bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of cell cycle on the regulation of the cell surface and secreted forms of type I and type II human tumor necrosis factor receptors
Authors: Pocsik Eva , Mihalik Rudolf , Penzes Maria , Loetscher Hansruedi , Gallati Harald , Aggarwal Bharat B.
Published: May 2005

The cell cycle has been shown to regulate the biological effects of human tumor necrosis factor (TNF), but to what extent that regulation is due to the modulation of TNF receptors is not clear. In the present report we investigated the effect of the cell cycle on the expression of surface and soluble TNF receptors in human histiocytic lymphoma U‐937. Exposure to hydroxyurea, thymidine, etoposide, bisbensimide, and democolcine lead to accumulation of cells primarily in G1/S, S, S/G2/M, G2/M, and M stages of the cell cycle, respectively. Whilie no significant change in TNF receptors occurred in cells arrested in G1/S or S/G2 stages, about a 50% decrease was observed in cells at M phase of the cycle. Scatchard analysis showed a reduction in receptor number rather than affinity. In contrast, cells arrested at S phase (thymidine) showed an 80% increase in receptor number.

The decrease in the TNF receptors was not due to changes in cell size or protein synthesis. The increase in receptors, however, correlated with an increase in total protein synthesis (to 3.8‐fold of the control levels). A proportional change was observed in the p60 and p80 forms of the TNF receptors. A decrease in the surface receptors in cells arrested in M phase correlated with an increase in the amount of soluble receptors. The cellular response to TNF increased to 8‐ and 2‐fold in cells arrested in G1 and S phase, respectively; but cells at G2/M phase showed about 6‐fold decrease in response. In conclusion, our results demonstrate that the cell cycle plays an important role in regulation of cell‐surface and soluble TNF receptors and also in the modulation of cellular response. © 1995 Wiley‐Liss, Inc.
Conditional gene expression in secretory tissues and skin of transgenic mice using the MMTV‐LTR and the tetracycline responsive system
Authors: Hennighausen Lothar , Wall Robert J. , Tillmann Urich , Li Minglin , Furth Priscilla A.
Published: May 2005

Molecular mechanisms of development and disease can be studied in transgenic animals. Controlling the spatial and temporal expression patterns of transgenes, however, is a prerequisite for the elucidation of gene function in the whole organism. Previously we reportted that mice carrying a tetR/VP16 hybrid gene (tTA), under the control of the hunman cytomegalovirus immediate early 1 (HCMV‐IE1) gene promoter, can be used to temporally activate the expression of transgenes under the control of a promoter containing tetop sequences. We now show that the MMTV‐LTR can be used to target expression of tTA to the epthelial cells of secretory organs and skin in transgenic mice. Notably, nearly uniform expression of a tetop‐lacZ transgene was found in seminal vesicle, salivary gland, and Leydig cells of mice carrying also the MMTV‐tTA transgene. More heterogeneous patterns of gene expression were observed in mammary epithelial cells and nasal cells of the epidermis. Different MMTV‐tTA lines had conparable tissue expression patterns. Transcriptional activation mediated by tTA was up to several hundred fold and it was abrogated after the administration of tetracycline. The MMTV‐tTA mice established in this work will be useful for experiments examining the roles of biological factors at defined developmental stages in the epithelial cells of salivary gland, seminal vesicle, mammary gland, and skin and the Leydig cells of testes in addition, in combination with the CRE/lox recombnation system, these mice will be useful to achieve gene deletions at defined time points in these organs. © 1995 Wiley‐Liss, Inc.
Enhanced removal of selected hydrocarbons from soil by Pseudomonas aeruginosa UG2 biosurfactants and some chemical surfactants
Authors: Scheibenbogen Karl , Zytner Richard G. , Lee Hung , Trevors Jack T.
Published: May 2005

The ability of rhamnolipid biosurfactants produced by Pseudomonas aeruginosa UG2 to wash a model hydrocarbon mixture from unsaturated soil columns was studied. Both aliphatic and aromatic hydrocarbons were effectively removed without soil clogging with non‐recirculating biosurfactant solutions. Recirculation of wash solutions did not substantially affect washing efficiency. Of the several chemical surfactants tested, only Triton X‐100 provided comparable hydrocarbon washing efficiency without soil clogging. The results suggest that UG2 biosurfactants have the potential for remediation of hydrophobic pollutants in unsaturated soil.
Natural zeolite utilisation in pollution control: A review of applications to metals' effluents
Authors: Kesraoui‐Ouki Sabéha , Cheeseman Christopher R. , Perry Roger
Published: May 2005

This paper assesses the potential of natural zeolite utilization as a low‐cost ion‐exchange and sorbent material in pollution control and recovery of metals. The improvement of the purity of natural zeolites coupled with their chemical modification capabilities in order to provide specific properties may provide a cost‐effective alternative for the treatment of heavy metal contaminated soil and water. The application of natural zeolites in industrial pollution control is becoming important and the level of technical effort is increasingly expanding. The extent of application is unlikely to be related solely to their low cost, but also to improved properties and performance characteristics, which will advance the practical implementation of natural zeolites' technology.
Convenience of immobilized Bacillus licheniformis α‐amylase as time—temperature‐integrator (TTI)
Authors: De Cordt Susanna F. , Hendrickx Marc E. , Maesmans Geert J. , Tobback Paul P.
Published: May 2005

For the immobilization of Bacillus licheniformis α‐amylase to porous glass beads, the performances of three possible linking agents, glutaric dialdehyde, benzoquinone and S‐trichlorotriazine were assessed in respect of the protein yield, the enzymic activity and the thermostability of the immobilized enzyme. These three properties are to be evaluated in view of the possible use of the enzyme preparations as time–temperature‐integrators (TTIs) for assessing the severity of heat pasteurization or sterilization processes of food or pharmaceuticals. All three linkers improved the enzymes's resistance to irreversible heat inactivation to a similar extent and in each case biphasic inactivation kinetics were observed, whereas the dissolved B. licheniformis α‐amylase showed a simple first order decay. The immobilization yield, measured as protein per carrier weight, did not differ markedly for the three linkers, although the enzymic activity of the glutaric dialdehyde‐linked enzyme was lower than that of the benzoquinone‐ and S‐trichlorotriazine‐linked preparations.
Electrolytic flotation of pyrite
Authors: Kydros Konstantine A. , Gallios George P. , Matis Konstantine A.
Published: May 2005

Electrolytic flotation, a rather unconventional flotation technique used in effluent treatment, was investigated on pyrite; the process was enhanced by xanthate and also a cationic collector. This was then compared with classical floatability experiments. Zeta‐potential measurements, under similar pulp conditions, were carried out to explain the process mechanism. The mineral flotation behavior in the presence of common modifiers was also examined during electrolytic flotation. The latter produces fine gas bubbles, has favorable hydrodynamic conditions and assists in flocculation of particles prior to flotation, as shown.
A continuous reactor system for production of lactulose
Authors: Kozempel Michael , Kurantz Michael
Published: May 2005

A continuous reactor process was developed to produce lactulose from lactose. A system of two CSTRs in series with a tubular finishing reactor gave conversion to lactulose of about 76%. The reactors ran at 71–75°C with a volumetric hold‐up in the CSTRs of 22·7 dm3 and in the tubular reactor of 2·6 dm3. Each CSTR had a nominal residence time of 44 min. The flow rate was 0·53 dm3 min−1.
The tularaemia vaccine
Authors: Sandström Gunnar
Published: May 2005

Tularaemia is a disease caused by the facultative intracellular bacterium Francisella tularensis. Vaccination resulting in protective immunity is induced by live vaccine only. Such vaccination can be performed by scarification utilizing the live vaccine strain of F. tularensis (F. tularensis LVS), which results in good but not complete protection. Humoral as well as cell‐mediated immunity are induced by vaccination and it has been shown that cell‐mediated immunity is a prerequisite for protection. Since the live vaccine strain is attenuated and the genetic background of attenuation is unknown it is important to consider process parameters so that the immunogenicity of the vaccine is preserved.
Performance of a high‐solids anaerobic digestion process under various ammonia concentrations
Authors: Kayhanian Masoud
Published: May 2005

Ammonia is produced during anaerobic digestion of protein‐containing materials. While ammonia can be utilized by some members of the anaerobic population, excess ammonia can inhibit methanogenesis. High‐solids anaerobic digestion may be especially sensitive to the effects of ammonia overproduction. This study explored the performance of a pilot scale high‐solids anaerobic digestion process under various total ammonia nitrogen (TAN) concentrations. In general the high‐solids digester could operate up to 1000 mg dm−3 without any inhibitory effect. The digester performed best when it was operated at TAN concentrations in the narrow range of 600 to 800 mg dm−3.
Catalytic activity and kinetic study of cerium‐catalyzed syntheses of hydroxybenzaldehydes by oxygen oxidation. II
Authors: Yoshikuni Tadatsugu
Published: May 2005

The cerium‐catalyzed syntheses of hydroxybenzaldehydes from cresols by oxygen oxidation have been developed. When cerium catalysts four‐coordinated by hydroxo ligand was employed, the oxidation process required much less catalyst (0·5%), a shorter reaction time (5→2 h) and a lower temperature (120→40°C). The rate of two first‐order reactions increased by a factor of c. 106.
Continuous ethanol production from carob pod extract by immobilized Saccharomyces cerevisiae in a packed‐bed reactor
Authors: Roukas Triantafyllos
Published: May 2005

The continuous production of ethanol from carob pod extract by immobilized Saccharomyces cerevisiae in a packed‐bed reactor has been investigated. At a substrate concentration of 150 g dm−3, maximum ethanol productivity of 16 g dm−3 h−1 was obtained at D = 0·4 h−1 with 62·3% of theoretical yield and 83·6% sugars′ utilization. At a dilution rate of 0·1 h−1, optimal ethanol productivity was achieved in the pH range 3·5–5·5, temperature range 30–35·C and initial sugar concentration of 200 g dm−3. Maximum ethanol productivity of 24·5 g dm−3 h−1 was obtained at D = 0·5 h−1 with 58·8% of theoretical yield and 85% sugars′ utilization when non‐sterilized carob pod extract containing 200 g dm−3 total sugars was used as feed material. The bioreactor system was operated at a constant dilution rate of 0·5 h−1 for 30 days without loss of the original immobilized yeast activity. In this case, the average ethanol productivity, ethanol yield (% of theoretical) and sugars′ utilization were 25 g dm−3 h−1, 58·8% and 85·5%, respectively.
Extractive membrane bioreactors: A new process technology for detoxifying chemical industry wastewaters
Authors: Livingston Andrew G.
Published: May 2005

This paper describes an extractive membrane bioreactor developed to extract and biodegrade toxic organic pollutants present in chemical industry wastewaters. The technology is applicable to wastewaters emanating in organic synthesis operations which are not treatable by conventional ‘direct’ biological treatment due to extremes of pH, high salt contents, or otherwise hostile organic compositions, and also to wastewaters that contain volatile organic compounds. A laboratory scale prototype demonstrating the technology has been operated continuously over periods of several months, using industrially produced wastewaters. No pre‐conditioning or dilution of the wastewaters is necessary prior to treatment, which removes and destroys over 99% of the toxic organics present.
Isotherms of chemical adsorption of bases on solid catalysts for acidity measurement
Authors: Aguayo Andrés T. , Gayubo Ana G. , Ereña Javier , Olazar Martín , Arandes José M. , Bilbao Javier
Published: May 2005

The measurement of the adsorption equilibrium constants of the bases and the total mass of base adsorbed at 200°C are proposed as reproducible indices of average acidity strength and of total acidity of the solid, respectively. The adsorption of different bases (ammonia, n‐butylamine, tert‐butylamine, pyridine) in gas phase on solid acidic catalysts (silica–alumina and zeolite catalysts and a silica gel) has been studied, by applying the calorimetric method in flow regime through an isothermal bed of solid. Both the conditions under which the adsorption is exclusively chemical as well as those under which the adsorption is not limited by the internal diffusion of the base have been determined. For these acidity measurements tert‐butylamine behaves well and is an alternative base to ammonia.
Mathematical model for lactic acid production from lactose in batch culture: Model development and simulation
Authors: Amrane Abdeltif , Prigent Yves
Published: May 2005

The models available to describe lactic acid production do not seem to fit the experimental data very well, especially at the end of batch cultures. From a careful analysis of batch data, an unstructured model of the process has been derived, in which the specific growth rate variations and lactic acid concentration with time have been described by complemented logistic functions. Also, an additional term has been introduced into the Luedeking–Piret expression, taking into account the reduction in rate of lactic acid production observed at very low growth rate.
Saccharification of microcrystalline cellulose by cellulase of Morchella conica mushroom mycelium in comparison with a commercial cellulase
Authors: Manzoni Matilde , Cavazzoni Valeria
Published: May 2005

A comparison was made of the hydrolysis of microcrystalline cellulose Avicel using the cellulolytic complex of the ascomycete Morchella conica and a commercial cellulase. An enzyme concentration of 1 U AVase mg−1 substrate gave the best results during the hydrolytic processes. At 24 h, the M. conica enzyme complex achieved 35.5% and the commercial cellulase 31·2% saccharification, with glucose 84·2% and 52% of the total reducing sugars liberated, respectively. The specific rates of hydrolyses were 0·77 and 0·14 h−1 for reducing sugars and 0·54 and 0·12 h−1 for glucose formation with M. conica and the commercial cellulase, respectively. At 96 h, the degree of saccharification reached 46% for M. conica and 49% for the commercial cellulase, with glucose 76·5% and 65·9% of the total reducing sugars liberated, respectively. Both the complexes were quite stable with a residual activity of 62% CMCase and 47% AVase for M. conica, and 74% CMCase and 57% AVase for the commercial cellulase at 96 h of hydrolysis. The qualitative analysis of the hydrolysis products by TLC indicated, for M. conica, an earlier appearance of cellobiose, which was quickly hydrolyzed to glucose.
Treatment of palm oil mill effluent by upflow anaerobic filtration
Authors: Borja Rafael , Banks Charles J.
Published: May 2005

An upflow anaerobic filter (23 dm3 working volume) was used for the treatment of palm oil mill effluent. The filter was continuously operated for 215 days with organic loads ranging from 1·2 to 11·4 kg of chemical oxygen demand per cubic metre per day and hydraulic retention times from 15 to 6 days. The overall substrate removal efficiency was very high, up to 90% and the filter effluent contained almost no suspended solids. For all runs, the operation of the filter exhibited good stability for acidity and alkalinity, indicating that the use of buffer solutions would not be required. The methane concentration in the biogas, whose production varied from 20 to 165 dm3 per day, was about 60%. Daily gas production varied in the range 0·69–0·79 dm3 per gram of chemical oxygen demand removed.
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

Penicillin‐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

3‐(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

An 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

The 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

The 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

The 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

Flow 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

Biological 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

The 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

Various 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

1‐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

In 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

The 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

Formal 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

Thermomyces 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

Adsorption 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

The 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

A 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

Nineteen 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

Thermolysin 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

Experimental 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.
A methodology for screening hydrocracking catalysts
Authors: Prasad Rameshwar , Dabral Rameshwar P. , Wadehra Brij M. L. , Moolchandra R. , Mittal Krishan G.
Published: May 2005

Hydroconversion of n‐heptane and toluene has been studied over a commercially proven Ni–W/SiO2–Al2O3 amorphous base hydrocracking catalyst (suitable for maximizing middle distillates production from heavier feedstocks) under a wide range of operating conditions (pressure: 400–1200 psig; temperature: 315–360°C, liquid hourly space velocity (LHSV) ≃ 1 h−1 and molar hydrogen/hydrocarbon feed ratio: 6–8) to assess the hydrogenation and cracking activities of the catalyst screening. Hydroisomerization followed by hydrocracking, ad hydrogenation followed by isomerization have been found to be the major reaction with n‐heptane and toluene respectively as the feeds. The hydroconversion of toluene gives a very high selectivity of hydrogenated product. With n‐heptane, a very high selectivity of hydroisomerized product, together with a high ratio of hydroisomerized to hydrocracked product, is obtained.
Pore entry effects in the solvent‐induced swelling of low‐rank coals
Authors: Jones J. C. , Prawitasari B.
Published: May 2005

The swelling of a low‐rank coal under the influence of various solvents is examined and results compared with those for a similar coal in briquetted from. Results are interpreted in terms of the effects of briquetting on pore structure.
Kinetic behavior of yeast alcohol dehydrogenase in AOT/isooctane reverse micelles
Authors: Chen Dong‐Hwang , Chen Hsien‐Hsin , Huang Ting‐Chia
Published: May 2005

The kinetic behavior of yeast alcohol dehydrogenase (YADH) in sodium di‐2‐ethylhexylsulfosuccinate (AOT) isooctane reverse micelles has been studied using methyl ethyl ketone (MEK), NADH and Tris as the substrate, coenzyme and buffer, respectively. The solubility diagrams of aqueous buffer in the isooctane solution of AOT were established as a function of temperature and molar ratio of water of surfactant (ω0) at various Tris and AOT concentrations. The dependence of enzyme activity on enzyme concentration, pH, ω0 and Tris concentration was determined. The optimal ω0 was at 10–15, increasing slightly with an increase in Tris concentration. The YADH entrapped in reverse micelles exhibited minimum activity at a Tris concentration of 0·1 mol dm−3, while in aqueous buffer enzyme activity was not significantly affected by Tris concentration. Comparing the rate equation of the reduction of MEK by YADH in reverse micelles with that in aqueous buffer, the association of YADH and NADH could apparently have proceeded with an irreversible reaction before the substrate was bound, when performed in a reverse micellar system. Although the YADH entrapped in reverse micelles was less stable than when dissolved in aqueous buffer, the enzyme retained at least 20% activity after 21 h at 25°C and ω0 = 20. This result was an improvement over previously reported data.
Influence of the organic volumetric loading rate on soluble chemical oxygen demand removal in a down‐flow fixed‐bed reactor treating abattoir wastewater
Authors: Borja Rafael , Banks Charles J. , Martín Antonio
Published: May 2005

A laboratory‐scale anaerobic down‐flow fixed‐bed reactor, operating at 35°C, was used to treat abattoir wastewater at input soluble chemical oxygen demand (COD) levels ranging from 4·7 to 28·7 g sm−3 and volumetric organic loading rates ranging from 2·5 to 25 g COD dm −3 day −1. Start up of the reactor was achieved within 35 days using a regime that include stepped increases in input COD and methanol substitution. The effects of the organic volumetric loading rates on soluble (COD) (SCOD) removal were studied at four feed SCOD concentrations between 4·7 and 28‐7 g dm−3. An exponential dependency of the organic volumetric loading rate with the SCOD removal was observed in the range of loading studied, with variation between 1 and 12 g COD sm−3 day −1 Further increases of the organic loading rates has smaller effects on SCOD removal. A pseudo first‐order kinetic model was used to obtain the gross removal coefficients, the values of which were virtually independent of the feed COD concentration at 6·9 to 7·3 g COD dm −3 day −1. The methane yield coefficient decreased slightly from 0·34 to 0·31 dm 3 g −1 COD when the feed SCOD concentration was increased from 4·7 to 28·7 g dm −3.
Separation of (3S, 3′S)‐, (3R 3′R)‐ and (3S, 3′R)‐astaxanthin via (−)‐camphanic acid esters
Authors: Vecchi Max , Müller Robert K.
Published: May 2005

A method is described for the qualitative and quantitative determination of configurational isomers of astaxanthin. It is based on the esterification of astaxanthin with (—)‐camphanic acid chloride and analysis of the corresponding diesters by HPLC.
Polygon diagrams of chromatographic data
Authors: Janssens Guido
Published: May 2005

Use of a Hewlett‐Packard 2648 A graphics terminal connected to a HP 3354 B Laboratory Automation System for drawing polygon diagrams of chromatographic data has been investigated. The computer program is designed to reduce polygon overlapping and hiding by fully automatic parameter adjustment.
A study of the effects of temperature and pressure on the retention time in series‐coupled columns under conditions of constant mass flow rate
Authors: Buys T. S. , Smuts T. W.
Published: May 2005

The technique of controlling chromatographic selectivity by the adjustment of column temperatures in systems of series‐coupled columns is investigated by means of a general model incorporating the effects of temperature and mobile phase compressibility. In a previous article the performance of series‐coupled columns was investigated under conditions of constant overall pressure drop. The present paper, on the other hand, considers systems in which a constant mass flow rate is maintained at all temperatures. The expressions derived for the effective partition coefficient and the retention time are compared with those of the previous paper. The numerical results for two‐column systems exhibit the same major trends as those for constant pressure drop. It is shown that the effective partition coefficient is slightly dependent on the mass flow rate.
Quantitative evaluation of thin‐layer chromatograms. 4. Calculation of fluorescence using Bodó equations
Authors: Pršsek M. , Medja A. , Kučan E. , Katifč M. , Bano M.
Published: May 2005

Changes in fluorescence intensity at the far and near side for various spot locations in a sorbent are calculated using a multilayer model and Bodó equations for each sublayer. Flow charts are given for evaluation of reflectance transmission, and fluorescence.
Separation of isomers of nitro‐polycyclic aromatic hydrocarbons
Authors: Greibrokk T. , Iversen B. , Johansen E. J. , Rønningsen H.‐P. , Svendsen H.
Published: May 2005

Since positional isomers of several nitro‐polycyclic aromatic hydrocarbons (nitro‐PAH) contain widely different mutagenic properties, methods for separating the isomers were investigated. High performance liquid chromatography with dichloromethane in hexane on silica gave the best resolution for the majority of the compounds. A few groups of isomers were better resolved with other modifiers or with reversed phases. Of the reversed phase systems, methanol‐water gave better resolution than acetonitrile‐water. With dichloromethane/hexane on silica, the retention was found to depend on the presence of a bay nitro group (first), the number of H atoms peri to the nitro group (second), and the length/breadth ratio of the molecule (third).

Front electron density calculations were combined with the structure‐retention relations in making tentative structure assignments of minor isomers of nitro‐PAH.
Two‐dimensional gas chromatography for determination of volatile compounds in ambient air
Authors: Berg S. , Jonsson A.
Published: May 2005

A two‐dimensional gas chromatograph is described for the analysis of volatile compounds. The chromatographic system consists of two separate chromatographs linked together with an interface containing an intermediate trap. The trap is cooled with nitrogen (−150°C) and a cryogradient is created inside the trap enclosure. The sample is reinjected during controlled (chromatographic) conditions, using thermostated air. The sample components are eluted from the trap as narrow symmetrical peaks; the shape and width of the peaks eluted do not noticeably affect the subsequent chromatography. The enrichment of n‐butane in the trap is quantitative in the range 10−10 – 10−5 g.