聚己内酯复合固体碳源的制备及其深度脱氮性能研究

以聚己内酯（PCL）为骨架结合不同低成本碳源制备得到PCL复合碳源,静态释放试验筛选出适用于污水深度脱氮的复合碳源,批式试验研究其脱氮性能.并通过比较碳源表面特征、反硝化功能基因丰度与微生物群落结构特征分析其脱氮机理.结果表明,PCL/玉米淀粉连续30 d释碳性能稳定,氮、磷释放量均低于1.0 mg·L^-1,对水质影响较小,可用于生活污水深度脱氮.批式脱氮试验结果显示,PCL/玉米淀粉反硝化系统脱氮效果好,反硝化功能基因nirS、nirK拷贝数高,能够有效富集反硝化菌.此外,PCL/玉米淀粉系统中群落丰富度与多样性更高,系统抗逆性更强.因此,PCL/玉米淀粉能够实现生活污水长效稳定深度脱氮.     

甲基叔丁基醚毒性研究综述

对国内外有关甲基叔丁基醚毒性的研究结果作了综述。目前的研究结果表明，不同的个体之间对ＭＴＢＥ及其代谢产物具有一定的遗传毒性和轻微的生殖毒性；可诱导肝细胞色素Ｐ－４５０活性的升高；多数试验显示，ＭＴＢＥ具有动物致癌效应；不同学者对于长期低浓度接触情况下，ＭＴＢＥ对人体健康可能会产生的影响存在争论。     

A comparative study of prenatal ultrasound findings and post-mortem examination in a tertiary referral centre

This retrospective study compares the findings of prenatal ultrasound, performed in a tertiary fetal medicine centre, with the results of post-mortem examination in pregnancies complicated by suspected fetal abnormality that results in fetal loss. The study was carried out over a year at a teaching hospital, Fetal Medicine Centre and Regional Centre for Perinatal Pathology. Results were directly compared and the level of agreement between the ultrasound and post-mortem findings described. These were classified as having complete agreement; major agreement or major disagreement. The group of cases with major agreement between findings was further divided into those with significant, or minor, additional findings at post-mortem examination. Over the 12-month period, 153 ultrasound cases were identified, of which 47 were also examined by autopsy and were thus suitable for comparison in this study (30.7%). Complete agreement between ultrasound and post-mortem findings was found in 22 cases (46.8%). In 24 cases (51.1%), major agreement between ultrasound and post-mortem findings was seen. Of these, 11 had minor additional findings at post-mortem examination and 13 were found to have significant additional findings at post-mortem (27.7%), adding to the eventual diagnosis. In 12.8% of cases, post-mortem examination provided a definitive diagnosis. Only in one case was there complete discordance in the findings of the ultrasound examination and the autopsy (2.1%). No major disagreement between ultrasound and post-mortem findings was seen in 98% of cases. This study confirms the accuracy of prenatal ultrasound diagnosis in specialist centres, whilst emphasising the continuing importance of post-mortem examination in cases of fetal malformation to refine and, in some cases, define the diagnosis. Copyright © 2004 John Wiley & Sons, Ltd.     

Formation potentials of typical DBPs and changes of genotoxicity for chlorinated tertiary effluent pretreated by ozone

The effects of ozonation on the formation potential of typical disinfection byproducts (DBPs) and the changes of genotoxicity during post chlorination of tertiary effluent from a sewage treatment plant were investigated. Ozonation enhanced the yields of all detected chlorine DBPs except CHCl3. At a chlorine dose of 5 mg/L, the three brominated THMs and five HAAs increased, while chloroform decreased with the increase of ozone dose from 0 to 10 mg/L (ozone dose in consumption base). At a chlorine dose of 10 mg/L, the two mixed bromochloro species THMs and two dominant HAAs (DCAA and TCAA) firstly increased and then decreased with the increase of ozone dose, with the turning point approximately occurring at an ozone dose of 5 mg/L. The genotoxicity detected using umu test, on the other hand, was removed from 7 μg 4-NQO/L to a negligible level by ozonation under an ozone dose of 5 mg/L. Chlorination could further remove the genotoxicity to some extent. It was found that SUVA (UV absorbance divided by DOC concentration) might be used as an indicative parameter for monitoring the removal of genotoxicity during the oxidation.     

“底辟(挤入)构造”

<正> 底辟构造是背斜或穹窿中活动的核部岩层冲破上覆地层所形成的一种构造。在同心褶皱作用过程中,随着褶皱的弯曲度越来越大,核部岩层占据的空间就越来越小。如果核部岩层是强塑性的,那么它们就会向上施加一种压力,冲破顶盖而挤出。底辟构造还可     

Formation potentials of typical disinfection byproducts and changes of genotoxicity for chlorinated tertiary effluent pretreated by ozone

The effects of ozonation on the formation potential of typical disinfection byproducts (DBPs) and the changes of genotoxicity during post chlorination of tertiary effluent from a sewage treatment plant were investigated. Ozonation enhanced the yields of all detected chlorine DBPs except CHCl3. At a chlorine dose of 5 mg/L, the three brominated THMs and five HAAs increased, while chloroform decreased with the increase of ozone dose from 0 to 10 mg/L (ozone dose in consumption base). At a chlorine dose of 10 ...     

Starch/polyvinyl alcohol blended materials used as solid carbon source for tertiary denitrification of secondary effluent

Starch/polyvinyl alcohol （PVA） blended materials for using as a solid carbon source （SCS） were prepared by blending PVA and gelatinized starch in an aqueous solution system, in which PVA served as framework material and starch as carbon source. The optimization of starch content and temperature effects were investigated. It was indicated that higher denitrification efficiency could be achieved with more starch in the materials. The average specific denitrification rates were 0.93, 0.66, 0.37 and 0.36 mg/（g·day） corresponding to starch content of 70%, 60%, 40% and 30% respectively at 37℃. The denitrification rates increased when operating temperature was raised from 23℃ to 30℃ and then 37℃. The mechanism of carbon release was analyzed incorporating the experimental results of abiotic release in deionized water. The organic carbon was mainly hydrolyzed by microbes, and the biological release efficiencies were at the range of 89.2% to 96.0%. A long-term experiment with a continuous flow reactor with SCS material containing 70% starch was conducted to gain some experience for practical application. When the influent nitrate concentration was in the range of 35.2 to 39.1 mg/L, hydraulic retention time of 4 hr, and operating temperature of 30℃, a nitrogen removal efficiency up to 94.6% and denitrification rate of 0.217 kg/（m3.day） was achieved. The starch-based materials developed in this study can be used as a solid carbon source for tertiary nitrogen removal from secondary effluent.     

Formation potentials of typical disinfection byproducts and changes of genotoxicity for chlorinated tertiary e uent pretreated by ozone

The effects of ozonation on the formation potential of typical disinfection byproducts (DBPs) and the changes of genotoxicity during post chlorination of tertiary effluent from a sewage treatment plant were investigated. Ozonation enhanced the yields of all detected chlorine DBPs except CHCl3. At a chlorine dose of 5 mg/L, the three brominated THMs and five HAAs increased, while chloroform decreased with the increase of ozone dose from 0 to 10 mg/L (ozone dose in consumption base). At a chlorine dose of 10 mg/L, the two mixed bromochloro species THMs and two dominant HAAs (DCAA and TCAA) firstly increased and then decreased with the increase of ozone dose, with the turning point approximately occurring at an ozone dose of 5 mg/L. The genotoxicity detected using umu test, on the other hand, was removed from 7 μg 4-NQO/L to a negligible level by ozonation under an ozone dose of 5 mg/L. Chlorination could further remove the genotoxicity to some extent. It was found that SUVA (UV absorbance divided by DOC concentration) might be used as an indicative parameter for monitoring the removal of genotoxicity during the oxidation.     

纳米级方解石结构参数的表征

从晶体化学、晶体结构的角度．根据方解石的晶胞参数、晶体内原子排列的特点等,提出了方解石最小颗粒的假设。通过对纳米级方解石颗粒晶胞数、原子数、表面晶胞数和表面原子数的计算,讨论了它们与纳米级方解石颗粒尺寸大小的相关规律．并结合纳米微粒的特性对其进行了简要分析。     

Maternally inherited architecture in tertiary leaf beetles: paleoichnology of cryptocephaline fecal cases in Dominican and Baltic amber

Complex ethological adaptations and intraspecific interactions leave few fossil traces. We document three Dominican (20 million years old [myo]) and Baltic (45 myo) amber fossils that exhibit firm evidence of highly integrated interactions between mothers and offspring in the diverse camptosomate lineage of beetles (Chrysomelidae, leaf beetles). As in contemporary species, these hard cases were initially constructed by mothers, then inherited and retained by offspring, which then elaborate this protective domicile with an unusual but economical building material, their feces. The three fossils are classified in the Subfamily Cryptocephalinae; two are classified in the tribe Chlamisini based on morphological evidence—the flattened head lacking a sharp keel and long legs with simple recurved untoothed claws. These diagnostic features are not clearly visible in the third specimen to permit more refined identification. These fossils provide more precise paleontological dating of tribal nodes within the cryptocephaline radiation of leaf beetles. These fossils are the first and earliest evidence of mother–offspring interaction, building behavior, and fecal recycling in Camptosomata beetles and of inheritance of architectural structures in beetles.