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Microstructure and mechanical properties of curved AZ31 magnesium alloy profiles produced by differential velocity sideways extrusion

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Journal of Magnesium and Alloys 2023年第2期11卷 493-508页

作者： Wenbin Zhou Jianguo Lin Trevor A.dean Department of Mechanical Engineering Imperial College LondonLondon SW72AZUK Department of Mechanical Engineering University of BirminghamBirmingham B152TTUK School of Science and Engineering University of DundeeDundee DD14HNUK

Lightweight curved profiles are widely utilised in the transportation industry considering the increasing need for improving aerodynamic efficiency,aesthetics and cutting *** this paper,curved AZ31 Mg alloy profiles were manufactured in one operation by a novel process,differential velocity sideways extrusion(DVSE),in which two opposed rams were *** of extrusion temperature and velocity(strain rate) on curvature,microstructure,and mechanical properties of the formed profiles were *** curvature was found to be more readily controlled by the velocity ratio of the bottom ram v2to the top ram v1,whereas extrusion temperature(T=250,300,350℃)and extrusion velocity(v_(1)=0.1,1 mm/s) slightly affect curvature for a given velocity ratio.A homogeneous microstructure with equiaxed grains(~4.5 μm) resulted from dynamic recrystallisation(DRX),was observed after DVSE(v_(2)/v_(1)=1/2) at 300 ℃ and v_(1)=0.1 mm/s,where the initial billet had an average grain size of ~25 *** extrusion temperature leads to grain growth(~5 μm) at 350 ℃ and v_(1)=0.1 mm/*** is incomplete at the relatively low temperature of 250℃(v_(1)=0.1 mm/s),and higher strain rate with v1=1mm/s(T=300℃),resulting in inhomogeneous bi-modal necklace pattern grains ranging in size around 1-25 μm for the former and 2-20μm for the *** refinement is attributed to DRX during the severe plastic deformation(SPD) arising in DVSE,and initiates at the prior boundaries of coarse grains in a necklace-like *** with the billet,micro-hardness and ultimate tensile strength of the profiles have been enhanced,which is compatible with grain ***,an obvious increase in tensile ductility was ***,yield strength slightly decreases except for the complete DRXed case(300℃,v_(1)=0.1 mm/s),where a slightly higher value was found,indicating strengthening by grain refinement is greater than softening caused by texture *** initial billet had a strong b

关键词： Extrusion Magnesium alloy AZ31 Curved profiles/sections Bending Grain refinement Dynamic recrystallisation

Mechanical and corrosion properties of full liquid phase sintered WE43 magnesium alloy specimens fabricated via binder jetting additive manufacturing

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Journal of Magnesium and Alloys 2024年第7期12卷 2711-2724页

作者： Dae Hyun Cho David dean Alan A.Luo Department of Materials Science and Engineering The Ohio State UniversityColumbusOH 43210USA Department of Plastic and Reconstructive Surgery The Ohio State UniversityColumbusOH 43210USA Department of Integrated Systems Engineering The Ohio State UniversityColumbusOH 43210USA

This study investigates full liquid phase sintering as a process of fabrication parts from WE43(Mg-4wt.%Y-3wt.%RE-0.7wt.%Zr)alloy using binder jetting additive manufacturing(BJAM).This fabrication process is being developed for use in producing structural or biomedical ***,this study focused on achieving a near-dense microstructure with WE43 Mg alloy while substantially reducing the duration of sintering post-processing after BJAM part *** optimal process resulted in microstructure with 2.5%porosity and significantly reduced sintering *** improved sintering can be explained by the presence of Y_(2)O_(3)and Nd_(2)O_(3)oxide layers,which form spontaneously on the surface of WE43 powder used in *** layers appear to be crucial in preventing shape distortion of the resulting samples and in enabling the development of sintering necks,particularly under sintering conditions exceeding the liquidus temperature of WE43 *** WE43 specimens rendered by BJAM achieved significant improvement in both corrosion resistance and mechanical properties through reduced porosity levels related to the sintering time.

关键词： Magnesium alloy Liquid phase sintering Additive manufacturing Binder jetting process Biodegradation

Town-scale microbial sewer community and H2S emissions response to common chemical and biological dosing treatments

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Journal of Environmental Sciences 2020年第1期32卷 133-148页

作者： Elizabeth R.Mathews Jennifer L.Wood dean Phillips Nathan Billington dean Barnett Ashley E.Franks Department of Physiology Anatomy and MicrobiologyLa Trobe UniversityMelbourneAustralia Centre for Future Landscapes La Trobe UniversityMelbourneAustralia Faculty of Science Engineering and TechnologySwinburne University of TechnologyMelbourneAustralia Western Water SunburyAustralia

Controlling hydrogen sulfide(H2S)odors and emissions using a single,effective treatment across a town-scale sewer network is a challenge faced by many water *** of a sewer diversion provided the opportunity to compare the effectiveness of magnesium hydroxide(Mg(OH)2)and two biological dosing compounds(Bioproducts A and B),with different modes of action(MOA),in a field-test across a large sewer ***(OH)2 increases sewer p H allowing suppression of H2S release into the sewer environment while Bioproduct A acts to disrupt microbial communication through quorum sensing(QS),reducing biofilm *** B reduces H2S odors by scouring the sewer of fats,oils and grease(FOGs),which provide adhesion points for the microbial *** revealed that only Mg(OH)2 altered the microbial community structure and reduced H2S emissions in a live sewer system,whilst Bioproducts A and B did not reduce H2S emissions or have an observable effect on the composition of the microbial community at the dosed *** results recommend in situ testing of dosing treatments before implementation across an operational system.

关键词： Microbially induced concrete corrosion Biological dosing treatments Magnesium hydroxide Hydrogen sulfide Sulfate-reducing bacteria Microbial ecology

Brain-derived cell-free DNA

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Neural Regeneration Research 2022年第10期17卷 2213-2214页

作者： dean Southwood Sanyukta Singh Zac Chatterton Brain and Mind Center School of Medical SciencesDepartment of NeuroscienceThe University of SydneyCamperdownNSWAustralia

Following cell death,DNA can be released into the blood plasma and other body fluids in the form of cell-free DNA(cfDNA).These DNA fragments are typically~167 bp in length,corresponding to the length of DNA wrapped around one nucleosome core(147 bp),plus DNA tails that survive endogenous DNase digestion(~10 bp).CfDNA is derived from a variety of sources,each having unique diagnostic *** pregnancy,fetal-derived cfDNA within an expectant mother’s blood plasma can diagnose fetal genetic abnormalities and is a well-established method for non-invasive prenatal ***-derived cfDNA is also detectable within blood plasma by high sensitivity methods(e.g.,NGS,ddPCR)and can accurately diagnose cancers by a minimally invasive blood test(Diehl et al.,2008).The short half-life of cfDNA(<2 hours)also facilitates real-time measurement of disease burden,such as monitoring cancer *** is now growing evidence of brain-derived cfDNA(bd-cfDNA)within the cerebrospinal fluid(CSF)and blood *** this perspective,we review the present understanding,current challenges,and potential utility of bd-cfDNA.

关键词： fetal mother endogenous

Experimental research on the mechanism of non-monotonic characteristic between curing temperature and mechanical behaviors of Kevlar/epoxy composite

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Science China(Technological Sciences) 2018年第7期61卷 1012-1020页

作者： LIU Li HU dean ZHANG YouMin HAN Xu State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Key Laboratory of Advanced Design and Simulation Technology for Special Equipments Ministry of Education Hunan University School of Mechanical Engineering Hebei University of Technology

An experimental procedure is conducted to investigate the mechanism of the non-monotonic characteristic between curing temperature and mechanical behaviors of the Kevlar/epoxy composite in macro and micro levels. Different specimens are fabricated at four different curing temperatures and tested with ±45° off-axis tensile loading on a universal test machine coupled with digital image correlation(DIC). Moreover, the environmental scanning electron microscope(SEM) was used to obtain the micrographs and reveal their mechanism. The tested results show that the tensile mechanical behaviors are sensitive to the curing temperature and the relationship is non-monotonic. Also, as the temperature increases, the thicknesses of the specimens are significantly enlarged. By analyzing the SEM micrographs of the matrix grooves in the damage zone and DIC strain contours, it is concluded that the non-monotonic relationship is dominated by the properties of the Kevlar/epoxy interfaces and deformation of the distorted fibers.

关键词： Kevlar/epoxy composite mechanical behavior digital image correlation SEM micrograph non-monotonic character-istic distorted fiber

Prediction of the Residual Welding Stress in 2.25Cr-1Mo Steel by Taking into Account the Effect of the Solid-State Phase Transformations

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Acta Metallurgica Sinica(English Letters) 2013年第3期26卷 333-339页

作者： dean DENG Yangang TONG Ninshu MA Hidekazu MURAKAWA College of Materials Science and Engineering Chongqing University State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology JWRI Osaka University11-1 MihogaokaIbaraki Osaka 567-0047 Japan

A computational approach based on the thermal elastic plastic finite element method was developed for predicting welding residual stress in low carbon alloyed steel welds by taking into account the effect of the solid-state phase transformations. The kinetics of phase transformations was described by Johnson Mehl Avrami Kolmogrov （JMAK） equation for bainitic transition and by Koistinen-Marburger （K-M） relationship for martensitic transition. Moreover, an additive rule depending on volumetric phase fraction was adopted to represent the material property changes during heating and cooling. Consequently, the residual welding stresses in a 2.25Cr1Mo steel TIG welded plate were computed. Early calculation results suggest that the bainitic and martensitic transformations took place in the weld the heat-affected zone drastically reduce the residual longitudinal tensile stress in the region.

关键词： Computational approach Numerical simulation Phase transformation Welding residual stress

Investigation of mechanical and electrical characteristics of selfsensing pneumatic torsional actuators

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Science China(Technological Sciences) 2024年第1期67卷 130-142页

作者： XIAO Wei HU dean HU GuoLiang XIAO YiHua Key Laboratory of Conveyance and Equipment Ministry of EducationEast China Jiaotong UniversityNanchang 330013China Key Laboratory of Advanced Design and Simulation Techniques for Special Equipment Ministry of EducationHunan UniversityChangsha 410082China

Soft pneumatic actuators are one of the most promising actuation for soft robots,and great achievements have been *** it remains challenging to endow sensing capabilities to pneumatic actuators,especially for the sensing ability originating directly from the actuator ***,a self-sensing pneumatic torsional actuator(SPTA)is designed based on the electromagnetic induction effect and magnetically responsive *** SPTA can generate feedback voltage and current with the deformation,in which the sensing function comes from its inherent *** investigate the mechanical and electrical characteristics,an experimental platform and a finite element model are established,*** find that the torsion angle and output torque increase in nonlinear with the actuating *** maximum torsion angle is 66.35°,which is 84.34%of that for the actuator fabricated by pure *** maximum output torque(24.9 N mm)improves by 23.19%compared with the actuator made by pure *** regards the electrical characteristics,the maximum feedback voltage and current are 2.90μV and 29.50 nA when the SPTA is actuated by a pressure of−40 *** also demonstrate that the relationship between the torsion angle and the magnetic flux change is approximately ***,the number of turns of wires,magnetic powders contents,and magnetic direction on the feedback voltage and current are *** show that the feedback voltage and current can be enhanced by increasing the number of turns and magnetic powders *** envision that the SPTA would be promising for soft robots to realize their accuracy control and intelligentization.

关键词： pneumatic torsional actuators self-sensing feedback voltage finite element modeling soft robots

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System control-mediated drug delivery towards complex systems via nanodiamond carriers

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International Journal of Smart and Nano Materials 2010年第1期1卷 69-81页

作者： dean Ho Chih-Ming Ho Department of Biomedical Engineering Department of Mechanical Engineering Northwestern UniversityEvanstonIL 60208USA Robert H.Lurie Comprehensive Cancer Center Northwestern UniversityChicagoIL 60611USA Department of Mechanical and Aerospace Engineering University of CaliforniaLos AngelesLACA 90095USA Center for Cell Control A NIH Nanomedicine Development CenterLos AngelesCA 90095USA

Cells represent the basic units of life and contain an intertwined network of signaling and regulatory circuitries that drive the processes of *** processes include the mediation of mechano-sensation,onset of and protection against disease,inflammation,and *** the network of bio-complex systems,each pathway interacts nonlinearly with others through different molecular *** a result,specific functionalities can not be simply linked to the cellular molecules in isolation.A complex system generally possesses very rich information content that can be characterized by the following features:(i)they contain a large number of building blocks;(ii)their interactions among building blocks and with their environment;(iii)they display organization without an external organizing principle being applied;and(iv)they exhibit adaptability and *** properties account for the innate intelligence of biology and its ability to regulate its homeostatic ***,this same complexity underlies,in cancer for example,challenges towards disease management,as the addressing of singular pathways with therapeutic compounds is not ***,combinatorial therapy often serves as a key strategy towards tumor *** iterative searching for optimized therapeutic combinations is indeed a daunting,if not preclusive task,we introduce the feedback system control(FSC)scheme,which may serve as a clinically relevant approach,provided a translational approach towards drug delivery is *** to their innate biocompatibility,which has been comprehensively observed,as well as their ability to delivery virtually any type of therapeutic in a sustained fashion due to their unique surface properties,nanodiamonds may serve as a foundation for nanoenabled combinatorial therapy.

关键词： bio-complex system feedback system control drug delivery,nanodiamond combinatorial medicine signaling network nanomedicine

Pseudo feature point registration of pavement images

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Journal of Traffic and Transportation Engineering(English Edition) 2018年第4期5卷 254-267页

作者： dean Wright Ginger Lehmann UK Leamington Spa CV31 1PR UK

Over the last 20 years road pavement imaging has become a routine output from annual pavement assessment survey regimes across the world. Hitherto the traditional use of road pavement images in road condition assessment has been crack detection, rather than direct analysis of image features such as aggregate loss, changes in surface texture or deterioration of road markings. Any attempt to assess pavement condition change from features in a sequence of such images captured months or years apart requires image registration. A method for registering road pavement images is presented that makes use of an affine transformation based on pseudo-features within images. An affine trans- formation is considered suitable for registering road pavement images because of the linear way in which pavements are surveyed. Pseudo feature points are found using a modified corner detector, and then matching points between reference and template im- ages established via a correlation analysis of pavement image texture. With 4 such points it is possible to establish an affine transformation between the images. The method is tested on pavement images captured on three UK sites between winter 2014/15 and 2015/16. The method successfully registered 98% of images captured on sites typical of the UK＇s strategic road network, and 65% of images captured on a site typical of the UK＇s minor road network.

关键词： Pavement engineering Pavement texture Image registration Pseudo feature point