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high temperature induced“glaze”layer formed in HVOF-sprayed NiCrWMoCuCBFe coating and its wear reduction mechanism

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Friction 2022年第9期10卷 1424-1438页

作者： Yijing WANG Xiaoqin ZHAO Enkang HAO Zhenyu BU Yulong AN Huidi ZHOU Jianmin CHEN State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

The in-situ formation of oxides on alloy surface induced by high temperature can effectively reduce wear and resist oxidation.In consideration of the solid solution strengthening effect and great oxidation resistance of additional elements at elevated temperature,the NiCrWMoCuCBFe coating was prepared by high velocity oxygen flame(HVOF)spraying technology,and its tribological behavior was scrutinized from 25 to 800°C.By means of high temperature Vickers hardness tester and high temperature X-ray diffractometer,the mechanical properties and microstructures of NiCrWMoCuCBFe coating were measured.And the effect of the mechanical properties and microstructures of the coating on tribological performance was discussed in detail.The results showed both its friction coefficient(0.37)and wear rate(5.067×10^(−6)mm^(3)·N^(−1)·m^(−1))at 800℃ were the lowest,which was mainly related to the formation of“glaze”layer on the coating surface at high temperature.The glaze layer consisted of two parts,which were NiCr_(2)O_(4)oxide film with the ability of interlaminar slip formed in the outer layer and nano-grains existed in the inner layer.Worth mentioning,these nano-grains provided bearing capability while the oxide film was vital to reduce wear rate and friction coefficient.As the ambient temperature increased,many hard oxides were produced on the wear scars,including NiO,Cr_(2)O_(3),MoO_(3),and Mo_(2)C.They can improve tribological and mechanical properties of NiCrWMoCuCBFe coating at a wide temperature range.

关键词： high temperature wear and friction NiCrWMoCuCBFe coating in-situ oxidation glaze layer mechanical properties

high temperature treatment induced production of unreduced 2n pollen in Camellia oleifera

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Horticultural Plant Journal 2024年第3期10卷 879-896页

作者： Hongda Deng Xiaoyu Zhang Song Sheng Yuxun Huang Ziqi Ye Tongyue Zhang Xing Liu Zhiqiang Han The Laboratory of Forestry Genetics Central South University of Forestry and TechnologyChangshaHunan 410004China Yuelushan Laboratory ChangshaHunan 410128China Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees of Ministry of Education Central South University of Forestry and TechnologyChangshaHunan 410004China National Forest and Seedling Workstation of Hunan Province The Forestry Department of Hunan ProvinceChangshaHunan 410004China

Unreduced gametes through chromosome doubling play a major role in the process of plant polyploidization.Our previous work confirmed that Camellia oleifera can produce natural 2n pollen,and it is possible to induce the 2n pollen formation by high temperature treatment.This study focused on the optimization of the 2n pollen induction technique and the mechanisms of high temperature-induced2n pollen formation in C.oleifera.We found that the optimal protocol for inducing 2n pollen via high temperature was to perform 45℃with4 h at the prophaseⅠstage of the pollen mother cells(PMCs).Meanwhile,high temperature significantly decreased the yield and fertility of2n pollen.Through the observation of meiosis,abnormal chromosome and cytological behaviour was discovered under high-temperature treatment,and we confirmed that the formation of 2n pollen is caused by abnormal cell plate.Based on weighted gene co-expression network analysis,fifteen hub genes related to cell cycle control were identified.After male flower buds were exposed to heat shock,polygalacturonase gene(CoPGX3)was significantly upregulated.We inferred that high temperature causes the CoPGX3 gene to be overexpressed and that CoPGX3 is redistributed into the cytosol where it degrades cytoplasmic pectin,which leads to an abnormal cell plate.Furthermore,abnormal cytokinesis resulted in the formation of dyads and triads,and PMCs divided to produce 2n pollen.Our findings provide new insights into the mechanism of 2n pollen induced by high temperature in a woody plant and lay a foundation for further ploidy breeding of C.oleifera.

关键词： Camellia oleifera Pollen mother cells(PMCs) high temperature Meiosis 2n pollen CoPGX3

high temperature H_(2)S selective oxidation on a copper-substituted hexaaluminate catalyst: A facile process for treating low concentration acid gas

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Chinese Chemical Letters 2022年第3期33卷 1279-1282页

作者： Xin Xu Ganggang Li Fenglian Zhang Guoxia Jiang Zhengping Hao Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China National Engineering Laboratory for VOCs Pollution Control Material&Technology Research Center for Environmental Material and Pollution Control TechnologyUniversity of Chinese Academy of SciencesBeijing 101408China

H_(2)S selective catalytic oxidation technology is a prospective way for the treatment of low concentration acid gas with simple process operation and low investment. However, undesirable results such as large formation of SO_(2) and catalyst deactivation inevitably occur, due to the temperature rise of fixed reaction bed caused by the exothermic reaction. Catalyst with high activity in wide operating temperature window, especially in high temperature range, is urgently needed. In this paper, a series of copper-substituted hexaaluminate catalysts (LaCu_(x), x = 0, 0.5, 1, 1.5, 2, 2.5) were prepared and investigated for the H_(2)S selective oxidation reaction at high temperature conditions (300-550℃). The LaCu_(1) catalyst exhibited excellent catalytic performance and great stability, which was attributed to the best reductive properties and proper pore structure. Besides, two facile deep processing paths were proposed to eliminate the remaining H_(2)S and SO_(2) in the tail gas.

关键词： Low concentration acid gas H_(2)S selective oxidation high temperature Hexaaluminate catalyst

high temperature oxidation resistance of CrN/(Ti,Al,Zr,Cr)N bilayer films deposited by multi-arc ion plating

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Journal of Iron and Steel Research(International) 2017年第3期24卷 343-349页

作者： Shi-lu Zhao Zhen Zhang Jun Zhang Jian-ming Wang Zheng-gui Zhang Shuang-hong Wang School of Mechanical Engineering Shenyang University Shenyang 110044 Liaoning China Paint Shop Planning BMW Brilliance Automotive Ltd. Shenyang 110113 Liaoning China

CrN/（Ti,Al,Zr,Cr） N bilayer films were successfully deposited on cemented carbide（ WC-8% Co） substrates by multi-arc ion plating process using two Ti-Al-Zr alloy targets and one pure Cr target. As a result of bilayered structure and addition of alloying elements（ e. g. Al and Cr）,the films exhibited excellent high temperature oxidation resistance under both short-term isothermal（ up to 800 ℃） and long-term cyclic（ up to 600 ℃） exposure conditions. Combined with pre-established outstanding tribological properties（ e. g. maximum hardness of 4 000HV0. 01 and maximum adhesion strength over 200 N）,these observations make such films quite a promising candidate to extend the cutting tool life span and boost the performance in high-productivity,high-speed and high-feed cutting or in dry machining conditions.

关键词： Nitride Bilayer film Cemented carbide Multi-arc ion plating high temperature oxidation resistance

high-temperature tribological behaviors of a Cr-Si co-alloyed layer on TA15 alloy

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Chinese Journal of Aeronautics 2017年第2期30卷 846-855页

作者： Lu Haifeng Miao Qiang Liang Wenping Wang Fang Ding Zheng Xia Jinjiao College of Material Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

A Cr-Si co-alloyed layer was successfully deposited on TA15 alloy by the double glow plasma surface technology to improve its poor wear resistance at elevated temperature.The microstructure,composition,and phase structure of the layer were investigated by SEM,EDS,and XRD.The tribological behaviors of the Cr-Si co-alloyed layer at 20 ℃ and 500 ℃ were analyzed in details.The results indicated that the friction coefficient and wear rate of the Cr-Si coalloyed layer at 20 ℃ and 500 ℃ were much lower than those of the substrate,which was due to higher hardness and superior elastic modulus.This layer may become an approach to effectively improving the wear resistance of TA15 alloy at elevated temperature.

关键词： Cr-Si layer high temperature TA 15 alloy Tribological behavior Wear mechanism

high-temperature tribological performance of functionally graded Stellite 6/WC metal matrix composite coatings manufactured by laser-directed energy deposition

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Friction 2024年第3期12卷 522-538页

作者： Marta OSTOLAZA Alaitz ZABALA Jon Inaki ARRIZUBIETA Iñigo LLAVORI Nagore OTEGI Aitzol LAMIKIZ Department of Mechanical Engineering University of the Basque Country UPV/EHUPlaza Torres Quevedo 1Bilbo 48013Spain Faculty of Engineering Mechanics and Industrial ProductionMondragon UnibertsitateaLoramendi 4Mondragon 20500Spain

Wear-driven tool failure is one of the main hurdles in the industry.This issue can be addressed through surface coating with ceramic-reinforced metal matrix composites.However,the maximum ceramic content is limited by cracking.In this work,the tribological behaviour of the functionally graded WC-ceramic-particlereinforced Stellite 6 coatings is studied.To that end,the wear resistance at room temperature and 400°C is investigated.Moreover,the tribological analysis is supported by crack sensitivity and hardness evaluation,which is of utmost importance in the processing of composite materials with ceramic-particle-reinforcement.Results indicate that functionally graded materials can be employed to increase the maximum admissible WC content,hence improving the tribological behaviour,most notably at high temperatures.Additionally,a shift from abrasive to oxidative wear is observed in high-temperature wear testing.

关键词： friction coating metal matrix composite functionally graded materials high temperature laserdirected energy deposition

ATF6 aggravates apoptosis in early porcine embryonic development by regulating organelle homeostasis under high-temperature conditions

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动物学研究(英文) 2023年第5期44卷 848-859页

作者： Ming-Hong Sun Wen-Jie Jiang Xiao-Han Li Song-Hee Lee Geun Heo Dongjie Zhou Zhi Chen Xiang-Shun Cui Department of Animal Science Chungbuk National UniversityCheongjuSouth Korea 28644Korea College of Animal Science and Technology Yangzhou UniversityYangzhouJiangsu 225009China

Activating transcription factor 6(ATF6),one of the three sensor proteins in the endoplasmic reticulum(ER),is an important regulator of ER stress-induced apoptosis.ATF6 resides in the ER and,upon activation,is translocated to the Golgi apparatus,where it is cleaved by site-1 protease(S1P)to generate an amino-terminal cytoplasmic fragment.Although recent studies have made progress in elucidating the regulatory mechanisms of ATF6,its function during early porcine embryonic development under high-temperature(HT)stress remains unclear.In this study,zygotes were divided into four groups:control,HT,HT+ATF6 knockdown,and HT+PF(S1P inhibitor).Results showed that HT exposure induced ER stress,which increased ATF6 protein expression and led to a decrease in the blastocyst rate.Next,ATF6 expression was knocked down in HT embryos under microinjection of ATF6 double-stranded RNA(dsRNA).Results revealed that ATF6 knockdown(ATF6-KD)attenuated the increased expression of CHOP,an ER stress marker,and Ca2+release induced by HT.In addition,ATF6-KD alleviated homeostasis dysregulation among organelles caused by HT-induced ER stress,and further reduced Golgi apparatus and mitochondrial dysfunction in HT embryos.AIFM2 is an important downstream effector of ATF6.Results showed that ATF6-KD reduced the occurrence of AIFM2-mediated embryonic apoptosis at HT.Taken together,our findings suggest that ATF6 is a crucial mediator of apoptosis during early porcine embryonic development,resulting from HT-induced ER stress and disruption of organelle homeostasis.

关键词： ATF6 Embryo high temperature ER stress Organelle homeostasis

Global Burden of Cardiovascular Disease Attributable to high temperature in 204 Countries and Territories from 1990 to 2019

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Biomedical and Environmental Sciences 2023年第3期36卷 222-230页

作者： HONG Le YAN Miao Miao ZHANG Yun Quan WANG Kai WANG Ya Qi LUO Si Qi WANG Fang Department of Epidemiology and Biostatistics School of Public HealthWuhan University of Science and TechnologyWuhan 430065HubeiChina Department of Biostatistics School of Public HealthXuzhou Medical UniversityXuzhou 221004JiangsuChina

Objective This study aimed to estimate spatiotemporal variations of global heat-related cardiovascular disease(CVD)burden from 1990 to 2019.Methods Data on the burden of heat-related CVD were derived from the Global Burden of Disease Study 2019.Deaths and disability-adjusted life years(DALYs)were used to quantify heat-induced CVD burden.We calculated the age-standardized mortality rate(ASMR)and DALY rate(ASDR)per 100,000population to compare this burden across regions.Generalized linear models were applied to evaluate estimated annual percentage changes(EAPC)for temporal trends from 1990 to 2019.The correlation between the socio-demographic index(SDI)and age-standardized rate was measured using the Spearman rank test.Results Heat-induced CVD caused approximately 90 thousand deaths worldwide in 2019.Global ASMR and ASDR of heat-related CVD in 2019 were 1.17[95%confidence interval(CI):0.13-1.98]and 25.59(95%CI:2.07-44.17)per 100,000 population,respectively.The burden was significantly increased in middle and low-SDI regions and slightly decreased in high-SDI regions from 1990 to 2019.ASMR showed an upward trend,with the most considerable increase in low-latitude countries.We observed a negative correlation between SDI and EAPC in ASMR(rs=-0.57,P<0.01)and ASDR(rs=-0.59,P<0.01)among204 countries.Conclusion Heat-attributable CVD burden substantially increased in most developing countries and tropical regions.

关键词： high temperature Cardiovascular disease Global disease burden Climate change

Enhanced piezoelectric performance of Cr/Ta non-equivalent co-doped Bi_(4)Ti_(3)O_(12)-based high-temperature piezoceramics

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Journal of Advanced Ceramics 2024年第3期13卷 263-271页

作者： Xuanyu Chen Ziqi Ma Bin Li Yejing Dai School of Materials Sun Yat-sen UniversityShenzhen 518107China

In this study,(Cr_(1/3)/Ta_(2/3))non-equivalent co-doped Bi_(4)Ti_(3)O_(12)(BIT)ceramics were prepared to solve the problem that high piezoelectric performance,high Curie temperature,and high-temperature resistivity could not be achieved simultaneously in BIT-based ceramics.A series of Bi_(4)Ti_(3-x)(Cr_(1/3)Ta_(2/3))_(x)O_(12)(x=0-0.04)ceramics were synthesized by the solid-state reaction method.The phase structure,microstructure,piezoelectric performance,and conductive mechanism of the samples were systematically investigated.The B-site non-equivalent co-doping strategy combining high-valence Ta^(5+)and low-valence Cr^(3+)significantly enhances electrical properties due to a decrease in oxygen vacancy concentration.Bi_(4)Ti_(2.97)(Cr_(1/3)Ta_(2/3))_(0.03)O_(12)ceramics exhibit a high piezoelectric coefficient(d_(33)=26 pC·N^(-1))and a high Curie temperature(TC=687℃).Moreover,the significantly increased resistivity(ρ=2.8×10^(6)Ω·cm at 500℃)and good piezoelectric stability up to 600℃are also obtained for this composition.All the results demonstrate that Cr/Ta co-doped BIT-based ceramics have great potential to be applied in high-temperature piezoelectric applications.

关键词： high temperature piezoelectricity co-doped Bi_(4)Ti_(3)O_(12)(BIT)