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Abnormal mechanochemical effect in ultraprecision machining of an additively manufactured precipitation-strengthened high-entropy alloy

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Journal of Materials Science & Technology 2024年第3期170卷 221-237页

作者： Long Xu Yuchao Bai Yunfa Guo Chang ren Xiaohua tan Yandong Jia Gang Wang hao Wang Institute of Materials Shanghai UniversityShanghai 200444China Zhejiang Institute of Advanced Materials Shanghai UniversityJiashan 314100China Department of Mechanical Engineering National University of SingaporeSingapore 117575Singapore

Recently,researchers have explored the use of precipitation strengthening and finer microstructures with high-density dislocations in additive manufacturing to produce high-entropy alloys(HEAs)with adjustable ***,the inherent surface roughness and lack of machinability research in AMed HEAs limit their engineering *** this study,we systematically investigated the microstructural characteristics,mechanical properties,and machinability of Fe_(29.3)Co_(28.7)Ni_(28.6)Al_(6.8)Ti_(6.6)(at.%)HEAs with three different structures:single FCC phase cellular(SPC),dual precipitation-strengthened(DPS),and single precipitation-strengthened(SPS).These structures were fabricated by selective laser melting and isothermally annealing at 780 and 940℃.Compared to SPC HEA,DPS HEA exhibits a significant increase in yield strength and ultimate tensile strength but with a dramatic sacrifice in *** HEA exhibits similar mechanical properties to SPC HEA due to the pronounced coarsening of L21 *** ultraprecision machining micro-cutting test showed that SPC HEA had a significant mechanochem-ical effect,as evidenced by a sharp drop in cutting force for inked workpieces,but not DPS *** abnormal finding was that the negligible reflection of cutting force for SPS HEAs suggested a negative mechanochemical effect,even though SPS HEA had equally excellent plasticity like SPC *** was found that nanocrystallization-induced strength enhancement and ductility reduction of SPS HEA lead to chips’deformation dominated by shear avalanche rather than chip folding of SPC HEA,which involves the reduction of surface energy and friction of chips’***,these results and our research findings may guide the machining of AMed precipitation-strengthened HEAs and accelerate their engineering ap-plication.

关键词： High-entropy alloy Selective laser melting Precipitation strengthening Machinability Mechanochemical effect

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Dynamic mechanical characteristics of deep Jinping marble in complex stress environments

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 630-644页

作者： Chendi Lou Heping Xie Ru Zhang Hai ren hao Luo Kun Xiao Yuan Peng Qiang tan Li ren Institute for Disaster Management and Reconstruction Sichuan UniversityChengdu610207China College of Water Resource&Hydropower Sichuan UniversityChengdu610065China MOE Key Laboratory of Deep Earth Science&Engineering Sichuan UniversityChengdu610065China Yalong River Hydropower Development Company Ltd.Chengdu610051China (Chongqing)International Engineering Technology Company Ltd.Chongqing401121China

To reveal the dynamic mechanical characteristics of deep rocks,a series of impact tests under triaxial static stress states corresponding to depths of 300-2400 m were *** results showed that both the strain rates and the stress environments in depth significantly affect the mechanical characteristics of *** sensitivity of strain rate to the dynamic strength and deformation modulus shows a negative correlation with depth,indicating that producing penetrative cracks in deep environments is more difficult when damage *** dynamic strength shows a tendency to decrease and then increase slightly,but decreases sharply *** demonstrates a similar trend as that of strength,whereas reflectivity indicates the opposite ***,two critical depths with high dynamically induced hazard possibilities based on the China Jinping Underground Laboratory(CJPL)were proposed for deep *** first critical depth is 600-900 m,beyond which the sensitivity of rock dynamic characteristics to the strain rate and restraint of circumferential stress decrease,causing instability of surrounding rocks under axial stress *** second one lies at 1500-1800 m,where the wave impedance and dynamic strength of deep surrounding rocks drop sharply,and the dissipation energy presents a negative *** suggests that the dynamic instability of deep surrounding rocks can be divided into dynamic load dominant and dynamic load induced types,depending on the second critical depth.

关键词： Rock mechanics Split-Hopkinson pressure bar Coupled static‒dynamic loading Different depths Holmquist-Johnson-Cook(HJC)model

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Polyelectrolyte Complexes and Coacervates Formed by De novo-Designed Peptides and Oligonucleotide

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Chinese Journal of Polymer Science 2024年第9期42卷 1333-1340,I0007页

作者： Tian-hao ren De-Hai Liang Beijing National Laboratory for Molecular Sciences Department of Polymer Science and Engineering and the Key Laboratory of Polymer Chemistry and Physics of the Ministry of EducationCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China

The liquid-liquid phase separation of biopolymers in living cells contains multiple interactions and occurs in a dynamic *** the regulation mechanism is still a *** this work,we designed a series of peptides(XXLY)_(6)SSSGSS and studied their complexation and coacervation behavior with single-stranded ***“X”and“Y”are varied to combine known amounts of charged and non-charged amino acids,together with the introduction of secondary structures and pH *** show that the electrostatic interaction,which is described as charge density,controls both the strength of complexation and the degree of chain relaxation,and thus determines the growth and size of the *** hydrophobic interaction is prominent when the charges are ***,the secondary structures of peptides exhibit profound effect on the morphology of the phases,such as solid phase to liquid phase *** study gains insight into the phase separation under physiological *** is also helpful to create coacervates with desirable structures and functions.

关键词： Polyelectrolyte complex Coacervate Peptides Secondary structure Electrostatic interaction

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Surfactant-assisted crystallization of lysozyme and its mechanism

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Particuology 2024年第7期90卷 199-208页

作者： Yujie Song Rongfei ren Min Su Zhihan Liang Qi hao School of Chemical Engineering Hebei University of TechnologyTianjin 300130China

Surfactants were used to assist in the crystallization of *** types of surfactants with different structures(sodium dodecyl sulfate,cetyltrimethylammonium bromide,or betaine hydrochloride[BH])were *** study indicated that three surfactants were all capable of shortening the crystallization induction time of lysozyme,with BH inducing the shortest crystallization induction time(t=1 min)and the largest crystal size(37μm).The molecular interactions among each of the three surfactants aforementioned and lysozyme were also investigated by *** was found that hydrogen bonding dominantly acted between the carboxyl structure of the surfactant BH and the lysozyme,which produced the most favorable conformation for the self-assembly of lysozyme(promote lysozyme orderly aggregation and shorten the crystallization induction time).On this basis,the mechanism of surfactant-promoted lysozyme crystallization was proposed.

关键词： Protein Crystallization Surfactant Lysozyme Molecular interaction Mechanism

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Reinforcement Learning-Based Dynamic Order Recommendation for On-Demand Food Delivery

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Tsinghua Science and Technology 2024年第2期29卷 356-367页

作者： Xing Wang Ling Wang Chenxin Dong hao ren Ke Xing Department of Automation Tsinghua UniversityBeijing 100080China School of Mechanical and Automotive Engineering Qingdao Hengxing University of Science and TechnologyQingdao 266100China Meituan Beijing 100015China

On-demand food delivery(OFD)is gaining more and more popularity in modern *** a kernel order assignment manner in OFD scenario,order recommendation directly influences the delivery efficiency of the platform and the delivery experience of *** paper addresses the dynamism of the order recommendation problem and proposes a reinforcement learning solution *** actor-critic network based on long short term memory(LSTM)unit is designed to deal with the order-grabbing conflict between different ***,three rider sequencing rules are accordingly proposed to match different time steps of the LSTM unit with different *** test the performance of the proposed method,extensive experiments are conducted based on real data from Meituan delivery *** results demonstrate that the proposed reinforcement learning based order recommendation method can significantly increase the number of grabbed orders and reduce the number of order-grabbing conflicts,resulting in better delivery efficiency and experience for the platform and riders.

关键词： on-demand food delivery order recommendation reinforcement learning actor-critic network long short term memory

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Experimental Study on Vortex-Induced Vibration of Rough Risers Coupling with Interference Effect in tandem Arrangement

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China Ocean Engineering 2024年第3期38卷 394-407页

作者： HU Ze-bo LIU Zhen LI Peng GUO Hai-yan ren Xiao-hui HOU hao hao Lian-hong College of Civil Engineering and Architecture Shandong University of Science and TechnologyQingdao 266590China Qingdao Key Laboratory of Marine Civil Engineering Materials and Structures Qingdao 266590China College of Engineering Ocean University of ChinaQingdao 266100China

In order to study the response law of vortex-induced vibration(VIV)of marine risers under the combined action of roughness and interference effects,and to reveal the coupling mechanism of roughness and interference effects on the riser,a VIV experiment of rough risers in tandem arrangement was conducted in a wave−current combined *** experiment characterized the risers’roughness by arranging different specifications of attachments on the surface of the *** rough risers with different roughness and smooth risers were arranged in tandem arrangement,with the rough risers arranged *** experimental results indicate that the suppression of the attachments on the downstream risers’vibration are more significant both in the CF and IL directions as the reduced velocity *** the downstream riser,the amplitude response of rough riser is more significantly weakened compared with the smooth one at high reduced *** the upstream risers,changes in the roughness and spacing ratio have an impact on their‘lock-in’*** the roughness of downstream risers is relatively large(0.1300)and the spacing between risers is small(S/D=4.0),the reduced velocity range of‘lock-in’region in the CF direction of upstream risers is obviously expanded,and the displacement in the‘lock-in’region is severer.

关键词： marine riser vortex-induced vibration tandem arrangement roughness interference effect

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Rational design of new in situ reduction of Ni(II)catalytic system for low-cost and large-scale preparation of porous aromatic frameworks

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Carbon Energy 2024年第5期6卷 105-113页

作者： Shanshan Wang Yue Wu Wenxiang Zhang hao ren Guangshan Zhu Heping Ma School of Chemical Engineering and Technology Xi'an Jiaotong UniversityXi'anChina State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of ChemistryJilin UniversityChangchunChina College of Chemistry Northeast Normal UniversityChangchunChina

Porous aromatic framework 1(PAF-1)is an extremely representative nanoporous organic framework owing to its high stability and exceptionally high surface ***,the synthesis of PAF-1 is catalyzed by the Ni(COD)2/COD/bpy system,suffering from great instability and high ***,we developed an in situ reduction of the Ni(II)catalytic system to synthesize PAF-1 in low cost and high *** active Ni(0)species produced from the NiCl_(2)/bpy/NaI/Mg catalyst system can effectively catalyze homocoupling of tetrakis(4-bromophenyl)methane at the room temperature to form PAF-1 with high Brunauer-Emmett-Teller(BET)-specific surface area up to 4948 m^(2) g^(−1)(Langmuir surface area,6785 m2 g−1).The possible halogen exchange and dehalogenation coupling mechanisms for this new catalytic process in PAF's synthesis are discussed in *** efficiency and universality of this innovative catalyst system have also been demonstrated in other PAFs'*** work provides a cheap,facile,and efficient method for scalable synthesis of PAFs and explores their application for high-pressure storage of Xe and Kr.

关键词： adsorption carbon material nickel catalysis porous aromatic framework porous organic polymer

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Eco-Friendly Encapsulation of Metal Clusters in Porous Organic Cages for Engineerable Microenvironment and Enhanced Catalysis

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CCS Chemistry 2024年第9期6卷 2186-2197页

作者： Siyu ren Liangxiao tan Jun-hao Zhou Jian Sun Peng Zhang Xingzhong Cao Yun-Hong Zhang Jian-Ke Sun MOE Key Laboratory of Cluster Science Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion MaterialsSchool of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 102488 Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049

Developing artificial catalysts that mimic the functionality of enzymes and adapt to the surrounding microenvironment to achieve specific activity and selectivity is a fascinating research area yet remains a great *** this work,we present a meticulously designed strategy for the successful encapsulation of ultrasmall metal clusters(MCs)within an amine-type porous organic cage(POC)through electrostatic complexation,phase transfer,and alcohol reduction *** amine cage showcases an intriguing and customizable feature that allows for the regulation of the surrounding microenvironment of the confined MCs through a feasible postmodifi-cation *** functionalization of cage skeleton further facilitates precise adjustment to the surface electronic state of Pd cluster,thereby influencing the adsorption behavior of ***,this controlled regulation leads to modified activity and chemoselectivity in the catalytic hydrogenation of halogenated ***,the investigation of the correlation between the surrounding microenvironment,substrate adsorption,and catalytic performance in the POC-immobilized MCs system has not been previously *** anticipate that our research will provide valuable insights in this field.

关键词： metal cluster porous organic cage encapsulation microenvironment catalysis

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Dynamic Identification and Evolution of Urban-suburban-rural Transition Zones Based on the Blender of Natural and Humanistic Factors: A Case Study of Chengdu, China

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Chinese Geographical Science 2024年第5期34卷 791-809页

作者： DENG Wei JIANG Zhenyuan ZHANG Shaoyao ren Ping ZHANG hao WANG Zhanyun The Faculty Geography Resources Science Sichuan Normal UniversityChengdu 610101China Sustainable Development Research Center of Resources and Environment in Western Sichuan Sichuan Normal UniversityChengdu 610101China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China

Urban-suburban-rural(U-S-R)zones exhibit distinctive transitional characteristics in interaction between human and nature.U-S-R transition zones(U-S-RTZ)are also highlighting the function diversity and landscape heterogeneity across territorial *** a super megacity in western China,Chengdu’s rapid urbanization has driven the evolution of U-S-R spaces,resulting in a sequential *** promote the high-quality spatial development of urban-rural region in a structured and efficient manner,it is essential to con-duct a scientific examination of the multidimensional interconnection within the U-S-RTZ *** proposing a novel identifica-tion method of U-S-RTZ and taking Chengdu,China as a case study,grounded in a blender of natural and humanistic factors,this study quantitatively delineated and explored the spatial evolutions of U-S-RTZ and stated the optimization orientation and sustainable devel-opment strategies of the production-living-ecological spaces along the U-S-R *** results show that:1)it is suitable for the quantitative analysis of U-S-RTZ by established three-dimensional identification system in this study.2)In 1990-2020,the urban-sub-urban transition zones(U-STZ)in Chengdu have continuously undergone a substantial increase,and the scale of the suburban-rural transition zones(S-RTZ)has continued to expand slightly,while the space of rural-ecological transition zones(R-ETZ)has noticeably compressed.3)The landuse dynamics within U-S-RTZ has gradually increased in *** main direction of landuse transition was from farmland to construction land or woodlands,with the expansion of construction land being the most significant.4)R-ETZ primarily focus on ecological functions,and there is a trade-off relationship between the production-ecological function within the S-RTZ,and in the U-STZ,production-living composite functions are *** study emphasizes the importance of elastic planning and precise governance within the U-

关键词： transition zone urban-suburban-rural zones spatial identification evolution mechanism Chengdu,China

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Highly selective adsorption of rhenium by amyloid-like protein material

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Science China(Technological Sciences) 2024年第5期67卷 1417-1430页

作者： MUHAMMAD Arif YANG QingMin KANWAL Aisha Zhao Jian NAWAZ Mohsan ren hao YANG Peng Key Laboratory of Applied Surface and Colloid Chemistry Ministry of Education Xi’an Key Laboratory of Polymeric Soft Matter International Joint Research Center on Functional Fiber and Soft Smart TextileSchool of Chemistry and Chemical EngineeringShaanxi Normal UniversityXi’an710119China School of Chemistry and Chemical Engineering Northwestern Polytechnical UniversityXi’an710072China

Rhenium separation from molybdenum in molybdenite minerals and waste leachate has become an emerging *** this challenge,we prepared a set of protein-based alkylamine/alkylammonium salts complexes as extractants for selective uptake of rhenium from molybdenum,where the protein component turned into the insoluble amyloid-like structure when its internal disulfide bonds were reduced,namely phase-transition *** them,the phase-transited lysozyme and methyletrioctyleammonium chloride complex(PTL-N263)exhibited the most efficient adsorption at the alkaline condition for the electrostatic interaction between negatively charged metal ions with positively charged center(R_(4)N^(+))in N263,where negatively charged protein residues hindered the ion exchange of Cl^(-)in N263 for larger size Mo species(Mo_(7)O_(24)^(6-))than smaller size Re species(ReO^(4-)).The adsorption follows the Freundlich model and pseudo-second-order kinetics,which exhibits toplevel adsorption performance with a maximum adsorption capacity of 124 mg/g and a separation factor(β_(Re/Mo))of 2.78×10^(3)for *** adsorption capacity per unit area(57.2 mg/(g m^(2)))is 1.6–41 times higher than previously reported adsorbents,and the cost for adsorbing 1 g of Re(VII)is$1.07,indicating its industrial *** adsorption strategy can be applied to separating Re from Mo in binary solutions and industrial wastewater with other competing ions.

关键词： amyloid phase-transited lysozyme selective adsorption rhenium waste leachate solution

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