Polarization dependent plasmonic modes in elliptical graphene disk arrays.

Plasmonic modes at mid-infrared wavelengths in elliptical graphene disk arrays were studied. Theoretically, analytical expressions for the modes and their dependence on the size, Fermi energy and the permittivity of substrate materials of the ellipses were derived. Experimentally, the elliptical graphene disks were fabricated and their plasmonic modes were characterized with the polarization-resolved extinction spectra. Both experimental and analytical results show that two electrical dipole modes, whose dipole moments are orthogonal to each other and along the major and minor axis of the ellipse respectively, exist in the elliptical disks. By adjusting the polarization directions of the incident light, the two orthogonal plasmonic modes could be excited either together or separately, showing that the optical properties of elliptical graphene disks are highly polarization dependent. By using ultraviolet illumination to change the Fermi energy of the elliptical graphene disks, the two modes can be tuned dynamically. Moreover, the highly polarization dependent modes are able to couple with the surface phonons of the substrate, leading to polarized plasmon-phonon polaritons. Thus the elliptical graphene disks can provide more degrees of freedom to design the mid-infrared polarization-resolved photonic devices.

Enhanced light-matter interactions in graphene-covered dielectric magnetic mirrors.

Enhanced interactions of light with graphene on the surface of a lossless dielectric magnetic mirror (DMM) are studied theoretically and experimentally in the visible range, where the DMM is composed of truncated dielectric photonic crystals (PCs). The absorption of graphene on the DMM was enhanced by about 4-fold for the spectral range within the forbidden gap of PCs over a wide range of incidence angles for both transverse electric and transverse magnetic polarizations compared with that of free-standing graphene. Moreover, the enhanced local electric field on the DMM surface led to much better detection efficiencies of the photocurrent, Raman spectroscopy and enhanced third-harmonic generation of graphene. These results offer a new way to achieve an enhanced interaction of light with graphene and develop new compact graphene-based devices.

Microwave-assisted or Cu-NHC-catalyzed cycloaddition of azido-disubstituted alkynes: bifurcation of reaction pathways.

Microwave irradiation promoted the intramolecular cycloaddition of 2-azidoacetamides derived from α-chiral propargylic amines, affording 1,4,5-trisubstituted triazoles 4 bearing a chiral aminomethyl side chain at C5. In contrast, for the same substrates 3a-k, Cu(I)-NHC complexes catalyzed the intermolecular cycloaddition in an unexpected desilylative fashion, leading to 1,4-disubstituted triazoles 5. This demonstrates that 1-silyl alkynes can be employed as substrates for CuAAC with a suitable coupling partner.

Gender differences in footwear characteristics between half and full marathons in China: a cross-sectional survey.

There are concerns about the risk of injuries caused by marathons in China. Since male and female runners have different injury risks, gender differences in running shoe functionality should be further complemented. A supervised questionnaire survey of 626 marathon runners was collected. The questionnaire was categorized into four sections: (1) participant profile, (2) importance of shoe properties, (3) functional evaluation of shoe properties and (4) importance ranking of shoe properties. The Mann-Whitney U test, Fisher's exact test of cross tabulation and Chi-square test, and two-way ANOVA were used to analyze the results of this survey. The significance level was set at P < 0.05. The full marathon participants were older than the half marathon participants. There was no gender difference in the importance of shoe features to elite runners. In addition, women are more concerned about upper elasticity and have higher requirements for running shoes than men. Women were more focused on injury prevention, while men were more focused on running performance. Heel cushioning was identified by all participants as the most important running shoe feature. There were no gender differences between elite players' demand for running shoes, but significant gender differences were found between genders at other running levels.

A Programmable Nanofabrication Method for Complex 3D Meta-Atom Array Based on Focused-Ion-Beam Stress-Induced Deformation Effect.

Due to their unique electromagnetic properties, meta-atom arrays have always been a hotspot to realize all kinds of particular functions, and the research on meta-atom structure has extended from two-dimensions (2D) to three-dimensions (3D) in recent years. With the continuous pursuit of complex 3D meta-atom arrays, the increasing demand for more efficient and more precise nanofabrication methods has encountered challenges. To explore better fabrication methods, we presented a programmable nanofabrication method for a complex 3D meta-atom array based on focused-ion-beam stress-induced deformation (FIB-SID) effect and designed a distinctive nanostructure array composed of periodic 3D meta-atoms to demonstrate the presented method. After successful fabrication of the designed 3D meta-atom arrays, measurements were conducted to investigate the electric/magnetic field properties and infrared spectral characteristics using scanning cathodoluminescence (CL) microscopic imaging and Fourier transform infrared (FTIR) spectroscopy, which revealed a certain excitation mode induced by polarized incident IR light near 8 µm. Besides the programmability for complex 3D meta-atoms and wide applicability of materials, a more significant advantage of the method is that a large-scale array composed of complex 3D meta-atoms can be processed in a quasi-parallel way, which improves the processing efficiency and the consistency of unit cells dramatically.