从纸上到躬行:基于有机化学理论和文献的实验设计及优化之低年级本科教学初探

国际公认化学类本科生的培养目标是能够胜任化学专业技术职务,或具备相关的科研能力,而核心考核因素之一被认为是能否以纸上所学理论和文献助力实验方案的设计,并躬行实现。我们在有机化学基础实验教学中融合以上理念,初步探索出适合低年级本科生的以理论知识和文献指导实验设计和优化的教学策略。以乙酰二茂铁的合成为例,以问题-讨论为主线,引导学生从文献、底物的电子结构、傅-克酰基化反应机理和重要的物理化学性质等进行综合分析,设计乙酰二茂铁的合成路线,鼓励学生对教材提出质疑并自主设计和开展验证实验,对教材中的经典方法持续优化。学生深度参与实验路线设计和关键参数设置,沉浸学术研究氛围,敢于质疑并验证,提升了将已学理论转化为解决实际问题的能力,一定程度上有利于其科学思维和科研执行力的培养,提高其从事化学专业技术职务或相关科研工作的核心竞争力。     

溶剂工程调控钙钛矿薄膜中PbI2和PbI2(DMSO)的形成

钙钛矿太阳能电池以其高效、低成本的特点备受关注。到目前为止,钙钛矿太阳能电池的最高光电转换效率已经超过25%,显示出良好的应用前景。钙钛矿薄膜的结晶性能是决定器件性能的关键,因此,调控钙钛矿薄膜的生长过程至关重要。本工作中,我们发现通过简单调节前驱体溶剂,即调节二甲基亚砜：1, 4-丁内酯: N, N-二甲基甲酰胺(DMSO : GBL : DMF)的三种混合溶剂的比例,可实现钙钛矿薄膜中PbI₂和PbI₂(DMSO)含量的调节,从而调节电池的器件性能。此外,本工作系统研究了PbI₂和PbI₂(DMSO)的含量对器件性能的影响。结果表明,PbI₂(DMSO)的形成会导致300–425 nm波长范围内电池的外量子效率(EQE)降低,从而导致器件性能下降。相反,通过在前驱体溶液中添加额外的碘化亚甲基铵(MAI),可以抑制PbI₂和PbI₂(DMSO)的形成。     

Controllable Photoelectric Properties of Carbon Dots and Their Application in Organic Solar Cells

Organic solar cells are a current research hotspot in the energy field because of their advantages of lightness,translucency,roll to roll printing and building integration.With the rapid development of small molecule acceptor materials with high-performance,the efficiency of organic solar cells has been greatly improved.Further improving the device efficiency and stability and reducing the cost of active layer materials will contribute to the industrial development of organic solar cells.As a novel type of carbon nanomaterials,carbon dots gradually show great application potential in the field of organic solar cells due to their advantages of low preparation cost,non-toxicity and excellent photoelectric performance.Firstly,the synthesis and classification of carbon dots are briefly introduced.Secondly,the photoelectric properties of carbon dots and their adjusting,including adjustable surface energy level structure,good film-forming performance and up/down conversion characteristics are summarized.Thirdly,based on these intrinsic properties,the feasibility and advantages of carbon dots used in organic solar cells are discussed.Fourthly,the application progress of carbon dots in the active layer,hole transport layer,electron transport layer,interface modification layer and down-conversion materials of organic solar cells is also reviewed.Finally,the application progress of carbon dots in organic solar cells is prospected.Several further research directions,including in-depth exploration of the controllable preparation of carbon dots and their application in the fields of interface layer and up/down conversion for improving efficiency and stability of device are pointed out.     

A modified super-efficiency DEA model for infeasibility

The super-efficiency data envelopment analysis (DEA) model is obtained when a decision making unit (DMU) under evaluation is excluded from the reference set. This model provides for a measure of stability of the “efficient” status for frontier DMUs. Under the assumption of variable returns to scale (VRS), the super efficiency model can be infeasible for some efficient DMUs, specifically those at the extremities of the frontier. The current study develops an approach to overcome infeasibility issues. It is shown that when the model is feasible, our approach yields super-efficiency scores that are equivalent to those arising from the original model. For efficient DMUs that are infeasible under the super-efficiency model, our approach yields optimal solutions and scores that characterize the extent of super-efficiency in both inputs and outputs. The newly developed approach is illustrated with two real world data sets.     

Catalysis and regioselectivity of the aqueous Heck reaction by Pd(0) nanoparticles under ultrasonic irradiation

An aqueous Heck reaction carried out under ultrasonic irradiation at the ambient temperature (25 degrees C) has been shown in this study to afford high yields of corresponding products. It was found that as a catalyst for the reaction palladium forms nanoparticles in-situ, characterized by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) analyses, and can be recycled. Furthermore, the Heck reaction under such mild and environmentally friendly conditions offers excellent regioselectivity of para- over ortho-substitution in phenyl iodides especially with electron-donating groups.     

Collision operator including large-angle scattering for moderately coupled plasma

A new approach has been developed to treat the large-angle as well as the small-angle binary collisions in high temperature and high density plasmas when the test particle distribution function f_α is even function about the test velocity and the relations of the mass and the velocity between the test particles and the field particles are satisfied with m_αm_β (such as electron–ion collision or Lorentz-gas model) and . With the approach, the Boltzmann collision operator is derived to be suitable for the plasma considered as weakly coupled (Coulomb logarithm ) and moderately coupled , i.e., for the electron–ion coupling constant Γ_ei<0.1. The modified collision operator has a direct and practical connection to the Rosenbluth potentials, the new reduced electron–ion collision operator differs from the original Fokker–Planck operator for Coulomb collisions by terms of order . Moreover, some calculations of relaxation rate and transport properties are given for new reduced electron–ion collision operator that shows corrections.     

Synthesis and evaluation of in vitro anticancer activity of novel solasodine derivatives

<正>Solasodine 11 is a steroidal alkaloid with various biological activities.Herein,8 novel solasodine derivatives were synthesized and their effect on prostate cancer cell proliferation was assessed in vitro.Significant improvement in antiproliferative activity was achieved among some of the synthetic analogs.In particular,19 exhibited the most potent inhibitory effect against the proliferation of PC-3 cell line(IC_(50) = 3.91μmol/L).     

与含有三个位势矩阵谱问题相联系的非线性发展方程族及其Hamilton结构

从含有三个位势的4×4矩阵谱问题出发,导出两类非线性发展方程.然后利用迹公式,给出了这两类方程的广义Hamilton结构.     

Improvement of the WENO scheme smoothness estimator

This paper has analyzed the weights of the fifth‐order weighted essentially nonoscillatory scheme suggested by Jiang and Shu and a modified smoothness estimator is suggested to improve the accuracy. Using a function of the minimum and maximum of the original smoothness estimators, the new smoothness estimators have smaller variation among them than the original ones in smooth regions. Hence, as the new weights are closer to the optimal weights, the numerical accuracy is improved. Several numerical experiments are presented to demonstrate the accuracy and robustness of the new scheme. Copyright © 2009 John Wiley & Sons, Ltd.