Extraordinary wavelength dependence of self-collimation effect in photonic crystal with low structural symmetry

We present the optical properties of a new type of photonic crystal (PC) named star-shaped PC (STAR-PC) with anomalous equi-frequency contours. Intentionally introducing low-symmetry in the primitive unit cell gives rise to progressively tilting flat contours, which are observed in the fifth band of the transverse magnetic mode. Due to the intrinsic dispersive feature of the proposed PCs, i.e. tilted self-collimation, the incident signal with different wavelengths can be successfully separated in a spatial domain without introducing any corrugations or complexities inside the structure. We show numerical investigations of wavelength selective characteristic of the proposed PC structure in both time and frequency domains. The STAR-PC approach can be considered a good candidate for the wavelength division applications in the design of compact photonic integrated circuits. For the purpose of wavelength separation implementations, the proposed structure may operate within the wavelength interval of 1484.5–1621.5 nm with a broad bandwidth of 8.82%. The corresponding inter-channel crosstalk value is as low as ?19 dB and the calculated transmission efficiency is above 97%.     

New quaternized poly(4-vinylpyridine-co-divinylbenzene) material containing nickel(II) Schiff base complex: synthesis,thermogravimetry, and application for heterogeneous electrooxidation of ethanol

Research on Chemical Intermediates - Poly(4-vinylpyridine) crosslinked by 2 % divinylbenzene was partially quaternized (20 % monomer equivalents) by a bidentate Schiff base nickel...     

Equivalence of structure constants in non-Kolmogorov and Kolmogorov spectra

We find the equivalence of the structure constants in non-Kolmogorov and Kolmogorov spectra in a turbulent atmosphere. As the reference point, the spherical wave scintillation index in a non-Kolmogorov medium is used. Relations of the structure constants are found to be functions of the power law of the turbulence spectrum and the Fresnel zone. It will be useful to employ the equivalence of the structure constants in making performance comparisons found with non-Kolmogorov and Kolmogorov spectra.     

On a new class of analytic function derived by a fractional differential operator

Making use of the fractional differential operator, we impose and study a new class of analytic functions in the unit disk (type fractional differential equation). The main object of this paper is to investigate inclusion relations, coefficient bound for this class. Moreover, we discuss some geometric properties of the fractional differential operator.     

Regioselective Synthesis of a New Class of N -Arylsulfonylaminated Biheterocycles

A novel and efficient method for the synthesis of a new variety of novel N -arylsulfonylamino derivatives of biheterocycles by the reaction of N -cyanoaceto-arylsulphonylhydrazides with f , g -unsaturated nitriles. The synthetic potential of the method is demonstrated. \centerline{\epsfbox{:art:s-fig-01a.eps}\hspace*{2pc}\epsfbox{:art:s-fig-01b.eps}\hspace*{2pc}\epsfbox{:art:s-fig-01c.eps}}     

Exploration of structural,optical, and photoluminescent properties of (1-x)NiCo2O4/xPbS nanocomposites for optoelectronic applications

The (1-x)NiCo₂O₄/xPbS (0≤ x≤ 0.2) nanocomposite samples are synthesized using the hydrothermal and thermolysis procedures. The different phases developed in the obtained nanocomposite samples are accurately determined using the x-ray diffraction technique equipped with a line-detector. The percentage of the formed phases (NiCo₂O₄ (NCO), PbS, PbSO₄), structural and microstructure parameters are determined using Rietveld quantitative phase analysis. The transmission electron microscope (TEM) images and Rietveld analysis reveal almost isotropic particle size in the nano range with a very narrow size distribution. The obtained phase percentage of PbS and PbSO₄ are smaller than nominated values (x) suggesting dissolving of some Pb and S ions into NCO which is then confirmed by the analysis of Fourier-transform infrared (FTIR) spectra of nanocomposite samples. The absorption spectra are modified upon doping NCO with PbS. The optical band gaps of the nanocomposites increase as the amount of PbS augments. The effect of alloying on extinction coefficient, refractive index, dielectric constant, optical conductivity, the intensity, and emitted color from the photoluminescence of the nanocomposite samples are also studied. The refractive index value of NCO and NCO-PbS nanocomposite samples exhibit normal dispersions. The photoluminescent measurements reveal that the NCO-PbS nanocomposites can emit a violet color. The improvement in the values of the nonlinear optical (NLO) parameters of pristine NCO at high frequencies or the nanocomposite samples at low frequencies, are made them used in NLO photonic devices.     

Normal coordinate analyses and barrier to internal rotation of nitroso- and nitroazides

The conformational and structural stability of nitrosoazide NNN-N=O and nitroazide NNN-NO2 were investigated by DFT-B3LYP and ab initio MP2 calculations with 6-311++G** basis set. From the calculations, nitrosoazide was predicted to exist predominantly in the planar trans (NNN and N=O groups are trans to each other) structure with high trans-cis rotational barrier of about 11 kcal mol-1 as a result of pronounced conjugation between the azide group and the N=O bond. The NO2 rotational barrier in nitroazide was predicted from the symmetric potential function to be of about 7 kcal mol-1. The vibrational frequencies were calculated at the DFT-B3LYP level and the infrared and Raman spectra of the cis-trans mixture were plotted. Complete vibrational assignments were made on the basis of normal coordinate calculations for the stable conformers of both molecules. For nitrosoazide, the calculated wavenumbers were compared to the corresponding experimental values obtained from early reported Raman spectrum of the molecule.     

Backlund transformations and Painleve analysis: Exact solutions for a Grad--Shafranov-type magnetohydrodynamic equilibrium

The problem of plasma equilibrium in a gravitational field isinvestigated analytically. For the two-dimensional problem,the system of ideal magnetohydrodynamic equations is reducedto a single nonlinear elliptic equation of the magnetic potentialas a Grad-Shafranov-type equation. By specifying the arbitraryfunctions in this equation, the sinh-Poisson equation can beobtained. Using the Bäcklund-transformation technique andPainlevé analysis, a set of exact solutions are obtainedwhich adequately describe force-free models for solar flaresand plane-parallel filaments of a diffuse magnetized plasmasuspended horizontally in equilibrium in a uniform gravitationalfield.     

维汉机器翻译词典的结构设计与实现

机器翻译词典的设计是机器翻译系统关键之一．机器翻译词典的质量和信息量直接限定机器翻译系统的应用领域和覆盏范围．本文介绍机器翻译词典词条收集方法且讨论维汉机器翻译词典的设计原则、构造方法及其数据结构．