bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of ICAM‐1 mRNA stability by cycloheximide: Role of serine/threonine phosphorylation and protein synthesis
Authors: Ohh Michael , Takei Fumio
Published: May 2005

Cycloheximide is a protein synthesis inhibitor that superinduces the expression of many genes by preventing the degradation of otherwise labile mRNAs. In some genes this depends on the presence of the AUUUA destabilizing multimers in the 3′UTR. We examined the effect of cycloheximide on the murine intercellular adhesion molecule‐1 (ICAM‐1; CD54) gene expression in several cell lines including A20 (B cell lymphoma), T28 (T cell hybridoma), P388D1 (monocytic cell), SVEC4‐10 (lymphoid endothelial cell), and ICAM‐1‐transfected murine fibroblast L cells. Cycloheximide was indeed able to dramatically increase the accumulation of ICAM‐1 mRNA in all the cell lines examined except T28, and this seemed to be due to the stablization of the ICAM‐1 mRNA as indicated by the half‐life analysis. To determine whether this effect is dependent on the 3′UTR containing the AUUUA sequences, L cells were transfected with either the full‐length ICAM‐1 cDNA or a truncated form lacking the AUUUA sequences in the 3′UTR (ICAM‐1Δ3). There was no discernible difference in the effect of cycloheximide on ICAM‐1 mRNA accumulation or half‐life between the two types of transfected cells. The effect of cycloheximide on ICAM‐1 mRNA was markedly suppressed by serine/threonine (ser/thr) kinase inhibitors, H‐7 and staurosporine, whereas the ser/thr phosphatase inhibitor, okadaic acid, augmented the cycloheximide effect. Inhibitors of protein tyrosine kinases and phosphatases had no effect. Unexpectedly, the level of cell surface ICAM‐1 as well as de novo synthesis of ICAM‐1 in SVEC4‐10 and the ICAM‐1‐transfected L cells were also upregulated by cycloheximide, whereas the overall protein synthesis in these cells was profoundly inhibited, suggesting that ICAM‐1 protein synthesis in these cells escapes the translational inhibition by cycloheximide. These results suggest that the stabilization of ICAM‐1 mRNA by cycloheximide is independent of its translational inhibition and that ser/thr phosphorylation of unidentified protein(s) seems to play a crucial role in this effect. © 1995 Wiley‐Liss, Inc.
Involvement of protein phsophatase‐1 in cytoskeletal organization of cultured endothelial cells
Authors: Shinoki Nobutoshi , Sakon Masato , Kambayashi Jun‐ichi , Ikeda Masataka , Oiki Eiji , Okuyama Masaki , Fujitani Kazumasa , Yano Yoshiko , Kawasaki Tomio , Monden Morito
Published: May 2005

The phosphorylation and dephosphorylation of cytoskeletal proteins regulate the shape of eukaryotic cells. To elucidate the role of serine/threonine protein phosphatases (PP) in this process, we studied the effect of calyculin A (CLA), a potent and specific inhibitor of protein phosphatases 1 (PP‐1) and 2A (PP‐2A) on the cytoskeletal structure of cultured human umbilical vien endothelial cells (HUVECs). The addition of CLA (5 min) caused marked alterations in cell morphology, such as cell constriction and bleb formation. Microtubules and F‐actin were reorganized, becoming markedly condensed around the nucleus. Although the fluorescence intensity of phosphoamino acids was not significantly different to immunocytochemistry between cells with and without CLA, polypeptides of 135, 140, 158, and 175 kDa were specifically phosphorylated on serine and/or threonine residues. There was no significant effect on tyrosine residues. The effects of CLA on cytoskeletal changes and protein phosphorylation were almost completely inhibited by the non‐selective kinase inhibitor, K‐252a. The effect of CLA on cell morphology was at least 100 times more potent than that of okadaic acid, consistent with the inhibitory potency against PP‐1. The catalytic subunit of PP‐1 was also identified in HUVECs by Western blotting with its monoclonal antibody. These results suggest that PP‐1 is closely involved in sustaining the normal structure of the cytoskeleton. © 1995 Wiley‐Liss, Inc.
Glucocorticoids coordinately regulate type I collagen proα1 promoter activity through both the glucocorticoid and transforming growth factor β response elements: A novel mechanism of glucocorticoid regulation of eukaryotic genes
Authors: Meisler Natalie , Shull Susan , Xie Ronglin , Long George L. , Absher Marlene , Connolly Joseph P. , Cutroneo Kenneth R.
Published: May 2005

Glucocorticoids have previously been shown to decrease Type 1 collagen synthesis in vivo and in fibroblast cell culture. Several studies have demonstrated that glucocorticoids decrease Type 1 procollagen gene expression. These latter studies have included uridine incorporation into proα1(I) and proα2(1) mRNas and nuclear run‐off experiments. Using the ColCat 3.6 plasmid, which contains part of the 5' flanking regionof the proα1 (1) coullagen gene and the reporter gene, chljoramphenicol acetyltransferase, the present studies demonstrate by stable transfection of fetal rat skin fibrolblasts that dexamethasone down regulates the promoter activity of the proα1(I) collagen gene. The glucocorticoid‐mediated down‐regulastionof procolljagen gene expression was demonstrated using the ColCat 3.6, 2.4, 1.7, or 0.9 plasmid. In addition, competitive oligonucleotide transfection experiments and site specific mutation of the glucocorticoid response element (GRE) in the whoulue ColCat 3.6 plasmid did not elimiinatre the effect. The ipossibility existed that another cis‐element inthe 5' flanking region of the proα1(I) collagen gene was also required for the glucocorticoid‐mediated down‐regulation of procollagen gene expression, since TGF‐β has been shown to stimulate collagen proα1(I) and proα2(I) gene activities. Dexamethasone treatment of non‐transfected skin fibroblasts did result in a decrease of transforming growth factor‐β. The decrease of CVAT activity by dexamethasone was brought back to control value by the addition of exogenous TGF‐β to the culture media. Gel mobility studies demonstrated that glucocorticoid treatment of rat skin fibroblasts decreased glucocorticoid recptor binding to the GRE and TGF‐β activator protein to the TGF‐β element which were brought back to control values by coordinate exogenous TGF‐β treatment. Thus the interaction of these TGF‐β molecules with cellular membrane receptors and subsequent rtransduction is dramatically decreased resulting in less signals to regulate collagen gene expression. These data indicate that glucocorticoids coordinately regulate procollagen gene expfrssion through both the GRE and TGF‐β elements. Depression of procollagen gene expression by glucocorticoids through the TGF‐β element is mediated by decreased TGF‐β secretion, possibly involving a secondary effect on regulatory protein(s) encoded by noncollagenous protein gene(s). The present studies provide the bassis for a novel mechanism of glucocorticoid‐mediated regulation of eukaryotic genes containing the TGF‐β element. © 1995 Wiley‐Liss, Inc.
Phosphorylation of elF‐4E and initiation of protein synthesis in P19 embryonal carcinoma cells
Authors: Kleijn Miranda , Voorma Harry O. , Thomas Adri A. M.
Published: May 2005

Mitogenic stimulation of protein synthesis is accompanied by an increase in elF‐4E phosphorylation. The effect on protein synthesis by induction of differentiation is less well known. We treated P19 embryonal carcinoma cells with the differentiating agent retinoic acid and found that protein synthesis increased during the first hour of addition. However, the phosphorylation state, as well as the turnover of phosphate on elF‐4E, remained unchanged. Apparently, the change in protein synthesis after RA addition is regulated by another mechanism than elF‐4E phosphorylation.

By using P19 cells overexpressing the EGF receptor, we show that the signal transduction pathway that leads to phosphorylation of elF‐4E is present in P19 cells; the EGF‐induced change in phosphorylation of elF‐4E in these cells is likely to be regulated by a change in elF‐4E phosphatase activity.

These results suggest that the onset of retinoic acid‐induced differentiation is triggered by a signal transduction pathway which involves changes in protein synthesis, but not elF‐4E phosphorylation. © 1995 Wiley‐Liss, Inc.
Cyclic‐AMP deficient MDCK cells form tubules
Authors: Klebe Robert J. , Grant Anne , Grant George , Ghosh Paramita
Published: May 2005

It has known for many years that MDCK cells blister structures, termed domes. During an examination of the morphbology of a large number of MDCK clones, we found that two stable morphotypes exist in an MDCK cell population namely, dome‐forming and tubule‐forming clones. When maintained at high cell density, tubule‐forming clones displayed large numbers of anastomosing tubules which contained lumens. The frequency of obseration of the tubule forming clones in an MDCK population was 0.7% Tubule‐forming MDCK clones should be useful in studying tubule morphogenesis. While agents that affect protein kinase A actiity increased dome formation, the same agents abolished the formation of tubules in all tubule‐forming clones. In contrast, drugs that stimulate protein kinase C actity (phorbol esters and staurosporine) decreased dome formation and increased tubule morphogenesis in all MDCK morphotyes. Tubules‐forming clones were found to have lower resting levels of cyclic‐AMP and to respond to forskolin stimulation of adenylate cyclase readily. Hence, sigals transmitted by the protein kinase C pathway appear to lead to tubule formation MDCK cells, while signals transmitted through the protein A pathway lead to dome formation. © 1995 Wiley‐Liss, Inc.
Microbial distribution throughout a cellobiose‐supplemented three‐stage laboratory‐scale anaerobic digester
Authors: Howgrave‐Graham Alan G. , Jones L. Robin , James A. Gordon , Terry Sandra J. , Senior Eric , Watson‐Craik Irene A.
Published: May 2005

Substrate and intermediate metabolite degradation were monitored in a three‐stage anaerobic digester fed cellobiose as sole carbon source. The digester vessels were of different sizes and the resultant different dilution rates enabled separation of the trophic groups. Biofilms were allowed to develop on microscope slides suspended at different depths within each vessel and these were examined using phase contrast and fluorescence microscopy. Cell quantification was performed on these and planktonic samples using image analysis. All cellobiose degradation and sulphate reduction and most of the acidogenesis was performed in the first vessel, by an activated sludge‐like population (attached or in flocs). Eighty percent of the methanogenesis and some acetogenesis occurred in the second vessel where populations of attached fluorescent rods and Methanosarcina‐like cells were abundant. The low population levels in the third vessel were responsible for 8% of the total methanogenesis.
Effect of chromium promoter on copper catalysts in ethanol dehydrogenation
Authors: Tu Yau‐Jen , Li Chiuping , Chen Yu‐Wen
Published: May 2005

A series of chromium‐promoted copper catalysts with various Cr to Cu molar ratios were prepared with the co‐precipitation method. The promotional effects of chromium on copper catalysts were examined by X‐ray powder diffraction (XRD), nitrous oxide decomposition, and the dehydrogenation reaction of ethanol. The dehydrogenation reaction was carried out in a continuous‐flow microreactor between 523 and 583 K under atmospheric pressure. The results indicated that the promotional effect was dependent on the Cr/Cu molar ratio, and the predominant decay of catalysts in this study was caused by sintering. The catalyst with the Cr/Cu molar ratio of 4/40 has the highest activity and stability. The surrounded well‐dispersed chromia strongly influenced the catalytic properties of copper metal. It also showed that the over‐promotation of a catalyst has a disastrous effect on the total make of product. The ethanol dehydrogenation reaction follows a first‐order reaction, and the kinetics for deactivation can be described by a second‐order expression.
MoO3—Fe2O3 catalysts: Characterization and activity for isopropyl alcohol decomposition
Authors: Bond Geoffrey C. , Halawy Samih A. , Abd El‐Salaam Khalafalla M. , Hassan Ehsan A. , Ragih Hesham M.
Published: May 2005

The vapour‐phase dehydration and dehydrogenation of isopropyl alcohol (IPA) have been carried out over pure MoO3 and Fe2O3, produced by calcination of ammonium heptamolybdate and of iron (III) nitrate respectively, as well as MoO3 mixed with 0·5 and 50 mol% Fe2O3, prepared from the same materials. All catalysts were calcined in air, in the temperature range 200–600°C for 5 h, and were characterized by thermal analysis (TG, DTA), XRD, IR and SBET. Surface areas decreased with increasing calcination temperature, and the catalytic activity of the pure oxides MoO3 and Fe2O3, as well as of MoO3–0.5 mol % Fe2O3, increased with their SBET. The activity of MoO3–50 mol % Fe2O3, which was independent of its SBET, could be attributed to the increased intensity of terminal Mo—O bonds as shown by IR spectra. The activation energies for the decomposition of IPA over catalysts calcined at 250 and 500°C are tabulated.
Methylcyclohexane dehydrogenation on Rh/γ‐Al2O3 catalysts
Authors: Reyes Patricio , Orellana Fresia , Pecchi Gina
Published: May 2005

The influence of the Rh loading on the surface properties and catalytic behaviour of Rh/γ‐Al2O3 catalysts has been studied. The series of catalysts presents differences in metal dispersion, reducibility, surface composition and catalytic activity. All the data reported suggest that the differences in catalytic behaviour in the methylcyclohexane dehydrogenation reaction can be explained in terms of electron‐deficient rhodium clusters, essentially when the metal particle size becomes smaller than 15 Å.
Biocatalysis of chlorophyllase from Phaeodactylum tricornutum in a biphasic organic system
Authors: Khamessan Ali , Kermasha Selim , Ismail Ashraf A. , Marsot Pierre
Published: May 2005

The hydrolytic activity of a partially purified chlorophyllase, obtained from the alga Phaeodactylum tricornutum, was determined in a biphasic organic system using different mixtures of hexane and Tris–HCl buffer solution (20 mmol dm−3, pH 7·5). The most appropriate kinetic parameters were determined for the optimum hydrolytic activity of chlorophyllase including hexane concentration (45%), optimum pH (7·5), time of incubation (7 h), incubation temperature (25°C) and enzyme concentration (10 μg cm−3). The optimum concentrations of magnesium chloride and dithiothreitol, used as activators, were determined to be 4 mmol dm−3 and 5 mmol dm−3, respectively. The results also indicated that diisopropyl fluorophosphate (DIFP) had a mixed competitive–non‐competitive inhibitory effect on chlorophyllase activity. The end‐products of the chlorophyllase hydrolytic reaction were identified and confirmed, using thin‐layer and high‐performance liquid chromatographies, spectrophotometric scanning and Fourier transform infrared spectroscopy.
Influence of pH on the acid‐phase anaerobic digestion of primary sludge
Authors: Elefsiniotis Panagiotis , Oldham William K.
Published: May 2005

This study explored the effect of pH on the acid‐phase anaerobic digestion of primary sludge. Controlled and uncontrolled pH experiments were conducted using two bench‐scale, continuous‐flow reactors having different configurations: a completely mixed reactor (CMR) with clarifier and solids recycling, and an upflow anaerobic sludge blanket (UASB) unit. Results indicate that the specific rates of VFA production and COD solubilization, in either system, were not affected by the variation in pH between 4·3 and 5·2, but at higher pH values (5·9–6·2) a significant decline (by 25–30%) in both parameters was observed. Analysis of the degradation behavior of the three important organic classes (carbohydrates, proteins, and lipids) revealed that each class followed an individual trend with respect to pH changes. Acetic acid was the major end‐product of acidogenic digestion in both reactors, regardless of pH. The percent VFA distribution did not appear to be influenced by pH variation, except for propionic and butyric acids. Besides VFAs, small amounts of formic acid, ethanol, and lactic acid were also formed at all pH values tested.
Evaluation of the performance of immobilized enzyme reactors with michaelis—menten kinetics
Authors: Lortie Robert
Published: May 2005

Two dimensionless models, taking into account the external mass‐transfer, are used to characterize and compare the behaviour of plug flow reactors (PFR) and continuous stirred tank reactors (CSTR). These models need only two parameters, the Damköhler number and the Stanton number, to cover all the range of operating conditions. The conversion and a new dimensionless number, quantifying the use of the enzyme, are calculated for different values of the Damköhler and Stanton numbers.
Synthesis and biological evaluation of some new sulfur‐containing heterocycles as possible antifungal agents
Authors: Hanna Mokhtar A. , Khodeir Mohamed N. , Mashaly Mohamed A. , El‐Shafei Hussain M.
Published: May 2005

Some novel sulfonate ester‐containing mono‐, bi‐ and tricyclic fused ring systems (IV, Xa,b, XIa,b, XIV and XV) together with their precursors I, II and III were synthesized with a view to evaluating their efficacy as new sulfur‐containing fungitoxic agents. The structures of the named compounds were established from elemental and spectral analyses.
Catalysis by intermetallic compounds I. A comparison of the catalytic behaviour of CePd3, ZrPd3 and Pd sponge for buta‐1,3‐diene hydrogenation and but‐1‐ene hydroisomerisation
Authors: Bahia Amrik , Winterbottom John M.
Published: May 2005

The hydrogenation of buta‐1,3‐diene and more briefly, the hydroisomerisation of but‐1‐ene catalysed by powdered CePd3, ZrPd3 and Pd sponge has been studied in a fixed bed continuous flow microreactor at 1 bar (101·5 k Pa) total pressure and in the temperature range 45–225°C. The two intermetallics (CePd3, ZrPd3) exhibited greater selectivity for butene formation than palladium, especially at high buta‐1,3‐diene conversions. The superior selectivity of the intermetallics was demonstrated further under the more demanding conditions, whereby but‐1‐ene was added to the feed buta‐1,3‐diene in the ratio C4H8/C4H6 = 24. The kinetics and apparent energies of activation were determined for the hydrogenation and isomerisation reactions. In the case of buta‐1,3‐diene hydrogenation, the kinetics suggest that for Pd sponge, hydrogen and buta‐1,3‐diene adsorb on similar sites, whereas in the case of the intermetallics different sites may be involved for hydrogen and buta‐1,3‐diene adsorption, which may result from palladium—metal oxide interactions. In the case of but‐1‐ene isomerisation, double bond migration appears to occur via addition–abstraction mechanisms on all three catalysts but in the case of the intermetallics hydrogenation and isomerisation involve different rate determining steps.
A simple model for estimating protein solubility in aqueous polymer solutions
Authors: Yu Ming , de Swaan Arons Jakob , Smit Jan A. M.
Published: May 2005

A simple scaling analysis of protein solubility in semi‐diluted polymer aqueous solutions was derived based on the recent theoretical development of Abbott et al.1 on the interactions between protein spheres and entangled polymer coils and the experimental observations of Atha and Ingham2 on the polymer‐induced protein precipitation. Both the hard‐sphere nature of the protein and the flexibility of the polymer coils have been taken into account in the model. The experimental data can be fitted by using this model with physically reasonable values of the exponent. This approach may be useful in estimating protein solubilities in water in the presence of polymer from limited and usually costly experimental data.
Solubilization of bituminous and lignite coals by chemically and biologically synthesized surfactants
Authors: Polman J. Kevin , Miller Karen S. , Stoner Daphne L. , Breckenridge Cynthia R.
Published: May 2005

Tween 80 (polyoxyethylene sorbitan monooleate), Triton X‐100 (nonaethylene glycol octylphenol ether), and SDS (sodium dodecyl sulfate) solubilized several components of Mississippi Wilcox lignite and Illinois No. 6 bituminous coal. Tween 80 extraction of alkali‐soluble Ugljevik lignite resulted in an increase in hydrogen content and decreases in the nitrogen and sulfur contents of undissolved coal solids. Biosurfactant‐containing cell‐free extracts of Bacillus licheniformis solubilized a 53 000 Da coal component of Mississippi Wilcox lignite. The results suggest that solubilization of coal organic components by chemically‐ and biologically‐synthesized surfactants has potential in terms of upgrading coals.
Combined bioreaction and separation in centrifugal fields using zonal rotors
Authors: Setford Steven J. , Barker Phillip E.
Published: May 2005

Combined biosynthesis and product separation has been successfully performed for the first time using a zonal centrifugal bioreactor–separator. The biosynthesis of dextran polymer from sucrose using the dextransucrase enzyme was investigated in order to evaluate bioreactor performance. The bioreactor consisted of a bowl, fitted with a Reorienting gradient rotor which facilitated substrate and enzyme loading and the reproducible unloading of solutions from the system. This allowed the distribution of substrate, enzyme and product materials in the bowl at the end of each trial to be accurately determined. Studies have indicated that combined bioreaction–separation is possible using this system. However, viscosity build‐up in the bioreactor must be minimised in order to increase the yield of polymer product per unit time and improve product separation.
Stability of a mineral membrane ultrafiltration reactor for peptide hydrolysis of hemoglobin
Authors: Sannier Frédéric , Piot Jean‐Marie , Dhulster Pascal , Guillochon Didier
Published: May 2005

Factors involved in the activity decay of an ultrafiltration reactor during the hydrolysis of hemoglobin by pepsin were studied. Biochemical and hydrodynamic parameters were assessed. The product of hydrolysis showed no inhibitory effect. Autolysis and mechanical damage of pepsin were limited by the presence of hemoglobin. Activity decay was mainly a result of the leakage of pepsin through the membrane. Electrostatic charges carried by either hemoglobin or pepsin were involved in the permeation process.
Comparative sorption kinetic studies of phenolic compounds on fly ash and impregnated fly ash
Authors: Singh Binay K. , Rawat Narendra S.
Published: May 2005

The factors affecting the rate processes involved in the removal of phenolic compounds, e.g. initial phenol concentration, particle size, impregnation of fly ash (IFA), pH and temperature have been studied. The removal rate of phenols varied in the order p‐nitrophenol m‐nitrophenol > o‐nitrophenol > p‐cresol > phenol > m‐cresol > o‐cresol. The process followed first order rate kinetics. The sorption data generally fit the Lagergren equation and the intraparticle diffusion rate equation from which adsorption rate constants, diffusion rate constants and diffusion coefficients were determined. Intraparticle diffusion was found to be the rate‐limiting step. These kinetic parameters were compared for various phenols under different conditions using fly ash (FA) and impregnated fly ash (IFA).
A description of three methods for the determination of the initial inert particulate chemical oxygen demand of wastewater
Authors: Orhon Derin , Artan Nazik , Ateş Esra
Published: May 2005

Three different methods are described for the determination of the initial inert particulate organics, measured in terms of COD. The methods involve experimental procedures using batch reators and are designed to differentiate residual particulate products generated by metabolic activities during the treatment processes. In the first method, the final threshold value of the particulate COD is monitored in an aerated batch reactor fed by the initial total COD. The second method uses the threshold values of the total and soluble COD in two parallel batch reactors, one fed with unfiltered and the other with filtered wastewater. The third method involves running three batch reactors, two with the wastewater to be studied and the thired with glucose. One method has been experimentally tested to assess the inert particulate fractions of domestic and textile wastewaters.
Optimization of experimental conditions for the catalytic oxidation of furfural to furoic acid
Authors: Verdeguer Philippe , Merat Nadine , Rigal Luc , Gaset Antoine
Published: May 2005

Oxidation of furfural in a stream of oxygen in aqueous alkaline medium in the presence of a lead–platinum catalyst leads to the formation of furan 2‐carboxylic acid. The influence of five factors was studied using a Doehlert matrix. The analysis of the areas of responses allowed the optimal operating conditions to be determined: platinum metal mass/furfural mass introduced × 100:1·7%; lead diacetate mass/platinum on carbon mass: 20%; initial furfural concentration 0·8 M; temperature 55°C. After 1 h of reaction, the whole of the furfural is then selectively transformed into furoic acid.
Measurement of bound water in waste activated sludge: Use of the centrifugal settling method
Authors: Lee Duu‐Jong
Published: May 2005

The feasibility of employing a centrifugal settling method for measuring the bound water content in waste activated sludge was investigated. The results demonstrated that, for such highly compressible sludge, the centrifugal settling test can only provide information about the cake compressibility and the method proposed by Matsuda and colleagues fails. A method combining vacuum filtration tests and centrifugal settling tests for estimating the bound water content is proposed and compared with expression tests. The agreement was close.
A mathematical model of microalgal growth in light‐limited chemostat culture
Authors: Grima E. Molina , Camacho F. García , Pérez J. A. Sánchez , Sevilla J. M. Fernández , Fernández F. G. Acién , Gómez A. Contreras
Published: May 2005

A mathematical model for light‐limited growth of a continuous microalgal culture is proposed. Average light intensity inside the photobioreactor was calculated, taking light attenuation by algae into account. The biomass absorption coefficient was determined by means of two new parameters, the pigment‐free biomass, YB, and the total pigment absorption, Yp (absorption coefficient normalized to total pigment content). The model reproduced the steady states reached and the dynamic behaviour of the system when the dilution rate was changed.
Preparation of membrane‐immobilised enzymes for phenol decomposition
Authors: Bodzek Michał , Bohdziewicz Jolanta , Kowalska Małgorzata
Published: May 2005

A method for the preparation of membranes with immobilised enzymes for the biological degradation of phenols is described. In the first stage, an enzymatic fraction from bacterial strains has been isolated. The enzyme membranes were obtained by ultrafiltration of protein solution through a membrane support made of non‐cellulose polymers. All enzymes were adsorbed onto the membrane surface. The enzyme membranes were found to degrade 70–80% of the phenol during single dead‐end ultrafiltration at a pressure of 1 × 105−3 × 105 Pa. The retention coeffcient of the ultrafiltration process also amounted to 70–80%.
Dehydrochlorination of propylene chlorohydrin with sodium hydroxide and with catholyte
Authors: Milchert Eugeniusz , Goc Waldemar , Meissner Egbert , Myszkowski Jerzy
Published: May 2005

Dehydrochlorination of an aqueous solution of propylene chlorohydrin with sodium hydroxide (12·5 and 30% by weight), with catholyte (5 or 10% by weight NaOH + 14% by weight NaCl) and with milk of lime (15% by weight) were compared. The use of catholyte (10% by weight NaOH + 14% by weight NaCl) enables propylene oxide to be obtained in a yield of 94·3%, with 100% conversion of chlorohydrin. The concentration of 1,2‐propylene glycol in the waste is 0·07% by weight.
Estimation of true biomass energetic yield and maintenance coefficient with errors in the variables
Authors: Solomon Bamidele O. , Erickson Larry E. , Yang Shie‐Shien , Posten Clemens , Deckwer Wolf‐Dieter
Published: May 2005

Simple regression analysis is based on the least square of residual errors. To use this method, an independent variable which is observable without error is assumed to exist. For most analyses, the assumption is normally made without realising the implications. The present study demonstrates how parameters may be estimated with the assumption of error in all measurements. Data sets involving batch/fed‐batch cultivation ofCandida utiliswere analysed using a statistical approach with error in variables for the estimation of true biomass energetic yield and maintenance coefficient. This approach requires replicated measurements. For linear systems, such as in chemical/biochemical processes, replicated measurements are sometimes possible or there are physical/physiological reasons to group the observations into clusters. When clusters of replicated measurements are not available, the cluster analysis technique may be used to identify groups of near‐replicated data points. The procedure yielded similar results to those obtained by the ordinary least squares procedure for consistent data. However, for data of poor quality (especially data with large errors in the independent variable), the disparity between the two procedures was more significant.
Characterization of the intermediate product of coal solubilization by Penicillium simplicissimum
Authors: Achi Ome K.
Published: May 2005

Penicillium simplicissimum has previously been shown to solubilize pre‐oxidized alkali‐extracted sub‐bituminous coal. The product of solubilization, a soluble acid‐precipitable coal polymer, was isolated and characterized. The effects of oxidation pretreatments on the ability to solubilize coal were also examined. The intermediate product, which comprised 30% of the original coal, was readily recovered from the growth medium by acid precipitation and possibly consisted of a heterogeneous mixture of high‐molecular‐weight compounds of approximately 2·7 × 104 molecular weight. Further characterization by elemental analyses revealed that the bioproduct was enriched in inorganic materials, oxygen, nitrogen but lower in carbon, hydrogen and sulphur when compared with the original coal. A 14% loss of carbon atoms occurred during the biodegradation. The product had a featureless visible light spectrum and a shoulder in the ultraviolet range at 290 nm. Infrared analyses showed a decrease in aromatic carbons, methylenic bonds and etheric oxygen. Experimental results suggested that solubilization changes appear to be largely oxidative and may involve cleavage of intermonomeric linkages in coal.
Micromixing and the steady‐state performance of bioreactors using recombinant bacteria—analysis through a reversed two‐environment model
Authors: Patnaik Pratap R.
Published: May 2005

A reversed two‐environment model has been to study micromixing in continuous fermentation for growth and product formation by recombinant bacteria. As an example, an Escherichia coli M72 strain harbouring the plasmid pPLc23trpA1 and producing tryptophan synthetase is considered. With excess substrate, 10% plasmid‐free bacteria in the initial broth do not affect the steady‐state concentrations of plasmid‐containing bacteria but their mass fractions decrease significantly. With a smaller substrate concentration, the mass fractions decrease sharply as the dilution rate increases if micromixing is good; but concentrations still remain high. There is also a clear demarcation between regions of good and poor micromixing. These results are explained and an optimal combination of micromixing and dilution rate is suggested to maximise productivity.
Azo disperse dyes for synthetic fibres. I: 2‐Methyl‐ and 2‐phenylquinazolone derivatives
Authors: Fadda A. A. , Etman H. A. , Amer F. A. , Barghout M. , Mohamed Kh. S.
Published: May 2005

Ten variously substituted derivatives (IVa–j) of 4′(quinazol‐4‐on‐3‐yl) azobenzene were prepared. The effects of the nature and orientation of the substituents on the colour and dyeing properties of these dyes on polyester and acrylic fibres were evaluated.
Recovery of chromium from tannery effluents using a redox–adsorption approach
Authors: O'Dwyer Thomas F. , Hodnett Benjamin K.
Published: May 2005

Adsorption isotherms for sodium and trivalent chromium uptake from aqueous solutions onto Amberlite resin were prepared at 18°C. Adsorption of each cation followed the Langmuir model. The rate of uptake of each cation was found to be film diffusion controlled with sodium showing the most rapid uptake. In aqueous solutions containing both chromium and sodium as the only cationic species, it was found that with increasing initial concentration of sodium, the trivalent chromium uptake on the resin decreased substantially. To overcome this difficulty a four step redox–adsorption system has been developed for the removal of Cr3+ from tannery effluents. The first step comprises the oxidation of trivalent chromium to the hexavalent form using selected common oxidising agents. The liquid effluent is then passed through an Amberlite cation‐exchange resin in step 2 where the sodium in the waste stream is completely removed. The anionic hexavalent form of chromium (Cr2O) passes unaltered through the resin along with the waste stream. In the third stage the dichromate is reduced back to the trivalent cationic form which is subsequently removed from the waste stream by a second Amberlite ion‐exchange bed in stage 4. Each step in this process is assessed in batch and flow mode using simulated and real tannery effluents.
Ethanol production by alginate immobilised yeast in a fluidised bed bioreactor
Authors: Gilson Christopher D. , Thomas Adrian
Published: May 2005

Yeast, immobilised in alginate beads of known standard size and mechanical strength, has been utilised in a novel design of fluidised bed bioreactor which avoids problems of particle flotation and gas logging. Circulating substrate simultaneously entered the top and bottom of the bed. The bioreactor operated reliably for periods of up to 20 days. Increasing alginate concentration in the range 1–5% (w/w) had little effect on the performance of the immobilised yeast in converting ethanol to glucose but reduced the tendency of beads to split. Increasing bead diameter in the range 1–5 mm increased the tendency to split and reduced overall conversion of glucose. A model was developed to describe the consumption of glucose within beads based on Michaelis–Menten kinetics and the diffusion of glucose into beads. Application of the model to experimental results showed maximum reaction velocity to be independent of bead diameter and alginate concentration. The model confirmed that the observed reduction in ethanol yield compared with free yeast cells was caused by the lower substrate concentration towards the centre of the bead as opposed to any change in the metabolic rate of the immobilised cells.
Separation of di‐ and tripeptides with solvent extraction and an emulsion liquid membrane
Authors: Hano Tadashi , Matsumoto Michiaki , Kawazu Takahisa , Ohtake Takaaki
Published: May 2005

The extraction equilibria of various di‐ and tripeptides with di‐2‐ethylhexylphosphoric acid (D2EHPA) were studied at low pH values. The complex extracted to organic phase consisted of one molecule of peptide and two molecules of D2EHPA dimer. The extraction constants of the peptides correlated well with the distribution coefficients of peptides between 1‐octanol and water, which is a measure of hydrophobicity. The permeation rates of peptides through an emulsion liquid membrane were examined by using D2EHPA as a carrier, Span 80 as an emulsifier and kerosene as a diluent. The rates varied considerably with peptide type, depending upon the hydrophobicity.
Synthesis and evaluation of alkyl fumarate–vinyl acetate copolymers in combination with alkyl acrylates as flow improvers for Borholla crude oil
Authors: Borthakur Arun , Laskar Narayan C. , Mazumdar Ranjit K. , Rao Kosuru V. , Subrahmanyam Bulusu
Published: May 2005

A number of alkyl fumarate–vinyl acetate copolymers were prepared and evaluated as flow improvers for high waxy Borholla crude oil. Alkyl fumarate–vinyl acetate copolymers having 19·2 as the average carbon number of the alkyl group in combination with polybehenyl acrylate were found to show optimum activity. Alkyl fumarate–vinyl acetate copolymers reduce the pour point, plastic viscosity and yield stress considerably and polybehenyl acrylate prevents the crude oil from attaining the gel structure on prolonged storage.
Synthesis of linear alkylbenzene in a liquid–solid circulating fluidized bed reactor
Authors: Liang Wugeng , Yu Zhiqing , Jin Yong , Wang Zhanwen , Wang Yao , He Mingyuan , Min Enze
Published: May 2005

The alkylation reaction of benzene with 1‐dodecene was investigated in a liquid–solid circulating fluidized bed reactor (LSCFBR) using HY zeolite as catalyst. The conversion of 1‐dodecene, the apparent reaction rate constant, the activity of catalyst and the product distribution in the LSCFBR were analysed and compared with the values obtained using a stirred tank batch reactor (STBR).
Influence of power input and aeration method on mass transfer in a laboratory animal cell culture vessel
Authors: Moreira José L. , Cruz Pedro E. , Santana Paula C. , Feliciano Ana S. , Lehmann Jurgen , Carrondo Manuel J. T.
Published: May 2005

Large‐scale animal cell operation is costly both in terms of facilities and consumables. Hence developmental studies with animal cells normally start at laboratory scale, often using small stirred tanks. In order to better optimise cell performance, it is necessary to know the physical conditions under which the cells are grown. In this study a laboratory‐scale vessel (2 dm3 working volume) with two large‐bladed paddle impellers was characterised hydrodynamically. Three different aeration methods (surface, sparging and membrane aeration) were investigated and compared. Power input and oxygen transfer rates to culture medium were determined as a function of agitation and gas flow rates. Non‐dimensional correlations were established for each case, which can be useful for scale‐up purposes. The results obtained indicate that power input is quite dependent on the vessel accessories: for the same agitation rate, the maximum power is required for the membrane structure and the minimum for surface aeration, with the addition of the sparger leading to an intermediate situation. Predictions found in the literature can be used for simple vessels, but may not be applicable when accessories are added to the vessel structure; in such cases, the use of experimental relationships are required. Oxygen transfer rate was dependent on the aeration method and working conditions (agitation and gas flow rates), particularly for sparger aeration. Membrane aeration gave larger oxygen transfer but higher gas pressure and flow rates were required. Surface aeration was the least effective method, nevertheless requiring gas flow rates similar to those used for membrane aeration. The aeration method of choice depends upon the culture and work specificities: surface aeration is limited to small cell concentrations and low oxygen consumption rates. For higher cell concentrations and oxygen consumption rates, both membrane and sparger aeration methods can be applied: the use of the sparger is limited to cells that are not affected by the presence of bubbles or the addition of surfactants, whereas the membrane aeration basket should not be used when a hydrodynamically controlled stirred tank is required.
Metal sorption with extractant‐impregnated macroporous resins. 1. Particle diffusion kinetics
Authors: Juang Ruey‐Shin , Lin Horng‐Chyuan
Published: May 2005

Kinetic measurements were made for the sorption of copper ions from aqueous sulfate solutions with di(2‐ethylhexyl)phosphoric acid‐impregnated Amberlite XAD macroporous resins in finite bath by a batch‐contact time method. The sorption process of copper was first determined to be controlled by particle diffusion using a modified shrinking‐core mechanism, which considered reversibility of the sorption. A more rigorous model based on Fick's law was then applied to justify the applicability of the modified shrinking‐core model to the present sorption systems. The effective particle diffusivity had an order of 10−12 (in m2 s−1), which was in agreement with those obtained for chelating ion‐exchange processes.
Composition and interfacial activity of hydrophobic sulphide‐type extractants
Authors: Dziwiński Euzebiusz , Cote Gerard , Bauer Denise , Szymanowski Jan
Published: May 2005

The composition and interfacial activity of dihexyl sulphide (Elf), dodecyl methyl sulphide (two samples from Elf and Penwalt) and n‐dodecyl hydroxyethyl sulphide (Elf) which are commercially available sulphide‐type extractants have been investigated. Recrystallized n‐dodecyl hydroxyethyl sulphide was found to be of high purity (i.e. impurities, if any, are below the detection level of a gas chromatograph equipped with an efficient capillary column), whereas it was shown that all the other sulphides contained many components which were separated and, for most of them, indentified by a GC/MS technique. Recrystallized n‐dodecyl hydroxyethyl sulphide starts to adsorb at the 2 M HCI/dodecane interface at concentrations (typically 10−3 M) of about one order of magnitude lower than dodecyl methyl sulphide (Elf or Penwalt). Dihexyl sulphide exhibits a very weak interfacial activity and the observed decrease in the interfacial tension in the system containing about 0·4 M dihexyl sulphide cannot be attributed with certainty to its own interfacial activity.
Complexation behavior of proteins with polyelectrolytes and random acrylic polyampholytes using turbidimetric titration
Authors: Nath Sunil
Published: May 2005

The complexation behavior of proteins with dilute solutions of a polyelectrolyte (polyacrylic acid) and a random acrylic polyampholyte composed of acrylic acid, dimethylaminoethyl methacrylate and methyl methacrylate was experimentally investigated using turbidimetric titration. The random polyampholyte had a number‐average molecular weight of 70,000 and a polydispersity index of only 1·3. Polyampholyte–polyampholyte interaction (self‐aggregation) and polyampholyte–protein complexation behavior was studied as a function of pH (3–9) and polymer dosage (50–400, 5000 mg polymer per g protein). Large increases in turbidity (>500%) were observed for protein–polyampholyte mixtures (compared with polyampholyte alone). However, protein analysis of the supernatant and precipitate after centrifugation revealed that only about 10% of the protein precipitated with the random polyampholyte while 90% of the protein remained in the equilibrium liquid. This implies that a very small degree of protein–polymer interaction can lead to unusually large increases in turbidity. Experiments with a single polyelectrolyte (polyacrylic acid) and oppositely‐charged protein showed the opposite trend with 90% precipitation of protein. Hence, great care needs to be taken in interpretation of turbidimetric titration data.
Friction on a solid sphere exposed to gas–liquid and gas–liquid–solid flow in bubble column and fluidized bed reactors
Authors: Essadki H. , Delmas H. , Svendsen H. F.
Published: May 2005

Local velocity gradients on a solid spherical surface have been studied in a bubble column and in two‐ and three‐phase fluidized beds, in order to clarify the influence of gas flow. The electrochemical method, measuring apparent local mass transfer coefficients, was verified and used to obtain the local velocity gradients, shear stresses and total frictional forces. The observed mass transfer rate was independent of liquid velocity, owing to a non‐changing flow structure around the particles and not to averaging opposing effects. The identity in flow structure also held for three‐phase fluidized beds up to a superficial gas velocity of 5 cm s−1. The dramatic increase in velocity gradient on gas introduction was not a result of decreased homogenous density, but was caused by a change in the turbulent structure around a particle, leaving a larger portion of the total drag as frictional drag, thus improving the mass transfer characteristics of the bed. Use of velocity gradient measurements, including span of fluctuations and exposure time, to predict biomass growth and mechanical degradation in a reactor is also discussed.
Clean technology—an introduction
Authors: Clift Roland
Published: May 2005

A Clean Technology is a means of providing a human benefit which, overall, uses less resources and causes less environmental damage than alternative means with which it is economically competitive. Life Cycle Assessment is central to Clean Technology, as the way to identify overall resource usage and environmental damage. Pollution Prevention and Waste Minimisation are important parts of Clean Technology, but more fundamental is the shift from selling products to providing services. Some specific technological challenges for the chemical and biotechnology industries are identified.
Homogeneous and heterogeneous catalytic reactions in a cobalt oxide/graphite air electrode. Part IV. Mechanistic studies on a ring‐disk carbon electrode in alkaline solution
Authors: Yang Y. , Tseung A. C. C. , Lin Z. G.
Published: May 2005

The redox properties of HCoO on a glassy carbon electrode in the absence and presence of hydrogen peroxide have been investigated by using cyclic voltammetry and UV‐Vis spectroscopy in alkaline solution. Corresponding rotating ring‐disk experiments showed that the disk current increased by about 60% in the presence of HCoO, confirming the important role played by HCoO in the homogeneous decomposition of hydrogen peroxide.
Recovery of vanadium and nickel in fly ash from heavy oil
Authors: Akita Shigendo , Maeda Tsuyoshi , Takeuchi Hiroshi
Published: May 2005

Recovery of vanadium and nickel from an oil fly ash is studied in a two‐step leaching process, carried out under ambient pressure without calcination. In the leaching, nickel is dissolved with NH4Cl in the first step, followed by vanadium leaching with Na2CO3 in the second step. Both leachants depress the dissolution of iron and aluminium from the ash and hence the selective leachings are feasible. Nickel was recovered in 87% yield from the leach liquor by precipitation with Na2S, the purity of NiS being over 99% on the basis of the target metals (V, Ni, Fe, Al and Mg). For the recovery of vanadium, which has a relatively low concentration in the leach liquor, solvent extraction with TOA is preferable to concentration, prior to crystallization with NH4Cl. The experimental data showed that the vanadium concentration of the stripping solution is increased by about 15 times that of the leach liquor, which results in 78% yield as NH4VO3 crystals.
Gas‐Sparged bioreactors for CO2 fixation by Dunaliella tertiolecta
Authors: Suzuki Takahiro , Matsuo Takeshi , Ohtaguchi Kazuhisa , Koide Kozo
Published: May 2005

Two kinds of bioreactors, a bubble‐column and an air‐lift bioreactor, have been designed. The influence of operating conditions such as medium composition, light intensity, carbon dioxide concentration in the flushing gas, culture temperature, and gas flow rate, on photosynthesis of Dunaliella tertiolecta were studied using a chemometrics approach. The bubble‐column bioreactor system was shown to be advantageous over the air‐life because of a weaker intensity of hydrodynamic stress derived from gas bubble dispersion and culture broth mixing. Optimal conditions for carbon dioxide fixation or maximal growth rate were determined. The effect of hydrodynamic shear forces on the algal wall produced by gas bubbling was identified as one of the most significant factors for algal growth.