bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphological and metabolic changes in the yeast Kluyveromyces marxianus var. marxianus NRRLy2415 during fermentation of lactose
Authors: Walker Graeme M. , O'Neill Joseph D.
Published: July 2010

Oxygen availability has been identified as a major factor in governing the morphology of the lactose‐fermenting yeast, Kluyveromyces marxianus var. marxianus (formerly fragilis) NRRLy2415. In this particular strain, filamentous cells (F forms) predominate during the initial stages of aerobic propagation whilst budding yeast cells (Y forms) predominate during anaerobiosis. In other K. marxianus strains, and in Candida pseudotropicalis, budding cells predominate irrespective of oxygen availability. Increased cellular cytochrome contents and oxygen uptake rates accompanied Y to F (yeast to filamentous) transitions in K. marxianus NRRLy2415, suggesting that functional mitochondria are involved in controlling dimorphism in this yeast. This was further supported by the observation that respiratory inhibitors such as chloramphenicol prevented filamentation and promoted formation of respiratory‐deficient budding cells. During aerobic batch cultivation. K. marxianus displayed physiological variability in which cells were initially filamentous and respiratory but latterly were yeast‐like and fermentative, suggesting that growth rate as well as oxygen availability affected cell physiology. This was supported by the finding that during growth in lactose‐limited chemostat culture, the morphology and respiratory activity of K. marxianus varied with the specific growth rate of cells. I n addition, the fermentation rates of F and Y forms varied, although maximum ethanol yields were not significantly different between the two morphologies. These results have implications for the more eflcient conversion of lactose to ethanol in commercial fermentations of cheese whey.
Reverse osmosis of lactic acid fermentation broths
Authors: Schlicher Laura R. , Cheryan Munir
Published: July 2010

Lactic acid model solutions and fermentation broths were concentrated using a tubular thin‐film composite reverse osmosis membrane. Flux increased linearly with applied transmembrane pressure and was relatively unaffected by flow rate. Osmotic pressures of 1% lactate solutions were 280–560 kPa, depending on the pH or degree of dissociation. Rejections increased with applied pressure. Higher pH caused a slight decrease in flux (due in part to the higher osmotic pressure) and a significant increase in rejection. Above pH 5·6, rejections of lactate and residual sugars were > 97%. In contrast, with cellulose acetate membranes, flux was generally lower and lactate rejection was proportional to the degree of dissociation at lower pressures.
Liquid‐phase oxidation of p‐cresol and Substituted p‐Cresols by Air
Authors: Sharma Shreekumar N. , Chandalia Sampatraj B.
Published: July 2010

The liquid‐phase oxidation of p‐cresol and substituted p‐cresols by air under alkaline conditions using cobaltous chloride as a catalyst and methanol as solvent, has been investigated with a view to obtain the corresponding aldehydes with sufficiently high selectivities. In the case of p‐cresol, the effects of various process parameters on the reaction rate and selectivity with respect to the aldehyde have been investigated. The results obtained are likely to be useful for the development of processes for the production of industrially relevant products such as 4‐hydroxybenzaldehyde, vanillin and syringaldehyde by using p‐cresol as the starting material. Various alternative process schemes have been proposed and evaluated.
Reaction of chrysotile asbestos with phosphate ion in relation to toxicity
Authors: Awadalla Farouk T. , Habashi Fathi , Pag Michel
Published: July 2010

Chrysotile asbestos (Grade 7RF66) sorbs phosphate ion from aqueous solution of phosphoric acid, basic disodium phosphate, ammonium dibasic phosphate, sodium pyrophosphate, or sodium tripolyphosphate. The amount sorbed varies from 0·2 to 2·5% P2O5. The fiber treated with ammonium dibasic phosphate has appreciably low toxicity that is comparable to chrysophosphate obtained by the reaction of chrysotile asbestos with POCl3 gas, provided the latter is washed thoroughly with water to remove watersoluble ingredients.
Kinetics of continuous whey fermentation by Kluyveromyces fragilis
Authors: Moresi Mauro , Trunfio Antonio , Parente Eugenio
Published: July 2010

Continuous whey fermentation by Kluyveromyces fragilis was studied in a 30‐dm3 stirred fermenter as a function of the dilution rate (D) and feed concentration of lactose (So). By using the concept of material and energy balances, it was possible not only to check the consistency of the experimental steady‐state responses, but also to develop an unstructured model based on a Monod‐type kinetic equation for cell growth and two independent linear equations for the consumption rates of lactose and oxygen. Moreover, a typical Lineweaver—Burk plot enabled the yeast specific growth rate to be described as that of an enzyme‐catalysed reaction in the presence of an unknown noncompetitive inhibitor (that was identified with a reference intermediate compound produced by the microorganism itself under partially anaerobic conditions and expressed in terms of ethanol equivalent). In this way, the experimental cell concentrations were reconstructed with a mean standard error of about 10%, thus confirming the capability of this model to provide a reliable basis for further scale‐up of this fermentation process.
Biomass production by thermophilic microorganisms simultaneously using reaction heat
Authors: Heinritz Brigitte , Gehrhardt Matthias , Baumann Frank , Rogge Gerlind , Hedlich Rolf
Published: July 2010

An energy‐economic use of reaction heat is possible only if thermophilic microorganisms convert carbon substrates into biomass at temperatures above 65°C.

The thermophilic bacterium Bacillus stearothermophilus TP5 was isolated from a man‐made hot water reservoir. The highest specific growth rate of 1.6 h−1 was obtained in continuous cultivation (chemostat) on a glucose‐containing nutrient medium at 68°C, pH 6.8 and normal pressure. The highest values for the biomass production rate (3.2 g dm−3 h−1) and the biomass yield coefficient (0.39 gg−1) were obtained at a dilution rate of 1.3 h−1 (about 80% of the highest specific growth rate) under the above‐mentioned conditions. The biomass production rate of the thermophilic bacterium was higher in the chemostat than in the semicontinuous process at normal pressure. The biomass produced in the chemostat at a dilution rate of 0.4 h−1 contained 71% of protein and 8% of RNA and had an ash content of 6%. The optimum and maximum temperatures of growth were changed by raising the pressure inside the reactor.

As a prerequisite for the energy‐economic use of the reaction heat, the specific heat production was determined by using a special calorimeter. The ratio of heat production to oxygen consumption (oxy‐caloric coefficient) was found to be 13.6 kJ g−1, which is close to the theoretical value deduced from mass‐ and energy‐balance theory.
Quantities relevant to the handling safety of greasy wool
Authors: Jones J. C. , Lucien F.
Published: July 2010

Greasy wool has a very considerable propensity towards self‐heating, and two quantities relevant to such self‐heating—activation energy of oxidation and thermal diffusivity—have been measured for four samples of ‘as‐received’ greasy wool. For comparison, the same quantities for two cellulosic fibre materials—raw cotton and kapok—are also presented.
Recycling of salts in partition protein extraction processes
Authors: Greve Arend , Kula Maria‐Regina
Published: July 2010

Aqueous two‐phase extraction systems were developed to separate intracellular proteins from cell debris. To economize on the use of chemicals as well as to minimize environmental pollution, a closed mode of operation was sought. Various approaches to achieve recycling of salt from the primary lower phase containing 30–60% (w/w) of the added salt together with cell debris, proteins and nucleic acids were studied. Techniques assessed included microfiltration, heat treatment and the extraction with phase systems formed by aliphatic alcohols. With 20% (w/w) primary lower phase it was found to be possible to separate 95% of the salt in 3–4 theoretical steps using counter‐current extraction.
Continuous separation of particles from macromolecules in split‐flow thin (SPLITT) cells
Authors: Levin Shulamit , Giddings J. Calvin
Published: July 2010

A split‐flow thin (SPLITT) cell with a perpendicular driving force of one gravity has been utilized for the rapid separation of micron‐sized particles from macromolecules. The procedure involves the simultaneous use of two transport mechanisms and thus two operating modes: a sedimentation process controls the displacement of the particles across the thickness of the thin channel, while diffusion controls the displacement of macromolecules. The theoretical equations for these two operating modes are summarized and it is shown how the two modes can be combined to yield specified recovery factors. The theory was tested on a mixture of 10 μm polystyrene latex beads and three different proteins. The observed separation was in excellent agreement with theory. Attempts to fractionate red blood cells and plasma proteins from whole blood were only partially successful as a consequence of the weak sedimentation of red blood cells. Various remedies to this problem are suggested, the most promising of which is the use of a SPLITT cell subject to mild centrifugal forces.
The hydrogenation of triglycerides using supported alloy catalysts. I. Silica‐supported Ni—Ag catalysts
Authors: Parry J. D. , Winterbottom J. M.
Published: July 2010

Silica‐supported Ni‐Ag catalysts with a loading of 2·1·0.6% (w/w) total metal have been prepared using the precursors nickel dimethylglyoxime and silver nitrate by means of a simple impregnation method. The resulting catalysts were activated by calcination at 260°C in air, followed by hydrogen reduction at 450°C. They were then employed for soyabean oil hydrogenation at 1 bar H2 pressure and 160°C in a stirred batch reactor.

Characterisation of the catalysts using temperature‐programmed reduction and electron microscopy indicated that alloying of nickel and silver had occurred, but metal particle composition, for a given overall composition, varied with metal particle size and smaller metal particles were nickel rich.

The hydrogenation activity and selectivity measurements revealed that the catalysts were more active and selective than a commercial nickel catalyst. Furthermore, the specific activities of the alloy catalysts were a maximum for alloys in the range 70–90 at. % Ni. However, the supported alloy catalysts also gave rise to greater trans isomerisation than the commercial catalyst. This is attributed to hydrogen deficiency caused by large triglyceride molecules blocking hydrogen chemisorption on small nickel particles (10–50 Å in diameter), leading to enhanced cis‐trans isomerisation.
The hydrogenation of triglycerides using supported alloy catalysts. II. Silica‐supported Pd‐Cu catalysts
Authors: Parry J. D. , Winterbottom J. M.
Published: July 2010

Palladium‐copper catalysts supported upon silica, containing 2–6% (w/w) total metal, have been prepared by (i) precipitation and (ii) impregnation methods. The catalysts were employed for the hydrogenation of soyabean oil at 1 bar H2 pressure and at 160°C in a stirred batch reactor.

Temperature‐programmed reduction studies provided evidence of alloying of palladium and copper and metal surface area measurements exhibited evidence of a slight maximum in the metal surface area at around 90 at. % Pd content. In addition, it was observed that the presence of copper seemed to prevent sintering of palladium, giving a more stable or even enhancing metal surface area compared with palladium alone.

Activity measurements showed that there was evidence of a maximum at around 80–90 at. % Pd content. However, selectivity measurements showed that the latter parameter was dominated by the presence of palladium and except at very high copper contents the superior selectivity of the latter for linolenate chain hydrogenation was hardly evident. It is thought that the palladium may cause the copper to be present largely as Cu°, which is not as effective as Cu1 in catalysing selective hydrogenation of multiply unsaturated species.
Large‐scale chromatography in industrial processing
Authors: Ganetsos G. , Barker P. E.
Published: July 2010

Although chromatography has been established as a powerful analytical tool, its large‐scale application is not widely appreciated. In this short review the up‐to‐date developments in the scaling‐up of chromatographic processes are considered and the designs judged to offer the greatest potential and commercial viability are described paying special emphasis to liquid applications.

Sufficient references are included to enable the interested reader to pursue the subject further.
Production of furfural by acid hydrolysis of corncobs
Authors: Riera Francisco A. , Alvarez Ricardo , Coca José
Published: July 2010

Hydrolysis of corncobs for producing furfural was carried out in a pressurized batch reactor using superheated water and diluted sulphuric acid as catalyst. The range of experimental conditions was T=140–200°C and P=350–1550 kPa. Yields of furfural are reported as a function of reaction temperature, particle size, acid concentration and liquid/solid ratio. Attention has been focused on the solid residue remaining after the hydrolysis process, so that it can be further used as a humic fertilizer after oxiammoniation treatment.
The internal architecture of anaerobic sludge granules
Authors: Morgan J. W. , Evison L. M. , Forster C. F.
Published: July 2010

The structural characteristics of well‐formed anaerobic granular sludges were examined using scanning electron microscopy and light microscopy of thin sections. Transverse sections were found to consist of randomly orientated filaments of Methanothrix soehngenii. These were tightly packed with little space between the individual filament sheaths, revealing a ‘honeycomb’ appearance. Sections cut from wax‐embedded granules were stained using a number of histochemical procedures. Detailed examination of the overall structure of the granules was possible, revealing the presence of filamentous bundles of Methanothrix surrounded by a matrix found to be carbohydrate in nature. Interpretation of serial sections through the depth of the granule allowed for the construction of a diagrammatic illustration of the internal structure. A relationship between the measured diameter of these microcolonies of Methanothrix and the distance from the centre of the granule was established. Together these results enabled a proposal to be made as to the possible mechanisms involved in the growth of granules. This supports previous suggestions relating to the involvement of Methanothrix and bacterial polymers.
Hydrodynamic and mass transfer parameter correlations for the rotating disc contactor
Authors: Korchinsky W. J.
Published: July 2010

The normal, fragmented manner in which various model hydrodynamic and mass transfer parameters are measured and correlated separately, in the vain hope that accurate predictions of extraction column performance will be eventually possible, is avoided here. The ‘forward mixing’ model parameters are all determined simultaneously, in experiments with two sizes of rotating disc contactor where all required measurements, including drop size distributions and continuous phase profile compositions, are made during solute transfer between phases. Accurate predictions from the derived correlations of dispersed phase hold‐up fraction, drop size distributions and extraction efficiency are the result.
A low cost adsorbent from spent bleaching earth. II—optimisation of the zinc chloride activation procedure
Authors: Pollard Simon J. T. , Sollars Christopher J. , Perry Roger
Published: July 2010

A set of optimised preparative parameters has been established for the zinc chloride activation of spent bleaching earth. Continuous volumetric nitrogen adsorption and aqueous phase phenol isotherms are used to characterise a range of adsorbents prepared using the rotary furnace. A structural model is proposed for these clay‐carbon materials and the key factors affecting their adsorptive capacity are discussed.
Mechanistic studies of proteases and lipases for the detergent industry
Authors: Aaslyng Dorrit , Gormsen Erik , Malmos Henrik
Published: July 2010

The wash performance of three specific proteases (asp, lys/arg and glu specific, respectively) is demonstrated to be comparable to that of commercial unspecific detergent proteases (Alcalase® and Savinase®). A hypothesis for the high performance of these specific proteases is proposed. The influence of pH and ionic strength on protease performance is discussed.

The removal of oily stains by lipases in detergent solution is improved only slightly under acidic conditions, whereas pH values >> pKa of the fatty acids formed results in strongly enhanced removal. Wash trials with LipolaseTM show very little effect of the lipase after the first wash, but high effect after the second and subsequent washes. This is explained by lipolytic activity under drying. Maximum activity is found when the water content of the cotton swatches is between 10 and 40% (w/w).
Interactions between Polymers and Insoluble Materials in the Detergents' Matrices
Authors: Zini Paolo
Published: July 2010

Polycarboxylated polymers have a strong tendency to adsorb on a large variety of surfaces. Among the surfaces of interest in detergency, insoluble materials in water are those which cause, in general, most of the washing problems.

The insoluble materials may come from the intentional addition of them into the detergent (e.g. zeolites and abrasive ingredients) or may be formed during the washing process itself (e.g. Ca carbonate and Ca phosphate salts).
The behaviour of LAS in the environment
Authors: Berna José Luis , Moreno Alfonso , Ferrer Juan
Published: July 2010

During the last few years a considerable amount of information about the biodegradation of linear alkylbenzene sulfonates (LASs) in real environmental situations has been made available. This paper reviews the existing LAS concentrations found today in the environment, using specific analytical techniques for this surfactant, as well as its mineralization and fate in compartments such as sludge amended soils. LAS is totally decomposed into carbon dioxide, water and inorganic sulfate without formation of stable metabolites, and no accumulation has been detected in the compartments studied. The highest degree of biodegradation (>95%) takes place in the processes (sewers and sewage treatment plants) showing the shortest half lives (1–10 h).
Non‐animal alternative toxicity tests for detergents: Genuine replacements or mere prescreens?
Authors: Balls Michael , Reader Sandra , Atkinson Karen , Tarrant Jane , Clothier Richard
Published: July 2010

Non‐animal toxicity tests and testing strategies for use in identifying the potential toxic hazard of chemicals and products, and in providing information for use in risk and safety assessment, are in the course of development, validation and evaluation.

Possible replacement alternatives to the rabbit Draize eye irritancy test are discussed, and results obtained for two in‐vitro tests developed by FRAME (the kenacid blue test and the neutral red release test), applied to 19 surfactants and 32 formulations, are discussed.

It is concluded that there are now legal and moral requirements that relevant and reliable non‐animal tests should be developed and accepted for use whenever possible.
The methanogenic toxicity of wastewater lignins and lignin related compounds
Authors: Sierra‐Alvarez Reyes , Lettinga Gatze
Published: July 2010

Lignin derivatives are major components of wastewater streams generated in the chemical processing of wood. The objective of this study was to evaluate the inhibitory effect of various lignins isolated from forest industry wastewaters, and selected lignin model compounds, on methanogenic bacteria. The methanogenic inhibition was determined at 30°C in standard toxicity assays, utilizing anaerobic granular sludge as inoculum. The wastewater lignins differed considerably in their inhibitory activity. Some lignin samples were nontoxic, whereas others caused 50% inhibition at concentrations ranging from 3320 to 5950 mg COD dm−3. Experiments with ultrafiltered lignins revealed that the toxicity of the inhibitory lignin samples originated from the low molecular weight fraction. In additional studies with low molecular weight lignin model compounds, it was observed that the inhibitory activity of these compounds was related to the functional groups on the aromatic ring. Compounds with aldehyde groups or apolar substituents were highly toxic, whereas those with carboxylic groups only caused significant inhibition at high concentrations. These results indicate that low molecular weight lignin derivatives in forest industry wastewaters are potential inhibitors of anaerobic treatment systems.
Continuous aqueous phase extraction of proteins: Automated on‐line monitoring of fumarase activity and protein concentration
Authors: Papamichael Neophytos , Börner Bernard , Hustedt Helmut
Published: July 2010

Automated assay techniques are described for on‐line measurements of fumarase activity and total protein concentration, including in‐line sample dilution and sample multiplexing during continuous aqueous phase extraction. Fumarase was determined by following the conversion of L‐malate to fumurate at a wavelength of 250 nm, while the protein assay was based on the Biuret reaction. Actual assay times of 2 and 4 min were achieved for the fumarase and protein measurements, respectively, with an effective measurement cycle time of 2 min. Standard deviations of c. 3.2 and 2% of the measured values were calculated for the enzyme and protein values, respectively. The assay system was coupled to a computer to allow on‐line data visualization and storage.
Electrochemical ion exchange
Authors: Bridger Nevill J. , Jones Christopher P. , Neville Mark D.
Published: July 2010

This paper introduces electrochemical ion exchange (EIX) as a technique for the removal of ionic species from aqueous waste streams. The basic mechanistic principles behind EIX are presented and experimental procedures described. Typical experimental results for a number of applications are given. A comparison is made between EIX and electrodialysis and electrodialysis combined with conventional exchange.
Hydrolysis and esterification with immobilized lipase on hydrophobic and hydrophilic zeolites
Authors: Lie Ewa , Molin Göran
Published: July 2010

Hydrolysis and esterification in a triolein/oleic acid system were compared with Candida cylindracea lipase attached to celite, hydrophobic zeolite and hydrophilic zeolite. The hydrophilic zeolite blocked the hydrolysis but mediated the esterification. Esterification with celite or hydrophobic zeolite as carrier was poor.
Purification and kinetics of penicillin G acylase from a mutant strain of escherichia coli ATCC 11105
Authors: Erarslan Altan , Terzi Ibrahim , Güray Ayşe , Bermek Engin
Published: July 2010

A mutant strain with high penicillin G acylase activity was derived from Escherichia coli ATCC 11105 by chemical mutagenesis, using N‐methyl‐N′‐nitro‐N‐nitrosoguanidine. Penicillin acylase was extracted from the mutant strain and highly purified by DEAE‐cellulose and hydroxyapatite column chromatography followed by preliminary precipitation steps. Vm and Km values of the enzyme (specific activity: 24·81 U mg−1, protein concentration: 0.56 mg cm−3) were found to be 22.73 U cm−3 mm−1 and 3.18 mmold m−3 penicillin G, respectively. The enzyme was shown to be uncompetitively inhibited by excess of substrate. The inhibition by phenylacetic acid was found to be competitive, and 6‐aminopenicillanic acid to be noncompetitive. Inhibition constants for excess of penicillin G, phenylacetic acid and 6‐aminopenicillanic acid were estimated as 74.20, 18.74 and 15.00 mmol dm−3 respectively, at pH 8.0 and 40°C. The activation energy of the enzymatic hydrolysis reaction of penicillin G was found to be 10.78 kcal mol−1. Optimal pH and temperature values of the enzyme were determined as 8.0 and 60°C. Complete loss of the enzyme stability occurred when the enzyme was incubated at pH 10.0 for 2 days or at 50°C for 2 h.
Effect of temperature on the removal of lead(II) by adsorption on China clay and wollastonite
Authors: Yadava K. P. , Tyagi B. S. , Singh V. N.
Published: July 2010

The removal of Pb(II) from aqueous solution by adsorption on china clay and wollastonite is an attractive process. The amount of Pb(II) removed by adsorption is highly dependent on the temperature of the adsorbate solution and favours low temperature. The equilibrium times were noted, i.e. 90 min for china clay and 120 min for wollastonite. The various rate parameters of the adsorption process have been determined at different temperatures. The activation energies were determined and found to be −5.345 kJ mol−1 and −8.730 kJ mol−1 for Pb(II)‐china clay and Pb(II)‐wollastonite systems, respectively. The adsorption isotherm was measured experimentally at various temperatures. The negative values of enthalpy change (ΔH = −77.95 kJ mol−1 and −16.40 kJ mol−1 for china clay and wollastonite, respectively) indicate the exothermic nature of the adsorption processes for both systems. The isosteric heats of the adsorption process have been determined at various surface coverages of the adsorbents used. The various thermodynamic parameters have been calculated to elucidate the mechanism involved in the adsorption process.
Synthesis and anticonvulsant properties of some novel quinazolinone
Authors: El‐Feky S. A. H. , El‐Samii Z. K. Abd
Published: July 2010

Some quinazolinone thiosemicarbazone and 4‐thiazolidone derivatives were prepared and tested for their anticonvtdsant activity. 3‐(2‐methyl‐4‐(3H)‐quinazolinon‐3‐yl)‐4‐oxo‐thiazolin‐2‐yl‐(4‐chlorobenzaldehyde)‐hydrazone (4a) shows the maximum protecting activity against pentylenetetrazol‐induced seizures in albino mice.
The catalytic activity of the ceramic superconductor YBa2Cu3O7 − δ
Authors: Rophael Magdy W. , Khalil Laila B. , Malati Mounir A.
Published: July 2010

The superconductivity of the ceramic solid YBa2Cu3O7 − δ, prepared by heating Y2O3, BaCO3 and CuO at 920°C for 22 h, was checked by the Meissner effect. Chemical analysis established the formula of the compound prepared. A thermostated aqueous suspension of the superconductor, treated with a solution of H2O2, produced oxygen, whose volume was measured at intervals in a gas burette. From the initial rates of the first‐order reaction at different temperatures, the activation enthalpy and entropy were 16 kJ mol−1 and −210 J K−1 mol−1 respectively. The rates of gas evolution were similar to those obtained when a MnO2 sample was used as a catalyst. Neither the superconductor nor its semiconductor phase photocatalysed the decomposition of KMnO4 solution. Evidence of the catalysed decomposition of N2H+5 by the superconductor is presented.
Bioconversion of Lmalic acid into Llactic acid using a high compacting multiphasic reactor (HCMR)
Authors: Naouri Pascal , Bernet Nicolas , Chagnaud Patrice , Arnaud Alain , Galzy Pierre , Rios Gilbert
Published: July 2010

Biotransformation of Lmalic acid into Llactic acid was studied in a fluidised bed reactor using cells of Lactobacillus sp. 89 and Leuconostoc oenos ATCC 23278 immobilised in a calcium alginate matrix. The reactor was used in a batch or a continuous manner under a non‐oxidising atmosphere. It was shown that 3 mm diameter beads loaded with 6 and 30 mg dry matter per gram of gel were the best operating conditions for Leuconostoc and Lactobacillus respectively. The optimal working conditions were as follows: pH = 3.0–5.0, temperature = 30°C for Lactobacillus and pH = 3.0, temperature = 25°C for Leuconostoc. No inhibition due to lactic acid was observed and the internal diffusional effects were negligible. The short catalyst life that was initially observed with both strains resulted from a depletion in NAD and Mn2+, two basic cofactors for malolactic enzymes. To prevent this detrimental effect, a regeneration process for biocatalyst was proposed.
Kinetic investigation of penicillin g acylase from a mutant strain of Escherichia coli ATCC 11105 immobilized on oxirane–acrylic beads
Authors: Erarslan Altan , Güray Ayse
Published: July 2010

Highly purified penicillin G acylase from a mutant derivative of Escherichia coli ATCC 11105 was immobilized on oxirane–acrylic beads by covalent binding via oxirane groups. The highest specific activity, (322 U g−‐1 dry matrix at 40°C and at pH 8·0) was obtained by using an enzyme solution having 13·8 U mg−‐1 specific activity and 72·73 mg total protein. The efficiency of immobilization was 95·8%. Kinetic parameters of immobilized penicillin G acylase were determined at the same pH and temperature by a preparation having 8·1 mg bound protein. The Km value and substrate inhibition constant of the enzyme were found to be 11·36 mmol dm−‐3 and 680 mmol dm−‐3 penicillin G respectively. Phenylacetic acid and 6‐aminopenicillanic acid were estimated as the competitive and non‐competitive inhibitors of the enzyme and their inhibition constants were found to be 90 mmol dm−‐3 phenylacetic acid and 76·1 mmol dm−‐3 for 6‐aminopenicillanic acid. The activation energy of the hydrolytic reaction was calculated to be 7·75 kcal mol−‐1. The immobilized enzyme showed highest activity at pH 8·0 and at 55°C. The enzyme was stable when incubated at 4°C for one day at a pH range of 5·0 to 9·0. Thermal stability (over 30 min) was observed up to 40°C but decreased at higher temperatures and was almost absent at 60°C. A 95% conversion rate was observed at 28°C and at 40°C with 60 and 30 min operation times respectively. Operational stability of the enzyme was improved further with dithiothreitol treatment. Activity loss was around 5% following 20 cycles of repeated use of the enzyme at 40°C. No significant loss of activity was observed at 28°C when the enzyme was used,for 20 cycles. 6‐Aminopenicillanic acid in the reaction mixture was observed to be stable during conversion reactions which were carried out at both temperutures.
Effects of floating contactors on oxygen transfer and hydrodynamics in a bubble column
Authors: Kang Yong , Min Bung T. , Nah Jong B. , Kim Sang D.
Published: July 2010

This study investigates the adoption of floating contactors to promote the rate of oxygen transfer from non‐uniform air bubbles to liquid in a bubble column with continuous operation. The volumetric oxygen transfer coefficient and axial dispersion coefficient of a liquid phase have been analyzed based on the axial dispersion model. Attention was focused on the effects of the volume fraction of the floating contactors on the volumetric oxygen transfer coefficient, axial dispersion coefficient of a liquid phase, and gas phase hold‐up in the bubble column. The results have shown that the volumetric oxygen transfer coefficient and gas phase hold‐up can increase by up to 25% and 13%, respectively, while the axial dispersion coefficient of a liquid phase decreases by up to 30% by adding floating contactors in the column.
Enhancing oil recovery
Authors: Dawe Richard A.
Published: July 2010

The extraction of oil from oil reservoirs beneath the North Sea has stimulated an immense popular interest in oil exploration and production. The mass media cover many of the sensational aspects of the industry but the mechanisms of the production of oil from the reservoir are not often mentioned. This is partly because the reservoir is a huge heterogeneous volume hidden underground, but also because some background in science is required. The mechanisms of oil recovery depend to a great extent on what happens at the interface between the displaced and displacing fluids at the pore scale (μm) and the reservoir scale (km). Oil is left unrecovered in areas of the reservoir where the displacing fluid has not passed (by‐passed zones–sweep efficiency) and as droplets trapped in the pores in areas where displacement has occurred (microscopic residual oil–pore displacement efficiency). The physics at the interfaces, including the interplay between capillary, (interfacial tension, wettability), viscous and gravity forces is fundamental to an understanding of the retention of this residual oil (a common reservoir average estimate is over 60%) trapped by the capillary forces or by‐passed by the displacing gas or liquid due to inhomogeneity of the reservoir. The alteration of the balance of these forces is the key to enhancing the oil recovery, either by sweeping new areas of the reservoir or recovering some of the microscopically trapped oil.

This article is written to provide some of the background to oil production in the context of enhanced oil recovery (EOR). It firstly covers oil recovery that is normally practised, then describes the EOR techniques currently under active development and finally discusses some of the problems that research must overcome before EOR can be successfully implemented with confidence.
Hydraulic characteristics of biological filters
Authors: Muslu Yilmaz
Published: July 2010

Relationships between the removal efficiency and the hydraulic regimes of trickling filters were investigated. At low flow rates, where break‐up of liquid jets occurs and drops form, completely mixed conditions prevail. For large hydraulic loadings effluent concentrations were calculated by means of a dispersed plug flow model. The ranges of validity of these models were studied theoretically. The effects of drop formation and breakage of liquid jets on the substrate utilization are expressed in terms of hydraulic and physical properties of the media and liquid.
Studies on the dechlorination and detoxificaton of organochlorine compounds. I. PCBs and PCNs
Authors: Stojkovski Stojan , Markovec Ladislav M. , Magee Robert J.
Published: July 2010

In the analysis of organochlorines such as polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs), levels of, for example, PCB concentration are often expressed as a ‘total PCB’ value, using a straight GC pattern‐matching technique with electron capture detection. Such methods provide little information about the identity of the individual components. In the present study, preliminary investigations using dechlorination with a NiCl2/NaBH4 catalyst indicated that the technique offered a comprehensive method for the analysis of PCBs and PCNs, as well as a method of detoxification of the ‘priority pollutants’ . This paper reports the use of capillary column GC‐MS with an ion trap detector (ITDTM) for the analysis of a number of PCBs and PCNs, including the commercially produced Aroclor 1254 and 1221, employing this dechlorination technique.
A mathematical model for a biological fluidized bed reactor
Authors: Lin S. H.
Published: July 2010

A physical model is given in the present report for representing a three‐phase biological fluidized bed reaction system which consists of microorganism‐coated particles, waste water and air. The system is assumed to be well fluidized. The physical model can be represented by two differential equations describing, respectively, the substrate axial dispersion and diffusion/reaction. Numerical values of the physical parameters are selected from the literature or estimated from semi‐empirical equations. The governing system equations are solved by an iterative finite‐difference scheme. The theoretical predictions are compared with several experimental measurements and the agreement between them found to be very good, validating the physical model reported here.
Determination of vanadium in steels using phenylfluorone and cetylpyridinium bromide
Authors: Tarek M. , Zaki M. , Abuo‐Zeid Said M.
Published: July 2010

Vanadium(V) was determined spectrophotometrically by reaction with phenylfluorone (I) at pH 8.8 in the presence of cetylpyridinium bromide to form a 1:2 vanadium‐I chelate. The molar absorptivity of the sensitised chelate was 7.0 × 104 dm3 mol−1 cm−1 at 550 nm and the sensitivity index was 0.7 ng cm−2. Beer's law was followed up to 0.37 ppm of vanadium. The interference of other metal ions was eliminated by electrolytic separation using a mercury cathode. The developed method was successfully applied for the determination of vanadium in steels.
Gas transfer in an external loop bioreactor with built‐in ultrafiltration
Authors: White C. , Morgan N. L. , Killick E. G.
Published: July 2010

The SGI Ultrafermenter is an external loop bioreactor with circulation through an ultrafiltration module allowing removal of medium and soluble products during fermentation. The contents are continually circulated during operation and the vessel is also equipped with a stirring turbine. The interaction of these two mixing agents on gas transfer was investigated. Both mechanisms produced similar increments in KLa over their working ranges, with values from approximately 0–700 h−1 at 200 dm3 h−1 airflow. The effects of these two mechanisms on KLa were approximately additive at low values but the combined mixing produced a maximum KLa value also in the region of 700 h−1. The power‐draw of mixing using the two agents was calculated and stirring was found to be 10–20 times more efficient than circulation.
A comprehensive study on the polarographic behaviour of α‐arylhydrazono‐3‐ketimino‐nitriles
Authors: Ismail M. I.
Published: July 2010

The polarographic behaviour of some α‐arylhydrazono‐3‐ketimino‐nitriles (Ia—h) in 50% ethanolic aqueous buffer is reported and discussed. The mechanism of electrode processes corresponding to the observed cathodic waves is proposed and confirmed by the aid of model compounds as well as through identification of controlled potential electrolysis products. The E1/2 and pKa values of the title compounds were evaluated and correlated to Hammett constants. The physical characteristics of the studied compounds in DMF regarding their redox potential (Δ1/2); electron affinity (EA); ionization potential (IP); electronic transition energy (ECT) and coulomb repulsion integral (J12) were computed. A linear correlation was shown to exist between Δ1/2 and ECT.
Anaerobic biodegradability and toxicity of eucalyptus fiber board manufacturing wastewater
Authors: Soto M. , Field J. A. , Lettinga G. , Méndez R. , Lema J. M.
Published: July 2010

Wastewater from eucalyptus fiber board manufacturing (EFBM) was characterized and studied for its treatability by anaerobic digestion. The characteristics of the wastewater (in mg dm−3), are as follows: COD (42 000), SS (550), SO (1200), PO.P (50), NH.N (15), VFA (710), phenol (20), p‐cresol (125), tannin COD (1460) and pH 2.8. Approximately 60% of the COD is composed of carbohydrates.

The continuous treatment of EFBM wastewater resulted in 93% COD removal and 78% COD methanogenized, with influent COD values of 20 g dm−3 and OLR of 17 kg COD m−3 d−1. The biodegradation reached 94% of influent COD and 74% of influent ultraviolet absorbance (215 nm).

EFBM wastewater supplied at 20 g COD dm−3 (1:1 tap water diluted) caused 50% methanogenic toxicity, which did not disappear when tannins were removed by adsorption on PVP (polyvinylpyrrolidone). The toxicity decreased to 25% once the wastewater was autoxidized with air at high pH values. However, the effluent of the continuously fed column didn't show methanogenic toxicity, therefore the main toxic compounds in the wastewater were removed during anaerobic treatment.
Production and extractive biocatalysis of ethanol using microencapsulated yeast cells and lipase system
Authors: Oliveira A. C. , Cabral J. M. S.
Published: July 2010

An extractive biocatalytic process for in situ ethanol recovery from fermentation broths of high glucose concentration (200 and 400 g dm−3) was developed. In this system, ethanol was recovered by liquid‐liquid extraction and enzymatic reaction. Oleic acid was used as extractant, allowing the esterification of ethanol catalysed by a lipase from Mucor miehei. The distribution coefficient of ethanol between the aqueous and the organic phases was improved tenfold by esterification. The better performance of the extractive fermentations of ethanol was obtained when co‐immobilized Saccharomyces bayanus cells and a lipase from Mucor miehei in microemulsions of phosphatidylcholine were used. These results emphasize the important role of the surfactant in the protection of biocatalysts against organic phase toxicity.
On the solvent‐induced swelling of low‐rank coals
Authors: Jones J. C. , Boother M. , Brown M.
Published: July 2010

Swelling of low rank coals due to solvent contact is measured for a suite of such coals from different sources. The method is a simple one: the pouring of solvent on to samples of the coal in glass tubes and measurements of coal height before and after pouring on the solvent. Correlations between swelling and coal properties are discussed, and for one of the coals a ‘swelling spectrum’, displaying swelling as a function of solvent solubility parameter, is presented.
The Effects of Spore Loading on the Growth of Penicillium chrysogenum Immobilised in K‐Carrageenan
Authors: Mussenden Paul J. , Keshavarz Tajalli , Bucke Christopher
Published: July 2010

Penicillium chrysogenum spores were immobilised in K‐carrageenan. The effect of the number of viable spores immobilised per bead on the rate of germination and degree of subsequent mycelial growth was investigated. The distribution of active mycelium throughout the bead was determined. At a high spore loading (103−104 viable spores per bead) the biomass concentration was low and the majority of the actively respiring biomass was located at the bead periphery. Reducing the spore loading (to 50 viable spores per bead) resulted in a fourfold increase in immobilised biomass concentration. At very low spore loadings (5 and 10 viable spores per bead) the concentration of biomass decreased, but mass transfer throughout the bead improved and the uniformity of active immobilised biomass increased. The spore loading also affected the morphology of the growing hyphae and the extent of free cell growth.
Simultaneous removal of SO2, SO3 and H2SO4 mist from the gas after TiO2 calcining
Authors: Tilly Jadwiga , Tomaszewski Zbigniew , Toczkowski Jacek
Published: July 2010

Absorption of SO2 and SO3 in the solutions of waste ferrous sulfate (so‐called ‘green salt’) and in the spent acid after TiO2 hydrolysis, at H2SO4 concentrations ranging from 0–5 to 15 g/m3 (STP), was studied. The rate of SO3 absorption has been found to rise linearly with increasing SO3 concentration in the gas and to be independent on H2SO4 concentration in solution. The SO2 absorption also rises linearly with increasing SO2 content in the gas, but diminishes as H2SO4 concentration increases—an upper limit of 100 g H2SO4/kg H2O is indicated. The initial concentration of the solution must not be higher than 40 g H2SO4/kg H2O.
The uptake of copper from aqueous solution by immobilized fungal biomass
Authors: Zhou Jun L. , Kiff Robert J.
Published: July 2010

The removal of cupric ions from aqueous solution by a biosorption column in which the Rhizopus arrhizus fungal biomass was immobilized in reticulated foam biomass support particles was studied. Solution pH was found to be crucial to copper uptake, with the optimum range being 6·7–7·0. The removal efficiency was usually higher at low influent copper concentration and long residence time. The presence of other cations and anions inhibited copper uptake in the following order: for the cations, Mn2+ ≫ Zn2+ > Cd2+ > Mg2+ > Ca2+; for the anions, EDTA ≫ SO ≫ Cl−. The biosorption process was fully reversible and regenerated columns showed undiminished performance.
Spectrophotometric determination of uranium(VI) in bacterial leach liquors using arsenazo‐III
Authors: Bhatti Tariq M. , Mateen Abdul , Amin M. , Malik Kauser A. , Khalid Ahmad M.
Published: July 2010

A highly sensitive and precise spectrophotometric method for the direct determination of uranium(VI) in bacterial leach liquors, obtained by the action of Thiobacillus ferrooxidans and T. thiooxidans, from low‐grade sandstone uranium ores, has been developed, Arsenazo‐III formed an intense pink‐violet complex at pH 2·0 ± 0·1, which showed maximum absorption at 655 nm. This method was found to obey Beer's law up to 6 μg cm−3, giving the values of molar absorptivity (ϵ) and Sandell sensitivity (S) as 4·6 × 104 mol−1 cm−1 and 0·0052 μg cm−2, respectively. Interference due to different metal ions, such as Al, Ca, Co, Cr, Fe, Mn, Mo, Zn and Zr, was successfully masked by diethylenetriaminepenta‐acetic acid without inhibiting the formation of the uranium(VI)‐arsenazo‐III complex. This method was also found suitable for detecting low levels of uranium(VI) in mine waters, acid leach liquors and tailings liquids. The results obtained were found to be in close agreement with the values determined by fluoro‐metric and indirect spectrophotometric methods.
Activated sludge characteristics in relation to stable foam formation
Authors: Khan A. R. , Kocianova E. , Forster C. F.
Published: July 2010

This paper examines the hydrophobicity and the surface charge of a range of foaming and nonfoaming activated sludges, together with an appraisal of the species involved. The results show that the solids in foaming sludges possess a higher hydrophobicity than those in nonfoaming sludges. The data also indicate that there are two distinct hydrophobicity/surface charge trends, depending on whether the sludges are foaming or nonfoaming. Sludges in which Nostocoida limicola was the dominant species did not conform to these patterns. In addition, the stability of the foam formed by these sludges was significantly lower.
The effect of steam and hydrogen in promoting the oxidation of carbon monoxide over a platinum on alumina catalyst
Authors: Muraki Hideaki , Matunaga Shin‐Ichi , Shinjoh Hirofumi , Wainwright Mark S. , Trimm David L.
Published: July 2010

Steam‐ and hydrogen‐induced effects on carbon monoxide oxidation at temperatures below 200°C were studied over an alumina‐supported Pt catalyst. These studies were complemented by measurements of rate expressions and IR spectroscopy. CO oxidation activity over alumina‐supported Pt, Pd and Rh catalysts was found to be strongly promoted by the presence of steam and H2 in the feed gas. The promotion effect decreased in the order Pi>Pd> Rh. The water‐gas shift reaction did not occur under these experimental conditions. The steam and H2 enhancement effects are attributed to the weakening of self‐poisoning by CO.
Design considerations for an immobilized cell bioreactor operating in a batch recirculation mode
Authors: Lakhwala Fayaz , Sofer Sam
Published: July 2010

Immobilizing microbial cells and enzymes used in biological and biochemical processes is advantageous and has been a subject of intensive study in recent years. Successful implementation of this technology requires complete understanding of physical, chemical and biological parameters which influence the performance of such a system. This paper focuses on a few basic design considerations which are essential to the design and operation of immobilized cell bioreactors. A process using microorganisms entrapped in calcium alginate gel as a biocatalyst is considered. This system is used to biodegrade the organic compound, phenol. A batch reactor operated in a recirculation mode is used, and parameters like concentration of dissolved oxygen, concentration of the organic compound, bead size, biomass loading and the flow rate are studied. The bioreactor can be operated within many operating windows where one of the above parameters may be rate limiting. With the help of conceptual and experimental data, the influence of the above parameters on the reaction rates is discussed.