| 1. |
- Löf, David, et al.
(författare)
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Structural Characterization of Nonionic Mixed Micelles Formed by C(12)EO(6) Surfactant and P123 Triblock Copolymer.
- 2009
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Ingår i: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 113:16, s. 5478-5486
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Tidskriftsartikel (refereegranskat)abstract
- A structural characterization of mixed micelles formed in aqueous solution by the PEO-PPO-PEO triblock copolymer P123 and the nonionic surfactant C(12)EO(6) was carried out using various techniques, including ultralow shear viscosimetry, depolarized dynamic light scattering (VH-DLS), depolarized static light scattering (VH-SLS), and small-angle X-ray scattering (SAXS). The sphere-to-rod transition of the mixed micelles was studied in a diluted regime (P123 concentrations ranging from 0.5 to 10 wt %) at C(12)EO(6)/P123 molar ratios of 2.2, 3.2, 6.0, and 11 as well as for the pure C(12)EO(6). The data from VH-SLS and viscosimetry displayed a sharp increase in the intensity and viscosity, respectively, at the sphere-to-rod transition, and the results from the two methods were in accordance. In both techniques, an increased transition temperature with increasing content of C(12)EO(6) (in the molar ratio regime from 2.2 to 11) was observed. SAXS was used as the main technique, and a thorough structural characterization was performed, where indirect Fourier transformation (IFT) and generalized indirect Fourier transformation (GIFT) were employed in the analysis procedure of the SAXS data. The p(r) functions obtained from the IFT (employed at low P123 concentrations, i.e., 1.0 and 2.0 wt %) and GIFT (employed above 2.0 wt %) analyses revealed increased inhomogeneities in the mixed micelles when the molar ratio was increased. This suggested that the C(12)EO(6) organized themselves at the interface between the PPO core and the PEO corona of the P123 micelles, with the C(12) alkyl chain stretching into the hydrophobic core and the EO(6) part residing in the hydrophilic corona. The structure factor parameters obtained with GIFT for a molar ratio of 2.2 at a P123 concentration of 5.0 wt % showed radius values smaller than what was estimated from the p(r) functions. This was explained by an interpenetration of the PEO chains from one mixed micelle into a neighboring one. VH-DLS was performed on the mixed micelles at a temperature 3 degrees C above the transition temperature and at a molar ratio of 2.2. From the analyzed data, the average length L of the rods was estimated to be 102 nm.
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| 2. |
- Wurst, Friedrich M., et al.
(författare)
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Measurement of direct ethanol metabolites in a case of a former driving under the influence (DUI) of alcohol offender, now claiming abstinence
- 2008
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Ingår i: International Journal of Legal Medicine. - : Springer Science and Business Media LLC. - 0937-9827 .- 1437-1596. ; 122:3, s. 235-239
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Tidskriftsartikel (refereegranskat)abstract
- A 37-year-old female subject had been convicted of driving under the influence of alcohol, and 19 months later, claimed abstinence after supervised disulfiram treatment. Our aim was to elucidate the value of direct ethanol metabolites as measures of abstinence. Ethyl glucuronide (EtG) and fatty acid ethyl esters (FAEE) in hair, phosphatidylethanol in whole blood and EtG and ethyl sulphate in urine were measured. The results were compared with self-report of alcohol consumption and traditional blood biomarkers for chronically elevated alcohol consumption as carbohydrate deficient transferrin (CDT), gamma glutamyl transpeptidase, mean corpuscular erythrocyte volume, aspartate aminotransferase and alanine aminotransferase. EtG was found in distal parts of hair only, whereas the proximal parts were negative. Furthermore, FAEE concentrations were found in the typical distribution over the hair length and showed values typical for either moderate social drinking or abstinence. CDT was above cut-off in 9 out of 16 analyses with a decreasing tendency and the lowest values in the last 2 months before the end of sampling. The data suggest that in addition to traditional markers, a combination of direct ethanol metabolites can be useful in the expert assessment of judging driving ability. A careful individual interpretation of the results for the different markers, however, is an absolute necessity.
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