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  • 1985-1989  (4,011)
  • Inorganic Chemistry  (3,415)
  • Life Sciences (general)  (596)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 504-511 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Different methods of bubble-free oxygenation are discussed. Today, the surface oxygenation has lost its importance. Technically, membrane oxygenation methods are used in various fermentervolumes although the construction principles are quite complicated. The scale-up-potential is here very limited. On the other hand, the CHEMCELL-oxygenation is a simple method, safe in terms of sterility and applicable to all fermenter sizes common for cell culturing. A great benefit of this principle is that the amount of oxygenation is not dependent from the mixing parameters.
    Additional Material: 4 Ill.
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  • 2
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The knowledge of the upper limits of growth rate and cell density is necessary to define the maximum possible productivity of a growth process. After a brief survey of the theoretical basis of microbial growth in dependence of mass transfer of oxygen and rheological properties of fermentation medium recent experimental results on the influence of higher pressure in the fermenter, of different substrate and dissolved oxygen concentrations on growth rate and yield coefficients of methanol utilizing bacteria are presented. Also some correlations between cell concentration and viscosity of fermentation broth are considered.
    Additional Material: 5 Ill.
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  • 3
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The increased interest in large scale production of biologically active molecules, as for example monoclonal antibodys, hormones, proteins and enzymes, has stimulated a rapid development of different methods to cultivate eukaryotic cells. Further progress in this field of modern biotechnology is expected not only from the selection of more productive cell lines and more efficient cultivation techniques, but also from the improvement in new bioreactor design and operation, which guarantees increased productivity per unit volume and reduces the downstream processing. Most important factors for a new reactor design in future will be the energy- and mass transfer, shear stress and scaleability. The provision of an adequate oxygen supply to large scale reactors is the most critical barrier to scale up. If oxygen is limited in a small degree, the result is inhibition of cell density and cellular efficiency in the production of the desired biomolecules. In addition, when methodologies are used which allow high cell densities and high metabolic active cells, the oxygen transfer becomes more important and, at the same time, more difficult. Since direct sparging of air into the cell-containing medium causes problems such as shear forces and foaming, new, efficient methods in bubble free aeration must be utilized. A new aeration system is presented, which is suitable to bubble-free aeration as well to separation of microcarrier-anchered cells from the harvested medium when running in a continuous perfusion mode. The efficiency of the CHEMCELL System regarding aeration and cell retention is demonstrated by the growth kinetics of BHK 21-cells in batch and perfusion mode.
    Additional Material: 6 Ill.
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  • 4
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Following the introduction referring to the fundamental role of the oxygen supply and the meaning of measured values of diluted oxygen in liquid culture media commonly used strategies to avoid the oxygen limitation in aerated fermentations are summarized and validated with respect to their realization requirements. Furthermore, a new developed principle for the control of the p O2-value based on the growth regulating influence of the acidity (pH-value) without using the increase of the oxygen transport rate of the fermenter is discussed.
    Additional Material: 4 Ill.
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  • 5
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Three different instruments for the determination of turbidity in liquid media are described. The SLP-2 was developed for the control of high biomass concentrations in fermenters and is fitted with a self-cleaning mechanism. The SLP-3 is used for control of very small turbidities, e.g. in brewery products or in drinking water. The SLP-4 is designed for continuous measurement of higher turbidities in (waste) water or in different products flowing through pipe-lines. It may be used alternatively as a submerged probe.
    Additional Material: 2 Ill.
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  • 6
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Authors have studied the dependence of the physiological and biochemical characteristics of lysine producers Brevibacterium flavum on medium stirring intensity upon constant pO2 during fermentation processes. Various factors affecting the rate of biochemical reactions in cells upon a changeable intensity of medium stirring in apparata with turbine stirrers; oxygen mass transfer intensity in the system; stirring characteristics in the fermenter; biochemical changes in the cells due to gradients of energy introduced by the stirrer in the fermenter, etc. have been studied. A comparison of the experimentally established values, characterizing macrostirring (e) and microstirring (KR), with the physiological and chemical characteristics of bacteria during fermentation made us suppose that the character of the kinetic energy distribution in the volume of fermenter is one of the factors regulating bacterial metabolism. Besides, there exists the value ecrit, upon which there can be observed essential changes of the physiological and biochemical properties of the cells. The effect of medium flows upon the cells is characterized by index Fstress, which takes into account both, the possible presence of the cells in the zone with e ≧ ecrit, and the degree of medium flow and cell interaction, numerically equal to value (e - ecrit)0.5.
    Additional Material: 12 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 578-578 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 68-68 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 247-253 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The sorption capacity of silver on different biological materials has been investigated depending on physico-chemical pretreatments. The maximum silver loading values measured were compared with the values obtained with nontreated biomasses.The results show an increase of the loading capacity up to a factor of 10 in case of the alkalitreated biomasses. When the biomasses are extracted before being used as adsorbent with a solvent mixture of chloroform/methanol in a ratio of 2:1 the efficiency of the silver adsorbing power can be increased.Beyond that, the ability to adsorb silver can also be influenced when microorganisms are used as biocatalysts in a product synthesis before they are used as adsorbents. A strain of Acetobacter methanolicus possesses 1.8 times higher affinity to silver when it is employed in a process of gluconic acid production before adsorption. Physico-chemical pretreatments influence not only the loading capacity of the biological material, but also the contacting time required for the establishment of the adsorption equilibrium can be considerable reduced.
    Additional Material: 4 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 354-354 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 11
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Various nitrogen and carbon sources, as well as natural products, were examined as inducers of the production of amylases, proteases and pectinases by A. niger C. A. niger C grown on wheat bran extract medium provided culture supernatants with the highest enzymatic activities. Some culture conditions, e.g. pH, medium temperature and time period of cultivation, were optimalized to improve the growth and enzymes biosynthesis by A. niger C.
    Additional Material: 5 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 361-361 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 362-362 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 9-16 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Calcium in soymilk was increased to that of human milk by the addition of 0.2% calcium lactate. It was, however, impossible to raise the calcium content of soymilk to that of cow's milk. The maximum amount of calcium lactate that could be added to soymilk without coagulation of the milk protein was found to be 0.45% which resulted in about 75 mg of Ca/100 ml of soymilk. This amount was approximately 60% of the calcium in cow's milk. Sodium citrate had to be added in combination with calcium lactate to reinforce colloidal stability of the milk. The ratio of Ca to P in the milk containing added 0.45% calcium lactate was comparable to that of cow's milk and at the amount normally consumed daily by infants and children it seemed to meet the requirements of Ca and P.
    Additional Material: 3 Ill.
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  • 15
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The loss of fermentative activity of yeast cells, observed in continuous fermentation experiments at increasing biomass concentration is explained by the assumption that the ethanol-tolerance behaviour of the microorganisms changes if a growth-stabilizing factor limitation is present. A mathematical specification of the relationships existing in this context is given and an improved steady-state productivity model of ethanol production is derived.
    Additional Material: 3 Ill.
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  • 16
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: In growth-factor limited fermentations carried out in continuous high-flow rate fermenters the relationship existing between the specific ethanol formation rate and the ethanol concentration was found to change its characteristics from a linear function into a nonlinear one at high biomass concentrations. The deviation from the linear inhibitory behaviour of the cells was the greater the more the biomass concentration increased.A very good correspondence between the experimentally found productivities of ethanol formation and its adequate values obtained by calculation could be attained by using an improved steady-state productivity model, in which the variability of the function v = f(P) had been considered.
    Additional Material: 6 Ill.
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  • 17
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 18
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 99-110 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The fermentation pattern of cassava starch utilization was investigated at 37°C using Rhizopus oligosporus UQM 145 F and eight different media. Depending on the medium used, the addition of zinc or zinc plus iron to a combination of calcium plus manganese switches the fermentation from glucose accumulation to biomass (single cell protein) production. Complete starch hydrolyzation was obtained in both cases, with a complete glucose utilization resulting in 24 g biomass containing 30% true protein per 100 g cassava starch (= 7.45 g SCP/100 g substrate) in 24 hours. In the case of glucose accumulation, biomass was kept low and 15.5 g/l glucose representing 57.3% of starch supplied were obtained in 36 hours. R. oligosporus UQM 145 F grows well between 30° and 45°C. At 45°C and pH 5.0, 7.0 g SCP/100 g substrate were obtained, which rose to 8.6 g if cassava starch is replaced by ground cassava tuber.
    Additional Material: 3 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 149-156 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Studies on the pelletization of fungus Pleurotus ostreatus have established the pellets to differ as to the size, density and chemical composition. Changes in the pellets, taking place during culture growth, are helpful in studying the mode of their development. We have studied various conditions of cultivation, and established the factors enhancing culture growth. Prehomogenization of seeds, velocity of stirrer revolution, partial pressure of dissolved oxygen and that of other factors was established to affect the structure of pellets and parameters of culture growth.
    Additional Material: 9 Ill.
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  • 21
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 22
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 197-200 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method is described for storage of microbial strains. The microorganisms are mixed with a 10% solution of polyvinylalcohol and stored at 4°C. It is demonstrated that most microbial strains studied remained uncharged were stable for 1 year.
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  • 23
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 203-209 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two kinds of redox-potential changes were observed in batch cultures of E. coli, B. subtilis and B. megaterium with intensive aeration and pH maintenance at constant level: (i) a gradual decrease of the redox potential during continual bacterial growth as a result of interactions between platinum electrode and cell surface; (ii) the redox jumps in the generation of which the soluble redox substances take part under the conditions of different transitional processes (exhaustion of the sources of carbon, energy of nitrogen, metabolism switching from one source to another and so on). The redox monitoring may be useful for cultivation control in these situations.
    Additional Material: 5 Ill.
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  • 24
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 25
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 255-267 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new biotechnological process for sulphide removal is proposed. The process is based on the oxidation of sulphide into elemental sulphur, which can be removed by sedimentation. In this study it was found that elemental sulphur and sulphate are the main oxidation products of the biological sulphide oxidation. The settling characteristics become worse as the sulphide concentration increases, due to polysulphide formation. The start-up phase of this biological system is very short; Only four days are needed to reduce the sulphide concentration of 100 to 2 mg/l at a HRT (Residence time) of 22 minutes. Also some environmental factors were evaluated. The optimal pH is situated in the pH-range 8.0-8.5. Significantly lower conversion rates are found at pH = 6.5 to 7.5 and pH = 9.0, while at pH = 9.5 the sulphide oxidation capacity of the system detoriates. The process temperature was 20°C, although the optimal temperature is situated in the range 25-35°C. No substrate inhibition of sulphide was found at sulphide concentrations up to 100 mg/l.
    Additional Material: 8 Ill.
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  • 26
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 268-268 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 27
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 269-273 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: New insoluble chromolytic substrates for the determination of proteolytic activity were prepared by incorporation of dyed proteins into the structure of calcium sulphate dihydrate. The prepared substrates could detect approximately 0.25-1.0 μg of trypsin per ml. The spontaneous leakage of dyed substances in water solutions was negligible.
    Additional Material: 2 Ill.
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  • 28
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 294-294 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 29
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 30
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 295-298 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The aim of this work is to study the IR spectra of the different lignins precipitated from the produced liquor of different pulping conditions of bagasse and cotton stalks, also to study their antimicrobial activities towards some bacteria and fungi.
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  • 31
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Chlorinated aromatic hydrocarbons are widely used in industry and agriculture, and comprise the bulk of environmental pollutants. Although simple aromatic compounds are biodegradable by a variety of degradative pathways, their halogenated counterparts are more resistant to bacterial attack and often necessitate evolution of novel pathways. An understanding of such evolutionary processes is essential for developing genetically improved strains capable of mineralizing highly chlorinated compounds. This article provides an overview of the genetic aspects of dissimilation of chloroaromatic compounds and discusses the potential of gene manipulation to promote enhanced evolution of the degradative pathways.
    Additional Material: 5 Ill.
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  • 32
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 383-387 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: UV/VIS diffuse reflectance spectroscopy and fluorescence spectroscopy have been used to investigate the cytochrome and pyridine nucleotide spectra during aerobic biomass growth of Saccharomyces cerevisiae followed by an anaerobic ethanol formation process. The cytochrome and NAD(P)H spectra are closely related to fermentation parameters such as biomass growth rate and ethanol concentration.
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  • 33
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 388-388 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 34
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 389-391 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: At late stages of development of surface cultures streptomycetes producing anthracycline antibiotics were shown to form secondary colonies on PRIDHAM & GOTTLIEB'S medium with xylose. Stable variants obtained from them possessed an increased biological activity (by a factor of 2-3 times) due to the accumulation of amounts of antibiotically active anthracyclines.
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  • 35
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 36
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 37
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 38
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 39
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 40
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 3-8 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Although the regulation of microbial secondary metabolism belongs to the important objects of actual investigations the results and knowledges are used rather poorly in industrial fermentations. This situation arises from the discrepancy between the economically driven development of the know how as soon as possible contrary to the more slow progress of profound examination of the complicated network of secondary metabolism. Nevertheless some well known principles of metabolic regulation, e.g. catabolite repression or resistance against products or metabolites are considered in fermentation processes by means of suitable substrate application as well as improvement of high yield strains. Both aspects are discussed with respect to examples of fermentations of β-lactams, polyketides and glycopeptides.
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  • 41
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 43-48 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fed-batch cultivation of Methanobacterium formicicum Z-281 was performed under substrate limiting conditions. Specific rate of culture growth amounted to 0.041 h-1, cell yield related to substrate was 0.6 mg proteine/mM formate. Significant increase of coenzyme F420 content in cells depending on time of cultivation was observed. Increase of the fluorescence intensity of the medium was also observed with the accumulation of biomass. These parameters were suggested for tracking culture growth. The possibility of application of fluorescent factors for methanogenic population control in the anaerobic digester is discussed.
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  • 42
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Study was made of the effect of medium humidity, source and dose of nitrogen, dose of phosphorus, dose of inoculum and aeration on protein biosynthesis by strain Aspergillus oryzae A. or. 11 in solid state fermentation. It was found that for a maximal protein yield the medium ought to contain about: 60% of water, 36% of starchy raw materials d. m. (e.g. 28.8% of coarse rye meal and 7.2% of beet pulp), 0.85% of nitrogen sources (1.6% of (NH4)2SO4 and 1.1% of urea), and 0.35% of phosphorus source (1.3% of KH2PO4). pH of medium should be near 6.5. The dose of inoculum should not be lower than 108 spores/100 g medium.The duration of culture ought to be 20-22 h at 30-35°C, with aeration at least 40 dm3 of air/h × 1000 g medium. Under these conditions the protein yield is about 6.0-6.3 g/100 g of starting medium d.m. at the cost of utilization of about 25 g total carbohydrates.
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  • 43
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 49-54 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The best proteolytic productivity of Pseudomonas fluorescens was observed when maltose and 5% peptone were in the medium. The optimal temperature was found to be 28°C.The pH values in the range of 4.0 to 8.6 have not influenced the enzyme production.The best proteinase cell activity (A) was in the early stage of culture (24-48 hours).
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  • 44
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 55-62 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method for the analysis of distributed growth of E. coli in k-carrageenan gel is described. The method uses optical and electron microscopy to determine morphometric data of cell microcolonies in the gel, such as average microcolony volume, distance of microcolonies to gel surface and cell density in the microcolonies. Logarithmic equations describing the distribution of authentic values of volume occupied by cells in gels at different times of incubation were determined. With these equations it is possible to predict the quantitative distribution of cells in the gel and to define some parameters. These parameters can characterize the growth behaviour of the microbial strains in any particular culture condition and can be useful in the future search to improve the industrial applications of immobilized cells.
    Additional Material: 4 Ill.
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  • 45
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 63-67 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A hydrocarbon utilizing strain of Micrococcus varians 2Fa isolated from local soil has been found to yield lysine 2.6 g l-1. Addition of B-vitamins and trace elements to the optimal media, has been found to stimulate growth and enhance lysine yield.
    Additional Material: 2 Tab.
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  • 46
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 110-110 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 47
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 111-121 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Measurements of liquid macromixing characteristics are reported for a half industrial scaled jet loop reactor operating with air-water mixtures. Based on a model of loop reactors with sections of different mixing behavior the single circulation dispersion coefficient can be split into its components caused by the riser and the downcomer. The dispersion coefficient of the riser is about 100 times greater than that of the downcomer. The addition of gas involves greater dispersions coefficients. The comparison of the mixing times of the JLR with those of stirred vessels leads to the conclusion that the JLR is equivalent or even superior to stirred vessels.
    Additional Material: 11 Ill.
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  • 48
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 49
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 50
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 143-148 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nine Candida species isolated from fleshy fruits have been examined for their organic growth factor requirements. Complete or partial deficiencies for thiamine, biotin, pyridoxine, inositol, pantothenic acid, ascorbic acid and xanthine have been reported in C. catenuclta, C. curiosa, C. curvata, C. humicola, C. rhagii, C. steatolytica and C. tropicalis. Only two species, namely, C. fragicola and C. ishiwadea were prototrophic for the growth factors. Concentrations of essential growth factors higher than the optimum have been found inhibitory for the growth of yeasts.
    Additional Material: 1 Ill.
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  • 51
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 179-190 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The cellulase complex of the fungus Aspergillus niger (strain CBS 554.65 = ATCC 16 888) was fractionated by gel filtration yielding six pronounced peaks. Only proteins from the fraction corresponding to the first peak (96 kDa) showed β-glucosidase activity vs. the substrate 4-nitrophenyl-β-D-glucopyranoside (pNPG). These proteins have been fractionated by chromatofocusing, yielding two β-glucosidases (I and II) which are shown to be homogeneous in isoelectric focusing experiments (pI = 4.6 and 3.8, respectively). Kinetic experiments with pNPG, MU-glucopyranoside and cellobiose revealed that both types of β-glucosidases behave like aryl-β-glucosidases. β-Glucosidase-I acting on pNPG exhibits a split kinetics characterized by high and low substrateconcentration kinetics which are differentiated by different values of V and of Km. In addition, β-glucosidase-II is shown to be an exo-glucohydrolase as deduced from experiments with MU-cellobiopyranoside.Experimental features should be emphasized; usual soft-gel ion-exchange materials did not work in the chromatofocusing separation of the two β-glucosidases, in contrast to the 10μ-Si 500 = DEAE exchange material (Serva) typically used in HPLC-experiments. Furthermore, protein content determinations based on different procedures yielded widely differing values.
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  • 52
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 227-232 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The oxygen requirements of Aspergillus awamori as well as the adaptation to it and the aeration of the cultivation medium were determined in the process of glucoamylase synthesis. Under the selected agitation and aeration conditions (impeller-tip speed = 4.2 m/s; aeration 1.5 vvm) the cultivation-medium aeration was analysed by means of dissolved-oxygen-concentration measurement during the course of the process. It was demonstrated that for obtaining the glucoamylase-activity level of 800 U GA/cm3 under the selected conditions and with the fungus applied the dissolved-oxygen concentration at the level of 25% saturation should be maintained. Those findings could serve as auxiliary indexes in the scale-up process of glucoamylase synthesis.
    Additional Material: 3 Ill.
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  • 53
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 239-246 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Four silica supports differing in pore dimensions were activated by treatment with SiCl4 and then with ethylenediamine to obtain alkylamine groups on the silica surface. Three enzymes, peroxidase from cabbage, glucoamylase from Aspergillus niger C and urease from soybean were immobilized on these supports using glutaraldehyde as coupling agent. It was found that the protein content, the retained enzymatic activity and the storage stability of the silica supported enzymes were considerably affected by support pore size and enzyme molecular weight, the factors which are supposed to alter protein distribution inside the support pores. The highest activity was found for peroxidase and glucoamylase attached to the silica with the widest pores, but their loss in activity during storage was considerable. The urease retained less activity after immobilization, but its storage stability was excellent.
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  • 54
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 324-324 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 55
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of the culture method in solid medium and the influence of starch-containing raw materials on the yield of fungal protein biosynthesis were studied. Three procedures (laboratory bioreactor method, tray method and pile method) gave satisfactory results. Protein yields amounted to 5.0-5.9 g/100 g of starting medium d.m. upon utilization of 20.9-24.1 g carbohydrates. The procedure involving the use of a fermenter with a mixer afforded protein yields by about 50% lower as compared with the three above-mentioned procedures, and therefore it requires technical improvement.As a result of fungal culture using various starch-containing raw materials, the protein content in post-culture products increased by 46-88%, as compared with starting medium. The contents of 13 amino acids (including some exogenous ones which increased by 52-82%) in post-culture products substantially rose (by 34-63%). The post-culture products exhibited proteolytic activity (1260-3500 HU/g of d.m.).The kind of the source of starch evidently influenced protein biosynthesis. Media based on potatoes afforded the greatest increases in protein (5.8-5.9 g/100 g of starting medium d.m.), and those containing coarse rye meal and milling by-products  -  the smallest ones (4.5-4.6 g/100 g of starting medium d.m.).
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  • 56
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    Acta Biotechnologica 9 (1989), S. 325-332 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the present work, a mathematical model was developed regarding the immobilized living yeast cell reactor for sugar bioconversion to ethanol. The model, composed of a system of ordinary differential equations (ODEs) enables the computation of the paramters involved in the steady state reactor behaviour. Comparing the values computed through the integration of this mathematical model with the experimental data, it has been shown its capacity to describe sufficiently accurate the steady state behaviour of the continuous fixed film bioconversion reactor.
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  • 57
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 346-346 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 58
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 333-346 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A survey is given summarizing recent insights into the causes of the genetic segregation of antibiotic-producing Streptomyces strains (plasmids, transposons, reiterated gene sequences, direct and inverted repeats). Referring to the classical regulatory models of prokaryotic operons, similar regulatory principles were shown to be involved in the secondary metabolism (pab-gene of S. griseus, brp-gene of S. hygroscopicus, afs B-gene and A-factor of S. griseus) and the known features of its control by catabolites as well. The heterogeneity of the transcriptional system (multiple promotors and holoenzymes of the RNA polymerase) is shown to constitute an essential element of the secondary metabolism accomplishing its integration into cellular cytodifferentiation.
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  • 59
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 353-353 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 60
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    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Penicillium funiculosum NRRL 13033 produced β-glucosidase and β-xylosidase activities when grown on wheat straw. The addition of some inducers (individually or in combination) to the fermentation medium were tested for the production of both enzymes. The relation of mycelial bound enzyme to cell free enzyme was studied during incubation period of fermentation. The optimum activity of β-glucosidase and β-xylosidase were found to be in the pH 4.5 using phosphate-citrate buffer at 50°C for 60 min and at 55°C for 40 min respectively. β-Glucosidase lost about 40% of its original activity by heating to 65°C for 60 min, while, β-xylosidase activity was found to be nearly stable with the same treatment. Both enzyme activities were greatly inhibited when 1.0% (w/v) of xylose and glucose were added to the assay mixture.
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  • 61
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    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Kluyveromyces bulgaricus protoplast formation was studied by the determination of the remaining intact cells with the Coulter counter, the decrease of the absorbance of the cell suspension upon dilution into an hypoosmotic medium and the liberation of intracellular proteins after protoplast lysis. Due to the scattering of light by cells and ghosts, spectrophotometric readings were not enough specific and led to the underestimation of the reaction rates (about 40% less). The Coulter counter technique and the determination of the liberation of intracellular proteins gave the same rates over a large range of cell concentrations and in the presence of various cell lytic enzymes. The importance of corrected etermination of the time course of the reaction was illustrated by the good correlation obtained between protoplast formation and ATP turnover.
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  • 62
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 368-368 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 63
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 377-377 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 64
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 369-377 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A bioelectrode consisting of two parallel noble metal nets and a thin layer of gel-entrapped urease between them permits to determine urea conductimetrically with a response time 3-5 min and reproducibility 5-6% above 60 micromolar concentration of urea. Differential measurement eliminates the interference due to conductive components of the real sample. Evidence has been obtained for extended application of the method by using immobilized microbial cells or tissue slice as biocatalyst in place of the immobilized purified enzyme. It is also suitable for simple kinetical assaying arginase activity in the tissue extracts.
    Additional Material: 7 Ill.
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  • 65
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 378-378 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 66
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 379-382 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ammonium and phosphate ions added to water extracts of juniper berries in optimum concentrations of about 70 and 35 mM, respectively, ensure a maximum ethanol yield of about 90% of the theoretical one in 16-18 hour fermentation. Magnesium ions have a slightly negative effect on the ethanol yield.
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  • 67
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    Acta Biotechnologica 9 (1989), S. 387-387 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 68
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 392-392 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 69
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 70
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    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 395-419 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Any bacterial strain can be infected by virulent phages or harbour one or more prophages. Therefore, bacteria-phage interactions are to be regarded as fundamental properties of bacteria. In current industrial fermentation processes phages can be advantageously employed for the identification of bacterial production strains (phage typing). In some cases phages are involved in the production of enzymes and special substances. The fundamental importance of phages in any technical fermentation process, however, is based on the peculiarities of their obligately parasitic life cycle. The propagation of phages in fermentation processes can cause complete (or at least partial) lysis of the production strains and, consequently, serious disturbances in the production process and considerable economic losses. The phage problem in the fermentation industry has not yet been completely solved. For the protection of technical processes against virulent phages five measures are discussed: phage-protected sterile fermentation, employment of alternative cultures, employment of phage-resistant mutants, employment of phage inhibitors, and employment of immobilized bacterial cells. The problem of the protection of bacterial production strains from prophage induction is more difficult and practically unsolved. Two possibilities to minimize the process risk due to temperate phages, the elimination of inducing factors during the fermentation process, and the selection of production strains which are difficult to induce, are discussed.
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  • 71
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    Acta Biotechnologica 9 (1989), S. 431-439 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The shape of the temperature profile curve of ethanol production changes in the presence of ethanol. So the characteristic points of the curve are shifted to lower values at increasing ethanol concentrations. As a reason for it the potentiation of thermal deactivation effects by ethanol already at lower temperatures is assumed. Compared to it, the activation energy of ethanol for mation in the suboptimal temperature range was found to be unaffected by alcohol.
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  • 72
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    Acta Biotechnologica 9 (1989), S. 421-430 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The efficiency of carbon substrate utilization is evaluated as the thermodynamic efficiency (ηx) of microbial growth.Three methods based on mass-energy balance are used for the efficiency studies of complex substrates (straw, plant juices, lye) utilization by microfungi Trichoderma viride.1According to substrate and biomass balance ηx = 0.55, 0.37 and 0.36 for Trichoderma viride growth on alkali pretreated wheat straw during 23, 34 and 50 hours. Cellulose biodegradation increases with cultivation time. However, the efficiency of cellulose utilization for cell mass growth decreases at the same time.2In accordance with oxygen-balance calculations ηx = 0.75 and 0.71 for the same processes. The discrepancy in results from the above two methods probably can be explained by the following: ASubstrate and biomass balance gives underestimated results.BOxygen balance method includes the part of energy for extracellular product formation and therefore ηx can be overestimated.CThe efficiency of complex soluble substrate utilization (lye, green juice, deproteinized brown plant juice) tested by means of pulse method gives the values of ηx = 0.72 - 0.88. Similar high estimates of ηx in C-limited batch culture are observed for soluble carbohydrates (glucose, galactose, lactose, xylose) but not for acetate. The pulse method is advantageous for testing the “true” efficiency of carbon substrate utilization in a definite physiological environment.
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  • 73
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    Acta Biotechnologica 9 (1989), S. 477-477 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 74
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    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 572 (1989), S. 89-94 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: About New Oxochromates: SrCr10O15 and BaCr10O15 Containing Divalent Chromium: MCr22+Cr83+O15High temperature reaction using reducing atmosphere lead to the new compounds (I) SrCr10O15 and (II) BaCr10O15. Single crystal X-ray investigations show orthorhombic symmetry: space group D2h18-Ccmb; I: a = 10.059; b = 11.406; c = 9.224 Å; II: a = 10.126; b = 11.491; c = 9.392 Å; Z = 4. Cr2+/Cr3+ are octahedral coordinated by O2-. Inside a CrO6-octahedral network are cavities comparable with those of some polyacids filled by Sr2+ or Ba2+ ions.
    Notes: Mit Hochtemperaturreaktionen in reduzierender Atmosphäre gelang die Darstellung der gemischtvalenten Oxochromate(I) SrCr10O15 und (II) BaCr10O15. Diese kristallisieren orthorhombisch, Raumgruppe D2h18-Ccmb mit (I): a = 10,059; b = 11,406; c = 9,224 Å und II: a = 10,126; b = 11,491; c = 9,392 Å; Z = 4. Cr2+/Cr3+ bilden mit O2- ein Oktaedergerüst, je 12 Oktaeder bauen wie bei Polysäuren für Sr2+ bzw. Ba2+ einen großvolumigen Hohlraum auf.
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  • 75
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    Zeitschrift für anorganische Chemie 572 (1989), S. 109-114 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: BaNi2In4Sc4O15 with BaV10O15-Structure, but Ordered Metal DistributionSingle crystal X-ray investigations of BaNi2In4Sc4O15 [space group D2h18-Cmca, a = 12.146; b = 10.880; c = 9.834 Å; Z = 4] show a statistical distribution of Ni2+ and Sc3+ of one of the possible point positions. The other oxygen octahedra are occupied by In3+ and Sc3+. This is the difference to compounds of the formula BaM10O15 (M = V, Cr, Ni/Cr) with total statistical metal distribution.
    Notes: Einkristalluntersuchungen an BaNi2In4Sc4O15 [Raumgruppe D2h18-Cmca. a = 12,146; b = 10,880; c = 9,834 Å; Z = 4] zeigen, daß Ni2+ nur mit Sc3+ eine der oktaedrisch koordinierten Metallpunktlagen statistisch besetzt. Alle anderen Polyeder sind frei von Ni2+, womit diese Verbindung sich von den Oxiden BaM10O15 (M = V, Cr, Ni/Cr) mit total statistischer Metallverteilung unterscheidet.
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  • 76
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 572 (1989), S. 102-108 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Contribution on the Crystal Chemistry of Oxotantalates. V. Ordered and Disordered Metal Distributions in MnZn2Ta2O8 and Mn0.33Zn0.67Ta2O6The compounds (I) MnZn2Ta2O8 and (II) Mn0.33Zn0.67Ta2O6 were prepared by solid state reactions. Single crystal X-ray investigations show (I): a = 19.286; b = 5.922; c = 5.228 Å; β = 90.3°; Z = 4; space group C2h6-C2/c; (II): a = 4.730; b = 17.154; c = 5.093 Å; Z = 4; space group D2h14-Pbcn. I belongs to the Zn3Nb2O8-type with ordered Mn2+, Zn2+ distribution. II crystalizes like tri-α-PbO2 (for example ZnTa2O6) but in respect to the metal distribution it belongs to the disordered α-PbO2-type.
    Notes: Mit Hilfe von Festkörperreaktionen wurden (I) MnZn2Ta2O8 und (II) Mn0,33Zn0,67Ta2O6 einkristallin dargestellt. [(I): a = 19,286; b = 5,922; c = 5,228 Å; β = 90,3°; Z = 4; Raumgruppe C2h6-C2/c; (II): a = 4,730; b = 17,154; c = 5,093 Å; Z = 4; Raumgruppe D2h14-Pbcn] I gehört zum Zn3Nb2O8-Typ mit geordneter Mn2+,Zn2+-Verteilung. Die Verwandtschaft zum Columbit wird aufgezeigt. II kristallisiert wie tri-α-PbO2 (z. B. ZnTa2O6), allerdings mit einer ungeordneten Metallverteilung, womit sie kristallchemisch zur α-PbO2-Struktur gehört.
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  • 77
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 572 (1989), S. 126-134 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Chalcogenolates. 192. S-Bis(trimethylsilyl)amino Esters of Dithiocarbamic Acids. 1. Synthesis and PropertiesThe title compounds RR′N—CS—S—N[Si(CH3)3]2, where R = R′ = CH3, C2H5, CH(CH3)2, CH2—C6H5, and with R = CH3 and R′ = C6H5 have been prepared by three procedures: by splitting the S—S bond of disulfanes [RR′N—CS—]2S2 with Na[N(Si(CH3)3)2] and with [(CH3)3Si]2N—MgBr as well as by reaction of Na[S2C—NRR′] with BrN[Si(CH3)3]2. The yields are compared.Physical and chemical properties are described, mass spectra are given.
    Notes: Die Titelverbindungen RR′N—CS—S—N[Si(CH3)3]2 mit R = R′ = CH3, C2H5, CH(CH3)2 und CH2—C6H5 sowie mit R = CH3 und R′ = C6H5 wurden nach drei Verfahren hergestellt: durch Spaltung der S—S-Bindung von Disulfanen [RR′N—CS—]2S2 mit Na[N(Si(CH3)3)2] und mit [(CH3)3Si]2N—MgBr sowie durch Reaktion von Na[S2C—NRR′] mit BrN[Si(CH3)3]2. Die Ausbeuten werden verglichen.Physikalische und chemische Eigenschaften sowie Massenspektren werden mitgeteilt.
    Additional Material: 5 Tab.
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  • 78
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 573 (1989), S. 12-18 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Oxoindate Ba4In2O7Ba4In2O7 was prepared for the first time by solid state reaction and investigated by X-ray methods. (Space group D4h17-14/mmm, a = 4.175; c = 29.483 Å; Z = 2). It shows a close crystal chemical relationship to Ba3In2O6 and La2SrCu2O6. One of the oxygen point positions is occupied only by a half. This fact alleviates the understanding of the layer structure of Ba4In2O7. The compound is compared with Sr4Tl2O7 and a further discussion in respect to Ba5In2O8 shows the probable identity of Ba5In2O8 with Ba4In2O7.
    Notes: Ba4In2O7 wurde erstmals dargestellt und an Einkristallen mit Röntgenbeugungsmethoden untersucht. (Raumgruppe D4h17-14/mmm, a = 4,175; c = 29,483 Å; Z = 2). Es liegt eine enge kristallchemische Verwandtschaft zu Ba3In2O6 und z. B. La2SrCu2O6 vor. Eine der Sauerstoffpunktlagen ist nur zur Hälfte besetzt; das macht den Schichtstrukturaufbau verständlich. Ba4In2O7 wird mit Sr4Tl2O7 verglichen. Eine Diskussion zeigt, daß Ba5In2O8 vermutlich mit Ba4In2O7 identisch ist.
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  • 79
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    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 573 (1989), S. 19-23 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: About an Oxotantalate with Partly Ordered Corundum-Structure: Mn0.6Mg3.4Ta2O9In the system of mixed crystals of the composition Mn4-xMgxTa2O9 single crystals with x = 3.4 were examined by X-ray methods (space group D43d-P3c1; a = 5.2141; c = 14.178 Å; Z = 2). The point positions of the divalent metals are occupied in an ordered manner. Order and disorder are discussed in respect to Mn2Zn2Nb2O9, Mn3ZnNb2O9, and oxotantalates (MM′)4Ta2O9 [M, M′ = Zn, Ni, Mg].
    Notes: Im System Mn4-xMgxTa2O6 wurden Einkristalle für x = 3,4 mit Röntgenbeugung untersucht (Raumgruppe D43d-P3c1, a = 5,2141; c = 14,178 Å, Z = 2). Mn2+ und Mg2+ besetzen die entsprechenden Metallpunktlagen partiell geordnet. Der Grad der Ordnung wird im Vergleich zu Mn2Zn2Nb2O9, Mn3ZnNb2O9 und den Oxotantalaten (MM′)4Ta2O9 [M, M′ = Zn, Ni, Mg] diskutiert.
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  • 80
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 573 (1989), S. 63-74 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ligand Exchange on Halogenonitrosyl-technetate(II) Compounds. An EPR StudyHalide ligand exchange reactions on the 4t52g low-spin halogenonitrosyltechnetate(II) complexes (n-Bu4N)2[Tc(NO)Cl5], (n-Bu4N)[Tc(NO)Br4], and (n-Bu4N)[Tc(NO)I4] have been analyzed by EPR. The EPR parameters go, aTco, ‖ and A‖Tc measured for the different mixed-ligand complexes of the type [Tc(NO)X4-pYpZ]2- (X, Y-Cl, Br, I; Z - axially coordinated solvent molecule or halide) are shown to be clearly correlated to the composition of the coordination sphere and can be used to characterize the mixed-ligand complexes unambiguously.
    Notes: Es wird über EPR-Untersuchungen zum Halogen-Ligandenaustausch an den 4t52g-„low-spin“-Halogenonitrosyltechnetat(II)-Komplexen (n-Bu4N)2[Tc(NO)Cl5], (n-Bu4N)[Tc(NO)Br4] und (n-Bu4N)[Tc(NO)I4] berichtet. Die Spektrenparameter go, aTco,g‖ und A‖Tc der verschiedenen beobachteten Gemischtligandkomplexe des Typs [Tc(NO)X4-pYpZ]2- (X, Y-Cl, Br, I; Z - axial koordiniertes Solventmolekül bzw. Halogenid) zeigen eine definierte Abhängigkeit von der Zusammensetzung der Koordinationssphäre und erweisen sich für die eindeutige Charakterisierung von Gemischt-Ligandenkomplexen als geeignet.
    Additional Material: 6 Ill.
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  • 81
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    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 573 (1989), S. 75-88 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Chalcogenolates. 193. S-Bis(trimethylsilyl)amino Esters of Dithiocarbamic Acids. 2. Spectroscopic CharacterizationElectron absorption, infrared, and nuclear magnetic resonance spectra (1H, 13C, 29Si, 15N) of the title compounds RR′N—CS—S—N[Si(CH3)3]2 with R = R′ = CH3, C2H5, CH(CH3)2, CH2—C6H5 as well as with R = CH3 and R′ = C6H5 are communicated and discussed.Coupling constants have been determined (data see „Inhaltsübersicht“).For the compound with R = R′ = CH3 the free activation energy of the rotation barrier around the N—CS bond is ΔG* = 58 kJ/mol at -2°C (coalescence temperature).
    Notes: Elektronenabsorptions-, Infrarot- und Kernresonanzspektren (1H, 13C, 29Si, 15N) der Titelverbindungen RR′N—CS—S—N[Si(CH3)3]2 mit R = R′ = CH3, C2H5, CH(CH3)2, CH2—C6H5 sowie mit R = CH3 und R′ = C6H5 werden mitgeteilt und diskutiert.Folgende Kopplungskonstanten wurden ermittelt (R = R′ = CH3):\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} ^{\rm 1} {\rm J}\left({{}^{\rm 1}{\rm H} - {}^{12}{\rm C}} \right) = 119{\rm Hz},{}^2{\rm J}({}^1{\rm H} - {}^{29}{\rm Si} = 6,5{\rm Hz}, \\ ^{\rm 1} {\rm J}\left({{}^{{\rm 13}}{\rm C} - {}^{12}{\rm Si}} \right) = 57,7{\rm Hz},{}^2{\rm J}({}^{13}{\rm C} - {}^{15}{\rm N} = 1,97{\rm Hz}, \\ ^{\rm 1} {\rm J}\left({{}^{{\rm 29}}{\rm Si} - {}^{15}{\rm N}} \right) = 8,97{\rm Hz},{}^3{\rm J}({}^{15}{\rm N} - {}^1{\rm H)} \approx 0,5{\rm Hz}{\rm .} \\ \end{array} $$\end{document}Für die Verbindung mit R = R′ = CH3 beträgt die freie Aktivierungsenergie der Rotationsbarriere um die N—CS-Bindung ΔG* = 58 kJ/mol bei der Koaleszenztemperatur (-2°C).
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  • 82
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    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 573 (1989), S. 107-118 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: „LaTa5O14“, a Derivative of the Tetragonal Tungsten Bronzes. Preparation and Structure„LaTa5O14“ single crystals were synthesized for the first time by heating mixtures La2O3/Ta2O5 (1:5) at temperatures of T = 1 685°C in air. „LaTa5O14“ crystallizes in the orthorhombic space group Cmmm with a = 16.977(1) Å, b = 17.594(1) Å and c = 3.8480(4) Å. The structure was refined to give R = 6.36% and Rw = 3.27%. The Ta atoms are partly surrounded by O octahedrally, partly pentagonal-bipyramidal. The unit cell is built up by layers of composition [Ta22O62]14- connected along the [001] direction with holes filled up totally or partly with La. The relationship to the tetragonal tungsten bronzes will be discussed.
    Notes: Im System La2O3/Ta2O5 gelang erstmals die Darstellung von gelben „LaTa5O14“-Einkristallen durch Tempern der Gemenge La2O3/Ta2O5 (1:5) bei T = 1 685°C an Luft. „LaTa5O14“ kristallisiert orthorhombisch in der Raumgruppe Cmmm mit den Gitterkonstanten a = 16,977(1) Å, b = 17,594(1) Å und c = 3,8480(4) Å. Die Struktur wurde bis R = 6,36% bzw. Rw = 3,27% verfeinert. Ta(1), Ta(3) und Ta(4) sind oktaedrisch, Ta(2) ist pentagonal-bipyramidal von O umgeben. Schichten aus diesen Polyedern sind über O-Teilchen entlang [001] miteinander eckenverknüpft. Vom Ta-O-Netzwerk der Zusammensetzung [Ta22O62]14- gebildete Lücken sind ganz oder teilweise mit La-Teilchen gefüllt; die Verbindung besitzt deshalb nur annähernd die Zusammensetzung LaTa5O14. Eine Verwandtschaft zu den tetragonalen Wolframbronzen ist erkennbar.
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  • 83
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    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 573 (1989), S. 119-127 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: High Resolution Electron Microscopy Investigation of La3TaO5(OH)Cl3 and Pr3TaO4Cl6 - A Comparison with Calculated ImagesThe phases La3TaO5(OH)Cl3 and Pr3TaO4Cl6 prepared by chemical transport have been investigated by high resolution electron microscopy. The micrographs taken agree well with simulated images. In spite of the close relationship of both structures the simulated images are not as similar as expected. The unoccupied channels at the corners of the cell can be seen distinctly. According to the resolution of our electron microscope La3TaO5(OH)Cl3 lattice constants of which are too small does not show any further detail, whereas the sites of the heavy atoms of Pr3TaO4Cl6 can be recognized at a suitable value of defocus.
    Notes: Kristalline Proben von La3TaO5(OH)Cl3 und der neuen Verbindung Pr3TaO4Cl6 konnten durch eine chemische Transportreaktion erhalten werden. Bei elektronenmikroskopischen Untersuchungen in Hochauflösung zeigten die Aufnahmen eine gute Übereinstimmung mit Bildern, die mit einem Kontrastprogramm simuliert worden waren. Wie eine Gegenüberstellung von zwei simulierten Defokusserien ergab, ist die enge strukturelle Verwandtschaft der beiden Oxidchloride hier nicht unmittelbar wiederzufinden. Man erkennt bei beiden Verbindungen die an den Eckpunkten der Zelle gelegenen unbesetzten Kanäle, die sich deutlich vom übrigen Kontrastmuster abheben. Bei La3TaO5(OH)Cl3, der Verbindung mit den kürzeren Gitterkonstanten, reichte das Auflösungsvermögen unseres Mikroskops für weitere Details im Innern der Elementarzelle nicht aus, während bei Pr3TaO4Cl6 die Schweratomlagen bei geeigneten Defokusbedingungen noch zu erkennen sind.
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  • 84
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    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 573 (1989), S. 133-142 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Oxotellurates(VI) of the Alkali Metals. Existence and Constitution of Li6TeO6For the first time Li6TeO6 is prepared as transparent, colourless single crystals, and the structure has been determined [four-circle diffractometer data, Siemens AED2, MoKα, 371 out of 371 IO(hkl), R = RW = 0.7%, R3, a = 791.99(6) pm, c = 696.44(7) pm, Z = 3].The structure refinement shows that Li6TeO6 is a variant of the NaCl-Typ. Nevertheless there is a relationship with α-Li6UO6 [2]. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, the latter derived from Mean Effective Fictive Ionic Radii, MEFIR, are calculated and discussed.
    Notes: Erstmals wurden klar durchscheinende, farblose Einkristalle von Li6TeO6 dargestellt und strukturell untersucht. [Vierkreisdiffraktometerdaten, Siemens AED2, MoKα-Strahlung, 371 von 371 IO(hkl), R = RW = 0,7%, R3, a = 791,99(6) pm, c = 696,44(7) pm, Z = 3].Die Strukturbestimmung zeigt, daß Li6TeO6 eine Variante des NaCl-Typs ist. Dennoch besteht Verwandtschaft mit α-Li6UO6 [2]. Der Madelunganteil der Gitterenergie, MAPLE, sowie Effektive Koordinationszahlen, ECoN, diese über Mittlere Effektive Ionenradien, MEFIR, werden berechnet und diskutiert.
    Additional Material: 12 Ill.
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  • 85
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    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 573 (1989), S. 157-169 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Two New Variants of the NaCl Type of Structure: On Li4MoO5 and Li4WO5For the first time in form of colourless, transparent single crystals of Li4MoO5 [annealed mixtures of Li2O and MoO3, Li:Mo = 4.2:1, Ni-cylinder, 950°C, 28 d] as well as Li4WO5 [annealed mixtures of Li2O and WO3, Li:W = 4.4:1, Au-tube, 950°C, 28 d, slowly cooling] have been prepared. Single crystal data show isotypic oxides of the Li4TeO5-type, a deformed variant of the NaCl-type of structure [Li4MoO5: 1379 IO(hkl), four-circle-diffraktometer Philips PW 1100, ω--2Θ scan, AgKα, R = 8.7% and RW = 8.3%, space group P1 with a = 511.9(1), b = 772.7(2), c = 506.4(1) pm, α = 101.70(1)°, β = 101.48(1)°, γ = 108.58(2)°, Z = 2 and Li4WO5: 1027 IO(hkl), Philips PW 1100, ω-2Θ scan, MoKα, R = 4.0% und RW = 3.7%, space group P1 with a = 510.94(5), b = 771.59(7), c = 506.09(4) pm, α = 101.804(8)°, β = 101.78(1)°, γ = 108.770(9)°, Z = 2]. The structural relations are deduced from Schlegel Diagrams. The Madelung Part of Lattice Energie, MAPLE, and Effective Coordination Numbers, ECON, these via Mean Fictive Ionic Radii, MEFIR, are calculated and discussed.
    Notes: Erstmals wurde in Form farbloser, transparenter Einkristalle Li4MoO5 [aus Gemengen von Li2O und MoO3. Li:Mo = 4,2:1, Ni-Bömbchen, 950°C, 28 d] sowie Li4WO5 [aus Gemengen von Li2O und WO3, Li:W = 4,4:1, Au-Rohr, 900°C, 30 d] dargestellt. Nach Einkristalldaten liegt bei den isotypen Oxiden vom Li4TeO5-Typ eine Ordnungsvariante des NaCl-Typs [Li4MoO5: 1379 IO(hkl), Vierkreisdiffraktometer Philips PW 1100, ω-2Θ scan, AgKα, R = 8,7% und RW = 8,3%, Raumgruppe P1 mit a = 511,9(1), b = 772,7(2), c = 506,4(1) pm, α = 101,70(1)°, β = 101,48(1)°, γ = 108,58(2)°, Z = 2 bzw. Li4WO5: 1027 IO(hkl), Philips PW 1100, ω-2Θ scan, MoKα, R = 4,0% und RW = 3,7%, Raumgruppe P1 mit a = 510,94(5), b = 771,59(7), c = 506,09(4) pm, α = 101,804(8)°, β = 101,78(1)°, γ = 108,770(9)°, Z = 2] vor.Die strukturellen Zusammenhänge werden aus den Schlegel-Diagrammen abgeleitet. Der Madelunganteil der Gitterenergie, MAPLE, sowie Effektive Koordinationszahlen, ECON, diese über Mittlere Fiktive Ionenradien, MEFIR, berechnet, werden mitgeteilt und diskutiert.
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  • 86
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    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 573 (1989), S. 185-194 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation of CF3SClF+MF6- (M = As, Sb) and Crystal Structure of CF3SCl2+SbF6-CF3SClF+MF6- (M = As, Sb) is prepared by oxidative fluorination of CF3SCl with XeF+MF6-. The new salt is characterized by IR, Raman and NMR spectra in comparison with CF3SF2+MF6- and CF3SCl2+MF6-. In SO2 solution CF3SClF+SbF6- symmetrizises into CF3SF2+SbF6- and crystalline CF3SCl2+SbF6- with the monoclinic space group P21/c with a = 773.5(14) pm, b = 954.8(15) pm, c = 1242.0(18) pm, β = 100.24(8)°, Z = 4.
    Notes: Die Darstellung von CF3SClF+MF6- (M = As, Sb) erfolgt durch oxidative Fluorierung von CF3SCl mit XeF+MF6-. Das Salz wird schwingungs- und NMR-spektroskopisch charakterisiert, orientierend an den bekannten Daten von CF3SF2+MF6- und CF3SCl2+MF6-. In einer SO2-Lösung symmetrisiert sich CF3SClF+SbF6- zu CF3SF2+SbF6- und einkristallinem CF3SCl2+SbF6- mit der monoklinen Raumgruppe P21/c, a = 773,5(14) pm, b = 954,8(15) pm, c = 1242,0(18) pm, β = 100,24(8)°, Z = 4.
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  • 87
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    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 573 (1989), S. 199-207 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Properties of 1,2,3-Thiazaboroles, 3-Sulfoimido- and 3-Pseudohalido-1,2,3-dithiaborolesThe reactions of 3,4,5-trimethyl- and 4,5-diethyl-3-methyl-1,2,3-dithiaborole with di-t.-butylsulfurdiimide leads to the 1,2,3-thiazaboroles 2. 3-Bromo-1,2,3-dithiaboroles react with trimethylsilyl-N-sulfinylamine, -isocyanate, and -cyanide by formation of 3-sulfoimido- (3), 3-isocyanato- (4), and 3-cyano- (5) -1,2,3-dithiaboroles. 3-Isothiocyanato-1,2,3-dithiaboroles (6) are formed by addition of elemental sulfur to 5. 1H-, 11B-, 13C-, 14N-, 15N-NMR-, mass-, and IR spectra are reported and discussed.
    Notes: Die Reaktionen von 3,4,5-Trimethyl- und 4,5-Diethyl-3-methyl-1,2,3-dithiaborol mit Di-t.-butylschwefeldiimid führen zu den 1,2,3-Thiazaborolen 2. 3-Brom-1,2,3-dithiaborole reagieren mit Trimethylsilyl-N-sulfinylamin, -isocyanat und -cyanid unter Bildung von 3-Sulfoimido- (3), 3-Isocyanato- (4) und 3-Cyano- (5) -1,2,3-dithiaborolen. 3-Isothiocyanato-1,2,3-dithiaborole (6) werden gebildet bei Addition elementaren Schwefels an 5. 1H-, 11B-, 13C-, 14N-, 15N-NMR, Massen- und IR-Spektren werden mitgeteilt und diskutiert.
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  • 88
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Elektrochemische Synthese von neutralen Nickel(II)-Komplexen mit Schiffschen Basen: Kristallstruktur von Bis-{N-[2-(2-pyridyl) äthyl]-salicylideneiminato}nickel(II) TrihydratNickel(II)-Komplexe mit im Pyridin-Ring substituiertem N-2-(2-pyridyl)-äthyl-salicylideneiminat wurden durch Elektrolyse einer nicht wäßrigen Lösung des entsprechenden Liganden hergestellt; als Anode diente ein Ni-Draht. Die Struktur von Bis-{N-[2-(2-pyridyl)äthyl]-salicylideneiminato}nickel(II). Trihydrat wurde röntgenographisch bestimmt. Der Komplex kristallisiert triklin in der Raumgruppe P1 mit den Gitterkonstanten a = 13,055(4) Å, b = 13,097(6)Å, c = 16,189(5) Å, α = 102,92(3)°, β = 99,80(3)°, γ = 90,42(3)° und Z = 4. Eine Least-squares-Verfeinerung führte zu einem R-Wert von 0,047. Das Molekül ist nicht zentrosymmetrisch, da die zwei dreizähnigen Liganden eine meridionale Konfiguration um das oktaedrisch koordinierte Nickel(II) annehmen.
    Notes: Nickel(II) complexes with N-2-(2-pyridyl)ethyl-ring substituted salicylideneiminatos have been synthesized by an electrochemical procedure using a sacrificial anode in non-aqueous solution of the corresponding ligand. The structure of bis{N-[2-(2-pyridyl)]-salicylideneiminato}-nickel (II) trihydrate has been determined by X-ray diffraction. Crystals are triclinic, space group P1, with four formula units in a cell of dimensions a = 13.055(4) Å, b = 13.097(6) Å, c = 16.189(5) Å, and α = 102.92(3)°, β = 99.80(3)°, γ = 90.42(3)°. Full matrix least squares refinement on R converged with a conventional agreement factor of 0.047. The molecule is non-centrosymmetric with two terdentate ligands in a meridional configuration around octahedral nickel(II).
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  • 89
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 573 (1989), S. 231-239 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies of the Heterogeneous Catalytical Ring Alkylation of Toluene with Methanol on Modified Zeolites ZSM-5Various ways for controlling the catalytic activity, the shape selectivity, and the deactivation behaviour of modified zeolites ZSM-5 has been shown by the example of the heterogeneous catalytical conversion of toluene with methanol. The preferred formation of the industrially interesting para-xylene is possible by use of ZSM-5-zeolites composed of large crystals, by dealumination of the external surface after hydrothermal treatment, by poisoning of external active centres after impregnation with inorganic salts as well as by isomorphic incorporation of boron for silicon and/or aluminium in the zeolite framework.
    Notes: Am Beispiel der heterogen-katalysierten Umsetzung von Toluen mit Methanol wurden verschiedene Wege zur Steuerung der katalytischen Aktivität, der Formselektivität und des Desaktivierungsverhaltens modifizierter H-ZSM-5-Zeolithe aufgezeigt. Eine Ausprägung der bei der Toluenmethylierung technisch interessanten para-Xylen-Selektivität gelingt durch den Einsatz von großkristallinen ZSM-5-Zeolithen, durch Dealuminieren der äußeren Oberfläche mittels hydrothermaler Behandlung, durch Vergiften äußerer aktiver Zentren mittels Tränkung anorganischer Salze sowie durch den isomorphen Einbau von Bor für Silicium und/oder Aluminium im Zeolithgerüst.
    Additional Material: 5 Ill.
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  • 90
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 91
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 573 (1989), S. 240-240 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 92
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 575 (1989), S. 26-30 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ni5HfB2O10 with Ordered Metal DistributionNi5HfB2O10 was prepared for the first time and investigated by X-ray methods. It crystallizes with orthorhombic symmetry, space group D2h16 - Pnma, a = 9.328; b = 6.120; c = 12.334 Å; Z = 4. In opposition to the Ni5TiB2O10-type all metal point positions are strongly ordered. The authors are in doubt about the partly statistic metal distribution within Ni5M4+B2O10 (M4+ = Ti, Zr, Ge).
    Notes: Ni5HfB2O10 wurde erstmals dargestellt und an Einkristallen untersucht. Ni5HfB2O10 kristallisiert orthorhombisch, Raumgruppe D2h16 - Pnma, a = 9,328; b = 6,120; c = 12,334 Å, Z = 4. Im Gegensatz zum Ni5TiB2O10-Typ weist NiHfB2O10 eine total geordnete Metallverteilung auf. Die partiell statistische Verteilung von Ni2+ mit M4+ (M4+ = Ti, Zr, Ge) wird in Frage gestellt.
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  • 93
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 575 (1989), S. 17-25 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 27Al NMR Studies on Alkali FluoroaluminatesThe 27Al NMR spectra of the alkali fluoroaluminates sensitively reflect the kind of condensation of the AlF6 octahedra. Whereas the chemical shift of the octahedral Al is shown to be rather independent on structural details, clear differences in the electric field gradients of isolated and condensed AlF6 octahedra were found. In contrast to the isolated octahedra which show only weak effects of quadrupole interaction, both for chains and layers of AlF6 octahedra axial EFG tensors result with quadrupolar coupling constants of between 10 and 13 MHz; for the threefold chains in CsAlF4 only a value of 7.5 MHz is obtained.
    Notes: Die 27Al-NMR-Spektren der Alkalifluoroaluminate spiegeln in empfindlicher Weise die Verknüpfung der AlF6-Oktaeder wider. Während sich die chemische Verschiebung für das oktaedrisch koordinierte Aluminium als nahezu unbeeinflußt von strukturellen Details erweist, ergeben sich deutliche Unterschiede in den elektrischen Feldgradienten (EFG) zwischen isolierten und verknüpften AlF6-Oktaedern. Im Gegensatz zu den isolierten Oktaedern, bei denen Quadrupolwechselwirkungseffekte nur eine untergeordnete Rolle spielen, ergeben sich sowohl für Ketten als auch schichtförmige Verknüpfung der AlF6-Oktaeder axiale EFG-Tensoren mit Quadrupolkopplungskonstanten zwischen 10 und 13 MHz, bei Verknüpfung als Dreierstrangkette im CsAlF4 lediglich ein Wert von 7,5 MHz.
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  • 94
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 572 (1989), S. 95-101 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Contribution about the Crystal Chemistry of Alkaline Earth Oxochromates(V): Sr3(CrO4)2 and Sr18Ca3Cr14O56The crystal structure of (I) Sr3Cr3(CrO4)2 was examined by X-ray single crystal technique. It belongs to the Ba3(PO4)2-type, space group 3d5-R3m, a = 5.562; c = 20.221 Å; Z = 3. The replacement of Sr2+ leads to a compound of the formula (II) Sr18Ca3Cr14O56, space group 3v6-R3c, a = 11.004; c = 39.256 Å; Z = 3. The Sr2+ and Ca2+ ions occupy the alkaline earth positions in an ordered manner. So the formulation Sr2.57Ca0.43(CrO4)2 should be avoided although it belongs to the β-Ca3(PO4)2 = Ca3(CrO4)2-type. The crystal chemistry of (I) and (II) is discussed.
    Notes: Die Kristallstruktur von (I) Sr3(CrO4)2 wurde an Einkristallen exakt untersucht. Sie gehört zum Ba3(PO4)2-Typ, Raumgruppe D3d5-R3m, a = 5,562; c = 20,221 Å; Z = 3. Der Ersatz von Sr2+ gegen Ca2+ führt zur Verbindung (II) Sr18Ca3Cr14O56, Raumgruppe C3v6-R3c, a = 11,004; c = 39,256 Å; Z = 3. Es wird gezeigt, daß Sr2+ und Ca2+ die Erdalkalimetall-Positionen im β-Ca3(PO4)2-Typ geordnet besetzen, womit die Schreibweise Sr2,57Ca0,43(CrO4)2 nicht verwendet werden sollte, obwohl dieser Stoff zum β-Ca3(PO4)2 = Ca3(CrO4)-Typ gehört. Die Kristallchemie von (I) und (II) wird diskutiert.
    Additional Material: 3 Ill.
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  • 95
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 572 (1989), S. 63-74 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Molecular and Crystal Structure of 1,4-Bis[tris(tetrahydrofuran)lithium]-octaphenyltetrasilane1,4-Dilithium-octaphenyltetrasilane prepared from octaphenyl-cyclo-tetrasilane and lithium in tetrahydrofuran (THF) [4], can be isolated from tetrahydrofuran/n-pentane as an adduct with six molecules of tetrahydrofuran per formula unit. The orange-red compound crystallizes in the triclinic space group P1 {a = 1159.6(3); b = 1268.4(2); c = 1367.8(3) pm; α = 92,23(2)° β = 113.79(2)° γ = 111.62(2)° at -5 ± 3°C; Z = 1}. An x-ray structure determination (Rw = 0.046) shows the existence of a centrosymmetric molecule with an extended planar Li—Si4—Li unit; either lithium atom is bound to silicon and to the oxygen atoms of three molecules of tetrahydrofuran. Characteristic bond lengths and angles are: Li—Si 271; Si—Si 241 and 243; Si—C 190 to 192 pm; Li—Si—Si 126°; Si—Si—Si 127°. 29Si and 7Li n.m.r. measurements at low temperatures indicate the presence of three different adducts.
    Notes: Das aus Octaphenyl-cyclo-tetrasilan und Lithium in Tetrahydrofuran (THF) dargestellte, orangerote 1,4-Dilithium-octaphenyltetrasilan [4] kristallisiert aus Tetrahydrofuran/n-Pentan als Addukt mit sechs Molekülen Tetrahydrofuran triklin in der Raumgruppe P1. Die Verbindung weist folgende, bei -5 ± 3°C bestimmte Parameter der Elementarzelle auf: a = 1159,6(3); b = 1268,4(2); c = 1367,8(3) pm; α = 92,23(2)°; β = 113,79(2)° γ = 111,62(2)°; Z = 1. Nach den Ergebnissen einer Röntgenstrukturanalyse (Rw = 0,046) liegt ein zentrosymmetrisches Molekül mit gestrecktem, planarem Li—Si4—Li-Gerüst vor; jedes Lithium ist an Silicium und die Sauerstoffatome aus drei Tetrahydrofuran-Molekülen gebunden. Charakteristische Bindungslängen und -winkel sind: Li—Si 271; Si—Si 241 und 243; Si—C 190 bis 192 pm; Li—Si—Si 126°; Si—Si—Si 127°. 29Si- und 7Li-Kernresonanz-Messungen bei tiefen Temperaturen ergeben in Lösung drei unterschiedliche Addukte.
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  • 96
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 572 (1989), S. 75-88 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metal Derivatives of Molecular Compounds. II. Preparation and Structure of β-Potassium SilanideAt -5°C potassium silanide crystallizes from 1,2-dimethoxyethane/n-pentane in a to date unknown low temperature modification {β-form: orthorhombic, Pnma, Z = 4; a = 880.0(2), b = 541.6(1), c = 682.3(1) pm at -110 ± 3°C}. An x-ray structure determination shows the compound to be built up from isolated potassium cations and pyramidal silanide anions without perceptible disorder. Seven counterions make up the coordination sphere of either particle (K⃛Si 356 to 386 pm), two anion-anion contacts (Si⃛Si 355 pm) are observed in addition. The packing of ions represents a defect variant of the barite type, but there are also relationships to the high temperature modification (α-form, rock salt type) and to cesium trihydrogengermanide (thallium iodide type).
    Notes: Kaliumsilanid kristallisiert bei -5°C aus 1,2-Dimethoxyethan/n-Pentan in einer bisher unbekannten Tieftemperatur-Modifikation {β-Form: orthorhombisch, Pnma, Z = 4; a = 880,0(2), b = 541,6(1), c = 682,3(1) pm bei -110 ± 3°C}. Nach den Ergebnissen der Röntgenstrukturanalyse (R = 0,032) baut sich die Verbindung ohne erkennbare Fehlordnung aus isolierten Kalium-Kationen und pyramidalen Silanid-Anionen auf. Zur Koordinationssphäre beider Teilchen gehören sieben Gegenionen (K⃛Si 356 bis 386 pm); beim Anion kommen zwei zusätzliche Kontakte zu gleichnamigen Nachbarn (Si⃛Si 355 pm) hinzu. Die Kristallstruktur stellt eine Defektvariante des Baryt-Typs dar, Verwandtschaft besteht aber auch zur Hochtemperatur-Modifikation (α-Form, Steinsalz-Typ) und zum Caesium-trihydrogengermanidWährend der Name Kaliumsilanid unseres Erachtens eindeutig ist, sollte die homologe Germanium-Verbindung zur Unterscheidung von den binären Phasen Caesium-trihydrogengermanid genannt werden. (Thalliumiodid-Typ).
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  • 97
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Organo Transition Metal Compounds. 54. Formation of Cyclic Chalcogenides of the Type [Cp2*Zr(μ-E)]2 at Thermolysis of Permethylzirconocene Divinyl in Presence of Sulfur, Selenum, and Tellurium4-membered cyclic chalcogenides of the type [Cp2*Zr(μ-E)]2are formed at thermolysis of Cp2*Zr(CH=CH2)2 in presence of sulfur, selenum and tellurium using an aliphatic hydrocarbon as a solvent. During the reactions acetylene and ethylene are liberated in equimolar amounts, which indicates the formation of a zirconocene acetylene ethylene complex as an intermediate.
    Notes: Die Thermolyse von Cp2*Zr(CH=CH2)2 in aliphatischen Kohlenwasserstoffen als Lösungsmittel führt in Gegenwart von Schwefel, Selen und Tellur zur Bildung viergliedriger cyclischer Chalkogenide des Typs [Cp2*Zr(μ-E)]2. Die Reaktionen verlaufen unter Freisetzung äquimolarer Mengen an Acetylen und Ethylen, was auf die intermediäre Bildung eines Zirconocenethylen-acetylen-Komplexes schließen läßt.
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  • 98
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 573 (1989), S. 208-214 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation of Ceramic Powders. II. Mg2TiO4, MgTiO3, and MgTi2O5 Formed by Hydrolysis of 2-EthoxyethylatesSolutions of 2-ethoxyethylates of magnesium and titanium in 2-ethoxyethanol submitted to hydrolysis, evaporation and heating of the residue up to 450°C allow to prepare Mg2TiO4, MgTiO3, and MgTi2O5 in an amorphous state with smaller than 1% of volatile components. Highly dispersed powders showing an increased sintering activity are obtained as a result of recrystallization. Mg2TiO4 is formed as inverse spinel phase in a metastable state.
    Notes: Die 2-Ethoxyethylate von Magnesium und Titan bilden in 2-Ethoxyethanol stabile Lösungen, deren Hydrolyse nach dem Abdestillieren des Lösungsmittels und Erhitzen des Rückstandes bis auf 450°C die Herstellung von Mg2TiO4, MgTiO3 und MgTi2O5 im amorphen Zustand mit weniger als 1% flüchtigen Bestandteilen gestattet. Die Rekristallisation führt zu hochdispersen sinteraktiven Pulvern, im Fall von Mg2TiO4 zur Bildung der inversen Spinellphase unter metastabilen Bedingungen.
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  • 99
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 573 (1989), S. 223-230 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pollucit- und Leucit-verwandte Phasen: A2BX5O12 und ACX2O6 (A = K, Rb, Cs; B = Be, Mg, Fe, Co, Ni, Cu, Zn, Cd; C = B, Al, Ga, Fe, Cr; X = Si, Ge)Darstellung und kristallographische Daten von 29 neuen Phasen dieser Strukturfamilie werden angegeben. Ein Überblick über die gesamte Strukturfamilie, die bis jetzt 59 Phasen enthält, wird gegeben. Die Familie enthält wenigstens sieben Strukturvarianten, von denen zwei die Pollucit-, CsAlSi2O6, und Leucit-, KAlSi2O6, Struktur sind. Beziehungen zwischen der Kationengröße und dem Strukturtyp werden vorgestellt. Ungewöhnliche Variationen in den Größen der Einheitszelle als Funktion der Kationengröße werden diskutiert, und auf die mögliche Bedeutung für das „partially collapsed framework“-Konzept von Taylor und Henderson wird hingewiesen.
    Notes: Synthesis and crystallographic data on 29 new phases in this family are given. A survey of the crystal chemistry of the complete family, containing 59 phases to date, is presented. The family contains at least seven structural variations, two of which are the pollucite, CsAlSi2O6 and leucite, KAlSi2O6 structures. Correlations between cation size and structure type are presented. Unusual variations in unit cell dimensions as a function of cation size are discussed and the possible relevance of the „partially collapsed framework“ concept of Taylor and Henderson indicated.
    Additional Material: 4 Ill.
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  • 100
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Drei Bromide des Lanthans: LaBr2, La2Br5 und LaBr3Farbloses LaBr3 wurde durch Umsetzung von La2O3 mit NH4Br bzw. in einkristalliner Form durch chemischen Transport mit AlBr3 erhalten. Schwarze Einkristalle von LaBr2 und La2Br5 wachsen aus der Schmelze, die man bei der metallothermischen Reduktion von LaBr3 mit Lithium erhält (verschweißte Tantalampulle, 850°C). Die Kristallstrukturen der drei Lanthanbromide wurden verfeinert: LaBr2. 2H2-Typ, hexagonal (P63/mmc); a = 409,88(4) pm; c = 1 390,0(1) pm; R = Rw = 0,092; La2Br5. Pr2I5-Typ, monoklin (P21/m); a = 789,09(6) pm; b = 424,89(4) pm; c = 1342,3(1) pm β = 91,60(1)º; R = 0,067; Rw = 0,055; LaBr3. UCl3-Typ, hexagonal (P63/m) a = 797,13(4) pm; c = 452,16(4) pm; R = 0,036; Rw = 0,032.
    Notes: Colourless LaBr3 was obtained via the ammonium-bromide route and in singlecrystalline form by chemical vapour-phase transport with aluminium tribromide. Black single crystals of LaBr2 and La2Br5 have been grown from the melts that are obtained by lithium reduction of lanthanum tribromide in sealed tantalum ampoules at 850°C. The crystal structures of the three bromides of lanthanum were refined: LaBr2. 2H2-MoS2 type, hexagonal (P63/mmc), a = 409.88(4) pm, c = 1390.0(1) pm, R = Rw = 0.092; La2Br5. Pr2I5 type, monoclinic (P21/m), a = 789.09(6) pm, b = 424.89(4) pm, c = 1342.3(1) pm, β = 91.60(1)º, R = 0.067, Rw = 0.055; LaBr3. UCl3 type, hexagonal (P63/m), a = 797.13(4) pm, c = 452.16(4) pm, R = 0.036, Rw = 0.032.
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