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21.
Roberto Fabiani Angelo De Bartolomeo Patrizia Rosignoli Guido Morozzi Angelo Cecinato Catia Balducci 《Polycyclic Aromatic Compounds》2013,33(4-5):486-499
The relationship between chemical composition of airborne particulates and the genotoxicity has been investigated in the atmosphere of Rome, Italy. For this purpose, both total suspended particulate (TSP) and the PM 10 fractions were collected daily inside a green park located in downtown, grouped on a weekly basis and speciated for their burdens of polycyclic aromatic hydrocarbons (PAH) and nitro-PAH. Concurrently, the genotoxicity of the organic extracts was evaluated by the Comet assay (SCGE: single cell gel electrophoresis) on human peripheral blood mononuclear cells (PBMC). The results indicate that organic extracts were able to induce DNA damage and a cytotoxic effect on PBMC. The TSP fraction was more cytotoxic than PM 10 while the genotoxicity of both fractions was comparable. The genotoxic potential of the different samples was highly correlated to the amount of total PAH (correlation coefficient = 0.87), carcinogenic PAH (correlation coefficient = 0.88), B(a)P (correlation coefficient = 0.87) and to a less extend to the concentration of 1-nitropyrene (correlation coefficient = 0.66). The seasonal modulation suggests that in Rome the air is more toxic during winter, however in the warm season oxidized species including nitro-PAHs (evolving from secondary pollution) seem to balance the decrease of PAH concentration rates. 相似文献
22.
In the present article, a new separation system was employed for the extraction of cadmium from nitric acid solutions for the first time. Phosphine oxide, tris[(dibutylamino)methyl]-(7CI,8CI),which contains nitrogen atoms and phosphorus atom in molecular, was used as extractant. The influence of the following parameters was investigated: the organic/aqueous phase ratio (O/A), pH, contact time, temperature, the concentration of extractant, cadmium (Ⅱ), sodium nitrate and sodium chloride. Results demonstrated that quantitative extraction of cadmium was feasible from 50 mg/L cadmium feed solution in a single stage at pH 3.0, 15 min and O/A phase ratio 1:5 with 20% extractant in cyclohexane diluent. The cadmium extraction isotherm under different cadmium ion concentrations was established. The loaded cadmium could be stripped by 4 mol/L ammonium chloride aqueous solutions. A contrast study was carried out, and the results indicated that phosphine oxide, tris[(dibutylamino)methyl] –(7CI,8CI), could take the place of commercial organo-phosphorous extractants in the process of cadmium(II) extractions for its effectivity, stability and low price. 相似文献
23.
《Materials at High Temperatures》2013,30(4):297-301
AbstractIron and model alloys containing 1, 2, and 3wt% Si were reacted with dry and wet CO2 gases at 800°C. All oxidised in dry CO2 according to approximately linear kinetics. Additions of H2O accelerated the reaction until steady-state parabolic kinetics were achieved. However, the effect of H2O was small in the steady-state reaction stage of Fe – 3Si. Alloy reaction products were a duplex scale consisting of an outer FeO+Fe3O4 layer and an inner FeO+Fe2SiO4 layer, plus an internal oxidation zone, in all gases. In Fe – 1Si, amorphous SiO2 precipitates in the internal oxidation zone grew with rod-like morphologies in all gases. However, internal amorphous SiO2 precipitates grown in Fe – 2Si and Fe – 3Si formed network patterns. Internal penetration rates were initially rapid in Fe – 1Si, but slowed considerably at longer times. In Fe – 3Si, the internal oxidation zone grew wider in the first 20 h of reaction, and then remained constant in dry gas. In the wet gases this zone subsequently diminished, and disappeared after 50 h reaction. 相似文献
24.
Jayne Merkel 《Architectural Design》2007,77(5):112-117
The two most interesting, talked about new office buildings in New York both have unique angular profiles and unusual shiny surfaces that have irrevocably changed their neighbourhoods. Jayne Merkel takes a peak at the interiors of Norman Foster's triangulated steel-and-glass Hearst Tower and Frank Gehry's curvaceous, white-glass hulk for the IAC/InterActiveCorp. In so doing she sizes up what effect the exotic exteriors have on the spaces where the editors, writers, designers and media executives work. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
25.
J. Mukherjee M. Aswatha Kumar P. P. Das B. N. Chatterji 《Pattern recognition letters》2002,23(14):211-1656
Medial axis transform (MAT) is well known for object representation. It is interesting to explore its use in different kinds of computations. In this paper an algorithm has been proposed for computation of normals at the boundaries of two-dimensional objects based on their MATs. In this technique, there is no requirement of linking boundary points during the computation compared to other existing techniques. The added advantage in the computation is that the computation can be restricted purely in the integer domain. 相似文献