用核磁共振氢谱法研究胸腺嘧啶与过氧化钒配合物的光照射反应

利用核磁共振氢谱的方法,研究在单线态氧的作用下,胸腺嘧啶残基(包括胸腺嘧啶(T)、胸腺嘧啶脱氧核苷(dT)和胸腺嘧啶脱氧核苷酸(TMP))的分解产物。胸腺嘧啶残基与过氧化钒配合物的光照射反应,由过氧化钒配合物光分解所产生的单线态氧使胸腺嘧啶碱基发生了光氧化反应,可能的反应产物通过核磁共振氢谱进行了测定。

Photocatalytic activity of CuO towards HER in catalyst from oxalic acid solution under simulated sunlight irradiation

CuO was synthesized by thermal decomposition of Cu(NO3)2·3H2O at various temperatures and characterized by powder X-ray diffractometry(XRD) as well as scanning electron microscopy(SEM).The effects of calcination temperature,category of sacrificial reagent,initial sacrificial reagent concentration,and Ag loading content on the photocatalytic activity of the as-obtained CuO sample were investigated.The results show that the as-obtained CuO exhibits high activity for photocatalysis of H2 evolution reaction(HER) in oxalic acid solution under simulated sunlight irradiation.The highest photocatalytic activity of the as-obtained CuO was achieved at the calcination temperature of 1000℃,and oxalic acid was used as the sacrificial reagent with the concentration 0.05 mol/L.H2 evolution rate is as high as 2.98 mmol/(h·g) with 2%(mass fraction) loaded Ag.The possible photocatalytic reaction mechanism on the CuO photocatalyst for HER in oxalic acid solution was also discussed.

Effect of microwave irradiation on secondary structure of α-amylase by circular dichroism

Based on the starch hydrolysis reaction accelerated by microwave irradiation with α-amylase, the circular dichroism （CD） and secondary structure changes of α-amylase under the condition of microwave irradiation and water bath were studied by circular dichroism spectra. The results showed that, both the peak heights （at 2=193 nm） of the CD spectra of the samples treated by microwave irradiation and water bath reduced. The reduced rate by microwave irradiation ranged from 140% to 220%, while the reduced rate by water bath ranged from 60% to 140%. The peak of the sample treated by microwave irradiation for 60 min disappeared at λ=193 nm, while the sample showed a wake peak by water bath. The peak position by microwave irradiation emerged a blue shift in the range of 5-8 nm at λ=204 nm and λ=220 nm, while it emerged in the range of 3-5 nm by water bath. With time going on, the microwave irradiation and water bath have prompted the secondary structure of α-helix, β-sheet, β-turn and the mutual transformations of random coil, but the trends were different.

Temperature Dependence of Thermal Emission Rate in Cr: GaAs

The new method of measuring the ratio of thermal emission rate to the photoexcitation constant is presented. The temperature dependence of the ratio for Cr:GaAs is calculated by using the previously published data of two-wave mixing. Results show that the calculating data and previous phenomenological theoretic ones coincide with each other very well.

Intensity Dependence of Stationary Energy Transfer in Codirectional Photorefractive Two－wave Mixing

The intensity and phase formulas that are valid for the saturation and intermediate regime (before saturation) are derived, and the analytical expressions with the ratio of saturation intensity to total incident intensity as their explicit variable are obtained. The intensity dependence of stationary energy transfer in photorefractive codirectional two-wave mixing is examined. It is necessary to using these formulas in some problems, such as the temperature or intensity dependence of two-wave mixing. A method of measuring exponential gain coefficient is presented, which is suitable for two-wave mixing in intermediate regime.

Unified Form of Photorefractive Coupling－wave Equation in the Undepleted Pump Approximate and the Lossless Solution

The coupling-wave equations of photorefractive wave mixing processes including two-and four-wave mixing are expressed as an unified matrix equation in the undepleted pump approximation.The lossless general solution of the matrix equation is obtained.The previous formulas of five wave-mixing processes in the undepleted pump are derived from the solution when their boundary conditions are used.

Metal-free direct oxidation of α-isophorone to ketoisophorone by I_2 under photoirradiation

Molecular iodine was first utilized for direct oxidation of a-isophorone （α-IP） to ketoisophorone （KIP） with molecule oxygen at room temperature and the effects of amount of iodine, solvents and reaction time were investigated extensively. The optimized result shows that 70.2% conversion of a-isophorone and 82.6% selectivity of ketoisophorone are obtained with 15% iodine （molar fraction） in acetonitrile under photoirradiation for 5 h. Moreover, the possible mechanism is proposed.

Readily accessible rhodamine B-based photoresponsive material

A photochromic rhodamine B-based material containing Cd（Ⅱ） as bridge was facilely prepared. The 4-methoxylsalicylalde hyde rhodamine B bydrazone Cd（Ⅱ） complex displayed unusual ring-open response upon 365 nm UV irradiation, exhibiting long photochromic lifetime and good fatigue resistance. The UV-induced ring-open of the complex led to a distinct color and fluorescence change in acetonitrile. A new mechanism was put forward： salicylaldehyde part in the complex underwent UV-promoted isomerization from enol-form to keto-form, enhancing the chelation of Cd（Ⅱ） and yielding the ring-opening rhodamine B part. Compared to other reported photochromic systems, this new photochromic material offered attractive new insights into the development of low cost photochromic materials with good performance.

Controllable synthesis of titania/reduced graphite oxide nanocomposites with various titania phase compositions and their photocatalytic performance

A facile method is presented for preparing TiO2/reduced graphite oxide （RGO） nanocomposites with phase-controlled TiO2 nanoparticles via redox reaction between the reductive titanium （III） precursor and graphite oxide （GO）, and a series of TiO2/RGO composites with various TiO2 phase compositions were obtained. In all the titania/RGO composites, the TiO2 nanoparticles were uniformly distributed on the surface of the RGO. The TiO2 consisted of anatase phase particles in the form of square-plates with edges less than 10 nm and the rutile phase nanorods in diameters less than 10 nm. The performances of the as-prepared TiO2/RGO composites were investigated on catalytically degrading phenol under visible light irradiation. The TiO2/RGO composites can effectively degrade phenol under visible light irradiation, and the phase composition of TiO2 in the composites significantly influences the activities of these catalysts.