Entire Transmission in Negative Directions through a Single Layer of Nanorods

We numerically investigate the regulation of beam direction by a single layer of high electrical permittivity nanorods with two kinds of cross-arranged radii. It is found that an oblique incident optical beam transmits more than 95% with a wide range wavelength of 80 nm near 1550 nm in a negative direction. In particular the efficiency can be up to 100% around the wavelength of 1550nm at a wide-range angle. The results are very promising for designing subwavelength optical elements to realize beam steering in optical integrated circuits.     

Combined Dynamic Kinetic Resolution and C−H Functionalization for Facile Synthesis of Non-Biaryl-Atropisomer-Type Axially Chiral Organosilanes

Although asymmetric C−H functionalization has been available for the synthesis of structurally diverse molecules, catalytic dynamic kinetic resolution (DKR) approaches to change racemic stereogenic axes remain synthetic challenges in this field. Here, a concise palladium-catalyzed DKR was combined with C−H functionalization involving olefination and alkynylation for the highly efficient synthesis of non-biaryl-atropisomer-type (NBA) axially chiral oragnosilanes. The chemistry proceeded through two different and distinct DKR: first, an atroposelective C−H olefination or alkynylation produced axially chiral vinylsilanes or alkynylsilanes as a new family of non-biaryl atropisomers (NBA), and second, the extension of this DKR strategy to twofold o,o′-C−H functionalization led to the multifunctional axially chiral organosilicon compounds with up to >99 % ee.     

Photo‐Powered Collapse of Supramolecular Polymers Based on an Overcrowded Alkene Switch

A supramolecular polymer was constructed from a light‐driven overcrowded alkene switch modified with two alkylated gallic acid amide pendants ( MSP‐1 ). Upon UV irradiation, stable MSP‐1 isomerized into unstable MSP‐2 , which induced the effective collapse of well‐defined cross‐linked supramolecular polymers, and the reassembly can be realized by aging at low temperature.     

X-Mechanics——An endless frontier

In contrast to the conventional wisdom that mechanics is a relatively mature subject, the new manifestation of mechanics in an extended or crossed form is unfolding. Mechanics is now powering all subjects, from physical sciences, life sciences to social sciences. We name this new phase for the development of mechanics X-Mechanics. The present article outlines the contents of X-Mechanics from four aspects: cross media, cross scales, cross compliances, and cross cyber/physical spaces. X-Mechanics constitutes an endless frontier of science and technology.     

Accuracy Improvement of Geographical Indication of Rice By Laser-Induced Breakdown Spectroscopy Using Support Vector Machine with Multi-Spectral Line

Journal of Applied Spectroscopy - Mislabeling and adulteration are problems in the food industry. Considering the frequent occurrence of safety affairs in agricultural products, it is necessary to...     

Coherent effects in a three-photon CPT process of Ca+

Linewidth narrowing and other quantum coherent effects based on three-photon coherent population trapping (CPT) in Ca⁺ ions are investigated. If the propagation directions of the three lasers obey the phase matching condition, the dark linewidth resulting from the CPT can be very narrow, and it can be controlled by adjusting the parameters of the lasers.     

Numerical investigation of flow over a two-dimensional square cylinder with a synthetic jet generated by a bi-frequency signal

Applied Mathematics and Mechanics - The flow around a square cylinder with a synthetic jet positioned at the rear surface is numerically investigated with the unsteady Reynolds-averaged...     

New synthetic methodology leading to a series of novel heterocyclic α-aminophosphonates: a very attractive expansion of Kabachnik–Fields reaction

A convenient one-pot three-component approach leading to synthesis of a series of novel heterocyclic α-aminophosphonates starting either from 2-hydroxyacetophenones or 2-hydroxybenzaldehyes was developed.     

Sphere-cone-polynomial special window with good aberration characteristic

Optical windows with external surfaces shaped to satisfy operational environment needs are known as special windows. A novel special window, a sphere-cone-polynomial (SCP) window, is proposed. The formulas of this window shape are given. An SCP MgF2 window with a fineness ratio of 1.33 is designed as an example. The field-of-regard (FOR) angle is ±75°. From the window system simulation results obtained with the calculated fluid dynamics (CFD) and optical design software, we find that compared to the conventional window forms, the SCP shape can not only introduce relatively less drag in the airflow, but also have the minimal effect on imaging. So the SCP window optical system can achieve a high image quality across a super wide FOR without adding extra aberration correctors. The tolerance analysis results show that the optical performance can be maintained with a reasonable fabricating tolerance to manufacturing errors.