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  • Inorganic Chemistry  (5)
  • Polymer and Materials Science  (4)
  • oxygen  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Mechanism of isothermal oxidation of the intel-metallic TiAl and of TiAl alloys (1992)
    Springer
    Oxidation of metals 38 (1992), S. 425-464 
    Details
    ISSN: 1573-4889
    Keywords: oxidation mechanism ; TiAl ; TiAl alloys ; air ; oxygen ; nitridation ; Ti-Al-O phase diagram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior of Ti36Al, Ti35Al-0.1C, Ti35Al-1.4V-0.1C, and Ti35 Al-5Nb-0.1C (mass-%) in air and oxygen has been studied between 700 and 1000°C with the major emphasis at 900°C. Generally an oxide scale consisting of two layers, an outward- and an inward-growing layer, formed. The outward-growing part of the scale consisted mainly of TiO2 (rutile), while the inward-growing part is composed of a mixture of TiO2 and α-Al2O3. A barrier layer of Al2O3 on TiAl between the inner and the outer part of the scale was visible for up to 300 hr. Under certain conditions, the Al2O3 barrier dissolved and re-precipitated in the outer TiO2 layer. This “shift” leads to an effect similar to breakaway oxidation. Only the alloy containing Nb formed a longlasting, protective Al2O3 layer, which was established at the metal/scale interface after an incubation period of 80–100 hr. During this time, Nb was enriched in the subsurface zone up to approximately 20 w/o. The growth of the oxide scale on TiAl-V obeyed a parabolic law, because no Al2O3 barrier layer formed; large Al2O3 particles were part of the outward-growing layer. A brittle α2-Ti3Al-layer rich in O formed beneath the oxide scale as a result of preferential Al oxidation particularly when oxidized in oxygen. Oxidation in air can lead also to formation of nitrides beneath the oxide scale. The nitridation can vary between the formation of isolated nitride particles and of a metal/Ti2AlN/ TiN/oxide, scale-layer system. Under certain conditions, nitride-layer formation seemed to favor protective Al2O23 formation at the metal/scale interface, however, in general nitridation was detrimental with the consequence that oxidation was generally more rapid in air than in oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00665663
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  • 2
    Electronic Resource
    Electronic Resource
    Oxygen regulated gene expression in facultatively anaerobic bacteria (1994)
    Springer
    Antonie van Leeuwenhoek 66 (1994), S. 3-22 
    Details
    ISSN: 1572-9699
    Keywords: facultatively anaerobic bacteria ; anaerobic gene regulation ; oxygen ; aerobic/anaerobic respiration ; metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In facultatively anaerobic bacteria such asEscherichia coli, oxygen and other electron acceptors fundamentally influence catabolic and anabolic pathways.E. coli is able to grow aerobically by respiration and in the absence of O2 by anaerobic respiration with nitrate, nitrite, fumarate, dimethylsulfoxide and trimethylamine N-oxide as acceptors or by fermentation. The expression of the various catabolic pathways occurs according to a hierarchy with 3 or 4 levels. Aerobic respiration at the highest level is followed by nitrate respiration (level 2), anaerobic respiration with the other acceptors (level 3) and fermentation. In other bacteria, different regulatory cascades with other underlying principles can be observed. Regulation of anabolism in response to O2 availability is important, too. It is caused by different requirements of cofactors or coenzymes in aerobic and anaerobic metabolism and by the requirement for different O2-independent biosynthetic routes under anoxia. The regulation mainly occurs at the transcriptional level. InE. coli, 4 global regulatory systems are known to be essential for the aerobic/anaerobic switch and the described hierarchy. A two-component sensor/regulator system comprising ArcB (sensor) and ArcA (transcriptional regulator) is responsible for regulation of aerobic metabolism. The FNR protein is a transcriptional sensor-regulator protein which regulates anaerobic respiratory genes in response to O2 availability. The gene activator FhlA regulates fermentative formate and hydrogen metabolism with formate as the inductor. ArcA/B and FNR directly respond to O2, FhlA indirectly by decreased levels of formate in the presence of O2. Regulation of nitrate/nitrite catabolism is effected by two 2-component sensor/regulator systems NarX(Q)/NarL(P) in response to nitrate/nitrite. Co-operation of the different regulatory systems at the target promoters which are in part under dual (or manifold) transcriptional control causes the expression according to the hierarchy. The sensing of the environmental signals by the sensor proteins or domains is not well understood so far. FNR, which acts presumably as a cytoplasmic ‘one component’ sensor-regulator, is suggested to sense directly cytoplasmic O2-levels corresponding to the environmental O2-levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00871629
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  • 3
    Electronic Resource
    Electronic Resource
    Prüfverfahren zur Wasserstoffversprödung bei Betonzusatzmitteln. Von A. Rauen, Schlußbericht zum Forschungsvorhaben IRB Verlag, Stuttgart 1994, Best. Nr. T2625, 18,30 DM (1996)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 47 (1996), S. 167-167 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19960470314
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  • 4
    Electronic Resource
    Electronic Resource
    VDI-Lexikon Werkstofftechnik, berichtigter Nachdruck, hrsg. von Hubert Gräfen, 1172 Seiten, 977 Bilder, 188 Tabellen, VDI-Verlag Düsseldorf 1993, 278,- DM, ISBN 3-18-400893-2 (1995)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 46 (1995), S. 388-388 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19950460613
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  • 5
    Electronic Resource
    Electronic Resource
    Werkstofftechnik: Aufbau, Eigenschaften und Verwendung der Metalle. G. Landsberger, 1. Auflage, Gela-Verlag für Luftfahrttechnik, Büttelborn, 1994, 44,- DM, ISBN 3-929845-01-6 (1995)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 46 (1995), S. 435-436 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19950460715
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  • 6
    Electronic Resource
    Electronic Resource
    Werkstoffkunde und Werkstoffprüfung für technische Berufe. Von E. Greven, 12. Auflage, durchgesehen und überarbeitet von Prof. Dr.-Ing. W. Margin, 304 Seiten, kartoniert, mit vielen Abb. und Tab., Verlag Handwerk und Technik, Hamburg 1994, DM 41,40, ISBN 3.582.02211.0 (1994)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 45 (1994), S. 680-680 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19940451210
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  • 7
    Electronic Resource
    Electronic Resource
    Schwermetall-π-Komplexe. IX. Die Kettenpolymere ∞1[(1,2- (CH3)2C6H4BiCl3)2], ∞1[(1,3) (CH3)2C6H4BiCl3)2] und ∞1[(1,4- (CH3)2C6H4BiCl3)2] (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1073-1082 
    Details
    ISSN: 0044-2313
    Keywords: Bismuth arene π-complexes ; bismuth xylene complexes ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heavy Metal π-Complexes. IX. The Chain Polymers ∞1[(1,2- (CH3)2C6H4BiCl3)2], ∞1[(1,3- (CH3)2C6H4BiCl3)2] and ∞1[(1,4- (CH3)2C6H4BiCl3)2]In the crystal structures of the three solid state complexes (C6H4(CH3)2BiCl3 (C6H4(CH3)2 = o-xylene: 1, m-xylene: 2, p-xylene: 3) quasi-dimeric units of almost undistorted, arene coordinated BiCl3 fragments can be found that are further associated via additional Bi—Cl contacts to form one-dimensional polymeric chains. Whereas the chains of 2 and 3 are constituted by Bi2Cl2 four-membered rings only, further Cl-bridging in 1 leads to additional trigonal-bipyramidal arrangements with Bi atoms exhibiting coordination numbers of 3 + 3 + 1 and 3 + 2 + 1, respectively (prim. + sec. Cl contacts + arene). The arene-metal bonding is characterized by Bi-arene distances in the range from 297 - 306 pm, including ring slippages of 24 -41 pm and 73 pm with the Bi atoms being six and seven coordinated, respectively. The direction of this slipping with respect to the arene's methylation sites cannot be understood in terms of electronic influences but is shown to be caused by steric demands. The values IP1 of the arenes prove to determine the colours of the complexes.
    Notes: In den Festkörperstrukturen der drei Komplexe (C6H4(CH3)2)BiCl3 (C6H4(CH3)2 = o-Xylol: 1, m-Xylol: 2, p-Xylol: 3) findet man quasidimere Einheiten fast unverzerrter, arenkoordinierter BiCl3-Fragmente, die über zusätzliche Bi—Cl-Kontakte zu eindimensionalen polymeren Ketten assoziiert sind. Während die Ketten von 2 und 3 nur aus Bi2Cl2-Vierringsegmenten bestehen, führt eine weitere Verbrückung in 1 zusätzlich zu trigonal-bipyramidalen Anordnungen mit Bi-Atomen der Koordinationszahlen 3 + 3 + 1 bzw. 3 + 2 + 1 (prim. + sek. Cl-Kontakte + Aren). Die Bindung des Arens an das Metall ist durch Bi-Aren-Abstände zwischen 297 und 306 pm charakterisiert. Die „ring slippage“ beträgt 24-41 bzw. 73 pm bei den sechsfach bzw. siebenfach koordinierten Bi-Atomen. Die Richtung dieser Verschiebung in bezug auf die Lage der Methylgruppen des Arens kann nicht auf elektronischer Basis interpretiert werden, sondern ist sterisch verursacht. Für die Farbe der Komplexe erweist sich IP1 des Arens als bestimmend.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190618
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  • 8
    Electronic Resource
    Electronic Resource
    Zur Kenntnis des K[OsF6]-Typs: Über die Konstitution von BaSnF6 und BaTiF6Professor Hans-Joachim Seifert zum 60. Geburtstage am 9. November 1990 gewidmet (1990)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 591 (1990), S. 7-16 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the K[OsF6] Type: The Constitution of BaSnF6 and BaTiF6Colourless single crystals of Ba[SnF6], a hitherto unknown representative of the K[OsF6] type as well Ba[TiF6] (Ba[SiF6] type) have been obtained.Ba[SnF6] (“Sealed copper) tube”; 28 d; 750°C; BaF2/met. Sn/CuF2 with Ba:Sn:Cu = 1:1:2) crystalizes in SPCG. R3 with a = 742.79(9) pm and c = 741.8(2) pm, (Four-circle diffractometer, Siemens AED 2, MoKα, R = 3.64% and Rw = 3.79%, 344 of 2047 Io(hkl). Ba[TiF6] (“Sealed copper tube”; 35 d; 650°C; BaF2/met. Ti/CuF2 with Ba:Ti:Cu = 1:1:2) crystalizes in the space group R3m with a = 736.76(9) pm and c = 725.2(1) pm, (Four-circle diffractometer, Siemens AED 2, MoKα, R = 2.33% and Rw = 2.31%, 202 of 2004 Io (hkl).BaSnF6 which is characterized by single crystal data is the first representative of the K[OsF6] type. Its structure is compared with that of Ba[TiF6], a fellow of the Ba[SiF6] type.The Madelung Part of Lattice Energy, MAPLE, “Mean Fictive Ionic Radii, MEFIR”, and “Effective Coordination Numbers, ECoN”, as well as the Charge Distribution, “CHARDI”, are calculated and discussed.
    Notes: Erstmals wurden farblose, rhomboedrische Einkristalle von Ba[SnF6] („Kupferbömbchen“; 28 d; 750°C; Gemenge BaF2/met. Sn/CuF2 im Verhältnis Ba:Sn;Cu = 1:1:2) und Ba[TiF6] („Kupferbombe“; 35 d; 650°C; Gemenge BaF2/met. Ti/CuF2 im Verhältnis Ba:Ti:Cu=1:1:2) erhalten. Ba[SnF6] kristallisiert in der Raumgruppe R3 mit a = 742,79(9) pm und c = 741,8(2) pm, Vierkreisdiffraktometer Siemens AED 2, MoKα, R = 3,64% und Rw = 3,79% mit 344 aus 2047 gemessenen Io(hkl), Ba[TiF6] dagegen in R3m mit a = 736,76(9) pm und c = 725,2(1) pm, (Vierkreisdiffraktometer Siemens) AED 2, MoKα, R = 2,33% und Rw = 2,31% mit 202 aus 2004 gemessenen Io(hkl)) kristallisiert.Ba[SnF6] ist der erste Vertreter des K[OsF6]-Typs, dessen Struktur durch Einkristalldaten belegt wird. Die Struktur wird mit der von Ba[TiF6], einem Vertreter des Ba[SiF6]-Typs, verglichen.Der Madelunganteil der Gitterenergie, MAPLE, sowie „Mittlere Fiktive Ionenradien, MEFIR“, und „Effektive Koordinationszahlen, ECoN“, sowie die „Ladungsverteilungen“, „CHARDI“, werden berechnet und diskutiert.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19905910102
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  • 9
    Electronic Resource
    Electronic Resource
    Komplexbildung des tert-Butyliminovanadium(V)-trichlorids mit O-Donor-LigandenProfessor Manfred Regitz zum 60. Geburtstag gewidmet (1995)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 1663-1671 
    Details
    ISSN: 0044-2313
    Keywords: tert-Butyliminovanadium(V) trichloride ; coordination compounds ; 1H, 13C, 51V NMR ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Coordination Compounds of tert-Butyliminovanadium(V) Trichloride with O-Donor-LigandsThe reaction of tert-butyliminovanadium(V)trichloride (1) with cyclic and acyclic ethers, ethylene carbonate and thietane has been studied. The 1:1-complexes have a different stability; reversible and irreversible cleavage of ether in the coordination sphere of the vanadium atom rearranging in ω-chloroalkanolato ligands are observed. The reaction of 1 with 2-chloroethanol, 3-chloropropanol and 5-chloropentanol yields the complexes tC4H9N = V(OR)Cl2 (R = CH2CH2CH2CH2CH2Cl) and [tC4H9N = V(OR)Cl2 · ROH]; in the presence of triethylamine the disubstituted compounds tC4H9N = V(OR)2Cl are formed. The 51V NMR spectra are discussed. The crystal structure of [tC4H9N = VCl3 · DME] (12) and [tC4H9N = V(OCH2CH2Cl)Cl2 · HOCH2CH2Cl] (13) has been determined. The vanadium atoms in 13 have a distorted octahedral coordination and are linked by the oxygen atoms of the 2-chloroethanolato ligands forming a binuclear complex. In solution molecular weight measurement and 51V NMR data indicate the equilibrium between a mononuclear complex 13 and its isomer [tC4H9N = V(OCH2CH2Cl)2Cl · HCl].
    Notes: Die Reaktion des tert-Butyliminovanadium(V)-trichlorids (1) mit cyclischen und acyclischen Ethern, Ethylencarbonat und Thietan wurde untersucht. Die 1:1-Komplexe zeigen eine unterschiedliche Stabilität; reversible und irreversible Etherspaltungen in der Koordinationssphäre des Vanadiumatoms unter Umlagerung in ω-Chloralkanolato-Liganden werden beobachtet. Die Reaktion von 1 mit 2-Chlorethanol, 3-Chlorpropanol und 5-Chlorpentanol liefert die Komplexe tC4H9N = V(OR)Cl2 (R = CH2CH2CH2CH2CH2Cl) und [tC4H9N = V(OR)Cl2 ω HOR]; in Gegenwart von Triethylamin als Hilfsbase werden die disubstituierten Verbindungen tC4H9N = V(OR)2Cl gebildet. Die 51V-NMR-Spektren werden diskutiert. Die Kristallstruktur der Komplexe [tC4H9N = VCl3 · DME] (12) und [tC4H9N = V(OCH2CH2Cl)Cl2 · HOCH2CH2Cl] (13) wurde bestimmt. In 13 sind die verzerrt oktaedrisch koordinierten Vanadiumatome über die O-Atome der 2-Chlorethanolato-Liganden zu einem zweikernigen Komplex verknüpft, während in Lösung ein einkerniger Komplex im Gleichgewicht mit dem Isomeren [tC4H9N = V(OCH2CH2Cl)2Cl · HCl] vorliegt.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19956211009
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  • 10
    Electronic Resource
    Electronic Resource
    Oxo- und Thiotantal(V)-Verbindungen: Synthese von TaOX3 und TaSX3 (X = OR, SR) (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1812-1817 
    Details
    ISSN: 0044-2313
    Keywords: Chloro, oxo and thiotantalum(V) compounds ; syntheses ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Oxo- and Thiotantalum(V) Compounds: Synthesis of TaOX3 and TaSX3 (X = OR, SR)TaO(OR)3 [R = tC4H9, Mes* (2)], TaO(SR)3 [R = tC4H9, p-Tolyl], TaS(OR)3 [R = tC4H9, Mes* (6)] and TaS(SR)3 [R = tC4H9, p-Tolyl] have been prepared by reaction of TaOCl3 and TaSCl3 with LiOR or LiSR. The reaction of TaCl5 with an excess of LiOMes* yields the chlorotantalum(V)compounds TaCl3(OMes*)2 and TaCl2(OMes*)3 (10). The synthesis of TaCl2(nC4H9)(OMes*)2 (11), Ta(Sp-Tolyl)5 and TaCl2(OEt)3 · C5H5N are also described. 2, 6, 10 and 11 decompose in benzolic solution or by heating under vacuum splitting off 2,4,6-tri-tert-butyl-phenol, n-butane respectively, and forming cyclometallated tantalum(V) complexes with the bidentate ligand OC6H2tBu2CMe2CH2. TaCl2(OEt)3 was investigated by X-ray diffraction analysis; the crystal structure has been found to be a binuclear tantalum complex with two bridging ethoxo ligands.
    Notes: TaO(OR)3 [R = tC4H9, Mes* (2)], TaO(SR)3 [R = tC4H9, p-Tolyl], TaS(OR)3 [R = tC4H9, Mes* (6)] und TaS(SR)3[ R = tC4H9, p-Tolyl] werden dargestellt durch Reaktion von TaOCl3 und TaSCl3 mit LiOR oder LiSR. Die Umsetzung von TaCl5 mit überschüssigem LiOMes* führt zu den Chlorotantal(V)-Verbindungen TaCl3(OMes*)2 und TaCl2(OMes*)3 (10). Darüber hinaus wird die Synthese von TaCl2(nC4H9)(OMes*)2 (11), Ta(Sp-Tolyl)5 und TaCl2(OEt)3 · C5H5N beschrieben. 2, 6, 10 und 11 zersetzen sich in benzolischer Lösung oder beim Erhitzen i. Vak. unter Abspaltung von 2,4,6-Tri-tert-butyl-phenol bzw. n-Butan und Bildung von cyclometallierten Tantal(V)-Verbindungen mit dem zweizähnigen Liganden OC6H2tBu2CMe2CH2. Die Kristallstruktur von TaCl2(OEt)3 wurde bestimmt; im zweikernigen Komplex sind die Tantalatome über zwei Ethoxo-Liganden verbrückt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946201025
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