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  • 1
    Electronic Resource
    Electronic Resource
    Glutathione transferase gene family from the housefly Musca domestica (1994)
    Springer
    Molecular genetics and genomics 245 (1994), S. 25-31 
    Details
    ISSN: 1617-4623
    Keywords: Glutathione transferase ; Musca domestica ; Insecticide resistance ; Multigene family ; Evolutionary rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three new glutathione transferase (GST) genes from the housefly Musca domestica are described. These genes, identified as MdGST-2, -3, and -4, were from cDNA clones obtained from a cDNA bank in phage λ. The bank was prepared using poly(A)+ RNA from a housefly that is highly resistant to organophosphate insecticides because of enhanced expression of multiple members of the glutathione transferase gene family. The DNA sequence of each is reported and has a complete open reading frame that specified an amino acid sequence similar to other dipteran glutathione transferases. Based on phylogenetic analysis, we can conclude that the insect glutathione transferase gene family falls into two groups, each of which evolves at a different rate, presumably due to differences in functional constraints. We show that MdGST-1 (and their homologues from Drosophila and Lucilia) evolve at a significantly slower rate than the other members of the gene family. Each housefly GST cDNA was inserted into a bacterial plasmid expression system and a glutathione transferase activity was expressed in Escherichia coli. The transcription pattern of each of these glutathione transferases was examined in a variety of different housefly strains that are known to differ in their resistance to organophosphate insecticides due to different patterns of glutathione transferase expression. We found that the level of transcription for two of our clones was positively correlated with the level of organophosphate resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00279747
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular cloning of a glutathione S-transferase overproduced in an insecticide-resistant strain of the housefly (Musca domestica) (1991)
    Springer
    Molecular genetics and genomics 227 (1991), S. 260-266 
    Details
    ISSN: 1617-4623
    Keywords: Glutathione S-transferase ; Musca domestica ; cDNA sequence ; Organophosphate triesters ; Insecticide resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We report the cloning and sequencing of a glutathione S-transferase (GST) gene from the housefly Musca domestica. A cDNA λgt11 library was prepared from the organophosphate insecticide-resistant housefly strain Cornell-R — a variant that has elevated GST activity. The λ phage GST clone was identified on the basis of its ability to cross-hybridize to a GST DNA probe from Drosophila melanogaster. Based on amino acid homology to other GSTs and expression of GST activity in Escherichia coli, the Musca GST gene (MdGST-1) belongs to the GST gene family. Although organophosphate resistance in Cornell-R is largely due to one of the GSTs, MdGST-1 is probably not the enzyme responsible for resistance. The mutation that controls resistance to organophosphate insecticides in Cornell-R is highly unstable and we isolated spontaneous variants to both insecticide sensitivity and to even higher levels of resistance. This provided us with an isogenic set of three strains. We found that MdGST-1 transcript levels as measured by Northern assays are higher in all three Cornell-R strains relative to the sensitive wild type, but that the sensitive Cornell-R strain has more MdGST-1 transcript than does the highly resistant Cornell-R strain. These data as well as Southern analysis of genomic DNA allow us to conclude: (1) there are multiple GST genes in M. domestica; (2) the natural variant Cornell-R excess transcript from two and probably more of these genes; and (3) the unstable mutation in Cornell-R influences the levels of multiple GSTs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00259679
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  • 3
    Electronic Resource
    Electronic Resource
    Computer simulation of driven diffusive systems with exchanges (1989)
    Springer
    Journal of statistical physics 56 (1989), S. 783-819 
    Details
    ISSN: 1572-9613
    Keywords: Driven Kawasaki models ; stochastic lattice gas ; non-equilibrium phase transitions ; computer simulations ; finite-size scaling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The field-driven Kawasaki model with a fractionp admixture of Glauber dynamics is studied by computer simulation:p=0 corresponds to the order-parameter-onserving driven diffusive system, whilep=1 is the equilibrium Ising model. Forp=0.1 our best estimates of critical exponents based on a system of size 4096×128 areβ≈0.22, ηRS≈0.45, andv ‖≈v ⊥≈1. These exponents differ from both the values predicted by a field-theoretic method forp=0 and those of the equilibrium Ising model. Anisotropic finite-size scaling analyses are carried out, both for subsystems of the large system and for fully periodic systems. The results of the latter, however, are inconsistent, probably due to the complexity of the size effects. This leaves open the possibility that we are in a crossover regime fromp=0 top≠0 and that our critical exponents are “effective ones.” Forp=0 our results are consistent with the predictionsv ‖〉v ⊥.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01016780
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  • 4
    Electronic Resource
    Electronic Resource
    Anisotropic finite-size scaling analysis of a two-dimensional driven diffusive system (1996)
    Springer
    Journal of statistical physics 82 (1996), S. 1409-1427 
    Details
    ISSN: 1572-9613
    Keywords: Driven diffusive systems ; anisotropic finite-size scaling ; non-equilibrium phase transitions ; computer simulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The standard two-dimensional uniformly driven diffusive model is simulated extensively for much larger systems with a multi-spin coding technique. The nonequilibrium phase transition is analyzed with anisotropic finite-size scaling both at the critical point and off the critical point. The field-theoretic values of critical exponents fit the data well at and aboveT c . BelowT c the scaling is rather difficult and the results are not conclusive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02183389
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  • 5
    Electronic Resource
    Electronic Resource
    The Enantioselective Synthesis of β-Amino Acids, their α-hydroxy derivatives, and the N-terminal components of bestatin and microginin (1996)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 79 (1996), S. 1203-1216 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: L-Aspartic acid by tosylation, anhydride formation, and reduction with NaBH4 was converted into (3S)-3-(tosylamino)butan-4-olide (8; Scheme 1). Tretment of 8 with ethanolic trimethylsilyl iodide gave the N-protected deoxy-iodo-β-homoserine ethyl ester 9. The latter, on successive nucleophilic displacement with lithium dialkyl-cuprates ( → 10a-e), alkaline hydrolysis ( → 11a-e), and reductive removal of the tosyl group, produced the corresponding 4-substituted (3R)-3-aminobutanoic acids 12a-e (ee 〉 99%). Electrophilic hydroxylation of 8 ( → 19; Scheme 3), subsequent iodo-esterification ( → 21; Scheme 4), and nucleophilic alkylation and phenylation afforded, after saponification and deprotection, a series of 4-substituted (2S, 3R)-3-amino-2-hydroxybutanoic acids 24 including the N-terminal acids 24e ( =3) and 24f ( =4) of bestatin and microginin (de 〉 95%), respectively.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19960790426
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  • 6
    Electronic Resource
    Electronic Resource
    Factors affecting the role of SiO2 in MgCl2-supported Ziegler-Natta copolymerization catalysts (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 211-221 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This paper describes the roles of silica (SiO2), the butoxy ligand (—OBu) and ethyl benzoate (EB) on ethylene/1-butene copolymerization with MgCl2/SiO2-supported titanium catalysts. The distribution of SiO2 and of the elements Mg and Ti was observed by means of an energy-dispersed X-ray micronalyzer on a scanning electron microscope (SEM). An inversed Si/Mg ratio results, at invariant Ti/Mg ratio and—OBu content, in higher catalyst efficiency and higher comonomer incorporation, with a correspondingly decreased crystallinity of the copolymers. Thus, the inert carrier SiO2 favors copolymerizability, as seen from the values of the reactivity ratios. The copolymer compositional distribution is also affected by the SiO2 content, as seen from the DSC curves of the copolymers. As to the copolymer morphology, addition of SiO2 makes the copolymer particles larger and more uniform.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1993.021940117
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  • 7
    Electronic Resource
    Electronic Resource
    Unsteady diffusion kinetics of Ziegler-Natta heterogeneous catalyst polymerization, 4Part 3: cf. ref.3.. Prediction of experimental results of propylene/ethylene/1-hexadecene terpolymerization (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 1807-1816 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The prediction, based on unsteady diffusion kinetics, of the enhancement of reactivity and incorporation of 1-hexadecene in its copolymerization with propylene on adding a small amount of ethylene (increase from 5,2 mol-% to 10,8 mol-% when 2% of ethylene was added, and to 16, 1 mol-% when 5% was added) was verified in the terpolymerization of propylene/ 1-hexadecene/ ethylene on a commercial Solvay-type δ-TiCl3 catalyst. The catalyst efficiency was thus also increased. These augmentations originate from the increase in diffusion coefficient of 1-hexadecene at the catalyst surface when the PP crystallinity decreases on introduction of ethylene. Calculation based on unsteady diffusion kinetics showed that the order of diffusion coefficients ethylene 〉 propylene 〉 1-hexadecene is reversed as the monomer concentration increases when the monomers are not at their equilibrium concentration. Sequence distribution as determined by means of 13C NMR revealed a tendency of blocky structure rather than a Bernoullian one. The terpolymer compositions obtained by means of an IR method developed in this work conform rather well with the NMR results. Results in this work not only support the unsteady diffusion kinetics but also provide a new route to prepare olefinic copolymer rubbers with heterogeneous titanium catalysts.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1993.021940627
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  • 8
    Electronic Resource
    Electronic Resource
    Removal of lead from aqueous solutions by Penicillium biomass (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 785-787 
    Details
    ISSN: 0006-3592
    Keywords: biosorption ; biosorbent ; Penicillium ; biomass ; lead ; wastewater treatment ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The removal of lead ions from aqueous solutions by adsorption on nonliving Penicillium chrysogenum biomass was studied. Biosorption of the Pb+2 ion was strongly affected by pH. Within a pH range of 4 to 5, the saturated sorption uptake of Pb+2 was 116 mg/g dry biomass, higher than that of activated charcoal and some other microorganisms. At pH 4.5, P. chrysogenum biomass exhibited selectivity for Pb+2 over other metal ions such as Cd+2, Cu+2, Zn+2, and As+3 Sorption preference for metals decreased in the following order: Pb 〉 Cd 〉 Cu 〉 Zn 〉 As. The sorption uptake of Pb+2 remained unchanged in the presence of Cu+2 and As+3, it decreased in the presence of Zn+2, and increased in the presence of Cd+2. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420615
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  • 9
    Electronic Resource
    Electronic Resource
    Thermal regeneration of the phenol-carbon system (1985)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 31 (1985), S. 496-498 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690310321
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  • 10
    Electronic Resource
    Electronic Resource
    Solution behavior of random copolymers of styrene with sodium-2-acrylamido-2-methylpropane sulfonate (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 1361-1371 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The nonaqueous solution behavior of random copolymers of styrene (ST) with sodium-2-acrylamido-2-methylpropane sulfonate (Na-AMPS) [poly(ST-Na-AMPS)] has been investigated using the transient electric birefringence (TEB) technique. The copolymers with varying high sulfonate contents (about 30-70 mol%), bridging the gap between conventional ionomers and classical polyelectrolytes, were dissolved in the solvent methylformamide (MFA) with a high permittivity ∊ of ca. 190. The solutions showed a negative birefringence at electric field strength E of the order of kV/cm. A typical Kerr effect was observed at low polymer concentrations C of ca. 10-3g/mL and electric field strengths of the order of kV/cm. However, the detailed, TEB studies demonstrated different behavior at two concentration regimes in dilute solution. At a low concentration regime (e.g., C ≤ 1 × 10-3g/mL for the copolymer with a 66.7 mol % sulfonate content) where the reduced viscosity exhibited a pronounced polyelectrolyte effect, the birefringence signal pattern showed a maximum before reaching a steady value. Additionally, during the rise at an applied electric field strength beyond a threshold value, it was observed that the nonexponential field-free decay was slower than the single exponential field-induced rise. The observed anomalous behavior was similar to those of a polyelectrolyte [sodium poly (styrene sulfonate)] in aqueous solution and might be attributed to the perturbation of the molecular shape by the applied electric field. At the higher concentration regime (e.g., C ≥ 4 × 10-3g/mL for the same copolymer with a 66.7 mol % sulfonate content) where the polyelectrolyte effects started to diminish as indicated by the viscosity study, the birefringence shape showed no variation with an increased electric field strength and the field-free decay turned out to be faster than the single exponential rise. The dissociation of ionic aggregates was tentatively interpreted to be responsible for this observation. It seems that by simply varying the polymer concentration, poly (ST-Na-AMPS) could behave either as a polyelectrolyte or as an ionomer in a single polar organic solvent.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1991.090291105
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