Simultaneous chromatic dispersion monitoring,extinction ratio enhancement and wavelength conversion using four-wave mixing

This paper presents a multi-functional all-optical device performs simultaneous chromatic dispersion (CD) monitoring, extinction ratio (ER) improvement and tunable wavelength conversion using four-wave mixing (FWM) in a single piece of highly nonlinear optical fiber (HNLF). The multi-functional ability arises from the nonlinear power transfer function (PTF) between the input signal and the output idler wave, which not only maps the CD information of the signal onto the average power of idler wave, but also transfers the data information to the idler wave with ER enhancement, making the device compact and cost effective. Furthermore within the wavelength tuning range the monitoring sensitivity and output ER can be much higher compared to all optical monitors and regenerators proposed before. Numerical simulations are then used to demonstrate the efficiency of this method.     

Preparation of Nd-doped BiFeO3 films and their electrical properties

The Nd-doped BiFeO₃ thin films were prepared on SnO₂(FTO) substrates spin-coated by the sol–gel method using Nd(NO₃)₃·6H₂O, Fe(NO₃)₃·9H₂O and Bi(NO₃)₃·5H₂O as raw materials. The microstructure and electric properties of the BiFeO₃ thin films were characterized and tested. The results indicate that the diffraction peak of the Nd-doped BiFeO₃ films is shifted towards right as the doping amounts are increased. The structure is transformed from the rhombohedral to pseudotetragonal phase. The crystal grain is changed from an elliptical to irregular polyhedron. Structure transition occurring in the Bi_0.85Nd_0.15FeO₃ films gives rise to the largest Pr of 64 μC/cm². The leakage conductance of the Nd doped thin films is reduced. The dielectric constant and dielectric loss of Bi_0.85Nd_0.15FeO₃ thin film at 10 kHz are 190 and 0.017 respectively.     

西北旱田黄土对Pb(Ⅱ)和氯吡硫磷复合污染的共吸附机制研究

通过静态批次实验研究旱田黄土对Pb(Ⅱ)和氯吡硫磷的共吸附行为,使用SEM,FTIR,XRD和理论分析揭示共吸附机制。实验结果发现:黄土对Pb(Ⅱ)和氯吡硫磷的共吸附符合Langmuir等温线方程,经计算得出的理论吸附容量qm分别为12.5和0.64mg.g-1,准二级动力学方程能更好地描述反应行为。吸附反应后,黄土表面形貌变化很小,FTIR图谱中的某些波峰红移、消失或强度减弱,综合XRD图谱及理论分析,认为:旱田黄土对Pb(Ⅱ)的吸附为表面配位络合和范德华力的作用,以化学吸附为主;而氯吡硫磷的去除涉及到黄土有机质对氯吡硫磷大分子的截留作用,以及氢键、范德华力的作用,以物理吸附为主,兼有化学吸附的贡献。旱田黄土有机质对Pb(Ⅱ)和氯吡硫磷的吸附有重要贡献。     

Influence of TiO2 impregnated with a novel copper(II) carboxylic porphyrin and its application in photocatalytic degradation of 4-Nitrophenol

A novel 5,15-di-[4-carboxylatomethoxy]phenyl-10,20-diphenylporphyrin, its copper complex and the corresponding metalloporphyrin-TiO₂ photocatalyst were synthesized and characterized by DRS, SEM, XRD, and FT–IR. The photocatalytic effects of anataseTiO₂ impregnated with this copper(II) porphyrin was investigated by photodegradation of 4-nitrophenol(4-NP) in aqueous solution under Xenon lamp irradiation. The results indicated that the photoactivity of copper(II) porphyrin-TiO₂ composite was evidently enhanced by the interaction between carboxyl of the porphyrin molecule and hydroxyls anchored on the TiO₂. Futhermore, the copper(II) carboxylic porphyrin displayed good adsorption behavior and activity of the dye-sensized TiO₂ system.     

Radiation-induced destruction of hydroxyl-containing amino acids and dipeptides

The yields of molecular products resulting from radiolysis of hydroxyl-containing amino acids and dipeptides under various conditions were determined. The possibility of a new radiation-induced destruction pathway has been shown for serine and threonine, as well as for the dipeptides having residues of these amino acids at the N-terminal part of the respective molecule. This process includes formation of N-centered radicals from the starting molecules followed by their decomposition with elimination of side substituents. On radiolysis, serine and threonine were also shown to undergo free-radical destruction to form acetaldehyde and acetone, respectively. A mechanism has been proposed including consecutive stages of fragmentation of α-hydroxyl-containing carbon-centered radicals with elimination of ammonia and decomposition of the secondary radicals with elimination of CO₂. The yields of CO₂ obtained on radiolysis of serine and threonine were significantly higher (except for solutions at pH 12) than those for alanine and valine, which have no hydroxyl groups in their structures. The obtained data indicate that the hydroxyl-containing amino acids occupy a special place among other amino acids as regards the variety of radiation-induced reactions which they may undergo due to their structural features.     

微波水热温度对合成Bi2MoO6微晶形貌和光学性能的影响

以硝酸铋和钼酸钠为起始原料,采用微波水热法制备了片状的Bi2MoO6微晶。利用X射线衍射仪(XRD)、透射电子显微镜(TEM)和紫外-可见吸收光谱(UV-vis)分别对产物的物相组成、形貌和光学性能进行分析。结果表明:随着微波水热温度的升高,衍射峰的强度增强,产物的结晶程度逐渐提高,晶粒尺寸逐渐增大,Bi2MoO6微晶由不规则的形状转变成规则的片状结构;紫外-可见吸收光谱分析表明,Bi2MoO6微晶在紫外光区具有优异的吸收性能,且随微波水热温度的降低,其吸收边出现略微蓝移,禁带宽度逐渐增大。