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Disturbance failure mechanism of highly stressed rock in deep excavation:Current status and prospects
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作者 Tao Wang Weiwei Ye +3 位作者 Liyuan Liu Kai Liu Naisheng Jiang Xianhui Feng 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第4期611-627,共17页
This article reviews the current status on the dynamic behavior of highly stressed rocks under disturbances.Firstly,the experimental apparatus,methods,and theories related to the disturbance dynamics of deep,high-stre... This article reviews the current status on the dynamic behavior of highly stressed rocks under disturbances.Firstly,the experimental apparatus,methods,and theories related to the disturbance dynamics of deep,high-stress rock are reviewed,followed by the introduction of scholars’research on deep rock deformation and failure from an energy perspective.Subsequently,with a backdrop of highstress phenomena in deep hard rock,such as rock bursts and core disking,we delve into the current state of research on rock microstructure analysis and residual stresses from the perspective of studying the energy storage mechanisms in rocks.Thereafter,the current state of research on the mechanical response and the energy dissipation of highly stressed rock formations is briefly retrospected.Finally,the insufficient aspects in the current research on the disturbance and failure mechanisms in deep,highly stressed rock formations are summarized,and prospects for future research are provided.This work provides new avenues for the research on the mechanical response and damage-fracture mechanisms of rocks under high-stress conditions. 展开更多
关键词 deep rock with high stress highly stressed rock rock failure residual stress energy release
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Support design method for deep soft-rock tunnels in non-hydrostatic high in-situ stress field
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作者 ZHENG Ke-yue SHI Cheng-hua +3 位作者 ZHAO Qian-jin LEI Ming-feng JIA Chao-jun PENG Zhu 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第7期2431-2445,共15页
Due to the long-term plate tectonic movements in southwestern China,the in-situ stress field in deep formations is complex.When passing through deep soft-rock mass under non-hydrostatic high in-situ stress field,tunne... Due to the long-term plate tectonic movements in southwestern China,the in-situ stress field in deep formations is complex.When passing through deep soft-rock mass under non-hydrostatic high in-situ stress field,tunnels will suffer serious asymmetric deformation.There is no available support design method for tunnels under such a situation in existing studies to clarify the support time and support stiffness.This study first analyzed the mechanical behavior of tunnels in non-hydrostatic in-situ stress field and derived the theoretical equations of the ground squeezing curve(GSC)and ground loosening curve(GLC).Then,based on the convergence confinement theory,the support design method of deep soft-rock tunnels under non-hydrostatic high in-situ stress field was established considering both squeezing and loosening pressures.In addition,this method can provide the clear support time and support stiffness of the second layer of initial support.The proposed design method was applied to the Wanhe tunnel of the China-Laos railway in China.Monitoring data indicated that the optimal support scheme had a good effect on controlling the tunnel deformation in non-hydrostatic high in-situ stress field.Field applications showed that the secondary lining could be constructed properly. 展开更多
关键词 non-hydrostatic stress field high in-situ stress deep soft-rock tunnel squeezing pressure loosening pressure support design method
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Resistance index and browning mechanism of apple peel under high temperature stress
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作者 Hui Wang Shuhui Zhang +8 位作者 Zidun Wang Dongmei Li Leiyu Yan Yifeng Feng Xiaojie Liu Rongxin Chen Wenmin Fan Lulong Sun Zhengyang Zhao 《Horticultural Plant Journal》 SCIE CAS CSCD 2024年第2期305-317,共13页
Apples are one of the most important economic crops worldwide.Because of global warming and an aggravation of environmental,abnormally high temperatures occur frequently in fruit-growing season and seriously affect no... Apples are one of the most important economic crops worldwide.Because of global warming and an aggravation of environmental,abnormally high temperatures occur frequently in fruit-growing season and seriously affect normal fruit growth and reduce fruit quality and yield.We took five-year-old Ruixue’(Qinfu 1×Pink Lady;CNA20151469.1) fruits as test materials,and the ambient temperature during fruit development was monitored.The results showed that during the fruit-growing season,especially during the rapid growth stage (July to August),the maximum daily temperature exceeded 30℃ and lasted for more than 40 days.To determine the effects of high temperature stress on the apple fruit resistance,we treated expanding,veraison,and maturity-period fruits at different temperatures.It was found that the fruits of the expanding period showed strong resistance to high temperature stress,whereas during veraison and maturity,fruit resistance to high temperature stress decreased,and the fruit peel browning phenotype appeared.Meanwhile,the content of malonaldehyde (MDA),hydrogen peroxide (H_(2)O_(2)),and superoxide anion (O._(2)^(-)) in the peel gradually increased with increasing temperature.The content of total phenols,flavanol,and flavonoids in the peel decreased substantially at 45℃.Moreover,it was found that polyphenol oxidase gene (MdPPO1) was most sensitive to high temperature stress in apple.Furthermore,transient and stable MdPPO1 overexpression significantly promoted peel browning.The transgenic materials were more sensitive to high temperatures,and browning was more severe compared to non-genetically modified organism (WT).Stable MdPPO1 knockout calli obtained via clustered regularly interspersed short palindromic repeats (CRISPR/Cas9) gene knockout technology reduced the browning phenotype,and the resultant fruits were not sensitive to the effects of high temperature stress.Thus,MdPPO1 expression may be a key factor of high temperature-related changes observed in the browning phenotype that provides a scientific theoretical basis for the selection of high temperature-resistant varieties and apple cultivation and management in the future. 展开更多
关键词 Malus domestica Borkh high temperature stress PEEL BROWNING MdPPO1
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Economic Stress, Precariousness and Risk of High Blood Pressure: A Descriptive Survey of Life Models within Households of the Central Region of Cameroon
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作者 Jean Ndibi Abanda Ulrich Dama +5 位作者 Viviane Foussouo Ndoungue Anicet Onana Akoa Melkior Fobasso Dzeuta Alphonse Tedonge Asobochia Arsène Emilien Messi Ndzengue Désiré Tchoffo 《Health》 2024年第2期118-130,共13页
Context/Objective: High blood pressure (HBP) currently represents the most widespread chronic non-communicable disease in Cameroon. The increase in its prevalence in the country is the result of multiple factors inclu... Context/Objective: High blood pressure (HBP) currently represents the most widespread chronic non-communicable disease in Cameroon. The increase in its prevalence in the country is the result of multiple factors including economic stress imposed by precariousness, poor living conditions, sources of anxiety, anguish, depression and other behavioral disorders. Economic stress is a globalizing concept that integrates into a purely hermeneutic approach, a particular functioning of the nervous system of an individual who faces employment problems and precarious remuneration conditions. The non-satisfaction by an individual of his basic needs due to insufficient financial means can cause him to become irritable, aggressive, and socially and symbolically isolated, thereby increasing the desire to resort to morbid life models such as excessive consumption of narcotics and other psychoactive substances often associated with high blood pressure. The fight against the emergence of BPH is a complex, multifaceted and multifactorial reality that requires taking into account economic stress. The main objective of this survey is to describe the situation of economic stress within the Cameroonian population, which imposes precariousness and life models at risk of high blood pressure. Specifically, we determined the level of household income and the sources of income. Methods: A cross-sectional survey with a descriptive aim among five hundred households in the Central Region of Cameroon was conducted. A probabilistic technique called simple randomness was used. The number of households to be surveyed was determined indirectly using the Cochrane formula. Data collection in face-to-face mode using a physical questionnaire took place from July 1 to August 31, 2023, after obtaining ethical clearance from the Regional Health Research Ethics Committee, Human from the Center and an administrative authorization for data collection. Regarding their processing, the data was grouped during processing in Excel sheets. Normality and reliability tests of the collected data were carried out. For this, the Chi-square test was used for data with a qualitative value and that of Kolmogorov-Sminorf for data with a quantitative value. Descriptive analysis was possible using R software version 3.2, SPSS version 25.0, XLSTAT 2016, PAST and EXCEL programs from Microsoft Office 2013. Results: The main results highlight economic stress, with 45.60% of households surveyed earning less than US$154 per month;55% of household heads were women in single-parent families;14% of household heads were unemployed, 22% worked in the private sector and 19% were self-employed. This general economic situation leads to precarious living conditions, thereby increasing the risk of high blood pressure among the Cameroonian population. 展开更多
关键词 Economic stress PRECARIOUSNESS high Blood Pressure Life Models Households
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Triaxial creep damage characteristics of sandstone under high crustal stress and its constitutive model for engineering application 被引量:1
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作者 Dongxu Chen Laigui Wang +1 位作者 Pierre Darry Versaillot Chuang Sun 《Deep Underground Science and Engineering》 2023年第3期262-273,共12页
The creep characteristics of rock under high crustal stress are of important influence on the long‐term stability of deep rock engineering.To study the creep characteristics and engineering application of sandstone u... The creep characteristics of rock under high crustal stress are of important influence on the long‐term stability of deep rock engineering.To study the creep characteristics and engineering application of sandstone under high crustal stress,this study constructed nonlinear creep damage(NCD)constitutive mode based on the triaxial graded loading‒unloading creep test of sandstone in the Yuezhishan Tunnel.A numerical NCD constitutive model and a breakable lining(BL)model were developed based on FLAC3D and then applied to the stability analysis of the Yuezhishan Tunnel.Based on the creep test results of sandstone,a power function of creep rate and stress level was constructed,by which the long‐term strength was solved.The results show that the long‐term strength of the red sandstone based on the related function of the steady‐state creep rate and stress level is close to the measured stress value in engineering.The NCD model considering damage factors reflects the instantaneous and viscoelastic plasticity deformation characteristics of the red sandstone.The numerical NCD constitutive model and the BL model can reflect surrounding rock deformation characteristics and lining failure characteristics in practical engineering.The research results provide theoretical references for long‐term stability analysis of rock engineering and the deformation control of surrounding rock under high crustal stress. 展开更多
关键词 creep damage model high stress long‐term strength secondary development tunnel engineering
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High-pressure and high-temperature sintering of pure cubic silicon carbide:A study on stress-strain and densification
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作者 刘金鑫 彭放 +5 位作者 马国龙 梁文嘉 何瑞琦 管诗雪 唐越 向晓君 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第9期498-505,共8页
Silicon carbide(SiC)is a high-performance structural ceramic material with excellent comprehensive properties,and is unmatched by metals and other structural materials.In this paper,raw SiC powder with an average grai... Silicon carbide(SiC)is a high-performance structural ceramic material with excellent comprehensive properties,and is unmatched by metals and other structural materials.In this paper,raw SiC powder with an average grain size of 5μm was sintered by an isothermal-compression process at 5.0 GPa and 1500?C;the maximum hardness of the sintered samples was31.3 GPa.Subsequently,scanning electron microscopy was used to observe the microscopic morphology of the recovered SiC samples treated in a temperature and extended pressure range of 0-1500?C and 0-16.0 GPa,respectively.Defects and plastic deformation in the SiC grains were further analyzed by transmission electron microscopy.Further,high-pressure in situ synchrotron radiation x-ray diffraction was used to study the intergranular stress distribution and yield strength under non-hydrostatic compression.This study provides a new viewpoint for the sintering of pure phase micron-sized SiC particles. 展开更多
关键词 high pressure and high temperature silicon carbide stress analysis DEFECT
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Metabolomics of astaxanthin hyperaccumulation in Haematococcus pluvialis under high light stress
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作者 Yong DOU Jiayi LI Wenli ZHOU 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2023年第5期1876-1886,共11页
Variation in metabolite profiles of Haematococcus pluvialis(a type of unicellular green algal)under light stress is a key issue of study at the present.To investigate the effect of light intensity on accumulation of a... Variation in metabolite profiles of Haematococcus pluvialis(a type of unicellular green algal)under light stress is a key issue of study at the present.To investigate the effect of light intensity on accumulation of astaxanthin in H.pluvialis,a 26-day batch culture experiment of H.pluvialis under the light intensity levels at 73,127,182,236,and 291μmol/(m^(2)·s)was conducted.Therefore,the optimal light intensity and the corresponding metabolic pathways of accumulation in H.pluvialis were determined.Results show that 236μmol/(m^(2)·s)was the optimum light intensity to induce astaxanthin accumulation,at which a maximum content of 9.01 mg/L was achieved on Day 24.A total of 132 metabolites were identified and quantified,of which 38 differential metabolites were highlighted and classified,including 3 fatty acids or intermediates,5 amino acids or derivatives,5 carbohydrates or intermediates,16nucleoside derivatives,and 9 other metabolites using LC-MS/MS technique.Subsequently,16 statistically significant differential metabolic pathways were enriched and annotated based on Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway analysis between the control and the 236μmol/(m^(2)·s)treatment group(P<0.05).In addition,the bioprocesses included cellular basal metabolism and signaling systems,such as carbohydrate metabolism,amino acid metabolism,glycerol and derivatives metabolism,nucleotide and derivative metabolism,and inositol phosphate metabolism were activated and regulated under strong light stress conditions.Moreover,4 hub metabolites containing D-glucose-6-phosphate,L-tyrosine,glycerol-3-phosphate,and L-glutamine were identified,based on which the associated metabolic network was constructed.The study provided a metabolomic view of astaxanthin accumulation in H.pluvialis under strong light stress. 展开更多
关键词 Haematococcus pluvialis ASTAXANTHIN high light stress metabolomic analysis
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Study on Asymmetric Deformation Law and Surrounding Rock Control Technology of High Stress Soft Rock Crossing Roadway
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作者 Linhao Zhang 《World Journal of Engineering and Technology》 2023年第2期353-369,共17页
In order to solve the problem of asymmetric large deformation of high-stress soft rock crossing roadway under complex geological conditions in deep mines, taking the 2# total return airway of 76.2# section of Wuyang C... In order to solve the problem of asymmetric large deformation of high-stress soft rock crossing roadway under complex geological conditions in deep mines, taking the 2# total return airway of 76.2# section of Wuyang Coal Mine as the engineering background, the causes of asymmetric deformation and failure of soft rock crossing roadway in deep mines were summarized and analyzed by means of field investigation, theoretical analysis and numerical simulation, and the asymmetric high-efficiency support technology with large row spacing was studied. The results show that the lithology of roadway strata is the main cause of asymmetric deformation and failure of roadway. The shape change of roadway is not the main influencing factor of asymmetric deformation of roadway, but for the control of roadway surrounding rock, the straight wall semi-circular arch roadway is better than the rectangular roadway. The field industrial test shows that after adopting the new support design scheme, the displacement of the roof and floor of the roadway is reduced by 86.39% compared with the original support design scheme, and the displacement of the two sides of the roadway is reduced by 86.05% compared with the original support design scheme, which can ensure the normal and safe production of the roadway during the service period, and provide reference for the support design of other similar geological conditions. 展开更多
关键词 Deep high stress Soft Rock Penetration Asymmetric Deformation Support FLAC3D
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Effects of high glucose and severe hypoxia on the biological behavior of mesenchymal stem cells at various passages
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作者 Fatimah Almahasneh Ejlal Abu-El-Rub +1 位作者 Ramada R Khasawneh Rawan Almazari 《World Journal of Stem Cells》 SCIE 2024年第4期434-443,共10页
BACKGROUND Mesenchymal stem cells(MSCs)have been extensively studied for therapeutic potential,due to their regenerative and immunomodulatory properties.Serial passage and stress factors may affect the biological char... BACKGROUND Mesenchymal stem cells(MSCs)have been extensively studied for therapeutic potential,due to their regenerative and immunomodulatory properties.Serial passage and stress factors may affect the biological characteristics of MSCs,but the details of these effects have not been recognized yet.AIM To investigate the effects of stress factors(high glucose and severe hypoxia)on the biological characteristics of MSCs at different passages,in order to optimize the therapeutic applications of MSCs.METHODS In this study,we investigated the impact of two stress conditions;severe hypoxia and high glucose on human adipose-tissue derived MSCs(hAD-MSCs)at passages 6(P6),P8,and P10.Proliferation,senescence and apoptosis were evaluated measuring WST-1,senescence-associated beta-galactosidase,and annexin V,respectively.RESULTS Cells at P6 showed decreased proliferation and increased apoptosis under conditions of high glucose and hypoxia compared to control,while the extent of senescence did not change significantly under stress conditions.At P8 hAD-MSCs cultured in stress conditions had a significant decrease in proliferation and apoptosis and a significant increase in senescence compared to counterpart cells at P6.Cells cultured in high glucose at P10 had lower proliferation and higher senescence than their counterparts in the previous passage,while no change in apoptosis was observed.On the other hand,MSCs cultured under hypoxia showed decreased senescence,increased apoptosis and no significant change in proliferation when compared to the same conditions at P8.CONCLUSION These results indicate that stress factors had distinct effects on the biological processes of MSCs at different passages,and suggest that senescence may be a protective mechanism for MSCs to survive under stress conditions at higher passage numbers. 展开更多
关键词 Mesenchymal stem cells high glucose HYPOXIA stressful microenvironment Serial passage SENESCENCE APOPTOSIS
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Potassium alleviated high nitrogen-induced apple growth inhibition by regulating photosynthetic nitrogen allocation and enhancing nitrogen utilization capacity
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作者 Xinxiang Xu Guangyuan Liu +10 位作者 Jingquan Liu Mengxue Lyu Fen Wang Yue Xing Hao Meng Min Li Yu Jiang Ge Tian Zhanling Zhu Yuanmao Jiang Shunfeng Ge 《Horticultural Plant Journal》 SCIE CAS CSCD 2024年第1期1-14,共14页
There is a close relationship between potassium(K)and nitrogen(N).However,the roles of K under high N conditions remain unclear.Using a hydroponics approach,we monitored the morphological,physiological,and molecular c... There is a close relationship between potassium(K)and nitrogen(N).However,the roles of K under high N conditions remain unclear.Using a hydroponics approach,we monitored the morphological,physiological,and molecular changes in M9T337 apple(Malus domestica)rootstocks under different nitrate(10 and 30 mmol·L^(-1)NO_(3)^(-))and K supply(0.5,6,10,and 20 mmol·L_(-1)K^(+))conditions.Results revealed that high nitrate inhibited the root growth of M9T337 rootstocks,downregulated the expressions of K transporter genes(MdPT5,MdHKT1,and MdATK1),and reduced the net NO3-and K+influx at the surface of roots,thereby resulting in an N/K imbalance in rootstocks.Further investigation showed that 10 mmol·L^(-1)K increased the activity of N metabolic enzymes(NR,GS,NiR,and GOGAT),upregulated the expressions of genes related to nitrate uptake and transport(MdNRT1.1,MdNRT1.2,MdNRT1.5,and MdNRT2.4),promoted15N transport from the roots to the shoots,optimized leaf N distribution,and improved photosynthetic N utilization efficiency under high nitrate conditions.These results suggest that the negative effects of high nitrate may be related to the N/K imbalance and that reducing N/K in plants by increasing K supply level can effectively alleviate the inhibition of N assimilation by high nitrate stress. 展开更多
关键词 Apple rootstock K level high nitrate stress N metabolism ^(15)N
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ANovel Non-Isolated Cubic DC-DC Converter with High Voltage Gain for Renewable Energy Power Generation System
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作者 Qin Yao Yida Zeng Qingui Jia 《Energy Engineering》 EI 2024年第1期221-241,共21页
In recent years,switched inductor(SL)technology,switched capacitor(SC)technology,and switched inductor-capacitor(SL-SC)technology have been widely applied to optimize and improve DC-DC boost converters,which can effec... In recent years,switched inductor(SL)technology,switched capacitor(SC)technology,and switched inductor-capacitor(SL-SC)technology have been widely applied to optimize and improve DC-DC boost converters,which can effectively enhance voltage gain and reduce device stress.To address the issue of low output voltage in current renewable energy power generation systems,this study proposes a novel non-isolated cubic high-gain DC-DC converter based on the traditional quadratic DC-DC boost converter by incorporating a SC and a SL-SC unit.Firstly,the proposed converter’s details are elaborated,including its topology structure,operating mode,voltage gain,device stress,and power loss.Subsequently,a comparative analysis is conducted on the voltage gain and device stress between the proposed converter and other high-gain converters.Then,a closed-loop simulation system is constructed to obtain simulation waveforms of various devices and explore the dynamic performance.Finally,an experimental prototype is built,experimental waveforms are obtained,and the experimental dynamic performance and conversion efficiency are analyzed.The theoretical analysis’s correctness is verified through simulation and experimental results.The proposed converter has advantages such as high voltage gain,low device stress,high conversion efficiency,simple control,and wide input voltage range,achieving a good balance between voltage gain,device stress,and power loss.The proposed converter is well-suited for renewable energy systems and holds theoretical significance and practical value in renewable energy applications.It provides an effective solution to the issue of low output voltage in renewable energy power generation systems. 展开更多
关键词 Cubic DC-DC converter high voltage gain low device stress high efficiency renewable energy
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Carbides Formation in MarM247 Directional Solidified during Stress-Rupture Test at High Temperature
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作者 Daniel Moreno Itzik Mizrahi +3 位作者 Yuri Lipkin Vasiliy Zevin Elinor Itzhak Zion Harush 《Journal of Minerals and Materials Characterization and Engineering》 2023年第5期131-142,共12页
In our study, stress-rupture tests were conducted at elevated temperatures to examine the impact of high temperature on MarM247 LC (low carbon). Our main objective was to investigate the alterations in the microstruct... In our study, stress-rupture tests were conducted at elevated temperatures to examine the impact of high temperature on MarM247 LC (low carbon). Our main objective was to investigate the alterations in the microstructure, particularly the carbon precipitation, during long-term stress-rupture tests. It was observed that cracks developed near the sample neck, following the path of the carbides and the gamma matrix, rather than occurring in the gamma-gamma prime eutectic. This occurred despite the formation of carbides because of prolonged exposure to high temperature and load, and the crack propagation did not follow that path. Based on these findings, we suggest that a reduction in the carbon content of Mar-M247 LC can enhance the sample's lifespan when subjected to temperatures below 760˚C and a stress of 690 MPa. 展开更多
关键词 MarM247 Carbides stress-RUPTURE high-Temperature CRACK-PROPAGATION
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Effect of Exogenous Nitric Oxygen on Lipid Peroxidation and Chlorophyll Fluorescence in Wheat Leaves under High Temperature and Strong Irradiance Stress 被引量:7
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作者 杨亚军 李利红 +2 位作者 赵会杰 马培芳 张超男 《Agricultural Science & Technology》 CAS 2008年第3期25-30,共6页
[Objective] The study aimed to prove effects of NO on oxidative damage and photosynthetic apparatus at filling stage of wheat leaves under high temperature and irradiance stress.[Method] Yunong 949 was taken as experi... [Objective] The study aimed to prove effects of NO on oxidative damage and photosynthetic apparatus at filling stage of wheat leaves under high temperature and irradiance stress.[Method] Yunong 949 was taken as experimental material to study the effects of sodium nitropprusside (SNP,an exogenous nitric oxide donor) at 0.1 mmol/L on protective enzyme activities, oxidative damage and fluorescence.[Result] The treatment with SNP (at 0.1 mmol/L) significantly increased the activity of SOD and APX, proline content, decreased the MDA content and relative electrical conductivity, Kept the higher Fv/Fm and lower Fo.[Conclusion] The adaptability of wheat with SNP treatment at 0.1 mmol/L was improved under high temperature and irradiance stress. 展开更多
关键词 Wheat SNP high temperature and IRRADIANCE stress ANTIOXIDANT ENZYME Fluorescence
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Effects of High Light Stress on Chlorophyll-protein Complexes of Two Subspecies of Rice 被引量:10
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作者 辛越勇 冯丽洁 +3 位作者 许亦农 焦德茂 李良璧 匡廷云 《Acta Botanica Sinica》 CSCD 2000年第12期1278-1284,共7页
Influence of high light stress on the photosynthesis of flag leaves of indica subspecies (cv. “Shanyou 63', sensitive to photoinhibition) and japonica subspecies (cv. “Wuyujing', resistant to photoin... Influence of high light stress on the photosynthesis of flag leaves of indica subspecies (cv. “Shanyou 63', sensitive to photoinhibition) and japonica subspecies (cv. “Wuyujing', resistant to photoinhibition) of rice ( Oryza sativa L.) was comparatively investigated. In both cultivars of rice, the excitation energy distribution between two photosystems was altered and the excitation energy transfer from light harvesting chlorophyll protein complexes to PSⅡ was inhibited by high light stress. These decreases were more pronounced in indica rice cultivar as compared to japonica one. The analysis of mild SDS_PAGE showed that in indica rice, high light stress almost disaggregated the trimer of light harvesting chlorophyll protein complexes of PSⅡ (LHC Ⅱ 1). The stress reduced the contents of internal antennae chlorophyll protein complexes of PSⅡ (CPa), light harvesting chlorophyll protein of PSⅠ (CPⅠa) and Chl a protein complex of PSⅠ reaction center (CPⅠ) as well as dimer of LHCⅡ (LHCⅡ 2) in indica rice. In japonica subspecies, however, high light stress depressed the contents of LHCⅡ 1, CPa and CPⅠa, but slightly impacted on CPⅠ content. Moreover, the increase in the contents of monomer of LHCⅡ by high light stress was found in both subspecies. In consistent with above results, analysis of polypeptide indicated that the amounts of 27 kD and 25 kD polypeptide of LHCⅡ in particular, as well as that of 21 kD polypeptide of CPⅠa were reduced by high light stress in both subspecies. It was found that, comparing with japonica rice, the stress pronouncedly diminished 43 kD and 47 kD proteins of CPa and 23 kD extrisic protein in indica rice. 展开更多
关键词 high light stress subspecies of rice excitation energy distribution chlorophyll_protein comp(
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Fatigue reliability quantitative analysis of cement concrete for highway pavement under high stress ratio 被引量:5
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作者 薛彦卿 黄晓明 +2 位作者 钱吮智 马涛 邹湘衡 《Journal of Southeast University(English Edition)》 EI CAS 2012年第1期94-99,共6页
In order to obtain the change law of the fatigue reliability of cement concrete for highway pavement under high stress ratios, first, the probability densities of monotonic random variables including concrete fatigue ... In order to obtain the change law of the fatigue reliability of cement concrete for highway pavement under high stress ratios, first, the probability densities of monotonic random variables including concrete fatigue life are deduced. And then, the fatigue damage probability densities of the Miner and Chaboche-Zhao models are deduced. By virtue of laboratory fatigue test results, the fatigue damage probability density functions of the two models can be obtained, considering different stress ratios. Finally, substituting load cycles into them, the change law of cement concrete fatigue reliability about load cycles can be acquired. The results show that under the same stress ratio, with the increase in the load cycle, the fatigue reliability declines from almost 100% to 0% gradually. No matter under what stress ratio, during the initial stage of the load action, there is always a relatively stable phase for fatigue reliability. With the increase in the stress ratio, the stable phase gradually shortens and the load cycle corresponding to the reliability of 0% also decreases. In the descent phase of reliability, the higher the stress ratio is, the lower the concrete reliability is for the same load cycle. Besides, compared with the Chaboche-Zhao fatigue damage model, the Miner fatigue damage model is safer. 展开更多
关键词 cement concrete fatigue life fatigue damage probability density function high stress ratio fatigue reliability
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Numerical simulation of optimum mining design for high stress hard-rock deposit based on inducing fracturing mechanism 被引量:3
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作者 姚金蕊 马春德 +1 位作者 李夕兵 杨金林 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第9期2241-2247,共7页
The 3D numerical simulation model of deep hard-rock deposit in Kaiyang Phosphate Mine of Guiyang was established based on the practical engineering using 3DEC numerical simulation software. The distribution characteri... The 3D numerical simulation model of deep hard-rock deposit in Kaiyang Phosphate Mine of Guiyang was established based on the practical engineering using 3DEC numerical simulation software. The distribution characteristics of displacement fields and plastic zones of the orebody were simulated in three different excavation cases, including the case of excavation artificial inducted roadway in the orebody, the case of horizontal or vertical excavation direction and the case of the upward or downward excavation order. The simulation results indicate that the plastic zone and displacement field of surrounding rock around the inducted roadway are continuously increasing with the increase of the exposure time after digging an artificial inducted roadway in the orebody. Thus the raw rock ore becomes easier to be fragmented, which provides advantageous conditions for roadheader to cut high stress hard-rock. It is worthy noting that there is a large difference in effective utilization of deep ground pressure between horizontal and vertical excavation directions. The later can produce larger deformation and fracture zone than the former on the rock mass around the deduced roadway, which means that the later may utilize the high ground pressure more effectively to break hard-rock. And the obtained results also show that upward excavation order is more helpful for ground pressure to break rock than downward excavation order. 展开更多
关键词 inducted fracturing high stress hard-rock deposit excavation case roadheader excavation numerical simulation
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Effects of Short-term High Temperature Stress on the Photosynthesis of Potato in Different Growth Stages 被引量:3
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作者 王连喜 金鑫 +3 位作者 李剑萍 马国飞 曹宁 李琪 《Agricultural Science & Technology》 CAS 2011年第3期317-321,342,共6页
[Objective] The aim was to study the effects of short-term high temperature stress on the photosynthesis of potato in different growth stages. [Method] Choosing powder potato named Longshu No.3 widely cultivated in Ni... [Objective] The aim was to study the effects of short-term high temperature stress on the photosynthesis of potato in different growth stages. [Method] Choosing powder potato named Longshu No.3 widely cultivated in Ningxia as test material,the changes of stomata conductance (Gs),transpiration rate (Tr) and CO2 concentration difference between internal and external leaf chamber,net photosynthetic rate (Pn) and photosynthetic water use efficiency (WUE) in different growth stages under short-term high temperature were analyzed. [Result] During seedling stage,the hysteretic nature of net photosynthetic rate and CO2 concentration difference between internal and external leaf chamber of potato could be found under high temperature stress,while the change trends of stomata conductance and transpiration rate under high temperature stress were consistent to that at normal temperature,but stomata conductance and transpiration rate were higher than those at normal temperature,and CO2 concentration difference between internal and external leaf chamber affected net photosynthetic rate most obviously. During branching stage,the change trends of net photosynthetic rate,CO2 concentration difference between internal and external leaf chamber,stomata conductance and transpiration rate under high temperature stress and normal temperature were similar,but they changed abruptly and reached peak value at noon under high temperature stress,while there existed consistent variation of water use efficiency under high temperature stress and at normal temperature,and CO2 concentration difference between internal and external leaf chamber also affected net photosynthetic rate most greatly,next came transpiration rate. [Conclusion] High temperature stress affected the photosynthesis of potato in different growth stages,and it was more obvious during branching stage than seedling stage,while CO2 concentration difference between internal and external leaf chamber had the most important influence on net photosynthetic rate. 展开更多
关键词 POTATO Different growth stages high temperature stress PHOTOSYNTHESIS
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Effects of High Temperature Stress on Growth of Stress-Tolerant Rice Seedlings with Resistibility 被引量:4
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作者 张晓晶 张思远 +1 位作者 李春青 张文会 《Agricultural Science & Technology》 CAS 2014年第4期576-578,584,共4页
Two heat-tolerant rice varieties, N5 and TQ, were chosen as test materi- als. Specifically, rice seedlings (leaf age at 2.1), cultivated in room, were treated at 40 ℃ for 7 d and some indices were measured, includi... Two heat-tolerant rice varieties, N5 and TQ, were chosen as test materi- als. Specifically, rice seedlings (leaf age at 2.1), cultivated in room, were treated at 40 ℃ for 7 d and some indices were measured, including plant height, dry weight, leaf color, proline, malondialdehyde and conductivity. The results showed that high temperature advanced the growth of N5 seedlings, for example, plant height, root length and dry weight of ground parts all increased. However, high temperature prevented TQ seedlings growth, plant height in particular. Furthermore, high temper- ature treatment increased the content of chlorophyll of N5 and had none effects on PSII of N5, with little damages on membrane system. On the other hand, high temperature actually reduced PSII activity of TQ, and seriously damaged TQ mem- brane system. It is speculated that the differences of the two varieties lie on pro- duction or removing capacity of reactive oxide species. 展开更多
关键词 high temperature stress Rice seedlings TOLERANCE
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Differentiation of Barley Genotypes with High Phosphorus Efficiency under Low Phosphorus Stress 被引量:2
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作者 杨涛 何金宝 +3 位作者 曾亚文 普晓英 杨树明 杜娟 《Agricultural Science & Technology》 CAS 2013年第11期1615-1619,共5页
[Objective] This study aimed to investigate differences in phosphorus effi-ciency between two-rowed barley and multiple-rowed barley and differences in phos-phorus efficiency among various agronomic traits, and to exp... [Objective] This study aimed to investigate differences in phosphorus effi-ciency between two-rowed barley and multiple-rowed barley and differences in phos-phorus efficiency among various agronomic traits, and to explore the relationship be-tween agronomic traits and row type with phosphorus efficiency. [Method] Under available phosphorus mass fractions of 1.32 and 36.6 mg/kg, 172 barley varieties, including 79 two-rowed foreign barley, 22 multiple-rowed foreign barley, 58 two-rowed Chinese barley and 13 multiple-rowed Chinese barley, were selected to com-pare differences in phosphorus efficiency-related agronomic traits. Plant height, spike length, number of unfil ed grains, number of unfil ed grains, main panicle weight, to-tal panicle weight, total stem weight, weight of aerial part and heading stage were surveyed for statistical analysis. [Result] The results showed that, various agronomic traits were larger under fertilization condition than under non-fertilization condition ex-cept number of unfil ed grains and heading stage. Plant high, spike length, weight of aerial part and heading stage varied greatly under non-fertilization condition; number of fil ed grains, number of unfil ed grains and total stem weight varied greatly under fertilization condition. In two-rowed barley, plant height and number of fil ed grains of Chinese varieties were higher than those of foreign varieties, while other agronomic traits such as spike length, number of unfil ed grains, main panicle weight, total panicle weight, total stem weight, weight of aerial part and heading stage of foreign varieties were higher than those of Chinese varieties. Spike length and weight of aerial part in multiple-rowed and two-rowed foreign barley were higher than those in Chinese barley. In multiple-rowed barley, plant height, number of unfil ed grains, total panicle weight and total stem weight of foreign varieties were higher under non-fer-tilization condition and lower under fertilization condition compared with those of Chi-nese varieties; number of fil ed grains, main panicle weight and heading stage of foreign varieties were lower under non-fertilization condition and higher under fertil-ization condition compared with those of Chinese varieties. [Conclusion] Heading stage, number of fil ed grains, number of unfil ed grains and total stem weight are more sensitive to phosphorus efficiency. Multiple-rowed barley is more sensitive to phosphorus efficiency than two-rowed barley. 展开更多
关键词 Low phosphorus stress BARLEY high phosphorus efficiency GENOTYPE Agronomic traits
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Effect of High-Gate-Voltage Stress on the Reverse Gated-Diode Current in LDD nMOSFET’s 被引量:2
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作者 陈海峰 郝跃 马晓华 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第5期875-878,共4页
The reverse generation current under high-gate-voltage stress condition in LDD nMOSFET's is studied. We find that the generation current peak decreases as the stress time increases. We ascribe this finding to the dom... The reverse generation current under high-gate-voltage stress condition in LDD nMOSFET's is studied. We find that the generation current peak decreases as the stress time increases. We ascribe this finding to the dominating oxide trapped electrons that reduce the effective drain bias, lowering the maximal generation rate. The density of the effective trapped electrons affecting the effective drain bias is calculated with our model. 展开更多
关键词 generation current high gate voltage stress trapped electron
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