Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Adsorption 3 (1997), S. 41-54 
    ISSN: 1572-8757
    Keywords: liquid crystals ; moving bed system ; simulation ; purification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract We investigate convective-diffusive transport of a solute through a medium with properties that can be externally modulated in space and time. In particular, we focus on the effect of a front—a sharp transition in the convective velocity (v) and diffusivity (D)—on the evolution of the solute concentration profile. Numerical results show that by suitably moving the front during the process an anti-dispersive effect may be realized, in which the solute accumulates in a thin region close to the moving boundary. Our computations take into account the realistic case of a front having a small but finite thickness, and we find that the width of the concentration profile scales as $$\left( {1/\sqrt {Pe} } \right)$$ , where Pe is the Péclet number. This is in sharp contrast to the 1/Pe scaling observed for the ideal case of the singular front assumed in previous work. The effect of the thickness of the front and the magnitude of the drop inv andD, on the solute concentration profile has also been studied. These results are relevant in order to implement and optimize protocols that apply an externally controlled moving boundary for the purpose of separation. We also present experimental results characterizing solute transport across a stationary front, expected to display many features needed in a model for moving fronts. The concentration profile of electrophoretically mobile BSA-FITC within the boundary layer at a polyacrylamde gel-buffer interface were visualized by epifluorescence microscopy. Measured boundary layer thickness exceeded that predicted for even a finite interface, indicating that the length scale associated with real boundaries is relevant to the modeling problem.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 631-644 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Electrophoresis of a solute through a column in which its transport is governed by the convection - diffusion equation is described. Approximate solutions to the convection - diffusion equation in the limit of small diffusion are developed using perturbation methods. The diffusion coefficient and velocity are assumed to be functions of space and time such that both undergo a sudden change from one constant value to another within a thin transition zone that itself translates with a constant velocity. Two cases are considered: (1) the thickness ∊f of the transition zone is negligible compared to the diffusional length scale, so the zone may be treated as a singular boundary across which the diffusion constant and velocity suffer discontinuous changes; (2) the transition zone is considerably wider than the diffusional length scale, so the diffusion coefficient and velocity, although sharply varying, are smooth functions of position and time. A systematic perturbation expansion of the concentration distribution is presented for case 1 in terms of the small parameter ∊ = 1/Pe. A lowest order approximation is given for case 2. A suitably configured system analyzed here can lead to progressive accumulation, or focusing, of the transported solute. The degree of focusing in case 1 scales with ∊-1, whereas in case 2 it scales with (∊f∊)-1/2, and thus increases much more weakly with increasing Pe. A separation based on this concept requires development of materials and devices that allow dynamic tuning of the mass-transport properties of a medium. This would make it possible to achieve progressive focusing and separation of solutes, such as proteins and DNA fragments, in electrophoretic media with an unprecedented degree of control.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 1366-1368 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...