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111.
Chu-Chi Ting Yi-Shan Chiu Chia-Wei Chang Liang-Chih Chuang 《Journal of solid state chemistry》2011,184(3):563-9
Er3+-doped Y2Ti2O7 nanocrystals were fabricated by the sol-gel method. While the annealing temperature exceeds 757 °C, amorphous pyrochlore phase ErxY2−xTi2O7 transfers to well-crystallized nanocrystals, and the average crystal size increases from ∼70 to ∼180 nm under 800-1000 °C/1 h annealing. ErxY2−xTi2O7 nanocrystals absorbing 980 nm photons can produce the upconversion (526, 547, and 660 nm; 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2, respectively) and Stokes (1528 nm; 4I13/2→4I15/2) photoluminescence (PL). The infrared PL decay curve is single-exponential for Er3+ (5 mol%)-doped Y2Ti2O7 nanocrystals but slightly nonexponential for Er3+ (10 mol%)-doped Y2Ti2O7 nanocrystals. For 5 and 10 mol% doping concentrations, the mechanism of up-converted green light is the two-photon excited-state absorption. Much stronger intensity of red light relative to green light was observed for the sample with 10 mol% dopant. This phenomenon can be attributed to the reduced distance between Er3+-Er3+ ions, resulting in the enhancement of the energy-transfer upconversion and cross-relaxation mechanisms. 相似文献
112.
This study presents the investigation of bioconjugating ability of near-infrared (NIR) CdSeTe/ZnS quantum dots (QDs) (710 nm) and visible CdSe QDs (595 nm) in immunofluorescent staining for cancer biomarkers in gastric cancer tissues probed with the homemade Hadamard transform (HT) spectral imaging microscope and a commercial multispectral imaging system. The results show that imunostaining ability of NIR QDs probes is stronger than that of visible QDs when the two kinds of QDs are simultaneously used to probe the cancer biomarkers such as cytokeratin 20 (CK20) and proliferating cell nuclear antigen (PCNA) in gastric cancer tissues. Moreover, when the two QDs probes are used for immunostaining successively for the same target molecules, staining order has great influences on the final results due to their different conjugating ability to the marker proteins. The results imply that NIR QDs hold more promise for real-time imaging of tumor tissues due to its higher sensitivity and contrast. In addition, the results also demonstrate the potential of Hadamard transform spectral imaging as a useful tool in biomedical analysis and quantitative evaluation for tumor tissues. 相似文献
113.
Chalcopyrite quaternary semiconductor Cu(In(x)B(1-x))Se(2) nanocrystals have been successfully prepared via a relatively simple and convenient solvothermal route. The effect of different solvents on the formation of the product also indicates that diethylenetriamine is the optimal solvent for this reaction. The device parameters for a single junction Cu(In(x)B(1-x))Se(2) solar cell under AM1.5G are as follows: an open circuit voltage of 265 mV, a short-circuit current of 25.90 mA/cm(2), a fill factor of 34%, and a power conversion efficiency of 2.34%. Based on a series of comparative experiments under different reaction conditions, the probable formation mechanism of crystal Cu(In(x)B(1-x))Se(2) nanorods is proposed. 相似文献
114.
Inverted carbenoid species, generated from attack of phosphines at the α(δ')-carbon of hex-2-en-4-ynedioic acid dialkyl esters, react with aldehydes to give γ-lactones possessing an α-phosphorus ylide moiety. 相似文献
115.
Chuang WT Hsieh CC Lai CH Lai CH Shih CW Chen KY Hung WY Hsu YH Chou PT 《The Journal of organic chemistry》2011,76(20):8189-8202
o-Hydroxy analogues, 1a-g, of the green fluorescent protein chromophore have been synthesized. Their structures and electronic properties were investigated by X-ray single-crystal analyses, electrochemistry, and luminescence properties. In solid and nonpolar solvents 1a-g exist mainly as Z conformers that possess a seven-membered-ring hydrogen bond and undergo excited-state intramolecular proton transfer (ESIPT) reactions, resulting in a proton-transfer tautomer emission. Fluorescence upconversion dynamics have revealed a coherent type of ESIPT, followed by a fast vibrational/solvent relaxation (<1 ps) to a twisted (regarding exo-C(5)-C(4)-C(3) bonds) conformation, from which a fast population decay of a few to several tens of picoseconds was resolved in cyclohexane. Accordingly, the proton-transfer tautomer emission intensity is moderate (0.08 in 1e) to weak (~10(-4) in 1a) in cyclohexane. The stronger intramolecular hydrogen bonding in 1g suppresses the rotation of the aryl-alkene bond, resulting in a high yield of tautomer emission (Φ(f) ≈ 0.2). In the solid state, due to the inhibition of exo-C(5)-C(4)-C(3) rotation, intense tautomer emission with a quantum yield of 0.1-0.9 was obtained for 1a-g. Depending on the electronic donor or acceptor strength of the substituent in either the HOMO or LUMO site, a broad tuning range of the emission from 560 (1g) to 670 nm (1a) has been achieved. 相似文献
116.
Fu XZ Lin JY Xu S Luo JL Chuang KT Sanger AR Krzywicki A 《Physical chemistry chemical physics : PCCP》2011,13(43):19615-19623
A dehydrogenation anode is reported for hydrocarbon proton conducting solid oxide fuel cells (SOFCs). A Cu-Cr(2)O(3) nanocomposite is obtained from CuCrO(2) nanoparticles as an inexpensive, efficient, carbon deposition and sintering tolerant anode catalyst. A SOFC reactor is fabricated using a Cu-Cr(2)O(3) composite as a dehydrogenation anode and a doped barium cerate as a proton conducting electrolyte. The protonic membrane SOFC reactor can selectively convert ethane to valuable ethylene, and electricity is simultaneously generated in the electrochemical oxidative dehydrogenation process. While there are no CO(2) emissions, traces of CO are present in the anode exhaust when the SOFC reactor is operated at over 700 °C. A mechanism is proposed for ethane electro-catalytic dehydrogenation over the Cu-Cr(2)O(3) catalyst. The SOFC reactor also has good stability for co-generation of electricity and ethylene at 700 °C. 相似文献
117.
Optical waveguides synthesized at the micro/nanoscale have drawn great interest for their potential applications in high speed miniaturized photonic integrations. In this Perspective article, we mainly focus on the related works on active optical waveguides based on functional small organic molecules in micro/nano regime. We begin with a general overview of recent progress in sub-wavelength optical waveguides, including the development of waveguide materials of inorganic semiconductors, polymers, and small organic molecules. Then brief highlights are put on the recently reported organic optical waveguides with various unique optical properties induced by the ordered molecular aggregations in the micro/nano-sized solid-state structures, such as polarized emission, lasing, aggregation-induced enhanced emission, etc. This article concludes with a summary and our personal view about the direction of future development in organic opto-functional waveguides as photonic devices. 相似文献
118.
Meccanica - Contact between two deformable bodies is a complex nonlinear problem especially when rigid-body motion and geometric errors of components are taken into consideration. In this paper, an... 相似文献
119.
由一个正弦映射和一个三次方映射通过非线性耦合,构成一个新的二维正弦离散映射. 基于此二维正弦离散映射得到系统的不动点以及相应的特征值,分析了系统的稳定性,研究了系统的复杂非线性动力学行为及其吸引子的演变过程. 研究结果表明:此二维正弦离散映射中存在复杂的对称性破缺分岔、Hopf分岔、倍周期分岔和周期振荡快慢效应等非线性物理现象. 进一步根据控制变量变化时系统的分岔图、Lyapunov指数图和相轨迹图分析了系统的分岔模式共存、快慢周期振荡及其吸引子的演变过程,通过数值仿真验证了理论分析的正确性.
关键词:
正弦离散映射
对称性破缺分岔
Hopf分岔
吸引子 相似文献
120.
塞曼效应与边缘离子温度的光谱测量 总被引:1,自引:0,他引:1
通过理论推导得到了谱线实际宽度和塞曼展宽之间的关系。在磁感应强度分别为1、2、2.5和3T的情况下,用数值方法进行了求解,用得到的结果拟合出了校正因子随离子温度变化的经验公式和拟合曲线,结果表明:离子温度较低时,塞曼效应对谱线宽度的影响很大,温度较高时,塞曼效应对谱线宽度的影响可以忽略。 相似文献