Bibliothek

X
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • Chemistry  (11)
  • Valley airflow  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Transition Regimes in Valley Airflows (1999)
    Springer
    Boundary layer meteorology 91 (1999), S. 385-411 
    Details
    ISSN: 1573-1472
    Schlagwort(e): Boundary layer ; Slope airflow ; Numerical model ; Transition ; Valley airflow
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract A three-dimensional, non-hydrostatic model was used to examine the dynamical characteristics of morning and evening transition periods in the atmosphere over four idealised valleys. The simulations provided detailed structure over full diurnal cycles of the valley-wind system. An essentially two-dimensional simulation (Case 1) clearly showed valley-side slope flows, driven by pressure gradients and modulated by vertical diffusion and Coriolis effects. The rotation of the wind was clockwise on both valley sides, contrary to most observations in nature. Three-dimensional simulations (Cases 2–4) rectified this feature and that for Case 4 satisfactorily modelled the valley-plain wind system throughout the diurnal cycle. Three types of transition were identified with the aid of different tools: hodographs; space-time evolution of the wind fields; and the evolution of the forcing terms in the momentum and temperature equations. Whichever type or Case was considered, the evening transition was longer than the morning one and the along-valley transition followed the along-slope one. In Cases 1 and 4 the evening transition started up to 2 h before sunset and the morning transition started up to 2.5 h after sunrise. In the three-dimensional cases the evening transition began at about 1700 and ended at about 2400, starting at the bottom of the valley and propagating up both valley sides, but at different speeds. It also started at the ground and propagated vertically. The morning transition began at about 0900 and ended at about 1100, also starting at the bottom of the valley and propagating both vertically and up the valley sides, albeit with different regimes on the two sides. The along-valley transition lagged that on the slopes by about 1.5 h. In Case 1 the forcing terms were dominated by the pressure gradient and the vertical diffusion, with the Coriolis effects introducing an along-valley component to the slope flows. The three dimensional cases were more complex, with not only the addition of the effects of advection and horizontal diffusion but also more temporal variation of more of the forcings than in Case 1.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1001846005338
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 2
    Digitale Medien
    Digitale Medien
    Characteristics of unbuffered gel-immobilized urease particles. I. Internal pH (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 19 (1977), S. 1037-1063 
    Details
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The overall rate of reaction of a gel-immobilized urease particle necessarily depends upon the hydrogen ion concentrations within the particle. When the particle is unbuffered, the internal hydrogen ion concentrations are a consequence of the local rates of reaction and the rate of egress of the products of hydrolysis. A simple apparatus has been devised which allows a fairly rapid determination of the hydrogen ion concentration in the center of a particle for any given size, enzyme concentration, substrate concentration, and external pH. The products of urea hydrolysis are self-buffering in the region of pH 8.83 and for an external pH less than the self-buffering pH, the pH within the particle is increased because of the reaction. When the external pH is greater than the self-buffering pH, the converse occurs. The pH at the center of the particle approaches the self-buffering pH with an increase in particle size and enzyme concentration. The external pH necessarily differs in effect when above or below the self-buffering pH. An increase in the external substrate concentration has a limited effect, simply rendering the local rates of reaction to be of zero order. The center-line pH and therefore all internal hydrogen ion concentrations depend upon the parameter \documentclass{article}\pagestyle{empty}\begin{document}$ L\sqrt {\rho _e} $\end{document} and the external pH. Differences between the external and center-line pH values of the order of units are unexceptional. The implications of the internal pH profiles on the local and overall rates of reaction are explored.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260190707
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 3
    Digitale Medien
    Digitale Medien
    The production of cellulase in a spouted bed fermentor using cells immobilized in biomass support particles (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 41-50 
    Details
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Continuous cellulase production by Trichoderma viride QM 9123, immobilized in 6 mm diameter, spherical, stainless steel biomass support particles, has been achieved using a medium containing glucose as the main carbon source. Experiments were carried out in a 10-L spouted bed fermentor. In this type of reactor-recycled broth is used to create a jet at the base of a bed of particles, causing the particles to spout and circulate. During the circulation, particles pass through a region of high shear near the jet inlet. This effectively prevents a buildup of excess biomass and thus enables steady-state conditions to be achieved during continuous operation. Continuous production of cellulase was achieved at significantly higher yield and productivity than in conventional systems. At a dilution rate of 0.15 h-1 (nominal washout rate for freely suspended cells is 0.012 h-1), the yield of cellulase on glucose was 31% higher than that measured during batch operation, while the volumetric productivity (31.5 FPA U/L· h) was 53% greater than in the batch system. The specific cellulase productivity of the immobilized cells was more than 3 times that of freely suspended cells, showing that diffusional limitations can be beneficial. This offers significant opportunity for the further development of biomass support particles and associated bioreactors.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260280107
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 4
    Digitale Medien
    Digitale Medien
    Characteristics of unbuffered gel-immobilized urease particles. II. Overall rate of reaction (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 19 (1977), S. 1065-1086 
    Details
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The overall rates of reaction of unbuffered gel-immobilized urease particles have been investigated with the aid of a packed-bed differential recycle reactor. Both substrate and enzyme concentrations have received attention. Cylindrical gel particles contained within impermeable tubelets were used to provide the physical strength necessary for the packed-bed arrangement and a one dimensional diffusion path to aid understanding of the complex interactions between substrate and product diffusion, and their effect on the reactions taking place. The experimental data have been interpreted with the aid of an enzyme rate equation (ERE) which relates the free solution characteristics of the enzyme to the conditions within a diffusion limited particle. The internal hydrogen ion profiles have been accommodated by a lumped parameter, the apparent pH (pHapp). Two methods have been suggested for the calculation of pHapp and the loss of activity on particle preparation, these methods are based on the use of the ERE in conjunction with experimental data.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260190708
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 5
    Digitale Medien
    Digitale Medien
    Effect of diffusion limitations and floc size distributions on fermentor performance and the interpretation of experimental data (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 21 (1979), S. 221-251 
    Details
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The biological rate equation that describes the overall rate of substrate uptake by microbial films has been extended to microbial flocs with the aid of a shape parameter. The “solid”- and liquid-phase diffusion limitations are explored and found to depend largely on a dimensionles characteristic size k21Vp/Ap. Procedures are discussed by which k21Vp/Ap can be determined from experimental data on the conversion efficiency in a completely mixed fermentor and measurements carried out on flocs recovered from the fermentor are assessed. Floc size distributions are shown to affect the performance characteristics of a fermentor when some of the flocs are sufficiently large to exhibit a diffusional limitation, and it is concluded that a single mean floc size (k21Vp/Ap)* is sufficient to characterize a given distribution, at least when all the flocs are geometrically similar. The mean floc size closely corresponds to the “surface” mean floc size of the floc size distributions.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260210209
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 6
    Digitale Medien
    Digitale Medien
    Practical reactor systems for yeast cell immobilization using biomass support particles (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 134-141 
    Details
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The technique of cell immobilization using porous support particles (biomass support particles) has been successfully applied to yeast cells. Two reactor configurations exploiting the use of these particles have been developed and assessed for use in aseptic yeast fermentations. A liquid-fluidized bed fermenter has been devised for use with particles denser than the fermentation liquor whilst a gas-stirred circulating bed fermenter proved suitable for particles of essentially neutral buoyancy. Both systems have been operated successfully for extended periods of continuous operation. The utilization of biomass support particle technology in such reactors provides a practical and robust system for immobilized cell reactors. This technology offers significant opportunities for further development.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260260205
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 7
    Digitale Medien
    Digitale Medien
    Microbial film fermenters: Their present and future applications (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 17 (1975), S. 1245-1267 
    Details
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The productivity of growth associated fermentations is dependent upon the quantity of biomass contained in the fermenter (microbial hold-up). In contrast, the performance characteristics of a fermenter are dominated by the form in which the microbial hold-up occurs, i.e., whether as films, flocs, or a combination of both. Industrial fermentations using biological films include biological waste-water treatment (trickling filter, rotating disc), the “quick” vinegar process, animal tissue culture, and bacterial leaching.Atkinson and Davies (Trans. Inst. Chem. Eng., 50, 208 (1972)), proposed a completely mixed microbial film fermenter (CMMFF) based upon the fluidized bed principle, for application to continuous operation when using growth associated systems. The potential performance characteristics of this fermenter are reviewed and the construction of a laboratory scale unit capable ofaseptic operation is described (volume 9 liters, maximum throughput 15 liter/hr). The fermenter has been continuously used for periods up to 2500 hr without contamination when growing brewer's yeast (NCYC 1026 flocculating). The experimental performance characteristics have been interpreted with the aid of the theory for the CMMFF.The knowledge and experience gained to date is used as a basis for speculation as to the future role of microbial film fermenters in the biochemical process industries.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260170902
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 8
    Digitale Medien
    Digitale Medien
    Influence of oxygen and substrate concentrations on the ideal film thickness and the maximum overall substrate uptake rate in microbial film fermenters (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 18 (1976), S. 15-35 
    Details
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The criterion for the oxygen limitation of substrate uptake in microbial film fermenters is expressed in terms of diffusion coefficients, utilization coefficients, and the free solution concentrations of substrate and oxygen. It is proposed that the ideal film thickness in such fermenters is equal to the penetration depth of the limiting substrate. The ideal film thickness is calculated, in terms of the parameters contained in the criterion for oxygen limitation, for three separate kinetic rate expressions. It is found that for the air-glucose-microbe system a simplified kinetic rate expression can be used and the region of dependence on two substrates is shown to be very limited. This is not true for other systems. Maximum uptake rates are calculated for a range of concentrations. Finally, it is shown that the procedure used can be generalized to determine the limiting substrate in a multisubstrate system and to calculate ideal film thickness and uptake rates for any pair of substrates where the kinetics of substrate uptake are known for the individual microorganism.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260180103
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 9
    Digitale Medien
    Digitale Medien
    An enzyme rate equation for the overall rate of reaction of gel-immobilized glucose oxidase particles under buffered conditions. I. Pseudo-one substrate conditions (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 16 (1974), S. 1299-1320 
    Details
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The overall rate of reaction of buffered gel-immobilized glucose oxidase particles is described by means of an enzyme rate equation which relates the overall reaction rate of a particle to the free solution characteristics of the enzyme, the effective diffusivity of the limiting substrate in the gel, the characteristic particle size, and the limiting substrate concentration adjacent to the gel surface. This equation accounts quantitatively for the limitation of the overall rate of reaction by substrate diffusion, and it is used to illustrate the influence of the system parameters, i. e., particle size, enzyme concentration, and pH, on the extent of the diffusional resistance associated with gel-immobilized glucose oxidase particles.The enzyme rate equation is generally applicable to those enzymes whose kinetics approximately follow Michaelis-Menten form when in free solution.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260161002
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 10
    Digitale Medien
    Digitale Medien
    Biological particles of given size, shape, and density for use in biological reactorsSee Refs. 1-4. (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 21 (1979), S. 193-200 
    Details
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Novel biomass support particles containing growing cells have been developed for use in large-scale fermentation processes. The characteristic size of the entrapped biomass is identical to that of the physical structure of the support particle, and particles can be produced of any size, shape, and density with a wide variety of microorganisms. Use of the particles in fermentors leads to high biomass concentration independent of throughput, predetermined biomass concentrations, the use of novel types of fermentor with advantageous performance characteristics, possibilities for the optimization of advantageous diffusion effects, and new procedures for biomass recovery.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260210206
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...