Characterization of odorants in contrasting ecotypes of Lake Taihu: algae-dominated versus macrophyte-dominated zones

Environmental Science and Pollution Research - Globally, odorant incidents are occurring at an increasing frequency, magnitude, and duration under the dual influences of eutrophication and climate...     

西安郊区泾河秋、冬季大气黑碳变化及粒径特征

利用西安郊区泾河大气成分站ρ(BC)(BC为黑碳)、粒子数浓度资料和观象台自动站、探空站数据,对西安郊区秋、冬季ρ(BC)变化特征、粒径分布特征和变化原因进行了分析.结果表明:①泾河郊区ρ(BC)比城区的低.城区ρ(BC)日变化呈三峰特征,峰值分别出现在凌晨02:00、清晨07:00和傍晚20:00,分别为17.0、12.5和21.5 μg/m3.泾河郊区ρ(BC)日变化呈双峰特征,峰值出现在上午09:00和晚上23:00,数值分别为5.5和6.1μg/m3;谷值出现在清晨06:00和下午16:00,数值分别为4.9和2.6μg/m3.②ρ(BC)与不同粒径颗粒物数浓度关系不同,其中与粒径＜4.0 μm粒子的数浓度成正比,与粒径≥4.0 μm粒子(如沙尘)的数浓度成反比;波长指数分析表明,沙尘可致ρ(BC)实测值偏大.③ρ(BC)与近地面逆温强度有密切相关性,R(相关系数)达到0.412 5(P ＜0.000 1);风速小于1.5 m/s时BC易堆积,大于1.5 m/s时则相反;连续降水对BC清除效果显著.     

皖南-浙西-赣东北地区锰矿资源及潜力预测

本文从锰矿成矿地质背景，矿床类型及地质特征，成矿带及潜力预测，勘查程度及利用现状等方面皖赣相邻区锰矿资源，讨论了该区锰矿勘查工作远景及重要性。     

ICP-MS同时测定饮用水中25种元素的研究

采用电感耦合等离子体质谱(ICP-MS)对饮用水中25种元素进行同时测定,并对其方法进行了研究.结果表明用ICP-MS同时测定饮用水中25种元素,其最低检出限为Th 1.238 E-5μg/L;其RSD%均小于5%;加标回收率介于98.94～100.4%之间,具有较高的灵敏度、精密度和准确,特别是对一些浓度低达ng/L级,但对人体健康却产生重要影响的超痕量组分,如Tl、Th、U等的测定,本法具有其它传统分析难以满足的优势.应用于直接测定元素浓度范围从ng/L-mg/L级的实际样品,具有快速、简便、准确等优点.     

清洁生产思想在MBR膜污染控制中的应用

膜污染是限制膜生物反应器大规模应用的关键所在，本文试图将现代清洁生产的思想应用到膜污染控制之中。采取从源头控制、过程控制以及末端治理相结合的全过程控制方法，最大限度地减缓膜污染，从而加快MBR在实际工程中的应用。     

区域土地利用类型的胁迫转换与优化配置——以三峡库区为例

三峡大坝蓄水淹没土地、库区移民安置和新城及工矿迁建等带来了库区土地利用结构与布局的巨大变化。为此,如何构建符合景观生态学原理和可持续发展准则的宏观土地利用类型新格局,不仅是近10年内百万移民安置和生产布局的重点,而且关系到库区未来经济、社会与资源、环境的协调和可持续发展。论文分析了在土地淹没与置换的胁迫条件下,库区土地资源类型转换的方式与过程;从要素控制、地段设计到系统模式优化的不同层次,提出了库区土地生态设计模式与措施;并从产业协调发展的角度,提出了库区土地利用优化配置的方案。     

Development of emission factors for polycarbonate processing

Emission factors for selected volatile organic compounds (VOCs) and particulate emissions were developed while processing eight commercial grades of polycarbonate (PC) and one grade of a PC/acrylonitrile-butadiene-styrene (ABS) blend. A small commercial-type extruder was used, and the extrusion temperature was held constant at 304 degrees C. An emission factor was calculated for each substance measured and is reported as pounds released to the atmosphere/million pounds of polymer resin processed [ppm (wt/wt)]. Scaled to production volumes, these emission factors can be used by processors to estimate emission quantities from similar PC processing operations.     

水分对煤中瓦斯放散初速度影响研究

为了研究水分对煤中瓦斯放散初速度的影响,对水分含量分别为3%,5%及7%的不同粒径的煤样进行了测定,绘制了不同粒径煤中瓦斯放散初速度随水分变化的曲线图,并从煤对瓦斯的吸附、解吸特性及渗透率等方面深入全面地分析了产生该曲线变化趋势的原因。     

基于GMM模型的煤矿顶板事故致死人数预测

为了解决目前常用预测模型对随机波动性较大数据预测精度偏低的问题,文章在灰色预测GM(1,1)的基础上引入马尔可夫状态转移矩阵,建立了灰色马尔可夫预测模型(GMM),并将该法运用到煤矿顶板致死人数的预测中。经计算GMM模型的预测平均相对误差为1.181%,最大相对误差3.426%,与GM(1,1)法相比,后者精度分别提高了21倍和13倍。     

Prenatal diagnosis of holoprosencephaly in two fetuses with der (7)t(1;7)(q32;q32)pat inherited from the father with double translocations

The presence of two independent translocations in one person is rare. Herein, we report the prenatal diagnosis of two sibling fetuses with holoprosencephaly, whose father is a carrier of double translocations. The karyotype of the father is 46,XY, t(1;7) (q32;q32), t(14,15) (q32.1;q26.3). The two fetuses had variable facial dysmorphisms and identical cytogenetic abnormality—a derivative (7) t(1;7) (q32;q32) inherited from the father. The proband 1 showed a small mouth, a single median eye and a proboscis above the eye, while the proband 2 showed hypotelorism, a flat nose, cleft lip and cleft palate. Both fetuses also had alobar holoprosencephaly. Haploinsufficiency of the sonic hedgehog gene at 7q36 does account for the occurrence of holoprosencephaly in the two fetuses with a deletion of distal 7q (7q32 → qter). Copyright © 2003 John Wiley & Sons, Ltd.