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| 2. |
- Bökman, C.F., et al.
(författare)
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Relating chromatographic retention and electrophoretic mobility to the ion distribution within electrosprayed droplets
- 2006
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Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305 .- 1879-1123. ; 17:3, s. 318-324
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Tidskriftsartikel (refereegranskat)abstract
- Ions that are observed in a mass spectrum obtained with electrospray mass spectrometry can be assumed to originate preferentially from ions that have a high distribution to the surface of the charged droplets. In this study, a relation between chromatographic retention and electrophoretic mobility to the ion distribution (derived from measured signal intensities in mass spectra and electrospray current) within electrosprayed droplets for a series of tetraalkylammonium ions, ranging from tetramethyl to tetrapentyl, is presented. Chromatographic retention in a reversed-phase system was taken as a measure of the analyte's surface activity, which was found to have a large influence on the ion distribution within electrosprayed droplets. In addition, different transport mechanisms such as electrophoretic migration and diffusion can influence the surface partitioning coefficient. The viscosity of the solvent system is affected by the methanol content and will influence both diffusion and ion mobility. However, as diffusion and ion mobility are proportional to each other, we have, in this study, chosen to focus on the ion mobility parameter. It was found that the influence of ion mobility relative to surface activity on the droplet surface partitioning of analyte ions decreases with increasing methanol content. This effect is most probably coupled to the decrease in droplet size caused by the decreased surface tension at increasing methanol content. The same observation was made upon increasing the ionic strength of the solvent system, which is also known to give rise to a decreased initial droplet size. The observed effect of ionic strength on the droplet surface partitioning of analyte ions could also be explained by the fact that at higher ionic strength, a larger number of ions are initially closer to the droplet surface and, thus, the contribution of ionic transport from the bulk liquid to the liquid/air surface interface (jet and droplet surface), attributable to migration or diffusion will decrease.
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| 4. |
- Lützenkirchena, J., et al.
(författare)
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Protonation of different goethite surfaces—Unified models for NaNO3 and NaCl media
- 2008
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 317:1, s. 155-165
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Tidskriftsartikel (refereegranskat)abstract
- Acid–base titration data for two goethites samples in sodium nitrate and sodium chloride media are discussed. The data are modeled based on various surface complexation models in the framework of the multi site complexation (MUSIC) model. Various assumptions with respect to the goethite morphology are considered in determining the site density of the surface functional groups. The results from the various model applications are not statistically significant in terms of goodness of fit. More importantly, various published assumptions with respect to the goethite morphology (i.e., the contributions of different crystal planes and their repercussions on the “overall” site densities of the various surface functional groups) do not significantly affect the final model parameters within simple 1-pK approximations. The simultaneous fit of the chloride and nitrate data results in electrolyte binding constants, which are applicable over a wide range of electrolyte concentrations including mixtures of chloride and nitrate. Model parameters for the goethite sample with 90 m2/g specific surface area are in excellent agreement with parameters that were independently obtained by another group on different goethite titration data sets.
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| 6. |
- Roos, Mårten, et al.
(författare)
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Graves' sjukdom vid graviditet ger risk för barnet : TSH-receptorantikroppar hos kvinnan kan ge fetal och neonatal tyreotoxikos
- 2008
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Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 105:3, s. 120-124
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Graves' sjukdom hos en gravid kvinna medför risk för fetal och neonatal tyreotoxikos hos barnet, vilket orsakas av stimulerande TSH-receptorantikroppar (TRAK) som passerar placenta under slutet av graviditeten. I enstaka fall kan TRAK även finnas hos en kvinna som tidigare opererats eller radiojodbehandlats för Graves' sjukdom. Antikroppstitern hos modern är ett bra mått på risken att barnet utvecklar fetal och neonatal tyreotoxikos. På senare år har nya metoder för att mäta TRAK introducerats. Vi har jämfört dessa med en tidigare metod och anger vilka TRAK-nivåer under graviditet som innebär stor risk för påverkan på barnet. Beskrivning av två fall illustrerar hur förloppet av Graves´ sjukdom under graviditet kan yttra sig.
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| 8. |
- Sjöberg, Jonny, et al.
(författare)
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Three-dimensional analysis of tunnel intersections for a train tunnel under Stockholm
- 2006
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Ingår i: North American Tunneling. - London : Taylor and Francis Group. - 9780415401289
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Konferensbidrag (refereegranskat)abstract
- The Citybanan commuter train tunnel will comprise a 6 km long, double-track train tunnel to be constructed in rock under Stockholm City. In this paper, analysis of the intersections between the planned train tunnel and so-called "energy tunnels" is described. The objective of this analysis was twofold: (i) to predict deformations and stability of the energy tunnels caused by excavation of the train tunnel, and (ii) to determine required rock reinforcement for the train tunnel. Analysis was conducted primarily using the three-dimensional finite difference program FLAC3[). The analysis results showed that only minor deformations can be expected in the energy tunnels due to the excavation of the train tunnel, and that the overall stability of the tunnels was satisfactory. Furthermore, the results could be used to confirm a proposed rock reinforcement scheme for the train tunnels, thus securing the stability of the load-bearing structure for the rock tunnel.
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| 9. |
- Wierup, P, et al.
(författare)
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Ex vivo evaluation of nonacceptable donor lungs
- 2006
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Ingår i: Annals of Thoracic Surgery. - : Elsevier BV. - 1552-6259 .- 0003-4975. ; 81:2, s. 460-466
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Tidskriftsartikel (refereegranskat)abstract
- Background. Only a minority of the potential candidates for lung donation are considered suitable, using current evaluation methods. A new method for ex vivo evaluation, with the potential for reconditioning of marginal and nonacceptable lungs, has been developed. This is a report of the ex vivo evaluation of six donor lungs deemed nonacceptable (arterial oxygen pressure less than 40 kPa) by the Scandiatransplant, Eurotransplant, and UK transplant organizations. Methods. The lungs are perfused ex vivo with Steen solution, a lung evaluation-preservation solution, mixed with red blood cells to a hematocrit of 15%. This extracellular solution is designed to have an optimal colloid osmotic pressure so that physiologic pressure and flow can be maintained without development of pulmonary edema. An oxygenator connected to the extracorporeal circuit maintains a normal mixed venous blood gas level in the perfusate. The lungs are ventilated and evaluated through analyses of pulmonary vascular resistance, oxygenation capacity, and arterial carbon dioxide pressure minus end-tidal carbon dioxide difference. Results. The arterial oxygen pressure (inspired oxygen fraction, 1.0) increased from 27 kPa (range, 17 to 34 kPa) in situ in the organ donor at the referring hospital to 57 kPa (range, 39 to 66 kPa) during the ex vivo evaluation. The pulmonary vascular resistance varied from 3.2 to 5.7 Wood units, and the arterial carbon dioxide pressure minus end-tidal carbon dioxide difference was in the range of 1 to 2.5 kPa. Conclusions. The arterial oxygen pressure improves significantly in this model. This ex vivo evaluation model is a valuable addition to the armamentarium in finding acceptable lungs in a donor population with inferior arterial oxygen pressure values.
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