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  • 1
    Electronic Resource
    Electronic Resource
    Thermal decomposition of mechanically activated sphalerite
    Amsterdam : Elsevier
    Thermochimica Acta 180 (1991), S. 117-123 
    Details
    ISSN: 0040-6031
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0040-6031(91)80380-2
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  • 2
    Electronic Resource
    Electronic Resource
    Surface and bulk properties of mechanically activated zinc sulphide (1992)
    Springer
    Journal of materials science 27 (1992), S. 653-657 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract BET, scanning electron microscopy, X-ray photoelectron, infrared, X-ray diffraction and Mössbauer spectroscopy methods were used to identify changes in surface, structural and spectroscopic properties of sphalerite produced by mechanical activation. Activated samples exhibit amorphization of crystallographic structure of the mineral, as well as of hyperfine structure of the accessory manganese. The presence of a new magnetic phase was disclosed in the samples activated for longer periods of time. Changes in structure are accompanied by mechanochemical oxidation of the surface layer of sphalerite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02403874
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  • 3
    Electronic Resource
    Electronic Resource
    Surface and bulk properties of mechanically activated zinc sulphide (1992)
    Springer
    Journal of materials science 27 (1992), S. 653-657 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract BET, scanning electron microscopy, X-ray photoelectron, infrared, X-ray diffraction and Mössbauer spectroscopy methods were used to identify changes in surface, structural and spectroscopic properties of sphalerite produced by mechanical activation. Activated samples exhibit amorphization of crystallographic structure of the mineral, as well as of hyperfine structure of the accessory manganese. The presence of a new magnetic phase was disclosed in the samples activated for longer periods of time. Changes in structure are accompanied by mechanochemical oxidation of the surface layer of sphalerite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00554031
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  • 4
    Electronic Resource
    Electronic Resource
    Trisomy associated with loss of maturation capacity in a long-term embryogenic culture of Abies alba (1997)
    Springer
    Theoretical and applied genetics 95 (1997), S. 353-358 
    Details
    ISSN: 1432-2242
    Keywords: Key words Abies alba ; Organic nitrogen ; Somatic embryogenesis ; Somaclonal variation ; Trisomic karyotype
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Karyological studies were made on a 6-year-old embryogenic cell line of Abies alba. Embryogenic cells were obtained from a mature zygotic embryo cultivated on modified MCM-medium and subcultured every 3 weeks. Three years after induction, part of the cell line was transferred to media supplemented with 500 or 1000 mg l-1 caseine hydrolysate and 500 mg l-1 L-glutamine. Approximately 3 years after addition of the organic nitrogen to the medium, morphological changes such as malformation of the suspensor cells and a loss of maturation capacity occurred. Chromosome counts revealed that all cells cultivated on medium with organic nitrogen were trisomic. Fluorescent-banding methods and comparison with an euploid cell line showed that the additional chromosome belonged to the group of long, metacentric chromosomes of Abies alba without secondary constriction. Those cells cultured on medium not supplemented with caseine hydrolysate and L-glutamine retained a stable chromosome number of 2n=24. Both normal and deformed suspensor cells were observed. The maturation frequency was very low. The emergence of aneuploidy within one cell line could be the consequence of high selection pressure caused by the different culture conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050570
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  • 5
    Electronic Resource
    Electronic Resource
    Origin of facultative heterochromatin in the endosperm ofGagea lutea (Liliaceae) (2000)
    Springer
    Protoplasma 212 (2000), S. 217-226 
    Details
    ISSN: 1615-6102
    Keywords: DNA content ; Embryo sac development ; Endosperm ; Facultative heterochromatin ; Fertilization ; Gagea lutea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Facultative heterochromatin occurs not only in certain animals in connection with sex determination but also in members of at least one plant genus,Gagea (Liliaceae s. str.), but here in the course of embryo sac development, fertilization, and endosperm formation. The present contribution intends to provide undebatable photographic and cytometric evidence, previously not available, for the events in the course of which three whole genomes in the pentaploid endosperm nuclei ofGagea lutea become heterochroma-tinized. In this plant, embryo sac formation usually follows the Fritillaria type, i.e., the embryo sac is tetrasporic, and a “1 + 3 position” of the spore nuclei is followed by a mitosis in which the three chalazal spindles fuse and two triploid nuclei are formed. A triploid chalazal polar nucleus is derived from one of these, which contributes to the pentaploid endosperm. These nuclei in the chalazal part of the embryo sac show stronger condensation compared with the micropylar ones. The pycnosis of the triploid polar nucleus is maintained and even enhanced during endosperm proliferation, while the micropylar polar nucleus and the sperm nucleus maintain their euchromatic condition. The origin of the heterochromatic masses in the endosperm nuclei from the three chalazal genomes of the central cell is unambiguously evident from the distribution of heterochromatic chromosomes in the first endosperm mitosis and the following interphase. DNA content measurements confirm a 3 ∶ 2 relationship of heterochromatic and euchromatic chromosome sets, which is usually maintained up to the cellularized endosperm. Pycnotic nuclei in the chalazal part of megagametophytes are characteristic of several embryo sac types, but only forGagea spp. it is documented that such nuclei can take part in fertilization and endosperm formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01282922
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  • 6
    Electronic Resource
    Electronic Resource
    Book reviews (1967)
    Springer
    Atomic energy 23 (1967), S. 777-787 
    Details
    ISSN: 1573-8205
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01565743
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  • 7
    Electronic Resource
    Electronic Resource
    Ein Beitrag zur Aufklärung irreversibler Desaktivierungsreaktionen in organischen Photoleitern vom Typ der Epoxid-Arylamin-Additionspolymere (1987)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 38 (1987), S. 340-347 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Light induced aging of the investigated photoconductors is studied by UV-VIS and EPR spectrometry. The reasons for the deterioration of the electrophotographic properties are discussed. It is supposed, that the holes generated by exposure are radical cations, which are able of R-abstraction and recombination with other free radicals.
    Notes: Die lichtinduzierten Alt erungsreaktionen der genannten Photoleiter werden durch UV-VIS- und EPR-Spektrometrie untersucht und die Ursachen für die Verschlechterung der elektrophotographischen Eigenschaften diskutiert. Es wird angenommen, daß die photogenerierten Defektelektronen sich chemisch wie Radikalkationen verhalten und zur R-Abstraktion sowie zur Rekombination mit anderen freien Radikalen befähigt sind.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1987.010380608
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  • 8
    Electronic Resource
    Electronic Resource
    Untersuchungen zum Einfluß einer Oberflächenmodifizierung von Fasermaterialien im nichtthermischen Plasma einer Hochfrequenz-Entladung auf die Adhäsionsfestigkeit zu Epoxidharz. Teil II. Veränderungen der Struktur von Glasfasern nach PlasmabehandlungTeil I: siehe [1] (1981)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 32 (1981), S. 36-40 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Fibres of boron-silicate-glass are destructed at the surface by ion bombardment from plasma of a radio-frequency glow discharge. The alkaline elements are sputtered away, but partly readsorbed as hydroxides. The strength of fibres decreases strongly on shorttime of plasma exposition. In a plasma of ammonia N-containing groups are formed on the surface of fibres.
    Notes: Borsilicatglasfasern werden durch den Beschuß mit Ionen aus dem Plasma einer Hochfrequenz-Glimmentladung oberflächlich umstrukturiert. Die Alkalielemente werden bevorzugt herausgesputtert und z. T. in Hydroxidform wieder abgelagert. Die Fasern verlieren auch nach nur kurzer Plasmabehandlungszeit stark an Eigenfestigkeit. Bei Behandlung im NH3-Plasma bilden sich an der Faseroberfläche N-haltige funktionelle Gruppen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1981.010320109
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  • 9
    Electronic Resource
    Electronic Resource
    Strukturuntersuchungen an Cr2O3-Mischoxidkatalysatoren. IV. Zum System MgO—Cr2O3Professor Günther Rienäcker zum 65. Geburtstage am 13. Mai 1969 gewidmet (1969)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 366 (1969), S. 240-248 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The phase composition of MgO/Cr2O3 mixed oxides prepared at various temperatures was investigated by chemical analysis, X-ray, IR-spectroscopic, and ESR measurements. The order of spinel phase increases with increasing temperature of preparation. No intermediate disordered structure was observed.
    Notes: Die Phasenzusammensetzung von MgO/Cr2O3-Mischoxiden, die bei verschiedenen Temperaturen hergestellt worden sind, wird durch chemische Analyse, röntgenographische, IR-spektroskopische und ESR-Messungen ermittelt. Die Ordnung innerhalb der sich bildenden Spinellphase wächst mit zunehmender Herstellungstemperatur. Ungeordnete Übergangsphasen wurden nicht beobachtet.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19693660315
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  • 10
    Electronic Resource
    Electronic Resource
    Untersuchungen des Einflusses von reinen, dotierten und gemischten Oxidkatalysatoren auf die Sauerstoffrekombination mit Hilfe der ESRProfessor Günther Rienäcker zum 70. Geburtstage am 13. Mai 1974 gewidmet (1974)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 405 (1974), S. 257-266 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Effect of Pure, Doped, and Mixed Oxides on the Recombination of Atomic Oxygen, Investigated by ESRThe recombination of oxygen atoms on the surface of oxides was determined by ESR. The resonance hypothesis of heterogeneous catalysis is valid for Li2O and Ga2O3 doped ZnO and for transition metal oxides. The most active catalysts are those with an activation energy of electrical conductivity of 1eV. This value is equal to the energy of the rate determining step O2(1Δg) → O2(3Σg-).The results obtained on the alkaline earth oxides and on mixed chromium oxides cannot be explained by the resonance hypothesis, because they exhibit ionic conductivity or react with the oxygen.
    Notes: Bei der Sauerstoffrekombination an Oxidkatalysatoren wurde die ESR als Nachweismethode für den atomaren Sauerstoff benutzt. Die Resonanzhypothese für heterogene Katalyse an Halbleitern wird durch Messungen an mit Ga2O3 und Li2O dotiertem ZnO und an reinen Oxiden der Übergangsmetalle gestützt. In beiden Versuchsreihen sind diejenigen Katalysatoren am aktivsten, deren Aktivierungsenergien der Leitfähigkeit Eσ ungefähr 1eV betragen. Dieser Wert von Eσ ist ungefähr gleich der Energie von 0,98 eV des geschwindigkeitsbestimmenden Teilschrittes O2(1Δg) → O2(3Σg-) der Oberflächenrekombination (2).Die Meßergebnisse an reinen Oxiden der Erdalkalimetalle und an Cr2O3-Mischoxidkatalysatoren können mit der Resonanzhypothese nicht interpretiert werden, da entweder Reaktion mit atomarem Sauerstoff oder Ionenleitung auftritt.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19744050306
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