bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hindered settling of organic pigment dispersions in hydrocarbon liquids
Authors: McKay Robert B. 
Published: July 2010

AbstractA modified Steinour hindered settling method has been developed for the study of dispersed organic pigment species containing a large proportion of associated immobile liquid. These species are termed flow units with effective volumes and densities different from those of the pigment itself. The effective volume and density are calculated from the final sediment volume fraction after correction (if practicable) by an appropriate packing factor. The mean flow unit diameter (or a size parameter) can then be estimated. The present method has been satisfactorily tested using formalin‐fixed yeast cells as model flow units which can be sized readily by optical microscopy. Data for organic pigment dispersions compare well with their appearance under the optical microscope. Various uses of simplified versions of the present technique in studies of dispersibility and dispersion stability of organic pigments are described and exemplified using mainly copper phthalocyanine pigments in hydrocarbon solvents.
Studies on the electrosynthesis of organic compounds II. Reducibility of some Schiff's bases on lead and copper cathodes
Authors: Osman Abdel Megid , El‐Cheikh Fathallah , Khalill Zarif H. , Khodair Ahmed I. 
Published: July 2010

AbstractThe electrochemical reducibility of some Schiff's bases was studied on copper and lead cathodes. The effects of different substituents and the nature of the cathode material on the reduction efficiency of these compounds were investigated. The products of reduction were found to catalyse the reduction process itself leading to an increase of reducibility (reduction efficiency) with time.
High‐pressure synthesis of ethyl benzoate from chloro‐ and bromobenzene
Authors: Murty K. Ramachandra , Goswami Asesh K. , Palit Sunanda K. 
Published: July 2010

AbstractWhen chlorobenzene was reacted with ethyl alcohol and carbon monoxide under pressure, the conversions of chlorobenzene to ethyl benzoate and benzoic acid under optimum reaction conditions were 31.3% and 30.1% respectively, with nickel naphthenate supported on silica gel (Ni:SiO2 = 50:50) as the best catalyst. When bromobenzene was used instead of chlorobenzene, the best catalyst was found to be nickel iodide supported on silica gel (Ni:SiO2 = 50:50), and the above conversions were 74.7% and 25.1% respectively under optimum reaction conditions.
Selection of strains of Penicillium chrysogenum with reduced penicillin yields in continuous cultures
Authors: Righelato Renton C. 
Published: July 2010

AbstractIn sucrose‐limited chemostat cultures of high‐yielding strains of Penicillium chrysogenum the ability to produce penicillin was progressively lost. Subcultures from the chemostats on to agar showed a progressive increase in the proportion of non‐conidiating colonies, designated the D‐phenotype, which produced low yields of penicillin in shake‐flask tests. When the growth‐limiting substrate was ammonia, phosphate or sulphate, production of penicillin was maintained and the D‐phenotype did not appear. However, when a mutant with the D‐phenotype was inoculated into an ammonia‐limited culture of the parent strain, it quickly displaced the parent. The mutant had a yield constant for ammonia 44% higher than had the parent. The conclusion reached is that growth‐limitation by the carbon source is necessary for the occurrence of the mutation or for the initial stages of selection.
Studies in the lightfastness of nitrodiphenylamine dyes
Authors: Asquith Raymond S. , Blair Hal S. , Hamill Aidan C. 
Published: July 2010

AbstractStudies of the photofading of nitrodiphenylamine dyes have been made in ethanolic solution. It has been shown that the presence of oxygen during photoirradiation of the solution acts as an inhibitor, causing an induction period before degradation commences. The results suggest that the intermediate in the degradation is a triplet state, and this is quenched by oxygen. The “deactivated” oxygen molecules, so formed, can be reactivated by collision with “normal” oxygen molecules. The enhancement of photodegradation in the presence of hydrogen donors suggests that the degradation mechanism is reductive in nature. The influence of the positions of the nitro‐groups in the diphenylamine derivatives supports the postulate that the reaction proceeds via quinonoid forms. The absence of brown degradation products suggests that the mechanism of degradation is not the same as that occurring on solid substrates, although the order of dye stability is the same in both cases.
Kinetics of the reaction of hafnium tetrachloride vapour with solid sodium chloride
Authors: Majumdar Sibnath , Ray Hemshanker S. , Kapur Prakash C. 
Published: July 2010

AbstractThe kinetics of the reaction of hafnium tetrachloride vapour with solid sodium chloride spheres to form sodium hexachlorohafnate have been studied as a function of pressure, temperature and sphere size. The course of the reaction was followed by weight gain measurements in an all‐glass closed system using a quartz spring. Various kinetic models for gas‐solid reactions were tested against the experimental data. Only the Carter‐Valensi kinetic model gave a consistently good fit. Possible reaction mechanisms are discussed in the light of the pressure and temperature dependence of the specific rate constant in the Carter‐Valensi model and in the inert marker experiments.
Hydrolysis of pentosans in bagasse pith
Authors: Nee Charles I. , Yee Wen F. 
Published: July 2010

AbstractWork has been conducted on the hydrolysis of pentosans in bagasse pith as the first part of a study of the chemistry of bagasse processing aimed at establishing an integrated industry. Bagasse pith is the fine part screened out and discarded as waste during the preparation of raw material for bagasse pulping plant. By using dilute sulphuric acid at a concentration less than 2% by weight and at a temperature lower than 165°C, pith is hydrolysed to pentoses in a yield of 80–90% based on potential pentoses in pith. Hydrolysis of pentosans in pith, within the scope of experiment, seems to be a first order reaction. However, the semi‐logarithmic time plot for the hydrolysis of potential pentoses in the residue consists of two straight lines of different slope. This may be explained on the assumption that bagasse pith contains two major fractions of pentosans that are hydrolysed at different rates. Saeman's equation for hydrolysis of wood with sulphuric acid may be adapted to represent dependence of rate constant K on acid concentration C and reaction temperature T in hydrolysis of the two major parts of pentosans in bagasse pith.K1 = 6.4 × 105C1.02 exp (−6378/T)K2 = 10.7C0.363 exp (‐ 2826/T)
An investigation into the factors governing the aqueous solubility of xanthine (purine‐2,6‐dione)
Authors: Lister John H. , Caldbick David S. 
Published: July 2010

AbstractThe solubility of xanthine in cold aqueous solutions has been reinvestigated in view of conflicting values given in the literature. A significant factor, not appreciated by earlier workers was that, unlike related oxopurines, only a small difference exists between the first acidic pKa of this purine and neutral pH. Thus, in view of the highly insoluble nature of the neutral molecule, compared with the very soluble anionic form, the solubility in this region is highly pH dependent. Other factors found which may have a bearing on solubility results are supersaturation effects and the formation of colloidal solutions. Some possible consequences of the solubility phenomena in pathological conditions in which xanthine metabolism is concerned are discussed.
Evaluation of bleaching capacity of acid‐leached egyptian bentonites
Authors: Kolta George A. , Novak Ivan , El‐Tawil Samir Z. , El‐Barawy Kamilia A. 
Published: July 2010

AbstractThe acid activation of Egyptian bentonites was tested by their bleaching capacity for cottonseed oil and was compared with that of a standard bleaching compound Tonsil AC. The bleaching ability of two samples representing two Egyptian deposits was relatively high, while the third sample could not be used for bleaching purposes. There is parallelism between the bleaching ability and the surface area of acid activated bentonites. Bleaching ability is greatly dependent on the montmorillonite content in the bentonite sample and on the method of acid activation.
Effect of carbon deposition on the activity of steam reforming catalysts
Authors: Moayeri Massoud , Trimm David L. 
Published: July 2010

AbstractThe activity of supported nickel used to catalyse the steam reforming of propylene has been found to be both increased and decreased by carbonisation of the catalyst. Increased activity is observed at temperatures between ca 650 and 375°C, and is suggested to result from the mechanism of carbonisation, which causes increased metal area and increased activity. At high temperatures (> ∼ 650°C) and at low temperatures (< ∼ 375°C), where a different mechanism of carbonisation results in encapsulation of metal, carbon formation poisons the catalyst. The kinetics of reaction have been measured over a catalyst which has attained steady‐state: they indicate that the overall kinetics are influenced by carbon deposition on the catalyst.
Purification of mitomycins produced by Streptomyces caespitosus
Authors: Abou‐Zeid Abou‐Zeid A. , Yousef Abd‐El‐Sadek A. 
Published: July 2010

AbstractMitomycins were fermentatively produced using certain agricultural raw by‐products by Streptomyces caespitosus NRRL 2564. The excreted antibiotics were thoroughly extracted with ethyl acetate at pH 6.0–8.0. The ethyl acetate extract was extensively purified by paper and thin‐layer chromatographic techniques. The most efficient solvent systems in the complete separation of mitomycins were water‐benzene‐methanol (2:1:1 by vol.) in the case of paper chromatography, while acetone‐ligroin‐n‐octanol (5:5:2 by vol.) was suitable for silical gel and alumina thin‐layer plates. Pure samples of mitomycins A, B and C were obtained by preparative thin‐layer chromatography using the solvent system composed of acetone‐ligroin‐n‐octanol (5:5:2 by vol.). The active principles of mitomycins A, B and C, when biologically assayed on Bacillus subtilis ATCC 6622, were 980, 955 and 1000 μg/mg respectively. Mitomycin A can be converted into mitomycin C by exposing thin‐layer chromatograms to concentrated ammonia vapour for 20 min.
Equilibrium between carbon dioxide and aqueous monoethanolamine solutions
Authors: Lee Jong I. , Otto Frederick D. , Mather Alan E. 
Published: July 2010

AbstractThe partial pressure of carbon dioxide has been measured over aqueous monoethanolamine solutions (1.0, 2.5, 3.75 and 5.0 N) at temperatures of 25, 40, 60, 80, 100 and 120°C. Partial pressures of CO2 ranged between 0.2 and 6616 kPa.b The results extend previously published data to higher partial pressures. Comparisons have been made with two methods of prediction based upon a thermodynamic model.
A rapid sensitive colorimetric method for the determination of ascorbic acid
Authors: Hammam Ahmed Sabet 
Published: July 2010

AbstractA new colorimetric procedure based on the interaction of ascorbic acid with 4,4′‐dimethoxydiquinone (I) in an aqueous dioxane solution was developed. In this procedure the diquinone reagent (I) is reduced to a blue‐violet product (II)1 which absorbs maximally at 490–500 nm. The colour development takes place within 6 min at 25°C and absorbance vs concentration was linear up to a sample size of 600 μg. Reducing substances likely to be present in biological fluids or in natural extracts of the vitamin do not interfere with colour development and average recoveries of 99.8 ± 0.4% were obtained for solutions containing these substances.
Heterocyclic quinones. VIII. Synthesis and spectra of new carbazoloquinone derivatives of naturally occurring amino acids
Authors: Hammam Ahmed Sabet 
Published: July 2010

AbstractFifteen naturally occurring amino acids representing basic, neutral and acidic members were interacted with 4,4′‐dimethoxydiquinone (I). Basic amino acids reacted readily to give amino acid substituted carbazoloquinones (III), while neutral and acidic amino acids reacted only after addition of an acid binding agent. Using an excess of any of the amino acids resulted in the substitution of the quinonoid methoxyl group in compounds (III) by an amino acid moiety. In the case of basic amino acids, this substitution reaction was preferentially influenced by a terminal amino or guanidino amino rather than by an α‐amino group. Moreover, basic amino acids could be reacted with two moles of (I) to produce dicarbazoloquinones (X). The i.r. and u.v.‐visible spectra of the various carbazoloquinone products were determined and discussed.
Extraction of some mineral acids by tri‐n‐octyl phosphine oxide
Authors: Sato Taichi , Watanabe Hiroshi , Yamatake Masahiro 
Published: July 2010

AbstractThe distribution equilibria of hydrochloric, nitric, perchloric, sulphuric and phosphoric acids between aqueous solutions and a solution of tri‐n‐octyl phosphine oxide (TOPO) in organic solvents have been investigated. The organic phases were studied by infrared and nuclear magnetic resonance spectroscopy. As a result, it is found that the extraction of these acids is governed by the formation of HCl·TOPO, HNO3·TOPO and HClO4·TOPO, of H2SO4·2 TOPO and H2SO4·TOPO, and of H3PO4·3 TOPO, H3PO4·2 TOPO and H3PO4·TOPO, respectively.
Radiometric investigation of the desulphurisation of barite‐containing iron oxides
Authors: Fakhoury S. S. , Shehata K. A. , Estefan S. F. , Hussein M. K. 
Published: July 2010

AbstractDesulphurisation of chemically pure iron oxide briquettes well mixed with Ba35SO4, was followed radiometrically during firing or reduction within the temperature range 800–1200°C. Effective desulphurisation was observed during firing rather than reduction. The extent of dissociation of BaSO4 depends mainly on temperature and reaches about 99% at 1200°C. The results obtained were confirmed by studies on crushed ore and ore pellets. Fluxing of ore pellets with CaO retarded desulphurisation whereas the presence of small proportions of water vapour in the reducing gas enhanced sulphur removal.
Heterocyclic compounds. X. Synthesis of some oxazoloquinoline derivatives
Authors: Osman Abdel M. , Khalil Zarif H. , Yanni Amal S. 
Published: July 2010

AbstractA series of 2‐aryl‐oxazolo[4,5‐h]quinoline‐5‐arylidines (II) was prepared through the reaction of 5,7‐diamino‐8‐hydroxy quinoline with aromatic aldehydes in the presence of a basic catalyst such as piperidine. The reaction also proceeded with aliphatic aldehydes but under slightly different conditions. On the other hand, 2‐stilbyl‐5‐diacetyl‐amino‐oxazolo[4,5‐h]quinolines (V) were prepared by interaction of 2‐methyl‐5‐diacetylamino‐oxazolo[4,5‐h]quinoline (IV) with aromatic aldehydes. Such compounds possessed structural relationships to some known antibiotics and their chemical constitution was confirmed by spectral studies.
Thermal decomposition, pore structure and heats of immersion of zirconia gel
Authors: Selim Suzy A. , El‐Akkad Taghreed M. 
Published: July 2010

AbstractThe surface properties of zirconia gel and its thermal dehydration products obtained in the temperature range 300–1000°C were investigated by N2 and C6H12 adsorption. Structural and phase changes were studied by X‐ray diffractometry and differential thermal analysis. Samples obtained up to 500°C were amorphous to X‐rays whereas those obtained at higher temperatures proved to be a mixture of tetragonal and monoclinic modifications. The glow phenomenon is attributed to the conversion of the amorphous oxy‐hydroxide of zirconium to the amorphous zirconium dioxide. Complete pore structure analysis showed the original parent material to be microporous. The pores widen with increase of temperature but at 500°C some narrowing occurs when the structure is changed to the oxide. Heats of immersion in cyclohexane were measured at 35°C. A correlation between the micropore fraction and the heats of immersion, normalised per unit area, could be traced for all samples.
Techniques for the experimental determination of liquid permeation data, with particular reference to the n‐hexane/polythene system
Authors: Peeters Hugo I. , Verhoeye Lucien A. 
Published: July 2010

AbstractPermeation rates of n‐hexane through polythene membranes have been determined as a function of temperature and pressure. The influence of membrane annealing and of the particular experimental technique adopted was studied. Concentration differences and diffusion coefficients were estimated from measurements of the time lag before a steady permeation rate could be achieved. It was shown that both random and systematic errors were so large that exact estimates of the diffusion coefficient were not possible. It was therefore necessary to use desorption data in conjunction with measurements of the permeation rate to arrive at values for the diffusion coefficient.
Catalytic dehydrogenation of propane on chromia, palladium and platinum supported catalysts
Authors: Ashmawy Fathy M. 
Published: July 2010

AbstractThe dehydrogenation of propane to propylene over Cr2O3/Al2O3, Pd/Al2O3 and Pt/SiO2 has been investigated in the temperature range 580–618°C. Runs were performed on propane, alone or in the presence of nitrogen (as a diluent), with complete analysis of the reaction products. The reaction was carried out in a fixed bed reactor at space velocities from 450–800 h−1 which are close to industrial values and at pressures from 0.3 to 1 atm. A set of runs was made over a commercial chromia‐alumina catalyst (10% Cr2O3) and over a promoted catalyst prepared in the laboratory by impregnation (16.8% Cr2O3 + 2% K2O). The latter catalyst showed high selectivity and stability even when subjected to continuous cycles of dehydrogenation, regeneration and purging. Of the two noble metal supported catalysts used, reduced Pd/Al2O3 showed higher activity than Pt/SiO2 at 618°C. The former catalyst gave a propylene yield of around 98% at 20% conversion level.
Solid‐phase acylating agents. I. The preparation and reactions of acetylpolystyrenesulphonates in aqueous solution
Authors: Laird Robert M. , Spence Michael J. 
Published: July 2010

AbstractMethods of preparing acetylsulphonate acylating reagents from commercial sulphonic acid ion‐exchange resins and their reaction with aqueous aniline solutions are described. The relative merits and limitations of the techniques employed are discussed.
Metachromic interactions between azo and triphenylmethane dyes in aqueous solution. II. The effect of organic solvents on the interaction
Authors: Owen Eryl D. , Al‐Akil Tarek N. 
Published: July 2010

AbstractThe interaction between dilute aqueous solutions of the disazo dye Brilliant Orange and the triphenylmethane dye Crystal Violet results in a decrease in the absorption of Crystal Violet in the region 550–600 nm and the appearance of a new absorption at 494 nm. The decrease in absorbance at 590 nm is characteristic of the metachromic interactions of Crystal Violet with a wide variety of polyanion substrates while the increase at 494 nm is due to the conversion of Brilliant Orange from its azo to its hydrazone tautomer. The relative effects of a variety of organic solvents in reversing the interaction has been investigated.
Continuous dissolution of sodium and potassium silicate glass in a tower dissolver
Authors: Jorgensen Frank R. 
Published: July 2010

AbstractSodium and potassium silicate glass was continuously dissolved in a tower dissolver operated at atmospheric pressure. In pilot experiments the rate, controlled by the dissolution process occurring at the glass/liquor interface, was dependent on surface area, temperature, type, and chemical composition of the glass, but was independent of concentration and flowrate. Activation energies for the dissolution process lay in the range 22‐48 kJ/mol, while typical rates of dissolution were 26 and 21 kg m−3 h−1 for 2.0 and 3.2 SiO2/Na2O weight ratio sodium silicate glass at 99°C. The corresponding rate for potassium silicate glass of SiO2/K2O weight ratio 2.0was 195 kgm−3h−1 at 80°C. Loss of potassium silicate due to the formation of insoluble compounds was prevented by operating below 93°C. Tower dissolvers warrant further consideration as an alternative to conventional digestors, having the advantages of continuous operation and uniform product density.
A phase model for the gas–liquid equilibria in the ammonia–carbon dioxide–water–urea system in chemical equilibrium at urea synthesis conditions. I. Theory
Authors: Lemkowitz Saul M. , Diepen George A. M. , van den Berg Pieter J. 
Published: July 2010

AbstractA ternary phase model of the reciprocal salt‐pair type (square composition plane) is presented to describe the gas–liquid equilibria of the ammonia–carbon dioxide–water–urea system in chemical equilibrium at urea synthesis conditions. The components of the model are CO2, H2O and (2NH3). Urea is represented by the equation:.magnified image and is therefore located at the corner of the composition square diagonally opposed to water. Characteristic of this phase model (at constant temperature) is the occurrence of minimum bubble‐ and dew‐points in planes located parallel to the (2NH3)‐CO2 diagonal. The point of tangency of the bubble‐ and dew‐point lines formed by these points forms the ternary azeotropic point. Intercepting the azeotropic point is a plane parallel to the urea–water diagonal; at the azeotropic point the bubble‐point line in this plane reaches a maximum pressure value. The ternary azeotrope is of the saddle type.
Preparation of mono(dimethylglyoxime)(triphenylphosphine)‐halogenocobalt(I) complexes and their application as homogeneous catalysts in reduction of aromatic nitrocompounds
Authors: Datta Manik C. , Saha Chitta R. , Sen Debabrata 
Published: July 2010

AbstractThe complexes [Co(I)(DMGH)(PPh3)X].C2H5OH (XCl/Br) have been prepared and characterised by elemental analysis, infrared and electronic spectral studies and magnetic measurements. These compounds have been used as homogeneous catalysts for the reduction of nitrobenzene at atmospheric and higher pressures. From a study of various operational parameters, it has been observed that the reduction at atmospheric pressure was only possible in a basic ethanolic medium and resulted in 64% of azobenzene on input nitrobenzene basis whereas at higher pressure (4.2 × 103 kN/m2), 60% of aniline on the same basis could be obtained in neutral ethanolic medium. The optimum conditions were established both under normal pressure and under high pressure.
The solvation of cellulose by the action of nitrogen tetroxide in organic solvents
Authors: Abou‐State M. Amine , Awad Boshra M. 
Published: July 2010

AbstractThis article reviews the solvation of cellulose by the action of N2O4 in presence of a suitable proton acceptor and its subsequent regeneration. The mechanism of the nitrosation reaction and the factors affecting cellulose degradation during solvation and regeneration are discussed. The possible industrial applications of this process as well as the use of cellulose nitrite in the preparation of novel cellulose derivatives are also included.
Oxidation of ferrous hydroxide suspension. III
Authors: Prasad Turaga P. , Ramasastry Vemuri V. 
Published: July 2010

AbstractThe rate equation developed in our earlier studies has been analysed and discussed. It has been found that the rate of oxidation of ferrous hydroxide suspensions obtained by the addition of calcium hydroxide, sodium and calcium carbonates, ammonium and sodium hydroxides follows zero order kinetics.