A new characteristic index of chaos

In this paper, k step chaometry (k SCM) is defined based on monopolized sphere and instantaneous chaometry (ICM), and the convergent theorem of asymptotical periodic orbit is also proved. The 400 SCM of the discrete model of Lorenz system is calculated and results disclose that 400 SCM can clearly identify the parameters of chaotic dynamic system. The EEG instrument is applied to measure time series of EEG, and it is observed that the instantaneous chaometry of the EEG and the data generated from Lorenz attractor produce similar results.     

Normal forms for NFDEs with parameters and application to the lossless transmission line

A method for the computation of normal forms for neutral functional differential equations (NFDEs) with parameters is developed by considering an extension of phase space, based on the method of computing normal forms for FDEs with parameters previously introduced by Faria. The Hopf bifurcation of the differential difference equation is considered as an example of a circuit involving a lossless transmission line. The direction and stability of the bifurcating periodic solutions are also determined. Finally, numerical simulations are carried out to support the analytic results. This research is supported by the NNSF of China.     

生物质石墨烯/LaFeO3纳米复合材料的光催化活性

采用两步法制备生物质石墨烯/LaFeO3纳米复合材料(石墨烯加入量分别为LaFeO3的1;、3;、5;、7;),应用差热-热重分析、X射线衍射(XRD)、扫描电子显微镜(SEM)等测试手段对生物质石墨烯/LaFeO3纳米复合材料样品的物相及微观结构进行了表征;采用傅里叶变换红外光谱仪对样品进行了红外分析(FTIR);研究了生物质石墨烯加入量对生物质石墨烯/LaFeO3复合材料降解亚甲基蓝光催化降解率的影响.结果 表明:通过两步法所制备的生物质石墨烯/LaFeO3纳米光催化剂稳定性好,具有高效光催化活性;生物质石墨烯的加入提高了LaFeO3对亚甲基蓝的光催化降解率;采用175W荧光高压汞灯光照30 min时,加入7;生物质石墨烯的LaFeO3样品对亚甲基蓝的光催化降解率最高达到56;,比纯LaFeO3光催化降解率高出50;.     

Defect of nanocrystalline copper and silver

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Photosensitized degradation of dyes in polyoxometalate solutions versus TiO2 dispersions under visible-light irradiation: mechanistic implications

This article examines the photoxidation of a dye (rhodamine-B, RhB) by visible-light irradiation in the presence of a polyoxometalate (12-tungstosilicic acid, H(4)SiW(12)O(40)), and compares it with the analogous process in the presence of TiO(2). The photoreaction processes were examined by UV-visible spectroscopy, fluorescence spectroscopy, high-performance liquid chromatography (HPLC), liquid chromatography/mass spectral techniques (LC-MS), and total organic carbon (TOC) assays in order to identify the intermediates produced. Formation of oxygen species, such as H(2)O(2) and O(2)*-, was also investigated to clarify the details of the reaction pathway. With the use of SiW(12)O(40)(4-) ions as the photocatalyst, the photoreaction leads mainly to N-dealkylation of the chromophore skeleton. In contrast, cleavage of the whole conjugated chromophore structure predominates in the presence of TiO(2). Strong O(2)*-/HO(2)*- ESR signals were detected in the TiO(2) dispersions, whereas only weak ESR signals for the O(2)*- radical ion were seen in the SiW(12)O(40)(4-) solutions during the irradiation period. Experimental results imply that reduction of O(2) occurs by different pathways in the two photocatalytic systems.     

Mechanistic Studies of TiO2 Photocatalysis and Fenton Degradation of Hydrophobic Aromatic Pollutants in Water

HO–adduct radicals have been investigated and confirmed as the common initial intermediates in TiO₂ photocatalysis and Fenton degradations of water‐insoluble aromatics. However, the evolution of HO–adduct radicals to phenols has not been completely clarified. When 4‐d‐toluene and p‐xylene were degraded by TiO₂ photocatalysis and Fenton reactions, respectively, a portion of the 4‐deuterium or 4‐CH₃ group (18–100 %) at the attacked ipso position shifted to the adjacent position of the ring in the formed phenols (NIH shift; NIH is short for the National Institutes of Health, to honor the place where this phenomenon was first discovered). The results, combined with the observation of a key dienyl cationic intermediate by in situ attenuated total reflectance FTIR spectroscopy, indicate that, for the evolution of HO–adduct radicals, a mixed mechanism of both the carbocation intermediate pathway and O₂‐capturing pathway occurs in both aqueous TiO₂ photocatalysis and aqueous Fenton reactions.     

制备高活性纳米零价铁的甘露醇改性机理

纳米零价铁(Nano zero-valent iron,nZVI)被广泛应用于水污染治理,高纯度且分散性良好的nZVI的制备方法一直是研究热点.本文采用含不同羟基数目的醇(乙醇、乙二醇、赤藓糖醇、甘露醇和山梨醇)作为改性剂,分别制备得到n ZVI-EA,nZVI-EG,nZVI-ER,nZVI-M和nZVI-S样品.将上述样品应用于水中微囊藻毒素(Microcystin-LR,MC-LR)的还原去除.结果表明,随着改性剂羟基数目的增多,改性nZVI的抗氧化能力和分散性增强,对MC-LR的降解反应速率也随之提高.nZVI-M去除MC-LR的表面积校正特征速率常数(79.35×10^-5L·m^?2·min^?1)是nZVI-S(8.55×10^-5 L·m^?2·min^?1)的9.3倍,是未改性样品nZVI₀(1.30×10^-5 L·m^?2·min^?1)的61.0倍.通过X射线衍射...     

Efficient degradation of dye pollutants using dioxygen mediated by iron(II) 2,2′-bipyridine loaded layered clay catalyst under visible irradiation

The organic-inorganic layered solid catalyst Fe(bpy) ₃ ²⁺ -laponite was able to photode-grade Rhodamine B (RhB) by activation of dioxygen under visible irradiation (λ> 420 nm), while the homogeneous aqueous solution Fe(bpy) ₃ ²⁺ showed no photoactivity. The catalyst could be repeatedly used and retained its reactivity. The hybrid catalyst could be separated from the suspension by centrifugation or sedimentation. The TOC removal yield of RhB was measured. Reactive oxygen species (ROS) formed during degradation was detected by EPR. A possible mechanism was proposed on the basis of the experimental results.     

Efficient degradation of dye pollutants using dioxygen mediated by iron(Ⅱ) 2,2′-bipyridine loaded layered clay catalyst under visible irradiation

The organic-inorganic layered solid catalyst Fe(bpy)32 -laponite was able to photode-grade Rhodamine B (RhB) by activation of dioxygen under visible irradiation (λ> 420 nm), while the homogeneous aqueous solution Fe(bpy)32 showed no photoactivity. The catalyst could be repeat-edly used and retained its reactivity. The hybrid catalyst could be separated from the suspension by centrifugation or sedimentation. The TOC removal yield of RhB was measured. Reactive oxygen species (ROS) formed during degradation was detected by EPR. A possible mechanism was pro-posed on the basis of the experimental results.