An efficient furan synthesis using heterogeneous catalysis

A wide variety of 3-alkyne-1,2-diols have been found to undergo exceptionally clean 5-endo-dig cyclisations followed by dehydration at ambient temperature to give the corresponding furans in essentially quantitative yields when exposed to 10 mol % of 10% w/w silver(I) nitrate absorbed on silica gel.     

双结π环自发磁化的研究

研究了超导双结π环的自发磁化现象.讨论了双结π环可能发生自发磁化的条件，指出了自发磁化条件不仅与电感参数β有关，而且与两结临界电流之比有关.并通过分析自由能证明自发磁化是稳定的状态.最后给出了讨论结果和渐进行为. 关键词： 双结π环 自发磁化 自由能     

On the invariants of base changes of pencils of curves,I

The main purpose of this paper is to prove the nonnegativity of the basic invariants of base changes of a surface fibration, which is conjectured by Xiao Gang. For this purpose we obtain some new inequalities between the invariants of the singularities ofz ^d =f(x, y). This work is supported by the National Natural Science Foundation of China and by the Science Foundation of the University Doctoral Program of CNEC. This paper is corrected while the author is visiting Max-Planck-Institut für Mathematik in Bonn.     

大气光通信中大气闪烁时间平滑效应研究

利用大气闪烁的时间平滑效应,增加光电探测器曝光时间是克服大气闪烁对大气光通信的瞄准、捕获、跟踪链路影响的有效途径之一.基于科尔莫戈罗夫谱,导出了弱湍流起伏区无限平面波和球面波的大气闪烁时间平滑因子的一般表达式,并且用几何光学近似得到了在大孔径和小孔径接收情况下的时间平滑因子近似表达式.在孔径远大于菲涅耳区尺度时,平面波和球面波的时间平滑因子的近似表达式与精确表达式的误差分别小于6%和3%.分析结果表明,孔径越小,时间平滑效应越显著,并且菲涅耳区尺度对时间平滑效应影响的程度也随着孔径的增加而减弱.     

Photoluminescence spectroscopy of carbon nanotube bundles: evidence for exciton energy transfer

We investigate photoluminescence of nanotube bundles. Their spectra are explained by exciton energy transfer between adjacent tubes, whereby excitation of large gap tubes induces emission from smaller gap ones. The consequent relaxation rate is faster than nonradiative recombination, leading to enhanced photoluminescence of acceptor tubes.     

Reservoir Engineering Strong Magnomechanical Entanglement via Dual-Mode Cooling

A hybrid cavity magnomechanical system to transfer the bipartite entanglements and achieve the strong microwave photon–phonon entanglement based on the reservoir engineering approach is constructed. The magnon mode is coupled to the microwave cavity mode via magnetic dipole interaction and to the phonon mode via magnetostrictive force (optomechanical-like). It is shown that the initial magnon-phonon entanglement can be transferred to the photon-phonon subspace in the case of these two interactions cooperating. In the reservoir-engineering parameter regime, the initial entanglement is directionally transferred to the photon-phonon subsystem, so a strong bipartite entanglement in which the magnon mode acts as the cold reservoir to effectively cool the Bogoliubov mode delocalized over the cavity and the mechanical deformation mode is obtained. Moreover, dual-mode cooling is realized by engineering the dissipation of photon and phonon modes within the target mode, which allows entanglement to be further enhanced. The results indicate that the steady-state entanglement is robust against temperature. The dual-mode cooling reservoir engineering scheme can potentially be extended to other three-mode quantum systems.     

Pressure-tuning domain-wall chirality in noncentrosymmetric magnetic Weyl semimetal CeAlGe

Science China Physics, Mechanics & Astronomy - The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is the largest and most sensitive single-dish radio telescope in the world and...     

Spin waves and phase transition on a magnetically frustrated square lattice with long-range interactions

We investigate the effects of long-range interactions on the spin wave spectra and the competition between magnetic phases on a frustrated square lattice with large spin S. Applying the spin wave theory and assisted with symmetry analysis, we obtain analytical expressions for spin wave spectra of competing Neel and (π, 0) stripe states of systems containing any-order long-range interactions. In the specific case of long-range interactions with power-law decay, we find surprisingly that the staggered long-range interaction suppresses quantum fluctuation and enlarges the ordered moment, especially in the Neel state, and thus extends its phase boundary to the stripe state. Our findings illustrate the rich possibilities of the roles of long-range interactions, and advocate future investigations in other magnetic systems with different structures of interactions.     

光纤传输速度干涉仪

介绍一种用多模光纤传输入射和反射激光的速度干涉仪，阐述了这种干涉仪的原理和结构，并将其与传统的速度干涉仪进行比较。给出了用这种干涉仪测量电爆管的弹丸速度和钨样品在铁飞片冲击压缩下的自由面速度的实验装置和结果。文中最后总结了这种干涉仪的性能及特点。     

Mass transfer of aerosols with axial diffusion in narrow rectangular channels

The problem of mass transfer of aerosols with axial, as well as radial, diffusion in laminar flow in a narrow rectangular channel is studied. Two cases are investigated. The first case is where all particles enter the channel inlet and none form within the channel; and the second, where no particles enter the channel, and “formation in flight” occurs within the channel. For each case, analyses are made for both slug and Poiseuille flows. The first twenty modes of the eigenvalues, the eigenfunctions, and the coefficients of series expansion are obtained for several diffusion Péclet numbers, Pe. The first twelve of them are presented for Pe=1, 5, 10, 100, and ∞. Asymptotic expressions for the eigenvalues and the eigenfunctions are also given. The effects of axial diffusion on the local particle concentration, the bulk concentration, the Sherwood number, and the fraction of aerosols arriving at any cross-section of the channel are studied for various diffusion Péclet numbers. It was found that, for diffusion with or without formation in flight, the effect of axial diffusion may be neglected at an axial distance from the channel inlet greater than one and a half times that of the channel height for 1<Pe<100.