摘要:

AbstractA method for recovery of glutamic acid from fermentation broth using microfiltration, diafiltration, and reverse osmosis has been proposed. Coupled with the technique of semi‐continuous isoelectric crystallisation, the method gave a product of 3·3% higher purity with 11.1% higher yield compared with the conventional meth

ISSN:0268-2575    

DOI:10.1002/jctb.280640202

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractNineteen samples from the United Nations Special Commission 65 on Iraq (UNSCOM 65) were analyzed for chemical warfare (CW) related compounds using a variety of spectroscopic and chromatographic techniques including multinuclear NMR, GC (phosphorus, sulfur and atomic emission detection), GC/MS (electron impact and chemical ionization), tandem MS, HPLC/ion chromatography, HPLC/thermospray/MS, FTIR, ICP and GFAA. The samples consisted of one piece of cloth, one piece of wood, six waters, six soils, two vegetation samples and two mortar shell crosscut sections. No intact CW agents were detected; however, diethyl phosphoric acid was unambiguously identified in three of the water samples and ethyl phosphoric acid was tentatively identified, at lower levels, in one of the water samples. Diethyl phosphoric acid and ethyl phosphoric acid are degradation products of munitions‐grade Tabun (GA), an organophosphorus nerve agent. However, these compounds are also degradation products of the Chemical Weapons Convention (CWC) scheduled compound Amiton as well as many commercially available pesticide

ISSN:0268-2575    

DOI:10.1002/jctb.280640203

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe physiological state of microorganisms should be considered in biotechnology and biosciences since this influences the rate and efficiency of cellular processes. Physico‐chemical methods, such as biocalorimetry and laser flow cytometry, and other spectroscopic methods for determination of biochemical data, such as concentration of NADH, ATP and cytochrome c, are suitable for describing the physiological stat

ISSN:0268-2575    

DOI:10.1002/jctb.280640204

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe behavior of inducted gas from liquid surface and the; power requirements in an agitated tank using a mechanical agitator are studied in order to increase the amount of gas self‐induction and the gas retention time for gas absorption. A 45° six‐blade downward impeller turbine was utilized in this study. Air and water, air and 40 wt% 60 wt%, and 80 wt% of glycerin water, and air and 106 cP silicon oil were employed as gas and liquid phases. Variables which were studied included geometrical factors (immersed depth of impeller, baffle with and diameter of impeller) and the physical properties of the liquid (viscosity, density, and surface tension). The correlations for the onset speed of impeller and power consumption after gas induction in the agitated tank are established from our experimental results. The amount of gas self‐induction from the liquid surface in the agitated tank increases with increasing impeller diameter and speed and decreases with increasing baffle width, depth of impeller and viscosity of

ISSN:0268-2575    

DOI:10.1002/jctb.280640205

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThermolysin metalloprotein affinity metal chromatography (MAMC) has been shown to be effective for the removal and concentration of lanthanide and actinide ions from aqueous solution. Using solution of trivalent lanthanide ions of appropriate radii and of Th4+and UO 22+ions as models, the calciumbinding sites of immobilized thermolysin have shown appreciable potential for the decontamination of actinide‐bearing waster solutions. The zinc‐binding site of the affixed protein may also be used for the removal and concentration of divalent transition metal

ISSN:0268-2575    

DOI:10.1002/jctb.280640206

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractIn the present paper, we study the adsorption of Cu2+from industrial wastewater and aqueous solution at 293 K, by a by‐product of activated carbon (raw charcoal) obtained from reds. A Method of preparation of raw charcoal was established and the main adsorption characteristics of metal ions were examined, as well as the static and dynamic conditions of the adsorption process. The adsorbent properties of the charcoal used were also studied. The presence of other metal ions in the solution decreases the adsorption capacity for copper, and the chemical nature of the charcoal surface and metal ions have a great significance for the adsorption process. The area of charcoal was about 400 m2g−1at a carbonization temperature of 97

ISSN:0268-2575    

DOI:10.1002/jctb.280640207

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractPapain, a sulfhydryl protease has been immobilized on flat‐sheet modified polysulfone membranes and hydroxyethyl cellulose coated polyethersulfone hollow fibers. Amidase activity of the enzyme in solution on the membranes has been assayed. Immobilized papain on the modified polysulfone membrane and the hollow fibers retains 12% and 25% of its activity (with 1 mmol dm−3substrate) in solution, respectively. Loading experiments revealed decreased activity on the modified polysulfone membrane with increased enzyme loading. Adsorption experiments for the reaction product,p‐nitroaniline, have been performed and an attempt has been made to correct for this in activity calculations. Apparent Michaelis–Menten parameters were determined for the modified polysulfone and hollow fibers with both Kmand Vmaxbeing lower in the immobilized cases. Electron paramagnetic resonance study of the changes in active site conformation of an enzyme on a hollow fiber membrane are reported for the first time. Experiments using the sulfhydryl‐specific (1‐oxyl‐2,2,5,5‐teetrahyl‐Δ3‐pyrroline‐3‐methyl)methanethiolsulfonate spin label depicted the presence of two subpopulations of immobilized papain on the hollow fibers, one of them

ISSN:0268-2575    

DOI:10.1002/jctb.280640208

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractPrevious studies show that axial dispersion in steady laminar flow can be substantially reduced by superimposing fluid oscillation in a baffled tube. In this paper, experimental observations on fluid dispersion for oscillatory flow in a baffled tube are obtained in a series of concentration measurements using high spatial resolution local conductivity probes, and two models—the continuous stirred tank (CST) with feedback and the plug flow with axial dispersion—are used to analyse the concentration curves and determine the fluid dispersion for such a system. The CST with feedback model combines the algorithms from Mecklenburgh and Hartland with the evaluations of unbiased moments from Anderssen and White to determine the dimensionless dispersion coefficient,D/uL, and the backmixing coefficient,F. The plug flow with axial dispersion model, on the other hand, utilises the axial diffusion model by replacing the molecular diffusion coefficient to the axial dispersion coefficient. This model uses an upstream concentration measurement together with an imperfect pulse technique to predict a downstream concentration profile, and thereby determine a best fit value for the dispersion coefficientD/uL. The axial dispersion results show that there is generally more dispersion predicted using the plug flow with axial dispersion model than when using the CST with feedback model for all the oscillatory Reynolds numbers and Strouhal numbers tested. The difference in the calculatedD/uLbetween the two models is discus

ISSN:0268-2575    

DOI:10.1002/jctb.280640209

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe growth and enzymatic production ofPseudomonassp. BA2 a newL‐aminoacylase‐producing microorganism, were studied in a bench‐top fermenter. Multiple fermentations were carried out in order to determine the optical pH and temperature values. The influence of the substrate concentration on both growth andLaminoacylase activity was also investigated. The maximum growth rate and the greatest yield of enzyme were obtained when the fermentation was carried out at pH 7·5, 25°C and DOT ≥ 50%.N‐Acetyl‐DL‐alanine, at a concentration 20 g dm−3, was used as the sole carbon and nitrogen source. The fermentation process provided a maximum biomass concentration of 3·36 g dry weight dm−3. The highestL‐aminoacylase production (11429 U g−1dry weight) was obtained after 39 h of cultivation. The results were a significant improvement over t

ISSN:0268-2575    

DOI:10.1002/jctb.280640210

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe combustion of two agricultural residues, grape and olive bagasses, has been studied. The influence of oxygen partial pressure and gas flow rate have been analysed. The analysis of residual gases, mainly containing CO and CO2, shows that there are two successive stages or effects owing to the combustions of volatile compounds and solid. Oxygen partial pressure has a pronounced influence on the temperatures at which combustion effects are observed. In fact, both temperatures of combustion coincide when oxygen partial pressure is higher than 5 × 104pa. For each run, curves of weight loss and differential weight loss have been followed. From a kinetic model proposed (first and nth reaction order, between 0·87 and 0·84, with respect to the solid and oxygen, respectively), the activation energy of combustion was found to be between 82·6 and 89·3 kJ

ISSN:0268-2575    

DOI:10.1002/jctb.280640211

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY