43 research outputs found
Properties of nuclear matter from macroscopic-microscopic mass formulas
Based on the standard Skyrme energy density functionals together with the
extended Thomas-Fermi approach, the properties of symmetric and asymmetric
nuclear matter represented in two macroscopic-microscopic mass formulas:
Lublin-Strasbourg nuclear drop energy (LSD) formula and Weizs\"acker-Skyrme
(WS*) formula, are extracted through matching the energy per particle of finite
nuclei. For LSD and WS*, the obtained incompressibility coefficients of
symmetric nuclear matter are MeV and MeV,
respectively. The slope parameter of symmetry energy at saturation density is
MeV for LSD and MeV for WS*, respectively, which
is compatible with the liquid-drop analysis of Lattimer and Lim [ApJ.
\textbf{771}, 51 (2013)]. The density dependence of the mean-field isoscalar
and isovector effective mass, and the neutron-proton effective masses splitting
for neutron matter are simultaneously investigated. The results are generally
consistent with those from the Skyrme Hartree-Fock-Bogoliubov calculations and
nucleon optical potentials, and the standard deviations are large and increase
rapidly with density. A better constraint for the effective mass is helpful to
reduce uncertainties of the depth of the mean-field potential.Comment: 5 figures, to appear in Phys. Lett.
Further Development of the Improved QMD Model and its Applications to Fusion Reaction near Barrier
The Improved Quantum Molecular Dynamics model is further developed by
introducing new parameters in interaction potential energy functional based on
Skyrme interaction of SkM and SLy series. The properties of ground states
of selected nuclei can be reproduced very well. The Coulomb barriers for a
series of reaction systems are studied and compared with the results of the
proximity potential. The fusion excitation functions for a series of fusion
reactions are calculated and the results are in good agreement with
experimental data.Comment: 17 pages, 10 figures, PRC accepte
Constraints on symmetry energy and nucleon effective mass splitting with Heavy Ion Collisions
A new version of the improved quantum molecular dynamics model has been
developed to include standard Skyrme interactions. Four commonly used Skyrme
parameter sets, SLy4, SkI2, SkM* and Gs are adopted in the transport model code
to calculate the isospin diffusion observables as well as single and double
ratios of transverse emitted nucleons. While isospin diffusion observables are
sensitive to the symmetry energy term, they are not very sensitive to the
nucleon effective mass splitting parameters in the interactions. Our
calculations show that the high energy neutrons and protons and their ratios
from reactions at different incident energies provide a robust observable to
study the momentum dependence of the nucleon effective mass splitting. However
the sensitivity of effective mass splitting effect on the n/p yield ratios
decreases with increasing beam energy, even though high energy proton and
neutron are produced more abundantly at high beam energy. Our calculations show
that the optimum incident energy to study nucleon effective masses is between
100-200 MeV per nucleon.Comment: Submitted to PLB, 14 pages, 4 figure
Manufacture of IRDye800CW-coupled Fe3O4 nanoparticles and their applications in cell labeling and in vivo imaging
BackgroundIn recent years, near-infrared fluorescence (NIRF)-labeled iron nanoparticles have been synthesized and applied in a number of applications, including the labeling of human cells for monitoring the engraftment process, imaging tumors, sensoring the in vivo molecular environment surrounding nanoparticles and tracing their in vivo biodistribution. These studies demonstrate that NIRF-labeled iron nanoparticles provide an efficient probe for cell labeling. Furthermore, the in vivo imaging studies show excellent performance of the NIR fluorophores. However, there is a limited selection of NIRF-labeled iron nanoparticles with an optimal wavelength for imaging around 800 nm, where tissue autofluorescence is minimal. Therefore, it is necessary to develop additional alternative NIRF-labeled iron nanoparticles for application in this area.ResultsThis study manufactured 12-nm DMSA-coated Fe3O4 nanoparticles labeled with a near-infrared fluorophore, IRDye800CW (excitation/emission, 774/789 nm), to investigate their applicability in cell labeling and in vivo imaging. The mouse macrophage RAW264.7 was labeled with IRDye800CW-labeled Fe3O4 nanoparticles at concentrations of 20, 30, 40, 50, 60, 80 and 100 μg/ml for 24 h. The results revealed that the cells were efficiently labeled by the nanoparticles, without any significant effect on cell viability. The nanoparticles were injected into the mouse via the tail vein, at dosages of 2 or 5 mg/kg body weight, and the mouse was discontinuously imaged for 24 h. The results demonstrated that the nanoparticles gradually accumulated in liver and kidney regions following injection, reaching maximum concentrations at 6 h post-injection, following which they were gradually removed from these regions. After tracing the nanoparticles throughout the body it was revealed that they mainly distributed in three organs, the liver, spleen and kidney. Real-time live-body imaging effectively reported the dynamic process of the biodistribution and clearance of the nanoparticles in vivo.ConclusionIRDye800CW-labeled Fe3O4 nanoparticles provide an effective probe for cell-labeling and in vivo imaging
The Influence of in-medium NN cross-sections, symmetry potential and impact parameter on the isospin observables
We explore the influence of in-medium nucleon-nucleon cross section, symmetry
potential and impact parameter on isospin sensitive observables in
intermediate-energy heavy-ion collisions with the ImQMD05 code, a modified
version of Quantum Molecular Dynamics model. At incident velocities above the
Fermi velocity, we find that the density dependence of symmetry potential plays
a more important role on the double neutron to proton ratio and the
isospin transport ratio than the in-medium nucleon-nucleon cross
sections, provided that the latter are constrained to a fixed total NN
collision rate. We also explore both and as a function of the
impact parameter. Since the copious production of intermediate mass fragments
is a distinguishing feature of intermediate-energy heavy-ion collisions, we
examine the isospin transport ratios constructed from different groups of
fragments. We find that the values of the isospin transport ratios for
projectile rapidity fragments with are greater than those constructed
from the entire projectile rapidity source. We believe experimental
investigations of this phenomenon can be performed. These may provide
significant tests of fragmentation time scales predicted by ImQMD calculations.Comment: 24 pages, 9 figures, to be published in Phys. Rev.
Altered expression of glycan patterns and glycan-related genes in the medial prefrontal cortex of the valproic acid rat model of autism
Autism spectrum disorders (ASD) represent a group of neurodevelopmental defects characterized by social deficits and repetitive behaviors. Alteration in Glycosylation patterns could influence the nervous system development and contribute to the molecular mechanism of ASD. Interaction of environmental factors with susceptible genes may affect expressions of glycosylation-related genes and thus result in abnormal glycosylation patterns. Here, we used an environmental factor-induced model of autism by a single intraperitoneal injection of 400 mg/kg valproic acid (VPA) to female rats at day 12.5 post-conception. Following confirmation of reduced sociability and increased self-grooming behaviors in VPA-treated offspring, we analyzed the alterations in the expression profile of glycan patterns and glycan-related genes by lectin microarrays and RNA-seq, respectively. Lectin microarrays detected 14 significantly regulated lectins in VPA rats, with an up-regulation of high-mannose with antennary and down-regulation of Siaα2-3 Gal/GalNAc. Based on the KEGG and CAZy resources, we assembled a comprehensive list of 961 glycan-related genes to focus our analysis on specific genes. Of those, transcription results revealed that there were 107 differentially expressed glycan-related genes (DEGGs) after VPA treatment. Functional analysis of DEGGs encoding anabolic enzymes revealed that the process trimming to form core structure and glycan extension from core structure primarily changed, which is consistent with the changes in glycan patterns. In addition, the DEGGs encoding glycoconjugates were mainly related to extracellular matrix and axon guidance. This study provides insights into the underlying molecular mechanism of aberrant glycosylation after prenatal VPA exposure, which may serve as potential biomarkers for the autism diagnosis
Effect of splitting of the neutron and proton effective mass on nuclear symmetry energy at finite temperature
We present the temperature and density dependence of symmetry energy for
nuclear matter at finite temperature based on the approach of the
thermodynamics with Skyrme energy density functional. We first classify the
Skyrme interactions into 7 groups according to the range of neutron and proton
effective mass in neutron matter limit(99.99 per cent neutron in the matter).
We find that there is obvious correlation between the temperature dependence of
the symmetry energy and the splitting of the neutron and proton effective mass.
For some Skyrme interactions with and strong splitting of
the neutron and proton effective mass in asymmetric nuclear matter, a
transition of the temperature dependence of symmetry energy from decreasing
with temperature at low densities to increasing with temperature at high
densities appears. For other Skyrme interactions, we do not observe such
phenomenon. Our study show that the symmetry energy in hot asymmetric matter
not only depends on symmetry potential part but also on the splitting of the
neutron and proton effective mass to a certain extent.Comment: 5 pages, 3 figures, accepted for Phys. Lett.