| 281. |
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| 282. |
- Svensson, Olof, et al.
(författare)
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Adsorption of beta-casein to hydrophilic silica surfaces. Effect of pH and electrolyte
- 2014
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Ingår i: Food Hydrocolloids. - : Elsevier BV. - 0268-005X. ; 36, s. 332-338
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Tidskriftsartikel (refereegranskat)abstract
- Adsorption of beta-casein to hydrophilic silica surfaces has been studied as an effect of pH and electrolyte, in the latter concentration, valency, and specificity (calcium or magnesium) have been considered. The used protein concentration has been an order of magnitude below the critical aggregation concentration, which implies that the protein is in monomeric form. By varying the salt concentration, the pH, and the concentration of divalent ions as calcium and magnesium, it is clearly shown that electrostatic interactions are of importance for adsorption of beta-casein to silica surfaces and tunes the adsorbed amount and saturation of the surface. Our results show that there is counterbalance between: (i) electrostatic repulsion between the surface and the protein, (ii) electrostatic attraction between positively charged amino acids in the protein and the surface, and (iii) electrostatic repulsion and excluded volumes between adsorbed proteins at the surface, and that the positively charged amino acids serve as anchoring points. (C) 2013 Elsevier Ltd. All rights reserved.
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| 283. |
- Svensson, Olof, et al.
(författare)
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Adsorption of delmopinol at the solid/liquid interface - the role of the acid-base equilibrium
- 2010
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier Inc.. - 0021-9797 .- 1095-7103. ; 350:1, s. 275-281
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Tidskriftsartikel (refereegranskat)abstract
- Delmopinol is a tertiary amine surfactant that is used to counteract dental plaque formation. As it is of interest to understand the interfacial behavior from both fundamental and applied perspectives the adsorption of delmopinol to model surfaces was investigated. Adsorption on Teflon, titanium and stainless steel was studied by radioactive labeling and adsorption on silica was studied by quartz crystal microbalance (QCM), ellipsometry and particle electrophoresis. It was shown that the adsorption of delmopinol was complex and strongly influenced by pH and concentration. Pronounced peak values were detected in the adsorption curves (adsorbed amount versus concentration) exceeding the expected value for a bilayer type of structure. To account for this behavior two surface active component were assumed to be present. Accordingly, the high amounts result from the deposition of the component with lower solubility and the decrease at the critical micelle concentration can be explained by solubilization of this component. Based on data from several experimental methods and the pH dependence of the effect we propose an explanation in which the protonated and non-protonated forms of delmopinol represent the two components. However, it cannot be excluded that the component with the lower solubility could be a compound chemically different from delmopinol in the sample.
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| 284. |
- Svensson, Olof, et al.
(författare)
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Adsorption of serum albumin on silica : The influence of surface cleaning procedures
- 2010
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier Inc.. - 0021-9797 .- 1095-7103. ; 344:1, s. 44-47
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the investigation was to study how different surface cleaning procedures affect the subsequent adsorption of bovine serum albumin (BSA) on silica. Ellipsometry was used to monitor the adsorbed amount and thickness of the protein films in situ at physiological buffer conditions. Plasma treatment was found to effectively reduce the amount of BSA on silica and on surfaces cleaned with hydrogen peroxide solutions (RCA method) adsorption was essentially absent. On clean silica surfaces the ellipsometric data furthermore suggest that a depletion zone is present at the surface where the BSA concentration is lower than in the bulk solution. Additional experiments showed that calcium did not promote the adsorption of BSA and that the adsorption of human serum albumin (HSA) is essentially absent on clean silica surfaces in agreement with the results obtained for BSA. The presented work contributes to the general understanding of protein adsorption as well as provides information on how to control serum albumin adsorption on silica based biomedical devices.
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| 285. |
- Svensson, Olof, et al.
(författare)
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An evaluation of 2D-wavelet filters for estimation of differences in textures of pharmaceutical tablets
- 2006
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Ingår i: Chemometrics and Intelligent Laboratory Systems. - : Elsevier BV. - 0169-7439 .- 1873-3239. ; 84:1-2, s. 3-8
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Tidskriftsartikel (refereegranskat)abstract
- In chemical imaging spectra are acquired over a surface with one spectrum for each pixel of the image. The obtained spectra usually carry a mixture of chemical and physical information. One may view the properties that vary over the image, the mean spectral magnitude from separate wavelength intervals, or better, PCA scores may be shown as images.In this way a multitude of images are compressed to a few images that in the PCA case are representative for the main variation in the sample images. These images may be viewed manually and deductions as to e.g. differences in homogeneity can be made. At an increased rate of samples, the observer will have difficulties coping with the repetitive work and different observers will most likely have slightly different interpretations. In order to automate the process of estimation of e.g. homogeneity and particle density, image filters can be used to calculate a small set of texture descriptors for each image. Calculations based on the 2D versions of the discrete wavelet transform (DWT) using Daubechies 14 and the dual tree complex wavelet transform (DT-CWT) using near-symmetric 13, 19 tap filters in combination with q-shift 14, 14 tap filters were evaluated for this purpose.The aim with this work is to evaluate texture descriptors based on a combination of 2D-wavelet filters and energy, i.e. l(1)-norm, calculations for each wavelet scale. These descriptors are then used as observations for overview in e.g. PCA. In this way the texture differences can be ranked by ordinary use of PCA or PLS.This method is tested on multivariate near infrared images of pharmaceutical tablets. Score images are selected to represent variations of the aggregate density and sizes in the compressed tablets. Images are shifted and rotated to compare shift and rotational independence of the texture descriptors.
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| 286. |
- Svensson, Olof, et al.
(författare)
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Antibody–antigen interaction on polystyrene : An in situ ellipsometric study
- 2012
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 368:1, s. 533-539
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this investigation was to monitor the adsorption of antibodies to polystyrene surfaces using ellipsometry. Commercial polystyrene slides used for solid state diagnostics were selected as substrates and the adsorption of three different antibodies (human IgG, bovine IgG and goat anti-human IgG) were evaluated. Based on theoretical models describing the ellipsometric data, it was concluded that the adsorption of antibodies should result in layers that are sufficiently thick to be able to monitor the adsorption in terms of adsorbed amount and thickness of the layer with a reasonable precision. The experimental results confirmed this assumption and values of 2.0–2.3 mg/m2 were detected for the adsorbed amount with a corresponding thickness of 10–16 nm. It was furthermore found that the antibodies bound irreversibly with respect to rinsing with protein-free solutions. In additional experiments, the consecutive incubation of human IgG and anti-human IgG was investigated. These results showed that, on average, approximately half of the surface immobilized anti-human IgG molecules are capable of binding to human IgG during its incubation. From the consecutive binding experiments it could also be concluded that antibodies present in the polyclonal anti-human IgG preparation were capable of binding to around four different epitopes on the human IgG. A final set of experiments addressed the stability of adsorbed human IgG layers with respect to drying and incubation with surfactant. The results revealed that the adsorbed antibody layer is relatively resistant to these treatments.
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| 287. |
- Svensson, Olof, et al.
(författare)
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Associations Between Conduct Disorder, Neurodevelopmental Problems and Psychopathic Personality Traits in a Swedish Twin Youth Population
- 2018
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Ingår i: Journal of Psychopathology and Behavioral Assessment. - : Springer Science and Business Media LLC. - 0882-2689 .- 1573-3505. ; 40:4, s. 586-592
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Tidskriftsartikel (refereegranskat)abstract
- Previous research has found a complex relationship between psychopathic traits, neurodevelopmental problems (NDPs), and conduct disorder (CD) in children. This study explores associations between psychopathic traits, assessed with the Child Problematic Traits Inventory—Short Version (CPTI-SV), and CD in children with and without coexisting NDPs (i.e., attention deficit/hyperactivity disorder [ADHD] and autism spectrum disorder [ASD]) in a community-based sample of Swedish twins (n = 8762). Findings indicate weak to moderately strong correlations between psychopathic traits and CD, ADHD, and ASD, respectively. Furthermore, in univariable analyses, both psychopathic traits and NDPs displayed significant positive associations with being screened positive for CD, though only the grandiose-deceitful dimension of CPTI-SV and the ADHD domain concentration and attention deficits remained significantly associated with CD in a multivariable regression model. The results are relevant to screening and assessment in child and youth psychiatry, as a grandiose and deceitful interpersonal style may also be a valid sign of children at risk of developing CD.
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| 288. |
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| 289. |
- Svensson, Olof, et al.
(författare)
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Experts' decision-making processes in Swedish forensic psychiatric investigations: A case vignette study.
- 2024
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Ingår i: International journal of law and psychiatry. - 1873-6386. ; 92
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Tidskriftsartikel (refereegranskat)abstract
- It has previously been demonstrated that decisions made by forensic experts can suffer from issues with both bias and poor reliability. The outcome of Swedish forensic psychiatric investigations can have a major impact on the courts' choice of sanction for a mentally disordered offender. These investigations are performed by multi-professional teams of experts, where each expert is obliged to state their opinion on whether the client has a severe mental disorder (SMD) or not. In the present study, a case vignette design was used to simulate the decision-making process of forensic psychiatric investigations. Of the 73 Swedish experts working with forensic psychiatric investigations, a total of 27 (37%) participated in the study. The results showed that the Swedish experts formulated multiple diagnostic hypotheses about cases throughout the process and revised these hypotheses when presented with new information. There was substantial variation between the experts in which hypotheses were seen as most relevant. While the experts grew more certain of their opinions on SMD during the simulated investigation, there was considerable variation in their opinions both throughout and at the end of the process. Although low statistical power and the sample not being randomized limit generalizations, the results indicate no idiosyncratic patterns in the decision-making processes of Swedish experts or signs of confirmation bias. If used properly, the variation in both process and outcome could be used to safeguard and possibly increase the reliability and validity of the final decision of Swedish forensic psychiatric investigations.
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| 290. |
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