bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pyrolysis of methane in a single pulse shock tube
Authors: Napier D. H. , Subrahmanyam N. 
Published: July 2010

AbstractThe thermal decomposition of methane has been studied in a chemical shock tube at pressures up to 20 atm over a temperature range of between 1750 and 2700 K and for reaction times up to 2.5 ms. Attention is drawn to some of the experimental features of the shock tube and to the fact that reaction temperatures were measured.Optimum conditions for the production of acetylene from methane are suggested, and the relatively small effect of pressure on the acetylene yields is noted.Values for activation energy (93.6 kcal/mol) and frequency factor (3.8 × 1013 s−1 for methane decomposition are given. The experimental results obtained are discussed in connection with suggested mechanisms of decomposition. In the discussion attention is drawn to the difficulty of predicting acetylene yields arising from the incomplete understanding of the mechanism of acetylene decomposition and of “carbon” formation under the conditions employed.
Optimisation of a liquid extraction process
Authors: Jeffreys G. V. , Mumford C. J. , Herridge M. H. 
Published: July 2010

AbstractA mathematical model of a solvent extraction process has been developed which has been arranged into a form suitable for optimising the process by the indirect optimisation procedure and by the direct method developed by Hooke and Jeeves. These optimisation procedures have been compared by analysing an extraction process in which solvent recovery is by distillation.
A semi‐automatic method for the production of primary cell suspensions
Authors: Belton F. C. , Garriock D. J. 
Published: July 2010

AbstractA method is described for the production of primary chick embryo cell suspensions that allows the processing of from 200 to several thousand embryos daily at a significantly lower cost than with other methods. Special apparatus enables high yields of cells, free of microbial contamination to be produced under controlled conditions with the minimum of supervision.
The application of an infrared absorption technique to the measurement of moisture content of building materials
Authors: Cornell J. B. , Coote A. T. 
Published: July 2010

AbstractThe principles underlying the use of differential infrared absorption for measuring moisture contents are explained and it is shown how a commercial moisture recorder of this type, intended for measuring the moisture content of paper, may be adapted for the measurement of the moisture content of the surface and interior of some building materials. Encouraging results are obtained with mortars and aerated concrete, but the results with bricks are inexplicably erratic. The results are substantially independent of changes in the soluble salt concentration in the moisture. The method seems to merit further investigation though the present high cost of the apparatus will restrict its use.
The effect of various alkali metal fluoride solutions on the brushite—fluoroapatite transformation
Authors: Duff Edward J. 
Published: July 2010

AbstractThe brushite—fluoroapatite transformation reaction has been examined in 10−1 M solutions of NaF, KF, RbF, CsF and NH4F at room temperature. The nature of the alkali metal ion has no effect on the fluoride‐diffusion‐controlled reaction, although the incorporation of the cation into the apatite structure is dependent the nature of the alkali metal cation.
The concentration of mammalian cells in a tangential flow filtration unit
Authors: Radlett P. J. 
Published: July 2010

AbstractA tangential flow filtration unit is described through which cell suspension is continuously recycled. A pressure drop is incurred across the filter which forces liquid through the filter sheet, and cells in the remaining suspension are thus concentrated. The unit described has been used to concentrate 4 1 of cell suspension containing at least 2 × 106 cells/ml 12‐to 23‐fold in 2 to 4 h, with 94% viable cell recovery and little loss of viability. The filter is amenable to scale‐up and a pilot scale version is under test in this laboratory.
Concentration of the virus of foot‐and‐mouth disease in a tangential flow ultrafiltration unit
Authors: Morrow A. W. 
Published: July 2010

AbstractUltrafiltration by means of a thin channel tangential flow unit was used to concentrate suspensions of inactivated foot‐and‐mouth disease virus. When 5 to 7 1 batches were filtered, the liquid volume was reduced by approximately 98 % with little loss of antigen and good separation from nitrogenous compounds of low molecular weight.
The effects of some esters on friction with particular reference to railway locomotion. II
Authors: Dyson R. W. , Himatsinghani G. V. 
Published: July 2010

AbstractWork previously described has been extended by the use of an electron microscope. Examination with this instrument of variously treated rail steel surfaces has been correlated with friction measurements. The results are reported and discussed, and a tentative theory has been proposed in outline.
The hydrothermal preparation of sodium silicate
Authors: Hussein A. T. , Maksoud M. Abdel , Elwan S. M. 
Published: July 2010

AbstractA comparatively high steam pressure should be used to give complete sodium silicate formation from the starting materials. Moreover, a higher steam pressure is required in the case of using sodium carbonate than on using sodium hydroxide. Sodium metasilicate hydrate prepared under a low steam pressure (2.5 atm)a appears to be amorphous in nature while that prepared from sodium hydroxide or sodium carbonate at a higher steam pressure is crystalline and very similar to the metasilicate hydrate with the formula Na2SiO3. 9H2O. However, the metasilicate prepared from sodium carbonate appears to be poorly crystalline due to the presence, in the prepared material, of an appreciable amount of sodium carbonate.
Fischer—tropsch waxes. VI. Distribution of branches and mechanism of branch formation
Authors: Le Roux J. H. , Dry L. J. 
Published: July 2010

AbstractA statistical method for the calculation of the concentrations of normal and mono‐, di‐ and trimethyl paraffins to be expected in Fischer—Tropsch products was derived from first principles. It was tested by means of analytical results that were available for the lighter products, found to be quite adequate and then applied to “hard wax”. An explanation is sought for the extremely high degree of branching of a certain wax fraction reported previously, in the light of the results of the statistical calculations. A comparison is made between the calculated and experimental values for isoparaffin content.The method was also used to predict the variation of isoparaffin content with molecular weight and the theoretical curve thus obtained compared with reported analytical results. The possibility of a variation of the probability of a carbon atom being a branching site with chain length is discussed in the light of results reported by other workers.A mechanism for the formation of branches during Fischer—Tropsch synthesis is proposed. It is based on the single site growth point concept and on the separation of a chain from the catalyst surface as a free radical. Isomerisation of the original primary free radical to a secondary one occurs. If the latter re‐attaches itself to the catalyst surface and grows further, a branched chain product is obtained.
Some problems in the design of Ziegler‐type catalytic reactors
Authors: McGreavy C. 
Published: July 2010

AbstractSince the discovery of the remarkable properties of the Ziegler heterogeneous stereoregulating catalysts, an enormous amount of effort has been expended on investigating the mechanisms of such reactions. By comparison, the design of industrial scale reactors has not been discussed so widely. Nevertheless, as an example of the complex interactions between physical and chemical processes, it offers a considerable challenge to the techniques which have been developed over the past few years in reactor design. This paper reviews the present state of knowledge in this area and indicates where basic data are required. It also considers the potential benefits of some of the techniques being developed for control and optimisation of such systems.
Selective heterogeneous hydrocarbon oxidation over oxide catalysts
Authors: Wragg R. D. , Ashmore P. G. , Hockey J. A. 
Published: July 2010

AbstractThe heterogeneously‐catalysed oxidation of hydrocarbons over oxide catalysts is reviewed. The first section of the paper deals in a general way with the structural features of hydrocarbons and relates these to the selective oxidation products which may be obtained from them. The interaction of oxygen and hydrocarbons with oxides is also considered in a general context and the kinetics of heterogeneous oxidation of hydrocarbons are discussed. The second section of the paper deals in more detail with the selective oxidation of aromatic hydrocarbons with particular reference to vanadium oxide containing catalysts. Finally, an account is given of the selective oxidation of monoalkenes to 1,3 conjugated systems and ketones over mixed oxide catalysts. The information available is considered throughout with a view to revealing those features of such systems which give rise to the selectivity.
Carbon‐supported platinum metal catalysts for hydrogenation reactions. Mass transport effects in liquid phase hydrogenation over Pd/C
Authors: Acres G. J. K. , Cooper B. J. 
Published: July 2010

AbstractThe efficient use of palladium charcoal catalysts in liquid phase hydrogenation processes is shown to depend on hydrogen transport limitations from the bulk liquid phase to catalyst particles, and on the diffusion of hydrogen through the porous structure of the support to the active metal crystallites. These processes impose a strict limitation on the maximum rate of hydrogenation, and can effect the selectivity of reaction processes. The factors which control the output of a reactor in terms of operating conditions, and catalyst design are examined.
Regeneration of coked catalysts
Authors: Shettigar U. R. , Hughes R. 
Published: July 2010

AbstractThe intrinsic kinetics of carbon removal from a coked catalyst have been determined. Measurements have also been made of the transient temperature distribution inside a coked catalyst pellet during regeneration. These transient temperature distributions have been compared with predictions based on the sharp interface unreacted core model and on the finite thickness reaction zone model. The experimentally determined values of the maximum temperature rise were found to be in good agreement with the latter model but the sharp interface unreacted core model predicted temperature rises of a very much greater magnitude.
Estimation of the influence of the mass transfer conditions in studies of gas‐liquid reactions by the gasometric method
Authors: Björnbom Pehr 
Published: July 2010

AbstractThe purpose of this investigation was to study a method for estimating the influence of the mass transfer conditions in gas—liquid reactions studied by the gasometric method. Theoretically it is shown, that when a reaction is taking place in the slow reaction regime, the initial gas absorption rate is higher than later on in the reaction, since an accumulation of the gaseous reactant, dissolved in the liquid phase, must occur immediately after the contact between the gas and the liquid. This effect is typical for the slow reaction regime. The rate of the initial gas absorption can be used to calculate the degree of saturation of the liquid at any moment. Furthermore, the error in gasometric measurements due to changes in the rate of reaction is discussed and a formula is derived, which permits calculation of this error from the absorption curve. In the experimental part the use of this method is demonstrated on the liquid‐phase oxidation of benzaldehyde in acetic acid solution.
The non‐oxidative decomposition of heated sodium dithionite
Authors: Goodhead Kenneth , O'Neill Ian K. , Wardleworth Dion F. 
Published: July 2010

AbstractThe non‐oxidative decomposition of heated sodium dithionite was shown by thermal and i.r. spectroscopic analyses to proceed by two routes depending on sample configuration. The previously postulated reaction

predominated when the heaped substance was heated at 16 °C/min giving a sudden exotherm of 47 kJ mol−1 at 205 °C. In other conditions, particularly when heated in thin layers, two exotherms were found. The major exotherm at 210 °C yielded 63 kJ mol−1 the main products being thiosulphate, trithionate, sulphate and sulphite. A subsequent exotherm at 250 °C appeared to arise from phase changes in this material, coincident with the endothermic decomposition of sodium trithionate.
Standard gas and vapour mixtures for chromatography
Authors: Szeri Levente S. 
Published: July 2010

AbstractStandard mixtures of gases and vapours are prepared gravimetrically with a high degree of accuracy and are used for the calibration of large quantities of multi‐component mixtures which may serve as chromatographic standards for routine analysis of gases and vapours. A dilution method is used for the preparation of very low concentrations such as fractions of a parts/106 of pentane in helium.
Microwave heating in concrete analysis
Authors: Figg John 
Published: July 2010

AbstractMicrowave heating has been shown to be a valuable method for weakening concrete prior to the separation of aggregate in the analysis of hardened concrete. Quantitative determinations were made of the strength reductions of concrete samples after microwave radiation using a 5 kW laboratory microwave generator and a 1.5 kW (later 2.5 kW) microwave oven. Aggregate separation was much easier after heating for 5 and 20 to 30 min respectively. The modulus of elasticity correlated best with subjective assessments of the ease of aggregate removal. Thirty minutes irradiation in the microwave oven reduced the modulus of elasticity to one fifth of its original value, compressive strength was reduced to 80% of the unheated value and the tensile strength to 55 to 65%. Tests with ‘miniature’ concrete showed that the reduction in impact strength was similar to the compressive strength. Conducting aggregate does not preclude the use of microwave heating although large metallic inclusions (reinforcement) should be avoided. Irradiated concretes containing an appreciable proportion of clay may yield increased amounts of soluble silica during subsequent chemical analysis. Comparison with conventional heating shows that microwave heating can produce the same strength reductions in about half the time, but the cohesiveness of the material is affected more markedly by microwave irradiation. Appendices give notes on the use of microwave heating in the analysis of concrete and some observations on the behaviour of different types of concrete heated during routine investigations.
Crystallisation of gelatinous aluminium hydroxide
Authors: Sato Taichi 
Published: July 2010

AbstractThe gelatinous precipitates from aqueous aluminium chloride solution on the addition of alkalies at various pH have been aged in the mother liquors for a given period of time. The resulting materials have been examined by X‐ray diffraction studies. In addition, the changes in the pH value of the mother liquor and the amount of aluminium dissolved in the mother liquor during ageing have been checked under various conditions. As a result, it is found that the freshly precipitated gelatinous aluminium hydroxide exists in an amorphous type independently of the pH value and goes to pseudoboehmite by ageing, but the amount of aluminium dissolved in the mother liquor increases with rising pH value. By further ageing, however, hydrargillite is produced in contact with the aqueous medium at low pH, and bayerite at higher pH.It is concluded that the crystallisation of gelatinous aluminium hydroxide precipitates aged with an aqueous medium occurs in the processmagnified imageand the presence of alkali plays an important role in promoting these transformations.
The quantitative assessment of the fastness to washing of a range of disperse dyes on Nylon 6 filament
Authors: Cook Christopher C. , Hajisharifi Mohsen 
Published: July 2010

AbstractEstablished methods for the estimation of fastness to washing of dyes on textiles usually involve visual estimation of changes in colour of the treated fibre. Such a method is unsuitable for certain depths of shade, when the amount of dye lost during washing is low or when a continuous record of dye loss is required. A method for the quantitative, continuous assessment of removal of disperse dye from dyed nylon 6 filament is described and has been found suitable in the case of C.I. Disperse Reds 1, 7, 13, 19, 31 and C.I. Disperse Orange 3. Rate of loss of a given dye during a washing process depends on factors such as the temperature and degree of agitation of the wash liquors, and the amount of dye already present in the wash liquors. Loss of dye is not thought to involve dye decomposition.
Autoprecipitation as a method of fixation of radioactive strontium
Authors: Azzam A. M. , El‐Atrash A. M. , Ghattas N. K. 
Published: July 2010

AbstractThe autoprecipitation of strontium ions from alkaline solutions as strontium carbonate by the action of atmospheric carbon dioxide was investigated radio‐metrically using 89Sr as a tracer. Titanium hydroxide precipitated in situ was found to enhance the autoprecipitation process of strontium ions as carbonate. The method is suggested for strontium fixation from radioactive waste solutions.
Fermentative production of cycloheximide by Streptomyces griseus and Streptomyces noursei
Authors: Abou‐Zeid A. A. , El‐Sherbini S. H. 
Published: July 2010

AbstractTwo species of Streptomyces namely Streptomyces griseus and Streptomyces noursei were used for the fermentative production of cycloheximide on ten different media. For optimum production different media were required by each type of micro‐organism. Egyptian black strap molasses (50% reducing sugars) was favoured for both microorganisms, while other carbon sources such as sucrose was the best for S. griseus and glucose was suitable for S. noursei. Organic nitrogen sources were generally suitable for the growth of both microorganisms and the antibiotic production was best with soyabean meal for S. griseus and with casein for S. noursei. The optimum concentrations of KH2PO4 were 5.0 and 3.0 g/l for S. griseus and S. noursei respectively.
Vapour phase oxidation of ethylene glycol to glyoxal on supported cupric oxide
Authors: Hotanahalli S. S. , Chandalia S. B. 
Published: July 2010

AbstractThe vapour phase oxidation of ethylene glycol to glyoxal by air was studied in a stainless steel tube reactor using cupric oxide as a catalyst on carriers such as active alumina, pumice stone, silicon carbide, ceramics and fused alumina. A catalyst containing 3 to 5% cupric oxide on pumice stone was found to be satisfactory for the process. The effects of temperature, period of reaction and concentration of ethylene glycol and oxygen on the yield and conversion to glyoxal were studied, and the most suitable conditions were determined for the process. Carbon dioxide and formaldehyde were the major by‐products in the reaction. Formaldehyde was formed mainly due to the homogeneous reactions of ethylene glycol with oxygen in the void space of the reactor. The formation of glyoxal and carbon dioxide were correlated by suitable empirical rate expressions.
The critical temperatures and pressures of thirty organic compounds
Authors: Ambrose Douglas , Broderick Brian E. , Townsend Roger 
Published: July 2010

AbstractCritical temperatures and pressures of some organic compounds were measured. There is good agreement between the observed critical pressures and values obtained by extrapolation of equations representing the variation of vapour pressure with temperature in the region of the normal boiling point. An incremental scheme relating critical temperatures to normal boiling points is described and is used for the correlation of the critical temperatures, obtained in this and other investigations, of more than 150 compounds.
The course of hydration: Its practical importance and theoretical interpretation
Authors: Schiller K. 
Published: July 2010

AbstractThe practical usefulness of plaster is due to the solidification (set) which accompanies the chemical process of hydration. The paper exposes the mathematical relationship between the time it takes to hydrate (completely or to any incomplete extent) and such physicochemical parameters as the rates of dissolution and growth of the hemi‐ and dihydrates respectively, the solubilities, the number of dissolution and growth nuclei, particle shapes, etc. Possible modes of action of impurities, retarders and accelerators are suggested by implication. The basic principles from which this relationship is derived are mentioned. The various very different shapes which the hydration curve (extent of conversion versus time) can take are shown. A simple method is indicated to express mathematically the hydration curve of any given plaster. Reference is also being made to the relation between set and water gauge. Finally, the limitations of the theory are indicated.
Studies on the selective flotation of pyrochlore
Authors: Abeidu A. M. 
Published: July 2010

AbstractThe feasibility and the mechanism of the separation of pyrochlore from associated main silicate gangue minerals such as albite and biotite in an anionic collector system, using oleic acid and sodium dodecyl sulphate as collectors, in absence and presence of Fe(III), Cu(II) and Ca(II) have been investigated. Contrary to published data, the presence or addition of salts of these cations impairs rather than improves the selectivity of both soap and alkyl sulphate flotation of pyrochlore. However, leaching of the minerals investigated by HC1 greatly promotes their selective separation owing to selective teaching of metallic sites, namely Al3+, Mg2+ and Fe2+, from crystalline lattice surfaces of silicate minerals leading to the predominance of the negatively charged silicate sites. This leads to a marked sluggishness of their adsorbability of collector anions and their floatability. In contrast, leaching has almost no effect on the adsorptive capacity and floatability of pyrochlore due to the close chemical similarity of its cationic sites. Sodium dodecyl sulphate is superior to oleic acid because of its low pKa and the predominance of its collecting anions at pH of 2. These anions possess a great affinity for the positively charged Cb and Ta sites over negatively charged silicate sites, leading to the selective flotation of pyrochlore.
Influence of heating rate on the hydrothermal formation of kilchoanite from lime‐quartz mixtures
Authors: Mitsuda T. , Taylor H. F. W. 
Published: July 2010

AbstractIf mixtures of Ca(OH)2 and quartz with Ca : Si = 1.3–2.0 are processed hydrothermally at 350 °C and 400–500 bars, the products depend on the heating rate. If this is sufficiently rapid, the main product at Ca : Si = 1.5 is kilchoanite (Ca6(SiO4)(Si3O10)); this is accompanied at Ca : Si = 1.3 by xonotlite and at Ca : Si = 2.0 by calciochondrodite. If the heating rate is slower, the main products are combinations of xonotlite, foshagite and dellaite. If the heating rate is rapid, kilchoanite is formed at 300 °C, and, if it is rapid and sufficiently finely divided quartz is used, at 250 °C; it was not obtained at 200 °C. Broadly similar results were obtained at saturated steam pressures. At Ca : Si = 1.5, 250–350 °C and 400–500 bars, kilchoanite is possibly stable relative to the other solid phases, formation of which at slow heating rates is attributed to nucleation while the temperature is rising. To obtain the fastest heating rates, a new method was used, in which water is not admitted into the reaction vessel until the working temperature has been reached.