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  • 1970-1974  (295)
  • 1973  (295)
  • Engineering General  (189)
  • Biochemistry and Biotechnology  (106)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 93-115 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Collagen was used as carrier for the immobilization of invertase, lysozyme, urease, glucose oxidase, penicillin amidase, and glucose isomerase. Immobilization was accomplished by either impregnation of a preswollen collagen membrane with enzyme solution or electrocodeposition of collagen and enzyme from a collagen dispersion containing dissolved enzyme. The collagen-enzyme complexes prepared are in membrane form.Membranous collagen-enzyme complexes were used to construct biocatalytic reactors such as the capillaric coil modular reactor. Such biocatalytic reactors were used in a recirculation system for the conversion of substrates. The biocatalytic reactors showed initial decreases of activity to stable limits which are maintained over a large number of reactor volume replacements. The stable limits correspond to approximately 35% of the initial activities for lysozyme and invertase, 25% for urease, 15% for glucose oxidase.The mechanism of complex formation between collagen and enzyme involves multiple salt linkages, hydrogen bonds, and van der Waals interactions. This protein-protein interaction which leads to stable complexes by both impregnation and electrocodeposition processes is unique among the enzyme immobilization methods currently available.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 163-179 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Kinetic studies on the growth of Aspergillus strains as well as constitutive and inductive polygalacturonase formation have been made in bath fermentations, without pH control. Equations describing growth and product formation of the four-stage growth of microorganisms were applied for the first time to diauxic growth and enzyme formation of Aspergillus strains. Diauxic growth of the cultures has been found in both sucrose- and peetin-containing media. Enzyme concentration in the second transient phase, calculated by the use of new equations, proved to be negligible. In the exponential and declining phases, the calculated values of mycelial and enzyme concentrations were in good agreement with the values observed. Types of classification of the product formation of Luedeking and Piret refer to the second cycle of diauxie. The types of product formation described by Kono and Asai and Luedeking and Piret are mostly in good agreement with each other. The greatest difference has been found in the case of inductive endo-polygalacturonase formation, where the final enzyme formation could not be plotted because of the decrease (autolysis) in mycelial weight.
    Additional Material: 12 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 225-237 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Xanthan gum, a heteropolysaccharide with unusual and useful properties, is now produced commercially by fermentation with Xanthomonas compestris NRRL B-1459 in a medium containing glucose, minerals, and a complex nitrogen source - distillers' dried solubles (DDS). Understanding the kinetics of the fermentation should contribute to process improvements and increase the market potential for the gum. Earlier studies showed that although DDS determined initial growth rate, growth was stopped by some mechanism other than substrate exhaustion, probably an effect related to product formation.Product formation did not require active growth, but its rate increased with cell concentration. Specific product formation rate declined at high viscosities. Varying glucose concentration from 0.5 to 5.0% and dissolved O2 tension between 20 and 90% air saturated had no effect on the rates, but pH had to be maintained near 7 and temperature near 28°C to permit continued product formation. Xanthan yield could be explained by the energy required for growth and polymerization, that energy coming from dissimilation of the part of the carbohydrate substrate not converted to polymer.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 285-297 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Several strains of bacteria, isolated from marine environments, were characterized for their hydrocarbon oxidizing abilities using a complex synthetic mixture of hydrocarbons. Attempts were made at a broad classification of these organisms on the basis of their behavior towards four major groups of hydrocarbons, normal paraffins, iso-paraffins, cyclo-paraffins, and aromatics, known to be present in crude oils. Although bacteria appear to be able to oxidize hydrocarbons at random, this study has shown that it may be possible to recognize a rudimental pattern if we view their oxidative abilities in terms of groups of hydrocarbons rather than individual compounds. A study of the action of combined strains on the synthetic hydrocarbon mixture was performed. It was found that no particular benefit could be derived as compared to the use of single strains.
    Additional Material: 2 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 299-308 
    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 potassium sorbate addition to a continuous culture of Saccharomyces cerevisiae was observed. The influence on the yeast performance depended on the way the inhibitor was added. The unsteady state continuous method seems to be the best one to obtain microorganisms' adaptation to inhibitors, and for the experimental study of microbial inhibition.
    Additional Material: 11 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 331-358 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Insofar as saturation kinetics are applicable to the growth of phytoplankton in laboratory experiments and to growth in nature, the computer modeling of intracellular nutrient partitioning in populations of cells can lead to better understanding of the dynamics of natural populations.A three-compartment mathematical model was developed to represent a phytoplankton population having the capability to store nitrogen in a nitrate-limited environment. Parameters were estimated by fitting the model to data from two chemostat experiments reported by Caperon (1968). The model was used to simulate growth dynamics observed in chemostat and batch experiments. The model demonstrated the changes which may occur in the nitrogenous constituents of a phytoplankton population with time and environmental conditions. The model also demonstrates three phenomena which have been observed in field and laboratory experiments but which are not represented by the customary Monod model: (1) uptake rates may significantly exceed not growth rates, (2) high growth rates may be encountered at very low environmental nitrate concentrations, and (3) the ratio of internal nitrogen to population size may change significantly during a study period. It is suggested that the amount of nitorgen in storage may be used as an indicator of the physiological state of a monospecific population.Parameters for the one-compartment Monod model were estimated by customary methods form data generated by the three-compartment model. It was shown that difficulties encountered in estimating the yield coefficient and the decay coefficient may be attributed to the intracellular storage phenomenon. It was also demonstrated that the one-compartment Monod model was inadequate to accurately represent population growth in chemostat experiments when intracellular storage is a significant factor.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 441-445 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 447-453 
    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 and efficient system for continuous ATP regeneration is described. The procedure is based on the enzyme-catalyzed reaction between carbamyl phosphate and ADP. The carbamyl phosphate was generated in situ by reaction between potassium cyanate and potassium phosphate. The enzyme, carbamyl phosphokinase, was isolated from extracts of Streptococcus faccalis and partially purified. Immobilization of the enzyme was achieved using glutaraldehyde-treated alkylamine glass giving 200-250 units of activity per gram of glass. A column of carbamyl phosphokinase on glass was used to form ATP continuously from ADP, phosphate, and cyanate and lost approximately 16% of the initial activity after 14 days operation at room temperature.
    Additional Material: 2 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 455-466 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Papain was covalently coupled to ZrO2-coated porous glass by several different methods. These derivatives were characterized and their operational half-lives determined using casein substrate. Papain covalently coupled to the porous glass, previously converted to a carboxylic acid derivative, through amide linkage gave a 35 day operational half-life.
    Additional Material: 7 Ill.
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  • 10
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A double polarographic device is described which permits regulation of dissolved oxygen concentration at any preset pO2 in suspensions or cultures of photosynthetic algae. It also simultaneously permits measurements of the rate of oxygen evolution during photosynthesis. The apparatus is designed to operate in closed vessels in the absence of a gas phase, and may be used at increased pressures tested up to 500 atmospheres. Regulation of oxygen levels was maintained constant at various preset concentrations equivalent to atmospheric pO2 values ranging between 0.02 and 0.21 at 25°C.
    Additional Material: 6 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 493-503 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Penicillin amidase, an enzyme which hydrolyzes benzylpenicillin to 6-aminopenicillanic acid and phenylacetic acid, is produced by Bacillus megaterium ATCC 14945 as an extracellular enzyme. We used this system as a model to examine the effects of nitrogen, sulfur, and phosphorous limitation on enzyme production in continuous culture. For these studies, we developed a minimal medium for B. megaterium which contained histidine as the sole nitrogen source. Batch experiments showed that this enzyme is produced as a growth-associated metabolite. Enzyme production was shown to be a function of the growth-limiting conditions and the concentration of the inducer, phenylacetic acid. Sulfur limitation in continuous culture yielded enzyme activities approximately three to five times those observed in nitrogen- and phosphorous-limited chemostats. These results are discussed in terms of the environment's influence on enzyme production in continuous culture.
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 561-563 
    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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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 579-581 
    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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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 603-606 
    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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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 649-675 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Oxidation rates of several alkane substrates by C. lipolytica ATCC 8661 grown on n-dodecane were determined using a Warburg Respirometer. Substrates were emulsified using Span 20, Span 80, Tween 20, Tween 80, and Triton X-100 surfactants and the effects of these surfactants on oxidation and growth were determined. The oxidation rates of a number of intermediates, including lauric acid and lauryl alcohol, were also assessed. Responses of dodecane-grown C. lipolytica to select substrates were compared to the corresponding behavior with glucose-grown yeast and with baker's yeast. The role of surfactants in hydrocarbon fermentations is discussed in the light of the present and previously published data.
    Additional Material: 9 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 729-741 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Twenty-eight Penicillium cultures were screened for dextranase activity. Dextranase yield of about 2000 DU/ml was obtained with Penicillium funiculosum SH-5. Maximum dextranase concentration was attained only when cell mass decreased. The kinetics of the dextranase production was correlated with the cell mass by a two-parameter model. The optimum pH and temperature for dextranase were 5.0-5.5 and 55°C, respectively. Crude dextranase preparation was inhibitory to insoluble glucan formation by streptococcus mutans 6715 in vitro.
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  • 17
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: 5′Xanthylic acid was efficiently converted to 5′guanine nucleotides (5′GMP, 5′GDP, and 5′GTP) without being degraded to guanine via 5′GMP by decoyinine resistant mutants of strain KY 13315 which had been isolated from Brevibacterium ammoniagenes and was practically devoid of 5′nucleotide degrading activity. The concentration of phosphate in the medium showed a profound effect on the ratio of the accumulated 5′guanine nucleotides, making it possible to direct the fermentation towards 5′GMP or 5′GTP. A direct accumulation of 5′guanine nucleotides from carbohydrate was possible by mixed cultivation of a 5′XMP accumulating strain and a 5′XMP converting mutant. A maximum concentration of 9.67 mg of 5′guanine nucleotides per ml was obtained directly from glucose in such a mixed culture.
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 819-820 
    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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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 833-843 
    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 characteristics of Thermomonospora fusca, a cellulolytic thermophilic actinomycete, are described in terms of growth on pulping fines, a cellulosic waste of the paper industry. A fermentation was developed which substantially degrades this waste, with the residual product of growth containing about 30% microbial protein. This protein, as shown by a preliminary feeding study with baby chicks and by amino acid analyses, appears to be of good nutritional quality and contains no strongly toxic materials. The extracellular cellulolytic enzymes present in the spent broth are discussed in relation to their potential recovery as a by-product of the fermentation, as is also the possible use of the fermentation as a waste disposal system.
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  • 20
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 897-903 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experiments are reported in which a mixed population of organisms was continuous cultured on phenol in a 1- to 2-liter well-mixed vessel. Steady state phenol concentrations were measured for a range of inlet concentrations from 100 to 800 mg/liter at various dilution rates. These results were compared with those predicted from a model which incorporates the effect of wall growth. It was found that the effect of growth on the walls of the vessel was considerable and increased by a factor of up to 3 × the dilution rate at which 90% conversion of phenol could be obtained.
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  • 21
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 927-932 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bacteriophage Φ × 174 was produced in 20 and 200 liter fermentors. The phage was concentrated without any loss of infectivity by precipitation with 10% (w/v) Poly(ethylene glycol) 6000 in 0.5M NaCl. The total yield of a 100 liter culture is around 1016 infectious particles. The final purification step in a CsCl gradient results in a 60 to 80% inactivation.
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  • 22
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 973-979 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A glutamic acid producing microorganism (Corynebacterium glutamicum) is entrapped in a polyacrylamide gel. These immobilized microorganisms were used to produce glutamic acid in successive batches of fresh medium. Free microorganisms similarly used produced much less glutamic acid under similar conditions.
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  • 23
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 1011-1016 
    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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  • 24
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 1023-1037 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Studies are reviewed on the composition of hemolymph from Japanese beetle larvae, Popillia japonica. This research was conducted to determine the chemical environment required for sporulation of the milky disease organism, Bacillus popilliae. Amino acids, proteins, organic acids, lipids, carbohydrates, and oxygen content were determined in hemolymph from healthy and diseased larvae. Oxygen content of hemolymph was measured by microelectrodes implanted in the hemocoel of living larvae. Vegetative growth of the pathogen reduces the dissolved oxygen; however, as sporulation occurs, oxygen concentration approaches normal values. Trehalose, the major hemolymph sugar, is reduced by ca. 50% during the course of milky disease. Neutral lipids, phospholipids, and hydrocarbons decrease markedly with infection. Both branched-chain and normal alkanes occur in hemolymph. Milky disease causes an increase in concentration of pyruvic, malic, glycolic, tartaric, and glyoxylic acids. The major hemolymph protein, a lipoglycoprotein, has a mol. wt. of ca. 500,000. Reduced concentration of this protein is accompanied by the appearance of a smaller protein. Amino acids that increase significantly as a result of infection are: Glutamic acid, aspartic acid, β-alanine, phenylalanine, threonine, lysine, and serine. Hemolymph contains few peptides of low molecular weight.
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  • 25
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 1039-1044 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is sometimes easier and cheaper to extract a drug's target sites from cells than it is to purify, concentrate or manufacture the drug itself. This is especially true in the case of DNA and some of the exotic antibiotics that react with it. Phleomycin, an inhibitor of replication, was considered as a specific case in point. Biologically active components of this antibiotic mixture bind nondestructively to DNA, in vitro and in vivo, and thereafter may be processed by simple, economical methods usually reserved to macromolecules of much greater size.
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  • 26
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Lactate dehydrogenase (LDH) and pyruvate kinase (PK), immobilized on solid glass beads by diazotization, were used in packed bed reactors to analyze for both pyruvate (PYR) and phosphoenolpyruvate (PEP) through the disappearance of β-nicotinamide adenine dinucleotide (NADH) monitored spectrophotometrically at 340 nm. Packed bed reactors containing PK and/or LDH were also capable of monitoring continuously varying concentrations of adenosine-5′-diphosphate (ADP), PEP, and PYR. The immobilized enzymes (∼40 μg/g glass) retained about 4% of the activity of the soluble enzymes. Preparations of immobilized LDH and PK exhibited enhanced stability when maintained in the presence of β-mercaptoethanol and NADH or EDTA, respectively, and were shown to regain 75% of the original activity after four months storage at 4°C.
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  • 27
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An investigation was made on the factors influencing the acetic acid concentration in the culture liquid of the aerobic fermentations where acetie acid was used as a carbon source. The acetic acid concentration in the culture liquid changed in proportion to the amount of unutilizable acid or base supplied. This was explained by the principle of conservation of electroneutrality.Another factor affecting the acetic acid concentration in the culture liquid was bicarbonate ions which were formed by the dissolution and dissociation of carbon dioxide in the gas phase of the fermentor. The increment in bicarbonate ion concentration was equal to the decrement in the acetie acid concentration in the culture liquid.
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  • 28
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 1193-1197 
    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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  • 29
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 13-25 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A rate equation has been derived to describe the hydrolysis of benzylpenicillin to 6-aminopenicillanic acid by penicillin amidase. The integrated from of the rate equation has been shown to predict satisfactorily the progress of the reaction in a batch reactor using either soluble or immobilized penicillin amidase. The rate equation was also used to predict the performance of a continuous feed stirred tank reactor containing immobilized enzyme. There was good agreement with experimental measurements.
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  • 30
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    Biotechnology and Bioengineering 15 (1973), S. 27-45 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The oxygen uptake rate in mycelial pellets of Aspergillus niger was studied experimentally and theoretically. The specific rate of respiration of mycelial pellets was found to decrease significantly with increasing pellet size. The distribution of respiratory activity in the mycelial pellets was evaluated and the specific rate of respiration of disrupted mycelia showed adaptation to the concentration of oxygen in the medium. The decrease of the specific rate of respiration of the mycelial pellets could be estimated according to diameter, mycelial density, oxygen diffusivity, and adaptation to the concentration of oxygen. Good agreement was found between the theoretical analysis and the experimental data.
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  • 31
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Various methods were tried for the immobilization of aspartase, and the preparation having the highest activity was obtained when partially purified aspartase from Escherichia coli was entrapped into polyacrylamide gel Iattice. Enzymatic properties of the immobilized aspartase were investigated and compared with those of the native aspartase. With regard to optimum pH, temperature, concentration of Mn++, kinetic constants and heat stability, no marked difference was observed between the native and immobilized aspartases.By employing an enzyme column packed with the immobilized aspartase, conditions for continuous production of L-aspartic acid from ammonium fumarate were investigated. When a solution of 1M ammonium fumarate (pH 8.5, containing 1mM MnCl2) was passed through the aspartase column at the flow rate of SV = 0.08 at 37°C, the highest rate of reaction was attained. From the column effluents, L-aspartic acid was obtained in a good yield.
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  • 32
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    Biotechnology and Bioengineering 15 (1973), S. 129-142 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Methods for the production of protein concentrates, with a low content of nucleic acid, in kilogram quantities from yeast have been studied with the aid of equipment designed for operation on pilot-plant scale. The influence of drum drying and mechanical disintegration on the nutritive value of the yeast was also investigated. Drum drying and mechanical disintegration improved the nutritive value of the yeast but high extractability of protein and nucleic acid was only obtained after mechanical disintegration.Protein concentrates without and with cell walls were produced from mechanically disintegrated yeast. The different fractions which were obtained when separating cell walls and precipitating protein by heating at alkaline pH, were analyzed. After protein precipitation, about 90% of the RNA could be precipitated from the supernatant by addition of acid, giving a product containing 50% RNA of the dry weight. The protein precipitate obtained after cell wall separation had an RNA content of less than 2% and contained 70-l75% of the amino acids in the starting yeast material. Protein concentrates containing cell walls were produced by precipitating protein by heating at alkaline pH directly after mechanical disintegration. The content of RNA was about 2% and the yield of amino acids was 70-80%. It was found that the nutritive value of the protein concentrate was higher than that of the starting yeast material. To produce such a protein concentrate on a large scale, the process described can probably be employed.
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  • 33
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    Biotechnology and Bioengineering 15 (1973), S. 201-206 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 34
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    Biotechnology and Bioengineering 15 (1973), S. 207-211 
    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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  • 35
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    Biotechnology and Bioengineering 15 (1973) 
    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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  • 36
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    Biotechnology and Bioengineering 15 (1973), S. 257-270 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Candida tropicalis was cultured with n-hexadecane, dispersed in water as submicron droplets, as the only carbon substrate; the emulsion being fed continuously into a fermentor containing only an aqueous medium (fed-batch culture). The results have demonstrated that the organism takes up hydrocarbon accommodated in the aqueous phase as submicron droplets. The cell/substrate yield for the linear growth phase, where growth was limited by the supply of the substrate, was much higher than the yield for the exponential growth phase.
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  • 37
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    Biotechnology and Bioengineering 15 (1973), S. 309-320 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Rotary vacuum precoat filtration of bakers' yeast disrupted in a high-pressure homogenizer is reported. Different precoat materials, knife cutting rates, and body feeds were tested on disrupted yeast suspensions ranging from 10 to 40% wt packed yeast/vol. The flow rates, solids contents, and protein and enzyme concentrations before and after filtration were determined. Filtration rates were found to be independent of precoat thickness during debris filtration. For 20% disrupted yeast, flow rates of up to 17 cm3/cm2/hr were attained at a precoat and body feed usage of 35 kg/1000 liters. By reducing the knife cutting speed to 0.025 mm/min and the body feed to 1% the filter aid usage could be reduced to 13.5 kg/1000 liters while maintaining a flow rate of 9.3 cm3/cm2/hr. In all experiments protein recoveries were in the range of 80-90% and with the four enzymes examined, recoveries ranged from 67-92%. With all the precoats tested, the product had a lower solids content than that obtained from centrifuges capable of processing similar quantities of cell debris.
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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: Many chemical and food processing wastes are deficient in nitrogen, and must therefore be supplemented with domestic sewage or ammonia to dispose of them by conventional biological treatment. A more economical treatment, especially of strong wastes, is possible by maintaining a semipure culture of nitrogen-fixing bacteria in a stirred aerated tank. When operated as a chemostat with 4 to 6 hr detention time, removal of 85% of the COD is possible in a single step without the need for clarifiers or digesters. A clarified effluent could also be produced by flotation or sedimentation of the flocculated bacteria. In that case there would be 99% removal of COD and a reduction in the amount of sludge by two-thirds over the conventional activated sludge process.
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  • 39
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    Biotechnology and Bioengineering 15 (1973), S. 551-560 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A substrain of Bacillus cereus 569/H produced under controlled fermentation conditions in a pilot plant fermentor phospholipase-C. A partially purified preparation showed good storage stability as a lyophylized powder and in frozen solutions. The preparation contained very small amounts of phosphomonoesterase and proteolytic activities and essentially no ribonuclease activity. The level of hemolytic activity of the preparation was much lower than that of a commercial preparation of phospholipase-C from Clostridium. Treatment of sarcoplasmic reticulum membrane with phospholipase-C from B. cereus and from Clostridium showed that the B. cereus enzyme caused hydrolysis of 96% of the membrane phospholipids whereas the enzyme from Clostridium could hydrolyze only 80% of the phospholipids.
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  • 40
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    Biotechnology and Bioengineering 15 (1973), S. 583-588 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 41
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    Biotechnology and Bioengineering 15 (1973), S. 589-596 
    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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  • 42
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    Biotechnology and Bioengineering 15 (1973), S. 607-610 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 43
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    Biotechnology and Bioengineering 15 (1973), S. 677-692 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Eighteen ultrafiltration membranes ranging in molecular weight cutoff ratings from 500 to 300,000 were tested with water, 0.5M NaCl solution, and, in some cases, with macromolecules and urea in a 3-in. stirred filter cell. Approximately half of the membranes showed a significant decrease in filtration rate during the first 24-hr period. The steady-state rates were less than the manufacturers' rating for about two thirds of the membranes, the discrepancy being greater for the membranes with high molecular weight cutoffs.The filtration rates were linearly dependent on applied pressure over the range at least as great as 15 to 55 psig. The rate decreased as the concentration of macromolecules such as transfer ribonucleic acid (tRNA) increased; the rate for a concentration of 3 mg tRNA/per ml was one-fourth of that observed when no tRNA was present. Some increase in rate (∼33 to 50%) was obtained by increasing the stirring speed from 100 rpm to 1000 rpm.The membranes were effective for desalting and concentration of macromolecules but not for separation of large molecules from each other, such as tRNA from bovine serum albumin. Easily denatured molecules such as catalase were not deactivated by filtration at 4°C.
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  • 44
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    Biotechnology and Bioengineering 15 (1973), S. 755-782 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new correlation is given for the prediction of the volumetric coefficient for mass transfer (KLa) in stirred tanks from dispersed gas bubbles to basal salt solutions of ionic strengths representative of fermentation media. The correlation includes the effects of both the operating parameters (agitation power per unit volume and gas superficial velocity) and the physicochemical properties of the system: interfacial tension, viscosity, density, diffusion, coefficient and, in particular, ionic strength. The effect of the latter was found to be most significant in the Newtonian systems of water-like viscosity investigated; no previous correlations have included the effect of ionic strength. KLa values were determined by using a dissolved oxygen probe to monitor the steady-state oxygen tension in continuous flow experiments, and/or the rate of change of oxygen tension in unsteady-state semibatch experiments. In the latter cases, results were computed by a nonlinear, least squares computer program which fitted the experimental data to a model of probe transient response characteristics. The general applicability of the model and the computational procedure was verified by comparing the results to those obtained with the same electrolyte solution in the steady-state mode. The experiments were run over a wide range of agitation power inputs, including those typical of both soluble- and insoluble-substrate fermentations. The correlation appears to be valid for both oxygen mass transfer with and without homogeneous chemical reaction in the liquid phase; in the former case, for example, sulfite oxidation, knowledge of the chemical reaction enhancement factor is required. In addition to predicting oxygen transfer capabilities, the correlation may be used for other sparingly soluble gases of interest in fermentation systems, such as methane, hydrogen, and carbon dioxide.
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  • 45
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    Biotechnology and Bioengineering 15 (1973), S. 811-815 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 46
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    Biotechnology and Bioengineering 15 (1973) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 47
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    Biotechnology and Bioengineering 15 (1973), S. 827-829 
    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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  • 48
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    Biotechnology and Bioengineering 15 (1973), S. 879-888 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The steady state, nonlinear diffusion equations which describe reactions in constrained enzyme solutions are of great interest in many biological and engineering applications. As in other types of nonlinear differential equations, exact analytical solutions do not exist except in some simplified cases. In this paper, a general procedure is presented for solving numerically for the substrate concentration profile and effectiveness factor utilizing the transformation method suggested by Na and Na. Design correlations for enzyme solutions constrained within spherical membranes are included. The use of a unique definition of the Thiele Modulus in these charts permits the clear illustration of the effects of substrate concentration and external mass transfer resistances on the overall effectiveness factor for the catalyst particle.
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  • 49
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    Biotechnology and Bioengineering 15 (1973), S. 905-916 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is shown that two steady states exist in certain regions of operation of a 2-liter continuous stirred tank biological reactor. Transition was made from one steady state to another by applying shock loads of either phenol substrate which is inhibitory to the culture at high concentrations or by adding large additional amounts of concentrated organisms. The existence of the multiple steady states is ascribed to the existence of wall growth, and their position is determined by the amount of wall growth. Transient behavior of the system did not follow the predictions of the simple wall growth model but the culture appeared to undergo a lag period immediately after applying the shock load to the system. It is concluded that the stability of a continuous culture utilizing an inhibitory substrate is improved by increasing the degree of wall growth and decreasing the substrate feed concentration. It is also concluded that small scale experiments can usually not be interpreted correctly unless the effect of wall growth is taken into account.
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  • 50
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    Biotechnology and Bioengineering 15 (1973), S. 963-972 
    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 minimize product toxicity, decrease fermentation cost, prolong the effective production phase, and shorten the lag phase before production in the citrate-hydrocarbon fermentation by Candida lipolytica ATCC 8661, the use of a nonsterile semicontinuous cell recycle system was investigated. Model experiments demonstrated that portions of the fermentor broth could periodically be removed and centrifuged under nonaseptic conditions with the cells being added to fresh medium and returned to the fermentor. Citrate production continued, however with repeated semicontinuous cell recycle, acid production gradually decreased. It was postulated that this decrease could be attributed largely to physiological trauma and that a truly continuous cell recycle system would minimize these effects and permit maintenance of higher citrate production rates.
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  • 51
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 52
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    Biotechnology and Bioengineering 15 (1973), S. 1075-1080 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The isolation and structure determination of a new microbial product, (+)- (123/45)-2,3,4,5-tetrahydroxy-1-cyclohexanemethanol is described. This product was detected in the fermentation broth of a newly isolated actinomycete by its antibacterial activity. A novel isolation method was developed and crystalline product was obtained in good yield. The structure was determined by spectroscopic examination of the product and its acetyl and trimethylsilyl derivatives. The racemic form of this compound had already been synthezised by G. E. McCasland et. al., as analog of galactose.
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  • 53
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    Biotechnology and Bioengineering 15 (1973), S. 1123-1129 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cellulase production by strains of Myrothecium verrucaria, Stachybotrys atra and Trichoderma viride was examined. Myrothecium verrucaria was found to give the greatest yields. A variety of media were examined as potential substrates for the industrial production of cellulase. The salts content of the medium was varied and was found to affect cellulase production. Glucose, carboxymethylcellulose (CMC), filter paper and three industrial wastes were examined as possible cellulase inducers. Filter paper was found to be the most effective, followed by sugar cane bagasse and CMC.
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  • 54
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    Biotechnology and Bioengineering 15 (1973), S. 1159-1177 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A simplified model of cell metabolism, consisting of a series of linked reversible enzymatic reactions dependent on the concentration of a single external substrate has been developed. The general mathematical solution for this system of reactions is presented. This general solution confirms the concept of a rate-limiting step, or “master reaction”, in biological systems as first proposed by Blackman. The maximum rate of such a process is determined by, and equal to, the maximum rate of the slowest forward reaction in the series.Of practical interest in modeling the growth rate of cells are three cases developed from the general model. The simplest special case results in the Monod equation when the maximum forward rate of one enzymatic reaction in the cell is much less than the maximum forward rate of any other enzymatic reactions.More realistic is the case where the maximum forward rates of more than one enzymatic reaction are slow. When two slow enzymatic reactions are separated from each other by any number of fast reactions that overall can be described by a large equilibrium constant, the Blackman form results: \documentclass{article}\pagestyle{empty}\begin{document}$$\mu = [S]/A, \rm{when} [S] 〈 A\mu_{\rm{max}}$$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$$\mu = \mu_{\rm{max}}, \rm{when} [S] \rm{〉} A\mu _{\rm{max}}$$\end{document}A third case is that in which two slow enzymatic steps are separated by an equilibrium constant that is not large. Unlike the Monod and Blackman forms, which contain only two arbitrary constants, this model contains three arbitrary constants: \documentclass{article}\pagestyle{empty}\begin{document}$$[S] = \mu A + \frac{{\mu B}} {{(\mu_{\rm{max}} - \mu)}}$$\end{document}The Monod and Blackman forms are special cases of this three constant form.In comparing equations with two arbitrary constants the Monod equation gave poorer fit of the data in most cases than the Blackman form. It is concluded that workers modeling the growth of microorganisms should give a t least as much consideration to the Blackman form as is given to the Monod equation.
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  • 55
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    Biotechnology and Bioengineering 15 (1973), S. 1189-1192 
    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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  • 56
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    Biotechnology and Bioengineering 15 (1973), S. 395-402 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A yeast lactase, Maxilact, was immobilized in crosslinked polyacrylamide using a bead-polymerization technique. The polymer beads obtained, containing the entrapped enzyme, were used for the preparation of lactose-free milk. The binding yield of the enzyme and residual enzymic activity in the “enzyme beads” were studied as a function of the amounts of monomeric acrylamide and cysteine and bovine serum albumin present as protecting agents in the monomer-enzyme solution prior to polymerization. A maximum of about 75% of the enzyme could be immobilized using a 20% (w/v) solution of acrylamide plus N, N′-methylenebis-acrylamide, whereas the highest activity quotient (bound to free) of about 60% was observed on using a 25% solution. The presence of cysteine increased the activity by up to 30% and that of serum albumin up to about 15%.
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  • 57
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    Biotechnology and Bioengineering 15 (1973), S. 419-439 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The synthesis of extracellular enzymes by microorganisms frequently occurs under genetic control. A simple two-parameter model is developed describing the degree of repression or induction in fermentation media.The case of substrate utilization by an extracellular enzyme was analyzed for a vegetable oil-lipase-yeast system. It is shown that fatty acids released by the lipase may accumulate in the early stage of growth and exert an influence on the limiting after which relatively little repression or induction takes place.Expressions are also derived for growth and extracellular enzyme synthesis in single-and multistage continuous cultures. When the cells grow on a directly available soluble substrate, the specific enzyme synthesis is maximal at low dilution rates in the case of repression and at high dilution rates in the case of induction. If the substrate is not directly available, a single continuous stirred tank reactor stage may not be sufficient for efficient substrate utilization; for fermentation processes where an insoluble has to be broken down before the cells can assimilate it, a plug flow type fermentor rather than a mixed chemostat may prove more satisfactory.
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  • 58
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    Biotechnology and Bioengineering 15 (1973) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 59
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    Biotechnology and Bioengineering 15 (1973), S. 933-949 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The response of aerobically growing heterogeneous microbial populations of sewage origin to step increases and decreases in pH were studied in both once-through and cell recycle systems. The pH range studied was 2.7 to 8.0. All studies were conducted at a dilution rate of 0.125 hr-1, and all shocks were administered from a base or preshock pH level of 6.4 to 6.7. In each experiment, the preshock or initial “steady state” was assessed, the pH of the feed changed, and the resulting transient behavior of the system examined until attainment of the new or final “steady state” was approached. The major objectives of the work were to characterize the nature of the response with respect to biomass and effluent substrate concentrations, types of microbial populations present and chemical composition of the biomass, and to obtain guidelines as to allowable change in pH in waste streams. It was found in once-through systems that substrate removal efficiency recovered from pH levels as low as 3.0 after rather long periods of transient leakage of substrate. Cell recycle attenuated the severity of substrate leakage. In all cases of severe acid shock, the microbial population changed from predominantly bacterial-protozoan to one consisting predominantly of filamentous fungi. Changes in chemical composition of the sludge (protein and carbohydrate content) were consistent with the population changes. Based upon the results, it can be conservatively estimated that changes in pH of no more than one unit from the neutral preshock range can be tolerated without possible disruption of biochemical efficiency of substrate removal.
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  • 60
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    Biotechnology and Bioengineering 15 (1973), S. 981-992 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Wheat germ agglutinin protein, which is able to agglutinate tumor cells better than normal cells, was covalently bound to polyacrylamide gel beads. The specific binding activity of the protein was preserved on these beads and was expressed heterogeneously by the binding of mouse leukemia cells (L1210) to the protein coupled gels. The selective activity of the immobilized protein was maximal when the number of sites available to covalently couple the protein was lowest. The application of this observation to the general field of covalent immobilization of proteins and enzymes may be of considerable utility.
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  • 61
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    International Journal for Numerical Methods in Engineering 6 (1973), S. 441-442 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
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  • 62
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    International Journal for Numerical Methods in Engineering 6 (1973), S. 427-439 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Stress fields near crack tips in an elastic body can be specified by the stress intensity factors which are closely related to the stress singularities arising from the crack tips. These singularities, however, cannot be represented exactly by conventional finite element models. A new method for the analysis of stresses around cracks is proposed in this paper on the basis of the superposition of analytical and finite element solutions. This method is applied to several two-dimensional problems whose solutions are obtained analytically, and it is shown that their numerical results are in excellent agreement with analytical ones. Sufficiently accurate results can be obtained by the conventional finite element analysis with rather coarse mesh subdivision. Computational efforts are then considerably reduced compared with other methods.
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    International Journal for Numerical Methods in Engineering 6 (1973), S. 443-446 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: This paper compares the results obtained by the finite element method with ‘exact’ solutions to a given set of problems. These are the stresses on the boundary of a hole in an infinite plate, the plate being subjected to three different types of loading. Two types of element are used for these plane stress problems, triangular elements with constant strains and tri- angular elements with linearly varying strains. The problems are solved for two different meshes and the results shown are stresses along a radial section and the values derived for stress concentrations against the number of unknowns in each mesh.
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    International Journal for Numerical Methods in Engineering 6 (1973), S. 446-447 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 6 (1973) 
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    International Journal for Numerical Methods in Engineering 6 (1973), S. 475-487 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: An essential feature of finite element methods of analysis for symmetrically loaded shells of revolution is the setting up of equations representing the response of a short ‘ring’ element to edge loading.In this paper the axisymmetric behaviour of a short elastic cylindrical shell element under edge loading is described in a new way by means of a matrix which is a combination of stiffness, flexibility and ‘neutral’ sub-matrices. The coefficients of the matrix are derived direct from the equations of the problem, which involves a trivial amount of work in comparison with conventional methods.The corresponding matrix for a short section of an arbitrary shell of revolution is set up with little additional effort, and its use is described for calculation of edge response coefficients for portions of spherical shells.Finally, the method is used to study by iteration the behaviour of a thin spherical shell of viscous material containing a rigid boss which is loaded radially inwards: changes in meridional profile are followed as deformation proceeds. Results are presented for both linear and non-linear viscous material.
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    International Journal for Numerical Methods in Engineering 6 (1973), S. 497-509 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A computer program for the in-core solution of large, sparse, unsymmetric systems of linear equations is presented in this paper. The program employs elimination techniques for solution of systems of linear equations. A limited number of zeros is stored and trivial arithmetic is by-passed to preserve computer storage and to reduce the time required for solution. Several techniques for selecting the pivotal elements are discussed and their effect on accuracy and computational time are examined.
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    International Journal for Numerical Methods in Engineering 5 (1973), S. 383-394 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Recent publications have emphasized the advantages of the sparseness of the over-all stiffness matrix of a structure. An alternative to setting up the over-all stiffness matrix is to use sub-structures. The main purpose of this paper is to show that there is equivalence between these two approaches when rows are not interchanged. It follows that a sparse matrix method can never be more efficient than the sub-structure method, if a suitable choice of sub-structures is assumed. However when identical sub-structures are contained within a structure the repetition can be utilized by the sub-structure method. In such cases the sub-structure method will often be quicker than the best sparse matrix solution.
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    International Journal for Numerical Methods in Engineering 5 (1973), S. 419-442 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A finite element formulation for flow of fluid in a porous elastic media has been derived from a Gurtin type variational principle. Biot's field equations for porous media have been used in which the constitutive relations include the compressibility of the fluid. It has been shown that by proper choice of the form of the compressibility of the fluid as a function of the state variables, this option of the formulation can be used to treat the partially saturated soil. The method is general with respect to geometry, boundary conditions and material properties. Finally, the results of a series of examples have been presented and compared with exact results to demonstrate accuracy and applicability.
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    International Journal for Numerical Methods in Engineering 5 (1973), S. 395-418 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: This article presents an efficient digital computer procedure, along with the complete listing of the associated computer program, which may be conveniently utilized for the accurate solution of a wide range of practical eigenvalue problems. Important applications of the present work are envisaged in the natural frequency analysis of spinning structures discretized by the finite element technique, and in the determination of transfer function associated with the dynamic blocks of control systems of spacecraft utilizing gas jets or reaction wheels for attitude control, as well as of spin-stabilized and dual-spin-stabilized satellites.The validity of the Sturm sequence property is first established for the related matrix formulation involving Hermitian and real symmetric, positive-definite matrices, both being usually of highly banded configuration. A numerically stable algorithm based on the Sturm sequence method is then developed which fully exploits the banded form of the associated matrices. The related computer program written in FORTRAN V for the JPL UNIVAC 1108 computer proves to be extremely fast and economical in comparison to other existing methods of such analysis. Numerical results are presented for spinning bent cantilever beam and the solar arrays of SKYLAB, the earth-orbiting space station proposed by NASA.
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    International Journal for Numerical Methods in Engineering 5 (1973), S. 443-446 
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    Notes: To isolate the relative accuracy in the numerical approximation of the natural boundary conditions, a plane- stress example is presented for which the field equations using finite element and finite difference methods are identical. For this example, and by implication a wider class of problem, it is demonstrated that by using conventional practice in both methods the implicit representation of the natural boundary conditions in the finite element gives rise to a lower numerical accuracy than that in the less convenient explicit satisfaction of these boundary conditions in finite difference method.
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    International Journal for Numerical Methods in Engineering 5 (1973), S. 446-449 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: This note presents a FORTRAN sequence for solving a particular case of the ‘bounded variables’ problem.1 It is this problem, rather than the standard linear programming problem, which appears when systematic matrix methods are applied to the rigid-plastic collapse analysis of a plane frame or truss The method uses considerably less storage than a standard simplex approach, and produces the collapse mode as a by-product of the calculation. The sequence is part of a complete program for the plastic collapse analysis of frameworks, details of which may be obtained from the author.
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    International Journal for Numerical Methods in Engineering 5 (1973), S. 452-452 
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  • 75
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    International Journal for Numerical Methods in Engineering 5 (1973) 
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    International Journal for Numerical Methods in Engineering 5 (1973), S. 449-452 
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    Notes: The problem of small sinusoidal oscillations imposed on a stagnation point flow is considered. This leads to an ordinary differential equation which, in the high frequency limit, has a simple solution. An iterative method (involving a linear integral operator) is developed, starting from this basic solution. This scheme, performed numerically, is ‘under-relaxed’ and this renders it applicable to as wide a frequency range as possible: convergence criteria are discussed in terms of the relaxation parameter. The streamwise velocity profiles computed are compared with those given by an independent method.
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    International Journal for Numerical Methods in Engineering 5 (1973), S. 455-458 
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    Notes: Some finite element solutions for the Saint Venant torsion problem accounting for orthotropy, inhomogeneity and multiply connected sections are presented. The Prandtl stress function formulation is used. The stresses, torsional stiffness and warping function are calculated. On the basis of various approximations using higher order elements the choice of ‘the best’ element is discussed.
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    International Journal for Numerical Methods in Engineering 5 (1973), S. 481-497 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A finite element method for solving Laplace's, Poisson's and Helmholtz's equations in the axisymmetric case is developed. Complete polynomial functions of arbitrarily high order are used as basis functions. Each triangular element is described by a matrix equation involving cotangents of the vertex angles, the vertex co-ordinates and the triangle area, as well as certain universal numeric matrices. The method of obtaining these matrices is given in detail. The matrices depend only on the polynomial order; values of all matrices to sixth order inclusive have been computed. Important properties of the matrices are discussed and simple example problems are presented.
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    International Journal for Numerical Methods in Engineering 5 (1973), S. 465-479 
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    Notes: A method of viscoelastic contact stress analysis introduced in an earlier paper10 is developed further to treat two problems: the steady-state rolling of a cylinder and axisymmetric impact of a sphere. The procedure is equally applicable to a medium of infinite depth (half-space) or to a slab of finite thickness. The analysis is based on the computation of a set of viscoeiastic influence coefficients. To find the pressure distribution on the instantaneous contact surface, point matching is used. In the rolling problem, a study is made of such phenomena as critical speed and the effect of medium thickness through a comparison with existing results. The impact problem is solved in an iterative scheme of successive approximations. An example is presented for the study of typical impact parameters.
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    International Journal for Numerical Methods in Engineering 6 (1973), S. 603-606 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 6 (1973), S. 606-607 
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    International Journal for Numerical Methods in Engineering 6 (1973), S. 607-608 
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    International Journal for Numerical Methods in Engineering 6 (1973), S. 608-608 
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    International Journal for Numerical Methods in Engineering 7 (1973) 
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    International Journal for Numerical Methods in Engineering 6 (1973), S. 608-608 
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    International Journal for Numerical Methods in Engineering 7 (1973), S. 1-15 
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Turbulent boundary-layer flows of non-reacting gases are predicted for both internal (nozzle) and external flows. Effects of favourable pressure gradients on two eddy viscosity models were studied in rocket and hypervelocity wind tunnel flows. Nozzle flows of equilibrium air with stagnation temperatures up to 10,000°K were computed. Predictions of equilibrium nitrogen flows through hypervelocity nozzles were compared with experimental data. A slender spherically blunted cone was studied at 70,000 ft altitude and 19,000 ft/sec in the earth's atmosphere. Comparisons with available experimental data showed good agreement. A computer program was developed and fully documented during this investigation for use by interested individuals.
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    Notes: This article presents an efficient and numerically stable algorithm, along with a complete listing of the associated computer program, developed for the accurate computation of specified roots and associated vectors of the eigenvalue problem Aq = λBq with band symmetric A and B, B being also positive definite. The desired roots are first isolated by the Sturm sequence procedure; then a special variant of the inverse iteration technique is applied for the individual determination of each root along with its vector. The algorithm fully exploits the banded form of relevant matrices, and the associated program written in FORTRAN V for the JPL UNIVAC 1108 computer proves to be most significantly economical in comparison to similar existing procedures.The program may be conveniently utilized for the efficient solution of practical engineering problems including free vibration and buckling analysis of structures. Results of such analyses are presented for representative structures.
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    International Journal for Numerical Methods in Engineering 7 (1973), S. 43-55 
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    Notes: A new family of triangular finite elements is described, useful for solving the axisymmetric vector Helmholtz equation, and a variety of scalar Helmholtz equation problems which lead to generalized Bessel equations of some order m. This family is similar in principle to the scalar axisymmetric Helmholtz elements derived earlier, but requires both reformulation of its describing equations and corresponding new universal element matrices, for successful computational implementation. The necessary formulation is given in this paper. Matrix elements to the sixth-order inclusive have been calculated and extensively tested computationally.
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    International Journal for Numerical Methods in Engineering 7 (1973), S. 69-83 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A convergence technique for use with the streamline curvature method of cascade and channel flow is presented which produces stable and rapid convergence for subsonic, transonic and supersonic flow and also in the downstream region where the Kutta-Joukowski condition is applied to a cascade flow. The convergence method is fully two-dimensional in nature, the iterative changes being determined via a model which takes into account the actual streamwise error distribution and the real normal changes in the grid.
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    International Journal for Numerical Methods in Engineering 7 (1973), S. 57-67 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The criteria for stability of the explicit finite difference solution of the one-dimensional, transient, conduction heat transfer problem with both radiant and convection heat transfer at the boundaries are considered in this paper. These criteria are governed by an inequality set from a functional relationship between the newly calculated and the old temperature at each node.From the node with the most stringent criteria, it is shown that setting the coefficient of the old temperature equal to zero in the governing difference equation is not sufficient for a general criterion. On the other hand, setting the derivative of the new temperature with respect to the old temperature equal to zero in the governing difference equation presents a simple, straightforward technique for obtaining a sufficient condition for a stable system. It is further shown that the second law of thermodynamics, written in explicit finite difference form, does present a necessary criterion for stability. However, the second law, because it is in the form of an inequality, does not present as simple a criterion as the derivative method does.The specific problem studied is a finite thickness slab, initially at a uniform temperature, but instantaneously subjected to both radiation and convection on its two surfaces. Temperature profiles were calculated on a digital computer and are presented in dimensionless graphical form over a range of five dimensionless parameters. A plot that relates stability to the maximum time-step size for the entire range of practical conditions of radiation numbers is also presented.
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    International Journal for Numerical Methods in Engineering 7 (1973), S. 243-254 
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    Notes: Five finite difference and two finite element schemes for solution of the one-dimensional consolidation problem are compared and evaluated from the viewpoints of convergence, accuracy, stability and computational efforts. An example problem involving laboratory experiments is also solved by using various schemes. Conclusions are drawn regarding relative suitability of these schemes for practical applications.
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    International Journal for Numerical Methods in Engineering 7 (1973), S. 255-271 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A finite element method is presented for the transient analysis of large-displacement, small-strain problems with material non-linearities. The method employs a convected co-ordinate technique and a direct nodal force computational scheme of considerable efficiency. Detailed formulations are given for a plane, constant strain triangular element and a Euler-Bernoulli beam element. Results are presented for several example problems and compared with experimental data and other numerical solutions.
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    International Journal for Numerical Methods in Engineering 7 (1973) 
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    International Journal for Numerical Methods in Engineering 7 (1973), S. 98-100 
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    International Journal for Numerical Methods in Engineering 7 (1973), S. 103-116 
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    Notes: The numerical solution of non-linear diffusion problems is considered from the computational view- point. The advantage of various aspects of the problem solution are considered toward enhancing the computational understanding of the system. First is the analytical solution to the reduced linear case which acts as an error check on the numerical solutions as well as providing a base for a perturbation theory approach. Next are two different numerical solutions which are utilized to generate solution redundancy. These are based upon the method of differential quadrature and the method of finite differences.The application to non-linear transient slab diffusion with a general reservoir boundary condition is shown as an example of the various methods.
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    International Journal for Numerical Methods in Engineering 7 (1973), S. 117-124 
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    Notes: A theorem expressing geometric conditions necessary and sufficient for the stiff stability of a linear multistep method is obtained. A corollary to this theorem provides sufficient conditions for stiff stability, for the class of algorithms characterized by a single essential root. By applying the Schur-Cohn criterion and employing a computerized algebraic manipulation program, the result provides a first step towards an exhaustive search technique for determining a continuum of members of this class.
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    International Journal for Numerical Methods in Engineering 7 (1973), S. 125-136 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The problem of optimizing the prestressing force and the tendon configuration for an indeterminate prestressed structure with prescribed cross-sectional dimensions is formulated in linear programming form, The structure is subjected to multiple load conditions and constraints are related to the structural behaviour and to the tendon configuration.It is shown that the number of behaviour constraints at each point in the structure can be reduced, as they represent parallel hyperplanes in the design space. Necessary conditions for feasible solutions are derived. The method based on transformation of the design variables, is suitable for beams, frames, grids and plates. Its application is illustrated for the case of a prestressed bridge.
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    International Journal for Numerical Methods in Engineering 7 (1973), S. 137-154 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: This paper shows how analytic surfaces can be used to define the vanes of an impeller of a centrifugal compressor. The analysis has been given of a cubic-linear patch for representing three-dimensional geometries. An example has shown how this type of patch can be successfully used to model the geometry of centrifugal or mixed flow impellers having 'swept back vanes at the outlet.The analysis has been programmed for the Atlas computer at the Computer Aided Design Centre (CADC), Cambridge and set up in such a way that the designer can examine systematically a range of impeller shapes.
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    International Journal for Numerical Methods in Engineering 7 (1973), S. 175-183 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A method is described for the solution of large sets of sparse equations arising in structural analysis. This method, called partial elimination, combines the concepts of elimination and iteration in such a way that good convergence rates can be obtained using a computer storage space not much greater than that required for other iterative methods.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973), S. 155-173 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The present investigation examines the multibar truss optimization problem in the context of a general class of unconstrained optimization procedures in conjunction with various types of penalty function transformations. Specifically, the problem is transformed into a series of unconstrained minimization problems using the penalty function techniques of Heaviside and SUMT. These are solved using the methods of Rosenbrock (orthogonal directions), Powell (conjugate directions) and Nelder-Mead (Simplex). This resulted in many cases in substantial improvements being recorded over previously reported data. The paper includes a comparative study of the synthesis based on these procedures.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
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