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Preparation of Self-limiting Heating Cables with Excellent Processability, Mechanical Properties and PTC Effect via Thermal and Electrical Treatments

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Chinese Journal of Polymer Science 2024年第4期42卷 511-520页

作者： Tian-Hao Yang Tong wu qiang Fu State Key Laboratory of Polymer Materials Engineering College of Polymer Science and EngineeringSichuan UniversityChengdu610065China State Key Laboratory of Polymer Materials Engineering Polymer Research Institute of Sichuan UniversityChengdu610065China

Polymer/conductive filler composites have been widely used for the preparation of self-limiting heating cables with the positive temperature coefficient (PTC) effect. The control of conductive filler distribution and network in polymer matrix is the most critical for performance of PTC materials. In order to compensate for the destruction of the filler network structure caused by strong shearing during processing, an excessive conductive filler content is usually added into the polymer matrix, which in turn sacrifices its processability and mechanical properties. In this work, a facile post-treatment of the as-extruded cable, including thermal and electrical treatment to produce high-density polyethylene (HDPE)/carbon black (CB) cable with excellent PTC effect, is developed. It is found for the as-extruded sample, the strong shearing makes the CB particles disperse uniformly in HDPE matrix, and 25 wt% CB is needed for the formation of conductive paths. For the thermal-treated sample, a gradually aggregated CB filler structure is observed, which leads to the improvement of PTC effect and the notable reduction of CB content to 20 wt%. It is very interesting to see that for the sample with combined thermal and electrical treatment, CB particles are agglomerated and oriented along the electric field direction to create substantial conductive paths, which leads to a further decrease of CB content down to 15 wt%. In this way, self-limiting heating cables with excellent processability, mechanical properties and PTC effect have simultaneously been achieved.

关键词： Self-limiting heating cables Positive temperature coefficient Thermal treatment Electrical treatment

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Multi-endpoint assays reveal more severe toxicity induced by chloraminated effluent organic matter than chloraminated natural organic matter

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Journal of Environmental Sciences 2024年第1期135卷 310-317页

作者： hai-Yan Wang De-Xiu wu Ye Du Xiao-Tong Lv Qian-Yuan wu State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China Environmental Protection Key Laboratory of Microorganism Application and Risk Control Guangdong Provincial Engineering Research Center for Urban Water Recycling and Environmental SafetyTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China College of Architecture and Environment Sichuan UniversityChengdu 610000China

Disinfection by chloramination produces toxic byproducts and the difference in toxicity of reclaimed and drinking water treated by chloramination remains unclear.This study investigated cytotoxic effects at the same concentrations of dissolved organic matter and showed that chloraminated effluent organic matter(EfOM)induced 1.7 times higher cytotoxicity than chloraminated natural organic matter(NOM)applied to simulate drinking water.Chloraminated EfOM induced more reactive nitrogen species than chloraminated NOM,and chloraminated EfOM and NOM induced similar and higher levels of reactive oxygen species than the negative control,respectively.Consequently,intracellular macromolecule damage indicated by DNA/RNA damage marker 8–hydroxy-(deoxy)guanosine and the intracellular protein carbonyl concentration induced by chloraminated EfOM was higher and slightly more than that induced by chloraminated NOM,respectively.These data were consistent with the effects on cell physiological processes.Cell cycle arrest mainly occurred in G2 phase by chloraminated EfOM and NOM.Early apoptotic cells,which could return to normal,increased upon exposure to high concentrations of chloraminated EfOM and NOM.Moreover,necrotic cells were significantly increased from 0.5%to 2.5%when the concentration increased from 20-to 60-fold chloraminated EfOM,but were not obviously changed by chloraminated NOM.These results indicated that the comprehensive intracellular changes induced by toxic substances in chloraminated EfOM were more irreversible and induced more cell death than chloraminated NOM.

关键词： Cytotoxicity Intracellular active nitrogen/oxygen Intracellular oxidative damage Cell necrosis Reclaimed water

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Brain Cognition Mechanism-Inspired Hierarchical Navigation Method for Mobile Robots

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Journal of Bionic Engineering 2024年第2期21卷 852-865页

作者： qiang Zou Chengdong wu Ming Cong Dong Liu Faculty of Robot Science and Engineering Northeastern UniversityShenyang110819China School of Mechanical Engineering Dalian University of TechnologyDalian116024China

Autonomous navigation is a fundamental problem in robotics.Traditional methods generally build point cloud map or dense feature map in perceptual space;due to lack of cognition and memory formation mechanism,traditional methods exist poor robustness and low cognitive ability.As a new navigation technology that draws inspiration from mammal’s navigation,bionic navigation method can map perceptual information into cognitive space,and have strong autonomy and environment adaptability.To improve the robot’s autonomous navigation ability,this paper proposes a cognitive map-based hierarchical navigation method.First,the mammals’navigation-related grid cells and head direction cells are modeled to provide the robots with location cognition.And then a global path planning strategy based on cognitive map is proposed,which can anticipate one preferred global path to the target with high efficiency and short distance.Moreover,a hierarchical motion controlling method is proposed,with which the target navigation can be divided into several sub-target navigation,and the mobile robot can reach to these sub-targets with high confidence level.Finally,some experiments are implemented,the results show that the proposed path planning method can avoid passing through obstacles and obtain one preferred global path to the target with high efficiency,and the time cost does not increase extremely with the increase of experience nodes number.The motion controlling results show that the mobile robot can arrive at the target successfully only depending on its self-motion information,which is an effective attempt and reflects strong bionic properties.

关键词： Bionic navigation Spatial localization cells Global path planning Hierarchical motion controlling

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The Sequential Pricing of Ride-hailing System with Rental Service in the Context of Fleet Electrification

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Journal of Systems Science and Systems Engineering 2024年第1期33卷 77-105页

作者： Yaoyao Ku Peng wu qiang Ren Yiqing Wang Business School Sichuan UniversityChengdu610065China

Surging demand and reduced capacity in the ride-hailing industry have prompted numerous ride-hailing platforms to build their own car-rental services catering to drivers who do not possess private vehicles. However, the trade-off between the ride-hailing service and the car-rental service is an important issue that is still unclear in theory. Moreover, ride-hailing platforms are transitioning towards all-electric fleets in the context of Carbon Neutrality goals and government regulations. This paper considers a ride-hailing system comprising a monopolist ride-hailing platform, an electric vehicle (EV) rental firm, and a gasoline vehicle (GV) rental firm. Furthermore, we build a stylized model to study the sequential pricing of the system. The equilibrium outcomes show the significant impact of the ride-hailing platform’s decision to continue or withdraw offering EV rental services on EV and GV drivers’ net earnings, rental prices, and wages. The ride-hailing platform providing EV rental services increases EV drivers’ net earnings but decreases the GV driver wages and rental prices. However, the EV rental service offered by the ride-hailing platform does not necessarily lead to an increased total profit for the system. The improved profitability of the system by the ride-hailing platform providing EV rental services is contingent upon lower rider prices and higher fuel costs. The ride-hailing platform’s EV rental services provision also effectively fosters the ride-hailing fleet’s electrification. Furthermore, as the number of riders increases, the ride-hailing platform should reduce the commission rate for EV drivers to maintain competitiveness and profitability.

关键词： Ride-hailing system car rental fleet electrification sequential pricing differential wage scheme

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Sustained release of vascular endothelial growth factor A and basic fibroblast growth factor from nanofiber membranes reduces oxygen/glucose deprivation-induced injury to neurovascular units

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Neural Regeneration Research 2024年第4期19卷 887-894页

作者： Yifang wu Jun Sun Qi Lin Dapeng Wang Jian hai Department of Neurosurgery Tongji HospitalSchool of MedicineTongji University Department of Pharmacy Institute of Medical SciencesShanghai Jiao Tong University School of Medicine

Upregulation of vascular endothelial growth factor A/basic fibroblast growth factor(VEGFA/b FGF)expression in the penumbra of cerebral ischemia can increase vascular volume,reduce lesion volume,and enhance neural cell proliferation and differentiation,thereby exerting neuroprotective effects.However,the beneficial effects of endogenous VEGFA/b FGF are limited as their expression is only transiently increased.In this study,we generated multilayered nanofiber membranes loaded with VEGFA/b FGF using layer-by-layer self-assembly and electrospinning techniques.We found that a membrane containing 10 layers had an ideal ultrastructure and could efficiently and stably release growth factors for more than 1 month.This 10-layered nanofiber membrane promoted brain microvascular endothelial cell tube formation and proliferation,inhibited neuronal apoptosis,upregulated the expression of tight junction proteins,and improved the viability of various cellular components of neurovascular units under conditions of oxygen/glucose deprivation.Furthermore,this nanofiber membrane decreased the expression of Janus kinase-2/signal transducer and activator of transcription-3(JAK2/STAT3),Bax/Bcl-2,and cleaved caspase-3.Therefore,this nanofiber membrane exhibits a neuroprotective effect on oxygen/glucose-deprived neurovascular units by inhibiting the JAK2/STAT3 pathway.

关键词： brain ischemia brain microvascular endothelial cell nanofiber membrane neurovascular unit

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Coinfection of SARS-CoV-2 Omicron variant and other respiratory pathogens in children

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World Journal of Pediatrics 2024年第1期20卷 92-96页

作者： Wei Li Bing-Han Wang Bao-hai Chen Yi Sun Lin Li Wen-Qing Xiang Ahmed Faisal Ali Lin-Xuan Su hai-Yan Mao Hong-qiang Shen qiang Shu Department of Clinical Laboratory Children's HospitalNational Clinical Research Center for Child HealthZhejiang University School of MedicineHangzhouChina School of Public Health Zhejiang University School of MedicineHangzhouChina Department of Information Center Children's HospitalZhejiang University School of MedicineHangzhouChina Zhejiang Provincial Center for Disease Control and Prevention HangzhouChina Department of Thoracic&Cardiovascular Surgery Children's HospitalNational Clinical Research Center for Child HealthZhejiang University School of MedicineHangzhouChina

Since the outbreak of coronavirus disease 2019(COVID-19),the entire world has been affected by the epidemic[1,2].On November 9,2021,a variant of the novel coronavirus B.1.1.529 was detected for the first time from case samples in South Africa.The Omicron strain spread and mutated significantly fast.This variant has the characteristics of escape immunity,which can induce relatively extreme disease and reduce the neutralization of antibodies in vaccinators,and is more likely to be reinfected[3,4].The clinical presentation of severe acute respiratory syndrome coronavirus 2(SARSCoV-2)in children has mild symptoms and a lower risk of hospitalization and death.

关键词： respiratory immunity acute

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Ultrafast investigation of room temperature valley polarization in“optical bilayer”WS_(2)

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Science China(Technological Sciences) 2024年第1期67卷 91-97页

作者： ZHAO LeYi WANG hai LIU TianYu LI FangFei ZHOU qiang WANG haiYu Synergetic Extreme Condition High-Pressure Science Center State Key Laboratory of Superhard MaterialsCollege of PhysicsJilin UniversityChangchun 130012China State Key Laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China

Monolayer transition metal dichalcogenides(TMDCs)have become a promising platform in valleytronics due to possessing the regulatable valley degrees of freedom.While,as a result of the rapid intervalley scattering,it is difficult to measure the PL valley polarization of monolayer TMDCs at room temperature,which limits their application in valleytronics devices.Here,we report a room temperature photoluminescence(PL)valley polarization up to 3.73%in an“optical bilayer”WS_(2)formed by transferring monolayer WS_(2)onto flat Ag film.Furthermore,in the transient absorption(TA)measurements,a remarkably long valley depolarization lifetime is found.Thus,we demonstrate the valley properties of such“optical bilayer”WS_(2)resemble actual bilayer WS_(2),in which the robust valley polarization can be attributed to the phonons depletion effect and the blocked interlayer hopping processes.These peculiar valley features in“optical bilayer”WS_(2)provide a particularly simple method to enhance valley control at room temperature.

关键词： valleytronics optical bilayer transient absorption tungsten disulfide

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Lithium-induced graphene layer containing Li_(3)P alloy phase to achieve ultra-stable electrode interface for lithium metal anode

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Rare Metals 2024年第2期43卷 562-574页

作者： Jia-Xin Chen Guo-qiang Zhang Xian-Ying Qin Kui Lin Zi-Jin Yang Ge-Meng Liang Yue Xia Guo-Bin Zhang hai-Kun wu Qiu-Chan Cai hai Lin Bao-Hua Li Shenzhen Key Laboratory on Power Battery Safety Research and Shenzhen Geim Graphene Center Tsinghua Shenzhen International Graduate SchoolShenzhen518055China Shenzhen Graphene Innovation Center Co. Ltd.Shenzhen518107China School of Chemical Engineering and Advanced Materials The University of AdelaideAdelaideSA5005Australia Department of Chemistry City University of Hong KongHong Kong990077China

Uncontrolled growth of lithium dendrite will lead to low Coulombic efficiency and poor cycle stability,which hinders the commercialization of lithium metal batteries.Herein,a novel modified lithium anode with reduced graphene oxide conductive network containing trace lithiophilic phosphorus(P-rGO/Cu)is prepared by electrospraying technique combined with heat treatment process.The rGO layer has a concave and undulating conductive structure,which can significantly improve the effective electrical contact between lithium metal and the current collector,speed up the kinetics of interfacial electron transport and reaction,and improve the resistance of the negative electrode to the internal stress caused by volume change of the lithium,which is advantageous for the stability of the SEI film.The extremely small and uniformly distributed red phosphorus element avoids the volume change caused by lithiation to the maximum extent.Lithiophilic two-phase compound Li_(3)P obtained by alloying P with Li can directionally induce the homogeneous nucleation and dense deposition of lithium metal,address the issue of lithium dendrites and extend the cycle life of the batteries.The obtained P-rGO/Cu exhibits excellent electrochemical performance with an average Coulombic efficiency(CE)of 98%at a current density of 1 mA·cm^(−2) for 400 cycles,and the capacity retention rate of the full cell matched with lithium iron phosphate(LFP)is 83%after 400 cycles at 1C.

关键词： Lithium anode Dendrite-free Lithiophilicity Induced nucleation deposition

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Boosting oxygen vacancies by modulating the morphology of Au decorated In_(2)O_(3)with enhanced CO_(2)hydrogenation activity to CH_(3)OH

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Journal of Environmental Sciences 2024年第6期140卷 91-102页

作者： Ruxian Hou Jiewen Xiao Qian wu Tianyu Zhang qiang Wang Beijing Key Lab for Source Control Technology of Water Pollution College of Environmental Science and EngineeringBeijing Forestry UniversityBeijing 100083China Engineering Research Center for Water Pollution Source Control&Eco-remediation College of Environmental Science and EngineeringBeijing Forestry UniversityBeijing 100083China

CO_(2)hydrogenation to methanol has become one of the most promising ways for CO_(2)utilization,however,the CO_(2)conversion rate and methanol selectivity of this reaction still need to be improved for industrial application.Here we investigated the structure-activity relationship for CO_(2)conversion to methanol of In_(2)O_(3)-based catalysts by modulating morphology and decorating Au.Three different Au/In_(2)O_(3)catalysts were prepared,their activity follow the sequence of Au/In_(2)O_(3)-nanosphere(Au/In_(2)O_(3)-NS)>Au/In_(2)O_(3)-nanoplate(Au/In_(2)O_(3)-NP)>Au/In_(2)O_(3)-hollow microsphere(Au/In_(2)O_(3)-HM).Au/In_(2)O_(3)-NS exhibited the best performance with good CO_(2)conversion of 12.7%,high methanol selectivity of 59.8%,and large space time yield of 0.32 g CH_(3)OH/(hr·gcat)at 300℃.The high performance of Au/In_(2)O_(3)-NS was considered as the presence of Au.It contributes to the creation of more surface oxygen vacancies,which further promoted the CO_(2)adsorption and facilitated CO_(2)activation to form the formate intermediates towards methanol.This work clearly suggests that the activity of In_(2)O_(3)catalyst can be effective enhanced by structure engineering and Au decorating.

关键词： CO_(2)hydrogenation Methanol Au/In_(2)O_(3) Morphology Oxygen vacancies

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Mechanical property of cylindrical sandwich shell with gradient core of entangled wire mesh

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Defence Technology（防务技术） 2024年第1期31卷 510-522页

作者： Xin Xue Chao Zheng Fu-qiang Lai Xue-qian wu Institute of Metal-rubber&Vibration Noise School of Mechanical Engineering and AutomationFuzhou UniversityFuzhou350116China Fujian Metallurgical Industry Design Institute Fuzhou350116China

To explore the wide-frequency damping and vibration-attenuation performances in the application of aerospace components,the cylindrical sandwich shell structure with a gradient core of entangled wire mesh was proposed in this paper.Firstly,the gradient cores of entangled wire mesh in the axial and radial directions were prepared by using an in-house Numerical Control weaving machine,and the metallurgical connection between skin sheets and the gradient core was performed using vacuum brazing.Secondly,to investigate the mechanical properties of cylindrical sandwich shells with axial or radial gradient cores,quasi-static and dynamic mechanical experiments were carried out.The primary evaluations of mechanical properties include secant stiffness,natural frequency,Specific Energy Absorption(SEA),vibration acceleration level,and so on.The results suggest that the vibration-attenuation performance of the sandwich shell is remarkable when the high-density core layer is at the end of the shell or abuts the inner skin.The axial gradient material has almost no influence on the vibration frequencies of the shell,whereas the vibration frequencies increase dramatically when the high-density core layer approaches the skin.Moreover,compared to the conventional sandwich shells,the proposed functional grading cylindrical sandwich shell exhibits more potential in mass reduction,stiffness designing,and energy dissipation.

关键词： Entangled wire mesh Gradient cylindrical sandwich shell Vacuum brazing Secant stiffness Damping

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