bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of oxidation of butadiene to crotonaldehyde
Authors: Hotanahalli S. S. , Chandalia S. B. 
Published: July 2010

AbstractThe oxidation of butadiene to crotonaldehyde has been investigated using an aqueous catalyst solution containing palladium chloride–cupric chloride in dilute hydrochloric acid. Unlike the oxidation of ethylene, propylene, etc., this oxidation was found to be a zero‐order reaction with respect to butadiene. The effects of temperature and the concentration of Pd2+, Cu2+, Cl− and H+ ions on the reaction rate were studied. The order of reaction with respect to Cl− and H+ ions in this case (approximately 1.5 and −0.25, respectively) is different from that observed in the case of lower alkenes.
Hydration of dibarium silicate I. Stoicheiometry of hydration
Authors: Hanna K. M. , Cook R. L. , Kantro D. L. 
Published: July 2010

AbstractDibarium silicate, Ba2SiO4, was hydrated in two ways: in paste form at 25° using a water/solid weight ratio of 0.7:1, and in a polyethylene bottle rotated on a wheel at 5°, 25° and 50°, using a water/solid weight ratio of 9.0:1. When Ba2SiO4 is hydrated in paste form, the stoicheiometry of the reaction at 25° is the same as in bottle‐hydration at 50°: 2BaO.SiO2+2.2H2O = 1.2BaO.SiO2.1.4H2O+0.8Ba(OH)2. The stoicheiometry of bottle‐hydration at 5° and 25° is represented by the equation: 2BaO.SiO2+2.2H2O = BaO.SiO.1.2H2O+Ba(OH)2. Barium silicate hydrate, 1.2BaO.SiO2.1.4H2O, is well crystallised and has a specific surface area of ˜ 3m2/g. The crystals are plate‐like and have a tendency to form clusters. The low‐baria hydrate, BaO.SiO2.1.2H2O, is poorly crystallised and consists of thin platelets. It has a specific surface area of ˜ 35m2/g. The thermal dehydration of fully hydrated barium silicate and of the barium silicate hydrates was investigated by thermogravimetric and differential thermal analysis techniques.The similarities and differences between the barium silicate hydrates obtained in the hydration of barium silicate and the calcium silicate hydrates obtained in the hydration of β‐dicalcium silicate and Ca3SiO5 are discussed. A mechanism of hydration of barium silicate is proposed which involves solution, precipitation and crystallisation steps.
Hydration of dibarium silicate II. rate of hydration
Authors: Hanna K. M. , Cook R. L. , Kantro D. L. 
Published: July 2010

AbstractThe rate of hydration of dibarium silicate (Ba2SiO4) in paste form at room temperature was investigated. The uncombined barium hydroxide produced in the reaction, determined by a modified Franke method, was used as a measure of the extent of hydration. The linear relationship obtained between the uncombined barium hydroxide and the chemically combined water confirms that similar hydration products are formed at all stages of hydration, and either may be used as a measure of the degree of hydration. The rate of hydration of dibarium silicate was found to be lower than that of tricalcium aluminate, but higher than those of alite, tricalcium silicate and β‐dicalcium silicate. The effect of water/solid ratio on the rate of hydration was also investigated. Dibarium silicate was completely hydrated after 30 days when it was mixed with a water/solid weight ratio > 0.7:1.
Optical studies of surface impurities on titanium dioxide
Authors: Clark W. C. , Broadhead P. 
Published: July 2010

AbstractTitanium dioxide powders, prepared by the hydrolysis of titanyl sulphate, discolour in a vacuum. The discoloration is stable in dry oxygen or dry air, but it bleaches in the presence of water vapour. Infra‐red and thermogravimetric measurements show that the discoloration and bleaching cycle is associated with the state of adsorption of hydrogen‐bonded water by sulphate impurities on the titanium surface.
Solubility of carbon in sodium
Authors: Longson B. , Thorley A. W. 
Published: July 2010

AbstractThe solubility of carbon in sodium over the range 600‐950° may be expressed by the equation: log sol. = 7.20‐5465/T where solubility is in ppm and T in °K.From plots of carbon activity versus concentration, and from observations that oxygen does not affect carbon solubility, it is proposed that carbon dissolves in sodium as single atoms.
Supply and demand for road aggregates
Authors: Please A. , Pike D. C. 
Published: July 2010

AbstractEstimates have been made of the production and use of the various materials used as road aggregates for 1966–67, and the regional distribution was also calculated. Future demand for road aggregates is considered, and it is estimated that the total demand by 1977 will be ∼ 85 × 106 tonnes per annum, the overall growth rate until then being ∼ 6% compound per annum.
Kinetics of dissolution of copper(II) sulphide in aqueous sulphuric acid solutions
Authors: Biswas A. K. , Mohan N. P. 
Published: July 2010

AbstractThe rate of dissolution of synthetic cupric sulphide (CuS) which is the analogue of the naturally occurring sulphide mineral covellite, in sulphuric acid solutions of concentration range 5 × 10−3 to 3 mole/l over the temperature range 20–65°c at atmospheric pressure was studied.Thermodynamic considerations suggested that the primary reaction taking place during the leaching is: CuS+1/2O2 + H2SO4 → CuSO4 + S+H2O.It is proposed that up to an initial sulphuric acid concentration of 1 mole/l, the reaction rate is controlled by the diffusion of H+ ions through the sulphur film to the CuS/S interface. For higher sulphuric acid concentrations the oxygen dissolved in the acid decreases and the rate‐determining step is believed to be diffusion of dissolved oxygen through the sulphur film to the CuS/S interface. A parabolic model is suggested for the dissolution reaction, and this model is supported by the experimental data.The activation energy for the dissolution reaction was found to be 8000±2000 cal/mole and this was independent of the H+ concentration and hence the nature of the diffusing species.
Barium aluminate hydrates III. BaO.Al2O3.2H2o and BaO.Al2O3.0.5H2O
Authors: Ahmed A. H. M. , Dent Glasser L. S. 
Published: July 2010

AbstractTwo compounds of formula BaO.Al2O3.2H2O have been synthesised and studied by infra‐red, X‐ray and thermal analytical techniques. One form yielded another crystalline product, BaO.Al2O3.0.5H2O, as an intermediate during dehydration. The results are interpreted in terms of the known crystal structure of one of the forms of the dihydrate.
Drying of sodium silicate solutions
Authors: Dent Glasser L. S. , Lee C. K. 
Published: July 2010

AbstractSodium silicate solutions with a silicon dioxide:sodium monoxide mole ratio of 3.41:1 were dried gently to give amorphous solids. These solids, together with the products obtained by heating them at various temperatures up to ∼ 200°c, were studied by differential thermal analysis, solubility tests and other techniques. The resultant data give some insight into the structural changes which occur in the solid during the drying process.
Characterisation of waxes by differential scanning calorimetry
Authors: Flaherty B. 
Published: July 2010

AbstractThe characterisation of hydrocarbon and natural waxes by differential scanning calorimetry is described. It is shown that the determination of the melting, cooling and remelting curves of a wax, and comparison with the corresponding curves of authenticated waxes, affords a rapid and valuable method for the identification of many waxes. Heats of transition of many waxes are also given.
Adsorption of sulphite, oleate and manganese(II) ions by β‐manganese dioxide and its activation in flotation
Authors: Yousef A. A. , Arafa M. A. , Malati M. A. 
Published: July 2010

AbstractA high‐grade ore sample A and a synthetic sample B of β‐MnO2 were characterised by a number of physical methods. The points of zero zeta potential were found at pH4.4 and 4.6 for A and B, respectively. Below the critical micellar concentration and at pH 7, the adsorption isotherms of oleate on to sample B followed the Freundlich equation, the adsorption density decreasing with rising temperature. Over a wider concentration range, the isotherm had a Langmuir shape and was displaced to higher adsorption densities in presence of NaCl. The adsorption density was slightly affected by pH, but it gradually decreased beyond pH 9. From a comparison of the adsorption and ζ potential results, the adsorption mechanism could not be electrostatic only but may also involve van der Waals and π interactions.The adsorption isotherm of sulphite ions exhibited a broad maximum and was shifted to lower adsorption densities in presence of oleate. The amount of Mn2+ ions released on conditioning sample A in sulphite solutions increased with increasing sulphite concentration. It could be assumed that sulphite ions were adsorbed prior to reaction with MnO2 producing Mn2+ ions, which were the activating species in flotation. Although there was an adsorption competition between sulphite and oleate ions, the adsorption of the latter was enhanced in presence of sulphites.The adsorption density of Mn2+ ions on to sample B increased linearly with increase in their equilibrium concentration. Assuming the low‐coverage form of the Langmuir isotherm, the heat of adsorption was found to be 51.9 kJ/mole.The adsorption density of Mn2+ ions increased with increasing the pH of the medium from 5 to 6.5, in agreement with the more negative surface charge on the MnO2 particles. Above a certain Mn2+ concentration, the charge was reversed. The adsorption of Mn2+ ions is interpreted in terms of an Na+/Mn2+ exchange mechanism. Tentatively, the cations are assumed to be in the outer Helmholtz layer of the electric double layer of MnO2.The activating effect of Mn2+ cations was demonstrated by the increased adsorption density of oleate in presence of Mn2+ ions and by the corresponding increase in flotation recovery. Oleate adsorption was exothermic, i.e. similar to its adsorption in absence of activating cations. It is assumed that activation involves electrostatic attraction between the activating Mn2+ and the oleate ions.
Reversible phase transformation in the system calcium oxide‐chromium sesquioxide‐oxygen
Authors: El‐Rafei E. A. 
Published: July 2010

AbstractFurther studies were carried out on the reversible phase transformation of the low melting (1228°c) calcium chromate chromite (941) into the high melting (2170°c) monocalcium chromite (CK) with the liberation of free CaO and oxygen.The investigation of specimens of synthesised 941, calcium chomate (CK1), and 941‐bearing samples with a high content of periclase (as in dolomitic magnesite chrome refractories) cooled from different temperatures showed the presence of transformation products of 941 phase under different conditions of its formation, and thermogravimetric analysis and complex differential thermal analysis confirmed the reversible nature of this phase transformation.Irrespective to the method of formation of 941 or the existence of a high periclase content and a solid solution of 2CaO.SiO2 with it, 941, at its melting point, starts to undergo a reversible phase transformation according to the equation: 9CaO.4CrO3.Cr2O3.3CaO.Cr2O3+6CaO+3 O2.The presence of 941 phase in basic refractories produced from raw materials with a high CaO content, should be considered to be a secondary phase, re‐formed during the cooling process.Beta‐alpha polymorphism of the liberated CK was exhibited above 1600°c during this phase transformation.
Apparatus for sampling of liquid oxygen, nitrogen and argon in the plant
Authors: Malan E. , Van Merwe P. Der 
Published: July 2010

AbstractA simple sampling system was developed to enable the sampling of liquid oxygen, nitrogen and argon in the plant, which can then be analysed at any remote laboratory. The procedure is described for the operation of the high pressure system to avoid contamination by air. Analyses have shown that repetitive sampling of the same product tank gave repeatable results.
The shapes and applications of enthalpic curves
Authors: Davidson Fay C. , Sloan John P. , Williams David R. 
Published: July 2010

AbstractA computer programme, RWCRVE, is reported that plots both the formation and enthalpic curves from ΔH° and ΔS° of complexing. RWCRVE (i) permits a detailed analysis of the factors dictating the shapes of enthalpic curves, and (ii) suggests new conclusions that may be drawn from experimental enthalpic curves; such conclusions concern symbiosis effects of a complexed ligand upon the next ligand‐metal bond being formed, ion‐pair effects and extrapolations of these discussions to industrial and biological systems where all the details of complexing may not be clearly established.
On the thermochemistry of gypsum
Authors: Khalil A. A. , Hussein A. T. , Gad G. M. 
Published: July 2010

AbstractHeating gypsum below 100°c gives rise to limiting values of weight loss around that of the hemihydrate formation whatever is the time of heating. Calcination at 100°c and above, on the other hand, causes a continuous loss in weight as the time is prolonged, leading to γ‐anhydrite when adequate time is given. In most of the examined samples a resistant state, with trace amounts of residual water, is reached towards the end of the dehydration process. Such residual water is driven off completely below the transformation temperature of γ‐ to β‐CaSO4.
Production of cyclodextrin glycosyltransferase by Bacillus macerans in batch cultures
Authors: Lane A. G. , Pirt S. J. 
Published: July 2010

AbstractSatisfactory growth of Bacillus macerans and high activities of cyclodextrin glycosyltransferase (CGT) were obtained in media containing potato extract. The appearance of CGT in culture supernatant fluids during the stationary phase of growth was not due to autolysis, since intracellular levels of the enzyme were very low throughout the cultivation. When cell growth was limited by the starch concentration in the medium, CGT activity remained low during the logarithmic phase of growth but high activities appeared suddenly in the supernatant fluid when growth ceased. Negligible activities were produced by cultures growing in a nitrogen‐deficient medium in which starch was present in excess. CGT therefore appears to be a true extracellular enzyme, produced in response to exhaustion of the starch from the medium. A simple fractionaltion procedure was developed for concentrating the CGT from culture supernatant fluids. This enzyme preparation was used to convert 20% (w/v) starch solutions to cyclodextrins in 24 h and the cyclodextrins recovered were equivalent to 55% of the original starch.
Isolation of glucose oxidase with the use of DEAE‐cellulose
Authors: Kučera J. , Hanus J. 
Published: July 2010

AbstractA method is described for the isolation of glucose oxidase from the bacteria Aspergillus niger using sorption on DEAE‐cellulose. The method is rapid by comparison with precipitation methods and results in a preparation having a specific activity of 87‐5 e.u./mg. The preparation contains no detectable catalase or amylase activity and appears to be suitable for most purposes without further treatment.
Reactions of cyclohexane in a microwave discharge reactor
Authors: Brooks B. W. , Sambrook R. M. 
Published: July 2010

AbstractA study has been made of the reactions of cyclohexane in a continuous‐flow microwave discharge reactor. Butene‐1 and propylene were the major reaction products; ethylene and hydrogen were produced in smaller amounts. The distribution of reaction products was found to depend on the reactor pressure and flow‐rate. The results show that the fragmentation of cyclohexane is not the sole source of butene‐1.The insertion of nickel wire into the reactor enhanced the production of ethylene and propylene; yields of butene‐1 were diminished. In the presence of nickel the production of ethylene and propylene became independent of pressure. When carbon dioxide was added to the cyclohexane feed the major reaction product was acetylene. The carbon dioxide did not react chemically. The yields of acetylene per unit energy input were found to be fairly high.
The catalytic activity and electronic property of cupric oxide semiconductor
Authors: Bhattacharya D. P. , Mukherjee P. N. 
Published: July 2010

AbstractThe correlation between catalytic and electronic properties has been experimentally verified for cupric oxide semiconductor. The catalytic activity of cupric oxide for CO oxidation was measured in terms of energy of activation for CO chemisorption whereas the electronic property was measured in terms of the electrical conductivity. The semiconducting properties of cupric oxide were varied by doping with different proportions of altervalent ions such as lithium and gallium.
The acid‐catalysed condensation of xylene and styrene
Authors: Malan E. 
Published: July 2010

AbstractDuring the plant process of acid‐refining of crude xylene with concentrated sulphuric acid, a considerable amount of residue remains after fractionation. The main constituents of this residue were identified as α‐phenyl‐α(dimethy1‐pheny1)ethanes. Mass spectrometry, n.m.r., infra‐red, gas chromatography and synthesis were used for structure elucidation.
Reconsideration of a theory of the setting of gypsum plaster
Authors: Ridge M. J. , King G. A. , Molony B. 
Published: July 2010

AbstractThe rates of hydration of eight samples of calcium sulphate hemihydrate, six of which were commercial calcined gypsum, were determined from the accompanying increases in temperature. The compositions of the samples and the areas of their surfaces were determined, and the sizes of the microcrystals in the hydrated and hardened systems were studied. The results strongly support the applicability of a theory of hydration of calcium sulphate hemihydrate developed earlier.The possibilities of calculating periods of induction are described, and some of the implications of the theory discussed.
The catalytic dealkylation of alkyl phenols at elevated pressures
Authors: Milnes M. H. , Dean R. E. 
Published: July 2010

AbstractThe most successful catalysts previously used in atmospheric pressure experiments were screened for their suitability for hydrodealkylation of o‐cresol at elevated pressures. Active charcoal was easily the best, while coke functioned well at higher temperatures, with soda‐lime and zinc fluoride on alumina notably less successful; the last named gave rise to a high yield of non‐phenolic compounds.Active charcoals from various sources were compared under standard conditions in the hydrodealkylation of o‐cresol at 50 atm, and the best two grades were used successfully to dealkylate high boiling acids tar acids derived from low temperature carbonisation of coal.These gave high yields of dealkylated phenols, and unchanged feed stock was recycled such that in two passes 90% of the feed reacted to give over 25 % phenol and cresols. The catalytic activity of the charcoals waned slowly and irreversibly under reaction conditions, and attempts to combat this by alteration of reaction variables and use of impregnating agents only effected marginal improvements.
Influence of triethanolamine on the hydration characteristics of tricalcium silicate
Authors: Ramachandran V. S. 
Published: July 2010

AbstractThe hydration characteristics of 3CaO.SiO2 or β2CaO.SiO2 are studied by an addition of 0.0, 0.1, 0.5 or 1.0% triethanolamine. The amount of Ca(OH)2 found at 1, 3, 7 or 28 days was in the order C3S + 0% TEA > C3S +0.1% TEA > C3S + 0.5% TEA > C3S+1.0% TEA, irrespective of whether lime was estimated by X‐ray, DTA, TGA or chemical analysis. The rate of hydration, in terms of the disappearance of 3CaO.SiO2, showed that hydration proceeded faster in the presence of TEA after 1 day. Additions of TEA increase the induction period, promote the formation of a C‐S‐H with higher CaO/SiO2 ratio, increase the formation of non‐crystalline Ca(OH)2 and enhance the surface area of the hydrated silicate product.
The metabolism of penicillium chrysogenum and the production of penicillin using a high yielding strain, at different temperatures
Authors: McCann E. P. , Calam C. T. 
Published: July 2010

AbstractResults are presented for a series of penicillin V fermentations run at temperatures from 19 to 30 °C. Data are given for penicillin production, cell production and carbon dioxide evolution. Consumption of arachis oil, lactose and glucose is recorded and some additional analytical results are provided. Penicillin production reached 10 000 to 11 000 units of penicillin V/ml. Optimal temperatures were 25 to 27 °C. The results are briefly discussed, and are published in the hope that they may be of value to others working in this field.
The unit cell of NaCaHSiO4: An electron‐microscope and X‐ray study
Authors: Alan Gard J. , Ramsay Cameron G. , Taylor Harry F. W. 
Published: July 2010

AbstractResults of selected‐area electron diffraction show that NaCaHSiO4 is monoclinic, with a = 5.72, b = 7.06, c = 5.48 Å, β = 122.5°, Z = 2, space group P21 or P21/m. A larger, B‐centred monoclinic unit cell can also be chosen and is dimensionally similar to the orthorhombic cell of Na2SO4(III) to which NaCaHSiO4 may be structurally related. NaCaHSiO4 may also be structurally related to several of the Ca2SiO4 polymorphs. Indexed X‐ray powder data are given.
Solute rejection by porous glass membranes. III. Reduced silica dissolution and prolonged hyperfiltration service with feed additives
Authors: Vernon Ballou E. , Leban Mark I. , Wydeven Theodore 
Published: July 2010

AbstractIt was found that inclusion of 0.3 g/l AlCl3,6H2O as a feed additive in hyperfiltration tests was sufficient to stabilise a porous glass membrane (batch A‐1) with relatively high volume flux and modest solute rejection characteristics. One‐tenth of this concentration was not sufficient. Further testing was directed toward treatment of porous glass membranes with concentrated aluminium chloride solution for a limited time, followed by hyperfiltration with a dilute feed additive. As little as 0.003 g/l AlCl3,6H2O stabilised batch A‐1 for 80 h; while batch A‐5, with lower volume flux and higher solute rejection characteristics, could be stabilised with no feed additive but only treatment with a concentrated aluminium solution every 100 h.Other experiments showed a similar equilibrium silica solubility, about 110 parts/million, in all solutions regardless of AlCl3, HC1, NaCl, or urea addition. The test which showed rates of silica dissolution revealed, however, that both low pH and aluminium lowered the rate of solution. The effectiveness of porous glass membrane stabilisation by aluminium treatment or reduced pH was also reflected in greatly reduced silica concentration of the effluent from hyperfiltration tests. Treatment of porous glass membranes with ferric and zirconyl chlorides was also tested, but aluminium chloride was the most effective in reducing silica loss.Chemical analysis of treated and tested membranes showed that aluminium remained in the pore structure in concentrations comparable to that of reactive silica hydroxyls. This is greater than the apparent concentration of ion exchange sites, and considerably less than total free hydroxyl concentration. Since suitable aluminium treatment or feed additive maintains membrane flux, rejection, and pore size characteristics, despite loss of soluble silica in the effluent, it appeared that added aluminium was retained in the membrane structure in amounts equivalent to the dissolved silica.
Structure and properties of microcrystalline waxes
Authors: Ratnasamy Paul , Anand K. S. , Gupta D. C. 
Published: July 2010

AbstractThe structure of three series of microcrystalline waxes has been studied using X‐ray diffraction and i.r. techniques. Their relative methylene/methyl group ratios as well as solid state parameters like size and shape of the unit cell, crystallite size and total crystalline fraction have been calculated. An attempt has been made to correlate these structural data with gross physical properties like oil content and needle penetration point. These correlations are found to hold good within any given series but varies from one series to another.