bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of the methanogenic fermentation of acetate
Authors: Powell Godfrey E. , Hilton Martin G. , Archer David B. , Kirsop Brian H. 
Published: July 2010

AbstractThe kinetics of methanogenesis from a stirred batch‐fed calcium acetate enrichment culture have been studied. A detailed kinetic analysis of the culture allowed four distinct phases to be distinguished. Phase 1 was a period of very rapid increase (from low initial values) in the rate of methanogenesis upon addition of acetate, and was not thought to be associated with cell growth. In Phase 2 the rate of methanogenesis increased exponentially with time reflecting exponential growth. Phase 3 was characterised by an approximately constant rate of methane production, and is discussed in relation to the uncoupling of growth and methanogenesis. Phase 4 is a period of rapid decline associated with depletion of acetate. The apparent size of the population of the acetate‐utilising methanogenic bacteria subsequently declined, with a specific decay constant of 0.4 ± 0.1 d−1. The significance of these phases, in particular 2 and 3, for industrial anaerobic digestion is discussed.
The hydrolysis of xylan by Cellulomonas preparations
Authors: Daly Jan M. , Švejkar Marc , Rickard Pamela A. D. 
Published: July 2010

AbstractThin layer chromatography was demonstrated as an effective technique for observing the time course of hydrolysis of a substituted xylan (arabinoxylan) by crude preparations of Cellulomonas. The chromatograms revealed a sequential pattern of appearance of xylooligomers and arabinoxylooligomers, with early appearance of relatively large oligomers and subsequent accumulation of xylobiose and (to a lesser extent) xylose and arabinose. The pattern indicated that the dominant enzymic activity towards arabinoxylan is that of an endoxylanase.
Electron‐transfer coupling in microbial fuel cells. 2. performance of fuel cells containing selected microorganism—mediator—substrate combinations
Authors: Delaney Gerard M. , Bennetto H. Peter , Mason Jeremy R. , Roller Sibel D. , Stirling John L. , Thurston Christopher F. 
Published: July 2010

AbstractVarious phenoxazine, phenothiazine, phenazine, indophenol and bipyridilium derivatives were tested for their effectiveness as redox mediators in microbial fuel cells containing Alcaligenes eutrophus, Bacillus subtilis, Escherichia coli, or Proteus vulgaris as the active biological agent, and glucose or succinate as the oxidisable substrate. A ferricyanide‐Pt cathode was used. The open‐circuit cell e.m.f.′s increased in the order of increasing negative formal redox potentials at pH 7(E7m) of the redox compounds. Several of the redox agents worked well as mediators, maintaining steady currents over several hours, and thionine was found to be particularly effective in maintaining relatively high cell voltages when current was drawn from the cell. A number of the compounds tested did not function well, either because they were incompletely or slowly reduced by the microorganisms or because of their instability. P. vulgaris, with thionine as mediator and glucose as substrate, showed the best performance in a fuel cell. This system was examined in some detail under various conditions of external load to establish the effects of organism concentration, mediator concentration, and substrate addition. Coulombic outputs from these cells were calculated by integration of the current‐time plots. Coulombic yields of 30–60% were obtained, on the basis of (theoretical) complete oxidation of added substrate to CO2 and water.
Growth kinetics of non‐competitive product inhibition in batch cultures
Authors: Powell Godfrey E. 
Published: July 2010

AbstractThis paper develops the kinetics of a substrate‐limited batch culture of bacteria subject to non‐competitive product inhibition. The equation of growth is solved exactly. The expression which represents, growth is shown to consist of the sum of three terms. These correspond to three successive phases: exponential in near‐optimal conditions, linear growth which reflects product inhibition and finally decelerating growth arising from substrate depletion. The extent and distinguishability of the three phases is dependent on the relative values of the growth parameters.
Increased enzyme activity in immobilised cell composites with a highly hydrophilic polymer matrix
Authors: Kumakura Minoru , Kaetsu Isao 
Published: July 2010

AbstractStreptomyces phaeochromogenes cells were immobilised by radiation polymerisation of hydrophilic monomers; highest levels of glucose isomerase activity were found in immobilised cell composites with highly hydrophilic polymer matrices. The enzyme activity in the composites from the copolymerisation of hydroxyethyl acrylate (or methacrylate) and N‐vinyl‐2‐pyrrolidone monomer increased markedly with increase in the content of the N‐vinyl‐2‐pyrrolidone monomer, owing to the higher water absorption by the polymer matrix, and was close to that of the non‐immobilised cells. The enzyme activity was affected by monomer concentration, the hydrophilicity, and chemical structure of the polymer matrix. The Michaelis constant of the composites from hydrophilic monomers was close to that of the intact cells.
An automatic ATP monitor for activated sludge characterisation
Authors: Van Esbroeck H. , Schram E. , Vereecken J. 
Published: July 2010

AbstractA continuous process control apparatus for the determination of ATP in biomass was developed for monitoring activated sludge quality in biological wastewater treatment plants. The determination of ATP was based on the firefly luciferase reaction. The extraction efficiency of ATP removal from the biomass, influence of extractant on bioluminescence and potential for automation were tested during optimisation procedures. During the operation of a laboratory scale bioreactor, the automatic ATP analysis system provided a rapid and reproducible monitor of the biomass. It was a sensitive detector of inhibitory effects in the bioreactor and proved an excellent ‘toxicity monitor’.
Mechanical foam control in a stirred draft‐tube bioreactor
Authors: Ohkawa Akira , Sakai Nobuyuki , Imai Hiroshi , Endoh Kazuo 
Published: July 2010

AbstractThe mechanical foam‐breaking rotating disk (MFRD) was installed in a stirred draft‐tube bioreactor and provided effective foam‐breaking action. The device utilised the impact between atomised liquid particles projected from the disk and the ascending foam. The foam‐breaking characteristics of the MFRD were investigated in relation to the air sparge rate and the impeller speed. Empirical equations were devised to describe and predict the critical foam‐breaking regions of the MFRD under any operating conditions of the stirred draft‐tube bioreactor.
Ethanol production and tolerance in grande and petite yeasts
Authors: Brown Stephen W. , Sugden David A. , Oliver Stephen G. 
Published: July 2010

AbstractIt has been suggested that cytoplasmic petite mutants of Saccharomyces yeasts might be useful in commercial ethanol production since they are incapable of respiration. The authors have compared the rate and extent of ethanol production in a grande strain of S. uvarum and in a cytoplasmic petite mutant derived from it. Increasing the concentration of O2 in the input gas feed to a continuous culture of the grande beyond 0.17% increased the rate of biomass production at the expense of that of ethanol. In contrast, the rates of production of both biomass and ethanol by a similar culture of the petite increased with increasing O2 up to a level of 0.6% of the input flow. Above that level no further increase was recorded. At no O2 level did the yield or productivity of ethanol by the petite exceed the maximum obtainable with the grande. Batch culture studies demonstrated that the petite was more sensitive to the growth inhibitory effects of ethanol than was its grande parent. This may explain the poorer performance of the mutant strain.
Immobilised cellulolytic and hemicellulolytic enzymes from Macrophomina phaseolina
Authors: Roy P. K. , Roy U. , Dube Dipak K. 
Published: July 2010

AbstractCellulolytic enzymes from Macrophomina phaseolina were immobilised in acrylamide polymer. The immobilised enzyme preparation showed activity towards filter paper and cotton. However, the degree of hydrolysis of highly organised cellulose, particularly cotton, appears to be low in comparison with that of soluble substrate. The kinetic studies of immobilised enzymes indicated the presence of diffusional limitations by the increase in Vmax as the particle size decreased. The operational studies suggested that the immobilised enzymes retained the original activities up to 25–29 times in the reuse cycle.
An explanation of the discrepancy between the results of h.p.l.c. and DNS assays in the analysis of lignocellulosic hydrolysates
Authors: Fox David J. , Gray Peter P. , Dunn Noel W. , Marsden Warwick L. 
Published: July 2010

AbstractThe concentration of polymerised sugars in enzymic hydrolysates from lignocellulosic materials was determined by high pressure liquid chromatography (h.p.l.c.) of hydrolysates before and after dilute acid hydrolysis: significant quantities of polymerised glucose and xylose were found in lignocellulosic hydrolysates, and these accounted for the discrepancy between the dinitrosalicyclic acid (DNS) and h.p.l.c. assay methods.
Recent Developments in Protein Recovery and Purification
Authors: Thomson Alan R. 
Published: July 2010

AbstractThis article deals with emerging techniques for the purification of proteins, with an emphasis on those methods which have potential for scale‐up. These include membrane processes, some new adsorption and affinity techniques, supercritical gas extraction, 2‐phase aqueous liquid/liquid extraction, and electrokinetic methods. Many are at an early stage of development for their use in the food industry. However, it is likely that in the future they will broaden substantially the options available for processing both ‘solid’ and ‘liquid’ streams. Significant and sustained research and development will be needed to convert these techniques to off‐the‐shelf established technologies.
Developments in cucumber fermentation
Authors: Fleming Henry P. 
Published: July 2010

AbstractCucumbers may be used as a fermentation substrate by lactic acid bacteria in a solution of sodium chloride. Successful fermentation is dependent upon interactions among the microbiological, chemical and physical factors associated with suspension of a solid, porous vegetable in a liquid. Maintenance of structural integrity of the cucumbers is very important, and this introduces complexities not encountered in fermentation of liquid materials. This review summarises recent efforts to understand and control the critical factors associated with cucumber fermentations. New and emerging technologies that have evolved from fundamental studies included in the review are: reduction in sodium chloride concentration for brining; purging of CO2 from fermenting brines to prevent gaseous deterioration of the cucumbers; gas exchange of fresh cucumbers to influence their brining properties; development of new and valuable cultures of lactic acid bacteria for use in fermentations, and development of an anaerobic tanking system for cucumber fermentations.
Adsorption and complexation mechanisms of heavy metal uptake in activated sludge
Authors: Lawson Patricia S. , Sterritt Robert M. , Lester John N. 
Published: July 2010

AbstractDifferences were observed between the uptake of cadmium, copper, manganese and nickel by activated sludge biomass: their removal was studied when a range of metal concentrations was added to resuspended mixed liquor solids in the absence of possibly competitive organic ligands. The predominant mechanism of metal removal was passive uptake with some indication of binding site specificity for copper and possibly manganese. The data obtained were interpreted in the form of adsorption isotherms. The results were used to calculate conditional stability constants (K′) of the complexes formed, and the complexation capacity of the biomass for heavy metal uptake. Studies were conducted over a range of sludge ages from 3 to 12 days. Log10K′ values between 4.6 and 6.7 were found. However, there was no direct relationship between sludge age and K′. EDTA was used to desorb bound metal: this provided a means of differentiating between the surface complexes and the unexchangeable metal such as that taken up intracellularly. There was a difference in the adsorption affinity series of the metals when EDTA was present. This indicated that more than one mechanism for metal uptake was operating, and that the relative importance of physical and chemical absorption varied with each metal.
Selection and isolation of glucose‐tolerant amylolytic Aspergillus by cyclic fed batch culture process
Authors: Lee Yuan‐Kun , Low Chin‐Seng 
Published: July 2010

AbstractA simple cyclic fed batch culture system was developed for selection and subsequent isolation of glucose‐tolerant Aspergillus niger strain. A culture medium which contained 1.2 g dm−3 of glucose was inoculated with a non‐glucose‐tolerant A. niger (Ki =20.25 g dm−3). A culture medium of higher glucose concentration (100 g dm−3 and 200 g dm−3) was fed at a rate equal to the rate of HN4+ consumption by means of a pH control system. The maximum and minimum liquid levels in the fed batch culture vessel were determined by two liquid level detectors which activated and deactivated a harvest pump. The novelty of the selection system is that the frequency and pressure of selection increase gradually but continuously, and they are determined by the intrinsic potential of the culture. The process was fully automatic. An Aspergillus mutant which had a glucose inhibition constant of 3200 g dm−3 was isolated after six generations. The process should be particularly useful for screening filamentous microorganisms growing on novel substrates or tolerating inhibitors.
Synthesis of vanillin and 4‐hydroxybenzaldehyde by a reaction scheme involving condensation of phenols with glyoxylic acid
Authors: Kalikar Rajendra G. , Deshpande Ramesh S. , Chandalia Sampatraj B. 
Published: July 2010

AbstractSynthesis of vanillin and 4‐hydroxybenzaldehyde from guaiacol and phenol, respectively, was investigated. The condensation of guaiacol and phenol with glyoxylic acid in an aqueous alkaline medium resulted in the formation of 3‐methoxy‐4‐hydroxymandelic and 4‐hydroxymandelic acid respectively. A process version for the condensation of the phenol with glyoxylic acid, wherein it was found advisable to add an aqueous solution of glyoxylic acid and part of alkali to a batch of the phenol in aqueous alkali, was found to give 77% yield of the mandelic acid based on glyoxylic acid. The oxidation of the mandelic acid could be more suitably carried out at 95°C using 0.51 mol of copper (II) hydroxide for every mole of the mandelic acid in a process where air is simultaneously passed. Taking 3‐methoxy‐4‐hydroxymandelic acid as an example, 88% conversion to vanillin could be obtained. The reaction was found to be second order with respect to the mandelic acid.
Adsorption of lead on activated carbons from olive stones
Authors: Rivera‐Utrilla José , Ferro‐García Maria A. , Mingorance María D. , Bautista‐Toledo Isidora 
Published: July 2010

AbstractStudies on the adsorption of lead on activated carbons from aqueous solutions are described. Olive stones have been used as raw material to prepare the activated carbon samples. The porous texture and the chemical nature of the surface of the carbon samples were studied. The adsorption yield as a function of pH, salinity and presence of different cations has been investigated. The results obtained by using these activated carbons have been compared with those corresponding to a commercial activated carbon. All samples show a high adsorption capacity against lead ions.
Hydrogenation of CO and CO2 on carbon black‐supported Ru catalysts
Authors: Rodríguez‐Ramos Inmaculada , Reinoso Francisco Rodríguez , Guerrero‐Ruiz Antonio , de Dios López‐González Juan 
Published: July 2010

AbstractThe activity and selectivity of both unsupported Ru and carbon black‐supported Ru catalysts toward the hydrogenation of CO and CO2 have been investigated in order to learn about the effect of metal particle size on both reactions. The specific activity for both reactions decreases with metal particle size and the product distribution obtained in the hydrogenation of CO (the hydrogenation of CO2 only yields methane) is also a function of metal dispersion; thus, the proportion of methane produced increases and the olefin/paraffin decreases with decreasing Ru particle size. This behaviour is attributed to changes in the electronic properties of the Ru crystallites in close contact with the graphitised carbon black used as support.
A kinetic study of cyclohexane dehydrogenation on Pt monolithic catalyst
Authors: el Sawi Mahmoud , Frusteri Francesco , Parmaliana Adolfo , Formisano Bruno , Giordano Nicola 
Published: July 2010

AbstractThe kinetics of dehydrogenation of cyclohexane over Pt (0.3%) supported on honeycomb monoliths has been investigated. Integral measurements have been performed using continuous flow tubular reactor. No attempt has been made to suppress the reverse reaction. Experimental data have been fitted well by the following reaction model:

The estimates obtained for the kinetic parameters have been tested for their physical significance applying the criteria suggested by Boudart et al.
Chlorination of alkylbenzenes with molecular chlorine in alcoholic media
Authors: Bermejo Jenaro , Cabeza César , Blanco Carlos G. , Moinelo Sabino R. , Martínez Amelia 
Published: July 2010

Abstractm‐Xylene is chlorinated with molecular chlorine supplied at a constant flow rate, utilising short chain alcohols as solvents. Chlorinations occur as fast and clean substitution reactions, giving very high yields of monochloro derivatives. o‐Xylene and p‐xylene in ethanol give, however, much lower yields, similar to those of catalysed chlorinations. The behaviour of benzene, some other alkylbenzenes, and mixtures of xylenes in ethanol is also studied. In the mixtures, m‐xylene is very selectively chlorinated and almost quantitatively converted into monochloro derivatives.
Hydrogenation of 2,5‐dimethyl‐2,4‐hexadiene and cis‐2‐heptene on palladium black modified by lead, thallium and cadmium
Authors: Červeny Libor , Paseka Ivo , Tobola Stanislav , Ružička Vlastimil 
Published: July 2010

AbstractThe competitive hydrogenation of 2,5‐dimethyl‐2,4‐hexadiene and cis‐2‐heptene catalysed by palladium black modified by lead, thallium and cadmium to various degrees of surface coverage, was investigated. An electrochemical method was used to determine the amounts of hydrogen dissolved and adsorbed on the catalyst. The effect of ad‐atoms of lead, thallium and cadmium on the kinetics of the competitive hydrogenation is discussed in terms of measured values of the reaction selectivity.
Factors influencing the reaction between phlogopite and CaSo4·2H2O plus CaO mixtures
Authors: Aitta Eero , Jyrkäs Kauko 
Published: July 2010

AbstractAccording to earlier studies phlogopite reacts with CaSO4.2H2O and a mixture of CaSO4.2H2O and CaO exchanging 40–80% of its potassium with calcium. The same reactions occur only poorly in the case of muscovite. The structural difference between phlogopite and muscovite is small so that some unknown factors must effect the exchange reaction. In the present work the factors influencing the reaction between phlogopite and a CaSO4.2H2O/CaO mixture have been studied by means of X‐ray diffraction and an electron microscope. A rod mill has been employed in the separation of the solid phases produced during the reaction. The results have been calculated and drawn by computer programs created for the study. The effects of gypsum, calcium oxide, iron, aluminium and magnesium have been treated in the exchange reaction. Also the poor reactivity of muscovite in the reaction conditions used has been discussed.
Inhibition of horse liver and yeast alcohol dehydrogenase by aromatic and aliphatic aldehydes
Authors: Richard Bowen W. , Pugh Shirley Y. R. , Schomburgk Nicola J. D. 
Published: July 2010

AbstractThe reactivity of yeast alcohol dehydrogenase (YADH) and horse liver alcohol dehydrogenase (HLADH) towards 12 different aldehydes was tested. YADH was inhibited by pre‐incubation with citral, citronellal, p‐cuminaldehyde, p‐anisaldehyde, m‐tolualdehyde, trans‐cinnamaldehyde, salicylaldehyde, p‐hydroxybenzaldehyde and benzaldehyde, although of these aldehydes only trans‐cinnamaldehyde acted as a substrate for the enzyme. HLADH was inhibited, to a much smaller extent, by pre‐incubation with citral, salicylaldehyde, citronellal, p‐anisaldehyde, piperonaldehyde, trans‐cinnamaldehyde, p‐hydroxybenzaldehyde and p‐cuminaldehyde and all of these aldehydes acted as substrates for the HLADH. Immobilisation of the enzymes on CNBr‐activated Sepharose 4B gave protection against inhibition by the aldehydes, suggesting a means of significantly extending the useful lifetime of the enzymes when they are used in industrial processes.
Thermodynamic studies on sulphate roasting for zinc electrowinning from carbonate ore
Authors: Madkour Loutfy H. 
Published: July 2010

AbstractThe bulk of the work consists of a theoretical study of the possibility of submitting Umm‐Gheig carbonate ore to sulphate roasting. The use of the admixture with pyrites is to enable a carbonate ore to be treated in a similar way to a sulphide ore, and by doing so, to produce a roasted product capable of being treated by orthodox zinc electrowinning methods using sulphate solutions. Thermodynamic studies have been made to find the optimum conditions for sulphate roasting, in either normal air or enriched 36% oxygen air. The results obtained from the experimental work at different roasting temperatures in a tube furnace indicated that a maximum dissolution of 91.2% Zn with a 17.9% Fe could be obtained at a roasting temperature of 650°C for 4 h, followed by leaching in 4% H2SO4 (by vol.) at 60°C. The results of the electron microscopic investigation confirmed by metal value data given in the ASTM cards coincide well with results given by chemical analysis.
Design of immobilised glucoamylase reactors using a simple kinetic model for the hydrolysis of starch
Authors: Cabral J. M. S. , Novais J. M. , Cardoso J. P. , Kennedy J. F. 
Published: July 2010

AbstractA comparative study is reported of the three main types of continuous reactors, continuous feed stirred tank reactor (CFSTR), packed bed reactor (PBR) and fluidised bed reactor (FBR), for the conversion at 50°C of a 30% (w/w) corn syrup 40 DE using glucoamylase (exo‐1,4‐D‐glucosidase, EC 3.2.1.3) immobilised on carbonyl derivatives of titanium(IV)‐activated porous silica by a method developed previously.1–3 The hydrolysis of starch in these reactors is described by a simple kinetic model4 which involves the intrinsic kinetic constants as well as mass transfer and dispersion effects, and allows the computation of enzyme activity values under continuous operation. FBR appears to be more effective for the hydrolysis of starch. This reactor also confers a better operational stability (t1/2=775h) on the immobilised enzyme than the other immobilised glucoamylase reactors (PBR, t1/2=629h; CFSTR, t1/2=239h).
The yeast alcohol dehydrogenase catalysed conversion of cinnamaldehyde to cinnamyl alcohol
Authors: Richard Bowen W. , Lambert Nigel , Pug Shirley Y. R. , Taylor Frank 
Published: July 2010

AbstractThe kinetics of the conversion of trans‐cinnamaldehyde to trans‐cinnamyl alcohol catalysed by yeast alcohol dehydrogenase (EC 1.1.1.1) have been characterised. Reaction with the free enzyme is curtailed after a short time as a result of inactivation by the substrate. It has been shown that immobilisation of the enzyme provides substantial protection against this inactivation. Use of the immobilised enzyme in a flow‐through reactor further enhanced the enzyme lifetime, creating a viable synthetic process. The product cinnamyl alcohol may be recovered by continuous solvent extraction.