2,691 research outputs found

    Relativistic description of J/\psi dissociation in hot matter

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    The mass spectra and binding radii of heavy quark bound states are studied on the basis of the reduced Bethe-Salpeter equation. The critical values of screening masses for ccˉc\bar{c} and bbˉb\bar{b} bound states at a finite temperature are obtained and compared with the previous results given by non-relativistic models.Comment: 13 latex pages, 2 figure

    The Tensor Current Divergence Equation in U(1) Gauge Theories is Free of Anomalies

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    The possible anomaly of the tensor current divergence equation in U(1) gauge theories is calculated by means of perturbative method. It is found that the tensor current divergence equation is free of anomalies.Comment: Revtex4, 7 pages, 2 figure

    Dynamics of Magnetic Defects in Heavy Fermion LiV2O4 from Stretched Exponential 7Li NMR Relaxation

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    7Li NMR measurements on LiV2O4 from 0.5 to 4.2 K are reported. A small concentration of magnetic defects within the structure drastically changes the 7Li nuclear magnetization relaxation versus time from a pure exponential as in pure LiV2O4 to a stretched exponential, indicating glassy behavior of the magnetic defects. The stretched exponential function is described as arising from a distribution of 7Li nuclear spin-lattice relaxation rates and we present a model for the distribution in terms of the dynamics of the magnetic defects. Our results explain the origin of recent puzzling 7Li NMR literature data on LiV2O4 and our model is likely applicable to other glassy systems.Comment: Four typeset pages including four figure

    Crystallography, magnetic susceptibility, heat capacity, and electrical resistivity of heavy fermion LiV2_2O4_4 single crystals grown using a self-flux technique

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    Magnetically pure spinel compound LiV2O4{\rm LiV_2O_4} is a rare dd-electron heavy fermion. Measurements on single crystals are needed to clarify the mechanism for the heavy fermion behavior in the pure material. In addition, it is known that small concentrations (<1< 1 mol%) of magnetic defects in the structure strongly affect the properties, and measurements on single crystals containing magnetic defects would help to understand the latter behaviors. Herein, we report flux growth of LiV2O4{\rm LiV_2O_4} and preliminary measurements to help resolve these questions. The magnetic susceptibility of some as-grown crystals show a Curie-like upturn at low temperatures, showing the presence of magnetic defects within the spinel structure. The magnetic defects could be removed in some of the crystals by annealing them at 700 ∘^\circC\@. A very high specific heat coefficient γ\gamma = 450 mJ/(mol K2{^2}\@) was obtained at a temperature of 1.8 K for a crystal containing a magnetic defect concentration nndefect{\rm_{defect}} = 0.5 mol%. A crystal with nndefect{\rm _{defect}} = 0.01 mol% showed a residual resistivity ratio of 50.Comment: 6 pages, 7 figures, Title modifie

    Relaxation of Spin Polarized 3^3He in Mixtures of 3^3He and 4^4He Below the 4^4He Lambda Point

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    We report the first study of the depolarization behavior of spin polarized 3He in a mixture of 3He-4He at a temperature below the 4He Lambda point in a deuterated TetraPhenyl Butadiene-doped deuterated PolyStyrene (dTPB-dPS) coated acrylic cell. In our experiment the measured 3He relaxation time is due to the convolution of the 3He longitudinal relaxation time, T1, and the diffusion time constant of 3He in superfluid 4He since depolarization takes place on the walls. We have obtained a 3He relaxation time ~3000 seconds at a temperature around 1.9K. We have shown that it's possible to achieve values of wall depolarization probability on the order of (1-2)x10^-7 for polarized 3He in the superfluid 4He from a dTPB-dPS coated acrylic surface.Comment: The Model used to interpret the data has been change

    Calculation of the Chiral Lagrangian Coefficients

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    We present a systematic way to combine the global color model and the instanton liquid model to calculate the chiral Lagrangian coefficients. Our numerical results are in agreement well with the experimental values.Comment: 7 pages, To appear in Chin.Phys.Lett, Year 200

    Formulation and characterization of biocompatible and stable I.V. itraconazole nanosuspensions stabilized by a new stabilizer polyethylene glycol-poly(β-Benzyl-L-aspartate) (PEG-PBLA)

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    Abstract Amphiphilic block copolymers, PEG-PBLA with different molecular weights, were synthesized and used as new stabilizers for Itraconazole nannosuspensions (ITZ-PBLA-Nanos). ITZ-PBLA-Nanos were prepared by the microprecipitation-high pressure homogenization method, and the particle size and zeta potential were measured using a ZetaSizer Nano-ZS90. Morphology and crystallinity were studied using TEM, DSC and powder X-ray. The effect of the PEG-to-PBLA ratio, and the drug-to-stabilizer ratio were investigated to obtain the optimal formulation. It was found that the optimal length of hydrophobic block was 25 BLA-NCA molecules and the optimal ratio of drug/stabilizer was 1:1, where the resulted average particle size of ITZ-PBLA-Nanos was 262.1 ± 7.13 nm with a PDI value of 0.163 ± 0.011. The images of TEM suggest that ITZ-PBLA-Nanos were rectangular in shape. ITZ existed as crystals in the nanoparticles as suggested by the DSC and XRD results. Compared with the crude drug suspensions, the dissolution rate of ITZ nanocrystals, was significantly increased and was similar to Sporanox® injection. The ITZ-PBLA-Nanos also demonstrated better dilution stability and storage stability compared with ITZ-F68-Nanos. The particle size of ITZ-PBLA-Nanos did not change significantly after incubated in rat plasma for 24 h which is a good attribute for I.V. administration. Acute toxicity tests showed that ITZ-PBLA-Nanos has the highest LD50 compared with ITZ-F68-Nanos and Sporanox® injection. ITZ-PBLA-Nanos also showed stronger inhibiting effect on the growth of Candida albicans compared with Sporanox® injection. Therefore, PEG-PBLA has a promising potential as a biocompatible stabilizer for ITZ nanosuspensions and potentially for other nanosuspensions as well

    Effect of gauge boson mass on the phase structure of QED3_{3}

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    Dynamical chiral symmetry breaking (DCSB) in QED3_{3} with finite gauge boson mass is studied in the framework of the rainbow approximation of Dyson-Schwinger equations. By adopting a simple gauge boson propagator ansatz at finite temperature, we first numerically solve the Dyson-Schwinger equation for the fermion self-energy to determine the chiral phase diagram of QED3_3 with finite gauge boson mass at finite chemical potential and finite temperature, then we study the effect of the finite gauge mass on the phase diagram of QED3_3. It is found that the gauge boson mass mam_{a} suppresses the occurrence of DCSB. The area of the region in the chiral phase diagram corresponding to DCSB phase decreases as the gauge boson mass mam_{a} increases. In particular, chiral symmetry gets restored when mam_{a} is above a certain critical value. In this paper, we use DCSB to describe the antiferromagnetic order and use the gauge boson mass to describe the superconducting order. Our results give qualitatively a physical picture on the competition and coexistence between antiferromagnetic order and superconducting orders in high temperature cuprate superconductors.Comment: 10 pages, 2 figure

    Energetic ion injection and formation of the storm-time symmetric ring current

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    An extensive study of ring current injection and intensification of the storm-time ring current is conducted with three-dimensional (3-D) test particle trajectory calculations (TPTCs). The TPTCs reveal more accurately the process of ring current injection, with the main results being the following: (1) an intense convection electric field can effectively energize and inject plasma sheet particles into the ring current region within 1&amp;ndash;3 h. (2) Injected ions often follow chaotic trajectories in non-adiabatic regions, which may have implications in storm and ring current physics. (3) The shielding electric field, which arises as a consequence of enhanced convection and co-exists with the injection and convection electric field, may cause the original open trajectories of injected ions with higher energy to change into closed ones, thus playing a role in the formation of the symmetric ring current

    Interface Engineering of Biomass-Derived Carbon used as Ultrahigh-Energy-Density and Practical Mass-Loading Supercapacitor Electrodes

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    The development of flexible electrodes with high mass loading and efficient electron/ion transport is of great significance but still remains the challenge of innovating suitable electrode structures for high energy density application. Herein, for the first time, lignosulfonate-derived N/S-co-doped graphene-like carbon is in situ formed within an interface engineered cellulose textile through a sacrificial template method. Both experimental and theoretical calculations disclose that the formed pomegranate-like structure with continuous conductive pathways and porous characteristics allows sufficient ion/electron transport throughout the entire structures. As a result, the obtained flexible electrode delivers a remarkable integrated capacitance of 6534 mF cm−2 (335.1 F g−1) and a superior stability at an industrially applicable mass loading of 19.5 mg cm−2. A pseudocapacitive cathode with ultrahigh capacitance of 7000 mF cm−2 can also be obtained based on the same electrode structure engineering. The as-assembled asymmetric supercapacitor achieves a high areal capacitance of 3625 mF cm−2, and a maximum energy density of 1.06 mWh cm−2, outperforms most of other reported high-loading supercapacitors. This synthesis method and structural engineering strategy can provide materials design concepts and a wide range of applications in the fields of energy storage beyond supercapacitors
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