bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mathematical modelling of industrial pilot‐plant penicillin‐G fed‐batch fermentations
Authors: Menezes José C. , Alves Sebastião S. , Lemos João M. , de Azevedo Sebastião Feyo 
Published: May 2005

AbstractPenicillin‐G fermentation with industrial media in 1 m3 stirred tank bioreactors was studied. A model based on the Bajpai–Reuss model structure was developed. Under typical production conditions catabolite repression is nonidentifiable and extensive mycelium differentiation occurs. Thus, the original model was reformulated, neglecting glucose repression of penicillin production and including biomass autolysis. The multi‐substrate nature of industrial media was critically analysed. By combining the two most important carbon substrates present, a simple and applicable model was obtained. Model predictions agreed well with experimental data and reproduced the general characteristics observed in the fermentations. The predictive power of the model was tested for fermentations with different sugar feed rate profiles and raw materials (corn‐steep liquor and sugar syrup). Several aspects of parameter estimation and model development are discussed on the basis of direct experimental data inspection and a sensitivity analysis of model parameters.
Synthesis and antibacterial activity of thioglycolic amino acid derivatives and dipeptides containing the 2‐methyl‐3,4‐dihydroquinazolin‐4‐one moiety
Authors: Atta Ferial M. 
Published: May 2005

Abstract3‐(2′‐Chloroethyl)‐2‐methyl‐3,4‐dihydroquinazolin‐4‐one (I) was reacted with sodio (sodium thioglycolate) in dry dioxane and yielded compound II. By using thionyl chloride, this compound was converted to the corresponding acid chloride (III). The prepared acyl chloride (III) was allowed to interact with different α‐amino acids such as Gly, L‐Ala, L‐B‐Phe, DL‐Asp, L‐Glu, L‐Thr and L‐Val to give new amino acid derivatives (IVa–g). A selected C‐terminal derivative of glycine (IVa) was converted into acid chloride (V). The acid chloride formed was reacted with L‐Ala, L‐B‐Phe, DL‐Asp, L‐Glu, L‐Thr and L‐Val and yielded the new dipeptides VIa–f. The structures of the synthesized compounds were elucidated by elemental analysis and IR spectra. The prepared peptides were tested for their antimicrobial activities by comparison with tetra‐cycline as a reference compound.
Heavy metals in the environment. Part V: The use of high‐copper zinc residues in the zinc chloride process and the recovery of copper as anhydrous copper(II) chloride
Authors: Chaudhary Abdul J. , Donaldson John D. , Grimes Susan M. , Boddington Stephen C. 
Published: May 2005

AbstractAn investigation into the use of high‐copper zinc residues in the production of zinc chloride solution and the recovery of copper, as anhydrous copper(II) chloride, is reported. The process developed involves leaching of the high‐copper zinc residues with concentrated hydrochloric acid to dissolve the zinc content leaving a residue which has a high copper content. Any copper dissolved in the primary leach is removed by electrodeposition to give a zinc chloride solution suitable for industrial use. The solid residue from the initial leach is trated with chlorine gas to solubilise the copper present, giving a solution of copper(II) chloride. This solution is purified to remove Zn2+ and Pb2+ by anion‐exchange and Fe3+ and Al3+ by hydrolysis. The purified solution can then be converted to anhydrous copper(II) chloride with a purity of 99·6%.
Microbial interactions with caesium—implications for biotechnology
Authors: Avery Simon V. 
Published: May 2005

AbstractThe continuing release of caesium isotopes into the environment has highlighted the necessity for efficient removal of Cs from industrial waste effluents prior to discharge. Existing technologies, e.g. zeolite ion‐exchange for Cs removal, can be expensive and microbial metal adsorption/accumulation may represent a cheap alternative. The distinct chemical properties of Cs+, which dictate a high degree of metabolism‐dependent uptake via monovalent cation transport systems, indicate that different approaches are required for biological Cs removal to those which are generally adopted for other metals/radionuclides. The low toxicity of Cs+eliminates one potential problem in the use of live cells for Cs removal. High levels of Cs+accumulation have been reported in a number of microorganisms, but uptake levels vary markedly in different organisms and are strongly influenced by a number of physico‐chemical and mechanical parameters, e.g. the use of batch or continuous‐flow systems, biomass immobilization (which tends to increase Cs+adsorption at the expense of metabolism‐dependent accumulation), pH and particularly the prevalence of other monovalent cations such as K+and Na+. Inherent differences in Cs+uptake capacities of different microorganisms appear to be largely attributable to differences in the affinity of monovalent cation transport systems for Cs+. The application of rigorous screening procedures involving the use of autoradiography has great potential for isolation of microorganisms with particularly high affinities for Cs+. Alternatively, manipulation of the physiological status of microorganisms can dramatically alter the transport of Cs+and other monovalent cations. Hyper‐ and hypo‐osmotic shock, respectively, have so far proved to be the most successful treatments for stimulating Cs removal and recovery. Other manipulations, at both the cellular and molecular level, which are known to influence K+fluxes but have yet to be characterized for Cs+, are outlined here.
Enzymatic synthesis of (R)‐ and (S)‐2‐cyclohepten‐1‐ol
Authors: Izumi Taeko , Eda Yuji 
Published: May 2005

AbstractThe synthetically useful chiral synthons, (R)‐ and (S)‐2‐cyclohepten‐1‐ol, can be prepared by an enantioselective transesterification of racemic trans‐2‐(phenylseleno) cycloheptanol using lipases, followed by selenoxide elimination and hydrolysis.
Adsorption of trivalent chromium from aqueous solutions onto activated carbon
Authors: Leyva‐Ramos Roberto , Fuentes‐Rubio Laura , Guerrero‐Coronado Rosa Maria , Mendoza‐Barron Jovita 
Published: May 2005

AbstractThe adsorption of chromium (III) onto activated carbon was investigated as a possible alternative method for its removal from aqueous solutions. The adsorption data were obtained in a batch adsorber and fitted the Langmuir adsorption isotherm well. The effect of pH on the adsorption isotherm was investigated at pH values of 2, 4, 5 and 6. It was found that at pH values below 2 the Cr(III) was not adsorbed and at pH values above 6.4 the Cr(III) was precipitated as Cr(OH)3. Maximum adsorption occurred at pH 5. The pH plays a very important role in the adsorption of Cr(III) since Cr(III) can form different complexes in aqueous solutions. The adsorption capacity was increased by about 20% as the temperature was raised from 25 to 40°C. It was concluded that Cr(III) is adsorbed to an appreciable extent on activated carbon and that the adsorption is highly dependent upon pH.
Improvement of substrate‐selectivity in enzyme‐linked FIA‐systems by differential measurement and ‘enzyme‐array’
Authors: Englbrecht Ursula , Schmidt Hanns‐Ludwig 
Published: May 2005

AbstractFlow injection systems with immobilized enzymes for the parallel determination of chemically similar substances such as xylose/glucose and L‐leucine/L‐isoleucine/L‐valine are described. The determination of xylose and glucose was performed either by differential measurement or by an ‘enzyme‐array’. Because of the different linear ranges of the calibration curves for xylose and glucose quantification was only possible when there was an excess of xylose (xylose 0·1–2·5 mmol dm−3, glucose 0·001–0·1 mmol dm−3). The parallel quantification of the branched‐chain amino acids could be realized by an array arrangement using an FIA‐system with several immobilized enzymes of slightly different selectivity. The total amount of branched‐chain amino acids can be up to about 1·1 mmol dm−3.
Combined biological–chemical (Ozone) treatment of wastewaters containing chloroguaiacols
Authors: Heinzle Elmar , Stockinger Hermann , Stern Marco , Fahmy Mona , Kut Oemer M. 
Published: May 2005

AbstractBiological degradation of chloroguaiacols contained in sulphite pulp chlorine bleaching wastewater was studied in four parallel biological fluidised bed reactor systems—one single aerobic, one single anaerobic and two combined anaerobic–aerobic reactors. At low loading rates, trichloroguaiacols were removed nearly quantitatively. 4,5‐Dichloroguaiacol was only partly removed. At high loading rates the anaerobic–aerobic recycle reactor removed individual guaiacols more than the other reactors. Only 4,5,6‐trichloroguaiacol was removed best by the anaerobic–aerobic reactors in series. Even mixed culture biofilms adapted during several years of continuous operation did not satisfactorily remove these compounds. Synthetic wastewater, containing chlorinated guaiacols, treated with ozone produced formate and oxalate and quantitatively inorganic chloride. Combined ozonation–biotreatment in two reactors in series as well as in a recycle system allowed complete removal of all individual chlorinated guaiacols (< 1 μmol m−3 remained). The efficiency of non‐purgable organic carbon removal could be increased from ≤0.55 to about 4 mol carbon mol−1 ozone by combination of ozonation with biotreatment. Simultaneously, the efficiency of removal of chlorinated guaiacols was increased by a factor of 10, which is essential for industrial application.
Effects of ionic strength and pH on the adsorption equilibria of lysozyme on ion exchangers
Authors: Hashim Mohd. A. , Chu Khim‐Hoong , Tsan Pek‐Sim 
Published: May 2005

AbstractThe effects of ionic strength and pH on adsorption of lysozyme to three strong cation exchangers have been studied. Adsorption equilibrium data obtained using the batch techniques corresponded well to the Langmuir isotherm. Ionic strength had a considerable influence on the isotherms. In all cases, the maximum binding capacity of the three exchangers decreased while the apparent dissociation constant increased with increasing ionic strength. The maximum binding capacity also decreased while the apparent dissociation constant was not significantly affected by an increase in pH. It was found that the three exchangers exhibited different levels of binding capacity under identical solution conditions. This was shown to be caused by variation in the arrangement and distribution of charged groups. However, the ion‐exchange matrix had little effect on the apparent dissociation constant.
Physicochemical characteristics of acrylic‐acid polymer‐impregnated cement pastes
Authors: Gad E. A. M. , El‐Sukkary M. M. A. , Sayed W. M. , Abo‐El‐Enein S. A. 
Published: May 2005

AbstractVarious Portland cement pastes were made using water cement ratios of 0·20, 0·25, 0·35 or 0·40 and then cured for 1, 3, 7, 28, 90 or 180 days. These pastes were impregnated with acrylic acid monomer under vacuum and the monomer‐impregnated samples were then treated at two different temperatures, 40 or 60°C, for the polymerization process, using benzoyl peroxide as initiator. Several physicochemical studies were carried out on each cement paste; these studies include compressive strength tests, bulk density, compressive strength versus gel/space ratio relationships, polymer load, X‐ray diffraction analysis and differential thermal analysis. Results have indicated that compressive strength improvement in acrylic acid‐polymer impregnated cement pastes is mainly dependent on initial water/cement ratio, curing time and gel/space ratio. The results of X‐ray diffraction analysis and differential thermal analysis indicated that the intrusion of polymer into the cement paste matrix does not affect the phase composition of the Portland cement hydration products.
Synthesis of some new spiroheterocyclic pyrylium salts related to 1‐oxa‐4‐thiaspiro[4.4] nonan‐2‐one and/or [4.5]decan‐2‐one as antimicrobial agents
Authors: Al‐Ahmadi Abdullah A. , El‐Zohry Maher F. 
Published: May 2005

Abstract1‐Oxa‐4‐thiaspiro[4.4]nonan‐2‐one (1a) and/or 1‐oxa‐4‐thiaspiro[4.5] decan‐2‐one (1b) were reacted with aniline and/or p‐chloroaniline to afford the corresponding spirothiazolidinones (2a–d). Reaction of 2a–d with chalcones gave 2‐(α – paracylbenzyl)‐4‐aryl‐1‐thia‐4‐azaspiro[4.4]nonan‐3‐one and 2‐(α‐aracylbenzyl)‐4‐aryl‐1‐thia‐4‐azaspiro[4.5]decan‐3‐one (3a–p) respectively. Compounds 3a–p were reacted with acetic anhydride and perchloric acid to yield the spiropyrano[2,3‐d]thiazol[4]ium perchlorate derivatives 4a–p. The structures of the synthesized compounds were elucidated by elemental and spectroscopic (IR and 1H‐NMR) analysis. All the prepared compounds were tested for their antimicrobial activities in comparison with tetracyclic as a reference compound.
Heterocyclic alternatives for benzidine‐based mono‐ and disarylazo pigments: Synthesis and characterization of a novel class of pyrazolo (1,5‐a)pyrimidine azo pigments
Authors: Hanna Mokhtar A. , Girges Margret M. 
Published: May 2005

AbstractIn a sequence of reactions, three different series of novel mono‐ and disarylazo pyrazolo(1,5‐a)pyrimidine pigments were prepared to determine whether these products might successfully act as possible alternatives for benzidine‐based dyestuffs, which are known to be associated with toxicological hazard and carcinogenic effects. The structure of the named compounds was inferred from elemental and spectral analysis and, in some cases, by alternative synthetic routes.
Hydrogenolysis of organochlorinated pollutants: Parallel hydrodesulfurization of methylthiophene and hydrodechlorination of dichlorobenzene over carbon‐supported nickel, molybdenum and nickel–molybdenum sulfide catalysts
Authors: Frimmel Jiří , Zdražil Miroslav 
Published: May 2005

AbstractThe sulfide catalysts Ni/C, Mo/C, Ni–Mo/C and Ni–Mo/alumina were compared in parallel hydrodesulfurization (HDS) of 3‐methylthiophene and hydrodechlorination (HDC) of o‐dichlorobenzene in a flow reactor at 1 MPa and 300°C. The work was related to the disposal of chlorinated organic wastes contaminated by sulfur. The magnitude of the synergism in activity between Ni and Mo in the composite Ni–Mo catalyst observed both for HDS and HDC was significantly smaller for HDC than HDS. HDC was faster than HDS over all catalysts studied. The Ni/C sample exhibited the highest selectivity to HDC versus HDS and also surprisingly high HDC activity, which was higher than that of the commercial Ni–Mo/alumina catalyst. It was concluded that HDC and HDS can be uncoupled by changing the active sulfide phase and that significant room exists to develop sulfide HDC catalysts with better activity than the conventional Co–Mo or Ni–Mo/alumina catalysts.
Kinetics and mechanism of maleic acid hydroxylation by hydrogen peroxide. Part I: Formal kinetic studies by immobilized catalysis in a pseudo‐homogeneous system
Authors: Oludipe John O. , Iyuke Sunny E. , Aderemi Benjamin O. 
Published: May 2005

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 H2O2 selectivity 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 H2O2 concentration 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 investigated.
The kinetics of cellulase‐free xylanase excretion by Thermomyces lanuginosus RT9
Authors: Hoq M. Mozammel , Solomon Bamidele O. , Hempel Carsten , Rinas Ursula , Deckwer Wolf‐Dieter 
Published: May 2005

AbstractThermomyces lanuginosus RT9 was grown in a stirred and aerated reactor for the production of xylan‐degrading enzymes and the kinetics of xylanase and β‐xylosidase secretion investigated. During each fermentation, kLa decreased with increasing mycelia concentration to the point of cellular disintegration. Although both agitation and aeration rates had significant influences on the growth rate as well as on the yields and rates of enzymes (xylanase and β‐xylosidase) release, the enzyme secretion kinetics showed a comparable pattern independent of the operating conditions. Enzyme secretion could be separated into a growth phase, during which extracellular xylanase was at low level, and an enzyme release phase, when there was a notable increase in the xylanase production rate accompanying cellular disintegration.
Interaction of triton X‐100 on silica: A relationship between surface characteristics and adsorption isotherms
Authors: Nevskaia Daniela M. , Cervantes Maria Luisa Rojas , Ruíz Antonio Guerrero , de Dios López González Juan 
Published: May 2005

AbstractAdsorption of Triton X‐100 on various silica substrates has been investigated. A number of solids, including a natural quartz, this quartz washed with HCl acid and subsequently heated at 1273 K; two aerosils and one Kieselgel silicas were studied. These solids exhibit surface areas in the range of 5 to 430 m2 g−1. All the Triton adsorption isotherms display an S‐shape at the adsorption temperatures studied (298 and 308 K). It has been found that the pretreatments of natural quartz (by water washing, impurities removed by acid and/or high temperature calcination) affect considerably the amounts of TX‐100 adsorbed. Measurements of surface composition have been made by X‐ray photoelectron spectroscopy (XPS) with particular emphasis on the presence of impurities and on the number of OH groups at the surface of the samples. The nature of the surface hydroxyl has also been studied by infrared spectroscopy. Furthermore, the specific number of hydroxyl groups on the surface of the silica samples has been determined by thermogravimetric analysis. Finally an attempt to correlate solid surface characteristics with adsorption isotherms has been developed.
Kinetics of addition of acetic acid to epichlorohydrin in the presence of DMF or DMSO
Authors: Bukowska Agnieszka , Guskov Andrei K. , Makarov Mikhail G. , Rokaszewski Edward , Svets Valery F. 
Published: May 2005

AbstractThe kinetics of reaction between acetic acid and epichlorohydrin carried out in the presence of DMF or DMSO was studied. In addition, the conductivity of the reaction mixture was measured. The conductivity was found to increase considerably as the reaction proceeded. This was explained in terms of the formation of new effective forms of catalysts: the ammonium salt (in case of DMF) or sulphonium salt (for DMSO). A reaction scheme has been proposed, taking into account the active catalyst forms. The set of kinetic equations describing the reaction has been developed and the appropriate rate constants evaluated.
Oxidation of ethanol vapors in a spiral bioreactor
Authors: Shim Jeong Seop , Jung Jont Tai , Sofer Sam , Lakhwala Fayaz 
Published: May 2005

AbstractA fixed film spiral bioreactor containing immobilized activated sludge microorganisms has been used to degrade ethanol vapors. The effect of air flow rate, and ethanol feed concentration on elimination capacity has been investigated. Air flow rate is varied in the range from 2ṁ34 to 40ṁ0 dm3 min−1. Ethanol feed concentration is varied in the range from 600 to 7000 ppmv. In the concentration range studied, the elimination capacity increased proportionately with an increase in feed concentration. However, the elimination capacity decreased significantly at flow rates greater than 20 dm3 min−1 owing to insulfficient residence time. The maximum elimination capacity observed was 185 g ethanol h−1 m−3 of reactor volume. Critical ethanol loading, defined as the maximum loading to achieve greater than 99% elimination at various residence times have been determined. These data are extremely useful in designing bioreactor for large scale applications.
Chemical analysis of environmental samples collected in Iraq: Analysis for the presence of chemical warfare agents
Authors: Weimaster John F. , Beaudry William T. , Bossle Paul C. , Ellzy Michael W. , Janes L. Gail , Johnson Dennis W. , Lochner J. Michael , Pleva Stephen G. , Reeder Janet H. , Rohrbaugh Dennis K. , Rosso Thomas E. , Szafraniec Leonard J. , Szafraniec Linda L. , Albro Thomas G. , Creasy William R. , Stuff John R. , Smith Philip B. , Stewart Ian R. 
Published: May 2005

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 pesticides.
Use of thermolysin metalloprotein affinity metal chromatography in the decontamination of actinide‐bearing solutions
Authors: Meier Laurel , Terrell Katisha , Vincent John B. 
Published: May 2005

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 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 ions.
Gas hold‐up and volumetric mass transfer coefficient in bubble columns under foam control
Authors: Takesono Satoshi , Onodera Masayuki , Yamagiwa Kazuaki , Ohkawa Akira 
Published: May 2005

AbstractExperimental measurements of the gas hold‐up and volumetric mass transfer coefficient have been made for baffle columns (BCs) reacting various foaming liquids under mechanical and chemical foam control. The gas hold‐up and the volumetric mass transfer coefficient in a mechanical foam‐control system (BCs with rating‐disk mechanical foam‐breakers) were larger than those in a chemical foam‐control system (BCs with an antifoam agent added). Correlations for the gas hold‐up and the volumetric mass transfer coefficient in BCs under foam control are presented. Comparison of the volumetric mass transfer coefficient between the mechanical foam‐control system and the chemical foam‐control system in terms of the specific power input also demonstrated higher mass transfer performance and saving power requirements for the mechanical foam‐control system.