Study on the mechanism of action between dimethyl phthalate and herring sperm DNA at molecular level

Dimethyl phthalate (DMP), a typical phthalic acid ester, is widespread in the environment and causes extensive concern due to its adverse effects on human health. To understand the genotoxicity of DMP at molecular level, the toxic interaction of DMP with herring sperm (hs) deoxyribonucleic acid (DNA; hs-DNA) was investigated in vitro under simulated physiological conditions using multi-spectroscopic techniques and a molecular modeling method. The results of Ultraviolet-Visible absorption spectroscopy, fluorescence emission spectroscopy, and circular dichroism spectra indicated that DMP interacts with hs-DNA in a groove-binding mode that changes the double helical structure of DNA. The binding constant and the number of binding sites calculated from the fluorescence quenching data were 565.718 L mol^?1 and 0.7872, respectively. A molecular modeling study revealed that DMP tends to bind with DNA in the A-T-rich regions of minor groove and that hydrogen bonding and van der Waals forces play main roles in the interaction. This research can help to elucidate the mechanism of DMP toxicity in vivo.     

A review on optimization techniques for sizing of solar-wind hybrid energy systems

Solar and wind are inexhaustible, abundant, environmentally friendly and freely available renewable energy sources. Integration of these two sources has always been a complex optimization problem which requires efficient planning, designing and control strategies. Many researchers have designed cost effective and efficient hybrid solar-wind energy systems by using various available software tools and optimization algorithms. With the advancement in artificial intelligence methods, various new optimization techniques have been developed in the last few decades. This paper presents state of the art optimization methods applied to hybrid renewable based energy systems. A brief introduction of each technique is presented along with papers published in different reputed journals. This article also reviews different power management, control strategies and multi-objective optimization methods used for hybrid wind-solar systems. A case study is presented to demonstrate the efficacy of some of the algorithms.     

New insights into the characterization of the binding of tetracycline analogues with lysozyme: a biophysical study

Tetracycline (TC), chlortetracycline (CTC) and oxytetracycline (OTC) are the most common members of the widely used veterinary drug tetracyclines, the residue of which in the environment can enter human body, being potentially harmful. Lysozyme is a monomeric protein widely distributed in the nature including human beings, having many physiological and pharmaceutical functions. The aim of this study was to examine the interaction of lysozyme with the three tetracyclines (TC, CTC and OTC) through spectroscopic and molecular modeling methods. The experimental results revealed that all the three tetracyclines (TCs) can interact with lysozyme with one binding site to form TCs-lysozyme complex, mainly through electrostatic forces with the affinity order: CTC > TC > OTC. The binding of TCs can cause conformational and some microenvironmental changes of lysozyme. Furthermore, molecular docking was applied to define the specific binding sites, the results of which show that all the three TCs can bind into lysozyme cleft and interact with the key active-site residues Glu 35 or Asp 52, resulting in competitive inhibition of lysozyme activity. The accurate and full basic data in the work is beneficial to clarifying the binding mechanism of TCs with lysozyme in vivo.     

Dissolved heavy metal concentrations of the Kralkızı, Dicle and Batman dam reservoirs in the Tigris River basin,Turkey

Water samples were collected at monthly intervals during 1 year of monitoring from Kralk?z?, Dicle and Batman dam reservoirs in the Tigris River basin to assess the concentrations of dissolved heavy metals and to determine their spatial and seasonal variations. The results indicated that dissolved heavy metal concentrations in the reservoirs were very low, reflecting the natural background levels. The lowest total metal concentrations in the three dam reservoirs were detected at sampling sites close to the dam wall. However, the highest total concentrations were observed at sites, which are located at the entrance of the streams to the reservoirs. Fe, Cr and Ni were the most abundant elements in the reservoirs, whereas Cd and As were the less abundant. The mean concentrations of dissolved metals in the dam reservoirs never exceeded the maximum permitted concentrations established by EC (European Community), WHO and USEPA drinking water quality guidelines. All heavy metals showed significant seasonal variations. As, Cd, Cr, Cu, Fe, Ni and Pb displayed higher values in the dry season, while higher values for Zn in the wet season. Cluster analysis grouped all ten sampling sites into three clusters. Clusters 1 and 2, and cluster 3 corresponded to relatively low polluted and moderate polluted regions, respectively. PCA/FA demonstrated the dissolved metals in the dam reservoirs controlled by natural sources.     

植物生态浮床的制备及其对富营养化水体的净化效果

针对福州市闽侯县旗山大学城景观湖某富营养化实验水区,制备了一种应用型植物生态浮床。原位修复结果表明,负载美人蕉(Canna coccinea Mill)的生态浮床对浮床周围的小生境有一定的修复效果;对美人蕉根际圈的微生物数量跟踪显示,在60 d内,微生物数量增加了2个数量级,微生物种类无明显变化,但不同植株根际圈的微生物种类存在一定差异。     

Biosorption and Biovolatilization of Arsenic by Heat-Resistant Fungi (5 pp)

Goal, Scope and Background

The aim of this work is to show the ability of several fungal species, isolated from arsenic polluted soils, to biosorb and volatilize arsenic from a liquid medium under laboratory conditions. Mechanisms of biosorption and biovolatilization play an important role in the biogeochemical cycle of arsenic in the environment. The quantification of production of volatile arsenicals is discussed in this article.

Methods

Heat-resistant filamentous fungi Neosartorya fischeri, Talaromyces wortmannii, T. flavus, Eupenicillium cinnamopurpureum, originally isolated from sediments highly contaminated with arsenic (more than 1403 mg.l-1 of arsenic), and the non-heat-resistant fungus Aspergillus niger were cultivated in 40 mL liquid Sabouraud medium (SAB) enriched by 0.05, 0.25, 1.0 or 2.5 mg of inorganic arsenic (H3AsO4). After 30-day and 90-day cultivation under laboratory conditions, the total arsenic content was determined in mycelium and SAB medium using the HG AAS analytical method. Production of volatile arsenic derivates by the Neosartorya fischeri strain was also determined directly by hourly sorption using the sorbent Anasorb CSC (USA).

Results

Filamentous fungi volatilized 0.025–0.321 mg of arsenic from the cultivation system, on average, depending on arsenic concentrations and fungal species. The loss of arsenic was calculated indirectly by determining the sum of arsenic content in the mycelium and culture medium. The amount of arsenic captured on sorption material was 35.7 ng of arsenic (22nd day of cultivation) and 56.4 ng of arsenic (29th day of cultivation) after one hour's sorption. Biosorption of arsenic by two types of fungal biomass was also discussed, and the biosorption capacity for arsenic of pelletized and compact biomass of Neosartorya fischeri was on average 0.388 mg and 0.783 mg of arsenic, respectively.

Discussion

The biosorption and amount of volatilized arsenic for each fungal species was evaluated and the effect of initial pH on the biovolatilization of arsenic was discussed.

Conclusions

The most effective biovolatilization of arsenic was observed in the heat-resistant Neosartorya fischeri strain, while biotransformation of arsenic into volatile derivates was approximately two times lower for the non-heat-resistant Aspergillus niger strain. Biovolatilization of arsenic by Talaromyces wortmannii, T. flavus, Eupenicillium cinnamopurpureum was negligible. Results from biosorption experiments indicate that nearly all of an uptaken arsenic by Neosartorya fischeri was transformed into volatile derivates.

Recommendations and Perspective

. Biovolatilization and biosorption have a great potential for bioremediation of contaminated localities. However, results showed that not all fungal species are effective in the removal of arsenic. Thus, more work in this research area is needed.

     

水体重金属污染治理技术研究进展

随着工业的发展和人口的不断增加,重金属废水排放量增加。有毒重金属对环境的严重威胁正逐渐成为全球性问题,不仅对环境造成危害,还威胁着人类的健康。介绍了水体重金属污染现状及危害,综述了目前国内外治理水体重金属污染主要技术的研究进展,指出了微生物治理重金属污染水体的良好应用前景。     

环境中多氯联苯（PCBs）的分析方法研究

探讨了环境中多氯联苯（PCBs）来源特性和分析检测方法。讨论了目前较为常用的样品前处理方法,如溶剂萃取法、固相萃取法、固相微萃取法等,常见的检测方法包括化学分析法和生物分析法,并对PCBs分析检测的发展前景进行了展望。     

削减和控制二恶英管理政策与技术应用的国际对比分析

削减和控制二恶英是履行<关于持久性有机污染物的斯德哥尔摩公约>的一项重要内容.我国是全球二恶英排放较大的国家之一,为了控制该类物质的排放,国家履约行动中将有80%用于减排二恶英.由于国外发达国家在20世纪80年代已经开始关注二恶英的污染,本世纪二恶英排放已经显著的降低.本文分析了发达国家在二恶英治理方面的政策措施,并与我国当前现有措施进行了比较,提出了我国政策制度的不足.其次总结了控制二恶英的主要技术,包括利用最佳可行技术进行削减和控制.分析发达国家利用最佳可行技术的情况及我国技术发展的状况,揭示了双方存在的技术差距.提出了由于上述管理和技术差异而导致发达国家和我国削减和控锚二恶英的不同工作侧重点.最后综合指出我国控制二恶英的管理和技术对策及整体框架体系.     

Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.