868 resultados para Exclusion Chromatography
Resumo:
We have searched for periodic variations of the electronic recoil event rate in the (2-6) keV energy range recorded between February 2011 and March 2012 with the XENON100 detector, adding up to 224.6 live days in total. Following a detailed study to establish the stability of the detector and its background contributions during this run, we performed an un-binned profile likelihood analysis to identify any periodicity up to 500 days. We find a global significance of less than 1 sigma for all periods suggesting no statistically significant modulation in the data. While the local significance for an annual modulation is 2.8 sigma, the analysis of a multiple-scatter control sample and the phase of the modulation disfavor a dark matter interpretation. The DAMA/LIBRA annual modulation interpreted as a dark matter signature with axial-vector coupling of WIMPs to electrons is excluded at 4.8 sigma.
Resumo:
Occupational exposures to organic solvents, specifically acetonitrile and methanol, have the potential to cause serious long-term health effects. In the laboratory, these solvents are used extensively in protocols involving the use of high performance liquid chromatography (HPLC). Operators of HPLC equipment may be potentially exposed to these organic solvents when local exhaust ventilation is not employed properly or is not available, which can be the case in many settings. The objective of this research was to characterize the various sites of vapor release in the HPLC process and then to determine the relative influence of a novel vapor recovery system on the overall exposure to laboratory personnel. The effectiveness of steps to reduce environmental solvent vapor concentrations was assessed by measuring exposure levels of acetonitrile and methanol before and after installation of the vapor recovery system. With respect to acetonitrile, the concentration was not statistically significant with p=0.938; moreover, exposure after the intervention was actually higher than prior to intervention. With respect to methanol, the concentration was not statistically significant with p=0.278. This indicates that the exposure to methanol after the intervention was not statistically significantly higher or lower than prior to intervention. Thus, installation of the vapor recovery device did not result in statistically significant reduction in exposures in the settings encountered, and acetonitrile actually increased significantly.^
Resumo:
On DSDP Leg 84, gas hydrates were found at three sites (565, 568, and 570) and were inferred, on the basis of inorganic and organic geochemical evidence, to be present at two sites (566 and 569); no evidence for gas hydrates was observed at Site 567. Recovered gas hydrates appeared as solid pieces of white, icelike material occupying fractures in mudstone or as coarse-grained sediment in which the pore space exhibited rapid outgassing. Also a 1.05-m-long core of massive gas hydrate was obtained at Site 570. Downhole logging indicated that this hydrate was actually 3 to 4 m thick. Measurements of the amount of methane released during the decomposition of these recovered samples clearly showed that gas hydrates had been found. The distribution of evolved hydrocarbon gases indicated that Structure I gas hydrates were present because of the apparent inclusion of methane and ethane and exclusion of propane and higher molecular weight gases. The water composing the gas hydrates was fresh, having chlorinities ranging from 0.5 to 3.2 per mil. At Sites 565, 568, and 570, where gas hydrates were observed, the chlorinity of pore water squeezed from the sediment decreased with sediment depth. The chlorinity profiles may indicate that gas hydrates can often occur finely dispersed in sediments but that these gas hydrates are not recovered because they do not survive the drilling and recovery process. Methane in the gas hydrates found on Leg 84 was mainly derived in situ by biogenic processes, whereas the accompanying small amounts of ethane likely resulted from low-temperature diagenetic processes. Finding gas hydrates on Leg 84 expands observations made earlier on Leg 66 and particularly Leg 67. The results of all of these legs show that gas hydrates are common in landward slope sediments of the Middle American Trench from Mexico to Costa Rica.
Resumo:
The purpose of this paper is to characterize the configurations of the families that live in contexts of social exclusion; provide conceptualizations of their operation mode; highlight the formative effects that neighborhood interdisciplinary practices with such families produce in the just graduated psychologists, included on the Extension Program. We wish to contribute to produce systematic knowledge that can account for such family configurations as potential receiver of integration policies. We are also interested on transferring the approach to diversity in the training of young professionals, in order not to be regarded as a deviation from ideal models, but as an expression of different strategies built by members of a community, to resolve children breeding and to bear their existences. This work is the result about reflections on productions inside a research fellowship: The complexities that takes the breeding in families who lives in a social exclusion situation; researches about breeding, carried out from signature Developmental Psychology II, and from de interdisciplinary work with psychologically assisted families in twelve suburbs of the city of La Plata (University Extension Program "Free Legal Offices" (Convention between Law and Social Sciences and Psychology Faculties, U.N.L.P.). From a qualitative methodology and an interdisciplinary participation, the results have arrive at the characterization and proposed conceptualizations of the included families and at the same time determine the benefits that brings with the work that articulates research and extension activities for the training of advanced students and young graduates.
Resumo:
The purpose of this paper is to characterize the configurations of the families that live in contexts of social exclusion; provide conceptualizations of their operation mode; highlight the formative effects that neighborhood interdisciplinary practices with such families produce in the just graduated psychologists, included on the Extension Program. We wish to contribute to produce systematic knowledge that can account for such family configurations as potential receiver of integration policies. We are also interested on transferring the approach to diversity in the training of young professionals, in order not to be regarded as a deviation from ideal models, but as an expression of different strategies built by members of a community, to resolve children breeding and to bear their existences. This work is the result about reflections on productions inside a research fellowship: The complexities that takes the breeding in families who lives in a social exclusion situation; researches about breeding, carried out from signature Developmental Psychology II, and from de interdisciplinary work with psychologically assisted families in twelve suburbs of the city of La Plata (University Extension Program "Free Legal Offices" (Convention between Law and Social Sciences and Psychology Faculties, U.N.L.P.). From a qualitative methodology and an interdisciplinary participation, the results have arrive at the characterization and proposed conceptualizations of the included families and at the same time determine the benefits that brings with the work that articulates research and extension activities for the training of advanced students and young graduates.
Resumo:
The purpose of this paper is to characterize the configurations of the families that live in contexts of social exclusion; provide conceptualizations of their operation mode; highlight the formative effects that neighborhood interdisciplinary practices with such families produce in the just graduated psychologists, included on the Extension Program. We wish to contribute to produce systematic knowledge that can account for such family configurations as potential receiver of integration policies. We are also interested on transferring the approach to diversity in the training of young professionals, in order not to be regarded as a deviation from ideal models, but as an expression of different strategies built by members of a community, to resolve children breeding and to bear their existences. This work is the result about reflections on productions inside a research fellowship: The complexities that takes the breeding in families who lives in a social exclusion situation; researches about breeding, carried out from signature Developmental Psychology II, and from de interdisciplinary work with psychologically assisted families in twelve suburbs of the city of La Plata (University Extension Program "Free Legal Offices" (Convention between Law and Social Sciences and Psychology Faculties, U.N.L.P.). From a qualitative methodology and an interdisciplinary participation, the results have arrive at the characterization and proposed conceptualizations of the included families and at the same time determine the benefits that brings with the work that articulates research and extension activities for the training of advanced students and young graduates.
Resumo:
Seventeen sediment samples of Albian-Cenomanian to early Pliocene age from DSDP Hole 530A in the Angola Basin and six sediment samples of early Pliocene to late Pleistocene age from the Walvis Ridge were investigated by organic geochemical methods, including organic carbon determination, Rock-Eval pyrolysis, gas chromatography and combined gas chromatography/mass spectrometry of extractable hydrocarbons, and kerogen microscopy. The organic matter in all samples is strongly influenced by a terrigenous component from the nearby continent. The amount of marine organic matter present usually increases with the total organic carbon content, which reaches an extreme value of more than 10% in a Cenomanian black shale from Hole 530A. At Site 530 the extent of preservation of organic matter in the deep sea sediments is related to mass transport down the continental slope, whereas the high organic carbon contents in the sediments from Site 532 reflect both high bioproductivity in the Benguela upwelling regime and considerable supply of terrigenous organic matter. The maturation level of the organic matter is low in all samples.