bluuebunny/crossref_metadata_2025 huggingface dataset:
Virus interactions with membrane filters
Authors: Cliver Dean O.
Published: December 2004

A survey of interactions of membrane filters with viruses has included 28 types of membranes, 4 types of enteroviruses, and 1 reovirus. Losses of these viruses in filtration, due to adsorption to the filter membranes, appear to be governed by three factors: the chemical composition of the filter membrane, the ratio of pore diameter to the diameter of the virus particle, and the presence of substances, such as those occurring in serum, which interfere with adsorption. Membranes of cellulose triacetate and of certain other materials have a very low affinity for these viruses. Cellulose triacetate filters adsorb virtually none when the pore size exceeds the virus diameter by a factor of more than 3. At porosities nearer the virus diameter, even low‐affinity membranes adsorb large quantities of virus unless serum or some other additive interferes. Cellulose nitrate membranes, in the absence of interfering substances, adsorb enterovirus significantly at a pore size 285 times the virus diameter.
The kinetics of β‐galactosidase attached to porous cellulose sheets
Authors: Sharp A. K. , Kay G. , Lilly M. D.
Published: December 2004

The properties of β‐galactosidase attached to cellulose and DEAE‐cellulose sheets arc described. Those insoluble enzyme derivatives obey the Michael‐Menten relationship but, the measured kinetic parameters are very dependent on the flow conditions. The results of long‐term stability tests are given.
Prediction of product formation as an aid to decision‐making in pilot plant experiments on batch fermentations
Authors: Gyllenberg H. G. , Koskenniemi Eeva , Rauramaa V.
Published: December 2004

A mathematical model for the prediction of product formation in batch processes is presented. The suggested procedure allows production of a prognose at any given moment of a run concerning the product concentration at any future moment of the same experiment. The series of subsequent prognoses thus produce a trend, and it is assumed that an analysis of the trend may provide information, which is useful in the evaluation of different decision alternatives in pilot plant batch experiments.
Growth of Streptococcus faecalus in dense culture
Authors: Sortland L. D. , Wilke C. R.
Published: December 2004

A fermentation system was designed and constructed to study the growth characteristics of microorganisms at low and high cell concentrations. The technique used to develop high cell densities utilized a rotating microfiltration unit to permit the removal of cell‐free product from the fermenter. The fermenter volume and the filter were contained in a single unit composed of a series of concentric cylinders. Annuli contained the fermenter volume while the second outermost cylinder supported a microfiltration membrane. Feed to the system was pumped at constant rates, and the internal pressure built up to a value, which would effect the required filtration rate. The system was operated batchwise and continuously with and without filtration.

The anaerobie growth characteristics of Streptococcus faccalus were determined at 37°C and pH 7.0 for batch, continuous, and continuous with filtration modes of operation. The growth characteristics were unchanged when the cell density was increased. Changes in cell yield peer model of glucose consumed were clearly illustrated during thee course of single run by operating the fermenter in the unsteady state with filtration. No consumption of glucose for developed was 40% packed cell volume, a value 45 times larger than could be grown in simple batch culture.
Performance of a perforated plate column as a multistage continuous fermentor
Authors: Kitai Atsuo , Tone Hiroshi , Ozaki Asaichiro
Published: December 2004

Microorganisms were continuously cultivated in multistage column consisting of ten perforated plate sections to which medium and air were supplied concurrently from the bottom.

At steady state the cell concentration in the various stages was gradationally differentiated from the bottom to the top in the direction of medium flow. RNA content per unit cell concentration at each sage was determined. The cells in the lower stages were higher in RNA content than those from the upper stages. Wash out was observed to occur in the column at dilution rates which do not result in wash out in a single stage chemostat system.

A study of the flow characteristics revealed that the overall performance of the plate column was equivalent to that of a multistage system, when hole diameter and hole area to column cross sectional area ratio were properly selected. This was true even in highly aerated conditions. These results indicated that the perforated plates in the column hindred intermixing through the plates, and that each stage functioned as an independent stirred vessel. Industrial and research application of this type fermentor was discussed.
Biopolymers in drug technology: The use of DNA in purifying Phleomycin
Authors: Pietsch Paul
Published: December 2004

It is sometimes easier and cheaper to extract a drug's target sites from cells than it is to purify, concentrate or manufacture the drug itself. This is especially true in the case of DNA and some of the exotic antibiotics that react with it. Phleomycin, an inhibitor of replication, was considered as a specific case in point. Biologically active components of this antibiotic mixture bind nondestructively to DNA, in vitro and in vivo, and thereafter may be processed by simple, economical methods usually reserved to macromolecules of much greater size.
The concentration of protein solutions by normal freezing
Authors: Janson Jan‐Christer , Ersson Bo , Porath Jerker
Published: December 2004

An apparatus is described which is designed for preparative freeze concentration experiments by the technique of normal freezing. It has a capacity of approximately 22 liters distributed over twelve vessels. The influence of various geometrical and chemical parameters such as stirring speed, crystallization rate, and sample composition on the normal freezing of protein solutions are discussed. For dilute protein solutions (<0.1%) the concentration factor generally was 8‐ to 10‐fold with recoveries of 90–100 percent. With higher protein concentrations and at ionic strengths higher than approximately 0.05, the recovery was decreased. No loss of activity was detected when concentrating enzyme solutions.
Covalent bond between the enzyme amyloglucosidase and a porous glass carrier: The effect of shearing
Authors: Weetall H. H. , Havewala N. B. , Garfinkel H. M. , Buehl W. M. , Baum G.
Published: December 2004

The utility of an immobilized enzyme depends not only on initial loading but also on operational half‐life. The loss of activity of an immobilized enzyme in a column reactor may occur in several ways. It is therefore of interest to determine whether the decay in activity is due to the rupture of any of the enzyme‐carrier bonds in the composite. In order to do this, it is first necessary to establish whether the enzyme on the composite is in fact covalently bound or adsorbed. In this report we have shown that there are a number of covalent links per protein molecule. We have also shown that the bond energies are sufficient to prevent shearing of the enzyme itself from the composite under any stresses which may occur in a chromatography column or packed‐bed reactor during continuous operation. The effect of the siloxane linkage on composite stability is also discussed.
Water insoluble enzyme columns: Kinetic study on steady state and transient conditions
Authors: Gellf G. , Thomas D. , Broun G. , Kernevez J. P.
Published: December 2004

The kinetic behavior of water insoluble enzyme columns was studied using the hydrolysis of GPNA (N‐glutaryl‐L‐phenylalanine‐p‐nitroanilide) by α‐chymotrypsin as a model. Thermal denaturation of soluble and insoluble enzyme was compared in a batch reactor and in a tubular reactor. Convection of metabolites, enzyme reaction, diffusion of metabolites across porous particles and the kinetic behavior of a water insoluble enzyme column were tested.

The respective and mutual effects of the first two phenomena were comprehensively analyzed for both stationary state and transient conditions. When the ingoing substrate concentration was varying with time, convection‐reaction equations were solved by digital computation. The possible effects of diffusion limitations and unstirred layers are discussed.
Study of performance of a tubular membrane reactor for an enzyme catalyzed reaction
Authors: Closset G. P. , Cobb J. T. , Shah Y. T.
Published: December 2004

A tubular membrane reactor offers many advantages over a solid wall reactor to carry out an enzyme catalyzed reaction. With proper membrane selectivity, the product, may be separated from the reacting stream and the enzyme recycled for continuous reuse. In most cases, enzyme reuse contributes to the economic feasibility of a continuous enzyme catalyzed process. Furthermore, the efficiency and performance of a membrane reactor is greater than that of a solid wall reactor.

Continuous hydrolysis of starch by the enzyme β‐amylase, carried out in a commercially available tubular membrane unit, is studied at different starch and enzyme concentrations for a given system pressure and inlet flow rate. Results show that the performance of the membrane reactor is in all cases greater than that of the solid wall reactor. A steady state in performance of permeation rate is, however, not reached by the membrane reactor, which shows a continuous decline within the periods examined in this study. This decline is caused in part by the aging of the starch solution, but mostly by the formation of a concentrated, or gel, layer at the membrane surface. This appears to be the main limiting factor for this process since the decline in reaction and permeation rate results in a severe decrease in the amount of maltose in the permeate.
Protein modification in nonaqueous media. Preparation and properties of matrix‐supported lysozyme
Authors: Bartling Greg J. , Brown Harry D. , Chattopadhyay Swaraj K.
Published: December 2004

Hen's egg white lysozyme (EC 3.2.1.17) has been covalently attached to a polystyrene matrix via interaction of protein nucleophiles with an aromatic imidazolide function under anhydrous conditions. The polymer‐enzyme complex is prepared in a way which allows nonaqueous solubilization of the complex. The activity of the bound enzyme compares favorably with the activity of the native protein. The pH optima for the matrix‐supported protein are shifted toward the basic side. The effect of substrate concentration on rate has been determined. (A preliminary report of this work has been published: G. J. Bartling, H. D. Brown, S. K. Chattopadhyay, Nature 243, 342–344 (1973).)
An immunoadsorbent process for removing hepatitis antigen from blood and plasma
Authors: Charm Stanley E. , Wong Bing L.
Published: December 2004

An immunoadsorbent process has been devised for removing serum hepatitis antigen (HAA), from blood, blood plasma, and plasma products.

The immunoadsorbent complexes specifically with HAA and the complex is removed from the plasma by filtration. The complex is dissociated with 0.23M NH4OH. The immunoadsorbant is regenerated for further processing, while the purified HAA by‐product my be used to produce more antibody in animals.

The rate of complexing is such that HAA is reduced one log cycle each 2hr. Since available tests can only detect HAA to about 109 particles per ml, it is proposed that HAA negative plasma and plasma products can be processed to reduce HAA to a probability of less than one HAA particle per plasma pool.

A gibbon injected with infectious commercial Factor IX that was subjected to the immunoadsorbent process showed no sign of infection after 8 months. However 14 weeks after injection with unprocessed Factor IX, the gibbon showed signs of infection.
Design and operational model for complete mixing activated sludge system
Authors: McKinney Ross E.
Published: December 2004

The complete mixing activated sludge (CMAS) system is gaining in popularity for treating both domestic and industrial wastewaters. Experience over the past 20 years has produced a simple mathematical model which can be used in both the design and the operational evaluation of CMAS systems. Laboratory pilot plants and full scale field units have furnished the basic data needed to confirm the validity of the mathematical model. The basic concepts of the model are discussed in light of field evaluations. Areas of conflict and confusion which have arisen in the past will be presented and discussed. Design examples and operational evaluations are presented for several different wastewater systems.
Kinetics studies in a continuous steady state hollow fiber membrane enzyme reactor
Authors: Davis James C.
Published: December 2004

Porous hollow cellulose fibers have been used to separate a nonflowing enzyme solution of alkaline phosphatase from a continuous flow of substrate. The porosity of the hollow fiber membrane allows the substrate and product to diffuse freely through the membrane while restricting the permeation of the enzyme. The resulting “immobilized” enzyme system has been shown to behave as a continuous reactor—converting p‐nitrophenylphosphate to p‐nitrophenol. By varying the concentrations, flow rate, etc., either diffusion or enzyme kinetics can be studied. The continual influx of product and removal of substrate at steady state allows the study of kinetics of relatively short half‐life enzymes and unstable systems.
An enzyme rate equation for the overall rate of reaction of gel‐immobilized glucose oxidase particles under buffered conditions. I. Pseudo‐one substrate conditions
Authors: Atkinson B. , Lester D. E.
Published: December 2004

The overall rate of reaction of buffered gel‐immobilized glucose oxidase particles is described by means of an enzyme rate equation which relates the overall reaction rate of a particle to the free solution characteristics of the enzyme, the effective diffusivity of the limiting substrate in the gel, the characteristic particle size, and the limiting substrate concentration adjacent to the gel surface. This equation accounts quantitatively for the limitation of the overall rate of reaction by substrate diffusion, and it is used to illustrate the influence of the system parameters, i. e., particle size, enzyme concentration, and pH, on the extent of the diffusional resistance associated with gel‐immobilized glucose oxidase particles.

The enzyme rate equation is generally applicable to those enzymes whose kinetics approximately follow Michaelis‐Menten form when in free solution.
Simple system for controlling dissolved oxygen concentration in laboratory fermentors
Authors: Fuchs Renato , Wang Daniel I. C.
Published: December 2004

A simple system for the control of oxygen transfer in laboratory fermentation units has been devised. This system employs pure oxygen to elevate the driving force for oxygen transfer. In addition, the aeration is controlled in a closed loop manner in order to minimize total exit flow of the gas from the fermentor. Fermentation study using Bacillus stearothermophilus grown on n‐dodecane at 55°C illustrates excellent carbon recovery as well as the ease of controlling oxygen transfer.
Studies on immobilized trypsin in high concentrations of organic solvents
Authors: Weetall Howard H. , Vann William P.
Published: December 2004

Trypsin was covalently immobilized on porous glass in the presence and absence of a specific substrate and reacted in various organic solvents of different dielectric constants. Optimum solvent concentration, pH profile, Km(app), Vmax(app), productivity versus temperature, activity, and reaction rates were determined. Reaction rates of six lysyl dipeptides were compared. Crystalline trypsin was dansylated for studies by nanosecond fluorescence techniques to determine the effects of introducing high concentrations of organic solvents on the molecule. The results indicated that greater reaction rates were observed with dipeptides having more acidic carboxyl terminal groups. The data also indicated that greater reaction rates were observed in higher concentrations of solvents of lower dielectric constants. Nanosecond fluorescence spectroscopy of trypsin in high concentrations of a low dielectric constant solvent indicated major dehydration even though maximal enzyme‐activity was achieved under these conditions.
Maximization of steady‐state Bacterial production in a chemostat with pH and substrate control
Authors: Spitzer David William
Published: December 2004

This analytical study deals with the steady‐state behavior and control of microbial growth in continuous cultures. A second order Haldane‐Monod model of continuous cultures is used as a basis for study of the effects of the adjustment of pH by the addition of acidic (or basic) materials. The treatment of a hydrogen ion concentration, in addition to substrate and microbial concentrations as state variables, results in a third order system of equations describing the process.

The analysis of the system in equilibrium yields several admissible steady states, that is, steady states which satisfy all constraints. An optimal control problem is formulated and subsequently solved to maximize steady‐state microbial production.
Parameters in the construction of an immobilized dual enzyme catalyst
Authors: Bouin James C. , Atallah Mokhtar T. , Hultin Herbert O.
Published: December 2004

The glucose oxidase and catalase activities immobilized to the γ‐aminopropyltriethoxysilane derivative of nickel‐impregnated silica alumina was controlled by several factors. The most important of these was enzyme concentration. In constructing the dual immobilized enzyme catalyst, competition between the two enzymes for available binding sites was observed. The order of addition of the various reactants during immobilization was also important. Higher glucose oxidase activities were immobilized when glutaraldehyde was added concurrently with the enzyme, while maximal coupling of catalase occurred if glutaraldehyde was first added to react with the amino derivative of the silica alumina support, excess reagent washed away, and then the catalase added. Bovine serum albumin, which aids in the crosslinking of glucose oxidase, hindered the coupling of the enzyme to the support particles.
Influence of pH and temperature on the substrate yield coefficient of yeast growth in a chemostat
Authors: Eroshin V. K. , Utkin I. S. , Ladynichev S. V. , Samoylov V. V. , Kuvshinnikov V. D. , Skryabin G. K.
Published: December 2004

The influence of pH and temperature on the substrate yield coefficient for growth of Saccharomyces cerevisiae in a chemostat under limited organic substrate conditions was studied.

Mathematical analysis of the substrate yield coefficient as a function of pH and temperature in the near‐optimal area was made. It was shown that the location of pH and temperature optima were independent of each other. The maximum substrate yield coefficient had the following coordinates: pH = 4.1, temperature = 28.5°C.
Influence of salts and gelatin on disintegration of Saccharomyces cerevisiae by freeze‐pressing
Authors: Magnusson K.‐E. , Edebo L.
Published: December 2004

The disintegration by freeze‐pressing of a low concentration of Saccharomyces cerevisiae suspended in aqueous solutions of gelatin and different salts has been studied at different temperatures. In the freeze‐pressing process deionized water and salt solutions flow in pulses, whereas samples with increasing concentrations of gelatin or cells tend to flow more smoothly. This smooth flow enhances the disruption efficiency particularly at lower temperatures, which seems to be of great practical importance. The addition of salts also promotes disintegration. The presence of both gelatin and salts works antagonistically on disintegration presumably because of different modes of action at disruption of cells.
Feather protein as a support for immobilizing enzymes
Authors: Stanley W. L. , Watters G. G. , Chan B. G. , Kelly S. H.
Published: December 2004

Feather meal protein was prepared in granular form and used as a support for lactase using glutaraldehyde as the crosslinking agent. The support gave a high retention of activity and in column operation it yielded apparent half‐lives from 50 to 100 days. Because of its gel‐like consistency (water content of about 90%), there is some diffusional restricting of activity as indicated by the kinetic data of soluble and immobilized enzymes.
Application of dynamic calorimetry for monitoring fermentation processes
Authors: Mou Duen‐Gang , Cooney Charles L.
Published: December 2004

The rate of heat evolution (kcal/liter‐hr) in mycelial fermentations for novobiocin and cellulase production with media containing noncellular solids was measured by an in situ dynamic calorimetric procedure. Thermal data so obtained have proved significant both in monitoring cell concentration during the trophophase (growth phase) and in serving as a physiological variable in the fermentation process. The validity of this technique has been demonstrated by closing the overall material and energy balances.

The maintenance energy in a batch fermentation can also be calculated by integrating heat evolution data. This integration method is applicable to a fermentation lacking a precise cell growth curve. The maintenance coefficient, obtained for the novobiocin fermentation by Streptomyces niveus, is equal to 0.028 g glucose equivalent/g cell‐hr. The production of novobiocin in the idio‐phase (production phase) also correlates well with the amount of energy catabolixed for maintenance and this results in an observed conversion yield of glucose to novobiocin of 11.8 mg of novobiocin produced per gram of glucose catabolized.

A new physiological variable, kilocalories of heat evolved per millimole of oxygen consumed, has been proposed to monitor the state of cells during the fermentation. This method may provide a simple way to monitor on‐line shifts in the efficiency of cell respiration and changes in growth yields during a microbial process.
Physical characteristics of porous cellulose beads as supporting material for immobilized enzymes
Authors: Chen Li Fu , Tsao George T.
Published: December 2004

Cellulose beads prepared in this report have high porosity (75–80%) and evenly distributed pores. The pore size is about 1000 Å. The cellulose beads are physically strong and contain large amounts of reactive groups, making them suitable for use as carriers for immobilized enzymes.
Heat transfer coefficients and two‐phase dispersion properties in a stirred‐tank fermentor
Authors: Pollard R. , Topiwala H. H.
Published: December 2004

Experiments were performed in a pilot scale 0.30 m3 conventional stirred‐tank fermentor using water, air/water, and air/K2SO4 solutions. Both single‐ and two‐stage impeller systems were investigated. Overall and tank‐side coefficients for heat transfer from a 0.012 m diameter coil were measured for a range of impeller speeds and superficial gas velocities. Power input, bubble size, and gas hold‐up were also determined. An analysis of the experimental results indicates that previously published correlations for single‐phase heat transfer in stirred tanks (of the type: Nu = C(Re)α(Pr)β) are not applicable for single‐ or multiimpeller gas/liquid systems. The introduction of air alters the mixing pattern significantly, affecting both average and local tank‐side heat transfer coefficients. Power input and gas hold‐up are suggested as the major correlating parameters for the determination of tank‐side heat transfer coefficients.
Application of polylysine bound succinyl‐NA to a membrane reactor
Authors: Yamazaki Y. , Maeda H. , Suzuki H.
Published: December 2004

The amide bond at N‐6 in succinyl‐NAD was found to be more stable than in former accounts. Succinyl‐NAD was coupled on polylysine to give a new polymer derivative of NAD, which retained at least 85% of the initial coenzymic activity even after dialysis for one week. The polymer derivative of NAD could be applied to a membrane reactor containing alcohol dehydrogenase and lactate dehydrogenase and lactate was continuously produced in a half‐life of ten days.
Analysing the factors influencing clean technology adoption: a study of the Spanish pulp and paper industry
Authors: del Río González Pablo
Published: January 2005

Technological change has a relevant role to play in the transition towards a sustainable industry. However, slow diffusion of clean technologies can be observed in OECD countries. The analysis of the determinants and barriers to clean technology adoption should be a main goal of economists and social scientists. This paper shows that three sets of interrelated factors prevent but also stimulate the widespread adoption and diffusion of clean technology: these are factors external and internal to the firm, conditions of the potential adopters and characteristics of the environmental technology. These factors are included in the so‐called ‘triangular model’, which is further applied to the analysis of clean technology adoption in the pulp and paper industry in Spain. The empirical study shows that clean technology adoption decisions are the result of an interaction between these factors, often involving contradictory signals for the potential adopter. The paper closes with some public policy recommendations for the effective and efficient promotion of clean technology diffusion. Copyright © 2005 John Wiley & Sons, Ltd and ERP Environment.
Reduced mitotic activity at the periphery of human embryonic stem cell colonies cultured in vitro with mitotically‐inactivated murine embryonic fibroblast feeder cells
Authors: Heng Boon Chin , Cao Tong , Liu Hua , Rufaihah Abdul Jalil
Published: January 2005

This study attempted to investigate whether different levels of mitotic activity exist within different physical regions of a human embryonic stem (hES) cell colony. Incorporation of 5‐bromo‐2‐deoxyuridine (BrdU) within newly‐synthesized DNA, followed by immunocytochemical staining was used as a means of detecting mitotically‐active cells within hES colonies. The results showed rather surprisingly that the highest levels of mitotic activity are primarily concentrated within the central regions of hES colonies, whereas the peripheral regions exhibited reduced levels of cellular proliferation. Two hypothetical mechanisms are therefore proposed for hES colony growth and expansion. Firstly, it is envisaged that the less mitotically‐active hES cells at the periphery of the colony are continually migrating outwards, thereby providing space for newly‐divided daughter cells within the more mitotically‐active central region of the hES colony. Secondly, it is proposed that the newly‐divided hES cells within the central region of the colony somehow migrate to the outer periphery. This could possibly explain why the periphery of hES colonies are less mitotically‐active, since there would obviously be an extended time‐lag before newly‐divided daughter cells are ready again for the next cell division. Further investigations need to be carried out to characterize the atypical mechanisms by which hES colonies grow and expand in size. Copyright © 2004 John Wiley & Sons, Ltd.
Large pKa Shifts of α‐Carbon Acids Induced by Copper(II) Complexes
Authors: Zhong Zhenlin , Postnikova Brenda J. , Hanes Robert E. , Lynch Vincent M. , Anslyn Eric V.
Published: December 2004

A series of synthetic receptors (4–6) incorporating metal ions, specifically copper(II), were examined for their ability to enhance the acidity of active methylene compounds. The copper(II) complexes were observed to reduce the pKa of 1,3‐diketone carbon acids in acetonitrile by as much as 12 pKa units. The relatively large pKa reduction achieved by the complex is attributed to the electrostatic interaction between the anionic π system of the enolate and the copper(II) ions. The cage structure and hydrogen bonding sites in receptors 4 and 5 lead to a very modest further enhancement of the acidity relative to that with 6. This study provides insight into the way in which metalloenzymes stabilize an enolate intermediate.
Enhanced Stabilization of Reverse Micelles by Compressed CO2
Authors: Shen Dong , Han Buxing , Dong Yu , Wu Weize , Chen Jiawei , Zhang Jiangling
Published: December 2004

The effect of compressed CO2 on the solubilization capacity of water in reverse micelles of sodium bis(2‐ethylhexyl) sulfosuccinate (AOT) in longer chain n‐alkanes was studied at different temperatures and pressures. It was found that the amount of solubilized water is increased considerably by CO2 in a suitable pressure range. The suitable CO2 pressure range in which the solubilization capacity of water could be enhanced decreased with increasing W0 (water‐to‐AOT molar ratio). The microenvironments in the CO2‐stabilized reverse micelles were investigated by UV/Vis adsorption spectroscopy with methyl orange (MO) as probe. The mechanism by which the reverse micelles are stabilized by CO2 is discussed in detail. The main reason is likely to be that CO2 has a much smaller molecular volume than the n‐alkane solvents studied in this work. Therefore, it can penetrate the interfacial film of the reverse micelles and stabilize them by increasing the rigidity of the micellar interface and thus reducing the attractive interaction between the droplets. However, if the CO2 pressure is too high, the solvent strength of the solvents is reduced markedly, and this induces phase separation in the micellar solution.
Löslichkeit von Kohlenwasserstoffen verschiedenen Typs in Methanol und Benzylalkohol
Authors: Sieg Lothar
Published: December 2004

Im Laufe von Untersuchungen über die Phasengleichgewichte in ternären und polynären Systemen war es notwendig, die Löslichkeit von Kohlenwasserstoffen in Methyl‐ und Benzylalkohol zu untersuchen. Außer Gesichtspunkten allgemeiner Natur spielte bei dieser Arbeit auch die Erwägung eine Rolle, gegebenenfalls neue analytische und präparative Möglichkeiten zu gewinnen.
Wirbelschicht‐Röstverfahren der Badischen Anilin‐ & Soda‐Fabrik
Authors: Johannsen Adolf
Published: December 2004

Nachstehend wird über eine neuere Anwendung des Winklerschen Wirbelschicht‐Verfahrens berichtet. Während der Nachkriegsjahre in den Betrieben der Badischen Anilin‐ & Soda‐Fabrik durchgeführte Entwicklungsarbeiten haben ergeben, daß das Wirbelschicht‐Verfahren sehr gut geeignet ist für die Gewinnung hochprozentiger Röstgase durch Abrösten von feinstückigen oder feinkörnigen Schwefelkiesen.
Inhaltsbestimmung teilweise gefüllter Flüssigkeitsbehälter
Authors: Schulze‐Bahr G.
Published: December 2004

Es wird der Zusammenhang zwischen dem Höhenverhältnis und dem Füllungsverhältnis für verschiedene Behälterformen, besonders für liegende Zylinder, erörtert und in zwei Nomogrammen dargestellt.
Probleme des konvektiven Stofftransports bei der Elektrolyse
Authors: Ibl N.
Published: December 2004

Die Vorgänge des Stofftransports (elektrische Wanderung, Diffusion, Konvektion) führen auch bei der Elektrolyse zu Konzentrationsunterschieden in der Nähe der Elektrodenoberfläche und im Innern der Lösung und bestimmen dadurch die Größe des Grenzstromes, der ein Maß für die maximale Geschwindigkeit ist, mit der ein elektrochemischer Prozeß bei gegebenen Rührbedingungen ausgeführt werden kann. Mit Hilfe der Dimensionsanalyse und der Grenzschichttheorie der Hydrodynamik lassen sich für besonders einfache Fälle diese Daten berechnen bzw. abschätzen, wie an Beispielen gezeigt wird.
Die technische Bedeutung der Abscheidespannung bei der elektrolytischen Gewinnung von Wasserstoff und Sauerstoff
Authors: v. Pichler Alarich
Published: December 2004

Die Abscheidespannung, die ein Maß für die bei der Elektrolyse aufgewandte elektrische Arbeit ist, läßt sich durch verschiedene technische und konstruktive Maßnahmen herabsetzen, wie an Beispielen gezeigt wird. Außerdem werden die wärmetechnischen Verhältnisse in der Elektrolysenzelle diskutiert.
Verwertung des bei Chloralkali‐Elektrolysen anfallenden Wasserstoffs zur Ammoniak ‐ Erzeugung
Authors: Hinrichs H. , Niedetzky J.
Published: December 2004

Die Österreichischen Stickstoffwerke haben in Schweden eine Anlage errichtet, in der Ammoniak aus dem bei einer Chloralkali‐Elektrolyse anfallenden Wasserstoff gewonnen wird. Bei einer Tageskapazität von 5 bis 15 †; Ammoniak arbeitet die Anlage bisher sehr wirtschaftlich, eine erhebliche Erweiterung wurde bereits ausgeführt.
Verfahrensgrundlagen der Stadt‐ und Ferngasentgiftung
Authors: Gross H. W.
Published: December 2004

Die Abhängigkeit des erreichbaren End‐Kohlenoxyd‐Gehaltes von Reaktionstemperatur und Wasserdampfgehalt bei der Konvertierung des Kohlenoxyds mit Wasserdampf wird erläutert. Die optimalen Reaktionsbedingungen lassen sich bei der Gasentgiftung, besonders bei der Behandlung der kohlenoxyd‐reichen Benzin‐ und ölspaltgase nicht immer anwenden, doch wird auch hier mit 3 bis 5% Rest‐Gehalt an Kohlenoxyd noch eine ausreichende Teilentgiftung erzielt. Die Konvertierung von heißen, noch ausreichend Wasserdampf enthaltenden Rohgasen bringt eine erhebliche Kostenersparnis, die durch die Kombination von Konvertierung und Schwefelwasserstoffwäsche in einer Anlage noch vergrößert werden kann.
Neuartiger Redoxtitrations‐Automat
Authors: Boldt Peter , Lackner Helmut
Published: December 2004

Zur Bestimmung von Redoxpotentialen organischer Verbindungen wurde ein Titrierautomat entwickelt. Dieser unterscheidet sich von den üblichen Titrierautomaten dadurch, daß neue Titrationslösung immer erst dann zugegeben wird, wenn sich das Gleichgewichtspotential sicher eingestellt hat. Dies wird durch einen Abfrage‐Regelvorgang erreicht, der sich periodisch wiederholt, bis die gesamte Titrationskurve aufgezeichnet ist. Die Apparatur arbeitet zuverlässig und ist außerdem billig, gut nachzubauen und leicht zu bedienen.
Erhöhen des Durchsatzes von Extraktionskolonnen durch elektrische Beeinflussung
Authors: Kneule F. , Nemec J.
Published: December 2004

Durch Einwirken elektrischer Felder läßt sich die Trennzeit stabiler Emulsionen verkürzen und somit die Raum‐Zeit‐Ausbeute von Extraktionsanlagen erhöhen. Die Anwendungsmöglichkeiten des Verfahrens beschränken sich auf Phasensysteme, bei denen die in einem flüssigen Dielektrikum dispergierte Phase elektrisch leitend ist.
Fortschritte auf dem Gebiet der Elektronenmikroskopie. Bericht über die 11. Tagung der Deutschen Gesellschaft für Elektronenmikroskopie
Authors: Speidel R.
Published: December 2004

Die 11. Tagung der Deutschen Gesellschaft für Elektronenmikroskopie wurde dieses Jahr gemeinsam mit der Sektion Elektronen‐Optik und Mikroskopie des Schweizerischen Komitees für Optik vom 22. bis 26. September in Zürich abgehalten. In den vier Tagen wurde eine Fülle physikalischer Probleme und Ergebnisse diskutiert. Dieser Bericht beschränkt sich jedoch auf die Entwicklung der Geräte und Präparationstechniken, die für den Techniker und Anwender der Elektronenmikroskopie von Bedeutung sind.
Zur Theorie der Elektroosmose
Authors: Schmid Gerhard
Published: December 2004

Die klassische Theorie der Elektroosmose von Helmholtz und v. Smoluchowski, die aus der Vorstellung einer elektrischen Doppelschicht an der inneren Phasengrenze der Porenwandungen abgeleitet ist, versagt bei der Anwendung auf Membranen. Die neue Theorie betrachtet vielmehr die feinporigen Kapillarsysteme der Membranen in erster Näherung als homogene Elektrolyte, in denen sich teils bewegliche (austauschbare), teils unbewegliche (an die Matrix der Membran gebundene) Ionen befinden. Man wird dadurch unabhängig von der Annahme einer bestimmten Porenstruktur der Membran und gewinnt Ansätze, die auch die elektrische Leitfähigkeit und das Dialysepotential mit den elektroosmotischen Erscheinungen in Zusammenhang bringen.
Mikromanometer hoher Empfindlichkeit
Authors: Elgeti K. , Eckert E. R. G.
Published: December 2004

Zum Ausmessen von Geschwindigkeitsfeldern in laminarer Strömung von Gasen wurde ein empfindliches Mikromanometer entwickelt, das eine Meßgenauigkeit von 3 · 10−5 mmWS oder — bei größeren Druckdifferenzen — von 0,5% hat. Der Meßbereich beträgt etwa 2,5 mmWS. Das Gerät arbeitet nach dem U‐Rohr‐Prinzip mit elektrischer Anzeige der Flüssigkeitshöhe. Es liefert Gleichspannung, und zwar bei der verwendeten Manometerflüssigkeit etwa 0,51 V je mm WS Druckdifferenz.
Erfahrungen mit Membranpumpen und Membranverdichtern
Authors: Schopenhauer H.
Published: December 2004

Die Verwendung von Membranpumpen und ‐kompressoren ist nicht neu, doch konnten größere Betrebserfahrungen mit diesen Maschinen erst in den letzten Jahren gesammelt werden. Bestimmte Schäden lassen sich durch konstruktive Maßnahmen vermeiden, so z. B. das Hängenbleiben oder die Beschädigung der Membran und das Auftreten von Kompressionsschlägen, wenn ein Membranverdichter als Gasumwälzverdichter betrieben wird.
Ein Verfahren zur Oxidation von Alkylaromaten
Authors: Katzschmann E.
Published: December 2004

Ein Verfahren der Chemischen Werke Witten zur Herstellung von Terephthalsäure‐dimethylester durch Luftoxidation von p‐Xylol in flüssiger Phase hat in der Industrie eine beachtliche Bedeutung erlangt. Es wird die Entwicklung des Verfahrens beschrieben. Aus dem Reaktionsablauf wurden neue Erkenntnisse über den Oxidationsmechanismus gewonnen. Charakteristische Zwischenprodukte sind der p‐Toluylsäure‐methylester und der Terephthalsäure‐monomethylester.
Elektrochemische Eigenschaften gespülter Gas‐Diffusionselektroden
Authors: Wendtland R. , Winsel A.
Published: December 2004

In den Poren von Gas‐Diffusionselektroden werden durch Elektro‐Dialyse Konzentrationsverschiebungen verursacht, die in alkalischer Lösung zu Grenzstromdichten in Wasserstoff‐Anoden führen. Auch in Sauerstoff‐Kathoden wirkt sich die Konzentrationserhöhung in den Poren ungünstig auf die Polarisation aus. Man kann derartige Polarisationseffekte durch Spülung der Elektrodenporen mit frischer Elektrolytlösung vollständig beseitigen. Es wird über Meßergebnisse an gespülten Sauerstoff‐ und Wasserstoff‐Elektroden berichtet.
Elektrochemische Untersuchung des Stoffübergangs von einer Flüssigkeit an eine gasende Düse
Authors: Weder Erich
Published: December 2004

Mit einer elektrochemischen Meßmethode wurde der Stoffübergang von einer Flüssigkeit an eine horizontale Platte, in deren Zentrum sich eine einzelne gasende Düse befand, untersucht. Die Platte bestand aus 11 konzentrisch um die Düse angeordneten, elektrisch gegeneinander isolierten Nickel‐Ringen, an deren Stirnflächen sich die elektrochemische Meßreaktion abspielte. Mit dieser Sonde konnte der Stoffübergang als Funktion des Gasdurchsatzes sowie des Abstandes vom Düsenmittelpunkt gemessen werden. Mit einem Schnellschreiber wurde die Änderung des Stoffübergangs‐Koeffizienten mit der Blasenbildung aufgezeichnet. Durch gleichzeitiges Photographieren der Blasen erhielt man die Zuordnung Stoffübergang–Blasenwachstum.
Potentiometrische Bestimmung des Wasserdampf‐Dissoziationsgleichgewichtes zwischen 1000 und 1300°K mit einer Festelektrolytzelle
Authors: Hartung R. , Möbius Habil. H.‐H.
Published: December 2004

Nachdem die Fehlerquellen (verschiedene Eigenschaften des Festelektrolyten und der Elektroden, Einflüsse der Gasströmung und Mängel im Temperaturausgleich) bei potentiometrischen Bestimmungen an H2/H2O/Inertgas‐Gemischen durch Vorversuche erkannt waren, wurde die Konstante des Wasserdampf‐Dissoziationsgleichgewichts zwischen 1000 und 1300°K direkt elektrochemisch bestimmt, wobei die Genauigkeit der bekannten, unter Benutzung der Bildungswärme sowie spektroskopischer Daten indirekt erhaltenen Werte nahezu erreicht werden konnte. Die Wasserstoff‐ und Wasserdampf‐Bestimmungen zeigten, daß die gaspotentiometrische Methode unter optimalen Bedingungen gestattet, das Verhältnis P/P über den Bereich von etwa 10−5 bis 105 mit einer absoluten Genauigkeit von ⩽ 3% kontinuierlich zu messen.
Transportprozesse und thermische Instabilitäten bei porösen Katalysatoren
Authors: Hugo P. , Wicke E.
Published: December 2004

Zwei bis heute noch nicht vollständig gelöste Probleme werden behandelt: die Diffusion von Gasen in porösen Medien im Übergangsbereich zwischen Gas‐ und Knudsen‐Diffusion und die thermischen Instabilitäten einzelner Katalysatorkörner bei stark exothermen Umsetzungen. Die Porendiffusion wird mit einer neuen Methode untersucht, die auf der Selbstdiffusion von Wasserstoff in Mischungen von ortho‐ und para‐Wasserstoff beruht. Die Zusammenhänge zwischen der Druck‐ und Temperaturabhängigkeit der effektiven Diffusionskoeffizienten und der Porenstruktur der untersuchten Materialien werden diskutiert. Beim zweiten Problem werden zunächst die experimentellen Erfahrungen zusammengestellt. Sie führen zu dem Schluß, daß Instabilitäten allein im Korninnern, wie sie theoretisch vorausgesagt wurden, praktisch nicht auftreten können. Mit einer erweiterten Theorie, welche außer der bei exothermen Reaktionen auftretenden inneren Kornüberhitzung den äßeren Wärme‐ und Stoffübergang berücksichtigt, läßt sich zeigen, daß für die thermischen Instabilitäten die Bedingungen des äußeren Wärmeübergangs ausschlaggebend sind. Die zusätzliche innere Kornüberhitzung steigert dabei die parametrische Empfindlichkeit des Systems.
Normung aus der Sicht des chemischen Apparatebaues
Authors: Winter J.
Published: December 2004

Unter dem Blickwinkel des Apparatebauers wird gezeigt, welche wirtschaftlichen Vorteile die bestehenden Apparatebau‐Normen bringen und welche Schwierigkeiten Normen insbesondere bei Angeboten für das Ausland verursachen können. Es gibt viele gute Werknormen, aber sie ermöglichen immer noch zu viele Variationen bei den Konstruktionen des Apparatebaues, wodurch die Fertigung von Serien und Wiederholteilen erschwert wird. Eine Normung, die der technischen Entwicklung entspricht, führt zu echter Kostensenkung.
Thermodynamische Bewertung chemischer Prozesse
Authors: Rant Z.
Published: December 2004

Durch Ergänzen der bisher üblichen quantitativen Betrachtungen durch qualitative Überlegungen läßt sich ein tieferer Einblick in das Wesen der bei chemischen Prozessen auftretenden Energieumformungen erhalten. Zu diesem Zweck werden die Energieströme in zwei Teile zerlegt, von denen der eine die beliebig umformbaren Energien, die Exergie, und der andere den Rest, die Anergie, darstellt. Aufgrund solcher Überlegungen werden die bei den Energietransformationen auftretenden Nichtumkehrbarkeiten nach Größe und Ort ermittelt und ein exergetischer Wirkungsgrad definiert. Dieser ist ein eindeutiges Maß für die energetische Güte des Prozesses. Das Verfahren wird an einigen Beispielen erläutert.
Schlammentwässerung mit Preßfiltern
Authors: Alt Christian
Published: December 2004

Preßfilter sind für die Verminderung der Restfeuchte bei bestimmten Filterkuchen geeignet. Mehrere diskontinuierliche und kontinuierliche Apparate und Maschinen haben sich zum Teil bewährt, andere befinden sich noch in der Erprobung. Nach einer kurzen theoretischen Behandlung, die einige Schlüsse für die verfahrenstechnischen Forderungen zuläßt, werden die Funktionen der wichtigsten Entwicklungen beschrieben und zusammenfassend deren typische Verhaltensweisen herausgestellt.
Is high‐dose intensity intraarterial cisplatin chemoradiotherapy for head and neck carcinoma feasible?
Authors: Robbins K. Thomas
Published: January 2005

The author outlines his personal experience treating hundreds of patients with head and neck carcinoma using combined high‐dose intraarterial cisplatin chemotherapy and concomitant, radiation therapy, and he also highlights the published experience of other investigators, all of whom concluded that the high‐dose intensity approach is feasible and highly efficacious. This differs from the results reported in this issue by a group of investigators from the Mayo Clinic.

See referenced original article on pages 559–68, this issue.
Reactions of K2[Fe(CO)3(PPh3)]: Reductive Sb−Sb Coupling with Ph2SbCl To Form trans‐[Fe(CO)3(PPh3)(Sb2Ph4)] and Salt Metathesis with Me3SbCl2 To Yield trans‐[Fe(CO)3(PPh3)(SbMe3)]
Authors: Lorenz Ingo‐Peter , Rudolph Stefan , Piotrowski Holger , Polborn Kurt
Published: December 2004

In contrast to the ferrate K2[Fe(CO)4], the phosphane‐substituted ferrate K2[Fe(CO)3(PPh3)] (1) reacts with the stibane derivative Ph2SbCl by metal‐assisted reductive Sb−Sb coupling to give the distibane complex trans‐[Fe(CO)3(PPh3)(Sb2Ph4)] (3). The distibane ligand in 3 is terminally η1‐coordinated trans to the phosphane ligand. However, the stiborane derivative Me3SbCl2 reacts with 1 in a metathetical substitution reaction to form the monostibane complex trans‐[Fe(CO)3(PPh3)(SbMe3)] (5). Both compounds have been characterized by spectroscopic (IR, NMR, MS), analytical (C, H) and X‐ray diffraction analyses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Oxidation of a One‐Dimensional Coordination Polymer and Synthesis of the Macrocyclic Silver Complex [Ag12(PhS2P−PS2Ph)6(dppeS)6]
Authors: Fenske Dieter , Rothenberger Alexander , Fallah Maryam Shafaei
Published: December 2004

The cluster chemistry with functionalised trimethylsilyl reagents was investigated. The oxidation of the one‐dimensional coordination polymer 1/∞[{Ag2(PhS2P−PS2Ph)dppe}·dppe]∞ leads to the formation of [Ag12(PhS2P−PS2Ph)6(dppeS)6] (dppeS = Ph2P(CH2)2P(S)Ph2]. The dianionic ligand [PhPS2−PS2Ph]2− could possibly give rise to a new class of macrocyclic transition‐metal chalcogenides. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Approximate iterative methods for variational data assimilation
Authors: Lawless A. S. , Gratton S. , Nichols N. K.
Published: December 2004

The problem of four‐dimensional variational data assimilation can be considered as a non‐linear least squares problem. A common method for solving it is equivalent to a Gauss–Newton method. However, approximations must be made in order to solve the problem efficiently. In this paper we examine two approximations to the Gauss–Newton method and their effect on the data assimilation problem. Copyright © 2004 John Wiley & Sons, Ltd.
Intracellular pH regulation in rat Schwann cells
Authors: Nakhoul Nazih L. , Abdulnour‐Nakhoul Solange , Khuri Raja N. , Lieberman Edward M. , Hargittai Pal T.
Published: December 2004

We examined H+ and HCO3− transport mechanisms that are involved in the regulation of intracellular pH of Schwann cells. Primary cultures of Schwann cells were prepared from the sciatic nerves of 1–3‐day‐old rats. pHi of single cells attached to cover slips was continuously monitored by measuring the absorbance spectra of the pH‐sensitive dye dimethylcarboxyfluorescein incorporated intracellularly. The average pHi of neonatal Schwann cells bathed in HEPES mammalian solution was 7.17 ± 0.02 (n = 32). In the nominal absence of HCO3−, pHi spontaneously recovered from an acute acid load induced by exposing the Schwann cells to 20 mM NH4+ (NH4+ prepulse). This pHi recovery from the acute acid load was totally inhibited in the absence of external Na+ or in the presence of 1 mM amiloride. In both cases, the pHi recovery was readily restored upon readdition of external Na+ or removal of amiloride. In the steady‐state, addition of amiloride caused a small and slow decrease in pHi which was readily reversed upon removal of amiloride. In the presence of HCO3−, removal of external Cl‐ caused pHi to rapidly and reversibly increase by 0.23 = 0.03 (n = 15) and the initial rate of alkalinization was 20.6 ± 2.7 × 10‐4 pH/sec. In the absence of external Na+, removal of bath Cl− still caused pHi to increase by 0.15 ± 0.02 and the initial rate of pHi increase was not significantly altered. In the nominal absence of HCO3−, removal of bath Cl‐ caused pHi to increase very slightly (0.05 ± 0.01) with an initial dpHi/dt of only 4.4 ± 0.2 × 10−4 pH/sec (n = 4). Addition of 100 μM DIDS did not inhibit the pHi increase caused by removal of bath Cl−. These data indicate that (1) Rat Schwann cells regulate their pHi via an Na‐H exchange mechanism which is moderately active at steady‐state pHi. (2) In the presence of HCO3−, there is a Na‐independent Cl‐HCO3 (base) exchanger which also contributes to regulation of intracellular pH in Schwann cells. © 1994 Wiley‐Liss, Inc.