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- Akselsson, Roland, et al.
(författare)
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Application of Proton Induced X-Ray Emission Analysis to the St. Louis Regional Air Pollution Study
- 1975
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Ingår i: Advances in X-Ray Analysis. ; 18, s. 588-597
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Tidskriftsartikel (refereegranskat)abstract
- The St Louis aerosol was sampled during the period 16-22 August 1973 simultaneously at two locations using cascade impactors for sequential 12-hour samples. The six particle size fractions of each sampling were individually analyzed using PIXE for elements from S to Br and beyond and for heavy elements including Pb which permitted time variations of concentrations and particle size distributions to be followed and related to meteorological changes during the sampling period. In addition, the data were compared with average levels of the elements in coastal north Florida and maritime Bermuda as well as at a third St. Louis site. From this it appeared that some of the concentrations in St. Louis were at natural levels whereas others appeared to be higher and linked to air pollution sources. These relationships and others in this study may lead to criteria for distinguishing between pollutants and natural background in urban aerosols.
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| 5. |
- Cottino, A, et al.
(författare)
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Die Schwedische Rechtshilfereform
- 1978
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Ingår i: Rechtsbedürfnis und Rechtshilfe. - Opladen : Westdeutscher Verlag. - 3531114506 ; , s. 162-174
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Johansson, C, et al.
(författare)
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Interaction by cholestyramine on the uptake of hydrocortisone in the gastrointestinal tract.
- 1978
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Ingår i: Acta medica Scandinavica. - 0001-6101. ; 204:6, s. 509-12
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Tidskriftsartikel (refereegranskat)abstract
- An absolute reduction of the plasma cortisol levels and a delay of the peak concentrations were recorded in 10 healthy subjects, when a bile-sequestering anionic exchange resin, cholestyramine, was given prior to a single oral hydrocortisone dose, indicating that the resin interferes with the uptake of a neutral sterol in the human gastrointestinal tract. The possibility of a direct binding of drug to resin is supported by the affinity of hydrocortisone to cholestyramine in vitro, which was uninfluenced by the presence of sodium taurocholate. Cholestyramine significantly delayed the gastric emptying of a glucose solution, indicating that the resin not only decreases but also delays hydrocortisone absorption. Careful supervision is recommended when treatment with cholestyramine is given concomitant to neutral sterol drugs.
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| 9. |
- Winchester, John W, et al.
(författare)
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Trace Metals in the St. Louis Aerosol
- 1974
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Ingår i: Proceedings of the Second International Conference on Nuclear Methods in Environmental Research. ; , s. 385-394
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Konferensbidrag (refereegranskat)abstract
- The elemental composition of the St. Louis aerosol has been investigated at rooftop sites in south and central locations in the city as part of the August, 1973 field season of the Regional Air Pollution Study of the U.S. Environmental Protection Agency. Sampling by 5-stage cascade impactor with backup filter permits analysis by proton-induced x-ray emission (PIXE) of size fractions of aerodynamic diameter >4, >2m >1, >0.5, >0.25, <0.25µm for elements 16S to 35Br by K x-ray detection and 82Pb by L x-rays. The aerosol study indicates the following: 1. Particle size distributions of S, Cl, K, Ca, Ti, V, Mn, Fe, Cu, Zn, Br, and Pb can be measured in samples from 0.7 m3 of air collected over 12-hour intervals at 1 liter/min flow rate, with precision of single analyses generally 10-30%, except near the nanogram detection limit. 2. Some elements, e.g. Ca, Fe, Ti, K show a tendency for highest concentrations in air measured in largest particle size fractions, and the pattern of distribution of concentration with size is relatively invariant. Predominantly dispersion source processes may account for their entry into the atmosphere. 3. Other elements, e.g. S, Pb, Zn, have substantial proportions of their atmospheric concentrations on smallest particles and show greater variability in particle size distribution patterns, suggesting aerosol formation processes of vapor condensation at high or low temperatures. 4. During 16-22 August 1973 an atmospheric change occurred from a period of low speed and mostly southerly air flow, with evident haze and air pollution, to higher speed and westerly shifting to easterly air flow, with improved visibility and air quality. The change was associated with drops in concentrations of Ti, Fe, Ca, K, and S but not Zn or Pb at the south site and Ti but not the other elements at the central site. Transport of air pollution from industrial sources south of the city is indicated. 5. The central site showed diurnal variation during the first period where concentrations of Ti, Fe, Ca, K, and S were higher in samples taken from midnight to noon than in those from noon to midnight. Variations were greatest for intermediate sized particles.
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