Vibrational Spectroscopic Study on Ion Solvation and Association of Lithium Perchlorate in 4-Methoxymethyl-ethylene Carbonate

Solvation interaction and ion association in solutions of lithium perchlorate/4-methoxymethyl-ethylene carbonate （MEC） have been studied by using Infrared and Raman spectra as a function of concentration of lithium perchlorate. The splitting of ring deformation band and ring ether asymmetric stretching band, and the change of carbonyl stretching band suggest that there should be a strong interaction between Li^＋ and the solvent molecules, and the site of solvation should be the oxygen atom of carbonyl group. The apparent solvation number of Li^＋ was calculated by using band fitting technique. The solvation number was decreased from 3.3 to 1.1 with increasing the concentration of LiClO4/MEC solutions. On the other hand, the band fitting for the ClO4^- band revealed the presence of contact ion pair, and free ClO4^- anion in the concentrated solutions.     

A simple and efficient algorithm for fused lasso signal approximator with convex loss function

We consider the augmented Lagrangian method (ALM) as a solver for the fused lasso signal approximator (FLSA) problem. The ALM is a dual method in which squares of the constraint functions are added as penalties to the Lagrangian. In order to apply this method to FLSA, two types of auxiliary variables are introduced to transform the original unconstrained minimization problem into a linearly constrained minimization problem. Each updating in this iterative algorithm consists of just a simple one-dimensional convex programming problem, with closed form solution in many cases. While the existing literature mostly focused on the quadratic loss function, our algorithm can be easily implemented for general convex loss. We also provide some convergence analysis of the algorithm. Finally, the method is illustrated with some simulation datasets.     

Synthesis, structure, and luminescent properties of three silver(I) complexes with organic carboxylic acid and 4,4′-bipyridine-like ligands

The reactions of AgNO₃ with combinations of 1,2-bis(4-pyridyl)ethane(bpa)/4,4′-bipyridine (bpy), 4,4′-stilbenedicarboxylic acid (H₂sda)/2,2′-diphenylaminedicarboxylic acid (H₂dpadc)/2,6-naphthalenedicarboxylic acid (H₂ndc) in aqueous alcohol/ammonia at room temperature produce block-like crystals of [Ag₂(bpa)_1.5(sda)_0.5](sda)_0.5·7H₂O, [Ag₂(bpa)₂(H₂O)₃](dpadc), [Ag₂(bpy)₂](ndc)·4H₂O. All three complexes consist of 1D infinite silver–ligand cationic chains, interspersed with organic carboxylate anions that provide charge compensation in the crystal structures. The lattice water molecules are situated among the framework of the crystal structure and show rich hydrogen-bonding interactions, which help to orientate the organic carboxylate anions in the crystal packing, and the presence of Ag···N and Ag···Ag contacts contributes to strengthen the frameworks. The luminescent properties and thermogravimetric analyses of the three complexes are also presented.     

Numerical study of the transition to chaos of a buoyant plume from a two-dimensional open cavity heated from below

The transition to a chaotic plume from a two-dimensional (2D) open cavity heated from below has been investigated using numerical simulation. A large range of Rayleigh numbers (Ra) pertaining to an aspect ratio of A = 1, and Prandtl number (Pr) of Pr = 0.71 (air) is numerically investigated. It is shown that there exists a complex transition of the plume from a steady reflection symmetry to a chaotic flow with a sequence of bifurcations. As the Rayleigh number increases, the plume from the open cavity undergoes a supercritical pitchfork bifurcation from a steady reflection symmetry to a steady reflection asymmetry flow. Once the Rayleigh number exceeds 7 × 10³, the plume appears as a distinct flapping namely, a Hopf bifurcation, and then as a distinct puffing. The chaotic plume has the possibility to exhibit an alternate appearance of flapping and puffing in the event the Rayleigh number exceeds 8 × 10⁴. Moreover, the dynamics of the plume from the open cavity is discussed, and the dependence on the Rayleigh number of heat and mass transfer of the plume from the open cavity is quantified.     

Self-converse large sets of pure hybrid triple systems

Acta Mathematicae Applicatae Sinica, English Series - A hybrid triple system of order v, briefly by HTS (v), is a pair (X, B) where X is a v-set and B is a collection of cyclic and transitive...     

Lifting graph automorphisms along solvable regular covers

A solvable cover of a graph is a regular cover whose covering transformation group is solvable. In this paper, we show that a solvable cover of a graph can be decomposed into layers of abelian covers, and also, a lift of a given automorphism of the base graph of a solvable cover can be decomposed into layers of lifts of the automorphism in the layers of the abelian covers. This procedure is applied to classify metacyclic covers of the tetrahedron branched at face-centers.     

Objective Bayesian analysis of the Frechet stress–strength model

Several reference priors and a general form of matching priors are derived for a stress–strength system, and it is concluded that none of the reference priors is a matching prior. The study shows that the matching prior performs better than Jeffreys prior and reference priors in meeting the target coverage probabilities.     

基于裂纹扩展脆性岩石动力压缩力学特性研究

动态压缩荷载作用下，脆性岩石内部动态细观裂纹扩展特性，对岩石宏观动态力学特性有着重要的影响。然而，对岩石内部动态细观裂纹扩展与宏观动态力学特性的关系研究较少。基于准静态裂纹扩展作用下的应力-应变本构模型、准静态与动态裂纹扩展断裂韧度关系、裂纹速率与应变率关系模型及应变率与动态断裂韧度关系，提出了一种基于细观力学的动态应力-应变本构模型。其中裂纹速率与应变率关系，是根据裂纹长度与应变关系的时间导数推出；应变率与动态断裂韧度关系，是根据推出的裂纹速率及应变率关系，与裂纹速率及断裂韧度关系相结合而得到。研究了应变率对应力-应变本构关系及动态压缩强度影响。并通过试验结果验证了模型的合理性。讨论了岩石初始损伤、围压、模型中参数m、ε₀和R对应力-应变关系、动态压缩强度和动态弹性模量的影响。研究结果可为动态压缩荷载作用下深部地下工程脆性围岩稳定性分析提供了一定的理论支持。     

The effects of chemical composition and distribution on the preservation of phytolith morphology

Different types of phytolith even when coming from the same plant react to high temperatures in different ways. To understand the behavior of phytoliths upon heating, we examined composition and distribution of some elements within different phytolith types using SEM-EDS and synchrotron radiation μ-X-ray fluorescence. By analyzing phytoliths from rice husk, rice leaf and Than tree leaf, we find that the compositions and distributions of metal oxides within different phytolith types are quite different. It is well known that metal oxides have been used as fluxing agent to reduce the melting temperature of SiO₂ in the production of glass, and different metal oxides can be used to produce a variety of glass with diverse features. Similarly, metal elements including potassium, magnesium and calcium in phytoliths should also act as a fluxing agent under high temperature, and the differential compositions and distributions of these metal elements within the phytoliths resulted in the variable reaction to heating. In sum, there is a negative relationship between the flux elements composition in phytoliths, and the temperatures at which phytoliths deform; furthermore, potassium and calcium in the rice leaf phytolith are almost evenly distributed in all parts, which may cause the phytolith’s shape to deform evenly. In comparison, Than tree leaf phytolith is found to have a high percentage of potassium and calcium located exclusively on the outside, which may explain why the deformation of Than tree leaf phytolith occurs firstly at the outside.     

磁光平面波导的单向传播特性

表面磁等离子体(surfacemagnetoplasmons,SMPs)是一种在电介质和偏置磁场作用下磁光材料界面处传播的近场电磁波.其独特的非互易传播特性引起了大量科研工作的关注,但在具体的波导结构设计上仍存在很多问题.本文研究了一种银-硅-磁光材料的3层平面波导结构,SMPs在磁光材料和硅的界面处传播,发现在特定的频率范围内,SMPs的基模及高阶模式均具有正向或反向的单向传播特性.分别计算了旋磁与旋电材料平面波导的色散方程,研究了硅层厚度与外加磁场对能带结构及SMPs单向传播区域的影响,发现无论是旋磁或旋电材料的结构,硅层厚度的增加使高阶模式使高阶模式出现在更低的频率位置,使单向传输带宽变小甚至消失,外加磁场的变大使磁光材料的能带结构频率增大的同时带隙中也引入了高阶模式.计算了2种磁光材料平面波导的正向和反向的单向传播带宽宽度,发现旋磁材料YIG的单向SMPs模式出现在GHz波段,最大单向带宽可达到2.45 GHz;旋电材料InSb的单向SMPs模式出现在THz波段,最大单向带宽达到3.9 THz.