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101.
We present a calculation of the neutrino-nucleon scattering cross-section which takes into account the nuclear correlations
in the relativistic random phase approximation (RPA). Our approach is based on a quantum-hadrodynamics model with exchange
of σ, ω, π, ρ and δ mesons. In view of applications to neutrino transport in the final stages of supernova explosion and proto-neutron
star cooling, we study the evolution of the neutrino mean free path as a function of density, proton-neutron asymmetry and
temperature. Special attention was paid to the issues of renormalization of the Dirac sea, residual interactions in the tensor
channel, coupling to the delta-meson and meson mixing. In contrast with the results of other authors, we find that the neutral-current
process is not sensitive to the strength g' of the residual contact interaction. As a consequence, it is found that RPA corrections with respect to the mean-field approximation
amount to only 10% to 15% at high density.
Received: 27 June 2001 / Accepted: 14 January 2002 相似文献
102.
The eigen frequencies of radial pulsations of neutron stars are calculated in a strong magnetic field. At low densities we
use the magnetic BPS equation of state (EOS) similar to that obtained by Lai and Shapiro while at high densities the EOS obtained
from the relativistic nuclear mean field theory is taken and extended to include strong magnetic field. It is found that magnetized
neutron stars support higher maximum mass whereas the effect of magnetic field on radial stability for observed neutron star
masses is minimal. 相似文献
103.
Jia WL Wang RY Song D Ball SJ McLean AB Wang S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(3):832-842
Two novel star molecules functionalized with 7-azaindolyl and 2,2'-dipyridylamino groups have been synthesized. Both molecules possess a sixfold rotation symmetry. Molecule L1 is based on the hexaphenylbenzene core with the formula of hexa[p-(7-azaindolyl)phenyl]benzene, while molecule L2 is based on the hexakis(biphenyl)benzene core with the formula of hexa[p-(2,2'-dipyridylamino)biphenyl]benzene. Both compounds have been characterized by single-crystal X-ray diffraction analyses. Molecule L1 forms extended two-dimensional layered structure, while L2 forms interpenetrating columnar stacks in the solid state, as revealed by X-ray diffraction analyses. Nanowire structures based on columnar stacks through self-assembly of L2 on a graphite surface were revealed by an STM study. Molecules L1 and L2 are capable of binding to metal ions, resulting in unusual structural motifs. Two Ag(I) complexes with the formulae of [(AgNO(3))(2)(L1)] (1) and [(AgNO(3))(3)(L1)] (2) were isolated from the reactions of AgNO(3) with L1. Compound 1 displays extended intermolecular pi-pi stacking interactions that are responsible for its extended two-dimensional structure in the crystal lattice. Complex 2 has a "bowl" shape and forms polar stacks in the crystal lattice. A Cu(II) complex with the formula of [{Cu(NO(3))(2)}(6)(L 2)] (3) was isolated from the reaction of Cu(NO(3))(2) with compound L2. The six Cu(II) ions in 3 are chelated by the 2,2'-dipyridylamino groups of the star ligand L2. Intermolecular Cu-O (nitrate) bonds lead to the formation of an extended two-dimensional coordination network of 3. Both L1 and L2 are blue luminescent. Their interactions with Ag(I) or Cu(II) cause drastic quenching of emission. In addition, the luminescence of L1 and L2 is sensitive to the presence of protons, which cause a reduction of emission intensity and a red shift of the emission energy. 相似文献
104.
Available Skyrme parametrizations with hyperons are examined from the point of view of their suitability for applications to neutron stars. It is shown that the hyperons can attenuate or even remove the problem of ferromagnetic instability common to (nearly) all Skyrme parametrizations of the nucleon-nucleon interaction. At high density the results are very sensitive to the choice of the interaction. The selected parameter sets are then used to obtain the resulting properties of both cold neutron stars and hot protoneutron stars. The general features known from other models are recovered. 相似文献
105.
We investigate the phase structure of color superconducting quark matter at intermediate densities for two- and three-flavor systems. We thereby focus our attention on the influence of charge neutrality conditions as well as -equilibrium of the different phases. These constraints are relevant in the context of quark matter at the interior of compact stars. We analyze the implications of color superconductivity on compact star configurations using different hadronic and quark equations of state.Presented at the 15th Indian-Summer School of Physics: Understanding Dense Matter, Prague, Czech Republic, 27 August–1 September, 2003. 相似文献
106.
Thodoris Tsoukatos Nikos Hadjichristidis 《Journal of polymer science. Part A, Polymer chemistry》2002,40(15):2575-2582
The synthesis of well‐defined 3‐ and 4‐miktoarm star copolymers of the A2B and A3B types is described, where A is 1,4‐polybutadiene and B is poly(1,3‐cyclohexadiene). The synthetic approach involves the reaction of poly(1,3‐cyclohexadienyl)lithium with an excess of methyltrichlorosilane or tetrachlorosilane followed, after the removal of excess silane, by a small excess of polybutadienyllithium. Characterization was carried out by size exclusion chromatography, low‐angle laser light scattering, laser differential refractometry, and NMR spectroscopy. The complete heterogeneous catalytic hydrogenation of the A2B and A3B miktoarm stars, with a calcium carbonate‐supported palladium catalyst, leads to the formation of A2B and A3B miktoarm stars with one amorphous polycyclohexylene arm with an extremely high glass‐transition temperature and two or three crystalline polyethylene arms. Differential scanning calorimetry was used to determine the glass‐transition temperature of the amorphous blocks of the starting and hydrogenated stars and the melting temperature of polyethylene. Solid‐state 13C NMR spectroscopy was performed to ensure the complete saturation of the polycyclohexadiene and polybutadiene arms. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2575–2582, 2002 相似文献
107.
Sergey Chernyy Jyoti P. Mahalik Rajeev Kumar Jacob Judas Kain Kirkensgaard Matthias M. L. Arras Hyeyoung Kim Lars Schulte Sokol Ndoni Gregory S. Smith Kell Mortensen Bobby G. Sumpter Thomas P. Russell Kristoffer Almdal 《Journal of polymer science. Part A, Polymer chemistry》2018,56(22):1491-1504
Fundamental understanding of microphase separation in ABC miktoarm copolymers is vital to access a plethora of nonconventional morphologies. Miktoarm stars based on poly(cis 1,4-isoprene) (I), poly(styrene) (S), and poly(2-vinylpyridine) (V) are model systems, which allow systematic studies of the effects of composition, chemical microstructure, and temperature on the thermodynamics of microphase separation. Eleven ISV-x (I:S:V = 1:1:x, v:v:v) miktoarm copolymers were synthesized by anionic polymerization affording well-defined copolymers with a variable V arm. Equilibrium bulk morphologies of all samples, as evidenced by small-angle X-ray scattering, transmission electron microscopy (TEM), and self-consistent field theory, showed a systematic transition from lamellae (x ≈ 0–0.2) to [8.8.4] tiling (x ≈ 0.6–0.9) to cylinders in undulating lamellae (x ≈ 2–4) and, finally, to hexagonally packed core–shell cylinders (x ≈ 5–8). Chemical microstructure of the I arm [poly(cis 1,4-isoprene)] versus poly(3,4-isoprene) is shown to play important role in affecting morphological behavior. To reconcile differences between ISV-x star morphologies reported in the literature and those reported herein, even for the same composition, effects of the microstructure of I arm on the Flory–Huggins parameter between I and V arms were taken into account in a qualitative manner. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1491–1504 相似文献
108.
Empirical data about the latitudinal asymmetry of the geomagnetic field are used to obtain quantitative estimates of the westward geographic drift. 相似文献
109.
Based on the new screening model, this paper discusses the influence
of superstrong magnetic fields on nuclear energy generation rates on
the surface of magnetars. The obtained result shows that the
superstrong magnetic fields can increase the nuclear energy
generation rates by many orders of magnitude. The enhancement may
have a significant influence for further study of the magnetars,
especially for the cooling, the x-ray luminosity observation and the
evolution of the magnetars. 相似文献
110.
By making use of Duan--Ge's decomposition theory of gauge potential
and the topological current theory proposed by Prof. Duan
Yi-Shi, we study a two-component superfluid Bose condensed system,
which is supposed to be realized in the interior of neutron stars in
the form of the coexistence of a neutron superfluid and a protonic
superconductor. We propose that this system possesses vortex lines.
The topological charges of the vortex lines are characterized by the
Hopf indices and the Brower degrees of φ-mapping. 相似文献