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A comparative study on Sn macrosegregation behavior of ternary Al-Sn-Cu alloys prepared by gravity casting and squeeze casting

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China Foundry 2023年第1期20卷 63-70页

作者： ming xu yan-guo Yin cong-min Li cong-chong Duan College of Mechanical Engineering Hefei University of TechnologyHefei 230002China Anhui Yihui New Materials Co. Ltd.Hefei 230000China

A comprehensive study on Sn macrosegregation behavior in ternary Al-Sn-Cu alloys was carried out by comparative analysis between gravity casting and squeeze casting *** microstructure and Sn distribution of the castings were characterized by metallography,scanning electron microscopy(SEM),energy-dispersive X-ray(EDX)spectroscopy,and a direct reading *** show that there are obvious differences in Sn morphology between gravity casting and squeeze casting *** squeeze casting condition,the grain size of the casting is smaller and the distribution ofβ(Sn)is *** effectively reduces the segregation of triangular grain boundary as well as the segregation of *** segregation types of Sn in gravity casting and squeeze casting samples are obviously *** upper surfaces of gravity casting samples show severe negative segregation,while all the lower surfaces have positive *** with gravity casting,squeeze casting solidifies under isostatic *** to the direct contact between the upper surface of the casting and the mold,the casting solidifies faster under higher undercooling degree and ***,the uniform distribution of Sn reduces the segregation phenomenon on the surface of the casting.

关键词： ternary Al-Sn-Cu alloy squeeze casting macrosegregation mechanism

Effects of macrosegregation on mechanical and tribological properties of squeeze casting immiscible bearing alloys

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China Foundry 2023年第5期20卷 443-451页

作者： ming xu yan-guo Yin cong-min Li Guo-tao Zhang cong-chong Duan Institute of Tribology School of Mechanical EngineeringHefei University of TechnologyHefei 230002China School of Mechanical Engineering Anhui University of TechnologyMaanshan 243002AnhuiChina Anhui Yihui New Material Co. Ltd.Hefei 230000China

The macrosegregation behaviors of Al-Sn-Cu ternary immiscible alloy castings and their effects on mechanical and tribological properties were *** results demonstrate that Sn and Cu segregate in the casting simultaneously,and the mass fraction of the two elements has a"U"shaped ***,positive and negative segregation occur in the casting,with positive segregation appearing on the top and lower surfaces and negative segregation on the remaining surfaces,with the 1/2 surface(hot node location)having the highest degree of negative ***,the results of Vickers hardness,tensile strength,and elongation show that Sn and Cu cooperatively affect the mechanical properties of *** higher the mass fraction of Sn and Cu elements,the higher the hardness,the greater the tensile strength,and the better the *** findings of the step-by-step loading tests demonstrate that the segregation of Sn and Cu significantly impacts the tribological characteristics of the *** higher the mass fraction of Sn and Cu on the sample surface,the better the tribological characteristics.

关键词： squeeze casting Al-Sn-Cu macrosegregation mechanical properties tribological property

Effect of Phase Separation Size on the Properties of Self-healing Elastomer

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Chinese Journal of Polymer Science 2024年第6期42卷 798-804页

作者： Jun xu Lei zhu Xian-Qi Feng cong Sui Wen-Peng Zhao Shou-Ke yan School of Chemical Engineering Qingdao University of Science&TechnologyQingdao266042China College of Engineering Yanching institute of TechnologyLangfang065210China Key Laboratory of Rubber-plastics Qingdao University of Science&TechnologyQingdao266042China State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing100029China

Regulation of phase structure has been recognized as one of the most effective ways to fabricate self-healing polymers with high mechanical *** mechanical properties of the resultant polymers are certainly affected by the size of separated phase ***,the study on this aspect is absence,because it can hardly exclude the influence of variation in monomer proportion required for tuning the separated phase ***,we report the first study on tuning the phase size through reversible addition-fragmentation chain transfer(RAFT)polymerization without changing the proportion of *** expected,the size of separated phase has been successfully mediated from 15 nm to 9 nm by tuning the molecular weight of the chain transfer *** is found that the mechanical strength and the self-healing efficiency of the resultant polymers increase simultaneously with the decrease of phase *** study on the formation kinetics of hydrogen bonds reveals that the decrease of phase size can facilitate the re-bonding rate of hydrogen bonds,even if the migration of polymer chains is restricted.

关键词： Self-healing polymers Phase separation Reversible addition-fragmentation chain transfer

Effects of Standard Tai Chi on Exercise Capacity and Mental Health in Exercise-deprived Overweight/Obese Adults and Assessment of Participant Adherence

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Chinese Journal of Integrative Medicine 2024年第12期30卷 1068-1079页

作者： TAO zhu xu Zi-ming GUO yan YU Hui-yong General department Xiyuan Hospital Affiliated to China Academy of Chinese Medical SciencesBeijing 100091China Chinese Journal of Integrated Traditional and Western Medicine Press Beijing 100091China Infectious Diseases department Third Affiliated HospitalBeijing University of Chinese MedicineBeijing 100029China

Objective:To explore the effects of Tai Chi on body mass index(BMI),exercise capacity,and mental health of overweight/obese adults,and investigate factors influencing adherence to enhance adherence of Tai Chi as a sustainable exercise ***:A randomized,controlled,exploratory clinical trial was conducted paired with a qualitative study of adherence management.A total of 20 overweight/obese participants were randomly assigned to a standard Tai Chi group(experimental)and a simplified Tai Chi group(control)for an 8-week intervention,10 patients in each group,with a 12-month *** was calculated and exercise capacity including an isokinetic muscle strength and balance ability test were *** health was assessed using the General Well-Being Schedule(GWB),Pittsburgh Sleep Quality Index(PSQI),and Coping Self Efficacy Scale(CSES)at baseline,4th week,and 8th week,*** qualitative research included open-interviews with Tai Chi practitioners and semi-structured interviews with ***:The intervention was conducted in Haidian Park,Beijing,China from October 6,2022,to January 1,2023,without *** an 8-week intervention,the participants in the experimental group exhibited a significant decrease in BMI(Pdemonstrated significant improvements in exercise capacity(Pdentified 15 themes,the top 3 themes mentioned were as follows:mind-body effects,online and on-site guidance,training schedule(for subjects);mind-body effects,difficulties in practicing,and understanding of Tai Chi(for practitioners).Conclusions:Both interventions were effective in

关键词： STai Chi overweight obesity exercise capacity mental health adherence interview

development of a masticatory robot using a novel cable-driven linear actuator with bidirectional motion

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Frontiers of Mechanical Engineering 2022年第4期17卷 53-65页

作者： Haiying WEN Jianxiong zhu Hui ZHANG Min DAI Bin LI Zhisheng ZHANG Weiliang xu ming cong School of Mechanical Engineering Southeast UniversityNanjing 211189China Engineering Research Center of New Light Sources Technology and Equipment Ministry of EducationNanjing 210009China department of Stomatology Zhongda Hospital Affiliated to Southeast UniversityNanjing 210009China department of Mechanical&Mechatronics Engineering The University of AucklandAuckland 1142New Zealand School of Mechanical Engineering Dalian University of TechnologyDalian 116024China

Masticatory robots are an effective in vitro performance testing device for dental material and mandibular prostheses.A cable-driven linear actuator(CDLA)capable of bidirectional motion is proposed in this study to design a masticatory robot that can achieve increasingly human-like chewing *** CDLA presents remarkable advantages,such as lightweight and high stiffness structure,in using cable amplification and pulley *** work also exploits the proposed CDLA and designs a masticatory robot called Southeast University masticatory robot(SMAR)to solve existing problems,such as bulky driving linkage and position change of the muscle’s *** analysis and performance experiment validate the CDLA’s efficiency,with its stiffness reaching 1379.6 N/mm(number of cable parts n=4),which is 21.4 times the input wire ***,the CDLA’s force transmission efficiencies in two directions are 84.5%and 85.9%.Chewing experiments are carried out on the developed masticatory robot to verify whether the CDLA can help SMAR achieve a natural human-like chewing motion and sufficient chewing forces for potential applications in performance tests of dental materials or prostheses.

关键词： masticatory robot cable-driven linear actuator parallel robot stiffness analysis

Experimental study on rehydration conditions of freeze-dried platelets

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第5期10卷 697-703页

作者： Ju-li FAN Xian-guo xu Shao-zhi ZHANG Fa-ming zhu Guang-ming CHEN Li-xing yan Institute of Refrigeration and Cryogenics Zhejiang Universit Hangzhou 310027 China Key Laboratory of Blood Safety Research Ministry of Health Blood Center of Zhejiang Province Hangzhou 310006 China

A rehydration process for freeze-dried human platelets was studied on 1 ml of samples. The effects of prehydration duration, prehydration temperature, an rehydration solution on the recovery rate, mean platelet volume （MPV）, and platelet distribution width （PDW） were investigated. The mass changes during the prehydration process were also studied. Three prehydration durations： 0, 1.5, and 3.5 h, and two rehydration solutions： platelet-poor plasma and phosphate-buffered saline （PBS）, were tested. It was found that：（1） the prehydration was of significance; （2） 1.5 h of prehydration had better effects than 3.5 h of prehydration; （3） as a rehydration solution, the platelet-poor plasma behaved better than the PBS. The impacts of prehydration duration and temperature on the results were studied. There was almost no difference between 35 and 37 ℃. Among all the prehydration durations tested, 15, 30, 60, 90, and 120 min, the best result was achieved with the time duration of 15 min. The weights of prehydrated platelets at the end of each test were measured and the water contents were calculated. After 15 min ofprehydration, the water contents in the samples were about （4.8±0.01）% and （5.27±0.29）% （w/w） corresponding to the conditions of 35 and 37 ℃, respectively. These results will be helpful for further studies on the freeze-drying of mammalian cells.

关键词： Freeze-drying Platelets Rehydration Prehydration Rehydration solution

Microstructure and magnetic properties of anisotropic hot-deformed magnet of different magnetic particle sizes

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Rare Metals 2015年第4期34卷 255-258页

作者： xu-Chao Wang ming-Gang zhu Wei Li yan-Feng Li Bin Lai An Du Division of Functional Materials Research Central Iron & Steel Research Institute College of Sciences Northeastern University

In this paper, the magnetic Nd-Fe-B particles of different sizes were conducted under vacuum by the hot pressing, then cooled quickly to room temperature. Finally hot deformation was performed to get the anisotropy Nd-Fe- B magnet at a deformation rate of 70 % in the protection of argon atmosphere. NIM-2000 was used for the measurement of hysteresis loop of the samples. Meanwhile, scanning electron microscopy （SEM） was used to observe the surface morphology of the magnetic particles with different sizes and hot-deformed magnets, energy spectrum analyzer to analyze the composition of magnetic particles. The effect of magnetic particle sizes on the microstructure and magnetic properties of the hot-deformed anisotropic magnet was investigated. Anisotropic hot-deformed magnets produced from the maximum particle size of 200-350 μm have the highest magnetic properties of Br = 1.465 T, Hcj = 1,157 kA.m-1, （Bn）max = 425 kJ.m-3.

关键词： Magnetic property Hot-deformed magnet Magnetic particle Size

Effect of temperature and reaction path interaction on fluidization reduction kinetics of iron ore powder

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Journal of Iron and Steel Research International 2024年第8期31卷 1840-1849页

作者： Guo-min zhu ming-wei Hu An-nan Dou Jin-yu Huang Jing Ding Qi-yan xu School of Metallurgical Engineering Anhui University of TechnologyMa'anshan 243002AnhuiChina

Due to the instability of FeO at temperatures below 843 K,the fuidization reduction pathway of iron ore powder changes with the reduction ***,the effect of temperature and reaction pathway interaction on the kinetics of fuidization reduction of iron ore powder under low-temperature conditions ranging from 783 to 903 K was investigated to describe the fluidization reduction rate of iron ore powder from three aspects:microstructure change,reaction limiting link,and apparent activation energy of the reaction,exploring their internal *** experimental results revealed that in a temperature range of 783-813 K,the formation of a dense iron layer hindered the internal diffusion of reducing gas,resulting in relatively high gas diffusion *** addition,due to the differences in limiting links and reaction pathways in the intermediate stage of reduction,the apparent activation energy of the reaction *** apparent activation energy of the reaction ranged from 23.36 to 89.13 kJ/mol at temperature ranging from 783 to 813 K,while it ranged from 14.30 to 68.34 kJ/mol at temperature ranging from 873 to 903 K.

关键词： Reaction limiting link Gas internal diffusion Interface reaction Apparent activation energy Iron ore powder Reaction pathway Fluidization reduction

Stimulation impact of electric currents on heterotrophic denitrifying microbial viability and denitrification performance in high concentration nitrate-contaminated wastewater

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Journal of Environmental Sciences 2019年第3期31卷 363-371页

作者： Shuang Tong Hengyuan Liu Chuanping Feng Nan Chen yan Zhao Baocai xu Jiamin Zhao ming zhu Beijing Key Laboratory of Meat Processing Technology China Meat Research Center School of Food and Chemical Engineering Beijing Technology and Business University School of Water Resources and Environment China University of Geosciences (Beijing)

Electric current stimulation has been shown to have a positive influence on heterotrophic denitrifying microbial viability and has the potential to improve wastewater denitrification performance. This study investigated the effects of varying current densities on microbial activity and NO_3^- removal efficiency under heterotrophic ***_3^-removal rate was highest at an applied current density of 400 mA/m^2. However, the optimum removal efficiency of total inorganic nitrogen(TIN; 99%) was achieved when the current density was fixed at 200 m A/m^2. Accumulation of NH_4^+-N and NO_2^--N byproducts were also minimized at this current density. The activity of heterotrophic denitrifying microorganisms was much higher at both 200 and 400 mA/m^2. Moreover, the average adenosine-5′-triphosphate(ATP)content(an indicator of cell metabolism) at a current density of 1600 mA/m^2 was lower than that under no current, indicating heterotrophic denitrifying microbial activity can be inhibited at high current densities. Hence, direct electrical stimulation on the activity of heterotrophic denitrifying microorganisms in the developed system should be lower than 1600 mA/m^2. This study improves the understanding of electric current influence on heterotrophic denitrifying microorganisms and promotes the intelligent application of direct electrical stimulation on wastewater treatment processes.

关键词： Direct electrical stimulation Nitrate removal denitrification Heterotrophic microbial activity Current density Wastewater treatment