bluuebunny/crossref_metadata_2025_split huggingface dataset:
Homogeneous immunoassay of polyclonal antibodies by use of antigen‐coupled liposomes
Authors: Katoh Shigeo , Sohma Yoshinori , Mori Yoshikazu , Fujita Ryoji , Sada Eizo , Kishimura Masaaki , Fukuda Hideki 
Published: December 2004

AbstractAnti‐cytochrome c and anti‐myoglobin antibodies were assayed by use of immunoliposomes coupled with the antigens. Addition of complement under the existence of the antigens. Addition of complement under the existence of the antigen‐antibody complex on the surface of the liposome caused lysis of the liposomes, which was proportional to the amount of the antigen‐antibody complex formed as well as the concentration of complement added. Thus, the degree of marker release depended on the average association constant and also on its heterogeneity of the polyclonal antibodies, which shows that the results assayed by this method are correlated to the antibody ability to form the antigen‐antibody complex © 1993 Wiley & Sons, Inc.
Affinity precipitation of proteins by polyligands
Authors: Morris John E. , Hoffman Allan S. , Fisher Rod R. 
Published: December 2004

AbstractA novel technique for affinity precipitation has been developed in which multimeric target proteins are precipitated as a result of network formation by polymer‐conjugated ligands (polyligands). A polyligand precipitant for avidin was synthesized by conjugation of biotin to a polyacrylamide‐based backbone. The effects of mixing conditions, ligand substitution frequency, and molecular weight on affinity precipitation were examined using the biotin‐PAAm precipitant. Biotin was replaced by iminobiotin to study the effect of the ligand‐protein dissociation constant o affinity precipitation. The iminobiotin‐PAAm precipitant was also used to examine the reversibility of the precipitation and recovery of the target protein after precipitation. © 1993 Wiley & Sons, Inc.
Dimensionless criteria for estimating oxygen transfer in aeration systems
Authors: Ognean T. 
Published: December 2004

AbstractThe effect of power consumption on oxygen transfer efficiency has been evaluated for both surface and subsurface aeration systems. Two new dimensionless criteria (numbers) have been proposed for this purpose. They are termed the efficiency criterion or To number and the power consumption effect criterion or Av number. The analysis presented in this article is based on data obtained on various full‐scale aeration systems, and it shows that for each aerator there is an optimum power consumption at which maximum oxygen transfer efficiency results. The oxygen transfer efficiency has maximum values when the efficiency criterion (To number) reaches an approximately constant value. The results have proven that when there are several aerators with identical diameters and the same rotational velocity but different geometrical shapes, the most efficient one will be (after having reached the maximum transfer efficiency) the one with the highest power consumption. For two aerators varying in diameter but with the same parameter as above (maximum transfer, equal rotational velocity), different efficiencies are obtained, the difference being a function of d−0.5. The results of investigating subsurface aeration systems show that the efficiency of decreased. © 1993 Wiley & Sons, Inc.
Tropane alkaloid production in Datura stramonium suspension cultures: Elicitor and precursor effects
Authors: Ballica Rabia , Ryu Dewey D. Y. , Kado Clarence I. 
Published: December 2004

AbstractThe effects of elicitation, carbon, and nitrogen sources, and precursors on cell growth and tropane alkaloid production in Datura stramonium cell cultures were studied. D. Stramonium cell cultures responded very well to elicitors in the late exponential phase. Addition of cell wall fragments of Phytophotora megasperma (Pmg) enhanced the final tropane alkaloid yield by fivefold compared with control culture. Supply of carbon culture. Supply of carbon and nitrogen sources, at a ratio (C/N) of up to 70, to cell cultures in the early stationary phase, suppressed tropane alkaloid production; whereas C/N rations beyond about 100 increased the final product yield by more than 100% compared to that of the control experiment. Total alkaloid production in the cell culture supplemented with phenylalanine and ornithine was five times higher that that in the control culture. Higher rations of tropine to tropic acid also stimulated alkaloid production. At a ratio of 20, the productivity was seven times higher that that in the control culture. Adding precursors at high concentrations (e.g., 3 to 10 mM) to the cell culture reduced the final cell yield by less than 40%, while elicitation did not affect the cell yield. On the other hand, cell yield in the cultures supplemented with carbon and nitrogen sources was influenced by the C/N ratio. The highest cell yield was obtained at C/N = 70. © 1993 Wiley & Sons, Inc.
Transport and intracellular accumulation of acetaldehyde in saccharomyces cerevisiae
Authors: Stanley G. A. , Pamment N. B. 
Published: December 2004

AbstractThe rate of acetaldehyde efflux from yeast cells and its intracellular concentration were studied in the light of recent suggestions that acetaldehyde inhibition may be an important factor in yeast ethanol fermentations. When the medium surrounding cells containing ethanol and acetaldehyde was suddenly diluted, the rate of efflux of acetaldehyde was slow relative to the rate of ethanol efflux, suggesting that acetaldehyde, unlike ethanol, may accumulate intracellularly. Intracellular acetaldehyde concentrations were measured during high cell density fermentations, using direct injection gas chromatography to avoid the need to concentrate or disrupt the cells. Intracellular acetaldehyde concentrations substantially exceeded the extracellular concentrations throughout fermentation and were generally much higher than the acetaldehyde concentrations normally recorded in the culture broth in ethanol fermentations. The technique used was sensitive to the time taken to cool and freeze the samples. Measured intracellular acetaldehyde concentrations fell rapidly as the time taken to freeze the suspensions was extended beyond 2 s. The results add weight to recent claims that acetaldehyde toxicity is responsible for some of the effects previously ascribed to ethanol in alcohol fermentations, especially Zymomonas fermentations. Further work is required to confirm the importance of acetaldehyde toxicity under other culture conditions. © 1993 John Wiley & Sons, Inc.
Oxygen transfer in a pulse bioreactor
Authors: Monahan Patrick B. , Holtzapple Mark T. 
Published: December 2004

AbstractOxygen transfer in a novel pulse bioreactor has been evaluated. The agitator consists of a series of alternately fixed and movable parallel plates mounted so that the movable plates vibrate at 30 Hz causing a pulsating fluid motion. Pure oxygen, at pressures up to 5 atm, diffuses through silicone rubber tubing that also vibrates at 30 or 60 Hz. The main feature of this bioreactor is high oxygen transfer with low shear to prevent damage to fragile animal cell membranes. We estimate that sufficient oxygen can be supplied to support over 108 cells/mL of human diploid foreskin cells growing on microcarriers. © 1993 John Wiley & Sons, Inc.
Carbon and energy balances in cell‐recycle cultures ofSchizosaccharomyces pombe
Authors: Uribelarrea J. L. , De Queiroz H. , Goma G. , Pareilleux A. 
Published: December 2004

AbstractA strain of the fission yeastSchizosaccharomyces pombewas aerobically grown in a cell‐recycle fermentor under various operating conditions, i.e., different bleeding rates and various separate feed rates of glucose and basal medium. Carbon and energy balances were analyzed during steady‐state culture regimes, allowing growth yields and maintenance coefficients to be determined under glucose‐limited and glucose‐excess environments. Special attention was given to the metabolic shift from purely oxidative to respirofermentative glucose catabolism resulting from a change in the growth‐limiting factor. No maintenance requirements for the carbon source and for energy were observed during glucose‐limited culture regimes and oxidative catabolism. Under glucose excess and respirofermentative metabolism, themGcoefficient was shown to be growth‐linked, whereas the enhancement of the apparentmecoefficient observed for increased residual glucose concentrations could be assigned to a decline in the ATP yield. © 1993 John Wiley & Sons, Inc.
On the applicability of adaptive bioprocess state estimators
Authors: Lant Paul A. , Tham Ming T. , Montague Gray A. 
Published: December 2004

AbstractThis article presents an industrial case study, examining the application of a novel adaptive biomass estimator to an industrial microfungi production process. It is our intention that this contribution should focus upon the implementation issues of the algorithm, in preference to a rigorous theoretical development. The novel algorithm adopted is developed from Adaptive Inferential Estimation studies of Guilandoust and co‐workers. The technique utilizes input–output process measurements obtained at different frequencies, thereby providing more frequent estimates of biomass concentration than are otherwise available from off‐line laboratory analyses. The algorithm is particularly suited to the biotechnology industry, as it is capable of utilizing irregular assay measurements with varying delays.Although this article demonstrates the encouraging industrial implications of the adaptive algorithm, like all adaptive techniques currently developed, it is restricted by the inability to perform robust on‐line system identification. The ultimate selection of a “suboptimal” “fixed parameter” algorithm for on‐line implementation, is therefore directly attributable to these inadequacies. Aspects of data acquisition, data pretreatment, and data quality are critical for real process applications, and while some practical approaches are adopted here, many important implementation problems remain unresolved. © 1993 John Wiley & Sons, Inc.
The influence of polyalcohols and carbohydrates on the thermostability of α‐amylase
Authors: de Cordt S. , Hendrickx M. , Maesmans G. , Tobback P. 
Published: December 2004

AbstractThe influence of polyhydric alcohols and carbohydrates on the thermostability, i.e., the heat inactivation kinetics, of Bacillus licheniformis α‐amylase was studied in the temperature range 96° to 130°C. High concentrations (from 9 to 60 weight percent) of glycerol, sorbitol, mannitol, sucrose, or starch can markedly decrease the inactivation rate constant, k, and in the studied cases, this stabilizing effect grows stronger with increasing additive concentration. Statements about stabilization should, however, be specified carefully with respect to temperature, because EA is mostly altered likewise. For dissolved enzyme EA was almost always decreased in the presence of polyol or carbohydrate, whereas for immobilized enzyme it was augmented in each studied instance. The inactivation of dissolved enzyme can, in all the studied cases, be adequately described as a firstorder process. Immobilized enzyme, however, shows biphasic then first‐order inactivation kinetics, depending on the additive concentration and temperature. © 1994 John Wiley & Sons, Inc.
Toward a self‐similar theory of microbial populations
Authors: Ramkrishna Doraiswami 
Published: December 2004

AbstractA fresh quest is made of segregated cell models of microbial populations with a view to determine whether the multivarite distribution of physiological states, during transient growth, can attain self‐similar forms (i.e., become time invariant) when each physiological state variable is scaled with respect to its population average. Such self‐similar growth situations are believed to be more general than those of balanced growth. The conditions under which self‐similarity is possible are investigated. Thus conditions are stipulated on the synthesis rates of different physiological entities, cell division rate, and the partitioning of the parent cell's components among the daughter cells (assuming binary division) in order for self‐similar growth to be attained. Subject to the attainment of self‐similar growth, it is shown that cytometric data can be analyzed systematically to determine how the rates of syntheses of various biochemical entities and cell division rates vary with the physiological entities that are measured. Inverse problems, represented by algebraic systems, are identified which will potentially allow flow cytometric data to be inverted to yield quantitative information on the absolute rates of cellular growth and reproductory processes as a function of the cell states chosen for measurement. It is suggested that the methods become more effective when cytometry can be used to make direct observations on dividing cells so that the number of unknowns in the inverse problem can be reduced, thus facilitating its more complete solution. Preliminary analysis of cytometric data obtained in the literature show promise of self‐similarity and thus the possibility of application of the methods discussed here. © 1994 John Wiley & Sons, Inc.
Kinetic modeling of interesterification reactions catalyzed by immobilized lipase
Authors: Reyes Héctor R. , Hill Charles G. 
Published: December 2004

AbstractKinetic data for lipase‐catalyzed interesterification reactions between free fatty acids and triglycerides were collected and the dynamics of the interesterification reactions were successfully modeled using tow rate experssions requiring a total of five adjustable parameters. One rate expression describes the disappearance of the free fatty acid (octanoic or linolenic acid), and the second describes the rate of release of fatty acid residues from the triglycerides (olive oil or milkfat). This model is able to account for the effects of the concentration of all chemical species participating in interesterification throughout the entire reaction. When the data for both milkfat and olive oil were subjected to nonlinear regression analyses using the same mathematical model, the parameter estimates for both systems were comparable. In addition to reproducing the tendencies observed experimentally, simulations of the interesterification system under a variety of initial conditions provided insight into the effects of several reaction variables which could not be examined experimentally. Among the most significant findings of the simulation work are (1) there is a limit beyond which increasing the initial concentration of water produces no further increase in the initial rate of the interesterification reaction; (2) an increase in the initial concentration of lower glycerides produces a concomitant increase in the rate of the interesterification reaction; (3) the free fatty acids inhibit the rate of hydrolysis of the fatty acid residues of the triglycerides; (4) there is a limit beyond which increasing the initial concentration of triglycerides produces no significant increase in the rate of either the hydrolysis reaction or the interesterification reaction. © 1994 John Wiley & Sons, Inc.
EPR characterizations of α‐chymotrypsin active site dynamics in reversed micelles at enhanced gas pressures and after subjection to clathrate formation conditions
Authors: Kommareddi Nagesh S. , O'Connor Kim C. , John Vijay T. 
Published: December 2004

AbstractElectron paramagnetic resonance spectroscopy is used to characterize the active site dynamics of α‐chymotrypsin solubilized in reversed micelles. Of particular interest is the behavior of the enzyme when the micellar system is subjected to enhanced gas pressures and low temperatures. At specific thermodynamic conditions, clathrate hydrates from from the intramicellar water, reducing the micelle size and water content. Also, beyond a critical pressure, micellar instbility results. The EPR spectra under these conditions indicate that the rotational correlation times increase appreciably only when the water‐to‐surfactant molar ratio, W0, is reduced to values lower than 10. The EPR characterization also reveals a remarkable resilience of the enzyme when subjected to pressure‐induced changes; when returned to ambient conditions, activity and active site dynamics are fully restored. © 1994 John Wiley & Sons, Inc.
Sorption and precipitation of metals in activated sludge
Authors: Kodukula Prasad S. , Patterson James W. , Surampalli Rao Y. 
Published: December 2004

AbstractA conceptual model describing the relative roles of sorption and precipitation processes for metals in solid‐solution suspensions is presented. The model performance is demonstrated using experimental data on sorption and precipitation of metals in samples of activated sludge mixed liquor. Based on the experimental results presented here, it appears that, at total metal and mixed liquor suspended solids concentrations and pH values generally encountered in full‐scale municipal (or combined municipal/industrial) activated sludge systems, metals are primarily removed by sorption processes.
Lipase catalyzed esterification of glycidol in nonaqueous solvents: Solvent effects on enzymatic activity
Authors: Martins João F. , de Sampaio Teresa Correaêa , de Carvalho Inê Borges , Barreiros Susana 
Published: December 2004

AbstractWe studied the effect of organic solvents on the kinetics of porcine pancreatic lipase (pp) for the resolution of racemic glycidol through esterification with butyric acid. We quantified ppl hydration by measuring water sorption isotherms for the enzyme in the solvents/mixtures tested. The determination of initial rates as a function of enzyme hydration revealed that the enzyme exhibits maximum apparent activity in the solvents/mixtures at the same water content (9% to 11% w/w) within the associated experimental error. The maximum initial rates are different in all the media and correlate well with the logarithm of the molar solubility of water in the media, higher initial rates being observed in the solvents/mixtures with lower water solubilities. The data for the mixtures indicate that ppl apparent activity responds to bulk property of the solvent. Measurements of enzyme particle sizes in five of the solvents, as function of enzyme hydration, revealed that mean particle sizes increased with enzyme hydration in all the solvents, differences between solvents being more pronounced at enzyme hydration levels close to 10%. At this hydration level, solvents having a higher water content lead to lower reaction rates; these are the solvents where the mean enzyme particle sizes are greater. Calculation of the observable modulus indicates there are no internal diffusion limitations. The observed correlation between changes in initial rates and changes in external surface area of the enzyme particles suggests that interfacial activation of ppl is only effective at the external surface of the particles. Data obtained for the mixtures indicate that ppl enantioselectivity depends on specific solvent‐enzyme interactions. We make reference to ppl hydration and activity in supercritical carbon dioxide. © 1994 John Wiley & Sons, Inc.
Artificial neural network based experimental design procedure for enhancing fermentation development
Authors: Glassey J. , Montague G. A. , Ward A. C. , Kara B. V. 
Published: December 2004

AbstractConventional experimental design techniques are available to assist in the optimization of fermentation processes, but due to the nonlinearities in the bioprocess, they are limited in their effectiveness. This problem is further complicated with recombinant systems as a result of the additional complexities of the process. This article describes a general strategy using artificial neural networks as an alternative approach to fermentation process development laboratory are presented for the neural network based procedures. © 1994 John Wiley & Sons, Inc.
DSC and protein–based time‐temperature integrators: Case study of α‐amylase stabilized by polyols and/or sugar
Authors: De Cordt S. , Avila I. , Hendrickx M. , Tobback P. 
Published: December 2004

AbstractDifferential scanning calorimetry (DSC) was used as a tool for rapid assay of the thermostability of two Bacillus sp. α‐amylases and horseradish peroxidase as a function of the concentration of glycerol, sorbitol, and sucrose. In this screening study, the DSC peak temperature proved to be a good measure of protein thermostability. By means of isothermal heating experiments, the kinetics of heat decay of B. amyloliquefaciens α‐amylase were studied by following the course of the DSC peak area (heat exchange (ΔH/wt)) as a function of time. The high stability of this enzyme in the presence of polyolic alcohols or carbohydrates allowed working at temperatures as high as 127°C. The results of this study can have particular relevance with regard to research on and development of protein‐based time‐temperature integrators (TTls) for evaluating heat pasteurization or sterilization treatments of foods or pharmaceutical products. The use of the DSC peak area (ΔH.wt) as TTI‐response was validated in experiments with a time‐variable temperature profile. Finally, it was shown how the results of such non‐isothermal experiments can even be used for (re‐) estimation of the protein decay kinetic parameters (k, EA). © 1994 John Wiley & Sons, Inc.
Modification of central metabolic pathway in escherichia coli to reduce acetate accumulation by heterologous expression of the bacillus subtilis acetolactate synthase gene
Authors: Aristidou Aristos A. , San Ka‐Yiu , Bennett George N. 
Published: December 2004

AbstractA novel metabolic engineering technique involving the redirection ofcellular carbon fluxes was employed to reduce acetate production in an Escherichia coli culture. Metabolic engineering was achieved by cloning E. coli the gene for the Bacillus subtilis acetolactate synthase (ALS), an enzyme capable of catalyzing the conversion of pyruvate to nonacidic and less harmful species. The heterologous expression of the ALS catabolic enzyme in Escherichia coli drastically modified the cellular glycolytic fluxes. In particular, acetate excretion, which is a common characteristic of E. coli, as well as a physiological burden, was minimized. The residual acetate level was kept under control and maintained at a level that was below the toxic threshold. The expression of the biologically active ALS enzyme in E. coli did not result in any detectable changes on either cell growth rate or cell yields. The alternative product, acetoin, was shown to be 50 times less harmful than acetate. Similarities in the growth pattern of two different E. coli strains, RR1 and GJT001, under all cultivation conditions suggested that the ability of ALS to reduce acetate accumulation is generic and not strain‐specific. © 1994 John Wiley & Sons, Inc.