1,716 research outputs found

    Mononitration of durene

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    Reaction conditions under which the nitration of durene give predominantly, and in high yield, mononitrodurene (I), rather than dinitrodurene were found. The nitrating agent was No2+RF6-. Nitration with nitrosulfuric acid also gave mononitrodurene; however, byproducts such as 2.3.5.6-Me4C6HCH2C6H2Me3-2,4,5, were also formed. The NO2 PF6- gave an intermediate additional compound with durene. The reaction carried out with 3.6-dideuterodurene in D2O shows no isotope effect

    Assumptions that imply quantum dynamics is linear

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    A basic linearity of quantum dynamics, that density matrices are mapped linearly to density matrices, is proved very simply for a system that does not interact with anything else. It is assumed that at each time the physical quantities and states are described by the usual linear structures of quantum mechanics. Beyond that, the proof assumes only that the dynamics does not depend on anything outside the system but must allow the system to be described as part of a larger system. The basic linearity is linked with previously established results to complete a simple derivation of the linear Schrodinger equation. For this it is assumed that density matrices are mapped one-to-one onto density matrices. An alternative is to assume that pure states are mapped one-to-one onto pure states and that entropy does not decrease.Comment: 10 pages. Added references. Improved discussion of equations of motion for mean values. Expanded Introductio

    Extrakorporale Stoßwellentherapie eines komplizierten chronischen Ulcus cruris venosum

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    Zusammenfassung: Extrakorporale Stoßwellen werden definiert als eine Sequenz von akustischen Schallimpulsen, die einen charakteristisch schnellen Druckanstieg auf über 100MPa mit Abfall auf Normaldruck in wenigen Mikrosekunden aufweisen. In den 1980er-Jahren wurde die extrakorporale Stoßwellenlithotripsie (ESWL) erstmals zur Behandlung der Urolithiasis angewandt. Orthopäden setzten anschließend die extrakorporale Stoßwellentherapie (ESWT) zur Behandlung von nicht heilenden Frakturen, Tendinopathien und Osteonekrose ein. Die erste Anwendung von ESWT in der Dermatologie erfolgte zur Behandlung des chronischen Ulcus cruris. Verschiedene Studien der letzten 10Jahre zeigten, dass die ESWT die Angiogenese stimuliert und die Perfusion im ischämischen Gewebe verbessert, die Entzündungsreaktion mindert, die Zelldifferenzierung unterstützt und hiermit die Wundheilung deutlich verbessern kann. Wir setzten die ESWT erfolgreich zur Behandlung eines komplizierten chronischen venösen Ulcus cruris ein. Weiter konnten wir eine Verbesserung des lymphatischen Abflusses nach Applikation von ESWT beobachten. Die ESWT stellt somit eine nebenwirkungsarme und effiziente physikalische Therapiemodalität zur Behandlung von therapieresistenten chronischen Wunden da

    Canonical Expansion of PT-Symmetric Operators and Perturbation Theory

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    Let HH be any \PT symmetric Schr\"odinger operator of the type 2Δ+(x12+...+xd2)+igW(x1,...,xd) -\hbar^2\Delta+(x_1^2+...+x_d^2)+igW(x_1,...,x_d) on L2(Rd)L^2(\R^d), where WW is any odd homogeneous polynomial and gRg\in\R. It is proved that H\P H is self-adjoint and that its eigenvalues coincide (up to a sign) with the singular values of HH, i.e. the eigenvalues of HH\sqrt{H^\ast H}. Moreover we explicitly construct the canonical expansion of HH and determine the singular values μj\mu_j of HH through the Borel summability of their divergent perturbation theory. The singular values yield estimates of the location of the eigenvalues \l_j of HH by Weyl's inequalities.Comment: 20 page

    SEVERE OSTEOPOROSIS DUE TO SYSTEMIC MAST CELL DISEASE: SUCCESSFUL TREATMENT WITH INTERFERON ALPHA-2B

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    We describe a 33-yr-old man suffering from severe vertebral osteoporosis and urticaria pigmentosa due to systemic mast cell disease (SMCD). Because i.v. clodronate therapy could not prevent further vertebral fractures, an additional treatment with interferon alpha-2b was initiated. During 24 months of treatment, our patient had no further pain episodes, no new vertebral fractures were discovered, trabecular bone mineral density (BMD) increased significantly and urticarial symptoms improved. Nevertheless, the extent of skin lesions remained unchanged. On histological examination, a remarkable decrease of mast cells was observed in the bone marrow, but not in the skin. Five months after discontinuation of interferon alpha-2b, trabecular BMD decreased and urticarial symptoms deteriorated. These findings illustrate a beneficial effect of interferon alpha-2b on SMCD-induced osteoporosis as well as urticarial symptoms, and raise the question whether this treatment may have a diverse impact on mast cell populations in different tissue

    Zircon dissolution in a ductile shear zone, Monte Rosa granite gneiss, northern Italy

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    The sizes, distributions and shapes of zircon grains within variably deformed granite gneiss from the western Alps have been studied. Zircon shows numerous indicators of a metamorphic response in both the host gneiss and a 5 cm wide continuous ductile shear zone, within which the zircon grain sizes range from <1 µm to >50 µm. However, the very fine grain sizes are virtually absent from grain boundaries. Within this zone, zircons consistently have more rounded and embayed margins, which are interpreted as evidence of dissolution in response to fluid influx during shearing. Zircons are preferentially located near metamorphic muscovite in both the host gneiss and the shear zone and tend to show the poorest crystal shape, indicating that fluids linked to the formation and presence of muscovite may enhance both the crystallization of zircon and its subsequent dissolution. Larger zircon crystals typically show a brittle response to deformation when adjacent to phyllosilicates, with fractures consistently perpendicular to the (001) mica cleavage. The variety of metamorphic behaviour observed for zircon indicates that it may be highly reactive in sub-solidus mid-crustal metamorphic environments

    Heat kernel estimates and spectral properties of a pseudorelativistic operator with magnetic field

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    Based on the Mehler heat kernel of the Schroedinger operator for a free electron in a constant magnetic field an estimate for the kernel of E_A is derived, where E_A represents the kinetic energy of a Dirac electron within the pseudorelativistic no-pair Brown-Ravenhall model. This estimate is used to provide the bottom of the essential spectrum for the two-particle Brown-Ravenhall operator, describing the motion of the electrons in a central Coulomb field and a constant magnetic field, if the central charge is restricted to Z below or equal 86
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