Fant 10278 publikasjoner. Viser side 302 av 412:
Nanomaterial grouping: Existing approaches and future recommendations
The physico-chemical properties of manufactured nanomaterials (NMs) can be fine-tuned to obtain different functionalities addressing the needs of specific industrial applications. The physico-chemical properties of NMs also drive their biological interactions. Accordingly, each NM requires an adequate physico-chemical characterization and potentially an extensive and time-consuming (eco)toxicological assessment, depending on regulatory requirements. Grouping and read-across approaches, which have already been established for chemicals in general, are based on similarity between substances and can be used to fill data gaps without performing additional testing. Available data on “source” chemicals are thus used to predict the fate, toxicokinetics and/or (eco)toxicity of structurally similar “target” chemical(s). For NMs similar approaches are only beginning to emerge and several challenges remain, including the identification of the most relevant physico-chemical properties for supporting the claim of similarity. In general, NMs require additional parameters for a proper physico-chemical description. Furthermore, some parameters change during a NM's life cycle, suggesting that also the toxicological profile may change.
This paper compares existing concepts for NM grouping, considering their underlying basic principles and criteria as well as their applicability for regulatory and other purposes. Perspectives and recommendations based on experiences obtained during the EU Horizon 2020 project NanoReg2 are presented. These include, for instance, the importance of harmonized data storage systems, the application of harmonized scoring systems for comparing biological responses, and the use of high-throughput and other screening approaches. We also include references to other ongoing EU projects addressing some of these challenges.
2019
2019
2019
2019
Europe's urban air quality — re-assessing implementation challenges in cities
This report analyses the implementation of EU air quality legislation at the urban level and identifies some of the reasons behind persistent air quality problems in Europe's cities. It is produced in cooperation with 10 cities involved in a 2013 Air Implementation Pilot project: Antwerp (Belgium), Berlin (Germany), Dublin (Ireland), Madrid (Spain), Malmö (Sweden), Milan (Italy), Paris (France), Plovdiv (Bulgaria), Prague (Czechia) and Vienna (Austria).
European Environment Agency
2019
2019
Two years of continuous in situ measurements of Arctic low‐level clouds have been made at the Mount Zeppelin Observatory (78°56′N, 11°53′E), in Ny‐Ålesund, Spitsbergen. The monthly median value of the cloud particle number concentration (Nc) showed a clear seasonal variation: Its maximum appeared in May–July (65 ± 8 cm−3), and it remained low between October and March (8 ± 7 cm−3). At temperatures warmer than 0 °C, a clear correlation was found between the hourly Nc values and the number concentrations of aerosols with dry diameters larger than 70 nm (N70), which are proxies for cloud condensation nuclei (CCN). When clouds were detected at temperatures colder than 0 °C, some of the data followed the summertime Nc to N70 relationship, while other data showed systematically lower Nc values. The lidar‐derived depolarization ratios suggested that the former (CCN‐controlled) and latter (CCN‐uncontrolled) data generally corresponded to clouds consisting of supercooled water droplets and those containing ice particles, respectively. The CCN‐controlled data persistently appeared throughout the year at Zeppelin. The aerosol‐cloud interaction index (ACI = dlnNc/(3dlnN70)) for the CCN‐controlled data showed high sensitivities to aerosols both in the summer (clean air) and winter–spring (Arctic haze) seasons (0.22 ± 0.03 and 0.25 ± 0.02, respectively). The air parcel model calculations generally reproduced these values. The threshold diameters of aerosol activation (Dact), which account for the Nc of the CCN‐controlled data, were as low as 30–50 nm when N70 was less than 30 cm−3, suggesting that new particle formation can affect Arctic cloud microphysics.
2019
2019
2019
Air quality assessment and management in Europe and Norway: History, current status and future plans
2019
2019
2019
2019
Norwegian Scientific Committee for Food and Environment (VKM)
2019
Målet med studien er å vurdere effekten av tilskudd til utskifting av gamle vedovner til nye rentbrennende ovner, og i hvilken grad ordningen har påvirket det totale partikkelutslippet og luftkonsentrasjoner i Oslo kommune. NILU har utført tre beregninger; 1) utslippsmodellering og spredningsberegninger for 4 ulike scenarioer; 2) utslippsreduksjon fra tilskuddsordningen i Oslo kommune; og 3) vurdering av tidsutvikling av vedfyringsutslipp, vedforbruk og utslippsfaktorer for kommuner med og uten tilskuddsordning. Modellering og vurdering av den potensielle utslippsreduksjonen som kan tilskrives tilskuddsordningen, viser at tilskuddsordningen potensielt har en stor effekt på reduksjon av partikkelutslipp og konsentrasjoner av PM2.5 og PM10. Beregnigene viser at tilskuddsordningen i Oslo kommune gir betydelig redusert utslippsfaktor over tid, men effekten på totalt PM-utslipp er liten.
NILU
2019
Anodes fabricated from a single source coke were used for investigations of effect of porosity and surface roughness on the electrochemical performance in laboratory scale cells. In order to fabricate anodes differing in porosity, the production parameters were varied with two levels of mixing temperatures (150 and 210 °C) and three baking levels (underbaking at 1150°E, normal baking at 1260°E, overbaking at 1350°E). °E denotes the equivalent temperature which is a function of both the temperature the anode sees, and the time kept at this temperature. The low mixing anodes were more inhomogeneous with respect to both micro- and macroporosity, which can be attributed to the wetting between pitch and coke. After electrolysis, the real surface area of the low mixing anodes was about 13% higher than the high mixing anodes. Also, the low mixing electrodes had slightly larger electrochemically active surface area after electrolysis compared to the high mixing electrodes, as evidenced by higher capacitance measured at low current densities. Still, the mixing and equivalent baking temperatures did not affect the electrochemical overpotential at 1 A/cm2 to any significant extent. This could be understood from the 3D computed tomography images, which also showed that the electrolyte does not generally penetrate into the pores on the surface, penetration will depend on the size and shape of the pore.
2019