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Search Results: 1 - 10 of 190499 matches for " YANG Li-jun "
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Determination of okadaic acid related toxins from shellfish (sinonovacula constricta) by high performance liquid chromatography tandem mass spectrometry  [PDF]
Hai-qi Zhang, Weicheng Liu, Xin He, Li-jun Liang, Wenyong Ding, Zhong-yang He
Agricultural Sciences (AS) , 2013, DOI: 10.4236/as.2013.45B001
Abstract:

Consumption of shellfish contaminated with algal toxins produced by marine dinoflagellates can lead to diarrhetic shellfish poisoning (DSP). It was therefore essential that there are analytical techniques to identify and quantify DSP toxins in shellfish. This new methodology could facilitate DSP monitoring and create a means of rapidly responding to incidents threatening public health. In the last years there were different analytical methods for DSP, such as mouse bioassay and LC-FLD. With the development of instrument, Liquid chromatography-mass spectrometry was substituted for other analytical methods with its good sensitivity and selectivity and without derivatization for the determination of DSP. In this report, a high performance liquid chromatogra-phytandem mass spectrometric(HPLC-MS/MS)method was developed for the simultaneous determination of okadaic acid (OA) and dinophysistoxins(DTX1) in Sinonovacula constricta. Optimization of pretreatment experiment was carried out to maximize recoveries and the effectiveness. The analytes were determined under multi-reactions monitoring (MRM) scan type with tandem mass analyzer using negative ion electrospray ionization (-ESI) mode .Finally, the detection and identification of OA and DTX-1 were based upon their retention times (RT) and the fragmentation patterns of their mass spectra. The method of LOQ for the two poisons was 0.02 mg·kg-1.The real sample test showed that this method could be used for sensitive, fast, and accurate determination of the two diarrheic shellfish poisons in shellfish.

Bis(2-methyl-1H-imidazole-κN3)bis[2-(naphthalen-2-yl)acetato-κO]copper(II)
Fu-Jun Yin,Li-Jun Han,Shu-Ping Yang,Xing You Xu
Acta Crystallographica Section E , 2011, DOI: 10.1107/s1600536811047969
Abstract: In the crystal structure of the title compound, [Cu(C12H9O2)2(C4H6N2)2], the Cu(II) cations are square-planar coordinated by two 1-naphthylacetate anions and two 2-methyl-imidazole ligands into discrete complexes that are located on centres of inversion. These complexes are linked into chains parallel to [010] by intermolecular N—H...O hydrogen bonding between the N—H H atom of the 2-methyl-imidazole ligands and the carboxylate O atoms that are not involved in metal coordination.
Bis(1-methyl-1H-imidazole-κN3)bis[2-(naphthalen-1-yl)acetato-κO]copper(II) monohydrate
Fu-Jun Yin,Li-Jun Han,Shu-Ping Yang,Xing-You Xu
Acta Crystallographica Section E , 2011, DOI: 10.1107/s1600536811049439
Abstract: In the crystal structure of the title compound, [Cu(C12H9O2)2(C4H6N2)2]·H2O, the CuII atom is coordinated by two 2-(naphthalen-1-yl)acetate anions and two 1-methylimidazole ligands, giving monomeric complexes with a square-planar coordination environment. Two complex molecules and two water molecules form a centrosymmetric ring system via O—H...O hydrogen bonds.
Composition-Dependent Dielectric Properties of DMF-Water Mixtures by Molecular Dynamics Simulations
Guo-Zhu Jia,Ka-Ma Huang,Li-Jun Yang,Xiao-Qing Yang
International Journal of Molecular Sciences , 2009, DOI: 10.3390/ijms10041590
Abstract: In this paper, we study the dielectric properties of water-N,N dimethylformamide (DMF) mixtures over the whole composition range using a molecular dynamics (MD) simulation. The static and microwave frequency-dependent dielectric properties of the mixtures are calculated from MD trajectories of at least 2 ns length and compared to those of available measurements. We find that the short-ranged structural correlation between neighboring water and DMF molecules strongly influences the static dielectric properties of mixtures. In terms of the dynamics, we report time correlation functions for the dipole densities of mixtures and find that their long-time behavior can be reasonably described by biexponential decays, which means the dielectric relaxations of these mixtures are governed by complex multitimescale mechanisms of rotational diffusion. The dipole density relaxation time is a non-monotonic function of composition passing through a maximum around 0.5 mole fraction DMF, in agreement with the measured main dielectric relaxation time of mixtures.
A Proline-Based Neuraminidase Inhibitor: DFT Studies on the Zwitterion Conformation, Stability and Formation
Zhi-Wei Yang,Xiao-Min Wu,Li-Jun Zhou,Gang Yang
International Journal of Molecular Sciences , 2009, DOI: 10.3390/ijms10093918
Abstract: The designs of potent neuraminidase (NA) inhibitors are an efficient way to deal with the recent “2009 H1N1” influenza epidemic. In this work, density functional calculations were employed to study the conformation, stability and formation of the zwitterions of 5-[(1R,2S)-1-(acetylamino)-2-methoxy-2-methylpentyl]-4-[(1Z)-1-propenyl]-(4S,5R)-D-proline (BL), a proline-based NA inhibitor. Compared to proline, the zwitterion stability of BL is enhanced by 1.76 kcal mol-1 due to the introduction of functional groups. However, the zwitterion of BL will not represent a local minimum on the potential energy surface until the number of water molecules increases up to two (n = 2). With the addition of two and three water molecules, the energy differences between the zwitterions and corresponding canonical isomers were calculated at 3.13 and -1.54 kcal mol-1, respectively. The zwitterions of BL are mainly stabilized by the H-bonds with the water molecules, especially in the case of three water molecules where the carboxyl-O atoms are largely coordination-saturated by three H-bonds of medium strengths, causing the zwitterion stability even superior to the canonical isomer. With the presence of two and three water molecules, the energy barriers for the conversion processes from the canonical isomers to the zwitterions are equal to 4.96 and 3.13 kcal mol-1, respectively. It indicated that the zwitterion formation is facile to take place with addition of two molecules and further facilitated by more water molecules. Besides, the zwitterion formation of BL is finished in a single step, different from other NA inhibitors. Owing to the above advantages, BL is a good NA inhibitor candidate and more attention should be paid to explorations of BL-based drugs.
Viscosity modeling for ionic liquid solutions by Eyring-Wilson equation
He Yang-Chun,Xu Xue-Jiao,Yang Li-Jun,Ding Bing
Chemical Industry and Chemical Engineering Quarterly , 2012, DOI: 10.2298/ciceq110829019h
Abstract: A semi-theoretical model based on the classical Eyring’s mixture viscosity equation and the Wilson activity coefficient equation is presented for correlating the viscosity of ionic liquids with solvent systems. The accuracy of the proposed model was verified by comparing calculated and experimental viscosity values from literatures for 49mixtures with total 1560 data points. The results show that the equation similar to the Wilson activity coefficient equation can be well applied to describe the non-ideal term in the Eyring’s mixture viscosity equation. The model has a relatively simple mathematical form and can be easily incorporated into process simulation software.
8-Acetyl-4-methyl-2-oxo-2H-chromen-7-yl acetate
Shu-Ping Yang,Li-Jun Han,Xin-Ran He,Li-Juan Chen
Acta Crystallographica Section E , 2011, DOI: 10.1107/s1600536811048835
Abstract: In the title compound, C14H12O5, the benzopyran-2-one ring system is approximately planar [maximum deviation = 0.018 (1) ]; the mean plane is oriented at dihedral angles of 52.26 (11) and 72.92 (7)°, respectively, to the acetyl and acetoxy groups. In the crystal, π–π stacking is observed between parallel benzene rings of adjacent molecules, the centroid–centroid distance being 3.6774 (17) . Intermolecular weak C—H...O hydrogen bonding, and C=O...C=O [O...C = 3.058 (3) ] and C=O...π [O...centroid = 3.328 (2) ] interactions occur in the crystal structure.
6′,7′-Dimethoxy-1′,2′-dihydrospiro[cyclohexane-1,2′-quinazolin]-4′(3′H)-one
Li-Jun Zhang,Yang Song,Xiang-Ning Luo,Hui Li
Acta Crystallographica Section E , 2011, DOI: 10.1107/s1600536811048732
Abstract: In the title compound, C15H20N2O3, prepared from the reaction of 2-amino-4,5-dimethoxybenzonitrile and cyclohexanone, the six-membered diaza ring assumes an envelope conformation. In the crystal, inversion dimers are formed by pairs of N—H...O hydrogen bonds. Futher N—H...O hydrogen bonds link the dimers into a two-dimensional structure parallel to (001).
First-principles calculations of electronic structure, optical and elastic properties of LiGaX2(X=S,Se,Te)
LiGaX2(X=S,Se,Te)的电子结构,光学和弹性性质的第一性原理计算

Chen Hai-Chuan,Yang Li-Jun,
陈海川
,杨利君

物理学报 , 2011,
Abstract: The density of states, electronic structure, optical and elastic properties of LiGaX2 (X=S, Se, Te) are investigated by the first-principles plane-wave pseudopotential density functional theory within the generalized gradient approximation (GGA). The results show that the band gaps of LiGaX2 (X=S, Se, Te) are 4.146 eV, 3.301 eV and 2.306 eV, respectively. It can be confirmed that the valence bands are mainly composed of X-np or Ga-4p states. The complex dielectric functions, reflectivity, index of refraction and elastic property are precisely calculated by band structure and density of states. The obtained results are in agreement with the available experimental data.
Field Emission Properties of Ball-Like Nano-Carbon Thin Films Deposited on Mo Films with Accidented Topography

WANG Long-Yang,WANG Xiao-Ping,WANG Li-Jun,ZHANG Lei,

中国物理快报 , 2008,
Abstract:
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