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  • 1990-1994
  • 1980-1984  (530)
  • 1981  (530)
  • Biochemistry and Biotechnology  (318)
  • Physical Chemistry  (123)
  • Gas chromatography  (89)
  • Nuclear reactions
Material
Years
  • 1990-1994
  • 1980-1984  (530)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 75 (1981), S. 179-183 
    ISSN: 1432-2072
    Keywords: DMT ; Gas chromatography ; Hyperactivity ; Pargyline ; SKF-525A ; Mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Mice pretreated with the monoamine oxidase inhibitor pargyline showed a dose-dependent increase in hyperactivity for up to 2 h following injections of N,N-dimethyltryptamine (DMT: 0.5–8.0 mg/kg). Hyperactivity was related to a linear increase in whole brain concentrations of DMT as measured by a new sensitive gas chromatographic assay. The duration of this behaviour paralleled the concentration of DMT in the brain from 15–120 min. However, at 15 min, there was no significant difference in brain DMT concentrations between mice receiving pargyline and those given distilled water at the two dose levels of DMT studied (2.0 and 8.0 mg/kg). Pre-treatment with the microsomal enzyme inhibitor SKF-525A, alone or in combination with pargyline, had no effect on the DMT-induced behaviour or on the brain levels of DMT.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 48 (1981), S. 99-106 
    ISSN: 1432-1246
    Keywords: Urine analysis metabolites ; Gas chromatography ; Hexane ; Cyclohexane ; Biological monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A gas chromatographic method for analyzing the urinary metabolites of n-hexane (2-hexanol, 2,5-hexanedione, 2,5-dimethylfuran and γ-valerolactone), of 2-methylpentane (2-methyl-2-pentanol), of 3-methylpentane (3-methyl-2-pentanol), and of cyclohexane (cyclohexanol) was developed. Processing of urine and the gas chromatographic conditions are described. The recovery rate of all hexane metabolites, except 2,5-dimethylfuran, ranged between 92 and 100%. The variation coefficient of metabolites determination was between 1.5 and 5%, apart from 2,5-dimethylfuran determination for which the variation coefficient was 15%. The detection limits ranged between 0.2 and 0.7 mg/1 and between 0.05 and 0.1 mg/1 when a packed or capillary column was used. Results obtained from a packed and capillary column are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 49 (1981), S. 115-123 
    ISSN: 1432-1246
    Keywords: Blood analysis of solvents ; Gas chromatography ; Head space ; Toxicokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The determination of toluene, benzene, ethylbenzene and trichloro-ethylene in blood by means of a gas chromatographic head space technique is presented. Internal standards are added to the blood samples in the form of water solutions of volatile hydrocarbons in proportion 2:1. This enables application of the internal standard within the broad range of concentrations and in addition increases significantly the concentrations of investigated compounds in the gas phase of incubation vessel. Elaborated methods were applied for determinations of ethylbenzene in blood samples collected after experimental inhalation exposure and for evaluation of the rate of disappearance of benzene, toluene and trichloro-ethylene from blood after acute accidental or suicidal intoxications.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 48 (1981), S. 319-324 
    ISSN: 1432-1246
    Keywords: Chlorophenols ; Gas chromatography ; Hexachlorocyclohexane ; Metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A sensitive and specific gas chromatographic method is described for the simultaneous determination of ten chlorinated phenols that appear in the urine of persons exposed to hexachlorocyclohexane (HCH). The phenolic compounds in the urinary samples are hydrolysed in an acidic medium and derivatised with acetic anhydride. This sample treatment permits routine application. The stationary phase (8% DC 200 on Chromosorb G AW-DMCS possesses a high separating capability for the acetic esters of the chlorophenols. The detection limits lie between 4.9 and 18.6 μg/l and allow determinations even in the environmentally interesting concentration range. The recoveries determined using aqueous standards range between 87 and 119% and the relative standard deviations are between 4.4 and 10.1%.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 315 (1981), S. 219-225 
    ISSN: 1432-1912
    Keywords: 3-Methoxytyramine ; Haloperidol ; Dopamine release ; Dopamine agonists ; Gas chromatography ; Mass Spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The value of 3-methoxytyramine (3-MT) as an indicator of impulse-related dopamine (DA) release has been assessed in rat corpus striatum. Moreover, the turnover of 3-MT was estimated by measuring its disappearance rate after COMT inhibition. Quantitation of 3-MT and DA was performed by gas chromatography/mass spectrometry (selected ion monitoring). Haloperidol in doses between 0.05 and 3 mg/kg p.o. did not increase endogenous 3-MT levels at any time up to 24 h after its administration, whereas it dose-dependently increased homovanillic acid and 3,4-dihydroxyphenylacetic acid. However, in doses above 0.1 mg/kg p.o., it enhanced the accumulation of 3-MT in clorgyline-pretreated animals. Conversely, baclofen in doses of 2 mg/kg i.p. and above decreased endogeneous 3-MT levels, but reduced the accumulation of this amine only poorly at 20 mg/kg i.p. in clorgyline-pretreated rats. A number of dopamine agonists, apomorphine (0.5 mg/kg i.v.), dipropyl-ADTN (0.03 mg/kg i.v.), but not bromocriptine (1 mg/kg i.v.) reduced endogenous 3-MT levels 10 min after administration by approximately 50%. The DA releasing agents d-amphetamine and methylphenidate showed different effects: the former increased endogenous 3-MT greatly, whereas the latter was without effect. The difference is likely to be related to the MAO inhibitory properties of amphetamine. 3-MT disappeared rapidly after COMT inhibition with 50 mg/kg i.v. tropolone (half-life of the initial disappearance about 1 min). The curve flattened off after 5–10 min. Turnover was calculated to be about 7 nmol/g/h, which corresponds to about a third of the turnover of DA. Our results suggest that an important part of DA metabolism occurs through 3-MT and that this amine is very effectively deaminated by MAO-A, so effectively indeed that increased formation does not increase its endogeneous levels. It appears, therefore, that 3-MT is not suitable as an indicator of increased DA release. However, it seems to have some value for an assessment of lowered DA release.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 19-22 
    ISSN: 1612-1112
    Keywords: Teflon columns ; Chemically modified teflon ; Gas chromatography ; Capillary columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Wall-coated open tubular columns prepared from chemically modified teflon tubing have been developed for gas chromatography. Chemical reaction of the inner walls of teflon tubing allows bonding of an adhesive layer on which a variety of stationary phaes can be coated. Test mixtures of alkanes and alcohols were used to investigate the chromatographic properties of these columns and the stability and mixing of the adhesive and stationary phae layers. the results in dicate that mixing of the layers is negligible and that the column is stable for a long period of time.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 55-66 
    ISSN: 1612-1112
    Keywords: Capillary columns, glass ; Gas chromatography ; Column preparation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Kapillar-Gas-Chromatographie ist heute das sich am stärksten entwickelnde Gebiet der Gas-Chromatographie. Es gibt viele komplexe, neue Fragestellungen in der Analytik, welche den Einsatz spezieller Kapillarsäulen erfordem. Glücklicherweise gibt es aber auch eine große Zahl von Herstellungsverfahren für Kapillarsäulen, welche — noch mehr als bei der Herstellung von gepackten Säulen — eine Anpassung an die gestellten Aufgaben ermöglichen. In diesem Artikel werden die Herstellungsverfahren für Kapillarsäulen zusammengestellt und Anregungen gegeben, wie aufgaben-orientierte Säulen erreicht werden.
    Notes: Summary Glass capillary column chromatography is the most rapidly growing part of gas chromatography. There are many complex new analytical tasks and they require special capillary columns, Fortunately there is a wide range of column preparation methods available, and they make the preparation of glass capillary columns a more varied job than that of packed columns. In this paper these methods are reviewed and suggestions are given for making task-oriented columns.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Urea herbicides ; Catalytic hydrolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the rapid catalytic hydrolysis of phenylurea herbicides on silica gel at elevated temperatures. After derivatisation of the anilines produced with heptafluorobutyric acid anhydride final analysis is done on a gas chromatograph equipped with an electroncapture detector. Detection limits are in the 1–5 picogram range. The method has successfully been applied to residue analysis of water samples at the 1 ppb level. The determination of free anilines present in water samples and the potential of various techniques to be used to discriminate between free anilines and parent herbicides are also discussed.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Graphitised carbon black ; Phenols ; Water pllutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The fractionation of eleven phenols which may be contaminants in drinking water has been accomplished by using acid-washed graphitised carbon black modified with trimesic acid and PEG 20 M.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 447-451 
    ISSN: 1612-1112
    Keywords: Headspace analysis ; Gas chromatography ; Residual analysis of polyethylene terephthalate ; Acetylene reduction assay ; Ethylene evolution in germinating seed ; Acetaldehyde generation in polyester resin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary New application areas for headspace gas chromatography in agricultural and polymer degradation research are described. Specific examples are drawn from the various forms of headspace analysis with emphasis on the automated static equilibrium method.
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 576-578 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Tortuosity factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The relationship between the obstructive factor γ and velocity was restudied. The dependence of the obstructive factor on velocity was verified. The effects of diffusion coefficient and particle-to-column diameter ratio on the obstructive factor-velocity relationship were investigated. The results are consistent with Hawkes' hypothesis that values of γ at low velocities are averages over tightly packed and loosely packed domains while at high velocities they are weighted in favour of the loosely packed domains where there is more flow.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 648-652 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas-liquid adsorption ; Bulk solution ; Mixed stationary phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary It is shown that the blending of some retention effects can make the resolution of complex mixtures on short classical columns as effective as on capillary columns.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 699-703 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace analysis ; Aromatic hydrocarbons ; Water analyses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The possibilities of using headspace analysis of aromatic hydrocarbon traces in aqueous solutions with changing values of the partition coefficients are discussed. A variant of headspace analysis of the simplest aromatic hydrocarbon in natural and waste water is described. It involves two-step gaseous extraction of a sample in vessels of varying volume before and after the equilibrium phase is replaced with a pure gas (air or nitrogen). This method permits to analyse 5–50 ml water samples with benzene and toluene contents varying from the ppb to the ppm range within an error not exceeding 155. The analysis time is about 1.5 h. The presence of non-volatile organic or mineral substances does not influence the determination. This method is unsuitable to heterogeneous systems (aqueous oil emulsions): before carrying out the analysis for the hydrocarbon content these systems have to be homogenized first.
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Open tubular (capillary) columns ; Glass columns ; Fused-silica columns ; Column testing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Column characteristics affecting the chromatographic behavior of glass and siliceous glass (“fused silica”) capillary columns include the dimensional uniformity of the column, the physical and chemical characteristics of the column wall and the characteristics of the liquid phase. In the case of the coated column the uniformity and thickness of the liquid phase film are the most important criteria affecting column reproducibility. The paper discusses these factors and their influence on column performance.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 203-211 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Quantitative analysis ; Copper oxide converter ; Inorganic gas analysis ; Determination of fluorine and oxygen ; Hydrocarbon analysis ; Wine analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A review of past activities concerning selected industrial analytical problems is given. This includes the following question: preparation of pure gas mixtures to be used for calibration, catalytic conversion of ester and pyridin samples to carbon dioxide and a one-point calibration method using peak heights, both for quantitative analysis, analysis of gas mixtures containing fluorine and inorganic fluorine compounds and the determination of the oxygen and fluorine content of the sample, separation and identification of hydrocarbons in shale oil and petroleum fraction samples, and analysis of wine.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 143-147 
    ISSN: 1612-1112
    Keywords: Capillary columns ; Gas chromatography ; Retention index ; Structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention index of twenty different homologous series of esters have been determined experimentally on polar (Carbowax 1540) and non-polar (squalane) columns. General equations to calculate retention index have been established by statistical methods. The influence of the length and inductive effect of acid and alcohol chains and the relative position of the carboxylic group are discussed.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 285-288 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Porous layer open tubular columns ; Kaolin as support ; Column performance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary PLOT columns have been prepared with kaolin as the liquid phase support. These columns show good efficiency with different stationary phases and good thermal stability with polar phases. The performance of columns is shown by the separation of various mixtures such as fatty acids, phenols and anilines which are of analytical importance.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 39-40 
    ISSN: 1612-1112
    Keywords: Xylidine isomers ; Heteroaromatic liquid phases ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Nicotinic acid and 1H-benzotriazole appreciably resolved all the xylidine (dimethylaniline) isomers, while benzimidazole, nicotinamide and phthalimide can also separate all the isomers except 2,4- and 2,3-xylidines. The analyses were carried out on supports which were not treated with an alkali.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 345-350 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Silica capillaries ; Glass capillaries ; Mixed gum phases ; Polarity and selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Mixed phases of Superox 20M and OV-1 can be coated homogeneously on the untreated wall of fused silica capillary columns. Excellent columns with regard to efficiency, inertness and thermal stability can be obtained. (CE〉95% and MAOT≥250°). The polarity and selectivity were ascertained with Rohrschneider-Reynolds probes and a capillary polarity test mixture. The analysis of an essential oil mixture illustrates the possibilities of mixed phases in practical capillary GC.
    Type of Medium: Electronic Resource
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  • 20
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Capillary columns ; Fused silica ; Contact angle ; Wettability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper describes the systematic characterization of glass and the newly introduced fused silica and quartz capillary columns from surface wettability measurements. Common gas chromatographic stationary phases were used in capillary-rise measurements at temperatures up to 300°C. By construction of Zisman plots and using the Cassie equation, the relative surface concentrations of wettable and non-wettable groups were determined. By application of the Fowkes equation, the dispersion force component of the surface energy was investigated. The influence of various surface treatments such as leaching, silylation, and polymeric film formation are discussed. Wettability measurements were also used to evaluate the thermostability of various treated surfaces and to compare the surface properties of glass, quartz, and fused silica. The wettability of the surfaces with selected stationary phases as a function of temperature is also discussed.
    Type of Medium: Electronic Resource
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  • 21
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Polycyclic aromatic hydrocarbons ; Retention index ; Average molecular polarizabilities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A significant correlation has been found between the retention indices of polycyclic aromatic hydrocarbons on non-polar stationary phases and the average molecular polarizabilities of the molecules separated on these phases. Equations have been derived for the determination of the average molecular polarizabilities, directly from the retention indices.
    Type of Medium: Electronic Resource
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  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 69-72 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Polynuclear aromatic hydrocarbons ; Retention index ; Vapour pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention index of a planar polynuclear aromatic hydrocarbon on the GC phases OV-101, SE-52, and OV-17 is strictly related only to the boiling point, and less closely to the relative molecular mass. The very approximates relation with connectivity index ins only a consequence of the latter. On a nematic lqiuid crystal phase, a variation of activity coefficient, expressed in terms of a shape factor, also influences the retention of PAH.
    Type of Medium: Electronic Resource
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  • 23
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 269-276 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Detector performance ; Trace analysis ; Catalytic conversion ; Multidimensional gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Relationships are derived describing how the detection limit of a chromatographic system depends on the minimum detectable limit of the detector and the chromatographic parameters such as column length, efficiency, carrier gas flow rate and the capacity factor. Performance data of detectors developed in the last 25 years at the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences are given and a few selected application examples are listed. These include trace analysis by preconcentration and by direct analysis and the utilization of multidimensional gas chromatography with two columns, two detectors, a 12-port valve, and a catalytic conversion reactor.
    Type of Medium: Electronic Resource
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  • 24
    ISSN: 1612-1112
    Keywords: Gas chromatography ; C1−C5 Hydrocarbons ; Dimethyl ether
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An analytical GC method was developed which uses a single packed column consisting of three packings in series prepared with the following liquid phases: dimethyl sulfolane, propylene carbonate, and silver nitrate. This system provides satisfactory resolution of mixtures of C1−C5 hydrocarbons and dimethyl ether obtained when converting methanol to gasoline. Due to the high capacity of the column it is possible to inject larger sample amounts permitting trace analysis.
    Type of Medium: Electronic Resource
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  • 25
    ISSN: 1612-1112
    Keywords: Phthalides ; Umbelliferae ; Liquid-solid chromatography ; Gas chromatography ; Ligustilide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A liquid-solid chromatographic pre-fractionation of naturally occurring phthalides has been developed. The LSC was carried out on a column of silica applying a 1–50% gradient elution of diethyl ether (containing 2% methanol) in pentane. The enrichment in the fractions led to better possibilities for a gas chromatographic separation and isolation allowing further studies by spectroscopic methods. Ligustilide may easily isomerize during GC as a result of ageing of the column.
    Type of Medium: Electronic Resource
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  • 26
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 601-602 
    ISSN: 1612-1112
    Keywords: Ethanolamines ; Ethylene glycols ; Direct separation ; Gas chromatography ; Short glass capillaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An effective and rapid GC separation of ethanolamines, even in the presence of ethylene glycols, using short glass capillary columns is developed. No preliminary derivatisation of the sample is necessary. The separation is completed in 6 minutes.
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  • 27
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 507-509 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace ; Phenol ; Urine ; Enzymatic hydrolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method has been developed for the determination of phenol in urine in which the phenol conjugates are hydrolysed enzymatically and the liberated phenol is analysed by headspace chromatography. The results compare favourably with those obtained by the method of van Haaften and Sie in which acid hydrolysis is carried out in a heated GC precolumn. The enzymatic hydrolysis headspace technique appears to be very reliable and does not suffer from the disadvantages of precolumn acid hydrolysis.
    Type of Medium: Electronic Resource
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  • 28
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 14 (1981), S. 421-424 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid sulfur ; McReynolds' constants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The McReynolds' constants for liquid sulfur as a stationary phase in gas-liquid chromatography (GLC) are presented. A simple graphical method of pattern analysis is used to indicate the uniqueness of the sulfur column as compared with other stationary liquid phases characterized by McReynolds. The limitations of using a single factor (as polarity) for the basis for the selection of GLC columns is discussed.
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  • 29
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Kováts retention indices ; Propellants ; Solvents ; Aerosol packs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A gas chromatographic method is described by which a nearly complete separation of all commonly used propellants and solvents and their identification and determination can be achieved in one step. The separation is by simple adsorption chromatography on columns packed with Porapak-T with a temperature program 100–180°C at 10°C/min. Kováts' retention indices have been calculated for isothermal conditions at 150°C respectively 100°C for the propellants, at 180°C for the solvents. An exact identification of the propellants and solvents by means of the Kováts' indices is practicable even in complex mixtures.
    Notes: Zusammenfassung Es wird eine gas-chromatographische Methode angegeben, welche eine fast vollständige Auftrennung aller handelsüblichen Aerosol-Treibgase und Lösungsmittel und ihre Identifizierung und Bestimmung in einem Schritt gestatet. Die Trennung erfolgt durch reine Adsorptions-Chromatographie and Porapak T-Säulen bei 100–180°C mit einer Temperaturate von 10°C/min. Zur Bestimmung der Retentionsindices nach Kovats wurden die Treibgase isotherm bei 150°C bzw. 100°C, die Lösungsmittel bei 180°C aufgetrennt. Anhand der Kovats-Indices ist eine eindeutige Identifizierung der Treibgase und Lösungsmittel selbst in vielfältigen Gemischen möglich.
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  • 30
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 243-243 
    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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  • 31
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 267-275 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Candida Krusei has a optimum growth temperature of 37°C on SASOL ethanol-isopropanol mixture. The organism was unable to grow on isopropanol, but oxidized it partially to acetone in the presence and absence of ethanol. Growth at 40°C in the alcohol mixture was slightly faster than at 30°C over an ethanol concentration range of 0.43 to 3.6% (v/v), although at both temperatures the growth rate declined continuously with increasing concentration. At an ethanol concentration greater than 3.6% (v/v), the mixture was much more inhibitory to growth at 40 and 30°C. The inhibitory effect was due to the ethanol rather than the isopropanol. Metabolites such as acetate, acetaldehyde, and ethyl acetate accumulated in the medium, but the degree of accumulation depended upon the temperature and alcohol mixture concentration. At 40°C, acetaldehyde and acetate accumulated to a greater extent than 30°C on a 4.0% (v/v) synthetic alcohol mixture and this may also cause the greater inhibition at this temperature. The alcohol mixture is unsuitable for single cell protein (SCP) production in batch culture because of the low cell densities observed at all alcohol concentrations.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 32
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 301-319 
    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 both theoretically and experimentally that interphase nitrogen transport may have a significant influence on the rate of interphase oxygen transport, and thereby also on the value of the volumetric mass transfer coefficient of oxygen, kla, determined in mechanically agitated bubble fermentors using the variants of dynamic method presented in the literature. The experiments were carried out in 1M KCI solution at five stirrer frequencies and two gas inlet levels. The gas interchanges were performed either without interrupting the aeration and agitation of the charge (A) or with the aeration and agitation of the charge turned on at the same time (B). The applied variants of the interchange were N2→ O2→, O2→ N2, N2→ air, air→ N2, O→ O2, and O→ air. In the two last variants the oxygen dissolved in the charge was removed by reacting with sulfite ions. The kla values calculated by allowing for the nitrogen transport for procedure A were approximately equal to the values obtained by disregarding the nitrogen transport, whereas those for procedure B were higher (up to 40%), than the values obtained disregarding the nitrogen transport.
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  • 33
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981) 
    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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  • 34
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    Biotechnology and Bioengineering 23 (1981), S. 291-299 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Raw cassava root starch was transformed into ethanol in a one-step process of fermentation, in which are combined the conventional processes of liquefaction, saccharification, and fermentation to alcohol. Aspergillus awamori NRRL 3112 and Aspergillus niger were cultivated on wheat bran and used as Koji enzymes. Commercial A. niger amyloglucosidase was also used in this experiment. A raw cassava root homogenate-enzymes-yeast mixture fermented optimally at pH 3.5 and 30°C, for five days and produced ethanol. Alcohol yields from raw cassava roots were between 82.3 and 99.6%. Fungal Koji enzymes effectively decreased the viscosity of cassava root fermentation mashes during incubation. Commercial A. niger amyloglucosidase decreased the viscosity slightly. Reduction of viscosity of fermentation mashes was 40, 84, and 93% by commercial amyloglucosidase, A. awamori, and A. niger enzymes, respectively. The reduction of viscosity of fermentation mashes is probably due to the hydrolysis of pentosans by Koji enzymes.
    Additional Material: 3 Ill.
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  • 35
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    Biotechnology and Bioengineering 23 (1981), S. 345-354 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The filamentous fungus, Rhizopus nigricans, was immobilized in polyacrylamide, alginate, and agar gels and its ability to 11α-hydroxylate progesterone was examined. No activity was detected using polyacrylamide gel but both agar and alginate gels have proved capable of hydroxylation. Agar gels displayed faster rates and higher yields. It was possible to induce hydroxylase synthesis within agar and alginate gels, and microscopical examination provided evidence for hyphal growth within these gels. The concept of increased biomass was used to explain the observed increase in the rates of hydroxylase activity of the immobilized cells. Conversely, hyphal overcrowding was postulated for the rapid inactivation observed under some operating conditions.
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  • 36
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    Biotechnology and Bioengineering 23 (1981), S. 391-404 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A fermentation system with a plug scheme unit has been developed, offering a variety of solutions to measurement, control, and operational problems. By means of the program unit, e.g., automatic pH control assigned to the dynamic of batch cultures and the feed of different ingredients controlled by a time program or a given variable have been solved. The continuous culture volume was controlled by a level controlled by a level controller equipped with a photosensor. A method was developed for variable control that provide information on the activity of the culture, and allows direct measurement of the different rate values, e.g., generation time or specific product formation rate. Applicability of the direct measurement of generation time is presented in the qualification of molasses and in a static off-line optimization process.
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  • 37
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    Biotechnology and Bioengineering 23 (1981), S. 833-841 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of immobilization with various glass-forming monomers on the stability of PS II activity of spinach chloroplast was investigated. PS II activity (O2 evolution due to the Hill reaction) was reduced very slightly by the addition of monomers including polyethyleneglycol (PEG). Immobilization of chloroplast was done with hydrophobic monomer as well as hydrophilic monomer and activity of immobilized chloroplast increased with decreasing monomer concentration as far as the polymerization was possible. The activity of immobilized chloroplast was very high and it decayed far more gradually with the storage time in comparison with the decay of unimmobilized chloroplast and was retained more than 30 days. The optimum monomer concentration for immobilization was about 10%. Thermostability of chloroplast also increased greatly by immobilization with these monomers, especially hydrophilic monomers.
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  • 38
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A range of cellulosic raw materials in the form of agricultural crop residue was analyzed for chemical composition and assessed for potential yields of sugars through chemical pretreatment and enzymatic hydrolysis of these materials. Corn stover was used as a representative raw material for a preliminary process design and economic assessment of the production of sugars and ethanol. With the process as presently developed, 24 gal ethanol can be obtained per ton of corn stover at a processing cost of about $1.80/gal exclusive of by-product credits. The analysis shows the cost of ethanol to be highly dependent upon: (1) the cost of the biomass, (2) the extent of conversion to glucose, (3) enzyme recovery and production cost, and (4) potential utilization of xylose. Significant cost reduction appears possible through further research in these directions.
    Additional Material: 6 Ill.
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  • 39
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    Biotechnology and Bioengineering 23 (1981), S. 213-220 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The cyanobacterium Anabaena cylindrica B629 was suspended in small glass beds and incubated in a gas-tight glass vessel outdoors under a gas atmosphere comprising carbon monoxide (0.2%), acetylene (5%), oxygen (6.5%), and nitrogen. The solution phase initially contained sodium bicarbonate (10mM) at pH 7. Under these conditions the organism continuously produced hydrogen gas for over three weeks. The temperature of the culture was maintained below 30°C and minimum night temperatures were recorded. The vessel was covered by a shadecloth, which reduced the natural illumination by approximately 70%. The system is an alternative to those requiring the strict absence of oxygen and little nitrogen, and requires virtually no attention during the incubation period.
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  • 40
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    Biotechnology and Bioengineering 23 (1981), S. 235-242 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 41
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    Biotechnology and Bioengineering 23 (1981), S. 361-371 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An enzyme which catalyzes the synthesis of cephalexin fromD-α phenylglycinemethylester (PGM) and 7-amino-3-desacetoxy-cephalosporanic acid (7-ADCA) was prepared from Xanthomonas citri (IFO 3835) and partially purified 30-fold by ammonium sulfate fractionation, DEAE-cellulose, and Sepharose-4B column chromatography. The Km values for 7-ADCA, PGM, and cephalexin were determined as 11.1, 2.1, and 1.61 mM, respectively. The enzymatic cephalexin synthesis follows the reversible bi-uni reaction kinetics. The equilibrium constant is influenced by the initial mole ratios of 7-ADCA and PGM. The cephalexin hydrolysis is catalyzed by the same cephalexin synthesizing enzyme, but methanol does not participate in the hydrolytic reaction. The amount of enzyme in the reaction mixture affects the initial rate but does not influence the equilibrium product concentration. This cephalexin-synthesizing enzyme was immobilized onto several adsorbents. Among these, Kaolin and bentonite showed a higher retention of enzyme activity and stability for reuse. The immobilized-enzyme reaction kinetics were investigated and compared with those of the soluble enzyme. A rate expression for the enzymatic synthesis of cephalexin was derived. The results of computer simulation showed good agreement with the experimental results.
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  • 42
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    Biotechnology and Bioengineering 23 (1981), S. 431-436 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
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  • 43
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    Biotechnology and Bioengineering 23 (1981), S. 425-429 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 44
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    Biotechnology and Bioengineering 23 (1981), S. 451-454 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 45
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    Biotechnology and Bioengineering 23 (1981), S. 487-497 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A simple method is presented that establishes intrinsic rate parameters when slow pore diffusion of substrate limits immobilized enzyme reactions that obey Michaelis-Menten kinetics. The Aris-Bischoff modulus is employed. Data at high substrate concentrations, where the enzyme would be saturated in the absence of diffusion limitation, and at low substrate concentrations, where effectiveness factors are inversely proportional to reaction modulus, are used to determine maximum rate and Michaelis constant, respectively. Because Michaelis-Menten and Langmuir-Hinshelwood kinetics are formally identical, this method may be used to estimate intrinsic rate parameters of many heterogeneous catalysts. The technique is demonstrated using experimental data from the hydrolysis of maize dextrin with diffusion-limited immobilized glucoamylase. This system yields a Michaelis constant of 0.14%, compared to 0.11% for soluble glucoamylase and 0.24% for immobilized glucoamylase free of diffusional effects.
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  • 46
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    Biotechnology and Bioengineering 23 (1981), S. 551-565 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper describes the scale-up from 0.1 to 100 liter of the unit process based on 3-mm-diameter glass spheres for the growth of BHK monolayer cells. The production of four strains of FMD virus at the 0.1-, 10-, and 100-liter scales was examined. Cell growth was estimated from measurements of the concentration of glucose in the growth medium, while the release of virus was inferred from measuring the concentration of LDH in the culture supernatant fluid. The yields of virus at 0.1-, 1-, and 10-liter scales were similar but that from the 100-liter version was somewhat lower. The reason for this lower yield and the method used to overcome it over outlined.
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  • 47
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A culture of R. rubrum cells apparently contaminated with K. pneumoniae were immobilized by entrapment in agar. This system was used as model for hydrogen production by photometabolic means. Observed results indicated that the contaminant exerted a major influence on the observed results. This preparation, when immobilized and used in a specifically designed reactor with glucose substrate, showed operational half-lives of approximately 1000 hr. The feasibility of using this “mixed” culture for producing hydrogen from acid hydrolyzed cellulose and wood sawdust was also examined.
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  • 48
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    Biotechnology and Bioengineering 23 (1981), S. 663-668 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: No abstract.
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  • 49
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    Biotechnology and Bioengineering 23 (1981), S. 677-689 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nickel-NiO-BSA-chymotrypsin has been used to hydrolyze casein in both batch and continuous stirred tank reactors. The kinetics of hydrolysis in both types of reactor were considered. Some operational problems encountered using fine powder catalysts in batch stirred tank reactors are discussed. High gradient magnetic separation was found to be a powerful catalysts retention method for magnetic support particles, particularly when using a ferromagnetic collection matrix. Nickel particles of diameter 3-7 μm were easily separated from water at a processing velocity of 39 mm/sec. Nickel powder and precipitated Fe3O4 were also separated satisfactorily using a rotating drum magnetic separator.
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  • 50
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    Biotechnology and Bioengineering 23 (1981), S. 717-738 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: There is now growing evidence that the production of many secondary metabolic by microorganisms is subjected to carbon-catabolite regulation. Even though the exact mode of this regulation is not yet clear, an engineering analysis of the production process is still possible based upon a suitable hypothesis. By way of simulation of penicillin fermentation data obtained from the literature, a mechanistic model involving a substrate inhibition kinetics of product formation has been verified in this paper. Such a model has been found successful not only in predicting simple sugar-feeding strategy, but also a complicated computer guided strategy based upon controlling biomass growth rates in the tropo and idiophases. Using this model, for strategies for sugar feeding into penicillin fermentation have been investigated. These results show that similar penicillin productivities can be obtained using any of these strategies provided fermentations are carried out under optimal conditions corresponding to the strategy chosen. Effect of maximum oxygen transfer capacity of the fermentor under the conditions of fungal growth has been incorporated using an upper limit of biomass concentration on achievement of which the fermentations must be stopped due to serious oxygen limitations. Results of model simulations with such limits throw light upon the way in which different fermentors may behave with respect to product formation.
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  • 51
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    Biotechnology and Bioengineering 23 (1981), S. 793-803 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Energetic yields associated with microbial growth on hydrocarbons are investigated and compared with values for other organic substrates. Both cell growth and extracellular product formation are investigated. Both carbon and energy limitations are considered in estimating theoretical yields. Carbon, available electron, and ATP balances are used in the theoretical analysis. The results indicate that the availability of carbon may limit growth and product formation.
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  • 52
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    Biotechnology and Bioengineering 23 (1981), S. 843-854 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to reduce the severe flux losses encountered during ultrafiltration of protein solutions, proteases were immobilized on Ultrafiltration membranes to hydrolyze the deposited solute molecules. Over a standard 22 hr run 25 to 78% improvement in cumulative permeate yield was obtained when processing 0.5% albumin or hemoglobin. It was also demonstrated that the flux enhancements were due to the biochemical action of the absorbed protease and not to its physical effect as a prefilter coat. with the aid of a model retardation of gel formation mechanism was demonstrated. Economics of the system were shown to be favorable, improving the rate of return on capital investment up to 50% by reduction of the total membrane area of the plant.
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  • 53
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    Biotechnology and Bioengineering 23 (1981), S. 887-898 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper describes the implementation of multilevel techniques using a microprocessor to control multistage continuous culture systems. A system which produces gramicidin S is taken as an example. The single level technique using the conjugate gradient method is applied to solve the two-stage and the three-stage continuous culture and is compared with the multilevel one. The results show that the application of multilevel techniques is more advantageous and suitable for this system than any other method which has been utilized so far. The advantages of using a microprocessor will be stated.
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  • 54
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    Biotechnology and Bioengineering 23 (1981), S. 917-917 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: No abstract.
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  • 55
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    Biotechnology and Bioengineering 23 (1981), S. 1015-1021 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The growth of E. coli W in a bench scale fermentor to high cell concentration is described. The method involves growth-linked introduction of ammonia to the culture, sparging the culture with oxygen, and maintenance of aerobic conditions during the final growth phase by gradually and automatically decreasing the concentration of the carbon source, sucrose, in the culture. Thus, the oxygen demand is kept within the limits of the supply capacity, and a linear growth rate during the final phase of growth is obtained. A concentration of 42 g dry cell per liter was obtained. The yield constants for nitrogen and phosphorous were determined and were compared with those obtained using the temperature variation method.
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  • 56
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    Biotechnology and Bioengineering 23 (1981), S. 1037-1044 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Rates of oxygen absorption into glucose solutions were measured using an immobilized-enzyme reactor, in which magnetite-containing beads of immobilized glucose oxidase were moved by a revolving magnetic field to reduce the mass transfer resistances at the gas-liquid interface and around the bead. Data were also obtained for oxygen absorption into glucose solutions containing soluble or immobilized glucose oxidase (without magnetite), as well as for physical absorption of oxygen. The rates of physical absorption for the runs with the magnetite-containing beads increased because of mechanical stirring caused by spinning of the beads at the gas-liquid interface. In this case the experimental enhancement factors were found to be larger than those predicted on the basis of the film theory for gas absorption with a pseudo-first order reaction.
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  • 57
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The relation between the intrinsic rate of the glucose-fructose isomerization catalyzed by whole-cell immobilized glucose isomerase and the substrate concentration can be described with the kinetic model The numerical values of k1, k-1, k2, and k-2 have been determined from low-conversion experiments starting from pure glucose or fructose solutions, and are presented as a function of pH and temperature. The difference between the overall chemical reaction rate determined in high-conversion experiments and that calculated from the individual k1, k-1, k2, and k-2 values is less than 10%.
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  • 58
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    Biotechnology and Bioengineering 23 (1981), S. 1-18 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A continuous-flow, high throughput, turbine-driven zonal centrifuge has been contained for use with biologically hazardous materials. The centrifuge and all ancillary equipment are enclosed in three sealed cabinets that are maintained at negative pressure, decontaminated with ethylene oxide, and provide cooling for the process fluids. Sample handling is semiautomated and remotely controlled for ease of operation and includes an automated decontamination system. The centrifuge subsystems can be decontaminated prior to an engineer servicing the machine, and apparatus is provided for absolute filtration of the centrifuge turbine exhaust.
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  • 59
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    Biotechnology and Bioengineering 23 (1981), S. 61-77 
    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 fermented by anaerobic acidogenic bacteria to produce volatile (C2-C6) organic acids. Mild pretreatment with dilute alkali solutions produced a two-fold increase in fermentability. A mixture of lime and sodium carbonate was found to be a better pretreatment agent than sodium hydroxide. Methane generation was inhibited by low temperature (≤ 25°C) and high solids [≥ 2.5% (w/v)] fermentation. Volatile acid yields of 0.5-0.55 g acetic acid equiv/g dry ash-free (DAF) stover could be obtained in batch fermentations. Several extractants and extraction solvents for organic acids were found to be nontoxic to acidogenic fermentation. The data show that acidogenic fermentation can produce useful volatile fatty acids in high yields from a complex lignocellulosic feedstock. These fermentations are nonsterile, need no stirring, and are easy to run. Moreover, cellulose, pentosans, and other carbohydrates are directly utilized by acidogenic bacteria. Hence, acidogenic fermentation could be useful in converting biomass to chemical feedstocks and fuel.
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  • 60
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    Biotechnology and Bioengineering 23 (1981), S. 111-148 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A modal has been described for the influence of growth rate and shear stresses in the fermentor upon the morphology of filamentous molds. The main concept of this model is the dynamic equilibrium between growth and breakup of the hyphae. The latter has been approached according to well-known engineering theories for dispersion of physical systems. Experiments to verify the model with a strain of Penicillium chrysogenum in batch and continuous culture revealed that the length of the mycelial particles increased with increasing growth rate and decreased with increasing power input her unit mass in the fermentor. Although this was qualitatively in agreement with the presented model, quantitatively the model had to be rejected. Variation of the tensile strength of the hyphae with age and culturing conditions could have been one of the causes of disagreement. Oxygen tension, varied independently from stirrer speed, in the range of 12-300 mm Hg was shown to have no influence upon the morphology. With respect to the question of possibly using high-energy inputs in industrial mold fermentation in order to decrease hyphal length and suspension viscosity, it was concluded that this is of little practical value. A substantial decrease in hyphal length requires an enormous increase in energy input.
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  • 61
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    Biotechnology and Bioengineering 23 (1981), S. 231-233 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 62
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    Biotechnology and Bioengineering 23 (1981), S. 249-266 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Optimal operation of repeatedly fed-batch was determined by the continuous maximum principle for the constant yield case. The objective of maximum cell productivity for a fixed cell concentration was achieved by finding the substrate feeding policy that minimized the processing time. Analytical criteria for the optimal filling policy show that an exponential policy is optimum when the specific growth rate has a maximum, and also that operation in the simple repeated batch mode is optimum when the specific growth rate is monotonic increasing. Comparisons between optimal repeated fed-batch culture and other modes of operation were made for the case of substrate-inhibited growth. Cell productivity by repeated fed-batch exceeds both batch and continuous operation for the case of low residual substrate concentration.
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  • 63
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 335-343 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The viscosity, density, and sedimentation characteristics of suspensions of whole and mechanically disrupted yeast cells were measured. Mechanical disruption increases the suspension viscosity and its non-Newtonian behavior. Experiments showed a good correlation between laboratory- and industrial-scale centrifugation results.
    Additional Material: 7 Ill.
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  • 64
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    Biotechnology and Bioengineering 23 (1981), S. 355-360 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Synthesis of a peptide bond is suggested to be enzymatically catalysed in a biphasic system “water-water-immiscible organic solvent”. The pH dependence of the apparent equilibrium constant is studied for synthesis of N-acetyl-L-tryptophanyl-L-leucine amide from N-Acet-Trp andL-Leu-NH2. The reaction was performed in the biphasic system ethyl acetate plus water [from 2 to 2% (v/v)] in the presence of α-chymotrypsin. The suggested approach is preparative value: with the stoichiometric ratio of the reagents, [N-Acet-L-Trp] = [L-Leu-NH2] = 2 × 10-3M, the yield is practically 100% (in water, with other conditions being the same, the yield is not over 01.%).
    Additional Material: 1 Ill.
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  • 65
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    Biotechnology and Bioengineering 23 (1981), S. 405-417 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An expensive computer-operated system suitable for data collection and steady-state optimum control of fermentation processes is presented. With this system, minimum generation time has been determined as a function of temperature and pH in the turbidostat cultivation of a yeast strain. The applicability of the computer-fermentor system is also presented by the determination of the dynamic KLa value.
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  • 66
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    Biotechnology and Bioengineering 23 (1981), S. 437-440 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 67
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    Biotechnology and Bioengineering 23 (1981), S. 455-460 
    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 Ill.
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  • 68
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    Biotechnology and Bioengineering 23 (1981), S. 473-485 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The production of sugars by enzymatic hydrolysis of cellulose is a multistep process which includes conversion of the intermediate cellobiose to glucose by β-glucosidase. Aside from its role as an intermediate, cellobiose inhibits the endoglucanase components of typical cellulase enzyme systems. Because these enzyme systems often contain insufficient concentrations of β-glucosidase to prevent accumulation of inhibitory cellobiose, this research investigated the use of supplemental immobilized β-glucosidase to increase yield of glucose. Immobilized β-glucosidase from Aspergillus phoenicis was produced by sorption at controlled-pore alumina with about 90% activity retention. The product lost only about 10% of the original activity during an on-stream reaction period of 500 hr with cellobiose as substrate; maximum activity occurred near pH 3.5 and the apparent activation energy was about 11 kcal/mol. The immobilized β-glucosidase was used together with Trichoderma reesei cellulase to hydrolyze cellulosic materials, such as Solka Floc, corn stove and exploded wood. Increased yields of glucose and greater conversions of cellobiose of glucose were observed when the reaction systems contained supplemental immobilized β-glucosidase.
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  • 69
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    Biotechnology and Bioengineering 23 (1981), S. 535-549 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A generalized mathematical model, previously developed and experimentally validated, was modified and used to computer-simulate two dialysate-feed systems for operating a dialysis continuous process for the ammonium lactate fermentation. The simulations predicted that the feeding of substrate into the dialysate circuit and thence into the fermentor circuit via dialysis should greatly improve the production of cell mass and metabolite product. Experiments were conducted to test the system in which the fermentor is operated without an effluent, thus immobilizing the cells. Dried cheese whey ultrafiltrate was rehydrated to contain a normal concentration of lactose (62 mg/ml), supplemented with yeast with an adapted culture of Lactobacillus bulgaricus. The system was operated without interruption for 26 days. Results during steady-state conditions showed that the system is a new and useful way to immobilize living cells for the purpose of producing a metabolite at a high rate for a prolonged time. The substrate consumed by the cells is converted to product via maintenance metabolism only and is sterilized by dialysis.
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  • 70
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    Biotechnology and Bioengineering 23 (1981), S. 615-626 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A description is presented of the design and performance of a model sewage treatment system consisting of one aerobic reactor and clarifier plus one anaerobic reactor, with an aerobic-mixed-liquor-volume/anaerobic-mixed-liquor-volume ratio of 1:4. Effluent values of ammonia, nitrite, and nitrate nitrogen were found to be 0, 0, and about 5 ppm, respectively. Effluent organic nitrogen was not determined, having been assumed to be negligible. Approximately 90% of the total influent nitrogen was removed by nitrification plus denitrification. Sludge production was found to be minimal, and it was never necessary to waste sludge from the system.
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  • 71
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    Biotechnology and Bioengineering 23 (1981), S. 657-661 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: No abstract.
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  • 72
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    Biotechnology and Bioengineering 23 (1981), S. 691-705 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Rate expression for enzyme poisoning which are consistent with a Michaelis-Menten main reaction are used to analyze the performance of a fixed bed reactor containing immobilized enzyme. When enzyme deactivation results from the irreversible bonding of a product molecule to an existing substrate-enzyme complex, it is shown that minimum enzyme activity can occur in the interior of the bed, well away from the ends. This suggests that bed sectioning techniques may enable direct evaluation of fundamental poisoning mechanisms.
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  • 73
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    Biotechnology and Bioengineering 23 (1981), S. 781-792 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Slime-covered rocks and samples of process waters from two trickling filters for treatment of municipal wastes were brought to the laboratory for probing with microelectrodes to determine dissolved oxygen (DO). Slime thickness was 0.4-1.5 mm. Flow rate of medium over the slime had a minor effect on slime respiration, but pH 5 or below was strongly inhibitory. Increasing temperature showed lower oxygen concentration throughout a slime, although 27°C had results little different from those at 22°C. Medium concentration had a profound effect on oxygen concentration profiles, and either oxygen-limited or substrate limited respiration could be demonstrated. Illumination of slimes from the top of the trickling filter developed oxygen supersaturation because oxygen from photosynthesis could not diffuse away rapidly.
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  • 74
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    Biotechnology and Bioengineering 23 (1981), S. 739-763 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The present paper presents a generalized treatment of the principles of elemental and enthalpy balances which are applied to aerobic fermentation processes. It is shown that strict relations do exist between the various yield factors of biomass or product on substrate, oxygen, carbon dioxide, and between the various maintenance coefficients. These relations are confirmed from the existing body of literature data on yield and maintenance coefficients. Another consequences of the application of elemental balances is the existence of limits for the maximum biomass yield on substrate and oxygen, which depend on the degree of reduction of the substrates with different degree of reduction. It appears from this model that substrates with a high degree of reduction are C limited and substrates with a low degree of reduction are energy limited. Finally the effects of temperature on yield and maintenance coefficients are analyzed from the existing body of literature data. It can be concluded that the maintenance coefficients follow an Arrhenius type of relationship and that yield is temperature independent. The literature data seem to indicate that a degree of reduction of about 4 is optimal for the carbon and energy needs for biomass formation.
    Additional Material: 7 Ill.
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  • 75
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    Biotechnology and Bioengineering 23 (1981), S. 823-831 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Wheat straw was pretreated with sodium hydroxide, ozone, and sulfur dioxide, and subsequently treated with four sources of cellulase, T. reesei, T. reesei, T. viride, A. niger, and Oxyporus sp. The effect of the combined chemical + enzyme treatments on the extent of saccharification and on the digestion rate by rumen microorganisms was studied. Cellulases were applied at an equal but low concentration (0.5 FPU/ml) on the pretreated straw. The combined treatments, SO2 + T. reesei cellulase nd SO2 + T. viride cellulase, produced the highest and significant levels of reducing sugars (RS), 577 and 597 mg RS/g straw organic matter. The highest enzyme efficiency, 44.7 mg RS/mg enzyme, was found with T. reesei cellulase when applied on SO2 pretreated straw. The in vitro organic matter digestibility was affected significantly only by the chemical pretreatments, whereas the effect of the cellulases was expressed mainly in increasing the fermentability of the hydrolyzed straw. The in vitro digestion pattern of the saccharified straw was found to be typical of a highly fermentable feed and comparable to a starchy mixture such as used in concentrate ruminant diets.
    Additional Material: 4 Ill.
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  • 76
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    Biotechnology and Bioengineering 23 (1981), S. 879-886 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Factors affecting acid hydrolysis of sweet potato powder (SSP) to fermentable sugars were examined. These include HCl concentration, temperature, time, and levels of SPP. Maximum reducing sugar, reported as dextrose equivalent (DE), was detected after 24 min hydrolysis (1% SPP) in 0.034N HCl heated at 154°C. These samples also had 3.43% droxymethylfurfural (HMF) based on dry weight. A high level of HMF (9.2%) was detected in 1% SPP heated at 154° in 0.10N HCl for 18 min. The lowest concentration of HMF formed (1.8%), at maximal DE of 61%, was established in samples containing 5% SPP and heated at 154° in 0.034N HCl for 48 min. Aqueous extracts of uncured SPP, examined by HPLC, contained glucose, fructose and sucrose, but degraded SPP had only glucose and fructose. Products of degraded SPP, under appropriate conditions, could be used for alcohol fermentation.
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  • 77
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    Biotechnology and Bioengineering 23 (1981), S. 899-916 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this study, live cells of Brevibacterium flavum were immobilized for the production of glutamic acid. The reason for such a choice was that glutamic acid fermentation is an extensively studied fermentation and one which requires the viability of entire cellular faculties for the acid production. Brevibacterium flavum was chosen because it is an industrially used bacterium, and is very potent via a vis glutamic acid production. Studies were performed to find aeration and agitation conditions for optimal growth and glutamic acid productivity. Experiments were also done to find the optimum harvesting time. The cell activity peaks during the run of fermentation, and the time at which the peak occurs, was found. Conventional methods for immobilizing the cells on collagen were found to be lacking. The pH and drying were the two main reasons for loss of viability of the cells; the latter being more important. A modified immobilization procedure has been devised, which can immobilize live cells at any given pH and ionic strength, in contrast to the conventional method which requires the pH to be above 11 or below 3. This new method involves dialysis of collagen in suitable dialysis bags against water at pH7 (or buffer at any desired pH). The dialysed collagen blended at 20,000 rpm, resulted in a very smooth dispersion, unnoticeably different from collagen dispersion prepared at pH 11. The dispersed collagen was then cast and dried at an elevated temperature, and high air flow rate over the cast membrane, decreasing the time of drying from 6-8 hr ( in the conventional method) to 1.5-2 hr. The membrane has been tested for glutamic acid producing capabilities in a column reactor with the membrane spirally wound. The reactor has been operated under continuous conditions for 5-10 days with stable activities.
    Additional Material: 6 Ill.
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  • 78
    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 was carried out to define how the overall rate of reaction would be influenced by different degrees of diffusional resistance to cofactor transport within an oxidoreductase membrane matrix. To accomplish this, 0.7-6.6μM yeast alcohol dehydrogenase was immobilized in an albumin matrix crosslinked with 2.5 or 5.0% glutaraldehyde to give 102-1685 μM thick membranes. The enzyme half-life was at least doubled at pH 7.5 or 8.8 on immobilization. Values of the kinetic constants for the soluble and immobilized enzyme were determined at 25°C and pH 8.8 over the range of 0.01-1.0M bulk solution concentration of ethanol as substrate and 140-1000μM bulk solution concentration of nicotinamide adenine dinucleotide (NAD+) as cofactor, to give essentially single substrate kinetics in NAD+. Equilibrium partitioning of ethanol and NAD+ between the solution and membrane was measured and used in the data analysis. The four kinetic constants for the soluble enzyme agreed with literature values; and all increased with immobilization of the enzyme. The Michaelis constants for NAD+ and for ethanol were greater for the immobilized enzyme. The diffusional resistance to NAD+ transport, presented in terms of the Thiele modulus, showed that the overall rate of reaction was decreased by about 50% even at values of the modulus as low as 2.0.
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  • 79
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    Biotechnology and Bioengineering 23 (1981), S. 1023-1035 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Saccharomyces cerevisiae CBS 426 was grown aerobically and anaerobically in a glucose-limited chemostat. The flows of biomass, glucose, ethanol, carbon dioxide, oxygen, glycerol, and the elemental composition of the biomass were measured. Models for anaerobic and aerobic growth are constructed. Values for YATP and P/O are obtained from continuous culture data for aerobic growth; this YATP value is compared with that obtained from the anaerobic growth results. The ratio between the heat produced and the oxygen consumed increases if more glucose in fermented to ethanol and carbon dioxide. An equation for φH/φO as a function of the respiratory quotient is given.
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  • 80
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    Biotechnology and Bioengineering 23 (1981), S. 1067-1078 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The conversion of the enzymatic hydrolysate of shellfish chitin waste to single-cell protein was investigated as part of a comprehensive waste treatment program. Forty-two yeasts were screened for ability to assimilate the monomer of chitin, N-acetylglucosamine, which has been shown to be the sole product of enzymatic hydrolysis of chitin. The Yeast Pichia Kudriavzevii was selected for study, based on ability to grow at high temperature (37°C and above), low pH (4.0 ± 0.5), and in a nutritionally simple medium. Growth rates of P. kudriavzevii were similar on N-acetylglucosamine and on the chitin hydrolysate. Dependencies of specific growth rate on temperature, pH, medium composition, and oxygen tension were studied. The variations of yield, protein content, and total nucleic acid content with the specific growth rate were evaluated. The amino acid distribution of the protein of P. kudriavzevii was obtained.
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  • 81
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    Biotechnology and Bioengineering 23 (1981), S. 1115-1120 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The study concerned the pH profile of the apparent equilibrium constant for synthesis of N-benzoyl-L-phenylalanine ethyl ester from the respective acid and ethanol in the biphasic system chloroform + 5% (v/v) water. The substitution of water (as a reaction medium) for the biphasic aqueous-organic system shifted the pH profile toward neutral pH values. As a result the pH range thermodynamically conducive to synthesis of the final product in the biphasic system coincided with the pH optimum of the catalytic activity of the enzyme used (α-chymotrypsin). This approach should, in principle, be considered as general: first, per se it is independent of a catalyst (enzyme) nature; second, the biphasic method helps the shift ionic equilibria involving not only organic acids, but also bases. A physical mechanism of the ionic equilibrium shift is the same is both cases, namely, a preferable extraction from water into an organic phase of one generally nonionic (more hydrophobic) form of the reagent.
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  • 82
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    Biotechnology and Bioengineering 23 (1981), S. 1103-1114 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A possible use of phosphorylating mitochondrial electron transport particles (ETPH) has been investigated for ATP regeneration. The oxidative phosphorylation of ETPH was considerably inhibited by the hydrolytic activity of ATPase and adenylate kinase. The hydrolytic activity of ATPase and adenylate kinase were found to be intensively retarded in the presence of Mg2+. ETPH continuously regenerated ATP from ADP over 4 hr when suspended in an isotonic buffer containing ADP, succinate, and 100 mM MgSO4. Furthermore, repeated use of ETPH was possible for ATP regeneration primarily due to considerable stabilization of the electron transport system.
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  • 83
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    Biotechnology and Bioengineering 23 (1981), S. 1145-1154 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The thermodynamics of the various anaerobic digestion patterns of hexose to methane are compared. It appears that by directing the hexose-hydrolysis phase towards ethanol and lactic acid production, methanogenesis can be enhanced because the syntrophic bacteria are allocated more potentially available energy. This hypothesis was confirmed in a series of laboratory test runs. They revealed that lactic acid and ethanol as intermediates, in comparison to lower volatile fatty acids, give rise to a considerably higher effluent quality and a slightly larger biogas production.
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  • 84
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    Biotechnology and Bioengineering 23 (1981), S. 1121-1132 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The specific growth rate of Chlorella vulgaris in the presence of glucose (mixotroph) was always larger than that in autotroph when the light intensity was less than 10 klux. However, Scenedesmus acutus behaved differently, i.e., when the light intensity was more than 6 klux, the specific growth rate in mixotroph became smaller than that in autotroph. Cellular contents of chlorophyll a and b in Scenedesmus acutus that deteriorated more markedly in mixotroph than those of Chlorella vulgaris could account for these different growth behaviors. In other words, mechanisms relevant to the photosynthesis and the oxidative phosphorylation of glucose seem to function independently with respect to Chlorella Vulugaris.
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  • 85
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    Biotechnology and Bioengineering 23 (1981), S. 1133-1144 
    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 treats the application of the macroscopic electric charge balance in fermentation modeling. From the presented calculations it follows that the definition formula of the so-called degree of reduction is changed due to the ionic character of the fermentation reactants. It is also shown that the macroscopic electric charge balance, together with the ionic equilibria between fermentation reactants, leads to an expression for the calculation of the pH during fermentation. Finally it is concluded that one should be very careful in the estimation of biomass production from the acid or base feed rates which are necessary for pH control.
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  • 86
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    Biotechnology and Bioengineering 23 (1981), S. 1159-1164 
    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 Ill.
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  • 87
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    Biotechnology and Bioengineering 23 (1981), S. 1155-1157 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 88
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    Biotechnology and Bioengineering 23 (1981) 
    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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  • 89
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    Biotechnology and Bioengineering 23 (1981), S. 1169-1169 
    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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  • 90
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    Biotechnology and Bioengineering 23 (1981), S. 1165-1168 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 91
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    Biotechnology and Bioengineering 23 (1981), S. 1193-1202 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The mechanism of Solid particle flotation was used for explaining an alternative route of oxygen uptake by cells situated within the relatively stagnant liquid region adjacent to bubbles in a submerged culture. The Two-phase model of oxygen uptake takes into consideration uptake from both liquid and gaseous phases, the latter being denoted as the direct uptake. Experiments obtained with yeast cultures on different substrates were used to evaluate the proportion of both types of uptake. The combined model provides a better fit to experimental data compared to the one-phase model which omits the direct uptake. The results are discussed from the viewpoint of the enhancement of oxygen absorption by cells present near the interface.
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  • 92
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    Biotechnology and Bioengineering 23 (1981), S. 1171-1191 
    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 present work methods and results of investigations on optimal construction of fermentor elements by multifactor planning at a random number of levels of any factor are presented. The optimal design of column fermentor of 0.02-100 m3 volume with sieve plates containing downcomers and with power introduced by aerating gas has been worked out. Several alternative designs have been compared by examining mass transfer rates, power requirements, and other operating characteristics. Several fermentor designs with the power introduced by aerating gas are discussed with respect to their performance for cultivating various microorganisms (yeast and bacteria).
    Additional Material: 9 Ill.
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  • 93
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 1237-1254 
    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 temperature control policy for an immobilized glucose isomerase reactor system was studied. This optimization study takes into consideration the enzyme deactivation during the continuous reactor operation. The Kinetic parameters including reduced Michaelis-Menten constant (K̄m), reduced maximum reaction rate (V̄m), equilibrium constant (Ke), and enzyme deactivation constant (kd) and their functional relationships to temperature were determined experimentally. The optimization problem was formulated in terms of maximization of fructose productivity as the objective function. The optimization problem was solved by making use of a maximum principle and the control vector iteration method. Approximately optimal temperature control policy was employed as compared with the reactor operation at an optimum constant temperature.
    Additional Material: 10 Ill.
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  • 94
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 1219-1236 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The thermal of free and immobilized α-chymotrypsin was investigated experimentally and theoretically. The inactivation process of free α-chymotrypsin was analyzed with a kinetic model which included a first- order reaction process and autolysis. The effects of ionic strength, Ca2+ concentration, and temperature are discussed here in terms of the estimated kinetic parameters included in this model. The inactivation process of α-chymotrypsin immobilized onto various supports by several methods was investigated. The Contribution of thermal denaturation and autolysis to the inactivation depended upon the method of immobilization. To interpret quantitatively the non-first-order thermal denaturation process of the immobilized enzyme, a model in which the heterogeneity of the immobilized enzyme was taken into account is proposed.
    Additional Material: 11 Ill.
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  • 95
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 1255-1265 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An improved process for the isolation of thienamycin, produced by the actinomycete Streptomyces cattleya, has been developed. The isolation procedure consists of three chromatographic steps, volume reduction by reverse osmosis between the steps, and freezedrying for obtaining the final product. The chromatographic steps are as follows: (1) ion exchange chromatography on Dowex 1 × 2 resin in the bicarbonate cycle, (2) gel chromatography on Dowex 1 × 2 resin in the chloride cycle, (3) reverse phase chromatography on XAD-2 resin. This procedure is useful for processing large volumes of fermentation broth.
    Additional Material: 5 Ill.
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  • 96
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 1203-1218 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Using Cudrania tricuspidata cells as model plant cells which have high sensitivity to hydrodynamic stress, technology problems in the cultivation of the plant cells at high density were investigated. Using “shake” flasks on a reciprocal shaker and Erlenmeyer flasks on a rotary shaker and with a high supply of oxygen on order to obtain high cell densities in shaken cultures, particles breakdown and damage to the largest cell aggregate group (above 1981 μm in diameter) occurred and normal cell growth became impeded. The mass-transfer coefficient (K)for a model solid-liquid system (β-naphthol particles and water) in place of a system of plant cells and a liquid medium was proposed as an intensity index of hydrodynamic stress effects on plant cells in subsequent cultures under various conditions in the bioreactor systems. Normal cell growth was obtained under culture conditions for K values less than about 4.4 × 10-3 cm/sec. The characteristics of various bioreactors used until now were investigated by considering the three main technological factors (capacity of oxygen supply, intensity of hydrodynamic stress effects on plant cells, and intensity of culture broth mixing and air-bubble desperation). The most suitable bioreactor for culturing plant cells at high density was ajar fermentor with a modified paddle-type impeller (J-M). The yield of cell mass in the 10-liter J-M (working volume 5 liter) was about 30 g dry weight per liter of medium.
    Additional Material: 10 Ill.
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  • 97
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 1267-1287 
    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 and develops a process for large-scale production of glycerol by means of a hemophilic algae. The process is shown to be economically and technically feasible. Although the proposed process is extremely capital intensive, the total production cost is competitive with existing glycerol process. In addition, the overall energy requirement is much lower than that of the petrochemical process. This proposed process provides an alternative route for glycerol production that is minimally dependent on fossil fuels and is therefore, less sensitive to crude oil availability and price. The primary raw material carbon dioxide from stack gas, is an inexpensive and renewable resource. Maximal Utilization of solar energy is made not only in the glycerol synthesis steps but also in the product recovery system. Significant improvement in the process economics can be realized through further development of large-scale cultivation technology, and biomass distribution and collection machinery. Due to the labor intensive nature of the proposed algal process, it is particularly suitable for less developed nations with limited fossil fuel resources and lower labor costs.
    Additional Material: 8 Ill.
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  • 98
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 1297-1307 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Use of Ultrafiltration membrane systems in stirred cell and in thin-Channel systems for immobilizing enzyme (sweet potato intrinsic and β-amylase) in hydrolysis of sweet potato through a continuous operation mode were studied. Both the filtration rate and reducing sugars, produced as the result of enzymatic hydrolysis, decreased with the filtration time. The immobilized enzymes in the thin-channel system showed a much better performance compared to that in the stirred cell system. Addition of crystalline sweet potato β-amylase to the sweet potato increased both the filtration rate and reducing-sugars content. Alcoholic fermentation of the filtrate resulted in an alcohol content of 4.2%. This represented fermentation of 95% of the sugars with an efficiency of 88%.
    Additional Material: 4 Ill.
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  • 99
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 1289-1296 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fermentation of xylose by Klebsiella pneumoniae (ATCC 8724) producers meso and nonmeso 2,3-butaneodiol. The enzyme Kinetic of 2,3-butanediol stereoisomer formation from acetone is currently under study in our laboratory. Modeling of these kinetics requires resolution of meso and racemic 2,3-butanediol and positive identification of these resolved components. We report their resolution by aqueous liquid chromatography on both an analytical and a preparative scale. The resolved stereoisomer were identified by a combination of gas chromatography, gas chromatography/mass spectroscopy, 13C-NMR spectroscopy, optical activity, and, melting points of the m-dinitrobenzoyl eaters of meso and racemic 2,3-butanediol. An aqueous liquid chromatographic technique for resolving and qualifying major components of a butanediol fermentation mixture in 40 min is presented.
    Additional Material: 9 Ill.
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  • 100
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 1309-1324 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A previously presented model for an airlift fermentor is extended by considering the variations of pressure along the tubes. The fluid dynamics of the system is represented with the acid of correlations obtained from experiments. Only oxygen concentrations are considerations are considered. The influences of the various parameters affecting the system are analyzed. The model allows prediction of oxygen concentrations in the different points of an airlift fermentor and calculation of the best values of the gas flow rate.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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