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  • Chemistry  (21)
  • Humans
  • 2000-2004  (2)
  • 1995-1999  (5)
  • 1980-1984  (12)
  • 1975-1979  (1)
  • 1960-1964  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Darstellung und Eigenschaften neuer perhalogenierter 1,3-Dithietan-S-oxide (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 1623-1630 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Properties of New Perhalogenated 1,3-Dithietane S-OxidesNew perchlorinated and perfluorinated 1,3-dithietanes (4, 6, 7, 12, 14, 15), which are partially oxidized at the sulfur atoms, are described. Pyrolysis of the 1,3-dioxides 7 and 15 leads to the sulfoxides 8 and 16, X2C = S = O (X = Cl, F). respectively. Two new oxidizing agents are used: trifluoromethane- and nonafluorobutanepersulfonic acid.
    Notes: Die neuen perchlorierten und perfluorierten, am Schwefel partiell oxidierten 1,3-Dithietane 4, 6, 7, 12, 14 und 15 werden beschrieben. Pyrolysen der 1,3-Dioxide 7 und 15 führen zu den Sulfoxiden 8 bzw. 16, X2C = S = O (X = Cl, F). Zwei neue Oxidationsmittel werden angewendet: Trifluormethan- und Nonafluorbutanpersulfonsäure.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160437
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  • 2
    Electronic Resource
    Electronic Resource
    Comparison of hydrolysis and esterification behavior of Humicola lanuginosa and Rhizomucor miehei lipases in AOT-stabilized water-in-oil microemulsions: II. Effect of temperature on reaction kinetics and general considerations of stability and productivity (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 190-196 
    Details
    ISSN: 0006-3592
    Keywords: hydrolysis ; esterification ; Humicola lanuginosa ; Rhizomucor miehei ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Humicola lanuginosa lipase (HIL) and Rhizomucor miehei lipase (RrnL), isolated from commercial preparations of Lipolase and Lipozyme, respectively, were solubilized in AOT-stabilized water-in-oil (w/o) microemulsions in n-heptane and aspects of their hydrolysis and condensation activity examined. The temperature dependence of HIL hydrolysis activity in unbuffered R = 10 microemulsions matched very closely that for tributyrin hydrolysis by Lipolase in an aqueous emulsion assay. Apparent activation energies were measured as 13 ± 2 and 15 ± 2 kJ mol / respectively. Condensation activity, however, was essentially independent of temperature over the range 5° to 37°C. The stability of HIL over a 30-day period was very good at all pH levels (6.1, 7.2, 9.3) and R values studied (5, 7.5, 10, 20), except when high pHs and low R values were combined. The excellent stability was reflected by the linearity of the productivity profiles which facilitate system optimization. The temperature dependence of RmL hydrolysis activity toward pNPC4 showed a maximum at 40°C and an apparent Eact = 20 ± 2 kJ mol-1 was calculated based on the linear region of the profile (5° to 40°C). RmL esterification activity showed only a slight dependence on temperature over the studied range (0° to 40°C) and an apparent Eact = 5 ± 1 kJ mol-1 was measured for octyl decanoate synthesis. Both RmL and HIL, therefore, have potential for application in low temperature biotransformations in microemulsion-based media. The stability of RmL over a 30-day period was good in R = 7.5 and R = 10 microemulsions containing pH 6.1 buffer, and this was reflected in the linearity of their respective productivity profiles. RmL stability was markedly poorer at more alkaline pH, however, and proved to be sensitive to relatively small changes in the R value. © 1995 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260480304
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  • 3
    Electronic Resource
    Electronic Resource
    Proline excretion by Escherichia coli K12A preliminary report of this research was made at the Fourth International Symposium on the Genetics of Industrial Microoganisms in Kyoto, Japan, June, 1982. (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 74-80 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Proline excretion from proline overproducing strains of E. coli K12 has been studied as a model chemical production system. We have isolated proline overproducing mutants of E. coli and have shown that uncontrolled synthesis is not sufficient to cause excretion of this amino acid. An episomal mutation causing proline over production has been introduced into a series of otherwise isogenic strains that bear well defined, chromosomal lesions affecting the active uptake and catabolism of L-proline. A syntropism test reveals that L-proline is excreted by overproducing strains only if transport and/or catabolism are impaired. Dansyl derivatization and chromatographic analysis of culture supernatants shows that proline is the only amino acid excreted. Batch cultures of an excreting strain in an amino acid production medium yield culture supernatants containing 1 g proline/L, whereas no proline is detectable in supernatants derived from cultures of an overproducing strain with normal transport and catabolic activities. These data reveal that genetic lesions eliminating active uptake can be used to specifically enhance metabolite excretion.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260260114
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  • 4
    Electronic Resource
    Electronic Resource
    Proline excretion by Escherichia coli K12 (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1140-1140 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260260924
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  • 5
    Electronic Resource
    Electronic Resource
    Comparison of hydrolysis and esterification behavior of Humicola lanuginosa and Rhizomucor miehei lipases in AOT-stabilized water-in-oil microemulsions: I. Effect of pH and water content on reaction kinetics (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 78-88 
    Details
    ISSN: 0006-3592
    Keywords: hydrolysis ; esterification ; Humicola lanuginosa ; Rhizomucor miehei ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Lipolase and Lipozyme are produced in large quantities (as a result of genetic engineering and overexpression) for the detergents market and provide a cheap source of highly active biocatalysts. Humicola lanuginosa lipase (HIL) and Rhizomucor miehei lipase (RmL) have been isolated in partially purified form from commercial preparations of Lipolase and Lipozyme, respectively. These lipases were solubilized in Aerosol-OT (AOT)-stabilized water-in-oil (w/o) microemulsions in n-heptane. HIL and RmL activity in these microemulsions was assayed by spectrophotometric measurement of the initial rate of p-nitophenyl butyrate hydrolysis, and by chromatographic determination of the initial rate of octyl decanoate synthesis from 1-octanol and decanoic acid. The hydrolytic activity of HIL in microemulsions measured as a function of buffer pH prior to dispersal, followed a sigmoidal profile with the highest activities observed at alkaline pHs. This broadly matches the pH-activity profile for tributyrin hydrolysis by Lipolase in an aqueous emulsion assay. The hydrolytic activity of RmL in the same microemulsions, measured as a function of pH, gave a bell-shaped profile with a maximum activity at pH 7.5. Again, the observed pH-activity profile was similar to that reported for a purified RmL in a tributyrin-based aqueous emulsion assay. In contrast, the esterification activity exhibited by both HIL and RmL in AOT microemulsions over the available range pH 6.1 to 10.4, decreases as the pH increases, most likely reflecting the effect of substrate ionization. The dependence of the hydrolytic and condensation activity of HIL on R, the mole ratio of water to surfactant, were similar with both profiles exhibiting a maximum at R = 5. The hydrolytic and esterification activities of RmL followed similar R-dependent profiles, but the profiles in this case exhibited a maximum at R = 10. The water activities at these R values were directly measured as 0.78 and 0.9, respectively. Measured water activities were unperturbed by the presence of lipase at the concentrations used in these studies. © 1995 John Wiley & Sons, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260480111
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  • 6
    Electronic Resource
    Electronic Resource
    The application of membrane biological reactors for the treatment of wastewaters (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 601-610 
    Details
    ISSN: 0006-3592
    Keywords: aerobic ; anaerobic ; biomass separation ; bioreactor ; bubbleless ; oxygen mass transfer ; extraction of organic pollutants ; membrane ; wastewaters ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Combining membrane technology with biological reactors for the treatment of municipal and industrial wastewaters has led to the development of three generic membrane processes within bioreactors: for separation and recycle of solids; for bubbleless aeration of the bioreactor; and for extraction of priority organic pollutants from hostile industrial wastewaters. Commercial aerobic and anaerobic membrane separation bioreactors already provide a small footprint alternative to conventional biological treatment methods, producing a high-quality effluent at high organic loading rates. Both the bubbleless aeration and extractive membrane bioreactors are in the development stages. The former uses gas-permeable membranes to improve the mass transfer of oxygen to the bioreactor by providing bubbleless oxygen. By using a silicone membrane process, extractive membrane bioreactors transfer organic pollutants from chemically hostile wastewaters to a nutrient medium for subsequent biodegradation. All three membrane bioreactor (MBR) processes are comparatively and critically reviewed. © 1996 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    The load-bearing capability of short-fiber thermoplastics composites - A new practical system of evaluation (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 173-180 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The load-bearing capabilities of short-fiber reinforced thermoplastics composites can be evaluated, in principle, by the methods known to be satisfactory for unreinforced thermoplastics, but in practice the cost of a comprehensive evaluation of a composite would be prohibitive because of the anisotropy of the properties and its variation from point to point. For the same reasons the properties measured on a specimen cut from a molding may have little relevance to its overall performance. This paper describes recent experiments that could lead to a radical change in testing strategy. Instead of the classical method in which standard specimens cut from moldings are assumed to provide the various stiffness coefficients needed for anisotropic stress analysis, simple moldings such as discs or plaques are tested directly. The sacrifice of precision in the measurements and the loss of rigor in the definition of the measured quantities is more than compensated for by a gain in the general utility of the data and the substantial reduction in the cost of evaluations. The mechanical properties of shortfiber thermoplastics composites are particularly sensitive to mold geometry and the new methods of testing enable the effects to be assessed readily, whereas the information generated by the classical method is virtually indecipherable in that context. Examples are given in the paper.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190303
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis of [1.1.1]Propellanes by Bridging of Bicyclo[1.1.0]butanes (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1705-1715 
    Details
    ISSN: 0947-3440
    Keywords: [1.1.1]Propellanes ; 13C-13C coupling constants ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several [1.1.1]propellanes were synthesized by bridging the 1,3-positions of the corresponding bicyclo[1.1.0]butane. The synthesis of 1-bromo-3-(chloromethyl)bicyclobutanes and the bridging were carried out in a one-pot reaction by addition of 2.0 equiv. of MeLi to 1,1-dibromo-2,2-bis(chlormethyl)-cyclopropanes 10. Three routes to 10 were investigated: Firstly, the Wittig reaction of 1,3-dichloroacetone leading to (chloromethyl)allyl chlorides 6 was, with the exception of 6m, successful only with Wittig reagents derived from primary alkyl halides, Secondly, reduction of diethyl alkylidenemalonates with LiAlH4 in benzene afforded carbinols 12 which were converted into 6 by reaction with N-chlorosuccinimide/dimethyl sulfide. The cyclopropanation of 6 to 10 was achieved by reaction with bromoform/NaOH under phase-transfer catalysis conditions. Finally, starting from diethyl alkylidenemalonates, the sequence of reduction and cyclopropanation could be interchanged, according to the sequence 11 → 13 → 14 → 10. Propellanes 5b and 3 were reduced with LiAlH4 to bicyclo[1.1.1]pentanes 15b and e. 2-D INADEQUATE NMR spectra of 5d and 5p indicate that the coupling constants J(13C-13C) between the bridgehead positions are very small, i.e. 0.47 and 0.53 Hz, respectively.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961103
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  • 9
    Electronic Resource
    Electronic Resource
    1-Vinyltricyclo[4.1.0.02,7]heptanes: Synthesis and Reactions with Electrophilic Dienophiles (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 29-41 
    Details
    ISSN: 1434-193X
    Keywords: Strained molecules ; 1-Vinyltricyclo[4.1.0.02,7]heptanes ; Electrophilic additions ; Rearrangements ; Cyclic ketene imine ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of 1-vinyltricyclo[4.1.0.02,7]heptanes 4 has been obtained by Ni0-catalyzed cross-coupling reactions of the corresponding Grignard reagent with vinyl halides or via reaction of 4b with various electrophiles. Selected model compounds 4 were treated with tetracyanoethylene (TCNE), N-phenyl-1,2,4-triazoline-3,5-dione (PTAD), and dimethyl acetylenedicarboxylate (DMAD). Product studies revealed that TCNE and PTAD attacked the CC double bond forming a zwitterion, which in most cases underwent several carbenium ion rearrangements until internal bond formation of the ionic centers took place. The main reaction path of DMAD and 4 led via attack at the bicyclo[1.1.0]butane bridgehead to a biradical of type 38, which after H abstraction and CC bond formation gave rise to the tricyclic system 37.
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  • 10
    Electronic Resource
    Electronic Resource
    4-Alkyl(Aryl)-λ5-phosphorine; 1,4-Dihydrophosphorin/λ5-Phosphorin-UmlagerungHerrn Prof. Dr. K. Dimroth zum 70. Geburtstag gewidmet. (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 870-918 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 4-Alkyl(Aryl)-λ5-phosphorins; 1,4-Dihydrophosphorin/λ5-Phosphorin4 RearrangementThe 1-R'-4-R-4-methoxy-1,4-dihydrophosphorins11-17, the 1H- and 13C-NMR spectra and stereochemistry of which are discussed, are formed by reaction of (1 Z, 4Z)-1,5-dilithio-3-R-3-methoxy-1,4-pentadienes9 with R'PCl2 [R' = aryl, alkyl, N(C2H5)2, OC4H9, SC6H5] at - 78°C. Addition of catalytic amounts of acid causes rearrangement of the 1,4-dihydrophosphorins and yields the 1-R'-1-methoxy-4-R-λ5-phosphorins23 - 29 which represent the most simple derivatives of this class of compounds. - The mechanism of this 1,4-dihydrophosphorin/λ5-phosphorin rearrangement has been studied; according to that a direct H+-catalyzed 1,4-migration of the methoxy group is assumed concerning the trans-isomers, while the 1-R'-phosphorinium cations are intermediates in the case of the cis-isomers. - Acid-catalyzed hydrolysis of the λ5-phosphorins yields the 1-R'-4-R-1,2-dihydrophosphorin oxides35. The 1,1-dimethoxy-4-R-λ5-phosphorins28 have been prepared by direct oxidative alkoxylation of the λ3-phosphorins with Hg(OAc)2/methanol.
    Notes: Durch Umsetzung der (1 Z,4Z)-1,5-Dilithio-3-R-3-methoxy-1,4-pentadiene9 mit R'PCl2 [R' = Aryl, Alkyl, N(C2H5)2, OC4H9, SC6H5] bei - 78°C werden die 1-R'-4-R-4-methoxy-1,4-dihydrophosphorine11 - 17 erhalten, deren 1H- und 13C-NMR-Spektren und cis/trans-Stereochemie diskutiert werden. - Die 1,4-Dihydrophosphorine lagern sich bei der Einwirkung von katalytischen Mengen Säure in die entsprechenden 1-R'-1-methoxy-4-R-λ5-phosphorine23-29 als bisher einfachste Vertreter dieser Verbindungsklasse um. Ihre 1H-NMR-, 13C-NMR-, UV-, IR- und Massenspektren werden diskutiert. - Der Mechanismus dieser 1,4-Dihydrophosphorin/λ5-Phosphorin-Umlagerung wird untersucht; danach muβ angenommen werden, daβ sich die trans-Isomeren in einer direkten H + -katalysierten 1,4-Verschiebung der Methoxygruppe umlagern, während bei den cis-Isomeren die 1-R'-phosphoriniumkationen Zwischenstufe sind. - Bei der säure-katalysierten Hydrolyse der λ5-Phosphorine entstehen die 1-R'-4-R-1,2-dihydrophosphorinoxide35. Die 1,1-Dimethoxy-4-R-λ5-phosphorine28 lassen sich direkt durch oxidative Alkoxylierung der λ3-Phosphorine mit Hg(OAc)2/Methanol darstellen.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119810512
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