西南山区某气井井场地基稳定性模拟分析

中国西南山区蕴藏着丰富的天然气资源,但随着开发规模的日益扩大,天然气井逐步转向山区这类地质环境恶劣的地区。本文以西南山区某气井为原型,在详细阐明井场区地质环境背景特征的基础上,首先对井场出现的典型地质问题——地下采空区进行定性判断和分析;之后选用F lac-2D有限差分软件,对井场加载前/后地下采空区可能造成的井场地基应力和变形特征,采用双洞和采空区这2种计算模型,进行数值模拟分析。模拟结果表明,井场加载前/后地基最大位移量为2 mm,地基局部地段出现拉应力区,但总体上地基稳定。研究结论将为后期建设中井场建筑物的优化布局及基础的选型提供依据。     

不同瓦斯压力下煤体力学特性试验研究

为研究瓦斯对煤体力学特性的影响,设计不同瓦斯压力条件下煤体单轴压缩试验,研究煤样力学参数及变形特征随瓦斯压力的变化趋势,探讨瓦斯对煤体力学性质的影响机制,得出单轴压缩下煤样力学参数,并记录煤样的破坏形态.研究结果表明:随瓦斯压力增大,应力-应变曲线压实阶段增大,弹性阶段缩小,失稳破坏后曲线缓慢下降,抗压强度和弹性模量单...     

干旱区2种猪毛菜萌发过程对水盐胁迫的生态响应

在实验室内模拟研究的基础上,运用生理生态学的原理,研究了水盐胁迫对钠猪毛菜(salsola nitraria)和散枝猪毛菜(salsola brachiata)种子萌发的影响,结果显示,钠猪毛菜与散枝猪毛菜种子萌发的最适温度分别为25 ℃和15 ℃.在盐溶液和PEG溶液中,2种种子的萌发规律相似,即随着水势的降低,萌发率和萌发速率下降.在盐胁迫下钠猪毛菜和散枝猪毛菜种子萌发的最低水势接近-7.2 MPa;在水分胁迫下2种种子萌发的最低水势均未超过-2.0 MPa,其中,钠猪毛菜种子表现出较强的耐水分胁迫能力.在相同水势条件下,PEG对2种猪毛菜种子萌发的抑制程度显著大于等渗NaCl,说明渗透胁迫是影响2种植物种子萌发的主要因素.     

顺倾山体采空侧滑致灾的复合应力场研究

本文分析了地下采空情况后认为，山体采空侧动，软弱夹层为决定性条件；其变动范围、速率、规模与性质，与地下采空有关的复合应力场有关。经对观测资料分析、仿真模型试验与仿真数值模拟的对比研究，揭露了顺倾山体的“复合临空面”条件下，“复合变动”的“复合应力场”。     

Thimerosal in childhood vaccines contributes to accumulating mercury toxicity in the kidney

Mercury (Hg) is a hazardous chemical that accumulates in many cells and tissues, thereby producing toxicity. The kidney is a key target organ for Hg accumulation and toxicity. The contributing factors to Hg accumulation in humans include: (1) elemental and inorganic Hg exposure, often occurring by inhalation of Hg vapors; (2) exposure to methyl Hg (meHg), for example, through contaminated seafood; and (3) exposure to ethyl mercury (etHg) via thimerosal-containing vaccines. Systematic investigations on the toxic effects of etHg/thimerosal on the nervous system were carried out, and etHg/thimerosal emerged as a possible risk factor for autism and other neurodevelopmental disorders. There is, however, little known about the mechanisms and molecular interactions underlying toxicity of etHg/thimerosal in the kidney, which is the focus of the current review. Susceptible populations such as infants, pregnant women, and the elderly are exposed to etHg through thimerosal-containing vaccines, and in-depth study of the potential adverse effects on the kidney is needed. In general, toxicity occurring in association with different forms of Hg is related to: intracellular thiol metabolism and oxidative stress reactions; mitochondrial function; intracellular distribution and build-up of calcium; apoptosis; expression of stress proteins; and also interaction with the cytoskeleton. Available evidence for the etHg-induced toxicity in the kidney was examined, and the main mechanisms and molecular interactions of cytotoxicity of etHg/thimerosal exposure in kidney described. Such accumulating knowledge may help to indicate molecular pathways that, if modulated, may better handle Hg-mediated toxicity.     

地表载荷对硬岩区埋地管道应力应变影响分析

为研究地表载荷对硬岩区埋地管道力学性能的影响,建立了管-土耦合三维数值模型,分析了地表载荷大小、作用面积、管道压力、管道径厚比及回填土弹性模量对管道应力分布、塑性应变、椭圆度的影响。结果表明:地表压载作用下,高应力区首先出现在管道顶部且呈椭圆形;随着地表载荷及其作用面积的增大,管道高应力区逐渐扩大,管道截面左右两侧也出现应力集中;随着回填土弹性模量、管道壁厚及内压的增加,管道顶部高应力区及最大等效应力均减小。塑性应变首先出现在管顶,且塑性区随地表载荷、载荷作用长度增加而增大,随回填土体弹性模量及管道壁厚增大而逐渐减小;当内压为0~4MPa时,管道塑性应变及塑性区随内压的增大而减小。管道椭圆度随回填土体弹性模量、管道内压、壁厚增加而逐渐减小,随地表压载增大而增大。     

前车突然切入时驾驶人应激生理特性研究

为研究前车突然切入对驾驶人生理负荷的影响,利用MP150生理监测系统对22名被试进行虚拟驾驶试验。采集记录前车突然切入时被试的生理参数。研究驾驶人心率增长率和心率变异性(HRV)指标与车速、应激距离之间的关系。结果表明:自车速度为100 km/h时,随着前车切入距离从55.6 m减小到27.8 m,被试的平均心率增长率从16.21%增大到23.27%,HRV参数低频(LF)值也呈现下降趋势。前车切入距离一定,随着自车车速从60 km/h增加到120 km/h,被试的平均心率增长率存在显著性差异,平均从13.05%上升到21.85%。差异性检验结果表明,前车切入距离和自车速度发生变化时驾驶人的生理负荷变化趋势一致,但自车速度因素对驾驶人生理负荷的影响程度高于切入距离因素。     

Involvement of mitochondrial-mediated caspase-3 activation and lysosomal labilization in acrylamide-induced liver toxicity

Acrylamide (ACR) is a chemical frequently used in both industrial and synthetic processes and may be produced during food processing. ACR at very high concentrations is postulated to exert its toxicity through the stimulation of an oxidative stress. ACR in excessive doses induces the central nervous system, reproduction, and genetic toxicity. However, ACR effects on the liver, a major organ of drug metabolism, have not been adequately explored. In addition, the role of mitochondria in an ACR-mediated hepatotoxicity is still unclear. The aim of this study was to investigate the cytotoxic mechanisms attributed to ACR using isolated rat hepatocytes. Hepatocytes were isolated by the collagenase perfusion method and incubated with an EC50_2hr concentration of ACR for 3 hr. The EC50_{2 hr} of ACR on isolated rat hepatocytes was determined to be 1 mM. Based on our results, hepatocytes cytotoxicity of ACR (1 mM) was mediated by a reactive oxygen species formation and lipid peroxidation. Incubation of hepatocytes with ACR produced rapid hepatocyte glutathione depletion which is another marker of the cellular oxidative stress. ACR cytotoxicity was also associated with mitochondrial injury as evidenced by the decline of mitochondrial membrane potential and lysosomal membrane leakiness. Our results also showed that ACR induced caspase-3 activation, the final mediator of apoptosis signaling. These findings contribute to a better understanding underlying mechanisms involved in ACR hepatotoxicity originating from the oxidative stress and ending in mitochondrial/lysosomal damage and cell death signaling.     

Influence of hypothyroidism on oxidative stress,c-Fos expression,cell cycle,and apoptosis in rats testes

The molecular basis of male reproduction for cross-regulation between androgen and thyroid hormone axes is still rudimentary. This study aims to define a possible mechanism of hypothyroidism-induced reproductive influence with respect to sex hormone, mineral, sperm motility, oxidative stress, c-Fos expression, cell cycle, and apoptosis in rat testes. The Wistar rats were randomly divided into control group (NS) and hypothyroidism group [1 ml/100g BW/day, 0.1% propylthiouracil (PTU)] by intragastric gavage for 60 days. Blood samples were collected to measure the serum levels. The epididymis was excised to measure sperm motility and testes were excised to measure mineral, oxidative stress, c-Fos expression, cell cycle, and apoptosis. After 60 days, body weight, relative testes weight, triiodothyronine, and total thyroxine were all significantly decreased, whereas thyroid stimulating hormone was increased in the hypothyroidism group. A significant increase in sex hormone level of estradiol (E2) and significant decreases in testosterone (T) and T/E2 ratio were observed following PTU treatment. And sperm quality was also significantly changed. There were significant decreases in the contents of calcium (Ca²⁺) and zinc (Zn²⁺). On the other hand, malondialdehyde and hydrogen peroxide contents significantly increased, whereas the activity of superoxide dismutase, catalase and nitric oxide synthase and nitric oxide content significantly decreased in hypothyroid rats. The mRNA and protein expressions of c-Fos decreased significantly. The cell percentage in G0/G1 phase increased significantly, whereas decreased significantly in S and G2/M phases. Also, a significant increase in testicular cell apoptosis was observed in hypothyroid-treated rats. These results suggested that hypothyroidism could affect reproductive function in the form of changed sex hormone levels, sperm motility and testicular Ca²⁺ and Zn²⁺, and enhanced oxidative stress leading to c-Fos abnormal expression and increased apoptosis.