(3S,4S)-4-氨基-3-羟基-6-甲基庚酸的合成

价廉易得的L-亮氨酸先以苄基同时保护氨基及羧基得(S)-2-(二苄胺基)-4-甲基戊酸苄酯,进而在碱性条件下与乙腈发生亲核取代反应得(S)-4-(二苄胺基)-6-甲基-3-氧代庚腈,再经硼氢化钠选择性还原羰基得(3S,4S)-4-(二苄胺基)-3-羟基-6-甲基庚腈,用双氧水氧化得(3S,4S)-4-(二苄胺基)-3-羟基-6-甲基庚酸,最后在Pd(OH)2/C-H2作用下脱掉苄基得到(3S,4S)-4-氨基-3-羟基-6-甲基庚酸,即(3S,4S)-statine。整个合成路线总产率为33.6%。     

Vertically aligned γ-AlOOH nanosheets on Al foils as flexible and reusable substrates for NH<Subscript>3</Subscript> adsorption

Vertically aligned γ-AlOOH nanosheets (NSs) have been successfully fabricated on flexible Al foils via a solvothermal route without morphology-directing agents. Three different reaction temperature (25, 80, and 120 ?C) and time (30 min, 45 min, and 24 h) are discussed for the growth period, which efficiently tune the density and size of the γ-AlOOH NSs. Meanwhile, the growth speed of the nanosheets confirms that dominant growth stage is seen in the initial 45 min. Furthermore, the interlayer of the γ-AlOOH NSs displays an average height of 140 nm and superhydrophilicity. By dynamic adsorption, the assynthesized γ-AlOOH NSs exhibit an outstanding NH₃ adsorption capacity of up to 146 mg/g and stably excellent regeneration for 5 cycles. The mechanism of NH₃ adsorption on the in-plane of the γ-AlOOH NSs is explained by the Lewis acid/base theory. The H-bond interactions among the NH₃ molecules and the edge groups (-OH) further improve the capture ability of the nanosheets.     

大学化学本科教学中综合化学实验的设计——锂离子电池制作

将CR2032型锂离子电池的制作及电化学性能测试实验设计为大学化学本科生的综合实验并将其应用于本科教学中，建立起基于锂离子电池用正极材料的合成、表征、电极制备及电池组装和性能测试的综合性开放实验。实验以无机材料制备为实验基础，以电化学原理为理论基础，通过文献查阅、确立合成路线、材料制备及表征、锂离子电池制作与测试等多项综合实验内容，使学生了解目前常见的正极材料种类、合成方法、电池的基本结构以及电池性能的测试方法。在教学过程中以学生主动探索为主体，培养学生的科学探究素养，锻炼学生查阅文献、自主设计实验和合作开发的能力。     

A 2-dimensional gradual period photonic heterostructure possessing omnidirectional band gap in visible range made by holography

A 2-dimensional gradual period photonic heterostructure was made with holography by use of non-uniform swelling effect of dichromated gelatin during processing. In this structure, the symmetric point group of triangle lattice was debased to C_2V from C_6V. Theoretical analysis and experimental results show that omnidirectional band gap in visible range can be achieved with this kind of heterostructure made by low refractive index materials.     

L- and M-weak compactness of positive semi-compact operators

We present some necessary and sufficient conditions for positive semi-compact operators being L-weakly compact and M-weakly compact respectively.     

Study on prediction of noise produced by stern wake-duct-propeller interaction

The mechanism and prediction methods of low-frequency discrete spectrmu noise of ducted propellers are studied. The acoustic pressure field of ducted propellers is divided into the propeller radiated field and the duct scattered field based on the linear acoustic theory. First of all, the flow field is analyzed with unsteady panel method to get the unsteady force, and then the pressure data are used as the sources for Ffowcs Williams-Hawings formulation to predict the propeller radiated field, meanwhile, the duct scattered field is obtained by Kirchoff integral equation. Through the analysis and calculation of a ducted propeller case, it is found that the duct scattered sound field is a small quantity compared with propeller radiated sound field under low-frequency and short duct condition; Also the predicted discrete spectrum noise level of ducted propellers is compared with that of full-scale propellers by experiment, verifying the predicted results are able to reflect the full-scale propellers＇ discrete spectrum noise level properly.     

锡汞齐工艺中Hg对铜镜的影响

采用X射线衍射、扫描电镜等实验手段,对涂抹锡汞齐的青铜样品进行分析,讨论Hg在铜镜表面处理过程中可能会产生的作用,证明铜镜中Hg并不能完全挥发,残留的Hg在铜镜中会不断扩散,最终使铜镜表面逐渐模糊,不能用于映照。     

非经典碳正离子简介

非经典碳正离子作为一种特殊的反应中间体,具有重要的理论和实际研究的意义。本文以碳正离子理论的发展为主线,以历史上非经典碳正离子(特别是降冰片基正离子)之争为中心,简要综述了Winstein、Brown和Olah三人的观点,并结合最新进展进行评述。此外,还对除降冰片基正离子之外的非经典碳正离子进行了适当的讨论。     

基于配体结构的Grb2-SH2抑制剂的结构优化:更高的活性、更少的电荷、更低的肽性

生长因子受体结合蛋白2(Grb2)在致癌基因Ras活化的信号传导通路中起着关键作用,目前被广泛认为是抗肿瘤药物设计的优秀靶标.对Grb2-SH2抑制剂的研究进展进行了综述,主要针对关键残基磷酸酪氨酸的高电荷性和多肽结构的低生物相容性两个缺陷,基于天然配体与Grb2-SH2相互作用的结构特征,围绕提高活性和简化结构开展的系统构效关系和合理结构优化研究,为进一步开发磷酸酪氨酸介导的Grb2-SH2抑制剂成为新型抗肿瘤药物提供结构和理论基础.