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Search Results: 1 - 10 of 56652 matches for " XU Ji "
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Distribution, Transition and Thermodynamic Stability of Protein Conformations in the Denaturant-Induced Unfolding of Proteins
Liujiao Bian, Xu Ji
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091129
Abstract: Background Extensive and intensive studies on the unfolding of proteins require appropriate theoretical model and parameter to clearly illustrate the feature and characteristic of the unfolding system. Over the past several decades, four approaches have been proposed to describe the interaction between proteins and denaturants, but some ambiguity and deviations usually occur in the explanation of the experimental data. Methodology/Principal Findings In this work, a theoretical model was presented to show the dependency of the residual activity ratio of the proteins on the molar denaturant concentration. Through the characteristic unfolding parameters ki and Δmi in this model, the distribution, transition and thermodynamic stability of protein conformations during the unfolding process can be quantitatively described. This model was tested with the two-state unfolding of bovine heart cytochrome c and the three-state unfolding of hen egg white lysozyme induced by both guanidine hydrochloride and urea, the four-state unfolding of bovine carbonic anhydrase b induced by guanidine hydrochloride and the unfolding of some other proteins induced by denaturants. The results illustrated that this model could be used accurately to reveal the distribution and transition of protein conformations in the presence of different concentrations of denaturants and to evaluate the unfolding tendency and thermodynamic stability of different conformations. In most denaturant-induced unfolding of proteins, the unfolding became increasingly hard in next transition step and the proteins became more unstable as they attained next successive stable conformation. Conclusions/Significance This work presents a useful method for people to study the unfolding of proteins and may be used to describe the unfolding and refolding of other biopolymers induced by denaturants, inducers, etc.
Leading Tree in DPCLUS and Its Impact on Building Hierarchies
Ji Xu,Guoyin Wang
Computer Science , 2015,
Abstract: This paper reveals the tree structure as an intermediate result of clustering by fast search and find of density peaks (DPCLUS), and explores the power of using this tree to perform hierarchical clustering. The array used to hold the index of the nearest higher-densitied object for each object can be transformed into a Leading Tree (LT), in which each parent node P leads its child nodes to join the same cluster as P itself, and the child nodes are sorted by their gamma values in descendant order to accelerate the disconnecting of root in each subtree. There are two major advantages with the LT: One is dramatically reducing the running time of assigning noncenter data points to their cluster ID, because the assigning process is turned into just disconnecting the links from each center to its parent. The other is that the tree model for representing clusters is more informative. Because we can check which objects are more likely to be selected as centers in finer grained clustering, or which objects reach to its center via less jumps. Experiment results and analysis show the effectiveness and efficiency of the assigning process with an LT.
A Latent Gaussian Process Model with Application to Monitoring Clinical Trials
Yanxun Xu,Yuan Ji
Statistics , 2014,
Abstract: In many clinical trials treatments need to be repeatedly applied as diseases relapse frequently after remission over a long period of time (e.g., 35 weeks). Most research in statistics focuses on the overall trial design, such as sample size and power calculation, or on the data analysis after trials are completed. Little is done to improve the efficiency of trial monitoring, such as early termination of trials due to futility. The challenge faced in such trial monitoring is mostly caused by the need to properly model repeated outcomes from patients. We propose a Bayesian trial monitoring scheme for clinical trials with repeated and potentially cyclic binary outcomes. We construct a latent Gaussian process (LGP) to model discrete longitudinal data in those trials. LGP describes the underlying latent process that gives rise to the observed longitudinal binary outcomes. The posterior consistency property of the proposed model is studied. Posterior inference is conducted with a hybrid Monte Carlo algorithm. Simulation studies are conducted under various clinical scenarios, and a case study is reported based on a real-life trial.
One-Pot Synthesis of Dimethyl Carbonate over Basic Zeolite Catalysts  [PDF]
Wenshuai Xu, Shengrong Ji, Wei Quan, Jianqiang Yu
Modern Research in Catalysis (MRC) , 2013, DOI: 10.4236/mrc.2013.22A004
Abstract:

One-pot synthesis of dimethyl carbonate (DMC) from methanol, propylene oxide (PO) and carbon dioxide has been investigated using the basic zeolites as catalysts. Among the zeolites studied, Beta showed the best catalytic performance for DMC production. That the desilication of zeolite structure resulted in a hierarchical porosity of Beta, leading to more amount of KOH can be loaded on the surface of zeolite and therefore enhancing the base strength of the catalyst was proposed to be the reason for improved catalytic performance.

Characteristics of Soil Organic Carbon, Total Nitrogen, and C/N Ratio in Chinese Apple Orchards  [PDF]
Shunfeng Ge, Haigang Xu, Mengmeng Ji, Yuanmao Jiang
Open Journal of Soil Science (OJSS) , 2013, DOI: 10.4236/ojss.2013.35025
Abstract:

Soil organic carbon and nitrogen are used as indexes of soil quality assessment and sustainable land use management. At the same time, soil C/N ratio is a sensitive indicator of soil quality and for assessing the carbon and nitrogen nutrition balance of soils. We studied the characteristics of soil organic carbon and total nitrogen by investigating a large number of apple orchards in major apple production areas in China. High apple orchard soil organic carbon content was observed in the provinces of Heilongjiang, Xinjiang, and Yunnan, whereas low content was found in the provinces of Shandong, Henan, Hebei, and Shaanxi, with the values ranging between 6.44 and 7.76 g·kg-1. Similar to soil organic carbon, soil total nitrogen content also exhibited obvious differences in the 12 major apple producing provinces. Shandong apple orchard soil had the highest total nitrogen content (1.26 g·kg-1), followed by Beijing (1.23 g·kg-1). No significant difference was noted between these two regions, but their total nitrogen content was significantly higher than the other nine provinces, excluding Yunnan. The soil total nitrogen content for Xinjiang, Heilongjiang, Hebei, Henan, and Gansu was between 0.87 and 1.03 g·kg-1, which was significantly lower than that in Shandong and Beijing, but significantly higher than that in Liaoning, Shanxi, and Shaanxi. Six provinces exhibited apple orchard soil C/N ratio higher than 10, including Heilongjiang (15.42), Xinjiang (13.38), Ningxia (14.45), Liaoning (12.24), Yunnan (11.03), and Gansu (10.63). The soil C/N ratio was below

Characterization and Synthesis Mechanism of Nanosilver/PAMPS Composites by Microwave  [PDF]
Guocai Xu, Shengtao Gao, Xiaoli Ji, Xiaomei Zhang
Soft Nanoscience Letters (SNL) , 2014, DOI: 10.4236/snl.2014.42003
Abstract: Nanosilver/Poly(2-acrylamido-2-methylpropanesulfonate sodium (AMPS)) composites were synthesized with sliver nitrate solution containing AMPS monomer in situ by microwave radiation without addition of any reducer. The composites were characterized by means of UV-Vis, XRD, FTIR, TEM and XPS respectively. The results show that silver nanoparticles are dispersed highly and homogeneously in PAMPS matrix and possessed face-centered cubic structure. The morphology of nanosilver particles is not affected by microwave treatment and AMPS polymerization. XPS analysis reveals that there is an interaction among silver nanoparticles with nitrogen atoms and carbonyl oxygen atoms from AMPS polymer. Thermoanalysis proves that thermal stability of the PAMPS nanocomposites is decreasing with silver nanoparticles dispersed in the composites. The mechanism of silver ion reduced to nanosilver particles catalysized by PAMPS under microwave is discussed.
Study on Precipitation Forecast and Testing Methods of Numerical Forecast in Fuxin Area  [PDF]
Xu Zhang, Ji Liu, Yue Gao, Xiaotong Yang
Journal of Geoscience and Environment Protection (GEP) , 2017, DOI: 10.4236/gep.2017.57004
Abstract: This research uses Japan facsimile data in May-September of 2011-2015 in Fumeng and Zhangwu County of Fuxin, Liaoning, China as the site selection for high altitude NECV circulation background, using statistical and synoptic methods testing the combination of test and Analysis on Japanese numerical precipitation prediction and error. The prediction equation of cold vortex precipitation in the region is established by SPSS software. It is predicted whether the product predicts precipitation, water vapor condition and vertical velocity according to the Japanese numerical forecast. The results show that the fitting rate is 88% in the past 5 years, and the rate of cold vortex precipitation in the summer of 2016 is 89%.
A Biosecure Composting System for Tilletia controversa Kühn-Infected Wheat Waste  [PDF]
Ji-Juan Cao, Dong-Mei Cao, Yang Xu, Li-Ji Jin
Advances in Microbiology (AiM) , 2013, DOI: 10.4236/aim.2013.32021
Abstract:

Tilletia controversa Kühn (TCK) has strong infectivity and viability and may cause great cut hazard to wheat and other crops. Composting treatment of TCK-infected wheat waste may be an effective method to eliminate the further contamination. This study applied microbial fermentation composting technique using mixed crop straws and manure to establish a bio-friendly composting method. The change of physicochemical properties of the compost was monitored regularly to detect the time course of TCK degradation and confirm the inactivation of TCK germination activity. The results of regular sampling indicate that the germination rate of TCK declines with the composting progress, and composting ten days under the condition of 50 to 60 completely inactivates the germination ability of TCK. Thus the present study provides a bio-friendly composting method for degrading TCK-infected wheat crops under TCK outbreak.

Phase-Dependent Effects in Stern-Gerlach Experiments

XU Xu,ZHOU Xiao-Ji,

中国物理快报 , 2010,
Abstract: In the frame of quantum mechanics, we consider an ensemble of spin-1/2 neutral particles passing through a Stern-Gerlach apparatus and explore how their motions depend on the initial phase difference between two internal spin states. Assuming the particles moving along y-axis, due to the initial phase difference between spin states, they not only split along the longitudinal direction (z-axis) but also separate along the lateral direction (x-axis). The dependence of the lateral displacement on the initial phase difference reminds one of the picture of a quantum interference. This generalized interference provides an alternative approach to measuring the initial phase difference. The experimental realization with ultracold atoms or Bose-Einstein condensates is also discussed.
2-Chloro-5-({[5-(4-methoxyphenyl)-1,3,4-oxadiazol-2-yl]sulfanyl}methyl)pyridine
Hao Ji,Xu-Dong Xu
Acta Crystallographica Section E , 2011, DOI: 10.1107/s1600536811050410
Abstract: In the title compound, C15H12ClN3O2S, the central oxadiazole ring forms dihedral angles of 7.72 (14) and 69.86 (12)° with the benzene and pyridine rings, respectively. The crystal packing is governed only by van der Waals interactions.
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