《高分子化学》双语教学的“战略性”思考

从当前国际形势、国家教育政策、高分子化学教学的全局出发,分析了《高分子化学》双语教学的重要性,讨论了开展《高分子化学》双语教学的前提条件.从“战略性”的思考角度,探讨了《高分子化学》双语教学在基础英语、专业英语方面的问题以及考评方法等.显然,树立“战略性”的思维模式,从大局出发,促进各学科协调发展、共同进步,对提高《高分子化学》双语教学效果,建立和完善培养高分子国际性专业人才的教育体系具有非常重要的意义.     

Gold-catalyzed cyclization of enediynes and arenediynes to 6H-benzo[c]chromen-6-one and dibenzo[c,h]chromen-6-one derivatives

The efficient synthesis of 6H-benzo[c]chromen-6-one and dibenzo[c,h]chromen-6-one derivatives is described. Thus, treatment of arenediynes 1 and enediynes 5 with 5?mol % Ph₃PAuCl and 10?mol % of AgSbF₆ in refluxing toluene gave dibenzo[c,h]chromen-6-ones 4 and 6H-benzo[c]chromen-6-ones 6, in good yields, respectively.     

Facile,single-pot preparation of nanoporous SiO2 particles (carrier) with AgNPs at core and crust for controlled disinfectant release

This study demonstrates a novel, facile and one-pot approach to synthesize silica nanoparticles with silver at core and crust (SiNP-AgCC). A modified Stöber method was used to make SiNP-AgCC. A significant reduction in the size of SiO₂ nanoparticles was seen, with 2–5 nm AgNPs being uniformly distributed on the surface and 10–20 nm AgNPs in the center. A typical mesoporous SiO₂ particle (SiNP) produced using the Stöber method was transformed to nanoporous SiO₂ by this modified Stöber method. Nanoporous SiO₂ particles with silver in the center are advantageous for slow and consistent Ag⁺ release, which was confirmed by Ag⁺ ion release test. Antibacterial activities of the samples were tested to evaluate the disinfection performance of the samples on gram-negative bacteria (Escherichia coli) using disk diffusion and the LB-agar method. SiNP-AgCC showed prolonged silver release for more than 20 days and improved antibacterial properties even after five days of incubation.     

新工科背景下湖南大学应用化学专业的改革与建设

It is necessary to develop new engineering-directed applied chemistry major on the basis of chemistry major and to remodel the current applied chemistry education according to the concept of emerging engineering. Herein, emendation in 2020 version of applied chemistry education plan and researches on teaching renovations for applied chemistry major in Hunan University is introduced. Through the adjustments of education goals, course systems, teaching contents and teaching models, we wish to highlight the central status of the educations that integrates morality and ability. In addition to the inheritance of the specialty in corrosion and protection, it is expected to further satisfy the need of graduates for the industries such as new materials, new energy, high-tech production, environmental protection, and new generation of information technique. At last, future trends and perspectives in emerging engineering applied chemistry is proposed.     

Envisioning the infinite by projecting finite properties

We analyze interviews with 24 post-secondary students as they reason about infinite processes in the context of the tricky Tennis Ball Problem. By metaphorically projecting various properties from the finite states such as counting and indexing, participants envisioned widely varying final states for the infinite process. Depending on which properties they attended to, some participants recognized contradictions arising from these infinite projections and sought to resolve the contradictions in non-dismissive ways. The findings indicate that increasing their meta-level awareness of the features of their mental constructions may help students overcome common difficulties with the infinite.     

What does it mean for a student to understand the first-year calculus? Perspectives of 24 experts

This article presents the views of 24 nationally recognized authorities in the field of mathematics, and in particular the calculus, on student understanding of the first-year calculus. A framework emerged that includes four overarching end goals for understanding of the first-year calculus: (a) mastery of the fundamental concepts and-or skills of the first-year calculus, (b) construction of connections and relationships between and among concepts and skills, (c) the ability to use the ideas of the first-year calculus, and (d) a deep sense of the context and purpose of the calculus. Each end goal for student understanding is explored in detail and the potential for using the framework as an organizational tool is discussed.     

Spectral analysis informs the proper frequency in the sampling of financial time series data

Applied econometricians tend to show a long neglect for the proper frequency to be considered while sampling the time series data. The present study shows how spectral analysis can be usefully employed to fix this problem. The case is illustrated with ultra-high-frequency data and daily prices of four selected stocks listed on the Sao Paulo stock exchange.     

Carbon nanotori as traps for atoms and ions

Carbon nanotori surely represent an ideal location to trap both charged and uncharged atoms, since they are open, accessible and possess strong attractive energy. In this paper, we investigate the plausibility of carbon nanotori as atomic traps and we use the continuum approximation together with the Lennard–Jones potential to model the encapsulation of an atom or ion by a nanotorus. The critical geometric factors such as the minor and major radii, i.e. r and R   of the nanotorus, for which the maximum interaction between the atom and the nanotorus occurs, are determined. For various atoms, assumed situated along the axis of the torus, the minimum potential energy between the atom and the nanotorus is calculated and compared, and shown to be approximately kηεσ²$k\eta \epsilon {\sigma }^2$, where η$\eta$ is the uniform atomic density, ε$\epsilon$ and σ$\sigma$ are the Lennard–Jones well depth and the van der Waals radius, respectively, and k is a universal non-dimensional constant with the approximate value −12.42. The results given in this paper might be used for future drug delivery and biosensing design.     

Formation of high aspect ratio polyamide-6 nanofibers via electrically induced double layer during electrospinning

In the present study, the formation of high aspect ratio nanofibers in polyamide-6 was investigated as a function of applied voltage ranging from 15 to 25 kV using electrospinning technique. All other experimental parameters were kept constant. The electrospun polyamide-6 nanofibers were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF). FE-SEM images of polyamide-6 nanofibers showed that the diameter of the electrospun fiber was decreased with increasing applied voltage. At the critical applied voltage, the polymer solution was completely ionized to form the dense high aspect ratio nanofibers in between the main nanofibers. The diameter of the polyamide-6 nanofibers was observed to be in the range of 75-110 nm, whereas the high aspect ratio structures consisted of regularly distributed very fine nanofibers with diameters of about 9-28 nm. Trends in fiber diameter and diameter distribution were discussed for the high aspect ratio nanofibers. TEM results revealed that the formation of double layers in polyamide-6 nanofibers and then split-up into ultrafine fibers. The electrically induced double layer in combination with the polyelectrolytic nature of solution is proposed as the suitable mechanisms for the formation of high aspect ratio nanofibers in polyamide-6.     

第11届全国大学生化学实验邀请赛物理化学操作考试试题的评析与思考

介绍了第11届全国大学生化学实验邀请赛物理化学实验的命题思路、实验试题的背景及考试情况,并对竞赛中所反映的当前实验教学中存在的问题进行了总结分析。