13,647 research outputs found

    Visible-light promoted atom transfer radical addition-elimination (ATRE) reaction for the synthesis of fluoroalkylated alkenes using DMA as electron-donor

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    Here, we describe a mild, catalyst-free and operationally-simple strategy for the direct fluoroalkylation of olefins driven by the photochemical activity of an electron donor-acceptor (EDA) complex between DMA and fluoroalkyl iodides. The significant advantages of this photochemical transformation are high efficiency, excellent functional group tolerance, and synthetic simplicity, thus providing a facile route for further application in pharmaceuticals and life sciences

    (1R*,2S*)-2-Nitro-1-(4-nitro­phen­yl)propanol

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    The title compound, C9H10N2O5, presents a racemic mixture of two enanti­omeric diastereomers. In the crystal, mol­ecules assemble into zigzag chains parallel to the b axis [C(6) motif] due to the formation of elongated O—H⋯O(N) hydrogen bonds. Of inter­est is the fact that only the aliphatic nitro group is involved in hydrogen bonding and it adopts a gauche conformation with respect to the OH group

    An adaptive scheduling scheme for fair bandwidth allocation

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    Class-based service differentiation is provided in DiffServ networks. However, this differentiation will be disordered under dynamic traffic loads due to the fixed weighted scheduling. An adaptive weighted scheduling scheme is proposed in this paper to achieve fair bandwidth allocation among different service classes. In this scheme, the number of active flows and the subscribed bandwidth are estimated based on the measurement of local queue metrics, then the scheduling weights of each service class are adjusted for the per-flow fairness of excess bandwidth allocation. This adaptive scheme can be combined with any weighted scheduling algorithm. Simulation results show that, comparing with fixed weighted scheduling, it effectively improve the fairness of excess bandwidth allocation

    5-Fluoro­isophthalic acid

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    In the crystal structure of the title compound, C8H5FO4, the complete molecule is generated by crystallographic twofold symmetry with two C atoms and the F atom lying on the axis. The mol­ecule is almost planar with the carboxyl group twisted with respect to the mean plane of the benzene ring by a dihedral angle of 2.01 (1)°. In the crystal, inter­molecular O—H⋯O hydrogen bonds and C—H⋯F inter­actions connect the mol­ecules into a two-dimensional supra­molecular array

    Charge order driven by Fermi-arc instability in Bi2201

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    The understanding of the origin of superconductivity in cuprates has been hindered by the apparent diversity of intertwining electronic orders in these materials. We combined resonant x-ray scattering (REXS), scanning-tunneling microscopy (STM), and angle-resolved photoemission spectroscopy (ARPES) to observe a charge order that appears consistently in surface and bulk, and in momentum and real space within one cuprate family, Bi2201. The observed wave vectors rule out simple antinodal nesting in the single-particle limit but match well with a phenomenological model of a many-body instability of the Fermi arcs. Combined with earlier observations of electronic order in other cuprate families, these findings suggest the existence of a generic charge-ordered state in underdoped cuprates and uncover its intimate connection to the pseudogap regime.Comment: A high resolution version can be found at http://www.phas.ubc.ca/~quantmat/ARPES/PUBLICATIONS/Articles/Bi2201_CDW_REXS_STM.pdf
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