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  • 1
    Electronic Resource
    Electronic Resource
    Sequential backbone assignment of uniformly 13C-labeled RNAs by a two-dimensional P(CC)H-TOCSY triple resonance NMR experiment (1995)
    Springer
    Journal of biomolecular NMR 5 (1995), S. 82-86 
    Details
    ISSN: 1573-5001
    Keywords: Labeled RNA ; Triple resonance ; HeteroTOCSY ; Assignment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A new 1H−13C−31P triple resonance experiment is described which allows unambigous sequential backbone assignment in 13C-labeled oligonucleotides via through-bond coherence transfer from 31P via 13C to 1H. The approach employs INEPT to transfer coherence from 31P to 13C and homonuclear TOCSY to transfer the 13C coherence through the ribose ring, followed by 13C to 1H J-cross-polarisation. The efficiencies of the various possible transfer pathways are discussed. The most efficient route involves transfer of 31Pi coherence via C4′i and C4′i-1, because of the relatively large J′PC4 couplings involved. Via the homonuclear and heteronuclear mixing periods, the C4′i and C4′i-1 coherences are subsequently transferred to, amongst others, H1′i and H1′i-1, respectively, leading to a 2D 1H−31P spectrum which allows a sequential assignment in the 31P−1H1′ region of the spectrum, i.e. in the region where the proton resonances overlap least. The experiment is demonstrated on a 13C-labeled RNA hairpin with the sequence 5′(GGGC-CAAA-GCCU)3′.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227472
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  • 2
    Electronic Resource
    Electronic Resource
    XPS and UPS examinations of the formation of passive layers on Ni in 1 M sodium hydroxide and 0.5 M sulphuric acid (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 14 (1989), S. 121-131 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The passivation of nickel has been studied in 1 M NaOH and 0.5 M H2SO4 by XPS. An electrochemical specimen preparation and transfer to an ultra-high vacuum, without contact with oxygen, permits a detailed examination of the oxide growth with potential and time resolution. Quantitative evaluation of the data yields values for the thickness of the partial layers of the duplex film structure. The Ni/NiO/Ni(OH)2 sequence for the passive range and Ni/NiO/NiOOH sequence for the transpassive range in alkaline solutions have been confirmed by a detailed peak analysis, including angular-dependent XPS measurements. These results are closely related to the polarization curves. An interpretation is given on the basis of a simple semiconductor model involving the results of UPS and work function measurements. The data of the acidic and the alkaline electrolytes are related to each other and their differences are explained by the increased solubility for low pH of the outer Ni(OH)2 and NiOOH layers, respectively. These properties cause thinner films in acidic electrolytes and prevent the formation of a stable NiOOH overlayer for these conditions.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740140305
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  • 3
    Electronic Resource
    Electronic Resource
    Combined surface analytical and electrochemical study of the formation of passive layers on Fe/Cr alloys in 1 M NaOH (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 21 (1994), S. 514-525 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Combined XPS and electrochemical studies of the passivation of Fe/Cr alloys have been performed in 1 M NaOH. Argon ion sputtering and a specimen transfer within a closed system provide a reliable situation with well-controlled starting conditions for passivation transients and surface analytical studies with sufficient time resolution, especially at negative electrode potentials. The results for Fe/Cr are discussed on the basis of previous studies with the pure elements. The extremely slow dissolution of Cr(III) oxide and its relatively negative formation potential are responsible for the excellent passive behaviour of these alloys. Chromium(III) stabilizes Fe(II) and Fe(III) within the passive layer. Any Cr(III) enrichment is a consequence of preferential Fe dissolution. In 1 M NaOH the reduced solubility of Fe(III) oxide leads to an overlayer consisting mainly of Fe(III)oxide/hydroxide. The formation and oxidation of Fe(II) follows similar characteristics as found for oxide films on pure iron. Iron oxide components may, however, not be reduced to metal, as in the case of passive layers on pure Fe. These studies show that not only the final stationary state but also the process of passivation and the chemical changes of passive layers with potential and time can be investigated with XPS. Thus, one can obtain more reliable insight into the complicated processes leading to passivity.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740210803
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  • 4
    Electronic Resource
    Electronic Resource
    A combined ISS and XPS investigation of passive film formation on Fe53Ni (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 18 (1992), S. 269-276 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A surface analytical study of the Fe53Ni alloy passivation process in alkaline solution was carried out by ISS (ion scattering spectroscopy) and XPS (x-ray photoelectron spectroscopy).The ISS depth profiles of the passive films formed in 1 M NaOH show an iron-enriched outer part of the film that is about three monolayers thick and stays on the surface independently of the polarization potential. This finding may be related to the outer hydroxide Fe/Ni film identified by XPS. The inner part of the quasi-steady-state passive film is nickel enriched and its thickness grows linearly with the potential. The results obtained by ISS satisfactorily agree with those obtained on the same samples by XPS, which demonstrates that ISS can be used profitably as a semiquantitative tool for the investigation of thin surface layers; in addition, it provides a higher depth resolution than XPS.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740180405
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  • 5
    Electronic Resource
    Electronic Resource
    XPS and ISS examinations of electrode surfaces and passive layers with a specimen transfer in a closed system (1986)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 9 (1986), S. 357-365 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The application of UHV surface analytical methods to the study of electrodes and surface layers may be affected by changes introduced by contact with the laboratory atmosphere. Therefore, a specimen preparation and transfer in a closed system with its specifications is described. Three examples of its application are discussed: the examination of the electrode - electrolyte interface on Cu and the study of the formation of passive anodic oxides on Fe and on Fe—Cr alloys in 1 M NaOH.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740090603
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  • 6
    Electronic Resource
    Electronic Resource
    XPS and UPS examinations of Fe53Ni and Fe10Ni in 1 M NaOH and 0.005 M H2SO4 (1990)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 16 (1990), S. 271-277 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The formation of passive films as a function of time and potential on Fe53Ni in 1 M NaOH in 0.005 M H2SO4 + 0.495 M K2SO4 and on Fe10Ni in 1 M NaOH was studied by XPS. In order to avoid air oxidation and to minimize contamination of the samples, an electrochemical specimen preparation and transsfer system attached to the ultrahigh vacuum (UHV) system was used. Quantitative evaluation of the data yields the total thickness and the composition of passive layers. Characteristic changes of the spectra in the transpassive range for Fe53Ni in the alkaline electrolyte, which include a shift of the peaks of the oxide components to lower binding energies, are observed. They are interpreted as a decrease of the Fermi level towards the valence bend as the result of the oxidation of Ni (OH)2 to NiOOH. This is supported by UPS measurements in dependence of the passivation potential of the specimen, which show an increase in work function corresponding to the Fermi level shift.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740160157
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