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Effect of enzyme and mechanical stirring on the degradation of polyaspartic acid hydro-gel

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Progress in Natural Science:Materials International 2015年第5期25卷 425-429页

作者： Jun Wei Mingyuan Xue Chunling Li Hui Cao Tianwei Tan Beijing Key Lab of Bioprocess Beijing University of Chemical Technology

As a biodegradable polymer, polyaspartic acid(PASP) hydro-gel has been applied in various fields. Although the degradation mechanism of PASP was well studied, to our knowledge, limited research has been done on the degradation of PASP hydro-gel, whose main chain was crosslinked. This work mainly focused on the effects of enzyme and mechanical stirring on the structure of the PASP hydro-gel during its *** change of the molecular weight and swelling ratio indicates that the simple mechanical stirring caused a break at the crosslink point of the PASP hydro-gel's spatial reticular structure with IR and SEM characterization, but has no significant effect on the degradation of the main *** the PH value of the degradation system also has little effect on the degradation of the main chain. However, the additions of enzyme both resulted in the break at the crosslink point and the degradation of the main chain, the significant decreases of both the molecular weight and swelling ratio of the PASP hydro-gel were observed.

关键词： Polyaspartic acid Hydro-gel Degradation Enzyme mechanical stirring

Segregation behavior and its regulating process in as-cast magnesium alloy containing heavy rare earth

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Journal of Rare Earths 2022年第8期40卷 1291-1304页

作者： Xin Tong Guoqiang You Fanjin Yao Mahmoud Ebrahimi Xinyue Deng Shokouh Attarilar College of Materials Science and Engineering Chongqing UniversityChongqing 400045China National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400044China Department of mechanical Engineering Faculty of EngineeringUniversity of MaraghehP.O.Box 55136-533MaraghehIran School of Materials Science and Engineering Iran University of Science and TechnologyTehranIran

Specific gravity segregation that occurs during the smelting process always leads to the low composition homogeneity and poor performance stability of the magnesium-rare earth(Mg-RE)*** this study,the segregation behavior of Mg-Gd alloy was investigated by sampling from different locations in the ingot fabricated in a resistance furnace without a pouring *** combined application of induction-heating and mechanical stirring with various speeds(0-130 r/min)was applied to promote the distribution homogeneity of Gd *** the resistance-heating fabricated ingot,Gd content at the bottom section reaches 407%of that at the *** coarse dendrites surrounded by the network-like eutectic structures are responsible for the brittle fracture with a poor elongation of 3.7%.By the combined employment of the induction heating and mechanical stirring with the speed of 87 r/min at 740℃for 40 s,the variation of the Gd content within the whole ingot can be reduced to be the minimum of 0.23 wt%.Corresponding formation and regulating models of segregation were also ***,the cooling rate of the melt is reduced by the continuous increase of the stirring speed to 130 r/min,which results in the grain coarsening and lower homogeneity of the ingot.

关键词： Mg-RE alloy Segregation Composition homogeneity Melting process mechanical stirring Rare earths

Stirred casting Al–Pb monotectic alloys with high damping capacity

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Rare Metals 2015年第8期34卷 560-563页

作者： Di-Qing Wan Key Laboratory of Ministry of Education for Conveyance and Equipment East China Jiaotong University

In this study, the stirred casting with various processing parameters, such as stirring temperature and stirring speeds, was carried out on the Al–Pb monotectic alloys in order to make Pb particles distribute much more uniformly. More importantly, their damping capacities were systematically studied. The results show tha mechanical stirring can not only make Pb in the aluminum matrix uniformly distribute but also dynamically influence the damping capacity of this alloy system. The Al–Pb alloy was prepared under a slow speed at solid–liquid temperature region, wherein high volume fraction of Pb in alloy could be obtained. The high volume fraction of Pb gives high overall damping capacity. The dislocation damping and interface damping theories are mainly dominated to the alloys.

关键词： Al–Pb alloy mechanical stirring Damping capacity

Microstructure Evolution of Semi-solid Processed Hyper-eutectic Al-30%Si Alloy

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International Journal of Minerals,Metallurgy and Materials 1999年第4期13卷 259-261页

作者： Yanjun Li Weimin Mao Xueyou Zhong(Material Science and Engineering School, University of Science and Technology Beijing, Beijing 100083, China) Material Science and Engineering School University of Science and Technology Beijing Beijing 100083 China

An investigation was made on the influences of mechanical stirring on microstructure of hyper-eutectic Al-30%Si alloy (inmass fraction) during solidification. The primary Si crystals formed in the alloy melt were gradually changed from elongated platelets tonear-spherical shapes by mechanical stirring. The spheroidization of primary St crystals occurs by the mechanism of bending and fractureof Si platelets, wear and collision between Si crystals, and coalescence of small Si particles. The influence of under-cooling and coolingrate of the alloy melt on primary Si crystals of semi-solid processed alloys is investigated as well. The increase of under-cooling andcooling rate decreases the size of primary Si crystals.

关键词： semi-solid state process solidification structure mechanical stirring hyper-eutectic Al-Si alloy

Numerical simulation and experimental study on eggshell membrane separation device

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International Journal of Agricultural and Biological Engineering 2019年第2期12卷 173-183页

作者： Yuan Chi Yong Wang Mengfu Li Jie Ren Yujie Chi College of Engineering Northeast Agricultural UniversityHarbin 150030China College of Food Science Northeast Agricultural UniversityHarbin 150030China

In order to provide theoretical guidance for separating egg membrane from eggshell by using mechanical agitation,CFD was used to explore the flow characteristics in stirred tank,using the Sliding Grid method to deal with the impeller rotational velocity zone in flow field,and using the Euler model to deal with liquid-solid two-phase *** study explored the influence of dish-shape bottom or flat-shape bottom,the clearance size between baffle and the side wall,and the axial height of impeller to bottom on suspension state of particles,solids holdup distribution,solid phase velocity and power number by *** results showed that better particles suspension effect in dish-shape tank can reduce particles accumulation at the bottom and power *** there was a small clearance size(S)between the baffle and the side wall of the stirred tank,it would reduce particles accumulation at the bottom,and reduce the power ***,too large S would decrease the suspension height of particles,not only cannot strengthen the main flow,but also lead to most fluid through clearance forming tangential flow,simulation results showed that S=6 mm was *** decreased axial height of impeller(C)to bottom,particles accumulation at the bottom was decreased,but power consumption would increase,simulation results showed that C=H/5(H is height of liquid surface)was *** to the simulation results,the structure of the stirring tank was *** the same time,the influences of stirring rotational velocity,stirring time,solid-liquid ratio and separating medium temperature on egg membrane recovery were also studied by experiment,and optimal parameter combination of factors was *** experiment results showed while the stirring time was 17.1 min,stirring rotational velocity was 350 r/min,solid-liquid ratio was 1:17 g/mL,the separating medium temperature was 32℃,the membrane recovery rate can reach above 89%.The device improves the recovery a

关键词： liquid-solid two-phase flow mechanical stirring field characteristics eggshell membrane separation

Effects of Electromagnetic stirring on Solidification of Metal Foams

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Journal of Iron and Steel Research(International) 2012年第S1期19卷 195-198页

作者： HAO Hai LU Guo-qiang WANG Fu-yun ZHANG Xing-guo School of Materials Science and Engineering Dalian University of Technology

Metal foams are usually used as light structural/functional *** nucleation,evolution and the solidification behavior of the metal foams can be influenced by the stining mode and the foaming *** this paper,the effects of electromagnetic stirring on metal foaming process were *** tests were carried out and the optimized parameters of the stirring modes were *** stirring effects of the spiral electromagnetic field are better than the travelling wave electromagnetic *** effects of the spiral electromagnetic-mechanical combined stirring are better than the situations of the single electromagnetic stirring or the single mechanical stirring.

关键词： Aluminum Foam Cell structure Solidification mechanical stirring Electromagnetic stirring

Gas-Liquid Separation Processes for Mud Logging Systems

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Journal of Geological Resource and Engineering 2021年第2期9卷 29-37页

作者： Daniela Martins Marum Maria Dina Afonso Brian Bernardo Ochoa Baker Hughes Baker-Hughes-strasse-129221 CelleLower SaxonyGermany Universidade de Lisboa Instituto Superior TécnicoCeFEMAAv.Rovisco Pais11049-001 LisbonPortugal

The TRU-Vision system,developed by Baker Hughes,analyzes the gas extracted from drilling mud to estimate the hydrocarbons composition in drilled rock *** separation processes had been surveyed in order to enhance the gas extraction at the gas trap,namely,mechanical stirring,vacuum,air sparging,membrane separation processes,ultrasounds,and *** stirring devices(one propeller,one flat-blade turbine,and two baffles sets),a vacuum generator,and an air bubble generator were designed and assembled to increase the efficiency and the response stability of TRU-Vision system.

关键词： Air sparging gas extraction mechanical stirring mud logging vacuum