Synthesis and spectroscopic characterization of cobalt porphyrins and their catalytic activity towards dioxygen reduction

The synthesis and spectroscopic characterization of cobalt(Ⅱ) 5-(4-pyridyl)-10,15,20-triphe-nylporphyrin,cobalt(Ⅱ) 5-(4-N-hexadecylpyridiniumyl)-10,15,20-triphenylporphyrin bromide andcobalt(Ⅱ) 5-(2-aminophenyl)-10,15,20-triphenyl-porphyrin are reported.The corresponding copperand vanadyl derivatives ((TriP)Cu,[(hTriP)Cu]~+Br~- and [(hTriP)VO]~+Br~-) were also studied.Eachmetalloporphyrin was characterized by UV-visible,ESR and ~1H NMR spectroscopy.These me-talloporphyrins can be firmly adsorbed on the glassy carbon (GC) surface.The catalytic reduction ofdioxygen at GC electrodes modified by these catalysts was studied by cyclic voltammetry (CV).Thekinetic process of dioxygen reduction at the cobalt porphyrin-modified electrodes was studied with arotating ring disk electrode.     

大规模无约束优化的一族LBFGS类算法

尝试在有限存储类算法中利用目标函数值所提供的信息.首先利用插值条件构造了一个新的二次函数逼近目标函数,得到了一个新的弱割线方程,然后将此弱割线方程与袁[1]的弱割线方程相结合,给出了一族包括标准LBFGS的有限存储BFGS类算法,证明了这族算法的收敛性.从标准试验函数库CUTE中选择试验函数进行了数值试验,试验结果表明...     

A general solution for one dimensional chemo-mechanical coupled hydrogel rod

Smart hydrogels are environmentally sensitive hydrogels, which can produce a sensitive response to external stimuli, and often exhibit the characteristics of multi filed coupling. In this paper, a hydrogel rod under chemo-mechanical coupling was analytically studied based on a poroelastical model. The already known constitutive and governing equations were simplified into the one dimensional case, then two different boundary conditions were considered. The expressions of concentration, displacement, chemical potential and stress related to time were obtained in a series form. Examples illustrate the interaction mechanism of chemical and mechanical effect. It was found that there was a balance state in the diffusion of concentration and the diffusion process could lead to the expansion or the stress change of the hydrogel rod.     

Holographic grating formation in dry photopolymer film with shrinkage

An important issue in developing applications for photopolymers in holography is the effect of shrinkage on recording properties. In this paper, we introduce a model to describe real-time formation of a single grating in photopolymers at any geometrical angle, under the assumption that the shrinkage is in proportion to the polymerization. This model combines polymerization kinetics with the coupled-wave theory, explaining the shrinkage effect on the diffraction efficiency. The model is validated by comparing its predictions with the experimental results for a film of 99μm thickness.     

三方和四方相PbZr0.5Ti0.5O3 的结构稳定性和电子结构的第一性原理研究

采用基于密度泛函理论的第一性原理超原胞方法和虚晶近似方法, 在局域密度近似和广义梯度近似下系统研究了三方相和四方相 PbZr_0.5Ti_0.5O₃的能量稳定性、原子结构以及电子结构. 计算结果表明三方相的能量比四方相低, 说明三方相结构更加稳定, 并且发现利用广义梯度近似计算的结构参数与实验值符合得更好. 电子结构表明, 两种相的Ti/Zr的3d电子和O的2p电子间存在明显的轨道杂化, 并且Ti-O之间的作用比Zr-O作用更强;Pb的6s和5d电子与O的2s和2p电子也分别存在轨道杂化. 而三方相中Pb的5d电子与O的2s电子杂化比四方相更强, 进一步说明三方相比四方相结构更加稳定.     

Characterization of the transient species generated by the photoionization of Berberine: A laser flash photolysis study

Using 266 nm laser flash photolysis it has been demonstrated that Berberine (BBR) in aqueous solution is ionized via a mono-photonic process giving a hydrated electron, anion radical that formed by hydrated electron react with steady state of BBR, and neutral radical that formed from rapid deprotonation of the radical cation of BBR. The quantum yield of photoionization is determined to be 0.03 at room temperature with KI solution used as a reference. Furthermore utilizing pH changing method and the SO₄⁻ radical oxidation method, the assignment of radical cation of BBR was further confirmed, the pK_a value of it was calculated, and the related set up rate constant was also determined.     

基于全光时域分数阶傅里叶变换的光脉冲最小损伤传输新方法

提出了一种基于全光分数阶傅里叶变换(optical fractional fourier transformation,OFRFT)的关于色散和自相位调制对光脉冲传输影响的分析方法,并基于该方法给出了一种新的光脉冲在光纤中传输最小损伤的方法,通过在发射端将输入的高斯光脉冲做OFRFT然后再送入到光纤中去传输,可以提高光脉冲抵抗色散和非线性的能力,仿真发现当色散占主要作用的时候,负阶数的分数阶傅里叶变换可以很大程度上减小光脉冲的展宽;当自相位调制作用占主要的时候,正阶数的分数阶傅里叶变换可以消除自相位调制作 关键词： 光脉冲传输 分数阶傅里叶变换 色散 自相位调制     

Mechanism of Phenol Hydroxylation with Hydrogen Peroxide Catalyzed by Iron Complex Oxide

Dihydroxybenzene are both very important chemical products. The oxidation of phenol to produce catechol and hydroquinone has been researched extensively since the 1970s. In this paper, the iron complex oxide was prepared by the air oxidation of aqueous suspension method and the catalytic activities were investigated in the hydroxylation of phenol with H₂O₂ to catechol and hydroquinone. The results showed that the catalyst had higher catalytic activities and the phenol conversion could reach 24% when the phenol/H₂O₂ (mole ratio) was 3 and the catechol/hydroquinone (mole ratio) 1.5 in products. Furthermore, the interaction of the catalyst with H₂O₂ had also been demonstrated by IR spectrometry. In the presence of H₂O₂ a band at 956 cm^-1 appeared and disappeared when the H₂O₂ is replaced by H20 or the catalyst was heated over 373 K, at which temperature decomposition of iron peroxide was very likely. The band at 956 cm^-1 was due to the formation of structure of iron peroxide species and the stretching vibration of surface 0-0 species. The results of IR studies suggested that the catalyst might be react with hydrogen peroxide to form iron peroxide, which decomposed to produce·OOH radical. In the presence of DMPO (5,5-dimethyl-1-pyrroline-N-oxide) the·OH radical was also successfully captured in the hydroxylation of phenol by H₂O₂ over iron complex oxide catalyst in the first time that has been confirmed by means of ESR spectrometry. The results of ESR suggested the process of hydroxylation of phenol with H₂O₂ was probably a radical process. A possible mechanism of the catalytic process was proposed.     

Multivariate calibration analysis for metal porphyrin mixtures by an ant colony algorithm.

A new biomimetic algorithm, Chemical Ant Colony Algorithm, has been developed, which has the characteristics of intelligent search, global optimization, robustness, distributed computation and easy combination with other heuristic. The proposed method has been successfully applied to the spectroscopy analysis of the Zn2+, Cd2+, Pb(2+)-porphyin tribasic color system with supramolecular properties; the errors are within +/-8.0%.     

Preparation of Group IIB Selenide Nanoparticles Using Soft-Hard Dual Template Method

Using a celloidin membrane as template, the uniform Group IIB selenide nanoparticles were inductively synthesized at room temperature and ambient pressure. The nanoparticles are cubic ZnSe quantum dots, hexagonal CdSe quantum dots and cubic HgSe nanoparticles with average diameters of 3.1, 2.0 and 44nm, respectively. In the ultraviolet-visible spectra, their absorption peaks are at about 360, 480 and 440nm individually, and have large blue shifts due to quantum size effect. The corresponding photoluminescence peaks individually showed at 367, 438 and 440nm. In addition, the preparation conditions and formation mechanism have been explored.