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Graphene-encapsulated silica as matrix solid-phase dispersion extraction sorbents for the analysis of poly-methoxylated flavonoids in the leaves of Murraya panaculata (L.) Jack

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JOURNAL OF SEPARATION SCIENCE 2015年第12期38卷 2132-2139页

作者： Sun, Ting li, xuwen Yang, Jie li, Lanjie Jin, Yongri Shi, Xiaolei Jilin Univ Coll Chem Changchun 130062 Peoples R China Jilin Univ Coll Quartermaster Technol Changchun 130062 Peoples R China

In this study, graphene-encapsulated silica was synthesized by a hydrothermal reduction strategy. The presence of silica in graphene was identified by Fourier-transform infrared spectrometry, X-ray diffraction and scanning electron microscopy. The graphene-encapsulated silica subsequently was used as adsorbent for matrix solid-phase dispersion extraction of poly-methoxylated flavonoids from the dried leaves of Murraya panaculata (L.) Jack. Compared with the other adsorbents (graphene, silica gel, C-18 silica, neutral alumina, diatomaceous earth) and without any adsorbents, better results were obtained. Then a method for analysis of poly-methoxylated flavonoids was established by coupling matrix solid-phase dispersion extraction with ultra high performance liquid chromatography and UV detection. Compared with reflux extraction and ultrasonic extraction, the proposed method is quicker, more efficient and more environmental protection. Less than 10 min is needed from extraction to detection.

关键词： Flavonoids Graphene Matrix solid-phase dispersion Murraya panaculata Traditional Chinese medicine

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Dispersive solid-phase extraction of organophosphorus pesticides from apple, cucumber and water samples using reduced graphene oxide coated with ZnO nanocomposites as a sorbent

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ANALYTICAL METHODS 2015年第15期7卷 6095-6102页

作者： Sun, Ting Jin, Yongri Yang, Jie li, Lanjie Shi, Xiaolei li, xuwen Jilin Univ Coll Chem Changchun 130021 Peoples R China Jilin Univ Coll Quartermaster Technol Changchun 130062 Peoples R China

In this work, reduced graphene oxide coated with ZnO (RGO-ZnO) nanocomposites was synthesized by a hydrothermal reduction strategy. The presence of ZnO was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Subsequently, RGO-ZnO was used as a dispersive solid-phase extraction (DSPE) sorbent for the enrichment of eight organophosphorus pesticides (OPs) in apple, cucumber and water samples prior to their determination by gas chromatography-mass spectrometry (GC-MS). Several experimental parameters affecting the extraction efficiencies, including the amount of RGO-ZnO, extraction time, and the pH of the sample solution, as well as the type and volume of eluent solvent, were investigated and optimized in this work. Under the optimal experimental conditions, good linearity existed in the range of 0.5-200.0 ng g(-1) for all the analytes with the correlation coefficients (R-2) ranging from 0.9894 to 0.9983. The limits of detection (S/N = 3) of the method for the compounds were between 0.01 and 0.05 ng g(-1). Good reproducibilities were acquired with the relative standard deviations (RSDs) below 8.6% for both intra-day and inter-day precision. The recoveries of the method were in the range of 75.0% to 104.2%.

关键词： Nanocomposites

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Dependence of the liquid crystalline properties on the exactly controlled single-site functionalized density of mesogens focused on the alternating copolymer model

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POLYMER CHEMISTRY 2021年第45期12卷 6561-6568页

作者： Zhang, Ruixue li, xuwen Ma, Hongwei Han, li li, Chao Zhang, Songbo Bai, Hongyuan li, Yang Dalian Univ Technol Sch Chem Engn Dept Polymer Sci & Engn State Key Lab Fine Chem Dalian 116024 Peoples R China

Fluorinated liquid crystal polymers (FLCPs) with an AB/A(2)B-alternating sequence of fluorinated biphenyl moieties (FMs) along their backbones were constructed, where the anionic copolymerization of isoprene (Ip) with, mono-SiH and di-SiH functionalized 1,1-diphenylethylene (DPE) derivatives was performed to prepare alternating copolymer precursors with exactly controlled single-site densities of -SiH, i.e., alt-P(D-S/Ip) and alt-P(D-2S/Ip), respectively, followed by highly efficient hydrosilylation to introduce FMs into the repeating unit (DPE). Previous work indicated that the mesogenic properties were related to the distance between neighbouring mesogenic moieties in different polymerized units when the degree of polymerization (DP) of the copolymers was low. Hence, the present strategy provides a novel model to explore dependence of the mesogenic properties on the exactly controlled single-site functionalized density of mesogens (FMs) for the resulting alternating-templated FLCPs, which was achieved due to a quite low DP (11 for mono-SiH and 5 for di-SiH), while exhibiting a similar overall concentration of FMs along backbones bearing a similar number of Si-H groups. The results show that the polarized optical textures and the temperature range of mesogenic phase formation (Delta T) varied remarkably between A(2)B-alternating (Delta T = 104 degrees C) and AB-alternating (Delta T = 23 degrees C) FLCPs;in particular, the variation in phase transition temperature is possibly a result of exactly controlled single-site functionalized density. Herein, a novel morphological aggregation model is proposed to increase the comprehension of how the exactly controlled single-site functionalized density of FMs arranged within the small scale of polymer chains directs molecular packing and interactions between them, thereby enriching the diversity of molecular interactions.

关键词： Silicon compounds

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Hardware design of ADSP-BF548 based portable patient monitor

Hardware design of ADSP-BF548 based portable patient monitor

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2nd Annual Conference on Electrical and Control Engineering, ICECE 2011

作者： li, xuwen Wu, Qiang Wu, Shuicai College of Life Science and Bio-engineering Beijing University of Technology Beijing China College of Electronic Information and Control Engineering Beijing University of Technology Beijing China

ISBN: (纸本)9781424481637

This paper studies on hardware design of a novel patient monitor based on one ADSP-BF548 blackfin dsp. The NIBP, 12-lead ECG, SPO2 and body temperature functions are successfully implemented. A 6.4 inch TFT LCD with a touch screen is used as GUI output to display all monitor curves and parameters. Through the convergent capabilities of the blackfin dsp, the patient moitor can store data into NAND FLASH and SD card. The Ethernet, USB and WCDMA communication functions are also realized. Another advantage of this design is the powerful DSP computation performance which can guarantee more complex algorithms into one processor system. © 2011 IEEE.

关键词： Electrocardiography

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The Influenceof Rare Earth Element on α-Solidification of A356 Alloy

The Influenceof Rare Earth Element on α-Solidification of A...

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International Conference on Advances in Materials and Manufacturing Processes

作者： Zheng, Zhiqiang Xiong, Xingen Chen, Keming li, xuwen Nanchang Univ Nanchang 330031 Peoples R China

ISBN: (纸本)9780878492039

The Influenceof Rare Earth Element on alpha-Solidification of A356 Alloy has been discussed in the paper. It is showed by the research, that the condition of interphase is changed by Rare Earth element asymmetry distribution, which influences the process of a phase growing and facilitates the growth of alpha phase in sphere, and leads to a optimal Rare Earth quantity for facilitative effect, which is 0.5% in this experimentation, and that alpha phase grain will be change to small by adding Rare Earth.

关键词： semi-solid aluminum silicon alloy solidify Rare Earth

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Detecting differences in volume pulse wave parameters among fingers and toes in four different postures

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BIO-MEDICAL MATERIALS AND ENGINEERING 2015年第Sup1期26卷 S389-S394页

作者： Yan, Tingting Yang, lin Zhang, Song Yang, Yimin li, xuwen Beijing Univ Technol Coll Life Sci & Bioengn 100 Ping Le Yuan Beijing 100124 Peoples R China

The measurement of volume pulse waves may be easily affected based on the measured position (different fingers or toes), body posture, as well as other factors. Therefore, interferences during measurement need to be removed. For this study, relevant parameters of volume pulse wave were obtained by changing the affecting factors. The data were analyzed in order to indicate the differences in volume pulse wave parameters among different fingers and toes in four postures. Results showed that when subjects were lying, inclined or in a sitting posture, volume pulse wave parameters of the index finger, middle finger and ring finger on both hands displayed no apparent differences. When subjects were in a sitting posture, volume pulse wave parameters of the big, second and third toes on both feet showed no significant differences.

关键词： Photoplethysmography volume pulse wave parameters different postures

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Sensitive determination of three aconitum alkaloids and their metabolites in human plasma by matrix solid-phase dispersion with vortex-assisted dispersive liquid-liquid microextraction and HPLC with diode array detection

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JOURNAL OF SEPARATION SCIENCE 2016年第10期39卷 1971-1978页

作者： Wang, Xiaozhong li, xuwen li, Lanjie li, Min liu, Ying Wu, Qian li, Peng Jin, Yongri Jilin Univ Coll Chem Changchun 130012 Peoples R China Ningxia Univ Sch Chem & Chem Engn Yinchuan Peoples R China

A simple and sensitive method for determination of three aconitum alkaloids and their metabolites in human plasma was developed using matrix solid-phase dispersion combined with vortex-assisted dispersive liquid-liquid microextraction and high-performance liquid chromatography with diode array detection. The plasma sample was directly purified by matrix solid-phase dispersion and the eluate obtained was concentrated and further clarified by vortex-assisted dispersive liquid-liquid microextraction. Some important parameters affecting the extraction efficiency, such as type and amount of dispersing sorbent, type and volume of elution solvent, type and volume of extraction solvent, salt concentration as well as sample solution pH, were investigated in detail. Under optimal conditions, the proposed method has good repeatability and reproducibility with intraday and interday relative standard deviations lower than 5.44 and 5.75%, respectively. The recoveries of the aconitum alkaloids ranged from 73.81 to 101.82%, and the detection limits were achieved within the range of 1.6-2.1 ng/mL. The proposed method offered the advantages of good applicability, sensitivity, simplicity, and feasibility, which makes it suitable for the determination of trace amounts of aconitum alkaloids in human plasma samples.

关键词： Aconitum alkaloids Dispersive liquid-liquid microextraction Human plasma Matrix solid-phase dispersion

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A POWER MANAGEMENT CIRCUIT COMPATIBLE with Ti SmartReflex and Xilinx Ultrascale+ MPSoC DUAL VOLTAGE MECHANISM 10

A POWER MANAGEMENT CIRCUIT COMPATIBLE with Ti SmartReflex an...

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10th International Conference on Computing and Pattern Recognition, ICCPR 2021

作者： li, Chenyun li, xuwen Tang, Changjiang Wu, Qiang Beijing University of Technology China

ISBN: (纸本)9781450390439

Since the semiconductor technology has entered the age of 90 nm, the static power consumption of the chip has increased rapidly. For edge computing devices, the waste of power can not be ignored. This paper uses the relationship between power consumption and power supply voltage of FPGA and DSP, analyzes the characteristics of the traditional scheme, and designs a hardware circuit according to the different mechanisms of reducing static power consumption of FPGA and DSP According to the design of FPGA and DSP core power supply voltage compatibility, the system realizes the requirement of FPGA and DSP for power supply voltage amplitude and realizes dynamic control of power supply voltage. After verification and comparison, FPGA and DSP can realize the adjustment of performance power consumption and stable operation under the power system. © 2021 ACM.

关键词： Field programmable gate arrays (FPGA)

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Design and Implementation of Electronic Image Stabilization System Based on Dual-core DSP

Design and Implementation of Electronic Image Stabilization ...

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9th International Conference on Intelligent Information Hiding and Multimedia Signal Processing (IIH-MSP)

作者： Zhang, Haolong Wu, Qiang liu, Tianqi li, xuwen Beijing Univ Technol Coll Elect Informat & Control Engn Beijing Peoples R China Beijing Univ Technol Coll Life Sci & Bioengn Beijing Peoples R China

ISBN: (纸本)9780769551203

Electronic image stabilization (EIS) technology is an important research area of video processing and computer vision. This paper presented a set of fast and parallel EIS algorithms. Firstly, this paper proposed a fast local motion vector (LMV) estimation algorithm based on the FAST feature to solve the problem that the traditional algorithm is too complex. Secondly, a parallel global motion vector (GMV) algorithm based on image division is designed, which computes every LMV simultaneously, and then estimates the GMV by all LMVs. Finally, based on the proposed algorithm, an EIS systems based on BF609 dual-core DSP processor is designed and implemented. Experiment results show that the algorithm and system presented in this thesis can effectively stabilize jittery video and achieve high real-time performance. When dealing with PAL standard video, the total time cost is less than 40ms.

关键词： electronic image stabilization parallel multi-core

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Research of The Real-time Performance of Operating System

Research of The Real-time Performance of Operating System

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5th International Conference on Wireless Communications, Networking and Mobile Computing

作者： Jun Shen Qiang Wu xuwen li Yanhua Zhang Beijing Univ Technol Coll Elect & Control Engn Beijing Peoples R China Beijing Univ Technol Coll Life Sci & Bio Engn Beijing Peoples R China

ISBN: (纸本)9781424436927

Contraposing the basic principles and mechanism of the real-time operating system, the paper has compared general operating systems with real-time operating system, and made a good effort to analyze the key factors which may affect the real-time characteristics of operating system, and then given a assessment methods to evaluate the real-time character of operating system. A practical application system is also tested at last.

关键词： real-time factor operating system

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