bluuebunny/crossref_metadata_2025 huggingface dataset:
Do organic solvents affect the catalytic properties of lipase? Intrinsic kinetic parameters of lipases in ester hydrolysis and formation in various organic solvents
Authors: van Tol J. Bert A. , Stevens Rob M. M. , Veldhuizen Willem J. , Jongejan Jaap A. , Duine Johannis A.
Published: December 2004

When it is assumed that organic solvents do not interfere with the binding process nor with the catalytic mechanism, the contribution of substrate‐solvent interactions to enzyme kinetics can be accounted for by just replacing substrate concentrations in the equations by thermodynamic activities. It appears from the transformation that only the affinity parameters (Km, Ksp) are affected by this. Thus, in theory, the values of these corrected, intrinsic parameters (K, k) and the maximal rate (V1) should be equal for all media. This was tested for hydrolysis, transesterification, and esterification reactions catalyzed by pig pancreas lipase and Pseudomonas cepacia lipase in various organic solvents. Correction was carried out via experimentally determined activity coefficients for the substrates in these solvents or, if not feasible, from values in data bases. However, although the kinetic performances of each enzyme in the solvents became much more similar after correction, differences still remained. Analysis of the enzyme suspensions revealed massive particles, which explains the low activity of enzymes in organic solvents. However, no correlation was found between estimates of the amount of catalytically available enzyme (present at the surface of suspended particles or immobilized on beads) and the maximal rates observed. Moreover, the solvents had similar effects on the intrinsic parameters of suspended and immobilized enzyme. The possible causes for the effects of the solvents on the catalytic performance of the enzymes, remaining after correction for solvent‐substrate interactions and the amount of participating enzyme, are discussed with respect to the premises on which the correction method is based. © 1995 John Wiley & Sons, Inc.
Membrane‐attached biofilms for VOC wastewater treatment I: Novel in situ biofilm thickness measurement technique
Authors: dos Santos L. M. Freitas , Livingston A. G.
Published: December 2004

This article reports a novel nondisruptive technique for measuring the thicknesses of membrane‐attached biofilms in situ, using a single tube extractive membrane bioreactor (STEMB). The biodegradation of a toxic volatile organic compound (VOC) (1,2‐dichloroethane [DCE]) by Xanthobacter autotrophicus GJ10 has been used as a model system to develop the technique. The results give information on the biomass‐silicone rubber attachment phenomena, and on the development over time of biofilms growing on the silicone membrane, without disrupting operation. Experimental results are presented showing the evolution over time of biofilm thickness, and also the density of biofilms for four experimental runs. The hydrodynamic conditions on the biomedium side of the membrane were found to influence the initial attachment phenomena and subsequent biofilm growth. © 1995 John Wiley & Sons, Inc.
Kinetics of phenolic polymerization catalyzed by peroxidase in organic media
Authors: Xu Yue‐Ping , Huang Guo‐Lan , Yu Yao‐Ting
Published: December 2004

Phenolic polymerization was carried out by enzymatic catalysis in organic media, and its kinetics was studied by using high‐pressure liquid chromatography (HPLC). Phenols and aromatic amines with electron‐withdrawing groups could hardly be polymerized by HRP catalysis, but phenols and aromatic amines with electron‐donating groups could easily be polymerized. The reaction rate of either the para‐substituted substrate or meta‐substituted substrate was higher than that of ortho‐substituted substrate. When ortho‐position of hydroxy group of phenols was occupied by an electron‐donating group and if another electron‐donating group occupied para‐position of hydroxy group, the reaction rate increased. Horseradish peroxidase and lactoperoxidase could easily catalyze the polymerization, but chloroperoxidase and laccase failed to yield polymers. Metallic ions such as Mn2+, Fe2+, or Fe3+, and Cu2+ could poison horseradish peroxidase to various extents, but ions such as Co2+, Cd2+, Zn2+, and K+ were not found to inhibit the reaction. © 1995 John Wiley & Sons, Inc.
Production and properties of a bifunctional fusion protein that mediates attachment of vero cells to cellulosic matrices
Authors: Wierzba Andrew , Reichl Udo , Turner Robin F. B. , Warren R. Antony J. , Kilburn Douglas G.
Published: December 2004

The sequence Arg‐Gly‐Asp (RGD) in extracellular matrix proteins such as fibronectin, collagen, and laminin mediates cell attachment by interacting with proteins of the integrin family of cell surface receptors. A gene fusion encoding the RGD‐containing peptide, fused to the C‐terminus of a cellulose‐binding domain (CBD/RGD), was expressed in Escherichia coli. Cultures produced up to 50 mg of CBD/RGD per liter, most of which was extracellular. It was purified from the culture supernatant by affinity chromatography on cellulose. CBD/RGD promoted the attachment of green monkey Vero cells to polystyrene and cellulose acetate. Attachment was inhibited by small synthetic peptides containing the RGD sequence. CBD/RGD was as effective as collagen in promoting the attachment of Vero cells to Cellsnow™ microcarriers. © 1995 John Wiley & Sons, Inc.
Fluxes of carbon, phosphorylation, and redox intermediates during growth of saccharomyces cerevisiae on different carbon sources
Authors: Cortassa Sonia , Aon Juan C. , Aon Miguel A.
Published: December 2004

In the present work we develop a method for estimating anabolic fluxes when yeast are growing on various carbon substrates (glucose, glycerol, lactate, pyruvate, acetate, or ethanol) in minimal medium. Fluxes through the central amphibolic pathways were calculated from the product of the total required amount of a specified carbon intermediate times the growth rate. The required amount of each carbon intermediate was estimated from the experimentally determined macromolecular composition of cells grown in each carbon source and the monomer composition of macromolecules.

Substrates sharing most metabolic pathways such as ethanol and acetate, despite changes in the macromolecular composition, namely carbohydrate content (34% ± 1 and 21% ± 3, respectively), did not show large variations in the overall fluxes through the main amphibolic pathways. For instance, in order to supply anabolic precursors to sustain growth rates in the range of 0.16/h to 0.205/h, similar large fluxes through Acetyl CoA synthase were required by acetate (4.2 mmol/hr g dw) or ethanol (5.2 mmol/h g dw).

The Vmax activities of key enzymes of the main amphibolic pathways measured in permeabilized yeast cells allowed to confirm, qualitatively, the operation of those pathways for all substrates and were consistent on most substrates with the estimated fluxes required to sustain growth.

When ATP produced from oxidation of the NADH synthesized along with the key intermediary metabolites was taken into account, higher Y values (36 with respect to 24 g dw/mol ATP) were obtained for glucose. The same result was obtained for glycerol, ethanol, and acetate. A yield index (YI) was defined as the ratio of the theoretically estimated substrate flux required to sustain a given growth rate over the experimentally measured flux of substrate consumption. Comparison of Yl between growth on various carbon sources led us to conclude that ethanol (Yl = 0.84), acetate (Yl = 0.77), and lactate (Yl = 0.77) displayed the most efficient use of substrate for biomass production. For the other substrates, the Yl decayed in the following order: pyruvate > glycerol > glucose.

An improvement of the quantitative understanding of yeast metabolism, energetics, and physiology is provided by the present analysis. The methodology proposed can be applied to other eukaryotic organisms of known chemical composition. © 1995 John Wiley & Sons, Inc.
Effect of yeast extract on growth kinetics during aerobic biodegradation of chlorobenzoic acids
Authors: Armenante Piero M. , Fava Fabio , Kafkewitz David
Published: December 2004

The Monod or Andrews kinetic parameters describing the growth of Pseudomonas sp. CPE2 strain on 2,5‐dich!orobenzoic acid and 2‐chlorobenzoic acid, and Al‐caligenes sp. CPE3 strain on 3,4‐dichlorobenzoic acid, 4‐chlorobenzoic acid, and 3‐chlorobenzoic acid were determined from batch and continuous growth experiments conducted in the presence or absence of yeast extract (50 mg/L). Strain CPE2 displayed inhibitory growth kinetics in the absence of yeast extract and a noninhibitory kinetics in the presence of yeast extract. Similar results were obtained for CPE3. The presence of yeast extract also resulted in a significant increase in the affinity of the strains for the chlorobenzoic acids they degraded. © 1995 John Wiley & Sons, Inc.
A structured metabolic model for anaerobic and aerobic stoichiometry and kinetics of the biological phosphorus removal process
Authors: Smolders G. J. F. , van der Meij J. , van Loosdrecht M. C. M. , Heijnen J. J.
Published: December 2004

A structured metabolic model is developed that describes the stoichiometry and kinetics of the biological P removal process. In this approach all relevant metabolic reactions underlying the metabolism, considering also components like adenosine triphosphate (ATP) and nic‐otinamide‐adenine dinucleotide (NADH2) are describedbased on biochemical pathways. As a consequence of the relations between the stoichiometry of the metabolic reactions and the reaction rates of components, the required number of kinetic relations to describe the process is reduced. The model describes the dynamics of the storage compounds which are considered separately from the active biomass. The model was validated in experiments at a constant sludge retention time of 8 days, over the anaerobic and aerobic phases in which the external oncentrations as well as the internal fractions of the relevant components involved in the P‐removal process were monitored. These measurements include dissolved acetate, phosphate, and ammonium; oxygen consumption; poly‐β‐hydroxybutyrate (PHB); glycogen; and active biomass. The model satisfactorily describes the dynamic behavior of all components during the anaerobicand aerobic phases.© 1995 John Wiley & Sons, Inc
In‐situ removal of ammonium and lactate through electrical means for hybridoma cultures
Authors: Chang Yu‐Hsiang David , Grodzinsky Alan J. , Wang Daniel I. C.
Published: December 2004

Ammonium and lactate are two known toxic products detrimental to mammalian cell growth and productivity. An electrokinetic technique, utilizing an electrophoretic mechanism, was developed to remove these cellular wastes in‐situ from suspension hybridoma (ATCC CRL‐1606) cultures to enhance cell growth and productivity. This technique applies continuously a dc electric field to selectively remove the electrically charged wastes. The experiments were shown to be successful in the removal of externally added 10 rnM ammonium and 45 mM lactate while maintaining the chemostatic condition of culture medium in a cell‐free condition under an electric current density of 50 A/m2. Toxic levels of ammonium were added, ranging from 7.5 to 12.5 mM, at the start of the hybridoma culture, and the applied dc electric fields were able to completely remove these added materials. This in turn released the inhibition and restored the cell growth. Finally, this electrokinetic technique was applied to the batch and glutamine fed‐batch hybridoma cultures. At an applied electric current density of 50 A/m2, this was able to completely remove cell‐produced ammonium and increased the cell growth and antibody titer by 30% to 50%, respectively, compared to the control experiment in the absence of the electric field. Lastly, the applied electric current density of 50 A/m2 did not affect cellular functionalities such as glucose and glutamine consumption and antibody productivity.© 1995 John Wiley & Sons, Inc
Analysis of cell‐to‐bubble attachment in sparged bioreactors in the presence of cell‐protecting additives
Authors: Michaels James D. , Nowak Jason E. , Mallik Ameet K. , Koczo Kalman , Wasan Darsh T. , Papoutsakis Eleftherios T.
Published: December 2004

To investigate the mechanisms of cell protection provided by medium additives against animal cell injury in sparged bioreactors, we have analyzed the effect of various additives on the cell‐to‐bubble attachment process using CHO cells in suspension. Cell‐to‐bubble attachment was examined using three experimental techniques: (1) cell‐bubble induction time analysis (cell‐to‐bubble attachment times); (2) forming thin liquid films and observing the movement and location of cells in the thin films; and (3) foam flotation experiments. The induction times we measured for the various additives are as follows: no additive (50 to 500 ms), polyvinyl pyrrolidone (PVP: 20 to 500 ms), polyethylene glycol (PEG: 200 to 1000 ms), 3% serum (500 to 1000 ms), polyvinyl alcohol (PVA: 2 to 10 s), Pluronic F68 (5 to 20 s), and Methocel (20 to 60 s). In the thin film formation experiments, cells in medium with either F68, PVA, or Methocel quickly flowed out of draining thin liquid films and entered the plateau border. When using media with no additive or with serum, the flow of cells out of the thin liquid film and film drainage were slower than for media containing Pluronic F68. PVA, or Methocel. With PVP and PEG, the thin film drainage was much slower and cells remained trapped in the film. For the foam flotation experiments, a separation factor (ratio of cell concentration in the foam catch to that in the bubble column) was determined for the various additives. In the order of increasing separation factors (i.e., increasing cell attachment to bubbles), the additives are as follows: Methocel, PVA, Pluronic F68, 3% serum, serum‐free medium with no additives, PEG, and PVP. Based on the results of these three different cell‐to‐bubble attachment experiments, we have classified the cell‐protecting additives into three groups: (1) Pluronic F68, PVA, and Methocel (reduced cell‐to‐bubble attachment); (2) PEG and PVP (high or increased cell‐to‐bubble attachment); and (3) FBS (reduced cell attachment butslower drainage films compared with F68, PVA, and Methocel with some cell entrapment in those films). These phenomena are discussed in relation to the interfacial properties of the media reported in a companion Study (this issue). © 1995 John Wiley & Sons Inc.
Enhanced acetone‐butanol fermentation using repeated fed‐batch operation coupled with cell recycle by membrane and simultaneous removal of inhibitory products by adsorption
Authors: Yang Xiaoping , Tsao George T.
Published: December 2004

A novel acetone–butanol production process was developed which integrates a repeated fed‐batch fermentation with continuous product removal and cell recycle. The inhibitory product concentrations of the fermentation by Clostridium acetobutylicum were reduced by the simultaneous extraction process using polyvinylpyridine (PVP) as an adsorbent. Because of the reduced inhibition effect, a higher specific cell growth rate and thus a higher product formation rate was achieved. The cell recycle using membrane separation increased the total cell mass density and, therefore, enhanced the reactor productivity. The repeated fed‐batchoperation overcame the drawbacks typically associated with a batch operation such as down times, long lag period, and the limitation on the maximum initial substrate concentration allowed due to the substrate inhibition. Unlike a continuous operation, the repeated fed‐batch operation could beoperated for a long time at a relatively higher substrate concentration without sacrificing the substrate loss in the effluent. As a result, the integrated process reached 47.2 g/L in the equivalent solvent concentration (including acetone, butanol, and ethanol) and 1.69 g/L · h in the fermentor productivity, on average, over a 239.5‐h period. Compared with a controlled traditional batch acetone–butanol fermentation, the equivalent solvent concentration and the tormentor productivity were increased by 140% and 320%, respectively. © 1995 John Wiley & Sons Inc.
Morphology of Trichoderma reesei QM 9414 in submerged cultures
Authors: Lejeune R. , Nielsen J. , Baron G. V.
Published: December 2004

The microscopic morphology of Trichoderma reesei QM 9414, growing in submerged culture, was studied by image analysis. The morphology was characterized by the total hyphal length, the total number of tips, the number of actively growing tips, and the length of the main hypha. To describe the growth of a single mycelium a simple model is set‐up. The main features of the model are: (1) saturation type kinetics for the tip extension of the individual branches within the mycelium; and (2) random branching with a frequency function, which is proportional to the total hyphal length. The model is used to simulate a population of mycelia, where spore germination is described with a log‐normal distribution. From the simulation of the population, the average properties of the mycelia, e.g., the average total hyphal length, are calculated, and by fitting the model to experimental data the model parameters are estimated. Finally, the distribution function with respect to the mycelia properties, that is, number of tips and total hyphal length, is calculated, and it corresponds well with the experimental determination of the distribution function. © 1995 John Wiley & Sons Inc.
Sequential adsorption of F(ab′)2 and BSA on negatively and positively charged polystyrene latexes
Authors: Ortega‐Vinuesa J. L. , Hidalgo‐Álvarez R.
Published: December 2004

The aim of the present work is to study the sequential adsorption of F(ab′)2 and bovine serum albumin (BSA) molecules adsorbed onto positively and negatively charged polystyrene latexes. Cationic and anionic latexes were prepared by emulsifier‐free emulsion polymerization. Adsorptions of F(ab′)2 on both latexes at a low ionic strength and different pHs were performed. The cationic latex showed a higher adsorption of F (ab′)2 molecules over a range of pH, which could be due to the formation of multilayers. Sequential adsorption of anti‐CRP F(ab′)2 and monomeric BSA were performed at two different pre‐adsorbed F(ab′)2 amounts on both types of latex. Displacement of F(ab′)2 occurred only when the preadsorbed amounts were larger than a certain critical value, which depends on the adsorption pH. A greater displacement of larger preadsorbed amounts might be the result of a weaker contact between the protein molecules and the polystyrene surface. The displacement of F(ab′)2 previously adsorbed onto both latexes occurred due to pH changes, an increase of ionic strength and the presence of BSA molecules. The effect caused by these three factors was studied independently. The main factors in the desorption of F(ab′)2 on the anionic latex are the changes in pH and ionic strength, whereas on the cationic latex the desorption is mainly caused by the increase of the ionic strength and the presence of BSA. The colloidal stability of the immunotatex was improved by BSA adsorption, especially on cationic latex. © 1995 John Wiley & Sons, Inc.
On the use of the pH control reagent addition rate for fermentation monitoring
Authors: Siano Steven A.
Published: December 2004

The linear relation between the pH control reagent addition rate, the net conversion rates of metabolites, the carbon dioxide mass transfer rate and the feed rates is developed and shown to have the same form for batch, fed‐batch, and continuous reactors, regardless of the number of feeds. The magnitudes of various biological and solution chemistry effects on the pH control reagent addition rate are estimated to be negligible, facilitating the use of the pH control reagent addition rate as a straightforward indicator of primary metabolism. Finally, application of the linear relation, termed the abiotic proton balance, is discussed for a number of fermentation processes. © 1995 John Wiley & Sons, Inc.
Use of comparative reasoning tools for evaluation of the effect of sterilization conditions on fermentations to produce acidic fibroblast growth factor
Authors: Marshall Carolynne T. , Lilly Malcolm D. , Gbewonyo Kodzo , Buckland Barry C.
Published: December 2004

The effects of various medium sterilization conditions on fermentations of a recombinant, acidic fibroblast growth factor (aFGF) producing Escherichia coli have been studied. Changes in the medium resulting from sterilization were monitored by pH and absorption spectra. This simple experiment provided excellent data for the demonstration of the usefulness of comparative reasoning tools in order to evaluate the effect of sterilization on fermentation performance. The time profiles of the main parameters (e.g., carbon dioxide evolution rate, dissolved oxygen, pH, and aFGF productivity) were simplified into piecewise contiguous linear segments, each of which was sequentially numbered. The length, position, and slope of each tine were then characterized. Application of the comparative reasoning tools confirmed that separate sterilization of the glucose was necessary for the success of the process, despite adding to the cost and complexity. The comparative data analysis also showed that scaleup with longer sterilization holding and cooling times would not be detrimental to aFGF production. © 1995 John Wiley & Sons, Inc.
Modeling biofilm accumulation and mass transport in a porous medium under high substrate loading
Authors: Wanner O. , Cunningham A. B. , Lundman R.
Published: December 2004

A packed bed biofilm reactor inoculated with pure culture Pseudomonas aeruginosa was run under high substrate loading and constant flow rate conditions. The 3.1‐cm‐diameter cylindrical reactor was 5 cm in length and packed with 1‐mm glass beads. Daily observations of biofilm thickness, influent and effluent glucose substrate concentration, and effluent dissolved and total organic carbon were made during the 13‐day experiment. Biofilm thickness appeared to rech quasi‐steady‐state condition after 10 days. A published biofilm process simulation program (AQUASIM) was used to analyze experimental data. Comparison of observed and simulated variables revealed three distinct phases of biofilm accumulation during the experiment: an initial phase, a growth phase, and a mature biofilm phase. Different combinations of biofilm and mass transport process variables were found to be important during each phase. Biofilm detachment was highly correlated with shear at the biofilm surface during all three phases of biofilm development. © 1995 John Wiley & Sons, Inc.
Implantable hollow fiber bioreactor as a potential treatment for hypercholesterolemia: Characterization of the catalytic unit
Authors: Shefer Samuel D. , Rosenberger Vered , Vahanian Gizette , Wong Wai T. , Langer Robert
Published: December 2004

Previous studies have shown that the modification of low density lipoprotein (LDL) by the enzyme phospholipase A2(PLA2)results in a reduction of cholesterol levels in the plasma of hypercholesterolemic rabbits, due to accelerated clearance of the modified LDL. In the current study, we established techniques and optimized the ratio of enzyme to support for the immobilization of PLA2 on a polymeric support. Hollow fiber bioreactors made from polytetrafluoroethylene (PTFE) polymers were used to encapsulate immobilized PLA2. This design was adopted to eliminate hemolysis of red blood cells by the enzyme. Characterization of the resulting immobilized enzyme in terms of its activity, Michaelis‐Menten kinetic constants, and the variation of its activity with incubation time is presented. The enzyme activity was not significantly altered upon incubation at 37°C in lipoprotein‐deficient serum (LPDS), over the course of 2 months. The Michaelis–Menten kinetics constants are KM = 8.9 mM, Vmax = 6434.2 for the free enzyme and K = 16.7 mM, V = 619.7 for the immobilized enzyme. These data suggest that a system based on immobilized PLA2 in conjunction with hollow fiber bioreactors (HFBs) may be a good candidate for lowering LDL levels in plasma. © 1995 John Wiley & Sons, Inc.
Overexpression of bcl‐2, apoptosis suppressing gene: Prolonged viable culture period of hybridoma and enhanced antibody production
Authors: Itoh Yohito , Ueda Hiroshi , Suzuki Eiji
Published: December 2004

Human bcl‐2 DNA was introduced into mouse hybridoma 2E3 cells and expressed at a high level by using BCMGSneo vector, which reportedly amplifies as multiple copies in the cells independently of their chromosomes. The high expression of bcl‐2 in BCMGSneo‐bcl‐2 transfectants was confirmed by western blotting. In batch cultures, the overexpression of bcl‐2 raised the maximum viable cell density by 45%, delayed the initiation of apoptosis by 2 days, and prolonged the viable culture period by 4 days. The delayed initiation of apoptosis was detected by emergence of the ladder pattern on DNA electrophoresis and increase of the dead cell number. The bcl‐2 transfectants produced lgG1 fourfold per batch culture in comparison with 2E3 cells transfected with BCMGSneo but not with bcl‐2: a little less than twofold due to the improved survival of the cells and more than twofold due to the enhanced lgG1 production rate per cell of the bcl‐2 transfectants. The method to engineer hybridoma cells genetically with bcl‐2 using BCMGSneo vector for increasing viability and productivity would be widely applied for improving antibody productivity of hybridoma cultures. © 1995 John Wiley & Sons, Inc.
Augmentation of mass transfer through electrical means for hydrogel‐entrapped Escherichia coli cultivation
Authors: Chang Yu‐Hsiang David , Grodzinsky Alan J. , Wang Daniel I. C.
Published: December 2004

Nutrient depletion and inhibitory end‐product accumulation are the major problems for hydrogel‐entrapment cell cultures. An electrokinetic technique was developed to enhance intrahydrogel mass transfer to overcome these problems. Escherichia coli cells (ATCC 15224) were entrapped in 3.2‐mm‐thick potassium‐K‐carrageenan and agarose hydrogel slabs. With a electric current density of 180A/m2 the cell densities were increased by 140%(from 3.9 to 9.6 dry cell weight [DCW] g/L) in potassium‐K‐carrageenan and by 80% (from 3.9 to 7.0 DCW g/L) in agarose. A mathematical model taking into account nutrient depletion, inhibitory end‐product formation, and cell growth kinetics under facultatively anaerobic conditions was developed to rationalize the overall transport and biological behaviors in the hydrogel. The cell growth in hydrogel was successfully simulated. It is concluded that the augmented transports for glucose and inhibitory end‐products accounted for these increases in cell growth. The increase in cell density in potassium‐K‐carrageenan was due to the enhanced removal of inhibitory end‐products (through electroosmosis and electro‐phoresis: 80%) and due to the augmented glucose transport (through electroosmosis: 20%). © 1995 John Wiley & Sons, Inc.
Effects of chemical treatments and heating on the crystallinity of celluloses and their implications for evaluating the effect of crystallinity on cellulose biodegradation
Authors: Weimer P. J. , Hackney J. M. , French A. D.
Published: December 2004

Chemical treatments similar to those routinely used to extract cellulose from plant biomass caused significant increases in the relative crystallinity index (RCI) of Sig‐macell 100 (a commercial cellulose of moderate crystallinity), as measured by x‐ray powder diffraction in both the reflectance and transmittance modes. In general, the largest increases in RCI were observed following higher (rather than lower) temperature treatments. Substantial increases in crystalliity were also observed upon resuspension in water prior to drying, with higher temperatures again resulting in the greatest increases in RCI. Measurement of the RCIs of wetted Sigmacell 100 samples by acid hydrolysis kinetics revealed that most of the increased crystallinity occurred rapidly upon contact with water. In contrast to Sigmacell 100, a cellulose of higher initial crystallinity (the microcrystalline cellulose Sigmacell 50) showed little change in crystallinity following the above treatments. The results provide a partial explanation for the inconsistent relationships reported between cellulose crystallinity and cellulose biodegradation. © 1995 John Wiley & Sons, Inc.
Protein purification by bulk crystallization: The recovery of ovalbumin
Authors: Judge Russell A. , Johns Michael R. , White Edward T.
Published: December 2004

Crystallization is used industrially for the recovery and purification of many inorganic and organic materials. However, very little is reported on the application of bulk crystallization for proteins. In this work, ovalbumin was selected as a model protein to investigate the feasibility of using bulk crystallization for the recovery and purification of proteins. A stirred 1‐L seeded batch crystallizer was used to obtain the crystal growth kinetics of ovalbumin in ammonium sulfate solutions at 30°C. The width of the metastable region, in which crystal growth can occur without any nucleation, is equivalent to a relative supersaturation of about 20. The bulk crystallizations were undertaken within this range (using initial relative supersaturations less than 10) and nucleation was not observed. The ovalbumin concentration in solution was measured by UV absorbance and checked by crystal content measurement. Crystal size distributions were measured both by using a Malvern Mastersizer and by counting crystals through a microscope. The crystal growth rate was found to have a second‐order dependence upon the ovalbumin supersaturation. While there is no discernible effect of ammonium sulfate concentration at pH 4.90, there is a slight effect at higher pH values. Overall the effect of ammonium sulfate concentration is small compared to the effect of pH, for which there is a 10‐fold increase in the growth rate constant, kGσ over the range pH 4.6–5.4. To demonstrate the degree of purification which can be achieved by bulk crystallization, ovalbumin was crystallized from a solution containing conalbumin (80,000 Da) and lysozyme (14, 600 Da). After one crystallization and a crystal wash, ovalbumin crystals were produced with a protein purity greater than 99%. No contamination by the other proteins was observed when using overloaded sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) stained with Coomassie blue stain and only trace amounts of lysozyme were observed using a silver stain. The presence of these other proteins in solution did not effect the crystal growth rate constant, kGσ. The study demonstrates the feasibility of using bulk crystallization for the recovery and purification of ovalbumin. It should be readily applicable to other protein systems. © 1995 John Wiley & Sons, Inc.
Development of an expanded bed technique for an affinity purification of G6PDH from unclarified yeast cell homogenates
Authors: Chang Y. K. , McCreath G. E. , Chaset H. A.
Published: December 2004

The use of an expanded bed of STREAMLINE Red H‐7B for the purification of the intracellular glycolytic enzyme glucose 6‐phosphate dehydrogenase (G6PDH) directly from untreated preparations of disrupted yeast cells has been investigated. Small‐scale experiments, carried out in packed beds, have shown that the optimal pH for adsorption is 6.0 and have enabled optimization of elution conditions using a series of eluents. The dynamic capacity of the adsorbent for G6PDH was determined in a small expanded bed to be 28 units/mL. These results were used to develop a preparative scale separation of G6PDH in a STREAMLINE 50 expanded bed column. G6PDH was purified directly from an unclarified yeast homogenate in 99% yield with an average purification factor in the eluted fraction of 103. Cleaning‐in‐place (CIP) procedures using 0.5 M NaOH and 4M urea in 60% (v/v) ethanol have demonstrated that the adsorbent can be regenerated with no loss of adsorption capacity of alteration of bed expansion characteristics after many cycles of operation. © 1995 John Wiley & Sons, Inc.
Microfiltration of recombinant yeast cells using a rotating disk dynamic filtration system
Authors: Lee Steven S. , Burt A. , Russotti G. , Buckland B.
Published: December 2004

To develop a highly efficient cell harvest step under time constraint, a novel rotating disk dynamic filtration system was studied on the laboratory scale (0.147‐ft.2 nylon membrane) for concentrating recombinant yeast cells containing an intracellular product. The existing cross‐flow microfiltration method yielded pseudo‐steady state flux values below 25 LMH (L/m2. h) even at low membrane loadings (10 L/ft.2). By creating high shear rates (up to 120,000−1) on the membrane surface using a rotating solid disk, this dynamic filter has demonstrated dramatically improved performance, presumably due to minimal cake buildup and reduced membrane fouling. Among the many factors investigated, disk rotating speed, which determines shear rates and flow patterns, was found to be the most important adjustable parameter. Our experimental results have shown that the flux increases with disk rotating speed, increases with transmembrane pressure at higher cell concentrations, and can be sustained at high levels under constant flux mode. At a certain membrane loading level, there was a critical speed below which it behaved similarly to a flat sheet system with equivalent shear. Average flux greater than 200 LMH has been demonstrated at 37‐L/ft.2 loading at maximum speed to complete sixfold concentration and 15‐volume diafiltration for less than 100 min. An order of magnitude improvement over the crossflow microfiltration control was projected for large scale production. This superior performance, however, would be achieved at the expense of additional power input and heat dissipation, especially when cell concentration reaches above 80 g dry cell weight (DCW)/L. Although a positive linear relationship between power input and dynamic flux at a certain concentration factor has been established, high cell density associated with high viscosity impacted adversely on effective average shear rates and, eventually, severe membrane fouling, rather than cake formation, would limit the performance of this novel system. © 1995 John Wiley & Sons, Inc.
Ein vollelektrischer Polarograph
Authors: Lieneweg Fritz
Published: December 2004

Die Aufzeichnung polarographischer Kurven in Tintenschrift gestattet einfachstes Modellieren und Auswerten der Kurven. Für den Betrieb normaler Tintenschreiber unter Verstärkung der Elektrodenströme mittels Verstärker in Saugschaltung1 wurde während des Krieges ein vollelektrisch arbeitendes Zusatzgerät durchgebildet, in dem alle erforderlichen Schaltelemente und Verstellorgane zur Kurvenaufnahme untergebracht sind. Die einfach zu bedienende, robuste und universell verwendbare polarographische Meßeinrichtung läßt sich auch in technischen Betrieben zur Durchführung von Serienanalysen verwenden. Seine Wirkungsweise wird im folgenden unter Beifügung einiger charakteristischer Kurven erläutert.
Vergleich der Pektin‐Gewinnungsverfahren
Authors: Hottenroth Beatrix
Published: December 2004

Die Bedeutung, die das Pektin für die Lebensmittelversorgung und für andere zahlreiche Industriezweige erlangt hat, gibt Veranlassung dazu die verschiedenen Methoden aufzuzeigen, die zu seiner Gewinnung führen, und kurz auf die Wege hinzuweisen die in der Weiterentwicklung des bisher Erreichten von der neueren Forschung beschritten werden.
Neuere Kunststoffe in USA für den chemischen Apparatebau
Authors: Stoeckhert Klaus
Published: December 2004

Die härtbaren und thermoplastischen Kunststoffe sowie die synthetischen Kautschuksorten werden wegen ihrer Korrosionsbeständigkeit an zahlreichen Stellen des chemischen Apparatebaues verwendet, darüber hinaus auch in der Textilchemie, Nahrungsmittelindustrie und Metallurgie als Baumaterial oder als Hilfsmittel für Geräte, Anlagen und Apparate.
Unfallgefahren an Lichtbogen‐Reduktionsöfen und ihre Verhütung
Authors: Heering E.
Published: December 2004

Da das elektrothermische Schmelzverfahren in der chemischen Industrie immer mehr Eingang gefunden hat und mit der Verwendung größerer Anlagen die Unfallmöglichkeiten gestiegen sind, werden zunächst typische Unfälle beschrieben und dann einige Gesichtspunkte für deren Verhütung zusammengestellt.
Flußstahlemaillierung im chemischen Apparatebau
Authors: Frick Karl
Published: December 2004

Für großtechnische Apparaturen der chemischen Industrie ist das Emaillieren von Flußstahl eine noch junge Veredelungstechnik. Emaillierte Apparate und Rohrleitungen aus Flußstahl haben erst seit etwa 15 Jahren in größerem Umfange Eingang in die Verfahrenstechnik gefunden. Das bis dahin verwendete Gußeisenemail wurde in zunehmendem Maße verdrängt. Bedenken, welche wegen der Gestaltung und Größe der zu emaillierenden Gegenstände, der Bewährung im Betrieb und der Verletzbarkeit der Emailschicht geäußert wurden, treffen nicht mehr zu. Im vergangenen Jahrzehnt sind in enger Zusammenarbeit zwischen Hersteller und Verbraucher wichtige Erkenntnisse bei der Ausführung emaillierter Apparate aus Flußstahl gemacht worden.
Die Bedeutung der Edelmetalle für die deutsche chemische Industrie 1939–1949
Authors: Fröhlich K. W.
Published: December 2004

Edelmetalle verwendet man seit einem Jahrzehnt immer mehr im Apparate‐ und Gerätebau, für Elektroden, vor allem aber für Katalysatoren. Obwohl die Mengen klein sind, fehlen vielfach auch diese. Dies gab mitunter Anstoß zu Neuentwicklungen von bleibendem Wert.
Der heutige Stand im Säureschutz und Säurebau
Authors: Heinrich F.
Published: December 2004

Die zeitbedingten Schwierigkeiten haben auch auf dem Gebiet des Säureschutzes und Säurebaues1 manche aussichtsreiche Entwicklung unterbrochen oder erschwert. Im allgemeinen ist aber der frühere hohe Stand der Säureschutztechnik wieder erreicht; zahlreiche Ansätze einer konstruktiven und werkstoffmäßigen Weiterentwicklung sind zu verzeichnen.
Kunstseiden und Kunstspinnfasern
Authors: Zart A.
Published: December 2004

Es wird über die wesentlichen Fortschritte der letzten 10. Jahre auf dem Gebiet der Kunstseide und Kunstspinnfasern berichtet. Ausgehend von den Ausgangsstoffen werden die verschiedenen Verfahren zur Herstellung von Fasern aus Cellulose nach dem Viskose‐ und dem Cuprammon‐Verfahren, der Acetat‐Fasern, der Casein‐Wolle, den verschiedenartigen Kunstharzfasern besprochen. In engem Zusammenhang damit stehen die wirtschaftliche Bedeutung, Eigenschaften und Anwendung.
Einfluß der Größe und Dichte von Katalysatorkörnern auf die Aktivität technischer Hochdruckkatalysatoren
Authors: Reitz O.
Published: December 2004

Der Einfluß von Größe und Dichte der Körnung eines WS2‐ und eines Trägerkatalysators (WS2 + NiS auf akt. Tonerde) auf deren Aktivität bei der Druckhydrierung von Mineralölen wird unter verschiedenen Versuchsbedingungen untersucht und eine Mitbeteiligung der Oberflächendiffusion am Stofftransport in das Korninnere wahrscheinlich gemacht.
Neues Verfahren zur Kesselspeisewasseraufbereitung
Authors: Reichelt H.
Published: December 2004

Versuche führten zu zwei neuartigen Wasseraufbereitungs‐Verfahren, einer Entsalzung über Ammonium‐Anionen‐Austauscher und einer Bicarbonat‐Entsalzung. Bei letzterer wird ein Restsalzgehalt von 15 mg/1 erreicht, ohne daß erhebliche apparative Aufwendungen notwendig sind. Durch geeignete Regeneration liegen die Betriebskosten niedrig.
Die Niedrigbauweise für Kolonnenapparate
Authors: Warencke A.
Published: December 2004

Die Bauhöhe von Kolonnenapparaten läßt sich dadurch verringern, daß die Kolonnen unterteilt und die einzelnen Teile nebeneinander aufgestellt werden. An Ausführungsbeispielen wird gezeigt, daß sich dieses Verfahren auch bei Anlagen, die aus mehreren hohen Kolonnen bestehen, anwenden läßt.
Beitrag zur Fischer‐Tropsch‐Synthese an Eisen‐Kontakten (Teil I)
Authors: Kölbel Herbert , Ackermann Paul , Ruschenburg Ernst , Langheim Robert , Engelhardt Friedrich
Published: December 2004

Es werden Ergebnisse kontaktchemischer und reaktionsmechanistischer Untersuchungen aus eigenen Arbeiten mitgeteilt. Der Einfluß von Oberflächenentwicklung und Katalysatorzusammensetzung sowie die Rolle der Promotoren und der Eisencarbide und die bei der Herstellung von Fällungskatalysatoren auftretenden Fragen werden behandelt. Im zweiten Teil dieser Arbeit wird über Inbetriebnahme der Katalysatoren, ihr Verhalten in der Synthese und die Ergebnisse verschiedener Syntheseverfahren berichtet.
Stabilisation von Röntgenanlagen mit Hilfe von Eisenwasserstoff‐Widerständen
Authors: Kahovec L. , Treiber E.
Published: December 2004

Mit der hier beschriebenen Apparatur kann man vor allem für Feinstrukturuntersuchungen einfach und billig eine Stabilisation erreichen, die wirksamer ist als die Stabilisationseinrichtung einer fabrikmäßig hergestellten Röntgenanlage ausländischer Herkunft.
Zur Berechnung von Zähigkeit und Diffussion in flüssigen Suspensionen und verdichteten Gasen
Authors: Franck E. U.
Published: December 2004

Die von Maxwell und Rayleigh abgeleitete Gleichung zur Berechnung der elektrischen Leitfähigkeit binärer, heterogener Legierungen aus der Leitfähigkeit der Bestandteile wird auf die Zähigkeit als Impulsleitfähigkeit und auf die Diffusion in heterogenen Zweistoffsystemen angewandt. Sie geht bei starker Verdünnung des eingelagerten Partners praktisch in den Einstein schen Zähigkeitsansatz über. Es wird gezeigt, daß die Mischungsformel zur Berechnung der Viscosität sowohl von binären flüssigen Suspensionen bis zu mäßigen Konzentrationen als auch von komprimierten Gasen bis etwa zur halben Dichte der Flüssigkeit brauchbar ist. Mit gewissen Zusatzannahmen läßt sich auch die von Drickamer gemessene Selbstdiffusion im hochverdichteten Kohlendioxyd wiedergeben. Die Dichteabhängigkeit der Prandtl schen, Lewis schen und Schmidt schen Kennzahlen für Kohlendioxyd bei 40°C und bis 200 at wird dargestellt und diskutiert.
Leistungswerte neuerer Graphit‐Wärmeaustauscher
Authors: Vogel K.
Published: December 2004

An drei Wärmeaustauschern, dem Rohrbündel‐, dem Scheiben‐ und dem Schraubenrohrwärmeaustauscher aus Diabon‐Graphit wurden Wärmedurchgangsmessungen durchgeführt. Die spez. Übertragungsleistungen, ausgedrückt durch die Wärmedurchgangszahlen, liegen bei allen drei Baumustern sehr günstig. Zweck der Untersuchung sollte sein, dem anwendenden Ingenieur ein Bild von der Leistungsfähigkeit und Belastbarkeit einiger Graphit‐Wärmeaustauscher aus jüngster Entwicklung zu vermitteln.
Kontinuierliche Darstellung von Estern der salpetrigen Säure mit niederen aliphatischen Alkoholen
Authors: Spengler Günter , Hohn Hannsheinz
Published: December 2004

Es wird die Entwicklung und der Bau einer kontinuierlich arbeitenden Apparatur zur Darstellung von Estern der salpetrigen Säure mit niedrigen aliphatischen Alkoholen beschrieben. Technische Einzelheiten sowie Betriebsdaten werden angegeben

Das Verfahren sowie die Apparaturen waren Gegenstand von Patentanmeldungen.

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Luftreinigung durch Adsorption nach dem Sorbogen I‐Verfahren
Authors: Kahle Heinrich
Published: December 2004

Nachdem bereits über das Grundprinzip des Sorbogen‐I‐Verfahens berichtet wurde, soll hier seine Anwendung bei der Abscheidung von Wasser, Kohlendioxyd und Acetylen aus zu zerlegender Luft in einer Reinigungsanlage beschrieben werden. Die Anlage arbeitet mit Aktivkohle als Adsorbens bei Normaltemperatur und mäßig erhöhtem Druck und bildet den vorgeschalteten Teil einer Luftzerlegungsanlage. Das Verfahren bietet gegenüber älteren Anlagen wirtschaftliche Vorteile. Es wird ein Reinheitsgrad von einigen Hundertstel pM (1 pM = 1 ċ 10−4%) Kohlendioxyd und eine völlige Entfernung von Acetylen und Wasserdampf ohne zusätzlichen Energieaufwand erreicht.
Der Transport von Gasen und Dämpfen in Papier
Authors: Vollmer Wilfried
Published: December 2004

Der Transport von Gasen und Dämpfen in Papier wird unter Verwendung einer Strömungsmethode untersucht. Die für die Luftdurchlässigkeit maßgebenden Faktoren können auf bekannte Gesetze zurückgeführt werden, so daß man die Durchlässigkeit für jedes permanente Gas aus einer Messung der Luftdurchlässigkeit für einen beliebigen mittleren Druck berechnen kann. — Der Wasserdampftransport in Papier und Folien kann, sofern er nicht nach den bekannten Gesetzen durch das freie Porenvolumen vonstatten geht, unter Berücksichtigung von Adsorptionsisothermen quantitativ erfaßt werden. Aus den theoretischen und experimentellen Untersuchungen folgt, daß das Oberflächenkonzentrationsgefälle sowie die Oberflächenkonzentration selbst von maßgeblichem Einfluß sind. Es wird damit die Möglichkeit aufgezeigt, Aussagen über die Wasserdampfdurchlässigkeit unter allen praktisch vorkommenden klimatischen Bedingungen zu machen.
Kurzweg‐Fraktionierung
Authors: Utzinger Gustav Ed.
Published: December 2004

Es wird ein Verfahren und die zugehörige Apparatur für die kontinuierliche Kurzweg‐Fraktionierung beschrieben. Die Apparatur ist aus kontinuierlich abgestuften Elementen der einfachen Destillation zusammengesetzt und hat als wesentlichsten Bestandteil eine Heizwanne mit einem Temperaturgradienten. Die Leistungsfähigkeit des Verfahrens wird am Beispiel eines Zweistoffgemisches mit einer gewöhnlichen Fraktionierung aus einem Claisenkolben verglichen.
Die Wirkung der Magnus‐Kraft in laminaren Strömungen. I. Teil. Der Quertrieb in sedimentierenden Teilchenschüttungen
Authors: Tollert Hans
Published: December 2004

Es werden die Bedingungen für die Entstehung eines Quertriebs (Auftriebs), der von der Magnus‐Kraft herrührt, beschrieben und zunächst an sedimentierenden Teilchenschüttungen verschiedener Größe und verschiedenen Materials geprüft. Dabei wird die Zahl der sedimentierenden Teilchen im wandnahen Bereich mit der im achsennahen Bereich verglichen. Es ergab sich eine Anreicherung der Teilchen im achsennahen Bereich bis zu 25%. Bei sedimentierenden Schüttungen mit Teilchen zweier Größenklassen reichern sich dagegen die größeren im Strömungsmaximum bis zu 40% an.

Im II. Teil dieser Arbeit wird die Wirkung der Magnus ‐ Kraft in strömenden Elektrolytlösungen und Gasgemischen erörtert.
Registriergerät zur Bestimmung der Gasfeuchtigkeit
Authors: Ripka L. v.
Published: December 2004

Das Meßgerät zur laufenden Bestimmung der Gasfeuchtigkeit arbeitet nach dem Prinzip des Taupunktspiegels. Durch wechselweises Abkühlen und Erwärmen des Gerätes pendelt die Temperatur um den Taupunkt, wobei der Beginn des Beschlagens des Spiegels mit Feuchtigkeit durch einen Photozellenverstärker in einen Impuls umgewandelt wird, der die Temperaturmessung auslöst und die Heizung steuert.
Kunststoffe als korrosionsfeste Werkstoffe. Beispiele aus dem chemischen Apparatebau
Authors: Dammer Otto
Published: December 2004

Lebensdauer und Betriebssicherheit einer Apparatur aus Kunststoff hängen u. a. von der Korrosionsfestigkeit des Werkstoffes ab. Die Literaturangaben über die chemische Beständigkeit der Kunststoffe sind zum Teil noch unzureichend, insbesondere in bezug auf die zulässige Temperaturbeanspruchung. Erodierende Einflüsse treten bei Kurzzeitversuchen an Kunststoffapparaten nicht auf, dagegen später oft im Betrieb.
Temperaturverlauf und Wärmeverluste beim Anheizen und Abkühlen dickwandiger, kugelförmiger Behälter. Teil II. Der Abkühlungsvorgang. Gasgefüllte Behälter
Authors: Baehr H. D.
Published: December 2004

Nachdem im ersten Teil das Anheizen flüssigkeitsgefüllter Behälter behandelt wurde, werden nun der Temperaturverlauf und die Wärmeverluste beim Abkühlen derartiger Behälter berechnet. Dabei wird sowohl der Abkühlungsvorgang aus dem stationären Zustand heraus behandelt als auch der Fall, daß vor Erreichen des stationären Zustands die Wärmezufuhr im Innern des Behälters aufhört. Die Resultate für den Abkühlungsvorgang lassen sich ohne neue Schwierigkeiten aus den schon in Teil I gewonnenen Ergebnissen für das Anheizen herleiten. Es wird ferner das Anheizen und die Abkühlung gasgefüllter Behälter untersucht. Zwei Beispiele zeigen die Anwendung der gewonnenen Gleichungen und der daraus entwickelten Diagramme.