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  • 1
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary liquid, choice of ; Physico-chemical data
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A table of data for acidity, basicity, polarity and London potential for stationary phases is given. These provide guidance in choosing a stationary phase for a given task from the 26 substances listed. The indices are calculated from infra-red shifts of 1-chlorobutane and the visible wavelength shifts of l2 when they are dissolved in the stationary phases, from NMR estimates of acidity and basicity and from relative retention data. They replace the less reliable data of Burns and Hawkes. Methods of determining the indices are suggested that require only a gas chromatograph and can be applied by technicians with no specialized understanding of solution parameters. An attempt to add electron donoracceptor indices to the table was unsuccessful. A further table is given of the slopes of the log plots d(logt′)/dC for use in extrapolating from one homologue to another on these stationary phases.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 20 (1985), S. 343-346 
    ISSN: 1612-1112
    Keywords: Thermosorb ; Tenax GC ; Environmental Analysis ; Trace Organics ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A preliminary study has been carried out to evaluate a new adsorbent, Thermosorb, for trace level organic contaminants. For this purpose, a comparison was made with a well-characterized adsorbent, Tenax GC, using a prepared aqueous solution of trace organic components. In addition, a comparison was made of chromatograms of air contaminants obtained using both of these adsorbents, under equivalent conditions. The results clearly indicated the potential of this thermally stable, inorganic adsorbent for many trace organic substances of environmental interest.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 20 (1985), S. 371-375 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Flame photometric detector ; Sulphur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of experimental conditions such as gas flow rates, detector and column temperatures on sulphur response are discussed. It is concluded that the response of the flame photometric detector is affected by the O/H ratio and the total gas flow. Column temperature has an important influence upon S2 emission. It is shown that the sulphur response of the FPD is dependent on the compound containing the sulphur.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European archives of oto-rhino-laryngology and head & neck 242 (1985), S. 177-182 
    ISSN: 1434-4726
    Keywords: Glycoprotein ; Middle ear fluid ; Serous otitis media ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We analyzed the sugar components of the glycoprotein fractions in human middle ear fluid samples by using gas chromatography. All ear effusions included serous, seromucinous and mucoid samples, and contained appreciable amounts of fucose, mannose, galactose, glucose, N-acetyl glucosamine and sialic acid. Total sugar content to protein was significantly higher in mucoid effusions than in serous effusions. Among the sugar components, the contents of sialic acid, N-acetyl glucosamine, fucose and galactose were much higher in the mucoid effusions. The data show new evidence that some glycoproteins having high proportions of sialic acid, N-acetyl glucosamine, fucose and galactose appear in the middle ear fluid of the glue ear.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid crystal ; Capillary columns ; Retention data ; Stationary phase film thickness ; Column surface quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Glass capillary columns were prepared from non-deactivated and deactivated glass and coated with (2-methyl-4-[trans-4-n-propyl-cyclohexylcarbonyloxy]-benzoic acid-[4-n-heptyloxy-phenylester]) as the liqud phase, in different film thicknesses. The columns were tested using substances of different structures and polarities. It was verified that the capacity factors, retention indices and selectivity significantly depend on the thickness of the liquid crystalline stationary phase film and the quality of the tube, particularly in the case of columns with thin films. Trasition temperatures (melting and clearing point) of the liquid crystal are also dependent on these two factors.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Esterification in aqueous solution ; n-Butyl esters of amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Amino acids have been esterified with n-butanol and isobutanol in the presence of perchloric acid. It has been established that in the concentration range of [H2O]/[n-BuOH]=0.10–0.40 esterification can be utilized for the determination of alanine, glycine, valine, leucine, proline, methionine, aspartic acid, phenylalanine, tyrosine, glutamic acid, lysine, arginine, histidine and cystine. In the case of [H2O]/[i-BuOH] =0.05–0.20 the esterification yield decreases from 100% to 70%, in proportion to the water content.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 20 (1985), S. 681-682 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Geothermal gases ; Molecular sieves ; Low temperature separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The gases evolved from geothermal fields, after condensation of H2O, CO2, H2S and NH3 in caustic solution, contain He, H2, Ar, O2, N2, CH4 and higher hydrocarbons. The analysis for the major components in these residual gas mixtures can be achieved by use of two simple gas chromatographs in parallel, and using 5Å molecular sieve. The separation of He and H2 to baseline is achieved by using low temperatures (30°C) coupled with a relatively long column; and the difficult separation of Ar and O2 is achieved by use of a cryogenically cooled column. The use of switching valves to backflush and bypass columns ensures that a minimum time for analysis can be achieved whilst retaining baseline separations of the He/H2 and Ar/O2 pairs.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 20 (1985), S. 685-688 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Fuming sulphuric acid-ethanol esterification ; Ethyl and methyl esters of herbicides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A fuming sulphuric acid-ethanol esterification method has been applied to chlorophenoxy acids and some other herbicides. This method is compared with esterification by iodoethane and diazomethane. The chlorophenoxy acids studied were: 2,4-D, dichlorprop, MCPA, MCPB, mecoprop and 2,4,5-T. Other herbicides studied were: benazolin, bentazone, bromophenoxime, bromoxynil, chlorthal, dicamba, 3,6-dichloropicolinic acid, dinoseb, ethephon, fluroxypyr, glyphosate, haloxyfop, ioxynil, picloram, 2,3,6-TBA and triclopyr. Fuming sulphuric acid-ethanol esterification can be successfully applied to chlorophenoxy acids, benazolin, 3,6-dichloropicolinic acid, dinoseb, fluroxypyr, haloxyfop, picloram and triclopyr. The reproductibility of the method is ±5%.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Step profile method ; Adsorption isotherm ; Water film pressure ; Surface free energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Investigation of water adsorption by the step profile method (Glueckauf method) was carried out with the help of a modified gas chromatography equipped with thermal-conductivity detector. On the basis of the adsorption isotherm obtained, the water film pressure and the polar component of the surface free energy of quartz were calculated. The calculated value of the polar component of the surface free energy of quartz agrees with analogous values obtained by other methods.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Electron-capture ; Thermal-energy electrons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The products resulting from the reaction between thermal energy electrons and organic compounds have been investigated to further our knowledge of the mode of action of the electron-capture detector. Thermal energy electrons were generated by maintaining a corona discharge between a stainless steel cathode and a silver/silver chloride anode. The effects of electrode geometry, gas composition, gas flow rate, and the physical properties of the test substances were investigated. The design of the reactor was modified to minimize losses of unchanged substrate. Reaction products of benzaldehyde, tolualdehydes, chlorobenzaldehydes, and dichlorobenzenes were identified by combined gas chromatography — mass spectrometry.
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 20 (1985), S. 195-196 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Wide-bore capillaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 20 (1985), S. 403-406 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Separation of sugars ; Oxime formation ; Silylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The procedure involving oxime formation followed by silylation for the analysis of standard hexoses by GC resulted in unseparated peaks for D-glucose, D-mannose and D-galactose. This procedure was therefore modified to obtain clear separation of hexoses. STOX (hydroxylamine containing phenyl-β-D-glucopyranoside as the internal standard) was mixed with trimethylsilylimidazol or hexamethyldisilazane, and then added to a standard sugar mixture containing D-glucose, D-galactose and D-mannose. The mixture was analyzed by gas chromatography with OV-17/OV-22 as the stationary phase, resulting in three distinct peaks.
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Esterification in aqueous solution ; n-Butyl esters of aliphatic hydroxy acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Aliphatic hydroxy acids were esterified in aqueous solution in the presence of sulfuric acid. Esterification of lactic, tartronic malic and citric acids in water/n-butanol mixtures with mole ratios between 0.02 and 2.53 can be utilized for the determination of these aliphatic hydroxy acids by gas chromatography. Water does not interfere at water/n-butanol mole ratios below 0.02. For mole ratios above 0.02 anhydrous sodium sulfate is used for the binding of water. The mole ratio range was 0.25–2.53 for anhydrous sodium sulfate/water, and 0.32–1.27 for sulfuric acid/anhydrous sodium sulfate.
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  • 14
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Nitrogen dioxide ; Diethyl ether ; Photo-induced reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary When dissolved in diethyl ether, nitrogen dioxide reacts with the solvent, slowly at room temperature, more rapidly on heating of UV irradiation. A complex mixture of products is formed in which further changes are observed after prolonged storge: these are less pronounced if the unreacted nitrogen oxides are removed. A gas chromatographic method was applied for the identification of the majority of products. Irradiation does not change significantly the qualitative and quantitative composition of the reaction products. The reaction is thus the so-called photo-induced process [ΔG〈0]. Preliminary suggestions are made concerning the reaction mechanism.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 20 (1985), S. 538-542 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Fluidized beds ; Industrial chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Chromatography is carried out under the conditions of fluidization, in long, straight tubes under organized and non-organized conditions. Under non-organized conditions the column is filled only with a sorbent. In organized conditions, either metal coils are added into the column or a segmented column is utilized with metal grids. The results obtained are compared to those obtained under fixed-bed conditions when the column is completely filled with the sorbent. Organized fluidized beds provide a significant decrease in longitudinal bandspreading.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 20 (1985), S. 197-200 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Polyalcohol quantification ; Wine ; Vinegar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatographic method is described for the analysis of arabitol, mannitol, sorbitol and inositol in wine. The method is evaluated for repeatability using perseitol as internal standard. Perseitol can be added to wine before or after passing the wine through the ion-exchange column without showing significant differences in the polyalcohol content. The method is also applied to the analysis of vinegar from different substrates (wine cider and rice).
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  • 17
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Modified diatomaceous supports
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Diatomaceous earth type supports are modified with a liquid phase, by high-temperature thermal treatment in a closed system. It is shown that the retention characteristics of the support changes by this treatment. The main advantage of this method, as compared with modification in a flow-through system is that liquid phase evaporation and possibility of oxydation during the process can be avoided. This ensures a better uniformity of the modified support.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 20 (1985), S. 308-312 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Silica surface modification ; Hexamethylcyclotrisilazane ; Hexamethyldisilazane ; Support materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary For chromatographic purposes the use of mixtures instead of individual silylating agents can produce better deactivated surface than those shown by silicas modified by hexamethylcyclotrisilazane or hexamethyldisilazane separately.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 20 (1985), S. 5-8 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; H2SO4-coated silica gel ; Air pollution (foundries) ; Tertiary amines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary After a brief review of the main publications dealing with air-sampling and analysis of aliphatic amines, the authors propose and investigate two sampling methods (bubbling through a sulfuric acid solution, trapping on sulfuric acid-treated silica-gel) for three tertiary aliphatic amines commonly encountered in foundries.
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  • 20
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid crystals ; Substituted benzenes and selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention mechanisms of polymethylbenzenes and n-alkylbenzenes on the inert solid support Chromaton (spec-surface area: 1m2/g) and the adsorbent-support Silochrom (C-80 (80 m2/g) coated with p-n-butyl oxybenzoic acid have been investigated.
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  • 21
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Thermodynamic characteristics ; Retention index calculation ; Temperature dependency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Thermodynamic characteristics determined from retention data measured under isothermal conditions were used for the calculation of retention indices of a number of model compound. The minimum retention index difference required for the identification of two adijacent compounds as well the temperature dependency of retention index are discussed. The possibility of alculating thermodynamic characteristics from retention indices published in the literature was also investigated.
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  • 22
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Glass capillary column ; Retention indices ; Alkylcyclopentane and Alkenylcyclopentane ; Alkylcyclohexane and Alkenylcyclohexane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reaction products of the pyrolysis of n-dodecylpentane and n-hexylcyclohexane had been separated and identified on a glass capillary column coated with Polydimethylsiloxane OV-1. The identification of the components in the pyrolysis products and of the corresponding hydrogenated samples was performed from structure retention correlations, especially retention index increments (1CH2), homomorphy values (HOV-1) and the temperature coefficients of retention indices (δI/δT). Hence the presence of homologous 1-alkenes and of monoalkenylcycloalkanes could be confirmed. Based on the addition principle of index increments the determination of the side chain structure of alkenylcycloalkanes (straight chain) and the position of the double bond was ascertained. The calculation of the retention indices of these compounds was performed with high accuracy (deviation 〈1 index unit). Retention indices of 10 1-alkenes, 11 monoalkenyl-cyclopentanes, 11 monoalkylcyclopentanes, 5 monoalkenylcyclohexanes and 5 monoalkylcyclohexanes were determined on the liquid phase Polydimethylsiloxane OV-1.
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  • 23
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 20-27 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Optimal conditions for solid substrate fermentation of wheat straw with Chaetomium cellulolyticum in laboratory-scale stationary layer fermenters were developed. The best pretreatment for wheat straw was ammonia freeze explosion, followed by steam treatment, alkali treatment, and simple autoclaving. The optimal fermentation conditions were 80% (w/w) moisture content; incubation temperature of 37°C; 2% (w/w) unwashed mycelial inoculum; aeration at 0.12 L/h/g; substrate thickness of 1 to 2 cm; and duration of three days. Technical parameters for this optimized fermentation were: degree of substance utilization, 27.2%; protein yield/substrate, 0.09 g; biomass yield/bioconverted substrate, 0.40 g; degree of bioconversion of total available sugars in the substrate, 60.5%; specific efficiency of bioconversion, 70.8%; and overall efficiency of biomass production from substrate, 42.7%. Mixed culturing of Candida utilis further increased biomass production by 20%. The best mode of fermentation was a semicontinuous fed-batch fermentation where one-half of the fermented material was removed at three-day intervals and replaced by fresh substrate. In this mode, protein production was 20% higher than in batch mode, protein productivity was maintained over 12 days, and sporulation was prevented.
    Additional Material: 4 Ill.
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  • 24
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 41-49 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: More than 90% of initial pyritic sulfur was removed from bituminous coal samples (containing 2.1% pyritic sulfur) using the thermophilic organism Sulfolobus acidocaldarius. Microbial desulfurization rate was improved nearly ten fold by adjusting the N/P and N/Mg ratios in the nutrient medium. Environmental conditions were optimized. The optimal values of temperature and pH were 70°C and 1.5, respectively. The influence of certain process variables (such as coal pulp density, particle size, and initial cell number density) on the rate of pyritic sulfur removal were determined. A pulp density of 20%, particle size of D¯p 〈 48 μm, and an initial cell number density of 1012 cells/g pyrite in coal were found to be optimal. The carbon dioxide enriched air did not improve the rate of pyritic sulfur removal compared to pure air at 10% pulp density of coal samples containing 2.1% pyritic sulfur. The kinetics of microbial leaching of pyritic sulfur from coal was investigated. The rate of leaching was found to be first order with respect to pyritic sulfur concentration in the reaction medium.
    Additional Material: 8 Ill.
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  • 25
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 86-93 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The stability of downflow stationary fixed-film (DSFF) reactors was evaluated under extreme organic shock loads. Reactors could handle five- to sevenfold increases in organic loading and recover to normal performance in a relatively short period of time (usually 24-72 h) during treatment of well-buffered sucrose and acetic acid wastewater at 27 and 35°C. Overloading was characterized by elevated volatile-acid concentrations, decreased reactor pH, and excess biofilm sloughing. Reactors could not cope with extreme organic shocks during treatment of poorly buffered sucrose wastewater. The pH of the mixed liquor was observed to be a more important factor than the volatile-acid concentration in determining whether DSFF reactors would recover in a reasonable period of time.
    Additional Material: 9 Ill.
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  • 26
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 260-265 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Synergistic action of α-amylase and glucoamylase on hydrolysis of starch is modeled by the kinetic equations presented in this paper. At the early stage of the reaction α-amylase acts as a contributor of newly formed nonreducing ends of starch molecules to glucoamylase by splitting the original starch molecules. This is expressed by the simultaneous differential equations which consist of each rate equation for α-amylase and glucoamylase. After the molecular weight of the substrate decreases to the value of about 5000, which is obtained experimentally in this work, the action of α-amylase can be neglected and the rate of formation of glucose obeys only the rate equation for glucoamylase.
    Additional Material: 6 Ill.
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  • 27
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 296-301 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous cultivation of Pelobacter acidigallici on gallic acid is accompanied by biofilm formation. Steady states can be obtained at dilution rates nearly twice the maximum growth rate. A two-compartment model is presented which allows us to determine rate constants of attachment and detachment. The model is based on the assumption that the biofilm is fully penetrated by the substrate. At high dilution rates the outcome of our experiments is mainly determined by the attachment rate. The influence of the thickness of the biofilm is discussed in order to demonstrate the limitations of the model.
    Additional Material: 3 Ill.
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  • 28
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 321-326 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The integration of enzyme saccharification with fermentation reduces the total time required to produce acceptable levels of ethanol. The use of a more concentrated mash (84.8 L total mash/bu corn) results in a 26.6% increase in ethanol productivity and a 21.4% increase in beer ethanol concentration compared to standard corn mash (96.6 L total mash/bu corn). Thus, the energy requirement and cost of distillation can be reduced. The addition of waste cola syrup at 30 g invert sugar/L total mash gave a 19% increase in ethanol concentration in the final beer and required only a small increase in the period of fermentation. Surplus laundry starch can replace 30-50% of the weight of corn normally used in fermentation without influencing ethanol production or the time required for fermentation. Both of these waste materials reduce the unit cost of ethanol and demonstrate the value of such substances in ethanol systems.
    Additional Material: 5 Ill.
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  • 29
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 137-145 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dried spheres made from an alginate solution containing magnetite particles have excellent potential as a support for enzyme immobilization and chromatographic applications. The beads were found to be much stronger than gels such as polyacrylamide and dextran, indicating that high flow rates and pressures could be used in column separations. The support withstood not only temperatures of up to 120°C, but also most pH values and common solvents. While some solutions, such as phosphate buffers, dissolved the spheres, stabilization with Tyzor TE® eliminated this problem. The physical properties of the beads include a glasslike density of 2.2 g/mL, excellent sphericity, low porosity, and a narrow size distribution. The magnetite present in the support allows the beads to be used for magnetic separations such as high gradient magnetic filtration. Their high degree of microroughness provides a large exposed surface area for enzyme and ligand binding. Mixed Actinomyces fradiae proteases and Aspergillus niger α-amylase, two enzymes representative of classes which attack large substrates, were immobilized on the bead's surface with high activity and stability. A cyanuric dye which can be used in chromatographic applications (Cibacron Blue F3GA®) was also readily coupled to the surface of this support with good yield. The support should have a wide range of applications in bioseparation and immobilized biochemical technology.
    Additional Material: 3 Ill.
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  • 30
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 409-414 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The integrated rate equation of Huang, originally used to describe the hydrolysis of insoluble acid treated cellulose, is shown equally applicable in describing the hydrolysis of carboxymethylcellulose (CMC) using a dilution series of Cellulomonas sp. ATCC 21399 crude cellulase as enzyme preparation. Interpretation of the progress curves of hydrolysis of CMC according to the integrated rate equation is used to calculate a standard formula for the conversion of the rate of hydrolysis into the initial velocity of hydrolysis. The validity of the standard formula is tested, using enzyme preparations from Cellulomonas grown under varied conditions, and enzyme preparations containing purified endoglucanases from Cellulomonas.
    Additional Material: 3 Ill.
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  • 31
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 415-419 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Porcine pepsin was immobilized by chemical aggregation using glutaraldehyde as a bifunctional crosslinking agent. The immobilzed pepsin followed Michaelis-Menten kinetics (Km = 5.3 × 10-5 M) and the yield of immobilization was 91%. The activation energy of the immobilized preparation was 90,613 cal/mol as compared to 67,532 cal/mol for native pepsin. Using acid-denatured hemoglobin and N-acetyl phenyl-alanyl-3, 5-diiodotyrosine (APDT) as substrates, the activities shown by the immobilized pepsin were, respectively, 67 and 79% that of the soluble pepsin. The immobiized pepsin showed marked stabilization against pH, temperature, urea, and guanidine hydrochloride. The activity of the immobilized preparation in the presence of urea was greater when hemoglobin was used as the substrate than when APDT was used as substrate. Storage of the preparation under refrigerated conditions for 160 days showed 58% retention in enzyme activity. The immobilized pepsin can be removed from the reaction mixture volume easily, retaining nearly 100% of its activity even after being used in seven consecutive assays.
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  • 32
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    Biotechnology and Bioengineering 27 (1985), S. 439-446 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of four pH steps and one dilution rate step are described for an ammonia-nitrogen-limited continuous culture of Escherichia coli B/r. Two of the pH steps, 6.06-5.49 and 5.96-5.60, led to prolonged transients in both cell density and rate-limiting nutrient concentration. The other two pH steps, 6.20-5.96 and 5.60-6.20, had almost no effect on the culture. The dilution rate step led to a sharp transition in the steady-state external pyruvate concentration. Monitoring of the external pyruvate concentration for the pH 5.96-5.60 step revealed that the transient phase continued long after the cell density and rate-limiting nutrient concentration returned to steady-state values. The implications for industrial and laboratory fermentations are discussed.
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  • 33
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aldehyde oxidase (E.C. 1.2.3.1) was isolated from rabbit liver and two potential bioaffinity ligands, i.e., 3-aminocarbonyl-1-benzyl-6-methylpyridinium bromide and 3-aminocarbonyl-1-benzyl-4,6-dimethylpyridinium chloride, were tested for their applicability in a purification procedure for this enzyme. Various supports and different coupling methods were investigated for the immobilization of aldehyde oxidase. Adsorption to n-hexyl- and n-octylamine-substituted Sepharose 4B and DEAE Sepharose 6B gave the best retention of aldehyde oxidase activity. The storage stability of free enzyme and enzyme immobilized to n-octylamine-substituted Sepharose 4B was studied in several buffers at pH 7.8 and 9.0. This showed that the stability of immobilized enzyme was much less than that of free enzyme. The apparent operational stability of the immobilized enzyme preparation, however, improved substantially compared to soluble enzyme, although the corresponding product yield is still very poor. Coimmobilization of catalase and/or superoxide dismutase provided no significant increase of the apparent operational stability and product yield. A positive effect on both parameters was found for aldehyde oxidase-n-alkylamine Sepharose 4B preparations by increasing the amount of enzyme adsorbed per unit weight of support, whereas the productivity of these preparations remained about constant.
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  • 34
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    Biotechnology and Bioengineering 27 (1985), S. 463-470 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The enzymatic hydrolysis of cellulose to glucose involves the formation of cellobiose as an intermediate. It has been found necessary1 to add cellobiase from Aspergillus niger (NOVO) to the cellobiase component of Trichoderma reesei mutant Rut C-30 (Natick) cellulase enzymes in order to obtain after 48 h complete conversion of the cellobiose formed in the enzymatic hydrolysis of biomass. This study of the cellobiase activity of these two enzyme sources was undertaken as a first step in the formation of a kinetic model for cellulose hydrolysis that can be used in process design. In order to cover the full range of cellobiose concentrations, it was necessary to develop separate kinetic parameters for high- and low-concentration ranges of cellobiose for the enzymes from each organism. Competitive glucose inhibition was observed with the enzymes from both organisms. Substrate inhibition was observed only with the A. niger enzymes.
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  • 35
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    Biotechnology and Bioengineering 27 (1985), S. 503-508 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the laboratory-type airlift tower reactor oxygen transfer from air in tap water and/or polyacrylamide solutions (Neuperm WF) was studied. In order to characterize the system, volumetric coefficient of oxygen transfer was determined by the gassing-out method. Two arrangements of the airlift tower reactor were compared, namely the reactor with and without motionless mixer. In addition, mean relative gas holdup and gas power output were determined for both arrangements.
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  • 36
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    Biotechnology and Bioengineering 27 (1985), S. 514-518 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Hydrophobic ligands were introduced onto agarose beads, and the adsorption capacity of the beads was measured. The adsorption capacity increased with increase in the carbon number of the ligand, ionic strength of the buffer solution, and temperature. Crude α-amylase was purified with these hydrophobic adsorbents and the breakthrough and elution curves were estimated based on the mass transfer theory. Under strongly hydrophobic conditions, impurities contained in crude feeds and the lack of uniformity of packing caused by aggregation of beads affected adsorption and elution behaviors.
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  • 37
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    Biotechnology and Bioengineering 27 (1985), S. 362-368 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Corn stover was pretreated with various chemical agents, including sodium hydroxide, sulfuric acid, ethylenediamine, n-butylamine (either alone or in solution with methanol), and acetonitrile or ethanol containing hydrochloric acid. Of these chemicals, n-butylamine was the best reagent for pretreatment of corn stover, considering the degree of loss of total carbohydrate, delignification, cumulative weight loss, cumulative yield of reducing sugars per original total carbohydrate, and the potential ease of recovery and reuse of reagent. In comparison to the other reagents tested, n-butylamine (n-BA) selectively delignified corn stover. The best conditions were as follows: a 12-h presoak of about a 155 g dry wt/L slurry (1 mm average particle size) in 100% n-BA at room temperature, followed by 30 min of refluxing (86.5°C) with 40% (w/w) n-BA-distilled water solution. The cumulative yield of reducing sugars after enzymic hydrolysis was 44.5% of the original total carbohydrate and the cumulative total weight loss (dry basis) was 59%. Degradative loss of total carbohydrate during pretreatment was not detected.
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  • 38
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    Biotechnology and Bioengineering 27 (1985), S. 389-397 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It was confirmed that simultaneous saccharification and fermentation are effective for accelerating enzymatic saccharification of cellulose. In this work, the effects of ethanol on the saccharification of tissue paper by Trichoderma cellulase (Meicelase CEPB) have been investigated. The following results were obtained. (1) Saccharification was inhibited by at least 0.2M ethanol. (2) Less than 4M ethanol did not affect the enzymatic activities of β-glucosidase and endoglucanase (Cx) at all. The thermal stability of endoglucanase was not also varied by ethanol. (3) It is suggested that ethanol depresses the adsorption of exoglucanase on cellulose. (4) The rate expression of saccharification of cellulose in the presense of ethanol is proposed. (5) The inhibititory effect of ethanol was found to become more significant in the later stages of the reaction than just the initial stage.
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  • 39
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    Biotechnology and Bioengineering 27 (1985), S. 572-578 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cellobiase was coupled to a dialdehyde dextran by reductive alkylation in the presence of sodium cyanoborohydride. The resulting conjugate, obtained without loss of enzymic activity, presents properties of thermoresistance largely superior to those of native enzyme: the rate of inactivation is reduced compared to that of native enzyme and its optimal temperature of activity is 70-75°C instead of 65°C. Finally the conjugate presents increased longevity when subjected to experiments of operational stability; its hydrolytic activity is maintained at 60°C in a 10% (w/v) cellobiose solution for more than 100 h whereas the native enzyme is inactivated after 45 h. The cellobiase-dextran conjugate was immobilized by covalent coupling on aminated silica by reductive alkylation in the presence of NaBH3CN. The characteristics of thermoresistance of this stabilized and immobilized conjugate were studied and compared to those of a preparation of native cellobiase immobilized on a silica support activated with glutaraldehyde. Analysis of the thermoresistance of these two cellobiase preparations clearly shows that immobilization has maintained and even enhanced their properties. In particular, the operational stability, measured at 68°C on 10% (w/v) cellobiose shows an increased longevity of the stabilized and immobilized enzyme for 120 h compared to 60 h for the native immobilized enzyme. Two successive incubations of these cellobiase derivatives show that it is possible to obtain 2.5 times more glucose with the stabilized-immobilized enzyme than with the immobilized preparation. The procedure described above enables us to prepare a thermostabilized immobilized cellobiase.
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  • 40
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    Biotechnology and Bioengineering 27 (1985), S. 585-595 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For the cultivation of mammalian cells on microcarriers a minimum inoculum concentration is required to initiate cell attachment and subsequent cell growth. A critical cell number model has been proposed to elucidate the mechanism of the inoculum requirement. In this model it was hypothesized that after inoculation a critical number of cells per microcarrier is required for normal growth to occur; failure to acquire enough cells will impede cell growth. This critical cell number model was expressed mathematically and used to simulate cell distribution and growth on microcarriers under different cultivation conditions. By comparing the simulated growth kinetics with the experimental results, the actual critical cell number per microcarrier was identified. The critical number could be reduced by employing an improved medium for the cultivation.
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  • 41
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    Biotechnology and Bioengineering 27 (1985), S. 596-602 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A regenerating reaction combined with the use of native malate dehydrogenase, native diaphorase, methylviologen, NAD, oxalacetic acid as the substrate and lipoamide as a stabilizer was carried out in the presence of electrolysis. Consequently, malic acid was efficiently produced from oxalacetic acid in the regenerating reaction. A glassy carbon bead electrode was used as a cathode. Twenty four milliamperes were passed at a rotation speed of 500 rpm, 29.8 ± 0.3°C and -1.0 V. It was found that lipoamide has a stabilizing effect on malate dehydrogenase and diaphorase. Low concentration (50 μM) of NAD was also effective for the stabilization of malate dehydrogenase. NADH regeneration activity based on malic acid production rate was 4.7 U/mg of the enzyme protein of the commercial diaphorase preparation. The current efficiency was more than 74%, compared with the theoretical yield, in the presence of enough oxalacetic acid.
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  • 42
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    Biotechnology and Bioengineering 27 (1985), S. 603-612 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We describe the use of affinity chromatography for separation of cell populations that do not differ significantly with respect to gross physical properties such as size, density, or charge. Cell affinity chromatography exploits differences in cell surface macromolecules by passage of mixtures of cell populations through a column containing beads to which are attached chemical ligands with specific binding affinity for particular cell surface receptors. In this article we focus on the application of this concept to separation of mature T lymphocytes from peripheral blood. This serves as a model for the separation of these cells from bone marrow in order to prevent graft-vs.-host disease in bone marrow transplantation. However, the concept of cell affinity chromatography should find more general widespread utility in a variety of biotechnological applications. Thus, we introduce a simple theoretical framework which is necessary in order to understand the results that might be expected in any given situation. Finally, we use this theory to provide a tentative explanation for experimental observation of the effects of temperature and flowrate on the degree of separation achieved for our current pplication.
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  • 43
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    Biotechnology and Bioengineering 27 (1985), S. 613-620 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Immobilized growing cells of Zymomonas mobilis were found to ferment rapidly and efficiently media containing 100 g/L fructose in a continuous reactor. A volumetric ethanol productivity of 94.8 g/L h was achieved at a substrate conversion of 75.5%. With 97% conversion of substrate the productivity was 28.4 g/L h. At fructose concentrations of 150 and 200 g/L substrate and product inhibitions limited the performance of the reactor. Ethanol production was constant over a period of 55 days.
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  • 44
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    Biotechnology and Bioengineering 27 (1985), S. 632-637 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Methods for the covalent coupling of microorganisms to a solid support were investigated. Both bacteria and yeast were attached to cellulose particles using cyanuric chloride as the coupling agent, although different experimental procedures were needed for the two types of microbes. This general technique for whole-cell immobilization offers an advantage over entrapment methods in that the cells are attached to the outer surface of the solid, thus eliminating the resistance of a gel to the transfer of nutrients and products. There are also indications that such immobilized cells show high productivities.
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  • 45
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    Biotechnology and Bioengineering 27 (1985), S. 660-674 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 46
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    Biotechnology and Bioengineering 27 (1985), S. 626-631 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Zymomonas mobilis immobilized on microporous ion exchange resins has previously been shown to allow the attainment of high ethanol productivities in packed-bed bioreactors. The formation of bacterial filaments after several days of continuous operation, however, had resulted in excessive pressure increases across the reactor bed. The present work examines techniques for controlling filament formation by Z. mobilis in two reactor sizes (161 mL and 7.85 L) and a feed glucose concentration of 100 g/L. By controlling the fermentation temperature at 20-25°C it has been possible to eliminate filament formation by Z. mobilis and to operate the larger bioreactor for 232 h with an ethanol productivity of 50 g/L h (based on total reactor volume). The rate of ethanol production has been shown to be very sensitive to temperature in the range 20-30°C, and it is likely that slightly higher temperatures than those used in this study will improve ethanol productivity while still permitting long-term operation.
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  • 47
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    Biotechnology and Bioengineering 27 (1985), S. 695-703 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A formulation to calculate the mean cell residence time (MCRT or sludge age) of unsteady-state activated sludge systems is presented. The formulation was studied by applying it to data generated by computer simulation and to data obtained from an actual wastewater treatment plant. The computer simulation study allowed the effects of step and pulse changes in biochemical oxygen demand (BOD) loading, and step changes in a control variable, waste sludge flow rate, to be studied independently of each other and of other disturbances. The unsteady-state MCRT formulation (herein called the dynamic sludge age, or DSA) was found to be an improvement over the traditional steady-state calculation, both for process control, and for research into activated sludge dynamics.
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  • 48
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    Biotechnology and Bioengineering 27 (1985), S. 711-720 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To simulate production-scale conditions of gluconic acid fermentation by Gluconobacter oxydans, different experimental setups are presented in this study. From the determination of the time constants of a production-scale reactor, it can be concluded that mixing and oxygen transfer are the rate-limiting mechanisms. This results in oxygen concentration gradients which were simulated in a one-compartment reactor in which the oxygen concentration was fluctuated by a fluctuated gassing with air and nitrogen. It could be concluded that only very long periods of absence of oxygen (ca. 180 s) results in lower specific oxygen uptake rates by Gluconobacter oxydans. From scale-down studies carried out in a two-compartment system to simulate a production-scale reactor more accurately, it could be concluded that not only the residence time in the aerated part of the system is important, but the liquid flow in between the different parts of the reactor is also an essential parameter. It could also be concluded that the microorganisms are not influenced negatively by the fluctuated oxygen concentrations with respect to their maximal oxidation capacity. The two-compartment system can also be used for optimization experiments in which the “aerated” compartment was gassed with pure oxygen. From these experiments it was concluded that also a short residence of the cells at high oxygen concentrations diminished the growth and product formation rates. These experiments show the necessity of the scale-down experiments if optimization is carried out. The two-compartment system presented in this study is a very attractive tool for reliable scale-down experiments.
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  • 49
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    Biotechnology and Bioengineering 27 (1985), S. 729-742 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article deals with the design and operation of a filtration probe for estimating cell concentrations in fermentations involving mycelial organisms such as Penicillium chrysogenum. This device, a much improved version of one developed previously, is placed directly into the fermentor and measures the filtration properties of the fermentation broth, which are correlated to the cell concentration. The probe is connected to a computer system which enables on-line estimation of the cell concentration. Fiber-optic light guides are used in combination with a pair of light sources and receivers to detect the relative position of the filter-cake-fermentation-broth interface. The lower sensor in the filtration tube enables reliable estimation of cell mass upto about 20 g/L (dry wt), while the upper sensor yields useful measurement of the filtration properties upto a concentration of about 40 g/L (dry wt) and appears to have the potential to go even higher. Major advantages of this probe system are the ease of measurement and the on-line ability to measure very frequently, due to its nondestructive mode of operation. Thus, the probe obviates the need for manual sampling and reduces the risk of contaminating the culture. But, more significantly, it enables one to implement on-line schemes including feedback control.
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  • 50
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    Biotechnology and Bioengineering 27 (1985), S. 743-755 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Based on batch cultivation data for the production of L-glutamic acid from glucose, a comparative evaluation was made for repeated batch cultivations using one and more fermentors. The problem was formulated as maximizing the productivity of metabolic product with the specified conversion with respect to the cell age and the volume fraction used as seed for the subsequent repeated batch cultivation. Simulations were carried out with the assumption of no lag in product formation for the cases where the total operation time was specified as 200 h with reproducible batch cultivation cycles. The product production was assumed to be solely a function of product concentration. The computation results show the advantage of using more than one fermentor from the viewpoints of productivity and conversion, which will apply in general to non-growth-associated product production with delay time. In particular, three fermentors are recommended for the production of L-glutamic acid chosen as an example in this article.
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  • 51
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    Biotechnology and Bioengineering 27 (1985), S. 761-768 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The increasing interest in alcohol fermentation over these last years because of the energy crisis has been demonstrated by an increase in scientific research. After a brief analysis of the main results of the literature in the field of alcohol fermentation reactors, the use of a new type of immobilized cell reactor [the rotating biological surface (RBS) reactor] was studied. As is well known, the RBS reactor is a form of fixed-film reactor and can be described as a dynamic trickling filter. Our experimental apparatus employed a spongy material to trap the yeast cells on the disks. The results of fermentations carried out in the RBS reactor working in batch, in continuous with cell support, and in continuous without cell support have been presented in order to compare the different productivities and to assess the performance of the RBS immobilized cell reactor. An ethanol productivity of 7.1 g/L h was achieved in the RBS-ICR at a dilution rate of 0.3 h-1, 2.5 times higher than the maximum productivity obtained in the RBS reactor without support at a lower dilution rate. The adoption of a spongy material as a cell immobilizer, combined with the use of the RBS reactor, enhances the particular advantages of both systems.
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  • 52
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    Biotechnology and Bioengineering 27 (1985), S. 769-775 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: As part of the development of a comprehensive mathematical model for chitinase production by Serratia marcescens QMB 1466 growing on chitin, the different mass transport and kinetic steps involved during chitin hydrolysis were studied. The experimental results for the hydrolysis of chitin by a crude preparation of chitinase show a system kinetically limited by the overall rate of chitin hydrolysis. This rate is linearly related to the concentration of enzyme adsorbed on the chitin particle. Adsorbed and bulk enzyme concentration were found to be related through a Langmuir type of isotherm.
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  • 53
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    Biotechnology and Bioengineering 27 (1985), S. 792-799 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The balances of reductivity and high-energy bonds (HEB) during microbial growth on glucose (a standard substrate), methanol, and ethanol are reported. Also, numerical values for the quantities of HEB formation in the respiratory metabolism, HEB consumption in the constructive metabolism, as well as in a number of the other intracellular processes are evaluated. Estimations of maximum cell yields by mass and energy are made during growth on methanol and ethanol with regard to peculiar features of different microbe metabolism.
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  • 54
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    Biotechnology and Bioengineering 27 (1985), S. 800-806 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new hybrid reactor, the upflow blanket filter (UBF), which combined on open volume in the bottom two-thirds of the reactor for a sludge blanket and submerged plastic rings (Flexiring, Koch Inc., 235 m2/m3) in the upper one-third of the reactor volume, was studied. This UBF reactor was operated at 27°C at loading rates varying from 5 to 51 g chemical oxygen demand (COD)/L d with soluble sugar wastewater (2500 mg COD/L). Maximum removal rates of 34 g COD/L d and CH4 production rates of 7 vol/vol d [standard temperature and pressure (STP)] were obtained. The biomass activity was about 1.2 g COD/g volatile suspended solids per day. Conversion (based on effluent soluble COD) was over 93% with loading rates up to 26 g COD/L d. At higher loading rates conversion decreased rapidly. The packing was very efficient in retaining biomass.
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  • 55
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    Biotechnology and Bioengineering 27 (1985), S. 807-817 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In addition to the role of maintaining the pH, buffers can also facilitate the transport of H+ ions in acid-generating systems. The role of this facilitation in proton transport in porous pellets on acid-generating immobilized enzymic reactions is examined. The activity in these systems can be maximized by a proper control of facilitation, which involves the determination of the appropriate variables out of (1) the concentration of the weak acid, (2) the pH of the medium, (3) the bulk substrate concentration, and (4) the type of weak acid. Since the intrinsic activity (IA) of the immobilized enzyme is such that it exhibits an optimum with respect to the pH, a partial (optimal) removal of diffusional limitation by facilitation maximizes the activity when the bulk pH is larger than this optimum pH. A complete removal of diffusional limitations, however, maximizes the activity when the bulk pH is less than or equal to the above optimum pH. The control of the diffusional resistance can be achieved by controlling the extent of facilitation, hence by adjusting the parameters mentioned above. Computations have been carried out to examine the effect of each of these parameters on the activity of the immobilized enzyme. It is found that when the bulk pH is less than or equal to the optimum pH of the intrinsic activity of the immobilized enzyme, there exists a lower limit on the amount of weak acid required to maximize the activity. However, an optimum amount of weak acid is required to maximize the activity when the bulk pH is higher than that optimum pH. For a given activity the amount of weak acid is minimal if the pK of the weak acid is close to the bulk pH. The effect of coupling between the proton and substrate transport on activity control is also examined and the effect of geometry on activity is evaluated for spherical, cylindrical, and flat-plate configurations.
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  • 56
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    Biotechnology and Bioengineering 27 (1985), S. 832-836 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This study deals with characterizing the extracellular xylanases produced by a strain of the thermophilic bacterial genus Thermomonospora. Supernatant from centrifuged fermentation broth was used as a crude enzyme preparation. From pH 5.5 to pH 7.7 the temperature optimum based on a 10-min assay of activity was 80°C. The crude enzyme had a half-life of approximately 1 month when stored at 55°C at pH 6.5. The enzyme produced a mixture of xylose oligomers from xylan, with xylobiose occuring in greatest quantity on a molar basis. Only trace quantities of xylose were produced by this hydrolysis.
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  • 57
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    Biotechnology and Bioengineering 27 (1985), S. 852-860 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Batch fermentations were run at varying agitation rates and were either pressurized to 1 bar (15.2 psig) or nonpressurized. Agitation and pressure both affect the level of dissolved hydrogen gas in the media, which in turn influences solvent production. In nonpressurized fermentations volumetric productivity of butanol increased as the agitation rate decreased. While agitation had no significant effect on butanol productivity under pressurized conditions, overall butanol productivity was increased over that obtained in the nonpressurized runs. Maximum butyric acid productivity, however, was found to occur earlier and increased as agitation increased. Peak hydrogen productivity occurred simultaneously with peak butyric acid productivity. The proporation of reducing equivalents used in forming the above products was determined using a redox balance based on the fermentation stoichiometry. An inverse relationship between the final concentrations of acetone and acetoin was found in all fermentations studied. The results show that agitation and pressure are important parameters for solvent productivity in acetone-butanol fermentation.
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  • 58
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    Biotechnology and Bioengineering 27 (1985), S. 842-851 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Immobilization experiments have been performed with glucose oxidase as enzyme and controlled-pore glass of different pore sizes as support for chemical coupling. The experimental results have been analyzed for comparison with the theoretical model predictions. Analysis of the initial stage of the process gives the fundamental characteristic of the immobilization reaction. These investigations allow us to study the influence of the degree of diffusional restriction on the evolution of the immobilization process and spatial distribution of immobilized enzyme. Nonuniformly distributed concentrations have been achieved within the porous matrix, and suggestions have been made in designing such profiles by choosing appropriate experimental parameters.
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  • 59
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    Biotechnology and Bioengineering 27 (1985), S. 870-876 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new technique is presented for the production of immobilized biocatalysts in large quantities. It consists of breaking up a jet of the biocatalyst/presupport mixture in uniform droplets by means of a resonance technique. Entrapment of yeast and plant cells in calcium alginate has been used as the model. The production capacity of the nozzles used (0.5, 0.8, and 1.1 mm exit diameters) is two orders of magnitude larger than the production capacity of the conventional techniques (maximum capacity with a 1.1-mm nozzle diameter is 24 L/h). Depending on frequency, nozzle diameter, and volumetric flow rate, the bead size varies between 1 and 2 mm, with standard deviations of 3-5% for yeast immobilization and 10-15% for plant cells. The deactivation of both yeast and plant cells is small and comparable to that found in the corresponding conventional procedures.
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  • 60
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    Biotechnology and Bioengineering 27 (1985), S. 890-892 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 61
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    Biotechnology and Bioengineering 27 (1985), S. 905-908 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Tab.
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  • 62
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Kluyveromyces fragilis immobilized in calcium alginate gel was compared to Saccharomyces cerevisiae coimmobilized with β-galactosidase, for continuous ethanol production from whey permeate in packed-bed-type columns. Four different whey concentrations were studied, equivalent to 4.5, 10, 15, and 20% lactose, respectively. In all cases the coimmobilized preparation produced more ethanol than K. fragilis. The study went on for more than 5 weeks. K. fragilis showed a decline in activity after 20 days, while the coimmobilized preparation was stableduring the entrire investigation. Under experimental conditions theoretical yields of ethanol were obtained from 4.5 and 10% lactose substrates with the coimmobilized system. Using 15% lactose substrate, theoretical yields were only obtained when a galactose-adapted immobilized S. cerevisiae column was run in series with the coimmobilized column. Then a maximum of 71 g/L ethanol was produced with a productivity of 2.5 g/L h. The coimmobilized column alone gave a maximum ethanol concentration of 52 g/L with a productivity of 4.5 g/L h, whereas immobolized K. fragilis only produced 13 g/L ethanol with a productivity of 1.1 g/L h. It was not possible to obtain theoretical yields of ethanol from the highest substrate concentration.
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  • 63
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    Biotechnology and Bioengineering 27 (1985), S. 953-960 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In enzymatic synthesis of cephalexin from D-α-phenylglycine methyl ester (PGM) and 7-amino-3-deacetoxy-cephalosporanic acid (7-ADCA) using α-acylamino-β-lactam acylhydrolase from Xanthomonas citri, it was found that this enzyme catalyzes all three reactions including PGM hydrolysis, cephalexin synthesis, and cephalexin hydrolysis. Based on our experimental results, a mechanistic kinetic model for cephalexin synthesizing enzyme system having acyl-enzyme intermediate was proposed. From this kinetic model, the reaction rate equations for three reactions were derived, and the kinetic parameters were evaluated. A good agreement between the simulation results and the experimental results was found.
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  • 64
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    Biotechnology and Bioengineering 27 (1985), S. 909-913 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This study is concerned with characterizing cell-bound inducible β-xylosidase produced by a strain of the thermophilic bacterial genus Thermomonospora. A crude preparation of this enzyme recovered from sonicated cells of this organism displayed high activity against paranitrophenyl-β-xylopyranoside over a pH range of 5.5-7.7. The temperature optimum, based on a 30-min assay of activity, at pH 6.5 was 70°C. The crude enzyme had a thermal half-life of approximately 1 week at 55°C and pH 6.5. Xylose inhibited the enzyme. Values of Km and Vmax are estimated from the reaction rate data as 0.82 mM and 8 U/L, respectively.
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  • 65
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    Biotechnology and Bioengineering 27 (1985) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 66
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    Biotechnology and Bioengineering 27 (1985), S. 917-920 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An electronic liquid level control system was developed to maintain constant working volume in a continuously fed and aerated fermentor from which spent medium was continously withdrawn by microfiltration in an external recycle loop. The level control system was comprised of an admittance sensor in the fermentor and an external transmitter and controller, which together regulated the speed of a recycle pump and thus the rate of liquid withdrawal from the fermentor. During test bacterial culture the liquid level was maintained usually within ± 1% and always within ± 5%. The control system could be applied to various other types and scales of continuous-flow fermentors.
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  • 67
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    Biotechnology and Bioengineering 27 (1985), S. 921-931 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model has been developed for a fixed-film biological process (film flow over a flat plate) that describes bulk liquid transport, diffusional transport of oxygen and organics across a stagnant film, diffusional transport of oxygen and organics into the biofilm, biochemical reactions by the individual cells within the biofilm, biofilm growth, and cell density changes within the biofilm due to cellular decay. Simulation studies are presented to show how contact time and diffusion layer thickness affect process performance.
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  • 68
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    Biotechnology and Bioengineering 27 (1985), S. 972-979 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This report describes the use of an anthraquinone mediated fuel cell for the direct production of electrical energy from sulfonated lignin and Kraft Black Liquor. The cell produces the equivalent of 1 kWh for each 2-3 lb sulfonated lignin and 5-8 lb black liquor combustibles. In the case of the sulfonated lignin, chain session occurs during the oxidation process, reducing the molecular weight from ca. 2 × 104 to less than 1000 D.
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  • 69
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    Biotechnology and Bioengineering 27 (1985), S. 984-995 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Zymomonas mobilis was grown in continuous cultures at 30 and 35°C. The specific substrate consumption rates at 35°C were higher than those at 30°C. An unstructured mathematical model based on the linear equation for substrate consumption provided a statistically adequate description for cultures grown at 35°C but not for cultures grown at 30°C. A structured two-compartment model described growth and substrate consumption well at both temperatures. Some theoretical and practical aspects of the two-compartment model are discussed.
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  • 70
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    Biotechnology and Bioengineering 27 (1985), S. 1005-1011 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A newly designed batch calorimeter was used to investigate the degradability of some celluloses having varying degrees of crystallinity. The PTC of an aerobic culture of Cellulomonas uda ATCC 21399 obtained revealed a diauxic growth which is attributed to the presence of hemicellulose contaminating Avicel and MN300 cellulose. The microcrystalline celluloses used were not completely utilized, whereas amorphous cellulose was easily metabolized, indicating that under the growth conditions used here, the physical structure of cellulose strongly influenced its microbial degradability. An equivalent growth yield of ca. 0.44 g/g was found with all the substrates used. The heat evolved by metabolism of 1 g cellulose was -5.86 kJ/g, a value similar to that obtained with glucose culture. The growth rate was the only variable parameter. The data obtained showed as expected that the hydrolysis product of cellulose was consumed in the same way as that of glucose and that the only limiting factor to the biodegradability of cellulose was the breakdown of the polymeric substrate. It is concluded that data obtained with glucose metabolism can be used to evaluate the extent of cellulose degradation.
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  • 71
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    Biotechnology and Bioengineering 27 (1985), S. 1021-1026 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Human embryonic kidney cells grown as an attached, confluent monolayer on a flat substrate were subjected to steady, uniform laminar flow of medium in a specially designed chamber in which flow patterns and shear stress are accurately defined and controlled. Experiments were performed for shear stress levels ranging from 0.2 to 6.0 N/m2 with times of exposure to the shear stress ranging from 2 to 24 h. The influence of the shear field was slight at low shear stress (0.26 N/m2). Higher stress levels (0.65 N/m2 and higher) had significant effects on cell morphology, and on the post-shear release of urokinase enzyme. Still higher stress levels (2.6 N/m2 and higher) caused marked reduction in cell viability. These results may be of interest in addressing practical problems in developing commercial biosynthesis reactors.
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  • 72
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    Biotechnology and Bioengineering 27 (1985), S. 1027-1035 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A computer model based on a previous model for aerobic growth of Escherichia coli is described which simulates cell composition, size, and shape; length of C and D periods; cell yields; and the rate of product formation of anaerobically grown cells of E. coli B/r-A on glucose-limited minimal medium. To verify the simulation results, the values of cell volume, cell content of DNA, RNA, and protein, substrate yield, ATP yield, and fermentation products for various growth rates were obtained experimentally. Model predictions are in good agreement with experimental results. Such agreement supports a hypothesis that only those equations describing energy metabolism need to be modified and other cell functions are not grossly altered by a switch from aerobic to an aerobic growth. The model's ability to predict reasonable growth responses under anaerobic conditions by only modifying energy metabolism is a further indication of the robust nature of the description of cell physiology included in the development of the aerobic model.
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  • 73
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    Biotechnology and Bioengineering 27 (1985), S. 1056-1059 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 74
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    Biotechnology and Bioengineering 27 (1985), S. 1060-1062 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 75
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    Biotechnology and Bioengineering 27 (1985), S. 1063-1066 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 76
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model substrate, Solka Floc BW 200, was semicontinuously hydrolyzed in an aqueous two-phase system based on crude dextran and polyethylene glycol over a period of more than 450 h. With an initial concentration of 75 g/L and intermittent addition of cellulose an average concentration of 50 g/L sugar was semicontinuously produced at dilution rates of 0.006-0.012 h-1. The conversion of substrate varied between 49 and 66%. The enzyme consumption measured as FPU/g reducing sugar (RS) produced could be reduced by a factor two when compared to a batch process since, in the aqueous two phase system investigated, the enzyme could be recycled two times.
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  • 77
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    Biotechnology and Bioengineering 27 (1985), S. 1051-1055 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A computer model is described that simulates a population of Escherichia coli B/r-A cells growing under anaerobic conditions. This population model is an ensemble of single-cell models. The ability of the model of predict the dynamic response of a cell population in a CFSTR to a change in feed flowrates or concentrations was investigated. With glucose as the limiting nutrient the feed concentration of glucose was shifted from 1.0 to 1.88 g/L. With a fixed concentration of glucose (1.0 g/L) step changes in residence time (4.1-1.95 h) were examined. The predicted changes of cell size distribution, substrate concentration, RNA content, and cell dry weight during the transition period compared reasonably well to those observed experiementally. We believe this model is the only model currently available that can make such predictions on an a priori basis.
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  • 78
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    Biotechnology and Bioengineering 27 (1985), S. 1067-1069 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 79
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    Biotechnology and Bioengineering 27 (1985), S. 1081-1084 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
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  • 80
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    Biotechnology and Bioengineering 27 (1985), S. 1077-1080 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Various supports and bio-reactors have been proposed. Packed bed reactors with polymer material in granular shape are most often employed in both laboratory and industry. But they have a disadvantage related to an increase in pressure drop. We already developed filter paper composed of short cut pieces of superfine filaments (SFF). It shows high performance, but its hydrodynamic resistance increases when substrate solution passes through it. A new type of enzyme reactor equipped with knitted SFF has been proposed. In this reactor, substrate does not pass through the support but flows along the thin channel and parallel to the support. Therefore, it is able to maintain flow rate constant during a considerable period. The productivity of the reactor fairly increases by reducing the thickness of the channel because linear velocity increases with the reduction of the thickness and that contributes to the decrease in mass transfer resistance.
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  • 81
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    Biotechnology and Bioengineering 27 (1985) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 82
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    Biotechnology and Bioengineering 27 (1985), S. 1095-1101 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aspergillus japonicus was grown in the presence of various aromatic compounds at 0.1 and 1 mg/mL, and extracellular xylanase and arabanase activities were measured. Some of the aromatic compounds tested, especially at the higher concentration, suppressed the appearance of hemicellulase activities, expressed as xylanase or arabanase. Vanillin at 1 mg/mL in the presence of either xylan or araban completely suppressed growth, and guaiacol and p-coumaric acid markedly inhibited the growth of A. japonicus. The effects of the aromatic compounds on the activity of crude enzyme preparations were also ascertained. In vitro arabanase activity was affected more than xylanase activity.
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  • 83
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    Biotechnology and Bioengineering 27 (1985), S. 1108-1114 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Alcoholic fermentation represents a significant example of production of compounds utilizable as alternative energy sources. High ethanol concentration in the fermented wort is needed in order to reduce the energy consumption in the process of alcohol recovery. A particular Saccharomyces strain, of the oviformis species, obtained from fermented worts exhibiting high ethanol concentrations is studied and compared with a common S. cerevisiae strain in order to show its skill in fermenting very concentrated sugar solutions with an energy saving of ca. 10%.
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  • 84
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    Biotechnology and Bioengineering 27 (1985), S. 1126-1135 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article deals with the mathematical modeling of the process of enzyme immobilization in porous membranes. During the initial period, an analytical solution is available to extract the rate constant for immobilization. Beyond this period, the model equations are solved numerically to yield the transient response of the enzyme concentration in the immobilizing solution and also the evolution of the enzyme loading profile inside the membrane. It is found that the immobilization practically ceases even through the attachment sites are still available within the membrane.
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  • 85
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    Biotechnology and Bioengineering 27 (1985), S. 1122-1125 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sugar compounds present in chopped solid-sweet sorghum particles were fermented to ethanol in a rotarydrum fermentor (RDF) using an ethanol tolerant yeast strain. The influence of rotational speed of the RDF on the rate of ethanol fermentation was investigated and compared with static flask experiments. The rate of ethanol formation decreased with increasing rotational speed. The maximum rate and extent of ethanol formation were ca. 3.1 g EtOH/L h (based on expressed juice volume) and ca. 9.6 g EtOH/100 g mash, respectively, at 1 rpm rotational speed.
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  • 86
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    Biotechnology and Bioengineering 27 (1985), S. 1136-1145 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An analytical model for dissolved oxygen concentration in an algal minipond was used to develop a new method for estimating, on-line, the net O2 production rate (OPR) of the biological process. The method was tested experimentally and was found to provide crucial information on the vitality of the biological process and to provide an early warning of a possible forthcoming collapse of the ecosystern. It is suggested that the newly developed model and measurement method could provide investigators with useful tools for optimization of algal cultivation in the laboratory and plant.
    Additional Material: 5 Ill.
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  • 87
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1152-1165 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: One of the serious problems limiting the application of full-scale anaerobic fixed film processes is reactor startup. To better understand startup, studies with downflow stationary fixed film (DSFF) reactors were conducted to characterize the effects of influent concentration, support material, and surface-to-volume ratio on biofilm development and overall reactor performance. Materials with roughened surfaces gave the best startup performance and as expected increased surface area in the reactors led to more rapid increases in loading rates and higher ultimate loadings. Soluble influent COD concentrations between 5 × 103 and 2 × 104 mg/L influenced the rate of biofilm development. Lower COD concentrations resulted in faster development of the biofilm, even though ultimate loadings were not necessarily achieved as rapidly as in reactors fed higher strength wastes. No decrease in specific activity of the biofilms in each reactor was observed as the thickness of the biofilms increased to their maximum value at the ultimate loadings. The operation of reactors fed lower strength wastes was more stable than reactors receiving higher strength feeds at comparable loadings. Biofilm yield and activity, COD removals, suspended growth and activity, and other system parameters are discussed.
    Additional Material: 10 Ill.
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  • 88
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1185-1191 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The hollow fiber enzyme reactor with pulsation developed by Kim and Chang (1983) was operated in a differential mode by recycling a substrate solution, in order to assess the efficiency of ultrafiltration swing. The rates of lactose conversion by β-galactosidase contained in the shell side of the reactor were measured to determine the effects of recirculation rate, pulsation period, and amplitude. The conversion increased with the increase of recirculation flow rate and the amplitude while variation in period affected the conversion relatively little. The maximum increase of 113% in the activity was observed in the reactor with pulsation as compared to that without pulsation. The two-compartment model well described the experimental data obtained in this study. Square-wave pulsation was theoretically more effective in increasing conversion than sine wave pulsation. However, in experimental operation the damping effect of the hollow fiber wall narrowed the difference between these two wave forms.
    Additional Material: 12 Ill.
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  • 89
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1214-1222 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The optimal periodic operation of the biological reactor was studied from the standpoint of the two-objective programming problem. The noninferior set with respect to the cell productivity and the conversion of the substrate into the biomass was determined by use of the optimization technique due to Miele. It was shown that the noninferior set was composed in general of the repeated batch branch and the repeated fed-batch branch, which occupy the high-productivity portion and the high-conversion portion of the noninferior set, respectively. However, the latter branch disappears in the case of growth kinetics with no substrate inhibition. In addition, the extreme points of the noninferior set yielding the maximal productivity and the maximal conversion represent such operations that are equivalent to the steady-state operation (chemostat culture) and the batch operation, respectively.
    Additional Material: 9 Ill.
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  • 90
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1236-1245 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An adaptive on-line optimization method that utilizes dynamic model identification has been applied to maximize the cellular productivity of a continuous bakers' yeast culture. Experiments were conducted on a sophisticated computerized fermentation system. Experimental results show that the adaptive on-line optimization method requires very little a priori information, is easy to implement, converges quickly, adapts to changes in the process, and is stable even when operational difficulties are encountered.
    Additional Material: 9 Ill.
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  • 91
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1199-1207 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It has been shown that the Upflow Anaerobic Sludge Bed (UASB) system data reported earlier1 cannot be explained by simple Monod-type substrate consumption patterns. An autoinhibition model was also ruled out because the substrate concentration range over which hysteresis was observed was much larger than such a model would predict. However, propionic and acetic acids were found to inhibit each other's conversion machineries. Since in the UASB system the biocatalyst is flocculated, it was found that a model additionally incorporating this facet of the reactor set-up could explain the steady-state data very well. Using the parameters generated from steady-state data and data from butyric acid step change,1 i.e., the entire set of parameters (Table I), a very good agreement between predicted and observed data was found. International Mathematical and Statistical Libraries (IMSL) and Upjohn's NONLIN library combined with various root-finding and integrating subroutines were used for parameter estimation. The model thus described was used to predict the response of the UASB system when acetic acid and propionic acid influent concentrations were stepped-up/down. The agreement between the predicted and observed data was found to be excellent in each case during the step-up schedule. During the step-down the data seemed to indicate that the UASB system, like any other chemostat, responded faster than predicted. This could be due to the fact that when the culture has to “gear up” part of the lag time is the time required for the cell to produce the requisite amount of enzymes. In the case of “gearing down” this time is not required and the system responds faster.
    Additional Material: 19 Ill.
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  • 92
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1229-1235 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: During the steady-state continuous culture of Saccharomyces cerevisiae on sugar cane blackstrap molasses under different experimental conditions, oscillatory variations of the invertase activity of the intact yeast cells were observed. The continuous morphological changes of the cells wall and of the periplasmic space affecting the interaction between invertase and sucrose molecules could be responsible by the observed oscillatory phenomena. The average invertase activity at the steady state is linearly correlated to the cell's growth rate.
    Additional Material: 8 Ill.
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  • 93
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1223-1228 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Insulin production requires a prolonged extraction process. An ultrasound method of insulin extraction was developed to increase efficiency. Application of ultrasound resulted in a significant increase in the extraction process as a result of pancreas tissue dispergation, destruction of the pancreas cells, intensive mixing, separation of particles, and increase in the interphase pancreas-extractive medium. Optimal technological parameters of insulin extraction were established: ultrasound frequency, 19.5 kHz, specific intensity of ultrasound, 3.3 W/cm2; time of ultrasound exposure, 5-10 min; and influence of cavitation process. Effectiveness of insulin extraction depends on the properties of the extractive medium. Optimal conditions were pH, 1.6-1.7, concentration of alcohol, 75%, temperature of extractive mixture, 13-17°C; ratio of ground pancreas to liquid extractive medium, 1 : 3.
    Additional Material: 10 Ill.
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  • 94
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1270-1273 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Studies have been conducted in a gas circulation type fermentor in order to characterize the ethanol fermentation of uncooked cassava starch with Rhizopus koji. Results showed that ethanol concentration reached 13-14% (v/v) in 4-day broth, and the maximum productivity of ethanol was 2.3 g ethanol/L broth h. This productivity was about 50% compared to the productivity of a glucose-yeast system. Ethanol yield reached 83.5-72.3% of the theoretical yield for the cassava starch used. The fermentor used in the present work has been proven by experiment to be suitable for ethanol fermentation of the broth with solid substrate.
    Additional Material: 4 Ill.
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  • 95
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1258-1269 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The microbial epoxidation of propene and 1-butene was used to study some fundamental aspects of two-liquid-phase biocatalytic conversions. Introduction of a water-immiscible organic solvent phase in a free-cell suspension gave rise to a series of undesired phenomena, e.g., inactivation by the solvent, clotting of biomass, and aggregation of cells at the liquid-liquid interface. Immobilization of the cells in hydrophilic gels, e.g., calcium alginate, prevented direct cell-organic solvent contact and the related clotting and aggregation of biomass. However, the gel entrapment did not seem to provide additional protection against the organic solvent. The influence of various organic solvents on the retention of immobilized-cell activity was related to solvent properties like the polarity (as expressed by the Hildebrand solubility parameter) and the molecular size (as expressed by the molecular weight or molar volume). High activity retention was favored by a low polarity in combination with a high molecular weight. The solubility parameter also proved useful to describe the capacity of various organic solvents for oxygen and alkene oxides. This facilitated the optimization of the solvent polarity.
    Additional Material: 10 Ill.
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  • 96
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 97
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1277-1281 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Immobilized whole cells of Clostridium butyricum reduced both NAD+ and NADP+ in the presence of hydrogen at a pressure of 100 atm. The NAD+ and NADP+ reduction activities were 4.45 and 4.30 U/g dry cells, respectively [U = NAD(P)H regenerated, μ mol/min]. The amount of NADH regenerated by immobilized cells increased with increasing hydrogen pressure above 10 atm. Immobilized cells (6 mg dry cells) of Cl. butyricum completely converted NAD+ (6.4 μmole) to NADH for 5 h, whereas only 60% of NAD+ were reduced by free cells. Immobilized cells retained 89% activity after the 5-h reactions were repeated 4 times. L-Alanine was continuously produced at the rate of 12.8 μmol/min g dry cells from hydrogen, ammonium, and pyruvate with immobilized Cl. butyricum-alanine dehydrogenase.
    Additional Material: 5 Ill.
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  • 98
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1291-1296 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mixed cultures of bacteria grew in medium containing real s-triazine wastes as nitrogen source. About 80% of the s-triazine waste could be degraded as determined by HPLC and by measurements of dissolved nitrogen. The culture required an added carbon source in order to degrade s-triazines. A temperature optimum near 40°C was observed and a salt concentration above about 4% markedly retarded growth and the degradation of s-triazines. This system was examined as a biological treatment for wastes from syntheses of s-triazines.
    Additional Material: 6 Ill.
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  • 99
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1306-1311 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A significant portion of the total biodegradative activity toward synthetic compounds may involve cometabolism; thus, the latter represents an important type of microbial process. A mixed microbial population acclimated to highstrength industrial wastewater degraded about 90% of the organic carbon present in the wastewater. A reasonable agreement in the carbon balance provided clear evidence for the biodegradability of residual organic species. Based on the growth expression of Haldane to account for substrate inhibition, a substrate utilization model to quantify the role of cometabolism coupled with cellular maintenance is proposed. The kinetic parameters of the model have been estimated from experimental data. If the maintenance values are assumed negligible, as has been observed for wastewater systems, it is possible to quantify the magnitude of co-metabolism encountered in the biological oxidation of synthetic organic compounds.
    Additional Material: 7 Ill.
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  • 100
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1320-1327 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The fermentation and recovery of the EcoRl restriction endonuclease with a genetically modified Escherichia coli strain is investigated. Vast amounts of product could be obtained after cultivation in a 20-L computer-coupled pilot fermentor and purification of the recovered wet cells. It was found that in the end the product is at least inhibitory and probably lethal to the cells (the lethality has been proven with genetic experiments) so that optimum yield requires an optimized choice for the time instant of induction. Growth after induction and product formation require substantial amounts of oxygen, which must be supplied if a high population level is to be achieved. pH control may alleviate the burden of high oxygen supply. Quantitative assessment after the different purification stages indicate that approximately 15% active enzyme can be obtained from the total amount produced.
    Additional Material: 5 Ill.
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