Brominated dibenzo-p-dioxins: a new class of marine toxins?

Levels of polybrominated dibenzo-p-dioxins (PBDDs) were measured in marine fish, mussels, and shellfish. PBDDs were nondetectable in samples from freshwater environments, and their levels were successively higher in samples from the marine environments of the Bothnian Bay and Bothnian Sea, the West Coast of Sweden, and the Baltic Proper. In Baltic Proper littoral fish the levels of PBDDs generally exceeded those of their chlorinated analogues (PCDDs). This is alarming as some Baltic fish species already are contaminated by chlorinated dioxins to such an extent that they cannot be sold on the European market. By comparing spatial trends in PBDD and PCDD distributions, and PBDD patterns in fish, mussels, and algae, we show that the PBDDs are probably produced naturally, and we propose a route for their biosynthesis. We further show that the levels of PBDDs are high (ng/g wet weight) in mussels, and that the levels increase over time. Finally, we discuss the possibility that the PBDDs have adverse biological effects, and that the levels are increasing as a result of global warming and eutrophication.     

The Location of Phenolic Antioxidants and Radicals at Interfaces Determines Their Activity

To characterize parameters influencing the antioxidant activity at interfaces a novel ESR approach was developed, which facilitates the investigation of the reaction stoichiometry of antioxidants towards stable radicals. To relate the activity of antioxidants towards the location of radicals at interfaces NMR experiments were conducted. Micellar solutions of SDS, Brij and CTAB were used to model interfaces of different chemical nature. The hydrophilic Fremy’s radical was found to be solubilized exclusively in the aqueous phase of SDS micellar solution but partitioned partly into the hydrophilic headgroup area of Brij micelles. In contrast the hydrophobic galvinoxyl was exclusively located in the micellar phase with the increasing depth of intercalation in the order SDS < Brij < CTAB. Gallates revealed a higher stoichiometric factor towards galvinoxyl in CTAB systems, which is accounted to a concentration effect of antioxidant and radical being both solubilized in the palisade layer. In contrast, in SDS solutions hardly any reaction between galvinoxyl and gallates was found. SDS acted as a physical barrier between radical (palisade layer) and antioxidant (stern layer). The influence of the hydrophobic properties of the antioxidant was clearly seen in Brij micelles. Elongation of the alkyl chain in gallate molecule resulted in increasing stoichiometric factors in the presence of galvinoxyl being located in the deeper region of the bulky headgroup area. The reverse trend was found in the presence of Fremy’s radical being located in the hydrated area of the micelles.     

Investigation of the potential release of polychlorinated dioxins and furans from PCP-treated utility poles

The United States (US) Environmental Protection Agency (EPA) estimated that the use of technical grade pentachlorophenol (PCP) between 1970 and 1995 to treat wood was approximately 400,000 metric tons in the US, and that between 4800 and 36,000 g of 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalents (TEQs) were incorporated annually in treated wood. The EPA has been unable, however, to estimate the rate of release of polychlorinated dibenzo-p-dioxins and dibenzofurans (CDD/Fs) from treated utility poles into the environment. There is some evidence that CDD/Fs leach from treated poles into the surrounding soils, but these studies do not allow for the calculation of a rate of release from this mechanism. Another possible release mechanism is the volatilization of dioxins into the atmosphere, but there are no data to demonstrate, much less quantify, this release. While not directly measuring the release of dioxins from treated utility poles into the environment, this study was designed to examine the potential for such release. The general approach taken was to collect PCP-treated poles of varying ages, to remove and analyze multiple samples from each pole cross-section, and to compare the spatial distribution of CDD/F congeners among poles of different ages. Evidence of concentration-depth profile changes over time may provide insight into the potential for dioxins to migrate through and then out of PCP-treated utility poles. It was found that the CDD/F concentrations were consistently higher in the outer portions of the poles than the center. This trend tends to be most marked in older poles and for the lower chlorinated congeners. The trend for dioxins to concentrate in the outer portions of the pole over time suggest migration within the poles, and this migration may result in some environmental release. Other possible explanations were also offered.     

Scanning tunnelling spectroscopy on arrays of CdSe quantum dots: response of wave functions to local electric fields

We use scanning tunnelling microscopy (STM) to controllably contact individual CdSe quantum dots (QDs) in a multilayer array to study electrical contacts to a model QD solid. The probability of electron injection into the QD array depends strongly on the symmetry of the QD wave functions and their response to the local electric field. Quantitative spectroscopy of the QD energy levels is possible if the potential distribution in the STM tip-QD array-substrate system is taken into account.     

Influence of liquid binder dispersion on agglomeration in an intensive mixer

In industrial scale mixer granulation, liquid binder is usually sprayed onto the agitated powder bed by means of a nozzle in order to enhance the agglomeration process. The early stage of this process, where granule nuclei are formed and grow, is not well understood. As it is desirable to model the agglomeration state right from the beginning of the process for the purposes of control and modeling, this nucleation step is therefore an important field of interest.To investigate the influence of binder droplet size on the nucleation stage of the agglomeration process, experiments were carried out with lactose and water in an intensive mixer. Water was sprayed in to the mixer with different nozzles to vary the size of the produced droplets. As a comparison, water was also directly poured into the turning mixer. Samples of the produced granules were taken at specific time intervals and analysed for size and water content. As the experiments were focused on examining short granulation times, the first samples were taken after only half of the water was added.Particle size distribution and liquid distribution in the wet granule samples were analyzed. It was found, that the droplet size of the binder liquid has great influence on agglomerate size and binder distribution at short mixing times, with increasing time, the mechanical stresses acting in the mixer becomes more and more dominating in the process. Preliminary comparisons are also carried out with single drop penetration tests in an attempt to correlate drop size to penetration time and also to produced granule size.In conclusion this paper studies the effect of different drop size conditions and subsequent spray flux on the behaviour of the nucleation and the early stages of the agglomeration process. The context of these findings for agglomeration in an intensive mixer is examined.     

Project managers and career models: An exploratory comparative study

Prior research has paid little attention to the careers and career models of project managers. This is troublesome for at least two reasons. First, project managers are becoming an increasingly important category of managers and today they constitute a major part of many organizations' leadership capability. Second, traditional literature on careers generally does not address project-based careers as a specific case in point, although this kind of career is unique in the sense that it is based on temporary assignments and lack of formal positions. The research presented in this paper identifies and explains patterns of similarities and differences among applied career models in ten large, mature project-intensive firms in Sweden. The paper identifies a number of factors that seem to be critical for the design of career models for project managers, including the number of levels, the complexity of assignments, and the degree of formal requirements. The paper also outlines two archetypes of career models applied by the firms under study: the competence strategy model and the talent management model.     

Improving Open Spaces for a Sustainable City

The feasibility of city living with nature as a way to restore the balance between human uses and natural processes is the focus of this paper about the city of Maringa in Southern Brazil. This urban form, a planned new town founded in 1947 upon a previous, comprehensive British land-development scheme, originally offered a friendly interaction between urban settlement and nature. Hence, this paper outlines how open spaces can be enhanced as an ecological structure, bringing parks, squares, gardens and urban farming into a productive system, both for nature＇s and for people＇s sakes. Following a morphological study, the proposed ecological structure will maintain ecological processes within the urban grid and help to preserve historical and social values, by linking a wide variety of natural and restored ecosystems and landscape features. The adoption of this kind of ecological planning will certainly result in an increase of the urban landscape quality, changing actual planning paradigm and preventing the city from environmental quality decrease.     

Identification of barramundi (Lates calcarifer) and tilapia (Oreochromis spp.) fillets by DNA- and protein-analytical methods

Fish and fillet of barramundi (Lates calcarifer) and tilapia (Oreochromis species) obtained from wholesale and retail trade were assigned to species by sequencing of PCR products. Two segments (358 and 464 bp) of the cytochrome b gene (cytb) were amplified using universal primers. The amplicons gave characteristic patterns in SSCP-analysis (single strand conformation polymorphism) suitable for differentiation of Lates calcarifer from Lates niloticus and Lateolabrax japonicus. Intra-specific variation of sequences and SSCP patterns were observed for barramundi. In case of tilapia species, it was found to be difficult to identify samples by BLAST due to the high similarity of cytb sequences of O. niloticus, O. mossambicus, O. aureus and Sarotherodon galileus. Four different patterns of single strand DNA (ssDNA) were obtained by SSCP analysis of the 464 bp amplicon of tilapia. Different patterns of ssDNA matched to variations in sequences. Protein profiles obtained by IEF (isoelectric focusing) of water-soluble proteins from raw fillet were found to be suitable for rapid differentiation of Lates calcarifer from Lateolabrax japonicus, but the three different Oreochromis species expressed only minor differences in protein patterns. The patterns of the tilapia and barramundi species showed a number of acidic, heat-stable proteins, presumably representing parvalbumin.     

碳化铬/Ni3Al复合堆焊层组织及摩擦磨损分析

采用光学显微镜、扫描电镜、电子探针及X射线衍射分析钨极氩弧堆焊碳化铬增强Ni3Al基复合堆焊层的组织结构,并采用销盘式干摩擦磨损试验机对堆焊层与活塞环用蠕墨铸铁材料的干摩擦磨损性能进行试验比较.结果表明,复合堆焊层内形成Ni3Al金属间化合物基体,其中弥散分布有大量细小的块状和条状碳化物硬质相Cr3C2和Cr7C3;焊接时焊丝中Cr3C2颗粒溶解析出,重新析出的碳化铬颗粒中包含Fe和Ni元素,碳化铬颗粒与Ni3Al基体形成良好的冶金结合;弥散分布的碳化铬颗粒和Ni3Al基体固溶强化的Cr元素决定了堆焊层具有较高的硬度.室温条件下,复合堆焊层具有优异的耐干摩擦磨损性能,其摩擦系数为0.23,远低于活塞环蠕墨铸铁的0.39;磨损率仅为蠕墨铸铁材料的43%.     

Environmental toxicology and risk assessment of pharmaceuticals from hospital wastewater

In this paper, we evaluated the ecotoxicological potential of the 100 pharmaceuticals expected to occur in highest quantities in the wastewater of a general hospital and a psychiatric center in Switzerland. We related the toxicity data to predicted concentrations in different wastewater streams to assess the overall risk potential for different scenarios, including conventional biological pretreatment in the hospital and urine source separation. The concentrations in wastewater were estimated with pharmaceutical usage information provided by the hospitals and literature data on human excretion into feces and urine. Environmental concentrations in the effluents of the exposure scenarios were predicted by estimating dilution in sewers and with literature data on elimination during wastewater treatment. Effect assessment was performed using quantitative structure-activity relationships because experimental ecotoxicity data were only available for less than 20% of the 100 pharmaceuticals with expected highest loads. As many pharmaceuticals are acids or bases, a correction for the speciation was implemented in the toxicity prediction model.The lists of Top-100 pharmaceuticals were distinctly different between the two hospital types with only 37 pharmaceuticals overlapping in both datasets. 31 Pharmaceuticals in the general hospital and 42 pharmaceuticals in the psychiatric center had a risk quotient above 0.01 and thus contributed to the mixture risk quotient. However, together they constituted only 14% (hospital) and 30% (psychiatry) of the load of pharmaceuticals. Hence, medical consumption data alone are insufficient predictors of environmental risk. The risk quotients were dominated by amiodarone, ritonavir, clotrimazole, and diclofenac. Only diclofenac is well researched in ecotoxicology, while amiodarone, ritonavir, and clotrimazole have no or very limited experimental fate or toxicity data available. The presented computational analysis thus helps setting priorities for further testing.Separate treatment of hospital wastewater would reduce the pharmaceutical load of wastewater treatment plants, and the risk from the newly identified priority pharmaceuticals. However, because high-risk pharmaceuticals are excreted mainly with feces, urine source separation is not a viable option for reducing the risk potential from hospital wastewater, while a sorption step could be beneficial.