Asymptotics toward the planar rarefaction wave for viscous conservation law in two space dimensions

This paper is concerned with the asymptotic behavior of the solution toward the planar rarefaction wave connecting and for the scalar viscous conservation law in two space dimensions. We assume that the initial data tends to constant states as , respectively. Then, the convergence rate to of the solution is investigated without the smallness conditions of and the initial disturbance. The proof is given by elementary -energy method.

     

Powder spectra of 181Ta NMR in 2HTaS2

Powder spectra of ¹⁸¹Ta NMR in a swept field for the transitions between degenerate PQR states are discussed. Spin-echo signals of ¹⁸¹Ta in 2HTaS₂ powder have been observed at 4.2 K with line shapes that can clearly be associated with two inequivalent Ta sites, having well-defined asymmetry parameter (η) with values of 0.00 and 0.52 (± 0.02), one of which has the local charge density deviating strongly from the axial symmetry.     

Electron hopping in Fe1−xCuxCr2S4 (0<x<0.5)

A theoretical expression for the line shape of the Mössbauer spectra in the presence of electron hopping between Fe²⁺ and Fe³⁺ is obtained by using a simple stochastic model. Analyses based upon this expression show that the origin of the complicated Mössbauer spectra observed in the magnetic semiconductors Fe_1?xCu_xCr₂S₄ (0<x<0.5) at 77 K is electron hopping between Fe⁺² and Fe³⁺ This hopping occurs at a rate of a few MHz. Quantitative estimates are given for some parameters; the isomer shifts, the internal magnetic fields, the quadrupole splittings and the proportions of Fe²⁺ and Fe³⁺. The valence distribution in this system is determined from the results. For example, the distribution Fe²⁺_0.69Fe³+_0.29Cu¹⁺_0.02Cr³⁺_1.72Cr²⁺_0.28S^2?₄ is obtained for x = 0.02. The existence of Cr²⁺ is concluded.     

The NMR study of the mixed compound (CH3NH3)2Cu(Cl0.1Br0.9)4

The mixed compound (CH₃NH₃)₂Cu(Cl_0.1Br_0.9)₄ which has random bonds of ferromagnetic and antiferromagnetic interactions has been investigated by the pulsed NMR of ¹H, ^63,65Cu and ^79,81Br. The temperature dependence of the line width of ¹H showed the existence of the magnetic phase transition at 15 K in the applied field of 4 kOe. The moments of Cu²⁺ have been shown to lie within the c-plane and have some randomness from the field dependence of the NMR spectrum and the spin-echo decay time of the copper and the bromine nuclei.     

Enhancement of pionic modes in the quasielastic region

We report an evidence for the precursor phenomena of the pion condensation, which is found in the enhancement of the spin longitudinal cross sections ID _q of the quasielastic ¹²C, $^{40} Ca(\vec p, \vec n)$ , reactions at the incident energy 494 and 346 MeV around the momentum transfer q ≈ q _c , the critical momentum of the pion condensation. We utilized the distorted wave impulse approximation incorporated with the continuum random phase approximation. We adjusted the Landau-Migdal parameters, g′ _NN and g′ _NΔ, and obtained g′ _NN ≈ 0.6–0.7 and g′ _N Δ ≈ 0.3–0.4, which are consistent with those obtained from the energy of the Gamov-Teller giant resonance and the quenching factor of the Gamov-Teller sum rule.     

Three-dimensional relativistic electromagnetic subcycle solitons

Three-dimensional (3D) relativistic electromagnetic subcycle solitons were observed in 3D particle-in-cell simulations of an intense short-laser-pulse propagation in an underdense plasma. Their structure resembles that of an oscillating electric dipole with a poloidal electric field and a toroidal magnetic field that oscillate in phase with the electron density with frequency below the Langmuir frequency. On the ion time scale, the soliton undergoes a Coulomb explosion of its core, resulting in ion acceleration, and then evolves into a slowly expanding quasineutral cavity.     

Proposed double-layer target for the generation of high-quality laser-accelerated ion beams

In order to achieve a high-quality, i.e., monoenergetic, intense ion beam, we propose the use of a double-layer target. The first layer, at the target front, consists of high-Z atoms, while the second (rear) layer is a thin coating of low-Z atoms. The generation of high-quality proton beams from the double-layer target, irradiated by an ultraintense laser pulse, is demonstrated with three-dimensional particle-in-cell simulations.     

Platinum complex-catalyzed hydrosilylation and isomerization of methylenecyclopropane derivatives. Effect of structures of the substrate and catalyst

PtI(2)(PPh(3))(2) catalyzes hydrosilylation of 2,2-diphenyl-1-methylenecyclopropane with HSiEt(3), HSiPh(3), HSiEt(2)Ph, HSiPhCl(2), and HSiCl(3) under solvent-free conditions at 140 degrees C to produce the silyl compounds with a (2,2-diphenylcyclopropyl)methyl substituent in moderate to high yields without ring-opening of the substrate. PtI(2)(PPh(3))(2) is converted by the reaction into PtH(I)(PPh(3))(2), which also catalyzes the hydrosilylation of the methylenecyclopropanes. The reaction of 2-phenyl-1-methylenecyclopropane, 2-methyl-2-phenyl-1-methylenecyclopropane, 2,2-diphenethyl-1-methylenecyclopropane, and alkylidenecyclopropanes with HSiEt(3) catalyzed by PtI(2)(PPh(3))(2) causes addition of hydrosilane to the substrate accompanied by ring-opening. 2,2-Diphenyl-1-methylenecyclopropane undergoes ring-opening isomerization in the presence of HSi(OEt)Me(2) and Pt(PEt(3))(3) catalyst to give 1,1-diphenyl-1,3-butadiene. The pathways for the hydrosilylation and the isomerization are discussed.     

Photoluminescence switching of azobenzene-conjugated Pt(II) terpyridine complexes by trans-cis photoisomerization

Pt(II) complexes with a terpyridylazobenzene ligand (tpyAB) were newly synthesized, and their photoluminescence properties by trans-cis isomerization of the azo moiety were investigated. In these complexes, upon excitation with 366-nm light in polar solvents such as DMF, DMSO, and propylene carbonate, trans-to-cis isomerization with significant UV-vis spectral changes occurred almost completely. Cis-to-trans isomerization was observed both by irradiation with visible light and by heat. The reduction peaks due to the terpyridine and the azo group in the cyclic voltammograms of the Pt complexes were shifted in the positive direction by trans-to-cis isomerization. Emission spectral changes due to trans-cis isomerization were observed for both the tpyAB and the Pt complexes. The significant differences in the emission properties of the complex compared to tpyAB include the observation that both the excitation and emission wavelengths were shifted to lower energy, located in the visible region. Moreover, the change in emission intensity between the trans and cis forms was more significant upon excitation with UV light, because the trans form of the complexes showed absolutely no emission. Accordingly, the azobenzene-conjugated Pt(II) terpyridine complexes promise to be doubly photofunctional materials, showing complete off-on switching of emission linked to the trans-cis conformation change.     

用L~2能量法研究粘性守恒律解的渐近性态(英文)

本文讨论单个粘性守恒律方程与具有粘性的ｐ方程组的Ｃａｕｃｈｙ问题．根据初始资料的不同情形,其相应的Ｒｉｅｍａｎｎ问题以疏散波,激波或它们的迭加为弱解．本文的目的是指出Ｃａｕｃｈｙ问题的解将分别趋于疏散波,激波或它们的迭加．本文基本方法是能量积分法．文中综述了现有的成果,也提出了一些未解决的问题．