亡率是安全生产维度提升的主要驱动力,种养平衡率与粪污还田能力是绿色发展维度提升的主要驱动力,现代化设备投入水平是福利提升维度的主要驱动因素。头均收益、饲料报酬率、防疫周期、废弃物资源化利用水平和饲养密度是4个维度提升的制约因素。饲料报酬率与肉牛出栏率、防疫周期、种养平衡率和粪污还田能力、现代化设备水平是散养户、小规模养殖户4个维度提升的主要驱动力,平均日增重、死亡率和发病率、废弃物资源化利用水平、饲养密度分别是制约因素;劳动效率、死亡率和发病率、资源利用强度、现代化设备水平是中大规模养殖户4个维度提升的主要驱动力,平均日增重、防疫周期、种养平衡率、饲养密度是制约因素。提出以种养结合为抓手,推进肉牛养殖绿色高效发展;提高肉牛养殖现代化发展水平;引导中小规模养殖户提升养殖高质量发展水平的对策建议。

关键词：河北省肉牛养殖高质量发展熵权法

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A Regional Economy's Resistance to the COVID-19 Shock: Sales Revenues of Micro-, Small-, and Medium-Sized Enterprises in South Korea

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International Journal of Disaster Risk Science 2022年第2期13卷 190-198页

作者： Seong-Jin Lee Joong-Hoo Park Seung-Min cha Donghyun Kim Department of Public Policy and Management.Pusan National University Busan 46241South Korea Department of Urban Planning and Engineering Pusan National UniversityBusan 46241South Korea

The coronavirus disease 2019(COVID-19) is a global pandemic that has heavily impacted not only the health sector, but also the economic sector in *** countries have projected a negative economic impact, and the effect on micro-, small-, and medium-sized enterprises(MSMEs) is predicted to be significantly *** study estimated the regional resistance of MSME sales revenues and identified the regional economic factors that affect resistance by analyzing South Korea, a country with one of the lowest economic impact projections from COVID-19. Resistance was estimated by comparing sales revenues and changes in resistance observed during the early COVID-19 period to those recorded in the same weeks(weeks 6 to 9) of 2019. The factors that affect regional resistance were determined by conducting robust regression and spatial regression analyses. The results show that the number of confirmed COVID-19 cases, a direct risk factor, is negatively related to regional resilience, while diversity is positively related to regional resistance. To improve the regional resistance against uncertain events, this study recommends increased diversity among regional industrial structures to reduce the duration of the early shock of an unexpected adverse event.

关键词： COVID-19 Economic resistance MSMEs South Korea

Highly flexible conductive fabrics with hierarchically nanostructured amorphous nickel tungsten tetraoxide for enhanced electrochemical energy storage

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Nano Research 2015年第12期8卷 3749-3763页

作者： Goli Nagaraju Ramesh Kakarla Sung Min cha Jae Su Yu Department of Electronics and Radio Engineering Institute for Wearable Convergence Electronics Kyung Hee University 1 Seocheon-dong Giheung-gu Yongin-si Gyeonggi-do 446-701 Republic of Korea Department of Environmental Science and Engineering Kyung Hee University 1Seocheon-dong Giheung-gu Yongin-si Gyeonggido 446-701 Republic of Korea

Amorphous nickel tungsten tetraoxide （NiWO4） nanostructures （NSs） were successfully synthesized on a flexible conductive fabric （CF） using a facile one- step electrochemical deposition （ED） method. With an applied external cathodic voltage （-1.8 V for 15 min）, the amorphous NiWO4 NSs with burl-like morphologies adhered well on the seed-coated CF substrate. The burMike amorphous NiWO4 NSs on CF （NiWO4 NSs/CF） are employed as a flexible and binder-free electrode for pseudocapacitors, which exhibit remarkable electrochemical properties with high specific capacitance （1,190.2 F/g at 2 A/g）, excellent cyclic stability （92% at 10 A/g）, and good rate capability （765.7 F/g at 20 A/g） in 1 M KOH electrolyte solution. The superior electrochemical properties can be ascribed to the hierarchical structure and large specific surface area of the burl-like amorphous NiWO4 NSs/CF. This cost-effective facile method for the synthesis of metal tungsten tetraoxide nanomaterials on a flexible CF could be promising for advanced electronic and energy storage device applications.

关键词： amorphous NiWO4 nanostructures conductive fabrics electrochemical deposition electrochemical energystorage properties

Parametric design of a part with free-form surfaces

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第9期7卷 1530-1534页

作者： KIM Yeoung-il KIM Li-ra JUN cha-soo Reseach Institute for CAD/CAM CITEK System Changwon 641-845 Korea School of Industrial and Systems Engineering Gyeongsang National University Jinju 660-701 Korea Research Center for Aircraft Parts Technology School of Industrial and Systems Engineering Gyeongsang National University Jinju 660-701 Korea

3D solid models for parts with regular-form surfaces (PRFSs) are effectively generated using traditional parametric design techniques. A new model is obtained by changing some parameters defining the model. The parts with free-form surfaces (PFFSs), however, cannot be defined by several parameters. Usually they are defined by some geometric elements like profile curves. The traditional parametric design approaches have not easily dealt with the PFFSs. A method for generating a solid model and an engineering drawing for PFFSs is proposed in this paper: First, the new profiles are generated from input point data. Second, the profile information is extracted from the existing model. Last, the old profiles are replaced with the new profiles. This method can preserve the associative information of the existing model and automatically generate the drawing including views, dimen- sions, and annotations. The proposed method has been implemented using a commercial CAD/CAM system, Unigraphics, and API functions written in C-language, and were applied to the blades of a turbine generator. Some illustrative examples are pro- vided in order to show the effectiveness of the proposed method.

关键词： Parametric modelling Free-form surface Solid model Drawing

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压力对微藻生长及固碳效果的影响

环境科学学报 2024年第10期44卷 227-234页

作者：严鹿鸣温馨茶建宾薛圣垣张永奎谢通慧自然资源部战略性矿产综合利用工程技术创新中心成都 610041 四川大学化学工程学院制药与生物工程系成都 610065 四川大学化学工程学院制药与生物工程系成都 610065

由于人类活动导致的温室气体排量升高加剧了全球变暖、海洋酸化等不利于生态多样性的进程,其中,二氧化碳占据总排量的70%以上.为减少其对生态环境的影响,必须研究二氧化碳的捕集与储存方法.微藻凭借温和的培养条件、较高的光合作用效率... 详细信息

由于人类活动导致的温室气体排量升高加剧了全球变暖、海洋酸化等不利于生态多样性的进程,其中,二氧化碳占据总排量的70%以上.为减少其对生态环境的影响,必须研究二氧化碳的捕集与储存方法.微藻凭借温和的培养条件、较高的光合作用效率和生物质产率成为生物固碳领域的研究热点.本研究旨在探究达到最大胞外分泌的最佳气压条件,以此为策略提高微藻的碳固定能力.采用密闭、微正压等形式增强培养体系中二氧化碳从气相到液相的传递.结果表明,在1.25 ATM条件下,培养体系中微藻细胞达到了38.4 mg·L-1的最大胞外有机碳分泌浓度.升高气压有利于促进微藻对培养基中无机氮、磷的吸收,培养体系的氮去除率最高达到31.92%,磷去除率最高达到45.00%.本研究结果将为突破微藻固碳的瓶颈提供可能,并推进微藻固碳的工业应用的可行性验证.

关键词：气压微藻密闭培养生物固碳

Recent Progress in Covalent Organic Frameworks(COFs) for Electrocatalysis

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Chinese Journal of Structural Chemistry 2022年第11期41卷 84-99页

作者： cha Li Zining Qiu Hongming Sun Yijie Yang Cheng-Peng Li College of Chemistry Tianjin Key Laboratory of Structure and Performance for Functional MoleculesTianjin Normal UniversityTianjin 300387China

Electrocatalysis provides various technologies for energy storage and conversion,which is an important part of realizing sustainable clean energy for the ***,as emerging porous crystalline polymers,possess high specific surface areas,tunable pore structures,high crystallinity and tailorable *** features endow COFs with abundant active sites and fast electron transport channels,making them potentially efficient *** recent years,COF-based electrocatalysts have been widely developed for hydrogen evolution reaction(HER),hydrogen oxidation reaction(HOR),oxygen evolution reaction(OER),oxygen reduction reaction(ORR),nitrogen reduction reaction(NRR)and carbon dioxide reduction reaction(CO_(2)RR).In this review,design strategies of COF-based electrocatalysts are briefly summarized,including applying COF as supports,introducing active metals in COF,constructing two-dimensional conductive COF,formation of COF-based hybrid and pyrolysis of COF to obtain carbon ***,the recent research progress in COF-derived catalysts for specific electrocatalytic reactions is introduced ***,the outlook and challenges of future applications of COFs in electrocatalysis are highlighted.

关键词： covalent organic frameworks electrocatalyst catalytic performance catalytic kinetics energy conversion

Hyperglycemia and reduced adiposity of streptozotocin-induced diabetic mice are not alleviated by oral benzylamine supplementation

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World Journal of Diabetes 2022年第9期13卷 752-764页

作者： Christian Carpéné Kristiyan Stiliyanov Atanasov Francisco les Josep Mercader Barcelo Institut des Maladies Métaboliques et Cardiovasculaires INSERM UMR 1297Toulouse 31432France Molecular Biology and One Health research group Department of Fundamental Biology and Health SciencesUniversity of the Balearic IslandsPalma 07122Spain Department of Pharmacy Faculty of Health SciencesUniversidad San JorgeVillanueva de GállegoZaragoza 50830Spain

BACKGROUND Benzylamine(Bza)oral administration delays the onset of hyperglycemia in insulin-resistant db-/-mice;a genetic model of obesity and type 2 *** To extend the antihyperglycemic properties of oral benzylamine to a model of insulin-deficient type 1 *** Male Swiss mice were rendered diabetic by streptozotocin treatment(STZ)and divided in two groups:one received 0.5%Bza as drinking solution for 24 d(STZ Bza-drinking)while the other was drinking water ad *** groups were constituted in age-matched,nondiabetic *** intake,liquid intake,body weight gain and nonfasting blood glucose levels were followed during *** the end of treatment,fasted glycemia,liver and white adipose tissue(WAT)mass were measured,while glucose uptake assays were performed in *** STZ diabetic mice presented typical features of insulin-deficient diabetes:reduced body mass and increased blood glucose *** altered parameters were not normalized in the Bza-drinking group in spite of restored food and water *** consumption could not reverse the severe fat depot atrophy of STZ diabetic *** the nondiabetic mice,no difference was found between control and Bza-drinking mice for any *** isolated adipocytes,hexose uptake was partially activated by 0.1 mmol/L Bza in a manner that was obliterated in vitro by the amine oxidase inhibitor phenelzine and that remained unchanged after Bza *** of 0.1 mmol/L Bza in WAT was lower in STZ diabetic than in normoglycemic *** Bza supplementation could not normalize the altered glucose handling of STZ diabetic mice with severe WAT ***,its antidiabetic potential in obese and diabetic rodents does not apply to lipoatrophic type 1 diabetic mice.

关键词： Diabetes Adipocytes Amine oxidases Insulin-like agents Glucose transport Polydipsia

Performance Study of a Hybrid Heat Pump Dryer based on Numerical Analysis and Experimental Set-up

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Journal of Thermal Science 2021年第1期30卷 111-122页

作者： SHAMSUDDEEN Mohamed Murshid cha Dong-An KIM Seon-chang KANEMOTO Toshiaki KIM Jin-Hyuk Industrial Technology Korea University of Science&TechnologyDaejeon 34113Republic of Korea Thermal&Fluid System R&D Group Korea Institute of Industrial TechnologyCheonan 31056Republic of Korea Institute of Ocean Energy Saga UniversityHonjo 1Saga 840-8502Japan

Seafood,especially sea cucumbers and oysters are an expensive delicacy in several Asian *** sun-drying of these products takes 3 to 4 days and fetches a lower market *** industrial drying machines used for seafood drying are unable to dry sea cucumbers and oysters without texture and color degradation as they are delicate,temperature-sensitive and have longer drying *** economical drying system that does not cause texture or color degradation is the heat pump drying system and is commonly applied for agriculture and fabric *** this study,the heat pump technology is applied to develop two hybrid dryer models(bottom discharge and front discharge)to dry shellfish and sea cucumbers in large scale for storage and *** model is tested in a laboratory-scale with wet sponges as input material for its dehumidification capacity and the power consumed to attain the target *** front discharge model is found to have rapid drying capability and *** fluid dynamic tools are used to study the hot air flow behavior and flow uniformity inside the drying *** front discharge model showed smooth uniform flow over the trays with fewer losses in the flow *** front discharge model with higher drying rate,lower power consumption and uniform airflow distribution over the trays is chosen for the industrial-scale design.

关键词： heat pump hybrid dryer CFD drying rate sea cucumber oyster

京津冀及周边地区夏季和初秋气象条件对PM_(2.5)和O_(3)双高影响

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环境科学 2024年第8期45卷 4375-4384页

作者：李博文张凯高健高庆先罗宇骞李迎新任家豪茶志春中国环境科学研究院环境基准与风险评估国家重点实验室北京100012

为了解2021年京津冀及周边地区夏季和初秋的PM_(2.5)和O_(3)的双高特征及气象影响,对京津冀及周边地区PM_(2.5)和O_(3)浓度的时空分布特征以及气象条件、副高指数和天气形势进行了分析.结果表明,2021年6~9月PM_(2.5)浓度和DPO_(3)[O_(3... 详细信息

为了解2021年京津冀及周边地区夏季和初秋的PM_(2.5)和O_(3)的双高特征及气象影响,对京津冀及周边地区PM_(2.5)和O_(3)浓度的时空分布特征以及气象条件、副高指数和天气形势进行了分析.结果表明,2021年6~9月PM_(2.5)浓度和DPO_(3)[O_(3)日最大8 h均值与06:00 O_(3)浓度的差值]与2020年和2022年同期相比都有所降低,浓度高值主要集中在6月;PM_(2.5)浓度和DPO_(3)整体呈现从中部向南北逐渐下降的特征,并具有同步的时空变化特征.PM_(2.5)浓度小时均值呈双峰分布,在07:00~10:00和22:00~24:00达到峰值;O_(3)浓度小时值呈相反的变化趋势,在14:00~16:00达到峰值.高PM_(2.5)浓度和DPO_(3)时近地面气象要素特征表现为气温在24.0~28.0℃,相对湿度在58.4%~76.3%,风速在1.5~3 m·s^(-1).副高指数与DPO_(3)存在滞后相关,当副高离京津冀及周边地区越远且强度越强时,DPO_(3)越高.研究区域PM_(2.5)和O_(3)浓度双高的主要天气形势为近地面低压前部、高压型和锋前型,高空受高压脊控制且副高脊线稳定在21°~28°N.

关键词：臭氧(O_(3)) PM_(2.5) 气象要素天气形势京津冀及周边地区