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  • Chemistry  (16)
  • Humans
  • 2000-2004  (2)
  • 1995-1999  (5)
  • 1980-1984  (12)
  • 1950-1954
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 601-610 
    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.
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  • 2
    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.
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  • 3
    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.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 1623-1630 
    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.
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  • 5
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Journal of Vinyl and Additive Technology 5 (1983), S. 13-18 
    ISSN: 0193-7197
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Poly(Vinyl chloride) is the basic material for a huge number of products which are fabricated using very many different techniques. Established processing techniques continue to be improved, leading to additional benefits in process efficiency and product quality. New processes are also being introduced which are intended to increase the efficiency of material usage and to open up new application areas. These include: molecular orientation, foaming, and cross-linking. Developments are also occurring in the use of PVC in conjunction with other materials as micro- or macro-composites. Processing techniques include coextrusion and lamination. Many processing methods are likely to benefit from the microelectronics revolution in process control and monitoring.
    Additional Material: 4 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 7 (1983), S. 123-127 
    ISSN: 0308-0501
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The apparatus described in DIN 4842 was used to measure the heat transmission of a series of Nomex, polyester-cotton, Proban®-Treated cotton, untreated cotton and wool workwear fabrics subjected to a radiant heat source. Heat transmission was found to be dependent on the incident heat flux, fabric weight and fabric thickness. At the heat flux levels tested, 10 KJ m-2s-1 and 20 KJ m-2s-1, heat transmission was found to be largely independent of the fibre composition of the fabric when single layers of fabric were tested. The level of heat transmission was reduced by the use of multiplayer assemblies or a reflective aluminium coating, but the greatest reduction was obtained when air spaces were interposed between the fabrics. Conbinaitons of fabrics were developed which transmitted less than 205 KJ m-2s-1 during testing at incident heat flux levels of 10 KJ m-2s-1 and 20 KJ m-2s-1.
    Additional Material: 4 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 14 (1980), S. 226-233 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In recent publications we have described a novel method of analysis for high-resolution NMR spectra of compounds in isotropic solution which differs from conventional procedures in that it exploits the full information content of a spectrum and does not require assignments of energy levels or transitions. We now present a further development of this technique which also makes it applicable to the NMR spectra of molecules partially oriented in liquid crystal solvents. Illustrative applications are reported for the nematic phase spectra of allyl fluoride, allyl chloride and allyl bromide. The results are discussed in terms of various theoretical models of the interplay between the internal and overall rotations of the conformationally mobile solutes.
    Additional Material: 3 Ill.
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  • 8
    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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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1705-1715 
    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.
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  • 10
    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.
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