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991.
A new series of ionic liquid crystals (ILCs), 1-(4-(4-nitrophenylazo)phenyloxy) vinyl-3-methyl-1H-imidazol-3-ium bromide salts (C n , n?=?6, 10) were synthesised. Their chemical structures were determined by 1H NMR, 13C NMR, UV spectroscopy and elemental analysis. The liquid crystalline properties were investigated by differential scanning calorimetry, polarising optical microscopy, and powder X-ray diffraction. These measurements showed that C n (n?=?6, 10) exhibit smectic liquid crystalline phases with focal-conic fan-shaped textures. The introduction of vinylimidazolium group onto the azobenzene enhances the thermal stability of the smectic state, which play an important role in forming the smectic layer structure. 相似文献
992.
Yan Ren Pengyuan Wang Caisheng Wu Jinlan Zhang Chunyan Niu 《Biomedical chromatography : BMC》2013,27(1):17-26
Ziziphi spinosae semen (ZSS) is a traditional Chinese medicine that has been widely used to treat insomnia and anxiety. Modern pharmacological studies have demonstrated that flavonoids are the main active compounds in ZSS. However, the metabolites and the metabolic pathways of flavonoids in ZSS have not been investigated thoroughly. In this study, a method based on high‐performance liquid chromatography coupled with Fourier transform ion cyclotron resonance mass spectrometry (HPLC/FTICR‐MS) was established to identify the metabolites of flavonoids after oral administration of extract of ZSS to rats or dogs, using parent mass list‐triggered data‐dependent multiple‐stage mass analysis at a resolving power of 50,000 in the external calibration mode. The mass accuracies obtained for all full‐scan analyses were less than 4 ppm (<2 ppm in most cases). A total of 15 compounds were detected in biological samples of rats and dogs, and nine compounds were identified. The metabolic pathways of flavonoids of ZSS in rats and dogs were proposed. The results may help better understand the material basis and pharmacological mechanism of ZSS. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
993.
Ying-Hao Pan Xiao-Xiao Chen Lei Dong Na Shao Li-Ya Niu Qing-Zheng Yang 《中国化学快报》2021,32(12):3895-3898
Evaluating the correlation between hypoxia inducible factor 1 (HIF-1) and nitric oxide (NO) generated under hypoxia is of great significance. In this work, we developed a fluorescent probe for the monitor of HIF-1 activity influenced by NO under hypoxia in hepatoma cells with dual-targeting for hepatocyte and lipid droplet (LD). The probe shows excellent selectivity to NO and high sensitivity with 6000-fold fluorescence enhancement. Live cell imaging experiments revealed the probe's capability of imaging exogenous and endogenous NO with specific in LDs of HepG2 cells. For cells under hypoxia, HIF-1 induced LD level is observed to correlate with NO level. This work provides the in-situ visualization of NO-dependent HIF-1 upregulation through LD accumulation. 相似文献
994.
基于经典快过程理论模型, 研究了原子核物理输入量的不确定性对Th/U, Th/Hf, Th/Eu, Th/Os, Th/Ir等核时钟估算宇宙年龄的影响. 其中利用蒙特卡罗模拟方法, 计算了不同质量模型下由单中子分离能引起的不确定性.结果表明, Th/U核时钟由原子核质量不确定性引起的误差大约为1.66 Ga, 比其他核时钟小2 Ga以上.对 Th/Eu, Th/Os和Th/Ir核时钟, 该误差分别为5.15, 3.93和3.95 Ga.由于Th/Hf核时钟受质量模型影响太大, 而Th/Os和Th/Ir的计算结果又明显偏大, 因此在年龄计算中都需谨慎使用.综合考虑原子核物理输入量和天文观测带来的误差, 利用Th/U核时钟估算的宇宙年龄为14.1± 3.8 Ga. 相似文献
995.
A method for hiding multiple images into one image is presented. The method is based on interference principle and double random phase mask method. A uniform plane wave interferes with two beams of light wave carrying information of two encrypted images on an output plane. The obtained interference distribution image contains information of two encrypted images. By using frequency spectrum center shift technique, the two encrypted images can be recovered successfully. Then, the interference distribution is encoded into an index matrix through a host image. The optical encryption system parameters and the host image can all be used as encryption keys, which make encrypted image information safer. Numerical simulation indicates that the method can encrypt more information into one image and reconstruct the encryption image information successfully. 相似文献
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This paper first applies a flux vector‐type splitting method based on the numerical speed of sound for computing incompressible single and multifluid flows. Here, a preconditioning matrix based on Chorin's artificial compressibility concept is used to modify the incompressible multifluid Navier–Stokes equations to be hyperbolic and density or volume fraction‐independent. The current approach can reduce eigenvalues disparity induced from density or volume fraction ratios and enhance numerical stability. Also, a simple convection‐pressure flux‐splitting method with high‐order essentially nonoscillatory‐type primitive variable extrapolations coupled with monotone upstream‐centered schemes for conservation laws‐type volume fraction recompressed reconstruction is used to maintain the preservation of sharp interface evolutions in multifluid flow simulations. Benchmark tests including a solid rotation test of a notched two‐dimensional cylinder, the evolution of spiral and rotational shapes of deformable circles, a dam breaking problem, and the Rayleigh–Taylor instability were chosen to validate the current incompressible multifluid methodology. An incompressible driven cavity was also chosen to check the robustness of the proposed method on the computation of single fluid incompressible flow problems. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献