bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal characteristics of rice hulls
Authors: Hamad M. A.
Published: July 2010

Evaluation of the thermal characteristics of rice hulls is described. Decomposition was negligible below 200°C, but on heating above 200°C, the amount of volatile matter evolved increased steadily with increasing temperature up to 450°C, where > 90 % of the total volatile matter was separated. Decomposition is rapid and is temperature dependent. The effect of temperature on the composition of the residues is also described. The carbon content of the residues increased while the oxygen and hydrogen content decreased sharply when the temperature of pyrolysis was increased.
Semiconductor‐electrochemical aspects of bacterial leaching. Part 2. Survey of rate‐controlling sulphide properties
Authors: Tributsch H. , Bennett J. C.
Published: July 2010

Sixteen metal sulphides with widely differing solid state, chemical and electrochemical properties have been investigated with respect to their suitability as an energy source for Thiobacillus ferrooxidans. The most critical rate‐determining parameter for bacterial oxidation (in the absence of any electron acceptors, e.g. Fe3+) was the solubility product of the sulphide. Deviations from the systematic dependence are, however, observed when a large concentration of the holes are present in the semiconducting sulphide (p‐type conduction), or when holes are generated through electron extraction from the sulphide surface (e.g. by Fe3+). The experimental results are consistent with a mechanism in which Th. ferrooxidans utilises H+ and Fe3+ as catalytic agents which break surface bonds by chemical and electrochemical mechanisms, respectively. They are subsequently recycled while the bacterium oxidises the generated surface products, — SHδ and So, etc., to sulphate. On the basis of the derived mechanism it should be possible to estimate and predict the suitability of sulphides for bacterial oxidation and to analyse the influence of crystalline quality and impurities, as well as the composition of the solution, on the rate of oxidation.
Hydrogenation of benzene to cyclohexene on an unsupported ruthenium catalyst: Effect of poisons
Authors: Odenbrand C. U. Ingemar , Lundin Sten T.
Published: July 2010

The influence of poisoning of ruthenium catalysing the selective hydrogenation of benzene to cyclohexene has been studied. Both the yield of cyclohexene and the rate of hydrogenation are greatly affected by the degree of poisoning (e.g. FeSO4, FeCl3, TiCl3 and oxygen), and may also be optimised. A reproducible catalyst has been prepared by precipitating the catalyst precursor, as the hydroxide, in a glass vessel at 353 K without influence of corrosion products from the reactor material. The influence of the hydrogen pressure on activity has also been investigated. An optimum pressure for maximum yield of cyclohexene was obtained and a rate expression was formulated which could account for reaction orders varying with hydrogen pressure.
The adsorption of lithium onto alumina from solutions of mixed chlorides: Effects of temperature and electrolyte control
Authors: Ding‐Xue Kang , Xiang‐Mu Shen , Xue‐Yuan Wan
Published: July 2010

The effects of temperature, type and concentration of electrolyte on the adsorption of lithium into amorphous hydroxide have been investigated. As a consequence of this phase change lithium was desorbed. In the presence of NaCl and, more particularly, of MgCl2 both the processes of lithium adsorption and the alumina phase change can be considerably modified.
Microcrystalline waxes. 1. Investigations on the structure of waxes by proton nuclear magnetic resonance spectroscopy
Authors: Agrawal Krishna M. , Joshi Girish C.
Published: July 2010

Information on the degree and type of branching in ten different microcrystalline waxes, their saturated and aromatic fractions has been obtained by proton nuclear magnetic resonance. The branches present in these waxes are of the long‐chain type with a terminal methyl group and an average of about 1.3 branches per molecule.
Liquid phase oxidation of substituted toluenes by air for the production of pharmaceutical intermediates
Authors: Borgaonkar Hemant V. , Chandalia Sampatraj B.
Published: July 2010

Liquid phase oxidation of several substituted methyl aromatic compounds by air in an acetic acid medium, using cobalt acetate as a catalyst and sodium bromide or paraldehyde as a promoter, has been investigated with a view to developing manufacturing processes for the production of various pharmaceutical intermediates. In most cases carboxylic acids and aldehydes were the major products of oxidation. The process parameters such as temperature, period of reaction, and concentrations of the substrate, catalyst and promoter were chosen to obtain a high proportion of the desired oxidation product.
Ternary phase equilibrium studies of furfural‐water‐solvent systems
Authors: Patel Amrit N.
Published: July 2010

Phase equilibrium and tie line data determined at 298 K for the ternary system comprising furfural, water and organic solvents (benzene, cyclohexane, pentan‐1‐ol, cyclohexanol and benzyl alcohol) are presented. The tie‐line data for the systems have been correlated by Hand's method. Among the five solvents studied, cyclohexane showed the highest selectivity followed by benzene, benzyl alcohol, pentan‐1‐ol and cyclohexan‐1‐ol, in that order.
Chemistry of the reduction of Ellman's reagent by ascorbic acid
Authors: Baker W. L.
Published: July 2010

Ellman's reagent is reduced in two stages by ascorbic acid in the presence of copper ions. The first stage involves some reversible steps and is associated with the formation of dehydroascorbic acid. In this stage, the disulphide compound probably accepts electrons in place of oxygen. The reducing power of 2,3‐diketogulonic acid, formed by delactonisation of dehydroascorbic acid, probably effects the second stage of reduction. This is only observed upon addition of EDTA at specified intervals. Two moles of sulphydryl anions are formed per mole of disulphide. The reaction is useful for following the copper catalysed oxidation of low concentrations of ascorbic acid, but is complicated by the effects of copper ion and the hydrogen peroxide formed on the coloured anion.
A study of the Pd/C catalyst for synthesis of hydroxylamine
Authors: Chang Kung R. , Chen Hwei W. , Wan Chi C.
Published: July 2010

Palladium dispersed on active carbon (Pd/C) is used as a catalyst in the synthesis of hydroxylamine. Alkaline precipitation was used to prepare the catalyst. It was found that the controlling factor was the size of palladium crystal, which in turn was chiefly determined by the PdCl42‐/Pd(OH)2 conversion stage. The sintering and crystal growth of Pd was the main reason for the decay of the catalyst. The sintering mechanism was found to follow the Ostwald ripening model.
Studies on the adsorption of caesium, thallium, strontium and cobalt radionuclides on activated carbons from aqueous solutions
Authors: Rivera‐Utrilla José , Ferro‐Garcia Maria A. , Mata‐Arjona Andrés , González‐Goméz Cecilio
Published: July 2010

Individual adsorption studies of Cs+, Tl+, Sr2+ and Co2+ on activated carbons from aqueous solutions are reported. The carbon samples were characterised using different techniques. The surface area and the micro‐, meso‐ and macropore volumes of all samples have been calculated. The chemical nature of the surface of the activated carbons was also studied. Optimal conditions for the adsorption of the metal ions have been identified. The adsorption of these cations by the carbon samples was also determined in the presence of a number of different anions. The data suggest the possible use of activated carbons for the preconcentration and separation of some cations.
Time‐dependent properties of colloidal dispersions of ferric‐hydroxy polycations
Authors: Segal David L.
Published: July 2010

The variation of pH, unpolymerised iron(III) concentration and optical density with time after preparation for colloidal dispersions of ferric‐hydroxy polycations has been measured. Changes in these parameters are sensitive to the extent of hydrolysis of the Fe(III) ion while counter‐ions and initial ferric ion concentration affect the stability of the dispersions with respect to the formation of hydrous oxide precipitates.
The decomposition of high grade bleaching powder (calcium hypochlorite)
Authors: Bibby David M. , Milestone Neil B.
Published: July 2010

The decomposition of commercial calcium hypochlorite (termed here High Grade Bleaching Powder, HGBP) has been studied by X‐ray diffraction, differential thermal analysis, thermogravimetry and isothermal calorimetry, after storage at various temperatures and humidities. It was found that Ca(OCl)2 can decompose by at least three main routes. These include disproportionation to give Ca(ClO3)2 and CaCl2, and with the evolution of Cl2 or O2 depending on the presence or absence of water. The heat output of HGBP between 15 and 70°C differed considerably between samples and was found to increase after exposure to water vapour; some metal oxides also had a positive effect on the heat output. At 65°C the heat output oscillated, showing that both exothermic and endothermic reactions were taking place. At room temperature and in the absence of water HGBP appears to be stable.
Unperturbed dimensions and intrinsic viscosity‐molecular weight relationship of copolyesters poly(ethylene terephthalate‐co‐ethylene isophthalate)
Authors: Uglea Constantin V. , Mihaescu Adraiana
Published: July 2010

The relationship [η] = KMa and unperturbed dimensions of the copolyesters poly(ethylene terephthalate‐co‐ethylene isophthalate) with 7.5% and 25% isophthalic structures in the main chain were determined. The experimental data proved the influence of the amount of isophthalic structures upon the values of K and a from the relation between intrinsic viscosity and molecular weight and on the values for unperturbed dimensions.
Synthesis, spectral behaviour and biological activity of pyrazolo‐pyrimidine cyanine dyes
Authors: El‐Maghraby M. A. , Koraiem A. I. M. , El‐Latif F. M. E. Abd
Published: July 2010

New asymmetrical 2(4)‐monomethine cyanine dyes (IIIa‐c IVa‐i), monomethine bases (Va,b), dicationic cyanines (VIIIa_c, IXa‐c) and styryl cyanines (XIa‐b) incorporating N‐phenyl‐1‐H‐pyrazolo (3, 4‐d) saturated or unsaturated pyrimidine were prepared. The new cyanines were identified by spectral determination. Bactericidal and fungicidal activity of selected cyanines (IIIa‐c, IVa‐i, Va,bVIIIa‐c, IXa‐c and XIa,b) were tested against bacterial and fungal strains.
Application of the methylene blue test to cement raw materials
Authors: Bensted John
Published: July 2010

Characterisation of raw materials for Portland cement manufacture by use of the methylene blue adsorption method is discussed. The method is shown to be a simple, convenient ‘rule of thumb’ procedure. It provides a guide to the quantity and type of argillaceous minerals present in a given raw material sample.
Kinetics of acetone hydrogenation over Pt/Al2O3 catalysts
Authors: Rositani F. , Galvagno S. , Poltarzewski Z. , Staiti P. , Antonucci P. L.
Published: July 2010

The hydrogenation of acetone to isopropanol has been studied in the vapour phase over Pt/Al2O3 catalysts. The rate law obtained at a total pressure of 1 atm and temperatures between 303 and 363 K is of the form V=kP0aP1/2H exp (‐44 kJ mol−1 RT−1). The kinetic results are consistent with a Langmuir‐Hinshelwood hydrogenation mechanism involving a half hydrogenated species and a non‐competitive chemisorption of acetone and hydrogen on the platinum surface. The specific activity (calculated per platinum surface atom) has been found to be scarcely dependent on the platinum particle size. It is suggested that the chemisorption sites are made of a very small ensemble of platinum atoms.
Analytical characterisation and production of wool wax from Akkaraman and Morkaraman sheep's wool
Authors: Akbulut Nihat , Özdemir Mustafa
Published: July 2010

The analytical characterisation and production of wool wax from Akkaraman and Morkaraman sheep in the East Anatolien region of Turkey have been investigated. It was shown that the analytical characteristics of Akkaraman and Morkaraman wool waxes differ only slightly from other wool waxes. Therefore, from a quality point of view, wool waxes obtained from this work can be used for the same purposes as wool waxes produced from different varieties of sheep.
Conversion of methanol to hydrocarbons over the aluminosilicate catalyst HTDZ‐48
Authors: Robinson J. Gordon , Riemer Pierce W. F. , Marr George
Published: July 2010

Methanol and methanol containing small quantities of nitrosobenzene, p‐benzoquinone and p‐cresol were passed at a liquid hourly space velocity of 1.0 h−1 over the microporous aluminosilicate catalyst HTDZ‐48 at temperatures in the range 250–450°C. In each case the methanol was converted to hydrocarbons. The presence of nitrosobenzene caused a reduction in the methanol conversion, p‐benzoquinone had little effect and p‐cresol caused an increase in methanol conversion.
Computational techniques for liquid‐liquid extraction column model parameter estimation, using the forward mixing model
Authors: Korchinsky Walter J. , Young Chee‐Hong
Published: July 2010

Here is presented the first step toward the practical application of a model of liquid‐liquid extraction column performance which includes the influence of drop size distribution, or of ‘forward mixing’. The theory, previously developed and described, has been used successfully to obtain model parameter values from experimental extraction data, including drop size distributions and solute concentration profiles. The presence of a significant settling zone height complicates the theory and poses difficulties. These were overcome by the reduction of the settling zone height to an insignificant level. Values of the continuous phase mass transfer, and axial dispersion, coefficients for an assumed (Handlos‐Baron) drop‐side model are reported. The overall mass transfer coefficients are confirmed to increase with drop size.
Cyanine dyes from 4,5,10‐trioxo‐ 1,2,3,4,5,10‐hexahydro‐benz[g]quinoline
Authors: Elmaghraby Mohamed A. , Koraiem Ahmed I. M. , Khalafalla Ali K.
Published: July 2010

Asymmetrical bis‐styryl cyanine dyes (IVa‐f) containing arylidene moieties were obtained through the interaction of 4,5,10‐trioxo‐1,2,3,4,5,10‐hexahydrobenz[g]quinoline (I) with aromatic aldehydes followed by condensation with 2‐methyl quaternary salts. In addition interaction of (I) with heterocyclic aldehydes, then condensation of the products (IIIa, b) with 2‐methyl quaternary salts gave the asymmetrical bis‐styryl cyanines (Va‐d). Other symmetrical bis‐styryl cyanines (VIIIa‐c) were also obtained as reaction products between 3,4,5,10‐tetra‐oxo‐1,2,3,4,5,10‐hexahydrobenz[g]quinoline (VII) and two moles of 2‐methyl quaternary salts. The new compounds were identified by i.r. spectra determination. Bactericidal activity of selected asymmetrical and symmetrical bis‐styryl cyanines (IVa‐i, Va‐d and VIIIa‐c) were tested against bacterial and fungal strains.
Sorption of caesium by complex hexacyanoferrates iv. ion exchange kinetics and mechanism of sorption by potassium copper ferrocyanide
Authors: Lee Edward F. T. , Streat Michael
Published: July 2010

The kinetics of caesium sorption by potassium copper ferrocyanide have been studied. Liquid film diffusion is rate controlling in very dilute solutions of caesium (3.8 × 10−6m). The average film diffusion coefficient was found to be 1.465 × 10−9 m2 s−1 at 20°C and the activation energy for the corresponding process was found to be 15.14 kJ mol−1. Chemical reaction rate controls the caesium‐potassium ion exchange process at a higher caesium concentration of 3.8 × 10−3m. The shell progressive reaction model was found applicable to the sorption process. The activation energy for the caesium‐potassium ion exchange reaction was measured to be 74.85 kJ mol−1. Finally, a comparison between the theoretical and the experimental sorption profile has been made to demonstrate the validity of the theory.
Cyanide detoxification by selective ion exchange with protonated poly(4‐vinyl pyridine)
Authors: Chanda M. , O'Driscoll K. F. , Rempel G. L.
Published: July 2010

In order to explore the possibility of using cross‐linked poly(4‐vinyl pyridine), PVP, for selective removal of cyanide in waste water by complexation of the cyanide with ferrous ion followed by ion exchange, the sorption behaviour of the anionic ferrocyanide complex (Fe(CN)64‐) on the resin operating in an acid salt form has been studied. The results are compared with those obtained on a conventional gel‐type weak base resin, Amberlite IRA‐68. The ferrocyanide complex is selectively sorbed in preference to other common ions and is readily stripped with dilute sodium hydroxide. PVP has a high sorption capacity, fast sorption kinetics and a rapid rate of regeneration, being much superior to Amberlite IRA‐68 in all these respects. The sorption rate is film‐diffusion controlled at low solution concentrations (< 0.8 mmol litre−1) and particle‐diffusion controlled at higher concentrations (> 0.8 mmol dm−3). Lowering pH to ∼ 1 increases the sorption of Fe(CN)64− on to protonated PVP by 75% over that at pH 7, a phenomenon explained by the formation of protonated ferrocyanide species, HFe(CN)63‐ and H2Fe(CN)62‐. From column operations with 156 mg dm−3 cyanide waste stream a capacity of 73 mg CN− g−1 of protonated PVP to 1 mg dm−3 breakthrough is determined, compared to 60 mg CN− g−1 of protonated IRA‐68.
Reversible adsorption of thiophene on copper chromite
Authors: Sansare S. D. , Choudhary V. R. , Doraiswamy L. K.
Published: July 2010

Adsorption isotherms of thiophene on copper chromite catalyst have been obtained under catalytic conditions using the gas chromatographic technique. The isotherms were found to follow the Freundlich adsorption equation. The isosteric heat of adsorption has been determined from the isotherms and found to be dependent on surface coverage.
Thermal decomposition of iron(iii) basic sulphates in air in the presence of alkali and alkaline earth carbonates
Authors: Swamy Sitarama M. , Nayak Rangadhar , Prasad Prabhakara T.
Published: July 2010

The thermal decomposition of iron(III) basic sulphates was studied. Decomposition of the hydroxysulphate was a single‐step process in the presence of carbonates of sodium, potassium and rubidium. In the presence of basic beryllium sulphate, however, the process involved decomposition of individual components. With some carbonates, the reaction was incomplete.
Measurement of concentration profiles in a liquid‐liquid extraction column
Authors: Bonnet Julio C. , Jeffreys G. V.
Published: July 2010

A novel experimental technique for withdrawing uncontaminated samples of each phase from a highly agitated two liquid phase system (primary dispersion) is presented. The technique has been applied in the study of the continuous and dispersed phase axial mixing characteristic of a mechanically agitated liquid Scheibel extraction column operating under different conditions treating the chemical system acetone‐toluene‐water. The column mixing compartments were separated by a mixed stainless steel‐polypropylene knitted mesh packed bed which was completely ‘wetted’ by the organic dispersed phase. Several concentration profiles are presented and the non‐ideal flow parameters as well as the mass transfer coefficients for the column and system under study are reported.
Polymetallic complexes. part iii. schiff base complexes of cobalt(ii), copper(ii), cadmium(ii) and mercury(ii)
Authors: Mahapatra Bipin B. , Pujari S. K.
Published: July 2010

Eight polymetallic complexes have been synthesised of the composition M2L2.nB [M = Co(II), n = 4, B=H2O, M = Cu(II), Cd(II) and Hg(II), n = 0] M2L2'.nB [M = Co(II), n = 4, B = H2O; M = Cu(II), Cd(II) and Hg(II), n = 0], LH2 = bi‐bidentate Schiff base derived from benzoin with m‐phenylenediamine; L'Hz = tridentate Schiff base derived from benzoin with o‐aminophenol. Elemental analysis, conductance, magnetic susceptibility, i.r. and electronic spectral measurements have been done to characterise the complex compounds. A dinuclear octahedral configuration has been assigned to the cobalt(II) complexes and a dinuclear square planar structure to the copper(II) complexes. A tetrahedral configuration has been attributed to the cadmiurn(II) and mercury(II) complexes.
Evaluation of effective diffusivity of adsorbate in the absence of adsorption and surface diffusion
Authors: Choudhary Vasant R.
Published: July 2010

A method is suggested for the evaluation of effective diffusivity of adsorbate in the absence of adsorption and surface diffusion, the precise value of which is required for estimating the effective surface diffusivity and the extent of influence of adsorption on the overall mass flux in a porous solid. The method does not require the knowledge of tortuosity factor, the accurate values of average pore radius for micro, transitional and macro pores, or the porosities corresponding to micro and macro pores, which are required in case of diffusion in the transitional region and in the solids containing bimodal pore size distribution.
The adsorption of dyestuffs from aqueous solutions using activated carbon. iv. external mass transfer processes
Authors: Mckay Gordon
Published: July 2010

The parameters affecting the mass transfer coefficients for external transport of dyes from water on to activated carbon particles have been studied. The external mass transfer coefficients have been determined and correlated as the dimensionless mass transfer term, Sh/Sc0.33. The dimensionless function has been found to vary linearly with agitation, initial dye concentration, particle size, adsorbent mass on log‐log coordinates, while reciprocal variation was obtained with absolute temperature. Activation energies were determined for the surface process, for the adsorption of Deorlene Yellow, Victoria Blue, Telon Blue and Disperse Blue 7 and found to be 26.5, 24.5. 25.4 and 74.6 kJ mol‐l respectively.
The role of nickel in hydrodesulphurisation catalysts
Authors: Laine Jorge , Brito Joaquin , Yunes Simon
Published: July 2010

The acidity and activity of promoted (with NiO) and unpromoted MoO3/A12O3 catalysts were studied by ammonia adsorption, titration using acid/base colour indicators, and thiophene hydrodesulphurisation. The incorporation of nickel into supported MoO3produced significant changes in activity, which was attributed to changes in the number and strength of the acid sites. Specifically, the nickel decreased the concentration of highly acid sites and increased the number of sites with intermediate acidity in the oxide catalyst. At the same time, the nickel markedly increased the steady state catalytic activity but decreased the initial activity. Carbon and sulphur analyses, as well as acid site concentration of used catalysts, suggest that this behaviour may be associated with modifications brought about by nickel on MoS2crystallite growth and on deactivation by carbon deposition. These suggestions are found to be consistent with other effects attributedtothe promoter, such as hydrogen spill‐over and p‐semiconductivity.
Leaching of raney ni‐a1 alloy with alkali: kinetics of hydrogen evolution
Authors: Choudhary Vasant R. , Chaudhari Sudhakar K.
Published: July 2010

Kinetics of leaching of Raney Ni‐AI alloy (Ni: 50% w/w) with alkali has been studied in an agitated reactor by measuring the rate of H2 evolved in the leaching process at constant alkali concentrations. The effects of various process parameters such as temperature, type and concentration of alkali, particle size of the alloy and stirring speed, on the leaching process have also been investigated. The kinetic data could be fitted to the empirical expression:

q=α+βlog(t)

Where, q is the amount of H2 evolved in the leaching process; t, the reaction time; and a and β, the constants. The order of reaction with respect to alkali concentration and the activation energy for the leaching process were determined from the analysis of the initial rates. An appreciable fraction of the hydrogen, which is formed in the leaching process, has been found to be retained on the solid product(s).
A modified method of nitric acid pulping of bagasse
Authors: El‐Taraboulsi M. A. , Nassar M. M. , Abd El‐Rehim E. A.
Published: July 2010

Pulping of bagasse by a rapid and mild nitric acid process was successfully carried out to produce different grades of pulp. Nitric chemimechanical bagasse pulp was produced in a high yield of 91 % on pulping depithed bagasse with 4% HNO3 for a period of 30 min at 80°C, followed by alkali pulping with 2% NaOH at 95°C for 30 min. The pulp had a satisfactory strength and high opacity. On increasing the strengths of nitric acid to 7% and alkali to 7% a nitric semichemical pulp of 65% yield was obtained. The pulp had a superior strength and high opacity. The pulp was easily bleached to 71% general electric brightness (GE) with the chlorination‐alkali‐extraction‐hypochlorite (CEH) sequence. With 15% HNO3 and 8% NaOH, nitric chemical bagasse pulp was produced. The pulp was easily bleached to a high brightness of 82% GE with one stage hypochlorite. The pulp had a higher strength than kraft bagasse pulp. A satisfactory newsprint paper was produced on an experimental paper machine with a furnish composed of 80% bleached nitric semichemical bagasse pulp, 10% bleached softwood pulp and 10% clay.
A review of the air oxidation of aqueous sulphide solutions
Authors: Kuhn A. T. , Chana M. S. , Kelsall G. H.
Published: July 2010

The oxidation by air or oxygen of aqueous solutions of sulphides is reviewed. Some additional data obtained by the authors is also included. A hypothesis is advanced explaining the widely accepted catalytic effects operative in this reaction in terms of a coupled pair of electrochemical reactions.
Das Duplifikationssystem der Bakterienzelle I. Beziehungen zwischen DNS‐Replikation und Zellteilung bei balanciertem Zellwachstum
Authors: Bleecken S.
Published: July 2010

On the basis of a model of Cooper and Helmstetter, processes are described, which are primarly responsible for the regular course of the multiplication of the bacterial cell and which are called ‘duplification system’. From the model the marker frequency function, the DNA content per cell, the number of nuclei per cell and the frequency of nascent replication points per cell are calculated. A connexion between the model of Cooper‐Helmstetter and the replicon model of Jacob, Brenner and Cuzin delivers predictions on the segregation pattern of the cytoplasmic membrane. Theoretical studies explain quantitatively some experimental results quoted from the literature. A comparison between the calculated frequency of nascent replication points and the amount of ribosomal RNA per cell suggests that both cell components depend on the growth rate in the same manner.
Der Einfluß der Doppelbindung in organischen Lösungsmitteln auf das Wachstum von Bakterien
Authors: Höhne C. , Patsch R.
Published: July 2010

Es wurden drei ungesättigte und die ihnen entsprechenden gesättigten Lösungsmittel auf ihre antibakterielle Wirkung gegenüber S. aureus, E. coli, Kl. pneumoniae und Ps. aeruginosa untersucht. Die Einführung der Doppelbindung führt zu einer Steigerung der antibakteriellen Wirkung, so daß ungesättigte Lösungsmittel für den Einsatz als Lösungsvermittler bei Resistenzbestimmungen von Bakterien gegenüber in Wasser schwer löslichen Chemotherapeutika nicht in Frage kommen

Frl. R. Niederschuh sei an dieser Stelle für exakte und zuverlässige Assistenz herzlichst gedankt.
Die autoradiographische Lokalisation der DNS in thyminbedürftigen Zellen von Escherichia coli CR 34 nach Thyminmangel
Authors: Strohbach G.
Published: July 2010

Under conditions of thymine starvation the cells of the thyminerequiring strain E. coli CR 34 elongate and give rise to filamentous forms without septa. In 95% of the cells the 3H‐thymidine labelled material is characteristically confined to the center of the cells and does not extend out to the tips of the filaments. With different methods it is shown that a proportion of the cells still may divide once when DNA synthesis is inhibited by thymine depletion. It is suggested, that a filament formed under conditions of thymine starvation mostly contains one „nucleus”︁.
Transferable colicinogenic factors as mobilizing agents for extrachromosomal streptomycin resistance
Authors: Frédéricq P. , Krčméry V. , Kettner M.
Published: July 2010

Many strains with transferable colicinogenic factors were found to mobilize non‐transferable but extrachromosomally located streptomycin resistance determinants in laboratory strains. In turn, with only one exception, all strains which were found in triparental crosses to mobilize the transfer of the S‐determinants harboured a transferable col factor. These findings may show the ecological importance of transferable colicinogenic strains which occur frequently among wild type strains of E. coli in the origin and spreading of resistance transfer factors under natural conditions. When studying transfer factors and transferable resistance, it is nessessary to check the donor strains for colicinogeny and to destroy the colicines produced. Otherwise false negative results may be obtained.
Vergleichende Taxonomie der Gattung Saccharomyces (MEYEN) REESS
Authors: Kocková‐Kratochvílová Anna , Nakase Takeshi
Published: July 2010

For the estimation of the GC‐content, we have elected representatives of single groups which have been formed by numerical evaluation of the relationships among the strains of the genus Saccharomyces. The estimated GC‐values for 48 strains of the genus Saccharomyces gave an average of 36.75 Mol%, standard deviation being 1.96. The variation range within the limit 35.0–39.0 corresponds to the normal distribution.

Between the strains of the genera Zygosaccharomyces and Saccharomyces was shown a low phenetic similarity. A low similarity in DNS base composition was found between the groups “delbrueckii” and “fermentati”. This shows that they are not related phylogenetically to each other but form a polyphyletic group. Although strains of the group “bailii” and “rouxii” are phenetically not much similar to the genus Saccharomyces, the DNA base composition falls into the range of Saccharomyces. On the contrary, the genus Saccharomyces appears to be homogeneous not only phenetically, but also on the basis of similarity of DNA base composition.
Cytologische Beobachtungen an Labyrinthula coenocystis SCHMOLLER bei verschiedenen Kulturbedingungen
Authors: Babtsch G. , Bartsch G.
Published: July 2010

Ein aus Zostera marina isolierter Stamm von Labyrinthula coenocystis entwickelte sich unter verschiedenen Kulturbedingungen stets in der typischen Form netzartiger Zellverbände. Bei relativ trockener Agaroberfläche erfolgte die Entwicklung bevorzugt innerhalb des Agars. Nach Zugabe von Ölsäure bzw. löslicher Stärke zum Medium oder bei Verwendung von Leinöl anstelle einer Futtermikroben‐Suspension entstanden an Verzweigungsstellen der Schleimbahnen auf der Agaroberfläche kolonieartige Zellaggregationen.

Die Zellen sind spindelförmig und 10–15 μ lang. In älteren Kulturen oder bei Eintritt ungünstiger Bedingungen stellen sie ihre Bewegung ein und haben dann wie die „Kolonie”︁ Zellen abgerundete Spindelpole.

Elektronenmikroskopisch unterscheiden sich die Labyrinthula‐Zellen. von anderen Protisten‐Zellen durch ein spärliches endoplasmatisches Reticulum, geringe Zahl der Tubuli pro Mitochondrium, besonders aber durch zahlreiche Lipidtropfen. Eine Differenzierung von Ekto‐ und Endoplasma erfolgt nicht. Desgleichen fehlen protoplasmatische Fibrillen innerhalb des Cytoplasmas. Hinsichtlich ihrer Feinstruktur unterscheiden sich die Labyrinthula‐Zellen junger Verbände und der „Kolonien”︁ nur unwesentlich.

Unter allen geprüften Kulturbedingungen sind die Zellen von der Schleimbahn umgeben, so daß sie sich stets innerhalb derselben vorwärts bewegen müssen. Auch nach Einstellung der Fortbewegung sowie in den „Kolonien”︁ liegen die Zellen einzeln innerhalb der Schleimbahn.

Die Begrenzung zur Schleimbahn bildet eine dünne Zellmembran. Besondere Organelle, die der Fortbewegung dienen könnten, ließen sich nicht nachweisen. In allen Altersstadien besitzt die Zellmembran jedoch als „bothrosomes”︁ bezeichnete Einstülpungen, deren Struktur und Funktion diskutiert werden.

Trotz zahlreicher Versuche gelang es nicht, die Bildung spezieller Dauer‐. Entwicklungs‐ oder Propagationsstadien zu induzieren. Es bleibt jedoch offen, ob solche Stadien überhaupt fehlen oder infolge der mehrjährigen Kultur nicht mehr ausgebildet werden.
Purinstoffwechsel und Riboflavinbildung in Mikroorganismen IV. Untersuchungen zur Speicherung von Riboflavin in den Zellen von Candidia guilliermondii (CAST.) LANG. et G
Authors: Liesegang A. , Fritsche W. , Schlee D. , Reinbothe H.
Published: July 2010

Zellen der flavinogenen Hefe Candida guilliermondii gelangen im Verlauf der diskontinuierlichen Kultur in eine Phase, in der das zu Beginn in das Nährmedium ausgeschiedene Riboflavin wieder aufgenommen und gespeichert wird. Die Aufnahme erfolgt nur durch einen Teil der Zellen, der etwa ein Drittel der gesamten Zellen ausmacht („Speicherzellen”︁). Die Riboflavin‐speichernden und ‐nichtspeichernden Zellen wurden näher analysiert. Dabei ergab sich für den Proteingehalt bei Speicherzellen 16%, bei nichtspeichernden Zellen ein Gehalt von 28% der Trockensubstanz. Der Unterschied im RNS‐Gehalt ist geringer. Der Wert für die Sauerstoffaufnahme (μl O2/Std./mg Protein) ist bei Speicherzellen etwa doppelt so hoch wie bei nichtspeichernden Zellen. Riboflavin‐speichernde Zellen sind spezifisch schwerer, unterscheiden sich in Form und Größe jedoch nicht signifikant von den übrigen Zellen. Das in den Zellen vorübergehend gespeicherte Riboflavin beeinflußt die weitere Synthese nicht. Auch exogen gebotenes Riboflavin übt weder auf den Speichereffekt noch auf die Riboflavinsynthese einen Einfluß aus. Schlechte Belüftung verzögert das Wachstum und verlängert die Speicherphase.

Das beschriebene Phänomen der Aufnahme und Speicherung von Riboflavin ist nach unseren Untersuchungen für den analysierten Stamm und die aufgezeigten Bedingungen spezifisch. Andere geprüfte nichtflavinogene Hefen nehmen exogen gebotenes Riboflavin nicht auf. Auch die Aufnahme von α‐Aminoisobuttersäure und α‐ Amino‐β‐ureidopropionsäure (Albizziin) als nichtproteinogene Aminosäuren durch Candida guillierimondii verläuft nicht parallel zu dem für Riboflavin beobachteten Verhalten. Mögliche Zusammenhänge zwischen Eisenmangel, Atmung und Riboflavinspeicherung werden disuktiert.
Isolationsbedingungen für Zellkerne aus Hefeprotoplasten
Authors: May R. , Gottstein Hildegard
Published: July 2010

The structure of isolated nuclei from Saccharomyces fragilis protoplasts depends on the composition of the medium used for isolation. Buffered solutions of polymers as for instance Dextran, Ficoll and Polyvinylpyrrolidon at pH 5.5–6.5 are suitable both for carefully lysing the protoplasts and for the isolation of the nuclei. The structure of isolated nuclei does not differ markedly from nuclei in living cells. Isolated nuclei do not behave like osmometers but are swelling in buffered solution of sugars such as sucrose, mannitol and sorbitol.
Biosynthesis of vitamin B12 by Propionibacterium shermanii IV. Vitamin B12 and porphyrin synthesis in relation to the metabolic activities of the bacterium
Authors: Osman H. G. , Chenoud M. S.
Published: July 2010

The bacterial cell pool contains 16 amino acids. No qualitative change appeared in the amino acid pool at different stages of growth. No amino acids were liberated from the cell pool into the culture medium. Pyruvic and α‐ketoglutaric acids were detected in the culture medium and cell pool of Propionibacterium shermanii. Bacterial growth, vitamin B12, and coproporphyrin III synthesis increased with increasing age of the culture. A part of the synthesized porphyrin is released into the culture medium.

Glucose, the total nitrogen content of the culture medium, ammonia nitrogen, amino acid nitrogen, methionine and glycine decreased gradually with the increase in the age and the bacterial dry weight of the culture. Succinic acid appeared on the 4th day and increased with age. Acetic and propionic acids were the only detectable volatile acids. The ratio of propionic to acetic acid was about 3:1 (w/w).
Biosynthesis of vitamin B12 by Propionibacterium shermanii V. Interrelationship between vitamin B12 and porphyrin synthesis
Authors: Osman H. G. , Chenouda M. S.
Published: July 2010

Iron and cobalt inhibited the porphyrin synthesis in presence and absence of δ‐amino‐laevulinic acid (ALA). ALA greatly stimulated the porphyrin synthesis and inhibited the vitamin B12 synthesis. Addition of ALA removed the inhibitory effect of chloramphenicol and azaguanine on porphyrin synthesis. Azaxanthine decreased the porphyrin synthesis in the bacterial cells in presence of ALA. Sodium azide and 2,4‐dinitrophenol inhibited growth and vitamin B12 but had no effect on porphyrin synthesis. Malonate had no effect. It is deduced that ALA is the structural material suitable for porphyrin synthesis.
Untersuchungen zum Überkompensationseffekt bei Phosphatmangelhefe
Authors: Jungnickel F.
Published: July 2010

The influence of extracellular concentration of orthophosphate on the phosphate‐fractions has been investigated in phosphate starved cells of Candida utilis. In consequence of phosphate starvation an intensive binding of orthophosphate and synthesis of inorganic polyphosphate occurs. These two components are the most important parts of the cells capacity for phosphate‐uptake.

The extracellular concentration of orthophosphate does not effect the patterns of intracellular phosphate compounds directly. The same effects could be observed with constant cellmass and different phosphate concentrations or constant phosphate concentrations and different cellmass. The most rapid part of the uptake process (orthophosphate saturation of the cells) could be observed best using high cell dry weight (= high uptake capacity) and low phosphate concentrations. The main effect of phosphate uptake at higher ratios of \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{{\rm extracellular phosphate}}}{{{\rm cell dry weight}}} $\end{document} is the formation of inorganic polyphosphosphate, while the orthophosphate‐pool remains almost constant. Glucose decreases the orthophosphate‐pool and increases the TCA‐soluble phosphate compounds even in subsequent phosphate uptake.
Lysosome‐like particles in Geotrichum candidum: A cytochemical study
Authors: Reiss J.
Published: July 2010

Lysosome‐like particles were localized in Geotrichum candidum by means of the technique for the detection of acid phosphatase of PEARSE and staining with the vital dyes Brilliant cresyl blue and Neutral red. Pretreatments of the cells with procedures injuring the lysosome membrane resulted in shortening of the incubation time (2 min instead of 30 min). After exposure to 1% Triton X‐100 the cells showed uniform strong staining due to the release of the enzyme into the cytoplasm.
Indirekte Induktion von Escherichia coli K 12 S (λ) HCR+‐und HCR−‐Bakterien durch wirtsmodifizierte λ. B Phagen
Authors: Scherneck S. , Theile M. , Geissler E.
Published: July 2010

Sowohl unbestrahlte als auch UV‐bestrahlte E. coli K12S (λ) HCR+‐ und HCR−‐Zellen können durch Superinfektion mit wirtsmodifizierten λ. B Phagen induziert werden. Eine solche indirekte Induktion durch wirtsmodifizierte λ. B Phagen erfolgt in HCR+‐ und HCR−‐Zellen in Abhängigkeit von der Strahlendosis auf die Phagen und verläuft über ein Maximum. Die Effektivität der indirekten Induktion durch wirtsmodifizierte Phagen ist geringer als bei der direkten UV‐Induktion und läßt sich bei E. coli K12(λ ind−)‐Bakterien nicht nachweisen. Wir interpretieren diese Befunde anhand einer von uns entwickelten Induktionshypothese.
Zum Mechanismus des Membranwachstums. Untersuchungen an Bakterien mit der Gefrierätzung
Authors: Meyer H. W. , Richter W.
Published: July 2010

With a strain of bacteria isolated from distilled water it is possible to demonstrate splitting of the cytoplasmic membrane during freeze‐fracturing. The fracture faces of the membrane are covered with particles, but in these bacteria frequently smooth areas appear. A second feature is a network‐like pattern in distribution of particles caused by many small and round areas free of particles. Smooth areas and the network‐like pattern are occurring especially in samples of growing cultures and of damaged cells, whereas in samples of non‐growing cultures both are very seldom. In earlier investigations the dislocation of particles could be attributed to alterations in the structural proteins of the membrane. Therefore, the same is assumed for the occurrence of areas without particles on physiological conditions. The network‐like pattern corresponds probably to one stage in the mechanism of growth of the membrane that of widening of the “meshes” of the network‐like arrangement of structural proteins by loosening in several spots.
Untersuchungen über den Tryptophanstoffwechsel von Streptomyceten III. Tryptophanumsatz in zellfreien Extrakten von Streptomyces cremeus
Authors: Teuscher Gisela
Published: July 2010

It has been shown that cell‐free extracts of Streptomyces cremeus are capable to metabolize L‐tryptophan in presence of NADH2 and methyleneblue. NADH2 could not be fully replaced by other hydrogen donors, while methyleneblue was replaceable by similar agents. The main product formed after L‐tryptophan administration to the cell‐free extracts was anthranilic acid.

The enzyme catalyzing L‐tryptophan degradation was partially purified by ammonium sulphate fractionation and gel filtration at Sephadex G 25 columns. Some characteristics of the enzyme are given.
Action of nalidixic acid and hydroxyurea on two blue‐green algae
Authors: Madan Vimla , Kumar H. D.
Published: July 2010

The blue‐green algae Anacystis nidulans and Anabaena doliolum can grow in concentrations of hydroxyurea and nalidixic acid that are highly toxic to bacteria and certain other organisms. These drugs apparently do not seem to be mutagenic in cyanophyta. Treatment with hydroxyurea leads to the production of dense yellow mucilage in Anabaena doliolum.
Ökophysiologische Untersuchungen zur Dephosphorylierung in Cyanophyceen‐Kulturen
Authors: Reichardt W.
Published: July 2010

Dephosphorylation capacities of 7 species of blue‐green algae as measured by intra‐and extracellular phosphomonoesterase (PME) activities were found to be largely dependent on the source of phosphorus in the culture media. Hydrolyzable phosphorus compounds which effected suboptimal growth mostly enhanced the PME. An axenic strain of Anacystis nidulans showed optimum growth on both K2HPO4 and energy‐rich sugar phosphates, whereas glycerol‐2‐phosphate and pyrophosphate led to a slower growth, but, again, enabled the cells to hydrolyze phosphates more intensively. In batch cultures, growth rates and PME of Anacystis decreased at the same time. Extracellular activities were detectable, too, depending directly on support from the intracellular pool. In mixed culture with Aerobacter aerogenes, Anacystis grew faster in the presence of old non‐growing cell suspensions of this bacterium, but was inhibited by young growing cells after reaching the exponential phase. The decrease of PME in time of batch culture appeared efficiently compensated by activation and by increases of the substrate affinities. Restricted aeration revealled a similar effect. The influence of culture temperature on the dephosphorylation capacity of Anacystis‐PME is described by ARRHENIUS‐constants.
Vorkommen von R‐Plasmiden bei Salmonellen
Authors: Höhne C.
Published: July 2010

Von Juni 1968 bis Januar 1971 wurden von sporadisch erkrankten Patienten 250 Salmonellen isoliert, die 33 verschiedenen Spezies angehörten. Sie wurden auf ihre Resistenz gegenüber Streptomycin, Chloronitrin, Tetracyclin, Nifurantin, Kanamycin, Polymyxin B, Ampicillin, Nalidixinsäure und Sulfonamid getestet. Nur 14 Salmonellen (5,6%) zeigten eine Resistenz gegenüber ein bzw. zwei der neun getesteten Antibiotica bzw. Chemotherapeutica. Gegenüber Chloronitrin, Kanamycin, Polymyxin B und Nalidixinsäure waren alle Stämme sensibel. Am häufigsten wurde eine Resistenz gegen Tetracyclin beobachtet. Bei 11 Salmonella‐Stämmen war es möglich, ihre Antibioticarestistenz durch Konjugation auf Escherichia coli K‐12 zu übertragen.
Stimulatory effects of Azotobacter chroococum exudates in culture and soil on its nitrogen fixation
Authors: Elwan S. H. , El‐Naggar M. R.
Published: July 2010

The effect of the exudates of Azotobacter chroococcum in nitrogen‐free liquid medium and in sterile soil, on its ability to fix nitrogen was studied. Cell‐free culture filtrates and water extract of sterile soil inoculated with Azotobacter were fractionated into ether soluble and insoluble aliquots, concentrated and chromatographically separated into ten consecutive zones. These were eluted and tested for their effect on nitrogen fixation by Azotobacter. UV‐fluorescence, and chemical tests for indoles, reducing substances, amino acids, and hydroxyl groups were made. Detection of gibberellins and water soluble vitamins was attempted. A biological test for activity of indolic compounds was carried out.

The results showed that Azotobacter produces biologically active indolic compounds in culture and soil, acting as a significant stimulation for the process of nitrogen fixation. Not all the zones of the chromatogram which were stimulatory for nitrogen fixation were the same for coleoptile growth and vice versa. Amino acids in some cases were associated with non‐significant stimulation of nitrogen fixation. An indication was obtained suggesting the possible stimulation of nitrogen fixation by gibberellins produced in culture and soil by Azotobacter. Suggestion was given for studying the effect of individual gib berellic compounds on the nitrogen fixation process, with a view to their interaction with amino acids and indolic compounds.
Zellwandstatus neu isolierter, stabiler L‐Formen von Escherichia coli B und W 1655 F+
Authors: Geuther R. , Tkocz H.
Published: July 2010

Aminosäureanalysen isolierter Zellbegrenzungen stabiler L‐Formen von Escherichia coli B und W 1655 F+ ergaben für beide Stämme Fehlen von DAP. Dagegen konnten im Vergleich zur Normalform reduzierte Mengen von Glukosamin und Muraminsäure in der L‐Form von W 1655 F+ gefunden werden. Fehlendes intaktes Murein charakterisiert beide Stämme als L‐Formen vom Protoplastentyp.
Einige Charakteristika Pyrophosphat‐spaltender Enzyme von Candida utilis
Authors: Jungnickel F.
Published: July 2010

Bei Phosphatmangelzellen von Candida utilis wurden durch Thermoinaktivierung und Aciditätscharakteristik zwei strukturgebundene Pyrophosphat‐Phosphohydrolasen gekennzeichnet, die bei pH 2 bis pH 7 exogenes Pyrophosphat in Orthophosphat überführen.

Das Aciditätsoptimum des Enzyms I liegt bei pH 2,5, das des Enzyms II bei pH 6; bei gemeinsamer Wirkung der Enzyme I und II liegt das Optimum bei pH 2,5.

Das Enzym II ist bereits nach 10 min Vorbehandlung bei Temperaturen über 70 °C weitgehend, das Enzym I jedoch erst bei entsprechender Behandlung über 90 °C inaktiviert. Nach 10 min Vorbehandlung bei 62 °C sind beide Enzyme unvermindert aktiv und fest an die Zellen gebunden.

Nach reichlichem Phosphatangebot ist in den Zellen eine nur sehr geringe Pyrophosphatspaltende Aktivität nachweisbar; Orthophosphat reprimiert offenbar die Synthese beider Enzyme.
Aspekte des Thyminstoffwechsels bei Athiorhodaceen
Authors: Rindt K. P. , Ohmann E.
Published: July 2010

In Rhodopseudomonas spheroides and Rhodospirillum rubrum lack of thymidine kinase activity has been shown to be responsible for the failure of labelling DNA by thymidine or by thymine plus a deoxyribosyl donor, and for the obvious impossibility of selecting thymine auxotrophes by the aminopterin or trimethoprim method.

Fluorodeoxyuridine, after in vivo phosphorylation known as inhibitor of the formation of thymidine monophosphate, becomes inhibitory to light‐induced pigment syntheses in Rhodopseudomonas spheroides. This inhibition is overcome by uracil but not by thymidine, indicating that the inhibition by fluorodeoxyuridine is brought about via splitting this compound and incorporation of the fluorouracil moiety into some RNA fractions.