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Modeling of microstructure evolution of AZ80 magnesium alloy during hot working process using a unified internal state variable method

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Journal of Magnesium and Alloys 2022年第1期10卷 299-313页

作者： zexing Su Chaoyang Sun Mingjia Wang lingyun Qian Xintong li School of Mechanical Engineering University of Science and Technology Beijing30 Xueyuan RoadHaidian DistrictBeijing 100083China Beijing Key Laboratory of lightweight Metal Forming Beijing 100083China College of Nuclear Equipment and Nuclear Engineering Yantai UniversityYantai 264005China Shunde Graduate School of University of Science and Technology Beijing Foshan528000China

In this paper, a unified internal state variable(ISV) model for predicting microstructure evolution during hot working process of AZ80 magnesium alloy was developed. A novel aspect of the proposed model is that the interactive effects of material hardening, recovery and dynamic recrystallization(DRX) on the characteristic deformation behavior were considered by incorporating the evolution laws of viscoplastic flow, dislocation activities, DRX nucleation and boundary migration in a coupled manner. The model parameters were calibrated based on the experimental data analysis and genetic algorithm(GA) based objective optimization. The predicted flow stress, DRX fraction and average grain size match well with experimental results. The proposed model was embedded in the finite element(FE) software DEFORM-3 D via user defined subroutine to simulate the hot compression and equal channel angular extrusion(ECAE) processes. The heterogeneous microstructure distributions at different deformation zones and the dislocation density evolution with competitive deformation mechanisms were captured.This study can provide a theoretical solution for the hot working problems of magnesium alloy.

关键词： AZ80 magnesium alloy Internal state variable model Microstructure evolution Dynamic recrystallization Hot working process Finite element simulation

Porous needle-like Fe-Ni-P doped with Ru as efficient electrocatalyst for hydrogen generation powered by sustainable energies

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Nano Research 2023年第2期16卷 2428-2435页

作者： Yue Wang Zhi Chen Qichang li Xinping Wang Weiping Xiao Yunlei Fu Guangrui Xu Bin li Zhenjiang li zexing Wu Lei Wang Key Laboratory of Eco-chemical Engineering International Science and Technology Cooperation Base of Eco-chemical Engineering and Green ManufacturingCollege of Chemistry and Molecular EngineeringQingdao University of Science and TechnologyQingdao 266042China College of Science Nanjing Forestry UniversityNanjing 210037China Shandong Engineering Research Center for Marine Environment Corrosion and Safety Protection College of Environment and Safety EngineeringQingdao University of Science and TechnologyQingdao 266042China College of Materials Science and Engineering Qingdao University of Science and TechnologyQingdao 266061China

Electrocatalytic water electrolysis,involving hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),two halfreactions,is an eco-friendly approach toward hydrogen production.In this work,needle-like Ru-Fe-Ni-P on NiFe foam is prepared through corrosive engineering and following a low-temperature phosphorization procedure for overall water-splitting.The as-designed Ru-Fe-Ni-P exhibits a porous needle-like structure,surface,and binder-free merits,and then can expose rich active sites,favor the transportation of mass/electron,and accelerate the reaction kinetics during catalytic process.Then,the synthesized Ru-Fe-Ni-P owns remarkable catalytic performance for HER,with 18 and 67 mV to reach 10 mA·cm^(−2)in alkaline and neutral media.Moreover,a low cell voltage of 1.51 V is required to produce a current of 10 mA·cm^(−2)in a two electrode electrolyzer with excellent stability.Interestingly,sustainable energies can power the electrolyzer effectively with abundant hydrogen generation.

关键词： metal phosphide needle-like morphology hydrogen generation overall water splitting

Influences of substituting of(Ni_(1/3)Nb(2/3))for Ti^(4+)on the phase compositions,microstructures,and dielectric properties of li_(2)Zn[Ti_(1-x)(Ni_(1/3)Nb_(2/3))_(x)]_(3)O_(8)(0<≤x≤0.3)microwave ceramics

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Journal of Advanced Ceramics 2023年第4期12卷 760-777页

作者： Jiamao li zexing Wang Yunfeng Guo Songlin Rana School of Materials Science and Engineering Anhui University of TechnologyMaanshan 243032China Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials Ministry of EducationAnhui University of TechnologyMaanshan 243002China

Complex ion substitution is gaining more attention as an appealing method of modifying the structure and performance of microwave ceramics.In this work,li_(2)Zn[Ti_(1-x)(Ni_(1/3)Nb_(2/3))_(x)]_(3)O_(8),0≤x≤0.3ceramics were designed based on the complex ion substitution strategy,following the substitution rule of radius and valence to investigate the relationship among phase compositions(containing oxygen vacancies and Ti^(3+)ions),microstructures,and microwave dielectric characteristics of the LZTNNx ceramics.The samples maintained a single li_(2)ZnTi_(3)O_(8)solid solution phase as x≤0.2,whereas the sample of x=0.3 produced a second phase with the liNbO_(3)structure.The appropriate amount of(Ni_(1/3)Nb_(2/3))^(4+)substitution could slightly improve the densification of the LZTNNx ceramics due to the formation of the liZnTi_(3)O_(8)solid solution accompanied by a decrease in the average grain size.The presence of a new Aig Raman active band at about 848 cm^(-1)indicated that local symmetry changed,affecting atomic interactions of the LZTNNx ceramics.The variation of the relative dielectric constant(εr)was closely related to the molar volume ionic polarizability(α_(D)^(T)),and the temperature coefficient of the resonant frequency(τ_(f))was related to the bond valence(V_(1))of Ti.The increase in density,the absence of the Ti3+ions and oxygen vacancies,and the reduction in damping behavior were responsible for the decreased dielectric loss.The LZTNNO.2 ceramics sintered at 1120℃exhibited favorable microwave dielectric properties:εr=22.13,quality factor(Q×f)=97,350 GHz,andτ_(f)=-18.60 ppm/C,which might be a promising candidate for wireless communication applications in highly selective electronics.

关键词： li_(2)ZnTi_(3)O_(8)ceramics microwave dielectric properties microstructure Raman spectroscopy X-ray photoclcctron spectroscopy(XPS)

多囊卵巢综合征不孕人群接受辅助生殖技术治疗后性激素水平的变化

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昆明医科大学学报 2024年第1期45卷 73-77页

作者：和丽梅冯雪敏李琳珺陈莹杨泽星昆明医科大学公共卫生学院云南昆明650500 邵阳市中心医院公共卫生办湖南邵阳422000 昆明医科大学第一附属医院生殖遗传科云南昆明650032

目的探析不孕症人群中多囊卵巢综合征在接受辅助生殖技术治疗后的性激素水平变化,为治疗方案的选择提供依据。方法收集2016年1月至2021年6月期间于昆明医科大学第一附属医院就诊患者的病例资料,根据是否诊断为多囊卵巢综合征分为PCOS组(... 详细信息

目的探析不孕症人群中多囊卵巢综合征在接受辅助生殖技术治疗后的性激素水平变化,为治疗方案的选择提供依据。方法收集2016年1月至2021年6月期间于昆明医科大学第一附属医院就诊患者的病例资料,根据是否诊断为多囊卵巢综合征分为PCOS组(103名)和非PCOS组(589名),对比2组患者性激素变化情况。结果PCOS组的患者更为年轻,BMI更高,窦状卵泡数更多,AMH值更高,而Gn使用总量更低,PCOS组中LH/FSH>2的人数多于非PCOS组(P<0.05)。经过治疗,2组的LH值均有所减少,FSH、E_2和P都呈上升趋势(P<0.05);且PCOS组LH和E_2治疗前后的差值均大于非PCOS组(P<0.05)。结论相较于非PCOS不孕患者,PCOS不孕人群治疗前后的性激素指标变化更明显。为使多囊卵巢患者获得更好的临床疗效,建议在之后的治疗过程中关注相关性激素水平变化,合理选择治疗方案。

关键词：多囊卵巢综合征性激素治疗效果

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交流高压静电防护服装标准的解读

棉纺织技术 2024年第1期52卷 69-73页

作者：汪泽幸李陆通李文辉张佳吴凯丽湖南工程学院湖南湘潭411104 湖南永霏特种防护用品有限公司湖南湘潭411101

为推动标准的有效推广和实施,以及交流高压静电防护服装的科学制备和合理适用,对GB/T18136—2008《交流高压静电防护服装及试验方法》和DL/T 1238—2013《1000 kV交流系统用静电防护服装》中的关键技术指标进行了探讨。对比分析了两个... 详细信息

为推动标准的有效推广和实施,以及交流高压静电防护服装的科学制备和合理适用,对GB/T18136—2008《交流高压静电防护服装及试验方法》和DL/T 1238—2013《1000 kV交流系统用静电防护服装》中的关键技术指标进行了探讨。对比分析了两个标准的异同点,并提出了合理化建议,为标准的修订提供参考。认为:应进一步增加衣料撕破强力、透湿量、色牢度、甲醛含量、pH值、接缝强力等考核指标,并明确相关考核指标的测试参数。

关键词：交流高压静电防护服装连接带衣料电阻屏蔽效率耐磨性能透气率断裂伸长率

大气污染物短期暴露对急性卒中日入院人数的影响:中国太原市的时间序列研究

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国际脑血管病杂志 2024年第3期32卷 180-185页

作者：李晓峰李泽星田芳怡宋士娜王少帅李常新李景鑫山西医科大学第一临床医学院太原030001 临汾市人民医院全科医学科临汾041000 山西省人民医院神经内科太原030012 太钢总医院老年内科太原030008 中国气象科学研究院灾害天气国家重点实验室北京100081

目的探讨大气污染物短期暴露对太原市急性卒中日入院人数的影响。方法连续收集2018年1月1日至2019年12月31日山西省太原市不同区域3家大型医院卒中患者的病例资料,同期收集太原市大气污染物的日均浓度及气象资料。采用Spearman秩相关分... 详细信息

目的探讨大气污染物短期暴露对太原市急性卒中日入院人数的影响。方法连续收集2018年1月1日至2019年12月31日山西省太原市不同区域3家大型医院卒中患者的病例资料,同期收集太原市大气污染物的日均浓度及气象资料。采用Spearman秩相关分析气象因素与大气污染物的相关性,采用基于时间序列研究分析的广义加性模型(generalized additive model,GAM)探讨大气污染物对卒中日入院人数的影响以及滞后效应,并对不同性别及年龄(≤64岁、65~74岁和≥75岁)患者进行分层分析。结果2018至2019年期间,在3家大型医院共收集急性卒中患者4921例,日平均卒中入院为6.74例。其中,缺血性卒中、脑出血和蛛网膜下腔出血患者分别为4310例(87.6%)、521例(10.6%)和90例(1.8%)。GAM分析显示,PM_(2.5)、PM_(10)以及SO_(2)短期暴露与卒中日入院人数存在显著相关性,三者均在发病当日和滞后3 d时对卒中日入院人数有显著影响;在发病当日达到效应最大值,PM_(2.5)、PM_(10)、SO_(2)平均浓度每增高10μg/m3,卒中日入院人数分别增加1.48%[95%置信区间(confidence interval,CI)0.46%~2.53%]、0.80%(95%CI 0.25%~1.36%)和2.80%(95%CI 0.76%~4.88%)。分层分析显示,在男性患者中,PM_(2.5)、PM_(10)、SO_(2)以及CO暴露对卒中日入院人数的影响更为显著,而在女性中仅PM_(10)呈阳性结果。年龄分层分析显示,PM_(2.5)会显著增加≥75岁人群的卒中日入院人数。结论大气污染物PM_(2.5)、PM_(10)、SO_(2)、CO短期暴露在一定程度上会增加太原市居民的卒中日入院人数,在男性和年龄≥75岁人群中更为显著。

关键词：空气污染空气污染物环境暴露卒中住院危险因素

Heterogeneous integrated phase modulator based on two-dimensional layered materials

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Photonics Research 2022年第6期10卷 1401-1407页

作者： HAO CHEN zexing ZHAO ZIMING ZHANG GUOQING WANG JIATONG li ZHENYUAN SHANG MENGYU ZHANG KAI GUO JUNBO YANG PEIGUANG YAN College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060China Institute of Systems Engineering AMSBeijing 100039China College of liberal Arts and Sciences National University of Defense TechnologyChangsha 410073China

Silicon nitride,with ultralow propagation loss and a wide transparency window,offers an exciting platform to explore integrated photonic devices for various emerging applications.It is appealing to combine the intrinsic optical properties of two-dimensional layered materials with high-quality optical waveguides and resonators to achieve functional devices in a single chip.Here we demonstrate a micro-ring resonator-based phase modulator integrated with few-layer MoS_(2).The ionic liquid is employed directly on the surface of MoS_(2) to form a capacitor configuration.The effective index of the composite MoS_(2)–SiN waveguide can be modulated via adjusting bias voltages to achieve different charged doping induced electro-refractive responses in MoS_(2) film.The maximum effective index modulation of the composite MoS_(2)–SiN waveguide can be achieved to 0.45×10^(−3).The phase tuning efficiency is measured to be 29.42 pm/V,corresponding to a V_(π)L of 0.69 V·cm.Since the micro-ring resonator is designed near the critical coupling regime,the coupling condition between the bus waveguide and micro-ring resonator can also be engineered from under-coupling to over-coupling regime during the charged doping process.That can be involved as a degree of freedom for the coupling tailoring.The ability to modulate the effective index with two-dimensional materials and the robust nature of the heterostructure integrated phase modulator could be useful for engineering reliable ultra-compact and low-power-consumption integrated photonic devices.

关键词： modulator waveguide resonator

Co-Ru alloy nanoparticles decorated onto two-dimensional nitrogen doped carbon nanosheets towards hydrogen/oxygen evolution reaction and oxygen reduction reaction

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Journal of Energy Chemistry 2023年第12期87卷 286-294,I0008页

作者： Huizhen Wang Pengfei Yang Xiaoyuan Sun Weiping Xiao Xinping Wang Minge Tian Guangrui Xu Zhenjiang li Yubing Zhang Fusheng liu Lei Wang zexing Wu Key Laboratory of Eco-chemical Engineering Ministry of EducationInternational Science and Technology Cooperation Base of Eco-chemical Engineering and Green ManufacturingCollege of Chemistry and Molecular EngineeringQingdao University of Science and TechnologyQingdao 266042ShandongChina College of Science Nanjing Forestry UniversityNanjing 210037JiangsuChina Scientific Green(Shandong)Environmental Technology Co.Ltd Jining Economic Development ZoneJining 272499ShandongChina School of Materials Science and Engineering Qingdao University of Science and TechnologyQingdao 266042ShandongChina College of Chemical Engineering Qingdao University of Science and TechnologyQingdao 266042ShandongChina

Constructing highly-efficient electrocatalysts toward hydrogen evolution reaction(HER)/oxygen evolution reaction(OER)/oxygen reduction reaction(ORR)with excellent stability is quite important for the development of renewable energy-related applications.Herein,Co-Ru based compounds supported on nitrogen doped two-dimensional(2D)carbon nanosheets(NCN)are developed via one step pyrolysis procedure(Co-Ru/NCN)for HER/ORR and following low-temperature oxidation process(Co-Ru@RuO_(x)/NCN)for OER.The specific 2D morphology guarantees abundant active sites exposure.Furthermore,the synergistic effects arising from the interaction between Co and Ru are crucial in enhancing the catalytic performance.Thus,the resulting Co-Ru/NCN shows remarkable electrocatalytic performance for HER(70 mV at 10 mA cm^(-2))in 1 M KOH and ORR(half-wave potential E_(1/2)=0.81 V)in 0.1 M KOH.Especially,the Co-Ru@RuO_(x)/NCN obtained by oxidation exhibits splendid OER performance in both acid(230 mV at 10 mA cm^(-2))and alkaline media(270 mV at 10 mA cm^(-2))coupled with excellent stability.Consequently,the fabricated two-electrode water-splitting device exhibits excellent performance in both acidic and alkaline environments.This research provides a promising avenue for the advancement of multifunctional nanomaterials.

关键词： Electrocatalyst 2D Carbon nanosheet Hydrogen/oxygen evolution reaction Oxygen reduction reaction Water-splitting

Relationships between climate change, agricultural development and social stability in the Hexi Corridor over the last 2000 years

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Science China Earth Sciences 2019年第9期62卷 1453-1460页

作者： Yanpeng li Quansheng GE Huanjiong WANG Haolong liU zexing TAO Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences

This case study of the Hexi Corridor, Northwestern China, utilizes statistical methods to estimate quantitatively the interaction at a regional level between climate change, ancient social developments, and political coping strategies over the past 2000 years. The data is sourced from high-resolution reconstructions of climate series(temperature and precipitation), and historical records of cultivated land, war, population, and changes in regional administrative systems. The results show that moisture conditions played a more significant role than temperature in driving land reclamation in the Hexi Corridor. Analysis also showed a negative correlation between war frequency and the area of cultivated land in the Corridor over 20-year time intervals. Population growth was found to have a significant positive correlation with the cultivated land area during the study period. The results indicate that a climate-induced decline in agricultural production and the subsequent fluctuations in population could act as a trigger for social unrest, which is especially true at the mutual decadal time-scales. However, the interaction with administrative reform also suggests that, in the face of social and economic turmoil, a reasonable administrative hierarchy could strengthen the social governance of regional government, and promote social stability and economic development at a regional level. The study substantiates this notion with empirical quantitative evidence.

关键词： Climate change Agricultural development Social stability Regional administrative reform Hexi Corridor