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  • 1
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 27 (1997), S. 118-130 
    ISSN: 0887-3585
    Schlagwort(e): homology modeling ; glutathione transferases ; theta class GSTs ; glutathione ; menaphthyl sulfate ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: A tertiary model of the human GSTT2 Theta class glutathione transferase is presented based on the recently solved crystal structure of a related thetalike isoenzyme from Lucilia cuprina. Although the N-terminal domains are quite homologous, the C-terminal domains share less than about 20% identity. The model is used to consolidate the role of Ser 11 in the active site of the enzyme as well as to identify other residues and mechanisms of likely catalytic importance. The T2 subfamily of theta class enzymes have been shown to inactivate reactive sulfate esters arising from arylmethanols. A possible reaction pathway involving the conjugation of glutathione with one such sulfate ester, 1-menaphthyl-sulfate, is described. It is also proposed that the C-terminal region of the enzyme plays an important role in allowing substrate access to the active site. Proteins 27:118-130 © 1997 Wiley-Liss, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 357-366 
    ISSN: 0887-624X
    Schlagwort(e): surface graft copolymerization ; adhesive-free adhesion ; polycarbonate ; XPS ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The surfaces of ozone-pretreated polycarbonate films were subjected to further modification by thermally induced graft copolymerization with acrylic acid (AAc), sodium salt of styrene sulfonic acid (NaSS), N,N-dimethylacrylamide (DMAA), N,N-(dimethylamino)ethyl methacrylate (DMAEMA) and 3-dimethyl(methacryloyl ethyl)-ammonium propanesulfonate (DMAPS) monomers. The structure and composition at the copolymer interface were studied by angle-resolved X-ray photoelectron spectroscopy (XPS). For polycarbonate films with a substantial amount of grafted polymer, the hydrophilic graft penetrates or becomes partially submerged beneath a thin surface layer of dense substrate chains. This microstructure was further supported by the water contact angle measurements. Adhesive-free adhesion studies revealed that the AAc, DMAA or DMAPS graft copolymerized polycarbonate film surface adhered strongly to another similarly modified surface (homo-interface) when brought into direct contact in the presence of water and subsequently dried. The development of the lap shear strength is dependent on the concentration of the surface graft, the microstructure of the grafted surface, the adhesion (drying) time, and the nature of the interfacial interaction. The simultaneous presence of chain entanglement and electrostatic interaction readily results in substantially enhanced adhesion strengths between two DMAPS graft copolymerized surfaces or between an AAc and a DMAA graft copolymerized surface (hetero-interface). XPS analyses of the delaminated surfaces suggest that failure occurred cohesively below the graft-substrate interface. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 357-366, 1998
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 3107-3114 
    ISSN: 0887-624X
    Schlagwort(e): PTFE ; auto-adhesion ; surface grafting ; amphoteric monomer ; Ar plasma ; XPS ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The surfaces of Ar plasma-pretreated polytetrafluoroethylene (PTFE) films are further functionalized via UV-induced graft copolymerization with amphoteric N,N′-dimethyl(methacryloylethyl)ammonium propansulfonate (DMAPS) either in Ar atmosphere, or under atmospheric conditions and in the absence of a polymerization initiator. The so-modified PTFE films from either process are capable of exhibiting adhesive-free adhesion or auto-adhesion with one another when brought into intimate contact in the presence of a small quantity of water. The lap shear adhesion strength increases with increasing graft concentration and can readily exceed the yield strength of the PTFE substrate. Two plasma-pretreated PTFE films also readily undergo thermal graft copolymerization with concurrent lamination when lapped together in the presence of a small quantity of the DMAPS monomer solution at elevated temperature in the atmosphere. The surface compositions of the graft-copolymerized PTFE films and the delaminated surfaces were characterized by X-ray photoelectron spectroscopy (XPS). In most cases, adhesional failure occurred near the graft-substrate interphase. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3107-3114, 1998
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 5 (1994), S. 171-177 
    ISSN: 1042-7147
    Schlagwort(e): Polyaniline ; XPS ; Charge transfer ; Oxidation states ; Films ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Four modes of charge transfer interactions in polyaniline (PAN), viz. acid protonation, self-doping, charge transfer interactions with organic acceptors, and charge transfer interactions with surface grafted functional polymers have been studied by X-ray photoelectron spectroscopy (XPS). In the case of acid protonation, the protonation behavior of volatile and non-volatile acid differs. The structures of sulfonated leucomeraldine (LM) and nigraniline (NA) are similar to those of sulfonated and self-protonated emeraldine (EM). A substantially higher degree of charge transfer interaction with the organic acceptors is observed for EM film that has been subjected to one cycle of acid/base treatment. The charge transfer interactions with the organic acceptors have proceeded further than the pure formation of molecular complexes. Both pristine and Ar plasma or O3 pretreated EM films are susceptible to surface modifications by graft copolymerization. The protonic acid functional groups of the graft readily give rise to a self-protonated EM surface.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 5 (1994), S. 837-842 
    ISSN: 1042-7147
    Schlagwort(e): Polyolefin ; Fluoropolymer ; Polyester ; Graft Polymerization ; Surface structure ; XPS ; SIMS ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Pristine and argon plasma pretreated polytetrafluoroethylene (PTFE), polystyrene (PS), high-density polyethylene (HDPE) and poly(ethylene terrephthalate) (PET) films have been subjected to near-UV light-induced graft polymerization with water-soluble acrylamide (AAm), the sodium salt of styrene sulfonic acid (NaSS), acrylic acid (AAc) and N,N-dimethylaminoethylmethylacrylate (DMAEMA) monomers. The structure and composition at the substrate surface with grafted polymer were studied by angle-resolved X-ray photoelectron spectroscopy (XPS). In most cases, the density of surface grafting is enhanced by plasma pretreatment. For each polymer substrate with a substantial amount of grafting, the hydrophilic graft penetrates or becomes partially submerged beneath a thin surface layer of dense substrate chains. This stratified microstructure is consistent with the static secondary ion mass spectroscopy (SIMS) and Ar+ beam depth profiling results. The two latter techniques also suggest that when the grafted polymer has a bulky substituent, there is less efficient penetration of the grafted polymer below the surface.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 9 (1991), S. 295-295 
    ISSN: 0263-6484
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 59 (1994), S. 31-36 
    ISSN: 0268-2575
    Schlagwort(e): polyaniline ; Au reduction ; acid solution ; redox states ; XPS ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The oxidation of the leucoemeraldine (LM) and emeraldine (EM) states of polyaniline (PAN) and the subsequent reprotonation and reduction of the nigraniline (NA) and pernigraniline (PNA) in acid gold solution were utilized for the spontaneous and sustained reduction of gold. The rate of Au reduction is strongly dependent on the intrinsic oxidation state of the polymer and the polymer surface area. The rate also increases with decreasing pH of the chloroauric solution to about pH ∼ 1. X-ray photoelectron spectroscopic (XPS) results indicate that only elemental gold or Au(0) accumulates on the polymer surface. The N1s core-level spectra of the protonated and base form of EM films after Au reduction confirm that the intrinsic structure of the polymer remains intact. The process, however, is limited by the decreasing effective surface area of the polymer due to Au deposition. The results indicate that an LM film accumulated up to five times its own weight of Au (Au/monomer mole ratio 〉 2) before the recovery rate was significantly retarded.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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