bluuebunny/crossref_metadata_2025_split huggingface dataset:
Catalysis by intermetallic compounds II. The behaviour of the pseudobinary alloy systems CeRh3–x Pdx and ZrRh3–xPdx for buta‐1,3‐diene hydrogenation
Authors: Bahia Amrik , Harris I. Rex , King Charles E. , Winterbottom John M. 
Published: May 2005

AbstractThe hydrogenation of buta‐1,3‐diene in the temperature range 45–110°C at 1 bar (101·5 kPa) total pressure has been studied using the pseudo‐binary alloy systems MRh3–x Pdx (M = Ce, Zr; 0 ≤ x ≤ 3) as catalysts. Characterisation studies show that surface and bulk Rh/Pd ratios are very similar but the surfaces were enriched particularly in cerium, with strong indications of oxide formation. Similar conclusions can be drawn with respect to zirconium but to a smaller extent. Differencs in product distributions, particularly in butene distributions are discussed in terms of two mechanisms which can interpret differences between the Rh‐rich system and the Pd‐rich system in respect of cis/trans‐but‐2‐ene ratios.
Effect of glucose concentration on citric acid production by Yarrowia lipolytica
Authors: Moresi Mauro 
Published: May 2005

AbstractCitric acid production by Yarrowia lipolytica ATCC 20346 was studied in a laboratory‐scale fermenter and schematically subdivided into three different phases, appropriately characterised by unstructed kinetic models. As the sugar level in the growth medium was increased from 40 to 108 g dm−3; a negative effect on the kinetic growth rate constant of the trophophase was obtained, where both the yield coefficients for glucose and nitrogen were found to be approximately constant. By using a production medium devoid of nitrogen, a citrate lag phase was observed whilst the yeast reduced its intracellular nitrogen fraction from 7–8% (w/w) to a new equilibrium value as low as 2·3–4·4%. Finally, the idiophase was found to be a non‐growth associated process, the citric acid formation rate being dependent on the cellular nitrogen concentration only. The yield factors for citric, isocitric and fumaric acids appeared to be independent of the initial concentration of glucose in the production medium (Sop). However, the yield factors for α‐ketoglutaric, malic, pyruvic and cis‐aconitic acids exhibited a negative correlation with respect to Sop, being virtually equal to zero for Sop values greater than 160–175 g dm−3. The strain in question was capable of equalling the best mutant strains of Aspergillus niger used industrially in citric acid productivity (ca. 1·05 g dm−3 h−1), but not in selectivity, since citric acid represented only 85·5% of total citric and isocitric acid and 83·7% of the total acid.
Activated carbon from sugar cane bagasse by carbonization in the presence of inorganic acids
Authors: Girgis Badie S. , Khalil Laila B. , Tawfik Tarek A. M. 
Published: May 2005

AbstractDried ground bagasse, impregnated with 50% inorganic acids and carbonized at 500°C, showed the sequence H3PO4 > H2SO4 > HCl > HNO3, with respect to the efficiency of activation. Treatment with phosphoric acid of various concentrations (30–50 wt%) was followed by carbonization at 300–500°C for 3 h. Pore structure parameters were determined from the low‐temperature adsorption of nitrogen, by applying the BET and αs methods. Activated carbons obtained at low temperatures are essentially microporous with a low degree of mesoporosity. At higher temperatures products of higher surface area and total pore volume with developed mesoporosity and low microporosity are formed. An increase in the period of carbonization leads to a small decrease in both surface area and pore volume. Activated carbons with surface areas > 1000 m2 g−1 and mean pore dimensions around 2·0 nm, suitable for various purposes, are thus obtained.
Preparation of substituted carbonyl compounds by catalytic dehydrogenation of substituted alcohols
Authors: Gulková Daniela , Kraus Miloš 
Published: May 2005

AbstractPossibilities for the preparation of substituted ketones by catalytic dehydrogenation of corresponding secondary alcohols were explored using a ZnO–Cr2O3 catalyst at 370–400°C. It was found that addition of about 1 wt% of sodium to the catalyst increases the yield of the ketone because the competitive dehydration of the alcohol is suppressed. Further improvement of the process was achieved by adding 20 wt% of water to the alcohol feed, which inhibited catalyst deactivation. Preparative experiments were conducted and 1‐methoxy‐2‐propanone, 1‐methoxy‐2‐butanone, 1‐phenoxy‐2‐propanone and 2‐methoxy‐1‐cyclohexanone were obtained.
Fourier‐transform infrared assay of bile salt‐stimulated lipase activity in reversed micelles
Authors: O'Connor Charmian J. , Cleverly Douglas R. 
Published: May 2005

AbstractA Fourier‐transform infrared (FT‐IR) spectroscopic method has been developed for assaying the bile salt‐stimulated human milk lipase (BSSL, EC3.1) catalyzed hydrolysis of triolein in AOT reversed micelles in iso‐octane. At 37°C in 50 mmol dm−3 AOT the molar absorbtivities for the carbonyl stretching frequencies for triolein (at 1751 cm−1) and oleic acid (at 1714 cm−1) were 1646 dm3 mol−1 cm−1 and 743 dm−3 mol−1 cm−1, respectively. The rate was linearly dependent upon the concentration of enzyme in the water pool up to 10 mg cm−3 and maximum activity was observed at a ratio (w0) of [H2O]:[AOT] = 16·7. Using these conditions, and in the presence of 10 mmol dm−3 sodium taurocholate (TC), the derived Michaelis–Menten parameters Vmax and Km were 57·5 μmol min−1 mg−1 and 5·53 mmol dm−3, respectively. These results are compared with those obtained in an oil‐in‐water microemulsion system and are discussed in terms of the relative partitioning of the enzyme and the substrate in the aqueous and oil phases and the interfacial concentration of the substrate in the two systems.
Narrowing of alkylphenol ethoxylate distribution
Authors: Barhoum R. , Szymanowski J. , Hreczuch W. , Meissner Egbert 
Published: May 2005

AbstractThe homologue distribution of alkylphenol ethoxylates can be narrowed by using the non‐standard catalyst proposed for alcohol ethoxylation. The reaction is carried out at 180–185°C in the presence of 0·3% catalyst in relation to the alkylphenol. The formation of increased amounts of dioxane and polyglycols is not observed.
Synergistic extraction of penicillin G with aliphatic alcohols and butyl acetate
Authors: Yang Zhi‐Fa , Yu Shu‐Qiu , Chen Jia‐Yong 
Published: May 2005

AbstractA solvent mixture of 1‐hexanol and butyl acetate has been successfully used for the extraction of penicillin G. This solvent mixture may not only synergistically and effectively extract penicillin G, but also inhibit emulsion formation during the extraction of penicillin G from the filtrate of the fermentation broth. The equilibrium constants of the extraction, the molar ratios of 1‐hexanol and penicillin G in the extracted species and the synergistic extraction of penicillin G have been studied by chemical analysis and by monitoring the absorbency shift in the FT‐IR spectra of the functional groups in the solvents.
The separation of pectinlyase from β‐glucosidase in a commercial preparation
Authors: Martino Angela , Pifferi Pier G. , Spagna Giovanni 
Published: May 2005

AbstractThis paper describes a new, simple and inexpensive procedure for separating pectinlyase (PL, EC 4.2.2.3) from β‐glucosidase (β‐glu, EC 3.2.1.21), both of which have potential for use in the beverage processing industry. The method described here, which entails the treatment of crude preparations with bentonite (4% (w/v)) and the acidification of the resulting supernatant to pH 3·5, leads to the production of two enzymic solutions which contain PL and β‐glu, respectively. In both solutions the amount of brown pigment is considerably less than in the crude mixture, and partial purification from extraneous proteins is also achieved.
Heavy metals in the environment. Part IV: An investigation into the solubility of metal chlorides in HCl‐saturated solutions and the recycling of high‐aluminium zinc residues in the zinc chloride process
Authors: Chaudhary Abdul J. , Donaldson John D. , Grimes Susan M. , Boddington Stephen C. 
Published: May 2005

AbstractAn investigation into the solubility of aluminium and lead chlorides in HCl‐saturated zinc chloride solutions and the use of high‐aluminium zinc residues in the production of zinc chloride solution is reported. The process developed involves leaching of the high‐aluminium zinc residues with concentrated hydrochloric acid followed by HCl gas treatment to reduce the concentration of aluminium and lead from zinc chloride solutions. The solubility of aluminium and lead chlorides in HCl‐saturated solutions depends on the zinc chloride concentration. The optimum zinc chloride concentration for maximum reduction in the aluminium and lead levels is 30–55% and 53% (w/w) respectively. Under optimum conditions the aluminium and lead concentrations are reduced to less than 0·1 and 0·9 mg cm−3 respectively.
Applications of supercritical CO2 extraction to microalgae and plants
Authors: Mendes Rui L. , Coelho José P. , Fernandes Helena L. , Marrucho Isabel J. , Cabral Joaquim M. S. , Novais Júlio M. , Palavra Antóanio F. 
Published: May 2005

AbstractA flow apparatus was constructed to carry out studies of supercritical fluid extraction in the temperature range 298·15–353·15 K and pressures up to 40 MPa. To test the apparatus, studies on the solubility of naphthalene in CO2 at 308·15, 313·15 and 318·15 K and pressures up to 35 MPa were carried out. These experimental data were correlated through the Peng–Robinson equation of state. Samples of the microalgae Botryococcus braunii and Chlorella vulgaris which produce diolefines C25–C31 and carotenoids, respectively, were submitted to supercritical CO2. The extraction yields for these compounds were studied and compared with those obtained using organic solvents. Supercritical CO2 was also used to produce extracts from rosemary leaves (Rosmarinus officinalis L.), which were compared with those obtained by hexane extraction.
Resistance of recombinant proteins to proteolysis during folding and in the folded state
Authors: Fountoulakis Michael 
Published: May 2005

AbstractProtein purification often involves the use of denaturing agents for solubilization. During refolding, following removal of the denaturants, the proteins of interest are exposed to proteases present in the expression system. Here the resistance of selected recombinant proteins to three widely used proteolytic enzymes, trypsin (EC 3.4.21.4), proteinase K (EC 3.4.21.14) and endoproteinase Glu‐C (EC 3.4.21.19), was investigated during folding and in the folded state. Target proteins and protease mixtures were denatured in 8 mol dm−3 urea and the proteins were allowed to refold by removal of the urea by dialysis. The proteolytic products were analyzed by sodium dodecyl sulfate–polyacrylamide gels and the protein digestion during folding was compared with the digestion under similar conditions in physiological buffer. Depending on the folding state of the proteins, the proteases had different effects on the substates. During folding, certain recombinant proteins were more efficiently digested by trypsin and, in particular, by proteinase K in comparison with digestion in the folded state, while other protein substrates were more resistant to proteolytic degradation in a denatured or partially denatured state than their folded counterparts. Incubation of most substrate proteins with endoproteinase Glu‐C yielded kinetics of digestion that were essentially similar for both partially folded and unfolded substrates. The results reported may be useful for protection of sensitive proteins and in studies of protein folding mechanisms.
Estimation of the energetic parameters associated with the aerobic degradation of quinoline by Comamonas acidovorans in continuous culture
Authors: Solomon Bamidele Ogbe , Hecht Volker , Posten Clemens , Deckwer Wolf‐Dieter 
Published: May 2005

AbstractAn estimation of the true growth yields and maintenance coefficients for Comamonas acidovorans DSM 6426 under continuous cultivation on quinoline has been performed. The data were checked for consistency using available electron, carbon and nitrogen balances. The true biomass energetic yields, ηmax, and energetic maintenance coefficients, me, were estimated using two models based on control of growth rate and control of substrate uptake rate, respectively. The estimations were converted to the various familiar true growth yield and maintenance units such as substrate‐based (Y, mS/X), oxygen‐based (Y, m) and carbon dioxide‐based (Y, m) units. For the complete mineralization of quinoline by C. acidovorans, values of ηmax = 0.371 and me = 0·0426 h−1 were obtained.
Electrooxidation of dyestuffs in waste waters
Authors: Allen Stephen J. , Khader Kayed Y. H. , Bino Murad 
Published: May 2005

AbstractAn electrochemical oxidation cell is used to reduce the concentrations of organic dyes and chemical oxygen demand in an aqueous effluent. The importance of the presence of an electrolyte is recorded and the effects of changing both electrolyte concentration and initial dye concentration are reported. The rate of the electrooxidation process is shown to be a pseudo‐first‐order kinetic process with the rate constant being affected by both the electrolyte concentration and the dye concentration. The use of different electrolytes is reported.
Adsorption of Pb2+ on blast furnace sludge
Authors: Lopez Felix A. , Perez Carlos , Sainz Enrique , Alonso Manuel 
Published: May 2005

AbstractAn evaluation of the applicability of blast furnace sludge, generated during the purification of blast furnace gases, as an adsorbent to remove heavy metals from industrial effluents is presented. The influence of residence time and temperature on the adsorption efficiency of the sludge is studied for the particular case of Pb2+. The adsorption data, which fit the Langmuir equation well, show that the blast furnace sludge has a high adsorption capability, up to 80 mg Pb per g dried sludge at saturation. The order of magnitude of the adsorption enthalpy, calculated from the apparent equilibrium constant, indicates that the adsorption of Pb2+ on the sludge is of a physical nature. XPS and EDAX analysis suggest that the physical adsorption process partially occurs through ionic exchange between Pb2+ and other ions such as Ca2+. Techniques exist for the recovery of metallic iron and either metallic lead or lead oxide from the sludge. The rendering of sludge into pellets, followed by their controlled heating, allows not only the extraction of these metals, but also makes use of the coke within the sludge. These techniques are clearly interesting alternatives to the dumping of this toxic and hazardous waste.
Epoxidized polyurethaneamide and polyesteramide as petroleum pipeline coatings
Authors: Motawie Ahmed Magdy , Hassan El‐Said Ali , Manieh Atef , Aboul‐Fetouh Mostafa , El‐Din Ashraf Fakhr 
Published: May 2005

AbstractLinseed oil fatty acids were epoxidized by peracetic acid, then reacted with diethanolamine to give epoxidized hydroxy ethyl linseed oil fatty acid amide (I). This amide was rejected with toluene diisocyanate to produce epoxidized polyurethane‐amide (II). Component I was also reacted with phthalic anhydride to give epoxidized polyesteramide (III). Resins II and III were evaluated as coating materials. The results obtained were compared with commercial epoxy resin, and show that resins II and III may be suitable to use as petroleum pipeline coatings.
Structure–basicity relationships for pyridine extractants
Authors: Szymanowski Jan , Borowiak‐Resterna A. , Voelkel A. 
Published: May 2005

AbstractTopological indices are determined for models of prospective pyridine extractants and the relationships structure–topological index and topological index–pyridine nitrogen basicity are described. The second order valence molecular connectivity index, the Balaban index and the Wiener number are appropriate structural descriptors of pyridine derivatives and, in several cases, permit the pyridine nitrogen basicity to be predicted. The relationships between pKa values and the structural descriptors are given and described.
Catalysis by superacidic zirconia: Transalkylation of di‐isopropylbenzene with benzene and substituted benzenes
Authors: Suresh R. , Rajadhyaksha R. A. , Kumbhar P. S. 
Published: May 2005

AbstractThe transalkylation reaction of di‐isopropylbenzene with benzene and substituted benzenes over sulphate‐treated superacidic zironia catalyst was studied. The catalyst was found to show comparable activity to that of zeolite and acid‐treated clay (Filtrol‐24). However, it was found to deactivate because of the heavy compounds in the starting reaction mixture and coke formation.
Chemical degradation of aldicarb in water using ozone
Authors: Beltrán Fernando J. , Alvarez Pedro M. , Legube Bernard , Allemane Hellene 
Published: May 2005

AbstractThe use of ozone to degrade aldicarb in water was investigated under different conditions. The oxidation develops through the direct attack of ozone since the presence of hydroxyl radical inhibitors, such as tert‐butanol, does not affect the degradation rate of aldicarb. The combination of ozone with hydrogen peroxide does not improve the oxidation rate which also confirms the absence of radical reactions to eliminate aldicarb. However, TOC removal increases 51% in the presence of hydrogen peroxide after 65 min of oxidation. The oxidation rate is strongly affected by the type of device for feeding ozone, which indicates that a fast gas‐liquid reaction is taking place. Therefore, mass transfer and chemical reaction steps are important factors in the establishment of the global rate of oxidation. Application of kinetic equations derived from gas absorption theories allows the determination of the rate constant of the direct ozone–aldicarb reaction, which was found to be: k = 3·18 × 1011 exp(–6000/T) m3 mol−1s−1.
Influence of the gas—liquid separator design on hydrodynamic and mass transfer performance of split‐channel airlift reactors
Authors: Choi Keun H. , Chisti Yusuf , Moo‐Young Murray 
Published: May 2005

AbstractThree geometric configurations of gas–liquid separators were used in split‐channel airlift reactors (0·1 m3 liquid volume; riser‐to‐downcomer cross‐sectional area ratio = 0·7; aspect ratio = 3.6) to test the effect of geometry on hydrodynamic performance and oxygen transfer behaviour. For otherwise fixed conditions, the design of gas–liquid separators affected the induced liquid circulation rate, the depth of penetration of the bubble layer in the downcomer, the gas holdup in the downcomer, the mixing time and the overall volumetric gas–liquid oxygen transfer coefficient. The gas holdup in the riser was only marginally affected by the design of the separator. The impact of the various separator designs on hydrodynamic behaviour could be explained as emanating from a combination of the gas–liquid separating ability of the design and its hydraulic resistance.
Enzymatic resolution of 1‐ferrocenylethanol and 1‐ferrocenyl‐2,2,2‐trifluoroethanol using lipases
Authors: Izumi Taeko , Aratani Satoshi 
Published: May 2005

Abstract1‐Ferrocenylethanol and 1‐ferrocenyl‐2,2,2‐trifluoroethanol were resolved with transesterification by lipases to the optically active (R)‐esters and (S)‐alcohols. Enzymatic hydrolysis of the racemic esters of 1‐ferrocenylethanol using lipases yielded (R)‐alcohol and (S)‐esters. Enantioselective hydrolysis of racemic acetate or butanoate of 1‐ferrocenyl‐2,2,2‐trifluoroethanol yielded the (S)‐alcohol and (R)‐esters. Enzymatic hydrolysis of (±)‐acetate of 1‐ferrocenyl‐2,2,2‐trifluoroethanol yielded (R)‐alcohol and (S)‐acetate, but the equivalent (±)‐butanoate was not hydrolyzed.
Aqueous solutions of hydrotropes as effective reaction media for the synthesis of 4‐aryl‐1,4‐dihydropyridines
Authors: Sadvilkar V. G. , Khadilkar B. M. , Gaikar V. G. 
Published: May 2005

AbstractThe condensation of benzaldehydes with acetoacetic esters and ammonia was carried out in aqueous solutions of aliphatic hydrotropes. Substantial enhancement in the rates of the reactions along with easy recovery of the product were noted. The recyclabilty of the hydrotropes has also been tested.
Molecular transport characteristics of a chlorosulfonated polyethylene geomembrane in the presence of aromatic esters
Authors: Aminabhavi T. M. , Munnolli R. S. 
Published: May 2005

AbstractResults of a study on sorption and diffusion of chlorosulfonated polyethylene geomembrane with methyl benzoate, ethyl benzoate, methyl salicylate, iso‐butyl salicylate, phenyl acetate, and diethyl phthalate in the temperature range 25–60°C are presented. A gravimetric sorption method is used to calculate the diffusion and permeation coefficients from the Fickian relationship. The diffusion results are dependent on penetrant–membrane interactions, temperature, and on penetrant concentration. The values of diffusion coefficients range from 0·02 × 10−7 cm2 s−1 for diethyl phthalate at 25°C to 1·81 × 10−7 cm2 s−1 for ethyl benzoate at 60°C. The activation energies for diffusion range from 21 to 50 kJ mol−1. The values of heat of sorption ranged between 2·2 and 6·4 kJ mol−1. Sorption results are also analyzed using a first‐order sorption kinetic equation. Experimental results and calculated parameters are used to discuss the transport behavior. None of the esters used have shown any chemical attack toward the geomembrane.
Study of water repellent effect of earth substrates impregnated with water‐based silicones
Authors: Ren Kebao , Kagi Douglas A. 
Published: May 2005

AbstractAs part of a study to assess the efficacy of impregnation for masonry materials, the impregnation of earth substrates with soluble sodium silicate followed by water‐based silane/siloxane emulsion was investigated. The treatment was found to be successful in achieving water repellent and consolidation effects for the earth substrates. The water repellent effect is developed by the silane/siloxane emulsion which forms a polysiloxane thin film on the capillary wall surface through siloxane bonds. The water repellent effect is greatly enhanced by pre‐impregnation with the silicate. The consolidation of the earth substrate by soluble sodium silicate is caused by the silicate gel formed by crosslinking with the substrate. The water repellent and consolidation effects in the earth substrates have been studied by using water absorption tests and FTIR examination.
Biosorption of heavy metals by Saccharomyces cerevisiae: Effects of nutrient conditions
Authors: Engl Andrea , Kunz Benno 
Published: May 2005

AbstractStudies took place to investigate the effects of different nutrient conditions on the biosorption ability and selectivity of heavy metals by Saccharomyces cerevisiae. After having grown in media supplemented with additional glucose, ammonium, phosphate or cysteine, the yeast was exposed to an equimolar solution of lead, cadmium, zinc and copper. Lead removal from a mixed solution was significantly higher than that of copper, followed by zinc and cadmium. Generally, yeasts from cysteine‐rich media showed greatest sorption capacity whereas phosphate addition influenced zinc selectivity. In addition, glucose, fructose and sucrose as carbon sources were examined. Cultures grown in glucose had a better uptake than those cultivated with fructose at an incubation time of 30 min.
Selective manipulation of only one of two similar sites within a molecule ‘odin reactions’: Strategic advantage for synthesis and tactics available
Authors: Milner David J. 
Published: May 2005

AbstractApproaches used to effect selective reaction at one of two or more similar sites in a molecule are reviewed. The nature of the problem is defined and the strategic advantage to be gained through the use of symmetrical intermediates is outlined early and re‐emphasised throughout the discussion with specific examples of multistage syntheses of important products. The various tactics used to effect site selectivity in a late synthetic step are described in a logical sequence and presented in a form aimed to help in the design of syntheses of unsymmetric products from symmetric intermediates.