Quantum discord and classical correlation signatures of mobility edges in one-dimensional aperiodic single-electron systems

We investigate numerically the quantum discord and the classical correlation in a one-dimensional slowly varying potential model and a one-dimensional Soukoulis–Economou ones, respectively. There are well-defined mobility edges in the slowly varying potential model, while there are discrepancies on mobility edges in the Soukoulis–Economou ones. In the slowly varying potential model, we find that extended and localized states can be distinguished by both the quantum discord and the classical correlation. There are sharp transitions in the quantum discord and the classical correlation at mobility edges. Based on these, we study “mobility edges” in the Soukoulis–Economou model using the quantum discord and the classical correlation, which gives another perspectives for these “mobility edges”. All these provide us good quantities, i.e., the quantum discord and the classical correlation, to reflect mobility edges in these one-dimensional aperiodic single-electron systems. Moreover, our studies propose a consistent interpretation of the discrepancies between previous numerical results about the Soukoulis–Economou model.     

原子核基态性质的系统研究

在Skyrme-Hartree-Fock-Bogoliubov（SHFB）理论框架下,利用SkOP1,SkOP2,SKC和SKD 4套新的Skyrme相互作用参数系统地研究了Ca,Ni,Sn和Pb同位素链上原子核的结合能、电荷半径等基态性质,并重点讨论了丰中子Ca核的新中子幻数以及Pb的同位素位移现象。通过与实验数据和SLy5相互作用参数的结果对比,发现这4套相互作用参数都能很好地再现结合能的实验数据,其预言精度比SLy5要高。对于丰中子Ca核,只有SKC和SKD相互作用参数能够再现N=28处的壳效应,而对于实验上发现的新幻数N=32和34,所有的相互作用参数均不能再现这一结果。对于电荷半径,发现所有的相互作用参数均不能很好地预言Ca同位素链电荷半径的演化规律以及Pb的同位素位移现象。另外,还将这些相互作用参数推广至远离β稳定线原子核的单粒子能级结构研究,发现其不适用于描述其随同位旋的演化行为。因此,为了更好地描述远离β稳定线原子核的宏观性质及单粒子能级,建议在拟合Skyrme相互作用参数时,除自旋-轨道耦合项包括合理的同位旋依赖外,还要考虑张量力成分。The nuclear ground state properties of Ca, Ni, Sn and Pb isotopes, such as the binding energies, the charge radii, are studied systematically by 4 sets of new Skyrme parametrizations SKC, SKD, SkOP1 and SkOP2 in the framework of the Skyrme-Hartree-Fock-Bogoliubov (SHFB) method. The new magic numbers of neutronrich Ca isotopes and the isotopic shift of Pb isotopes are discussed emphatically. By the comparisons between the calculations and the experimental data and results from the SLy5 interaction parametrization, it is found that the experimental binding energies can be reproduced accurately by all parametrizations. The calculated accuracies of SKC, SKD SkOP1 and SkOP2 parametrizations are higher than the ones of SLy5 parametrization. For the neutron-rich Ca nuclei, the shell effect of N=28 can be reproduced by the SKC and SKD parametrizations, but the magic numbers at N=32 and 34 are not found by the calculations of all the parametrizations. For the charge radii, the experimental evolution tendency of Ca isotopes and isotopic shift of Pb isotopes can not be reproduced by all the parametrizations. In addition, all Skyrme parametrizations are extended to study the structure of the nuclei far from the β stability line, it is shown that the single-particle energy evolutions with the isospin are not suitable for being studied by these parametrizations. Thus the tensor force component should be considered besides the isospin dependence in spin-orbit coupling term when the Skyrme interaction parametrizations are fitted.     

并行多注THz折叠波导行波管的理论分析与数值模拟

为了提高THz行波管的输出功率,通过并行多注和功率合成的方法,完成了并行多注D波段折叠波导行波管的理论分析与数值模拟。计算结果表明：单束行波管在0.135~0.157 THz频率区间具有很好的色散平坦度,3 dB带宽为13 GHz,0.14 THz处获得了20.88 dB的最大增益;多束合成行波管在0.14 THz处获得了20.8 dB的合成增益,3 dB带宽区间合成效率不低于92%。数值模拟表明该方法很好地实现了多路放大信号的合成输出。并行多注行波管具有输出功率大、单束电流小、聚焦磁场低等优点,能够在低发射电流密度条件下实现大功率THz辐射。     

两注THz折叠波导行波结构的增益与传输特性（英文）

为了提高太赫兹行波管的输出功率,提出了多个传输信号进行功率合成的方法。首先,对D波段多注慢波结构进行设计及功分器的优化;然后,通过微铣削工艺完成了两注THz折叠波导结构的加工,加工精度满足实际设计要求;最后,利用CST软件对该结构的冷测与互作用特性进行了分析。仿真结果表明:该结构的S11值小于-20dB,实际测试值在-20dB左右,两者较吻合。冷测分析表明该结构具有22GHz(16%)的冷带宽,3dB增益带宽为12.5GHz。在各电子注的电压、电流、峰值输入功率大小分别为15.79kV,12mA,10mW时,单注结构获得了1.58 W的输出功率及22dB的增益;而两路信号在互作用完成后,获得了2.91 W的合成功率输出,合成效率不低于90%。通过合成的方法可以有效提高THz行波管的输出功率。     

Nano Si preparation by constant cell voltage electrolysis of FFC-Cambridge Process in molten CaCl2

Using FFC-Cambridge Process to prepare Si from SiO₂ is a promising method to prepare nanostructured and highly pure silicon for solar cells. However, the method still has many problems unsolved and the controlling effect of the cell voltage on silicon product is not clear. Here we report in this article that nano cluster-like silicon product with purity of 99.95% has been prepared by complete conversion of raw material SiO₂, quartz glass plate, using constant cell voltage electrolysis FFC-Cambridge Process. By analysis of XRD, EDS, TEM, HRTEM and ICP-AES as well as the discussion from the thermodynamics calculation, the morphology and components of the product based on the change of cell voltage are clarified. It is clear that pure silicon could be prepared at the cell voltage of 1.7–2.1 V in this reaction system. The silicon material have cluster-like structure which are made of silicon nanoparticles in 20–100 nm size. Interestingly, the cluster-like nano structure of the silicon can be tuned by the used cell voltage. The purity, yield and the energy cost of silicon product prepared at the optimized cell voltage are discussed. The purity of the silicon product could be further improved, hence this method is promising for the preparation of solar grade silicon in future.     

Erratum to “Forbidden pairs for spanning (closed) trails” [Discrete Math. 340 (2017) 1012–1018]

In this Erratum, we correct a flaw in Lv and Xiong (2017) and give a supplement of one result in it.     

Molecular Packing-Controlled Mechanical-Induced Emission Enhancement of Tetraphenylethene-Functionalised Pyrazoline Derivatives

Organic mechanofluorochromic (MFC) materials with mechanical-induced emission enhancement (MIEE) are scarce. Herein, Aggregation-induced emission (AIE)-active tetraphenylethene-functionalised pyrazoline derivatives with various non-conjugated substituent groups (Br, F, N,N-dimethylamino and cyano groups for TPEB, TPEF, TPEN and TPECN, respectively) were designed and synthesised. The fluorescence spectra of the compounds in the solid state were sensitive to mechanical stimuli and exhibited unique MFC properties. The solid fluorescence peaks of all compounds were red shifted, whereas the quantum yields of TPEB, TPEF and TPEN were increased and that of TPECN was slightly reduced after grinding. The MIEE mechanism was systematically investigated through structure–property relationship studies. The results showed that the pyrazoline ring of TPEB with MIEE property formed H-dimer aggregates with weak π–π stacking in the solid state. After grinding, the synergistic effects of conformational planarization and destructive π–π interactions induced the red shift of the fluorescence peak and the intensity enhanced. TPECN formed incompact J-aggregates with weak intermolecular interactions instead. The conformational planarization and increased intermolecular interactions induced by grinding led to the red-shifted peak and the slightly reduced intensity. These results clearly demonstrated that the translation of packing arrangements is an efficient method to design MIEE materials, which opens a new scope for designing unique MFC materials.     

Cu-catalyzed decarboxylative iodination of aryl carboxylic acids with NaI: A practical entry to aryl iodides under aerobic conditions

A simple and practical Cu-catalyzed decarboxylative iodination has been well established under aerobic condition, which provides a useful method to synthesize aryl iodides in moderate to good yields with the use of (hetero)aryl carboxylic acids and NaI as starting materials. Thiabendazole has been prepared via a three-step procedure to show synthetic practicability of the protocol.     

Dichloromethane as a methylene synthon for regioselective linkage of diverse carboxylic acids: Direct access to methylene diesters under metal-free conditions

This simple protocol is a convenient and cost-effective route to synthesize methylene diesters from a wide scope of carboxylic acids substrates with good functional group tolerance. Several gram-scale reactions have been performed to evaluate the effectiveness and practicality of this protocol.     

Prefixed-Threshold Real-Time Selection for Free-Space Sending-or-Not Twin-Field Quantum Key Distribution

As a variant of the twin-field quantum key distribution (TF-QKD), the sending-or-not twin-field quantum key distribution (SNS TF-QKD) is famous for its higher tolerance of misalignment error, in addition to the capacity of surpassing the rate–distance limit. Importantly, the free-space SNS TF-QKD will guarantee the security of the communications between mobile parties. In the paper, we first discuss the influence of atmospheric turbulence (AT) on the channel transmittance characterized by the probability distribution of the transmission coefficient (PDTC). Then, we present a method called prefixed-threshold real-time selection (P-RTS) to mitigate the interference of AT on the free-space SNS TF-QKD. The simulations of the free-space SNS TF-QKD with and without P-RTS are both given for comparison. The results showed that it is possible to share the secure key by using the free-space SNS TF-QKD. Simultaneously, the P-RTS method can make the free-space SNS TF-QKD achieve better and more stable performance at a short distance.