Two-dimensional tellurium saturable absorber for ultrafast solid-state laser

Two-dimensional(2 D) Te nanosheets were successfully fabricated through the liquid-phase exfoliation(LPE) method. The nonlinear optical properties of 2 D Te nanosheets were studied by the open-aperture Z-scan technique. Furthermore, the continuous wave mode-locked Nd:YVO_4 laser was successfully realized by using 2 D Te as a saturable absorber(SA) for the first time, to the best of our knowledge. Ultrashort pulses as short as 5.8 ps were obtained at 1064.3 nm with an output power of 851 m W. This primary investigation indicates that the 2 D Te SA is a promising photonic device in the fields of ultrafast solid-state lasers.     

High-power continuous-wave operation of a diode-pumped laser at

The continuous-wave laser properties of an efficient diode-pumped Nd:GdVO₄ crystal operating at formed with a simple plane-concave cavity have been studied. With the incident pump power of 21 W, an output power of 6.9 W was obtained, giving an optical conversion efficiency of 32.8% and a slope efficiency of 35.3%. The laser characterization of two different Nd³⁺-doped concentration of Nd:GdVO₄ crystals were studied.     

Purification and Characterization of Hyaluronate Lyase from <Emphasis Type="Italic">Arthrobacter globiformis</Emphasis> A152

A hyaluronate lyase was obtained by cultivating Arthrobacter globiformis strain A152. The enzyme was purified to homogeneity from the supernatant by ammonium sulfate fractionation, Q Sepharose Fast Flow, and Sephadex G-100 chromatography. The purification resulted in a 32.78-fold increase in hyaluronate lyase activity with specific activity of 297.2 U/mg. The molecular weight of the enzyme determined by SDS-PAGE was approximately 73.7 kDa. Using hyaluronic acid (HA) as a substrate, the maximal reaction rate (V_max) and the Michaelis–Menten constant (K_m) of hyaluronate lyase were found to be 4.76 μmol/min/ml and 0.11 mg/ml, respectively. The optimum pH and temperature values for hyaluronate lyase activity were pH 6.0 and 42 °C, respectively. This enzyme was stable at pH 4–10, 5–7, and 5–7 at 4, 37, and 42 °C, respectively. Investigation about temperature effects on hyaluronate lyase displayed that it was stable at 30–37 °C and also showed high activity at 37 °C. The enzymatic activity was enhanced by Ca²⁺ and was strongly inhibited by Cu²⁺ and SDS. These properties suggested that the hyaluronate lyase in this study could bring promising prospects in medical and industry applications.     

由杉木锯屑生物质制合成气:镍基整体式催化剂的表征及催化性能

以酸处理的蜂窝状堇青石为载体制得了一系列用于生物质热解气制合成气的不同NiO负载量的整体式催化剂,考察了该Ni基催化剂的催化性能.结果表明,酸处理后堇青石载体的比表面积和孔容分别可达156m2/g和0.099m3/g;NiO的负载使得比表面积和孔容急剧减小,并随着NiO负载量的增加而变化不大.NiO负载量对产气组分的影...     

Dynamical properties of a stochastic predator-prey model with functional response

A stochastic prey-predator model with functional response is investigated in this paper. A complete threshold analysis of coexistence and extinction is obtained. Moreover, we point out that the stochastic predator-prey model undergoes a stochastic Hopf bifurcation from the viewpoint of numerical simulations. Some numerical simulations are carried out to support our results.     

曲率限制的红外焦平面告警系统目标搜索算法

为了降低红外焦平面告警系统中较高的虚警率,提出了一种速度限制基础上基于曲率限制的目标搜索算法。以视场角5.34.0凝视型红外告警系统为例,在MATLAB中对红外图像序列进行了目标搜索实验,验证了该算法的可行性。按照蒙特卡罗法思路模拟了包含大量随机噪声的目标场景,研究了该算法相比传统多帧检测算法对随机噪声的抗干扰性。对该算法的搜索帧数进行了扩展,给出了不同搜索帧数的搜索效果和时效性表现。     

Nonlinear compressed sensing-based adaptive modal shapes selection approach for efficient dynamic response analysis of flexible multibody system

Nonlinear Dynamics - The modal truncation is usually used in the dynamic response analysis of flexible multibody systems, in which, appropriate selection of modal shapes is very critical to achieve...     

An efficient and general approach to beta-functionalized ketones

[structure: see text]. The oxidation of selected anions (N3-, SCN-, I-, and Br-) by ceric ammonium nitrate (CAN) in the presence of substituted cyclopropyl alcohols provides a novel approach to beta-functionalized ketones. The protocol has a number of advantages including short reaction times, ease of reagent handling, and mild, neutral reaction conditions. Overall, this method provides an alternative pathway to important starting materials and intermediates in organic synthesis.     

固定化酶的反应扩散过程的靶波解

通过固定化酶的数学模型的数值模拟,发现其反应扩散过程是以靶波形式出现的。