Search

Your search keyword '"Lü, Yanfei"' showing total 110 results
Start Over Author "Lü, Yanfei"
110 results on '"Lü, Yanfei"'

1. Formation mechanisms and fluorescence properties of carbon dots in coal burning dust from coal fired power plants

Author

Zhao, Zhexian, Zhang, Weizuo, Zhang, Jin, Li, Yuzhao, Bai, Han, Zhao, Fangming, Jin, Zhongcai, Tang, Ju, Xiao, Yiming, Xu, Wen, and Lü, Yanfei

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Carbon dots (CDs) shows great application potential with their unique and excellent performances. Coal and its derivatives are rich in aromatic ring structure, which is suitable for preparing CDs in microstructure. Coal burning dust from coal-fired power plants can be utilized as a rich resource to separate and extract CDs. It has been shown in our results that there have two main possible mechanisms for the formation of CDs in coal burning dust. One is the self-assembly of polycyclic aromatic hydrocarbons contained in coal or produced by incomplete combustion of coal. The other mechanism is that the bridge bonds linking different aromatic structures in coal are breaking which would form CDs with different functional groups when the coals are burning at high temperature. Under violet light excitation at 310-340 nm or red light at 610-640 nm, CDs extracted from coal burning dust can emit purple fluorescence around 410 nm. The mechanism of up-conversion fluorescence emission of CDs is due to a two-photon absorption process. The recycling of CDs from coal burning dust from coal-fired power plants are not only good to protect environment but also would be helpful for mass production of CDs.

Published
2024
Full Text
View/download PDF

2. Fluorescent property of carbon dots extracted from cigarette smoke and the application in bio-imaging

Author

Li, Yuzhao, Bai, Han, Zhang, Jin, Tang, Ju, Li, Yingfu, Zhang, Weizuo, Zhao, Zhexian, Xiao, Yiming, and Lü, Yanfei

Subjects
Physics - Biological Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Optics
Abstract

Cigarette smoke is one of the six major pollution sources in the room air. It contains large number of particles with size less than 10 nm. There exist carbon dots (CDs) in cigarette smoke which have strong fluorescence and with good bio-compatibility and low toxicity. CDs in cigarette smoke can be applied in bio-imaging which has great potential applications in the integration of cancer diagnosis and treatment. In this paper, CDs were extracted from cigarette smoke. Then, sodium borohydride was added to CDs aqueous solution for reduction and the reduced CDs (R-CDs) were used for biological cell imaging. The results indicate that the CDs with the particle size $<$10 nm in cigarette smoke are self-assembled by the polymerizated polycyclic aromatic hydrocarbons (PAHs) and ammonium nitrite which are disk nano-structure composed of $sp^2$/$sp^3$ carbon and oxygen/nitrogen groups or polymers. Sodium borohydride can reduce the carbonyl group on the surface of CDs to hydroxyl group and increase the ratio of the Na 1s ratio of the CDs from 1.86 to 7.42. The CDs can emit blue fluorescence under ultraviolet irradiation. After reduction, the R-CDS have the intensity of fluorescence 7.2 times than before and the fluorescence quantum yield increase from 6.13\% to 8.86\%. The photoluminescence (PL) wavelength of R-CDS have red-shift of 7 nm which was due to the increasing of Na element ratio. The onion epidermal cells labeled with R-CDs show that the CDs could pass through the cell wall into the cell and reach the nucleus. The cell wall and the nucleus could be clearly visualized. CDs also shows low toxicity to human bronchial epithelial cells (BEAS-2B) with good biological activity. The obtained results indicate that the CDs and R-CDs have good fluorescent property which could be used as bio-imaging agent., Comment: 12 pages, 9 figures

Published
2022
Full Text
View/download PDF

12. Application of Judd–Ofelt theory in analyzing Dy3+ doped SrCaF4 single crystal

Author

Zhao, Jianbin, primary, Wu, Min, additional, Wang, Xinxin, additional, Chen, Yitong, additional, Yan, Yuhui, additional, Feng, Weida, additional, Liu, Zhu, additional, Zheng, Lihe, additional, Lü, Yanfei, additional, Wang, Yangxiao, additional, Zhang, Zhen, additional, Liu, Junyang, additional, Chen, Weichao, additional, Su, Liangbi, additional, and Ruan, Fangfang, additional

Published
2023
Full Text
View/download PDF

20. Tunable Pr3+:LiYF4 lasers in the green-red spectral region.

Author

Liu, Huilong, Zhao, Zhexian, Xia, Jing, and Lü, Yanfei

Subjects
TUNABLE lasers, SECOND harmonic generation, FIBER lasers, WAVELENGTHS
Abstract

A tunable Pr3+:LiYF4 laser using a single birefringent filter (BF) plate under excitation with a frequency doubled optically pumped semiconductor laser was demonstrated to operate at nine different laser wavelengths of 523, 546, 604, 613, 639, 645, 670, 698, and 720 nm. Within these wavelengths, several new wavelengths of 613, 639, 645, and 670 nm were obtained. The total tuning range exceeded 190 nm in the visible spectral range on nine intervals between 523 nm and 720 nm. The highest output power of 2.32 W was achieved at an emission wavelength of 523 nm with a slope efficiency of 61.5% and an optical-to-optical efficiency of 52.1% with respect to the absorbed pump power. Moreover, by adjusting the rotation angle of the BF plate, a continuous-wave simultaneous dual-wavelength Pr3+:LiYF4 laser operating at 698 and 720 nm was also demonstrated. At an absorbed pump power of 4.45 W, the maximum output powers at 698 nm and 720 nm were 162 mW and 258 mW, respectively. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

44. Generation and propagation dynamics of Airy beam with the tunable tail.

Author

Liu, Huilong, Lü, Yanfei, Xia, Jing, Pu, Xiaoyun, and Zhang, Li

Subjects
*LIGHT propagation, *LASER beams, *ELLIPTIC curves, *GAUSSIAN beams, *DISTRIBUTION (Probability theory)
Abstract

We introduce a new kind of Airy beam called Airy beam with the tunable tail, which can be generated from the elliptical flat-topped Gaussian beam. The analytical formula of Airy beam with the tunable tail is derived. Airy beam with the single tail can be obtained by adjusting the ration of the beam width of elliptical flat-topped Gaussian beam. The tail length of Airy beam can be controlled by the orderNof incident beam. The normalized intensity distributions of Airy beam with the tunable tail propagating in free space are studied, and the propagation dynamics of Airy beam with the single tail are investigated. Compared with the Airy beam generated from the fundamental Gaussian beam or the flat-topped Gaussian beam, some interesting and useful information has been found. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

49. Modified Algorithm for Designing of Diffractive Optical Element to Decrease the Phase Singular Spots

Author

董渊 Dong Yuan, 吕彦飞 Lü Yanfei, 金光勇 Jin Guangyong, 李青松 Li Qingsong, 李述涛 Li Shutao, and 张喜和 Zhang Xihe

Subjects
Optics, Materials science, Spots, business.industry, Phase (waves), Element (category theory), business, Atomic and Molecular Physics, and Optics, Simulation, Electronic, Optical and Magnetic Materials
Published
2012
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results