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71.
E. B. Barmatov D. A. Pebalk M. V. Barmatova V. P. Shibaev 《Journal of polymer science. Part A, Polymer chemistry》2001,39(22):3953-3959
Liquid‐crystalline (LC) ionomers containing 2–15 mol % calcium ions were synthesized by the exchange reaction between the nematic LC copolymer, bearing oxycyanobiphenyl mesogenic groups, and the carboxyl groups of acrylic acid, with calcium acetate. The incorporation of 2–3 mol % Ca ions in the LC copolymer leads to some rise in the clearing point and glass‐transition temperature. A further increase in the concentration of metal ions (>5 mol %) is accompanied by induction of the smectic A phase where clearing point and glass‐transition temperatures keep constant values. Phase behavior of the LC ionomers may be understood on the basis of a structural model that considers the dual role of calcium ions in a polymer matrix. Metal ions act as points of noncovalent electrostatic binding of the polymer chains and are capable of forming larger ionic associates (multiplets). The comparison of the phase behavior of sodium and calcium containing LC ionomers shows that the formation of ionic links may lead to the growth of structure defects suppressing a positive influence of charged groups on the mesophase clearing temperature. The orientation behavior of the LC ionomers in the magnetic field was studied. It was shown that the incorporation of calcium ions (3 mol %) in the LC copolymer matrix leads to the growth of orientation order parameter S of the nematic phase. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3953–3959, 2001 相似文献
72.
73.
By employing the QCD factorization approach for the exclusive B→Vу decays, we study the exclusive decay B→K^*у in the top-quark two-Higgs-doublet mode/(T2HDM). Within the considered parameter space, we find the following conclusions (a) A hght charged-Higgs boson with a mass about 200 GeV is clearly excluded by the date of B→K^*у decay, and this lower limit is comparable with that from the inclusive B→X8*у decay; (b) The theoretical predictions for CP asymmetry of B→K^*у in the T2HDM is always less than 1% in size; and (c) The isospin symmetry breaking for B→K^*у decay in the SM and T2HDM considered here is around 6% in size and well consistent with the data and the general expectations. 相似文献
74.
75.
In this paper, we calculated the new physics contribution to theoretically very clean rare decay
B→Xsνν
in the general two-Higgs-doublet model (model III). Within the considered parameter space, we found that
(a) the new physics contribution can provide one to two orders of enhancement to the branching ratio
B(B→Xsνν) and can saturate the experimental bound
on B(B→Xsνν) in some regions of the parameter space; (b) besides the CLEO data of B→Xsγ, the ALEPH upper
limit on B(B→Xsνν) also leads to further constraint on the size of the Yukawa coupling λtt: λtt< 6.4 for
λbb=2.7 and
mH+=200 GeV. 相似文献
76.
Resonating-group method has been applied to calculate the
ΩΩ (SIJ=-6,0,0) dibaryon state in the framework of the extended quark-delocalization color-screening model. The mass of the di-Ω is predicted to be about 45 MeV lower than the
Ω-Ω threshold. The effect of channel coupling due to the
tensor force and sensitivity to meson exchange short-range cutoff
radius, r0 have also been studied. 相似文献
77.
相对论夸克模型用来计算面和N*的电产生振幅.介子云的贡献是一个重要的课题.计算表明考虑了介子云的作用对Δ和N*(1440)螺旋度振幅的解释将会有明显的改进.这有助于进一步认识Roper共振态的性质. 相似文献
78.
79.
用16O束轰击197Au靶,通过熔合蒸发4n反应产生了209Fr,借助于氦喷嘴带传输系统对其衰变性质进行了研究.由γ-t,X-γ-t,γ-γ-t符合及γ-γ延迟符合测量得到的结果,首次建立了209Fr的(EC+β+)衰变纲图.它包含了20条γ射线.209Rn的5个低位态的成员可以用[(210Rn2+)(νf5/2)-1]多重态结构来解释.实验估计209Fr(EC+β+)衰变的分支比为(3.0±1.5)%. 相似文献
80.
We try to determine phenomenologically the extent of in-medium modification of σ-meson parameters so that the saturation observables
of the nuclear matter equation of state (EOS) are reproduced. To calculate the EOS we have used Brueckner-Bethe-Goldstone
formalism with Bonn potential as two-body interaction. We find that it is possible to understand all the saturation observables,
namely, saturation density, energy per nucleon and incompressibility, by incorporating in-medium modification of σ-meson-nucleon
coupling constant and σ-meson mass by a few per cent. 相似文献