综放工作面沿空留巷支护阻力研究

为了计算综放工作面沿空留巷支护阻力,以结构力学理论为基础,分析综放工作面沿空留巷支护阻力计算模型,建立沿空留巷围岩和支护体的结构力学模型,应用超静定结构和静定结构分析支护体与沿空留巷围岩相互作用机制,推导出巷旁支护阻力的计算公式.结果表明,进行沿空留巷支护阻力力学分析时,要考虑顶板极限断裂前和断裂后两种状态下的受力情况,支护阻力与岩层厚度、容重、煤体极限平衡区宽度、跨距、支护体宽度和巷道宽度等因素密切相关.工业性试验表明,该技术的应用是成功而有效的.因此,综放巷内沿空留巷围岩结构力学模型和支护阻力计算公式是合理的,可在类似条件的综放工作面中应用.     

雷击时地下空间电磁场与负载感应电磁场的仿真计算

随着高新电子技术的迅猛发展,雷电电磁辐射给人们的生产生活造成的危害越来越大。为了分析雷电电磁辐射的危害,基于MTLE雷电回击模型,以及北京地区实测雷电流波形,采用三维时域有限差分(FDTD)方法,计算了雷击时地下空间中的电磁场,并对线缆终端负载进行了雷电电磁耦合,计算了负载上的雷电感应电压和感应电流。计算结果表明,土壤对雷电电磁场的屏蔽并不彻底,地下空间仍需要进行防雷设计;线缆终端负载上感应的电压和电流峰值可达数百千伏和数百安培,并且其数值随雷电波波头时间的减小而增大,对当前大多数自动化系统危害严重。     

含酸油脱水影响因素及处理技术研究进展

文章在介绍油田含酸油来源的基础上,详细阐述了国内外关于影响含酸油脱水因素的研究进展,分析表明:含酸油pH值在6~8范围外,原油脱水率均小于85%;不同酸对原油脱水影响不同,其影响程度一般为残酸土酸盐酸;原油中酸化淤渣越多,油水界面膜稳定性越高,酸化油脱水难度越大;酸化油中亲水固体颗粒趋向于水包油型乳状液,亲油固体颗粒趋向于油包水型乳状液,固体颗粒的粒径越小,形成乳状液越稳定;酸化油中胶质、沥青质越高,油水乳状液相对越稳定。最后综述了中和预处理法、水洗法、化学破乳法、超声波辅助法以及联合破乳法对含酸油有效的破乳方法,介绍了这几种破乳方法的适用范围,并建议处理含酸油时,应先弄清影响含酸油脱水的主要因素,采用合适的脱水方法,提高含酸油脱水效率。     

江苏陆地海岸线绿潮藻种类组成及分布特征

2012年12月—2013年5月对江苏启东蒿枝港至连云港西大堤长约730 km岸线内的69个岸滩堤坝站点进行了绿潮藻种类组成及数量分布调查.结果表明:绿潮藻出现的站点占总设置站点的26.09%,出现绿潮藻岸线长度约占整个江苏调查岸线长度的22.83%;岸滩上绿潮藻主要生长在沿岸石堤、养殖围坝和植被较浅相对稀疏的草滩上,绿潮藻种类组成主要有浒苔(Ulva prolifera)、曲浒苔(Ulva flexuosa)和缘管浒苔(Ulva linza).1—3月浒苔为主要优势种,4—5月曲浒苔为主要优势种,缘管浒苔在历次调查中其湿重生物量均很低.5月岸滩上固着绿潮藻量约36.7 t,不及海上飘来附着在岸滩上绿潮藻量的1/10,岸滩上固着绿潮藻中浒苔的量约为同期海上飘来浒苔湿重生物量的0.6%,岸滩堤坝不会是引起绿潮暴发的主要源头.     

围生期毒死蜱暴露致子代8周雄鼠睾丸组织的氧化损伤

毒死蜱是目前全世界使用和销售量最大的有机磷杀虫剂之一。为探讨围生期毒死蜱暴露致8周雄性子鼠睾丸组织的氧化损伤,选择健康Wistar妊娠母鼠于妊娠期(gestation days,GD)第6天至子鼠出生后(postnatal days,PND)21天通过灌胃染毒0、0.75、1.35和2.70 mg·kg~(-1)剂量的毒死蜱,待雄性子鼠8周龄取左侧睾丸实施组织病理学检查,右侧睾丸用以检测丙二醛(maleic dialdehyde,MDA)的含量和谷胱甘肽S转移酶(glutathione S transferases,GST)、谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)、总超氧化物歧化酶(total superoxide dismutase,T-SOD)的活力。结果表明,与对照组比较,随着染毒剂量的增加子鼠体重和睾丸、附睾脏器系数有下降的趋势(P0.05);而MDA呈升高趋势(P0.05)。各组T-SOD和1.35、2.70 mg·kg~(-1)剂量组GSH-Px活力的下降及2.70 mg·kg~(-1)剂量组GST活力的升高均有统计学意义(P0.05)。睾丸组织病理学检查结果可见2.70mg·kg~(-1)剂量组睾丸组织有明显的损伤,管腔中精液量减少,生精细胞脱落增多。上述研究结果提示母鼠于围生期暴露于毒死蜱,可通过氧化损伤诱导子代雄性大鼠睾丸的毒性作用。     

胎盘内多环芳烃分布及源解析研究

探讨多环芳烃在胎盘中的分布,并对其进行源解析。从2012年6月—2013年6月在云南省第一人民医院产科分娩的产妇中随机抽取30例,利用气相色谱-质谱联用仪(GC-MS)检测其胎盘中多环芳烃的含量;比较胎盘的中央部分和边缘部分多环芳烃含量的差异;对多环芳烃进行源解析,探讨其主要来源。胎盘中检测到多种多环芳烃成分;其中2~4个苯环的多环芳烃占总量的90%以上,尤其是萘、苊、芴、菲、蒽、芘、荧蒽的含量较高;萘、苊烯、苊、茚并(1,2,3-c,d)芘、二苯并(a,h)蒽5种多环芳烃在胎盘中央的含量高于边缘,具有显著性差异(P0.05),其他多环芳烃在胎盘中央和边缘的含量无显著性差异(P0.05)。多环芳烃源解析提示80%研究对象体内的多环芳烃主要来自石油产品的燃烧或暴露于石油产品。     

辽河口粪便污染指示菌的时空分布特征

2013年分别于夏季和秋季对辽河口海域的粪便污染指示菌(总大肠菌群、粪大肠菌群和肠球菌)及环境、水化学要素进行分析,研究粪便污染指示菌在海水中的数量、分布特征及其与环境、水化学指标间的相关性,在此基础上,选取河口地区合适的粪便污染指示菌.结果表明:夏季总大肠菌群数量在1.7×105~6.2×106CFU·L-1之间,粪大肠菌群数量在5.0×102~8.7×104CFU·L-1之间,肠球菌数量在1.0×101~2.5×102CFU·L-1之间;秋季总大肠菌群数量在5.0×102~1.1×105CFU·L-1之间,粪大肠菌群数量在4.0×102~1.0×103CFU·L-1之间,肠球菌数量在3~95 CFU·L-1之间.总大肠菌群、粪大肠菌群和肠球菌的数量变化与环境指标之间有着密切联系,特别是与盐度存在显著相关性;粪大肠菌群、肠球菌与水化学指标Si O4-4-Si、NH+4-N、TP和COD之间均存在显著相关性;其中粪大肠菌群与SiO4-4-Si和TP的相关性系数均大于0.742(p0.01),肠球菌与TP和COD的相关性系数均大于0.742.实验结果表明,辽河口粪便污染指示菌的数量在夏季高于秋季,近岸高于远海,其中粪大肠菌群和肠球菌的数量、分布特征与陆源污染物特别是氮磷的输入量密切相关,而且两者之间呈显著正相关关系.粪大肠菌群与肠球菌在一定程度上可以反映河口粪便污染情况,建议采用粪大肠菌群与肠球菌作为河口粪便污染的指示菌.     

水环境中不同形态氮对甲芬那酸光降解影响机制的研究

研究了紫外光照射下水环境中不同形态的无机氮(NO-3、NO-2和NH+4)对甲芬那酸(MEF)光解的影响.NO-3与NO-2均促进MEF的光解,NH+4对MEF的光解基本无影响;在NO-3、NO-2存在下添加适量异丙醇,显著抑制MEF的降解,实验表明NO-3、NO-2在光照下产生了·OH并参与对MEF的氧化降解.同时模拟研究了水体处于不同p E值下,水中存在的不同形态的无机氮对MEF光解的复合影响,其对MEF光解促进作用不是简单的叠加关系,增大p E值,MEF的光解速率先增大后减小.当NO-2和NH+4共存时,对MEF的光解主要表现为NO-2的影响;当NO-2和NO-3共存时,两者对MEF的光解存在拮抗作用.     

Changes in nitrogen budget and potential risk to the environment over 20 years (1990–2010) in the agroecosystems of the Haihe Basin,China

The nitrogen balance can serve as an indicator of the risk to the environment of nitrogen loss from agricultural land. To investigate the temporal and spatial changes in agricultural nitrogen application and its potential threat to the environment of the Haihe Basin in China, we used a database of county-level agricultural statistics to calculate agricultural nitrogen input, output, surplus intensity, and use efficiency. Chemical fertilizer nitrogen input increased by 51.7% from 1990 to 2000 and by 37.2% from 2000 to 2010, concomitant with increasing crop yields. Simultaneously, the nitrogen surplus intensity increased by 53.5% from 1990 to 2000 and by 16.5% from 2000 to 2010, presenting a continuously increased environmental risk. Nitrogen use efficiency decreased from 0.46 in 1990 to 0.42 in 2000 and remained constant at 0.42 in 2010, partly due to fertilizer composition and type improvement. This level indicates that more than half of nitrogen inputs are lost in agroecosystems. Our results suggest that although the improvement in fertilizer composition and types has partially offset the decrease in nitrogen use efficiency, the environmental risk has still increased gradually over the past 20 years, along with the increase in crop yields and nitrogen application. It is important to achieve a better nitrogen balance through more effective management to significantly reduce the environmental risk, decrease nitrogen surplus intensity, and increase nitrogen use efficiency without sacrificing crop yields.     

Risk assessment of Giardia from a full scale MBR sewage treatment plant caused by membrane integrity failure

Membrane bioreactors (MBR) are highly efficient at intercepting particles and microbes and have become an important technology for wastewater reclamation. However, many pathogens can accumulate in activated sludge due to the long residence time usually adopted in MBR, and thus may pose health risks when membrane integrity problems occur. This study presents data from a survey on the occurrence of water-borne Giardia pathogens in reclaimed water from a full-scale wastewater treatment plant with MBR experiencing membrane integrity failure, and assessed the associated risk for green space irrigation. Due to membrane integrity failure, the MBR effluent turbidity varied between 0.23 and 1.90 NTU over a period of eight months. Though this turbidity level still met reclaimed water quality standards (≤5 NTU), Giardia were detected at concentrations of 0.3 to 95 cysts/10 L, with a close correlation between effluent turbidity and Giardia concentration. All β-giardin gene sequences of Giardia in the WWTP influents were genotyped as Assemblages A and B, both of which are known to infect humans. An exponential dose-response model was applied to assess the risk of infection by Giardia. The risk in the MBR effluent with chlorination was 9.83 × 10^-3, higher than the acceptable annual risk of 1.0 × 10^-4. This study suggested that membrane integrity is very important for keeping a low pathogen level, and multiple barriers are needed to ensure the biological safety of MBR effluent.