Critical Conformational Change of Poly(oxypropylene)diamines in Layered Aluminosilicate Confinement

The intercalation of aluminosilicate clays proceeds via a critical conformation change. Ion exchange of the poly(oxypropylene)diamine salts allows widening of the clay layers from 12 Å to 20 Å and then a sharp increase to 58 Å. The data indicate a critical conformation change of the intercalated amines, thus providing a new way for manipulating nanomaterials and control of polymer conformations in layered silicate confinement.

Schematic illustration of POP‐amine self‐assembly in silicate confinements.     

Recent advances in heterostructured cathodic electrocatalysts for non-aqueous Li–O2 batteries

Developing efficient energy storage and conversion applications is vital to address fossil energy depletion and global warming. Li–O₂ batteries are one of the most promising devices because of their ultra-high energy density. To overcome their practical difficulties including low specific capacities, high overpotentials, limited rate capability and poor cycle stability, an intensive search for highly efficient electrocatalysts has been performed. Recently, it has been reported that heterostructured catalysts exhibit significantly enhanced activities toward the oxygen reduction reaction and oxygen evolution reaction, and their excellent performance is not only related to the catalyst materials themselves but also the special hetero-interfaces. Herein, an overview focused on the electrocatalytic functions of heterostructured catalysts for non-aqueous Li–O₂ batteries is presented by summarizing recent research progress. Reduction mechanisms of Li–O₂ batteries are first introduced, followed by a detailed discussion on the typical performance enhancement mechanisms of the heterostructured catalysts with different phases and heterointerfaces, and the various heterostructured catalysts applied in Li–O₂ batteries are also intensively discussed. Finally, the existing problems and development perspectives on the heterostructure applications are presented.

The structure–function relationships between heterostructures and their catalytic properties were discussed in detail, and the challenges and improvement strategies for heterostructure based cathodes towards Li–O₂ catalysis were also summarized.     

In-plane free vibration of a single-crystal silicon ring

In this paper the natural frequencies and the associated mode shapes of in-plane free vibration of a single-crystal silicon ring are analyzed. It is found that the Si(1 1 1) ring is two-dimensionally isotropic in the (1 1 1) plane for elastic constants but three-dimensionally anisotropic, while the Si(1 0 0) ring is fully anisotropic. Hamilton’s principle is used to derive the equations of vibration, which is a set of partial differential equations with coefficients being periodic in polar variable. Expressing the radial and tangential displacements in sinusoidal form with non-predetermined amplitudes, and through the integration with respect to the circumferential variable, the original governing equations in partial differential form can be converted into the amplitude equations in ordinary differential form. The exact expressions for frequencies and mode shapes are obtained. It is found that for Si(1 0 0) rings the frequencies of a pair of modes, which are equal for an isotropic ring, split due to the anisotropic effect only for the second in-plane vibration mode. The phenomena of frequency splitting and degenerate modes can be proved either based on the conservation of averaged mechanical energy or by the concept of crystallographic symmetry groups. When the single-crystal silicon is replaced by the polycrystalline silicon, which is isotropic in elastic constants, the derived equations for frequencies correctly predict the vanishing of the phenomenon of frequency splitting.     

Synthetic Applications of 3‐(Phenylsulfinyl)‐3‐sulfolene

The title compound 2 was readily prepared by MCPBA oxidation of the sulfide 1. Thermal desulfonylation of 2 gave the sulfoxide‐substituted diene 3. The Diels‐Alder reactions of 3 with various dienophiles gave the cyclized products 4‐9 in good yields. The regiochemistry was found to be dominated by the phenylsulfinyl group, but could be reversed by the presence of a Lewis acid. Deprotonation of 2 by BuLi, followed by the reaction with alkyl halides, gave the substituted 2‐sulfolenes 10. A synthetic application of 10 was demonstrated by converting 10e to the bicyclic product 11.     

Experimental Study of Red-, Green-, and Blue-Based Light Emitting Diodes Visible Light Communications for Micro-Projector Application

In this research, an experimental short-range visible light communication link using red-, green-, and blue-based light-emitting diodes (LEDs) for portable micro-projector applications is presented. A Reconfigurable design of a post-equalizer aimed to improve the inherent narrow modulation bandwidth of red-, green-, and blue-based LEDs has been experimentally implemented, and its effectiveness with optical filters at the receiver is investigated. Reflective liquid-crystal-on-silicon-based micro-projection architecture, widely used in portable micro-projectors, was set up to evaluate the proposed visible light communication system. The measurement results demonstrated that a significant aggregative bandwidth improvement of 162 MHz as well as an aggregative data transmission rate of nearly 400 Mb/s can be achieved by using a non-return-to-zero–on-off keying (NRZ–OOK) modulation scheme based on only one polarization state of incident light without any offline signal processing.     

自忆模式中差分格式的稳定性研究

基于大气运动是一种不可逆过程的观点，引进了忆及过去时次资料的记忆函数，导出热传导的自忆性方程，研究了方程分别取Richardson和DuFort-Frankel格式，回溯阶p取1时的稳定性.探讨了多时刻模式中数值积分有时发散的问题，揭示了由过去时次资料动态求取记忆函数，改变了原定设计的差分格式，且它是一个时间平滑因子的本质. 关键词： 回溯阶差分格式 多时次 稳定性 记忆性     

Acyclotomy of torsion in the CM case

The Ramanujan Journal - Let F be a number field, and let $$F^{{\text {cyc}}}$$ be obtained by adjoining to F all the roots of unity. We show that as E ranges over all elliptic curves defined over...     

Formal synthesis of schulzeines B and C: A new route to Gurjar's lactams

Described is a formal synthesis of racemic schulzeines B and C that intercepts intermediates developed by Gurjar and co-workers. The synthetic sequence features an annulative coupling of a ketimine and acrylic acid enabling the construction of the benzoquinolizidine nucleus in a highly convergent manner. We also examined a continuous-flow version of the thermal aza-annulation, which proved less practical as compared to the batch processes.