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Sökning: WFRF:(Marie Nathalie) > Chalmers tekniska högskola

  • Resultat 1-6 av 6
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1.
  • Allan, Ian J., et al. (författare)
  • Evaluation of the Chemcatcher and DGT passive samplers for monitoring metals with highly fluctuating water concentrations
  • 2007
  • Ingår i: Journal of Environmental Monitoring. ; 9:7, s. 672-681
  • Tidskriftsartikel (refereegranskat)abstract
    • Passive sampling devices accumulate chems. continuously from water and can provide time weighted av. (TWA) concns. of pollutants over the exposure period. Hence, they offer a no. of advantages over other conventional monitoring techniques such as spot or grab sampling. The diffusive gradient in thin film (DGT) and the Chemcatcher passive samplers can be used to provide TWA concns. of labile metals, but the approaches to their calibration differ. DGT uses diffusion coeffs. of metals in the hydrogel layer, whereas Chemcatcher uses metal specific uptake rates, with both sets of values obtained under controlled lab. conditions with const. aq. metal concns. However, little is known of how such samplers respond to fluctuating concns. We evaluated the responsiveness of these two passive sampling devices to rapidly changing concns. of Cd, Cu, Ni, Pb and Zn in natural freshwater, over a relatively short deployment time. Maximum metal concns. in water were varied between 70 and 140 mg L-1. Expts. were carried out in a tank with a rotating carousel system and filled with Meuse River water, allowing a degree of control over exptl. conditions while using natural river water. Fluctuating concns. were obtained by stepwise addn. of std. solns. of the metals. The reliability and accuracy of the TWA concns. measured by the samplers were assessed by comparison with concns. of the metals in spot samples of water taken regularly over the deployment period. The spot samples of water were either unfiltered (total), filtered (0.45 mm) or ultrafiltered (5 kDa). Predictive speciation modeling using the visual MINTEQ program was also undertaken. There was reasonable agreement between the TWA concns. of Cd and Ni obtained with Chemcatcher and DGT and the total Cd and Ni concns. measured in repeated unfiltered spot samples. For elements (i.e. Cu, Pb, Zn) that assoc. to a significant degree with suspended solids, colloids or dissolved org. carbon, or form complexes with large org. ligands, optimum agreement was with the filtered or ultrafiltered fractions and with the predicted inorg. and inorg.-fulvic acid assocd. fractions. While Chemcatcher-based TWA concn. ranges for Cu and Zn were in best agreement with the total filtered fraction, there was lack of agreement for Pb. The combined use of DGT devices with open pore (OP) and restricted pore (RP) gels allowed the labile fraction of metal assocd. with large org. ligands or DOC to be differentiated and quantified, since this is available to DGT OP but unable to diffuse into the DGT RP. This evaluation of the two sampling devices clearly demonstrated their ability to react reliably to transient peaks in concn. of metal pollutants in water and indicated where future efforts are needed to improve calibration data. Such samplers may prove valuable in responding to the monitoring requirements of the European Union's Water Framework Directive. [on SciFinder (R)]
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2.
  • Allan, Ian J., et al. (författare)
  • Strategic monitoring for the European Water Framework Directive
  • 2006
  • Ingår i: TrAC - Trends in Analytical Chemistry. - : Elsevier BV. - 0165-9936. ; 25:7, s. 704-715
  • Tidskriftsartikel (refereegranskat)abstract
    • This article first reviews the principal monitoring requirements of the Water Framework Directive (WFD) of the European Union (EU) and assesses how contaminant monitoring may fit into a risk-assessment approach. In this context, we show the limited ability of conventional trace-contaminant-monitoring methods to fulfil all of the WFD requirements. We then clearly define and exemplify the roles and the functions of a new set of monitoring tools, using three case studies based on datasets that we obtained during a field trial in the River Meuse as part of the Screening methods for Water data InFormaTion (SWIFT-WFD) project in support of implementing the WFD.
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4.
  • Berne, Olivier, et al. (författare)
  • PDRs4All : A JWST Early Release Science Program on Radiative Feedback from Massive Stars
  • 2022
  • Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 134:1035
  • Tidskriftsartikel (refereegranskat)abstract
    • Massive stars disrupt their natal molecular cloud material through radiative and mechanical feedback processes. These processes have profound effects on the evolution of interstellar matter in our Galaxy and throughout the universe, from the era of vigorous star formation at redshifts of 1-3 to the present day. The dominant feedback processes can be probed by observations of the Photo-Dissociation Regions (PDRs) where the far-ultraviolet photons of massive stars create warm regions of gas and dust in the neutral atomic and molecular gas. PDR emission provides a unique tool to study in detail the physical and chemical processes that are relevant for most of the mass in inter- and circumstellar media including diffuse clouds, proto-planetary disks, and molecular cloud surfaces, globules, planetary nebulae, and star-forming regions. PDR emission dominates the infrared (IR) spectra of star-forming galaxies. Most of the Galactic and extragalactic observations obtained with the James Webb Space Telescope (JWST) will therefore arise in PDR emission. In this paper we present an Early Release Science program using the MIRI, NIRSpec, and NIRCam instruments dedicated to the observations of an emblematic and nearby PDR: the Orion Bar. These early JWST observations will provide template data sets designed to identify key PDR characteristics in JWST observations. These data will serve to benchmark PDR models and extend them into the JWST era. We also present the Science-Enabling products that we will provide to the community. These template data sets and Science-Enabling products will guide the preparation of future proposals on star-forming regions in our Galaxy and beyond and will facilitate data analysis and interpretation of forthcoming JWST observations.
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5.
  • McGinn, Steven, et al. (författare)
  • New Technologies for DNA analysis-A review of the READNA Project.
  • 2016
  • Ingår i: New Biotechnology. - : Elsevier BV. - 1876-4347 .- 1871-6784.
  • Forskningsöversikt (refereegranskat)abstract
    • The REvolutionary Approaches and Devices for Nucleic Acid analysis (READNA) project received funding from the European Commission for 4 1/2 years. The objectives of the project revolved around technological developments in nucleic acid analysis. The project partners have discovered, created and developed a huge body of insights into nucleic acid analysis, ranging from improvements and implementation of current technologies to the most promising sequencing technologies that constitute a 3(rd) and 4(th) generation of sequencing methods with nanopores and in situ sequencing, respectively.
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6.
  • Scheers, Nathalie, 1974, et al. (författare)
  • Determination of Fe2+ and Fe3+ in aqueous solutions containing food chelators by differential pulse anodic stripping voltammetry
  • 2010
  • Ingår i: Electroanalysis. - : Wiley. - 1040-0397 .- 1521-4109. ; 22:10, s. 1090-1096
  • Tidskriftsartikel (refereegranskat)abstract
    • The objective was to investigate interactions between iron and food chelators in an aqueous environment. The net complexation were investigated by DPASV in a NaClO4 electrolyte using a platinum electrode. The experimental conditions were simulating the environment of the human duodenum. The results indicated a net coordination affinity between Fe2+ and the organic acids in the following order; ascorbic acidphytate>pyruvate>lactate>acetate. For Fe3+ net complexation, the stability was in the order of lactate>phytate>pyruvate>acetate>citrate. In conclusion, DPASV in conjunction with a platinum electrode is suitable for studies in aqueous systems where the net complexation of metal is important.
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  • Resultat 1-6 av 6

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