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11.
The crystal structure of the new title compound 2,2-dimethyl-4-oxochroman-3-ylmorpholine-4-carbodithioate(C16H19NO3S2,Mr = 337.44) has been prepared and determined by single-crystal X-ray diffraction.The crystal is of triclinic,space group P1 with a = 9.5518(7),b = 9.7172(7),c = 11.0220(8),α = 67.08(1),β = 74.66(1),= 61.31(1)°,V = 822.72(10)3,Z = 2,Dc = 1.362 g/cm3,F(000) = 356,μ = 0.092 mm-1,MoKa radiation(λ = 0.71073),R = 0.0515 and wR = 0.1389 for 2623 observed reflections with I > 2(I).X-ray diffraction analysis reveals that the chroman ring adopts a half-chair conformation while the morpholine ring shows a chair conformation.Intramolecular and intermolecular C-H···S and C-H···O hydrogen bonds together with π-π interations are found in the structure.The result of MTT assay shows the title compound displays good antiproliferative activity against two human cancer cell lines. 相似文献
12.
提出了三种基于少模光纤的全光纤熔融模式选择耦合器. 根据模式匹配原理采用单模光纤与少模光纤熔融连接方式, 运用耦合模理论及光束传播法模拟分析了模式选择耦合器的结构参数对模式选择及耦合特性的影响, 实现了单模光纤中基模到少模光纤中不同阶模式的转换, 以满足不同的应用需求. 实验上以2× 2熔融光纤耦合器为例, 采用对称和非对称熔融拉锥方式, 分别实现了从基模到LP11, LP21模式的转换. 实验结果表明所得到的LP11, LP21模式在1530–1560 nm的波长带宽范围内均有较高的模式纯净度, 且模式耦合效率高于80%, 与理论模拟结果基本一致. 相似文献
13.
Fast parallel algorithm for three-dimensional distance-driven model in iterative computed tomography reconstruction 下载免费PDF全文
The projection matrix model is used to describe the physical relationship between reconstructed object and projection.Such a model has a strong influence on projection and backprojection,two vital operations in iterative computed tomographic reconstruction.The distance-driven model(DDM) is a state-of-the-art technology that simulates forward and back projections.This model has a low computational complexity and a relatively high spatial resolution;however,it includes only a few methods in a parallel operation with a matched model scheme.This study introduces a fast and parallelizable algorithm to improve the traditional DDM for computing the parallel projection and backprojection operations.Our proposed model has been implemented on a GPU(graphic processing unit) platform and has achieved satisfactory computational efficiency with no approximation.The runtime for the projection and backprojection operations with our model is approximately 4.5 s and 10.5 s per loop,respectively,with an image size of 256×256×256 and 360 projections with a size of 512×512.We compare several general algorithms that have been proposed for maximizing GPU efficiency by using the unmatched projection/backprojection models in a parallel computation.The imaging resolution is not sacrificed and remains accurate during computed tomographic reconstruction. 相似文献
14.
Wei-Wei Zhang Na Wang Ling Zhang Wan-Xia Wu Cheng-Li Hu Xiao-Qi Yu 《Applied biochemistry and biotechnology》2014,172(6):3128-3140
An inexpensive, facile, and environmentally benign method was developed to improve the activity and stability of Candida rugosa lipase (triacylglycerol acylhydrolase) immobilized on microemulsion-based organogels (CRL MBGs) via the addition of additives during immobilization. The additives used were polyethylene glycol (PEG) or polysaccharides. This study is the first report on the effect of additives in CRL MBGs. Among the tested additives, PEG produced the most improvement in the immobilized CRL, enhancing its stability in organic solvents (specifically polar solvents). The results of circular dichroism and fluorescence spectra experiments indicated that exposure of the acidic CRL to electronegative additives in the buffer, such as polyethylenimine and the electropositive surfactant cetyltrimethylammonium bromide, may change the lipase secondary structure, ultimately causing enzyme inactivation. However, sodium bis(2-ethylhexyl)sulfosuccinate and PEG 2000 had minimal effects on the secondary structure of CRL. The CRL MBGs containing PEG 2000 demonstrated remarkable retention of their catalytic activity during the recycling test. No significant changes in enzymatic activity were observed, even after nine runs, and 90 % of the original yield was maintained after 15 cycles. 相似文献
15.
Single crystal of lithium terbium tungstate LiTb(WO4)2 has been grown by the flux method. The crystal structure was refined from single-crystal X-ray data. It crystallizes in tetragonal system, space group I41/a with a = 5.1749(9), c = 11.1953(19) ?, V = 299.81(12) ?~3, Z = 2, Mr = 661.56, Dc = 7.328 g/cm^3, F(000) = 560, μ(MoKα) = 49.94 mm-1, R(F^2 > 2σ(F^2)) = 0.026 and wR(F^2) = 0.070. It features a typical scheelite-type structure composed of two-direction packing of isolated WO4 tetrahedra. Li and Tb atoms in the structure occupy the same crystallographic site. Moreover, a series of solid solution phosphors LiTb(1-x)Eux(WO4)2(x = 0.004~0.1) were synthesized by high temperature solid-state reactions. The phosphors could be effectively excited by a wavelength range from 379 to 487 nm, which matches well with the UV and near-UV LED chip. The emission color of the phosphor can be tuned from green, through yellow to red by simply adjusting the relative Eu3+ and Tb3+ concentration due to the Tb3+ to Eu3+ energy transfer. 相似文献
16.
17.
聚乙撑二氧噻吩阳极降解的研究 总被引:1,自引:0,他引:1
研究了聚乙撑二氧噻吩(PEDOT)膜在水溶液中的阳极降解过程. 研究发现PEDOT的阳极过程可以分为p掺杂区[电位范围-0.3~0.5 V (相对于饱和甘汞电极; vs. SCE)]、过渡区[电位范围0.6~1 V (vs. SCE)]、过氧化区[电位范围1.2~1.6 V (vs. SCE)]三个电位区域. 用电化学阻抗谱法、循环伏安法、红外光谱技术、膜电阻测量以及电子自旋共振技术分别研究了PEDOT膜在这三个电位区域的行为. 结果表明: PEDOT膜在这三个电位区域的性质有明显不同. 在p掺杂区PEDOT膜的官能团、共轭结构、导电性均保持, 即在这个电位区发生可逆的掺杂/脱掺杂反应, 膜几乎不降解. 在过渡区和过氧化区, PEDOT膜均发生了降解. 与传统的导电聚合物在高电位的阳极降解的过氧化过程不同, 我们认为膜在较高电位(过渡区)发生一个驰豫过程, 该过程使得膜的官能团改变, 但是膜的共轭结构和导电性均保持; 而在更高的电位区(过氧化区)膜的降解和一般意义的过氧化降解相同, 此时膜的官能团、共轭结构、导电性均发生不可逆的破坏. 相似文献
18.
利用温度梯度法,在6.5 GPa、1 300~1 350℃的高温高压极端物理条件下,通过在FeNiCo-C合成体系中添加硫脲(CH4N2S)成功合成了金刚石,所合成的晶体呈现出黄色且具有六-八面体形貌.利用扫描电镜(SEM)对所合成金刚石的表面形貌进行了表征,测试结果表明,随着合成体系中CH4N2S添加量的逐渐增加,所合成金刚石的表面变得逐渐粗糙.借助傅里叶红外(FT-IR)光谱对金刚石样品内部的氮、氢缺陷以及化学键结构进行了测试分析,结果表明,金刚石中的氢元素以-CH3,-CH2-,C-H形式存在,而其内部的氮杂质以C心、A心形式存在.此外,在3 300~3 600 cm-1观察到NH的吸收带. 相似文献
19.
丙烯酸盐喷膜防水材料在酸碱溶液浸润和冻融条件下的耐久性能是该类材料在工程应用中较难回避的实际问题,论文采用酸性介质(0.2%的H2SO4溶液)和碱性介质(0.1%NaOH+饱和Ca(OH)2溶液)对该材料进行饱和浸泡并进行冻融循环后,研究了该材料的吸水性、断裂拉伸强度和拉断伸长率的变化规律。试验结果表明:喷膜防水材料在侵蚀-冻融循环作用下,其拉断伸长率和断裂拉伸强度显著降低,且酸性介质对材料拉伸性能的影响较大;材料耐低温冰冻能力较强,耐高温能力较差。反映出丙烯酸盐喷膜防水材料在低温冰冻和碱性介质中耐久性较好,不建议在高温和酸性介质条件下使用。 相似文献
20.
In this paper, the stereoselective homogeneous catalysis polymerization of phenylacetylene by using two kinds of catalysts W(CO)_5CH_3I and W(CO)_4I_2 produced from UV laser photolysis of W (CO)_6 in CH_3I, I_2—C_6H_6 and CHI_3—C_6H_6 respectively was studied. The effects of laser energy, laser irradiation time and lifetime of catalyst on the polymerization of phenylacetylene were discussed. The photoproducts of W (CO)_6 in CH_3I, I2—C_6H_6 and CHI_3—C_6I_6 were determined by IR spectra. The structures of polyphenylacetylene obtained by W (CO)_5CH_3I and W (CO)_4I_2 catalysts were characterized by IR spectra and ~1H NMR spectra. 相似文献