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Fabrication of wear-resistant PA6 composites with superior thermal conductivity and mechanical properties via constructing highly oriented hybrid network of SiC-packed BN platelets

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Journal of Materials Science & Technology 2023年第15期146卷 200-210页

作者： Jing Chen jiaming Zhu Yang Pan Hong wu Shaoyun Guo Jianhui Qiu The State Key Laboratory of Polymer Materials Engineering Sichuan Provincial Engineering Laboratory of PlasticRubber Complex Processing TechnologyPolymer Research Institute of Sichuan UniversityChengdu 610065China Jiangsu Industrial Technology Research Institute of Advanced Polymer Materials Nanjing 211899China Department of Mechanical Engineering Faculty of Systems Science and TechnologyAkita Prefectural UniversityAkita 015-0055Japan

Herein,a strong extensional and shearing field was introduced to construct highly oriented hybrid networks of silicon carbide(SiC)-packed boron nitride(BN)platelets to fabricate high-performance wearresistant PA6 composites.Results show that in-plane and through-plane thermal conductivity(TC)of the prepared PA6 composites with a total filler loading of 20 wt.%reached 1.31 and 0.35 W/(m K),352%and 25%higher than those of pure PA6,respectively.It is attributed to the highly oriented hybrid network that facilitates the formation of efficient thermal conductivity pathways.Temperature monitoring results during friction confirm that high TC favors the friction heat dissipation performance.Meanwhile,the yield strength of PA6 composites increased by 39.1%and they still have excellent ductility with an elongation at break of 207.1%.Finally,the wear rate of PA6 composites decreased sharply by 92.5%.This method can be used to manufacture advanced linear bearing and guideway parts,etc。

关键词： Polymer-matrix composites(PMCs) Hybrid Wear Thermal properties

父母婚姻状况对中学生消极情绪和非自杀性自伤行为的影响:一项多中心横断面研究

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中国全科医学 2024年第14期27卷 1708-1715页

作者：任晓虹岑雨罗静周玉玲何金龙林岑吴大鹏罗家明川北医学院附属医院风湿免疫科四川省南充市637000 川北医学院精神卫生学院四川省南充市637000

背景父母婚姻状况对青少年负性心理及非自杀性自伤行为(NSSI)影响的研究报道较少,且现有的研究样本量较小。目的探究父母婚姻状况与中学生消极情绪和NSSI的关联,为中学生NSSI的防控提供参考。方法2020年3—4月,采用分层随机抽样法对南... 详细信息

背景父母婚姻状况对青少年负性心理及非自杀性自伤行为(NSSI)影响的研究报道较少,且现有的研究样本量较小。目的探究父母婚姻状况与中学生消极情绪和NSSI的关联,为中学生NSSI的防控提供参考。方法2020年3—4月,采用分层随机抽样法对南充市及周边20个乡镇、67所中学的学生进行问卷调查。调查人员将问卷输入问卷星平台生成二维码,学校发放二维码给家长或学生监护人。问卷包括一般信息问卷、渥太华自残量表(OSI)和中文版抑郁焦虑压力量表-21(DASS-21)。统计中学生NSSI、抑郁、焦虑、压力检出率,并分析影响中学生NSSI、抑郁、焦虑和压力的相关因素。结果本调查共对23所中学的8785名学生发放问卷,最终获得有效问卷8606份,有效回收率98.0%。8606名中学生中男4540名(52.8%)、女4066名(47.2%);初中5937名(69.0%),高中1028名(11.9%),职业高中1641名(19.1%);双亲家庭7274名(84.5%),父母离异单亲787名(9.1%),父母离异再婚545名(6.4%)。本次调查的中学生NSSI检出率为5.6%(486/8606),抑郁检出率为21.9%(1884/8606),焦虑检出率为26.8%(2305/8606),压力检出率为12.3%(1060/8606)。多因素Logistic回归分析结果显示,在所有中学生中,与男生相比,女生发生NSSI、焦虑的风险较大(OR=2.363,95%CI=1.946~2.868;OR=1.195,95%CI=1.086~1.315);与初中生相比,职业高中生发生NSSI、抑郁、焦虑、压力的风险较大(OR=1.847,95%CI=1.494~2.284;OR=1.886,95%CI=1.667~2.134;OR=1.857,95%CI=1.141~1.532;OR=1.527,95%CI=1.309~1.781);与双亲家庭的中学生相比,离异单亲、离异再婚家庭的中学生NSSI、抑郁、焦虑、压力的风险较大(离异单亲:OR=2.194,95%CI=1.699~2.834;OR=1.563,95%CI=1.326~1.843;OR=1.573,95%CI=1.346~1.839;OR=1.417,95%CI=1.153~1.741;离异再婚:OR=2.207,95%CI=1.638~2.975;OR=1.863,95%CI=1.543~2.249;OR=1.796,95%CI=1.499~2.153;OR=1.821,95%CI=1.453~2.282);与长期由双亲照顾的中学生相比,长期由父亲单独照顾、母亲单独照顾、祖父母照顾发生NSSI、抑郁、焦虑的风险较大(父亲单独照顾:OR=2.045,95%CI=1.366~3.062;OR=1.633,95%CI=1.289~2.145;OR=1.373,95%CI=1.069~1.762;母亲单独照顾:OR=1.772,95%CI=1.141~2.751;OR=1.435,95%CI=1.095~1.882;OR=1.513,95%CI=1.174~1.951;祖父母照顾:OR=2.465,95%CI=1.918~3.168;OR=1.783,95%CI=1.513~2.100;OR=1.843,95%CI=1.577~2.154),由母亲单独照顾、祖父母照顾发生压力的风险较大(OR=1.604,95%CI=1.166~2.207;OR=1.678,95%CI=1.375~2.049)(P<0.05)。结论中学生的NSSI、抑郁、焦虑、压力与父母离异及照顾者有关,因此,需要对处于这些情况的中学生给予特别关注和干预。

关键词：抑郁焦虑情绪困扰非自杀自伤行为父母婚姻状况负性情绪中学生心理学,青春期

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活性氧与线粒体自噬在牙周炎中的作用

口腔医学 2024年第3期44卷 237-240页

作者：张家铭段燕武云霞山西医科大学口腔医学院·口腔医院山西太原030001 山西省人民医院口腔科山西太原030001

活性氧(reactive oxygen species,ROS)与机体抗氧化防御系统的动态平衡失调是导致牙周炎发生的重要原因之一,线粒体自噬(mitophagy)是机体自身清除损伤线粒体以维持其数量与质量的机制。ROS水平升高会导致线粒体自噬,自噬具有促进细胞... 详细信息

活性氧(reactive oxygen species,ROS)与机体抗氧化防御系统的动态平衡失调是导致牙周炎发生的重要原因之一,线粒体自噬(mitophagy)是机体自身清除损伤线粒体以维持其数量与质量的机制。ROS水平升高会导致线粒体自噬,自噬具有促进细胞死亡或阻止细胞凋亡的双重作用,同时可以清除ROS。该文就ROS和线粒体自噬在牙周炎中的作用及两者之间的关系作一综述。

关键词：牙周炎活性氧线粒体自噬

3种最大摄氧量实验室直接测试方法结果比较、回归分析与应用

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中国运动医学杂志 2024年第1期43卷 29-38页

作者：林岭吴文腾罗嘉铭樊凯文王华叶李志广段小平宁波大学体育学院宁波315211 内蒙古自治区冬季运动项目管理中心呼和浩特010000 广东省体育科学研究所广州510663

目的:通过实验研究比较3种常用最大摄氧量(VO2max)实验室直接测试法测试结果间差异,探讨不同方法测试结果间线性回归关系,便于不同方法测试结果间的互相预测与实现可比性。方法:采用整群抽样、组内交互设计的准实验研究,对20名越野滑雪... 详细信息

目的:通过实验研究比较3种常用最大摄氧量(VO2max)实验室直接测试法测试结果间差异,探讨不同方法测试结果间线性回归关系,便于不同方法测试结果间的互相预测与实现可比性。方法:采用整群抽样、组内交互设计的准实验研究,对20名越野滑雪男运动员分别采用Bruce法(方法1)、功率自行车90秒递增负荷法(方法2)、跑台1分钟递增负荷法(方法3)3种方法进行最大摄氧量直接测试,每两种方法测试间歇期为1周。自变量为3种最大摄氧量测试方法,因变量为最大摄氧量。结果:(1)3种测试方法最大摄氧量的组间均值方差分析结果显示组间差异具有统计学意义(P方法3>方法2,差异均具有统计学意义(P<0.05);(2)3种方法测试结果个体差值的频数统计显示,测试方法1的最大摄氧量高于方法2约6 ml/min·kg,高于方法3约3 ml/min·kg;(3)同等跑台跑速下,方法3的平均血乳酸高于方法1,且方法3达有氧阈、无氧阈的跑速均低于方法1约一个速度单位(1 km/h);(4)方法1与方法2、方法1与方法3测试结果的线性回归分析显示,回归模型与回归系数均具有统计学意义(P<0.001),线性模型检验拟合度R2分别为9.25、9.05。结论:(1)Bruce法在评价运动员阶段最大摄氧量的最大值方面效果最好,其它两种方法与其存在线性回归关系,可用于不同测试方法结果间的互相预测;(2)不同项目、不同水平的运动员可分别采用适合其能力特点的方法进行最大摄氧量测试;(3)有氧阈、无氧阈对应的跑速、心率变化区间可作为把控有氧阈、无氧阈训练强度的有效、便捷方法。

关键词：最大摄氧量跑台测试法功率自行车测试法差值分布回归分析

Effects of probiotics and its fermented milk on constipation: a systematic review

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Food Science and Human Wellness 2023年第6期12卷 2124-2134页

作者： jiaming Yan Meiling wu Wei Zhao Lai-Yu Kwok Wenyi Zhang Key Laboratory of Dairy Biotechnology and Engineering Ministry of EducationInner Mongolia Agricultural UniversityHohhot 010018China Key Laboratory of Dairy Products Processing Ministry of AgricultureInner Mongolia Agricultural UniversityHohhot 010018China

This study reviewed clinical evidence of probiotics-mediated effects on constipation.Four databases were used in the literature searches,namely Cochrane Library,Embase,Pubmed,and Web of Science.The last retrieval time was March 2021.Collected data were analyzed by Review Manager(version 5.3)and Stata(version 14).The primary search retrieved 8418 articles after removing duplicates.Eventually,26 studies were included in the meta-analysis.Administration of probiotics signifi cantly increased stool frequency(MD:1.15 times/week;95%CI:0.59 to 1.70;Pothers(tablets,powder)>fermented milk.

关键词： Constipation Probiotics Fermented milk Meta-analysis Dosage form

Vulnerability Assessment of Distributed Load Shedding Algorithm for Active Distribution Power System Under Denial of Service Attack

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CSEE Journal of Power and Energy Systems 2023年第6期9卷 2066-2075页

作者： Weiwei Xu jiaming Weng Boliang Lou Xiaoming Huang Hongyang Huang Jun wu Dan Zhou the School of Electronic Information and Electrical Engineering Shanghai Jiao Tong UniversityShanghai 200240China State Grid Zhejiang Electric Power Research Institute Hangzhou 310014China the State Grid Zhejiang Electric Power Research Institute Hangzhou 310014China the College of Information Engineering Zhejiang University of TechnologyHangzhou 310023China

In order to deal with frequency deviation andsupply-demand imbalance in active distribution power system, inthis paper a distributed under frequency load shedding (UFLS)strategy is proposed. Different from conventional centralizedUFLS schemes, no centralized master station gathering all thebuses’ information is required. Instead, each bus decides itsown load shedding amount by only relying on limited peer-topeer communication. However, such UFLS strategy may sufferfrom some unexpected cyber-attacks such as integrity attacksand denial of service (DoS) attack. The latter DoS attack aimsto degrade the system performance by jamming or breakingthe communication, which is of high probability to happen inpractical power system. To assess the vulnerability of proposeddistributed UFLS algorithm, the effect of DoS attack on distributed average consensus algorithm is theoretically derived,which indicates that the final consensus value can be estimatedby a given attack probability. It is also investigated that such DoSattack does harm to the load shedding amount and finally affectsthe system frequency performance in the active distributionpower system. Several case studies implemented on an IEEE33-bus active distribution power system are conducted to verifythe effectiveness of the theoretical findings and investigate thevulnerability of the considered power system.

关键词： Active distribution power system cyber security denial of service attack distributed average consensus load shedding

Effect of Zr on phase separation,mechanical and corrosion behavior of heterogeneous CoCrFeNiZr_(x) high-etropy alloy

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Journal of Materials Science & Technology 2022年第14期109卷 76-85页

作者： wu Qi Wenrui Wang Xiao Yang Lu Xie jiaming Zhang Dongyue Li Yong Zhang School of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China Key Laboratory of Fluid Interaction with Material Ministry of EducationBeijing 100083China Key Laboratory of Cryogenics Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

CoCrFeNi high entropy alloy(HEA)has attracted extensive attention due to its excellent corrosion resistance,but the low strength limits its engineering application prospects.In order to develop CoCrFeNi based HEAs with high strength,ductility and corrosion resistance,the effects of Zr content on the microstructure,mechanical properties and corrosion resistance of heterogeneous CoCrFeNiZr_(x)(x=0,0.25,0.5 and 1)HEAs were investigated in this work.The results indicate that the increase of Zr content can significantly affect the phase stability of the alloy,and promote the formation of intermetallic compounds(Ni_(7)Zr_(2)and/or Laves phase)and the transformation of solid solution from face-centered cubic(FCC)structure(x=0,0.25 and 0.5)to body-centered cubic(BCC)structure(x=1).Reasonable control of the Zr content can endow the alloy excellent comprehensive properties.Especially,for CoCrFeNiZr_(0.25) alloy,composed of FCC matrix and a small amount of Ni_(7)Zr_(2)phases,the yield strength(~655 MPa)is increased by nearly four times higher than that of Zr-free alloy,and it also has good ductility(fracture stain>50%).Meanwhile,the corrosion resistance of CoCrFeNiZr_(0.25) alloy is better than that of SS304.The EIS results show that the addition of Zr reduces the stability of the passive film on the alloy,which can be related to the content of the beneficial oxide in the passive film and the thickness of the passive film through XPS analysis.Moreover,the work functions of different phases in CoCrFeNiZr_(x)alloys were obtained by firstprinciples calculations,which further confirmed the selective corrosion mechanism of the CoCrFeNiZr_(x) alloy combining the experimental results.

关键词： High-entropy alloy Microstructure Corrosion resistance First-principles Work function

Recent research progress on the phase-field model of microstructural evolution during metal solidification

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International Journal of Minerals,Metallurgy and Materials 2023年第11期30卷 2095-2111页

作者： Kaiyang Wang Shaojie Lv Honghui wu Guilin wu Shuize Wang Junheng Gao jiaming Zhu Xusheng Yang Xinping Mao Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Carbon NeutralityUniversity of Science and Technology BeijingBeijing 100083China Institute of Steel Sustainable Technology Liaoning Academy of MaterialsShenyang 110004China Institute of Materials Intelligent Technology Liaoning Academy of MaterialsShenyang 110004China School of Civil Engineering Shandong UniversityJinan 250061China Department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China

Solidification structure is a key aspect for understanding the mechanical performance of metal alloys,wherein composition and casting parameters considerably influence solidification and determine the unique microstructure of the alloys.By following the principle of free energy minimization,the phase-field method eliminates the need for tracking the solid/liquid phase interface and has greatly accelerated the research and development efforts geared toward optimizing metal solidification microstructures.The recent progress in the application of phasefield simulation to investigate the effect of alloy composition and casting process parameters on the solidification structure of metals is summarized in this review.The effects of several typical elements and process parameters,including carbon,boron,silicon,cooling rate,pulling speed,scanning speed,anisotropy,and gravity,on the solidification structure are discussed.The present work also addresses the future prospects of phase-field simulation and aims to facilitate the widespread applications of phase-field approaches in the simulation of microstructures during solidification.

关键词： solidification process phase-field models microstructure evolution alloy composition casting process parameters

Air-Stable Ultrabright Inverted Organic Light-Emitting Devices with Metal Ion-Chelated Polymer Injection Layer

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Nano-Micro Letters 2022年第1期14卷 239-249页

作者： Shihao Liu Chunxiu Zang jiaming Zhang Shuang Tian Yan wu Dong Shen Letian Zhang Wenfa Xie Chun-Sing Lee State Key Laboratory of Integrated Optoelectronics College of Electronics Science and EngineeringJilin University2699 Qianjin StreetChangchun 130012People’s Republic of China Department of Chemistry Center of Super-Diamond and Advanced Films(COSDAF)City University of Hong KongKowloonHong KongPeople’s Republic of China

Here,this work presents an air-stable ultrabright inverted organic lightemitting device(OLED)by using zinc ionchelated polyethylenimine(PEI)as electron injection layer.The zinc chelation is demonstrated to increase the conductivity of the PEI by three orders of magnitude and passivate the polar amine groups.With these physicochemical properties,the inverted OLED shows a record-high external quantum efficiency of 10.0% at a high brightness of 45,610 cd m^(-2) and can deliver a maximum brightness of 121,865 cd m^(-2).Besides,the inverted OLED is also demonstrated to possess an excellent air stability(humidity,35%)with a half-brightness operating time of 541 h@1000 cd m^(-2) without any protection nor encapsulation.

关键词： Air stability Ultrabright Electron injection Metal ion chelation Inverted organic light-emitting device