Papers by Keyword: Fluorescence

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Authors: Chao Yi Shi, Yu Jun Zhang, Gao Fang Yin, Nan Jing Zhao, Jing Bo Duan, Li Fang, Xue Xiao
Abstract: We employed a method based on pseudorandom sequence modulation to suppress the system noise and sunlight interference for in situ measurement of algae concentration. Based on the theory analysis of the pseudorandom sequence modulation method, we established a measurement system. The excitation light was modulated by m sequence. The induced modulated fluorescence was demodulated by AD630 and then narrow-band filtered by a two-order Butterworth low-pass filter. The practical experiment results show that the linear response correlation coefficients of the measurement system reach up to 0.999 weather in a low concentration range (0~10μg/L) or in the whole concentration range (0.5~100μg/L).
271
Authors: Xiong Lu Zhang, Qiu Yan Qin, Yi Ping Qian, Hong Xiao
Abstract: 1,3,4-oxadiazole(OXD) and its derivatives have excellent thermal stability and oxidation resistance and strong blue fluorescence emission[1].Six novel compounds have been designed and and synthesized. And their structures were confirmed by 1HNMR,FT-IR MS, UV-vis absorption results showed that the maximum absorption wavelength appeared at 304 nm,and fluorescence spectroscopy results showed that they emit strong purple fluorescence in DMF solution.
768
Authors: Hao Zhang, Xi Jiang
Abstract: The recognition and sensing of biologically and environmentally important species has emerged as a significant goal in the field of chemical sensors in recent years1. Fluorogenic methods in conjunction with suitable probes are preferable approaches for the measurement of these analytes because fluorimetry is rapidly performed, is nondestructive, is highly sensitive, is suitable for high-throughput screening applications2,3. We synthesized rhodamine derivatives compounds by a Schiff base reaction.
267
Authors: Ling Liang Long, Yan Jun Wu, Lin Wang
Abstract: A new fluorescent probe 1, bearing a pyridine group as receptor for H+ and a coumarin dye as fluorophore, was synthesized and characterized by 1H NMR, 13C NMR, ESI-Ms and single crystal X-ray diffraction analysis. The probe exhibited fluorescence ratiometric response to acidic pH. With decreasing of the pH from 8.32 to 2.49, the fluorescence emission spectra exhibited large red shift from 541 to 631 nm, with the emission ratios (I541 /I631) changed dramatically from 25.9 to 0.08, and the pKa value was calculated to be 5.45. Probe 1 exhibited high selectivity to pH, other interference species including metal ions and amino acid exerted no visible effect on probe 1 detecting pH. The intracellular pH imaging applications proved that the probe is suitable for monitoring acidic pH fluctuations in living cells.
83
Authors: Su Wen Liu, Hai Zheng Zhang
Abstract: As advances are made in the lithographic patterning process and critical defect size continues to shrink, new filters are required to remove particles in the sub-10 nm size range. Membrane filtration separates unwanted particles from a fluid by retaining particles on the membrane surface and pores, in much the same manner as a sieve. One key parameter of membrane performance is pore size, usually expressed as pore diameter. However, for nanofiltration, especially for the membranes whose pore size measures under 30 nm, manufacturers may use different methods to rate the membranes pore. Considering the different chemical structures of membranes, the vast combination of materials, and the methods of manufacturing, it is highly unlikely that a universal method can be used for all combinations.
217
Authors: Hong Liang Liu, Shou Zhi Pu, Shi Qiang Cui, Wei Jun Liu
Abstract: A novel photochromic diarylethene based on pyrazole moiety was synthesized and its photochromic and fluorescent properties were also investigated. The compound exhibited remarkable photochromism, changing from colorless to purple after irradiation with UV light both in solution and in PMMA film. In hexane solution and in PMMA film, the open-ring isomer of the diarylethene 1 exhibited relatively remarkable fluorescence. The results indicated that the pyrazole moiety played a very important role during the process of photochromic reaction for the diarylethene derivative. Using this dithienylethene 1c as optical storage was performed successfully.
53
Authors: Hong Liang Liu, Shou Zhi Pu, Wei Jun Liu, Shi Qiang Cui
Abstract: A novel photochromic diarylethene based on isoxazole moiety was synthesized and its photochromic and fluorescent properties were also investigated. It underwent reversible cyclization and cycloreversion reactions upon alternating irradiation with UV and visible light in hexane and in PMMA film. The compound exhibited remarkable photochromism, changing from colorless to purple after irradiation with UV light. When irradiation with UV light, the fluorescence intensity declined remarkably. The results showed that the diarylethene exhibited a relatively strong fluorescence switch along with the photochromism from open-ring isomer to closed-ring isomer. Using this dithienylethene 1c as optical storage was performed successfully.
3290
Authors: Wei Jun Liu, Yan Lu, Shou Zhi Pu
Abstract: A novel unsymmetrical diarylethene derivative bearing both phenyl and thiophene moieties, in which a chlorine group was substituted at the para-positions of the terminal phenyl ring, was synthesized. At the same time, its photochromic properties and fluorescence switch were investigated in detail. The results showed that this compound exhibited reversible photochromism, undergoing reversible cyclization and cycloreversion reactions upon alternating irradiation with UV and visible light both in solution and in PMMA film, and its absorption maxima were observed at 541 nm in hexane and at 550 nm in PMMA amorphous film, respectively, upon irradiation with 297 nm UV light. The fluorescence intensity of diarylethene decreased dramatically along with the photochromism from open-ring isomer to closed-ring isomer upon irradiation with 297 nm UV light in PMMA. In hexane solution, the open-ring isomer of the diarylethene 1 exhibited relatively strong fluorescence at 462 nm when excited at 316 nm.
1519
Authors: Zhi Peng Tong, Shou Zhi Pu, Shi Qiang Cui
Abstract: A photochromic diarylethene bearing a six-membered aryl unit 1-[(2,5-dimethyl-3-thienyl)]-2-[2-methy-4-(3,5-difluorophenyl)-phenyl]perfluoroyclopentene (1a) was synthesized and its photochromic and fluorescent properties were also investigated in detail. The results showed that this compound exhibited reversible photochromism, changing from colorless to red after irradiation with UV light, in which absorption maxima were observed at 521 and 536nm in hexane and PMMA film, respectively. The fluorescence intensity decreased along with the photochromism upon irradiation with 297 nm light in hexane.
37
Authors: Prasanta Kumar Biswas
Abstract: Nanostructured transparent conducting oxide (TCO) films such as tin doped indium oxide (ITO), antimony doped tin oxide (ATO), tin doped cadmium oxide (CTO) were deposited on suprasil grade pure silica glass from their respective precursors with wide variation of dopant concentration, 10, 30, 50, 70 at. % and their optical properties have been studied. The films were obtained by thermal curing (350 - 500°C) in air. If the cluster size be decreased to nanoscale then blue shift of bulk band gap occurs due to the quantum confinement effect of the semiconducting TCO materials. Free carrier concentration of ITO and ATO films were in the order of 1019 cc-1. The Moss-Burstein shift occurred in each case. The photoluminescence (PL) behaviour of the nanostructured materials revealed emissions for the HOMO-LUMO excitonic transitions. This was identified by selecting the excitation energy according to the photoluminescence excitonic transitions (PLE).
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