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Search Results: 1 - 10 of 104318 matches for " Zhiquan Zhang "
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Influence Factor Analysis on Strength of Lime-Fly Ash Loess  [PDF]
Yufen Zhang, Zhiquan Zhang
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.56068
Abstract: Lime-fly ash loess is composed of fly ash, lime and loess. It is a new material in subgrade backfill. Main factors to influence the strength of lime-fly ash loess are age, amount of fly ash and lime, ratio of fly ash to lime (1:K), and moisture content. In order to observe the effect of each factor influencing the strength of lime-fly ash loess and find out the relationship between each other, this paper adopted orthogonal test design to conduct unconfined compression tests. The result shows that 90d strength can be considered to calculate the strength of lime-fly ash loess in practice. And the most important factor to influence the 90d strength of lime-fly ash loess is the amount of fly ash and lime, the second is moisture content, and then is the ratio of fly ash to lime (1:K). These achievements are significant to the design and application of lime-fly ash loess in subgrade construction of loess areas.
地质与勘探 , 1999,
Abstract: 研究了找锶矿的
Transmembrane Protein Alignment and Fold Recognition Based on Predicted Topology
Han Wang, Zhiquan He, Chao Zhang, Li Zhang, Dong Xu
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069744
Abstract: Background Although Transmembrane Proteins (TMPs) are highly important in various biological processes and pharmaceutical developments, general prediction of TMP structures is still far from satisfactory. Because TMPs have significantly different physicochemical properties from soluble proteins, current protein structure prediction tools for soluble proteins may not work well for TMPs. With the increasing number of experimental TMP structures available, template-based methods have the potential to become broadly applicable for TMP structure prediction. However, the current fold recognition methods for TMPs are not as well developed as they are for soluble proteins. Methodology We developed a novel TMP Fold Recognition method, TMFR, to recognize TMP folds based on sequence-to-structure pairwise alignment. The method utilizes topology-based features in alignment together with sequence profile and solvent accessibility. It also incorporates a gap penalty that depends on predicted topology structure segments. Given the difference between α-helical transmembrane protein (αTMP) and β-strands transmembrane protein (βTMP), parameters of scoring functions are trained respectively for these two protein categories using 58 αTMPs and 17 βTMPs in a non-redundant training dataset. Results We compared our method with HHalign, a leading alignment tool using a non-redundant testing dataset including 72 αTMPs and 30 βTMPs. Our method achieved 10% and 9% better accuracies than HHalign in αTMPs and βTMPs, respectively. The raw score generated by TMFR is negatively correlated with the structure similarity between the target and the template, which indicates its effectiveness for fold recognition. The result demonstrates TMFR provides an effective TMP-specific fold recognition and alignment method.
Investigation of electron transfer across the ice/liquid interface by scanning electrochemical microscopy
Zhiquan Zhang,Peng Sun,Zhao Gao,Yuanhua Shao
Chinese Science Bulletin , 2003, DOI: 10.1007/BF03183331
Abstract: The study of interfacial electron transfer (ET) reaction between ferricinium (Fc+) producedin situ in 1,2-dichloroethane (DCE) and ferrocyanide in ice matrix under low temperatures by the scanning electrochemical microscopy (SECM) is reported. Tetrabutylammonium (TBA+) is used as the common ion (potential-determining ion) in both phases to control the interfacial potential difference. The potential drop across the liquid/liquid interface can be quantitatively adjusted by changing the ratio of concentrations of TBA+ between the two phases. The apparent heterogeneous rate constants for Fc+ reduction by Fe(CN) 6 4 at the interface under different temperatures have been obtained by a best-fit analysis, where the experimental approach curves are fitted to the theoretical simulated curves. A sharp change has been observed for heterogeneous rate constants around the freezing point of the aqueous phase, which reflects the phase transition process.
Prevalence and Trends of the Abdominal Aortic Aneurysms Epidemic in General Population - A Meta-Analysis
Xi Li, Ge Zhao, Jian Zhang, Zhiquan Duan, Shijie Xin
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0081260
Abstract: Objective To conduct a meta-analysis assessing the prevalence and trends of the abdominal aortic aneurysms (AAA) epidemic in general population. Method Studies that reported prevalence rates of AAA from the general population were identified through MEDLINE, EMBASE, Web of Science, and reference lists for the period between 1988 and 2013. Studies were included if they reported prevalence rates of AAA in general population from the community. In stratified analyses possible sources of bias, including areas difference, age, gender and diameter of aneurysms were examined. Publication bias was assessed with Egger's test method. Results 56 studies were identified. The overall pooled prevalence of AAA was 4.8% (4.3%, 5.3%). Stratified analyses showed the following results, areas difference: America 2.2% (2.2%, 2.2%), Europe 2.5% (2.4%, 2.5%), Australia 6.7% (6.5%, 7.0%), Asia 0.5% (0.3%, 0.7%); gender difference: male 6.0% (5.3%, 6.7%), female 1.6% (1.2%, 1.9%); age difference: 55–64years 1.3% (1.2%, 1.5%), 65–74 years 2.8% (2.7%, 2.9%), 75–84 years1.2%(1.1%, 1.3%), ≥85years0.6% (0.4%, 0.7%); aortic diameters difference: 30–39 mm, 3.3% (2.8%, 3.9%), 40–49 mm,0.7% (0.4%,1.0%), ≥50 mm, 0.4% (0.3%, 0.5%). The prevalence of AAA has decreased in Europe from 1988 to 2013. Hypertension, smoking, coronary artery disease, dyslipidemia, respiratory disease, cerebrovascular disease, claudication and renal insufficiency were risk factors for AAA in Europe. Conclusion AAA is common in general population. The prevalence of AAA is higher in Australia than America and Europe. The pooled prevalence in western countries is higher than the Asia. Future research requires a larger database on the epidemiology of AAA in general population.
Protein Structural Model Selection by Combining Consensus and Single Scoring Methods
Zhiquan He, Meshari Alazmi, Jingfen Zhang, Dong Xu
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0074006
Abstract: Quality assessment (QA) for predicted protein structural models is an important and challenging research problem in protein structure prediction. Consensus Global Distance Test (CGDT) methods assess each decoy (predicted structural model) based on its structural similarity to all others in a decoy set and has been proved to work well when good decoys are in a majority cluster. Scoring functions evaluate each single decoy based on its structural properties. Both methods have their merits and limitations. In this paper, we present a novel method called PWCom, which consists of two neural networks sequentially to combine CGDT and single model scoring methods such as RW, DDFire and OPUS-Ca. Specifically, for every pair of decoys, the difference of the corresponding feature vectors is input to the first neural network which enables one to predict whether the decoy-pair are significantly different in terms of their GDT scores to the native. If yes, the second neural network is used to decide which one of the two is closer to the native structure. The quality score for each decoy in the pool is based on the number of winning times during the pairwise comparisons. Test results on three benchmark datasets from different model generation methods showed that PWCom significantly improves over consensus GDT and single scoring methods. The QA server (MUFOLD-Server) applying this method in CASP 10 QA category was ranked the second place in terms of Pearson and Spearman correlation performance.
Effects of liver inflammation on FibroScan diagnosis of hepatic fibrosis in patients with chronic hepatitis B
LIU Zhiquan
Journal of Clinical Hepatology , 2013,
Abstract: ObjectiveTo investigate the influence of liver inflammation on the ability of the FibroScan non-invasive elastrography scanner to diagnose hepatic fibrosis in patients with chronic hepatitis B (CHB). MethodsA total of 124 CHB patients who received liver biopsy and concomitant liver stiffness measurement (LSM) by FibroScan between June 2011 and February 2012 were enrolled in the study. The liver puncture biopsies were subjected to histological analysis to determine fibrosis stage (S1 to S4, mild fibrosis to severe fibrosis or cirrhosis) and inflammation grade (G1 to G4, low to high extent of inflammation). Differences between groups were assessed by Kruskal-Wallis H test or Mann-Whitney U test. The correlations between LSM and fibrosis stages and inflammation grades were evaluated by Spearman’s rank correlation coefficient. Results The progressive fibrosis stages were accompanied by increased inflammatory grades, such that the significant majority of S1 samples showed G1 inflammation (81.8%, n=55; P<0.01), of S2 showed G2 inflammation (54.2%, n=13; P<0.01), of S3 showed G3 inflammation (47.4%, n=9; P<0.05), and of S4 showed G3 and G4 inflammation (40.0%, n=6 and 334%, n=5; both P<0.01). LSM and inflammation grade were positively correlated within each fibrosis stage group (P<0.01), suggesting that the degree of liver inflammation affects the FibroScan measured value. ConclusionLiver inflammation influences LSM by FibroScan and may impact the ability of this technology to diagnose hepatic fibrosis, with more severe inflammatory activity affecting the LSM to a greater extent.
Noise Removal Algorithm of LIDAR Point Clouds Based on 3DFinite-element Analysis

ZUO Zhiquan,ZHANG Zuxun,ZHANG Jianqing,

遥感学报 , 2012,
Abstract: According to analysis of the limitations of traditional algorithms, such as local points fitting and frequency domainsignal analysis, a typical noise removalremoval algorithm of LIDAR point clouds based on 3 D finite-element analysis is proposed.Firstly, point clouds is partitioned into smaller and similar units by finite elements named space hexahedron model. Andthen, all of the units are classified into noise units or non-noise units with adjacency-based reasoning rules. Finally, the lownoise is removed by iterative processing with finer threshold. In this approach, we did experiments with a real strip data whichis obtained by an international mainstream system. The result shows that finite-element analysis has good performance in noiseremoval.soil dielectric constant, organic matter, humus, microwave remote sensing
Scientific design and preliminary results of three-dimensional variational data assimilation system of GRAPES
JiShan Xue,ShiYu Zhuang,GuoFu Zhu,Hua Zhang,ZhiQuan Liu,Yan Liu,ZhaoRong Zhuang
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0416-0
Abstract: The scientific design and preliminary results of the data assimilation component of the Global-Regional Prediction and Assimilation System (GRAPES) recently developed in China Meteorological Administration (CMA) are presented in this paper. This is a three-dimensional variational (3DVar) assimilation system set up on global and regional grid meshes favorable for direct assimilation of the space-based remote sensing data and matching the frame work of the prediction model GRAPES. The state variables are assumed to decompose balanced and unbalanced components. By introducing a simple transformation from the state variables to the control variables with a recursive or spectral filter, the convergence rate of iteration for minimization of the cost function in 3DVar is greatly accelerated. The definition of dynamical balance depends on the characteristic scale of the circulation considered. The ratio of the balanced to the unbalanced parts is controlled by the prescribed statistics of background errors. Idealized trials produce the same results as the analytic solution. The results of real data case studies show the capability of the system to improve analysis compared to the traditional schemes. Finally, further development of the system is discussed.
Direct assimilation of satellite radiance data in GRAPES variational assimilation system
GuoFu Zhu,JiShan Xue,Hua Zhang,ZhiQuan Liu,ShiYu Zhuang,LiPing Huang,PeiMing Dong
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0419-x
Abstract: Variational method is capable of dealing with observations that have a complicated nonlinear relation with model variables representative of the atmospheric state, and so make it possible to directly assimilate such measured variables as satellite radiance, which have a nonlinear relation with the model variables. Assimilation of any type of observations requires a corresponding observation operator, which establishes a specific mapping from the space of the model state to the space of observation. This paper presents in detail how the direct assimilation of real satellite radiance data is implemented in the GRAPES-3DVar analysis system. It focuses on all the components of the observation operator for direct assimilation of real satellite radiance data, including a spatial interpolation operator that transforms variables from model grid points to observation locations, a physical transformation from model variables to observed elements with different choices of model variables, and a data quality control. Assimilation experiments, using satellite radiances such as NOAA17 AMSU-A and AMSU-B (Advanced Microwave Sounding Unit), are carried out with two different schemes. The results from these experiments can be physically understood and clearly reflect a rational effect of direct assimilation of satellite radiance data in GRAPES-3DVar analysis system.
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