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  • Chemistry  (22)
  • Atomic, Molecular and Optical Physics  (1)
  • URSEIS 95, Urals, tectonics/crustal structure, refraction seismics  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Tunneling phenomena in three-dimensional double-well potentialsResearch Supported in part by a grant from the National Science Foundation. (1973)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 7 (1973), S. 319-332 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tunneling of a hydrogen atom through the barrier of a three-dimensional double-well potential is considered. From the time-dependent Schrödinger equation, expressions are derived for the ensemble-averaged probability density and for the probability that the hydrogen atom is in the reactant region, in the barrier region, or in the product region. It is found that when thermal vibrations are not taken into account, the ensemble-averaged probability density may oscillate with time about its equilibrium value. When thermal vibrations are included, the oscillations become damped and the probability density approaches equilibrium. The tunneling rate is found to decrease considerably for increasing barrier thickness and barrier height.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560070214
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetic Behavior of Microencapsulated β-Galactosidase (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 17 (1975), S. 1157-1181 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Escherichia coli β-D-galactosidase (E.C. 3.2.1.23) was immobilized in cellulose nitrate membrane microcapsules and the reaction kinetics with o-nitrophenyl-β-D-galactopyranoside (ONPG), lactose, and whole milk were studied using both continuous stirred tank and packed bedreactor configurations. The results of the experiments gave effectiveness factors of 0.3 for ONPG, 0.6 to 0.7 for lactose in solution, andclose to unity for lactose in milk. Using a coupled mass transfer and kinetic model, it was possible to estimate the permeability of the microcapsule membrane from the reactor data. Membrane permeabilities on the order of 5 × 10-3 and 3 × 10-4 cm/sec were estimated for ONPG and lactose, respectively. It was determined that the membrane was the limiting mass transfer resistance for the overallreaction. The analysis showed that within the microcapsule, the reaction is reaction rate limited for lactose and slightly diffusion limitedfor ONPG.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260170806
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  • 3
    Electronic Resource
    Electronic Resource
    Effectiveness factors for substrate and product inhibition (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 17 (1975), S. 1761-1773 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The transformation technique of Na and Na (Math. Biosci., 6, 25, 1970) is extended to convert boundary-value problems involving the steady-state diffusion equation for spherical immobilized enzyme particles exhibiting substrate and product inhibition to initial-value problems. This allows a study of the influence of external mass transfer resistances on the effectiveness factors. It also considerably reduces the number of calculations required to investigate the effect of changes in the kinetic parameters on the overall rate of reaction. The existence of multiple steady states for substrate inhibition kinetics in spherical catalyst particles is illustrated and a criterion for uniqueness of steady states is developed. Effectiveness factors for competitive and noncompetitive product inhibition increase with increasing value of the Sherwood number for the substrate and increasing value of the ratio of substrate to product effective diffusivities within the particle.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260171206
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  • 4
    Electronic Resource
    Electronic Resource
    Hydrophobic chromatography of β-galactosidase (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 22 (1980), S. 377-399 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The hydrophobic interaction of β-galactosidase with Sepharose 4B substituted with 3,3′-diaminodipropylamine was studied in both batch and column experiments. The equilibrium and the binding rate constants were determined for different phosphate buffer concentrations. The equilibrium constants exhibit a hysteresis effect, i.e., desorption constants are less than adsorption constants, and the higher the ionic strength to start the desorption, the larger the effect. The rate data are not satisfactorily described by a simple reversible first-order model. The column chromatographic data are semiquantitatively described by a local equilibrium theory without axial dispersion or intraparticle diffusion.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260220211
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  • 5
    Electronic Resource
    Electronic Resource
    Lateral thermal dispersion in gas-liquid cocurrent downflow through packed beds (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2977-2983 
    Details
    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: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690421025
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  • 6
    Electronic Resource
    Electronic Resource
    Electrostatic and hydrophobic effects in affinity chromatography (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 17 (1975), S. 895-914 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A semi-quantitative theory is developed to explain the nonspecific binding of proteins to substituted affinity chromatography supports due to electrostatic and hydrophobic interactions. The equilibrium constant for the absorption of an enzyme to a solid support, and the rate of desorption of the enzyme are studied as functions of ionic strength. Experimental measurements were taken of the adsorption equilibrium constant and rate of desorption of E. coli β-galactosidase on Sepharose 4B substituted with 3, 3,-diaminodipropylamine in batch systems. It was found that the enzyme adsorption exhibits a hysteresis effect as the ionic strength is increased and then decreased. Furthermore, the adsorption of theenzyme becomes more reversible at the lower ionic strengths, while at the higher ionic strengths it is essentially irreversible. Using the measured equilibrium constants, and knowing the region of ionic strength where the adsorption becomes reversible, we were able to predict the desorption of enzyme in a continuous stirred tank as a function of time when a decreasing linear gradient of ionic strength was introduced into a slurry. It was found that the presence of another protein, hemoglobin, does not affect these results, and therefore can be separated from the enzyme.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260170609
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  • 7
    Electronic Resource
    Electronic Resource
    Mass transfer coefficients in coiled tubes (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 17 (1975), S. 1383-1385 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: No Abstrast.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260170916
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  • 8
    Electronic Resource
    Electronic Resource
    Water-soluble nonionic surfactants for affinity bioseparations (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 33 (1989), S. 1267-1276 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Reversible competitive inhibitors of the three enzymes β-galactosidase, trypsin, and serum cholinesterase have been covalently attached to nonionic ethoxylated surfactants. The binding of the resulting affinity-derivatized surfactants to the respective enzymes has been quantified by measuring Michaelis-Menten inhibition constants with kinetic assays. The surfactant-inhibitor of serum cholinesterase, octaethylene glycol monohexadecy ether pyridinium (C16E8-PYR), was adsorbed in aqueous solution to an octadecyl-bonded reverse-phase silica packing in a 2 × 0.2 cm stainless steel test column. The ability of the test column to function as a high-performance affinity chromatography (HPAC) column was determined by applying a mixture of bovine serum albumin and cholinesterase (4:1 w/w). Virtually all of the cholinesterase bound and was eluted by applying a gradient in ionic strength. The applied cholinfesterase was recovered with a yield of over 90% and an 11-fold purification. An aliquot of raw horse serum was then purified in the same fashion with a yield of 84% and a 280-fold purification. The surfactant-inhibitor was easily removed from the column with an alcohol wash for sterilization, cleaning, or application of a different affinity ligand. Moreover, the ligand density on the column can be easily manipulated by adsorbing mixtures of derivatized and underivatized surfactants. Leakage of ligands from the support seems to be minimal since the cholinesterase affinity column was operated efficiently after being exposed to 24,000 column volumes of buffer. The application of this technique to high-capacity, high-throughput reversible affinity purifications is limited only by the ability to identify suitable ligands.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260331007
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  • 9
    Electronic Resource
    Electronic Resource
    Immobilization of β-galactosidase in collodion microcapsules (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 17 (1975), S. 617-619 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260170414
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  • 10
    Electronic Resource
    Electronic Resource
    Simultaneous ultrafiltration and affinity sorptive separation of proteins in a hollow fiber membrane module (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 572-580 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A protein separation scheme combining affinity or ion exchange sorption with hollow fiber cross-flow filtration is described. Sorptive gel particles were loaded into the shell side of a hollow fiber membrane module. In the adsorption step, crude protein mixtures were passed through the lumen and permeating proteins passed through the membrane to bind on the gel particles in the shell. During elution, a buffer of adequate ionic strength to desorb the bound proteins was passed through the lumen and permeated through the shell. The eluant was then collected at the outlet to the shell of the hollow fiber module. The concept is illustrated by two examples: the purification of butyrylcholinesterase (EC 3.1.1.7) from raw horse serum using the affinity gel procainamide-Sepharose as the packing and the separation of carboxylesterase (EC 3.1.1.1) from beef liver homogenate using DEAE-Sephadex as the packing. The technique has the advantage of high volumetric throughputs typical of hollow fiber membrane modules as well as the high capacity characteristic of chromatographic packings. In addition, cross-flow filtration of particulates, agglomerates, and debris in passing protein from lumen to shell side can help eliminate the need for extensive pretreatment.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360604
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