[en] We report for the first time (to our knowledge) a quasi-three-level Nd:Sr₃Ga₂Ge₄O₁₄ (Nd:SGG) laser emitting at 902 nm. An end-pumped Nd:SGG crystal yielded 718 mW of continuous-wave (CW) output power for 17.9 W of incident pump power. Intracavity second-harmonic generation (SHG) in CW mode has also been demonstrated with a power of 116 mW at 451 nm by using a LiB₃O₅ (LBO) nonlinear crystal. The blue beam quality factor M² was less than 1.27. The green power stability was less 5.3% in 4 hour

[en] We report a coherent blue-green radiation at 497 nm by self-sum-frequency generation of the 936 and 1060 nm laser-lines of the Nd:YCa₄O(BO₃)₃ (Nd:YCOB) crystal. With a diode pump power of 14.3 W, the maximum blue-green output power of 75 mW is obtained. The beam quality M² value is 1.22 in both horizontal and vertical dimensions. The output power stability over 30 min is better than 4.1%. To the best of our knowledge, this is first work on self-sum-frequency generation of a diode pumped Nd:YCOB laser at 497 nm

[en] To improve the powder convergence and cladding layer quality, the three-dimensional axisymmetrical powder flow through a coaxial feeding nozzle was simulated by the Eulerian-Eulerian two-fluid model. With the composite design via the response surface method, the significance between the main geometric dimensions of nozzle and fluidization characteristics of powder flow was analyzed and regression-fitted. Moreover, a mathematical model was constructed to optimize the nozzle structure, and the optimal nozzle was used in laser cladding experiments. The results show that appropriate powder flow can be obtained in the condition of the carrier gas more than 9 l/min, and the powder sending rate less than 7.5 g/min. The structural parameters of the optimized nozzle are as follows: nozzle angle of 62.94°, outlet width of 1.0mm, exit radius of 5.83mm, and flow separation angle of 3.00°. With the optimized nozzle, the waist diameter and focus depth of the original powder flow decreased by 39.4 and 46.4%, respectively, and the discrepancy between the experimental and simulation results was less than 9%. With the appropriate technological parameters, a layer with good geometry morphology and appropriate dilution rate can be prepared in the laser cladding process with a coaxial feeding nozzle. (paper)

[en] We report for the first time a Nd:LuVO₄ laser operating in a continuous wave (CW) on the true three-level laser at 880 nm, based on the ⁴F_3/2 – ⁴I_9/2 transition. CW 345 mW output power at 880 nm is obtained under 18.2 W of incident pump power. Moreover, the intracavity second-harmonic generation (SHG) has also been achieved with a blue power of 37 mW by using a LiB₃O₅ (LBO) nonlinear crystal

[en] A diode pumped Yb:CaNb₂O₆ (Yb:CN) laser at 1082 nm with a maximum output of 1.35 W at 13.3 W pump power has been demonstrated. The slope efficiency was 12.4%. Moreover, intracavity second-harmonic generation (SHG) has also been achieved with a maximum green power of 374 mW by using a LiB₃O₅ (LBO) nonlinear crystal. To the best of our knowledge, this is the first report on continuous wave (CW) green generation by intracavity frequency doubling Yb:CN laser

[en] We describe the output performances of the 1.35 μm ⁴F_3/2 → ⁴I_13/2 transition in Nd-doped Sr₃Ga₂Ge₄O₁₄ (SGG) under in-band pumping with diode lasers at the 879 nm wavelength, directly into the ⁴F_3/2 emitting level. An end-pumped Nd:SGG crystal yielded 7.1 W of continuous-wave (CW) output power for 17.7 W of absorbed pump power. The slope efficiency with respect to the absorbed pump power was 47.7%. To the best of our knowledge this is the first demonstration of such a laser system. Comparative results obtained for the pump with diode laser at 806 nm, into the highly-absorbing ⁴F_5/2 level, are given in order to prove the advantages of the in-band pumping

[en] In recent years, conductive composites have been attracted more attentions, but their applications and developments are restricted by the deficiency of the research on conductive mechanism. The electrical conductivity and percolation threshold of silica (SiO₂) matrix with different particle sizes using polypyrrole nanowires (PPy-NWs) as fillers are experimentally investigated. The results show that the electrical properties of PPy-NWs/SiO₂ composites typically exhibit a non-linear percolation behavior. PPy-NWs/SiO₂ (30 nm) nanocomposites need more filler content to achieve percolation threshold compared to that of PPy-NWs/SiO₂ composites with 2 µm SiO₂ particles as matrix. The conductive behavior of these composites is the result of the interaction and competition of various conductive mechanisms. The difference in electrical properties of PPy-NWs/SiO₂ composites with different particle size SiO₂ as matrix is attributed to the effect of matrix size on tunnelling conduction and the establishment of conductive pathways. Moreover, a two-dimensional conductive network model filled with PPy-NWs and an effective electrical resistivity model of PPy-NWs/SiO₂ composites were established. The simulation models can reflect the electrical properties of conductive composites, and are well agreement with the experimental data. (paper)

[en] Chitosan has been investigated as a non-viral vector because it has several advantages such as biocompatibility, biodegradability and low toxicity with high cationic potential. However, the low specificity and low transfection efficiency of chitosan need to be solved prior to clinical application. In this paper, we focused on the galactose or mannose ligand modification of chitosan for enhancement of cell specificity and transfection efficiency via receptor-mediated endocytosis in vitro and in vivo

[en] The size of Earth's field angle is one of the most important parameters of Earth simulator. At present, this parameter can only be calculated by the way of optical calculation, and can not be tested exactly. Infrared detecting and optical modulation technique are introduced in the paper to demarcate the Earth's field angle. The field angle demarcating system's elements, general structure and measuring principle are all analyzed detailed in the paper. The small field infrared detector, the key element for demarcating field angle is discussed and analyzed theoretically and experimentally, and it can be seen from the experimental results that the Earth's field size and shape is 0.41⁰x0.49⁰ and ellipse respectively