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- Buser, Andreas M., et al.
(författare)
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Concentrations in Ambient Air and Emissions of Cyclic Volatile Methylsiloxanes in Zurich, Switzerland
- 2013
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 47:13, s. 7045-7051
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Tidskriftsartikel (refereegranskat)abstract
- Tens of thousands of tonnes of cyclic volatile methylsiloxanes (cVMS) are used each year globally, which leads to high and continuous cVMS emissions to air. However, field measurements of cVMS in air and empirical information about emission rates to air are still limited. Here we present measurements of decamethylcyclopentasfloxane (D-5) and dodecamethylcyclohexasiloxane (D-6) in air for Zurich, Switzerland. The measurements were performed in January and February 2011 over a period of eight days and at two sites (city center and background) with a temporal resolution of 6-12 h. Concentrations of Ds and D-6 are higher in the center of Zurich and range from 100 to 650 ng m(-3) and from 10 to 79 ng m(-3), respectively. These values are among the highest levels of D-5 and D-6 reported in the literature. In a second step, we used a multimedia environmental fate model parametrized for the region of Zurich to interpret the levels and time trends in the cVMS concentrations and to back calculate the emission rates of D-5 and D-6 from the city of Zurich. The average emission rates obtained for D-5 and D-6 are 120 kg d(-1) and 14 kg d(-1), respectively, which corresponds to per capita emissions of 310 mg capita(-1) d(-1) for D-5 and 36 mg capita(-1) d(-1) for D-6.
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- Kierkegaard, M, et al.
(författare)
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The relationship between walking, manual dexterity, cognition and activity/participation in persons with multiple sclerosis
- 2012
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Ingår i: Multiple sclerosis (Houndmills, Basingstoke, England). - : SAGE Publications. - 1477-0970 .- 1352-4585. ; 18:5, s. 639-646
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Tidskriftsartikel (refereegranskat)abstract
- Background: Multiple sclerosis has a vast impact on health, but the relationship between walking, manual dexterity, cognition and activity/participation is unclear. Objective: The specific aims were to explore the discriminative ability of measures of walking, manual dexterity and cognition, and to identify cut-off values in these measures, for prediction of independence in personal and instrumental activities of daily living (ADL) and activity/participation in social and lifestyle activities. Methods: Data from 164 persons with multiple sclerosis were collected during home visits with the following measures: the 2 × 5 m walk test, the Nine-hole Peg Test, the Symbol Digit Modalities Test, the Katz Personal and Instrumental ADL Indexes, and the Frenchay Activities Index (measuring frequency in social and lifestyle activities). Results: The 2 × 5 m walk test and the Nine-hole Peg Test had high and better discriminative and predictive ability than the Symbol Digit Modalities Test. Cut-off values were identified. The accuracy of predictions was increased above all by combining the 2 × 5 m walk test and the Nine-hole Peg Test. Conclusion: The proposed cut-off values in the 2 × 5 m walk test and the Nine-hole Peg Test may be used as indicators of functioning and to identify persons risking activity limitations and participation restrictions. However, further studies are needed to confirm the usefulness in clinical practice.
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- Krogseth, Ingjerd S., et al.
(författare)
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Occurrence and seasonality of cyclic volatile methyl siloxanes in arctic air
- 2013
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 47:1, s. 502-509
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Tidskriftsartikel (refereegranskat)abstract
- Cyclic volatile methyl siloxanes (cVMS) are present in technical applications and personal care products. They are predicted to undergo long-range atmospheric transport, but measurements of cVMS in remote areas remain scarce. An active air sampling method for decamethylcyclopentasiloxane (D5) was further evaluated to include hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), and dodecamethylcyclohexasiloxane (D6). Air samples were collected at the Zeppelin observatory in the remote Arctic (79 degrees N, 12 degrees E) with an average sampling time of 81 +/- 23 h in late summer (August-October) and 25 +/- 10 h in early winter (November-December) 2011. The average concentrations of D5 and D6 in late summer were 0.73 +/- 0.31 and 0.23 +/- 0.17 ng/m(3), respectively, and 2.94 +/- 0.46 and 0.45 +/- 0.18 ng/m(3) in early winter, respectively. Detection of D5 and D6 in the Arctic atmosphere confirms their long-range atmospheric transport. The D5 measurements agreed well with predictions from a Eulerian atmospheric chemistry-transport model, and seasonal variability was explained by the seasonality in the OH radical concentrations. These results extend our understanding of the atmospheric fate of D5 to high latitudes, but question the levels of D3 and D4 that have previously been measured at Zeppelin with passive air samplers.
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| 8. |
- McLachlan, Michael S., et al.
(författare)
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Concentrations and Fate of Decamethylcyclopentasiloxane (D-5) in the Atmosphere
- 2010
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 44:14, s. 5365-5370
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Tidskriftsartikel (refereegranskat)abstract
- Decamethylcyclopentasiloxane (D-5) is a volatile compound used in personal care products that is released to the atmosphere in large quantities. Although D-5 is currently under consideration for regulation, there have been no field investigations of its atmospheric fate. We employed a recently developed, quality assured method to measure D-5 concentration in ambient air at a rural site in Sweden. The samples were collected with daily resolution between January and June 2009. The 05 concentration ranged from 0.3 to 9 ng m(-3), which is 1-3 orders of magnitude lower than previous reports. The measured data were compared with D-5 concentrations predicted using an atmospheric circulation model that included both OH radical and D-5 chemistry. The model was parametrized using emissions estimates and physical chemical properties determined in laboratory experiments. There was good agreement between the measured and modeled D-5 concentrations. The results show that D-5 is clearly subject to long-range atmospheric transport, but that it is also effectively removed from the atmosphere via phototransformation. Atmospheric deposition has little influence on the atmospheric fate. The good agreement between the model predictions and the field observations indicates that there is a good understanding of the major factors governing D-5 concentrations in the atmosphere.
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