Heteroduplex formation: A potential source of genotyping error from PCR products

The formation of heteroduplexes from polymerase chain reaction (PCR) products has recently become a diagnostic tool that is routinely used for the prenatal detection of small deletions or insertions in a number of disease-causing alleles. We present evidence illustrating that heterozygous PCR products can manifest ‘invisible’ heteroduplexes that can ultimately lead to genotyping errors. Justifications for these ‘invisible’ heteroduplexes and requisite parameters to optimize their detection are presented.     

芬顿氧化法处理水中酸性品红的研究

研究了酸性品红在Fenton体系中的降解过程,反应30 min后,在[Fe2+]0=0.06 mmol/L、[H2O2]0=0.3 mmol/L、pH=3、T=30℃的条件下,初始浓度为20 mg/L的酸性品红的去除率达到97%以上。升高反应温度,有利于Fenton体系中酸性品红的降解,但影响并不显著。根据不同温度下的速率常数,并结合Arrhenius方程求出了Fenton试剂降解酸性品红的反应活化能,仅为11.63 kJ/mol。C1?的存在对酸性品红在Fenton体系中的降解表现出明显的阻碍作用,并且随着C1?浓度的增加,抑制作用越来越大;SO24-和NO3-的存在也降低了Fenton试剂的氧化性能。     

滑坡灾害危险性评价信息图谱研究——以福建省莆田市为例

近年来,滑坡灾害频繁发生且极大地危害着人类的生产生活,因此,如何快速有效地进行滑坡灾害危险性分析与评价,进而为滑坡的预测、预报及风险管理服务是一个亟待解决的问题。以莆田市为例,通过将地学信息图谱应用到滑坡灾害危险性评价中,构建莆田市高程、岩性、坡度、坡向影响因子信息图谱,并在此基础上得出莆田市滑坡灾害危险性评价信息图谱,以一系列的图谱直观地反映了莆田市滑坡发生的机制及滑坡危险性空间分布情况,反演了莆田市滑坡发生的时空变化规律,为滑坡灾害预测提供了矢量化的图形信息。     

Regulation of soil enzyme activities in constructed wetlands under a short-term drying period

The activities of extracellular enzymes are important in understanding decomposition of soil organic matter in wetlands subjecting to drying. The activity of soil extracellular enzymes (β-glucosidase, N-acetylglucosaminidase, and phosphatase), and related physicochemical parameters were monitored in constructed freshwater wetlands during a one-month drying manipulation. Drying increased redox potential and decreased soil water content significantly (P<0.05). Higher content of soil organic matter (P<0.05) and higher concentrations of inorganic N (nitrate, P<0.01; and ammonia, P<0.001) were also observed significantly under drying condition. Soil hydrolase enzyme activities were stimulated significantly (β-glucosidase, P<0.05; N-acetylglucosaminidase, P<0.01; and phosphatase, P<0.001), and a two-phase pattern of enzyme activities was revealed under drying condition. The increase of soil enzyme activities under drying condition was significantly related to soil redox potential (P<0.001). Drying strongly affected soil enzyme activities only when soil water content remained above an optimal level for enzymatic catalysis (higher than 23% w/w), corresponding to redox potentials below 250–300 mV. Our results suggest that, under drying condition, potential enzyme activities may be regulated by redox potential, in respect to soil moisture, and consequently alter nutrient availability in wetlands.     

粉煤灰水热法合成沸石及其对氨氮吸附性能的研究

以粉煤灰为原料,采用NaOH碱熔融制得粉煤灰熟料,由水热法合成沸石产品。通过单因素试验和正交试验考察搅拌陈化时间、水热晶化时间、液固比对合成沸石的氨氮吸附容量的影响。试验结果表明:搅拌陈化时间为12 h、水热晶化时间为6 h、液固比为10时,合成的产品主要为P型沸石,其氨氮吸附容量达最大为6.15 mg/g,并以此为理论基础讨论其运用于水处理工艺中的可能。     

2,4-D levels in the South Saskatchewan River in 1973 as determined by GLC method.

2,4-D levels in the South Saskatchewan River near Saskatoon in 1973 at the height of the spraying season, and at harvestime, were determined by a method involving direct glc analysis, ankaline hydrolysis, followed by n-butylation of the liberated free acid after acidification of the alkaline solution, and confirmed by subsequent n-octylation. GC/MS also confirmed the presence of 2,4-D. 2,4-D was detected during the spraying season but not at harvest time or in river mud samples. The average level was ca. 2mug of acid equivalent to 2,4-D per liter of river water at the height of the spraying season.     

地理信息系统技术在土壤污染状况调查工作中的应用

地理信息系统（GIS）是处理资源、环境等多种信息的计算机数据管理系统。本文介绍了6IS技术在全国土壤污染状况调查工作中调查点位的布设、现场定位采样、调查数据存储等方面的应用,并探讨该技术在今后土壤污染防治工作中的应用。     

芦山地震单开间砌体结构房屋震害特征∗

4.20芦山地震灾区临街自建单开间砌体结构房屋震害特别严重,本文基于现场调查研究该类特殊房屋的建造习惯、震害特征与损伤机理,研究表明:单开间砌体房屋是芦山地震灾区等四川小城镇比较常见的临街建筑模式,其平面狭长,建造随意,结构体系不合理,构造措施不到位,抗震能力弱;芦山地震地震烈度8、9度灾区单开间砌体房屋底层纵墙剪切破坏,普遍出现严重的贯通整片墙体的斜裂缝或X形裂缝。底层前部房间横墙无纵向支撑,独立墙段过长,横墙压弯破坏出现贯通整片墙体的水平裂缝,并且墙体外鼓;结构刚度中心与质量中心严重偏离,房屋扭转震动加剧墙体裂缝开展,相邻建筑反复碰撞作用是上部楼层震害的主要原因;鞭梢效应加重突变楼层结构损伤,引起出屋面附属建筑严重破坏甚至倒塌,横墙端部剪切断裂乃至溃散。据此,提出了既有单开间砌体房屋加固工作的建议。     

基于熵权-云模型的城市群综合承灾度评价

为解决城市群综合承灾度评价过程中的模糊性与随机性问题,合理评估城市群的综合承灾度。从防灾、抗灾、救灾和恢复4个维度构建城市综合承灾度评价指标体系,提出基于云模型的城市群综合承灾度评价模型。以西北地区3个城市群为例,运用云模型对城市群的综合承灾度进行评价,通过熵权法进行赋权,最终确定算例城市群的综合承灾状况。结果表明:西北地区3个城市群承灾度等级均为Ⅱ级,承灾能力中等;该方法利用能综合反映多因素之间复杂关系的特征指标得出相应的评价等级,同时为地区内城市的承灾度大小判断提供参考,对提升城市群综合承灾度具有积极意义。