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Search Results: 1 - 10 of 28234 matches for " DongFei Sun "
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Boundary Induced Inductive Delay in Transmission of Electromagnetic Signals  [PDF]
Yong Yang, Mingzhi Li, Yan Sun, Dongfei Pei, Shengyong Xu
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2012, DOI: 10.4236/jemaa.2012.44020
Abstract: When an electromagnetic signal transmits through a coaxial cable, it propagates at speed determined by the dielectrics of insulator between the cooper core wire and the metallic shield. However, we demonstrate here that, once the shielding layer of the coaxial cable is cut into two parts leaving a small gap, while the copper core wire is still perfectly connected, a remarkable transmission delay immediately appears in the system. We have revealed by both computational simulation and experiments that, when the gap spacing between two parts of the shielding layer is small, this delay is mostly determined by the overall geometrical parameters of the conductive boundary which connects two parts of the cut shielding layer. A reduced analytic formula for the transmission delay related with geometrical parameters, which is based on an inductive model of the transmission system, matches well with the fitted formula of the simulated delay. This above structure is analog to the situation that an interconnect is between two inter-modules in a circuit. The results suggest that for high speed circuits and systems, parasitic inductance should be taken into full consideration, and compact conductive packaging is favorable for reducing transmission delay of inter-modules, therefore enhancing the performance of the system.
Preparation and cytocompatibility of polylactic acid/hydroxyapatite/graphene oxide nanocomposite fibrous membrane
HaiBin Ma,WenXin Su,ZhiXin Tai,DongFei Sun,XingBin Yan,Bin Liu,QunJi Xue
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-012-5336-3
Abstract: A series of polylactic acid (PLA) based nanocomposite fibrous membranes, including neat PLA, PLA/hydroxyapatite (HA) and PLA/HA/graphene oxide (GO), were fabricated via electrospinning method. The morphology and composition were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) respectively. The thermal stability was determined by thermogravimetric analysis (TGA). To estimate the cytocompatibility of asprepared PLA/HA/GO fibrous membrane, MC3T3-E1 cells were cultured, and the corresponding cell adhesion and differentiation capability were investigated by fluorescence microscopy, SEM and MTT test. The electrospun ternary PLA/HA/GO membrane exhibited three-dimensional fibrous structure with relatively rough surface morphology, which made itself ideal for cell attachment and proliferation in bone tissue regeneration. The fluorescence microscopy, SEM and MTT test confirmed that the PLA/HA/GO nanocomposite fibrous membrane created a proper environment for the seeding and proliferation of MC3T3-E1 cells.
Characterization of a Self-sufficient Trans-Anethole Oxygenase from Pseudomonas putida JYR-1
Dongfei Han, Michael J. Sadowsky, Youhoon Chong, Hor-Gil Hur
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0073350
Abstract: A novel flavoprotein monooxygenase, trans-anethole oxygenase (TAO), from Pseudomonas putida JYR-1, which is capable of catalyzing the oxidation of trans-anethole to p-anisaldehyde, was heterologously expressed in E. coli and purified. Enzymatic kinetics of diverse substrates and cofactors revealed that TAO is likely to be a novel self-sufficient flavoprotein monooxygenase. Enzyme assays of GST-TAO demonstrated that TAO catalyzed a trans-anethole oxidation reaction without auxiliary component enzyme-like electron-transfer flavin reductases. The single component TAO had the ability to reduce flavin cofactors and simultaneously oxidize trans-anthole to p-anisaldehyde. In the processes of reduction of flavin and oxidation of trans-anethole, TAO accepted various flavin and NAD(P)H cofactors. TAO also catalyzed oxidation of isoeugenol, O-methyl isoeugenol, and isosafrole, all of which contain the 2-propenyl functional group on the aromatic ring structure with different catalytic efficiency. TAO had the greatest catalytic efficiency (kcat/Km) with the original substrate, trans-anethole. Investigation about partially deleted mutants of TAO indicated that reductase active sites appeared to be located near the N terminal. Site directed mutagenesis studies also proved that the proposed flavin binding sites, Trp-38, Thr-43, Tyr-55, were critical for flavin reduction. However, disruption of any portion of TAO eliminated the oxygenase activity.
MCP-1 Upregulates Amylin Expression in Murine Pancreatic β Cells through ERK/JNK-AP1 and NF-κB Related Signaling Pathways Independent of CCR2
Kun Cai,Dongfei Qi,Xinwei Hou,Oumei Wang,Juan Chen,Bo Deng,Lihua Qian,Xiaolong Liu,Yingying Le
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0019559
Abstract: Amylin is the most abundant component of islet amyloid implicated in the development of type 2 diabetes. Plasma amylin levels are elevated in individuals with obesity and insulin resistance. Monocyte chemoattractant protein-1 (MCP-1, CCL2) is involved in insulin resistance of obesity and type 2 diabetes. We investigated the effect of MCP-1 on amylin expression and the underlying mechanisms with murine pancreatic β-cell line MIN6 and pancreatic islets.
Study on the effect of calcine temperature and additives on aluminum oxide extraction from coal gangue

Cui Li,Wang Dongfei,Zhang Juncai,Cheng Fangqin,

环境工程学报 , 2009,
Abstract: Coal gangue is industrial residue that is discharged when coal is excavated and washed in the production course of coal mine,and is one of industrial solid wastes with biggest discharge.Aluminum oxide(Al2O3),silicon dioxide(SiO2),carbon(C) account for more than 90% of coal gangue;so coal gangue can be used.In this paper,in order to explore the mechanism of coal gangue activation,scanning electronic microscope(SEM),infrared(IR),X-ray diffraction(XRD) measurement were used to systematically study calcined coa...
Formal Derivation of the Combinatorics Problems with PAR Method  [PDF]
Lingyu SUN, Yatian SUN
Journal of Software Engineering and Applications (JSEA) , 2009, DOI: 10.4236/jsea.2009.23026
Abstract: Partition-and-Recur (PAR) method is a simple and useful formal method. It can be used to design and testify algo-rithmic programs. In this paper, we propose that PAR method is an effective formal method on solving combinatorics problems. Furthermore, we formally derive combinatorics problems by PAR method, which cannot only simplify the process of algorithmic program's designing, but also improve its automatization, standardization and correctness. We develop algorithms for two typical combinatorics problems, the number of string scheme and the number of error per-mutation scheme. Lastly, we obtain accurate C++ programs which are transformed by automatic transforming system of PAR platform.
Accuracy Improvement of PLIC-VOF Volume-Tracking Method Using the Equation of Surface Normal Vector  [PDF]
Mingyu Sun
Advances in Pure Mathematics (APM) , 2013, DOI: 10.4236/apm.2013.31A031

The PLIC/SN method that combines the second-order volume tracking method (PLIC-VOF) with the equation of surface normal (SN) vector was recently proposed (M. Sun, Volume Tracking of Subgrid Particles, International Journal for Numerical Methods in Fluids, Vol. 66, No. 12, 2011, pp. 1530-1554). The method is able to track the motion of a subgrid particle, but the accuracy is not as good as expected on high resolution grids for vortical flows. In this paper, a simple unsplit multidimensional advection algorithm is coupled with the equation of SN vector. The advection algorithm is formulated as the finite volume method, so that it can be used readily for both structured and unstructured grids while maintaining the exact mass conservation. The new method improves the accuracy significantly for high resolution grids. In the well-known test of the time-resolved vortex problem of T = 2, the circular interface is resolved with an accuracy better than ever using the equation of SN vector.

Positive Solutions for a Boundary Value Problem with a Derivative Argument  [PDF]
Bo Sun
Journal of Applied Mathematics and Physics (JAMP) , 2013, DOI: 10.4236/jamp.2013.14014

In this paper, several existence results of multiple positive solutions are obtained for a boundary value problem with p-Laplacian, by applying a fixed point theorem in cones. The interesting point is that the nonlinear term f is involved with the first-order derivative explicitly.

Is Urban China’s CPI Underreported?  [PDF]
Sun Wenkai
Chinese Studies (ChnStd) , 2013, DOI: 10.4236/chnstd.2013.24024
Abstract: Many have doubts about statistics, including the consumer price index (CPI) released by Chinese Government. We re-estimate the CPI in urban China from 1997 to 2009, with two widely accepted approaches to treating owner-occupied housing (i.e., user cost approach and consumption cost approach). The results are not considerably different from the NBS statistics, especially for recent years.
Retrospect and Prospect of the Research into Chinese Hezhe Nationality  [PDF]
Yan Sun
Open Journal of Social Sciences (JSS) , 2014, DOI: 10.4236/jss.2014.28020
Abstract: Through the scientometric analysis of these sample documents is related to the ten-year academic researches on Chinese Hezhe nationality, it could find out that the continuous study in this field provides a solid intelligence support for the development of Chinese ethnic minorities. However, problems still exist for the present, that is, the research content need to be deepened while the research perspective is expanded. And what’s more, the lack of the comparative analysis and the empirical research also should be given more attention in the future study. This essay would like to focus on the existing disadvantages by strengthening the problem consciousness which can help improve the researchers’ concern over the Hezhe nationality, reinforce the comparative analysis and empirical research, enhance the comprehensive analysis of multi-disciplinary and multi-perspective and constantly promote the further development of the research in this field.
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