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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of circular mitochondrial plasmids in three Pythium species (1991)
    Springer
    Current genetics 20 (1991), S. 91-97 
    Details
    ISSN: 1432-0983
    Keywords: Pythium ; Mitochondrial plasmid ; RNA transcript
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Four circular plasmids, with a monomer size ranging from 3.2 to 4.94 kb, have been identified in isolates of P. aphanidermatum (two different plasmids), P. torulosum, and an unidentified echinulate isolate. The mitochondrial location has been confirmed for three of the plasmids. Each fungal isolate contained a single plasmid, present in both monomeric and oligomeric forms; plasmid monomers were present as open circles and as supercoiled forms. Restriction maps of the plasmids were dissimilar. Hybridization studies using cloned plasmids revealed no DNA sequence similarity among the different plasmids or between the plasmids and the nuclear or mitochondrial genome of the isolates from which they were recovered. Hybridization of labeled plasmid DNA to Northern transfers of mitochondrial RNA for two isolates indicate that what appears to be the predominant RNA transcript is unit length in size. For three isolates, the plasmid was retained following subculturing and was present in all asexual and sexual single-spore progeny evaluated. For one isolate of P. aphanidermatum the plasmid was unstable and was lost during subculturing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00312771
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  • 2
    Electronic Resource
    Electronic Resource
    Linear mitochondrial genome organization in vivo in the genus Pythium (1995)
    Springer
    Current genetics 28 (1995), S. 225-234 
    Details
    ISSN: 1432-0983
    Keywords: Pythium ; Linear mitochondrial DNA ; Pulsed-field gel electrophoresis ; ATPase9 ; mtDNA replication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pulsed-field gel electrophoresis (PFGE) of isolates of Pythium oligandrum with linear mitochondrial genomes revealed a distinct band in ethidium bromide-stained gels similar in size to values estimated by restriction mapping of mitochondrial DNA (mtDNA). Southern analysis confirmed that these bands were mtDNA and indicated that linear genomes were present in unit-length size as well as multimers. Isolates of this species with circular mtDNA restriction maps also had low levels of linear mono- and multimers. visualized by Southern analysis of PFGE gels. Examination of 17 additional species revealed similar results; three species had distinct linear mtDNA bands in ethidium bromide-stained gels while the remainder had linear mono- and multi-mers in lower amounts detected only by Southern analysis. Sequence analysis of an isolate of P. oligandrum with a primarily circular mitochondrial genomic map and a low amount of linear molecules revealed that the small unique region of the circular map (which corresponded to the terminal region of linear genomes) was flanked by palindromic intrastrand complementary sequences separated by a unique 194-bp sequence. Sequences with similarity to ATPase9 coding regions from other organisms were located adjacent to this region. Sequences with similarity to mitochondrial origins of replication and autonomously replicating sequences were also located in this region: their potential involvement in the generation of linear molecules is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00309781
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  • 3
    Electronic Resource
    Electronic Resource
    Binders for higher-solids coatings. IV. Liquid-crystalline acrylic lacquers (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 36 (1988), S. 141-163 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: A previously reported synthetic procedure was used to graft oligo-p-hydroxybenzoic acid (oligo-PHBA) to COOH-functional acrylic copolymers. Most of the products were side-chain LC copolymers. Length of the mesogenic oligo-PHBA groups averaged up to five aromatic rings per group. Because these long mesogenic groups have a strong tendency to form LC domains, it was possible to prepare LC side-chain copolymers having as little as 5 mol % of mesogenic monomer. Thus this synthetic procedure provides a versatile route for exploration of the properties of LC copolymers having relatively few but especially effective mesogenic groups. The potential utility of such LC copolymers as binders for nonbake coatings was assessed. Variables studied were molecular weight and Tg of the acrylic copolymer backbone, number and average length of oligo-PHBA segments, and the presence or absence of a flexible spacer between the acrylic backbone and the PHBA segments. Optimum LC copolymers have moderate (15,000-30,000) Mn, low (-10°C) backbone Tg, and low (5-7.5 mol %) population of long (5 PHBA units) oligo-PHBA units. Such copolymers have two major advantages as coatings binders: They form concentrated, stable, low-viscosity dispersions in common solvents, a very desirable characteristic for application. Coating films have excellent adhesion to metal, and they have an extraordinary combination of hardness (H-2H) and impact resistance (〉 80 in. Ib). These properties are key indicators of coating performance and indicate that LC copolymers have excellent potential for use as binders for nonbake coatings. Other properties remain to be investigated.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070360112
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  • 4
    Electronic Resource
    Electronic Resource
    Graft copolymers of para-hydroxybenzoic acid (PHB). I. A general method for grafting mesogenic oligo-PHB to oligomers (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1109-1125 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method for grafting oligo-(p-hydroxybenzoic acid) to carboxyl-functional oligomers or polymers to give copolymers having mesogenic side chains was developed. The method employs dicyclohexylcarbodiimide (DCC) to promote esterification of PHB at mild temperatures and to remove water. Pyridine is used as solvent, and catalytic amounts of p-TSA are added to suppress side reactions. Grafting efficiencies are estimated to range from 74 to 90%. Ungrafted oligo-PHB and other by-products are readily removed. Structure assignments were supported by IR,1H-NMR, GPC, DSC and model compound studies. The method appears capable of grafting oligo-PHB side chains to any pyridine soluble oligomer or polymer having carboxyl groups and no other reactive groups that could interfere.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080250417
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  • 5
    Electronic Resource
    Electronic Resource
    High solids-content nanosize polymer latexes made by microemulsion polymerization (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 1075-1079 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymer nanoparticles were prepared from monomers such as styrene (St), butyl methacrylate (BMA), butyl acrylate (BA), methyl methacrylate (MMA), and methyl acrylate (MA) using a modified microemulsion polymerization process. With this process high polymer: surfactant weight ratios (7 : 1 or greater), relatively concentrated (10-30 wt.-%) latexes and small (10-20 nm) particle diameters were attained. Nucleation mechanisms were investigated through observations of the particle size change during the polymerization.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Cyclization during polyesterification: Isolation of an 18-member ring compound from reaction of phthalic anhydride with 2,2-dimethyl-1,3-propanediol (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 2517-2520 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410951
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  • 7
    Electronic Resource
    Electronic Resource
    Enhanced reactivity of melamine-formaldehyde resins by fractionation. Crosslinking at ambient temperature (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 1903-1909 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: A commercial hexakis(methoxymethyl)melamine (HMMM) resin was fractionated (1) by crystallization of the hexane-soluble fraction from hexane and (2) by partitioning the hexane-soluble and hexane-Insoluble fractions between alumina and various solvents. Crystallization afforded hexakis(methoxymethyl)melamine (1) of 90 to 95% purity. Partitioning afforded 12 fractions with altered proportions of polar and nonpolar species; the least polar fraction was spectroscopically and chromatographically similar to the crystallized material. Relative reactivities of certain fractions were estimated by 1H NMR studies of the rates of reaction with neopentyl alcohol in the presence of catalytic amounts of p-toluenesulfonic acid (p-TSA). It was found that the reactivity of fractions, rich in less-polar species, was substantially greater than that of the commercial HMMM resin, whereas reactivity of fractions, rich in polar species, was less. Reactivity was especially enhanced by removal of all active hydrogen species, notably those containing NH groups. A practical consequence of this result was that fully formylated and alkylated melamine resins could crosslink with polyols at substantially lower temperatures than the commercial HMMM resin, which contained NH groups. Therefore, room-temperature crosslinking was feasible.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070451105
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  • 8
    Electronic Resource
    Electronic Resource
    Rheological behavior of solutions of amphiphilic acrylic copolymers in mixed solvents (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 1927-1938 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: A descriptive model was developed, using viscometry and light scattering, that explains the anomalous rheological behavior of solutions of amphiphilic acrylic copolymers upon the addition of water. The rheological behavior can be explained by considering the relative magnitudes of three interactions: the intra-and intermolecular electrostatic interactions between the ionizable acid groups in the copolymer, the intramolecular hydrophobic in-teractions, and the intermolecular hydrophobic interactions. The initial addition of water enhances the ionization of the acid groups, causing the electrostatic interactions between the acid groups to dominate the other two interactions. This leads to expansion of the polymer molecules and, consequently, to a relatively constant viscosity during dilution with water. Upon attaining the maximum ionization of the acid groups on the chain, the intra-molecular hydrophobic interactions dominate the electrostatic repulsion, and the chains start to contract. Further addition of water leads to aggregation of the polymer chains into large polymolecular domains, resulting in a sharp decrease in the viscosity. Intermolecular hydrophobic interactions dominate the rheological behavior in this stage of water dilution. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    End-grafting of oligoesters based on terephthalic acid and linear diols for high solids coatings (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 1609-1618 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Oligomers derived from terephthalic acid and 1,6-hexanediol or 1,10-decanediol have been chemically modified through end-grafting with succinic anhydride or trimellitic anhydride followed by glycidyl neodecanoate. The grafted oligomers are paste-like semisolids or viscous liquids at room temperature. As the grafted oligomers are heated, their viscosity goes down to a minimum, then up to a maximum, and then down again. Combined DSC, crossed polarizing microscopy, and wide-angle x-ray diffraction indicate that the grafted oligomers form crystalline domains dispersed in amorphous phase. The grafted oligomers are soluble in common organic solvents, such as toluene, at lower concentrations (〈14-51 wt %) and form stable dispersions at higher concentrations. High solid coatings formulated with mel-amine or isocyanate resins gave glossy films with excellent combined hardness and impact resistance. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    13C-NMR studies of commercial and partially self-condensed hexakis(methoxymethyl)melamine (HMMM) resins (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 1237-1251 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: 13C-nuclear magnetic resonance (NMR) spectroscopy was employed to study the linkages in three commercial fully methylocated melamine-formaldehyde (HMMM) resins and their partially self-condensed resins by acid catalysis, in order to probe the structures linking melamine units. Distortionless enhancement by polarization transfer (DEPT) experiments show that the partially self-condensed resins contain both methylene ether and methylene linkages between melamine units. The extent of these linkages were estimated by quantitative 13C-NMR spectroscopy using inverse gated decoupling techniques. The results show that the ratios of methylene ether and methylene linkages to the triazine moiety vary from resin to resin. © 1996 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
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