bluuebunny/crossref_metadata_2025 huggingface dataset:
Strain improvement in antibiotic‐producing microorganisms
Authors: Normansell Ian D.
Published: July 2010

In the context of commercial strain development for improved antibiotic production it is important to stress the efficiency and practicability of the procedures used. Typical constraints are the novelty of the microorganism, time and manpower. Established and more novel techniques applied to strain improvement can be divided into the induction of beneficial alterations and the screen for and recognition of such altered mutants. Recent advances have contributed mainly to the former of these two divisions. The empiricism of mutagenesis can be removed as more is known about mutation induction with respect to repair phenomena. Mutagens must be assessed for efficiency with rapid test systems for forward and reverse mutation. Enhanced mutation frequencies can be achieved with repair‐deficient mutants or chemical inhibitors of repair processes. It is widely accepted that recombinational methods are an important part of strain development although published examples of its successful application are rare. Parasexuality in asexual fungi and protoplast fusion in both bacteria and fungi facilitate recombination and therefore the construction of improved strains. As a result of these advances it has become necessary to deviate from the classical, linear mutation and selection programmes. The application of recombinant DNA technology to strain development is undoubtedly promising. In the field of antibiotic research this approach may necessitate extensive basic research before its potential can be realised. Major constraints may be poor knowledge of both the biosynthesis of the antibiotic and the genetic systems in the producing microorganism. It will also be necessary to develop suitable vector systems. This approach clearly consumes time and resources which are important considerations in commercial terms. The ability to recognise and isolate improved mutants is just as important as their production and again time and efficiency is paramount. Shake‐flask screening has been central to most programmes although its format may be changing to accommodate multiline screens to capitalise on recombination techniques. Its major limitation as a primary screen is in the work involved in testing a comparatively small number of strains. To circumvent this problem many laboratories are miniaturising screens or moving towards ‘plate‐based’ screens in which colony productivity is assessed on agar. Plate screens also permit less empirical screening procedures such as reversion of mutants impaired in antibiotic production or the use of chemical inhibitors of antibiotic biosynthesis. This approach has the advantage of allowing large numbers to be screened as well as providing information of a biosynthetic nature if the mutants and inhibitors are subject to investigation in their own right.
Environmental factors influencing the growth of animal cells in culture
Authors: Birch John R. , Cartwright Terence
Published: July 2010

An analysis is made of environmental factors controlling growth rate and maximum population density of cultured mammalian cells. Three factors may limit maximum population density: accumulation of an inhibitor, exhaustion of essential nutrients or availability of surface for growth. Whilst the significance of inhibitors is uncertain, examples are given of nutrient exhaustion limiting maximum population density. Growth of anchorage‐dependent cells is influenced by both available surface area and by the physicochemical properties of the surface. Finally examples are given of ways in which environmental terms may interact, often in complex fashion, to modify cell growth.
Cultivation of anchorage‐dependent cells and their applications
Authors: van Wezel A. L.
Published: July 2010

A short review and evaluation of the various cultivation systems for anchorage‐ dependent cells is given. From the cultivation systems presently available the micro‐carrier culture system might be considered to be the most suitable system for large‐scale cultivation of these cells. Beside its high potential for scaling up and control of environmental conditions, it has the advantage of easy separation of cells and culture medium. This facilitates medium changes either batch‐wise or continuously. For continuous refreshment the sieve for retaining the beads with cells in the fermenter should be built on the stirrer shaft in order to avoid blocking.
Hydrogenation of benzene to cyclohexene on a ruthenium catalyst: Physical and chemical characterisation of the catalyst and its precursor
Authors: Ingemar Odenbrand C. U. , Andersson S. Lars T.
Published: July 2010

The chemical and physical characteristics of a ruthenium catalyst used in the hydrogenation of benzene to cyclohexene has been investigated. The active catalyst consists of metallic ruthenium obtained by hydrogen reduction of the precursor suspended in the alkaline aqueous phase. The precursor consists of hydrous oxides of ruthenium with a surface area of 27 m2 g−1. After reduction the surface area increases to 112 m2 g−1 and a drastic change in pore‐size distribution occurs. The average pore diameter decreases from 28 to 13 nm and the number of pores < 8 nm increases substantially. The macroscopic particle size, in the range 25–40 μm, decreases along with the decreasing ruthenium concentration. Poisoning of the catalyst by corrosion products, mainly hydroxides of iron and chromium, is also discussed.
On the importance of dimension variation in determining the limiting steps in adsorption kinetics
Authors: Kärger Jörg , Bülow Martin , Ulin Vladimir I. , Voloshchuk Albert M. , Zolotarev Pavel P. , Kočiřik Milan , Zikánová Arlette
Published: July 2010

Information about the limiting processes in adsorption kinetics can be obtained by an analysis of the shape of the uptake curves (first and second statistical moments M1 and M2) as well as by an analysis of the dependence of the adsorption time constants on the radii (R) of the adsorbing particles. The sensitivity of these dependences on the various models of adsorption has been investigated by introducing the factors M12/M2 and d ln M1/d ln R. d ln M1/d ln R‐2 is shown to be a reliable criterion for diffusion‐limited adsorption. From the shape of M12/M2 no corresponding criterion can be derived.
Study of multicycle melting and freezing of sodium thiosulphate pentahydrate
Authors: Stunić Zlatko , Djuričković Veljko , Majstorović Slobodan , Buljan Vlado
Published: July 2010

The behaviour of sodium thiosulphate pentahydrate in the course of repeated use as a heat‐storing medium can be predicted, cycle by cycle, on the basis of a generalised phase‐transition equation adapted for incongruently melting material. An indice is derived for this purpose and named ‘coefficient of true phase‐transition reversibility’. Its predictive value is shown for three additional incongruently melting materials well known as heat‐storing media: CaCl2.6H2O, Na2SO4.10H2O and the mixture Na2SO4.10H2O + 2/3NH4Cl + 2/3NaCJ.
Synthesis and biological activity of new β‐lactam and thiazolidinones containing a sulphanilamide moeity
Authors: Hassan Khairy M. , El‐Shafei Ahmed K. , El‐Kashef Hussein S. , Mashaly Mohamed M.
Published: July 2010

Some new sulpha drugs containing both β‐lactam and/or thiazolidinone moieties have been prepared. The biological screening of the prepared compounds has been carried out on some strains of pathogenic bacteria. It is clear that these compounds have a different mechanism of action other than that already known for the sulpha drugs.
Electrochemical treatment of effluents from adipic acid plants
Authors: Cox David A. , El‐Ghaoui Elias A. , Ellis Keith G. , Jansson Robert E. W. , Meissner Dieter
Published: July 2010

Electrochemical measurements have been made on the system Cu2+‐adipic acid‐HNO3 (which models the effluent from adipic acid plants) to investigate the reasons for the observed low current efficiency for copper deposition from such solutions. The most probable cause is a cathodic shift in the deposition potential of copper making the reduction of NO3− the preferred process. Depletion experiments have been carried out on real effluent in two three‐dimensional cells, a bipolar trickle tower and a porous reticulated carbon bed. Each performs reasonably well and, while the current efficiencies are low (c 20%), the deposition is essentially mass‐transfer controlled.
Syntheses of dihydrolavandulol and its related compounds from carboxylic acids and conjugated dienes
Authors: Fujita Tsutomu , Watanabe Shoji , Suga Kyoichi , Miura Toshiro , Sugahara Kotoji , Kikuchi Hajime
Published: July 2010

5‐Methyl‐2‐isopropyl‐4‐hexenoic acid, dihydrolavandulic acid (III), was synthesised in 65% yield from 3‐methylbutanoic acid and isoprene with sodium naphthalenide in the presence of N,N,N′,N′‐tetramethylethylenediamine. Reduction of III with lithium aluminum hydride gave 5‐methyl‐2‐isopropyl‐4‐hexen‐l‐ol, dihydrolavandulol (IV) (85% yield). Oxidation of IV with pyridinium chlorochromate gave 5‐methyl‐2‐isopropyl‐4‐hexenal, dihydrolavandulyl aldehyde (V) (81 % yield).
Polarographic reduction of some oxazolones at the dropping mercury electrode
Authors: Fahmy Hussein M. , Daboun Hamed A. , Hussein Mona M , Elnagdi Mohamed H.
Published: July 2010

The polarographic behaviour of a series of 4‐arylidene‐2‐phenyl‐2‐oxazolin‐5‐one derivatives over a wide range of pH is reported and discussed. A mechanism for the electrode process is elucidated and confirmed via isolation and characterisation of electrolysis products.
Hydrogen‐gas production with Citrobacter intermedim and Clostridium pasteurianum
Authors: Brosseau James D. , Zajic J. E.
Published: July 2010

Citrobacter intermedius and Clostridium pasteurianum were grown in 14‐dm3 batch reactors on glucose and measured for biomass and H2 production. Gas production with C. intermedius was found to be growth related, whereas that with C. pasteurianum was entirely produced during the stationary phase of growth. The maximum yield and productivity of H2 with C. intermedius was 60% H2 or 1 mol of H2 mol−1 of glucose at a maximum of 3.7 mmol of H2 h−1 and 85% H2 or 1.5 mol of Ha mol−1 of glucose at a maximum of 9.0 mmol of H2 h−1 with C. pasteurianum. The overall H2 productivity (QH2) was 2.5 mmol of H2 h−1 g−1 dry biomass for C. pasteurianum at a glucose concentration of 7.6 g dm−3. As the glucose concentration was increased from 7.6 to 15.4 g dm−3, up to 44% of the gas produced with C. pasteurianum was growth associated. The remainder of the gas was produced in the stationary phase. In this case the overall Ha productivity (QH2) was 1.2 mmol of H2 h−1 g−1 dry biomass. The comparative experiments indicate that maximum yields and rates of H2 production were achieved with C. pasteurianum.
Effect of some aromatic hydroxy sulphonic acids on uptake of acid dyes by nylon 6
Authors: Guthrie John , Cook Christopher C.
Published: July 2010

The major constituents of a synthetic tanning agent for leather, prepared from the condensation of a naphthol sulphonic acid with formaldehyde, have been separately synthesised and have been shown to be of low molecular weight. The effect of these ‘syntan components’ on the uptake of four acid dyes by nylon 6 has been studied as has the desorption of the agents during the uptake of dye. Although the components have only a minor effect on the rate at which dye is adsorbed by the fibre, they reduce the extent to which dye is taken up at equilibrium. The restraining effect observed is governed by the affinity of both dye and agent. It is concluded that unlike commercial syntans which are available for the aftertreatment of dyed nylon, the products studied diffuse readily into the polymer matrix and, after application to nylon, are not held firmly at the fibre surface.
Crystallisation of pentaerythritol. III. Impurity distribution coefficients
Authors: Simons Terrence J. , de Silva Rohan L. , Creasy Dennis E.
Published: July 2010

Commercially available pentaerythritol usually contains di‐pentaerythritol, a formal and formaldehyde as impurities. The distribution coefficients of these impurities were measured on crystallising pentaerythritol from aqueous solution at temperatures of 30, 50 and 70°C. It was found that di‐pentaerythritol did not co‐precipitate with pentaerythritol. The formal readily co‐precipitates and crystallisation will only yield purification if carried out above 90°C. Purification from formaldehyde was achieved readily and only at temperatures below 10°C should the product be less pure. The free energy of the transfer was found to be approx.‐40 kJ mol−1 in both cases.
Effect of trace impurities on calcium sulphate precipitation
Authors: Sarig Sara , Mullin John W.
Published: July 2010

Induction periods for the precipitation of CaSO4.2H2O in the concentration range 0.05‐lM have been determined by the stopped‐flow method utilising changes in the solution conductivity after nucleation and growth. The measured induction periods were insensitive to calcium sulphate concentration, suggesting that the nucleation process was heterogeneous. At first additions of Al3+ increasingly prolonged the induction period, but above a certain Al3+ concentration further additions caused the induction period to reduce again. Tentative explanations based on the poisoning of growth sites by [Al(H2O)6]3+ complexes for the first effect and the deaquation of aluminium complexes followed by formation of polymeric species for the second are given. It is suggested that the small crystallites which appeared on the surfaces of the gypsum crystals precipitated in the presence of relatively high fluoride concentrations are CaF2.
Effects of biocide and nutrient availability on microbial contamination of surfaces in cooling‐water systems
Authors: Miller P. C. , Bott T. R.
Published: July 2010

The results of an evaluation of the effects of different factors on formation, growth and removal of biological films are reported. Experiments have been performed both on laboratory equipment and a test system located on a cooling‐water system at an industrial site.

The effects of temperature, nutrient availability and surface material of construction are discussed in relation to film formation. Experiments concerning continuous biocide treatment are assessed in relation to biofilm removal. A pure culture of Pseudomonas fluorescens was used to grow biological films in the laboratory under identical hydrodynamic conditions but at different temperatures. Drastic reductions in film thickness were noted at temperatures 5°C above and below the optimum temperature for growth of the organism. The effects of nutrient loading under similar hydrodynamic conditions have been studied in the laboratory. The maximum biofilm thickness was reduced by 55% when no air was present and by 80% when neither air nor nutrient were supplied. Biofilm growth at the industrial site was unexpectedly more pronounced on brass than mild steel. Examination of destruction of existing biofilms in the laboratory showed that at a concentration of 4 parts 10−‐6 free chlorine (sodium hypochlorite) the initial rate of film removal was four‐to‐six times higher than that at 2.5 parts 10−‐6 free chlorine. A higher velocity of sodium hypochlorite solution over the biofilm resulted in a higher rate of removal. The results are discussed in the light of published data in related tests.
A comparison of Nylon‐66‐supported platinum and palladium catalysts for the hydrogenation of 1‐octyne in the liquid phase
Authors: Bowden Colin , McLellan Richard J. , Macdonald Ronald P. , Winterbottom John M.
Published: July 2010

A number of Nylon‐66 fibre‐supported platinum (Pt) catalysts were prepared by refluxing solutions of ammonium chloroplatinite with Nylon‐66 fibres. The resulting Pt‐Nylon‐66 catalysts were used for the hydrogenation of 1‐octyne in n‐propanol and n‐heptane at 70°C and 1 atm. total pressure. They, like their palladium (Pd) counterparts, exhibited solvent sensitivity in respect of their selectivity for 1‐octyne production. However, both activity and selectivity trends, as metal concentration increased, were different from those exhibited by Pd‐Nylon‐66 catalysts. Pd‐Nylon‐66 catalysts gave an activity maximum, whereas Pt‐Nylon‐66 catalysts did not, activity increasing with metal concentration. Both catalysts gave constant selectivity, independent of metal concentration in n‐heptane (Pd‐Nylon‐66 = 0.99–1.00; Pt‐Nylon‐66=0.75–0.76).

In n‐propanol Pd catalysts gave high selectivity (0.99–1.00) for low metal concentrations. Pt‐Nylon‐66 catalysts exhibited the opposite tendency, giving low selectivity (0.46–0.50) at low metal concentrations and higher selectivity (0.75–0.76) at high metal concentrations. It is concluded that, whereas Pd‐Nylon‐66 catalysts exist as some form of Pd(II) complex over a wide concentration range, Pt‐Nylon‐66 only exists as a complex at low concentrations and becomes predominantly zero‐valent (metallic) Pt supported on the Nylon‐66 at higher concentrations.
Sorption of caesium by complex hexacyanoferrates: II. X‐ray crystallography and mössbauer spectroscopy of sodium‐copper cyanoferrates (II)
Authors: Bennett B. A. , Shahbandeh M. R. , Streat M.
Published: July 2010

X‐Ray diffraction patterns and Mössbauer spectra of sodium‐copper cyanoferrate(II) (NaCuFC) before and after incorporation of caesium atoms have been studied. The positions of the X‐ray reflections and the symmetry of the Mössbauer spectra suggest that NaCuFC has a cubic lattice structure which remains cubic as caesium atoms are introduced. Calculations based on the assumption that the lattice is face‐centred cubic, with high‐symmetry space group Fm3m, enable the distribution of atoms and vacancies to be estimated. In the case of iron atoms, 33 % of the corner sites are vacant in the sodium compound. The isomer shift data obtained by Mössbauer spectroscopy suggest that the sorption of caesium is not a simple ion‐exchange process. It may be regarded as ‘pseudochemisorption’ resulting from augmentation of 3d orbitals and/or the contribution from 4s bonding.
Synthesis of furoates and 5‐nitrofuroates in cyclohexane in the presence of cation‐exchange resins
Authors: Bigot Yves Le , Ayedi Hacine Ferid , Delmas Michel , Gorrichon Jean‐Pierre , Gaset Antoine
Published: July 2010

The use of ion‐exchange resins for the esterification of furoic acid and 5‐nitrofuroic acid was characterised by an excellent yield and the absence of side reactions, particularly when the reaction was carried out in cyclohexane in the presence of the resin, SPC 118. The use of this solvent for such a reaction in a biphasic medium is thus reported for the first time. This procedure might therefore be considered on a larger scale.
Effect of calcium oxide on the hydration of calcined by‐product gypsum
Authors: Beretka Julius , Crook Douglas N. , King George A.
Published: July 2010

The effect of adding increasing amounts of calcium oxide (CaO) in the pH range 3–11 on the rate of hydration and physical properties of calcined by‐product gypsums from four Australian locations was examined. The results were interpreted in terms of the Ridge equation. It was found that, as pH increased by the addition of small quantities of CaO, the kinetic parameters changed greatly. In particular, the velocity constant k gradually decreased, while α0, the measure of heterogeneous nucleation, increased. In general, increases in pH resulted in longer setting times but little change in water requirement. The mechanical strength of cast by‐product gypsum increased with the addition of CaO up to about pH 7–8, then decreased in the alkaline region. Below about pH 7 the kinetics of hydration of the hemihydrates were in close accordance with the model developed by Ridge, but differed from it above pH 7–8. This may be due to poisoning of the gypsum nuclei by habit modifiers, which are present in small quantities in by‐product gypsum.
Quantitative measurement of the percentage of aromatic carbons in petroleum crudes by using 13C‐nuclear magnetic resonance spectrometry
Authors: Srivastava Shanti P.
Published: July 2010

Quantitative 13C‐nuclear magnetic resonance has been applied to the determination of the percentage of aromatic carbon atoms (% CA) of Nahorkatia, Ankleshwar (both Indian) and Basrah (Middle‐Eastern) crude oils. From the analysis of these results it has been demonstrated that a combination of the instrumental and chemical methods (gated decoupling with a relaxation reagent added) is the only satisfactory method for the precise determination of % CA The maximum deviation in % CA due to nuclear Overhauser effect has also been estimated.
Solar‐energy storage with quadricyclane systems
Authors: Behr Arno , Keim Wilhelm , Thelen Gerhard , Scharf Hans‐Dieter , Ressler Ingrid
Published: July 2010

Norbornadiene derivatives are able to store solar energy under isomerisation to a quadricyclane system. This energy can be liberated by a transition‐metal catalysed back reaction. With methanol as a solvent during the isomerisation of dimethylquadri‐cyclanedicarboxylate I to the dimethylnorbornadienedicarboxylate II the isomeric nortricyclylmethylethers IIIa and IVa are formed as by‐products. In the presence of water the formation of the alcohols IIIb and IVb has been observed. As a result of the side‐reactions observed, it is concluded that this solar‐energy storage system I→II offers no practicability.
Decomposition of aziridine (ethyleneimine) and N‐acetylaziridine in aqueous solution
Authors: Clifford‐King William , Ferrige Anthony G. , Torkington Peter
Published: July 2010

The decompositions of ethyleneimine (EI) and its N‐acetyl derivative (AEI) have been studied in aqueous buffers at concentrations down to 1 mM. The course is determined by pH dependence, of two alternative reactions for AEI and of two consecutive reactions for EI. Consistent kinetic systems are presented. One of the reactions of AEI is a hydrolysis to EI, not reported previously. The rate‐determining step for EI decomposition is initial dimerisation to N‐(β‐aminoethyl)‐aziridine.
Oxidation of anthracene to anthraquinone in liquid‐phase with an air/oxygen/nitric acid system
Authors: Das Chandra Kumar , Das Nikhilendu Sekhar
Published: July 2010

Oxidation of anthracene to anthraquinone by air/oxygen in the presence of small amounts of nitric acid was studied in the liquid phase. The effects of various process variables (e.g. temperature, flow rate, amount of nitric acid and solvent substrate ratio) were investigated. An attempt was made to minimise the amount of nitric acid. The optimum conversions of anthracene into anthraquinone free from nitro compounds, using air and oxygen was found to be 81.7 and 96.2% respectively with corresponding purities of 98.5% and 99.6%.
Metabolic‐heat relation for aerobic yeast respiration and fermentation
Authors: Volesky B. , Yerushalmi L. , Luong J. H. T.
Published: July 2010

A specially developed temperature control system on a laboratory scale fermenter enabled continuous measurement of the rate of heat production during undisturbed growth of microbial cultures. Apart from being correlated with oxygen uptake rate, the heat of fermentation was established as an additional indicator of metabolic activity. The ‘aerobic respiration’ energetic activity of Candida utilis, Candida lipolytica and Saccharomyces cerevisiae on different carbon substrates was investigated with cultures of the latter species being also studied under the ‘aerobic fermentation’ conditions induced by glucose catabolite repression.
Industrial fermentation in China
Authors: Chen T. S.
Published: July 2010

A brief description of the recent advances in industrial fermentation in China is presented. Subject areas discussed include century‐old food products such as Soy sauce and ‘Shao Jiu’ (distilled spirits), ethanol, amino acid, citric acid, nucleic acid and enzymes. Also discussed are the recent studies on immobilised enzymes and cells and on long‐chain dicarboxylic acid fermentation.
Urea removal by anodic oxidation from saline‐simulating haemofiltrate
Authors: Köster Klaus , Wendt Hartmut , Gallus Jürgen , Krisam Gerd , Lehmann Hans‐Dieter
Published: July 2010

Urea can be oxidised electrochemically in chlorine solution to carbon dioxide, water and nitrogen. The microkinetics of this hypochlorite‐mediated urea oxidation are elucidated. Urea destruction by hypochlorite is a relatively slow reaction and needs either high reactor volumes or a high stationary temperature to proceed with a high degree of conversion. Based on this kinetic information, the optimal working conditions and construction principles of a cheap disposable oxidation cell as well as necessary auxiliary equipment are described. Data in vitro are reported for urea removal simulating a 3 h treatment of a 60 kg kidney patient. The technical and economical possibilities for haemofiltrate regeneration are discussed.
Production and quantification of transglucosidase from Aspergillus niger
Authors: Benson Colm P. , Kelly Catherine T. , Fogarty William M.
Published: July 2010

The production of transglucosidase by Aspergillus niger was examined in batch culture with thin‐layer chromatography (t.l.c.). Corn steep liquor was used as the nitrogen source and the activities obtained with four different carbon sources were examined both qualitatively and quantitatively. Prompted by the non‐quantitative nature of the t.l.c. assay technique, a quantitative transglucosidase assay procedure was developed subsequently. This was based on the hydrolysis of α‐methyl‐D‐glucoside which was shown to be unaffected not only by amyloglucosidase of A. niger but also by that from a number of other organisms. The glucose released was measured by the glucose oxidase‐peroxidase reagent, thus providing a rapid and reliable quantitative assay procedure for determining transglucosidase in the presence of amyloglucosidase.
Effect of high‐temperature treatment in air on the surface area and porous texture of zirconium dioxide prepared by thermal decomposition of the nitrate
Authors: Areán Carlos Otero , Fern Ández Colinas José M. , Arjona Andrés Mata , Villa García María A.
Published: July 2010

Zirconium dioxide, prepared by thermal decomposition of zirconium nitrate, was heated in air at temperatures ranging from 573 to 1023 K. An analysis of nitrogen adsorption‐desorption isotherms on the resulting materials allowed determination of the corresponding specific surface area and porous texture. All oxides calcined within the temperature range 573–873 K were found to be basically mesoporous; the most frequent pore radius increasing from 3 to 10.5 nm as the temperature was raised. BET surface areas decreased across the same temperature range, from 94 down to 20 m2 g−1. The sample fired at 1023 K showed a BET surface area smaller than 5 m2 g−1.
Extraction of Ca(OH)2 from portland cement and 3CaO.SiO2 pastes
Authors: Ramachandran Vangipuram S. , Polomark Gary M.
Published: July 2010

A procedure for extracting free lime from mature pastes of Portland cement and tricalcium silicate is described. It involves exposure of thin discs of paste to an aqueous solution of Ca(OH)2 in such a way that the concentration of the solution remains in the range 9.5–12 mmol CaO dm−3 throughout the extraction period. Calcium hydroxide remaining in the solid is estimated by differential scanning calorimetry and that in the extractant is estimated by atomic absorption spectrophotometry. Investigations of the extracted samples by scanning electron microscope, helium pycnometry, X‐ray diffraction, mercury porosimetry and thermogravimetry indicate that the extraction procedure has no significant influence on the C‐S‐H phase.
The selectivity of n‐heptane isomerisation on catalysts containing platinum and/or chlorine on different supports
Authors: Aodul‐Gheit Ahmed K. , Menoufy M. F. , El‐Fadly A. M. , Sif El‐Din O. I. , Sultan S. A.
Published: July 2010

The effect of promoting gamma‐alumina before and after calcination at 1130 K and silica‐alumina with 0.35% (w/w) Pt and/or 3.87% (w/w) Cl upon the selectivity of n‐heptane isomerisation was studied in a high pressure continuous flow reactor. Chlorination of Pt on γ‐alumina increased its catalytic activity but decreased its isomerisation selectivity, whereas chlorination of Pt on γ‐alumina calcined at 1130 K enhanced both activity and selectivity. Pt on silica‐alumina was the most active but the least selective among catalysts containing Pt plus Cl.

The larger the surface area of a support, the larger the dispersion of Pt in it. Pt dispersion and distribution on the support increased markedly if impregnation was associated with chlorination. The isomerisation selectivity of a catalyst did not appear to depend on dispersion of platinum, whereas hydrocracking increased as dispersion increased.
The catalytic oxidation of organic air pollutants part 1. Single metal oxide catalysts
Authors: Heyes Christopher J. , Irwin James G. , Johnson Hilary A. , Moss Ronald L.
Published: July 2010

Single metal oxides, particularly Co3O4, MnO2 and CuO1 were evaluated as the basis of catalysts for the destructive oxidation of organic air pollutants, e.g. in malodorous process emissions, with special reference to their resistance to deactivation by sulphur compounds compared with Pt‐honeycomb catalysts. Tests with low odorant concentrations, 100 volumes per million (vpm) in air, demonstrated highly efficient conversion of n‐butanal or methyl mercaptan to acceptable products over the best oxides. Ability to destroy butanal in mixtures with mercaptan at the end of life‐tests, during which the mercaptan was completely removed, decreased in the order: CuO ⋍ Pt > MnO2 > V2O5 > CO3O4. Values of the odour detection threshold measured at the catalyst exit by dynamic‐dilution olfactometry were interpreted in terms of unreacted butanal and selectivity in conversion of the odorants to CO + CO2.
The catalytic oxidation of organic air pollutants part 2. Cobalt molybdate and copper chromite catalysts
Authors: Heyes Christopher J. , Irwin James G. , Johnson Hilary A. , Moss Ronald L.
Published: July 2010

Two mixed metal oxides, cobalt/molybdenum oxide (supported on alumina) and copper/chromium oxide, were evaluated as catalysts for the control of organic air pollutants responsible for malodorous process emissions. In laboratory tests, the ability to achieve and maintain high efficiency for the complete oxidation of n‐butanal and methyl mercaptan [100 volumes per million (vpm) in air] was determined. The life of copper chromite could be extended by washing after partial deactivation by retained sulphur. In tests with process gas using copper chromite, odour removal efficiencies (measured by olfactometry in terms of dilution to detection threshold values) at 340–415°C were mostly in the range 98.5–99.5%.
Synthesis and dyeing characteristics of some new arylazopyrazole derivatives
Authors: Fahmy Sherif Mahmoud , El‐Hosami Mamdouh , El‐Gamal Sherif , Elnagdi Mohamed Hilmy
Published: July 2010

A variety of new arylazopyrazole derivatives were obtained by the coupling of diazotised 5‐amino‐4‐arylazopyrazoles with active methylene reagents and treatment of the resulting products with hydroxylamine hydrochloride. The behaviour of the newly synthesised products as acidic, direct and basic dyes on textiles is reported.
Kinetics of deactivation of Re2O7‐Al2O3 metathesis catalyst
Authors: El‐Sawi Mahmoud , Lannibello Antonio , Giordano Girolamo , Fedele Ubaldo , Ricca Gianfranco
Published: July 2010

The deactivation of 9% Re2O7‐Al2O3 catalyst during the metathesis of propene is investigated. Based on integral kinetic measurements and assuming separable deactivation kinetics, a deactivation rate equation has been developed which fits the experimental results well.
The effect of catalyst particle size on the oxidative dehydrogenation of butenes to butadiene over bismuth molybdate
Authors: Taylor Geoffrey R. , Hughes Ronald
Published: July 2010

The oxidative dehydrogenation of but‐1‐ene to butadiene has been investigated in a continuous flow system using a range of different particle sizes. A but‐1‐ene to oxygen ratio of 2:1 was adopted in most experiments in order to avoid over‐oxidation. The reaction rate was found to be first order in butene and zero order in oxygen in agreement with previous work. Particle size was found to have a profound influence on the rate of reaction and selectivity. The larger particle sizes operated at a temperature level above the ambient gas stream due to interphase effects. Allowance for this phenomenon enabled a revised activation energy of 41.42 kJ mol−1 to be estimated which was independent of particle diameter.
An 1H pulsed N.m.r. study of some amorphous silicate hydrates
Authors: Belton Peter S.
Published: July 2010

An 1H pulsed n.m.r. study of a series of amorphous sodium silicate hydrates (Na:Si= 1:1.61) is reported. Both transverse and longitudinal relaxations were examined. The transverse relaxation curves could be resolved into a Gaussian component and a component exhibiting dipolar splitting. These components were assigned to protons in hydroxyl groups and water, respectively. It was found that the hydroxyl content was independent of the total proton content. The implications of this for the structure of these solids is discussed in terms of various models.
The microbial oxidation of mixtures of methanol, phenol, acetone and isopropanol with reference to effluent purification
Authors: Wilkinson Timothy G. , Hamer Geoffrey
Published: July 2010

The microbial growth of a mixed culture on a simulated effluent containing methanol, phenol, acetone and isopropanol was shown to be less complex than might have been expected, with the system behaving as if it consisted of three superimposed noninteracting systems responsible for oxidation of the methanol, phenol and acetone. It was also shown that the isopropanol was cometabolised by the acetone‐utilising culture. Steady‐state data were used to predict both the minimum residence time in the reactor needed to remove the various organic components from the effluent and to predict the likely residual level of substrate in the effluent. The transient response to step changes in the operating conditions was also investigated and it was shown that the culture could respond instantaneously to defined changes with no increase in the organic concentration in the treated waste. It was shown that the culture has a higher respiratory activity compared to steady‐state respiration which gives the organism the ability to adjust quickly to changes in conditions in the reactor. These studies demonstrate that it is essential to understand biological parameters of waste water treatment processes—particularly for new treatment applications.
Litho‐ionomer cements and their technological applications
Authors: Prosser Havard J. , Wilson Alan D.
Published: July 2010

Litho‐ionomer cements are based on the setting reaction between polymeric acid solutions and ion‐leachable materials. The setting reactions are reviewed with regard to the structure of the ion‐leachable material, the action of the polyacid and the structure of the set cement. The hydration and adhesive properties of the cements are related to the chemical structure and are important in the application of the cements as dental filling materials and splinting bandages. Other applications as a binder and cementing agent are discussed.
Stabilisation of invertases by treatment with cross‐linking reagents
Authors: Woodward Jonathan , Wiseman Alan
Published: July 2010

Commercial baker's yeast invertase concentrate, used in the manufacture of a variety of confectionary products, was treated with various chemical cross‐linking agents in an attempt to improve its thermal stability to that of the more useful invertase from Candida utilis, which has been shown previously to have high thermal stability. Only glutaraldehyde was successful but at the expense of a loss of enzyme activity and a three‐fold increase in Km. Dimethylsuberimidate stabilised commercial invertase only slightly and the other reagents tried, either had no effect upon stability or caused a destabilisation of the enzyme. C. utilis invertase can be stabilised even further against thermal denaturation by dimethylsuberimidate. A similar stabilisation was found when this enzyme was heated in the presence of ≥ 10 mM‐CaCl2.
Synthesis of molybdenum (IV) sulphide: Part II. Reaction of molybdenum (VI) oxide with (a) zinc sulphide and (b) cadmium sulphide in the presence of ammonium chloride
Authors: Bhuiyan Nurul Haque , Ahmed Aftabuddin , Begum Sufia
Published: July 2010

Reactions of molybdenum (VI) oxide with (a) zinc sulphide and (b) cadmium sulphide were studied in the temperature range 723–973 K. Small amounts of mixtures of molybdenum (IV) sulphide and molybdenum (IV) oxide, which are difficult to separate, were produced. When ammonium chloride was added to the reactants, 89.1% pure MoS2 at 773 K and 96.17% pure MoS2 at 798 K were produced in the case of zinc sulphide and cadmium sulphide respectively.
Analysis of fed‐batch fermentation processes by graphical methods
Authors: Shioya Suteaki , Dunn Irving J.
Published: July 2010

Graphical methods are used for many types of engineering calculations. Their appeal is often related to calculational simplicity, but probably the increased understanding that accompanies a graphical calculation method is chiefly responsible for their popularity. In the present work existing graphical concepts which have been used in chemical reaction engineering and fermentation technology have been extended to allow the calculation of biomass and product formation for a variety of fermentation processes. Comparisons in productivity are made among chemostat, batch, fed batch with variable and constant feed rate, and cyclic fed‐batch operations.
Biological effects of solvent extraction chemicals on aquatic organisms
Authors: Dave GÖRan , Blanck Hans , Gustafsson Kersti
Published: July 2010

Aquatic environments are the main recipient for chemicals lost from solvent extraction plants. Therefore, the toxicity of these chemicals to aquatic organisms must be considered. So far the effects of solvent extraction chemicals on aquatic organisms have been underestimated. The toxicity of some commonly employed solvent extraction chemicals to a green alga, Chlorella emersonii, a fish, Salmo gairdneri, and two cellulose‐degrading bacteria, Cellulomonas sp. and Sporocytophaga myxococcoides, are reported. For most aliphatic amines studied (Primene JM‐T, Amberlite LA‐1, Adogen 283, Alamine 336 and Aliquat 336) inhibition of growth (algae and bacteria) and mortality of fish are shown at nominal concentrations below 1 mg dm−3 (EC50s and LC50s). Other chemicals tested (Adogen 383, TBP, HDEHP, NA SUL AS‐50, LIX 64N, Versatic 10 and 2‐ethylhexanol) are less toxic, having EC50s for inhibition of growth and/or LC50s between 0.3 and 100 mg dm−3. The acute toxicity to fish is shown to be dependent on ambient temperature for all chemicals studied. Solvent extraction chemicals spread into the environment have the potential to produce toxic effects on aquatic organisms. It is therefore recommended that the status of aquatic life in natural waters receiving solvent extraction chemicals is monitored.
Glyoxal as a possible curing agent for paints based on sodium silicate
Authors: Glasser Lesley S. Dent , Grassick Eoin G. , Lachowski Eric E.
Published: July 2010

The effects of adding glyoxal to sodium silicate solutions have been investigated and compared with those of adding glycollic acid or hydrochloric acid: gel‐time and the proportions of small silicate units in the solutions were both studied. It is concluded that the effect of adding glycollic acid is the same as that of adding HCI and that the effect of adding glyoxal is wholly accounted for by its conversion to glycollic acid through a Cannizzaro reaction.
New terpenoid dyes, 3‐arylazocamphor derivatives: Dyeing performance and fastness properties
Authors: Kaddah Ahmed M. , Khalil Abdulgalil M. , Tawfik Nizar I. , Hamouri Abdulghani
Published: July 2010

The 3‐arylazocamphor (I–VI) and 3‐arylazocamphor‐2‐oxime (VII–XI) dyes were prepared, for use as azodisperse dyes by coupling camphor or camphoroxime respectively with the appropriate diazonium salt in cold ethanol containing sodium acetate solution (10%). The structure of these compounds (I–XI) was established by studying their elemental analysis, i.r. and u.v. spectra. The effect of the nature and position of substituent in the arylazo moiety on the colour, dyeing behaviour, rate of exhaustion and fastness properties when applied to protein and man‐made fibres were discussed. The effect of after‐treatment with different metal salts on the dyed woollen fibre was also investigated.
Influence of heat generated on adsorption in bidisperse adsorbents
Authors: Kočiřík Milan , Kärger Jörg , Zikánová Arlette
Published: July 2010

Sorption behaviour in adsorbate‐adsorbent systems can be considerably influenced by adsorption heat generation. General relations for sorption in bidisperse adsorbents, represented by zeolites, are derived. One limiting case is treated analytically assuming mass transport in the interior of the crystallites and heat transport in the zeolite pellets to be fast compared both with mass transport in the intercrystalline space and with the heat dissipation into the surroundings of the zeolite pellets. The first statistical moment of the sorption curve is given and applied to the interpretation of kinetic data in the cyclohexane‐13X zeolite system.
Kinetics of absorption of chlorine in acetic acid in the presence of homogeneous catalysts
Authors: Kumar Suresh , Gehlawat Jagdish K.
Published: July 2010

The physical solubility of chlorine in acetic acid is sufficiently large (=1.00 mol dm−3 at 333 K) to enable the kinetics of reaction between chlorine and acetic acid to be determined in the homogeneous phase. The product of reaction, monochloroacetic acid, is industrially important. The solubility of chlorine in acetic acid and monochloroacetic acid was determined. The homogeneous reaction kinetics between chlorine and acetic acid were studied using acetyl chloride and ferric chloride as catalysts. The heterogeneous kinetics of absorption of chlorine in acetic acid in the presence of ferric chloride as soluble catalyst was studied in a 10 cm agitated glass reactor. The reaction between dissolved chlorine and acetic acid was found to be very slow. In the agitated reactor the diffusion effects were completely eliminated and the reaction followed homogeneous kinetics. It was first order both with respect to chlorine as well as acetic acid. The values of second order rate constant were 2.9 × 10−5 and 13.7 × 10−5 dm3 mol−1 s−1 at 333 and 353 K, respectively.
Improvement of amyloglucosidase production of Aspergillus awamori by mutagenic treatments
Authors: Nevalainen K. M. Helena , Palva E. Tapio
Published: July 2010

Mutants with increased properties of amyloglucosidase production were isolated from Aspergillus awamori after mutagen treatments. The improvement achieved in three sequential steps of mutagen treatment and screening was 2.5‐fold. Clearly improved amyloglucosidase production was also obtained in fermentor cultivations. The production of α‐amylase was also increased in the mutants.
Conductometric study of ion association in some polyelectrolytes
Authors: Islam S. Serajul , Rahman M. Lutfer
Published: July 2010

Conductances of sodium alginate, sodium carboxymethylcellulose and sodium carboxymethyl dextran solutions have been measured in the presence of sodium chloride. It has been found that the sum of the specific conductances of the components measured separately is always greater than the specific conductance of the mixture. The difference in specific conductance between the sum and the mixture, Δ, has been studied as a function of the polyelectrolyte concentration, concentration of sodium chloride and also temperature. An attempt has been made to interpret the results in terms of both electrostatic effects and the Donnan theory of membrane equilibrium. The latter approach does not seem satisfactory.
The miniloop: A small‐scale air‐lift microbial culture vessel and photobiological reactor
Authors: Pirt S. John , Panikov Nicolai , Lee Yuan‐Kun
Published: July 2010

The miniloop culture vessel provides a simple means of obtaining high oxygen transfer rates in a small scale (10 cm3) reactor. The reactor contains no moving parts. The volumetric oxygen transfer rate (measured by Cu2+ catalysed sulphite oxidation) exceeded 400 h−1. The high surface: volume ratio (12 cm−1) permitted photosynthetic algal cultures with biomass densities over 35 g dm−3 in chemostat steady‐states.
Kinetics and mechanism of the vapour‐phase ammoxidation of 4‐picoline
Authors: Das Asis , Kar Anil K.
Published: July 2010

The kinetics of the heterogeneous vapour phase ammoxidation of 4‐picoline was studied over V2O5‐Cr2O3‐Al2O3 catalysts in a differential flow reactor between 548 and 598 K and under atmospheric pressure. The rate equation

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for the conversion of 4‐picoline to isonicotinonitrile and the rate equation

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for the overall conversion of 4‐picoline, represented the rate data satisfactorily. The overall conversion of 4‐picoline was also tested by the Langmuir‐Hinshelwood mechanism.
Soda—Oxygen bleaching of kraft bagasse pulp
Authors: El‐Ashmawy Ahmed E. , Hiekal Salwa O. , Fadl Mohammed H.
Published: July 2010

Soda—oxygen bleaching of commercially available kraft bagasse pulp has been investigated. Alkali charge, temperature and oxygen pressure are important factors in controlling brightness and physical properties of the pulps produced. Pulp yields, lignin and degree of polymerisation of the bleached pulps decreased with increasing alkali charge from 2 to 6%. Strength properties as well as brightness increased by increasing alkali charge at 368 K, whereas optimum strength properties are obtained with 4% alkali at 383 K. In the range of oxygen pressure used, 5–8 kg cm−2, DP as well as strength properties of the bleached pulps increased with increasing oxygen pressure. Brightness up to 61% was reached by soda‐oxygen alone. To obtain higher brightness an afterbleaching step is necessary. The soda—oxygen—hypochlorite and soda—oxygen—chlorite pulps prepared have strength properties comparable with those of conventionally bleached pulps.
Production of solasodine by microbial hydrolysis of glycoalkaloids of Solanum eleagnifolium Cav. and its application to the synthesis of 16‐dehydropregnenolone acetate
Authors: Rodriguez J. , Segovia R. , Guerreiro E. , Ferretti F. , De Sosa G. Zamarbide , Ertola R.
Published: July 2010

Glycoalkaloids from Solanum eleagnifolium Cav. were converted into solasodine in high yield by microbial hydrolysis. It was possible to use the mycelium obtained in the fermentation for further enzymic conversion of glycoalkaloids. The crude solasodine obtained by microbial hydrolysis was converted into 16‐DHPA with 48–53% yields.
Recent advances in the analysis of coal‐derived products
Authors: Bartle Keith D. , Collin Gerd , Stadelhofer Jürgen W. , Zander Maximilian
Published: July 2010

Recent developments in some of the most important fields of the analytical chemistry of coal and its derivatives are critically reviewed: separation methods; in particular gel‐permeation, high‐pressure liquid and gas chromatography, 13C‐nuclear magnetic resonance spectroscopy, u.v. visible spectrophotometry, fluorimetry and phosphorimetry. Progress in statistical structural analysis, based on both chemical reactions and physical methods, usually n.m.r., is also comprehensively reported.