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Search Results: 1 - 10 of 120222 matches for " Wang Yadong "
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Carbon nanotube-based quantum pump in the presence of superconducting lead
Yadong Wei,Jian Wang
Physics , 2002, DOI: 10.1103/PhysRevB.66.195419
Abstract: Parametric electron pump through superconductor-carbon-nanotube based molecular devices was investigated. It is found that a dc current, which is assisted by resonant Andreev reflection, can be pumped out from such molecular device by a cyclic variation of two gate voltages near the nanotube. The pumped current can be either positive or negative under different system parameters. Due to the Andreev reflection, the pumped current has the double peak structure around the resonant point. The ratio of pumped current of N-SWNT-S system to that of N-SWNT-N system (I^{NS}/I^N) is found to approach four in the weak pumping regime near the resonance when there is exactly one resonant level at Fermi energy inside the energy gap. Numerical results confirm that in the weak pumping regime the pumped current is proportional to the square of the pumping amplitude V_p, but in the strong pumping regime the pumped current has the linear relation with V_p. Our numerical results also predict that pumped current can be obtained more easily by using zigzag tube than by using armchair tube.
A Co-verification Method Based on TWCNP-OS for Two-way Cable Network SOC  [PDF]
Chong LI, Xiaotong ZHANG, Yadong WAN, Qin WANG
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2008, DOI: 10.4236/ijcns.2008.12024
Abstract: Co-verification is the key step of software and hardware codesign on SOC. This paper presents a hw/sw co-verification methodology based on TWCNP-OS, a Linux-based operating system designed for FPGA-based platform of two-way cable network (TWCNP) SOC. By implementing HAL (hardware Abstraction level) specially, which is the communications interface between hardware and software, we offer a homogeneous Linux interface for both software and hardware processes. Hardware processes inherit the same level of service from kernel, as typical Linux software processes by HAL. The familiar and language independent Linux kernel interface facilitates easy design reuse and rapid application development. The hw/sw Architecture of TWCNP and design flow of TWCNP-OS are presented on detail. A software and hardware co-verification method using TWCNP-OS is proposed, through the integrated using of Godson-I test board and TWCNP, which realizes the combination of design and verification. It is not a replacement of the co-verification with generic RTOS modeling, but is complementary to them. Performance analysis of our current implementation and our experience with developing this system based on TWCNP-OS will be presented. Most importantly, since the introduction of TWCNP-OS to our FPGA-based platform, we have observed increased productivity among high-level application developers who have little experience in FPGA application design.
Cloning of multicopper oxidase gene from Ochrobactrum sp. 531 and characterization of its alkaline laccase activity towards phenolic substrates  [PDF]
Yang Li, Wenfeng Zuo, Yadong Li, Xingguo Wang
Advances in Biological Chemistry (ABC) , 2012, DOI: 10.4236/abc.2012.23031
Abstract: A 1602 bp fragment was cloned from a soil bacterium Ochrobactrum sp. 531. It contained an open reading frame (ORF) of 1092 bp which was identified as a multicopper oxidase (MCO) with potential laccase activity. After inserting the cloned gene into the expression vector pET23a, it was expressed in E. coli BL21(DE3)pLysS, and its product was purified to homogeneity through chromatography. The Ochrobactrum sp. 531 MCO, consisting of 533 amino acids with a molecular mass of 57.8 kDa, was quite stable in neutral pH and showed laccase-like activity oxidizing 2,6-dimethoxyphenol (DMP), 2,2’-azino-bis(3-ethylbe- nzthiazolinesulfonic acid) (ABTS), and syringaldazine (SGZ). The enzyme showed optimum activity towards DMP, ABTS, and SGZ at the pH 8.0, 3.6, and 7.5 respectively. Kinetic studies gave this enzyme Km, kcat and kcat//Km values of: 0.09 mM, 7.94 s–1, and 88.22 s–1?mM–1 for DMP; 0.072 mM, 2.95 s–1, and 40.97 s–1.mM–1 for ABTS; and 0.015 mM, 2.4 s–1, and 160 s–1.mM–1 for SGZ. Our results demonstrate that Ochrobactrum sp. 531 MCO is a bacterial laccase which oxidized phenolic substrates DMP and SGZ effectively under alkaline conditions. These unusual properties make the enzyme an interesting biocatalyst in applications for which classical laccases are unsuitable.
Grounding Impedance Measurement of High Speed Railway Integrated Grounding System  [PDF]
Zhang Yi, Jianguo Wang, Yadong Fan, Mi Zhou, Li Cai
Journal of Power and Energy Engineering (JPEE) , 2015, DOI: 10.4236/jpee.2015.34027

The high-speed railway integrated grounding system is the basic guarantee for the safe and stable operation of the railway. It is the world’s largest long-distance horizontally elongated joint grounding system, which stretches the length of hundreds to thousands of kilometers, and its structure is not only different from power station and substation grounding system, but also different from the transmission line tower, lightning rod and other small grounding devices. There is little research information on the grounding impedance of high-speed railway integrated grounding system. This paper adopted 0.618 compensation method and reverse away method respectively, measured a section of high-speed railway integrated grounding system grounding impedance by JD16 and CA6425. Measurement results are in good agreement using those two type instrument. By using 0.618 compensation method, the measurement result will be gradually converged at 0.3 Ω with the increasing of current electrode distance, which is the real grounding impedance of integrated grounding system. By using reverse away method, the maximum measurement result difference is less than 0.024 Ω with the lead of current electrode distance increasing. The measurement results will be rapidly converged 0.25 Ω. The results showed that the reverse away method is helpful to shorten the length of current electrode wiring. The measurement error will be small when the current electrode wiring is longer.

Controlled Delivery of Sonic Hedgehog Morphogen and Its Potential for Cardiac Repair
Noah Ray Johnson, Yadong Wang
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0063075
Abstract: The morphogen Sonic hedgehog (Shh) holds great promise for repair or regeneration of tissues suffering ischemic injury, however clinical translation is limited by its short half-life in the body. Here, we describe a coacervate delivery system which incorporates Shh, protects it from degradation, and sustains its release for at least 3 weeks. Shh released from the coacervate stimulates cardiac fibroblasts to upregulate the expression of multiple trophic factors including VEGF, SDF-1α, IGF-1, and Shh itself, for at least 48 hours. Shh coacervate also demonstrates cytoprotective effects for cardiomyocytes in a hydrogen peroxide-induced oxidative stress environment. In each of these studies the bioactivity of the Shh coacervate is enhanced compared to free Shh. These results warrant further investigation of the in vivo efficacy of Shh coacervate for cardiac repair.
Fully Complex Magnetoencephalography
Jonathan Z. Simon,Yadong Wang
Quantitative Biology , 2005, DOI: 10.1016/j.jneumeth.2005.05.005
Abstract: Complex numbers appear naturally in biology whenever a system can be analyzed in the frequency domain, such as physiological data from magnetoencephalography (MEG). For example, the MEG steady state response to a modulated auditory stimulus generates a complex magnetic field for each MEG channel, equal to the Fourier transform at the stimulus modulation frequency. The complex nature of these data sets, often not taken advantage of, is fully exploited here with new methods. Whole-head, complex magnetic data can be used to estimate complex neural current sources, and standard methods of source estimation naturally generalize for complex sources. We show that a general complex neural vector source is described by its location, magnitude, and direction, but also by a phase and by an additional perpendicular component. We give natural interpretations of all the parameters for the complex equivalent-current dipole by linking them to the underlying neurophysiology. We demonstrate complex magnetic fields, and their equivalent fully complex current sources, with both simulations and experimental data.
To Enhance Light Extraction for Organic Light-Emitting Diodes by Body Modification of Substrate
Jun Wang,Chong Wang,Yadong Jiang
International Journal of Photoenergy , 2013, DOI: 10.1155/2013/649564
Abstract: A facile approach of body modification on substrate is introduced to enhance the light extraction for organic devices. The lateral metal reflective film (LMRF) was coated on side of substrate and microlens array (MLA) was fabricated on forward surface of substrate. The two methods of improving light output are simulated and optimized to form body modification. The metal thin film was evaporated on the side of reversal trapezoid shape substrate to form LMRF layer and the MLA with semicircle shape was fabricated on the substrate using normal photolithography process. The external quantum efficiency of fabricated organic device with body modification is ~1.8 times higher than the device with normal substrate. 1. Introduction Organic light-emitting diodes (OLEDs) have shown tremendous potential in display and solid state lighting (SSL) applications because of their low power consumption, wide viewing angle, excellent color gamut, and fast response time [1–3]. Although an internal quantum efficiency of nearly 100% has been achieved [4, 5], the problem of low light extraction efficiency remains unresolved especially for illumination application [6, 7]. In conventional OLEDs, the refractive index mismatch at the ITO/glass and glass/air interfaces is large enough to induce the total internal reflection of a considerable portion of light coming from the emitting layer. Typically, the fraction of generated lights that is output into the forward viewing space for an OLED fabricated on planar glass is as low as 20% [8, 9]. To recover these waveguide modes, various techniques had been studied with the aim of improving the light output for OLEDs, including low-index grids [10, 11], periodic corrugated structure [12], Bragg mirrors [13], buckling patterns [14], photonic crystals [15], antireflection coatings [16], and monolayer of SiO2 microparticles [17]. Those methods focused on changing the contact surface of glass substrate with organic device and mere modification of the external surface of the glass substrate of the OLED to minimize the total internal reflection. The effectiveness of surface structures (different geometries and materials of microlens) for the light extraction enhancement has been explored by different authors. The microlens array (MLA) using prepolymer NOA65 material was fabricated on the substrate by microcontact printing of hydrophobic self-assembled monolayers, and the light outcoupling efficiency was improved by 24.5% without any apparent color change [18]. Spherical microlenses patterns using photoresist material were designed on the
Control Growth Factor Release Using a Self-Assembled [polycation∶heparin] Complex
Blaine J. Zern,Hunghao Chu,Yadong Wang
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0011017
Abstract: The importance of growth factors has been recognized for over five decades; however their utilization in medicine has yet to be fully realized. This is because free growth factors have short half-lives in plasma, making direct injection inefficient. Many growth factors are anchored and protected by sulfated glycosaminoglycans in the body. We set out to explore the use of heparin, a well-characterized sulfated glycosaminoglycan, for the controlled release of fibroblast growth factor-2 (FGF-2). Heparin binds a multitude of growth factors and maintains their bioactivity for an extended period of time. We used a biocompatible polycation to precipitate out the [heparin:FGF-2] complex from neutral buffer to form a release matrix. We can control the release rate of FGF-2 from the resultant matrix by altering the molecular weight of the polycation. The FGF-2 released from the delivery complex maintained its bioactivity and initiated cellular responses that were at least as potent as fresh bolus FGF-2 and fresh heparin stabilized FGF-2. This new delivery platform is not limited to FGF-2 but applicable to the large family of heparin-binding growth factors.
Mechanochemical synthesis and high-capacity performances of transition-metal borides as aqueous anode materials
YaDong Wang,XianYong Guang,Mu Pan
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-012-5070-x
Abstract: Transition-metal borides MB0.5 (M = Co, Mo, V) were synthesized by high-speed mechanical ball-milling of the corresponding elemental metals and boron, and investigated as aqueous anode materials. The as-synthesized borides can achieve an excellent discharge capacity, about twice that of their parent transition metals. The metal boride electrodes also exhibit polarizations about 100–300 mV lower than those of their parent metals. The galvanostatic discharge curve of CoB0.5 shows a single discharge voltage plateau as a result of simultaneous electro-oxidation of elemental cobalt and/or amorphous cobalt boride. Both MoB0.5 and VB0.5 show two well-defined voltage plateaus, corresponding to the electro-oxidation of the corresponding metal and boride. These results show that the coexisting transition metal and boride in the metal borides co-activate each other in the ball-milling process, thereby significantly enhancing their electrochemical performances.
The Minimum Feature Subset Selection Problem
Chen Bin,Hong Jiarong,Wang Yadong,
Chen Bin
,Hong Jiarong,Wang Yadong

计算机科学技术学报 , 1997,
Abstract: In applications of learning from examples to real-world tasks, feature subset selection is important to speed up training and to improve generalization performance. ideally, an inductive algorithm should use subset of features as small as possible. In this paper however, the authors show that the problem of selecting the minimum subset of features is NP-hard. The paper then presents a greedy algorithm for feature subset selection. The result of running the greedy algorithm on hand-written numeral recognition problem is also given.
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