| 31. |
- Larsson, Per-Olof, et al.
(författare)
-
Direct measurement of intraparticle fluid velocity in superporous agarose beads
- 1998
-
Ingår i: Journal of Molecular Recognition. - 1099-1352. ; 11:1-6, s. 270-272
-
Tidskriftsartikel (refereegranskat)abstract
- Superporous agarose beads contain both normal diffusion pores and special, very wide superpores through which part of the chromatographic flow is transported, a situation that may greatly improve the chromatographic performance. For the first time such pore flow was measured directly by following the movement of microparticles (dyed yeast cells) through superporous beads packed in a chromatographic bed. The passage of the microparticles through the superpores and through the interstitial pores was recorded by a microscope/video camera, The video recordings were subsequently used to determine flow paths as well as the convective fluid velocities in both the superpores and the interstitial pores. The superpore fluid velocity was found to be proportional to the ratio between the squares of the respective pore diameters, which is in agreement with the Kozeny-Carman equation, Values for two-dimensional and three-dimensional tortuosity of the flow paths were measured and calculated respectively. (C) 1998 John Wiley & Sons, Ltd.
|
|
| 32. |
- Lundberg, Staffan, et al.
(författare)
-
Cutting forces at and near a cutting edge
- 1992
-
Ingår i: Better wood products through science : All-Division 5 conference "Forest Products". - Nancy : ENGREF. - 2907086030
-
Konferensbidrag (refereegranskat)
|
|
| 33. |
- Mattisson, C, et al.
(författare)
-
Diffusivity measurements using holographic laser interferometry in a cubic lipid-water phase
- 1996
-
Ingår i: Chemistry and Physics of Lipids. - 0009-3084. ; 84:1, s. 1-12
-
Tidskriftsartikel (refereegranskat)abstract
- The diffusion of glucose in a cubic lipid-water phase was studied with holographic laser interferometry. The X-ray diffraction data showed that the structure of the cubic phase could be described as a primitive cubic lattice under the experimental conditions used. The present study shows that holographic laser interferometry is suitable for determining the concentration profile due to diffusion, even for such intriguing structures as cubic lipid-water phases. The concentration profile obtained revealed that the diffusion process can be described by Fick's Second Law, and the effective diffusion coefficient was obtained by fitting a theoretical concentration profile to the experimental data. The diffusion coefficient obtained for glucose was four times smaller than the corresponding coefficient in aqueous bulk solution. The effective diffusion coefficient in the cubic phase is greater than that predicted by models developed for polymer gels.
|
|
| 34. |
- Nilsson, B, et al.
(författare)
-
Simulation of chromatographic processes using MATLAB
- 1999
-
Ingår i: Computers & Chemical Engineering. - 1873-4375. ; 23:Suppl., s. 715-718
-
Tidskriftsartikel (refereegranskat)abstract
- This paper deals with the dynamic simulation of chromatographic processes using MATLAB. Three different simulation tools are presented,; BIOPRO2, CPS toolbox and an application using of FEMLAB. Our main application is separation of biomolecules, like proteins, using different kinds of stationary phases. BIOPRO2 has a user-friendly graphical interface and is mainly based on simplified models for fast simulation. The CPS toolbox can facilitate the development of a simulation of different classes of models based on a number of simulation methods. FEMLAB is a general modelling and simulation system based on finite element method.
|
|
| 35. |
- Westrin, BA, et al.
(författare)
-
A diaphragm diffusion cell applied to ethanol diffusion in agarose gel: A reproducibility study
- 1991
-
Ingår i: Biotechnology Techniques. - 0951-208X. ; 5:4, s. 303-306
-
Tidskriftsartikel (refereegranskat)abstract
- The effective diffusion coefficient of ethanol in a 4 %(w/v) agarose gel at 25-degrees-C was measured using a diaphragm diffusion cell. The reproducibility was very good; a standard deviation of only 2% was obtained. The mean value (9.5 x 10(-6) cm2/s) agreed well with available theory and previous investigations.
|
|
| 36. |
- Westrin, BA, et al.
(författare)
-
Diffusion in gels containing immobilized cells - A critical review
- 1991
-
Ingår i: Biotechnology and Bioengineering. - : Wiley. - 1097-0290 .- 0006-3592. ; 38:5, s. 439-446
-
Tidskriftsartikel (refereegranskat)abstract
- Eleven experimental investigations of diffusion in gels containing immobilized cells are reviewed. The experimental data, which quantitatively express the diffusion coefficient as a function of the cell concentration, are compared with a number of well-known equations developed for mass transfer in heterogeneous media. Based on this comparison, a procedure for the theoretical prediction of effective diffusion coefficients in cell-containing gels is recommended.
|
|
| 37. |
- Westrin, BA, et al.
(författare)
-
Diffusion measurement in gels
- 1994
-
Ingår i: Journal of Controlled Release. - : Elsevier BV. - 1873-4995 .- 0168-3659. ; 30:3, s. 189-199
-
Forskningsöversikt (refereegranskat)abstract
- Methods for measuring diffusion coefficients in gels are reviewed, and their capacities, limitations and requirements are briefly discussed. With four of these methods, i.e., the diaphragm cell, uptake/release from beads, holographic laser interferometry and nuclear magnetic resonance (FT-PGSE), a comparison is made with regard to accuracy and precision. The comparison is based on a number of studies in which the diffusion coefficient of ethanol in agarose gel has been measured. It is concluded that the diaphragm cell and nuclear magnetic resonance (FT-PGSE) are very accurate and precise.
|
|
| 38. |
- Zacchi, Guido, et al.
(författare)
-
Economic evaluation of preconcentration in production of ethanol from dilute sugar solutions
- 1989
-
Ingår i: Biotechnology and Bioengineering. - : Wiley. - 1097-0290 .- 0006-3592. ; 34:2, s. 223-233
-
Tidskriftsartikel (refereegranskat)abstract
- The economic feasibility of preconcentrating dilute sugar solutions prior to fermentation is investigated. Two methods, evaporation and reverse osmosis, are compared. A computer program to determine the optimal preconcentration conditions for glucose solutions of 1.5–16 wt% has been developed. It was used to compute the fractional cost for labor and maintenance, preconcentration, fermentation, and distillation. Preconcentration with evaporation resulted in a higher total cost, compared with no preconcentration, for all cases studied, although a six-effect unit was used. Reverse osmosis was found to be economically feasible for preconcentration to about 5–10 wt % depending on the concentration of the feed.
|
|
