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Search Results: 1 - 10 of 81163 matches for " Weiwei Liu "
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Analysis of University Science Research Capability Elements and Evaluation Based on BP Neural Network  [PDF]
Weiwei Liu, Chunsheng Shi
Journal of Service Science and Management (JSSM) , 2008, DOI: 10.4236/jssm.2008.13030
Abstract: After analyzing effect elements of University Science Research Capability (USRC) based on dynamic capability theory, combined the substance of university science research with the highly self-organized, self-adapted and self-learned characteristics of Back Propagation (BP) Neural Network, the paper conducts a research on evaluation of USRC, in which an evaluation index system of USRC is constructed and a 15-7-1-typed BP Neural Network with three layers is presented to evaluate USRC, which provides a BP Neural Network-based methodology for evaluation of USRC with multiple inputs.
Philosophy Thoughts Affect Costume
Weiwei Liu
Asian Social Science , 2009, DOI: 10.5539/ass.v4n6p129
Abstract: Apart from beautifying and protecting human body, costume itself is a symbol of culture and an image of some thoughts. Furthermore, different origins of Western and Eastern civilizations and various cultures for thousands of years have created distinctive varieties in costume. In Chinese history of apparel, whether the two forms of yi and shang (upper garment and the lower garment), i.e. skirts, or shenyi, i.e. qunju usually worn by women, and the later changes in color or in structure or in details, costume has been deeply affected by Confucianism, Taoism and Buddhism and other traditional Chinese thoughts. Among them, Confucianism has given the greatest. The Western costume is completely different from that of China. Westerners have paid more attention to the pursuit of their own natural beauty, the rational exploration and the worship of religion and theology.
Donkey’s Story: A Study on the Changes of Ecology, Economy and Culture Based on the Change of Donkey Populations of Four Communities in Central TAR  [PDF]
Yang Weiwei, Liu Yinghua, Luorong Zhandui
Chinese Studies (ChnStd) , 2013, DOI: 10.4236/chnstd.2013.24026
Abstract: Based on long time field study in Tibetan communities in central Tibet Autonomous Region (TAR) and empirical knowledge, through analyzing the population change of donkeys of different communities, this article aims at finding the reasons of the changes caused by economic and social changes, especially changes in eco-environment, in order to provide a perspective to better understand changes in TAR.
A Simple Strategy for Capturing the Unstable Steady Solution of an Unsteady Flow  [PDF]
Weiwei Zhang, Yilang Liu, Jing Li
Open Journal of Fluid Dynamics (OJFD) , 2015, DOI: 10.4236/ojfd.2015.52021
Abstract: A simple strategy for capturing unstable steady solution is proposed in this paper. By enlarging the real time step, the unstable high frequency modes of the unsteady flow can be effectively suppressed because of the damping action on the real time level. The steady component will not be changed during real time marching. When the unsteady flow solution converges to a steady state, the partial derivatives of real time in unsteady governing equations will disappear automatically. The steady solution is the exacted unstable steady solution. The method is validated by the laminar flow past a circular cylinder and a transonic buffet of NACA0012 airfoil. This approach can acquire high-precision unstable steady solutions quickly and effectively without reducing the spatial discretization accuracy. This work provides the basis for unstable flow modeling and analysis.
Distribution of 5-Hydroxymethylcytosine in Different Human Tissues
Weiwei Li,Min Liu
Journal of Nucleic Acids , 2011, DOI: 10.4061/2011/870726
Abstract: 5-hydroxymethylcytosine (5-hmC) is a modified form of cytosine recently found in mammalians and is believed, like 5-methylcytosine, to also play an important role in switching genes on and off. By utilizing a newly developed 5-hmC immunoassay, we determined the abundance of 5-hmC in human tissues and compared 5-hmC states in normal colorectal tissue and cancerous colorectal tissue. Significant differences of 5-hmC content in different tissues were observed. The percentage of 5-hmC measured is high in brain, liver, kidney and colorectal tissues (0.40–0.65%), while it is relatively low in lung (0.18%) and very low in heart, breast, and placenta (0.05-0.06%). Abundance of 5-hmC in the cancerous colorectal tissues was significantly reduced (0.02–0.06%) compared to that in normal colorectal tissues (0.46–0.57%). Our results showed for the first time that 5-hmC distribution is tissue dependent in human tissues and its abundance could be changed in the diseased states such as colorectal cancer. 1. Introduction DNA methylation is an epigenetic modification which is catalyzed by DNA cytosine-5-methyltransferases (DNMTs) and occurs at the 5-position (C5) of the cytosine ring, within CpG dinucleotides. DNA methylation is essential in regulating gene expression in nearly all biological processes including development, growth, and differentiation [1–3]. Alterations in DNA methylation have been demonstrated to cause the changes in gene expression. For example, hypermethylation leads to gene silencing or decreased gene expression while hypomethylation activates the genes or increases gene expression. Region-specific DNA methylation is mainly found in 5′-CpG-3′dinucleotides within the promoters or in the first exon of genes, which is an important pathway for the repression of gene transcription in diseased cells. Very recently, a modified nucleotide, 5-hydroxymethylcytosine (5-hmC) was detected to be abundant in mouse brain and embryonic stem cells [4–6]. 5-hmC is a hydroxylated and methylated form of cytosine and was first seen in bacteriophages in 1952 [7]. In mammals, it can be generated by a TET protein-mediated reaction [5]. The exact function of 5-hmC in epigenetics is still a mystery today. However, a line of evidence showed that conversion of 5-mC to 5-hmC greatly reduced affinity of MBD proteins to methylated DNA [8], and 5-hmC accounts for roughly 40 percent of the methylated cytosine in Purkinje cells and is also specifically localized in CpG regions [4]. Thus, 5-hmC might also play an important and different role in regulation of DNA methylation, chromatin
Interfacial Actions and Adherence of an Interpenetrating Polymer Network Thin Film on Aluminum Substrate  [PDF]
Weiwei Cui, Dongyan Tang, Jie Liu, Fan Yang
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2011, DOI: 10.4236/jsemat.2011.13013
Abstract: The interpenetrating polymer networks (IPN) thin film with the –C=O group in one network and the terminal –N=C=O group in another network on an aluminum substrate to reinforce the adherence between IPN and aluminum through interfacial reactions, were obtained by dip-pulling the pretreated aluminum substrate into the viscous-controlled IPN precursors and by the following thinning treatment to the IPN film to a suitable thickness. The interfacial actions and the adhesion strengths of the IPN on the pretreated aluminum substrate were investigated by the X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and strain-stress(?-?) measurements. The XPS and FTIR detection results indicated that the elements’ contents of N, O, and Al varied from the depths of IPN. The in-terfacial reaction occurred between the –N=C=O group of IPN and the AlO(OH) of pretreated aluminum. The in-creased force constant for –C=O double bond and the lower frequency shift of –C=O stretching vibration absorption peak both verified the formation of hydrogen bond between the –OH group in AlO(OH) and the –C=O group in IPN. The adherence detections indicated that the larger amount of –N=C=O group in the IPN, the higher shear strengths between the IPN thin film and the aluminum substrate.
Improvement in Structural and Magnetic Properties of Electrospun Ni1-xCuxFe2O4 Nanofibers  [PDF]
Weiwei Pan, Xinlei Zhang, Qin-Fang Liu, Jianbo Wang
Soft Nanoscience Letters (SNL) , 2017, DOI: 10.4236/snl.2017.72002
Abstract:
A series of Ni1-xCuxFe2O4 (0.0 ≤ x ≤ 1.0) nanofibers have been synthesized employing electrospinning method at 650°C. The effect of Cu substitution on structural, morphology and magnetic properties of NiFe2O4 nanofibers is reported. The XRD analysis showed the formation of single-phase cubic spinel Ni-Cu ferrite and an increasing behavior of lattice constant. The surface morphology is characterized by SEM, it is investigated that nanofibers have uniform and continuous morphology. The VSM results showed Cu substitution played an important role in magnetic properties of Ni1-xCuxFe2O4. The saturation magnetization (Ms) decreases linearly with increasing Cu2+ content, while coercivity (Hc) has slowly decreased before x ≤ 0.5, and then sharply increased to 723.9 Oe for x = 1.0. The magnetic properties of Ni1-xCuxFe2O4 can be explained in Neel’s model, cation distribution and shape anisotropy.
Graphical deployment strategies in radar sensor networks (RSN) for target detection
Ling Yang, Jing Liang and Weiwei Liu
EURASIP Journal on Wireless Communications and Networking , 2013, DOI: 10.1186/1687-1499-2013-55
Abstract: Nodes deployment is a major challenge to a successful implementation of radar sensor network (RSN). The goal of the deployment is to ensure that the target can achieve expected detection performance with high-energy efficiency. In this article, two deployment strategies, named Hexagonal Deployment Strategy (HDS) and Diamond Deployment Strategy (DDS), are proposed to solve this problem. Each Radar Sensor (RS), separately, obtains probability of target detection depending on the position of RS according to the deployment strategies. To appraise these two deployment strategies, two decision fusion rules are derived over pass-loss fading channel in multi-hop RSN. We combine these two decision fusion rules with unfixed local detection performance. Simulations results show that given a finite number of RSs, our proposed strategies are far superior to Random Deployment Strategy in terms of detection probability and energy consumption to satisfy detection and false alarm requirements. The DDS achieves higher probability of detection and consumption fewer energy than HDS, no matter in decision fusion rules with Binary Transmission (BT) or without Binary Transmission (NBT). The BT fusion rules performs better than NBT and the number of RS needed for expected detection performance is not the more the better.
Dimethyl(2-oxo-2-phenylethyl)sulfanium bromide
Zhiling Cao,Weiwei Liu,Fujun Yin
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810046404
Abstract: Single crystals of the title compound, C10H13OS+·Br , were obtained from ethyl acetate/ethyl ether after reaction of acetophenone with hydrobromic acid and dimethylsulfoxide. The carbonyl group is almost coplanar with the neighbouring phenyl ring [O—C—C—C = 178.9 (2)°]. The sulfanium group shows a trigonal–pyramidal geometry at the S atom. The crystal structure is stabilized by C—H...Br hydrogen-bonding interactions. Weak π–π interactions link adjacent phenyl rings [centroid–centroid distance = 3.946 (2) ].
Molecular Modeling Study on the Allosteric Inhibition Mechanism of HIV-1 Integrase by LEDGF/p75 Binding Site Inhibitors
Weiwei Xue, Huanxiang Liu, Xiaojun Yao
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0090799
Abstract: HIV-1 integrase (IN) is essential for the integration of viral DNA into the host genome and an attractive therapeutic target for developing antiretroviral inhibitors. LEDGINs are a class of allosteric inhibitors targeting LEDGF/p75 binding site of HIV-1 IN. Yet, the detailed binding mode and allosteric inhibition mechanism of LEDGINs to HIV-1 IN is only partially understood, which hinders the structure-based design of more potent anti-HIV agents. A molecular modeling study combining molecular docking, molecular dynamics simulation, and binding free energy calculation were performed to investigate the interaction details of HIV-1 IN catalytic core domain (CCD) with two recently discovered LEDGINs BI-1001 and CX14442, as well as the LEDGF/p75 protein. Simulation results demonstrated the hydrophobic domain of BI-1001 and CX14442 engages one subunit of HIV-1 IN CCD dimer through hydrophobic interactions, and the hydrophilic group forms hydrogen bonds with HIV-1 IN CCD residues from other subunit. CX14442 has a larger tert-butyl group than the methyl of BI-1001, and forms better interactions with the highly hydrophobic binding pocket of HIV-1 IN CCD dimer interface, which can explain the stronger affinity of CX14442 than BI-1001. Analysis of the binding mode of LEDGF/p75 with HIV-1 IN CCD reveals that the LEDGF/p75 integrase binding domain residues Ile365, Asp366, Phe406 and Val408 have significant contributions to the binding of the LEDGF/p75 to HIV1-IN. Remarkably, we found that binding of BI-1001 and CX14442 to HIV-1 IN CCD induced the structural rearrangements of the 140 s loop and oration displacements of the side chains of the three conserved catalytic residues Asp64, Asp116, and Glu152 located at the active site. These results we obtained will be valuable not only for understanding the allosteric inhibition mechanism of LEDGINs but also for the rational design of allosteric inhibitors of HIV-1 IN targeting LEDGF/p75 binding site.
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