丁酸胁迫对产氢污泥以厨余为底物的产氢影响

采用丁酸对产氢污泥进行胁迫处理,经胁迫后的污泥接种厨余垃圾进行产氢实验,考察丁酸胁迫对提高产氢性能的影响。结果表明,低浓度胁迫能提高产氢污泥的耐丁酸性,从而提高产氢量,而胁迫浓度过高则抑制产氢污泥活性,胁迫浓度呈"horm esis"效应。实验采用的4 g/L胁迫浓度为最佳,反应结束后,丁酸浓度和产氢量分别为8 417.1 mg/L和63.72 mL/g VS,比空白提高了31.3%和114%。产氢过程中SCOD的主要来源是有机酸。对产氢污泥胞外多聚物(EPS)的测定表明,厨余垃圾酸化速率、氢气产生速率和EPS总量成正相关。     

Effect of gender on physiological and behavioural responses of Gammarus roeseli (Crustacea Amphipoda) to salinity and temperature

The importance of potentially interacting factors in organisms responses to a stress are often ignored or underestimated in ecotoxicology. In laboratory experiments we investigated how gender, temperature and age influence the behaviour and the physiology of the freshwater amphipod Gammarus roeseli under salinity stress. Our results revealed a significant higher sensitivity of females in survival, ventilation and ionoregulation whereas no inter-age differences were reported. Water temperature also exerted a significant effect in survival and ventilation of G. roeseli. Some of those factors appeared to interact significantly. This study provides evidence that gender can affect organisms responses to a stressor and consequently has to be considered while assessing a stress impact. We discussed the potential relationships between biological and behavioural responses.     

Influence of arsenic stress on synthesis and localization of low-molecular-weight thiols in Pteris vittata

The roles of low-molecular-weight thiols (LMWTs), such as glutathione and phytochelatins, in arsenic (As) tolerance and hyperaccumulation in Pteris vittata an As-hyperaccumulator fern remain to be better understood. This study aimed to thoroughly characterize LMWT synthesis in P. vittata to understand the roles played by LMWTs in As tolerance and hyperaccumulation. LMWT synthesis in P. vittata was induced directly by As, and not by As-mediated oxidative stress. Expression of PvECS2, one of the putative genes of γ-glutamylcysteine synthetase (γECS), increases in P. vittata shoots at 48 h after the onset of As exposure, almost corresponding to the increase in the concentrations of γ-glutamylcysteine and glutathione. Furthermore, localization of As showed similar trends to those of LMWTs in fronds at both whole-frond and cellular levels. This study thus indicates the specific contribution of LMWTs to As tolerance in P. vittata. γECS may be responsible for the As-induced enhancement of LMWT synthesis.     

The impact of ambient ozone on mountain spruce forests in the Czech Republic as indicated by malondialdehyde

Malondialdehyde (MDA), a product of lipid peroxidation and biomarker of oxidative stress, is measured over the long term in spruce Picea abies needles under real conditions in three Czech mountain border areas. The trends presented collate the MDA content in spruce needles with ambient ozone, temperature and precipitation as casual, and defoliation as a subsequent factor for the period 1994-2006. We have found the overall decreasing trends in MDA and defoliation. The highest MDA and defoliation are recorded in the Jizerske, the lowest in the Krusne hory Mts. Out of the examined variables the MDA is predicted best by mean temperature in vegetation season, median of O₃ concentrations and AOT40; these three variables account for 34% of MDA1 and 36% of MDA2 variability. Our hypothesis that higher ambient O₃ exposure results in higher MDA contents in P. abies needles under real conditions has not been approved.     

混合集成电路HALT和HASS技术应用研究

介绍了HALT和HASS技术的概念和内涵,探讨了混合集成电路HALT和HASS技术应用的基本原理以及具体的应用方法和流程。     

道路车辆电气及电子设备在振动试验中的应力循环和试验设计原则

本文试从振动试验的特点和受试样品承受振动激励的应力循环切入分析,为把握试验方案的拟订提供支持。同时也简要介绍了应力循环的计算方法,供试验人员参考使用。     

The living environment and children's fears following the Indonesian tsunami

The tsunami that struck South-east Asia on 26 December 2004 left more than 500,000 people in Aceh, Indonesia, homeless and displaced to temporary barracks and other communities. This study examines the associations between prolonged habitation in barracks and the nature of fears reported by school-age children and adolescents. In mid-2007, 30 months after the tsunami, the authors interviewed 155 child and parent dyads. Logistic regression analysis was used to compare the fears reported by children and adolescents living in barracks with those reported by their peers who were living in villages. After adjusting for demographic factors and tsunami exposure, the data reveals that children and adolescents living in barracks were three times more likely than those living in villages to report tsunami-related fears. The study demonstrates that continued residence in barracks 30 months after the tsunami is associated with higher rates of reporting tsunami-related fears, suggesting that barracks habitation has had a significant impact on the psychological experience of children and adolescents since the tsunami.     

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。     

断裂构造对斜坡应力场影响的数值模拟及成灾机理研究

断裂构造及活动强度对斜坡体的应力场分布具有重要的影响。采用基于强度折减法的有限元法,分别以正断层和逆断层与斜坡体的组合关系为例,剖析了断裂构造对斜坡体应力场的影响及成灾机理,揭示了含有断层的斜坡体塑性区的贯通过程。研究表明,包含断层的斜坡体在应力分布特征及斜坡变形破坏机理方面与无断层的斜坡体有较大差别:含断层的斜坡体在坡面和断层面附近的最大主应力迹线与坡面或断层面相平行,在天然状态下,塑性区同时出现在坡脚和断层面后方,随着折减系数的增大,塑性区分别从坡脚和断层面后方向坡体深部和上部发展,直至断层面前后两个塑性区相贯通,坡体发生破坏,并且对坡体变形破坏的影响程度以逆断层最强,其次为正断层,断层不活动时较弱。     

Biochemical biomarkers in Nile tilapia (Oreochromis niloticus) after short-term exposure to diesel oil, pure biodiesel and biodiesel blends

Fossil fuels such as diesel are being gradually replaced by biodiesel, a renewable energy source, cheaper and less polluting. However, little is known about the toxic effects of this new energy source on aquatic organisms. Thus, we evaluated biochemical biomarkers related to oxidative stress in Nile tilapia (Oreochromis niloticus) after two and seven exposure days to diesel and pure biodiesel (B100) and blends B5 and B20 at concentrations of 0.01 and 0.1 mL L⁻¹. The hepatic ethoxyresorufin-O-deethylase activity was highly induced in all groups, except for those animals exposed to B100. There was an increase in lipid peroxidation in liver and gills in the group exposed to the higher concentration of B5. All treatments caused a significant increase in the levels of 1-hydroxypyrene excreted in the bile after 2 and 7 d, except for those fish exposed to B100. The hepatic glutathione-S-transferase increased after 7 d in animals exposed to the higher concentration of diesel and in the gill of fish exposed to the higher concentration of pure diesel and B5, but decreased for the two tested concentrations of B100. Superoxide dismutase, catalase and glutathione peroxidase also presented significant changes according to the treatments for all groups, including B100. Biodiesel B20 in the conditions tested had fewer adverse effects than diesel and B5 for the Nile tilapia, and can be suggested as a less harmful fuel in substitution to diesel. However, even B100 could activate biochemical responses in fish, at the experimental conditions tested, indicating that this fuel can also represent a risk to the aquatic biota.