2,691 research outputs found
Relativistic description of J/\psi dissociation in hot matter
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 and 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
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
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 LiVO single crystals grown using a self-flux technique
Magnetically pure spinel compound is a rare -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 ( 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 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 C\@. A very
high specific heat coefficient = 450 mJ/(mol K\@) was obtained
at a temperature of 1.8 K for a crystal containing a magnetic defect
concentration = 0.5 mol%. A crystal with = 0.01 mol% showed a residual resistivity ratio of 50.Comment: 6 pages, 7 figures, Title modifie
Relaxation of Spin Polarized He in Mixtures of He and He Below the He Lambda Point
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
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)
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 QED
Dynamical chiral symmetry breaking (DCSB) in QED 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 QED 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 QED. It is found
that the gauge boson mass 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 increases. In
particular, chiral symmetry gets restored when 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
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 1–3 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
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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