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  • 1
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Schwingungsspektren kristalliner Hexachlorocerate(IV), R2CeCl6Eine vollständige Zuordnung aller Fundamentalbanden in den Spektren kristalliner R2CeCl6, die zu den Ce—Cl-Schwingungen gehören, wurde unter Benutzung von Daten über Kombinationsschwingungen und im Raman-Spektrum aktiver Oberschwingungen vorgenommen. Die Vermutung über die Existenz einer isolierten [CeCl62-]-Gruppe, die in Kristallen mit einer genügend hohen Gitterpunktsymmetrie eine oktaedrische Struktur aufweist, konnte bestätigt werden. Auf der Grundlage des experimentellen Materials und seiner Deutung wird die Vermutung über das Auftreten eines Pseudo-Jahn-Teller-Effektes in der Hexachloroceraten(IV) geäußert.
    Notes: A complete assignment of all fundamentals in the spectra of crystalline R2CeCl6 belonging to the Ce—Cl vibrations was undertaken using data about combination bands and active in the Raman spectrum overtones. The assumption of the presence of a separate [CeCl62-] group possessing an octahedral structure in crystals with a sufficient high site symmetry has been confirmed. Based on the experimental material and its interpretation a presumption concerning the appearence of a pseudo-Jahn-Teller effect in the hexachlorocerates(IV) was supposed.
    Additional Material: 2 Ill.
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  • 2
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Über die Säure-Base-Eigenschaften des Di- und Tetrafluorxenons in Reaktionen bei erhöhten TemperaturenEs wurde die Reaktion von Xenondifluorid und Xenontetrafluorid mit Fluorkomplex-Verbindungen verschiedener Übergangsmetalle bei erhöhter Temperatur untersucht. Unter diesen Bedingungen wurde die Bildung von Anionenkomplexen M2XeIVF6 festgestellt. Es wurde gezeigt, daß XeF4 unabhängig davon, ob es direkt in die Reaktion eingeführt wird oder dort aus XeF2 entsteht, zwei typische Eigenschaften aufweist: die eines Oxydationsmittels (〉 300°C) und einer Säure (zwischen 150°C und 300°C). Das Reaktionsverhalten des XeF4 hängt ferner von den Eigenschaften des Reaktionspartners ab. Die Eigenschaften der Xenonfluoride als Lewis-Säuren folgen der Reihe: XeF6 ≈ XeF4 ≫ XeF2.
    Notes: Reaction of xenon di- and tetrafluoride with different transition element fluorocomplexes at high temperatures has been studied. The formation of XeIV anionic complexes M2XeF6 has been found. XeF4 is shown to reveal two kinds of properties: oxidative (higher than 300°C) and acidic (between 150-300°C), independently whether it was initially introduced into the system or arised in it from XeF2. The reaction path of xenon tetrafluoride is shown to depend upon the other reagent properties. The conclusion is made that Lewis acidic properties of xenon fluorides decrease as follows: XeF6 ≈ XeF4 ≫ XeF2.
    Additional Material: 1 Ill.
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  • 3
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Über die Umsetzung der Di- und Tetrafluoride des Xenons mit Fluoriden der AlkalimetalleDie Umsetzung von XeF2 und XeF4 mit Verbindungen des Typs MF (M = Na, K, Rb, Cs) wird untersucht. Es bilden sich dabei Hexafluoroxenate(IV) mit der Summenformel M2XeF6, die das oktaedrische Anion XeF62- enthalten. Cs2XeF6 und Rb2XeF6 bilden monokline Kristalle (a0 = 853,7(5); b0 = 669,6(2); c0 = 843,6(5) pm; β = 121,7(1)° für Cs2XeF6 und a0 = 812,6(4); b0 = 631,9(2); c0 = 795,6(4) pm; β = 121,5(1)° für Rb2XeF6). K2XeF6: tetragonal mit a0 = 868,8(2); c0 = 747,8(2) pm; Na2XeF6: hexagonal mit a0 = 642,1(3); c0 = 844,8(5) pm. Es wird gezeigt, daß sich die Verbindungen M2XeF6 inkongruent in wasserfreiem HF lösen, wobei sich unter anderem das Solvolyseprodukt XeF4 bildet. Es wird nachgewiesen, daß die Thermolyse von M2XeIVF6 und M2XeVIF8 unter ähnlichen Bedingungen abläuft.
    Notes: Interaction of XeF2 or XeF4 with MF (M = Na, K, Rb, Cs) has been studied. Hexafluoroxenates(IV) M2XeF6 containing the octahedral XeF62- anion (in accordance with spectroscopy data) were formed in the reaction. Cs2XeF6 and Rb2XeF6 form monoclynic crystals (a0 = 853.7(5); b0 = 669.6(2); c0 = 843.6(5) pm; β = 121.7(1)° and a0 = 812.6(4); b0 = 631.9(2); c0 = 795.6(4) pm; β = 121.5(1)°, respectively). K2XeF6 has a tetragonal lattice (a0 = 868.8(2); c0 = 747.8(2) pm), while Na2XeF6 has a hexagonal one (a0 = 642.1(3); c0 = 844.8(5) pm). M2XeF6 is shown to dissolve in unhydrous HF incongruently, one of the solvolitic products being XeF4. Thermolysis of M2XeIVF6 and M2XeVIF8 were shown to proceed under similar temperatures.
    Additional Material: 4 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 81-84 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 new approach to the quantitative evaluation of the thickness hi and the volume fraction Vi of the interfacial layer in polyimide coatings has been developed using the model of a one-sided polymer coating as a three-phase system (a substrate, an interfacial layer and a polymer matrix) and the method of differential scanning calorimetry. The new approach is characterized by the fact that a “pure” polymer matrix is modeled with the help of free films obtained on mercury. The formulas for the calculation of the thickness and volume fraction of the interfacial layer have been proposed. The value hi has been determined in polymer coatings of different thicknesses on aluminium foil. This parameter has been shown to be independent of the film thickness if the latter is not larger than the length of the interfacial layer. An assumption has been made about the “mechanical” origin of thick (〉 1-5 μm) interfacial layers, and their relaxation character has been revealed.
    Additional Material: 4 Ill.
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  • 5
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Aminolyse von makroporösen Copolymeren aus Glycidylmethacrylat und Ethylendimethacrylat führte zu Sorbentien mit einem unterschiedlichen Gehalt an Amino-und Hydroxygruppen. Es wurde die Abhängigkeit zwischen strukturellen Parametern und der Schwefeldioxidsorption auf der einen und der Konzentration des Vernetzungsmittels und der porogenen Lösungsmittel in der Polymerisationsmischung auf der anderen Seite untersucht. Die Schwefeldioxidsorption hängt von der geometrischen Struktur des Sorbens, der Konzentration, der chemischen Struktur und der Erreichbarkeit der funktionellen Gruppen ab.
    Notes: Macroporous copolymers of 2,3-epoxypropyl methacrylate and ethylenedimethacrylate modified by aminolysis yielded sorbents with various contents of amino and hydroxy groups. The dependences of structural characteristics of these sorbents and of the sorption of sulphur dioxide on the content of crosslinking agent and on the cyclohexanol/dodecanol ratio used as the porogenic medium in the preparation of copolymers were investigated. The sorption of sulphur dioxide depends on the geometrical structure of the sorbent, concentration, chemical structure and accessibility of functional groups.
    Additional Material: 7 Ill.
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  • 6
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A tool was developed for enhancement of plasmid penetration into an intact cell, based on increasing DNA hydrophobicity via inclusion into a soluble interpolyelectrolyte complex (IPC) with polycations. The characteristics of formation of DNA IPC with synthetic polycations [poly(N-ethyl-4-vinylpyridinium)bromide (PVP) and PVP modified with 3% of N-cetyl-4-vinylpyridinium units (PVP-C)] were studied using ultracentrifugation and polyacrylamide gel electrophoresis methods. The conditions were established under which the mixing of DNA and polycation aqueous solutions results in the selfassembly of soluble IPC species. Incorporation of DNA into IPC results in the enhancement of DNA binding with isolated Bacillus subtilis membranes. A considerable increase in the efficiency of transformation of B. subtilis cells with pBC16 plasmid resulted from incorporation of the plasmid into the IPC with PVP and CVP.
    Additional Material: 6 Ill.
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  • 7
    Publication Date: 2014-10-25
    Description: Author(s): Alexei D. Kiselev and Vladimir G. Chigrinov In order to explore electric-field-induced transformations of polarization singularities in the polarization-resolved angular (conoscopic) patterns emerging after deformed-helix ferroelectric liquid crystal (DHFLC) cells with subwavelength helix pitch, we combine the transfer matrix formalism with t... [Phys. Rev. E 90, 042504] Published Fri Oct 24, 2014
    Keywords: Liquid Crystals
    Print ISSN: 1539-3755
    Electronic ISSN: 1550-2376
    Topics: Physics
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  • 8
    Publication Date: 2015-12-03
    Description: Author(s): Svetlana P. Kotova, Sergey A. Samagin, Evgeny P. Pozhidaev, and Alexei D. Kiselev We study both experimentally and theoretically modulation of light in a planar aligned deformed-helix ferroelectric liquid crystal (DHFLC) cell with subwavelength helix pitch, which is also known as a short-pitch DHFLC. In our experiments, the azimuthal angle of the in-plane optical axis and electri… [Phys. Rev. E 92, 062502] Published Tue Dec 01, 2015
    Keywords: Liquid Crystals
    Print ISSN: 1539-3755
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  • 9
    Publication Date: 2017-03-28
    Description: Author(s): Vladimir V. Kesaev, Alexei D. Kiselev, and Evgeny P. Pozhidaev We study the electro-optic properties of subwavelength-pitch deformed-helix ferroelectric liquid crystals (DHFLC) illuminated with unpolarized light. In the experimental setup based on the Mach-Zehnder interferometer, it was observed that the reference and the sample beams being both unpolarized pro… [Phys. Rev. E 95, 032705] Published Mon Mar 27, 2017
    Keywords: Liquid Crystals
    Print ISSN: 1539-3755
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  • 10
    Publication Date: 2013-05-17
    Description: Author(s): Evgeny P. Pozhidaev, Alexei D. Kiselev, Abhishek Kumar Srivastava, Vladimir G. Chigrinov, Hoi-Sing Kwok, and Maxim V. Minchenko We study both theoretically and experimentally the electro-optical properties of vertically aligned deformed helix ferroelectric liquid crystals (VADHFLC) with subwavelength pitch that are governed by the electrically induced optical biaxiality of the smectic helical structure. The key theoretical r... [Phys. Rev. E 87, 052502] Published Thu May 16, 2013
    Keywords: Liquid Crystals
    Print ISSN: 1539-3755
    Electronic ISSN: 1550-2376
    Topics: Physics
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