bluuebunny/crossref_metadata_2025_split huggingface dataset:
Breakthrough behavior of 17.5 mol% water in methanol, ethanol, isopropanol, and t‐butanol vapors passed over corn grits
Authors: Bienkowski P. R. , Barthé A. , Voloch M. , Neuman R. N. , Ladisch M. R. 
Published: May 2005

AbstractGround corn is now used in industry as an adsorbent to remove water from ethanol vapors. It is stable and inexpensive at 10 cents/lb (22 cents/kg). For regeneration it requires less than 2000 Btu/gal of 190 proof ethanol processed. If necessary, it could be readily saccharified and fermented into ethanol after use. This renewable resource has further exciting potential as an inexpensive adsorbent for water removal from other alcohols, including methanol, isopropanol, and t‐butanol. Water sorption capacity in a fixed bed, nonisothermal adsorption column appears to be a function of the heat capacity of the non‐adsorbed alcohol vapor, relative to the heat capacity of the corn adsorbent. Methanol, ethanol, isopropanol, and t‐butanol containing 17.5 mol% water gave 105,151, 284, and 358 g anhydrous product/kg adsorbent, respectively, per adsorption cycle. This adsorbent, having operational temperature ranges between 80 and 100°C, is indicated to be of potential utility in solvent recycle processes using these industrially important alcohols. Observed adsorption characteristics are discussed in terms of the alcohol properties of molecular size, heat capacity, and diffusivity. The adsorption mechanism is hypothesized to include transport of water molecules into the structure of adjacent starch molecules present in small spherical bodies (diameter of several microns) immobilized on the surface of the corn grit particles.
Vapor liquid equilibrium behavior of aqueous ethanol solution during vacuum coupled simultaneous saccharification and fermentation
Authors: Roychoudhury P. K. , Ghose T. K. , Ghosh P. , Chotani G. K. 
Published: May 2005

AbstractThe data on ethanol‐water vapor‐liquid equilibrium in the presence of cellulase enzyme, nutrients, yeast, and rice straw indicated a substantial increase in ethanol concentration in vapor phase at reduced pressures. Maximum relative volatility of ethanol in the presence of added components is approximately twice that of a pure ethanol‐water system. The equation correlating the activity coefficient and ethanol concentration in the liquid phase adequately represents the equilibrium behavior.
Photosynthesis in modulated light: Quantitative dependence of photosynthetic enhancement on flashing rate
Authors: Terry Kenneth L. 
Published: May 2005

AbstractIn order to predict the potential benefit associated with mixing devices designed to introduce periodic light modulations in dense cultures of microalgae, it is necessary to develop a quantitative understanding of the relationship between the frequency of the modulations and the resulting photosynthetic efficiency enhancement. To explore this relationship, the photosynthetic rate of cells of Phaeodactylum tricornutum from a dense steady state culture was determined as a function of modulation frequency, intensity of light received, and the proportion of the total cycle period during which the cells were illuminated. At high flash frequencies, the photosynthetic rate was determined by the average intensity received by the cells (full light intensity integration), while at low frequencies the cells responded to the instantaneous intensity (no light intensity integration). Full integration was approached asymptotically with increasing flash frequency. The frequency response could be described by a rectangular hyperbola, and the parameters of this hyperbola were nearly independent of the illumination intensity and the flash proportion. The saturation constant of the hyperbola, at which the response is one‐half of the maximum, was 0.67 Hz.
Use of hexadecyl fractosil as a hydrophobic carrier for adsorptive immobilization of proteins
Authors: Nemat‐Gorgani Mohsen , Karimian Khashayar 
Published: May 2005

AbstractFractosil, a porous form of silica, has been used for the preparation of a hydrophobically derivatized carrier for protein immobilization. Interaction of a number of arbitrarily chosen proteins with hexadecyl‐substituted Fractosil has been investigated. Binding of proteins was found to take place with retention of their native properties. Glutamate dehydrogenase, used as a model allosteric protein, was found to retain its catalytic and allosteric properties upon binding to the adsorbent in the form of suspension or column. Positive cooperative interactions for binding of bovine serum albumin and glutamate dehydrogenase to the matrix were observed. These findings are discussed in terms of hydrophobic interactions occurring between various residues of the protein molecules and the hydrophobic ligands in addition to those interactions which may occur with the unsubstituted gel. Results presented on immobilized glutamate dehydrogenase, trypsin, α‐chymotrypsin, α‐amylase, and amyloglucosidase clearly indicate possible potential of the support for continuous catalytic transformations.
Investigation of bacterial growth on mixed substrates: Experimental evaluation of cybernetic models
Authors: Kompala Dhinakar S. , Ramkrishna Doraiswami , Jansen Norman B. , Tsao George T. 
Published: May 2005

AbstractCybernetic models, developed earlier by the authors, have been evaluated experimentally for the growth of Klebsiella oxytoca in batch cultures using mixed substrates from glucose, xylose, arabinose, lactose, and fructose. Based entirely on information procured from batch growth on single substrates, the models accurately predict without further parameter fitting, diauxic growth on mixed substrates, automatically predicting the order in which the substrates are consumed. Even triauxic growth on a mixture of glucose, xylose, and lactose is predicted by the model based on single substrate data. Growth on glucose‐fructose mixtures appears to need a slightly modified strategy for cybernetic variables.
Effects of mixing during acid addition on fractionally precipitated protein
Authors: Fisher R. R. , Glatz C. E. , Murphy P. A. 
Published: May 2005

AbstractIsoelectric fractionation of the two major proteins of soy is characterized. Fractions are acid precipitated and cen‐trifugally collected at pH 6.0 (glycinin) and pH 4.8 (β‐conglycinin). Two extremes in the speed of acid addition (rapid, with no mixing, and slow, via acid dialysis, with complete mixing) are compared to determine their effects on the properties of the precipitate. Total protein yield, fraction composition, and aggregate microstructure do not depend significantly on the method of acid addition. Particle size distribution and hindered settling behavior do differ and are explained using a model of aggregate strength. The rapid acid addition produces larger primary particles, because of higher supersaturation, and yields larger aggregates, because of higher interparticle potential and stronger aggregates. Further aggregation in low‐shear hindered settling is faster for the slowly precipitated aggregate because few of these bonding sites could survive the high‐shear precipitator, whereas more can contribute to aggregation during hindered settling.
Operation and pressure distribution of immobilized cell hollow fiber bioreactors
Authors: Tharakan John P. , Chau Pao C. 
Published: May 2005

AbstractIt has been cited in the literature on hollow fiber systems that pressure gradients persist, and the transmembrane flux of the hollow fiber system is dependent on the pattern of the pressure gradients. The pattern can be used to its advantage in immobilized enzyme systems. However, with immobilized living cell systems, the pressure gradients lead to a nonuniform environment within the hollow fiber cartridge and not necessarily favorable results. This article provides pertinent pressure‐drop data on hollow fiber cartridges which are in flow configurations typical of immobilized cell culture work. The results illuminate operational problems that may arise in the culture of either anchorage dependent or independent cells. Possible solutions with crossflow systems are suggested.
Mixed culture model of anaerobic digestion: Application to the evaluation of startup procedures
Authors: Torre Alberto Dalla , Stephanppoulos Gregory 
Published: May 2005

AbstractThe successful operation of anaerobic digestion depends on the balanced growth of many bacterial species. The functions of the main groups of microorganisms present in a digester have been analyzed and a mathematical model constructed that describes the interactions among the microbial populations and their effect on the digester performance. The model was validated by comparing its predictions with actual digester operation. Several startup procedures were evaluated in the light of the model predictions and improvements on current operational practices suggested in order to minimize startup time.
Alcoholic fermentation of sorghum without cooking
Authors: Thammarutwasik Paiboon , Koba Yojiro , Ueda Seinosuke 
Published: May 2005

AbstractSorghum was used as raw material for alcoholic fermentation without cooking. Two varieties of sorghum grown in Thailand, KU 439 and KU 257, contained 80.0 and 75.8% of total sugar. Optimum amount of sorghum for alcoholic fermentation should be between 30 and 35% (w/v) in the fermentation broth. In these conditions 13.0 and 12.6% (v/v) of alcohol could be obtained in 84 and 91.9% yield based on the theoretical value of the starch content from KU 439 and KU 257, respectively.
Simulation study of anaerobic digestion control
Authors: Torre Alberto Dalla , Stephanopoulos Gregory 
Published: May 2005

AbstractA mixed culture anaerobic digestion model developed previously was applied to the evaluation of several digester control strategies. It was found that pH control by base addition or flow rate manipulation is inadequate. Based on an analysis of digester dynamics, a new control of the total suspended solids concentration at the feed was proposed through the manipulation of the underflow flow rate of the preceeding sedimentation unit. This control was tested in a variety of simulated runs and proved very effective in eliminating most of the usual causes of digester failure.
Effect of organic solvents on the activity of glucoamylase
Authors: Nagamoto H. , Yasuda T. , Inoue H. 
Published: May 2005

AbstractHydrolyses of maltose, maltotriose, and soluble starch catalyzed by glucoamylase (Asp. Niger) were carried out in the aqueous solutions of methanol, ethanol, ethylene glycol, and 1,4‐dioxane at 40°C and at the optimum pH in the respective solutions. By the kinetic analysis based on the subsite model, it was shown that the intrinsic rate constant, Kint, was electrostatically affected by the dielectric constant of the hydroorganic solutions. The affinity of the third subsite, A3, which affects the apparent rate constant, K0, was correlated with the ×Gtr's of maltose and amino acid side chains.
Mathematical model of extractive fermentation: Application to the production of ethanol
Authors: Fournier Ronald L. 
Published: May 2005

AbstractA mathematical model has been developed for the process of extractive fermentation. The model rigorously treats the material balance, reaction kinetics, and liquid–liquid equilibrium relationships. Convergence is promoted through use of the Quasi‐Newton Method. Extractive fermentation is particularly attractive for those bioreactions where the cell growth and product formation is inhibited by the product or other secondary cellular products. The model is illustrated for the production of ethanol. The results show an increase in specific productivity and the ability to process a more concentrated feed. However, volumetric productivity is reduced in the presence of a low capacity solvent.
Structures of steady states of an enzyme reaction in a CSTR
Authors: Byeon Kee Hoh , Chung In Jae 
Published: May 2005

AbstractStructures at steady states have been investigated for an enzyme reaction in a continuous stirred tank reactor that has a random bi‐uni reaction mechanism, using the imperfect bifurcation theory via singularities. The analysis has shown that two types of singular points exist. One of these points has the two types of transition states characterized by the hysteresis and double‐limit points. It is obtained when the derivative of the steady‐state equation with respect to the bifurcation parameter does not vanish. When the derivative vanishes, the other type of singular point is obtained. This point has the two transition states of hysteresis and bifurcation points.
Periodical batch culture of the immobilized growing fungi Sporotrichum cellulophilum producing cellulase in the nonwoven materials
Authors: Tamada Masao , Kasai Noboru , Kumakura Minoru , Kaetsu Isao 
Published: May 2005

AbstractThe thermophilic fungus Sporotrichum cellulophilum was immobilized with nonwoven materials for cellulase production. The cellulose powder concentration in the medium was an important factor controlling cellulase production. When the cellulose powder concentration in the nonwoven materials was more than 4%, cellulase production was suppressed. The growth of the immobilized fungi depended on the spaces in the nonwoven materials. Immobilized growing fungi were retained by the non‐woven materials, and the supernatant medium did not contain mycelia. The heat stability of the immobilized growing fungus was higher than that of the free fungus. The immobilized fungus gave the same FPA as the free mycelium, but the lag time for cellulase production in the immobilized fungus was longer. It was necessary for the only medium to be changed in order to get the immobilized growing fungus to continue producing cellulase. In this instance there was no difference of lag time in comparison with the free cells, and the supply of cellulose powder and polypepton was reduced to two‐thirds. After 23 exchanges of the medium (2.6 mg cellulose powder/1 cm3 nonwoven materials) FPA value was maintained. The periodic batch culture was continued for 69 days.
Heterogeneous one‐dimensional model for fixed bed enzyme reactors
Authors: Lortie R. , Thomas D. 
Published: May 2005

AbstractA one‐dimensional model, taking into account the diffusion of substrate between the liquid phase and the solid support, has been used to describe fixed bed enzyme reactors. The equations were solved numerically, and the values of the different parameters were calculated by a nonlinear regression method. The model was applied to different systems. The results are presented and discussed.
Diffusion in κ‐carrageenan gel beads
Authors: Nguyen An‐Lac , Luong J. H. T. 
Published: May 2005

AbstractUsing a well‐mixed and temperature‐led vessel, the diffusion characteristics of various solutes into spherical κ‐carrageenan gel beads were experimentally investigated. The diffusion coefficient of glucose was markedly affected by the glucose concentration and the operating temperature. In all cases the diffusivity obtained was noticeably smaller than that of glucose in pure water. The experimental data also indicated an inverse relationship between the diffusivity and the polymer concentration used in the gel preparation. As well, the glucose diffusivity was affected by the presence of other solutes in the glucose solution. Electrolytes such as ammonium sulfate, KCl, and CaCl2 were observed to enhance the diffusion coefficient. On the other hand, the addition of arginine or bovine serum albumin had an adverse effect on the diffusivity. No diffusion of albumin into the gel beads was observed, and such a solute created a significant mass transfer resistance during the diffusion process.
Deactivation theory
Authors: Henley James P. , Sadana Ajit 
Published: May 2005

AbstractA general model of enzyme deactivations involving unimolecular processes is introduced. For most mechanisms of this type, the parameters of the general model can be expressed in terms of actual physical parameters. The number of physical parameters that can be determined from the deactivation data cannot exceed the number of independent constants in the general model. When there is an excess of physical parameters, then some parameters must be determined from independent methods of analysis. If this is not possible, then some parameters must be left as lumped parameters or global parameters. The general form of the model can be useful in determining the number of independent, potentially active forms of the enzyme present during deactivation. Some exceptions to the general model are due to higher‐order processes such as dissociation, autolysis, and biological contamination.
Substrate concentration control by dialysis in fermentations of Escherichia coli
Authors: Thompson B. G. 
Published: May 2005

AbstractA substrate control system based upon dialysis culture techniques has been developed. In fermentations of Escherichia coli where phosphate or sulfate concentrations were controlled, the relation between the apparent specific growth rate, μ, and the phosphate concentration followed Monod kinetics, while the relation between μ and sulfate showed a sharp optimun. The pH of fermentations of E. coli was controlled by dialysis culture techniques without the fluctuations in pH associated with control by direct addition of acid or base.
Reduction of waste product excretion via nutrient control: Possible strategies for maximizing product and cell yields on serum in cultures of mammalian cells
Authors: Glacken M. W. , Fleischaker R. J. , Sinskey A. J. 
Published: May 2005

AbstractMammalian cells grown in culture excrete lactic acid and ammonium ions in quantities that may limit growth and reduce product synthesis. Frequent replenishment of the culture medium is often necessary to prevent waste product accumulation which could inhibit cell growth. Since increased medium replenishment results in increased usage of animal serum, the most expensive raw material, excessive production of waste products lowers the cell and product yield on serum, and hence increases production costs. Strategies for reducing the production of lactic acid and ammonium bymammalian cells via controlled addition of glucose and glutamine will be demonstrated. Mathematical relations coupling ammonium and glutamine kinetics will be described. Additionally, a method for automatic on‐line estimation of the cell concentration was developed. This method involves calculating the ATP production rate from the oxygen uptake rate and the lactic acid production rate. Automatic online estimation of the cell concentration is critical if nutrient levels in large‐scale mammaliancell cultures are to be accurately maintained via process control.
Biofilm development in laboratory methanogenic fluidized bed reactors
Authors: Gorris L. G. M. , van Deursen J. M. A. , van der Drift C. , Vogels G. D. 
Published: May 2005

AbstractBiofilm development on sand with different heterogeneous inocula was studied in laboratory‐scale methanogenic fluidized bed reactors. Both the course of biofilm formation during reactor start‐up and the bacterial composition of newly developed biofilms at steady‐state were found to be similar irrespective of the type of inoculum applied. Biofilm formation proceeded according to a fixed pattern that could be subdivided in three consecutive phases, designated as the lag phase, biofilm production phase, and steady‐state phase. Methanogenic activity and biomass content of the fluidized bed granules were found to be accurate parameters of the course of biofilm formation. More indirect parameters monitored did not give unambiguous results in all instances. The composition of the newly developed biomass as assessed on the basis of potential methanogenic activities on different substrates and of the concentration of specific methanogenic cofactors was consistent with electron microscopic observations.
Studies of Saccharomyces cerevisiae during fermentation—an in vivo electrokinetic investigation
Authors: Bowen W. Richard , Cooke Richard J. 
Published: May 2005

AbstractAn extensive in vivo study of the electrokinetic properties of six strains of the brewing yeast S. cerevisiae has been carried out. The yeasts were cultured under laboratory conditions. They were electrokinetically characterized by the electro‐osmotic dipped cell technique, and data are presented as zeta‐potentials. The effects of pH, fermentation time, successive fermentation cycles, and initial wort density have been established. The electrokinetic properties of an ale yeast which did not function correctly during commercial fermentation have also been examined. The results are discussed in the context of two controversial topics concerning the mechanism of yeast flocculation, the relative importance of yeast cell wall carboxyl and phosphate groups and the influence of wort components.
Growth and death in overagitated microcarrier cell cultures
Authors: Croughan Matthew S. , Wang Daniel I. C. 
Published: May 2005

AbstractThe effects of hydrodynamic forces on cell growth are investigated for animal cells growing on microcarriers. A reduction in net growth was observed with high levels of agitation. DNA measurements indicated that the reduction in net growth was due entirely to cell death, from hydrodynamic forces. No inhibition or enhancement of cell replication appeared to occur with high levels of agitation.
Control of interspecies electron transfer flow during anaerobic digestion: Dynamic diffusion reaction models for hydrogen gas transfer in microbial flocs
Authors: Ozturk Sadettin S. , Palsson Bernhard O. , Thiele Jurgen H. 
Published: May 2005

AbstractDynamic reaction diffusion models were used to analyze the consequences of aggregation for syntrophic reactions in methanogenic ecosystems. Flocs from a whey digestor were used to measure all model parameters under the in situ conditions of a particular defined biological system. Fermentation simulations without adjustable parameters could precisely predict the kinetics of H2 gas production of digestor flocs during syntrophic methanogenesis from ethanol. The results demonstrated a kinetic compartmentalization of H2 metabolism inside the flocs. The interspecies electron transfer reaction was mildly diffusion controlled. The H2 gas profiles across the flocs showed high H 2 concentrations inside the flocs at any time. Simulations of the syntrophic metabolism at low substrate concentrations such as in digestors or sediments showed that it is impossible to achieve high H2 gas turnovers at simultaneously low steady‐state H2 concentrations. This showed a mechanistic contradiction in the concept of postulated low H2 microenvironments for the anaerobic digestion process. The results of the computer experiments support the conclusion that syntrophic H2 production may only be a side reaction of H2 independent interspecies electron transfer in methanogenic ecosystems.