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Effect of heat treatment on microstructural evolution,mechanical properties and tribological properties of H13 steel prepared using selective laser melting

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Journal of Iron and Steel Research(International) 2024年第5期31卷 1246-1259页

作者： Li-xiong Han Yan wang shi-feng Liu Zhao-hui Zhang wei Liu Xin Yang Dang-shen Ma Jian Zhou Ying-kang wei College of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an710055ShaanxiChina Zhejiang University City College Hangzhou310015ZhejiangChina China Iron and Steel Research Institute Group Co. Ltd.Beijing100081China

H13 tool steel was successfully prepared by selective laser melting(SLM)*** effects of heat treatment on the microstructure,mechanical properties,and tribological properties of SLMed H13 steel were *** heat treatment process involved a solution treatment and a double aging treatment of the deposited H13 tool steel prepared by *** aim is to optimize the microstructure and mechanical properties of SLMed H13 *** to the rapid heating and cooling effects of SLM,carbide precipitation in the deposited H13 steel was not uniform and residual stresses were *** purpose of the solution treatment is to dissolve the solution at a high temperature to eliminate the residual stresses and defects introduced by the SLM-forming *** solution treatment and first aging treatment produced the precipitation of small carbides at the grain boundaries and inside the crystals,which increased the hardness of SLMed H13 *** hardness increased from 538±4.0 HV of the as-deposited sample to 548±5.8 HV of samples after the first aging ***,the ultimate tensile strength and the elongation at break decreased from 1882 MPa and 11.5%in the as-deposited sample to 1697 MPa and 7.9%in those after the first aging treatment,***,the friction coefficient and wear rate in the as-deposited sample decreased from 0.5160 and 2.36×10^(–6)mm^(−3)N^(−1)m^(−1)to 0.4244 and 1.04×10^(–6)mm^(−3)N^(−1)m^(−1),***,the distribution of carbides inside the crystals was not *** second aging treatment adjusted the morphology of carbide precipitation and made it more uniform,but the precipitation of carbides grew and settled at the bottom of the grain *** hardness decreased to 533±6.7 HV compared with that with the first aging treatment,but the ultimate tensile strength and plasticity reached a balance(1807 MPa,14.05%).Accordingly,the friction coefficient and wear rate also showed a stable and decreasin

关键词： Selective laser melting H13 steel Solution aging Double aging Friction and wear Retained austenite

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Bioinspired Stretchable MXene Deformation-Insensitive Hydrogel Temperature Sensors for Plant and Skin Electronics

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Research 2024年第1期2023卷 389-401页

作者： Jun Wu Yinghui Li Shengshun Duan Zhehan wang Xu Jing Yucheng Lin Di Zhu wei Lei Qiongfeng shi Li Tao Joint International Research Laboratory of Information Display and Visualization School of Electronic Science and EngineeringSoutheast UniversityNanjingJiangsu 210096China School of Materials Science and Engineering Southeast UniversityNanjingJiangsu 210096China Center of 2D Materials and Devices Southeast UniversityNanjingJiangsu 210096China

Temperature sensing is of high value in the wearable healthcare,robotics/prosthesis,and noncontact physiological ***,the common mechanic deformation,including pressing,bending,and stretching,usually causes undesirable feature size changes to the inner conductive network distribution of temperature sensors,which seriously influences the ***,inspired by the transient receptor potential mechanism of biological thermoreceptors that could work precisely under various skin contortions,we propose an MXene/Clay/poly(N-isopropylacrylamide)(PNIPAM)(MCP)hydrogel with high stretchability,spike response,and deformation *** dynamic spike response is triggered by the inner conductive network transformation from the 3-dimensional structure to the 2-dimensional surface after water being discharged at the threshold *** water discharge is solely determined by the thermosensitivity of PNIPAM,which is free from mechanical deformation,so the MCP hydrogels can perform precise threshold temperature(32℃)sensing under various deformation conditions,i.e.,pressing and 15%*** a proof of concept,we demonstrated the applications in plant electronics for the real-time surface temperature monitoring and skin electronics for communicating between human and *** research opens venues for the accurate temperature-threshold sensation on the complicated surface and mechanical conditions.

关键词： stretching proof precise

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Decabromodiphenyl ether induces the chromosome association disorders of spermatocytes and deformation failures of spermatids in mice

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Journal of Environmental Sciences 2024年第4期138卷 531-542页

作者： Jinglong Xue Xiangyang Li Yafei Chi Leqiang Gao Yue Zhang Yan wang Moxuan Zhao Jialiu wei Zhixiong shi Xianqing Zhou Department of Toxicology and Hygienic Chemistry School of Public HealthCapital Medical UniversityBeijing 100069China Beijing Key Laboratory of Environmental Toxicology Capital Medical UniversityBeijing 100069China Laboratory Animal Center Capital Medical UniversityBeijing 100069China Key Laboratory of Cardiovascular Epidemiology&Department of Epidemiology Fuwai HospitalNational Center for Cardiovascular DiseasesChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100037China

The environmental presence of decabromodiphenyl ether(BDE-209),which is toxic to the male reproductive system,is *** current study investigated its mechanism of toxicity in *** results showed,that BDE-209 induced DNA damage,decreased the expression of the promoter of meiosis spermatogenesis-and oogenesis-specific basic helix-loop-helix 1(Sohlh1),meiosis related-factors Lethal(3)malignant brain tumor like 2(L3MBTL2),PIWI-like protein 2(MILI),Cyclin-dependent kinase 2(CDK2),Cyclin A,synaptonemal complex protein 1(SYCP1)and synaptonemal complex protein 3(SYCP3),and caused spermatogenic cell apoptosis,resulting in a decrease in sperm quantity and ***,BDE-209 downregulated the levels of anaphase-promoting complex/cyclosome(APC/C),increased the expression of PIWI-like protein 1(MIWI)in the cytoplasm of elongating spermatids,and decreased the nuclear levels of RING finger protein 8(RNF8),ubiquitinated(ub)-H2A/ub-H2B,and Protamine 1(PRM1)/Protamine 2(PRM2),while increasing H2A/H2B nuclear levels in *** reproductive toxicity was persistent for 50 days following the withdrawal of BDE-209 *** results suggested that BDE-209 inhibits the initiation of meiosis by decreasing the expression of ***,the reduced expression of L3MBTL2 inhibited the formation of chromosomal synaptonemal complexes by depressing the expression of meiosis regulators affecting the meiotic progression and also inhibited histone ubiquitination preventing the replacement of histones by protamines,by preventing RNF8 from entering nuclei,which affected the evolution of spermatids into mature sperm.

关键词： BDE-209 Meiosis L3MBTL2 Sperm RNF8 Histone ubiquitination

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Promoted surface charge density from interlayer Zn–N_(4) configuration in carbon nitride for enhanced CO_(2) photoreduction

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Nano Research 2024年第4期17卷 2400-2409页

作者： Xianjin shi Yu Huang Gangqiang Zhu wei Peng Meijuan Chen State Key Laboratory of Loess and Quaternary Geology(SKLLQG) Key Laboratory of Aerosol Chemistry and PhysicsInstitute of Earth EnvironmentChinese Academy of SciencesXi’an 710061China Center of Excellence in Quaternary Science and Global Change Chinese Academy of SciencesXi’an 710061China University of Chinese Academy of Sciences Beijing 100049China School of Physics and Information Technology Shaanxi Normal UniversityXi’an 710062China School of Human Settlements and Civil Engineering Xi’an Jiaotong UniversityXi’an 710049China

The solar-driven reduction of CO_(2) into valuable products is a promising method to alleviate global environmental problems and energy ***,the low surface charge density limits the photocatalytic conversion performance of CO_(2).Herein,a polymeric carbon nitride(PCN)photocatalyst with Zn single atoms(Zn1/CN)was designed and synthesized for CO_(2) *** results of the CO_(2) photoreduction studies show that the CO and CH_(4) yields of Zn1/CN increased fivefold,reaching 76.9 and 22.9μmol/(g·h),respectively,in contrast to the unmodified ***+plasma-etched X-ray photoelectron spectroscopy and synchrotron radiation-based X-ray absorption fine structure results reveal that Zn single atom is mainly present in the interlayer space of PCN in the Zn–N_(4) *** characterizations indicate that the interlayer Zn–N_(4) configuration can amplify light absorption and establish an interlayer charge transfer ***-assisted Kelvin probe force microscopy confirms that more photogenerated electrons are delivered to the catalyst surface through interlayer Zn–N_(4) configuration,which increases its surface charge ***,in-situ infrared spectroscopy combined with density functional theory calculation reveals that promoted surface charge density accelerates key intermediates(*COOH)conversion,thus achieving efficient CO_(2) *** work elucidates the role of internal single atoms in catalytic surface reactions,which provides important implications for the design of single-atom catalysts.

关键词： single-atom catalysts photocatalytic CO_(2)reduction interlayer modification charge transfer dynamics surface charge density

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taBOX: A water-soluble tetraanionic rectangular molecular container for conjugated molecules and taste masking for berberine and palmatine

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Chinese Chemical Letters 2024年第5期35卷 175-178页

作者： Qihan Lin Jiabin Xing Yue-Yang Liu Gang Wu shi-Jia Liu Hui wang wei Zhou Zhan-Ting Li Dan-wei Zhang Department of Chemistry Shanghai Key Laboratory of Molecular Catalysis and Innovative MaterialsFudan UniversityShanghai 200438China

A water-soluble macrocycle that bears four carboxylate anions has been designed and prepared,which forms a rectangular cavity that can efficiently encapsulate discrete electron-deficient aromatic compounds,including berberine and *** macrocycle is revealed to be highly biocompatible and able to inhibit the bitter taste of the two drugs.

关键词： Macrocycle Multianion Molecular container Molecular recognition Bitter taste masking

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Design and mechanical properties analysis of a cellular Waterbomb origami structure

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Theoretical & Applied Mechanics Letters 2024年第3期14卷 193-202页

作者： Yongtao Bai Zhaoyu wang Yu shi School of Civil Engineering Chongqing UniversityChongqing 400045China Research Center of Steel Structure Engineering Chongqing UniversityChongqing 400045China

Cellular structures are commonly used to design energy-absorbing structures,and origami structures are becominga prevalent method of cellular structure *** paper proposes a foldable cellular structure based on theWaterbomb origami *** geometrical configuration of this structure is ***-static compressiontests of the origami tube cell of this cellular structure are conducted,and load-displacement relationship curvesare *** simulations are carried out to analyze the effects of aspect ratio,folding angle,thicknessand number of layers of origami tubes on initial peak force and specific energy absorption(SEA).Calculationformulas for initial peak force and SEA are obtained by the multiple linear regression *** degree ofinfluence of each parameter on the mechanical properties of the single-layer tube cell is *** resultsshow that the cellular structure exhibits negative stiffness and periodic load-bearing capacity,as well as foldingangle has the most significant effect on the load-bearing and energy-absorbing *** adjusting the designparameters,the stiffness,load-bearing capacity and energy absorption capacity of this cellular structure can beadjusted,which shows the programmable mechanical properties of this cellular *** foldability andthe smooth periodic load-bearing capacity give the structure potential for application as an energy-absorbing structure.

关键词： Cellular structure Waterbomb origami Mechanical metamaterial Numerical simulation Energy absorption

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Is the Cape Stone Forest in Shantou City formed by wave erosion? A comparison of the pedestal rocks on the coasts and the mountains of Queshi in eastern Guangdong, China

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Journal of Mountain Science 2024年第5期21卷 1447-1463页

作者： CHEN Min wang wei School of Geography South China Normal UniversityGuangzhou 510631China

Cape Stone Forest is a group of granite rock pillars(pedestal rocks) towering over shilin Lake, on the southern shore of Shantou Bay in eastern Guangdong, China. The rock pillars were previously identified as sea stacks because they have marine notch-like concave sidewalls at their base, and more importantly, the lake is immediately adjacent to the bay, which is exposed to the open sea. However, rock pillars similar in shape and size can also be found at the top of Queshi Mountain, which is only about 300 meters northwest of the lake and about 85 meters above sea level. Therefore, the marine origin of Cape Stone Forest is seriously questioned. In this study, 3D imagery and drone technology were used to collect data in the investigations without direct manual measurements in the water or on the mountain. It shows that the concave sidewalls of the rock pillars in the lake and on the mountains occur at different heights and are exposed to different directions, while a natural sea stack on Mayu Island at the mouth of Shantou Bay has a horizontal notch parallel to the sea level, although the granite rock of the sea stack is the same as that of the lake and the mountains. The eastern side of the island, where the sea stack is located, is exposed to the open sea but blocks large waves for the rock pillars in the lake. Therefore, the origin of Cape Stone Forest cannot be explained by wave-based mechanisms. The only satisfactory explanation that takes into account all the field evidence is that the narrow rock pillars of the lake and mountain were formed by chemical weathering that penetrated closely the spaced joints of the granite rock, and the notch-like concave sidewalls were formed by more effective chemical weathering at the base of the pillars.

关键词： Pedestal rock Granite Closely spaced joints Wave erosion Chemical weathering

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Aboveground biomass stocks of species-rich natural forests in southern China are influenced by stand structural attributes,species richness and precipitation

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Plant Diversity 2024年第4期46卷 530-536页

作者： Wen-Hao Zeng shi-Dan Zhu Ying-Hua Luo wei shi Yong-Qiang wang Kun-Fang Cao State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources College of ForestryGuangxi UniversityNanning 530004China Guangxi Key Laboratory of Forest Ecology and Conservation College of ForestryGuangxi UniversityNanning 530004China Key Laboratory of National Forestry and Grassland Administration on Biodiversity Conservation in Karst Mountainous Areas of Southwestern China School of Life SciencesGuizhou Normal UniversityHuaxi College TownGui'an DistrictGuiyang 550025China

Forests,the largest terrestrial carbon sinks,play an important role in carbon sequestration and climate change *** forest attributes and environmental factors have been shown to impact aboveground biomass,their influence on biomass stocks in species-rich forests in southern China,a biodiversity hotspot,has rarely been *** this study,we characterized the effects of environmental factors,forest structure,and species diversity on aboveground biomass stocks of 30 plots(1 ha each) in natural forests located within seven nature reserves distributed across subtropical and marginal tropical zones in Guangxi,*** results indicate that forest aboveground biomass stocks in this region are lower than those in mature tropical and subtropical forests in other ***,we found that aboveground biomass was positively correlated with stand age,mean annual precipitation,elevation,structural attributes and species richness,although not with species *** we compared stands with the same basal area,we found that aboveground biomass stock was higher in communities with a higher coefficient of variation of diameter at breast *** findings highlight the importance of maintaining forest structural diversity and species richness to promote aboveground biomass accumulation and reveal the potential impacts of precipitation changes resulting from climate warming on the ecosystem services of subtropical and northern tropical forests in ***,many natural forests in southern China are not fully ***,their continued growth will increase their carbon storage over time.

关键词： Subtropical forest Marginal tropical forest Aboveground biomass Species diversity Forest structural attribute Environment factor

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Steady-state Voltage Security-constrained Optimal Frequency Control for Weak HVDC Sending-end AC Power Systems

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 658-669页

作者： Qiangqiang wang Liangzhong Yao Jian Xu Yuping Zheng wei Li wei wang School of Electrical Engineering and Automation Wuhan UniversityWuhan 430072China Hubei Engineering and Technology Research Center for AC/DC Intelligent Distribution Network(Wuhan University) Wuhan 430072China State Key Laboratory of Smart Grid Protection and Control NARI Group Corporation(State Grid Electric Power Research Institute)Nanjing 211106China

Due to the fact that a high share of renewable energy sources(RESs)are connected to high-voltage direct current(HVDC)sending-end AC power systems,the voltage and frequency regulation capabilities of HVDC sending-end AC power systems have *** has resulted in potential system operating problems such as overvoltage and overfrequency,which occur simultaneously when block faults exist in the HVDC *** this study,a steady-state voltage security-constrained optimal frequency control method for weak HVDC sending-end AC power systems is *** integrated virtual inertia control of RESs is employed for system frequency *** dynamic reactive power compensation devices are utilized to control the voltage of all nodes meet voltage security ***,an optimization model that simultaneously considers the frequency and steady-state voltage security constraints for weak HVDC sending-end AC power systems is *** optimal control scheme with the minimum total cost of generation tripping and additional dynamic reactive power compensation required is obtained through the optimization *** are conducted on a modified IEEE 9-bus test system and practical Qing-Yu line commutated converter based HVDC(LCC-HVDC)sending-end AC power system to verify the effectiveness of the proposed method.

关键词： Renewable energy source(RES) high-voltage direct current(HVDC) AC power system optimal frequency control steady-state voltage security dynamic reactive power compensation

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High-performance Refractive Index Sensor Based on Photonic Crystal Single Mode Resonant Micro-cavity

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稀有金属材料与工程 2006年第A3期35卷 425-428页

作者： Shengye Huang Junfeng shi Dongsheng wang wei Li State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision Instruments and Mechanology Tsinghua University Beijing 100084 China

An effective refractive index sensor built with square lattice photonic crystal is proposed,which can be applicable to photonic integrated *** photonic crystal waveguides rather than conventional ridge waveguides are used as entrance/exit waveguides to the *** layers of photonic lattice are set between the photonic crystal waveguides and the micro-cavity to achieve both a high transmission and a high *** plane wave method is utilized to calculate the disperse curves and the finite difference time domain scheme is employed to simulate the light *** the resonant wavelength of about 1500 nm,the resonant wavelength shifts up by 0.7 nm for each increment of Δn=0.001.A transmission of more than 0.75 is *** the position disorder of the photonic crystal doesn't affect the sensitivity of the sensor, the transmission reduces rapidly as the disorder increases.

关键词： optical biosensor refractive index sensor photonic crystal resonant cavity

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