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As a key skill for language learners, oral communication ability is one of the most important factors to measure one person’s overall quality. Being a widely used language, English has become an important communicative medium worldwide. Oral English teaching is an important part of the whole process of English learning and is generally an emerging topic for the education circle. However, the traditional oral English teaching model has no significant effect on improving oral English performance. Therefore, this paper studies the mixed oral English teaching model under the guidance of core qualities. The connotation of core literacy of oral English is analyzed and the general framework of the core literacy system of oral English is constructed. Then, the relationship between the four elements of English subject core literacy is examined based on the classification of the spoken English teaching resources. Next, the integration of spoken English teaching resources is realized and the oral English knowledge ontology and the cultural differences between Chinese and Western analysis are explored. Finally, a task-based oral English teaching hybrid model is developed. The experimental results show that there is a significant difference in the oral English level of the students before and after the experiment. The model can improve the overall quality and overall performance of English learning for our society.

All-optical magnetic switching promises ultrafast, high-resolution magnetisation control with the technological attraction of requiring no magnetic field. Existing all-optical switching schemes are driven by ultrafast transient effects, typically requiring power-hungry femtosecond-pulsed lasers and complex magnetic materials. Here, we demonstrate deterministic, all-optical magnetic switching in simple ferromagnetic nanomagnets (Ni$_{81}$Fe$_{19}$, Ni$_{50}$Fe$_{50}$) with sub-diffraction limit dimensions using a focused low-power, linearly-polarised continuous-wave laser. Isolated nanomagnets are switched across a range of dimensions, laser wavelengths and powers. All square-geometry artificial spin ice vertex configurations are written, including ground-state and energetically-unfavourable `monopole-like' states at powers as low as 2.74 mW. Usually, magnetic switching with linearly polarised light is symmetry-forbidden; however, here the laser spot has a similar size to the nanomagnets, producing an absorption distribution dependent on the relative nanoisland-spot displacement. We attribute the observed deterministic switching to the transient dynamics of this asymmetric absorption. No switching is observed in Co samples, suggesting the multi-species nature of NiFe alloys plays a role in reversal. The results presented here usher in cheap, low-power optically-controlled devices with impact across data storage, neuromorphic computation and reconfigurable magnonics.

Three-dimensional Dirac semimetal Cd3As2 has been considered as an excellent candidate for applications of electronic devices owing to its ultrahigh mobility and air-stability. However, current researches are focused mainly on the use of gate-voltage to control its carrier transport tunability, while the manipulation of transport properties by element-doping is quite limited. Here we report the tunable magneto-transport properties by adjusting Mn-doping in the Cd3As2 compound. We find that Mn-element doping has a strong influence on the Fermi level positions, and the Fermi energy approaches to Dirac point with higher Mn-doping. More importantly, the introduction of Mn atoms transforms diamagnetic Cd3As2 to antiferromagnetic (Cd, Mn)3As2, which provides an approach to control topological protected Dirac materials by manipulating antiferromagnetic order parameters. The Shubnikov-de Hass oscillation originates from the surface states, and the Landau fan diagram yields a nontrivial Berry phase, indicating the existence of massless Dirac fermions in the (Cd1-xMnx)3As2 compounds. Our present results may pave a way for further investigating antiferromagnetic topological Dirac semimetal and expand the potential applications in optoelectronics and spintronics.

The Raman scattering of light by molecular vibrations offers a powerful technique to 'fingerprint' molecules via their internal bonds and symmetries. Since Raman scattering is weak, methods to enhance, direct and harness it are highly desirable, e.g. through the use of optical cavities, waveguides, and surface enhanced Raman scattering (SERS). While SERS offers dramatic enhancements by localizing light within vanishingly small 'hot-spots' in metallic nanostructures, these tiny interaction volumes are only sensitive to few molecules, yielding weak signals that are difficult to detect. Here, we show that SERS from 4-Aminothiophenol (4-ATP) molecules bonded to a plasmonic gap waveguide is directed into a single mode with >99% efficiency. Although sacrificing a confinement dimension, we find 10$^4$ times SERS enhancement across a broad spectral range enabled by the waveguide's larger sensing volume and non-resonant mode. Remarkably, the waveguide-SERS (W-SERS) is bright enough to image Raman transport across the waveguides exposing the roles of nanofocusing and the Purcell effect. Emulating the $\beta$-factor from laser physics, the near unity Raman $\beta$-factor observed exposes the SERS technique in a new light and points to alternative routes to controlling Raman scattering. The ability of W-SERS to direct Raman scattering is relevant to Raman sensors based on integrated photonics with applications in gas and bio-sensing as well as healthcare., Comment: 12 pages, 4 figures in the main article; 12 pages, 7 figures in the supplementary information

8 pags., 5 figs., Mid-infrared spectroscopy is essential for chemical identification and compositional analysis because of the existence of characteristic molecular absorption fingerprints. However, it is very challenging to determine the refractive index of an analyte at low concentrations using current photonic systems in a broad mid-infrared spectral range. We propose an imaging-based nanophotonic technique for refractive index determination. The technique is based on deep subwavelength graphene plasmon nanocavities and allows for the retrieval of molecular concentration. This method features a two-dimensional array of suspended graphene plasmon nanocavities, in which the extremely high field enhancement and extraordinary compression of graphene plasmons can be realized simultaneously by combining shallow and deep cavities. This enables resonant unit cells to be read out in the spatial absorption pattern of the array at multiple spectral points, and the resulting information is then translated into the refractive index of the analytes. The proposed technique gives complementary information compared with the current nanophotonic techniques based on molecular absorption, including the ability of the refractive index measurement, the ultra-broadband measurable spectral range, and the small volume of the analyte required, thereby pushing the potential for refractometric sensing technologies into the infrared frequencies., X.X. is supported by Lee Family Scholars. S.M. acknowledges the Lee-Lucas Chair in Physics. V.G. acknowledges the Spanish Ministerio de Economia y Competitividad for financial support through the grant NANOTOPO (FIS2017-91413-EXP) and also the Ministerio de Ciencia, Innovación y Universidades through the grant MELODIA (PGC2018-095777-B-C21).

Graphene and hexagonal boron nitride (h-BN) have attracted intensive interests in very recent years because of their unique physical and chemical properties. With similar crystal structures, graphe...

Coronavirus disease 2019 (COVID‐19) has widely spread all over the world and the numbers of patients and deaths are increasing. According to the epidemiology, virology, and clinical practice, there are varying degrees of changes in patients, involving the human body structure and function and the activity and participation. Based on the World Health Organization (WHO) International Classification of Functioning, Disability and Health (ICF) and its biopsychosocial model of functioning, we use the WHO Family of International Classifications (WHO‐FICs) framework to form an expert consensus on the COVID‐19 rehabilitation program, focusing on the diagnosis and evaluation of disease and functioning, and service delivery of rehabilitation, and to establish a standard rehabilitation framework, terminology system, and evaluation and intervention systems based the WHO‐FICs.

The Raman scattering of light by molecular vibrations offers a powerful technique to ‘fingerprint’ molecules via their internal bonds and symmetries. Since Raman scattering is weak1, methods to enhance, direct and harness it are highly desirable, e.g. through the use of optical cavities2, waveguides3–6, and surface enhanced Raman scattering (SERS)7–9. While SERS offers dramatic enhancements6,15,22,2 by localizing light within vanishingly small ‘hot-spots’ in metallic nanostructures, these tiny interaction volumes are only sensitive to few molecules, yielding weak signals that are difficult to detect10 . Here, we show that SERS from 4-Aminothiophenol (4-ATP) molecules bonded to a plasmonic gap waveguide is directed into a single mode with > 99% efficiency. Although sacrificing a confinement dimension, we find > 104 times SERS enhancement across a broad spectral range enabled by the waveguide’s larger sensing volume and non-resonant mode. Remarkably, the waveguide-SERS (W-SERS) is bright enough to image Raman transport across the waveguides exposing the roles of nanofocusing11–13 and the Purcell effect14. Emulating the e-factor from laser physics15–17, the near unity Raman -factor observed exposes the SERS technique in a new light and points to alternative routes to controlling Raman scattering. The ability of W-SERS to direct Raman scattering is relevant to Raman sensors based on integrated photonics7–9 with applications in gas and bio-sensing as well as healthcare.

Structural metallic materials with excellent functional performance and lightweight features have always been the goal of material scientists’ pursuit. In this work, laminated metal composites of different thicknesses (less than 0.4 mm) composed of structural materials with great differences in deformation ability were successfully fabricated via a novel processing procedure. Ultra-high strength and excellent soft magnetic properties were combined perfectly in the ultra-thin and super-light laminated metal composite strips due to unique structural design and essential attributes of the initial materials. These results emphasize the significant potential application value of the ultra-thin laminated metal composites in the field of structural and functional integration.

Based on EGFR-TKI Osimertinib as lead compound, a series of novel macrocyclic derivatives bearing aniline pyrimidine scaffolds were designed and synthesized by macrocyclization. Their structures were identified by

methods and fabrication process

Correction to: ACS Omega 2017, 2 (7), 3640−3646. DOI: 10.1021/acsomega.7b00726

16 pags., 11 figs., Plasmonic metamaterials enable extraordinary manipulation of key constitutive properties of light at a subwavelength scale and thus have attracted significant interest. Here, we report a simple and convenient nanofabrication method for a novel meta-device by glancing deposition of gold into anodic aluminum oxide templates on glass substrates. A methodology with the assistance of ellipsometric measurements to examine the anisotropy and optical activity properties is presented. A tunable polarization conversion in both transmission and reflection is demonstrated. Specifically, giant broadband circular dichroism for reflection at visible wavelengths is experimentally realized by oblique incidence, due to the extrinsic chirality resulting from the mutual orientation of the metamaterials and the incident beam. This work paves the way for practical applications for large-area, low-cost polarization modulators, polarization imaging, displays, and bio-sensing., Beijing Municipal Commission of Education (BJJWZYJH01201910007022); National Natural Science Foundation of China (61775019).

17 pags., 10 figs., The breathing honeycomb lattice hosts a topologically non-trivial bulk phase due to the crystalline-symmetry of the system. Pseudospin-dependent edge states, which emerge at the interface between trivial and non-trivial regions, can be used for the directional propagation of energy. Using the plasmonic metasurface as an example system, we probe these states in the nearand far-field using a semi-analytical model. We provide the conditions under which directionality was observed and show that it is source position dependent. By probing with circularly-polarised magnetic dipoles out of the plane, we first characterise modes along the interface in terms of the enhancement of source emissions due to the metasurface. We then excite from the far-field with non-zero orbital angular momentum beams. The position-dependent directionality holds true for all classical wave systems with a breathing honeycomb lattice. Our results show that a metasurface in combination with a chiral two-dimensional material, could be used to guide light effectively on the nanoscale., M.P., R.V.C and P.A.H. acknowledge funding from the Leverhulme Trust. V.G. acknowledges the Spanish Ministerio de Economia y Competitividad for financial support through the grant NANOTOPO (FIS2017-91413-EXP) and also the Ministerio de Ciencia, Innovación y Universidades through the grant MELODIA (PGC2018-095777-B-C21). P.A.H. acknowledges financial support from Fundação para a Ciência e a Tecnologia and Instituto de Telecomunicações under projects UID/EEA/50008/2020 and the CEEC Individual program with reference CEECIND/03866/2017. S.A.M. acknowledges the Lee-Lucas Chair in Physics.

Rapid progress in nonlinear plasmonic metasurfaces enabled many novel optical characteristics for metasurfaces, with potential applications in frequency metrology [Zimmermann et al. Opt. Lett. 29:310 (2004)], timing characterization [Singh et al. Laser Photonics Rev. 14:1 (2020)] and quantum information [Kues et al. Nature. 546:622 (2017)]. However, the spectrum of nonlinear optical response was typically determined from the linear optical resonance. In this work, a wavelength-multiplexed nonlinear plasmon-MoS2 hybrid metasurface with suppression phenomenon was proposed, where multiple nonlinear signals could to be simultaneously processed and optionally tuned. A clear physical picture to depict the nonlinear plasmonic bound states in the continuum (BICs) was presented, from the perspective of both classical and quantum approaches. Particularly, beyond the ordinary plasmon-polariton effect, we numerically demonstrated a giant BIC-inspired second-order nonlinear susceptibility 10−5 m/V of MoS2 in the infrared band. The novelty in our study lies in the presence of a quantum oscillator that can be adopted to both suppress and enhance the nonlinear quasi BICs. This selectable nonlinear BIC-based suppression and enhancement effect can optionally block undesired modes, resulting in narrower linewidth as well as smaller quantum decay rates, which is also promising in slow-light-associated technologies.

Unprecedented physical properties make graphene a very promising plasmonic candidate material from the terahertz to mid-infrared frequencies. However, a theoretical model for graphene plasmon cavities has not been fully established. In this work, we analyse the graphene surface plasmon polaritons supported on silicon carbide or metallic cavities. We derive an analytical expression for the dispersion relation of graphene plasmon waves in a multilayer system, providing a useful tool to illustrate the dependence on the cavity's geometric properties. The results show that the analytical description can precisely predict the excitation of cavity graphene plasmon waves. Complete absorption can be achieved under certain parameters, which can be predicted precisely using two Fabry–Perot models. We further show that the interaction of surface plasmon polaritons with surface phonon polaritons can be used to tune the cavity resonances. The tunability of the Fermi energy and the geometric parameters of the cavities make for flexible system design. High enhancement (∼4000) and extraordinary compression (∼λ0/400) of graphene plasmon waves are also realized under certain conditions. These findings make this an ideal setup for molecular sensing, pushing the potential for enhanced, broadly tunable spectroscopy into the mid-infrared, while also offering distinct advantages for integrated optics.

Metasurface can arbitrarily control the polarization states of incident light and has attracted signicant attention. However, the transmission eciency of cross-polarization conversion of transmissive type metallic metasurfaces for polarized beam-splitters reported to date are low, especially the transmission eciency of cross-polarization conversion by single-layer metallic metasurfaces has a low theoretical upper limit of 25%, whose low value severely works against the application requirements. In this work, we propose two beam-splitters based on single-layer anomalous silicon metasurfaces, which can realize high conversion eciency and broad bandwidth wavefront control. A broadband half-wave plate and the high-eciency beam splitting of quarter-wave plate with circularly polarization beam are both achieved. Moreover, with big incident angles, the metasurface still maintains high-eciency performance.

In this work, a high-efficiency and tunable dual-frequency reflective polarization converter composed of graphene metasurface with twisting double L-shaped unit is firstly realized. Numerical results demonstrate that the device can convert a linearly polarized wave to its cross-polarized wave, and meantime it can also convert to a circularly polarized wave. Subsequently, one thickness of 500 nm SiO 2 layer sandwiched by two graphene metasurfaces with similar pattern is stacked on the top of the two-layered structure, a four-frequency efficient reflective polarization converters is realized. Above all, those working frequencies can also be dynamically tuned within a large frequency range by adjusting the Fermi energy of the graphene, without reoptimizing and refabricating the nanostructures, which paves a novel way toward developing a controllable polarization converter for mid-infrared applications.

A plasmonic quarter-wave plate which is based on U-shaped silver nanopatches array in the near-infrared range is designed and presented by us. It utilizes localized surface plasmon resonances with an abrupt phase shift to achieve the desired phase modulation in the transmitted field. The optimized quarter-wave plate can perfectly convert a linearly polarized light to circularly polarized light, whose ellipticity reaches to 1 at the wavelength of 1.55 μm. The bandwidth, in which the ellipticity is larger than 0.83, is 120 nm. This structure offers an enormous potential applications in optical sensor systems, advanced nanophotonic devices and integrated optical circuits.

AOP 2019, Lisbon, Portugal, 31 May - 4 June, 2019. -- http://www.aop2019.org/

Sylwester Gawinkowski opened discussion of the paper by Javier Aizpurua: How many electrons are transferred by one ultrashort pulse? If you are thinking about applications in electronics, then it seems that this number may be too small. Is simply increasing the pulse energy and therefore significantly increasing the number of such emitted electrons possible?

The effects of wheel speeds and high-pressure hydrogen treatment on phase evolution, microstructure, and magnetocaloric properties in La0.5Pr0.5Fe11.4Si1.6 melt-spun ribbons are studied in this work. The results reveal that the increase of wheel speed is beneficial to the formation of cubic NaZn13-type phase and the grain refinement. The optimized wheel speed for microstructural and magnetocaloric properties is 30 m/s. The largest entropy change of 18.1 J/kg⋅K at 190 K under a magnetic field change of 0 T–5 T is obtained in La0.5Pr0.5Fe11.4Si1.6 ribbons melt-spun at 30 m/s. After a high-pressure hydrogen treatment of 50 MPa, the Curie temperature of the ribbons prepared at 30 m/s is adjusted to about 314 K and the large –ΔS M of 17.9 J/kg⋅K under a magnetic field change of 0 T–5 T is achieved at room temperature with almost none hysteresis loss. The small thermal and magnetic hysteresis and the large –ΔS M make the La0.5Pr0.5Fe11.4Si1.6 hydride ribbons appropriate for magnetic refrigerant applications around room temperature.

We present efficient designs of graphene-based thin absorbers, which are capable of near-unity absorption of the incident electromagnetic waves in the terahertz regime. Primarily, a single-frequency absorber is proposed. Subsequently, by simply stacking the double layer graphene metasurface with various geometric dimensions, the dual-frequency absorption and broadband absorption are realized respectively. Results demonstrate that the absorptivity of the single-frequency absorber reaches 99.51% at 2.71 THz when the Fermi energy is fixed at 0.9 eV. The dual-frequency absorber can simultaneously work at two frequencies with its absorptivity being 98.94% for 1.99 THz and 99.1% for 2.69 THz. The bandwidth of absorption rate above 90% expands three times when compared with the former single-frequency absorber. Additionally, it possesses the polarization-insensitive and large angle tolerance properties. More importantly, the absorption frequency can be dynamically controlled by adjusting Fermi energy levels without varying the nanostructure, which exhibits tremendous application values in many fields.

This paper presents a wideband tunable cross-polarization converter based on a graphene metasurface with a hollow-carved “H” array in the mid-infrared regions. The converter consists of three layers: the upper layer of the insulation dielectric layer is a periodic regular hollow-carved “H” array, and the bottom layer is a metal ground plane. Simulation is carried out by applying the frequency domain solver of the CST Microwave Studio software. The numerical simulation results show that the polarization converter transforms linear light into its cross-polarization light. The polarization conversion ratio is over 90% at 2.53 THz within the range of 34.39 to 36.92 THz, whereas the FWHM bandwidth is 3.87 THz within the range of 33.8 to 37.67 THz, about 11% of the central frequency. Thus, the cross-polarization converter can be dynamically tuned over a wide frequency range by altering the Fermi-energy of graphene, without reoptimizing and refabricating nanostructures. The operating frequency band of the proposed structure can also be tuned by changing the size of $w_1$ or $\Lambda$ while keeping the polarization conversion ratios high. Moreover, strong robustness is observed under the oblique incidence. Specifically, the polarization conversion ratios can be maintained at over 90% at angles of incidence of up to $50^\circ$ . Therefore, the proposed device has potential development and application in the manipulation of light polarization in the mid-infrared regions.