5,200 research outputs found

    Controlled motion of electrically neutral microparticles by pulsed direct current

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    A controlled motion of electrically neutral microparticles in a conductive liquid at high temperatures has not yet been realized under the uniform direct electric current field. We propose a simple method, which employs pulsed direct current to a conductive liquid metal containing low-conductivity objects at high temperature. The electric current enables the low-conductivity particles to pass from the centre towards the various surfaces of the high-conductivity liquid metal. Most interestingly, the directionality of microparticles can be controlled and their speed can be easily regulated by adjusting pulsed current density. We find that the movement may arise from the configuration of electrical domains which generates a driving force which exceeds the force of gravity and viscous friction. All of these features are of potential benefit in separating the particles of nearly equal density but distinctly different electrical conductivities, and also offer considerable promise for the precise and selective positioning of micro-objects or the controlled motion of minute quantities of surrounding fluids

    A design for investigating the association of birth weight, weight change during life course with adult hypertension in Hong Kong women

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    Poster Presentation: P-6A-270"Fetal origins hypothesis" by Barker in 1990 is a well known hypothesis. One of the key finding was that low birth weight was associated with higher adult systolic blood pressure. However, in 2002, Huxley et al argued that birth weight had little relevance in determining blood pressure levels in later life. But after that, several studies argued against it until now. In addition, some experts think that change in size between birth and current rather than fetal biology itself affect the blood pressure, which means the fetal origins hypothesis must be weighed against a "postnatal origins hypothesis". Therefore, it is important to explore what is the interaction between later body weight change and fetal programming on the effect of BP ...published_or_final_versio

    Adaptive flocking of multi-agent systems with locally Lipschitz nonlinearity

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    This paper investigates adaptive flocking of multi-agent systems (MASs) with a virtual leader. All agents and the virtual leader share the same intrinsic nonlinear dynamics, which satisfies a locally Lipschitz condition and depends on both position and velocity information of the agent itself. Under the assumption that the initial network is connected, an approach to preserving the connectivity of the network is proposed. Based on the Lyapunov stability theory, an adaptive flocking control law is derived to make the MASs track the virtual leader without collision. Finally, a numerical example is presented to illustrate the effectiveness of the theoretical results. © 2012 Chinese Assoc of Automati.published_or_final_versio

    Enhanced performance of Si MOS capacitors with HfTaOxNy gate dielectric by using AlOxNy or TaOxNy interlayer

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    Si MOS capacitors with HfTa oxide and oxynitride as gate dielectric were fabricated. Moreover, AlOxNy or TaOxN y was used as the interlayer between HfTa oxynitride and Si substrate to improve the electrical quality of the capacitors. Experimental results showed that the HfTaOxNy capacitor with TaO xNy interlayer achieved better performance with larger capacitance and smaller leakage current than its counterpart with AlO xNy interlayer. © 2008 IEEE.published_or_final_versio

    Treatment time for non-surgical endodontic therapy with or without a magnifying loupe

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    Improved electrical properties of Ge p-MOSFET with HfO 2 gate dielectric by using TaO xN y interlayer

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    The electrical characteristics of germanium p-metal-oxide-semiconductor (p-MOS) capacitor and p-MOS field-effect transistor (FET) with a stack gate dielectric of HfO 2TaO xN y are investigated. Experimental results show that MOS devices exhibit much lower gate leakage current than MOS devices with only HfO 2 as gate dielectric, good interface properties, good transistor characteristics, and about 1.7-fold hole-mobility enhancement as compared with conventional Si p-MOSFETs. These demonstrate that forming an ultrathin passivation layer of TaO xN y on germanium surface prior to deposition of high- k dielectrics can effectively suppress the growth of unstable GeO x, thus reducing interface states and increasing carrier mobility in the inversion channel of Ge-based transistors. © 2008 IEEE.published_or_final_versio

    Comparative study of HfTa-based gate-dielectric Ge metal-oxide- semiconductor capacitors with and without AlON interlayer

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    The electrical properties and high-field reliability of HfTa-based gate-dielectric metal-oxide-semiconductor (MOS) devices with and without AlON interlayer on Ge substrate are investigated. Experimental results show that theMOS capacitor with HfTaON/AlON stack gate dielectric exhibits low interface-state/oxide-charge densities, low gate leakage, small capacitance equivalent thickness (∼1.1 nm), and high dielectric constant (∼20). All of these should be attributed to the blocking role of the ultrathin AlON interlayer against interdiffusions of Ge, Hf, and Ta and penetration of O into the Ge substrate, with the latter effectively suppressing the unintentional formation of unstable poorquality low-k GeO x and giving a superior AlON/Ge interface. Moreover, incorporation of N into both the interlayer and high-k dielectric further improves the device reliability under high-field stress through the formation of strong Nrelated bonds. © Springer-Verlag 2009.published_or_final_versionSpringer Open Choice, 01 Dec 201

    Genetic and phylogenetic analysis of ten Gobiidae species in China based on amplified fragment length polymorphism (AFLP) analysis

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    To study the genetic and phylogenetic relationship of gobioid fishes in China, the representatives of 10 gobioid fishes from 2 subfamilies in China were examined by amplified fragment length polymorphism (AFLP) analysis. We established 220 AFLP bands for 45 individuals from the 10 species, and the percentage of polymorphic bands was 100%. The percentage of polymorphic loci within species ranged from 3.61 to 58.56%. Chaeturichthys stigmatias showed the greatest percentage of polymorphic loci (58.56%), the highest Nei’s genetic diversity (0.2421 ± 0.2190) and Shannon’s information index (0.3506 ± 0.3092), while Pterogobius zacalles showed the lowest percentage polymorphic loci (3.61%), the lowest Nei’s genetic diversity (0.0150 ± 0.0778) and lowest Shannon’s information index (0.0219 ± 0.1136). The topology of UPGMA tree showed that the individuals from the same species clustered together and the 10 species formed two major clades. One clade consisted Cryptocentrus filifer, P. zacalles, Tridentiger trigonocephalus, Chaeturichthys hexanema, C. stigmatias, Acanthogobius flavimanus and Synechogobius ommaturus, and the other clade consisted Odontamblyopus rubicundus, Trypauchen vagina and Ctenotrypauchen microcephalus. The results agreed with the traditional taxonomy of the morphological characters. AFLP fingerprints were successfully used to study the phylogenetic relationship of the gobioid fishes and it identified species origins of morphologically similar taxa.Key words: Phylogenetic, amplified fragment length polymorphism (AFLP), gobiidae, Amblyopinae, gobiinae

    Cloning and characterization of a nitrite reductase gene related to somatic embryogenesis in Gossypium hirsutum

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    A nitrite reductase gene related to somatic embryogenesis was first cloned from Gossypium hirsutum. The cDNA sequence of the gene, named GhNiR, is 2,257 bp in length, with 254 bp of the 5’ untranslated region and 236 bp of the 3’ untranslated region. The open reading frame is 1,767 bp in length, encoding a deduced amino acid sequence of 588 residues with a molecular weight of 65.722 kDa and an isoelectric point of 7.07. Semi-quantitative RT-PCR analysis showed that the expression level of GhNiR was higher in embryogenic calli and somatic embryoids than in nonembryogenic calli among different somatic embryogenesis stages, and that the level of GhNiR mRNA was also higher in the cultivar with higher somatic embryogenesis ability. The catalytic GhNiR was verified by transformation in E. coli BL21 (DE3) strain with the recombinant expression vector pET-28A-GhNiR. NiR activity assay showedthat the crude GhNiR protein had obvious activity to NaNO2 substrate

    Electric current-driven migration of electrically neutral particles in liquids

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    We design and experimentally demonstrate a migration of electrically neutral particles in liquids driven by electric current according to the discrepancies of their electrical conductivities. A force from electric current to electrically neutral particles has been identified to drive the particles toward the lateral surface from the centre of suspension via three distinguishable zones, namely, pushing, trapping, and expelling zones. The driving force can overtake gravity in practical cases. The property of the force is found neither similar to that of the force in electromagnetophoresis nor similar to that of the electromigration force in terms of direction and magnitude. An expression for the force at the pushing zone has been developed based on the numerical calculation of the thermodynamics of suspension fluids. The excellent agreement between numerical calculations and experimental data demonstrates that our calculation provides fundamental and predictive insight into particles separation from the liquids. Therefore, it is possible to use the force in many engineering applications such as separation of particles according to the differences of their electrical conductivities
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