A new polyoxygenated cyclohexene derivative from Artabotrys hainanensis

A new polyoxygenated cyclohexene derivative, artahainanol A (1), together with three known analogues (2–4), was isolated from the stems and leaves of Artabotrys hainanensis. Among them, 1 is an unusual polyoxygenated cyclohexene containing 14 carbon atoms on the carbon skeleton. All known compounds (2–4) were isolated from the genus Artabotrys for the first time. The structure of 1 was elucidated by extensive spectroscopic methods and the known compounds were identified by comparisons with data reported in the literature. All isolated compounds were evaluated for their cytotoxicities against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480 in vitro. Compounds 1–4 showed significant inhibitory effects against various human cancer cell lines with IC₅₀ values ranging from 2.68 to 18.32 μM.     

Enhanced rheological properties and performance of viscoelastic surfactant fluids with embedded nanoparticles

A combination of viscoelastic surfactants with nanoparticles gives a new class of functional self-assembled materials promising for a large variety of applications. Nanoparticles improve the rheological properties of these systems because of the incorporation into the network of entangled wormlike micelles by linking to micellar end-caps, thus leading to elongation or cross-linking of the micelles. The present article reviews recent studies of these hybrid systems. Mechanisms of the interaction of nanoparticles with wormlike surfactant micelles as well as factors favoring the enhancement of rheological properties of viscoelastic surfactants by added nanoparticles are discussed, providing ways for proper design of such systems in the future. It is shown that viscoelastic surfactants modified with nanoparticles display very attractive features for practical applications, in particular, for fracturing fluids in oil recovery.     

二氧化钛纳米晶薄膜的吸收光谱和激发发射光谱

由TiO₂反胶束溶胶制备一系列TiO₂纳米晶薄膜，对膜的吸收光谱和激发发射光谱研究表明制备的膜存在有二种模式的跃迁，直接跃迁和间接跃迁。由于厚膜中存在较强的表面相互作用，厚膜的直接跃迁禁带宽与薄膜相比发生了红移。在不同陈化时间，浸渍相同次数制得的膜具有相同的直接跃迁禁带宽。除浸渍一次的膜不存在间接跃迁外，所有的膜具有相同的间接跃迁禁带宽。所有的膜具有几乎相同的发射光谱模式。     

A new triterpenoid glucoside from Leucas zeylanica

Abstract

A new triterpenoid glucoside, leuctriterpencoside (1), along with two known compounds (2–3) were isolated from Leucas zeylanica. The structure of the new compound was elucidated using comprehensive spectroscopic methods. Compound 1 showed significant inhibitory activity against α-glucosidase (IC₅₀ value of 0.85?±?0.12?μM).     

高中化学原子核外电子排布教学模型设计及应用

为加深学生对原子核外电子排布规律的理解，帮助他们快速掌握核外电子排布的书写，设计了2种教学模型：“台阶模型”和“台阶房子模型”。向学生介绍了这2种模型，并用试题和访谈了解他们的学习效果，结果良好。这2个教学模型可供中学化学教师在教学中参考和使用。     

Asymptotic Properties of Nonparametric Kernel Regression Estimator for \rho-Mixing Samples

For \rho-mixing samples, we discuss thestrong consistency of the nonparametric kernel regression estimator proposed by Gasser and Muller. Under more weaker conditions, its strong consistency and uniformly strong consistency are proved.     

Oxodiperoxo tungsten complex-catalyzed synthesis of adipic acid with hydrogen peroxide

An amphiphilic oxodiperoxo complex of tungsten using 8-quinolinol (QOH) as ligand has been synthesized and characterized by elemental analyses, gravimetry, chemistry titration, TG/DSC, IR and UV-vis spectroscopy. Oxidation of cyclohexene, cyclohexanol, cyclohexanone, cyclohexene oxide and 1,2-cyclohexane-diol to adipic acid in one-step was conducted by this complex catalyst using 30 wt.% hydrogen peroxide in the absence of organic solvent and phase-transfer catalyst. The effect of the reaction conditions on the oxidation of cyclohexene was studied by varying the amount of the catalyst, reaction temperature, reaction time and the amount of hydrogen peroxide. The results showed that oxodiperoxo tungsten complex with QOH as ligand could achieve 89.8% yield of adipic acid at 90°C by refluxing for 20 h.     

Almost Periodic Solutions by the Harmonic Balance Method

Acta Mathematicae Applicatae Sinica, English Series - We consider non-autonomous ordinary differential equations in two cases. One is the one-dimensional case that admits a condition of...     

Gompertz曲线参数估计新方法(英文)

我们提出了一种估计Gompertz曲线参数的新方法。通过研究产生Gompertz曲线的Gompertz微分方程,利用微分与差分的基本原理,借助多元回归方法,给定显著性水平α,在置信水平1-α下,估计出Gomper-tz曲线的参数。应用该结果研究中国1994年至2007年的汽车年销售数据,获得相应的预测数据和2008的预测值(1090万辆)。MAPE=5.58<10,显示模型有预测精度较高。     

高校实验教学质量提升的思考与路径探讨*

实验教学是高校多类专业本科教育和人才培养的重要实践环节之一,实验教学质量关系着本科教育的成效,是一个系统化的工程。实验教学必须坚持践行“学生中心、产出导向、持续改进”三大质量建设理念。基于此,高校应进行全方位审视,明确影响实验教学质量的因素及其提升路径,制定和落实可行的改革举措,着力加强实验教学质量标准化建设,更精、更细、更实地做好实验教学质量管理的各项工作,提高高校人才培养的产出和效能,为培养满足新时代社会主义现代化建设需求的高层次专业人才做出应有贡献。基于近几年海南师范大学化学国家级实验教学示范中心的教学实践,就实验教学质量提升问题做了多视角的深入思考与探讨,提出的改进路径可供同行们参考。