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Search Results: 1 - 10 of 104189 matches for " Zhang Yongxing "
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STUDY ON MACRO- AND MESO-DAMAGE COMPOSITE MODEL OF ROCK AND CRACK PROPAGATION RULE
岩石宏、细观损伤复合模型及裂纹扩展规律研究

LAI Yong,ZHANG Yongxing,
赖 勇
,张永兴

岩石力学与工程学报 , 2008,
Abstract: 通过假设微元具有破坏、损伤和无损3种状态,损伤和破坏可以用无损的程度表示;把细观损伤理论和宏观统计损伤模型结合,建立应力-应变与微裂纹密度变化的关系;分别运用Taylor方法、广义自洽法和Taylor介质法,通过计算实例分析岩石应力-应变过程中裂纹密度的发展变化规律,讨论特征点处的裂纹密度变化特点及计算方法的影响,尝试利用细观损伤理论确定岩石残余强度,得出岩石非线性性质是裂纹密度发展速度的宏观表现等结论.
STUDY ON LOW STRAIN DYNAMIC RESPONSE THEORY FOR ANCHOR BARS-SURROUNDING ROCK SYSTEM AND ITS APPLICATION
锚杆–围岩结构系统低应变动力响应理论与应用研究

ZHANG Yongxing,CHEN Jiangong,
张永兴
,陈建功

岩石力学与工程学报 , 2007,
Abstract: The low strain longitudinal dynamic model of anchor bars-surrounding rock system under impulse force is established.The model is essential to nondestructive detection of anchorage system quality.Through theoretical study,model experiment and numerical simulation,the characteristics of dynamic response with different defects in the anchor bars are studied.In dynamic analysis,the variations of dynamic parameters reflect the damaged degree of anchorage system and dynamic parameters are the vital reference of the anchorage quality.The simplified models of anchorage system with different damage conditions are constructed in laboratory;and a new approach which uses genetic algorithm is employed to solve the problem of multi-parameter inversion for anchorage system in dynamic testing.By modern signal processing and artificial intelligent methods,the method of fixing defect position and structure identification of anchorage system are researched.Meanwhile,a quantitative assessment method of anchoring quality is put forward;and an intelligent diagnosis system for nondestructive evaluation of anchorage system is established and applied to field engineering.
NUMERICAL STUDY OF LOW STRAIN DYNAMIC TEST FOR BOLT
锚杆低应变动测的数值研究

Xu Ming,Zhang Yongxing,
许明
,张永兴

岩石力学与工程学报 , 2003,
Abstract: Sonoprobe method has been applied in non-destructive inspect of bolt-supported project,with the fundament that dynamic transient excitation causes the elastic vibration of bolt,and flaws can be estimated or dedermined by analysing transient response of bolt. In the mechanics field this method means that if the information of disturbance resource,boundary conditions and initial conditions has been given,the dominant equation describing medium motion could be established and then the dynamic response solved. Usually it comes down to the question of initial value or initial-boundary value of hyperbolic equation or hyperbolic- diffusibility equation. FE solution is made on the hyperbolic equation,based on acoustic parameters,such as velocity of sound,vibration range,wave shape,etc,when inspecting interior flaws of grout of bolt. The obtained estimation is more credible with the spectrum aberration taken into account.
ENVIRONMENTAL IMPACT OF NUCLEAR POWER INDUSTRY IN CHINA
中国核电工业环境危害评价

Zhang Shaedong,Pan Ziqiang,Zhang Yongxing,
张少东
,潘自强,张永兴

环境科学学报 , 1995,
Abstract: 利用所编排的健康危害评价计算程序包,在计入核电生产过程中燃料循环各环节中的辐射危害及工伤事故的伤亡后,计算给出目前中国核电工业的总健康危害约为3.0人.(GW.a)^-1。由此说明,中国的核电工业是安全和清洁的工业。
Efficient Generation of Fully Reprogrammed Human iPS Cells via Polycistronic Retroviral Vector and a New Cocktail of Chemical Compounds
Zhonghui Zhang, Yongxing Gao, Albert Gordon, Zack Z. Wang, Zhijian Qian, Wen-Shu Wu
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0026592
Abstract: Direct reprogramming of human somatic cells into induced pluripotent stem (iPS) cells by defined transcription factors (TFs) provides great potential for regenerative medicine and biomedical research. This procedure has many challenges, including low reprogramming efficiency, many partially reprogrammed colonies, somatic coding mutations in the genome, etc. Here, we describe a simple approach for generating fully reprogrammed human iPS cells by using a single polycistronic retroviral vector expressing four human TFs in a single open reading frame (ORF), combined with a cocktail containing three small molecules (Sodium butyrate, SB431542, and PD0325901). Our results demonstrate that human iPS cells generated by this approach express human ES cells markers and exhibit pluripotency demonstrated by their abilities to differentiate into the three germ layers in vitro and in vivo. Notably, this approach not only provides a much faster reprogramming process but also significantly diminishes partially reprogrammed iPS cell colonies, thus facilitating efficient isolation of desired fully reprogrammed iPS cell colonies.
Suppression of murine breast cancer metastasis by selective inhibition of CXCR4 by synthetic polypeptide derived from viral macrophage inflammatory protein II
QingLing Yang,YongXing Ding,ChangJie Chen,Jie Tang,Ju Zhang,ZhiFeng Yang
Chinese Science Bulletin , 2010, DOI: 10.1007/s11434-010-3262-9
Abstract: Stromal cell-derived factor-1 and its receptor CXC chemokine receptor-4 (CXCR4) have been implicated in breast cancer metastasis. A significant association between HER2 and CXCR4 expression has been observed in human breast tumor tissues, and overexpression of CXCR4 is essential for HER2-mediated tumor metastasis. Moreover, CXCR4 expression is low in normal breast tissues and high in malignant tumors, suggesting that a blockade of CXCR4 may limit tumor metastasis. The present study investigated the action of a synthetic antagonist 21-mer peptide derived from viral macrophage inflammatory protein II against CXCR4 (NT21MP) in inhibiting metastasis in vitro and in vivo. The results showed that chemotaxis of SKBR3 cells toward SDF-1α was reduced by NT21MP in a dose-dependent manner (P < 0.05). NT21MP inhibited tumor growth at 500 μg/kg and in combination with Herceptin, the anti-HER2 antibody. The in vivo metastatic assay showed that NT21MP significantly inhibited pulmonary metastasis, and the number of metastatic tumor nodes on the surface of the lung was greatly decreased. Compared with the saline-treated control group, PCNA expression was dose-dependently decreased by NT21MP, the percentage of apoptotic cells was increased, and CXCR4 mRNA and protein expression were downregulated. In conclusion, NT21MP inhibits cellular proliferation, promotes apoptosis by downregulating CXCR4 expression, and suppresses the progression of primary and metastatic tumors. CXCR4 may be a useful therapeutic target for breast cancer, and NT21MP may serve as a potential target drug for the treatment of breast cancer metastasis.
Proinflammatory Cytokines Stimulate Mitochondrial Superoxide Flashes in Articular Chondrocytes In Vitro and In Situ
Yongxing Cao, Xin Zhang, Wei Shang, Jiejia Xu, Xianhua Wang, Xiaoqing Hu, Yingfang Ao, Heping Cheng
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0066444
Abstract: Objective Mitochondria play important roles in many types of cells. However, little is known about mitochondrial function in chondrocytes. This study was undertaken to explore possible role of mitochondrial oxidative stress in inflammatory response in articular chondrocytes. Methods Chondrocytes and cartilage explants were isolated from wild type or transgenic mice expressing the mitochondrial superoxide biosensor - circularly permuted yellow fluorescent protein (cpYFP). Cultured chondrocytes or cartilage explants were incubated in media containing interleukin-1β (10 ng/ml) or tumor necrosis factor-α (10 ng/ml) to stimulate an inflammatory response. Mitochondrial imaging was carried out by confocal and two-photon microscopy. Mitochondrial oxidative status was evaluated by “superoxide flash” activity recorded with time lapse scanning. Results Cultured chondrocytes contain abundant mitochondria that show active motility and dynamic morphological changes. In intact cartilage, mitochondrial abundance as well as chondrocyte density declines with distance from the surface. Importantly, sudden, bursting superoxide-producing events or “superoxide flashes” occur at single-mitochondrion level, accompanied by transient mitochondrial swelling and membrane depolarization. The superoxide flash incidence in quiescent chondrocytes was ~4.5 and ~0.5 events/1000 μm2*100 s in vitro and in situ, respectively. Interleukin-1β or tumor necrosis factor-α stimulated mitochondrial superoxide flash activity by 2-fold in vitro and 5-fold in situ, without altering individual flash properties except for reduction in spatial size due to mitochondrial fragmentation. Conclusions The superoxide flash response to proinflammatory cytokine stimulation in vitro and in situ suggests that chondrocyte mitochondria are a significant source of cellular oxidants and are an important previously under-appreciated mediator in inflammatory cartilage diseases.
Correlational Analysis of neck/shoulder Pain and Low Back Pain with the Use of Digital Products, Physical Activity and Psychological Status among Adolescents in Shanghai
Zhi Shan, Guoying Deng, Jipeng Li, Yangyang Li, Yongxing Zhang, Qinghua Zhao
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0078109
Abstract: Purpose This study investigates the neck/shoulder pain (NSP) and low back pain (LBP) among current high school students in Shanghai and explores the relationship between these pains and their possible influences, including digital products, physical activity, and psychological status. Methods An anonymous self-assessment was administered to 3,600 students across 30 high schools in Shanghai. This questionnaire examined the prevalence of NSP and LBP and the level of physical activity as well as the use of mobile phones, personal computers (PC) and tablet computers (Tablet). The CES-D (Center for Epidemiological Studies Depression) scale was also included in the survey. The survey data were analyzed using the chi-square test, univariate logistic analyses and a multivariate logistic regression model. Results Three thousand sixteen valid questionnaires were received including 1,460 (48.41%) from male respondents and 1,556 (51.59%) from female respondents. The high school students in this study showed NSP and LBP rates of 40.8% and 33.1%, respectively, and the prevalence of both influenced by the student’s grade, use of digital products, and mental status; these factors affected the rates of NSP and LBP to varying degrees. The multivariate logistic regression analysis revealed that Gender, grade, soreness after exercise, PC using habits, tablet use, sitting time after school and academic stress entered the final model of NSP, while the final model of LBP consisted of gender, grade, soreness after exercise, PC using habits, mobile phone use, sitting time after school, academic stress and CES-D score. Conclusions High school students in Shanghai showed high prevalence of NSP and LBP that were closely related to multiple factors. Appropriate interventions should be implemented to reduce the occurrences of NSP and LBP.
ANALYSES ON STRAIN LOCALIZATION AND COMPLETE STRESS-STRAIN RELATION OF MESOSCOPIC HETEROGENOUS ROCK UNDER UNIAXIAL TENSION
单轴拉伸条件下细观非均匀性岩石变形局部化分析及其应力-应变全过程研究

Zhou Xiaoping,Zhang Yongxing,Ha Qiuling,Wang Jianhua,
周小平
,张永兴 哈秋 王建华

岩石力学与工程学报 , 2004,
Abstract: 岩土工程的开挖卸荷往往产生拉应力,因此研究单轴拉伸条件下细观非均匀性岩石的变形局部化和全过程应力.应变关系具有重要的理论和现实意义。利用损伤力学理论研究了岩石在线弹性阶段、非线性强化阶段、应力跌落、应变软化阶段的拉伸应力.应变关系,并分析了产生应力跌落和应变软化的主要原因是损伤和变形局部化,将损伤和变形局部化引入本构模型是和以往模型的重要区别。通过与实验成果的对比分析,验证了模型的正确性和有效性。
Preparation of Laponite Bioceramics for Potential Bone Tissue Engineering Applications
Chuanshun Wang, Shige Wang, Kai Li, Yaping Ju, Jipeng Li, Yongxing Zhang, Jinhua Li, Xuanyong Liu, Xiangyang Shi, Qinghua Zhao
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0099585
Abstract: We report a facile approach to preparing laponite (LAP) bioceramics via sintering LAP powder compacts for bone tissue engineering applications. The sintering behavior and mechanical properties of LAP compacts under different temperatures, heating rates, and soaking times were investigated. We show that LAP bioceramic with a smooth and porous surface can be formed at 800°C with a heating rate of 5°C/h for 6 h under air. The formed LAP bioceramic was systematically characterized via different methods. Our results reveal that the LAP bioceramic possesses an excellent surface hydrophilicity and serum absorption capacity, and good cytocompatibility and hemocompatibility as demonstrated by resazurin reduction assay of rat mesenchymal stem cells (rMSCs) and hemolytic assay of pig red blood cells, respectively. The potential bone tissue engineering applicability of LAP bioceramic was explored by studying the surface mineralization behavior via soaking in simulated body fluid (SBF), as well as the surface cellular response of rMSCs. Our results suggest that LAP bioceramic is able to induce hydroxyapatite deposition on its surface when soaked in SBF and rMSCs can proliferate well on the LAP bioceramic surface. Most strikingly, alkaline phosphatase activity together with alizarin red staining results reveal that the produced LAP bioceramic is able to induce osteoblast differentiation of rMSCs in growth medium without any inducing factors. Finally, in vivo animal implantation, acute systemic toxicity test and hematoxylin and eosin (H&E)-staining data demonstrate that the prepared LAP bioceramic displays an excellent biosafety and is able to heal the bone defect. Findings from this study suggest that the developed LAP bioceramic holds a great promise for treating bone defects in bone tissue engineering.
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