1,602 research outputs found

    4,4′,6,6′-Tetra­bromo-2,2′-(2,8-diazonia-5-azanona-1,8-diene-1,9-diyl)diphenolate

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    In the zwitterionic title compound, C18H17Br4N3O2, the two salicylaldimine groups form a dihedral angle of 51.94 (2)° and the dihedral angle between the aromatic ring planes is 51.14 (2)°. One of the C atoms adjacent to the aza N atom is disordered over two positions; the site-occupancy factors are 0.51 (1) and 0.49 (1). There are two strong intra­molecular N—H⋯O hydrogen bonds in the mol­ecule

    Exploring Anisotropic Lorentz Invariance Violation from the Spectral-Lag Transitions of Gamma-Ray Bursts

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    The observed spectral lags of gamma-ray bursts (GRBs) have been widely used to explore possible violations of Lorentz invariance. However, these studies were generally performed by concentrating on the rough time lag of a single highest-energy photon and ignoring the intrinsic time lag at the source. A new way to test nonbirefringent Lorentz-violating effects has been proposed by analyzing the multi-photon spectral-lag behavior of a GRB that displays a positive-to-negative transition. This method gives both a plausible description of the intrinsic energy-dependent time lag and comparatively robust constraints on Lorentz-violating effects. In this work, we conduct a systematic search for Lorentz-violating photon dispersion from the spectral-lag transition features of 32 GRBs. By fitting the spectral-lag data of these 32 GRBs, we place constraints on a variety of isotropic and anisotropic Lorentz-violating coefficients with mass dimension d=6d=6 and 88. While our dispersion constraints are not competitive with existing bounds, they have the promise to complement the full coefficient space.Comment: 17 pages, 2 figures, 2 tables. Published by Universe. Constribution to the Special Issue "Advances in Astrophysics and Cosmology-in Memory of Prof. Tan Lu

    High-Entropy Alloys

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    Surgical management of 142 cases of split cord malformations associated with osseous divide

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    Objectives To investigate the key surgical points in treating split cord malformations associated with osseous divide and scoliosis (SCM-OD-S). Materials and methods The surgical options and methods of a total of 142 SCM-OD-S cases were retrospectively analyzed, and the surgical precautions and imaging diagnosis were also discussed. Results The 142 patients were performed osseous divide resection plus dural sac molding, which achieved good results and no serious complication such as spinal cord and nerve injury occurred; certain symptoms such as urination-defecation disorders, muscle strength subsidence, Pes Cavus, and toe movement disorder in partial patients achieved various degrees of relief, and it also created good conditions for next-step treatment against scoliosis. Conclusions The diagnosis of SCM-OD mainly depended on imaging inspection, routine magnetic resonance imaging (MRI) combined with computed tomography (CT) 3D reconstruction, which can comprehensively evaluate the types and features of diastematomyelia as well as other concomitant diseases. SCM alone needed no treatment, but surgery will be the only means of treating SCM-OD. Intraoperatively removing osseous divide step-by-step, as well as carefully freeing the spinal cord and remodeling the dural sac, can lay good foundations for relieving tethered cord, improving neurological symptoms, and further scoliosis orthomorphia, thus particularly exhibiting importance for the growth and development of adolescents
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