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  • Chemistry  (17)
  • 13.87.Ce  (2)
  • Key wordsAegilops  (2)
  • 1
    Digitale Medien
    Digitale Medien
    The pattern of zygotene and pachytene pairing in allotetraploid Aegilops species sharing the U genome (1996)
    Springer
    Theoretical and applied genetics 93 (1996), S. 1152-1155 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key wordsAegilops ; Allotetraploid ; Diploidization ; Pairing control ; Synaptonemal complex
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Allotetraploid Aegilops species sharing the U genome, Ae. columnaris (UUMM), Ae. ovata (UUMM), Ae. triaristata (UUMM), Ae. triuncialis (UUCC) and Ae. variabilis (UUSS), regularly form bivalents at metaphase I of meiosis. The pattern of zygotene and pachytene pairing was analyzed by whole-mount surface-spreading of synaptonemal complexes under the electron microscope. The data indicated that at the zygotene stage the chromosomes were almost exclusively associated as bivalents; only a few multivalents (7%) were observed. These observations are discussed in relation to mechanisms of diploidization of polyploid meiosis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050349
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  • 2
    Digitale Medien
    Digitale Medien
    The pattern of zygotene and pachytene pairing in allotetraploid Aegilops species sharing the D genome (1996)
    Springer
    Theoretical and applied genetics 93 (1996), S. 1175-1179 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key wordsAegilops ; Allotetraploid ; Diploidization ; Pairing control ; Synaptonemal complex
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Chromosome pairing behaviour of the allotetraploid Aegilops species sharing the D genome, Ae. crassa (DDMM), Ae. cylindrica (DDCC) and Ae. ventricosa (DDNN), was analyzed by electron microscopy in surface-spread prophase-I nuclei. Synaptonemal-complex analysis at zygotene and pachytene revealed that synapsis in the allotetraploids was mostly between homologous chromosomes, although a few multivalents were also formed. Only homologous bivalents were observed at metaphase-I. It is concluded that the mechanism controlling bivalent formation in these species acts mainly at zygotene by restricting pairing to homologous chromosomes, but also acts at pachytene by preventing chiasma formation in homoeologous associations. These observations are discussed in relation to mechanisms of diploidization of polyploid meiosis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050353
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  • 3
    Digitale Medien
    Digitale Medien
    Correlations between D and $${\overline D}$$ mesons produced in 500 GeV/cπ−-nucleon interactions (1999)
    Springer
    EPJ direct 1 (1999), S. 1-67 
    Details
    ISSN: 1435-3725
    Schlagwort(e): 12.38.-t ; 13.85.-t ; 13.87.Ce ; 13.87.Fh
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We present a study of correlations between D and $${\overline D}$$ mesons produced in 500 GeV/cπ−-nucleon interactions, based on data from experiment E791 at Fermilab. We have fully reconstructed 791 ± 44 charm meson pairs to study correlations between the transverse and longitudinal momenta of the two D mesons and the relative production rates for different types of D meson pairs. We see slight correlations between the longitudinal momenta of the D and the $${\bar D}$$ , and significant correlations between the azimuthal angle of the D and the $${\bar D}$$ . The experimental distributions are compared to a next-to-leading-order QCD calculation and to predictions of the PYTHIA/JETSET Monte Carlo event generator. We observe less correlation between transverse momenta and different correlations between longitudinal momenta than these models predict for the default values of the model parameters. Better agreement between data and theory might be achieved by tuning the model parameters or by adding higher order perturbative terms, thus contributing to a better understanding of charm production. The relative production rates for the four sets of charm pairs, $$D^0{{\overline D}^0}, D^0 D^{-}, D^+{{\overline D}^0}, D^+ D^{-}$$ as calculated in the PYTHIA/JETSET event generator with the default parameters, agree with data as far as the relative ordering, but predict too many $$D^+ {{\overline D}^0}$$ pairs and too few $$D^+ D^{-}$$ pairs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s101059900c0004
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  • 4
    Digitale Medien
    Digitale Medien
    Correlations between D and $${\overline D}$$ mesons produced in 500 GeV/cπ−-nucleon interactions (2000)
    Springer
    EPJ direct 1 (2000), S. 1-67 
    Details
    ISSN: 1435-3725
    Schlagwort(e): 12.38.-t ; 13.85.-t ; 13.87.Ce ; 13.87.Fh
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We present a study of correlations between D and $${\overline D}$$ mesons produced in 500 GeV/cπ−-nucleon interactions, based on data from experiment E791 at Fermilab. We have fully reconstructed 791 ± 44 charm meson pairs to study correlations between the transverse and longitudinal momenta of the two D mesons and the relative production rates for different types of D meson pairs. We see slight correlations between the longitudinal momenta of the D and the $${\bar D}$$ , and significant correlations between the azimuthal angle of the D and the $${\bar D}$$ . The experimental distributions are compared to a next-to-leading-order QCD calculation and to predictions of the PYTHIA/JETSET Monte Carlo event generator. We observe less correlation between transverse momenta and different correlations between longitudinal momenta than these models predict for the default values of the model parameters. Better agreement between data and theory might be achieved by tuning the model parameters or by adding higher order perturbative terms, thus contributing to a better understanding of charm production. The relative production rates for the four sets of charm pairs, $$D^0{{\overline D}^0}, D^0 D^{-}, D^+{{\overline D}^0}, D^+ D^{-}$$ as calculated in the PYTHIA/JETSET event generator with the default parameters, agree with data as far as the relative ordering, but predict too many $$D^+ {{\overline D}^0}$$ pairs and too few $$D^+ D^{-}$$ pairs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s101059900c0004
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  • 5
    Digitale Medien
    Digitale Medien
    Growth modes of solution-grown CdS thin films (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 5 (1995), S. 11-17 
    Details
    ISSN: 1057-9257
    Schlagwort(e): CdS ; chemical deposition ; complexing agent ; sulfurising agent ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: The growth modes of CdS thin films on glass in a chemical bath were analysed using scanning electron microscopy and optical microscopy. The results of these studies show that the film growth occurs by ion-by-ion condensation and by colloidal particles of CdS adhering to the substrate. Both mechanisms are operative from the initial stages of film growth. The predominance of one or other of these two growth modes depends on the abundance of Cd and S ions present in the solution, which is determined by the amount of complexing and sulphurising agents and ammonia used for the controlled release of Cd and S ions into the solution. The growth mode influences the optical properties of the films.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/amo.860050104
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  • 6
    Digitale Medien
    Digitale Medien
    Optimisation of the electrochemical bath for growing device-quality CuInSe2 thin films (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 8 (1998), S. 1-8 
    Details
    ISSN: 1057-9257
    Schlagwort(e): electrodeposition ; copper-indium-selenide ; thin films ; layer-by-layer deposition ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: The electrochemical bath used for growing device-quality CIS (CuInSe2) thin films by co-deposition as well as layer-by-layer (LBL) deposition was characterised and optimised with respect to the film properties. The bath composition was varied by changing the Cu, In and Se ion concentrations in specific ratios in both co-deposition and LBL deposition. The film properties were analysed using techniques such as SEM (scanning electron microscopy), EPMA (electron probe microanalysis), AES (Auger electron spectroscopy) and XRD (X-ray diffraction). The structural, morphological and compositional properties of the films were characterised and their variation is attributed to the bath composition and growth conditions. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Modification des polyméres de vinyl-4 benzophénones méthoxylées et copolymérisation des monomères avec le styréne (1973)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 168 (1973), S. 19-26 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Methoxylierte 4-vinylbenzophenone wurden radikalisch mit Styrol in benzolischer Lösung copolymerisiert. Die Zusammensetzung der Produkte konnte mittels 1H-NMR-Spektren bestimmt werden. Die Copolymerisationsparameter für die radikalische Copolymerisation wurden berechnet; hierbei zeigten die methoxylierten p-Vinylbenzophenone eine größere Reaktivität als Styrol. Diese 4-Vinylbenzophenonhomo- und -copolymeren haben keine schützende Wirkung gegen UV-Bestrahlung. Die hierfür notwendige Bedingung ist das Vorhandensein einer Hydroxylgruppe in ortho-Stellung zur Carbonylgruppe. Deshalb untersuchten wir die partielle Entmethylierung der 4-Vinyl-2′-methoxy-benzophenonpolymeren. Ihre saure Behandlung gab 2′-Hydroxyderivate. Das UV-Spektrum des erhaltenen Poly(4-vinyl-2′-hydroxy-4′-methoxybenzophenons) zeigt eine schützende Wirkung gegen natürliches Tageslicht an.
    Notizen: Les monomères cités ont été copolymérisés radicalairement dans le benzene avec le styrène. La composition des copolymères a été déterminée à partir de leurs spectres NMR. Les constantes r1 et r2 été détérminée d calculdes; dans ce cas, les p-vinylbenzopédnones méthoxy-lées ont une plus grande réactivité que le styrene. Les homo et copolymkres de ces p-vinyl-benzophdnones n'ont aucun effet protecteur contre le rayonnement UV. La condition nécessaire pour obtenir cet effet est la pédsence d'un groupement hydroxyle en position ortho par rapport au groupement carbonyle. La déméthylation partielle des polyméres des vinyl-4 méthoxy-2′ benzophénones a été étudiée dans ce but. Cette réaction a permis d'obtenir en particulier la poly(viny1-4 hydroxy-2′ mdthoxy-4′ benzophenone) dont le spectre UV indique un effet protecteur contre la lurnière naturelle.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1973.021680103
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  • 8
    Digitale Medien
    Digitale Medien
    Recherche de polymères «Absorbeurs UV». Synthèse et polymérisation de nouveaux monomères du type vinyl-4 benzophénone méthoxylée (1973)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 167 (1973), S. 147-154 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Es wurden methoxylierte p-Vinylbenzophenone dargestellt, indem man die aus p-Chlorstyrol bereitete magnesiumorganische Verbindung mit methoxylierten Benzaldehyden reagieren ließ und die dabei erhaltenen p-Vinylbenzhydrole oxidierte. Die Monomeren ließen sich radikalisch in Lösung polymerisieren Dabei entstanden Polymere hohen Mol.-Gew., die in einer späteren Arbeit teilweise entmethyliert und deren Absorptionseigenschaften im UV-Gebiet eingehend untersucht werden sollen.
    Notizen: Les p-vinyl benzophénones méthoxylées ont été synthétisées par action du chlorure de p-vinyl phényl magnésium sur les benzaldéhydes méthoxylés suivie de l'oxydation des p-vinyl benzhydrols obtenus. Les monoméres ont été polymérisés par procédure radicalaire en solution. Cette réaction conduit, dans le cas de la benzophénone diméthoxylée, à des polyméres de grandes masses. Ces polymères seront partiellement déméthoxylés dans un prochain travail afin de faire apparaître les propriétés d'absorbeurs UV.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1973.021670109
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  • 9
    Digitale Medien
    Digitale Medien
    Synthesis and properties of epoxy-episulfide resins (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 67-81 
    Details
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Standard epoxy resins have good mechanical properties, but their prolonged low temperature curing time limits their potential use in clinical applications as well as in many industrial applications. A fast-curing epoxy-episulfide resin has been developed. The gel time of epoxy-episulfide made from EPONTrade mark of Shell Chemical Company. 828 ranges from 2 to 10 minutes by changing the ratio of the ingredients. The heat of reaction of this system is low, resulting in low cure shrinkage. Water absorption of the episulfide network is low. The epoxy-episulfide system cured with polyamide curing agent V-40 exhibits two transition temperatures, at about 85°C and 130°C, as shown in dynamic mechanical analysis data. In order to solve the long term stability problem of the above episulfides, and also the mixing problem, a lower viscosity resin, Eponex, was used to make Eponex-sulfide. Eponex-sulfide systems show promise in that they remain in a stable liquid form without epoxy. The other advantages appear to be retained.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/apmc.1996.052400106
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  • 10
    Digitale Medien
    Digitale Medien
    XPS and ISS study of NiTiO3 and PbTiO3 subjected to low-energy ion bombardment. I. Influence of the type of ion (Ar+ and O2+) (1993)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 20 (1993), S. 941-948 
    Details
    ISSN: 0142-2421
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Compositional and chemical changes in PbTiO3 and NiTiO3 induced by 3.5 keV Ar+ and O2+ ion bombardment have been studied quantitatively by XPS and ISS. Whereas in NiTiO3 the Ti/Ni ratio determined by XPS remained practically constant, a preferential loss of lead was observed in PbTiO3 during ion bombardment. In that case, Ar+ removed lead more effectively than O2+ ions. Argon ion bombardment induced strong chemical changes in both titanates: Ni2+ and Pb2+ species were nearly totally reduced to the metallic state, while Ti4+ species were partially reduced to Ti3+ and Ti2+ oxidation states. This reduction is more efficient in PbTiO3 than in NiTiO3. The preferential loss of lead in PbTiO3 and the removal at equivalent rates of Ti and Ni in NiTiO3 are discussed within the context of the chemical stability and physical constants of the compounds by assuming a chemically guided lattice relaxation of the bombarded targets. The possibility that solid-state reactions play a role in the control of some of the results is stressed. Other possible effects, such as agglomeration or surface enrichment, are discussed by using the ISS results.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/sia.740201203
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