Genetic and DNA-methylation changes induced by potassium dichromate in Brassica napus L

This study evaluated genetic and DNA methylation alteration induced by potassium dichromate in Brassica napus L. plants. Amplified fragment length polymorphism (AFLP) and selective amplification of polymorphic loci (SAMPL) tests revealed dose-related increases in sequence alterations in plantlets exposed to 10-200 mg/l potassium dichromate. Individual plantlets exposed to chromium under similar conditions showed different AFLP and SAMPL DNA profiles. These observations suggest random DNA mutation in response to potassium dichromate and argue against preferential sites for mutation. DNA methylation changes in response to chromium treatment were also evaluated. Two complementary approaches were applied: (i) immunolabelling, using a monoclonal antibody against 5-methylcytosine; and (ii) methylation-sensitive amplified polymorphism (MSAP). Immunolabelling showed cytosine-hypermethylation in the Brassica napus L. genome when plants were treated with potassium dichromate. MSAP analysis showed extensive methylation changes in CCGG-sequences, with the net result being genome-wide hypermethylation. These results showed a clear DNA alteration in plants as a response to chromium exposure and the effect was dose-dependent. DNA polymorphism detected by different markers supports the effectiveness of the use of these tools for the investigation of environmental toxicology and for evaluating the concentration of pollutants by DNA analysis in plants.     

Enhancement of photocatalytic activity of sprayed nitrogen-containing ZnO powders by coupling with metal oxides during the acetaldehyde decomposition

Colored N-containing MOx-ZnO (M = W, V) composite powders with high surface area were synthesized by spray pyrolysis. The nitrogen content was controlled from 600 to 3000 ppm by changing the powder ingredients and the spray pyrolysis temperature. Ultraviolet-visible spectra indicated that the N-containing MOx-ZnO powders absorbed not only ultraviolet light like pure ZnO powder, but also some visible-light. Acetaldehyde decomposition was used as a probe reaction to evaluate the photocatalysis of these MOx-ZnO powders. The photocatalytic activity of the N-containing ZnO powder was pronouncedly enhanced by the WO3 or V2O5 addition under both UV and visible-light irradiation. This enhancement was ascribed to the MOx acting as a sink for photogenerated electrons in the UV case, and to a synergistic effect of N-doping and MOx-ZnO coupling in the case of visible-light.     

重庆市春季大气NO2浓度空间分布特征研究

为了解重庆市大气中NO2浓度空间分布特征，研究了一种被动式采样器在该地区野外采集大气NO2的可行性，并在2004年3～5月期间利用这种采样器对重庆城区2600Km^2范围大气中的NO2进行了连续观测。结果表明：NO2浓度值随城区类型、观测点位置不同有一定的差异，其分布与交通强度密切相关；前后两次观测有相同(除南岸区外)的区间浓度梯度。     

Risk curve boundaries

Insights into the science and the dynamics associated with the stimulus-injury relationship of the human system are often gained by focusing on the results obtained from human surrogate testing. These results are commonly mapped into an injury risk paradigm for the purpose of characterizing the stimulus injury response: the injury risk curve. However, the quality and quantity of the data along with the experimental design are critical factors when considering the value of the estimated risk curve. Presented in this article is an analysis of injury risk curves in terms of their usability and appropriateness with respect to the sample size, stimulus distribution over the critical range, censoring, shape of the underlying risk function, and the inclusion of "actual" (uncensored) along with censored data. The results from this analysis indicate that for "large" biomechanical injury data sets there is no advantage to using actual data; censored data will yield the same injury risk curve as actual data. However, for "small" biomechanical injury data sets the inclusion of actual data will significantly improve the quality of the resulting risk curve. In addition, the results show that the amount of injury data needed to generate a risk curve with a given confidence bound is not only dependent on the relative contribution of the censored data and actual data but also on the shape of the risk function along with the stimulus distribution over the critical range. Confidence intervals are presented for the thoracic injury risk and the head injury risk to show the influence of data distribution on the goodness of the risk function estimation.     

浅淡高校艺术设计专业的基础教学

现代艺术设计教学跟上时代,应理清授课思路,鼓励学生的创造,启发学生的想象力,开发学生的潜在智慧,培养学生有机的运动的思维方式,以发扬个性,来寻求自己的艺术语言和发展道路。     

油库火灾危害分析

运用“池火灾伤害模型”,对某油库汽油罐火灾危害程度进行分析,得出火灾危害程度与事故原点距离之间的关系,为油库安全运营提供参考。     

EDTA-2Na盐除垢与清洗液循环利用的实验研究

利用锅炉行业以及石油化工行业除垢的经验,结合稀土行业的实际情况,提出了稀土湿法冶金行业蒸发器结垢的技术处理,选用EDTA-2Na(乙二胺四乙酸二钠)除垢剂。实验表明,使用EDTA-2Na盐除垢的最优反应条件为质量浓度不小于50 g/L、反应温度控制在70℃、反应时间控制在4 h、pH值控制在13~14(碱度在0.1~0.5 mol/L)之间,反应量控制在1 L除垢液处理10 g结垢物;若使用盐酸配合EDTA-2Na盐除垢,建议先使用盐酸(浓度为5 mol/L)再使用EDTA-2Na溶液;清洗废液再生的最优条件应为pH值调至3.5,再补加一定量(20%)的EDTA-2Na除垢剂,可以达到清洗液的要求并实现循环利用,效果显著。     

Feeding and reproductive behaviour in fallow bucks (<Emphasis Type="Italic">Dama dama</Emphasis>)

Observations on individually marked fallow deer (Dama dama) in central Italy were performed over 2 years in order to analyse time budgets of four age and sex classes. The aim was to test whether feeding activity was influenced by mating activity, forage quality or physiological constraints during the rut. Only adult males (bucks) completely ceased feeding during the rutting season, well before the actual start of mating behaviour and concurrently with the phenomenon of scent-urination, and spending most of their daily time completely inactive. All other age and sex classes were unaffected in their feeding behaviour by the rutting season. Indeed, females and young males showed a marked increase in grazing in response to an improvement in forage quality from summer to autumn. These results seem to confirm the hypothesis that hypophagia, displayed only by bucks, may be of no adaptive value in itself. On the other hand, it may be a by-product of other physiological processes occurring during the rut, inducing scent-urination, which plays an important role in intraspecific recognition and sexual attraction.     

挥发性有机物光催化降解研究进展

阐述了挥发性有机物（ＶＯＣｓ）光催化降解的基本原理，分析了气相条件下不同ＶＯＣｓ的降解途径以及Ｏ２和Ｈ２Ｏ在光催化反应中的作用、光催化反应过程的传质和动力学规律，提出了反应器设计需要遵循的基本原则，叙述了ＶＯＣｓ光催化降解的催化剂及其换活现象、已研究的ＶＯＣｓ的光催化降解效率、部分物质难光催化降解的原因，讨论了ＶＯＣｓ光催化降解进一步研究的方向和应用前景。