bluuebunny/crossref_metadata_2025 huggingface dataset:
Esterification of ethylenediaminetetraacetic acid
Authors: Alner D. J. , Claret P. A. , Osborne A. G.
Published: July 2010

The esterification of ethylenediaminetetraacetic acid (EDTA) in a hot acidic medium gives rise to impure products. The impurities have been identified and shown to be esters of various acids: nitrilotriacetic acid; iminodiacetic acid; piperazine‐1,4‐diacetic acid; N‐methylethylenediaminetriacetic acid; N,N‐ and N,N′‐dimethylethylenediaminediacetic acids and 2‐ketopiperazine‐1,4‐diacetic acid. The reactions for the formation of these impurities are discussed and a method for the preparation of pure esters of EDTA is described. Details of some crystalline derivatives, 1H‐n.m.r. and infrared spectra of a series of esters of EDTA are presented. The determination of the molecular weights of the esters by saponification is discussed.
The oligomerisation of isoprene catalysed by nickel naphthenate and isoprene magnesium
Authors: Suga Kyoichi , Watanabe Shoji , Fujita Tsutomu , Shimada Takashi
Published: July 2010

The oligomerisation of isoprene catalysed by nickel naphthenate and isoprene magnesium was studied under various conditions. The use of various phosphites as donors gives cyclic dimers containing dimethyloctadiene (about 90%); in particular 1,1,1‐trishydroxymethylpropane phosphite gives trimethylcyclo‐dodecatriene selectively. The use of triphenylphosphine gives a linear isoprene trimer containing farnessene.
Fluorination in gaseous phase of carbon tetrachloride on aluminium fluoride catalyst: Kinetics and chemical mechanism
Authors: Gambaretto Gian Paolo , Avezzu Francesco , Gola Everardo
Published: July 2010

The fluorination in gaseous phase of carbon tetrachloride has been investigated on aluminium fluoride with the aim of defining the mechanism of the reaction on this catalyst.

The reactor and the operating conditions, were chosen in such a way as to isolate the effects of diffusion analysing the single reaction steps.

While for the process in liquid phase the kinetics appears to be controlled by the formation of activated complexes between carbon tetrachloride and the catalytic support, the selective adsorption of HF on the catalyst is more probably the controlling step when the reaction is carried out in gaseous phase.
Glycerolysis of methyl esters of fatty acids using molecular sieves
Authors: Barrer Richard M. , Ruiz José L. LÓPez
Published: July 2010

Glycerolysis of the methyl esters of oleic and stearic acid has been investigated in presence and absence of zeolite 4A. By removing the methanol produced this zeolite improved the yields of glyceride substantially. Other factors studied which influenced the yields were temperature, reactant concentrations and proportions and catalyst.
The thermodynamics of fluorine loss during the chemical analysis of welding fluxes
Authors: Halstead W. D.
Published: July 2010

The chemistry of the solution of welding fluxes in Li2O‐B2O3 melts prior to analysis has been examined using chemical thermodynamics. A chemical model describing these melts is proposed, and using it, the particular abilities of two components of the fluxes, SiO2 and Al2O3, in facilitating loss of fluorine from the solutions, are described.
The preparation and characterisation of crystalline α‐zirconium phosphate
Authors: Horsley Stuart E. , Nowell Derek V.
Published: July 2010

Crystalline α‐zirconium phosphate has been prepared by four methods. The products have been characterised by chemical and thermal analysis, X‐ray and infrared spectroscopy, surface area, porosity and particle size determinations and electron microscopy. A method is recommended for the preparation of crystalline α‐zirconium phosphate.
Kinetic models for the setting of plaster of paris
Authors: Taplin John H.
Published: July 2010

A general rate equation is derived for processes such as the hydration of calcium sulphate hemihydrate in which the position of the rate maximum depends on the relative rates of dissolution and precipitation. Allowance is made for these processes to depend on powers of under or super‐saturation other than unity and for limitation of the precipitation rate by crystal‐crystal contact.

The equations of Ridge and of Coombe et al. have the rate maximum fixed at 60 and 28 % respectively due to inadequate derivation, however they are both readily fitted by the general equation.
The thermal decomposition of pure and doped cadmium carbonate: II. Surface and pore structure studies
Authors: Mikhail R. Sh. , Dollimore David , Kamel A. M. , El‐Nazer N. R.
Published: July 2010

Specific surface areas and pore structure studies were carried out on pure and doped cadmium carbonate heated at different temperatures. Doping with a different valency cation than the host ion was found to influence appreciably both the extent and location of the surface. Results could be interpreted in terms of anion vacancy mechanism, in which these vacancies could be created in the case of Li+ doping and could be annealed in the case of Al3+ doping, thus affecting “material” transport which in turn is reflected in changes in the extent and location of the surface. In this respect Al3+ ions might act as “inhibitors” for material transport and thus lead to a “stabilised” pore structure. The results implicitly suggest that “material” transport is more significant in affecting the pore structure than changes in the rates of isothermal decomposition.
Liquid phase oxidation of cyclohexanone to adipic acid by air in acetic acid solution
Authors: Kamath Sharatchandra S. , Chandalia Sampatraj B.
Published: July 2010

The liquid phase oxidation of cyclohexanone to adipic acid by air in the presence of acetic acid as a solvent and cobalt acetate or manganese acetate as a catalyst was investigated at a temperature of 60 to 100 °C, and at essentially atmospheric pressure. Succinic acid and glutaric acid were the major by‐products. Under the most suitable set of conditions (cyclohexanone, 1.2 M; cobalt acetate, 7 × 10−3 M; superficial air velocity, 2.5 cm/s, temperature, 80 °C; period of reaction, 5 h), the overall conversion of cyclohexanone was 61 % and the yield of adipic acid and diabasic acids was 69.3% and 85.6% respectively.
High‐pressure steam curing of high‐slag cement: I. Composition of the hydrated cement
Authors: Kamel Abdel‐Aziz H.
Published: July 2010

The phases formed in a high‐slag cement on curing in saturated steam at 180 lbf/in2, have been investigated. X‐ray diffraction revealed that in the presence of suitable addition of fine quartz, 11‐Å tobermorite was the predominant phase formed in an autoclaving period of 5 h at maximum pressure; the phases identified in neat slag cement were 11‐Å tobermorite and hillebrandite. The same phases were identified in the samples autoclaved for 6 h, in addition to minor amount of xonotlite. Chemical analysis of the same hydrated samples has shown that the molar CaO/SiO2 ratio was 1.27 for the cement‐quartz and 1.49 for the neat cement for the 5‐h autoclaving period, and 1.35 and 1.57, respectively, for the 6‐h period.
High‐pressure steam curing of high‐slag cement. II. Strength of cement‐sand mixes
Authors: Kamel Abdel‐Aziz H.
Published: July 2010

The strength of dense high‐slag cement‐sand mixes autoclaved at 180 lbf/in2, and of certain aerated mixes autoclaved at pressures ranging from 120 to 210 lbf/in2, has been determined. It was found that maximum strengths were developed in an autoclaving period of 5 h at 180 lbf/in2, and that longer periods, as well as higher autoclaving pressures, yielded lower strengths. The maximum strength values obtained for compacted 1: 3 (w/w) mixes were 425 kg/cm2 in the absence of fine quartz, and 510 kg/cm2 in the presence of suitable addition of fine quartz. The corresponding values for Portland cement mixes were, respectively, 330 and 460 kg/cm2 for a heating period of 5 h, and 360 and 505 kg/cm2 for a period of 6 h.
Pulp and paper from corn stalks
Authors: Amine Abou‐State M. , Zimaity Tawfik , El‐Masry Ahmed M.
Published: July 2010

The whole corn plant was successfully used for the production of pulp and paper by employing comparatively simple procedures of atmospheric pressure digestion followed by multi‐stage bleaching. Water pre‐treatment was found necessary to remove the dust particles. However, the use of boiling water was not recommended. The effects of the amount of active chlorine in the hypochlorite step on the optical and the physical‐strength properties of paper were investigated. One‐and two‐stage pulping were compared and the effect of depithing after the first stage was studied.
Investigation of the energetics of methane‐utilising bacteria in methane‐ and oxygen‐limited chemostat cultures
Authors: Nagai Shiro , Mori T. , Aiba S.
Published: July 2010

A special apparatus was used to establish methane‐ and oxygen‐limited chemostat cultures of a methane‐utilising bacterium, at 30 °C, pH = 7.0, respectively. Although total growth yields with respect to methane and oxygen were hardly affected by dissolved oxygen concentration in the medium, provided dilution rate was kept nearly at 0.1 h−1, these values appeared to increase slightly with the increase of dilution rate. Assuming that no metabolites other than carbon dioxide and water were produced during bacterial growth, maintenance coefficients and true growth yields were assessed from specific rates of methane uptake and respiration. These energetic constants, nearly independent of the limiting substrates, either methane or oxygen, were compared with those from published data on facultative and obligate aerobes, including a mixed culture of methane‐utilising bacteria.
The vapour—liquid equilibria of the binary, ternary and quaternary systems formed by acetone, methanol, propan‐2‐ol, and water
Authors: Verhoeye Lucien , De Schepper Herman
Published: July 2010

The vapour‐liquid equilibrium data of the binary, ternary and quaternary systems that may be formed by combination of the components acetone, methanol, propan‐2‐ol and water, have been determined at 760 mmHg by means of an equilibrium still based on the principle of circulation of both phases. The binary data have been correlated by means of the Margules and of the Wilson equation. The data of the ternary and quaternary systems have been predicted by these equations. The results of both equations are discussed and compared.
The choice of sampling tube material in the determination of nitrogen oxide concentrations in products of combustion
Authors: White Alan , Beddows Linda M.
Published: July 2010

It has been confirmed that when hot products of combustion containing traces of nitrogen oxides are sampled through metal tubes the concentration falls. The mechanism is in part due to the conversion of nitrogen dioxide to nitric oxide. Glass tubing may be used as a substitute at high sampling temperatures and PTFE is suitable at lower temperatures; nylon, EVA and PVC tubing should not be used since significant losses may occur in these materials even at room temperature.
Changes in south‐east anatolian bitumens and their main fractions under various oxidative conditions
Authors: Tüzün C. , Yaǧiz F.
Published: July 2010

Fractional analyses of South‐East Anatolian bitumens were made using Marcusson's method and changes in fractional compositions and in functional groups under oxidative conditions were investigated. A more detailed study was carried out on the asphaltic resins fraction of bitumen of Maǧrip origin, since, of those tested, this bitumen proved to be the most susceptible to oxidative conditions.
A simple high‐temperature infrared cell and its application to the dehydroxylation of kaolinite
Authors: Mackenzie Kenneth J. D.
Published: July 2010

A simple method is described for making infrared measurements on solids at temperatures up to the melting point of KBr by using a fine nichrome heating coil wound directly on to the KBr disc containing the sample either in suspension or sedimented on to the surface. The usefulness of the method is illustrated by intensity measurements of the hydroxyl stretching bands in kaolinite as a function of temperature, which are compared with results obtained by the more conventional quenching method.
Oxidation of ferrous hydroxide suspensions. I
Authors: Prasad T. P. , Ramasastry V. V.
Published: July 2010

Ferrous hydroxide suspensions, obtained by the addition of calcium hydroxide to ferrous sulphate solution have been oxidised at room temperature (28 ± 3 °C). The extent of oxidation and the rate of oxidation were studied as a function of time by varying the air flow rate, concentration of calcium hydroxide (stoichiometry) and the concentration of ferrous sulphate. Expressions have been obtained giving the relation between velocity constant, k, and the air‐flow rate as well as between k and concentration of ferrous sulphate.
Anion exchange of uranium from aqueous sulphuric acid solutions: Diffusion kinetics
Authors: Barnes C. D. , Da Silva Neves R. A. , Streat M.
Published: July 2010

The ion exchange kinetics of uranium sorption from acidic sulphate solutions onto weak and strong base resins has been studied. In order to facilitate experimentation and analysis, isotopic redistribution experiments of uranyl sulphate ions (with U‐235 as a tracer) under conditions of particle diffusion control have been performed. Also, self‐diffusion experiments for sulphate ions (with S‐35 as a tracer) and counter diffusion measurements involving uranyl sulphate‐sulphate exchange have been performed. The ion exchange of uranium is a slow reaction and appears to be particle diffusion controlled at all solution conditions of practical interest. For a weak base resin (Relite MG‐1), the self‐diffusion coefficient of uranyl sulphate ions changes with particle size, increasing from 1.49 to 4.88 × 10−9 cm2/s as the particle diameter is reduced from 0.146 to 0.054 cm. With a strong base resin (Dowex‐1×8), the self‐diffusion coefficient of uranyl sulphate ions remains reasonably constant with varying particle diameter at a value of 1.76 × 10−9 cm2/s. Sulphate ion self‐diffusion coefficients were also constant with particle size (2.50 × 10−7 cm2/s) and the counter exchange diffusivity lies between the values for the individual species; a typical value is 1.53 × 10−8 cm2/s. It is argued that resin matrix structure has a significant effect on uranium kinetics and that a knowledge of the relevant diffusion coefficients will provide a rational basis for the design of ion exchange processes and plant equipment.
1,2‐Asymmetric induction when grignard reagents are added to α‐aminoketones. II. Structural effects. Application to the stereoselective synthesis of α‐aminoalcohols
Authors: Gaset Antoine , Audoye Paul , Lattes Armand
Published: July 2010

The best conditions for obtaining selectively diastereoisomeric aminoalcohols have been determined in an example where the combination of environmental and structural effects has controlled the addition of Grignard reagents to α‐aminoketones.
Extraction of some mineral acids by high molecular weight quaternary ammonium chloride
Authors: Sato Taichi , Watanabe Hiroshi , Kikuchi Shoji
Published: July 2010

The distribution equilibria of hydrochloric, nitric, perchloric, sulphuric and phosphoric acids between aqueous solutions and a solution of tricaprylmethyl‐ammonium chloride in organic solvent have been investigated. The organic phases have been studied by infra‐red and nuclear magnetic resonance spectroscopy. As a result, it is found that at low aqueous acidity the extraction of these acids is governed by the ion exchange reaction, forming the mono‐quaternary ammonium salts of monobasic acids and the mono‐, di‐ (and tri‐) quaternary ammonium salts of di‐ (and tri‐) basic acids, and at higher acidity by the formation of the adducts to quaternary ammonium salts with additional acids.
Variations in gypsum and the reactivity of its product of calcination
Authors: Ridge Mayhew J. , King George A. , Molony Bruce C.
Published: July 2010

Five samples of Australian gypsum and one from Thailand were analysed chemically and subjected to comparable degrees of grinding and calcination. During hydration of the products considerable differences were found in the periods of induction and other kinetic parameters. Both differences in nucleation, and in the transport of calcium sulphate from the grains of hemihydrate to the growing crystals of dihydrate, seemed to contribute to the variations in reactivity. The variations did not seem to be related to the content of sodium sulphate, but a connection with that of chloride was indicated. The samples of gypsum varied in their susceptibility to transformation to orthorhombic calcium sulphate.
A new method for the preparation of acicular goethite crystals
Authors: Derie R. , Ghodsi M. , Hourez R. J.
Published: July 2010

A new method of preparation of goethite (α‐FeO(OH)) is described. It involves simultaneous oxidation and precipitation from a solution of FeSO4 by means of the addition of a mixture of sodium hypochlorite and sodium carbonate. It is possible to use other oxidants and other alkaline substances. One can also coprecipitate various heteroelements. A brief description is given of the effect of these foreign elements on the magnetic properties of the oxides of the type γ‐Fe2O3 obtained after subsequent reduction and reoxidation.
A dry electrochemical cell containing cupric chloride supported by γ‐alumina
Authors: Aharoni Chaim , Inbar Jonathan , Roker Moshe , Rosenzweig Nahum
Published: July 2010

An electrochemical cell was formed by enclosing a commercial catalyst containing cupric chloride supported by γ‐alumina between electrodes of copper and iron. The voltage obtained is a logarithmic function of the vapour pressure of the water sorbed by the support. Voltages of a few hundred millivolts are obtained at relative pressures between 0.1 and 0.8 and temperatures between 25 and 170°C.
Ultraviolet absorption spectra: Some substituted benzoic acids
Authors: Kamath B. V. , Mehta J. D. , Bafna S. L.
Published: July 2010

The u.v. absorption spectra of 22 monosubstituted and 19 disubstituted benzoic acids have been studied in water or aqueous dioxan over a pH range of about 1–8. The isosbestic points have been measured and the results are discussed.
Densities of urea–ammonia–water–carbon dioxide solutions in chemical equilibrium at and above urea synthesis conditions
Authors: Broers Jan N. , Lemkowitz Saul M. , Van Berg Pieter J. Den
Published: July 2010

The densities of the urea synthesis solution in chemical equilibrium have been measured over the ranges 2.04 ⪕ NH3/CO2 ⪕ 6.3, H2O/CO2=0, 150 ⪕ T ⪕ Tcritical and Pbuble–point ⪕ P ⪕ 900 atm. In the temperature and composition range of, respectively, 150 ⪕ T ⪕ (Tcritical–20°C) and 2.7 ⪕ NH3/CO2 ⪕ 6.3, it is possible to describe accurately the experimental results by means of an empirical equation based on regression analysis. Experiments suggest that at high temperatures near critical conditions the chemical composition of the urea synthesis solution becomes a strong function of pressure.
Removal of radioactive strontium from water by coagulation–flocculation with ferric hydroxide
Authors: Bull Patrick S. , Evans John V. , Knight Ronald J.
Published: July 2010

A systematic study of the removal of the radioactive fission product strontium from aqueous solution by ferric hydroxide flocs has shown that strontium can be removed effectively, in contrast to caesium which is poorly removed (⩽5%) under all conditions examined. Removal of strontium was enhanced by raising pH to a maximum of 10.5, increasing the iron/strontium ratio, or by adding phosphate ion, provided the phosphate/iron mole ratio did not exceed 0.33. In the absence of phosphate the optimum conditions for strontium removal, over the range of iron and strontium concentrations examined, were pH 10 and strontium/iron mole ratio 0.08. Addition of phosphate reduced the pH at which significant removal was obtained to about 8. The mechanism of removal has been identified as an ion‐exchange reaction at the surface of the ferric hydroxide particles; consequently, when considering the process for the removal of stron‐tium‐90 from hard natural or process waters competitive effects from the larger concentrations of calcium and magnesium present in the water would become important.
Some quantitative studies on light fading of after‐treated direct dyes
Authors: Shah Champaklal D. , Srinivasan Rajagopalan , Venkateshmurthy J.
Published: July 2010

Quantitative measurements of increase in lightfastness of direct dyes on cellophane on after‐treatment with different metallic salts, e.g. sulphates of copper, cobalt, nickel, chromium and (ferrous) iron have been carried out. Copper sulphate has been found to be the best of all these salts. About 2% copper sulphate is found to cause considerable increase in the lightfastness. Measurements of y/x ratios of dyed and after‐treated cellophane and also slopes of CF curves have shown that the higher fastness is due to higher aggregation of the dye in the fibre on after‐treatment with copper sulphate. Metal complex formation with dye structures of the type o‐hydroxy‐o′‐methoxy (or o′‐hydroxy or ethoxy) azo has been found to be more useful for copper after‐treatment than complex formation with dyes with a salicylic acid residue.
Effect of pH on the retention of inorganic fillers
Authors: Jaycock Michael J. , Pearson Joseph L.
Published: July 2010

The effect of pH on the retention of various inorganic fillers has been studied. It is found that the isoelectric point of the filler has no effect on its retention characteristics with our particular sulphate bleached pulp. This is due to the fact that the surface of the filler is modified by either the adsorption of or the flocculation with the fines and colloidal material originating from the fibre surface. This surface modification produces a shift of the apparent isoelectric point of the fillers and in many cases gives rise to heteroflocculation of the fibres and filler particles only when the pH is at more acid values than 4.0.
Hardened slag–cement pastes of various porosities. III. Surface area in relation to pore structure
Authors: Mikhail Raouf Sh. , Abo‐El‐Enein Salah A. , Abd‐El‐Khalik Mohamed
Published: July 2010

The total surface areas, total pore volumes, and the distribution of pore surface and pore volume in pores of different sizes were determined on the hardened slag‐cement pastes. Adsorption isotherms of four different adsorbates, namely water, methanol, nitrogen and cyclohexane, were used for surface area and pore structure determinations. The results obtained indicated that water can penetrate into the total pore system, namely both the micropores and the wide pores; whereas methanol can measure wide pores and some of the micropores; moreover, nitrogen and cyclohexane molecules tend to measure only wider groups of pores. The indication gained from this result is that the molecular sieve property plays the most significant role in surface area and pore structure determinations of the hardened cement pastes. The polarity of the molecules seems to be important at low relative vapour pressures, and at high pressures it causes expansion of the pastes.
Alkane sulphonate preparation by the sulphitation of long chain olefins
Authors: Bright Samuel C. , Stubbs Christopher E. , Thompson Laurence
Published: July 2010

The free radical addition of sodium bisulphite to linear olefins (sulphitation) has been investigated. It was observed that the kinetic consequences of the probable mechanism of sulphitation were consistent with the experimental results. Thus sulphitation is first order with respect to olefin concentration and above a critical level is independent of bisulphite concentration. In the sulphitation of 1‐dodecene an undesirable alkane–sulphonate–sulphinate forms, the proportion of which, as expected, varies with sulphitation pH; the higher the pH the less the proportion of sulphonate–sulphinate. To prepare alkane sulphonates optimally thereby restricting the sulphonate–sulphinate proportion to an acceptable minimum (15% w/w) sulphitation pH should be the maximum at which the critical bisulphite concentration can exist. Further minimisation of sulphonate–sulphinate formation requires a new approach. It was found that whereas linear olefins give rise to this product, as does 1‐hexyne, vinylidene olefins, styrene and 1,3–hexadiene do not. These observations have been rationalised in terms of the relative thermal stabilities of the intermediate sulphone–sulphonate radicals.
Metallurgical characterisation of high resilience stainless steel orthodontic wires
Authors: Williams David W. , von Fraunhofer Joseph A. , Davies Edward H.
Published: July 2010

Nominally 0.4 mm diameter high resilience stainless steel orthodontic spring wires, as used in appliances (or braces) for the correction of children's malaligned teeth, are notoriously inconsistent in their clinical behaviour. This is principally due to a lack of compositional control and to the severe work hardening of the wire drawing process. A selection of the spring wires in clinical use has been investigated here to characterise them by means of spectrochemical analysis, tensile testing, potentiostatic polarisation, and ferromagnetic measurements. The study of these interrelating factors is suggested as a method of characterisation for the wires to ensure greater clinical consistency. The effects of bending and low temperature heat treatment on the wires have also been investigated.
Prediction of isobaric and isothermal vapour–liquid equilibria from limited experimental data
Authors: Khanna Ashok , Mukhopadhyay Mamata
Published: July 2010

Malesinski's method for prediction of isobaric vapour–liquid equilibrium data using a single experimental datum on a T–x isobar has been modified and extended to a more general case where the molar entropies of vaporisation of the components are not necessarily equal and the non‐ideality in the vapour phase is considered. However, it is assumed that the solution behaves like a strictly regular one over the temperature range in question, that is, the constant A in the expression for excess free energy: gE=Ax1x2 is independent of temperature. The method has been illustrated for several systems and is found to be highly satisfactory for non‐polar–non‐polar as well as polar–non‐polar systems in which the boiling points of the pure components are not much different. Incorporating temperature dependence of the constants in the Redlich–Kister equation for excess free energy, a method has been developed for predicting isothermal vapour–liquid equilibrium data at several temperature levels from equilibrium values at a single pressure. For testing the validity of this method, predicted results have been compared with the available experimental data for zeotropic as well as azeotropic systems comprising non‐polar–non‐polar, polar–non‐polar and polar–polar mixtures, and the method has been found to be satisfactory for all systems.
Textural variations of acid‐treated serpentine
Authors: Girgis Badie S. , Mourad Wedad E.
Published: July 2010

A natural serpentine deposit was subjected to treatment with hydrochloric acid of different concentrations, and for varying times. Changes in the texture parameters were determined from adsorption isotherms of nitrogen. In general, treatment with increasing acid concentrations (up to 25%) leads to an increase in various characteristics of serpentine, i.e. weight loss, dissolved iron oxide, “free” silica, surface area, and pore volume. Prolonged treatment results in only slight changes in such parameters. Solids of high specific surface areas (up to 300 m2/g) and of microporous character (mean pore radii ca 15–20 Å) are obtained.
Activation of platinum‐alumina catalysts for the hydrogenation of aromatic hydrocarbons
Authors: Aboul‐Gheit Ahmed K. , Cosyns J.
Published: July 2010

A white spirit fraction was hydrogenated in a continuous flow microreactor unit, using 0.35% platinum‐alumina catalysts. These catalysts contained 0.0, 0.40 or 0.87% chlorine. Chlorination of the catalysts was carried out during the process of platinum impregnation. This treatment was found to enhance significantly the hydrogenation activity of the catalysts, and may be attributed to an improvement in the dispersion of platinum in the alumina support. Calcination of the catalysts before their reduction proved to be an important preparation step. Increasing the reduction temperature from 200 to 500°C considerably increased the catalytic activity. The activation energies obtained for hydrogenation of aromatics over catalysts reduced at temperatures between 200 and 500°C were found to range between 10.14 and 6.50 kcal mol−1. These energies were found to decrease, in general, with increasing chlorine content of the catalyst and with its reduction temperature. The variation in activation energy with the Arrhenius pre‐exponential factor, as a function of the catalyst reduction temperature, indicates that catalysts containing 0.40 and 0.87% chlorine follow the equation k0 = exp (‐3.25 + 0.001E), and hence their surface uniformity would be identical. However, unchlorinated catalysts, both calcinated before reduction or uncalcinated, exhibit considerably different surface uniformity.
Pressure effects in the infrared vibrational spectra of gaseous molecules
Authors: Corbett John K.
Published: July 2010

A new semi‐empirical equation is proposed which predicts the extent of the observed spectral intensity enhancement caused by the effect of foreign gases on many infrared‐active gaseous molecules. The evolved expression has the form:

Sv2μ−1=A exp {−B/(F+C)}

Where S is a symmetry factor, v is the vibrational frequency (cm−1), μ is the reduced mass of the colliding pair, and F is the spectral enhancement factor for one atmosphere of foreign gas. A is a constant for a particular foreign gas, and B and C are general equation constants with values B = 18.5 and C = 1.5. Predicted and observed values of the enhancement factors are listed for a range of common gaseous molecules in the foreign gases nitrogen and helium. Suggested causes of the discrepancies between the calculated and experimental results are briefly discussed.
Increase of β‐glucanase production by Bacillus subtilis by use of starch feeding during fermentor cultivation
Authors: Markkanen Pertti , Reinwall Anneli , Linko Matti
Published: July 2010

The production of β‐glucanase by Bacillus subtilis VTT 160 was studied. Using a medium containing barley and distiller's grain the concentration of available sugars approached zero at the end of the phase of active production of β‐glucanase. For this reason starch feeding was employed, commencing at this stage of the cultivation. Markedly increased yields of β‐glucanase were obtained when the starch feed was commenced at the correct time.
Hindered settling of organic pigment dispersions in hydrocarbon liquids
Authors: McKay Robert B.
Published: July 2010

A 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

The 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

When 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

In 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

Studies 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

The 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

Work 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

The 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

The 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

The 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.
Measurement of diffusion and flow of gas through a porous solid
Authors: Ray Hem Shanker
Published: July 2010

Experiments for measuring the flow or diffusion of a gas through a porous solid are described. The experiments allow calculation of an effective diffusion coefficient and the tortuosity factor for a porous sample of undefined pore characteristics.
Purification of mitomycins produced by Streptomyces caespitosus
Authors: Abou‐Zeid Abou‐Zeid A. , Yousef Abd‐El‐Sadek A.
Published: July 2010

Mitomycins 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

The 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

A 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

Fifteen 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

The 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

Desulphurisation 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

A 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

The 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

Permeation 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.
The filtration characteristics of yeast
Authors: Rushton Albert , Khoo Hock E.
Published: July 2010

The filtration characteristics of yeast cells are reported and the use of the information in process calculations of filtration rates is demonstrated. Comparison is made between filtration properties obtained by vacuum filtration studies and permeability measurements. The kinetics of cell growth are followed by size distribution records.