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Now showing items 113 - 128 of 348

  • [IEEE 2017 IEEE 14th International Conference on Wearable and Implantable Body Sensor Networks (BSN) - Eindhoven, Netherlands (2017.5.9-2017.5.12)] 2017 IEEE 14th International Conference on Wearable and Implantable Body Sensor Networks (BSN) - A wearable sensor system for neonatal seizure monitoring

    Chen, Hongyu   Gu, Xiao   Mei, Zhenning   Xu, Ke   Yan, Kai   Lu, Chunmei   Wang, Laishuan   Shu, Feng   Xu, Qixin   Bambang Oetomo, Sidarto   Chen, Wei  

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  • Fluctuation-assisted nucleation in the phase separation/crystallization of iPP/OBC blends

    Jin, Jing   Du, Jiang   Chen, Hongyu   Han, Charles C.  

    This work mainly focused on the nucleation behavior in iPP/OBC (isotactic polypropylene/polyolefin block copolymers) blends with two distinct OBCs. The influence of composition and molecular structure of the OBC component on the crystallization kinetics of the blends was investigated systematically with the aim to better understand the interplay between the two coupled phase transitions in the blends: macrophase separation and crystallization. The isothermal crystallization kinetics showed component and composition dependence in iPP/OBC blends. All the blends in the studied range have enhanced nucleation ability of iPP than the pure iPP under identical conditions. Furthermore, the distinct macrophase separation morphology resulting from the different compatibility between the various OBCs and iPP caused remarkable diversity between the blends: the nuclei density is qualitatively higher (or the nucleation rate is qualitatively faster) in the more compatible blends, and this enhancement of nucleation can be depressed by imposing a macrophase separation process before crystallization. The crystal nuclei from the phase separated matrix were preferentially formed at the interface of the phase domains, and then grew toward and into the iPP-rich phase. It is postulated that the increased nuclei density and/or nucleation rate followed the fluctuation-assisted nucleation mechanism: the enhanced concentration fluctuation at the interfacial area created by the spinodal decomposition played an important role in the nucleation behavior of iPP/OBC blends. The decreased interface areas with increased domain sizes after deeper phase separation, coupled with a more depressed concentration fluctuation, are responsible for lower nuclei density after long time annealing for phase separation. (C) 2011 Elsevier Ltd. All rights reserved.
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  • Hollow Spherical Nanoshell Arrays of 2D Layered Semiconductor for High-Performance Photodetector Device

    Chen, Xiaoshuang   Yang, Huihui   Liu, Guangbo   Gao, Feng   Dai, Mingjin   Hu, Yunxia   Chen, Hongyu   Cao, Wenwu   Hu, PingAn   Hu, Wenping  

    Well-defined hollow spherical nanoshell arrays of 2D transitional metal dichalcogenide (TMDC) nanomaterials for MoSe2 and MoS2 are grown via chemical vapor deposition technique for the first time. The hollow sphere arrays display the uniform dimensions of approximate to 450 nm with the shell thickness of approximate to 10 nm. The unique hollow sphere architecture with increased active surface area is forecasted to supply more efficient route to improve light-harvesting efficiency through repeated light reflection and scattering inside the hollow structure without decay of response and recovery speed, because exceptional "SP-SP" junction barriers conducting mechanism can facilitate carriers tunneling and transport during the electron transfer procedure within the present particular structure. The MoSe2 hollow sphere photodetector exhibits an outstanding responsivity (8.9 A W-1), which is tenfold higher than that for MoSe2 compact film (0.9 A W-1), fast response and recovery speed, and good durability under illumination wavelength of 365 nm. Meanwhile, MoSe2 hollow sphere arrays on flexible polyethylene terephthalate substrates reveal excellent bending stability. Therefore, this research indicates that unique hollow sphere architecture of 2D TMDC materials will be an anticipated avenue for efficient photodetector devices with far-ranging capability.
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  • New insight of tertiary-amine modified bentonite amendment on the nitrogen transformation and volatile fatty acids during the chicken manure composting

    Ren, Xiuna   Awasthi, Mukesh Kumar   Wang, Quan   Li, Zhao Ronghua   Tu, Zhineng   Chen, Hongyu   Awasthi, Sanjeev Kumar   Zhang, Zengqiang  

    In this study, the main objective was to investigate the potential effect of tertiary-amine modified bentonite (TAMB) on the nitrogen transformation and the volatile fatty acids (VFAs) degradation during the chicken manure (CM) composting. Six dosages of TAMB (0%, 2%, 4%, 6%, 8% and 10%) were amended into the mixture of CM and wheat straw and then composted for 50 days. The results revealed the TAMB amendment could prolong the thermophilic phase and enhance the organic matter (OM) degradation. With the increasing dosage of TAMB, the ammonia volatilization was reduced by 15.41%-65.35%. Meanwhile, the TAMB addition had a positive effect on VFAs degradation and reducing odor unitMAx (OUMAX) by 17.61%-59.24%. Moreover, CH4 was reduced by 12.15%-32.78% in TAMB applied treatments compared to control. Finally, combined with all results, it indicated that TAMB amendment could reduce VFAs, CH4 emission and nitrogen loss to improve the compost quality.
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  • A multilayered regulatory mechanism for the autoinhibition and activation of a plant CC-NB-LRR resistance protein with an extra N-terminal domain

    Chen, Xiaojiao   Zhu, Min   Jiang, Lei   Zhao, Wenyang   Li, Jia   Wu, Jianyan   Li, Chun   Bai, Baohui   Lu, Gang   Chen, Hongyu   Moffett, Peter  

    The tomato resistance protein Sw-5b differs from the classical coiled-coil nucleotide-binding leucine-rich repeat (CC-NB-LRR) resistance proteins by having an extra N-terminal domain (NTD). To understand how NTD, CC and NB-LRR regulate autoinhibition and activation of Sw-5b, we dissected the function(s) of each domain. When viral elicitor was absent, Sw-5b LRR suppressed the central NB-ARC to maintain autoinhibition of the NB-LRR segment. The CC and NTD domains independently and additively enhanced the autoinhibition of NB-LRR. When viral elicitor was present, the NB-LRR segment of Sw-5b was specifically activated to trigger a hypersensitive response. Surprisingly, Sw-5b CC suppressed the activation of NB-LRR, whereas the extra NTD of Sw-5b became a positive regulator and fully activated the resistance protein, probably by relieving the inhibitory effects of the CC. In infection assays of transgenic plants, the NB-LRR segment alone was insufficient to confer resistance against Tomato spotted wilt tospovirus; the layers of NTD and CC regulation on NB-LRR were required for Sw-5b to confer resistance. Based on these findings, we propose that, to counter the negative regulation of the CC on NB-LRR, Sw-5b evolved an extra NTD to coordinate with the CC, thus developing a multilayered regulatory mechanism to control autoinhibition and activation.
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  • Hexagonal boron nitride nanosheet for effective ambient N2 fixation to NH3

    Zhang, Ya   Du, Huitong   Ma, Yongjun   Ji, Lei   Guo, Haoran   Tian, Ziqi   Chen, Hongyu   Huang, Hong   Cui, Guanwei   Asiri, Abdullah M.   Qu, Fengli   Chen, Liang   Sun, Xuping  

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  • Boosting electrocatalytic N2 Reduction to NH3 on β-FeOOH by fluorine doping

    Zhu, Xiaojuan   Wang, Huanbo   Liu, Zaichun   Zhao, Runbo   Chen, Hongyu   Wang, Ting   Wang, Faxing   Luo, Yonglan   Wu, Yuping   Sun, Xuping  

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  • Boosting electrocatalytic N2 reduction by MnO2 with oxygen vacancies

    Zhang, Ling   Xie, Xiao-Ying   Wang, Huanbo   Ji, Lei   Zhang, Ya   Chen, Hongyu   Li, Ting Shuai   Luo, Yonglan   Cui, Ganglong   Sun, Xuping  

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  • Individual Ag Nanowire Dimer for Surface-Enhanced Raman Scattering

    Du, ChaoLing   You, YuMeng   Chen, Tao   Zhu, Yan   Hu, HaiLong   Shi, DaNing   Chen, HongYu   Shen, ZeXiang  

    We have investigated the polarization-dependent surface-enhanced Raman scattering (SERS) of an individual Ag nanowire (AgNW) dimer, which contains two parallel closely packed AgNWs with very different lengths. Similar cos(2) theta dependence of signal intensities with respect to the polarization angle theta of the incident laser was observed from the dimeric part and the parts of the body as well as the tip of the longer AgNW. The dimeric part was demonstrated to exhibit the strongest SERS effect. The results agree well with our numerical simulations of the electric field distributions using finite element method. The SERS enhancement mechanisms at different parts of the dimer were also discussed which are different in origin.
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  • Unconventional Chain-Growth Mode in the Assembly of Colloidal Gold Nanoparticles

    Wang, Hong   Chen, Liyong   Shen, Xiaoshuang   Zhu, Liangfang   He, Jiating   Chen, Hongyu  

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  • Analyte-triggered cyclic autocatalytic oxidation amplification combined with an upconversion nanoparticle probe for fluorometric detection of copper(II)

    Chen, Hongyu   He, Kaili   Li, Huan   Zhang, Youyu   Yao, Shouzhuo  

    The authors describe an upconversion nanoparticle-based (UCNP-based) fluorometric method for ultrasensitive and selective detection of Cu2+. The UCNPs show a strong emission band at 550 nm under near-infrared excitation at 980 nm. The principle of the strategy is that gold nanoparticles (AuNP) can quench the fluorescence of UCNP. In contrast, the addition of L-cysteine (Cys) can induce the aggregation of AuNP, resulting in a fluorescence recovery of the UCNPs. On addition of Cu2+, it oxidizes Cys to cystine and is reduced to Cu+. The Cu+ thusformed can be oxidized cyclically to Cu2+ by dissolved O-2, which catalyzes and recycles the whole reaction. Thus, the aggregation of AuNP is inhibited and the fluorescence recovered by Cys is quenched. Under the optimal condition, the quenching efficiency shows a good linear response to the concentrations of Cu2+ in the 0.4-40 nM range. The limit of detection is 0.16 nM, which is 5 orders of magnitude lower than the U.S. Environmental Protection Agency limit for Cu2+ in drinking water (20 mu M). The method has been further applied to monitor Cu2+ levels in real samples. The results of detection are well consistent with those obtained by atomic absorption spectroscopy.
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  • The electrochemical performances of a novel lead-sodium binary grid alloy for lead-acid batteries

    Tang, Liping   Li, Aiju   Chen, Hongyu   Li, He   Chen, Qian   Zhou, Huawen   Wei, Wenwu   Zhang, Wei   Hu, Jie   Dou, Chuanlong   Wang, Hui   Finlow, David  

    A series of Pb-Na alloys were synthesized by adding sodium to lead. Linear sweep voltammetry (LSV), cyclic voltammograms (CV), electrochemical impedance spectroscopy (EIS), open circuit potential (OCP), and other analytical methods were used to investigate the electrochemical performances of the Pb-Na alloys in 1.28 g cm(-3) H(2)SO(4) solution. The results indicate that the addition of sodium reduces the generation of PbO and PbSO(4) greatly during anodic process, inhibits the oxygen evolution reaction and accelerates the evolution of hydrogen, and the Pb-Na alloys have good cycle performance and corrosion resistance properties. The alloys retain the merits, whilst removing the flaws, of the pure grid, thereby providing a promising positive grid alloy for spirally wound lead acid batteries. Crown Copyright (c) 2011 Published by Elsevier Ltd. All rights reserved.
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  • Synthesis of brightly PEGylated luminescent magnetic upconversion nanophosphors for deep tissue and dual MRI imaging.

    Chen, Hongyu   Qi, Bin   Moore, Thomas   Colvin, Daniel C   Crawford, Thomas   Gore, John C   Alexis, Frank   Mefford, O Thompson   Anker, Jeffrey N  

    A method is developed to fabricate monodispersed biocompatible Yb/Er or Yb/Tm doped beta-NaGdF4 upconversion phosphors using polyelectrolytes to prevent irreversible particle aggregation during conversion of the precursor, Gd2 O(CO3 )2.H2 O:Yb/Er or Yb/Tm, to beta-NaGdF4 :Yb/Er or Yb/Tm. The polyelectrolyte on the outer surface of nanophosphors also provided an amine tag for PEGylation. This method is also employed to fabricate PEGylated magnetic upconversion phosphors with Fe3 O4 as the core and beta-NaGdF4 as a shell. These magnetic upconversion nanophosphors have relatively high saturation magnetization (7.0 emu g(-1) ) and magnetic susceptibility (1.7 * 10(-2) emu g(-1) Oe(-1) ), providing them with large magnetophoretic mobilities. The magnetic properties for separation and controlled release in flow, their optical properties for cell labeling, deep tissue imaging, and their T1 - and T2 -weighted magnetic resonance imaging (MRI) relaxivities are studied. The magnetic upconversion phosphors display both strong magnetophoresis, dual MRI imaging (r1 =3D 2.9 mM(-1) s(-1) , r2 =3D 204 mM(-1) s(-1) ), and bright luminescence under 1 cm chicken breast tissue. Copyright =C2=A9 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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  • Microstructure and composition homogeneity,tensile property,and underlying thermal physical mechanism of selective laser melting tool steel parts

    Chen, Hongyu   Gu, Dongdong   Dai, Donghua   Ma, Chenglong   Xia, Mujian  

    This paper systematically investigated the crystallization thermodynamics and dynamic process within melt pool of 5CrNi4Mo steel fabricated by selective laser melting (SLM). The experimental results in conjunction with finite element analysis (FEA) demonstrated that the nucleation rate during SLM process was determined by the combined effects of supercooling degree and transfer capacity of atoms near solid/liquid interface; variant nucleation rate in different region of melt pool caused microstructure heterogeneity. Chemical compositions, including Cr, Ni and C, were observed to be homogeneously distributed due to the rapid solidification of the material. Specimens built along different orientation exhibited discrepant tensile properties due to the different deformation mode during loading. All the as-fabricated SLM-processed tensile specimens showed unfavorable ductility due to heterogeneous microstructures and residual stress concentration. After post-vacuum heat treatment, for horizontally built specimens, the elongation was significantly elevated from 5.6-9.7% and the toughness was enhanced form 63.68 J/m(3) to 134.12 J/m(3). The tensile strength increased marginally from 1576 MPa to 1682 MPa. These promotions were mainly caused by pronounced relief of intrinsic residual stress and recrystallization effect.
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  • The Major Outer Membrane Protein MopB Is Required for Twitching Movement and Affects Biofilm Formation and Virulence in Two Xylella fastidiosa strains

    Chen, Hongyu   Kandel, Prem P.   Cruz, Luisa F.   Cobine, Paul A.   De la Fuente, Leonardo  

    MopB is a major outer membrane protein (OMP) in Xylella fastidiosa, a bacterial plant pathogen that causes losses on many economically important crops. Based on in silico analysis, the uncharacterized MopB protein of X. fastidiosa contains a b-barrel structure with an OmpA-like domain and a predicted calcium-binding motif. Here, MopB function was studied by mutational analysis taking advantage of the natural competence of X. fastidiosa. Mutants of mopB were constructed in two different X. fastidiosa strains, the type strain Temecula and the more virulent WM1-1. Deletion of the mopB gene impaired cell-to-cell aggregation, surface attachment, and biofilm formation in both strains. Interestingly, mopB deletion completely abolished twitching motility. Electron microscopy of the bacterial cell surface revealed that mopB deletion eliminated type IV and type I pili formation, potentially caused by destabilization of the outer membrane. Both mopB mutants showed reduced virulence using tobacco (Nicotiana tabacum) as a host under greenhouse conditions. These results suggest that MopB has pleiotropic functions in biofilm formation and twitching motility and is important for virulence of X. fastidiosa.
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  • Study on degradation of acid orange II in aqueous solution using one-dimensional MnO(2) nanorods

    Sun, Hongmei   Chen, Hongyu   Shu, Dong   Xie, Zhengyi   He, Chun   Peng, Liangbo  

    MnO(2) nanorods were prepared by the reaction of KMnO(4) and MnSO(4) in aqueous media and subsequently followed by hydrothermal methods. The structure and surface morphology of as-prepared powder were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD results indicated that the prepared MnO(2) possessed a-and g structure. SEM observations showed that the obtained MnO(2) powder possessed a well-defined one-dimensional nanorod-like shape 100nm wide and 700nm long. The surface area of the MnO(2) nanorods was 92m(2)g(-1). The degradation efficiency of MnO(2) nanorods towards the organic pollutants in aqueous solution was evaluated using acid orange II as a model dye. It was found that the degradation efficiency of MnO(2) nanorods was a function of initial acid orange II concentration, MnO(2) nanorods concentration, and the proton concentration. The apparent reaction orders for the initial acid orange II concentration, MnO(2) nanorods concentration and the proton concentration were determined to be -0.76, 0.37 and 0.12, respectively. It was found that the degradation efficiency for 60ppm acid orange II reached 99% with 0.5gL(-1) MnO(2) nanorods concentration at pH 2.0 after 60min, demonstrating its higher degradation efficiency in aqueous solution. The apparent activation energy of the degradation reaction of acid orange II was calculated to be 17.3kJmol(-1). Furthermore, MnO(2) nanorods were demonstrated to have superior durability during regeneration tests.
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