| 1. |
- Nisslert, R., et al.
(författare)
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Identification of the three-dimensional gel microstructure from transmission electron micrographs
- 2007
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Ingår i: Journal of Microscopy. - : Wiley. - 0022-2720 .- 1365-2818. ; 225:1, s. 42298-
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Tidskriftsartikel (refereegranskat)abstract
- Mass transport in gels depends crucially on local properties of the gel network. We propose a method for identifying the three-dimensional (3D) gel microstructure from statistical information in transmission electron micrographs. The gel strand network is modelled as a random graph with nodes and edges (branches). The distribution of edge length, the number of edges at nodes and the angles between edges at a node are estimated from transmission electron micrographs by image analysis methods. The 3D network is simulated by Markov chain Monte Carlo, with a probability function based on the statistical information found from the micrographs. The micrographs are projections of stained gel strands in slices, and we derive a formula for estimating the thickness of the stained gel slice based on the total projected gel strand length and the number of times that gel strands enter or exit the slice. © 2007 The Authors.
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| 2. |
- Bergstrand, A., et al.
(författare)
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Aggregation behavior and size of lipopolysaccharide from Escherichia coli O55:B5
- 2006
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Ingår i: Colloids and Surfaces B. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 53:1, s. 42261-
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic light scattering, steady-state fluorescence, NMR diffusometry and cryo-TEM have been used to gain more insight into the aggregation behaviour of LPS from Escherichia coli O55:B5. Knowledge of this behaviour of the amphiphilic LPS molecule is in many cases of importance for the design of experiments and interpretation of results when using LPS in solution. The aim of this work was to study the aggregation and determine the aggregate size of E. coli O55:B5. The mean hydrodynamic radius of the LPS aggregates was determined by NMR diffusometry and dynamic light scattering to 14 and 26 nm, respectively. The cryo-TEM technique revealed predominately spherical aggregates of 9-19 nm. We wish to report 10 ?g/ml as the aggregation start for LPS E. coli O55:B5 in PBS buffer, pH 7.2. We suggest that the aggregation is a continuous process that starts at 10 ?g/ml and proceeds up to 300 ?g/ml. © 2006.
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| 3. |
- Folmer, B. M., et al.
(författare)
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Structure and dynamics of micelles and cubic phase structures with ethoxylated phytosterol surfactant in water
- 2008
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 24:13, s. 6441-6446
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Tidskriftsartikel (refereegranskat)abstract
- The self-assembly of a sterol ethoxylate surfactant with 30 oxyethylene units in water was studied by 1 H NMR self-diffusion measurements in a wide concentration range in the micellar region (0-25 wt %). The data showed that the surfactant aggregates do not interact by hard sphere interactions but rather a strong concentration dependence of the diffusion coefficient was noted which was explained by polymer scaling theory. In the cubic phase (30-65 wt %), the self-diffusion data from water, from surfactant, and from free polyoxyethylene suggest spherical micelles, although water diffusion was much restricted due to binding to the surfactant headgroup. From X-ray measurements in the cubic phase, the unit cell size was calculated, and together with surfactant self-diffusion measurements the exchange dynamics between free and aggregated surfactant was obtained. © 2008 American Chemical Society.
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| 4. |
- Loren, Niklas, et al.
(författare)
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Water mobility in heterogeneous emulsions determined by a new combination of confocal laser scanning microscopy, image analysis, nuclear magnetic resonance diffusometry, and finite element method simulation
- 2005
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 122:2, s. 24716-
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Tidskriftsartikel (refereegranskat)abstract
- Nuclear magnetic resonance (NMR) diffusometry and confocal laser scanning microscopy (CLSM) were combined in a quantitative way in finite element calculations of water propagation in CLSM images obtained from a very heterogeneous emulsion. The propagators calculated on the basis of microstructure were Fourier transformed and subsequently compared with the echo decays obtained by the NMR diffusometry method. The results showed very good agreement between microstructure based calculations and experiments, indicating that the short gradient pulse approximation in the NMR diffusometry experiment holds for a certain q range. Furthermore, the CLSM was able to achieve a relevant two-dimensional microstructure although some discrepancy at low q values was noted. This effect is attributed to the inherent three-dimensional connectivity between the water domains in this type of structures, making the calculations slightly underestimate the water diffusion at longer distances. © 2005 American Institute of Physics.
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