bluuebunny/crossref_metadata_2025 huggingface dataset:
Pressure synthesis of dibenzylamine from benzylamine and benzyl alcohol
Authors: Nandi Dilip K. , Das Birendra N.
Published: July 2010

The synthesis of dibenzylamine from benzylamine and benzyl alcohol in the presence of a phosphoric acid catalyst has been carried out under pressure. Very high pressure has no beneficial effect on the synthesis of dibenzylamine. Under optimum conditions (473K, 3.10×106Nm−2; residence period 2h; benzylamine to benzyl alcohol mol. ratio, 1:2 and benzylamine to catalyst mol. ratio, 1:0.2174), the conversion of benzylamine to dibenzylamine was 88.50%.
Oxidation of phenol by aqueous hydrogen peroxide catalysed by ferric ion‐catechol complexes
Authors: Hocking Martin B. , Intihar Donald J.
Published: July 2010

Phenol has been oxidised with aqueous hydrogen peroxide under a wide variety of conditions and yields of the catechol and hydroquinone products recorded. Catalysts tested included a number of transition metal and related ions of which only Cu+, Cu2+, Cr3+, WO42‐, Hg2+, Fe2+, and Fe3+ gave any degree of success. Extensive tests with ferric ion established 2.5:1000, Fe3+:phenol mole ratio as being the optimum catalytic range. Temperatures lower than 30°C gave relatively high catechol:hydroquinone product ratios, about 1.9:1, but lowered the yields of dihydroxybenzenes to about 70% of theory. From experiments conducted over the pH range of 1 to 8 the optimum pH for high yield reactions was found to be 2 to 3. Operating at a hydrogen peroxide:phenol mole ratio of 0.30:1.0 gave the highest catechol:hydroquinone product ratios, 1.6:1.0. The catechol:hydroquinone ratio produced decreased as the ratio of reacting peroxide to phenol was increased. Optimised conditions gave dihydroxybenzene yields of 84 and 53% on phenol and hydrogen peroxide respectively, and ratios of 1.5:1 and 2.0:1, catechol:hydroquinone. A research stage economic summary from averaged pairs of experimental results gave a value added of $3.19 (technical grade products) or $8.47 (pure grades) per kg of catechol on a raw material cost base of $2.87, as two among four calculated cost evaluation scenarios.
Effects of some plating variables on the electrodeposition of catalytically active nickel‐thallium alloy powders
Authors: El‐Halim Abd , El‐Halim M. Abd , Khalil Reda M.
Published: July 2010

The electrodeposition of nickel‐thallium alloy powders was investigated from a selected bath of the composition 0.0125 NiSO4·6H2O, 0.01 TICI, 0.10 (NH4)2SO4, 0.10 H3BO3 and 0.07 Na2SO4·10 H2O (mol dm−3). The effects of the pH of the bath, deposition current density and deposition time on the cathodic polarisation, current efficiency and composition of the electrodeposited alloy were determined. The properties of the electrodeposits examined, as a function of the above‐mentioned variables, were surface morphology and catalytic activity towards the decomposition of 0.4% H2O2 solution. It was found from this investigation that the operating variables influence to a great extent the current efficiency, composition and surface morphology of the electrodeposited alloys; and the catalytic activity is primarily controlled by the surface morphology.
Dolomite decomposition in a high temperature fluidised bed reactor
Authors: Hehl Martin , Helmrich Harald , Schugerl Karl
Published: July 2010

The decomposition of dolomite was investigated in a bench‐scale fluidised bed reactor (30 cm diameter) at temperatures between 600°C and 1000°C in batch and continuous operations. The composition of the solids was determined by X‐ray analysis, the gas composition by infrared (i.r.) spectroscopic analysis. The reaction kinetics were investigated in a small fluidised bed (2.6 cm diameter) as well as in the bench‐scale equipment and compared with kinetic data evaluated from differential thermal gravimetric (DTG) curves. The measurements were carried out by adding small amounts of dolomite into the isothermal fluidised bed. The resulting CO2 concentration within the gas could then be very low, thus MgCO3 and CaCO3 decompose as parallel reactions (singlestage reaction). At somewhat higher CO2 gas concentrations prevailing in technical operational conditions the decomposition mechanism changes into a two‐stage reaction where MgCO3 decomposes first. The bed temperature, pressure drop, superficial gas velocity, solid conversion, and specific interfacial area of solids were determined as functions of time and/or reactor wall temperature with a constant temperature increase rate for batch runs. The distributions of the residence time of solids indicate that in the continuously operated fluidised bed well‐mixed conditions prevail. The concentrations of dolomite, CaCO3, MgO, CaO, and solid conversion as well as the specific surface area of particles were determined as functions of the mean residence time in the continuous reactor. By means of the CO2 concentration in the gas phase and the mean residence time the conversions of the consecutive reactions can be controlled.
Vapour‐phase nitration of paraffin hydrocarbons on bismuth‐molybdenum catalyst
Authors: Toromanova Pepa , Mladenov Ivan
Published: July 2010

The effect of bismuth‐molybdenum catalyst on the vapour‐phase nitration of propanebutane fraction with nitric acid has been studied. The catalyst examined increases the total yield of nitroparaffins obtained nearly four times in comparison with the nitration without catalyst. The influence of the temperature, initial mole ratio of gas/nitric acid and contact time on the catalyst activity and the yields of individual nitroparaffins have been studied.
Kinetics and mechanism of adsorption of triton x‐100 on a reservoir sand
Authors: Singh Vimal Sheel , Pandey Birendra Prasad
Published: July 2010

Adsorption of Triton X‐100 on a reservoir sand (characterised by chemical analysis and i.r. spectra to be silica) has been studied under field conditions. The adsorption behaviour is best characterised by Freundlich and Temkin adsorption models. The kinetics of adsorption is found to be very much dependent on temperature and the rate of adsorption shows an anti‐Arrhenius temperature dependence. The adsorption is proposed to proceed through Si—CH3 bond formation. Addition of common inorganic salts is found to cause maxima and minima in the adsorption isotherm and to change the shape of the isotherm.
Cure of elastomeric building sealants
Authors: Beech J. C. , Turner C. H. C.
Published: July 2010

The cure of a range of elastomeric building sealants is investigated by measuring tack‐free time and hardness under a range of laboratory test regimes and under natural exposure. Temperature, relative humidity and ultraviolet light were noted to have an interactive effect on cure, although the influence of these factors varied between the different sealant types studied. The investigation identifies laboratory conditions which are favourable to cure, and these are compared with cure conditions specified in standard tests.
Sorption of caesium by complex hexacyanoferrates iii. a study of the sorption properties of potassium copper ferrocyanide
Authors: Lee Edward F. T. , Streat Michael
Published: July 2010

Commercially available potassium copper ferrocyanide (KCuFC) has been studied for caesium sorption. An effective capacity of 2.25 ± 0.06 mmol g−1 can be achieved at a caseium concentration of 0.015m. The presence of 0.82m, magnesium nitrate reduces the effective capacity to 2.04 ± 0.06 mmol g−1. The cyanoferrate also shows high caesium uptake in various simulated process solutions relevant to the treatment of radioactive wastes. KCuFC also possesses a high selectivity for caesium in high salt concentration solution. However, the cyanoferrate is not stable in acidic solution of pH < 3. Desorption of the sorbed caesium at various nitric acid concentrations has been investigated and it is concluded that caesium is eluted by a chemical reaction step as a consequence of the oxidation of the cyanoferrate.
Kinetics of the dissolution of copper(ii) oxide in acidified ascorbic acid solution
Authors: Harvey Helen , Malati Mounir A.
Published: July 2010

The zero order kinetics of the dissolution of CuO in ascorbic acid solution, acidified with HCl, was followed by measuring the absorbance of the coloured solution formed at 750 nm. From the variation of the logarithm of the rate constant with the reciprocal of the absolute temperature, an activation energy of 36 kJ mol‐1 was calculated. The infrared spectrum of a solid isolated from the reaction mixture was compared with the spectrum of ascorbic acid. A tentative mechanism of the reaction is suggested.
Ternary data for the acetic acid‐water‐mesityl oxide system
Authors: Hegazi Mohamed F. , Salem Abu‐Bakr
Published: July 2010

The ternary equilibrium data for the system acetic acid‐mesityl oxide‐water were determined at different temperatures. The results showed no significant effect of temperature on the solubility area. However, addition of about 10% sodium chloride increased the area under the binodal curve by more than 40 %. The tie line data were also determined. These data proved that mesityl oxide particularly in presence of salt is a promising solvent for acetic acid extraction from aqueous solutions.
Fibrous active carbons from coir
Authors: Hitchcock Stephanie J. , Mcenaney Brian , Watling Stephen J.
Published: July 2010

The production and adsorptive properties of fibrous active carbons produced from coir were investigated using thermogravimetric analysis, gas adsorption, adsorption from solution, mercury porosimetry and electron microscopy. Additions of ZnCl2 to coir increased carbon yield by lowering the temperature of primary carbonisation. Apparent specific surface areas of the carbons lie in the range 435–880 m2 g‐1; the carbons are microporous and exhibit strong preferential adsorption of p‐nitro‐phenol from solution. Macropores in the carbons were identified as interfilamentary voids in the carbon fibre bundles.
Ternary phase equilibrium studies of the systems tetrahydrofuran—water—solvents
Authors: Patel Amrit N.
Published: July 2010

Ternary phase equilibrium data for tetrahydrofuran (THF) with water and the hydrocarbons, benzene, toluene, cyclohexane, chlorobenzene and nitrobenzene are presented. The tie‐line data for the systems have been correlated and the plait‐points have been located. The distribution of THF is more in favour of the organic phase for all the systems. Among the five solvents studied, benzene showed the highest distribution coefficient and selectivity for THF, followed by toluene.
A study of the hydrogenation of kelex 100 loaded with copper
Authors: Demopoulos George P. , Distin Philip A.
Published: July 2010

Direct metal precipitation from loaded organic extractants by reaction with hydrogen may offer certain potential advantages over the conventional alternative steps of stripping and electrowinning in extractive metallurgy. As part of an experimental programme involving the interaction of loaded chelating extractants with hydrogen, the thermal and chemical behaviour of loaded Kelex 100 (an alkylated derivative of 8‐hydroxyquinoline) was studied. Copper was found to precipitate stoichiometrically with simultaneous organic regeneration from loaded Kelex l00/decanol/kerosene solvents by reaction with hydrogen. The chemical stability of the extractant was some‐what reduced when the decanol was removed from the system. In the latter case, some limited hydrogenation of the quinoline nucleus of the extractant and some of the impurities present was observed. When loaded Kelex 100 was heated under nitrogen, a slow thermal dissociation was observed resulting in copper precipitation and apparent organic regeneration.
Kinetics of desorption of hydrogen from copper chromite catalyst
Authors: Choudhary Vasant R. , Srinivasan K. R.
Published: July 2010

Isothermal desorption of hydrogen from copper chromite has been studied from 50 to 300°C. An empirical expression, β exp [—αq]= t, is found to fit the desorption data satisfactorily, while the application of the Elovich and the first order desorption rate expressions lead to the detection of three kinetic stages in the desorption process. The rate parameters obtained using these latter two models have a complex trend in their behaviour with temperature. The Elovich rate parameters are found to undergo undulatory changes with temperature like those of the adsorption isobar and their transition regions are very close to those of the adsorption isobar. Also, there seems to be a close relationship between the surface coverage at transition points and the adsorption isobars. The presence of the three kinetic stages in the desorption process may be accounted for by considering the three distinctly different types of adsorption sites on the reduced copper chromite.
Synthesis and antibacterial activity of some new pyrazolone dyes
Authors: El‐Kashef H. S. , Abd‐Alla M. A. , Bayoumi B. E. , El‐Timawy A. A. M.
Published: July 2010

Some 1‐phenyl‐3‐methyl‐4‐(thia‐and/or selenadiazolylphenylhydrazo)‐Δ2‐pyrazolin‐5‐one derivatives have been prepared and screened in vitro for their antibacterial and antifungal properties.
Sorption of caesium by complex hexacyanoferrates. v. a comparison of some cyanoferrates
Authors: Lee E. F. T. , Streat M.
Published: July 2010

The properties of copper cyanoferrates and potassium cobalt ferrocyanide prepared at Imperial College and similar commercial products for caesium sorption have been investigated. Copper and cobalt based cyanoferrates have different chemical compositions and appear to be good adsorbers for the removal of caesium in aqueous solutions. Different caesium sorption mechanisms were observed for these cyanoferrates. A conventional ion exchange reaction, physical adsorption and a combination of the two processes were observed. The difference in caesium sorption mechanism also reflects the kinetics of the sorption process. Potassium copper ferrocyanide has the highest effective capacity but the caesium sorption rate is the slowest, whilst potassium cobalt ferrocyanide possesses faster kinetics but considerably lower effective capacity. Copper ferrocyanide tends to have better mechanical stability and moderate sorption kinetics and caesium uptake.
Properties and structures of some butoxysiloxanes
Authors: Alagar M. , Krishnasamy V.
Published: July 2010

Tetrabutoxysilane and polybutoxysiloxanes were prepared by reacting SiCl4 with I‐butanol and I‐butanol‐water mixtures in liquid phase. The effect of water content on some of the physical properties, such as viscosity, density, surface tension, refractive index, specific heat, thermal expansion and ultrasonic sound velocity, was determined. Also, the molecular weights and the percentages of silica and butoxy group were estimated. Using these experimentally determined physical properties, other properties such as Rao's number, molecular radius, Van der Waal's constant, isothermal and adiabatic compressibilities, the ratio of specific heats, thermal conductivity and the activation energies for vaporisation and viscosity were calculated theoretically. Based on the experimental values and theoretical calculations, the cyclic structure of some of the compounds was established.
Microstructure and water sorption mechanism of coconut pith
Authors: Idiculla Roschen , Radhika L. G. , Seshadri S. K. , Satyanarayana K. G.
Published: July 2010

The water sorption isotherm of coconut pith is studied in order to get an insight into the nature of the sorption process. The surface area available for adsorption, heat of adsorption and approximate size of possible capillaries are computed from the isotherm. A considerable hysteresis effect is observed. The cell structure of coconut pith is studied using an optical microscope. On the basis of the computations and microscopic observations, the similarity of the sorption process with that of woody materials is established.
Fitting the momentum dependent loss function in EELS
Authors: Bertoni Giovanni , Verbeeck Jo , Brosens Fons
Published: July 2010

Momentum dependent inelastic plasmon scattering can be measured by electron energy loss in a transmission electron microscope. From energy filtered diffraction, the characteristic angle of scattering and the cutoff angle are measured, using a thin film of aluminum as a model test. Rather than deconvolving the data (as done in previous works), a fitting technique is used to extract the loss function from angular resolved spectra, starting from a simple model simulation. Microsc. Res. Tech., 2010. © 2010 Wiley‐Liss, Inc.
Investigations of SiC merged pin Schottky diodes under isothermal and non‐isothermal conditions
Authors: Zarębski J. , Dąbrowski J.
Published: July 2010

The paper concerns the problem of SPICE modeling of the merged pin Schottky (MPS) diodes. In the paper, the SPICE electrothermal model (ETM) of the SiC MPS diodes proposed by Infineon Technologies is investigated. The model was verified experimentally by comparing the calculated and the measured d.c. characteristics of the diode IDT06S60C. Some modifications of the model resulting in the improvement of its accuracy at d.c. analysis are proposed. Copyright © 2010 John Wiley & Sons, Ltd.
Subgroups within a team: The role of cognitive and affective integration
Authors: Cronin Matthew A. , Bezrukova Katerina , Weingart Laurie R. , Tinsley Catherine H.
Published: July 2010

We examine the effects of subjectively experienced (as opposed to objectively prescribed) subgroups in a team. We propose two mechanisms that might explain the consequences of subgroup perceptions in teams: Affective integration (the degree to which teammates think they have quality interpersonal relationships) and cognitive integration (CI) (the degree to which teammates have learned to understand others interpretive frameworks). We test our theory using 64 MBA project teams. Cognitive integration moderated the effect of subgroup formation on team effectiveness, while affective integration mediated the decrement that subgroup formation had on team satisfaction. Our model is general for any team that has subgroups (regardless of their reason for forming), and so provides prescriptions as to how to maximize the benefits of subgroups while minimizing their liabilities. Copyright © 2010 John Wiley & Sons, Ltd.
Crafting scholarly life: Strategies for creating meaning in academic careers
Authors: Wellman Ned , Spreitzer Gretchen
Published: July 2010

Job crafting, which occurs when individuals proactively make changes to their jobs, can be a useful tool for academics seeking more meaningful careers. We suggest changes to the cognitive, task, and relational aspects of academic jobs that can infuse scholarly work with more personal meaning. Copyright © 2010 John Wiley & Sons, Ltd.
A simple method for detection of penicillinase‐negative variants among large numbers of penicillinase‐producing staphylococcal colonies
Authors: Borowski Jerzy
Published: July 2010

As has been shown by the studies of BARBER (1948, 1949), FAIRBROTHER et al. (1954). BONDI et al. (1953), HAMBURGER et al. (1958, 1960) and by BOROWSKI (1963a, 1963b), penicillinase‐producing staphylococci may give rise to penicillinase‐negative mutants displaying full sensitivity to penicillin. BOROWSKI (1963) reported that strains yielding penicillinase‐negative mutants in appreciable numbers are found most frequently among staphylococci of phage group I. HAMBURGER et al. (1958, 1960), and BOROWSKI (1963) isolated penicillin‐sensitive variants from the organs of infected animals which were challenged with penicillinase‐producing Staphylococcus aureus strains.
Streptomyces sp. producing litmocidin
Authors: Abou‐Zeid A. A. , El‐Gammal Amira A.
Published: July 2010

Morphological and physiological studies on an isolated strain of Streptomyces from an Egyptian soil, producing high yields of litmocidin, were carried out. The local strain was compared with litmocidin producing species. The morphological and physiological characteristics revealed that the isolated strain is more related to Streptomyces litmocidini. The local strain was considered to be a new species of Streptomyces producing than to Nocadia. The utilization of the different carbon sources by the microorganism for the production of the antibiotic was investigated.
Effect of rifampicin on stability and transfer of R‐factors
Authors: Krčméry V. , Janoušková J.
Published: July 2010

Rifampicin LEPETIT, an antibiotic known to interfere with the activity of DNA‐dependent bacterial RNA polymerase, prevented the conjugational transfer of R‐factors in Salmonella typhimurium and Escherichia coli, and showed appreciable accumulation of R— variants in R+ cultures. The drug was active in concentrations from 0.25 to 5.0 μg/ml while there was no influence on the viable count of the R+ cultures. Although the concentrations of rifampicin found to be active in R+ strains of enterobacteria are about 10 times higher than those found to be active in staphylococci by JOHNSTON and RICHMOND (1970), the sub‐bacteriostatic concentrations of the drug were effective enough to eliminate R‐factors and to prevent their transfer from the donor cells studied.
Zellteilungsverhalten von Bacillus megaterium beim Übergang zu Kohlenstoffhunger
Authors: Kretschmer Sigrid
Published: July 2010

In cultures of a sporulating strain of B. megaterium grown at different growth rates the rate of division and the distribution of cell length were measured electronmicroscopically. Samples were taken from two doubling times before carbon limitation through 2.5 hours after the shift down.

Contrary to the optical density, which increased exponentially until the carbon source was exhausted, the frequency of division changed 1–2 generations before. In fast growing glucose‐cultures the cells were longer than those in the slow growing arabinose‐cultures. These first mentioned cells became shorter already one doubling before the shift down by a transitory increase in division rate. No difference in length of growing and starvating cells was found with the arabinose‐culture. In all cultures the final decrease of the frequency of division also took place before the stationary phase was reached. This indicates that the initiation of division is more sensitive to carbon starvation than the net growth.

The shapes of the curves reflecting the distribution of cell size were nearly identical with growing and starving populations. Thus, cell elongation is inhibited by carbon exhaustion in all cells at the same time.

During the starvation period not all division septa were completed. 3–10% of the cells with in the populations remained uncompletely divided.
The presence of penicillin‐G destroying enzymes among different bacteria
Authors: Vandamme E. J. , Voets J. P.
Published: July 2010

Different bacterial strains were investigated for their benzylpenicillin destroying activity. The possible degrading products, benzylpenicilloic acid (BPA), 6‐aminopenicillanic acid (6‐APA) or penicic acid (PA) were screened by thin layer chromatography, using a new solvent system. Near all the strains tested, produce at different levels a β‐lactamase as observed from the BPA production. Acylase was not produced by the strains investigated. Neither 6‐APA nor PA were found, although small amounts of these products could not be detected by this qualitative method. BPA production from benzylpenicillin was measured quantitatively as a function of the enzymatic activity of the β‐lactamase.

These experiments were carried out on the washed bacterial cells, the cell‐free growth medium and the cells treated with toluene. Most of the β‐lactamase activity was produced extracellularly by the bacteria; lower levels were found in the washed cell suspensions.
Bestimmung der Trockenmasse von Zellsuspensionen durch Extinktionsmessungen
Authors: Günther H. H. , Bergter F.
Published: July 2010

Die Aussagemöglichkeit der Trübungs‐ bzw. Extinktionsmessung an Zellsuspensionen wurde untersucht. Dazu wurden Extinktionsmessungen unter Einbeziehung möglichst großer Variationen der Zellgröße und unter Verwendung eines Photometers mit möglichst kleiner Apertur, des PULFRICH‐Photometers mit Wechsellichtzusatz, durchgeführt. Durch zusätzliche mikroskopische Zellzahlbestimmung und gravimetrische Bestimmung des Trockengewichtes der untersuchten Bakterien‐ und Hefearten konnten experimentell ermittelte Extinktionskoeffizienten für 108 Zellen pro cm3 und Extinktionskoeffizienten für 0,1 mg Trockenmasse pro cm3 erhalten werden. Diese experimentellen Werte wurden den nach der Theorie der Lichtstreuung für analoge, idealisierte Partikeln berechneten Extinktionskoeffizienten gegenübergestellt.

Während sich die Extinktionskoeffizienten, die sich auf gleiche Zellzahl beziehen, für die verschiedenen Zellgrößen um zwei Größenordnungen unterscheiden, verändern sich die Extinktionskoeffizienten, die sich auf gleiche Trockenmasse beziehen, hier um etwa 30%. Damit ist, wie auch von der Theorie gefordert wird, die Extinktionsmessung an Zellsuspensionen viel mehr mit der Trockenmasse als mit der Zellzahl korreliert.
Transduktion mit dem temperenten Proteus mirabilis‐Phagen π1. I. Charakterisierung des Transduktionssystems
Authors: Stäber H. , Böhme H.
Published: July 2010

The influence of adsorption and multiplicities of infection on the transducing system Proteus mirabilis—π1 was studied. The frequency of transduction and the rate of survival depended on the duration of the incubation of the transducing mixture. The maximum of transducing frequency was obtained after 5 min of incubation at 37 °C. This time corresponds to that required for optimal adsorption. The frequency of transduction and the rate of survival depended on the multiplicities of infection. An optimal frequency of transduction for the system studied was obtained with multiplicities of infection ranging from 4:1 to 8:1.
Der Stoffwechsel von Tetrahymena pyriformis bei der Aufnahme von Nahrung und unverdaulichen Partikeln
Authors: Burmeister J.
Published: July 2010

Die Aufnahme von unverdaulichen Partikeln (Kohle, Quarz, Polystyrol) führte bei Tetrahymena nicht zu einer Steigerung der Atmung. Verdauliche Teilchen (Bakterien, Hefe, Stärkekörner, Fettröpfchen) verursachten stets eine sofort einsetzende deutliche und für die gesamte Versuchszeit (2 Std.) gleichbleibende Erhöhung der Atmung auf das 1,2—1,8fache. Es wird angenommen, daß die Verdauung der Nahrung Ursache der Atmungssteigerung ist. Bei der Kombination zweier aktiver Substanzen (Hefe, Hefeextrakt) kam es nicht zu einer einfachen Addition der Einzelwirkungen, sondern das System des Verdauungsstoffwechsels zeigte einen gewissen Sättigungseffekt. Der Phagocytosestoffwechsel von Tetrahymena gleicht nicht generell dem von Phagocyten (Leukocyten) sondern weist eigene Züge auf.
Manganoxidierende Pilze I. Vorkommen, Isolierungen und mikroskopische Untersuchungen
Authors: Schweisfurth R.
Published: July 2010

Aus Boden, Wasser, Eisen‐Mangan‐Schlämmen und Manganoxid‐Lagerstätten wurden etwa 50 manganoxidierende Pilze isoliert. Die Befähigung zur Manganoxidation ist nicht auf einzelne Familien, Ordnungen und Gattungen beschränkt. Mehrere Arten gleicher Gattung können demnach in ihrem Verhalten gegenüber Mn++ verschieden sein.

Menge und makroskopisch erkennbare Form der gebildeten Manganoxide sind verschieden (locker‐unstrukturiert, fädig oder kugelig), jedoch für Gruppen von Pilzarten typisch und annäherend gleich innerhalb einer Art.
A new polypeptide antibiotic produced by a Streptomyces species isolated from Egyptian soil
Authors: Abou‐Zeid A. A. , Shehata Y. M.
Published: July 2010

An actively antibiotic producing actinomycete, Streptomyces NRC‐101, was isolated from Egyptian soil. The strong antibiotic effect of the fermentation broth of the microorganism on grampositive and gramnegative bacteria led to experiments for the isolation of the active principle. After isolation and purification its physico‐chemical and biological properties were different from the well‐known antibiotics. Therefore, it was identified as a new antibiotic designated as antibiotic NRC‐101.
Thermodynamics of the chemostat
Authors: van Uden N.
Published: July 2010

Practical equations are written for the transfer rates of substrates and products into and out of cells growing in the chemostat, the rates of heat production and of biomass production, and the exchange rates of heat and matter between the chemostat and its surroundings. These rate equations together with partial molal quantities of the substrates and the products at their steady state concentrations in the chemostat, and with thermodynamic quantities of biomass, are combined to give equations for the rate of entropy production due to irreversible processes in the chemostat and for the rate of entropy exchange between the chemostat and its surroundings. In addition, expressions are obtained using practical thermodynamics quantities, for calculating the minimum entropy content and the enthalpy of formation of cells growing in the chemostat under defined steady state conditions.
Untersuchungen zur Antigenstruktur von Shigellen III. Schwankungen in der chemischen Zusammensetzung und der serologischen Aktivität der Lipopolysaccharide von Shigella flexneri
Authors: Seltmann G. , Beer W.
Published: July 2010

Die chemische Zusammensetzung der Polysaccharide von Sh. flexneri‐Stämmen und ihre serologische Wirksamkeit können von Anzüchtungscharge zu Anzüchtungscharge schwanken. Es wird gezeigt, daß dies auf Unregelmäßigkeiten bei der Biosynthese der Lipopolysaccharide zurückzuführen ist, bei der neben den vollständig ausgebildeten S‐spezifischen Teilen auch solche gebildet werden, die entweder zu wenig eingebaute Glucose oder eine zu geringe Anzahl an „repeating units”︁ enthalten. Schließlich konnte bei Stamm 2 auch eine Fraktion isoliert werden, die nur noch das Kernpolysaccharid enthielt.
Physiology of heterocyst production in the blue‐green alga Anabaena doliolum I. Nitrate and light controls
Authors: Singh H. N. , Kumar H. D.
Published: July 2010

In the blue‐green alga Anabaena doliolum heterocyst differentiation is sequential and independent of vegetative growth. Its control is photosynthetic in nature. The nature of growth curves obtained in nitrate and nitrogen‐free media indicates that the heterocyst regulates vegetative growth but has no role in sporulation. The formation of the first heterocyst is determined at a certain stage during the development of a 2‐celled germling into a 4‐celled filament.
Physiology of heterocyst production in the blue‐green alga Anabaena doliolum II. Effects of ultraviolet light
Authors: Singh H. N. , Kumar H. D.
Published: July 2010

Effects of UV radiation on the morphogenesis of Anabaena doliolum are described. After irradiation the frequencies of the 2nd and 3rd cells in 4‐celled filaments differentiating into a heterocyst increase markedly. The spatial relations between successive heterocysts of the series in growing filaments, however, remain nearly unchanged.

While nitrate prevents both heterocyst formation and sporulation, after UV irradiation out of a total of 1925 survivors growing on nitrate plates 5 formed heterocysts without sporulation and 2 sporulated without forming heterocysts. It is concluded that there exist genetic control processes for both types of differentiation which can mutate independent of each other.
Behaviour of polygalacturonase and pectin‐methylesterase of Clostridium felsineum in the paper chromatographic process
Authors: Abdel‐Fattah A. F.
Published: July 2010

Paper chromatography of pectin‐methylesterase and polygalacturonase produced by Clostridium felsineum was achieved with buffers, buffered salt solutions and acetone‐water mixture. No true separation of both enzymes was attained and they became inactivated when chromatographed on paper under appropriate conditions. The chromatographed enzyme preparation showed only pectin‐methylesterase activity when the acetone‐water solvent was used as the developing agent. The aforementioned enzyme occupied the lower part of the chromatograms on using the ascending technique. The inactivation of pectolytic enzymes was attributed to their denaturation by spreading in the form of a film on the paper chromatograms. The extent of solubility of these enzymes in the developing agent was found to be a limiting factor for their spreading on the chromatograms and, hence, their inactivation.
Nachweis seltener Basen in mikrobieller Desoxyribonucleinsäure
Authors: Reinert H. , Venner H.
Published: July 2010

Die DNA von fünf Mikroorganismen, Proteus mirabilis 273, dessen UV ‐sensibler Mutante P. mirabilis PG 672, einer stabilen zellwandlosen L‐Form von P. mirabilis VI sowie die der Actinomyceten Streptomyces chrysomallus und Str. griseus, wurde mit Hilfe der Dünnschicht‐ und Säulenchromatographie auf ihren Gehalt an seltenen Basen untersucht. In beiden Streptomyces‐Stämmen konnte nur 5‐MC nachgewiesen werden. Die zellwandlose L‐Form von P. mirabilis VI und der Stamm P. mirabilis 273 enthalten neben 5‐MC noch 6‐MAP, der Stamm P. mirabilis PG 672 zwar 6‐MAP aber nur sehr wenig 5‐MC.
Interferenzmikroskopische Trockenmassebestimmungen an primären Strumazellen in Gewebekultur I. Methode
Authors: Seeber Christine , Klagge E. , Beyer H.
Published: July 2010

Vergleichende Gangunterschiedsmessungen an Kern und Plasma von primären Strumazellen erfolgten unter Anwendung des Beleuchtungsspalts bzw. des Beleuchtungsgitters. Der Fehler der Methode war bei Benutzung des Beleuchtungsgitters kleiner als bei Anwendung des Beleuchtungsspaltes. Die Trockenmasse wurde von Plasma und Kern in Hankslösung von pH 6,8, 7,0, 7,2 oder 7,4 bestimmt. Die Trockenmasse ließ sich an der gleichen Zelle 7mal im Abstand von 15 min bis zu 90 min Meßzeit ermitteln. Es ist zu empfehlen, die Trockenmasse in Hankslösung von pH 6,8 zu bestimmen und die Meßzeit auf 60 min zu beschränken. Anderenfalls verändern sich bei pH 6,8 der Hankslösung die Werte für die Trockenmasse des Kernes bis zu 25%.
Autotrophic growth of hydrogen bacteria in continuous culture
Authors: Voytovich J. V. , Gitelson I. I. , Ponomaryev P. I. , Sidko F. Ya. , Terskov I. A. , Trubachov I. N.
Published: July 2010

A laboratory installation was developed for continuous cultivation of hydrogen bacteria by turbidistate with a capacity of about 5 1. A steady state process with Hydrogenomonas eutropha was realized which produces up to 40 g/1 · day of dry biomass. Optimum concentration values for oxygen, hydrogen, carbon dioxide in the gas phase for various densities of bacterial suspensions were found. The minimum concentrations of bioelements are: N 50–70 mg/1, P, Mg, K 20–40 mg/1.

The biomass of hydrogen bacteria is characterized by a high protein content (up to 77%) including irreplaceable amino acids up to 40%, and nucleic acids up to 10%. Oxygen and nitrogen deficiency lead to a protein decrease up to 46% and an increase in the concentration of poly‐β‐hydroxybutyric acid. The possibility of a continuous unsterile cultivation of Hydrogenomonas with prevalence over the growth of the accompanying microflora is shown.
On the clotting of milk by rennet‐like enzyme of Aspergillus niger
Authors: Abdel‐Fattah A. F. , Mabrouk S. S.
Published: July 2010

No intracellular enzyme possessing milk‐clotting activity was found in the mycelium of Aspergillus niger. There was a time‐lag in the clotting stage on using small amounts of the culture filtrate in the reaction mixture. Dilution of milk caused a decrease in the milk‐clotting activity and this was attributed to several factors. Phosphate buffer was found to accelerate the enzymatic coagulation of milk when the reaction mixture had a pH less than 6.3. The addition of CaCl2 to buffered reaction mixtures caused decrease in pH and time of milk‐clotting. The extent of any decrease depended on the amount of CaCl2 added, the type and pH of buffer.
Untersuchungen zur Antigenstruktur von Shigellen V. Bindung der Neutralzucker in den O‐antigenen Seitenketten der Lipopolysaccharide von Shigella flexneri 1b und Variante Y
Authors: Beer W. , Seltmann G.
Published: July 2010

Die durch Permethylierung des Polysaccharidteils der O‐Antigene von Shigella flexneri 2 (Serotyp 1 b) und 1290/63 (Variante Y), Totalhydrolyse, Reduktion und Peracetylierung gewonnenen Alditolacetate wurden gaschromatographisch getrennt und massenspektrometrisch zugeordnet. Es wurde gefunden, daß Stamm 2 Rhamnose in 1,2‐ und 1,3‐Bindung sowie endständig gebundene Glucose enthält. Stamm 1290 enthält Rhamnose in 1,2‐ und 1,3‐Bindung. Die in der Polysaccharidfraktion dieses Stammes gefundene Glucose entstammte mitgeschlepptem Poly‐1,4‐glucan.
Aminoacyl‐tRNS‐Synthetasen und Zellteilung bei einer temperatursensitiven filamentösen Mutante von Bacillus subtilis SB 19
Authors: Süss J. , Mach Hiltraut , Mach F.
Published: July 2010

Die temperatursensitive Mutante ts 33‐6 von Bacillus subtilis SB 19 wächst bei 46 °C als Filament und bei 30 °C als normales Kurzstäbchen. Die wichtigsten Makromolekül synthesen der Mutante ts 33‐6 und des Wildstammes SB 19 verlaufen ähnlich.

In Rohextrakten aus Kurzstäbchen ist die Aminoacyl‐tRNS‐Synthetasen (AAS)‐Aktivität hoch, ein Nachweis dieser Enzyme in Rohextrakten aus Filamenten ist nicht möglich. Durch Temperaturwechselexperimente (Umsetzen wachstumsaktiver Filamente von 46 °C auf30 °C) wird Zellteilung induziert und die AAS‐Aktivität nimmt zu. Der Wildstamm B. subtilis SB 19 zeigt bei 30 °C und 46 °C AAS‐Aktivität. Eine Hemmung der AAS‐Aktivität durch Temperaturbehandlung in vitro (46 °C) gelingt bei 30 °C‐Rohextrakten der Mutante ts 33‐6 nicht, wenn das Enzym durch ATP und Aminosäuren geschützt wird. Durch Temperaturvorbehandlung der 30 °C‐Rohextrakte der Mutante ts 33‐6 steigt die AAS‐Aktivitätum 170%. Dieser Effekt kann bei Rohextrakten von Escherichia coli B und B. subtilis try nicht nachgewiesen werden.
Wirkungsmechanismus des systemischen Fungicids Carboxin
Authors: Lyr H. , Ritter G. , Casperson G.
Published: July 2010

The selective effect of oxathiin compounds (DCMO) on basidiomycetes does not depend on stronger accumulation of the fungicide by sensitive fungi. Uptake of DCMO is closely related to the lipid content of a fungus. It is shown by electron microscopy that within 120 min DCMO damages the mitochondrial system and the vacuolar membrane, while plasmalemma, nuclear membrane and ER remain unchanged.

In isolated mitochondria of sensitive fungi DCMO causes a similar inhibition of respiration as in whole cells. Succino‐dehydrogenase (SDH) is inhibited to the same extent, while NADH‐dehydrogenase is only weakly inhibited and malate‐dehydrogenase not at all. Inhibition of SDH is reduced with increasing temperature. Soluble SDH is insensitive to DCMO.

The point of attack of DCMO is considered to be SDH in situ or a closely following reaction.
Synthesis of inducible phospholipase A with antibacterial activity by Bacillus cereus
Authors: Gaál Vera , Ivánovics G.
Published: July 2010

Mitomycin C was added to cultures of Bacillus cereus growing exponentially. Mass lysis in cultures of all strains (altogether 12) ensued at reincubation was associated with liberation either of an antibacterial substance or a phage; lysates of two strains (W and V8) contained both phage and bacteriocin of high titre. Several characteristics of the antibacterial substance, released by these two strains, appeared to be identical with those of megacin A, a bacteriocin of Bacillus megaterium. Analysis of a homomolecular fraction of a purified active material resolved by gel electrophoresis suggested that the antibacterial substance is identical with phospholipase A.
Transductional analysis of resistance to lincomycin and erythromycin in Streptococcus pyogenes
Authors: Malke H.
Published: July 2010

From the group A streptococcal strain 56188, mutants were selected for resistance to lincomycin. Among these, two distinguishable classes occurred: whereas mutations assigned to the linA locus did not change the susceptibility to erythromycin and were transducible by phage A25, class B mutations conferred erythromycin cross‐resistance and failed to be transducible under the conditions employed. Corresponding findings have previously been made concerning the properties of mutants selected for resistance to erythromycin.

By two‐point transduction crosses, the eryA and linA loci were placed in the same linkage group, as defined by cotransfer with phage A25. A common feature of mutants carrying both an eryA and a linA mutation was the slower growth compared to that of the parental strains bearing either mutation alone. This interaction among eryA and linA mutations proved to be strongest in certain combinations which were phenotypically unrecognizable because the resultant strains failed to develop colonies under the conditions used. On the other hand, the mutations of the established double mutants did not interact with respect to their effect on the resistance characteristics of the strains, which were the simple addition of the effects of the single mutations. Both the linkage relationships and the phenotypic properties of the eryA and linA mutations suggested that they might occur in genes coding for ribosomal proteins.

Mutations carried out by the B classes of the erythromycin‐resistant and lincomycin‐resistant strains appeared to be located outside the eryA linA linkage group in region(s), the function of which is unknown.
Einbau von Thymin und Thymidin in die DNS von Proteus mirabilis
Authors: Störl K. , Venner H.
Published: July 2010

Wildtypzellen von Proteus mirabilis nehmen normalerweise Thymin gar nicht und Thymidin nur während einer relativ kurzen Inkubationszeit aus dem Kulturmedium auf. Der Einbau radioaktiver Präkursoren zur Markierung der DNS von Wildtypzellen ist jedoch nach Zugabe von Desoxypurinnucleosiden über einen großen Bereich der exponentiellen Wachstumsphase möglich. Für die Inkorporation von Thymin und Thymidin erwies sich Desoxyadenosin in einer Konzentration von 500 μg/ml als optimal. Die Verwertung von exogenem Thymidin für die DNS‐Synthese war jedoch im Vergleich zu Thymin effektiver.

Aus der Spezifität des Einbaus der Präkursoren in die DNS ergibt sich die Möglichkeit, sie nach Ablauf einer Vormarkierungsperiode zur Untersuchung der DNS‐Synthese‐Kinetik von P. mirabilis‐Wildtyp einzusetzen.

Die erhaltenen Ergebnisse zeigen, daß das Verhalten von P. mirabilis in wesentlichen Punkten in Bezug auf den Einbau von Thymin und Thymidin mit den von anderen Autoren bei Escherichia coli gewonnenen Resultaten übereinstimmt.
Estimation of the thickness of films used in electron microscopy
Authors: Weibull C.
Published: July 2010

Carbon films or thin sections of plastic materials were introduced into the electron beam of an electron microscope and the fraction of electrons scattered enough not to reach the fluorescent screen was estimated by means of the exposure meter of the microscope. The values obtained showed that a simple relationship existed between the fraction of electrons scattered and the thickness of the sections (films) as estimated with a microtome or otherwise. In this way, film thicknesses between about 5 and 130 nm can rapidly be estimated. However, when sectioned material is studied, areas free of embedded material must be present in the sections.
Zur Charakterisierung des Resistoflavin produzierenden Streptomyces‐Stammes sowie Isolierung und Eigenschaften des neuen Antibioticums
Authors: Bradler G. , Eckardt K.
Published: July 2010

Aus dem Mycel von Kulturansätzen einer Selektante des Streptomyces‐Stammes JA 3733 wurden durch Extraktion zwei Antibiotica gewonnen. Die Selektante JA 3733‐4/6/7‐1 steht nach Artvergleichen auf Grund ihrer morphologischen und physiologischen Merkmale der Species Streptomyces griseoflavus nahe und wird als Varietät Streptomyces griseoflavus (KRAINSKY) WAKSMAN et HENRICI var. jenensis nov. var. bezeichnet. Von den beiden isolierten Antibiotica erwies sich A 3733A als identisch mit Resistomycin. Das zweite Antibioticum ist neu und wurde Resistoflavin genannt. Resistoflavin ist antibakteriell und antiprotozoal wirksam.
Einfluß der Antibiotica Resistomycin und Resistoflavin auf Wachstum, Nucleinsäure‐ und Proteinsynthese von Bacillus subtilis
Authors: Haupt Ina , Eckardt K.
Published: July 2010

Resistomycin und Resistoflavin, zwei aus dem Streptomyces‐Stamm JA 3733 isolierte Antibiotica, hemmen das Wachstum von Bacillus subtilis 168 thy‐ind‐ schon bei sehr niedrigen Konzentrationen. Die minimale Hemmstoffkonzentration für Resistomycin liegt bei 10‐7 M, für Resistoflavin bei 3 × 10‐7 M. In niedrigen Konzentrationen wirken beiden Antibiotica bakteriostatisch, in höheren Konzentrationen baktericid. Die Untersuchungen über den Einfluß dieser Antibiotica auf die DNS‐, RNS‐ und Proteinsynthese haben gezeigt, daß von diesen drei Makromolekülsynthesen bevorzugt die RNS‐Synthese gehemmt wird.
Einfluß von Purin‐ und Pyrimidinderivaten auf die Prophageninduktion in Escherichia coli C600 T44
Authors: Noack D. , Klaus S.
Published: July 2010

The inducibility of the prophages λ+ and λ ind8 within the lysogenic, temperature sensitive strain E. coli C600 T44 can be influenced by precursors of nucleic acid metabolism or by substances chemically related to those. With an agar diffusion test 63 substances of this kind were tested both qualitatively and quantitatively. It was shown that there are substances with stimulating or inhibiting action, respectively, on the inducibility of prophages. Furthermore, the prophages λ+ and λ inds exhibit different reactions on the exposure of the respective lysogenic strains against some substances tested. A small selection of effective substances are moreover qualitatively tested on the nonlysogenic strain E. coli C600 T44 and on the lysogenic complex E. coli C600 T44 (λ ind‐) the prophage of which is known to be not inducible by UV light. The results are discussed in terms of a different sensitivity of the lambda phage repressors against intermediates of the nucleic acid metabolism. An immediate comparison between the action of test substances and control substances such as adenine. guanosine, chloramphenicol, and nalidixic acid is possible on each test plate.
Manganoxydierende Pilze II. Untersuchungen an Laboratoriumskulturen
Authors: Schweisfurth R.
Published: July 2010

Untersuchungen haben ergeben, daß eine Manganoxydation bei Pilzen meist nur in Gegenwart geringer Mengen von organischer Substanz stattfindet. Hierbei ist es gleichgültig, ob die organische Substanz als Pepton, Casamino acids oder Zucker gegeben wird. Zu hohe Mn++‐Konzentrationen (über 10–50 mg/l) haben überwiegend negativen Effekt auf die Bildung von Trockensubstanz. Eine deutliche Manganoxydation findet unter annähend autotrophen Bedingungen nicht statt; unter heterotrophen, nährstoffarmen Bedingungen wird in Gegenwart und bei Oxydation von Mn++ die Bildung von Myceltrockengewicht gefördert. Die Ergebnisse werden im Hinblick auf die Existenz von Metallogenium symbioticum diskutiert.
Cell wall growth during the cell cycle of Schizosaccharomyces pombe
Authors: Streiblová Eva , Wolf A.
Published: July 2010

Cell wall growth of an asynchronous culture of Schizosaccharomyces pombe was studied by fluorescence microscopy and time‐lapse cinematography. The cell wall growth of individual cells is a time‐ordered process which can be divided into 4 stages: post‐division stage, stage of growth initiation, stage of extension growth, and constant length stage. Different aspects of these stages are discussed. During the exponential phase of growth the population has a rather stable structure from the point of view of division scar numbers. The significance of the division scars for the study of cell wall growth and multiplication is discussed.