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31.
Organic nanocrystals of 1,3,5-triphenyl-2-pyrazoline(TPP) with a series of sizes were synthesized by reprecipitation method.The luminescence quantum efficiency of TPP nanocrystals increases from 24.2% for the nanocrystals with an average size of 300nm to 34.6% for those with an average size of 20nm.Surface capping by polyvinyl pyrrolidone(PVP) will improve the quantum efficiency of TPP nanocrystals.The size-dependence and capping-induced variation of the luminescence quantum efficiency was elucidated in viewpoint of aggregation quenching and the equilibrium between the TPP monomers and the aggregates in TPP nanocrystals. 相似文献
32.
Xiaoxiong Xu Zhaoyin Wen Zhonghua Gu Xiaohe Xu Zuxiang Lin 《Electrochemistry communications》2004,6(12):342
Li2O–Cr2O3–GeO2–P2O5 based glasses were synthesized by a conventional melt-quenching method and successfully converted into glass-ceramics through heat treatment. Experimental results of DTA, XRD, ac impedance techniques and FESEM indicated that Li1.4Cr0.4Ge1.6(PO4)3 glass-ceramics treated at 900 °C for 12 h in the Li1 + xCrxGe2 − x(PO4)3 (x = 0–0.8) system exhibited the best glass stability against crystallization and the highest ambient conductivity value of 6.81 × 10−4 S/cm with an activation energy as low as 26.9 kJ/mol. In addition, the Li1.4Cr0.4Ge1.6(PO4)3 glass-ceramics displayed good chemical stability against lithium metal at room temperature. The good thermal and chemical stability, excellent conducting property, easy preparation and low cost make it promising to be used as solid-state electrolytes for all-solid-state lithium batteries. 相似文献
33.
Zhonghua Ji Jingjian Li Gu Yuan Shengmin Cai Jia Liu Chang Liu 《Journal of Electroanalytical Chemistry》2004,570(2):265-273
Polyamides containing N-methyl pyrroles and N-methyl imidazoles are a type of small molecule that can bind and recognize the bases of DNA with high affinity and specificity. Five polyamides were studied at glassy carbon electrode in acetate buffer by cyclic and differential pulse voltammetry to clarify their redox pathways. The polyamide electrochemical responses are compared by peak currents and peak potentials. The slopes of the three anodic Ep vs. pH plots of a typical polyamide are linear and show 0.059, 0.057, 0.056 V per pH in acid media, respectively, which correspond to a mechanism involving the equal number of electrons and protons. A possible mechanism for the redox pathway of various polyamides is proposed: the oxidation product of imidazole ring is acylamide and the results of in situ UV–Vis spectroscopy at Pt web electrode support the proposed mechanism. electrospray ionization mass spectroscopy (ESI-MS) indicates that one or two oxygen atoms are added into polyamide molecule after electrochemical oxidation. 相似文献
34.
The components of the rock, the pigments, the gold foils and the adhesive of One Thousand Hand Buddha in Dazu stone sculptures, Chongqing, China, have been analyzed by X-ray diffraction (XRD), X-ray fluorescence (XRF), infrared spectroscopy (IR), energy dispersive X-ray analysis (EDX) and fiber optics reflectance spectroscopy (FORS). Furthermore, the weathering and degeneration of One Thousand Hand Buddha have been discussed and the protective methods have been provided. In this work some useful information to study on conservation of stone relics is given. 相似文献
35.
A new separation matrix, consisting of polymer poly(N-isopropylacrylamide) (PNIPAM) and small molecule additive mannitol, was used for double-stranded (ds) DNA and plasmid DNA separation by capillary electrophoresis. The matrix had a low viscosity, which made it very easy to handle. The additive mannitol dramatically enhanced the sieving performance of PNIPAM in TBE buffer. The optimal mannitol concentration 6% in polymer solution, was determined with the consideration of both speed and resolution. A resolution of 0.95 was achieved on the separation of 271/281 bp in the phiX174/HaeIII digest by using 1.5% PNIPAM + 6% mannitol, while the supercoiled, linear and nicked conformers of lambda plasmid were separated in 1% PNIPAM + 6% mannitol, demonstrating the potential use of this new matrix for effective DNA separations. The dramatic impact of mannitol on sieving performance of PNIPAM solution was investigated. pH dependent self-coating ability of PNIPAM was revealed. The presence of mannitol in TBE buffer decreased the pH of the buffer, which led to more efficient self-coating ability of PNIPAM probable due to the formation of hydrogen bonds between PNIPAM molecules and silanol groups at the silica wall. 相似文献
36.
1INTRODUCTION Over the past decades,olefin oligomerization and polymerization based on late transition metal catalysts have been the most exciting developments in the area of organometallic chemistry and polymer science[1~3].In this broad context,neutral nickel(II)complexes have attracted much attention for their less sensitivity to protonic solvents and polar mon-mers.The most typical one is the SHOP-type cata-lyst[4~6],which contains an anionic[P,O]chelate ring and shows high activ… 相似文献
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表面修饰的二氧化锡纳米粒子的制备及微结构表征 总被引:11,自引:0,他引:11
采用胶体化学制得表面包覆有DBS的二氧化锡纳米粒子,并运用一系列手段对其微结构进行了表征。 相似文献
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40.
通过对溶剂热“一锅法”合成中碱性溶剂的调整,成功制备了2种形貌不同的Cd(Ⅱ)苯并咪唑基金属有机骨架(Cd-MOF)与氧化石墨烯(GO)的复合材料,利用扫描电子显微镜(SEM)、X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、紫外可见吸收光谱(UV-Vis)和傅里叶红外光谱(FT-IR)对复合材料的结构和性能进行了表征,并研究了其对水中罗丹明 B(rhodamine B,RhB)的吸附性能。结果表明:GO的加入增强了Cd-MOF在水中的稳定性,提高了吸附能力;当溶液pH为3.5,吸附时间为60 min时,吸附率可达约95%。 相似文献