Microstructure and wear properties of laser clad Cuss/Cr5Si3 metal silicide composite coatings

Wear resistant Cu-based solid solution (Cu_ss) toughened Cr₅Si₃ metal silicide composite coatings were fabricated on austenitic stainless steel AISI321 by laser cladding process. Due to the rapidly solidified microstructural characteristics and the excellent toughening effect of Cu_ss on Cr₅Si₃, the Cu_ss/Cr₅Si₃ coatings have outstanding wear resistance and low coefficient of friction under room temperature dry sliding wear test conditions coupling with hardened 0.45% C steel.     

Er3+/Yb3+共掺Gd3Sc2Ga3O12晶体的上转换发光

研究了提拉法生长的Er³⁺/Yb³⁺:Gd₃Sc₂Ga₃O₁₂和Er³⁺:Gd₃Sc₂Ga₃O₁₂晶体在室温下320—1700nm范围的吸收光谱和500—750nm范围内的上转换荧光谱,同时对其上转换荧光的可能发生机制、途径以及上转换过程可能对Er^{3+相似文献}   

Atom waveguide and 1D optical lattice using a two-color evanescent light field around an optical micro/nano-fiber

We propose a two-color scheme of atom waveguides and one-dimensional （1D） optical lattices using evanescent wave fields of different transverse modes around an optical micro/nano-fiber. The atom guide potential can be produced when the optical fiber carries a red-detuned light with TE01 mode and a blue-detuned light with HEll mode, and the 1D optical lattice potential can be produced when the red-detuned light is transformed to the superposition of the TE01 mode and HE11 mode. The two trapping potentials can be transformed to each other for accurately controlling mode transformation for the red-detuned light. This might provide a new approach to realize flexible transition between the guiding and trapping states of atoms.     

175-W continuous-wave master oscillator power amplifier structure ytterbium-doped all-fiber laser

We report on hundred watts range ytterbium-doped all-fiber laser assembly based on the master oscillator power amplifier structure. It consisted of an oscillator and an amplifier with all-fiber components. And fiber fusion splice made the laser be an integrated fiber system. It generated up to 175.5 W of continuouswave (CW) output power at 1085 nm with more than 75% extraction efficiency in the amplifier when the total coupled pump power into the double clad fiber was 270 W.     

CsNiCl3晶体的光谱精细结构、零场分裂参量及Jahn-Teller效应

应用不可约张量理论构造了三角对称晶场中3d²/3d⁸态离子的45阶可完全对角化的微扰哈密顿矩阵，研究了CsNiCl₃晶体的光谱精细结构、晶体结构、零场分裂参量、Jahn-Telller效应以及自旋单重态对Ni²⁺离子基态能级的影响，理论与实验相符合.在此基础上，进一步研究了以前工作中被忽略的自旋-自旋耦合作用和Trees修正对CsNiCl₃晶体的光谱精细结构和零场分裂参量的影响，发现有四种机理会影响零场分裂参量：1)自旋-轨道耦合机理，2)自旋-自旋耦合机理；3)自旋-轨道与自旋-自旋联合耦合机理；4)自旋-轨道与Trees修正联合耦合机理，其中自旋-轨道耦合机理是最主要的，其他三种机理也是不可忽略的. 关键词： 基态能级 精细结构 零场分裂 自旋-自旋耦合     

Synchronization of different chaotic systems via active radial basis functions sliding mode controller

This paper presents a new method to synchronize different chaotic systems with disturbances via an active radial basis function （RBF） sliding controller. This method incorporates the advantages of active control, neural network and sliding mode control. The main part of the controller is given based on the output of the RBF neural networks and the weights of these single layer networks are tuned on-line based on the sliding mode reaching law. Only several radial basis functions are required for this controller which takes the sliding mode variable as the only input. The proposed controller can make the synchronization error converge to zero quickly and can overcome external disturbances. Analysis of the stability for the controller is carried out based on the Lyapunov stability theorem. Finally, five examples are given to illustrate the robustness and effectiveness of the proposed synchronization control strategy.     

Versatile Nitro-Fluorophore as Highly Effective Sensor for Hypoxic Tumor Cells: Design, Imaging and Evaluation

Based on the characteristics of a nitro-group, which can be partially or totally reduced to an amino-group in hypoxic cells, two series of hypoxic sensors containing 7H-Benzimidazole [2,1-a]benz[de]isoquinolin-7-one cores with nitro groups in different positions were designed, synthesized and evaluated. The target compounds exhibited significantly different fluorescence characteristics (fluorescence enhancement or quenching). The strong fluorescences of some partially reduced compounds could be explained through the examination of their infrared spectra, which showed a restriction of the nitro-group vibration. These compounds exhibited significant hypoxic–oxic fluorescence differences not only in numerical values but also in their fluorescent imaging properties as reported for the first time.      

First-principles study on electronic structures of BaWO4 crystals containing F-type color centers

The electronic structures of BaWO₄ crystals containing F-type color centers are studied within the framework of the fully relativistic self-consistent Dirac-Slater theory, using a numerically discrete variational (DV-Xα) method. It is concluded that F and F⁺ color centers have donor energy level in the forbidden band. The optical transition energies are 2.449 and 3.101 eV, which correspond to the 507 and 400 nm absorption bands, respectively. It is predicted that 400-550 nm absorption bands originate from the F and F⁺ color centers in BaWO₄ crystals.     

A neat semi-Gaussian laser beam with no diffraction fringes: Theoretical analysis

We propose a simple optical device to convert a Gaussian laser beam into a neat semi-Gaussian laser beam without any diffraction fringe by using a spatial light modulator and a thin, sharp blade, and numerically calculate the diffracted, relative intensity distributions of both the semi-Gaussian laser field and the semi-Gaussian, pseudo-thermal light. We also study the dependence of the border width of the semi-Gaussian beam on the waist of the Gaussian beam. Our study shows that the proposed scheme can be used to cancel all diffraction fringes from both the straight edge of the blade and a finite lens aperture in all the planes vertical to the z axis and obtain a neat semi-Gaussian beam without any diffraction fringe, and find that the border width w_B of the generated semi-Gaussian beam is not dependent on the waist of the incident Gaussian beam.     

Statistical properties of thermal radiation in a Kerr nonlinear blackbody

We study the statistical properties of thermal radiation in a Kerr nonlinear blackbody in which bare photons with opposite wave vectors and helities are bound into pairs and unpaired photons are transformed into a different kind of quasiparticle, the nonpolariton. This paper investigates the statistical properties of the photon blackbody field by using the second-order correlation function, the phase space distribution function, the photon number distribution and the nonclassical depth. The numerical computation and a discussion of the results are present.