A Study of Effects from a_(0)(980)Meson to Asymmetric Matter Based on a Parity Doublet Model

In the present work,we study the effect of the isovector scalar meson a_(0)(980)(also calledδ)to the asymmetric matter properties by constructing a parity doublet model with including the a_(0)(980)meson based on the approximate chiral U(2)_(L)×U(2)_(R)symmetry.The effect of a_(0)(980)to the properties of symmetric matter such as symmetry energy S(n_(B)),symmetry incompressibility K_(sym),symmetry skewness Q_(sym)is investigated.We find that,a_(0)(980)meson has significant effect to these nuclear matter properties especially when the chiral invariant mass of nucleon m_(0)is small.We also study the effect of the a_(0)(980)meson to the neutron star(NS)properties and find that it increase the radius of NSs,especially those having intermediate mass.Finally,we further constrain the value of the chiral invariant mass of the nucleon to 640 MeV≲m_(0)≲860 MeV for L_(0)=57:7MeV by comparing with the recent accepted value of K_(sym)and neutron star(NS)observational data.

Roles of Isospin in Evaporation Residue Cross Section as a Probe of Nuclear Dissipation

The influence of isospin on the excess of evaporation residue cross section over its standard statistical-model value for nuclei ^194pb, ^200Pb, and ^206pb is studied via a Langevin equation coupled with a statistical decay model. The magnitude of this excess for a low-isospin fissioning nucleus is shown to be larger and its dependence on the nuclear viscosity coefficient to be stronger than those of a high-isospin fissioning nucleus. These results suggest that to obtain a more accurate information of viscosity coefficient inside the saddle point by measuring evaporation residue cross sections, we had better choose those compound systems with small isospin.

Effects of Isospin on Pre-scission Particle Multiplicity of Heavy Systems and ItsExcitation Energy Dependence

Isospin effects on particle emission of fissioning isobaric sources and isotopic sources , and its dependence on the excitation energy are studied via Smoluchowski equations. It is shown that with increasing the isospin of fissioning systems, charged-particle emission is not sensitive to the strength of nuclear dissipation. In addition, we have found that increasing the excitation energy not only increases the influence of nuclear dissipation on particle emission but also greatly enhances the sensitivity of the emission of pre-scission neutrons or charged particles to the isospin of the system. Therefore, in order to extract dissipation strength more accurately by taking light particle multiplicities it is important to choose both a highly excited compound nucleus and a proper kind of particles for systems with different isospins.

Three—Body Force Effects on EOS of Asymmetric Nuclear Matter and Proton Fraction in Neutron Star Matter

The three-body force effects on the equation of state and its iso-spin dependence of asymmetric nuclear matter and on the proton fraction in neutron star matter have been investigated within Brueckner-Hartree-Fock approach by using a microscopic three-body force. It is shown that, even in the presence of the three-body force, the empirical parabolic law of the energy per nucleon vs. isospin asymmetry is fulfilled in the whole asymmetry range and also up to high density. The three-body force provides a strong enhancement of symmetry energy at high density in agreement with relativistic approaches. It also shows that the three-body force leads to a much more rapid increasing of symmetry energy with density in relatively high density region and to a much lower threshold density for the direct URCA process to occur in a neutron star as compared to the predictions adopting only pure two-body force.

Nitrogen Forms of Maillard Polymers Derived from Xylose and ^(15)N-Labelled Glycine

Water-soluble, nondialyzable Maillard polymers were prepared by reacting D-xylose with 15N-glycine (and/or glycine) at 68 ℃ and pH 8.0 at equimolar concentrations of 1, 0.5 and 0.1 mol L-1, respectively,for 13 days and partitioned into acid-insoluble (MHA) and acid-soluble (MFA) fractions. The nitrogen forms in these polymers were studied by using the 15N cross polarization-magic angle spinning nuclear magnetic resonance (CPMAS NMR) technique in combination with chemical methods. The 15N nuclear magnetic resonance (NMR) data showed that while the yield, especially the MHA/MFA ratio, varied considerably with the concentrations of the reactants, the nitrogen distribution patterns of these polymers were quite similar.From 65% to 70% of nitrogen in them was in the secondary amide and/or indole form with 24%~25% present as aliphatic and/or aromatic ammes and 5% to 11% as pyrrole and/or pyrrole-like nitrogen. More than half (50%~77%) of the N in these polymers were nonhydrolyzable. The role of Maillard reaction in the formation of nonhydrolyzable nitrogen in soil organic matter is discussed.

Structure of high spin state in proton-rich ^(74,76,78)Kr isotopes:A projected shell model description

The N≈Z nuclei in the mass A^80 region has been researched because of an abundance of nuclear structure phenomena.The projected shell model(PSM)was adopted to investigate the structure of high spin state in proton-rich 74,76,78Kr isotopes including yrast spectra,moment of inertia,electric quadrupole transitions and the behavior of single particle.The calculated results are in good agreement with available data and the shape coexistence in low-spin is also discussed.