光纤中光的偏振态的几种表示方法

阐述了光纤中影响光的偏振态的几个因素。用椭圆表示法和邦加（Poincare)球图形表示法对光的任意偏振态进行了描述，并用平面的史密斯圆图来等效邦加球。编制了QUICK BASIC计算机程序，绘制了史密斯圆图的等α线、等δ线和等β线，程序能快速显示任意偏振态的椭圆表示和史密斯圆图表示，讨论了史密斯圆图的特性和应用。     

Several classes of optimal ternary cyclic codes with minimal distance four

In this paper, by analyzing the solutions of certain equations over ${\mathbb{F}}_{3^m}$, we present four classes of optimal ternary cyclic codes with parameters $[3^m-1,3^m-1-2m,4]$. It is shown that some recent work on this class of optimal ternary cyclic codes are special cases of our results.     

Second Sphere Effects Promote Formic Acid Dehydrogenation by a Single-Atom Gold Catalyst Supported on Amino-Substituted Graphdiyne

Regulating the second sphere of homogeneous molecular catalysts is a common and effective method to boost their catalytic activities, while the second sphere effects have rarely been investigated for heterogeneous single-atom catalysts primarily due to the synthetic challenge for installing functional groups in their second spheres. Benefiting from the well-defined and readily tailorable structure of graphdiyne (GDY), an Au single-atom catalyst on amino-substituted GDY is constructed, where the amino group is located in the second sphere of the Au center. The Au atoms on amino-decorated GDY displayed superior activity for formic acid dehydrogenation compared with those on unfunctionalized GDY. The experimental studies, particularly the proton inventory studies, and theoretical calculations revealed that the amino groups adjacent to an Au atom could serve as proton relays and thus facilitate the protonation of an intermediate Au−H to generate H₂. Our study paves the way to precisely constructing the functional second sphere on single-atom catalysts.     

A Bidentate Ligand Featuring Ditopic Lewis Acids in the Second Sphere for Selective Substrate Capture and Activation

We present a ligand platform featuring appended ditopic Lewis acids to facilitate capture/activation of diatomic substrates. We show that incorporation of two 9-borabicyclo[3.3.1]nonane (9-BBN) units on a single carbon tethered to a pyridine pyrazole scaffold maintains a set of unquenched nitrogen donors available to coordinate Fe^II, Zn^II, and Ni^II. Using hydride ion affinity and competition experiments, we establish an additive effect for ditopic secondary sphere boranes, compared to the monotopic analogue. These effects are exploited to achieve high selectivity for binding NO₂⁻ in the presence of competitive anions such as F⁻ and NO₃⁻. Finally, we demonstrate hydrazine capture within the second-sphere of metal complexes, followed by unique activation pathways to generate hydrazido and diazene ligands on Zn and Fe, respectively.     

Photosystem II Inspired NiFe-Based Electrocatalysts for Efficient Water Oxidation via Second Coordination Sphere Effect

The mismatched fast-electron-slow-proton process in the electrocatalytic oxygen evolution reaction (OER) severely restricts the catalytic efficiency. To overcome these issues, accelerating the proton transfer and elucidating the kinetic mechanism are highly sought after. Herein, inspired by photosystem II, we develop a family of OER electrocatalysts with FeO₆/NiO₆ units and carboxylate anions (TA²⁻) in the first and second coordination sphere, respectively. Benefiting from the synergistic effect of the metal units and TA²⁻, the optimized catalyst delivers superior activity with a low overpotential of 270 mV at 200 mA cm⁻² and excellent cycling stability over 300 h. A proton-transfer-promotion mechanism is proposed by in situ Raman, catalytic tests, and theoretical calculations. The TA²⁻ (proton acceptor) can mediate proton transfer pathways by preferentially accepting protons, which optimizes the O−H adsorption/activation process and reduces the kinetic barrier for O−O bond formation.     

Synthesis and Structural Characterization of a Novel Sphere Compound of Mo_8V_2O_(28)·7H_2O

Polyoxometalates( POMs) are attractivebuilding blocks for functional materials withpotential application in electrocatalysis and thepreparations of molecular electronic,orelectrooptical devices[1,2 ] . With the recentdiscovery of giant nanoporous and spherePOMs[3— 6] ,it remains a great challenge tosynthesize rationally new nanoscale materialspossessing novel structures and desirableproperties.The present paper covers a novelstructure characterization of Mo8V2 O2 8· 7H2 O( abbreviated Mo…     

一个微生物生态模型分岔的周期轨

本文研究一类与厌氧消化过程微生物生态模型有关的微分方程组在非双曲情形下的扰动。在其一维不变流形上讨论自治扰动下中心附近发生的Pionceare分岔,所涉及的闭轨存在性问题是许多熟知结果^[1-5]不能包含的情形。进而,利用Melnikov函数方法,给出周期扰动下发生次调和分岔的参数条件。     

A compatible and conservative spectral element method on unstructured grids

We derive a formulation of the spectral element method which is compatible on very general unstructured three-dimensional grids. Here compatible means that the method retains discrete analogs of several key properties of the divergence, gradient and curl operators: the divergence and gradient are anti-adjoints (the negative transpose) of each other, the curl is self-adjoint and annihilates the gradient operator, and the divergence annihilates the curl. The adjoint relations hold globally, and at the element level with the inclusion of a natural discrete element boundary flux term.     

Universal Inequalities for Eigenvalues of the Buckling Problem of Arbitrary Order

We investigate the eigenvalues of the buckling problem of arbitrary order on compact domains in Euclidean spaces and spheres. We obtain universal bounds for the kth eigenvalue in terms of the lower eigenvalues independently of the particular geometry of the domain.