| 271. |
- Svensson, Nils-Olof
(författare)
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Salinity dynamics in the Baltic Sea linked to anthropogenic foraging behavior during the Holocene : S03-03
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- S03-03 Salinity dynamics in the Baltic Sea linked to anthropogenic foraging behavior during the Holocene Nils-Olof Svensson1 1 Department of Science and Mathematics, Kristianstad University, 291 88 Kristianstad, Sweden Email: nils-olof.svensson@hkr.se Former Lake Vesan is situated in the province of Blekinge in South Sweden. Before drainage and cultivation in 1927 forming a shallow lake surrounded by Phragmites reeds and connected to the Baltic Sea through a c. 3 km long outlet river. This region has a well studied sea-level history showing that here global sea-level change since the last glacial is surprisingly well balanced by the glacioisostatic uplift. The result is that the studied basin for the last 10 000 years repeatedly shifted between being a lake or a bay of the Baltic. For most of this time it´s shores were important for fishing and hunting as well as for dwelling places. Later also activities like farming and burials left their traces. In this archeologically unusually rich environment it was decided to build a highway initiating extensive archaeological and paleoecological studies of which this study is a part. In the project my role is to study a more than 5 m long sediment core for microfossils and physical parameters to reveal the environmental history of the basin and its surroundings. Pollen and algae are the primary subjects here and analysis is still ongoing. Diatoms give information both on nutrient levels and salinity in the water, important both for revealing local sea-level history and productivity. This information may allow discussing changes in abundance and species composition of the limnic and marine fauna foraged by man. The sediments from early Holocene are unfortunately missing due to a hiatus. This is related to the wave action during the early part of the transgressive Ancylus stage. The younger sediments shows initially rather low but gradually increasing organic content, interpreted as low organic production during later part of the Ancylus Lake stage, and then increasing productivity as salinity in the Baltic increased due to the sea level rise in the areas of the Baltic Sea inlets. Further up in the sediments a color change and increase in organic content coincides with major changes in the algae flora, the green algae Pediastrum decreases at the same time as dinoflagellate resting spores becomes frequent. The diatom flora also changes distinctly, indicating higher salinity. The horizon is radiocarbon dated to 5900 BC (7900 BP) and coincides in time rather well with the shift to the fully marine part of the Littorina Sea stage.
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| 276. |
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| 277. |
- 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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| 278. |
- 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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| 279. |
- 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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| 280. |
- 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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