bluuebunny/crossref_metadata_2025 huggingface dataset:
The hydrothermal preparation of sodium silicate
Authors: Hussein A. T. , Maksoud M. Abdel , Elwan S. M.
Published: July 2010

A 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

A 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

Since 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

The 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

The 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

The 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

The 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

The 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

Standard 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

Microwave 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

The 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

Established 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

The 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

Two 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

The 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

Critical 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

The 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

The 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

If 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.
The condensate polishing performance of powdered ion‐exchange resins
Authors: Bull Patrick S. , Evans John V. , Nicholson Frank D.
Published: July 2010

The coating properties and ion‐exchange performance of powdered ion‐exchange resins were examined in a small test facility. Satisfactory resin coatings were obtained with cation : anion resin ratios in the range 1 : 1 to 3 : 1, but a 9 : 1 resin ratio resulted in a high pressure drop across the coating. The “settled resin volume” proved to be a reliable guide to the coating performance of resin slurries. The ion‐exchange capacity of the cation resin increased from 2.5 to 2.8 equiv./kg as the sodium concentration in the influent decreased from 49 to 0.5 mg 1−1. Within the ranges examined, resin ratio, resin loading and flowrate had no significant effect on cation capacity. The ion‐exchange capacity of the anion resin for chloride ions was 2.2 to 2.3 equiv/kg at ambient temperature but exposure of the resin for four days at 80 °C reduced the capacity to 1.6 equiv./kg; four days at 90 °C reduced the capacity to less than 1 equiv./kg. The thermal stability of the powdered anion resin was markedly less than that quoted elsewhere for anion bead resin. The stability of the floc was also investigated.
Kinetics of sintering of unsupported platinum catalyst in nitrogen, oxygen and hydrogen atmospheres
Authors: Hassan Salah A.
Published: July 2010

The sintering of platinum black catalyst in different atmospheres, namely, nitrogen, oxygen and hydrogen was studied in the temperature range 300‐600 °C.

The rate of sintering was found to differ in different atmospheres; it is the least in oxygen, whereas in nitrogen the sintering seems to be much facilitated and in hydrogen the rapid de‐activation becomes much more pronounced.

Analysis of the kinetic results showed that the sintering process follows the first order equation in nitrogen and in vacuo, and follows the second order equation in oxygen and hydrogen atmospheres.

The activation energy of the sintering process, calculated from the Arrhenius equation, was found to be 2.9, 3.7 and 13 k cal/mol in hydrogen, oxygen and nitrogen respectively, as obtained from the activity measurements, and 3, 3.5 and 12.5 respectively, as obtained from the surface measurements. An interpretation was given for the high activation energy of sintering in nitrogen in view of compound formation on the surface.
Studies on bitumen production from North Rumaila crude oil
Authors: Tripathi Raghunath P. , Bahl Jogindar S. , Purohit Ramesh C.
Published: July 2010

In the present investigation, the effect of three process variables viz., air rate, temperature and time of oxidation has been studied to determine the possibility of making paving bitumens from North Rumaila Crude Oil. In order to have flexibility in the choice of proper feedstock for bitumen production, the effect of these process parameters was studied on three different vacuum residues. Air rate and temperature of oxidation were optimised to produce a bitumen product having less temperature susceptibility. The composition studies of typical feeds and oxidised products indicate that mainly “saturates” components get converted to “asphaltics” on air blowing.
Disinfection by electrohydraulic discharges
Authors: Stirling Robert , Bettelheim Karl A.
Published: July 2010

Many sterilisation techniques are available which rely on physical chemical processes, the final choice being dictated by the particular application. The electrohydraulic discharge technique was investigated with the aim of optimising bacterial inactivation in a variety of aqueous fluids. Discharges were produced between two submerged electrodes by the rapid release of electrical energy stored in a capacitor. Variations in optical density of the fluid undergoing treatment greatly influenced the degree of cellular inactivation and it is postulated that U.V. radiation from the discharge is the principal bactericidal agent.
Thermal decomposition, structural changes and surface properties of chromium oxide gel
Authors: Mikhail R. Sh. , Selim S. A.
Published: July 2010

Structural and phase changes of a prepared sample of chromium oxide gel were explored by differential thermal analysis and X‐ray diffraction analysis. Dehydration products were obtained at various temperatures up to 740 °C, by heating in air for 3 hours. Samples obtained by heating below 320 °C were amorphous to X‐rays whereas those obtained at 320 °C, and between 320 and 510°C proved to be a mixture of α‐ and γ‐Cr2O3. However, at temperatures above 510 °C, only one form, the stable α‐Cr2O3 exists. The glow phenomenon is attributed to the presence of excess oxygen, resulting from the reduction of Cr(VI) to Cr(III), just prior to the conversion of the amorphous gel to the crystalline γ‐Cr2O3, which is accompanied by a release of energy.

Surface area measurements were carried out by cyclohexane, methanol and water adsorption at 35 °C, and the areas were compared with those measured by nitrogen at liquid nitrogen temperature.

Pore structure analysis for both micro‐ and mesopores were carried out. The low temperature samples are characterised by the presence of both types of pores, with the micropore fraction predominating acquiring thus the property of molecular sieves; the pores being accessible to water and nitrogen but not to cyclohexane or methanol. At temperatures above 320 °C, the microporosity collapses with the production of a heterogeneous assembly of mesopores. In the mean time the surface changes to be hydrophobic in nature; accordingly it cannot be measured from water adsorption.
Flocculating agnets derived from kraft lignin
Authors: McKague A. Bruce
Published: July 2010

The Mannich reaction product, a dihydrooxazine and a quaternary ammonium salt were prepared in high yield from the model compound 4‐propylguaiacol. When these reactions were extended to the purified kraft lignin, Indulin AT, products were obtained which could remove up to 95% of the colour from kraft whole mill effluent. Flocculation with the lignin derivatives was more efficient at low pH. These materials were less efficient for colour removal than aluminum sulphate.
Activation energy and other thermodynamic parameters for the diffusion of surfactant cations through a sodium bentonite membrane
Authors: Srivastava Suresh K.
Published: July 2010

The diffusion of surfactants, cetyl pyridinium bromide, dodecyl pyridinium bromide and cetyl trimethyl ammonium bromide through sodium bentonite membrane has been measured. It has been found to take place via exchange sites of the membrane and the permeability decreases with increase in size of the cation. The energy and entropy of activation, enthalpy and free energy change of the process have been calculated and the permeability has been explained in terms of these thermodynamic parameters.
Reactions of benzene and ammonia in a continuous‐flow microwave discharge reactor
Authors: Brooks Brian W. , Spearot Rebecca M.
Published: July 2010

Gaseous mixtures of benzene and ammonia have been passed through a continuous‐flow microwave discharge reactor. The principal reaction products were hydrogen cyanide, hydrogen, nitrogen and acetylene. Aniline and butadiene were produced in smaller amounts. At a pressure of 4 × 10−2 bar, no reaction occurred unless the molar ratio of ammonia to benzene exceeded 1 : 1. At 9.3 × 10 −2 bar, no reaction occurred unless the reactant ratio exceeded 2:1. The presence of nickel wire affected the distribution of reaction products. The conversions of benzene were less than those which had previously been found in pure benzene. The maximum conversions of ammonia were much higher than the conversions obtained in pure ammonia. The consumption of both benzene and ammonia were found to be zero order rate processes. The consumption rates of the reactants varied linearly with power absorption in the reactor.
The nature of pseudoboehmite and its role in the crystallisation of amorphous aluminium hydroxide
Authors: Bye G. C. , Robinson J. G.
Published: July 2010

Pseudoboehmite samples were prepared by ageing the amorphous hydroxide obtained by the hydrolysis of aluminium s‐butoxide using water or aqueous ethanol. Further ageing resulted in the formation of a mixture of crystalline trihydroxides. The two re‐crystallisation stages are accompanied by similar but opposite changes in the volume of the aqueous suspension but pseudoboehmite can only be identified by X‐ray diffraction in a separated xerogel. Crystallinity of the latter was shown to be enhanced by preparation in 80% ethanol but at concentrations providing only a little more than the water needed for hydrolysis of the alkoxide a new modification of pseudoboehmite was observed.

X‐ray line broadening and displacement indicated that it possessed an even greater degree of lattice strain than exists in the common form. The composition and specific surface of a number of pseudoboehmite xerogels suggest that the major part of the water, in excess of that in the basic structures AlOOH, is present in a surface monolayer with a minor amount responsible for lattice strain.
A study of asphalt‐aggregate interactions using inverse gas‐liquid chromatography
Authors: Barbour F. Alan , Barbour Richard V. , Peterson J. Claine
Published: July 2010

Aggregate surfaces were shown to interact strongly with many i.g.l.c. test compounds having chemical functional groups similar to those believed present in asphalt.

Asphalt refers to the binder in road mixes. In many countries the binder is referred to as bitumen.

I.g.l.c. and infra‐red spectroscopy showed that fractions in the asphalt containing the more polar functional groups exhibited the stronger interaction with the aggregate surface. Asphaltenes separated by pentane show a reduced interaction of polar groups with the aggregate, probably because of agglomeration of the asphaltene molecules. Oxidation of the asphalt fractions produced polar functional groups which interacted strongly with aggregate surfaces. Aggregate surfaces were found to catalyse the oxidation of the more non‐polar fractions. Their catalytic effect on the more polar fractions is unknown. Of the two aggregates tested, limestone was found to interact more strongly than quartzite with the asphalt fractions, although quartzite was a more effective oxidation catalyst for the more non‐polar fractions. Carboxylic acids were found to be a major component formed on oxidation that is strongly adsorbed on the limestone surface.
The fermentative production of gentamicins by Micromonospora purpurea
Authors: Abou‐Zeid Abou‐Zeid A. , El‐Wahab Abd , Eissa I. , Salem Hassan M.
Published: July 2010

For fermentative production of gentamicins by Micromonospora purpurea it was necessary to adjust the initial pH value of the medium to 7.0–7.5. Glucose was the preferred carbon source. The production of gentamicins was performed in two steps. The first step was to grow the microbial cells and the second step was to inoculate the fermentation medium with the growing cell culture (6.0% v/v). The organism produced more antibiotic with organic nitrogen sources than with inorganic nitrogen source.

Fodder yeast (50 and 40% total nitrogen) was a good nitrogen source both for microbial growth and the antibiotic production. The suitable concentrations of fodder yeast (50 and 40%) were 2 and 6 g/1 respectively.
The preparation of an immobilised glucose isomerase II. Immobilisation and properties of the immobilised enzyme
Authors: Kent C. A. , Emery A. N.
Published: July 2010

Glucose isomerase ex Lactobacillus brevis was successfully immobilised on microcrystalline cellulose, using the transition metal‐link method. Immobilisation could be performed over a pH range of 5 to 9, and usually resulted in an apparent specific activity increase.

The immobilised glucose isomerase generally displayed properties similar to those of the soluble enzyme, with the exception of the following differences:

a pH optimum at pH = 6, an acid shift of 0.5 units on immobilisation;

an optimum reaction temperature at 50 °C, lower than that for the soluble enzyme;

on incubation at 4 °C, a retention of 53% of the initial specific activity, when stored in 0.02 M, pH = 7, Tris buffer, after 8 weeks, compared with an apparent activation of the soluble enzyme after 10 and 19 weeks' storage.

Storage properties of the immobilised enzyme at 4 °C in Tris were apparently improved by the presence of Mn++ and Co++, although associated with some protein release. Storage at 4 °C in water alone, as opposed to Tris, resulted in a more rapid activity loss.
The kinetics of anaerobic digestion of farm wastes
Authors: Hobson Peter N.
Published: July 2010

The conversion of animal excreta and similar feedstocks to biogas in single‐stage, continuous‐flow anaerobic digesters running in steady‐state conditions can be described in terms of undegradable material and hydrolysis and fermentation of two solid components plus conversion of acid and hydrogen plus carbon dioxide to methane. These reactions, while linked in provision of substrates for the different bacterial groups, can be regarded as separate continuous‐cultures, each with one limiting substrate, but with nitrogen in excess. The substrate utilisations can then be described by simple kinetic equations applicable to bacterial growth in pure‐culture chemostats. The degradation of solids is the overall rate‐limiting reaction and the use of two biodegradable solids, distinguished more by particle size than by chemical composition, explains some apparent anomalies in solids degradation and gas production at different retention times. While the general principles apply to any waste, the values of constants used in the equations depend on the solids in a particular feedstock. Temperature effects on digestion are explained by using a recently‐suggested formula for modification of the maximum growth rates of the bacteria with temperature. This distinguishes between mesophilic and thermophilic digestions. Inhibitory effects of ammonia and high input solids concentrations can also be described by modification of maximum bacterial growth rates.
The use of sugar cane stillage for single cell protein production
Authors: Cabib Gustavo , Silva Humberto J. , Giulietti Ana , Ertola Rodolfo
Published: July 2010

Stillage from cane molasses alcohol for SCP production was used for the growth of strains of Candida and Paecilomyces as SCP sources. The results of small and large scale experiments carried out with a Candida utilis strain with data on chemical composition, amino acid profile, vitamin content and biological value of the cell material are given.
A tubular bioreactor for photosynthetic production of biomass from carbon dioxide: Design and performance
Authors: Pirt S. John , Lee Yuan Kun , Walach Marek R. , Pirt Margaret Watts , Balyuzi Hushang H. M. , Bazin Michael J.
Published: July 2010

A theory of photobioreactor design is developed. A photobioreactor was constructed in the form of a loop made from 52 m of glass tubing of 1 cm bore; the loop covered about 0.5 m2. The culture was illuminated with mercury halide lamps to reproduce sunlight. Computer control was used to maintain constant biomass concentration. The influence of radiation on the reactor temperature is quantitatively predicted. An air lift system was preferred to a liquid pump for culture recycle. The energy required for culture recycle in the loop with Reynolds number 2000 was 0.6 W m−2. The CO2 gas/liquid transfer rate achieved was sufficient to meet the maximum possible demand with solar irradiation. The O2 gas/liquid transfer rate was sufficient to meet the maximum respiration demand at night. The maximum algal biomass concentration achieved exceeded 20 g dry weight litre−1. A biomass concentration of 8 g dry weight litre−1 was found to be convenient for normal operation. The maximum uptake of light in the available wavelength range (400–700 nm) was 38 W m−2, this corresponds to utilisation of solar irradiation up to 89 W m−2. Below the maximum light uptake rate the efficiency of storage of light energy in the biomass corresponded to 16.6% of solar energy.
Computer control of an algal bioreactor with simulated diurnal illumination
Authors: Walach Marek R. , Balyuzi Hushang H. M. , Bazin Michael J. , Lee Yuan Kun , Pirt S. John
Published: July 2010

Design details are presented for the construction of a microcomputer based system to measure and control the growth of an algal population in a continuous‐flow bioreactor. Diurnal variation in the light intensity was simulated by computer control of a Venetian blind placed in front of the solar lamps. An indirect method of biomass estimation was based on balancing the amount of nitrogen (NH3) in and out of the system. The computer‐control system held the algal biomass at a constant concentration while fluctuations in CO2 partial pressure, turbulence and light intensity occurred. Under diurnal illumination, CO2 assimilation began without lag when illumination started, although there was a lag before ammonia utilisation began.
Invertase immobilised on activated clay: Properties and kinetic study
Authors: López‐Santín J. , Solà C. , París J. M. , Caminal G.
Published: July 2010

Invertase was immobilised on activated ball clay. The immobilised enzyme showed maximum activity at pH 4.8–6. The thermal deactivation was significant at temperatures above 30°C. The kinetics of sucrose hydrolysis with free invertase showed substrate and product inhibition. Immobilised enzyme kinetics followed the same mechanisms. Modelling curves were plotted to explain the experimental results. The thermal deactivation followed first order kinetics. The characteristics of thermal deactivation of immobilised enzyme were studied in the range 25–50°C.
Detoxification of cyanide by immobilised fungi
Authors: Nazly Naheed , Knowles Christopher J. , Beardsmore Andrew J. , Naylor William T. , Corcoran Eugene G.
Published: July 2010

Cyanide detoxification was studied by immobilisation of fungal mycelia that had been induced to form cyanide hydratase (formamide hydrolyase) which is able to hydrolyse cyanide to formamide. The fungal pathogens of cyanogenic plants, Stemphylium loti, Gloeocercospora sorghi and Fusarium moniliforme were immobilised using polyelectrolyte flocculating agents. The effect of immobilisation on the enzymic properties of S. loti and G. sorghi were investigated. The apparent Km values increased from 21.0 mmol and 25.5 mmol KCN to 43.5 mmol and 71.0 mmol KCN, respectively. The pH profile for the two enzymes widened on immobilisation. The stoichiometry of 1:1 cyanide utilisation to formamide formation was retained on immobilisation, with complete conversion of 70 mmol KCN in 120 min by 0.12 g dry wt of S. loti and in 6 min by 0.13 g dry wt of G. sorghi. When the two fungi were stabilised by immobilisation, and tested in column reactors containing 1.2 g dry wt of S. loti and 1.3 g dry wt of G. sorghi, they completely converted cyanide (70 mmol; added continuously at 7.5 ml h−1) into formamide for 2 days and 30 days, respectively. Stability was enhanced by inclusion of 1.0 mmol glucose in the 70 mmol KCN solution, by a further 10 h for S. loti and an extra 10 days for G. sorghi. Operational stabilities of immobilised G. sorghi (1.3 g dry wt) and F. moniliforme (1.0 g wet wt) in column reactors, with 100 % cyanide conversion, at varying flow rates was investigated. G. sorghi was stable for 15, 10 and 2 days whereas F. moniliforme was only stable for 48, 20 and 10 h at 30, 60 and 120 ml h−1 flow rates respectively.
Mechanistic aspects of biotransformations by the monooxygenase system of Methylosinus trichosporium OB3b
Authors: Jezequel S. G. , Higgins I. J.
Published: July 2010

Mechanistic aspects of the mode of action of the soluble monooxygenase system of Methylosinus trichosporium OB3b have been investigated. The hydroxylation of 4‐deuteroanisole in the 4‐position was shown to proceed via an NIH shift with a deuterium retention of 66 %, indicative of an epoxide intermediate. Isotopic studies using ethylbenzene and ethylbertzene‐d10 showed an isotopic effect, kH/kD = 4.5 for benzylic hydroxylation, and an inverse isotopic effect, kH/kD = 0.75 for arene hydroxylation. It is suggested that a stepwise mechanism (hydrogen abstraction and hydroxylation) could be involed.
Production and purification of a maltose‐producing amylase from Bacillus subtilis IMD 198
Authors: Fogarty William M. , Bourke Edward J.
Published: July 2010

A strain of Bacillus subtilis (IMD 198) isolated from peat degraded starch to maltose with little production of glucose and other products. Highest levels of enzyme were achieved in a salts medium containing soya bean meal and starch. The enzyme was purified by precipitation with isopropanol, adsorption on calcium phosphate gel and fractionation on DEAE‐and CM‐cellulose ion‐exchange resins. The latter chromatographic procedure removed a contaminating activity that produced dextrins as end‐products from starch or amylose. The action pattern of the purified, major enzyme activity indicates that it may be β‐amylase.
Analysis of process dynamics in bioreactors
Authors: Meiners Marinus , Rapmundt Werner , Wania Wolfgang , Gleis Joachim , Isernhagen Rolf
Published: July 2010

The dynamic behaviour of bioreactors was analysed by means of experimental process identification using correlation analysis with pseudo‐random binary input signals (PRBS) for excitation of the process. Agitation speed and airflow were used as input signals. The correlation with oxygen partial pressure in the liquid and oxygen and carbon dioxide concentrations in the exhaust gas were calculated. Results of the computation are: degree of a linear differential equation and coefficients of the equation, which can then be used to design adaptive controllers. The dead time of the system can be found by comparing the least squares of different models. The variation of the parameters during process time are shown for a low order adaptive controller.
Bioprotein production from the waste products of olive oil extraction
Authors: Karapmar M. , Worgan J. T.
Published: July 2010

After the expression of the oil from olive fruits, two principal residues, namely the press‐cake and the vegetable water (black liquor), remain. These by‐products of olive processing have little economic significance, despite studies carried out to evaluate them.1‐4 In this study, growth of Aspergillus oryzae, Aspergillus niger, Sporotrichum pulverulentum and Trichoderma viride on the solid waste was examined in shake flasks. The press‐cake contains a proportion of tissue which is resistant to microbial attack. Microbial growth on the original solid waste was poor and did not decrease the cellulose content appreciably, even after alkali treatment. Therefore the press‐cake was milled in a hammer mill and larger particles were separated by sieving. The protein content of the product was about 19–24%, and about 52% of the cellulose present in the sieved residue was degraded.
Extraction of proteins from shrimp processing waste
Authors: Bataille Marc P. , Bataille Pierre F.
Published: July 2010

Up to 70% of the theoretical protein content of shrimp waste was recovered by a boiling water extraction method. Digestion time, volume and concentration of calcium hydroxide were varied to optimise the yield of dry matter recovered on processing the shrimp waste. Amino acid analysis was carried out to characterise the protein content of the dry matter.
Kinetics of the methanogenic fermentation of acetate
Authors: Powell Godfrey E. , Hilton Martin G. , Archer David B. , Kirsop Brian H.
Published: July 2010

The kinetics of methanogenesis from a stirred batch‐fed calcium acetate enrichment culture have been studied. A detailed kinetic analysis of the culture allowed four distinct phases to be distinguished. Phase 1 was a period of very rapid increase (from low initial values) in the rate of methanogenesis upon addition of acetate, and was not thought to be associated with cell growth. In Phase 2 the rate of methanogenesis increased exponentially with time reflecting exponential growth. Phase 3 was characterised by an approximately constant rate of methane production, and is discussed in relation to the uncoupling of growth and methanogenesis. Phase 4 is a period of rapid decline associated with depletion of acetate. The apparent size of the population of the acetate‐utilising methanogenic bacteria subsequently declined, with a specific decay constant of 0.4 ± 0.1 d−1. The significance of these phases, in particular 2 and 3, for industrial anaerobic digestion is discussed.
The hydrolysis of xylan by Cellulomonas preparations
Authors: Daly Jan M. , Švejkar Marc , Rickard Pamela A. D.
Published: July 2010

Thin layer chromatography was demonstrated as an effective technique for observing the time course of hydrolysis of a substituted xylan (arabinoxylan) by crude preparations of Cellulomonas. The chromatograms revealed a sequential pattern of appearance of xylooligomers and arabinoxylooligomers, with early appearance of relatively large oligomers and subsequent accumulation of xylobiose and (to a lesser extent) xylose and arabinose. The pattern indicated that the dominant enzymic activity towards arabinoxylan is that of an endoxylanase.
Electron‐transfer coupling in microbial fuel cells. 2. performance of fuel cells containing selected microorganism—mediator—substrate combinations
Authors: Delaney Gerard M. , Bennetto H. Peter , Mason Jeremy R. , Roller Sibel D. , Stirling John L. , Thurston Christopher F.
Published: July 2010

Various phenoxazine, phenothiazine, phenazine, indophenol and bipyridilium derivatives were tested for their effectiveness as redox mediators in microbial fuel cells containing Alcaligenes eutrophus, Bacillus subtilis, Escherichia coli, or Proteus vulgaris as the active biological agent, and glucose or succinate as the oxidisable substrate. A ferricyanide‐Pt cathode was used. The open‐circuit cell e.m.f.′s increased in the order of increasing negative formal redox potentials at pH 7(E7m) of the redox compounds. Several of the redox agents worked well as mediators, maintaining steady currents over several hours, and thionine was found to be particularly effective in maintaining relatively high cell voltages when current was drawn from the cell. A number of the compounds tested did not function well, either because they were incompletely or slowly reduced by the microorganisms or because of their instability. P. vulgaris, with thionine as mediator and glucose as substrate, showed the best performance in a fuel cell. This system was examined in some detail under various conditions of external load to establish the effects of organism concentration, mediator concentration, and substrate addition. Coulombic outputs from these cells were calculated by integration of the current‐time plots. Coulombic yields of 30–60% were obtained, on the basis of (theoretical) complete oxidation of added substrate to CO2 and water.
Growth kinetics of non‐competitive product inhibition in batch cultures
Authors: Powell Godfrey E.
Published: July 2010

This paper develops the kinetics of a substrate‐limited batch culture of bacteria subject to non‐competitive product inhibition. The equation of growth is solved exactly. The expression which represents, growth is shown to consist of the sum of three terms. These correspond to three successive phases: exponential in near‐optimal conditions, linear growth which reflects product inhibition and finally decelerating growth arising from substrate depletion. The extent and distinguishability of the three phases is dependent on the relative values of the growth parameters.
Increased enzyme activity in immobilised cell composites with a highly hydrophilic polymer matrix
Authors: Kumakura Minoru , Kaetsu Isao
Published: July 2010

Streptomyces phaeochromogenes cells were immobilised by radiation polymerisation of hydrophilic monomers; highest levels of glucose isomerase activity were found in immobilised cell composites with highly hydrophilic polymer matrices. The enzyme activity in the composites from the copolymerisation of hydroxyethyl acrylate (or methacrylate) and N‐vinyl‐2‐pyrrolidone monomer increased markedly with increase in the content of the N‐vinyl‐2‐pyrrolidone monomer, owing to the higher water absorption by the polymer matrix, and was close to that of the non‐immobilised cells. The enzyme activity was affected by monomer concentration, the hydrophilicity, and chemical structure of the polymer matrix. The Michaelis constant of the composites from hydrophilic monomers was close to that of the intact cells.
An automatic ATP monitor for activated sludge characterisation
Authors: Van Esbroeck H. , Schram E. , Vereecken J.
Published: July 2010

A continuous process control apparatus for the determination of ATP in biomass was developed for monitoring activated sludge quality in biological wastewater treatment plants. The determination of ATP was based on the firefly luciferase reaction. The extraction efficiency of ATP removal from the biomass, influence of extractant on bioluminescence and potential for automation were tested during optimisation procedures. During the operation of a laboratory scale bioreactor, the automatic ATP analysis system provided a rapid and reproducible monitor of the biomass. It was a sensitive detector of inhibitory effects in the bioreactor and proved an excellent ‘toxicity monitor’.