摘要:

AbstractThe objective of this work was to study the effect of pH and ionic matrix on product release and on the removal of uranyl ion by aCitrobacter. sp phosphatase enzyme‐catalysed reaction. An improvement in the efficiency of uranyl removal was obtained by incorporating ammonium acetate (NH4Ac) into the solution. It was confirmed using X‐ray diffraction (XRD), and other analytical techniques, that the insoluble, cell‐bound product was NH4U

ISSN:0268-2575    

DOI:10.1002/jctb.280630202

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractWater dephenolation was studied using a multistage Rotating Film Pertractor (RFP). This relatively new liquid membrane technique allows the use of almost water‐insoluble liquids as intermediate organic ‘membranes’. The effects of the main processing parameters such as disc rotation velocity, temperature and phase flowrate, on removal efficiency were studied. A mathematical model describing the process of dephenolation in a counter‐current multistage cascade ofn‐RFP contactors was proposed for the prediction of pheno

ISSN:0268-2575    

DOI:10.1002/jctb.280630203

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractA perovskite oxide, YBa2Cu3O7 −x(YBCO), has been prepared by the method of carbonate precipitation from a mixed nitrate solution and oxidised at 950°C in an air atmosphere to obtain a perovskite oxide to be used as a catalyst for H2/CO reactions. The characterisation of the perovskite oxide was performed by using X‐ray diffraction before and after the treatment with different gases, A.C. susceptibility measurements, particle size measurements and temperature programmed reduction (TPR) in which hydrogen was used in order to monitor the changes of the perovskite with temperature in a hydrogen atmosphere. A.C. susceptibility measurements showed that the YBCO perovskite exhibited the typical good superconducting sharp transition temperature at 93 K, indicating that the wet chemical preparation route is suited to the production of this mate

ISSN:0268-2575    

DOI:10.1002/jctb.280630204

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe preparation of 4‐bromophthalic anhydride is described. This compound, useful as raw material for production of dianhydride monomers such as bisphthalic dianhydride, oxy‐bisphthalic dianhydride and several bisphenol dianhydrides for the specialty polyimide sector, was prepared via gas phase oxidation of 4‐bromo‐ortho‐xylene with air over a V–Ti–P catalyst in a yield of 85%. Oxidation of 3‐bromo‐ortho‐xylene gave only a 45% yield of 3‐bromophthalic anhydride. Mixtures of 4‐ and 3‐bromo‐ortho‐xylene gave, as expected, mixtures of 4‐ and 3‐bromophthalic anhydride which were enriched in the 4‐isomer (in comparison with the startin

ISSN:0268-2575    

DOI:10.1002/jctb.280630205

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractCombined bioreaction and separation has been successfully carried out in a Simulated Counter‐Current Chromatographic Reactor–Separator (SCCR–S) system for the saccharification of modified starch to maltose and dextrin. The effects of the operating parameters (switch time, eluent flowrate, feed concentration and enzyme activity) on the performance of the SCCR–S system were investigated. By using an eluent of dilute enzyme solution, starch conversions of up to 60% were achieved using lower amounts of enzyme than the theoretical amount required by a conventional bioreactor to produce the same amount of maltose over the same time period. Comparing the SCCR–S system with a continuous rotating annular chromatograph (CRAC) for the saccharification of modified starch showed that the SCCR–S system required only 34·6–47·3% of the amount of enzyme required by t

ISSN:0268-2575    

DOI:10.1002/jctb.280630206

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe synthesis of severalS‐ andN‐substituted derivatives of 5‐[(5,6‐diphenyl‐1,2,4‐triazin‐3‐yl)oxymethyl]‐s‐triazole‐3‐thiol, 2‐[(5,6‐diphenyl‐1,2,4‐triazin‐3‐yl)‐oxymethyl]‐5,6‐dihydrothiazolo‐[3,2‐b]‐s‐briazole, 2‐[(5,6‐diphenyl‐1, 2,4‐triazin‐3‐yl)oxymethyl]‐5H,6,7‐dihydro‐s‐triazolo‐[3,2‐b]‐1,3‐thiazine, 2‐[(5,6‐diphenyl‐1,2,4‐triazin‐3‐yl)oxymethyl]‐5,6‐dihydrothiazolo‐[3,2‐b]‐s‐triazol‐5‐one and 2‐[(5,6‐diphenyl‐1,2,4‐triazin‐3‐yl)oxymethyl]‐6‐phenylthiazolo‐[3,2‐b]‐s‐triaz

ISSN:0268-2575    

DOI:10.1002/jctb.280630207

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractBased on a mathematical model for ethanol fermentation, the optimal pattern for changing culture temperature to maximize the final ethanol concentration was derived utilizing the maximum principle. The optimal temperature scheme started cultivation at 30°C (upper limit) descending later to 20°C (lower limit). The effects of culture temperature and ethanol concentration on growth and ethanol formation were studied by controlling the ethanol concentration at a specified level using recycle with a hollow fiber module. A novel method of operation was also investigated where temperature was initially kept at 30°C and ethanol concentration was controlled low simultaneously by the recycle system. The culture temperature was eventually lowered and the draw‐off rate through the hollow fiber stopped. This operation was shown to yield significant improvement for efficient ethanol produc

ISSN:0268-2575    

DOI:10.1002/jctb.280630208

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractFormal kinetic studies of the epoxidation and hydroxylation of maleic acid by hydrogen peroxide (H2O2) have been carried out in the presence of a molybdenum salt, as catalyst, immobilized on Amberlite IRA‐400 polymer resin in the chloride form. Immobilization of the catalyst on the resin was by a sorption process. Hydroxylation by immobilized catalysis afforded higher H2O2selectivity and increased product yield in excess of 85%. Analysis of kinetic results shows that the reaction in the pseudo‐homogeneous system follows the typical pseudo‐zero order dependence on H2O2concentration and is first order with respect to maleic acid concentration. However, the rate model developed for the immobilized catalyst fits the experimental data smoothly and parameter estimation using the Lineweaver–Burk plot fulfils the kinetic consistency tests without additional mathematical manipulation. The problem of activity and stability of the present catalyst was also inves

ISSN:0268-2575    

DOI:10.1002/jctb.280630209

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractA major difficulty in the monitoring and control of bioprocesses is the lack of reliable and simple sensors for following the evolution of the main state variables and parameters such as biomass, substrate, product and growth rate. An adaptive estimation algorithm is proposed to recover the state and parameters in bioprocesses. This estimator utilises the physical process model and the reference model approach. Experiments concerning estimation of biomass and product concentrations and specific growth rate, during batch, fed‐batch and continuous fermentation processes are presented. The results show the performance of this adaptive estimation approac

ISSN:0268-2575    

DOI:10.1002/jctb.280630210

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

Abstractn‐Fatty alcohols (average molecular weight 187), prepared fromn‐paraffins, were treated with a series of dibasic acids such as malonic, succinic, glutaric, adipic and phthalic anhydride to give the corresponding fatty esters. The prepared fatty esters were formulated with poly(vinyl acetate) emulsion and used as films or textile coatings. Tests such as rate of drying, mechanical properties and resistance to micro‐organisms were carried out. Samples of poly(vinyl acetate) plasticized with dibutyl phthalate were also prepared and evaluated for the purpose of comparison. The antifungal activity of these compounds was studied. The results obtained indicate that the prepared fatty esters can be used not only as plasticizers but also as fungicides and in some respects they are better than the conventional dibutyl phthalate plasti

ISSN:0268-2575    

DOI:10.1002/jctb.280630211

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY