Broadband dispersion compensation using microstructure fibers

Beijing University of Posts and Telecommunications, Beijing 100876Dispersion and dispersion slope compensation of 10-Gb/s pulses using microstructure fibers (MFs) is demonstrated experimentally. A 26-m MF is used to compensate the dispersion of 2-km standard singe mode fiber in a 20-nm range in C band. The experimental results show that a significant improvement can be achieved in the quality of the observed pulses with the dispersion compensation. Moreover, the further research shows that the MF can compensate the anomalous dispersion of a single mode fiber within ±0.27 ps/(nm·km) over a 50-nm wavelength range from 1520 to 1570 nm.     

Demonstration of fiber pulsed light source at 1.6 μm with adjustable pulse duration

A novel practical 1.66-μm pulse light source with adjustable pulse duration is proposed. A 2.5-km Raman fiber is placed into a ring type Q-switched erbium-doped fiber laser (Q-EDFL), serving as both delay line fiber and Raman gain medium so that in addition to the wavelength shifted to 1.6μm, the pulse duration and the buildup time can be relatively extended. By properly controlling the fall edge of the acousto-optic switch (AOS), the pulse duration of 30-345 ns for ～ 770-Hz repetition frequency with power of 1-1.6 W is achieved.     

Structural characterization and biological activity of galactoglucan from Castanea mollissima Blume

Abstract

A galactoglucan (HCPA) was extracted from C. mollissima Blume fruits using hot water, which was composed of glucose and galactose, with a molecular weight of 5.5?kDa. Methylation and 1?D, 2?D NMR spectroscopy analysis showed that HCPA contained [→4)-α-D-Glcp(1→], [→4,6)-α-D-Glcp(1→], [→4)-β-D-Galp(1→] and [α-D-Glcp(1→] motifs in a molar ratio of approximately 6.11:1.08:1.00:1.03. HCPA showed a spherical-like structure as detected by scanning electron microscope (SEM). HCPA biological activity was investigated in vitro. The results showed that HCPA inhibited the proliferation of HeLa, MCF-7 and MGC-803 cells, induced HeLa cells apoptosis and arrested cell cycle in G2/M phase of HeLa cells. HCPA also enhanced the viability and phagocytic ability of RAW 264.7 cells and stimulated the production of NO, TNF-α and IL-6. The results demonstrated that HCPA had a potent antitumor and immunomodulating effects in vitro, suggesting its potential use as functional food and drug products.     

Coderivatives of the generalized perturbation maps

This paper is devoted to considering the coderivatives of the generalized perturbation maps in general Banach spaces. Under some mild conditions, the upper estimate of coderivatives of the generalized perturbation maps are obtained. Their exact calculus rules are obtained under some additional conditions. Furthermore, the generalized perturbation maps are shown to be differentiably regular under some strong conditions.     

Smooth solutions for a stochastic hydrodynamical equation in Heisenberg paramagnet

In this article, we consider a stochastic hydrodynamical equation in Heisenberg paramagnet driven by additive noise. We prove the existence and uniqueness of smooth solutions to this equation with difference method.     

植物导水模型初探

目前世界上对于植物长距离水分运输的微观机理假说存在争论。据此本文初步讨论了植物的导水模型。从流体力学角度讨论了水分在植物体内的运动状态,得出导管中的水分流动是在层流的状态下进行,且必须考虑粘性的作用;通过分析流体的层流运动,建立了导管中一维的流体模型,并简化导管以连续的梯形圆柱排列;分析受力,列出N-S方程,并求解出了一维导管模型的半径与压力梯度和各节管长的关系表达式。研究结果表明,模型中每一节导管的水受力都是平衡的,且各节之间相互独立。     

(HAlNH)n(n=2～3)环状化合物的结构特征

用自洽场理论 (HF)和密度泛函理论 (DFT)的B3LYP方法 ,在 6 31G 的水平上对化合物(HAlNH) 2 和 (HAlNH) 3 的几何结构进行优化 ,并分别与环丁二烯C4 H4 和苯分子C6H6的结构和成键方式进行比较。以B3LYP STO 3G方法讨论其分子轨道波函数 (Ψ)。结果表明 :C4 H4 和 (HAlNH) 2 均为D2h对称 ,前者为长方形结构 ,形成两个孤立的π键 ;而后者为菱形结构 ,形成一个π44键。C6H6和 (HAlNH) 3分子点群分别为D6h和D3h,并均形成一个π66键。成键原子对分子轨道的贡献不同 ,其中C原子是完全等价的 ,而Al和N原子各不相同 ,N原子比Al的贡献要大得多     

K3PO4 promoted dipolar [3+3] cyclization: Direct synthesis of pyrazino[2,1-a]isoquinoline derivatives

A K₃PO₄ promoted dipolar [3+3] cyclization of dihydroisoquinoline imines and arylacyl bromides has been developed. This process realized the direct synthesis of pyrazino[2,1-a]isoquinoline derivatives in 44–69% yields. A head to tail dimerization was proposed as key step for this procedure.