巷道布置对围岩稳定性影响的数值模拟

采用理论分析不同应力场下巷道轴线与最大水平主应力方向夹角的最佳角度,利用数值模拟不同夹角情况下,巷道围岩应力分布、正前方应力分布及变形特征。得出：1）最大水平主应力σH〉最小水平主应力σh〉垂直主应力σr时,最佳角度为0°;σt〉σH〉σh时,最佳角度为90°;σH〉σa〉σA时,最佳夹角为α0.2）巷道开挖后,水平应力在两帮出现应力降低区,在顸、底板出现应力集中区;垂直应力在两帮出现应力集中区,在顶、底板出现应力降低区;随角度变化,应力变化区均有明显变化,正前方断面的最大主应力变化明显。3）巷道达到最佳角度时,围岩变形相对较小,最大主应力围绕在巷道周边,呈环状或类环状分布;其它角度时,围岩变形相对较大,最大主应力逐渐向顶、底板的四角或两帮发展。     

Auswirkungen einer definierten Belastung auf die Enzymaktivitäten im Blutplasma bei der Maus Effects of a definite stress on the enzyme activities in blood plasma in mice

Summary The present study was designed to analyze the effects of a short term stress on the quantitative levels of alkaline phosphatase (AP), creatine phosphokinase (CK), aldolase (ALD), lactate dehydrogenase (LDH), and lactate dehydrogenase-1-isoenzyme (LDH 1) during 24 h after stress. For all the enzymes studied higher values for the activity were found due to stress in comparison to the activity level before the stress. The period during the 24 h after stress to reach maximum activity depends on the enzyme and in part on the sex of the animal.     

Effects of a definite stress on the enzyme activities in blood plasma in mice (author's transl)

The present study was designed to analyze the effects of a short term stress on the quantitative levels of alkaline phosphatase (AP), creatine phosphokinase (CK), aldolase (ALD), lactate dehydrogenase (LDH), and lactate dehydrogenase-1-isoenzyme (LDH 1) during 24 h after stress. For all the enzymes studied higher values for the activity were found due to stress in comparison to the activity level before the stress. The period during the 24 h after stress to reach maximum activity depends on the enzyme and in part on the sex of the animal.     

Mechanisms regulating immune surveillance of cellular stress in cancer

The purpose of this review is to explore immune-mediated mechanisms of stress surveillance in cancer, with particular emphasis on the idea that all cancers have classical hallmarks (Hanahan and Weinberg in Cell 100:57–70, 67; Cell 144:646–674, 68) that could be interrelated. We postulate that hallmarks of cancer associated with cellular stress pathways (Luo et al. in Cell 136:823–837, 101) including oxidative stress, proteotoxic stress, mitotic stress, DNA damage, and metabolic stress could define and modulate the inflammatory component of cancer. As such, the overarching goal of this review is to define the types of cellular stress that cancer cells undergo, and then to explore mechanisms by which immune cells recognize, respond to, and are affected by each stress response.     

Osmotic stress signaling via protein kinases

Plants face various kinds of environmental stresses, including drought, salinity, and low temperature, which cause osmotic stress. An understanding of the plant signaling pathways that respond to osmotic stress is important for both basic biology and agriculture. In this review, we summarize recent investigations concerning the SNF1-related protein kinase (SnRK) 2 kinase family, which play central roles in osmotic stress responses. SnRK2s are activated by osmotic stress, and a mutant lacking SnRK2s is hypersensitive to osmotic stress. Many questions remain about the signaling pathway upstream and downstream of SnRK2s. Because some SnRK2s also functions in the abscisic acid (ABA) signaling pathway, which has recently been well clarified, study of SnRK2s in ABA signaling can provide clues regarding their roles in osmotic stress signaling.     

Cellular responses to mild heat stress

Since its discovery in 1962 by Ritossa, the heat shock response has been extensively studied by a number of investigators to understand the molecular mechanism underlying the cellular response to heat stress. The most well characterized heat shock response is induction of the heat shock proteins that function as molecular chaperones and exert cell cycle regulatory and anti-apoptotic activities. While most investigators have focused their studies on the toxic effects of heat stress in organisms such as severe heat stress-induced cell cycle arrest and apoptosis, the cellular response to fever-ranged mild heat stress has been rather underestimated. However, the cellular response to mild heat stress is likely to be more important in a physiological sense than that to severe heat stress because the body temperature of homeothermic animals increases by only 1–2°C during febrile diseases. Here we provide information that mild heat stress does have some beneficial role in organisms via positively regulating cell proliferation and differentiation, and immune response in mammalian cells.Received 14 May 2004; received after revision 2 August 2004; accepted 16 August 2004     

Stress and the nonsense-mediated RNA decay pathway

Cells respond to internal and external cellular stressors by activating stress-response pathways that re-establish homeostasis. If homeostasis is not achieved in a timely manner, stress pathways trigger programmed cell death (apoptosis) to preserve organism integrity. A highly conserved stress pathway is the unfolded protein response (UPR), which senses excessive amounts of unfolded proteins in the ER. While a physiologically beneficial pathway, the UPR requires tight regulation to provide a beneficial outcome and avoid deleterious consequences. Recent work has demonstrated that a conserved and highly selective RNA degradation pathway—nonsense-mediated RNA decay (NMD)—serves as a major regulator of the UPR pathway. NMD degrades mRNAs encoding UPR components to prevent UPR activation in response to innocuous ER stress. In response to strong ER stress, NMD is inhibited by the UPR to allow for a full-magnitude UPR response. Recent studies have indicated that NMD also has other stress-related functions, including promoting the timely termination of the UPR to avoid apoptosis; NMD also regulates responses to non-ER stressors, including hypoxia, amino-acid deprivation, and pathogen infection. NMD regulates stress responses in species across the phylogenetic scale, suggesting that it has conserved roles in shaping stress responses. Stress pathways are frequently constitutively activated or dysregulated in human disease, raising the possibility that “NMD therapy” may provide clinical benefit by downmodulating stress responses.     

区域构造应力场对煤与瓦斯突出影响的数值模拟分析

依据地质动力区划方法,对鹤壁八矿进行Ⅰ～Ⅴ级活动断裂划分,确定了区域构造的特征。分析了煤层的顶板岩性和构造断裂特点,并在此基础上建立了构造应力计算模型。结合对矿区地应力测量和岩体应力状态分析,确定了岩体应力状态的分布规律。通过对结果的分析,认为区域构造应力场控制鹤壁八矿地应力的分布状态,从而决定煤与瓦斯突出呈区域性分布。确定了易发生煤与瓦斯突出的应力升高区的位置,为开采煤层时何时何地采取防突措施提供了科学依据。     

Rapid development and a long life: an association expected under a stress theory of aging

Life span and development time are considered in the context of the abiotic stresses to which free-living organisms are normally exposed. Under these circumstances, long life span depends upon metabolically efficient stress-resistance genes, which tend to be heterozygous. Similarly, rapid development time tends to be a feature of heterozygous stress-resistant individuals. Therefore, individuals who have high inherited stress resistance should develop fastest and live longest; in addition, they should show high homeostasis in the face of the energy costs of stress. In this way, the stress theory of aging can incorporate the developmental stage, based upon oxidative stress as an important major direct challenge.     

The use of metabolomics to dissect plant responses to abiotic stresses

Plant metabolism is perturbed by various abiotic stresses. As such the metabolic network of plants must be reconfigured under stress conditions in order to allow both the maintenance of metabolic homeostasis and the production of compounds that ameliorate the stress. The recent development and adoption of metabolomics and systems biology approaches enable us not only to gain a comprehensive overview, but also a detailed analysis of crucial components of the plant metabolic response to abiotic stresses. In this review we introduce the analytical methods used for plant metabolomics and describe their use in studies related to the metabolic response to water, temperature, light, nutrient limitation, ion and oxidative stresses. Both similarity and specificity of the metabolic responses against diverse abiotic stress are evaluated using data available in the literature. Classically discussed stress compounds such as proline, γ-amino butyrate and polyamines are reviewed, and the widespread importance of branched chain amino acid metabolism under stress condition is discussed. Finally, where possible, mechanistic insights into metabolic regulatory processes are discussed.     

Hsp70 in myocardial ischaemia

Numerous reports suggest that stress protein accumulation confers protection in various mammalian tissues against differing stresses. The purpose of this article is to review the evidence that stress proteins, in particular hsp70, are able to alter the resistance of the heart to subsequent ischaemic and non-ischaemic injury and to discuss the possible physiological basis for this apparent protection. The possible, though unlikely involvement of heat stress proteins in classical ischaemic preconditioning is addressed as is the possibility of their involvement in a delayed second window of protection.     

电子封装热应力数值分析

针对目前电子封装的封装密度越来越高、封装厚度越来越薄、封装体在基板上所占面积越来越大,发热引起的失效越来越严重等问题,以晶体管瞬态热应力分析为例,建立热力耦合力学模型.利用ansys研究电子封装热失效问题,得到温度场、应力场和变彤场的分布规律.温度和应力的主要规律包括两点,一是温度和应力都在角点处变化明显,应力比较集中.温度从上到下逐层变化,逐渐减小,并且层与层之间温度变化不大,模型中间部分温度层厚度几乎相同,下半部分同一温度层有规律的变化.二是当温度较高时,在受约束面上和角点处应力值较大,并且在模型的角点和中部出现应力集中现象.     

Effect of stress on choline acetyltransferase activity of the brain and the adrenal of the rat.

Choline acetyltransferase (ChAT) activity was determined in cerebral cortex, hypothalamus, hippocampus, cerebellum, medulla oblongata, midbrain and adrenal gland of rats exposed to acute or chronic stress. The exposure of animals to acute immobilization and cold stress (4 degrees C) for one hour resulted in a significant decline of ChAT activity in all brain regions examined except for the medulla oblongata. Moreover, the exposure to acute stress resulted in significant increase of the same enzyme in the adrenal gland. However, chronic exposure of animals to cold stress (4 degrees C) for 7 days resulted in no significant changes of ChAT activity in all tissues examined except for a decline in the midbrain and an increase in the medulla oblongata. The administration of corticosterone (2.0 mg/kg) 1 h prior to sacrificing caused an effect similar to that of acute stress on ChAT activity in all brain regions except for the hypothalamus and the cerebellum. It was concluded from this experiment that stress-induced changes in the ChAT activity of specific brain regions might be mediated by the adrenal steroids.     

The influence of cold or isolation stress on resistance of mice to West Nile virus encephalitis

The effect of cold or isolation stress on mortality rate and brain virus level were investigated in mice infected with West Nile virus (WNV). Exposure of mice for 5 min/day to cold water (1 +/- 0.5 degrees C) for 8-10 days resulted in 92% mortality as compared to 47% in control mice (p less than 0.001). Mice housed in individual cages (isolation stress) were also more susceptible to WN viral infection, as shown by increased mortality rate reaching 85% as compared to 50% in mice housed 6 per cage (p less than 0.01). Cold or isolation stress increased blood brain and spleen virus levels as early as 2 days after inoculation. After 8 days of isolation or cold stress, mice inoculated with WNV had 8.9 and 9.0 log10 plaque forming units in the brain, respectively, as compared to 6.9 in the control (p less than 0.01-0.001). Furthermore, lymphoid organs such as spleen and thymus showed severe mass loss. These data suggest that physical or non-physical stress situations enhance WNV encephalitis by accelerating virus proliferation and increase mortality in mice.     

Stress-induced increase in noradrenaline release in the rat hypothalamus assessed by intracranial microdialysis

The hypothalamic microdialysis of conscious rats was used to investigate the effects of immobilization stress (20 min) on extracellular noradrenaline (NA) levels. The stress significantly increased NA levels relative to basal efflux by 106% and this elevation continued for 40 min after release from stress.     

Stress-induced increase in noradrenaline release in the rat hypothalamus assessed by intracranial microdialysis

Summary The hypothalamic microdialysis of conscious rats was used to investigate the effects of immobilization stress (20 min) on extracellular noradrenaline(NA) levels. The stress significantly increased NA levels relative to basal efflux by 106% and this elevation continued for 40 min after release from stress.     

The influence of cold or isolation stress on resistance of mice to West Nile virus encephalitis

Summary The effect of cold or isolation stress on mortality rate and brain virus level were investigated in mice infected with West Nile virus (WNV). Exposure of mice for 5 min/day to cold water (1±0.5°C) for 8–10 days resulted in 92% mortality as compared to 47% in control mice (p<0.001). Mice housed in individual cages (isolation stress) were also more susceptible to WN viral infection, as shown by increased mortality rate reaching 85% as compared to 50% in mice housed 6 per cage (p<0.01). Cold or isolation stress increased blood brain and spleen virus levels as early as 2 days after inoculation. After 8 days of isolation or cold stress, mice inoculated with WNV had 8.9 and 9.0 log₁₀ plaque forming units in the brain, respectively, as compared to 6.9 in the control (p<0.01–0.001). Furthermore, lymphoid organs such as spleen and thymus showed severe mass loss. These data suggest that physical or non-physical stress situations enhance WNV encephalitis by accelerating virus proliferation and increase mortality in mice.     

Prenatal stress and postnatal androgen: Effects on reproduction in female rats

Summary Heat-restraint stress applied to pregnant rats during the last trimester disrupts oestrus cycles in female offspring and alters adrenal, ovarian and uterine weights at autopsy. Sexual receptivity is left intact. Prenatal stress may operate by increasing exposure of fetal females to androgens in utero.     

基于ANSYS的集汽集箱蒸汽出口应力分析

针对蒸汽锅炉集汽集箱蒸汽出口部位采用有限元分析软件ANSYS建立三维模型,并对其进行应力分析,得出应力分布规律。此外,对蒸汽出口接管和集箱筒体相贯区域的应力分布状况进行了深入研究,绘出相贯区域内表面的各种应力分布曲线,并对应力较高位置采用线法进行强度评定,以确定应力强度是否符合设计要求,可以有效地保证锅炉运行的安全可靠性,具有重要的理论意义和实用价值。