| 1. |
- Elofsson, Ulla, et al.
(författare)
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Adsorption studies of interaction between water-extractable nonstarch polysaccharides and prolamins in cereals
- 2000
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Ingår i: Cereal Chemistry. - 0009-0352. ; 77:5, s. 679-684
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Tidskriftsartikel (refereegranskat)abstract
- Adsorption of cereal storage protein and nonstarch polysaccharides onto methylated silica surfaces, as measured by ellipsometry, was used to study possible interactions between those components. All fractions, rye secalin, wheat gliadin, rye arabinoxylan, and wheat arabinogalactan peptide, were surface- oxylan and wheat arabinogalactan peptide on top of gliadin and secalin, respectively, indicated that an interaction occurred. As ionic strength and pH influenced both the adsorption and the interaction of the components studied, these phenomena are believed to be of electrostatic nature.
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| 2. |
- Elfstrand, Lidia, et al.
(författare)
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Molecular characterization of native and processed waxy maize starch in relation to the recrystallization behavior of model systems and starch microspheres
- 2004
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Ingår i: Starch: from polysaccharides to granules, simple and mixture gels. - 1594540136 ; , s. 203-214
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Konferensbidrag (refereegranskat)abstract
- The recrystallization behavior of five starch materials, native waxy maize starch, and starches modified by acid hydrolysis and mechanical treatments, were investigated by DSC (differential scanning calorimetry) and electron microscopy (SEM). The starches were known to vary significantly in molecular weights but not in the degree of branching. Microspheres manufactured from one of these starches were also studied by both methods. The acid hydrolysis did not produce major breakdown of the granular structure of starch as evidenced by SEK or the amount of crystalline amylopectin, as measured by DSC, but broadened the melting temperature range compared to native starch. No crystallinity could be detected in the material after the mechanical treatment, which also seemed to destroy the granular structure. The crystallinity was regained after the material had been dispersed in 70 % water during heating followed by 20 hour storage at 6 degreesC, called as one-step temperature treatment, while within the set of samples stored at 20 degreesC only one of the starches showed presence of regained crystallinity. No significant differences could be observed with regard to endothermic transition temperature or temperature range between the samples of native starch and both the acid hydrolysed and the mechanically treated samples, as measured by DSC. Apparently from the enthalpy values and presence of endothermic transitions, amylopectin molecular weight and modification method seemed to affect the amount of starch crystallites formed and/or the recrystallization rates, with acid hydrolysed samples showing higher enthalpy values compared to mechanically treated samples. The same conclusion, as for one-step temperature treatment of starch materials, was done for a two-steps temperature treatment of the starch materials, regarding transitions temperatures within the set of experiment. The two-steps treatment with nucleation at a lower temperature and crystal growth and perfection at a higher temperature resulted in an increase in the melting temperatures and narrower melting intervals. This treatment is also similar to the actual microsphere manufacture process. DSC thermogram of placebo starch microspheres revealed that the crystallites, obtained in production process of the microspheres, melted at temperatures similar to melting temperatures of the starch dispersion after 14 days/6 degreesC- storage but showed higher enthalpy value and smaller melting interval.
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| 3. |
- Elfstrand, Lidia, et al.
(författare)
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Recrystallisation behaviour of native and processed waxy maize starch in relation to the molecular characteristics
- 2004
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617. ; 57:4, s. 389-400
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Tidskriftsartikel (refereegranskat)abstract
- Molecular characteristics were determined for native waxy maize starch and maize starch modified in different way (by mechanical treatment or/and acid hydrolysis). Recrystallisation behaviour was studied. Methods used in this study were MALLS, HPAEC-PAD, NMR, DSC, SEM, light microscopy. Five starch materials were subjected to storage under the same conditions in the presence of water (70 w/w%). Molecular weight, radius of gyration, initial crystallinity, and degree of polymerisation, degree of branching, chain length distribution profiles, were related to nucleation rate during the recrystallisation process, rate of recrystallisation, thermal stability and amount of obtained crystallinity. This allowed the following connections between the molecular characteristics and kinetic of recrystallisation to be proposed: Amylopectin molecular weight appeared to affect the number of starch crystallites formed and amount of crystallinity but not the stability of the rebuilt crystallites. The stability of rebuilt crystallites can be controlled by degree of polymerization, degree of branching and unit chain length distribution, characteristics which were similar for the starches. A mixture of two starches, with and without crystalline structure in initial state but with molecular weight in same range, were stored and scanned in order to understand possible cocrystallisation effects. (C) 2004 Elsevier Ltd. All rights reserved.
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| 4. |
- Ali, Abdullah, 1985-, et al.
(författare)
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Relationship between sensorial and physical characteristics of topical creams : A comparative study on effects of excipients
- 2022
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Ingår i: International Journal of Pharmaceutics. - : Elsevier B.V.. - 0378-5173 .- 1873-3476. ; 613
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Tidskriftsartikel (refereegranskat)abstract
- Rising consumer demands for safer, more natural, and sustainable topical products have led to increased interest in finding alternative excipients, while retaining functionality and cosmetic appeal. Particle-stabilized Pickering creams have emerged as possible alternatives to replace traditional surfactant-stabilized creams and are thus one of the focuses in this study. The aim of this paper was to study relationships between sensorial characteristics and physical properties to understand how different excipients affect these aspects, comparing one starch particle–stabilized and three surfactant-stabilized formulations. A human panel was used to evaluate sensorial perception, while physical properties were deduced by rheology and tactile friction, together with in vivo and ex vivo skin hydration measurements. The results show that sensorial attributes related to the application phase can be predicted with rheology, while afterfeel attributes can be predicted with tactile friction studies. Differences in rheological and sensory properties among surfactant-based creams could mainly be attributed to the type of emollients used, presence of thickeners and surfactant composition. Differences between surfactant-based creams and a Pickering cream were more evident in relation to the afterfeel perception. Presence of starch particles in the residual film on skin results in high tactile friction and low perception of residual coating, stickiness, greasiness, and slipperiness in sensorial afterfeel. © 2021 The Authors
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| 5. |
- Ali, Abdullah, 1985-, et al.
(författare)
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Tactile friction of topical creams and emulsions : Friction measurements on excised skin and VitroSkin® using ForceBoard™
- 2022
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Ingår i: International Journal of Pharmaceutics. - : Elsevier B.V.. - 0378-5173 .- 1873-3476. ; 615
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Tidskriftsartikel (refereegranskat)abstract
- Tactile perception can be investigated through ex vivo friction measurements using a so–called ForceBoard™, providing objective assessments and savings in time and money, compared to a subjective human panel. In this work we aim to compare excised skin versus VitroSkin® as model substrates for tactile friction measurements. A further aim is to detect possible differences between traditional surfactant-based creams, and a particle-stabilized (Pickering) cream and investigate how the different substrates affect the results obtained. It was found that the difference in tactile friction between excised skin and VitroSkin® was small on untreated substrates. When topical creams were applied, the same trends were observed for both substrates, although the frictional variation over time relates to the difference in surface structure between the two substrates. The results also confirmed that there is a difference between starch-based Pickering formulations and surfactant-based creams after application, indicating that the latter is greasier than Pickering cream. It was also shown that the tactile friction of Pickering emulsions was consistently high even with high amounts of oil, indicating a non-greasy, and non-sticky formulation. The characteristics of starch-stabilized Pickering formulations make them promising candidates in the development of surfactant-free topical formulations with unique tactile properties. © 2022 The Authors
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| 6. |
- Billsten, P, et al.
(författare)
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Adsorption of human carbonic anhydrase II onto silicon oxides surfaces : The effects of truncation in the N-terminal region
- 1998
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Ingår i: The Colloid Science of Lipids New Paradigms for Self-Assembly in Science and Technology. - 1435-1536 .- 0340-255X. - 9783798511125 - 9783798516557 ; 108, s. 161-165
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Konferensbidrag (refereegranskat)abstract
- The adsorption of human carbonic anhydrase II pseudo-wild type (HCAIIpwt) and an N-terminally truncated version thereof onto silica surfaces were studied. The amount adsorbed and the adsorption kinetics were measured using in situ ellipsometry. A substantial difference was seen between the two proteins. The adsorbed amount of the truncated version (2.53 mg/m2) indicates an end-on orientation, while the HCAIIpwt seems to adsorb side-on (1.84 mg/m2). It is suggested that the orientation effects arise from the truncation. The truncation is known to unfold the two most N-terminal helical segments, which could inhibit adsorption with the N-terminal region facing the surface, due to steric repulsion.
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| 7. |
- Gekas, Vassilis, et al.
(författare)
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Contact angles of ultrafiltration membranes and their possible correlation to membrane performance
- 1992
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Ingår i: Journal of Membrane Science. - 0376-7388. ; 72:3, s. 293-302
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Tidskriftsartikel (refereegranskat)abstract
- The captive bubble method was used to describe the wetting characteristics of a number of commercial ultrafiltration (UF) membranes. The membranes belonged to one of two homologous (same material, different cut-off) series made by the same manufacturer. One series was made of polysulphone and the other one of cellulose triacetate. The porosimetric characteristics of the membranes have also been measured. The combined data were used to explain the fouling behaviour of the membranes upon ultrafiltration of solutions containing dextran, whey protein concentrate and silicate sols. The cellulose triacetate series is characterized by lower receding contact angle and smaller contact angle hysteresis and shows better flux behaviour (permeate flux during UF and pure water flux recovery at the end of UF) than the polysulphone series. Within the same series the mean permeability pore size shows a better correlation with membrane flux behaviour than with contact angle hysteresis.
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| 8. |
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| 9. |
- Jansson, Magnus, et al.
(författare)
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Efficient Implementation of a Submodel for Composite Materials to be Combined with the FDTD-Algorithm
- 1994
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Ingår i: IEEE Transactions on Magnetics. - : IEEE Magnetics Society. - 0018-9464 .- 1941-0069. ; 30:5, s. 3188-3191
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Tidskriftsartikel (refereegranskat)abstract
- A submodel to be used for thin sheets of semiconducting materials in combination with the finite difference time domain algorithm for solving Maxwell's equations is derived. Emphasis is concentrated on accomplishing an efficient and robust algorithm. Stability properties of the combined model are also investigated
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| 10. |
- McGuire, J, et al.
(författare)
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Comparative Adsorption Studies with Synthetic, Structural Stability and Charge Mutants of Bacteriophage T4 Lysozyme.
- 1995
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Ingår i: Proteins at Interfaces II. - Washington, DC : American Chemical Society. - 9780841233041 - 9780841215276 ; 602, s. 52-65
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Bokkapitel (refereegranskat)abstract
- We have purified wild type, three structural stability mutants and four charge mutants of bacteriophage T4 lysozyme from E. coli strains harboring desired expression vectors. Structural stability mutants were produced by substitution of the isoleucine at amino acid position three, yielding a set of proteins with stabilities ranging from 1.2 kcal/mol greater, to 2.8 kcal/mol less, than that of the wild type. Charge mutants were produced by replacement of positively charged lysine residues with glutamic acid, yielding a set of molecules with formal charges ranging from +5 to +9 units. Adsorption kinetic data, along with the dodecyltrimethylammonium bromide-mediated elutability of each protein, has been monitored with in situ ellipsometry at hydrophobic and hydrophilic silica surfaces. A simple mechanism that allows adsorbing protein to adopt one of two states, each associated with a different resistance to elution and a different interfacial area occupied per molecule, has been used to assist interpretation of the adsorption data. Conditions implicit in the model have been used to estimate the fraction of molecules present on the surface just prior to surfactant addition that had adopted the more resistant state, and this fraction has been observed to correlate positively with resistance to elution. For the stability mutants, these properties were clearly related to protein stability as well. Concerning the charge mutants, results have not been clearly explainable in terms of protein net charge, but rather in terms of the probable influence of the location of each substitution relative to other mobile, solvent-exposed, charged side chains of the molecule.
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