bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diels‐alder reaction: New antimicrobial pyrazolo‐chroman derivatives
Authors: Abd el Latif F. M. , Maghraby A. S. , Barsy M. A. , Badr M. Z. A. 
Published: July 2010

AbstractPyrazolo‐[2,3‐d]‐chroman dione derivatives were obtained via Diels‐Alder reaction of pyrazolone arylidenes and 1,4‐benzoquinone. The reaction rate and its yield have been found to be solvent and time dependent. The evaluation of the bactericidal and fungicidal screening showed significant inhibition effects against some thermophilic organisms grown and incubated at 55°C.
The preparation and properties of magnesia catalyst supports
Authors: Sidjabat O. , Trimm D. L. , Wainwright M. S. 
Published: July 2010

AbstractThe preparation of magnesia has been investigated with the object of preparing a catalyst support material that maintained high surface area after heating to high temperatures. The effect of precipitation, ageing, washing, drying and calcining on the surface area and porosity of magnesia has been studied. It was found possible to produce stable magnesia by washing with methanol or acetone, but the surface area was low for most catalytic applications.
Kinetic studies on dehydrogenation of butanol to butyraldehyde using zinc oxide as catalyst
Authors: Raizada V. K. , Tripathi V. S. , Lal Darshan , Singh G. S. , Dwivedi C. D. , Sen A. K. 
Published: July 2010

AbstractButyraldehyde is an important chemical for many industrial applications, especially in the production of polyvinylbutyral. A systematic study of its synthesis by catalytic dehydrogenation of butanol, using zinc oxide as catalyst has been carried out. The effect of the method of preparation of zinc oxide on its catalytic activity for the title reaction has also been studied. The optimum conditions for maximum yield have been worked out and on the basis of secondary electron micrograms the reasons for higher activity/selectivity in the case of zinc oxide calcined from zinc hydroxide is attributed to the presence of hexagonal morphology. A kinetic study for the best zinc oxide catalyst has been carried out and the rate equation has been determined.
Kinetics of carbonization of calcium sulfide in water suspension
Authors: Nishev T. , Pelovski Y. 
Published: July 2010

AbstractThe carbonization of CaS in water suspension was studied. The process takes place under diffusion control. The complicated process mechanism causes the appearance of a compensation effect. By increasing the carbon dioxide partial pressure, the probability of interaction is raised, which leads to the increase of the pre‐exponential factor. When the chemical reaction is faster then less porous CaCO3 is deposited and as a result the apparent activation energy is increased.
Kinetic properties of the periplasmic hydrogenase from Desulfovibrio desulfuricans NCIMB 8372 and use in photosensitized H2‐production
Authors: Eng Lars H. , Lewin Mona B.‐M. , Neujahr Halina Y. 
Published: July 2010

AbstractThe periplasmic hydrogenase (hydrogen: ferricytochrome‐c3 oxido‐reductase EC 1.12.2.1) from Desulfovibrio desulfuricans (NCIMB 8372) was isolated and the catalytic properties of the enzyme determined with different electron mediators.In the direction of H2‐oxidation with the physiological electron mediator cytochrome c3, the value of the apparent second order rate constant (kcat/Km) is close to that expected for a diffusion‐controlled reaction. In H2‐production however, the value of kcat/Km with cytochrome c3 is almost 200 times lower. When methyl viologen is used as mediator, the value of kcat/Km is the same in both directions and is intermediate to the values obtained with cytochrome c3.The close to optimum value of kcat/Km in H2‐oxidation with cytochrome c3 as electron acceptor is discussed with respect to the biological role of this and related hydrogenases.H2‐production occurred with the hydrogenase in a system where the mediator was reduced with either of three photosensitizers (proflavin, 5‐deazariboflavin, Zn‐tetraphenyl porphyrin sulphonate) upon illumination. The efficiency of different mediators is discussed.
Recovery of lanthanides from kola apatite in phosphoric acid manufacture
Authors: Zielinski Stefan , Szczepanik Anna , Buca Marek , Kunecki Miroslaw 
Published: July 2010

AbstractThe paper presents the results of bench‐scale studies for the recovery of lanthanides from Kola apatite in the phosphoric acid production by a two‐stage hemihydrate‐dihydrate wet‐process. The second stage of the process (hydration of hemihydrate) provides the best conditions for the recovery of lanthanides. In the postulated recovery process use is made of solvent extraction for the removal of lanthanides during hydration of hemihydrate, and precipitation‐stripping for the removal of lanthanides from the solvent. Lanthanides are recovered in the form of Ln‐enriched concentrates with an efficiency of 80–85%. The process does not disturb the phosphoric acid production, and additionally purifies the by‐product gypsum, so that it can be utilized.
Sulphide inhibition of methanogenic activity at various pH levels at 55°C
Authors: Visser A. , Nozhevnikova Alla N. , Lettinga G. 
Published: July 2010

AbstractThe purpose of this study was to evaluate the toxic effect of sulphide on thermophilic methanogenic bacteria, pre‐cultivated in UASB‐reactors fed with and without sulphate, at 55°C and different pH levels. For granular sludge, precultivated in the presence of sulphate, the inhibition caused by hydrogen sulphide was dependent on the pH imposed. At alkaline pH the inhibitory effect of hydrogen sulphide was higher than at neutral or acidic pH. The effect of sulphide could not be described in terms of free hydrogen sulphide level only. For dispersed sludge, pre‐cultivated in the absence of sulphate, the inhibition caused by free hydrogen sulphide was independent of the pH, and the toxic effect of sulphide could be described in terms of free hydrogen sulphide.
A novel approach to the production of clinical‐grade dextran
Authors: Barker P. E. , Ganetsos G. , Ajongwen N. J. 
Published: July 2010

AbstractEfficient unit operations for the production and purification of the enzyme dextransucrase and the biosynthesis and fractionation of dextrans have been developed and tested. An alternative process for the production of clinical‐grade dextran has been proposed by integrating these processes to achieve improved dextran product yield and the recovery of fructose as a valuable byproduct. The enzyme dextransucrase, which synthesizes dextran from sucrose, has been produced either by non‐aerated fed‐batch or continuous fermentations, purified by continuous ultracentrifugation and ultrafiltration and used in a bio reactor‐separator stage for the biosynthesis of dextran. High molecular weight dextrans have been biosynthesized on continuous counter‐current chromato‐graphic bioreactor‐separator systems. Membrane filtration and size exclusion continuous chromatography were used for the fractionation of the native dextran and production of clinical‐grade dextran. The advantages of the proposed process over the conventional process are related to cost reduction due to the elimination of ethanol usage and recovery, improved product quality control and the production and recovery of fructose as a by‐product.
Mechanistic study of cobalt, nickel and copper transfer across a supported liquid membrane
Authors: Marchese José , Campderrosa Mercedes E. , Acosta Adolfo 
Published: July 2010

AbstractThe mechanism of cobalt, copper and nickel transport through supported liquid membranes containing di(2‐ethylhexyl)phosphoric acid as a mobile carrier has been studied. An equation describing the permeation rate has been derived, taking into account stagnant layer aqueous diffusion, interfacial resistance due to solvatation reaction and liquid membrane diffusion as simultaneous controlling factors. The validity of this model is evaluated with experimental data of mass transfer coefficient measured employing a permeation cell. For these ions it was found that at low stirring conditions the stagnant layer resistance mainly controlled the processes, but it is controlled by diffusion of the ion complex through the supported liquid membrane when the stagnant layer resistance is negligible.
Synthesis and surface activity of nonionic surfactants containing fluorocarbon hydrophobes
Authors: Meissner Egbert , Myszkowski Jerzy , Szymanowski Jan , Barhoum Rakan 
Published: July 2010

AbstractNonionic surfactants having polydisperse polyoxyethylene chains and highly fluorinated hydrophobes were synthesized via a complex reaction route and their adsorption at water/air interfaces studied. They exhibit high surface activity and decrease both effectively and efficiently the surface tension of their aqueous solutions. The effect of the length of the polyoxyethylene chain upon surfactant surface activity is relatively low. Lower values of surface tension, below 30 mN m−1, are obtained for surfactants having a low degree of ethoxylation. Surfactants having two terminal highly fluorinated hydrophobes are less surface active than analogues with one terminal hydrophobe.
Removal of aldehydes by amino acids and their salts in ambient air
Authors: Sugiura Masahiro , Fukumoto Kazuhiro 
Published: July 2010

AbstractThe removal of gaseous aldehydes by amino acids and by their sodium salts and hydrochlorides was studied in ambient air with the relative humidity of 30% at 25°C. Amino acid sodium salts, diamino acids, sodium p‐aminobenzoate (PABANa), and o‐aminobenzoate (OABANa), and p‐aminobenzoic acid (PABA) on sepiolite, both having a carboxylato functionality (COO−) together with an amino (NH2) group, were highly reactive with aldehydes. In contrast, PABA which has free carboxylic acid functionality (COOH: dimeric) was not so reactive with aldehydes. Normal amino acids and their hydrochlorides having ammonio (NH2+) and COO− or COOH (dimeric) groups were less reactive with aldehydes. The reactivity was closely related to the degree of dissociation of carboxylate anion; as the degree of dissociation increases, the compound becomes more reactive. p‐Aminobenzoic acid hydrochloride (PABA · HCl), having NH3+ and COOH (monomeric) groups, was the most reactive (with ethanal) of all the amino acids and their salts examined. Amino acid sodium salts, diamino acid, PABANa, OABANa, and PABA on sepiolite are proved to be excellent removers of aldehydes in ambient air. Among them, PABA · HCl is particularly good for ethanal.
Simple method for the simultaneous evaluation of combustion and selective oxidation catalysts
Authors: Ramdasi Sudhakar S. , Kulkarni Suresh Y. , Gokarn Ashok N. , Pande Anita R. 
Published: July 2010

AbstractThe conventional rapid combustion technique used for microanalysis of organic compounds has been modified for the simultaneous evaluation of combustion and selective oxidation catalysts. Using this technique, MnO2 has been confirmed to be a good combustion catalyst. It was also possible to conclude that Fe2O3 and V2O5 are good selective oxidation catalysts at 250°C and 300°C, respectively. This simple and rapid method offers much scope for probing into the mechanism of oxidation of hydrocarbons.
Saccharification of modified starch to maltose in a continuous rotating annular chromatograph (CRAC)
Authors: Sarmidi M. R. , Barker P. E. 
Published: July 2010

AbstractSimultaneous biochemical reaction and separation has been successfully carried out in a continuous rotating annular chromatograph (CRAC) by saccharifying liquefied starch to maltose using the enzyme maltogenase. Maltogenase is a thermostable, exo‐acting alpha‐amylase. A simple optimisation procedure involving both volume overload and concentration overload was used. For soluble potato starch, maltose conversions of up to 79% were achieved at feed flow rates of up to 400 cm3 h−1 and 15–5% w/v concentrations. The resolution between maltose and dextrin was 0.92.
Effect of acetate medium on the extraction of cobalt(II) with Di(2‐ethylhexyl)phosphoric acid dissolved in kerosene
Authors: Juang Ruey‐Shin , Lo Ru‐Huey 
Published: July 2010

AbstractIn this paper, the effect of acetate ion (OAc−) on the extraction of cobalt(II) from sulfate media with kerosene solutions of di(2‐ethylhexyl)phosphoric acid (D2EHPA, HR) was investigated at 25°C. In the absence of acetate ions, the composition of the extracted species was graphically determined to be CoR2(HR)2 at low loading of D2EHPA (α < 0.06). In the presence of acetate medium, the acetate ions were co‐extracted and the mixed complexes of the type Co2OAcqR4‐p(HR), were formed at a relatively higher loading of D2EHPA (0.10 < α < 0.34), where q = 0–4 and r = 2–4 depending on the concentration of acetate ions.
Synthesis and structural assignment of certain pyrimido[1,2‐a]benzimidazole derivatives
Authors: Ahmed Samia G. , Ahmed Abd‐El Hamid N. , Omar Nabil M. , El‐Gendy Mahmoud A. 
Published: July 2010

AbstractThe pyrimido[1,2‐a]benzimidazole derivatives compounds 1–8 were synthesized through cyclocondensation of 2‐aminobenzimidazole with the appropriate benzsubstituted benzoylacetone by fusion at 150–170°C for 5 h. Quaternary salts compounds 9–22 were obtained by quaternization of compounds 1–8 with dimethyl or diethyl sulfate and subsequent isolation as the relatively insoluble perchlorate salts. Assignment and confirmation of the structures of the newly synthesized compounds were based upon elemental microanalyses and other spectral evidence.
Covalent immobilization of aminoacylase to alginate for L‐phenylalanine production
Authors: Lee Pat M. , Lee Kong H. , Siaw Yew S. 
Published: July 2010

AbstractAminoacylase I (EC. 3.5.1.14) was immobilized by covalent crosslinking to alginate molecules with 1‐ethyl‐3‐(3‐dimethyl‐aminopropyl)‐carbodiimide HCl followed by calcium alginate bead formation for the production of L‐phenylalanine from the racemic mixtures of N‐acetyl‐DL‐phenylalanine. Different concentrations of the coupling reagent were tested and the coupling process was optimized. The immobilized and the partially purified aminoacylase were characterized in terms of the activity, operational stability, thermal stability, pH and temperature optima and kinetic constants, Km and Vmax. The activity of the enzyme covalently immobilized in calcium alginate beads was enhanced by about 75% compared to that of free enzyme. The beads showed stable activity under operational conditions, they lost about 40% of their activity after four reaction cycles. The immobilized aminoacylase was more stable over a broader pH range. Thus this simple method provides irreversible immobilization of aminoacylase to give a biocatalyst with good operational stability and enhanced activity.
Anaerobic digestion of alkaline black liquor using an up‐flow anaerobic sludge blanket reactor
Authors: Dangcong Peng , Qiting Jin 
Published: July 2010

AbstractThe anaerobic digestion of alkaline black liquor from a cereal straw pulping mill was studied in batch (serum bottles) and continuous systems (up‐flow anaerobic sludge blanket reactor—UASB). The batch digestion studies confirmed that lignin and related compounds (LRC) in the alkaline black liquor were the main inhibitory substances and could not be decomposed by anaerobic bacteria. At organic loading rates of 5–10 kg COD m−3 day−1, the UASB reactor achieved 50–60% COD removal efficiencies. Gas production was 2–3 dm3 per dm3 of alkaline black liquor. Two different sludge types were examined in the reactor: granular and cluster‐like sludges. Sludge in a cluster, which involved many small granules and flocs, tended to form larger aggregates and possessed good settling ability.
Extraction of gold from aqueous solution by carrier‐mediated process using kryptofix 22 DD
Authors: Uddin Mohammad S. , Hidajat Kus , Woo Fook‐Cheong 
Published: July 2010

AbstractReactive extraction of gold from alkaline aqueous cyanide solution into n‐decanol in the presence of Kryptofix 22 DD as complexing agent was studied using a stirred transfer cell. The study investigated the effects of carrier concentration and temperature on mass transfer rates. A two‐film model was proposed by considering film mass transfer resistances at the aqueous and organic phases. The model predicted adequately the experimental time‐concentration data at different carrier concentrations and temperatures. Experiments have also been carried out to extract gold in an emulsion system using the same carrier and a mixed solvent of kerosene and decanol.
Spectrophotometric study of the complexation equilibria of iron(III) with 3‐hydroxypicolinic acid and determination of iron in pharmaceutical preparations
Authors: Abu‐Bakr Mohamed S. 
Published: July 2010

AbstractThe complexation equilibria of iron(III) with 3‐hydroxypicolinic acid (hypa) have been studied spectrophotometrically in 40% (v/v) ethanol—water medium at 25°C and an ionic strength of 0.1 M NaClO4. The equilibria occurring in solution were established and the basic characteristics of the complexes formed were determined. The spectral study of the reaction solutions containing equimolar concentrations or an excess of one component in the pH range 1.5 to 10.5 gave the evidence for the formation of [FeLH]2+, [FeL]+ and [FeL2]− complex species, depending upon the pH of the medium (LH2 symbolising the molecular form of hypa). The possible complex transitions that occur in solution were demonstrated using graphical and logarithmic analysis of the absorbance—pH graphs. A simple, rapid, sensitive and selective method for spectrophotometric determination of trace levels of iron(III) was proposed based on the formation of Fe(hypa)2 complex at pH 5.5 (λ = 440 nm, ϵ = 1.5 × 104 dm3 mol−1 cm−1). The interference of a large number of foreign ions was investigated. The method has been applied successfully to the analysis of multivitamin and mineral preparations containing iron.
Effects of pH and temperature on the continuous production of amylolytic enzymes by bacillus amyloliquefaciens MIR‐41
Authors: Castro Guillermo R. , Baigorí Mario D. , Méndez Beatriz S. , Siñeriz Faustino 
Published: July 2010

AbstractBacillus amyloliquefaciens MIR‐41 produces three exocellular amylolytic enzymes: α‐amylase, pullulanase and α‐glucosidase. Physicochemical factors such as pH and/or temperature may affect the enzyme yield. Continuous culture at a dilution rate of 0.15 h−1 demonstrated that the maximum production of α‐amylase and α‐glucosidase occurred at 36°C and pH 6.8 and of pullulanase at 44°C and pH 5.6. The results indicated that combinations of temperature and pH might be used for the production of crude extracts of α‐amylase or pullulanase.
Evolution of the active surface of carbons produced from various raw materials by steam pyrolysis/activation
Authors: Gergova K. , Petrov N. , Butuzova L. , Minkova V. , Isaeva L. 
Published: July 2010

AbstractA one step pyrolysis/steam activation was used to produce activated carbons from apricot stones, nuts, coconuts, almond shells and grape seeds, and Bulgarian lignite from Maritza Iztok and Chukurovo deposit. The evolution of the active surface of the carbons produced was investigated. The changes in the structure of activated carbons give evidence for the periodicity of the processes of oxidation and thermal destruction. It was established that the adsorption properties of activated carbons are dependent on the treatment temperature, soak time and the nature of the raw materials.The activated carbons produced from various raw materials have a high concentration of surface functional groups, carboxyl and hydroxyl. Activated carbons with predominantly meso‐ and macropore structures showed high capacity for adsorbing Cu2+ ions from solutions.
Applicability of the simplified model for the correlation of vapour—liquid equilibrium in the CO2NH3H2o system
Authors: Ciric Gordana M. , Paunovic Ratomir N. 
Published: July 2010

AbstractThe applicability of the simple empirical model—previously derived by Paunovic et al.1 for correlating the VLE in the concentrated CO2—NH3—H2O system—to water‐rich mixtures, encountered in waste water treatment, has been tested. The new parameters of the model have been evaluated for concentrations of ammonia and carbon dioxide up to 16 and 7 molal respectively, for temperatures from 360 to 393 K, and total pressures up to 0.7 MPa. The limit of model applicability in terms of the minimal molality ratio of ammonia to carbon dioxide is established, and suggested to be 2.3. In the region of model applicability, the proposed correlations fit the experimental phase equilibrium constants of ammonia and water with average relative errors of 5.7% and 5.1% respectively, and the reaction equilibrium constant with 31% error.
Kinetics of the liquid phase esterification of acrylic acid with butanol catalysed by cation exchange resin
Authors: Darge Olivier , Thyrion Fernand C. 
Published: July 2010

AbstractEsterification of butyl alcohol with acrylic acid catalysed by Amberlyst‐15 cation exchange resin was carried out in a batch reactor in the liquid phase in the temperature range 333 to 364 K and 1 atm. The reaction rate increased with an increase in catalyst concentration and decreased with an increase in water concentration. The rate data were correlated with a kinetic model based on inhibition by water. The apparent activation energy was found to be 59.5 kJ mol−1 for the formation of butyl acrylate.
Combustion profiles of a double‐base nitrocellulose propellant
Authors: Patai S. , Jordan J. 
Published: July 2010

AbstractThe form of combustion profiles of lamellae of a double‐base nitrocellulose propellant (referred to as plasticized nitrocellulose) was investigated. Experiments were performed both in air and in inert gases, using wrappings of different thermal conductivity. An interpretation of the various profiles obtained (inverted V, rectilinear, concave‐parabolic) is proposed. The factor mainly determining the geometry of the combustion profiles is heat transfer from the flame front to the solid lamellae, through the ambient media.
The saponification of α‐monomyristin, α‐monostearin and α‐mono‐olein
Authors: Jellinek H. H. G. , Gordon A. 
Published: July 2010

AbstractThe saponification of α‐monomyristin, α‐monostearin and α‐mono‐olein has been studied in 75% (v/v) aqueous alkaline acetone.The reactions obey a second‐order law. The energies of activation for the three monoglycerides are very similar: α‐monomyristin, 9900; α‐monostearin, 11,100; α‐mono‐olein, 10,800 g.‐cal.The glycerides show the general phenomenon of alcoholysis in aqueous alkaline ethanol solutions.
Itaconic acid. I. Production by aspergillus terreus from unrefined cane sugar
Authors: Van Der Westhuizen G. C. A. , Spruit C. J. P. , Sephton H. H. 
Published: July 2010

AbstractConditions for the formation from sucrose of itaconic acid by a strain of Aspergillus terreus have been examined. The optimum concentrations of certain mineral components of the medium and some other factors have been investigated. It has been shown that unrefined cane sugar contains substances favouring the formation of itaconic acid. This stimulating effect could be duplicated in solutions containing pure sucrose and dextrose, by adding small amounts of molasses or corresponding amounts of molasses ash. These additions gave better yields than those obtained by the corresponding use of corn steep liquor.
The corrosion of a steel surface by condensed films of sulphuric acid
Authors: Flint D. , Kear R. W. 
Published: July 2010

AbstractAn experimental technique is described which has been used to study the corrosion of a steel surface at elevated temperatures by condensed films of sulphuric acid. The results show that (a) the rate of corrosion of the steel increases with increasing sulphuric acid dew‐point, and (b) irrespective of the dew‐point temperature, the rate of corrosion reaches a maximum at a surface temperature of the steel lying between 20° and 45° c. below that of the dew‐point.