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  • 1
    Electronic Resource
    Electronic Resource
    Composites from furfuryl alcohol and inorganic solids by cationic initiation, 3Part 2: cf. ref.1.. Scanning electron microscopic investigations of solid poly(furfuryl alcohol)-silica composites (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 208 (1993), S. 125-131 
    Details
    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: Composites von Siliciumdioxid mit aufgepfropftem Poly(furfurylalkoho1) mit unterschiedlichen Pfropfgraden wurden mittels Rasterelektronenmikroskopie, Elementaranalyse und UV/Vis-Reflexionsspektroskopie untersucht. Die Größe der für die Pfropfung verwendeten Siliciumdioxid-Partikel bleibt bis zu einem Pfropfgrad von 30% unverändert. Ein Gehalt von mehr als 35 Gew.-% Polymerem verbessert die Bindung der Partikel untereinander, da eine Vernetzung des auf der Oberfläche gebundenen Poly(furfurylalkoho1)s mit dem sich in Lösung befindenden zum Agglomerieren der Partikel führt. Ein allgemeines Modell für vernetzte Poyl(furfurylalkoho1)-Silici-umdioxid-Composites wird vorgeschlagen.
    Notes: Composites of poly(furfuryl alcohol) grafted onto silica, with different percentage of grafting, have been investigated by scanning electron microscopy, elemental analysis and UV/Vis-reflectance spectroscopy. The size of the silica particles used for the coating procedure is not changed till a percentage of grafting to around 30%. A content of polymer higher than 35 wt.-% enhances the bonding between the particles due to the crosslinking of poly(furfuryl alcohol) on the surface with those in solution leading to the agglomeration of the particles. A general model of cross-linked poly(furfuryl alcohol)-silica composites is suggested.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052080112
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  • 2
    Electronic Resource
    Electronic Resource
    New oligomers with isatin. Condensation reactions of thiophene and 2,2′-bithiophene with isatin (1990)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 178 (1990), S. 1-16 
    Details
    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: Die seit langem in der Literatur als “Indophenin-Reaktion” bekannte Umsetzung von Isatin mit Thiophen wurde systematisch untersucht und auf die Umsetzung mit Bithiophen erweitert. Die Reaktionsprodukte wurden isoliert und durch FT-IR, UV, 1H-NMR, 13C-NMR sowie GPC charakterisiert.Im Gegensatz zu den Literaturdaten wurden Reaktionsprodukte mit höheren Molgewichten und anderer Molmassenverteilung gefunden. Die Reaktionsbedingungen - Lösungsmittel, Temperatur und Konzentration - sind für den Reaktionsablauf und die entstehenden Produkte von entscheidender Bedeutung.Füur die oligomeren Reaktionsprodukte werden neue Strukturen vorgeschlagen, die in Übereinstimmung mit allen analytischen Daten sind. Anhand eines Formelschemas werden die Reaktionen des Isatins mit Thiophen (Bithiophen) erläutert.
    Notes: A systematic study of the well-known indophenin reaction between isatin and thiophene was extended to embrace bithiophene. The products of the reactions were isolated and characterized by FT-IR, UV, 1H-NMR, 13C-NMR, and GPC. The values of the thus determined molar masses and molar mass distributions differed from the data given in the literature. The reaction conditions - solvent, temperature, and concentration - are of crucial importance for the course of the reaction and the products obtained.New structures suggested for the oligomeric reaction products agree with all the analytical data. The reactions between isatin and thiophene (bithiophene) are explained schematically.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1990.051780101
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  • 3
    Electronic Resource
    Electronic Resource
    Sub-Tg molecular motions in glassy poly(vinyl chloride). Influence of the nucleophilic substitution (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 871-880 
    Details
    ISSN: 0887-6266
    Keywords: modified poly(vinyl chloride) ; dielectric ; relaxation ; stretched exponential law ; coupling model ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dielectric local molecular motions in the glass transition region of poly(vinyl chloride) (PVC) have been investigated by means of the isothermal depolarization currents technique. Attention is paid to the influence of the modification of the polymer by the substitution of chlorine atoms of PVC chain by the benzenethiolate group. The results are well described by stretched exponential laws. According to the Ngai's coupling model, the coupling between moving units as well as the activation energy responsible for the motions occurring at primitive level have been calculated for each sample at each temperature. All these parameters are noticeably altered by the modification of PVC. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1994.090320510
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of some tacticity-depending local chain conformations on the behaviour of poly(vinyl chloride). Changes of glass transition temperature through stereoselective substitution in solution (1994)
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 15 (1994), S. 189-196 
    Details
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1994.030150302
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  • 5
    Electronic Resource
    Electronic Resource
    Electroanalytical determination of diazinon: Direct current and differential pulse polarography and adsorptive stripping voltammetry (1990)
    Weinheim : Wiley-Blackwell
    Electroanalysis 2 (1990), S. 567-571 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polarographic behavior of the pesticide Diazinon was investigated in water/methanol solutions. Two methods are proposed for its determination. The first involves differential pulse polarography with a detection limit of 2.65 × 10-6 M, and the second is based on adsorptive stripping voltammetry at a hanging mercury drop electrode that yields a detection limit of 4.01 × 10-9 M.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140020712
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  • 6
    Electronic Resource
    Electronic Resource
    Electrode reactions of nitroxide radicals. IX. Anodic oxidations of 4-hydroxyimino-2,2,6,6-tetramethylpiperidine-1-oxyl and 4-[(aminocarbonyl)-hydrazone]-2,2,6,6-tetramethylpiperidine-1-oxyl in water solutions (1991)
    Weinheim : Wiley-Blackwell
    Electroanalysis 3 (1991), S. 233-237 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Anodic reactions of two stable nitroxide radicals, 4-hydroxyimino-2,2,6,6-tetramethylpiperidine-1-oxyl (1) and 4-[(aminocarbonyl)-hydrazone]-2.2,6,6-tetramethylpiperidine-1-oxyl (2) were studied in aqueous solutions over the pH range 5.33-8.04 using the cyclic voltammetry technique. They show one-electron oxidation processes of reversible and quasi-reversible natures, depending on scan rate conditions at pH 5.33. The diffusion coefficients, the observed standard rate constants (ks), and the oxidation potentials for the redox reaction nitroxyl radical ⇌ oxoammonium salt have been determined. A one-electron transfer process, followed by an irreversible chemical reaction, is observed at pH ≥ 5.71, and the rates of this reaction at pH 5.71 and 6.71 are 0.11 and 0.080 s-1, respectively. Controlled-potential electrolysis at 0.8 V (vs. SCE) confirms a one-electron electrode reaction.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140030316
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  • 7
    Electronic Resource
    Electronic Resource
    EELS and low-energy electron emission of clean and oxygen-exposed tantalum (1990)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 15 (1990), S. 675-680 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The electron energy-loss spectra (EELS) associated with 4f and 5p excitations, and the secondary electron spectra (SES) have been used to study the oxidation of a clean polycrystalline tantalum surface. For the clean and oxygen-exposed surfaces, the EELS results are discussed in terms of bulk and surface plasmons as well as interband transitions to unoccupied states above the Fermi level (EF). The secondary electron spectra have been used as a fingerprint for the density of unoccupied states above EF. The changes observed in the EEL spectrum upon oxygen exposure are explained as being due to oxide formation, in agreement with previous results by XPS and AES. The features observed above the NVV and OVV Auger transitions, in both the clean and oxidized surfaces, are described as auto-ionization emission due to the decay of electrons that have been excited resonantly from the 4f and 5p levels to states well above the states well above the Fermi energy. The excitation process has been identified also in the EEL spectra.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740151107
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  • 8
    Electronic Resource
    Electronic Resource
    Structural properties of BN thin films obtained by plasma-enhanced chemical vapour deposition (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 21 (1994), S. 809-813 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: In this work BN films have been deposited by the plasma-enhanced chemical vapour deposition (PECVD) technique on p-type (100) silicon substrates, using borazine and nitrogen as precursors. X-ray photoelectron spectroscopy, infrared spectroscopy, x-ray diffraction, nuclear reaction analysis and Rutherford backscattering spectroscopy were used to analyse the films. The results of quantitative XPS analysis indicate the formation of a thin surface layer (∼3 nm) of boron oxynitride, BNO0.3, over a bulk of nearly stoichiometric boron nitride, BN1.1. The presence of the hexagonal phase mixed with amorphous boron nitride was identified. Infrared and Rutherford backscattering spectroscopies combined with a liquid etching technique were used to determine the composition and structure across the film thickness. From these measurements we infer that the composition across the film is nearly constant but with a gradual transition from an amorphous structure close to the Si/BN1.1 interface to an hexagonal structure towards the outer layers. Thermal treatments of the boron nitride films up to a temperature of ∼1000°C in a nitrogen atmosphere resulted in a small decrease of both the B/N atomic concentration ratio and the refractive index of the film. The insulating characteristics of the boron nitride for application as an intermetal dielectric were also treated. The electrical conduction results can be interpreted in terms of a Schottky mechanism, which allows us to calculate the high-frequency dielectric constant, εr = 3.2.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740211112
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  • 9
    Electronic Resource
    Electronic Resource
    AES and HRTEM study of an a-SiNx: H/W/WSix/a-SiNx: H multilayer structure realized by PEVCD (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 21 (1994), S. 823-829 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A multilayer insulator-metal-insulator capacitive structure was realized by plasma-enhanced chemical vapour deposition for a discharge frequency of 35 kHz. The chosen materials were amorphous hydrogenated silicon nitride as the insulator and tungsten as the metal. An interlayer of tungsten silicide used as an adhesion layer is deposited between W and a-SiNx:H. An AES depth profiling study coupled with high-resolution transmission electron microscopy observation showed the presence of interphases: the interfacial zone between a-SiNx:H and W is constituted by a WNx interphase ∼10 nm deep. Small crystallites are observed in tungsten-based materials. The presence of a mixed phase containing tungsten, silicon, nitrogen and a small amount of oxygen is obvious and noticed on the AES spectra at the WSix/a-SiNx:H interface: its thickness appears to be ∼7 nm.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740211202
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  • 10
    Electronic Resource
    Electronic Resource
    In-depth inhomogeneous photoluminescent properties of porous silicon layers (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 22 (1994), S. 358-362 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Chemical composition and photoluminescence of free-standing porous silicon (PS) layers produced by anodization of p-Si in aqueous HF solutions at high current densities (Ja = 50-250 mA cm-2) are studied. It is shown that the PS layers are enriched in oxide phase, presumably due to silicic acid formation during the pore growth. Chemical composition of PS films produced at current densities about 100-150 mA cm-2 is non-uniform: internal faces of PS samples contain more silicon atoms than external. Their luminescent properties are also asymmetrical: the external face of the PS layer emits less light than the internal one. The samples grown at current densities above 200 mA cm-2 do not exhibit asymmetry of chemical composition and luminescence. The obtained results are considered based on existing models for PS luminescence and it is shown that the quantum confinement and siloxene-based models may fit the present data.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740220178
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