Optically pure polyfluoroalkanesulfinamides: synthesis and application as promising and monitorable chiral auxiliaries

Efficient synthesis of enantiopure polyfluoroalkanesulfinamides (PFSAs) has been achieved. Their application as novel chiral auxiliaries with an electron-withdrawing and (19)F NMR monitorable polyfluoroalkyl group was initially demonstrated in an asymmetric Strecker reaction under mild conditions.     

Y2O3:Yb3+,Tm3+纳米材料的可见及紫外上转换发光

通过燃烧法制备了Yb³⁺-Tm³⁺共掺的Y₂O₃纳米粉体,并对样品在980 nm激光照射下的上转换发光特性进行了研究.实验发现,样品在可见光区域能够产生强烈的蓝色发光(476 nm和487 nm)和较弱的红色发光(约650 nm),而且同时观察到了两个紫外发光峰¹I₆→³H₆ (~297 nm)和^{1关键词： 2O₃:Yb3+')" href="#">Y₂O₃:Yb3+ 3+}')" href="#">Tm³⁺ 上转换光谱 敏化 紫外发光     

Regularity of Traveling Free Surface Water Waves with Vorticity

We prove real analyticity of all the streamlines, including the free surface, of a gravity- or capillary-gravity-driven steady flow of water over a flat bed, with a Hölder continuous vorticity function, provided that the propagating speed of the wave on the free surface exceeds the horizontal fluid velocity throughout the flow. Furthermore, if the vorticity possesses some Gevrey regularity of index s, then the stream function of class C ^2,μ admits the same Gevrey regularity throughout the fluid domain; in particular if the Gevrey index s equals 1, then we obtain analyticity of the stream function. The regularity results hold not only for periodic or solitary-water waves, but also for any solution to the hydrodynamic equations of class C ^2,μ .     

三维有序大孔尖晶石型Li1.6Mn1.6O4的制备及锂离子筛吸附特性

用LiNO3、Mn(Ac)2•4H2O和柠檬酸的混合溶液填充聚甲基丙烯酸甲酯胶体晶体模板, 在空气中氧化焙烧, 制备出三维有序大孔尖晶石型锂锰氧化物Li1.6Mn1.6O4. 前驱体经过0.1 mol/L盐酸脱锂后获得相应的三维有序大孔锂离子筛, 其大孔直径和孔壁厚度分别为240 nm和50 nm左右. XRD测试结果表明, Li1.6Mn1.6O4、锂离子筛和吸锂后的样品均保持尖晶石结构. 三维有序大孔材料呈现彼此连通的孔道空间, 缩短了Li+的平衡吸附时间, 前驱体脱锂率在80 ℃时达到95%, 而锰的溶损率在低于60 ℃时小于2.5%. 溶液温度对Li+的交换能力影响很大, 升高温度, Li+与H+的可逆交换程度增大, Li+的最大吸附容量为56.7 mg/g, 但处于锰16d八面体缺陷位置的氢难于被交换. pH滴定和分配系数(Kd)分析表明, 该固体酸在Li+, Na+和K+共存溶液中对Li+的吸附具有较高的选择性.     

Ag@AgI等离子体负载TiO2酸蚀纳米带的制备及可见光光催化性能的研究

采用沉积-沉淀法将AgI分散到TiO2酸蚀纳米带上,然后通过光照进而分解出Ag颗粒,最终获得了Ag@AgI等离子体负载的TiO2酸蚀纳米带(AIST)。利用UV-Vis吸收光谱、XRD、SEM对产物进行表征,并研究了可见光下对甲基橙(MO)的光催化降解性能。结果表明,纳米带酸蚀后利于AgI的沉积,Ag的表面等离子体共振效应可以增强催化剂对于可见光的吸收,使可见光下AIST的光催化降解性能显著提高。     

氮杂环荧光试剂2-(11H-苯[a]咔唑)乙基氯甲酸酯对胺类化合物标记及质谱鉴定

含氮类荧光试剂2-(11H-苯[a]咔唑)乙基氯甲酸酯(BCEC-Cl)经柱前衍生处理后,采用荧光检测及柱后在线质谱鉴定对食品中胺类化合物进行了测定。标记反应在pH9的硼酸缓冲液中进行,3min后获得稳定的荧光产物。衍生物于λex=279nm激发条件下产生强烈荧光,其发射波长在λem=380nm处。产物的分离在EclipseXDB-C8色谱柱(150mm×4.6mm,5μm)上进行,采用梯度洗脱对12种脂肪胺衍生物进行了优化分离。采用大气压化学电离源(APCISource)正离子模式进行在线的柱后质谱鉴定,实现了多种脂肪胺衍生物的快速、准确测定。建立的方法具有良好的重现性,回归系数大于0.9996,检出限为1.8~14fmol。     

2-(11H-苯[a]咔唑)乙基氯甲酸酯柱前衍生化用于氨基酸的高效液相色谱分析

利用新型荧光试剂2-(11H-苯[a]咔唑)乙基氯甲酸酯(BCEC-Cl)作为柱前衍生化试剂,在HypersilBDS C18(200mm×4.6mm,5μm)反相色谱柱上,采用梯度洗脱对20种氨基酸衍生物进行了分离检测。在乙腈与Na2B4O7缓冲液中,室温下BCEC-Cl与氨基酸反应5min可实现完全衍生。检测的激发和发射波长分别为λex=279nm,λem=380nm。采用柱后质谱电喷雾离子源(ESI source)正离子模式,实现了水解牛血清白蛋白中氨基酸和油菜蜂花粉中氨基酸的定性定量检测。荧光定性检测的线性回归系数均大于0.9990,检出限为1.49~19.74fmol(S/N=3)。     

Li(Na)AuS体系拓扑绝缘体材料的能带结构

在拓扑领域中发现可以通过大数据搜索拓扑绝缘体,使得此领域对材料的探索转变为对材料性质的研究.半Heusler合金体系是非平庸拓扑绝缘体材料的重要载体.通过全势线性缀加平面波方法计算Li(Na)AuS体系拓扑绝缘体材料的能带结构.采用各种关联泛函计算LiAuS的平衡晶格常数,发现得到的能带图均为具有反带结构的拓扑绝缘体,...     

Isolation of a new flavanone from Daidai fruit and hypolipidemic activity of total flavonoids extracts

In order to further discover the medicinal value of Daidai fruit, an exploration on the hypolipidemic activity of total flavonoids extracts of Daidai fruit (TFEODF) was conducted in high-fat diet-induced hyperlipemia rats. Results indicated that TFEODF exhibited significant hypolipidemic activity which resulted in the decline of serum total cholesterol, triglyceride, low density lipoprotein cholesterol, arteriosclerosis index and rise of high density lipoprotein cholesterol in hyperlipemia rats. For the purpose of expounding the chemical constituents of TFEODF, a phytochemical investigation of TFEODF was carried out for the first time. Research resulted in the isolation of a new compound together with 17 known compounds. This study lay a foundation for the development of a new hypolipidemic agent of traditional Chinese medicine whose chemical constituents were clarified.     

抗坏血酸与过氧化氢反应的自旋捕捉-ESR研究

利用自旋捕捉-ESR方法研究了分析纯抗坏血酸(Aa)与医用维生素C注射液(Vc)的自氧化和过氧化氢反应,在自氧化反应中只观察到去氢抗坏血酸负离子基A-.,而与过氧化氢反应时除观察到A-.外,还观测到另外数种自由基,经计算机拟合后得到这些自由基或其5,5-二甲基-1-吡咯啉-1-氧化物(DMPO)加合物的ESR谱参数,在此基础上推测出该反应的机理.