bluuebunny/crossref_metadata_2025 huggingface dataset:
The reduction of ilmenite with carbon
Authors: Wouterlood Huibert J.
Published: July 2010

The reduction of natural and pre‐oxidised ilmenite with carbon at temperatures between 1173 and 1473 K (900–1200°C) was studied. The reaction was carried out in the atmosphere produced by the gaseous reaction products and the degree of reduction was determined from the CO and CO2 contents of the product gas, as measured by chemical absorption and continuous infrared analysis. Solid reaction products were analysed chemically, by X‐ray diffraction and by magnetic balance. The reaction was found to consist of a fast first stage representing the reduction of ferric to ferrous iron, and a slower second stage in which ferrous iron was reduced to metallic iron. A change in reaction mechanism, leading to retention of iron in solid solution in the reaction product, was shown to be promoted by high temperatures and/or the presence of Mn and Mg solute impurities. The applicability of various reaction models to the experimental data is discussed.
A thermodynamic method based upon the theory of regular solutions for selection of solvents and process conditions for aromatics extraction
Authors: Mukhopadhyay Mamata
Published: July 2010

Selectivity and distribution coefficients are two important parameters required for selection of solvents and process conditions for efficient separation of aromatics from a multi‐component hydrocarbon feedstock. A simple thermodynamic method is presented in this paper for the prediction of these parameters from a knowledge of physical properties of the pure components, such as vapour pressure, molar volume and critical temperature. The activity coefficients were calculated using the solubility parameter theory extended to multi‐component mixtures of polar and nonpolar components. The compositions of the extract and raffinate phases were computed using an iterative search technique for simultaneous solution of the thermodynamic criterion equations and the material balance equations for each component. For testing the validity of this method, the predicted values of the selectivity at infinite dilution and the equilibrium phase compositions were compared with the corresponding experimental values from the literature and the agreement is found to be highly satisfactory.
A study of the rate of sedimentation of magnesium hydroxide obtained from sea water
Authors: Petric Bartul , Petric Nedjeljka
Published: July 2010

A study has been made of the influence of incomplete precipitation on the rate of sedimentation of magnesium hydroxide obtained from sea water with the use of the following flocculants: Flocculant‐B (polyacrylamide) and slag from Fe—Cr of a high carbon content. Incomplete precipitation of magnesium ions from sea water considerably affected the rate of sedimentation of magnesium hydroxide. The rate of sedimentation increased considerably and thus the capacity of the thickener was also increased. At a precipitation of 80%, the capacity of the thickener increased by 86.5% in relation to complete precipitation. Calculations were made according to Kynch's theory. The above procedure leads to a substantial reduction in the content of calcium salt in the product, which can be explained by the law of adsorption, as set out by Paneth, Fajans and Hahn. For optimal conditions of sedimentation, a mathematical expression of the dependence of the quantity of the flocculant, ‘Flocculant‐B’ on the degree of completeness of precipitation was determined.
The reduction of sulphur dioxide by carbon monoxide on a La0.5Sr0.5CoO3 catalyst
Authors: Hibbert D. Brynn , Tseung Alfred C. C.
Published: July 2010

The semiconducting perovskite oxide, La0.5Sr0.5CoO3, is a catalyst for the reduction of sulphur dioxide by carbon monoxide. Unlike aluminia‐supported metal catalysts, La0.5Sr0.5CoO3 tolerates high levels of oxygen in the gas stream if sufficient carbon monoxide is present to react with all the oxygen. Water vapour (2%) does not adversely affect the reaction; unwanted byproducts H2S and COS are reduced for contact times less than 0.25 s. A computer model is used to predict equilibrium gas compositions for systems containing oxygen and water vapour. During the reaction the catalyst itself reacts with sulphur producing metal sulphides, possibly of simple cubic structure. The perovskite sulphides LaCoS3 and La0.5Sr0.5CoS3 are theoretically unstable.
Origin of porosity in titania gels. I. Microporous and mesoporous gels prepared from titanous chloride and ammonia
Authors: Ragai Jehane , Sing Kenneth S. W. , Mikhail Raouf
Published: July 2010

Titania gels were prepared by oxidation of precipitates of hydrous TiIII oxide obtained at different pH values from aqueous titanous chloride by the addition of ammonia. The gels were dried at 110–120°C (383–393 K) and their surface properties were characterised by nitrogen adsorption at 196°C (77 K). The nitrogen isotherms have been analysed by the BET and αs‐methods. Gels prepared at pH values of 3.30, 5.01, 6.20 and 7.10 were all mesoporous; the pore volume increasing with increase of pH, over the range studied. The gel prepared at pH 2.30 had a small micropore volume, whereas the gel prepared at pH 5.01 and aged for 6 months in water had a much larger micropore volume. The formation of the mesopore structure appears to be due to a condensation‐polymerisation process associated with the creation of hydroxo and oxo bridges between neighbouring Ti3+ ions. If stabilising ligands (H2O or NH3) are allowed to remain attached to the cations, the condensation‐polymerisation process is retarded and microporosity results.
The photosynthetic efficiency of Chlorella biomass growth with reference to solar energy utilisation
Authors: Pirt S. John , Lee Yuan‐Kun , Richmond Amos , Pirt Margaret Watts
Published: July 2010

The photosynthetic efficiency (PE) of a growing algal culture was determined from the growth yield (Y), that is, biomass produced/light absorbed and the calorific value of the biomass (k); PE = kY. To obtain the maximum photosynthetic efficiency the algae were grown in light‐limited chemostat cultures in urea‐mineral salts media plus CO2 and steady‐states were obtained at different specific growth rates. With a given light input the biomass output rate was independent of the specific growth rate up to at least 70% of the maximum specific growth rate. The photosynthetic efficiency was independent of the incident light intensity over the range studied, 5.3–21.3 W m−2. The light source had a spectral range of 400–700 nm and its mean wavelength was assumed to be 575 nm. The values of the maximum growth yields (YG, g dry weight kJ−1) were 0.0153 for the Sorokin Chlorella strain 211/8k and 0.0206 for a newly selected mixed culture MA003 which consisted of an alga and three species of heterotrophic bacteria. The maintenance energy (m) of the mixed culture MA003 was in the range 0–0.32 kJ g−1 dry weight h−1 and the specific maintenance rate (mYG) was in the range 0–0.0066 h−1. In Chlorella strain 211/8k the maximum PE was 34.7% which corresponds to a quantum demand (n) of 6.6 per O2 molecule evolved. In the mixed culture MA003 the maximum PE was 46.8% with 95% confidence limits, 42.7–51.5. This PE value corresponds to a quantum demand (n) of 4.8 per O2 molecule evolved. These results call in question the current model of photosynthesis which predicts that the maximum PE with absorbed light of mean wavelength 575 nm should not exceed 29% and the minimum quantum demand, n = 8. From our results with culture MA003 it is deduced that the maximum practicable storage of total solar energy by algal biomass growth in vitro is 18%.
The production of chlorate with a bipolar pump cell
Authors: Ghoroghchian Jamal , Jansson Robert E. W.
Published: July 2010

Chlorate has been produced in a system consisting of an electrochemical pump cell (space‐time ∼ 150 ms) and a holding volume. The overall current efficiency has been determined as a function of ratio of tank:cell volume, electrolyte concentration and applied voltage, and the interaction of the electrochemical and chemical reactions investigated. At low applied voltages the reduction of dispersed and dissolved oxygen provides an alternative counter reaction to the more normal evolution of hydrogen, although only at low current densities on graphite. Space‐time yields range from 0.52 to 8.76 mol h−1 dm−3 at energy yields of 2.65 to 7.59 kW h kg−1.
Active carbons from almond shells as adsorbents in gas and liquid phases
Authors: Linares‐Solano Angel , De D. López‐González Juan , Molina‐Sabio Miguel , Rodriguez‐Reinoso Francisco
Published: July 2010

Almond shells have been used as raw material to prepare activated carbons. The preparation conditions, by direct activation of the raw material with CO2 or air, or by activation after carbonisation under nitrogen, have been compared in respect to the percentage burn‐off and the adsorptive properties of the resulting carbons. It is shown that direct activation with CO2 in the temperature range 1023–1173 K (750–900°C) gives activated carbons with similar or larger surface areas than those obtained by the conventional method (carbonisation followed by activation). On the other hand, the results show the role played by the particle size of the carbonised products on the adsorptive properties of the activated carbons prepared from them. Activation with air (in the temperature range from 573 to 673 K) does not produce carbons with large surface areas, but the yield is large and this could be of practical interest. The adsorption of methylene blue and phenol, both in aqueous solution, has allowed further comparison of the adsorptive properties of the activated carbons. In all, the direct activation with CO2 seems to be a very good way to prepare activated carbons from almond shells; they can be favourably compared with commercial activated carbons, two of which have been used in this study.
Synthesis of 4,4′‐aryldihydrazono‐3‐(3′‐pyridyl)‐2‐pyrazolin‐4,5‐diones and 1‐aryl‐3‐(3′‐pyridyl)‐4,4′‐arylbisazo‐5‐aryliminopyrazoles and their application as disazo disperse dyes. Part II
Authors: Amer Fathy A. , Afsah El‐Sayed , Soafan Mamdouh
Published: July 2010

3‐(3′‐Pyridyl)‐2‐pyrazoline‐4,5‐dione 4,4′(4,4′‐biphenylenedihydrazone and p‐phenylenedihydrazone) and its derivatives (IIa‐e, IIIa‐e) were obtained by the coupling reaction of tetrazotised benzidine and p‐diamonobenzene with 3‐(3′‐pyridyl)‐2‐pyrazolin‐5‐ones (Ia‐e). Similarly, bis‐azo compounds containing pyrazole nucleous as, 1‐aryl‐3‐(3′‐pyridyl)‐4,4′‐arylbisazo‐5‐aryliminopyrazoles (VIa‐i and VIIa‐i) were prepared by the interaction of the corresponding chloro compound (IV and V) with aromatic amines. The compounds so obtained (II, III, VI and VII) are used as disazo disperse dyes for dyeing polyester fibres fast yellow‐orange shades. Their fastness properties towards washing, rubbing, acid‐alkaline perspiration and light were investigated.
Selectivity and reactor analysis for parallel electrochemical reactions
Authors: Sakellaropoulos George P. , Francis Gary A.
Published: July 2010

A methodology is outlined for the analysis of multiple parallel electro‐organic reactions of arbitrary, simple electrode kinetics on solid or porous electrodes, in the absence and in the presence of slow mass transport processes. The analysis is further used to predict the selectivity and rate of two model electrochemical reactors under potentiostatic, channel plug‐flow or complete mixing. The product yield of both reactors depends strongly on the electrode potential, with reductions of low transfer coefficients favoured by positive, electrogenerative potentials. Channel flow reactors result in non‐uniform rate, current and selectivity distributions and exhibit apparent limiting currents before the onset of slow mass transport. With multipath competing reactions or in the presence of slow external transport, both reactors are amenable to maximisation of desirable product yields.
Mechanism of the photofading of Dye. Contribution of singlet oxygen in the catalytic fading of anthraquinone dye mixtures
Authors: Kuramoto Nobuhiro , Kitao Teijiro
Published: July 2010

The mechanism of the catalytic fading of some dyes has been investigated. The relative fading of quinophthalone in solution increases when C.I. Disperse Red 15 was added. The mechanism of catalytic fading proceeds via the singlet oxygen mechanism, since this phenomenon is suppressed by adding singlet oxygen quencher as DABCO or nickel dimethyldithiocarbamate (NMC). However, when quinophthalone mixed with C.I. Disperse Blue 14 was irradiated under the same conditions (λ > 520 nm), no catalytic fading occurred. Competitive photo‐oxidation experiments for these dyes with NMC, giving evidence for intermediacy of singlet oxygen by the self‐sensitised process, were carried out. The relative rate constants for reactions in solution were examined to predict the possibility of the catalytic fading in these dye mixtures.
Investigation on the textural characteristics of supported nickel hydrogenation catalysts
Authors: Srinivasan Ganapthy , Murthy Ramaraju Sreerama , Kumar Kallambella M. Vijaya , Kamat Prashant V.
Published: July 2010

Nickel catalysts supported on a range of carriers such as kieselguhr, silica, γ‐alumina, silica‐alumina and mordenite were investigated in order to gain an understanding of their structural properties. The surface area and pore distribution characteristics of the carriers and unreduced catalysts obtained from nitrogen adsorption isotherms gave strong indications that the formation of the nickel salt submerged the carrier. Metallic nickel produced after reduction at high temperature was perhaps present in the macropores or on the outer surface of the carrier forming a microporous network of fine crystallites. The metal surface area of the catalyst in its reduced state, calculated from hydrogen chemisorption data, was not influenced by the specific surface area of the carrier. Among the different carriers, the nickel‐carrier interaction was mainly found with kieselguhr and silica. Activity of the different catalysts in the hydrogenation of unsaturated fatty acid was found to be directly related to the metal area.
Preparation of gelatinous aluminium hydroxide by urea from aqueous solutions containing chloride, nitrate and sulphate of aluminium
Authors: Sato Taicho , Ikoma Shuji , Ozawa Fusaji
Published: July 2010

The preparation of gelatinous aluminium hydroxide from aqueous solutions containing a mixture of the chloride, nitrate or sulphate of aluminium and urea by heating at 95°C has been investigated under different conditions. The pH value of aqueous solutions, on heating for a given period of time, gradually increases, rises steeply at pH 4.0–7.5 and finally approaches a constant value. The precipitate appears at about pH 7 in the presence of chloride or nitrate ions and about pH 4 in the presence of sulphate ions. Although the gelatinous precipitates in the chloride and nitrate systems are apparently different from the granular, filterable one in the sulphate system, their compositions are not influenced by the species of aluminium salt. The fresh precipitates exist in an amorphous state, and go to pseudoboehmite by ageing. It seems that the amount of pseudoboehmite increases as the concentration of aluminium salt in aqueous solution decreases. However, the transformation from amorphous aluminium hydroxide to pseudoboehmite is reduced in the presence of sulphate ions. Furthermore, it is found that the X‐ray diffraction peak for the (200) plane, as an orthorhombic structure, in the pseudoboehmite precipitated from chloride or nitrate solution is more intense than that from sulphate solution.
Performance of electrolysis with two‐phase electrolyte. The trickle electrode for the electrochemical conversion of substances with low solubility in aqueous electrolytes with special respect to electrochemical extraction processes
Authors: Feess Hans , Wendt Hartmut
Published: July 2010

The electrochemical conversion of organic substances with low solubility in water which yield ionic products can be performed in aqueous electrolytes, as the main medium for the ionic charge transfer, by dissolving the organic depolariser in a nonaqueous solvent and conducting the electrolysis at the organic solvent‐electrode interface. Polarity of this second phase, as well as good contact between organic phase and working electrode are essential. The anodic oxidation of ferrocene dissolved in organic solvents (preferentially methylene chloride) to ferricinium salts was chosen as a model system to study the conditions of this type of two‐phase electrolyte electrolysis. Experiments with single CH2Cl2‐droplets on smooth nickel anodes covered by an aqueous electrolyte show that the most important parameters which govern the anodic conversion of ferrocene are: (a) electrical conductivity supplied to the organic phase by the anodically‐produced ferricinium salt; (b) small difference in surface tensions at the electrode‐organic phase interface and the electrode‐aqueous phase interface; and (c) direction and magnitude of the Galvani potential difference at the aqueous‐organic interface. Quantitative studies on the influence of the different parameters were performed at a well‐defined and stationary three‐phase boundary. The results were used for the construction of a trickle cell with particulated horizontal working electrodes (nets, perforated plates etc.) which offers the possibility for continuous processing of two‐phase liquid‐liquid electrolytes. Such electrodes show excellent mass and charge transfer characteristics and can be used for simultaneous electrochemical conversion of a neutral depolariser and extraction of its ionic conversion‐product out of the organic solvent into the aqueous electrolyte (electrochemical extraction).
Segregated flows in model cells
Authors: Marshall Rodney J. , Jansson Robert E. W.
Published: July 2010

The flow of an electrolyte in a parallel channel electrochemical reactor has been simulated in a simple Perspex flow channel, operating at Reynolds numbers between 20–1000. Age distribution information was obtained by the marker‐pulse technique and analysed with the aid of various simple mathematical models of the flow. It was found that the flow appeared to be segregated and that, in particular, electrogenerated species were retained for long periods in the vicinity of the electrode. Regression was performed in both the time domain and Laplace plane and the effect of experimental noise on the accuracy of the results was estimated. Fitting in real‐time was found to be inherently less sensitive to noise than fitting in the Laplace plane. Data are given for the highly structured flow within a model of an Mg‐AgCl sea water battery as well as for channel flow.
Porosity of alumina gels prepared from solutions of aluminium nitrate in various alcohols
Authors: Cormack Brian , Freeman John J. , Sing Kenneth S. W.
Published: July 2010

Mercury porosimetry and nitrogen adsorption measurements have been made on a series of alumina gels prepared by the passage of gaseous ammonia into solutions of aluminium nitrate nonohydrate in various alcohols. The values of surface area calculated from mercury intrusion curves and nitrogen isotherms (BET method) are in reasonable agreement with the macroporous gels, but the restricted penetration of mercury into the mesopore structures results in larger values of areas when calculated by nitrogen adsorption. Marked differences have been obtained in the pore size distribution of gels prepared in various alcohols, including the isomers of propanol and butanol. The alcohol appears to play a double role: (a) by replacing water at the solid‐liquid interface (it promotes aggregation‐cementation); (b) by decreasing the solubility (it reduces the rate of Ostwald ripening). Propan‐1‐ol and propan‐2‐ol tend to promote aggregation‐cementation and hence the formation of a well‐defined mesopore structure, whereas butan‐1‐ol and heptan‐1‐ol appear to favour particle growth and the development of larger pores.
The kinetics of the gaseous extraction of gallium from mica
Authors: Gesser Hyman D. , Vaidya Om , Baldwin W. George , Chow Arthur , Bock Ernest , McBride David W.
Published: July 2010

The gaseous reduction of gallium in white mica has been studied using natural gas as the reducing gas. From a study at three temperatures, the initial extraction was observed to be linear with time and independent of particle size. The results suggest that delamination of the mica lattice is important. The measured activation energy for the loss of gallium from the white mica is 184 × 21 kJ mol−1.
Simple and rapid spectrophotometric and titrimetric methods for the determination of ascorbic acid in pharmaceutical preparations
Authors: Aly Mohamed M. , Hassan Moustafa K. , Souliman Rafat M.
Published: July 2010

Ascorbic acid in pharmaceutical preparations can be determined by either spectrophotometric or titrimetric methods by its reaction with ferricinium trichloroacetate at pH 3. The latter is quantitatively reduced to ferrocene. This is extracted by chloroform and its concentration calculated from the absorbance at 440 nm. Alternatively, an aqueous solution of ascorbic acid is titrated with that of the blue ferricinium salt which acts as an indicator. Vitamins, minerals, hormones, dextrose and coloured additives do not interfere with the reaction. Both methods are simple, rapid and sensitive.
Activated sludge wastewater treatment— stoichiometric relationships
Authors: Sherrard Joseph H.
Published: July 2010

A mathematical procedure based on biokinetic and stoichiometric principles is presented as a basis for modelling biological wastewater treatment process systems. An example problem is formulated and solved to illustrate the utility of the model. Important process relationships are presented graphically.
Vapour pressures, molar entropies of vaporisation and liquid‐state conformation of alkoxides
Authors: Thomas Leo H. , Smith Harry , Davies Gwyn H.
Published: July 2010

The vapour pressures of eight alkoxides (of carbon, silicon and boron) are reported, together with the molar entropies of vaporisation deduced therefrom. These data, along with those previously reported for 11 other alkoxides, are correlated by a simple equation containing only two adjustable parameters. The entropy values, which are substantially higher than the Trouton ‘constant’, are explained in terms of molecular parallelism of stretched flexible chains.
Biochemical basis of free and immobilised enzyme applications in industry, analysis, synthesis and therapy
Authors: Wiseman Alan
Published: July 2010

Biotechnological use of enzymes has been started with cheap enzymes in soluble form, which were chosen from those that do not require the expense of added cofactors. These simple uses have been mainly in food industry applications, often for hydrolytic purposes in order to improve a process or product. Purified enzymes are finding application in analysis, including immunoassay, stereospecific synthesis and in therapy. In these cases, however, much more enzymological knowledge is needed to understand and control the use of the soluble or immobilised enzyme form. It is the appreciation of enzyme structure‐mechanism relationships that is essential to progress. This, and the control of enzyme stability, as determined by changes in protein conformation and aggregation, is of the greatest importance for the ultimate goal of designing new and better enzymes and enzyme analogues.
Magnetic adsorbents: Properties and applications
Authors: Dixon David R.
Published: July 2010

Magnetic adsorbents which are capable of selectively removing impurities of low molecular weight from a food process stream without reducing the nutritional value of the product have been prepared by the methods described. The procedure has been tested by Kraft Food Ltd for a product derived from yeast cells, where it is essential to remove bitter‐tasting isohumulones without removing the valuable proteins and nucleic acids. The handling properties of the magnetic material allow ready separation of the saturated adsorbent from other suspended solids inevitably present in the process stream, prior to regeneration and reuse.
Ion flotation and solvent sublation of cobalt cyanide complexes
Authors: Walkowiak Władysław
Published: July 2010

An experimental investigation into the batch ion flotation of cobalt complex anions with the cationic surfactant, cetylpyridinium chloride is described. The concentration ratio of cetyl‐pyridinium: cobalt in the foam was determined and found to be 2.0–2.7 for CoCl2 plus KCN solution and 3.0–3.3 for K3[Co(CN)6] solution. Spectroscopic measurements of the former anion show that mainly [Co(CN)5H2O]2‐ anions were floated. The [Co(CN)6]3‐ flotation was established in the presence of Cl−, Br−, I−, CN−, NO3− and SO42‐ anions. The accelerating influence of the ion flotation produced by the presence of Cl−, Br−, I−, CN−, NO3− and SO42‐ increased as their partial molal volume increased. The solvent sublation of [Co(CN)6]3‐ anions was established in the presence of these anions.
Catalytic oxide coatings on ceramic supports
Authors: Unger Klaus K. , Engler Martin , Krys Siegfried , Inacker Otto , Plog Carsten , Seidl Max
Published: July 2010

Thin porous oxide coatings composed of Al2O3, SiO2, TiO2 and ZrO2, respectively, on ceramic carriers have been produced by either a wash‐coat procedure or by liquid coating followed by solidification. By dehydration and calcination of the supported ceramics the pore texture was stabilised. The thickness of the layer, its homogeneity, specific surface area, porosity and pore volume distribution have been shown to be controlled by the properties of the oxides deposited, and by the conditions of the coating procedures. On the basis of the results obtained, it is evident that porous oxide layers can be prepared with tailor‐made and desired properties. The procedures described also permit the incorporation of catalytic components (e.g. CuO) into the layer.
Basic characteristics and applications of a silica derived by flame hydrolysis. XX. Dust‐free handling of solid materials in powder form with extremely low bulk densities
Authors: Ferch H. , Schmitz W.
Published: July 2010

Powders of small particle size and low bulk density find widespread use. Methods of handling must minimise their release into the atmosphere so as to reduce environmental and health implications. These methods are considered in detail here.
Cyclohexane dehydrogenation kinetics on a platinum‐rhenium/aluminium oxide catalyst with hydrogen and inert diluents
Authors: Susu Alfred A. , Enoh Felix E. , Ogunye AyöDele F.
Published: July 2010

The dehydrogenation of cyclohexane to benzene on a platinum‐rhenium/aluminium oxide (Pt‐Re/Al2O3) catalyst was investigated using both pulse and continuous flow techniques with hydrogen and inert (N2, He, Ar) diluents at the following conditions: 1 and 4 atm (1 atm = 101 kPa) total pressure and 432–623 K. Experiments performed with hydrogen as a carrier in the pulse mode showed anomalous behaviour as cyclohexane conversion was observed to increase with pulse size/pulse width and decrease with temperature and contact time. The dehydrogenation reaction was first‐order with respect to cyclohexane for both the pulse and continuous flow experiments. Lower activation energies were observed for the inert carriers; activation energies were between 37.7–54.4 kJ mol<−1 for inert diluents. With a hydrogen carrier, the activation energies were found to be 87.9 and 121.3 kJ mol−1 for T<553 K and <553 K, respectively. The difference in activation energy between hydrogen and the inert carriers was attributed to a change in mechanism on the coked catalyst surface. Surface conversion of cyclohexane to adsorbed cyclohexane was the slowest step in a hydrogen carrier. For the inert carriers, it was postulated that surface diffusion of adsorbed intermediate for for subsequent conversion was rate determining.
Elimination of ethanol inhibition of yeast growth by a multistream ethanol feed in a multistage tower fermenter
Authors: Páca Jan
Published: July 2010

The effect of several types of ethanol feed into a multistage tower fermenter, under conditions of oxygen supply rate limitation, on growth and physiological activity of the yeast Candida utilis was studied. The measurements were made at steady states of continuous culture for single values of dilution rate, temperature and pH in all stages of the fermenter and with a constant total sum of ethanol supplied. It was found that the type of ethanol feed significantly affects both the economic parameters associated with biomass production and the cell physiology in the individual stages of the fermenter.
Studies on the extraction of aromatics with sulpholane and its combination with thiodiglycol
Authors: Rawat Bachan S. , Gulati Indar B.
Published: July 2010

Liquid—liquid equilibria for the systems: toluene—heptane—sulpholane, toluene—heptane—sulpholane plus thiodiglycol at 40°C, and benzene—heptane—sulpholane plus thiodiglycol and benzene—heptane—sulpholane plus 9% water at 110°C have been studied. The results of the combined solvents have been compared with those obtained with sulpholane containing up to 9% water. Several advantages of combined solvents are discussed. The selectivities of the mixed solvents for different hydrocarbon types have been calculated from the limiting activity coefficients determined by gas chromatography.
The use of Caenorhabditis elegans for anthelmintic screening
Authors: Simpkin K. Graham , Coles Gerald C.
Published: July 2010

Caenorhabditis elegans maintained on ampicillin‐treated Escherichia coli has been found to be sensitive to the benzimidazole anthelmintics, albendazole, cambendazole, fenbendazole, flubendazole, mebendazole, oxfendazole, oxibendazole, parbendazole, thiabendazole and the non‐benzimidazoles, avermectin B1a, bitoscanate, febantel, levamisole, morantel, nitroscanate, oxantel, phenothiazine, pyrantel, pyrvinium pamoate, rafoxanide and stilbazium iodide at concentrations of 50 μg cm−3 or less. It can therefore be used in a high through‐put in vitro pre‐screen for anthelmintics. It is suggested that C. elegans may also be useful for evaluating the mode of action of drugs and the mechanism of resistance of nematodes to anthelmintics.
Synthesis of some new diarylsulphides and diarylsulphones containing a quinazol‐4‐one moiety
Authors: Abbady Mahmoud A. , Ali Morsy M. , Kandeel Maymouna M.
Published: July 2010

4‐Amino‐4′‐nitrodiphenylsulphide and 4‐amino‐2′‐nitrodiphenyl sulphide (I) were smoothly condensed with 2‐methyl‐3,1‐benzoxazin‐4‐one (II) to produce the corresponding 2‐methyl‐3‐diphenylsulphidoquinazol‐4‐ones (III). 2‐Styryl‐3‐diphenylsulphidoquinazol‐4‐ones (IV) were prepared by heating III with the appropriate aromatic aldehydes using piperidine as a basic catalyst. Compounds IV oxidised easily in a hydrogen peroxide‐glacial acetic acid mixture to produce the corresponding sulphones (V). The constitution of some of the prepared products is discussed in the light of their infrared and ultraviolet spectra. The biological activities of some of these compounds were tested.
Development of a correlation between the non‐polar solubility parameter, refractive index and molecular structure. I. Aliphatic hydrocarbons
Authors: Wingefors Stig , Liljenzin Jan‐Olov
Published: July 2010

For non‐polar liquids (e.g. the alkanes) the cohesion energy density (λ2) can be shown to be a function of the refractive index (nD), molal volume (V) and molecular structure according to:

where Δ is the non‐polar solubility parameter and the increments gij are determined from molecular structure. The difference between values of Δ calculated by this formula and experimental data is <0.1% for the C5–C16 n‐alkanes and <0.8% for the C5–C8 branched isomers. The main object of this correlation was to provide a method for estimating the London dispersion force contribution to the cohesive energy of branched polar liquids.
Production of citric acid by submerged fermentation. Effect of medium sterilisation at pilot‐plant level
Authors: Chopra Charanjit L. , Qazi Ghulam N. , Chaturvedi Surya K. , Gaind Chand N. , Atal Chand K.
Published: July 2010

In large‐scale fermenters, in situ sterilisation takes a long time and there is probably thermal degradation of the medium constituents, the products of which generally affect the final yield. Sterilisation cycles were designed according to the microbial load in the broth and their effect on the production of citric acid studied in 4‐m3 fermenters. It was found that the medium could tolerate Del values up to 48 against a calculated value of 35.50. Above this value there was thermal degradation of the medium constituents which adversely affected the morphology of the fungus Aspergillus niger, and consequently the citric acid yields.
Control of the production of cephamycin C and thienamycin by Streptomyces cattleya NRRL 8057
Authors: Lilley Gerald , Clark Anne E. , Lawrence Gordon C.
Published: July 2010

Batch and continuous flow chemostat cultures were used to analyse the effect of environment and specific growth rate on thienamycin and cephamycin C production by Streptomyces cattleya NRRL 8057. Thienamycin was shown to be a phosphateregulated product, optimally produced in phosphate‐limited cultures. In batch culture, antibiotic production started as phosphate was exhausted in the medium. In phosphate‐limited chemostat culture, optimal production occurred at low dilution rates and low specific rate of phosphate utilisation. Synthesis was severely repressed in phosphate‐sufficient cultures irrespective of the specific growth rate. In contrast, the growth rate, rather than the nature of the limitation, was a major controlling factor in regulating cephamycin C production. Production of this antibiotic occurred, optimally at low specific growth rates, irrespective of whether phosphate, nitrogen or carbon were limiting the cultures. It was therefore concluded that cephamycin C production could be regulated by phosphate, nitrogen or carbon‐mediated control. Ammonium nitrogen was shown to be more repressive than nitrate nitrogen. Collectively the data emphasised the significance of the growth‐limiting substrate and the specific growth rate on the production of these β‐lactam antibiotics.
Physico‐chemical properties of by‐product gypsum
Authors: Beretka Julius , Crook Douglas N. , King George A.
Published: July 2010

Four samples of by‐product gypsum were analysed by chemical and physical methods and subjected to comparable degrees of calcination in a special rotary furnace. The hydration characteristics of the resulting calcium sulphate hemihydrates were determined in terms of three basic parameters viz. α0, a measure of heterogeneous nucleation in the system; k, a measure of self‐acceleration of the reaction; and θ, the period of induction. Measurements were made of the size distribution of particles, pH, water requirement, the colour and compressive strength of cast gypsums made from the hemihydrates, and comparisons were made with two samples of calcined natural gypsum. Additions of calcium oxide were also made to the by‐product gypsums and the same procedures followed. Hydration of the calcined products resulted in considerable differences in the kinetic parameters. Both differences in nucleation and transport of calcium sulphate from the grains of hemihydrate to the growing crystals of the dihydrate seemed to contribute to variations in reactivity. The by‐product gypsums calcined alone, or in the presence of calcium oxide, yielded hemihydrates with water requirements greater than those of the calcined natural gypsums. The compressive strengths of cast gypsums made from these hemihydrates were somewhat less than those made from the calcined natural gypsums. The colour co‐ordinates were about the same. After treatment with calcium oxide, the by‐product gypsum appears to be suitable for making plaster of Paris.
The preparation of thiophenes. III. From aromatic compounds and carbon disulphide
Authors: Azizian Farid , Pizey James S.
Published: July 2010

The high‐temperature, vapour‐phase reaction of carbon disulphide with 2‐isopropyl‐phenol and with o‐methylbenzyl alcohol in the presence of various catalysts gave high yields of 3‐methylbenzo[b]furan and dihydrobenzo[c]thiophene, respectively.
The preparation of 5‐chloromethylfurfuraldehyde from high fructose corn syrup and other carbohydrates
Authors: Szmant H. Harry , Chundury Deena D.
Published: July 2010

A 92–95% conversion of high fructose corn syrup (HFCS) or crystalline D‐fructose to 5‐chloromethylfurfuraldehyde (CMF) was achieved using 300 mol% of concentrated hydrochloric acid in chlorobenzene, under a nitrogen atmosphere, a reaction temperature of 75°C and a reaction time of 1–2 h. Constant high‐speed stirring was essential for high yields and purity of CMF. Inferior yields of CMF were obtained from glucose and starch. Saccharine, phenyl sulphone and thiuronium derivatives were prepared and characterised. The use of surfactants did not improve the yields of CMF.
The measurement of effective substrate diffusities within whole cell suspensions using a diffusion‐limited hollow fibre reactor
Authors: Webster Ian A. , Shuler Michael L.
Published: July 2010

An immobilised whole cell membrane reactor system is described which permits estimation of effective substrate diffusivities within whole cell suspensions. The reactor unit uses a membrane to separate the cell slurry from the nutrient solution (e.g. an artificial kidney hollow fibre dialyser). Whole cells are pumped into the shell side of the unit and clamped off. Substrate solution makes one pass through the dialyser tube side at a flow rate such that its conversion over the complete reactor does not exceed 10%. Under such conditions the reactor operates differentially; previously published mathematical expressions being used in evaluating the effective substrate diffusivity, once η (the effectiveness factor) is determined. The value of η can be estimated readily from the true reaction rate (in the absence of diffusional limitations) and the experimentally observed reaction rate. A hypothetical example is presented. The advantages and disadvantages of the method are discussed.
Effect of aeration and pH on gramicidin S production by Bacillus brevis
Authors: Vandamme Erick J. , Leyman Dirk , De Visscher Patrick , De Buyser Dirk , Vansteenkiste Ghislain
Published: July 2010

Although the biosynthesis of the antibiotic gramicidin S (GS) by Bacillus brevis ATCC 9999 has been studied extensively, almost no attention has been given to environmental control of its fermentation process. In this respect, GS fermentations conducted in a 7.5 dm3 fermentor in complex (YP) medium revealed that a high aeration rate resulted in a high biomass yield (12 g DCW dm−3) with very low GS levels (170 mg GS dm−3). Lowering the aeration rate (5 dm3 air min−1 at 300 rev min−1) caused a dramatic increase in GS formation (2100 mg GS dm−3) and comparable but slower biomass formation. In chemically‐defined (F3/6) medium fermentations, an aeration rate of 5 dm3 air min−1 at 300 rev min−1 was apparently too high as only 0.104 mg GS mg−1 DCW was produced. A much lower aeration rate (2 dm3 air min−1 at 250 rev min−1) was needed to arrive at a higher specific antibiotic level: 0.130 mg GS mg−1 DCW. These data seem compatible with the finding that oxygen is known to inactivate the GS‐synthetases. Furthermore, keeping the pH constant at 7.3 under low aeration conditions increased specific GS production up to 0.220 mg GS mg−1 DCW in YP, as well as in F3/6 fermentations. Both environmental pH and dissolved oxygen tension clearly affect growth pattern, growth extent and GS production in these high yielding media. These data stress the importance of controlling pH and aeration rate during GS fermentations.
The increase in intracellular free‐lysine levels of growing Baker's yeast (Saccharomyces cerevisiae) by sodium chloride
Authors: Tanner Robert D. , Richmond L. Daniel , Wei Chia‐Jenn , Woodward Jonathan
Published: July 2010

Fermentation by baker's yeast was carried out in medium containing exogenously added sodium chloride. The cell, intracellular free‐lysine, glucose and ethanol concentrations were monitored at intervals of time during the fermentation. Sodium chloride (0.15–0.6M) stimulated the maximum intracellular free‐lysine concentration of baker's yeast. The greatest stimulation was observed using 0.6M sodium chloride and was accompanied by a reduction in the rate of glucose uptake from the medium and a lowering of the ethanol concentration in the medium.
The dynamics of anaerobic phenol biodegradation in lower greensand
Authors: Rees John F. , King John W.
Published: July 2010

The anaerobic biodegradation of phenol in the unsaturated zone beneath landfill sites has been simulated by percolating an artificial landfill leachate containing phenol through columns of disturbed Lower Greensand. The columns were inoculated with microbes from a laboratory‐scale landfill simulator. Phenol degradation was observed at concentrations up to 8.2 g dm−3 but decomposition was increasingly inhibited above 3.0 g dm−3. Maximum rates of decomposition were observed at concentrations between 1.5 and 3.0 g dm−3. The Vmax value at a flow rate of 0.5 cm3 h−1 was 1.05 g dm−3h−1 and the Km value was 450 mg phenol dm−3. Zero‐ (r0) and first‐order (r1) rate constants increased with increasing flow rate. The data are used to calculate the rates of phenol degradation which might be obtained in real landfill.
Coke formation during cracking of hydrocarbons. I. The effect of pre‐sulphiding on coke formation on a nickel‐chromium‐iron alloy under steam cracking conditions
Authors: Trimm David L. , Holmen Anders , Lindvag Odd
Published: July 2010

Studies have been carried out on the effect of pre‐sulphiding a nickel‐chromium‐iron alloy on coke formation under steam cracking conditions. Pre‐sulphiding has no great effect on the gaseous product spectrum as long as some sulphur is present, but the coking rate is dependent on the amount of sulphur pre‐deposited. Small amounts of sulphur reduce the coke formation, but the coking rate increases with increasing amounts of pre‐deposited sulphur. As the sulphur content increases still further, coke formation passes through a maximum. A tentative explanation of these observations is advanced in terms of the effect of metal sulphides on the established mechanism of coke formation. Initial sulphiding is suggested to increase grain boundary penetration by coke and to result in the accumulation of iron sulphide on the surface. Eventually this may act to seal off grain boundaries, thereby inhibiting further coke formation.
Fundamental aspects of lead extraction and stripping by a liquid ion exchange reagent
Authors: Hoh Ying‐Chu , Wang Wei‐Ko
Published: July 2010

LIX 34 liquid ion exchange reagent was introduced commercially by General Mills in 1976. The fundamental aspects of lead extraction and stripping using LIX 34 as the organic extractant in acetic solution has been studied here. Equilibrium isotherms for extraction and stripping, isothermal pH effects, temperature effect, loading capacity and the rate of extraction and stripping on the system Pb2+‐HAc‐LIX 34—Kermac 470B are reported.
The kinetics of reduction of selenious(IV) ions in hydrochloric acid with sulphur dioxide
Authors: Chiu Tai‐Ming , Hoh Ying‐Chu , Wang Wei‐Ko
Published: July 2010

The reduction of selenious ions to its elemental state has been found to be a function of selenious ion concentration, solution acidity, gas flow rate and temperature. The rate equation can be written as:

where α = −1/2, β = 1, γ = 0.9, E = −53 411 kJ kg−1mol−1, R = 8314 kJ kg−1 mol−1 K−1 and k0 = 194. The reaction temperature starts to decrease when the conversion rate reaches a maximum. This observation can be used to determine the end of the reaction.
Some aspects of homogeneous and two‐phase aromatic sulphonation
Authors: Sohrabi Morteza , Kaghazchi Tahereh
Published: July 2010

The two‐phase sulphonation of benzene and toluene with concentrated sulphuric acid solutions at 30°C has been studied in a continuous stirred tank reactor (1.06 dm3 capacity). The rates of reaction, as a function of sulphuric acid concentration and the overall mass transfer coefficient times, and the interfacial area per unit volume of the acid phase as a function of agitation speed, have been determined. In homogeneous systems, the kinetic rate constants and the relative rates of sulphonation of a series of aromatic hydrocarbons have been measured in the range of 13–16 mol dm−3 sulphuric acid. It has been shown that the rates of sulphonation of compounds, with levels of reactivity beyond that of m‐xylene, are likely to be affected by diffusional phenomena.
Influence of oxygen and medium conditions on the performance of a tower reactor with an external loop
Authors: Buchholz Heinrich , Luttman Reiner , Zakrzewski Wolfgang , Schügerl Karl
Published: July 2010

Hansenula polymorpha was cultivated using ethanol and/or glucose as substrate in a bubble column, air lift, loop reactor. The optimum aeration rate was determined for extended culture operation. Considerable influence of the ethanol concentration on the volumetric mass transfer coefficient (kLa), and the specific gas‐liquid inter‐facial area (a) was found. Glucose concentration had no comparable influence on kLa and a. The influence of lack of substrate and/or dissolved oxygen on the culture was investigated. For 30 min the absence of substrate did not influence μm, whereas a lack of dissolved oxygen for 2.5 min reduced μm to one half of its original value.
Smoke—the hazard, the measurement and the remedy
Authors: Skinner G. A.
Published: July 2010

Methods of smoke analysis and suppression are reviewed in detail.
Examination and standardisation of amine titration in surface acidity measurements of silicas, aluminas and synthetic zeolites
Authors: Unger Klaus K. , Kittelmann Udo R. , Kreis Wilfried K.
Published: July 2010

The amine titration method using Hammett and arylmethanol indicators has been examined on selected samples of porous silica, active alumina and synthetic zeolites. On the basis of the successive approximation technique the evaluation of surface acid strength distribution has been standardised. A new method has been developed to assess the total acidity without employing indicators. The distinction between Bronsted and Lewis acidity through measuring the Ho and HR acidity distribution function on aluminas and zeolites is shown to be erroneous. The acidity is strongly affected by the size of amine and by the density of surface acid centres—as demonstrated on a series of silicas and on synthetic zeolites. The size dependence can be utilised to detect the acidity of distinct pore size ranges within a given porous solid. Under certain conditions the acidity measurements can be correlated with those obtained from other techniques such as heterogeneous exchange and infrared spectroscopy.
Coalescence phenomena in liquid‐liquid systems
Authors: Austin D. G. , Jeffreys G. V.
Published: July 2010

The factors affecting phase separation of liquid dispersion are discussed in order to identify the parameters controlling the coalescence processes occurring in primary and secondary dispersions. Models for the estimation of wedge length and band thickness in gravity settlers are reviewed, and the trends in future studies in the design and analysis of this type of equipment introduced. The phase separation of dispersions in packed beds is also considered, and the effects of the properties of the packing and the system on the coalescence processes occurring in the packing analysed. The importance of the system properties, packing voidage and the exit drop mechanism on the design of a packing for a phase separation operation are emphasised. Some recent results explaining the increased coalescence rate at the junction between a high energy and low energy surface are presented. In addition, some recent work in these laboratories on the separation of secondary dispersions are also presented.
Synthesis of 5‐hydroxymethyl‐2‐furancarboxaldehyde catalysed by cationic exchange resins. Part 3. Kinetic approach of the D‐fructose dehydration
Authors: Mercadier Daniel , Rigal Luc , Gaset Antoine , Gorrichon Jean‐Pierre
Published: July 2010

The best conditions for the production of 5‐hydroxymethyl‐2‐furancarboxaldehyde (HMF) in an ion exchange resin‐water‐solvent triphasic system have been determined using static operating conditions.