Search

Your search keyword '"Li, Yan-Feng"' showing total 59 results
Start Over Author "Li, Yan-Feng" Publisher springer science and business media llc
59 results on '"Li, Yan-Feng"'

24. Novel kinetic method for expressing the ability of antioxidant to scavenge radicals

Author

LI Yan-feng, LI Pei-ze, and Liu Zai-qun

Subjects
Antioxidant, ABTS, DPPH, Radical, medicine.medical_treatment, General Chemistry, Medicinal chemistry, Chemical kinetics, Reaction rate, chemistry.chemical_compound, Reaction rate constant, Galvinoxyl, chemistry, medicine, Organic chemistry
Abstract

A method was developed to treat the result from an antioxidant trapping radicals including 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonate) cationic radical(ABTS+·), 2,2′-diphenyl-1-picrylhydrazyl radical(DPPH), and galvinoxyl radical. In the presence of a certain concentration of an antioxidant, the decrease of the concentration of a kind of radicals follows the second order exponential function with the increase of the reaction time(t), viz., [radical]=Ae−t/a +Be−t/b +C, the derivation operation of which obtains the differential style, −d[radical]/dt= (A/a)e−t/a +(B/b)e−t/b , revealing the relationship between the reaction rate(r=-d[radical]/dt) and the reaction time(t). Thus, the reaction rate at the beginning of the reaction(r 0) can be calculated by assigning t=0 in the equation of -d[radical]/dt-t. Based on the concept of the reaction rate, r=k[radical][antioxidant], the rate constant(k) can be calculated based on r 0 and the initial concentrations of radical and antioxidant, k=r 0/([radical]0[antioxidant]0). The k means the rate of a fresh antioxidant molecule to trap a fresh radical. This method was used to treat the interactions of ABTS+·, DPPH, and galvinoxyl radicals with three homoisoflavonoids, four pyrazoles, and three ferrocenyl Schiff bases. It was found that ferrocenyl group is beneficial for antioxidants to reduce ABTS+·, and ortho-hydroxyl group is beneficial for antioxidants to donate hydrogen atom in phenolic hydroxyl group to DPPH and galvinoxyl radicals.

Published
2013

27. Treatment of complicated urinary tract infection and acute pyelonephritis by short-course intravenous levofloxacin (750 mg/day) or conventional intravenous/oral levofloxacin (500 mg/day): prospective, open-label, randomized, controlled, multicenter, non-inferiority clinical trial

Author

Ren, Hong, primary, Li, Xiao, additional, Ni, Zhao-Hui, additional, Niu, Jian-Ying, additional, Cao, Bin, additional, Xu, Jie, additional, Cheng, Hong, additional, Tu, Xiao-Wen, additional, Ren, Ai-Min, additional, Hu, Ying, additional, Xing, Chang-Ying, additional, Liu, Ying-Hong, additional, Li, Yan-Feng, additional, Cen, Jun, additional, Zhou, Rong, additional, Xu, Xu-Dong, additional, Qiu, Xiao-Hui, additional, and Chen, Nan, additional

Published
2017
Full Text
View/download PDF

29. Enhanced nonlinear effects in photonic crystal fibers

Author

Wang Ching-Yue, Hu Minglie, Li Yan-Feng, and Chai Lu

Subjects
PHOSFOS, Materials science, Optical fiber, Physics and Astronomy (miscellaneous), business.industry, Physics::Optics, Microstructured optical fiber, Supercontinuum, law.invention, Optics, Zero-dispersion wavelength, law, Optoelectronics, Fiber, business, Photonic crystal, Photonic-crystal fiber
Abstract

Photonic crystal fibers are a new class of single-material optical fibers with wavelength-scale air holes running down the entire fiber length. Photonic crystal fibers were first developed in 1996 and have subsequently been the focus of increasing scientific and technological interest in the field of fiber optics. The manufacturing, principles, basic properties, and some applications of photonic crystal fibers are briefly described in this paper. A review of our recent work on the nonlinear effects in photonic crystal fibers is presented, and special emphasis is placed on such effects as supercontinuum generation, frequency conversion, and solitons observed when femtosecond light pulses propagate in these fibers.

Published
2006

Catalog

Books, media, physical & digital resources
See catalog results