Universities of Hunan Province

Changsha, China

Universities of Hunan Province

Changsha, China
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Zhao J.,Universities of Hunan Province | Chen X.,Universities of Hunan Province | Rong C.,Hunan Normal University | Yu L.,Universities of Hunan Province | And 3 more authors.
Journal of Rare Earths | Year: 2011

The establishment of an approach to design tunable yellow emission through singly doped single-phased phosphors to obtain white LED-based InGaN chip was reported. BaY2-xS4:xHo3+ phosphors were prepared by the high temperature solid state reaction and characterized by X-ray diffraction and photoluminescence spectra. Under the excitation of 465 nm, the emission spectra of these phosphors exhibited three sharp emission lines peaked at about 492, 543 and 661 nm of Ho3+ corresponding to 5F3, 5F4 (5S2) and 5F5→5I8 transitions, respectively, with comparable intensities, resulting in a yellow light emission. The luminescence mechanism for Ho3+ in BaY2S4 was explained. © 2011 The Chinese Society of Rare Earths.

Wang J.,Xiangtan University | Yan J.,Xiangtan University | Zhou H.,Xiangtan University | Huang H.,Xiangtan University | And 4 more authors.
Australian Journal of Chemistry | Year: 2016

Norbornene-functional poly(lactide)s backbone-based amphiphilic copolymer, P(LA-g-mOEG)-b-P(LA-SS-COOH), was synthesized as the polymeric scaffold and paclitaxel (PTX) was directly conjugated to the carboxyl groups of the amphiphilic copolymer to obtain redox-responsive P(LA-g-mOEG)-b-P(LA-SS-PTX) prodrugs. The dynamic light scattering and transmission electron microscopy analyses showed that P(LA-g-mOEG)-b-P(LA-SS-PTX) self-assembled into prodrug micelles with a diameter of 60-70nm and a low polydispersity in aqueous solution. Remarkably, in vitro release studies revealed that 80% of PTX was released in 72h under a reductive environment, whereas only 23% of PTX was released in 72h under non-reductive conditions. In addition, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays showed that P(LA-g-mOEG)-b-P(LA-SS-PTX) prodrug micelles retained high anti-tumour activity while polymer carriers were non-toxic up to a tested concentration of 1.0mg mL-1. These redox-responsive prodrug micelles have tremendous potential for anti-tumour drug delivery. © The Authors 2016.

Wang J.,Xiangtan University | Sun H.,Xiangtan University | Li D.,Xiangtan University | Yuan J.,Xiangtan University | And 4 more authors.
Australian Journal of Chemistry | Year: 2015

In this paper, poly(ε-caprolactone)-graft-carboxylic acid (P(α-C2CL)) was prepared via a thio-bromo click reaction between mercaptosuccinic acid and poly(α-bromo-ε-caprolactone). It is readily soluble in aqueous solutions (pH 5.5-9.8) due to the presence of carboxylic groups in each repeating unit. A series of water-soluble P(α-C2CL)-paclitaxel prodrugs with high drug contents (up to 41.4wt-%) was prepared by esterification. Meanwhile, methyl tetrazolium (MTT) assays showed that P(α-C2CL)-paclitaxel prodrugs exhibited a high antitumour effect on A549 and MCF-7 cells. These prodrugs have appeared as a highly versatile and potent platform for cancer therapy. © CSIRO 2015.

Yang C.-A.,Universities of Hunan Province | Tan Q.,Universities of Hunan Province | Zhong G.,Universities of Hunan Province | Xie H.,Universities of Hunan Province | And 3 more authors.
Polymer | Year: 2010

A series of vinyl monomers, 2, 5-bis [(4-methoxy benzyl) oxycarbonyl] styrene (MBCS); 2, 5-bis [(3, 5-dimethoxy benzyl) oxycarbonyl] styrene (DMBCS) and 2, 5-bis [(3, 4, 5-trimethoxy benzyl) oxycarbonyl] styrene (TMBCS) were synthesized and polymerized via free radical polymerization. The terminal groups of the semirigid side chain were systematically varied to investigate the effects of their numbers on the ability of mesophase formation of the resultant polymers. The chemical structures of the monomers were confirmed by elemental analysis, 1H NMR and 13C NMR. The characterization of the polymers was performed with 1H NMR, gel permeation chromatography (GPC). The phase structures and transition behaviors were studied using differential scanning calorimetry (DSC), polarized light microscopy (PLM) and one- and two-dimensional wide-angle X-ray diffraction (WAXD). The experimental results suggested that the ability of mesophase formation of the polymers decreased as the rigidity of side-chain group decreased and increased as the number of the alkoxy terminal group increased, and that all the polymers with high molecular weight showed stable columnar nematic phase (ΦN). © 2009 Elsevier Ltd. All rights reserved.

Zhu J.,Central South University | Zhu J.,Universities of Hunan Province | Tian Y.,Central South University | Tian Y.,Universities of Hunan Province | And 2 more authors.
Cehui Xuebao/Acta Geodaetica et Cartographica Sinica | Year: 2012

The core problem of the concerned survey adjustment is to find appropriate value for the unknown criterion parameter. Until now, there is no united theory to solve this problem. The authors firstly use one expression to unite all adjustment criteria with unknown parameters in form. Then a method with virtual observations is proposed to resolve the united expression. In order to illustrate the feasibility and advantages of this method, an example compared with LS and other methods is presented at last.

Wang J.,Hunan University of Science and Technology | Gong M.,Universities of Hunan Province | Hou Z.,Changsha University of Science and Technology
Sensors and Transducers | Year: 2014

Propose a fault diagnosis method which combines analytical redundancy with bond graph model for electrolytic high power rectifier system. Firstly, using the software 20-sim, the author builds a bond graph model of the system and established a diagnostic bond graph model through adding virtual sensor in bond graph model; then, according to the causal relationship in the components, analytical redundancy relationship and its fault characteristic matrix are set up; finally, comparing the observed characteristics matrix and fault characteristic matrix, fault can be detected and isolated quickly. The simulation results demonstrate that the method is convenient and effective for Power electronic fault diagnosis. © 2014 IFSA Publishing, S. L.

Bin N.,Universities of Hunan Province | Yongbin L.,Universities of Hunan Province | Yujie L.,Universities of Hunan Province | Sheng C.,Universities of Hunan Province | Hailiang Z.,Universities of Hunan Province
New Journal of Chemistry | Year: 2015

A series of end-on side-chain liquid crystalline polymers (SCLCPs) based on a biphenyl mesogen, poly(4,4′-alkoxybiphenyl acrylate) (PBiA-m, m = 1, 4, 6, 10, 18), were successfully synthesized by free radical polymerization or reversible addition fragmentation chain transfer (RAFT) polymerization. The chemical structures of the monomers were confirmed by 1H NMR and mass spectrometry. The phase structures and transition behaviors were studied using DSC, POM and 1D WAXD. The experimental results found that PBiA-m showed the bilayer smectic phase and a higher clearing point (Ti) compared with poly(4,4′-alkoxybiphenyl methacrylate) (PBiMA-m). In addition, poly(4,4′-hexyloxybiphenyl methacrylate) (PBiMA-6) and poly(4,4′-hexyloxybiphenyl acrylate) (PBiA-6) with different molecular weights (Mn) and low molecular weight distributions have been successfully synthesized via the RAFT polymerization. The results indicated that all the polymers exhibited a bilayer smectic phase and Ti increased as the Mn of PBiMA-6 and PBiA-6 increased. Moreover, PBiA-6 had a higher Ti compared with PBiMA-6 with a similar Mn value. All the results suggested that the main-chain (acrylate and methacrylate) and Mn had a great influence on the properties of SCLCPs without the spacer. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015.

Hu T.,Universities of Hunan Province | Yi J.,Universities of Hunan Province | Xiao J.,Universities of Hunan Province | Zhang H.,Universities of Hunan Province
Polymer Journal | Year: 2010

Main-chain/side-chain liquid crystalline polymers (MCSCLCPs) based on ethyl cellulose (AzomEC, m=2, 4, 6, where m is the length of the spacer between the main chain and mesogens) were successfully synthesized by N,N′- dicylcohexylcarbodiimide (DCC) coupling. Molecular characterizations of the resultant polymers with different spacer lengths were performed by proton nuclear magnetic resonance, Fourier transform-infrared spectroscopy and gel permeation chromatography. The phase transitions and liquid crystalline (LC) behaviors of these polymers were investigated by differential scanning calorimetry, polarized optical microscopy and wide-angle X-ray diffraction. The results indicate that spacer length has a tremendous effect on the LC behavior of the polymer. The glass transition temperatures, phase transition temperatures and the corresponding enthalpy of transitions decreased as the flexible spacer length increased. The mesophase structures of polymers consisted of a large-scale ordered lamellar structure composed of the EC main chain and a relatively small-scale ordered structure formed by azobenzene side chains. All the polymers form a similar lamellar structure on a large scale; however, the small-scale ordered structure becomes relatively disordered, that is, from crystal (m=2) to smectic B (m=4) to smectic A (m=6) at low temperatures. © 2010 The Society of Polymer Science, Japan (SPSJ) All rights reserved.

Deng Y.,Universities of Hunan Province | Hu Q.,Universities of Hunan Province | Yuan Q.,Universities of Hunan Province | Wu Y.,Universities of Hunan Province | And 2 more authors.
Macromolecular Rapid Communications | Year: 2014

Molecular bottle-brush functionalized single-walled carbon nanotubes (SWCNTs) with superior dispersibility in water are prepared by a one-pot synthetic methodology. Elongating the main-chain and side-chain length of molecular bottle-brushes can further increase SWCNT dispersibility. They show significant enhancement of SWCNT dispersibility up to four times higher than those of linear molecular functionalized SWCNTs. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tao X.,Central South University | Tao X.,Universities of Hunan Province | Zhu J.,Central South University | Zhu J.,Universities of Hunan Province | And 2 more authors.
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2012

Many methods can be used to determine smoothing parameters in semiparametric model, but smoothing parameters vary with these methods for the same model. After comparative analysis of the L-Curve, GCV(Generalize Cross Validation) and virtual observational approach, the factors influencing smoothing parameter are studied by simulated example. Smoothing parameters have a close relation with signal-to-noise ratio. When the signal-to-noise ratio increases, variation trend of smoothing parameters is different. The best method determining smoothing parameters in different situations is different.

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