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911.
Distribution and fate of HBCD and TBBPA brominated flame retardants in North Sea estuaries and aquatic food webs 总被引:21,自引:0,他引:21
Morris S Allchin CR Zegers BN Haftka JJ Boon JP Belpaire C Leonards PE Van Leeuwen SP De Boer J 《Environmental science & technology》2004,38(21):5497-5504
Tetrabromobisphenol A (TBBPA) and hexabromocyclododecane diastereoisomers (alpha-, beta/-, and gamma-HBCD) were investigated in effluents from sewage treatment works, landfill leachates, sediments, and food web organisms of the North Sea basin. Residues were quantified by liquid chromatography-mass spectrometry. Both flame retardants were enriched in sewage sludges, where a maximum total (sigma) HBCD concentration of 9.1 mg/kg (dry weight; d.w.) was found; TBBPA was at levels of 102 microg/kg. Landfill leachates from The Netherlands showed up to 36 mg (sigmaHBCD)/ kg (d.w.). gamma-HBCD dominated isomeric profiles in sediments, and concentrations were elevated near to a site of HBCD manufacture. alpha-HBCD was the primary congener detected in marine mammals; however, very few samples exhibited TBBPA. sigmaHBCD ranged from 2.1 to 6.8 mg/kg (lipid weight; l.w.) in liver and blubber of harbor porpoises (Phocoena phocoena) and seals (Phoca vitulina). TBBPA levels in cormorant (Phalacrocorax carbo) livers were up to 1 order of magnitude lower compared to sigmaHBCD. HBCD in eels (Anguilla anguilla) from the Scheldt basin (Belgium) reflected the spatial distribution of concentrations in local sediments. This study shows evidence of HBCD bioaccumulation at the trophic level and biomagnification in the ascending aquatic food chain, and these findings justify risk assessment studies at the ecosystem level. 相似文献
912.
Convergent beam electron diffraction is used to study the effect of the sample bending on diffracted intensities as observed in transmission electron microscopy (TEM). Studied samples are made of thin strained semiconductor Ga(1-)(x)In(x)As epitaxial layers grown on a GaAs substrate and observed in plan view. Strong variations of the diffracted intensities are observed depending on the thinning process used for TEM foil preparation. For chemically thinned samples, strong bending of the substrate occurs, inducing modifications of both kinematical and dynamical Bragg lines. For mechanically thinned samples, bending of the substrate is negligible. Kinematical lines are unaffected whereas dynamical lines have slightly asymmetric intensities. We analyse these effects using finite element modelling to calculate the sample strain coupled with dynamical multibeam simulations for calculating the diffracted intensities. Our results correctly reproduce the qualitative features of experimental patterns, clearly demonstrating that inhomogeneous displacement fields along the electron beam within the substrate are responsible for the observed intensity modifications. 相似文献
913.
Rhodotorula gracilis CFR-1 has been evaluated for its potential to produce lipids. The yeast lipids closely resembled palmolein, a liquid fraction
of palm oil. It contained 2.3–3% free fatty acids, 64.4% tri-, 23.1% di-, and 6.1% mono-acylglycerols, 94.2% neutral and 5.8%
polar lipids. Most abundant fatty acids were C18∶1, C16∶0, C18∶2 and C18∶0 (43.8, 28.5, 13.5 and 4.5%). All fatty acids, irrespective
of the levels, followed definite patterns of increase or decrease during the advancement of fermentation. A pincers-shaped
curve was obtained when the total saturation and unsaturation were plotted. Use of different glucose and molasses-based media
did not show any significant overall effect on saturation (34.4–39.5%) and unsaturation (60.4–65.3%). Desaturation of fatty
acids was found to be a metabolic function occurring in the process of cell maturation. 相似文献
914.
The open circuit potentials of the galvanic cell,Pt (or Au)¦(Ar + H2S + H2)′∥CaS + ZrO2(CaO)∥ (Ar + H2S+ H2)″£t (or Au) has been measured in the temperature range 1000 to 1660 K and PH2S:PH 2 ratios from 1.73×10?5 to 2.65×10?1. The solid electrolyte consists of a dispersion of calcium sulphide in a matrix of calcia-stabilized zirconia. The surface of the electrolyte is coated with a thin layer of calcium sulphide to prevent the formation of water vapour by reaction of hydrogen sulphide with calcium oxide or zirconia present in the electrolyte. The use of a ‘point electrode’ with a catalytically active tip was necessary to obtain steady emfs. At low temperatures and high sulphur potentials the emfs agreed with the Nernst equation. Deviations were observed at high temperatures and low sulphur potentials, probably due to the onset of significant electronic conduction in the oxide matrix of the electrolyte. The values of oxygen and sulphur potentials at which the electronic conductivity is equal to ionic conductivity in the two-phase electrolyte have been evaluated from the emf response of the cell. The sulphide-oxide electrolyte is unsuitable for sulphur potential measurements in atmospheres with high oxygen potentials, where oxidation of calcium sulphide may be expected. 相似文献
915.
We present a generalization of the Multiscale Enrichment based on Partition of Unity (MEPU) formulation originally reported
in Fish and Yuan (Int J Numer Methods Eng 62:1341–1359, 2005) to account for boundary layers, nonperiodic fields and nonlinear
systems. MEPU is aimed at extending the range of applicability of the mathematical homogenization theory to nonlinear nonperiodic
systems with inseparable fine and coarse scales. Performance studies for both continuum and coarse grained discrete systems
are conducted to validate the formulation. 相似文献
916.
Lilienfeld Scott O.; Jacob Rolf G.; Turner Samuel M. 《Canadian Metallurgical Quarterly》1989,98(1):100
W. Holloway and R. J. McNally (see record 1988-07600-001) found that normals with high scores on the Anxiety Sensitivity Index (ASI), an instrument developed to assess beliefs regarding the adverse consequences of anxiety, reported more anxiety and more frequent and intense somatic sensations following hyperventilation than did normals with low scores on the ASI. They concluded that this result provides support for the construct validity of the ASI and thus for the construct of anxiety sensitivity. Nevertheless, we argue that (a) the developers of the ASI have conflated beliefs regarding the adverse consequences of anxiety with fear of these consequences, (b) the accumulated evidence for the construct validity of the ASI is weak, and (c) Holloway and McNally's design and analyses do not permit them to exclude the more parsimonious explanation that trait anxiety accounts for their findings. Implications for research on anxiety sensitivity are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
917.
918.
Energy planning for mixed energy distribution systems is important to increase the flexibility in the regional and national energy systems. Expected maximum loads, load profiles and yearly energy demands, all divided into heat and electricity purposes, are important input parameters to plan for the most economical, technical and environmental optimal energy distribution system for a planning area. First, this article presents a load prediction method which estimates heat and electricity load profiles for various building categories. The method is based on statistical analyses of hourly simultaneous measured district heat and electricity consumption in several buildings, as well as background information of the measured buildings. The heat load model is based on regression analyses, whereas the electricity load model is based on various statistical distributions. Second, a method for load aggregation based on the building categories’ load profiles is presented to estimate the maximum load demands, yearly load profiles, load duration profiles and yearly energy demands, all divided into heat and electricity purposes, for a planning area. 相似文献
919.
Joseph V.P. Mathew S. Jacob J. Raveendranath U. Mathew K.T. 《Electronics letters》1997,33(24):2002-2004
The authors report the development of a novel E-plane sectoral horn. A metallic strip of optimum length loaded on the horn is capable of giving symmetric patterns both in the E and H-planes with low sidelobe levels 相似文献
920.
Jacob Fish Ted Belytschko 《International journal for numerical methods in engineering》1992,33(1):149-162
A rank-sufficient flat triangular shell element with drilling degrees-of-freedom is described. A variational basis for this element has been provided by a three-field variational principle with relaxed interelement compatibility and traction continuity conditions. A generalized spurious mode control procedure has been developed in order to stabilize zero energy kinematical modes. Excellent performance has been found in an obstacle course and buckling problems. 相似文献