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OALib Journal期刊

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匹配条件: “ Zhao Guan” ,找到相关结果约38924条。
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Design of a High Frequency Driving Circuit of Surface Acoustic Wave Transducer  [PDF]
Guan Zhao
Open Access Library Journal (OALib Journal) , 2018, DOI: 10.4236/oalib.1104737
Abstract:
In this paper, a high frequency driving circuit of surface acoustic wave transducer has been designed to separate oil from oil/water mixed droplet. The transmission frequency of the surface acoustic wave transducer driving circuit can be up to 1 MHz. The transmit frequency of conventional ultrasonic driving circuit is mostly 40 kHz. However, the high transmit frequency driving circuit presents a good stability and accuracy. By establishing the surface acoustic wave driving circuit model, the actual circuit and debugging verification, the driving circuit can excite the frequency signal required for the experiment. Thus, the surface acoustic wave driving circuit could provide necessary technical support for application in other fields.
An Investigation into Culturally-Loaded Words Teaching and Learning by Non-English Majors  [PDF]
Chen Guan, Yanan Zhao
Open Journal of Modern Linguistics (OJML) , 2016, DOI: 10.4236/ojml.2016.62004
Abstract: Culturally-loaded words and expressions are the direct and indirect reflection of national culture in the structure of words and expressions. Improper use of culturally-loaded words may result in misunderstanding in cross-cultural communication. By means of paper test and questionnaire, this paper aims at investigating the current situation of culturally-loaded words teaching and learning among non-English majors in Baoding University. Some suggestions are proposed on how to improve culturally-loaded words teaching and learning based on the study result.
A Pilot Study Verifying How the Curve Information Impacts on the Driver Performance with Cognition Model
Xiaohua Zhao,Wei Guan,Xiaoming Liu
Discrete Dynamics in Nature and Society , 2013, DOI: 10.1155/2013/316896
Abstract:
Leader selection and weight adjustment problems for multi-agent systems
Bin Zhao,Yongqiang Guan,Long Wang
Computer Science , 2015,
Abstract: For an uncontrollable system, adding leaders and adjusting edge weights are two methods to improve controllability. In this paper, controllability of multi-agent systems under directed topologies is studied, especially on leader selection problem and weight adjustment problem. For a given system, necessary and sufficient algebraic conditions for controllability with fewest leaders are proposed. From another perspective, when leaders are fixed, controllability could be improved by adjusting edge weights, and therefore the system is supposed to be structurally controllable, which holds if and only if the communication topology contains a spanning tree. It is also proved that the number of fewest edges needed to be assigned on new weights equals the rank deficiency of controllability matrix. An algorithm on how to perform weight adjustment is presented. Simulation examples are provided to illustrate the theoretical results.
Iterative Technology in a Singular Fractional Boundary Value Problem with q -Difference  [PDF]
Xiuli Lin, Zengqin Zhao, Yongliang Guan
Applied Mathematics (AM) , 2016, DOI: 10.4236/am.2016.71008
Abstract: In this paper, we apply the iterative technology to establish the existence of solutions for a fractional boundary value problem with q-difference. Explicit iterative sequences are given to approxinate the solutions and the error estimations are also given.
The Design of Surface Acoustic Wave Receiving Circuit Based on Piezoelectric Transducer  [PDF]
Hao Jiang, Fuqiang Zhang, Zhao Guan
Open Access Library Journal (OALib Journal) , 2018, DOI: 10.4236/oalib.1104829
Abstract:
A type of Surface Acoustic Wave (SAW) receiving circuit with high stability is introduced in this paper on the basis of analyzing common surface acoustic wave receiving circuits. The circuit design is based on receiving transducer and the center frequency is 1 MHz. This circuit includes pre-amplification electric circuit with high input impedance, automatic gain amplifying circuit based on VCA810, tertiary amplifying circuit, filter circuit and automatic voltage com-parison circuit. Receiving gate is used to preventing transmission pulse inter-feres the receipt signal. For better detecting the arrival time of receipt signal, voltage comparing circuit is served as examining the receipt signal, and meas-urement accuracy of acoustic transit time is improved substantially. By con-trast, amplification in three levels improves the circuit’s working stability. In addition, the circuit has the advantage of simple structure, signal stability and low manufacturing cost.
Comparison of the 48-week efficacy between entecavir and adefovir in HBeAg-positive nucleos(t)ide-na?ve Asian patients with chronic hepatitis B: a meta-analysis
Pan Zhao, Weiwei Liu, Jun Zhao, Qun Guan
Virology Journal , 2011, DOI: 10.1186/1743-422x-8-75
Abstract: We searched all data documented in Pubmed, Embase, Wanfang Database and CNKI (China National Knowledge Infrastructure) before November 30, 2010. Heterogeneity was examined by Chi-square test, the relative risk calculated and forest plot drawn. Rates of undetected serum HBV DNA, serum alanine aminotransferase (ALT) normalization, HBeAg clearance and HBeAg seroconversion were analyzed. A total of 6 articles was included. Meta analysis showed that the rate of undetected serum HBV DNA (relative risk, 1.73; 95% confidence interval, 1.38-2.17; P < 0.00001) and that of serum ALT normalization (relative risk, 1.25; 95% confidence interval, 1.06-1.49; P = 0.009) in the entecavir group were higher than those in the adefovir group. However, no statistic significance existed between the two groups in the rate of HBeAg clearance (relative risk, 0.77; 95% confidence interval, 0.44-1.35; P = 0.36), or the rate of HBeAg seroconversion (relative risk, 0.74; 95% confidence interval, 0.28-1.94; P = 0.53).Entecavir is superior to adefovir in decreasing serum HBV DNA and normalizing ALT but similar with adefovir in clearing HBeAg and encouraging HBeAg seroconversion for the HBeAg-positive nucleos(t)ide-naive Asian patients with chronic hepatitis B. Adefovir can be still used for first-line therapy in these patients.Infection with HBV is a major public health problem. Approximately 2 billion people have been exposed to HBV, and more than about 350 million are chronically infected with HBV [1]. Chronic hepatitis B (CHB) can lead to life-threatening conditions like liver cirrhosis (LC) and hepatocellular carcinoma (HCC) [2-4]. By the effective anti-HBV therapy, the worsening progress may be blocked or delayed. Oral nucleoside and nucleotide analogues (NAs) have revolutionized the treatment of chronic hepatitis B, which can suppress HBV replication in most patients and improve transaminase levels. To date, three nucleoside analogues (lamivudine, entecavir, telbivudine) and one nucleotide an
Effects of 2′-O-Methyl Nucleotide Substitution on EcoRI Endonuclease Cleavage Activities
Guojie Zhao, Bin Zhao, Zhaoxue Tong, Runqing Mu, Yifu Guan
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0077111
Abstract: To investigate the effect of sugar pucker conformation on DNA-protein interactions, we used 2′-O-methyl nucleotide (2′-OMeN) to modify the EcoRI recognition sequence -TGAATTCT-, and monitored the enzymatic cleavage process using FRET method. The 2′-O-methyl nucleotide has a C3′-endo sugar pucker conformation different from the C2′-endo sugar pucker conformation of native DNA nucleotides. The initial reaction velocities were measured and the kinetic parameters, Km and Vmax were derived using Michaelis-Menten equation. Experimental results showed that 2′-OMeN substitutions for the EcoRI recognition sequence decreased the cleavage efficiency for A2, A3 and T4 substitutions significantly, and 2′-OMeN substitution for T5 residue inhibited the enzymatic activity completely. In contrast, substitutions for G1 and C6 could maintain the original activity. 2′-fluoro nucleic acid (2′-FNA) and locked nucleic acid (LNA) having similar C3′-endo sugar pucker conformation also demonstrated similar enzymatic results. This position-dependent enzymatic cleavage property might be attributed to the phosphate backbone distortion caused by the switch from C2′-endo to C3′-endo sugar pucker conformation, and was interpreted on the basis of the DNA-EcoRI structure. These 2′-modified nucleotides could behave as a regulatory element to modulate the enzymatic activity in vitro, and this property will have potential applications in genetic engineering and biomedicine.
Investigation of the Frequency Shift of a SAD Circuit Loop and the Internal Micro-Cantilever in a Gas Sensor
Liu Guan,Jiahao Zhao,Shijie Yu,Peng Li,Zheng You
Sensors , 2010, DOI: 10.3390/s100707044
Abstract: Micro-cantilever sensors for mass detection using resonance frequency have attracted considerable attention over the last decade in the field of gas sensing. For such a sensing system, an oscillator circuit loop is conventionally used to actuate the micro-cantilever, and trace the frequency shifts. In this paper, gas experiments are introduced to investigate the mechanical resonance frequency shifts of the micro-cantilever within the circuit loop(mechanical resonance frequency, MRF) and resonating frequency shifts of the electric signal in the oscillator circuit (system working frequency, SWF). A silicon beam with a piezoelectric zinc oxide layer is employed in the experiment, and a Self-Actuating-Detecting (SAD) circuit loop is built to drive the micro-cantilever and to follow the frequency shifts. The differences between the two resonating frequencies and their shifts are discussed and analyzed, and a coefficientrelated to the two frequency shifts is confirmed.Micro-cantilever sensors for mass detection using resonance frequency have attracted considerable attention over the last decade in the field of gas sensing. For such a sensing system, an oscillator circuit loop is conventionally used to actuate the micro-cantilever, and trace the frequency shifts. In this paper, gas experiments are introduced to investigate the mechanical resonance frequency shifts of the micro-cantilever within the circuit loop(mechanical resonance frequency, MRF) and resonating frequency shifts of the electric signal in the oscillator circuit (system working frequency, SWF). A silicon beam with a piezoelectric zinc oxide layer is employed in the experiment, and a Self-Actuating-Detecting (SAD) circuit loop is built to drive the micro-cantilever and to follow the frequency shifts. The differences between the two resonating frequencies and their shifts are discussed and analyzed, and a coefficientrelated to the two frequency shifts is confirmed.
Molecular dynamics study on BPTI aqueous solution by ABEEM/MM fluctuating charge model
Guan QingMei,Cui BaoQiu,Zhao DongXia,Gong LiDong,Yang ZhongZhi
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-007-0493-5
Abstract: Molecular dynamics simulation on BPTI (biovine pancreatic trypsin inhibitor) aqueous solution has been performed for the first time in terms of the atom-bond electronegativity equalization method fused with molecular mechanics (ABEEM/MM). The simulated parameters including ABEEM parameters and force field parameters have been tested. Some structural properties including root-mean-square deviations of atomic coordinates and radial distribution functions were studied by ABEEM/MM fluctuating charge method. The results demonstrate that this model can obtain reasonable structural properties compared with experimental crystal data. The radial distribution functions indicate that ABEEM/MM method can well embody the electrostatic polarizations between protein molecule and its surrounding solvent waters.
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