Toxic trace elements in Chilean seafoods: development of analytical quality control procedures.

Chile is a well known producer and exporter of shell fish. These seafoods, like other specimens of marine origin, are susceptible to environmental and other contamination by trace elements, including toxicants. Therefore, adequate analytical quality assurance is mandatory before accepting analytical results. In this context, the use of at least two independent methods of determination and validation with certified reference materials (CRM) provides acceptable criteria for judging the reliability of the data. This paper describes sample treatments and analytical procedures for Cd, Cu and Hg determinations in mollusc samples. Three independent analytical techniques, namely differential pulse anodic stripping voltammetry, neutron activation analysis and atomic absorption spectrometry, were used. CRM standards of the IAEA, NIST and BCR were analyzed to evaluate quality assurance. Following the quality control phase, the concentrations of cadmium, copper and mercury in fresh and canned mollusc samples Tagelus dombeii and Semelle solida (Navajuelas and Almejas chilenas respectively) from different locations were determined.     

认知“绿色”消费者

##正## 虽然消费者信奉关爱环境的概念,但"可持续性"这一术语的含义依然模糊不清,并且它的范围超出了关注员工安全的生态系统。尽管消费者需要可持续性食品,但他们对其含义却不甚了解。这种不确定性为研发一种以科学为基础的可持续食品的生产方法提供了一个机会。     

Processing and Mechanical Properties of Pressureless-Sintered Niobium-Alumina-Matrix Composites

Niobium-alumina (Nb-Al2O3) composites have been fabricated via the pressureless sintering of compacts of intensively milled Nb-Al2O3 mixtures. Strength and fracture toughness of the composites increase as the niobium content increases. For a composite that contains 50 vol% niobium, strengths of up to 680 MPa, with a corresponding fracture toughness of 6.3 ± 0.3 MPam1/2 and hardness of 6.4 GPa, have been obtained.     

Variational optic flow on the Sony PlayStation 3

While modern variational methods for optic flow computation offer dense flow fields and highly accurate results, their computational complexity has prevented their use in many real-time applications. With cheap modern parallel hardware such as the Cell Processor of the Sony PlayStation 3, new possibilities arise. For a linear and a nonlinear variant of the popular combined local-global method, we present specific algorithms on this architecture that are tailored towards real-time performance. They are based on bidirectional full multigrid methods with a full approximation scheme in the nonlinear setting. Their parallel design on the Cell hardware uses a temporal instead of a spatial decomposition, and processes operations in a vector-based manner. Memory latencies are reduced by a locality-preserving cache management and optimised access patterns. For images of size 316 × 252 pixels, we obtain dense flow fields for up to 210 frames per second.     

The air-sea equilibrium and time trend of hexachlorocyclohexanes in the Atlantic Ocean between the Arctic and Antarctica

Hexachlorocyclohexanes (HCHs) were determined simultaneously in air and seawater during two cruises across the Atlantic Ocean between the Arctic Ocean (Ny-Alesund/ Svalbard, 79 degrees N; 12 degrees E) and the Antarctic Continent (Neumayer Station/ Ekstroem Ice Shelf, 70 degrees S; 8.2 degrees W) in 1999/ 2000. The concentrations of alpha-HCH and gamma-HCH in air and surface waters of the Arctic exceeded those in Antarctica by 1-2 orders of magnitude. The gaseous concentrations of gamma-HCH were highest above the North Sea and between 20 degrees N and 30 degrees S. Fugacity fractions were used to estimate the direction of the air-sea gas exchange. These showed for alpha-HCH thatthe measured concentrations in both phases were close to equilibrium in the North Atlantic (78 degrees N-40 degrees N), slightly undersaturated between 30 degrees N and 10 degrees S and again close to equilibrium between 20 degrees S and 50 degrees S. Y-HCH has reached phase equilibrium in the North Atlantic as alpha-HCH, but the surface waters of the tropical and southern Atlantic were strongly undersaturated with y-HCH, especially between 30 degrees N and 20 degrees S. These findings are significantly different from two earlier estimates around 1990 as a result of global emission changes within the past decade. Therefore, we investigated the time trend of the HCHs in the surface waters of the Atlantic between 50 degrees N and 60 degrees S on the basis of archived samples taken in 1987-1997 and those from 1999. A decrease of alpha-HCH by a factor of approximately 4 is observed at all sampling locations. No decrease of gamma-HCH occurred between 30 degrees N and 30 degrees S, but there was a decrease in the North Atlantic, North Sea, and in the South Atlantic south of 40 degrees S. The constant level of gamma-HCH in the tropical Atlantic confirms the conclusion that the tropical Atlantic acts as a sink for y-HCH at present time. The measured alpha-HCH seawater concentrations were compared with results from a global multimedia fate and transport model. Whereas the time trend over 13 years and the latitudinal gradient were well reproduced by the model, the absolute levels were too high by a factor of 4.5. This may be explained by the zonal averaging employed in the model as well as uncertain emissions and degradation rates.     

Image Compression with Anisotropic Diffusion

Compression is an important field of digital image processing where well-engineered methods with high performance exist. Partial differential equations (PDEs), however, have not much been explored in this context so far. In our paper we introduce a novel framework for image compression that makes use of the interpolation qualities of edge-enhancing diffusion. Although this anisotropic diffusion equation with a diffusion tensor was originally proposed for image denoising, we show that it outperforms many other PDEs when sparse scattered data must be interpolated. To exploit this property for image compression, we consider an adaptive triangulation method for removing less significant pixels from the image. The remaining points serve as scattered interpolation data for the diffusion process. They can be coded in a compact way that reflects the B-tree structure of the triangulation. We supplement the coding step with a number of amendments such as error threshold adaptation, diffusion-based point selection, and specific quantisation strategies. Our experiments illustrate the usefulness of each of these modifications. They demonstrate that for high compression rates, our PDE-based approach does not only give far better results than the widely-used JPEG standard, but can even come close to the quality of the highly optimised JPEG2000 codec.     

Investigation of the structure of neodymium-di-(2-ethylhexyl) phosphoric acid combinations using electrospray ionization and matrix-assisted laser desorption ionization mass spectrometry and nuclear magnetic resonance spectroscopy

Neodymium-di-(2-ethylhexyl) phosphoric acid (DEHPA) species forming in the organic phase during solvent extraction of neodymium with solutions of DEHPA have been studied. Two samples were prepared: one with a low molar ratio of neodymium to DEHPA, which is liquid and clear, and the other with a high molar ratio of neodymium to DEHPA (complete loading), which has the consistency of a gel. Electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI) mass spectrometric investigations show numerous compounds, in addition to the generally assumed species dimeric DEHPA and Nd(DEHP-DEHPA)₃, in the liquid sample. The nuclear magnetic resonance (NMR) spectroscopic investigation of pure DEHPA and of completely loaded sample confirm the formula of pure DEHPA and of the organic part of Nd(DEHP)₃. Furthermore, chemical analysis of a dried, completely loaded sample also proves the existence of the species Nd(DEHP)₃. Results of X-ray powder diffraction measurements of this sample agree well with literature data.     

Reaction Processing of Al2O3 Composites Containing Iron and Iron Aluminides

Different Fe-Al₂O₃ and FeAl-Al₂O₃ composites with metallic contents up to 30 vol% have been fabricated via reaction processing of Al₂O₃, Fe, and Al mixtures. Low Al contents (<∼10 vol%) within the starting mixture lead to composites consisting of Fe embedded in an Al₂O₃ matrix, whereas aluminide-containing Al₂O₃ composites result from powder mixtures with higher Al contents. In both cases, densification up to 98% TD can be achieved by pressureless sintering in inert atmosphere at moderate temperatures (1450°-1500°C). The proposed reaction sintering mechanism includes the reduction of native oxide layers on the surface of the Fe particles by Al and, in the case of mixtures with high Al contents, aluminide formation followed by sintering of the composites. Density and bending strengths of the reaction-sintered composites depend strongly on the Al content of the starting mixture. In the case of samples containing elemental Fe, crack path observations indicate the potential for an increase of fracture toughness, even at room temperature, by crack bridging of the ductile Fe inclusions.     

Measuring deeper meaning responses: A discrimination scale for play therapists in training.

The authors developed a terminology bridge for reflecting deeper meaning in play therapy by melding Carkhuff’s scale for measuring accurate empathy with the child-centered, Adlerian, and ecosystemic play therapy approaches. Designed to help university practicum and other supervisors facilitate beginning play therapists in the reflection of deeper meaning, this scale draws from historic core conditions in psychotherapy and correlates them to response skills of respected play therapy approaches in a 5-level scale. (PsycINFO Database Record (c) 2010 APA, all rights reserved)