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515 results on '"Yang, Yanqiang"'

104. Synthesis optimization of metal-organic frameworks MIL-125 and its adsorption separation on C8 aromatics measured by pulse test and simulation calculation

Author

Yang Yanqiang, Lunxi Li, Jianfeng Ma, Wang Hongchao, Qiao Xiaofei, Gao Ningning, Weiqiang Liu, Wang Dehua, Liu Yusi, and Huiguo Wang

Subjects
Alkane, chemistry.chemical_classification, Materials science, 02 engineering and technology, Microporous material, 010402 general chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Toluene, 0104 chemical sciences, Electronic, Optical and Magnetic Materials, Inorganic Chemistry, chemistry.chemical_compound, Crystallinity, Adsorption, chemistry, Chemical engineering, Materials Chemistry, Ceramics and Composites, Gravimetric analysis, Metal-organic framework, Physical and Theoretical Chemistry, 0210 nano-technology, Zeolite
Abstract

The metal-organic frameworks (MIL-125) were synthesized by the solvothermal method and the experimental parameters of preparation, purification and activation were optimized and the physicochemical properties were characterized. The adsorption capacity of MIL-125 on C8 aromatics was tested by the intelligent gravimetric analyzer (IGA) and the toluene vapor static adsorption device. The adsorption selectivity was studied by liquid static adsorption equilibrium experiment and large-scale pulse test. The C8 aromatics adsorption conformation and adsorption heat in MIL-125 was simulated by Materials Studio software. The characterization results show that the synthesized sample has excellent crystallinity, regular morphology with a grain size of about 1 ​μm, surface area of 1315 ​m2/g, micropore volume of 0.601 ​mL/g and a bulk density of 0.45 ​g/mL. Moreover, the vapor static adsorption results show that the synthesized sample has almost three times of adsorption capacity as large as BaX zeolite and the liquid dynamic adsorption results indicate the synthesized sample is preferentially selective to pare-xylene with the alkane desorbent. The simulation results show that the adsorption heat of pare-xylene in the synthesized sample and the binding energy of pare-xylene in the tetrahedral cage are the largest among these four isomers.

Published
2021

106. Spatial four-axis gyro combination surge protection and data filling method.

Author

DAI Minpeng, ZHANG Chunxi, and YANG Yanqiang

Subjects
DATA protection, LIGHT sources, RATE setting
Abstract

Aiming at the problems of surge and data loss when the four-axis gyro combination is used for space axial switching and light source switching, a surge protection and data filling method is proposed. Firstly, the dual light source scheme is adopted, and the surge protection circuit is designed to reduce the impact of the instantaneous high current on the components during the power-on process. Secondly, a data filling mechanism is established to compensate for the data lost during the switching process. Finally, the ground data filling experiment is carried out, the angular rate is set to 0.1745 rad/s and 1.745 rad/s, the difference between the predicted angular rate and the actual angular rate are no more than 0.003 rad/s and 0.008 rad/s, and the relative residuals are 0.003 9 and 0.0012 respectively, which verifying the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Published
2021
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107. Development of a deep eutectic solvent-based matrix solid phase dispersion methodology for the determination of aflatoxins in crops

Author

Yang Yanqiang, Xinxin Zhang, Xiaoni Chen, Yurong Liu, and Wu Xi

Subjects
Crops, Agricultural, Aflatoxin, Materials science, 01 natural sciences, Analytical Chemistry, Matrix (chemical analysis), chemistry.chemical_compound, 0404 agricultural biotechnology, Aflatoxins, Limit of Detection, Phase (matter), Sample preparation, Chromatography, High Pressure Liquid, Detection limit, Chromatography, 010401 analytical chemistry, Extraction (chemistry), Solid Phase Extraction, 04 agricultural and veterinary sciences, General Medicine, 040401 food science, 0104 chemical sciences, Deep eutectic solvent, Spectrometry, Fluorescence, chemistry, Solvents, Dispersion (chemistry), Food Science
Abstract

A novel and sensitive deep eutectic solvent-based matrix solid phase dispersion (DES-MSPD) method for the determination of aflatoxins (AFB1, AFB2, AFG1, AFG2) in various crops was established using high-performance liquid chromatography with fluorescence detection (HPLC-FLD). The DES-MSPD sample preparation procedure was optimized. Based on the optimal conditions, the intra-day and inter-day variability for AFs in all crop samples was less than 7.5%. Linearity was observed with R2 values (>0.994). Using the present method, HPLC-FLD gave the limits of detection (LODs) of 0.03–0.10 μg/kg and the limits of quantification (LOQs) of 0.10–0.33 μg/kg for AFs. This work represents the first attempt of using DESs as a green extraction medium for the extraction of AFs in MSPD. Compared with conventional MSPD methods, the DES-MSPD procedure looks promising as a relatively simple and low cost process to build an assay that can be used for monitoring concentrations of AFs in crops.

Published
2018

121. The Stellar-INS Navigation Performance Influence Mechanism of Star Vector Orientation in the Field of View.

Author

Zhang, Chunxi, Yang, Yanqiang, Zhang, Hao, and Cai, Xiaowen

Subjects
*VECTOR fields, *INERTIAL navigation systems, *STAR observations, *UNIVERSAL design
Abstract

The star sensor field of view varies from several arc-minutes to 20 degrees, which directly determines the star vector orientation in the field of view (FOV). Although the relationship between star vector orientation in the FOV and attitude accuracy has been revealed, the influence mechanism of star vector orientation on the integrated navigation performance of a stellar inertial navigation system has not been analysed. In order to improve the integrated accuracy, the main errors such as star sensor installation error, gyro error and initial platform angle error should be estimated online. It is significant to study the influence mechanism of star vector orientation on estimation of the above errors. In this paper, the star sensor sensitivity and the geometry factor are defined to feature the difference between the optical axis direction and the non-optical axis direction. The formulised mechanism and quantification results between star vector orientation and integration attitude and error estimation accuracy are clearly given. Simulation and ground testing were conducted and it was found that the larger the star vector orientation along the optical axis, the better the error estimation accuracy. In contrast, the attitude accuracy is weakly sensitive to the orientation of the star vector in conditions of appropriate posture adjustment and star observation scheme. This conclusion can offer universal guidance for the design and evaluation of stellar inertial navigation systems with narrow field of view or large field of view star sensors. [ABSTRACT FROM AUTHOR]

Published
2021
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122. Reconsideration of the Detection and Fluorescence Mechanism of a Pyrene-Based Chemosensor for TNT

Author

Lu, Meiheng, Zhou, Panwang, Ma, Yinhua, Tang, Zhe, Yang, Yanqiang, and Han, Keli

Abstract

The rapid detection of chemical explosives is crucial for national security and public safety, and the investigation of sensing mechanisms is important for designing highly efficient chemosensors. This study theoretically investigates the detection and fluorescence mechanism of a newly synthesized pyrene-based chemosensor for the detection of trinitrotoluene (TNT) through density-functional-theory (DFT) and time-dependent density-functional-theory (TDDFT) methods and suggests a different interaction product of the probe and TNT from previously reported ones [Mosca et al. J. Am. Chem. Soc.2015, 137, 7967]. Instead of forming Meisenheimer complexes, the energies of which are beyond those of the reactants, a low-energy product generated by a π–π-stacking interaction is more rational and favorable. The fluorescence-quenching property further confirms that the π–π-stacking product is the predicted one rather than luminescent Meisenheimer complexes. Frontier-molecular-orbital (FMO)-analysis results show that photoinduced electron transfer (PET) is the mechanism underlying the luminescence quenching of the probe upon exposure to TNT.

Published
2024
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123. DFT/TDDFT investigation on the D–π–A type molecule probes 4-(5-R-thiophen-2-yl)-2-isobutyl-2H-[1,2,3]triazolo[4,5-e][1,2,4] triazolo[1,5-a]pyrimidines: fluorescence sensing mechanism and roles of weak interactions.

Author

Ma, Yinhua, Feng, Liqiang, Liu, Jianyong, Yang, Yanqiang, and Chu, Tianshu

Subjects
FLUORESCENCE, STACKING interactions, CHARGE exchange, FLUORESCENT probes, TIME-dependent density functional theory
Abstract

We performed DFT/TDDFT investigation on the sensing mechanism of the D–π–A type fluorescence probes 4-(5-R-thiophen-2-yl)-2-isobutyl-2H-[1,2,3]triazolo[4,5-e][1,2,4] triazolo[1,5-a]pyrimidines (ITTP1, ITTP2, ITTP3), which are designed for detecting 2,4,6-trinitrophenol (TNP) explosive. Theoretical calculations reveal that the fluorescence sensing mechanism was induced by the combination of the π–π stacking interaction and photo-induced electron transfer. The blueshift in the UV–Vis spectrum of the ITTP sensors was correlated with the decrease in electron-donating ability of the molecule probes and was further evidenced by the calculated 1H NMR spectra and DCT index. The roles of the weak interactions: π–π stacking and hydrogen-bonding interaction for the probes fluorescence sensing process were analyzed, and the π–π stacking interaction was verified to be the dominant for the fluorescence sensing. The present finding should be useful for the future design of explosive fluorescent probes and the interpretation of the sensing mechanisms. [ABSTRACT FROM AUTHOR]

Published
2020
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139. Effect of intramolecular charge transfer on the two-photon absorption behavior of multibranched triphenylamine derivations.

Author

He, Xing, Xu, Bin, Liu, Yuqiang, Yang, Yanqiang, and Tian, Wenjing

Subjects
POLARITY (Physics), ABSORPTION spectra, FLUORESCENCE spectroscopy, TRIPHENYLAMINE, LIGHT absorption, MOLECULES, CHARGE transfer
Abstract

Solvent polarity effect on the absorption spectra and fluorescence spectra of a series of multibranched structure triphenylamine derivations (Ph-G0, Ph-G1, and Ph-G2) were analyzed to reveal the factors that determine the two-photon absorption (TPA) ability in these molecules. It was found that the dominate factor is the extent of intramolecular charge transfer upon photoexcitation, rather than coherent coupling between branches. This result suggests that it is more effective to change the electron withdrawing ability or electron giving ability of branches and core than simply increase the number of branches for enhancing the TPA ability in multibranched structure molecules. [ABSTRACT FROM AUTHOR]

Published
2012
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144. Yellow-green upconversion luminescence of Dy3+ ion in LiNbO3 crystal heavily codoped with ZnO.

Author

Li, Aihua, Lü, Qiang, Zheng, Zhiren, Sun, Liang, Wu, Wenzhi, Liu, Weilong, Yang, Yanqiang, and Lü, Tianquan

Subjects
LIGHT sources, LUMINESCENCE, ABSORPTION, MOLECULAR spectroscopy, EXCITON theory, ABSORPTION spectra
Abstract

The observed Dy3+ ion upconversion luminescence in LiNbO3 crystal heavily codoped with ZnO was spectrally and temporally analyzed by microsecond time-resolved spectrum under 806 nm intense femtosecond laser excitation at room temperature. Absorption spectrum and modified Judd-Ofelt approach were used to investigate its spectroscopic properties. The bright blue and intense yellow emissions are assigned to transitions 4F9/2→6H15/2 and 4F9/2→6H13/2, respectively. It is concluded that the main upconversion mechanism is excited state absorption by pump power dependence in combination with luminescence intensity temporal evolvements. [ABSTRACT FROM AUTHOR]

Published
2007
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