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| 2. |
- Karlsson, Camilla A-C, et al.
(författare)
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Detergent Induced Removal of b-Lactoglobulin from Stainless Steel Surfaces at Influenced by Surface Pretreatment
- 1999
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 220, s. 471-473
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of β-lactoglobulin to stainless steel and its subsequent removal were followed using in situ null ellipsometry. The influence of the surface pretreatment on the protein removal by the surfactant SDS and by sodium hydroxide was studied. All surfaces were precleaned in strongly alkaline solution. Some surfaces received no further pretreatment, while others were either passivated in nitric acid or plasma-cleaned prior to experiments. Stainless steel surfaces subjected to different surface pretreatments showed considerable differences in cleaning behavior. Cleaning, using NaOH, of surfaces which had been precleaned with alkali only or with plasma resulted in practically complete β-lactoglobulin removal. In contrast, appreciable amounts of protein remained on passivated stainless steel. Protein removal by SDS was limited and comparable for all three surface pretreatments investigated. Only minor effects on the protein adsorption tendency were observed. The amounts of β-lactoglobulin adsorbed tended to be somewhat lower on the passivated surfaces.
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| 3. |
- Karlsson, Camilla A-C, et al.
(författare)
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Some surface-related aspects of the cleaning of new and reused stainless-steel surfaces fouled by protein
- 1998
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Ingår i: International Dairy Journal. - 0958-6946. ; 8:10, s. 925-933
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of β-lactoglobulin to stainless steel and its subsequent alkali-induced removal were followed using ellipsometry. New steel samples differing in bulk composition, surface finish or chemical pretreatment were used. All surfaces were precleaned in strongly alkaline solution, and some were subsequently passivated in nitric acid. Furthermore, on surfaces differing in pretreatment measurements were performed during repeated fouling and cleaning cycles. No correlation was found between the bulk composition or the surface finish and the fouling tendency or the cleanability. However, striking differences in cleanability between stainless-steel surfaces subjected to different chemical pretreatments were evident, particularly at low temperature. Still, only minor effects on the fouling tendency were observed. When subjecting surfaces to repeated fouling and cleaning without renewed pretreatment, the differences in cleaning performance decreased but were still significant. While the cleanability of non-passivated surfaces appeared to decrease somewhat when reused, changes seemed smaller for passivated surfaces.
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| 4. |
- Karlsson, Camilla A-C, et al.
(författare)
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Time and temperature aspects of β-lactoglobulin removal from methylated silica surfaces by sodium dodecyl sulphate
- 1996
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Ingår i: Colloids and Surfaces B: Biointerfaces. - : Elsevier BV. - 0927-7765. ; 6:4, s. 317-328
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of β-lactoglobulin onto methylated silica surfaces and the subsequent protein removal by the anionic surfactant sodium dodecyl sulphate (SDS) were followed using in-situ ellipsometry. Experiments were performed at pH 6.0 in phosphate-buffered saline solution. Parameters varied include temperature, length of time for protein adsorption from solution and surface residence time of β-lactoglobulin. The temperature was kept constant throughout a trial, and the majority of experiments were carried out at a few degrees below the protein denaturation temperature as reported from differential scanning calorimetry studies. β-Lactoglobulin adsorption at high temperatures resulted in aggregation at the surface after a lag phase of several minutes. Varying the protein adsorption time and thus the amount adsorbed while keeping the protein surface residence time fixed did not seem to affect the amount desorbed upon rinsing or the amount eluted by surfactant. For short β-lactoglobulin adsorption times, the adsorbed amounts were comparable at all temperatures studied. The temperature hardly affected the amount desorbed during rinsing, but did however have a pronounced influence on the protein removed by surfactant. Up to around 60°C practically all β-lactoglobulin was eluted by the SDS. The fraction removed then decreased with temperature, with a sharp drop between 70 and 73°C, and a further decline at higher levels. SDS was seen to be highly inefficient at removing β-lactoglobulin adsorbed at temperatures above 70°C. The trend observed is attributed to temperature-dependent changes in the protein resident on the surface. The β-lactoglobulin surface residence time was seen to significantly affect the elutability. At short residence times the removal efficiency was comparably high, but decreased with time. However, no significant difference could be detected between two sufficiently long residence times. The behaviour is consistent with the assumption of multiple states of adsorbed proteins, together with slow conformational changes in the adsorbed protein layer.
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| 5. |
- Karlsson, Camilla A-C, et al.
(författare)
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β-Lactoglobulin fouling and its removal upon rinsing and by SDS as influenced by surface characteristics, temperature and adsorption time
- 1996
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Ingår i: Journal of Food Engineering. - 0260-8774. ; 30:1-2, s. 43-60
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Tidskriftsartikel (refereegranskat)abstract
- The extensive fouling common in the food industry puts high demands on equipment cleaning. The adsorption of β-lactoglobulin and its removal by the anionic surfactant sodium dodecyl sulphate (SDS) were followed at pH 6.0 using in situ ellipsometry. Hydrophilic chromium oxide and stainless steel together with hydrophobic methylated silica were studied at different temperatures. Differences between chromium oxide and steel were small, while hydrophobic silica showed significantly different initial adsorption kinetics and adsorbed amounts. Also, the temperature-dependence of the amount desorbed upon rinsing as well as of the overall cleanability differed greatly. At around the β-lactoglobulin denaturation temperature, multilayer build-up at the surface was seen, and the cleanability was very low. Of two protein adsorption times employed, the longer resulted, for metal oxide surfaces, in less desorption during rinsing.
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| 6. |
- Sikstrom, C. M, et al.
(författare)
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New Zr II oscillator strengths and the zirconium conflict in the HgMn star chi Lupi
- 1999
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Ingår i: Astronomy & Astrophysics. - 0004-6361. ; 343:1, s. 297-302
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Tidskriftsartikel (refereegranskat)abstract
- Lifetimes on the sub-nanosecond scale for the levels v(2)D(3/2), v(2)F(3/2) and v(2)F(5/2) in the 4d5s5p configuration in Zr II have been measured, using the method of laser-induced fluorescence. Combined with branching fractions obtained with the Lund Ultraviolet (UV) Fourier Transform Spectrometer (FTS), experimental oscillator strengths have been derived. From Hubble Space Telescope/Goddard High-Resolution Spectrograph spectra, the zirconium abundance in the HgMn star chi Lupi has been determined from Zr II and Zr III lines. More than an order of magnitude difference in the Zr II abundance has been derived from these ionization stages. The difference is much too large to be explained by uncertainties in the oscillator strengths. Possible explanations of this difference have to be found in the stellar models, such as the influence of non-LTE or diffusion.
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| 7. |
- Arnebrant, Thomas, et al.
(författare)
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Protein-surfactant interactions at solid surfaces
- 1995
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Ingår i: Proteins at Interfaces II Fundamentals and Applications. - Washington, DC : American Chemical Society. - 9780841233041 - 9780841215276 ; 602, s. 239-255
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Bokkapitel (refereegranskat)abstract
- Effects of surfactants on protein adsorption are reviewed. Differences between removal of preadsorbed proteins (elutability) and competitive adsorption are discussed and simple models are suggested. It can be concluded that surfactants may interact through solubilization or replacement mechanisms depending on surfactant- surface interactions and surfactant- protein binding. Solubilization requires complex formation between protein and surfactant, and the replacement adsorption of the surfactant to the surface. As for protein adsorption, one of the most important properties affecting the elutability appears to be the conformational stability. Differences between a competitive situation and addition of surfactant after adsorption of the protein are suggested to originate from alteration in surface activity of protein-surfactant complexes formed in solution as compared to pure protein, the difference in diffusivity of surfactants and protein, and time dependent conformational changes of the protein.
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| 14. |
- Stephens, M. B., et al.
(författare)
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Bedrock geology and mineral resources of Sweden
- 1997
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Ingår i: Encyclopedia of European and Asian regional geology. - London : Taylor and Francis Group. - 0412740400 ; , s. 690-704
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 15. |
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| 17. |
- Örnebro, J, et al.
(författare)
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Adsorption of α-, β-, γ- and ω-Gliadins onto Hydrophobic Surfaces
- 1999
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Ingår i: Journal of Cereal Science. - : Elsevier BV. - 0733-5210. ; 77:5, s. 105-114
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Tidskriftsartikel (refereegranskat)abstract
- Adsorption onto hydrophobic surfaces of α-, β-, γ-, and ω-gliadins from the wheat variety Chinese Spring was studied by means of in situ ellipsometry. Most measurements were conducted in 0·01m phosphate buffer, pH 6·0, with the protein concentrations 1, 5 and 25 μg/mL. The adsorbed amount varied between 1·3 and 11·4 mg/m2, which is high considering the low protein concentrations. The concentration dependence was largest for the α-gliadins and lowest for the ω-gliadins. An intermediate concentration dependence was found for the β- and γ-gliadins, which also behaved similarly in all experiments. It was suggested that α-gliadins aggregated at the surface to a larger extent than the other gliadins when the protein concentration was 25 μg/mL. Further, it seemed as β- and γ-gliadins switched from a side-on orientation (major axis parallel to the surface) to an end-on orientation (major axis perpendicular to the surface) with increasing concentration, contrasting to the ω-gliadins that probably had side-on orientation at all concentrations. Sequential adsorption measurements indicated that α-, β-, and γ-gliadins blocked adsorption of ω-gliadins, but could replace ω-gliadins in a previously formed layer.
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