bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical measurements with glucose oxidase immobilized in polyacrylamide gel: Constant current voltametry
Authors: Wingard Lemuel B. , Liu C. C. , Nagda Niren L. 
Published: May 2005

AbstractConstant current voltametry was shown to be a suitable method for evaluation of electrodes containing immobilized oxidative enzymes as catalysts. The half‐cell potential for the oxdidation of D‐glucose at constant pH was measured at a series of constant dc currents, using glucose oxidase immobilized in a polyacrylamide gel‐platinum gauze matrix as catalyst. Over the range studied the potential versus current data were linear and could be extrapolated to give the open‐circuit half‐cell potential at zero current. The difference between the measured potential and the open‐circuit potential at a constant current was indicative of the loss in useful voltage due to concentration gradients within or adjacent to the enzyme electrode assembly. The relationship between the open‐circuit potential and the pH of the reaction mixture was linear with a slope of −0.056, in good agreement with the predicted slope of −0.061.
Continuous synchronous culture of Tetrahymena pyroformis
Authors: White Robert W. , Howell John A. 
Published: May 2005

AbstractTetrahymena was continuously cultivated in a series of stirred tank reactors with recycle. By holding part of the reactor train at a higher temperature than the remainder a synchronizing influence was introduced into the cells' environment. The system resulted in division occurring preferentially in a small contiguous group of the reactors, this effect being observed in both the number of cells found in each reactor and also their size distribution.
Effect of additives on mass transfer in turbine aeration
Authors: Benedek Andrew , Heideger William J. 
Published: May 2005

AbstractMass transfer coefficients and interfacial areas were determined for the aeration of aqueous solutions in a turbine agitated vessel. The mass transfer coefficients measured for water without additive and for sodium chloride solutions matched very well to measurements in the literature for air bubbles of the same diameter in free rise. Thus the only effect of agitation was to determine the bubble size which then in turn set the coefficient. Two surface active agents were studied: sodium dodecyl sulfate and Dow Corning Antifoam C. The rate of mass transfer increased with the former additive but decreased with the latter; however, the mass transfer coefficient was the exact same function of bubble diameter in both cases and the different rates are attributed to the quite different effects on interfacial area.
A continuous flow automatically recording respirometer
Authors: O'Brien W. J. , Agnew R. W. , Chun M. R. 
Published: May 2005

AbstractA respirometer suitable for continuous operation over extended periods of time is described. Oxygen is supplied to the culture by the electrolysis of water. The quantity of oxygen produced by electrolysis within any specified time interval is automatically printed on a tape. This record is combined with a continuous recording of the concentration of dissolved oxygen entering and leaving the reactor to produce a mass balance for oxygen in the system. Details on respirometer construction and operation are presented.
Deep‐tank culture of blue‐green algae in H2O and D2O
Authors: Taecker R. G. , Crespi H. L. , DaBoll H. F. , Katz J. J. 
Published: May 2005

AbstractA 160‐liter stainless steel algal growth tank has been constructed and has been used essentially continuously for over three years. Filamentous and unicellular blue‐green algae as well as a photosynthetic bacterium have been cultured using both ordinary and heavy water (99.8 atom % 2H). By using a recycling technique, yields as high as 25 g/liter of 2H2O have been obtained.
Response of continuous cultures to stimuli in glucose feed rate and dilution rate
Authors: Regan D. L. , Roper G. H. , Moss F. J. 
Published: May 2005

AbstractThe response of continuous cultures of yeast was investigated following step disturbances in glucose feed rate and dilution rate.The responses of the culture to the stimuli were oscillatory. The oscillatory responses were explained in terms of cell synchrony which was induced by the step change. An understanding of continuous cultures to stimuli was made possible with an appreciation of the inherently oscillatory events occurring in the single cell cycle between one mitosis and the next. Step changes in glucose feed rate and dilution rate induced a partial synchrony, which enabled the inherently oscillatory behavior of the individual cells to be made observable in the culture as a whole.
Continuous fermentation to produce xanthan biopolymer: Effect of dilution rate
Authors: Silman R. W. , Rogovin P. 
Published: May 2005

AbstractSingle‐stage continuous fermentations to produce xanthan gum have been run at dilution rates (D) from 0.023 to 0.196 hr−1. Xanthan production rate (XPR) was a function ofD. XPR increased from 0.34 g/hr/kg atD= 0.023 hr−1to the maximum 0.84 g/hr/kg atD= ca. 0.15 hr−1. AtD> 0.15 hr−1XPR decreased and at the highestDstudied (0.196 hr−1) was 0.69 g/hr/kg. Yield of xanthan from glucose consumed was 81–89%. Steady states ended between 6.5 and 8.7 turnovers when a variant strain occurred.
Kinetics of protein release from yeast sonicated in batch and flow systems at 20 kHz
Authors: James C. J. , Coakley W. T. , Hughes D. E. 
Published: May 2005

AbstractThe release constant, k, of brewers yeast sonicated at powers up to 200 W at 20 kHz has been shown to be independent of cell concentration up to values of 60 g made up to 100 ml. It is inversely proportional to the volume of the treatment vessel in the range 75 to 450 ml, and almost proportional to the input acoustic power from 60 to 195 acoustic watts. A flow system is described and a relationship linking protein release, flow rate, and the protein release constant, determined from batch experiments, is derived. Good agreement between the theoretical prediction of protein release and experimental results with the flow system was obtained.
Oil drop size distribution in hydrocarbon–water systems
Authors: Podlech Pablo A. Sanchez , Borzani Walter 
Published: May 2005

AbstractIn this work, a radiometric method is used for the determination of the oil drop size distribution in agitated hydrocarbon–water systems. The influence of the counter position, the oil concentration, and the rotation speed of impeller were studied. An experimental parameter is proposed for the definition of the drop size distribution. It was observed that an unsymmetrical distribution represents the drop size distribution better than the normal distribution law.
Degradation of ribonucleic acid in Candida lipolytica: Extraction of ribonucleic acid degrading enzymes
Authors: Imada Akira , Sinskey Anthony J. , Tannenbaum Steven R. 
Published: May 2005

AbstractWe developed an efficient and simple method for RNase extraction from Candida lipolytica cells which consists of predrying the cells with solvents and incubating them for 8 to 15 hr at 37 to 45°C in a slightly acid buffer which contains EDTA or salts. This method is called Solvent Dehydration Buffer Extraction (SDBE) procedure. Predrying with acetone or ethanol, or by lyophilization, followed by washing with acetone or ethylacetate gives the most efficient RNase extraction. The yield and specific activity obtained by this extraction procedure are higher than by any other method examined. An apparent 1.5‐ to 2.0‐fold activation of RNase occurred during the SDBE process. Activation of RNase in homogenates obtained by grinding fresh cells is also observed with EDTA or acetate buffer. The SDBE procedure works efficiently regardless of growth phase for Candida lipolytica, and works also with other Candida yeasts.
The relationship between hydrogen gas and butanol production by Clostridium saccharoperbutylacetonicum
Authors: Brosseau James D. , Yan Jwo‐Yee , Lo K. Victor 
Published: May 2005

AbstractTwo simultaneous fermentations were performed at 26°C with simultaneous inocula using Clostridium saccharoperbutylacetonicum. Fermentation 1 prevented the gas formed by the biomass from escaping the fermentor while 2 allowed the gas formed to escape. Fermentor 1 provided for the production of butanol, acetone, and ethanol, while when the H2 formed was allowed to escape with fermentor 2, neither butanol nor acetone were produced. Ethanol was also formed in both fermentors and began along with the initial growth of biomass and continued until the fermentations were complete. Butanol and acetone production began after biomass growth had reached a maximum and began to subside. The butanol‐acetone‐ethanol millimolar yields and ratios were 38:1:14 respectively. The fermentor 2 results show that a yield of 2.1 L H2, 93 or 370 mmol H2/mol glucose, was formed only during the growing stage of growth; neither butanol nor acetone were produced; ethanol was formed throughout the fermentation, reaching a yield of 15.2 mmolar. It appears that hydrogen gas is required for butanol production during the resting stage of growth.
A multispecies biofilm model
Authors: Wanner O. , Gujer W. 
Published: May 2005

AbstractUsing a continuum approach and observing conservation principles, an analytical mathematical model of microbial interaction in biofilms was developed. The model predicts changes in biofilm thickness and describes the dynamics and spatial distribution of microbial species and substrates in the film. It allows for biomass detachment due to shear stress and sloughing, external mass transfer limitations, as well as variations in substrate concentrations in the bulk liquid. A computer implementation of the model is provided using an example of heterotrophicautotrophic competition to illustrate how the observed phenomena can be numerically reproduced and indicating how they might affect overall biofilm performance.
A measuring system for biotechnical processes based on discrete methods of estimation
Authors: Staniškis J. , Simutis R. 
Published: May 2005

AbstractAn adaptive measuring system of the main variables of biotechnical processes based on the theory of estimation is elaborated upon here. All stages of system synthesis are considered. It is shown that for an adaptive measuring system all a priori information on modelling and measurement noise and process mathematical models must be used. The data of direct and indirect measurements are used for estimating the main variables. The performance of the proposed measuring system was checked using imitative modelling.
The kinetics of protein precipitation by different reagents
Authors: Chan M. Y. Y. , Hoare M. , Dunnill P. 
Published: May 2005

AbstractThe kinetics of precipitation of soya protein has been examined in a tubular flow reactor with the precipitants, ammonium sulfate, ethanol, divalent calcium, and sulfuric acid. The precipitate growth profiles obtained in all cases showed the rapid formation of a precipitate phase and the attainment of a final size within 16 s. The final mean particle diameter dm varied with precipitating agent used in the order: sulfuric acid (12.5 μm) > ethanol (7.5 μm) ≈ calcium ion (7.2 μm) > ammonium sulfate (3.1 μm). In the case of ethanol precipitation, changes in the design of the contacting section of the reactor led to differences in the precipitate growth curve. Protein solubility curves are also presented, and with the reactor data, they provide a convenient method for assessing the effect of precipitating agent on the design of protein precipitation reactors.
A computer model for the growth and differentiation of a fungal colony on solid substrate
Authors: Georgiou G. , Shuler M. L. 
Published: May 2005

AbstractMold growth and differentiation are closely related to the formation of secondary products. In solid‐substrate fermentations this interrelationship is often more completely realized than in submerged cultures. Solid substrate reactions are used commercially in a limited manner in the western world, but are relatively common in Asia. Basic studies in solid‐substrate fermentation should yield results applicable to all types of commercial mold fermentations for the production of a secondary product. This paper presents a relatively simple model for the growth of a mold colony on a solid surface with a defined medium utilizing glucose. Unlike submerged cultures the model must account for both cellular differentiation and the spatial heterogeneity in the system. Model parameters were estimated independently using literature values. The results of the simulation studies suggest that mass transfer limitations are at least partially responsible for the proliferation of differentiated structures on solid substrates as compared to liquid cultures. Since the concentration profile depends on the depth of the substratum, conditions that enhance conidia production can be achieved by controlling the depth of the solid medium.
Pressure drop in a packed bed with a liquid of variable viscosity: The case of dextrin hydrolysis by immobilized glucoamylase
Authors: Kim Kyung Hoe , Chang Ho Nam 
Published: May 2005

AbstractThe activity of an immobilized enzyme in a packed bed is monitored for the change in a substrate conversion with time. But pressure drop in the packed bed with immobilized glucoamylase can serve as an indirect indicator for the changes in the conversion and activity of the immobilized enzyme. The method is simple and the change can be monitored continuously. This method can be generally applicable to systems where the viscosity of a substrate changes with its conversion.
A novel method of determination of the internal enzyme distribution within porous solid supports and the deactivation rate constant
Authors: Do D. D. , Hossain M. M. 
Published: May 2005

AbstractThis article presents a method for determining the rate constant for deactivation and the internal distribution of immobilized enzyme. This method makes use of the parallel deactivation process in a diffusion‐controlled regime, in which the internal activity profile behaves like a penetration front. This front basically traces through the initial active enzymatic profile, and one can determine the internal profile and the rate constant for deactivation from the experimentally observable bulk concentration versus time. This method is applied to the experimental data of the system of hydrogen‐peroxide‐immobilized catalase on controlled pore glass and Si–Al particles.
Kinetics of anaerobic purification of industrial wastewater
Authors: Bolle W. L. , van Breugel J. , van Eybergen G. C. , Kossen N. W. F. , van Gils W. 
Published: May 2005

AbstractAs a part of the development of an integral mathematical model describing the up‐flow anaerobic sludge blanket (UASB) reactor, the kinetics of the conversion of organic wastes has to be known. We compared the Monod model with the model proposed by Andrews et al. Together with the assumption that the substrate for the anaerobic bacteria is formed by nonionized, volatile fatty acids, the Andrews model is able to describe substrate inhibition and reactor failure due to pH changes.From four batch experiments, with different concentrations of microorganisms, it could be concluded with a reliability of over 95% that the monod model was inadequate and Andrews' model was adequate to describe the measurements. Standard statistical techniques like the X2‐ and the F‐test were used for this purpose.From a parameter sensitivity analysis for the Andrews model it followed that the maximum specific growth rate μ of the bacteria and the inhibition constant K1 are the parameters which influence the system most. Thus, these parameter were determined experimentally and most accurately. The results are:

The other parameters were taken from literature. From calculation of the Thiele modulus for the particles it follows that transport limitation of the substrate in the flocus is not significant. The efficiency η is 0.85 in the worst case.
Effects of periodic change in pressure and dissolved‐oxygen concentration on the incubation characteristics of Pseudomonas aeruginosa
Authors: Kataoka Hiroshi , Sato Seigo , Mukataka Sukekuni , Namiki Atsushi , Yoshimura Keiichiro , Takahashi Joji 
Published: May 2005

AbstractExperiments were carried out to identify an efficient procedure for decreasing the amount of excess sludge in deep aeration columns. Incubation characteristics, especially cellular yield, are closely related to excess sludge, maximum specific growth rate, and chemical oxygen demand. They were measured here for the bacterium Pseudomonas aeruginosa, which tends to be predominant in sewage treatment, at a pressure remaining constant or periodically changing in the range of 1–6 atm (abs.). Cellular yields tended to decrease over 1–2 min pressure cycles; in steady operation they decreased considerably with increasing pressure or dissolved oxygen concentration. Maximum specific growth rates were moderately affected by periodic changes in pressure or dissolved oxygen concentration but markedly affected in the higher concentration range under steady operation. Substrate consumption rates on the other hand, were little affected in either case. The values of chemical oxygen demand ranged from 220 to 250 mg/L, and were thus nearly constant.
Production of acetic acid by Clostridium thermoaceticum in batch and continuous fermentations
Authors: Sugaya K. , Tusé D. , Jones J. L 
Published: May 2005

AbstractBatch and continuous fermentations with Clostridium thermoaceticum (ATCC 39073) using automatic pH control were conducted. The value of μmax obtained from batch fermentation was about 0.14 h−1; acetate yield, which was both growth and non‐growth associated, was about 2 mole of acetic acid/mole of glucose, compared with a theoretical maximum value of 3. This low yield, compared with literature data, may be explained by glucose loss through a combination of degradation routes. Continuous fermentation could be sustained for 1600 h or more without contamination problems. Continuous fermentation at high dilution rates indicates that μmax may be well above 0.17 h−1 when fresh feed medium is used. Acetate yields in continuous fermentation were about 77% of theoretical or 2.3 mole of acetic acid/mole of glucose.
Induction and elimination of oscillations in continuous cultures of Saccharomyces cerevisiae
Authors: Parulekar Satish J. , Semones Gary B. , Rolf Michael J. , Lievense Jefferson C. , Lim Henry C. 
Published: May 2005

AbstractContinuous cultures of Saccharomyces cerevisiae are known to exhibit oscillatory behavior in the oxidative region. Important findings of a series of experiments conducted to identify the causes for initiation of and the means for elimination of oscillations in these cultures are reported in this paper. These oscillations are seen to be connected to the growth kinetics of the microorganism and are induced at very low glucose concentrations and at dissolved oxygen (DO) levels that are neither high nor low (DO values between 20 and 78% air saturation at a dilution rate of 0.2 h−1 and pH of 5.5 at 30°C). The oscillatory behavior is encountered over a range of dilution rates (0.09–0.25 h−1 at 30°C for pH = 5.5 and DO = 50% air saturation). The oscillations can be eliminated by raising the DO level above a critical value or by lowering the DO level below a critical value.
Kinetic considerations about the study of alcoholic fermentations of starch hydrolysate
Authors: Converti Attilio , Perego Patrizia , Borghi Marco Del , Parisi Federico , Ferraiolo Giuseppe 
Published: May 2005

AbstractAlcoholic fermentations of starch hydrolysate by two different yeast strains, Saccharomyces cerevisiae(var. Vinal) and Saccharomyces oviformis(IMAP 383), have been studied in batch runs. In order to evaluate the different inhibition phenomena due to both substrate and product, a new kinetic equation is suggested.
Electroenzymatic reactors with coenzyme regeneration: A theoretical approach
Authors: Bergel Alain , Comtat Maurice 
Published: May 2005

AbstractA comparison of the relative performance of production techniques using coenzyme or cofactor electrochemical regeneration demonstrates the superiority of those processes in which the enzymatic reaction and the regeneration are conducted in the same reactor as opposed to those in which the reaction and regeneration are separated. For the former type of reactor, a method of calculation is proposed. This method is based on the solution of equations which describe the phenomena in modules representing three areas: the surface of the electrode, a layer where occur simultaneously the transport of material and the enzymatic reaction, and the bulk of the solution. This method is suggested for three types of reactor: those in which an enzyme solution is held close to an electrode by a semipermeable membrane, those in which an enzyme‐charged membrane is in contact with an electrode, and those in which the enzyme is in solution in the vessel into which the electrode is dipped.
Optimization of CSTRs in series by dynamic programming
Authors: Ong S. L. 
Published: May 2005

AbstractThis article concerns the development of a simple yet effective procedure for optimizing the design of a reactor system employing CSTRs in series. The basic approach used in this work was to translate the problem of reactor design to a mathematical programming model. The resulting model was then solved by dynamic programming. The procedure was tested on an IBM 3033 computer and an IBM PC‐compatible machine, the CORONA PC‐II microcomputer. The results of this study indicate that the optimization procedure developed is very effective.
Utilization of spline functions for smoothing fermentation data and for estimation of specific rates
Authors: Oner M. D. , Erickson L. E. , Yang S. S. 
Published: May 2005

AbstractA response surface method of smoothing fermentation data with spline functions is presented. The available electron balance is used to optimally select the values of the smoothing parameters associated with the spline functions. The method is applied to six sets of anaerobic fermentation data in which pure and mixed cultures are grown in batch followed by fed batch culture.Lactobacillus bulgaricusandStreptococcus thermophilusare cultured on 3% dry milk. Measured concentrations of biomass, lactose, galactose, lactic acid, and other acid products are smoothed using spline functions. Values of specific growth rate, specific lactose consumption rate, specific galactose formation rate, and specific acid product formation rate are estimated and the consistency of the results is examined using the available electron balance. The results show that the method works reasonably well, but that an upper bound should be used for the smoothing parameters to obtain accurate estimates of the derivative quantities.
Estimation of the true growth yield and maintenance coefficient for yoghurt cultures
Authors: Oner M. D. , Erickson L. E. , Yang S. S. 
Published: May 2005

AbstractPoint and 95% confidence interval estimates of the true growth yield and maintenance coefficient are reported for four pure cultures andtwo mixed cultures of Lactobacillus bulgaricus and Streptococcus thermophilus grown anaerobically on 3% nonfat dry milk using batch followed by fed batch culture. An improved method of data analysis, which includes separate analysis of the exponential growth region and a new method of selecting smoothing spline functions, is utilized. The parameter estimation results are compared with the theoretical maximum yields for one and two moles of ATP produced per mole of glucose and to the growth yield estimated from the exponential growth region analysis.