Identification of the flame retardant decabromodiphenyl ethane in the environment

The brominated flame retardant decabromodiphenyl ethane, DeBDethane, is marketed as an alternative to decabromodiphenyl ether, BDE209. There are currently no data available about the presence of DeBDethane in the environment. In this study, DeBDethane was positively identified by high-resolution mass spectrometry and quantified by low-resolution mass spectrometry with electron capture negative ionization in sewage sludge, sediment, and indoor air. It was found in 25 of the 50 Swedish sewage treatment plants investigated, with estimated levels up to about 100 ng/g dry weight. The concentration of DeBDethane in sediment from Western Scheldt in The Netherlands was 24 ng/g dry weight, and in an air sample from a Swedish electronics dismantling facility it was 0.6 ng/m3. DeBDethane was also found together with nonabromodiphenyl ethanes in water piping insulation. All samples contained BDE209 in higher concentrations as compared to DeBDethane (DeBDethane/BDE209 ratios ranging from 0.02 to 0.7), probably reflecting the higher and longer usage of BDE209. There is an ongoing risk assessment within the European Union regarding BDE209. Since DeBDethane has similar applications, it is important to investigate its environmental behavior before using it to replace BDE209.     

Quantitative methods to reconstruct length and weight of Great Lakes prey fishes from dietary observations of partially digested prey

Dietary studies of fish inform many aspects of fisheries science and ecosystem management, providing critical information to signify fluctuations in ecosystem functions. Bony structures are persistent, remaining in the stomach longer than soft tissue. We evaluated the utility of bony structures (cleithra, standard length, full vertebral column, and partial vertebral column) for reconstituting length and weight of thirteen prey fish species commonly found in the diets of piscivores in the Great Lakes. Standard length and full vertebral measurements were the most accurate for estimation of total length. Cleithra provided the third most accurate length estimates with exceptions for deepwater and slimy sculpin where extraction was more difficult. Partial vertebral measurements resulted in less variable results for species with low total vertebrae counts. Sculpin, a species with lower numbers of total vertebrae, produced more reliable estimates from partial vertebral measures than rainbow smelt or bloater which have more vertebrae. The accuracy of partial vertebrae measurements is improved when larger numbers or a greater proportion of the vertebral column is measured. Access to more broadly available digital X-ray technologies allowed for more rapid processing by eliminating the need for tissue removal to measure vertebrae and facilitated estimation of numeric relationships for prey length reconstitution. Using the data and mathematical relationships provided herein, investigators can easily reconstitute many of the diet items observed in Laurentian Great Lakes piscivores and can tailor methodologies and structures utilized to minimize estimation error and maximize efficiencies in evaluating stomach contents.     

Influence of grain size on arrest of a dynamically propagating cleavage crack in ferritic steels—micromechanics

Cleavage fracture in ferritic steels is controlled by several critical steps. First a microcrack must nucleate, grow and overcome barriers, such as grain boundaries. The latter is examined here by use of a periodic, axisymmetric model representing two grains. A microcrack nucleated at the center in one grain is driven by a constant remotely applied stress towards the second grain. The cleavage planes of the grain in which the microcrack is nucleated coincide with the principal loading direction. In the adjacent grain, due to misalignment in possible cleavage planes, the propagation direction changes and separation occurs in mixed mode, involving both normal and shear separations. The temperature dependence of the mechanical properties of the material is accounted for by use of a temperature dependent elasto viscoplastic material model. The largest grain size that can arrest a rapidly propagating microcrack is defined as the critical grain size. The effects of stress state and temperature on the critical grain size are examined. The influence of mismatch in lattice orientation between two adjacent grains in terms of a tilt angle is both qualitatively and quantitatively described. It is shown that the critical grain size is influenced by plastic geometry change and prestraining, which depend on the applied stress state. The results also show that a microcrack can be arrested in an adjacent grain under specific conditions.     

基金会现场总线技术十年以来进步与发展——需求牵引,技术推动

在基金会现场总线（FF）技术开始推广应用的初期,生产厂商、工程公司、工厂技术人员付出了艰苦努力,通过学习和实践,以掌握总线技术、产品性能,积累工程经验。在经历上千个基金会总线项目的系统安装应用之后,技术人员已经能够快速而经济地实施现场总线的工程项目,     

Numerical analysis of nonlinear dynamic structural behaviour of ice-loaded side-shell structures

This investigation examines how the nonlinear structural response of a ship side-shell structure that impacts with ice is affected by the layout/design of the structure, ice characteristics and ship speed operational conditions. The finite element (FE) method was used for nonlinear analysis and comparison of a reference side-shell structure with a topology-optimized structure. Nonlinear dynamic FE collision simulations were carried out, using the reference side-shell structure, to study how the impact with ice (having different values of damping coefficients), and the variation in ship speed operational conditions, affected the damage caused to the side-shell. In addition, the results from the comparison of the topology-optimized and reference side-shell structures showed slightly larger stresses locally in the former structure. It was concluded that it was possible to reduce the weight of the reference side-shell structure and that the objective function and optimization require more detailed investigation. The FE analyses with various damping coefficients of ice showed that, for the chosen values of the damping coefficients, there was only small influence on the dynamic nonlinear response of the reference side-shell structure. Finally, a limit value for the maximum allowed velocity in the normal direction towards a level ice belt of the reference side-shell structure was calculated to result in an elastic structural response of the side-shell. For a side-shell structure movement in the direction along a level ice, the influence of velocity on structural response was negligible due to low friction between the side-shell structure and the ice in the contact.     

Refining the relationship between personality and subjective well-being.

Understanding subjective well-being (SWB) has historically been a core human endeavor and presently spans fields from management to mental health. Previous meta-analyses have indicated that personality traits are one of the best predictors. Still, these past results indicate only a moderate relationship, weaker than suggested by several lines of reasoning. This may be because of commensurability, where researchers have grouped together substantively disparate measures in their analyses. In this article, the authors review and address this problem directly, focusing on individual measures of personality (e.g., the Neuroticism-Extroversion-Openness Personality Inventory; P. T. Costa & R. R. McCrae, 1992) and categories of SWB (e.g., life satisfaction). In addition, the authors take a multivariate approach, assessing how much variance personality traits account for individually as well as together. Results indicate that different personality and SWB scales can be substantively different and that the relationship between the two is typically much larger (e.g., 4 times) than previous meta-analyses have indicated. Total SWB variance accounted for by personality can reach as high as 39% or 63% disattenuated. These results also speak to meta-analyses in general and the need to account for scale differences once a sufficient research base has been generated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rural electrification in an imperfect world: A case study from Mozambique

Electricity is universally recognized as a necessary, although not sufficient, requirement for social and economic development. However, increasing access to electricity in developing countries has proven to be difficult and expensive, particularly in rural areas. In this article, we analyze the dynamics of the relationship between electricity and socio-economic development by means of a cost–benefit analysis of a typical rural electrification project in Mozambique, assessing the impact of electricity on households, education, agro-business, commerce, and the public sector. We show that rural electrification can be commercially viable and cause structural transformation in rural areas within a short period of time. Finally, illustrated by the actual policy practice in Mozambique, we argue that low institutional quality is a key barrier to promote increased access to electricity for the poor.