Photonic thermal switch via metamaterials made of vanadium dioxide-coated nanoparticles.

In this work, a photonic thermal switch is proposed based on the phase-change material vanadium dioxide (VO) within the framework of near-field radiative heat transfer (NFRHT). The switch consists of two metamaterials filled with core-shell nanoparticles, with the shell made of VO. Compared to traditional VO slabs, the proposed switch exhibits a more than two times increase in the switching ratio, reaching as high as 90.

High-efficiency broadband achromatic metalenses for visible full-stokes polarization imaging.

Polarization-imaging technology has important applications in target detection, communication, biomedicine, and other fields. A polarization imaging system based on metalenses, which provides new possibilities for the realization of highly integrated full-Stokes polarization imaging systems, can solve the problems of traditional polarization imaging systems, such as complex structures, large volumes, and the inability to simultaneously obtain linear and circular polarization states. However, currently designed metalens arrays that can achieve real-time full-Stokes polarization imaging can generally only be used for monochromatic detection, which significantly limits the amount of measured information of the object.

Performance improvement of three-body radiative diodes driven by graphene surface plasmon polaritons.

As an analogue to an electrical diode, a radiative thermal diode allows radiation to transfer more efficiently in one direction than in the opposite direction by operating in a contactless mode. In this study, we demonstrated that within the framework of three-body photon thermal tunneling, the rectification performance of a three-body radiative diode can be greatly improved by bringing graphene into the system. The system is composed of three parallel slabs, with the hot and cold terminals of the diode coated with graphene films and the intermediate body made of vanadium dioxide (VO).

Photoinduced Radical Sulfinylation of C(sp)-H Bonds with Sulfinyl Sulfones.

A direct C(sp)-H sulfinylation reaction of alkanes with sulfinyl sulfones via decatungstate photocatalysis is reported. The sulfinyl sulfones generated in situ from sulfinates in the presence of an acylating reagent were able to trap the alkyl radicals that were produced via the photoinduced direct hydrogen atom transfer of alkanes, leading to a range of sulfoxides. This radical sulfinylation process provides an efficient and concise method for the synthesis of sulfoxides from abundant alkanes under mild conditions.

Control of Maize Sheath Blight and Elicit Induced Systemic Resistance Using Strain SF05.

Maize ( L.) is an important crop in the world and maize sheath blight damages the yield and quality greatly. In this study, an antagonist strain, which exhibited antagonism against pathogenic fungi of maize and controlled maize banded leaf sheath blight in the field, was effectively isolated and named strain SF05.

Lattice Boltzmann modeling of two-phase electrohydrodynamic flows under unipolar charge injection.

In this work, a two-dimensional droplet confined between two parallel electrodes under the combined effects of a nonuniform electric field and unipolar charge injection is numerically investigated using the lattice Boltzmann method (LBM). Under the non-Ohmic regime, the interfacial tension and electric forces at the droplet surface cooperate with the volumetric Coulomb force, leading to complex deformation and motion of the droplet while at the same time inducing a bulk electroconvective flow. After we validate the model by comparing with analytical solutions at the hydrostatic state, we perform a quantitative analysis on the droplet deformation factor D and bulk flow stability criteria T_{c} under different parameters, including the electric capillary number Ca, the electric Rayleigh number T, the permittivity ratio ɛ_{r}, and the mobility ratio K_{r}.

Conditions for establishing the "generalized Snell's law of refraction" in all-dielectric metasurfaces: theoretical bases for design of high-efficiency beam deflection metasurfaces.

The generalized Snell's law dictates that introducing a phase gradient at the interface of two media can shape incident light and achieve anomalous reflection or refraction. However, when the introduced phase gradient is realized via the scattering of nanoparticles in the metasurfaces, this law needs to be modified; certain conditions need to be met when the law is established. We present the conditions for establishing the "generalized Snell's law of refraction" in all-dielectric metasurfaces under the incidence of different polarized light.

High-Accuracy Correction of a Microlens Array for Plenoptic Imaging Sensors.

Microlens array (MLA) errors in plenoptic cameras can cause the confusion or mismatching of 4D spatio-angular information in the image space, significantly affecting the accuracy and efficiency of target reconstruction. In this paper, we present a high-accuracy correction method for light fields distorted by MLA errors. Subpixel feature points are extracted from the microlens subimages of a raw image to obtain correction matrices and perform registration of the corresponding subimages at a subpixel level.

Mechanism of polaritons coupling from perspective of equivalent MLC circuits model in slit arrays.

Magnetic polariton is a significant mode in tailoring thermal radiative properties with micro/nanostructures metamaterials and can be explained by equivalent inductor-capacitor circuit model. However, the equivalent inductor-capacitor circuit model is out of operation when the magnetic polariton resonance frequency is close to the surface plasmon polariton excitation frequency and cases of oblique incidence. In this work, we present a mutual inductor-inductor-capacitor circuit model to describe magnetic polariton resonance conditions.

Efficient lattice Boltzmann method for electrohydrodynamic solid-liquid phase change.

Melting in the presence of electrohydrodynamic (EHD) flow driven by the Coulomb force in dielectric phase change material is numerically studied. A model is developed for the EHD flow in the solid-liquid phase change process. The fully coupled equations including mechanical equations, electrical equations, energy equations, and the continuity equations in the solid-liquid interface are solved using a unified lattice Boltzmann model (LBM).

Assessment of column aerosol optical properties using ground-based sun-photometer at urban Harbin, Northeast China.

Aerosol plays a key role in determining radiative balance, regional climate and human health. Severe air pollution over Northeast China in recent years urges more comprehensive studies to figure out the adverse effects caused by excessive aerosols. In this study, column aerosol measurements over urban Harbin, a metropolis located at the highest latitude in Northeast China, during May 2016 to March 2017 were conducted using a CIMEL sun-photometer to analyze local aerosol properties and its variation from different aspects.

Flame temperature estimation from light field image processing.

We propose a novel flame temperature estimation method based on a flame light field sectioned imaging model of complex temperature distribution in different media. The proposed method relies on multi-pixel reconstruction to improve the resolution of sub-aperture images. In addition, the wavelet transform denoises the flame refocused image, and then the Lucy-Richardson algorithm deconvolves the image.

Tunable absorption as multi-wavelength at infrared on graphene/hBN/Al grating structure.

This work designs a graphene/hBN/Al grating anisotropic hybrid structure. Formed by strong coupling between plasmonic Magnetic polaritons (MPs) in the metal grating and phonon-plasmon polaritons, hybrid hyperbolic phonon-plasmon polaritons in the graphene/hBN film have been excited, resulting in three sharp, high absorption peaks, which are 0.75, 0.

Multiscale solutions of radiative heat transfer by the discrete unified gas kinetic scheme.

The radiative transfer equation (RTE) has two asymptotic regimes characterized by the optical thickness, namely, optically thin and optically thick regimes. In the optically thin regime, a ballistic or kinetic transport is dominant. In the optically thick regime, energy transport is totally dominated by multiple collisions between photons; that is, the photons propagate by means of diffusion.

First-principles investigations of manganese oxide (MnO ) complex-sandwiched bilayer graphene systems.

In this paper, we calculate the structural, electronic, magnetic and optical parameters of MnO ( = 0-4), cluster-sandwiched bilayer graphene (Gr) systems, utilizing first-principles calculations with van der Waals corrections implemented with density functional theory (DFT). Charge transfer is observed from the graphene layers to the MnO clusters, thus producing a hole doping phenomenon in the graphene layers. The MnO clusters' electronegative nature greatly modifies the electronic structure of bilayer graphene.

Rectification of Images Distorted by Microlens Array Errors in Plenoptic Cameras.

A plenoptic cameras is a sensor that records the 4D light-field distribution of target scenes. The surface errors of a microlens array (MLA) can cause the degradation and distortion of the raw image captured by a plenoptic camera, resulting in the confusion or loss of light-field information. To address this issue, we propose a method for the local rectification of distorted images using white light-field images.

Responses transition in a monolayer Al-AlO nanoparticle-crystal due to oxidation.

Nanoparticle is a promising candidate for large scale fabrication of metamaterial. However, optical responses for metamaterial made of abound metal like Al can be thoroughly changed due to oxidization. Especially for nanoparticle whose aspect ratio is extremely high, oxidation usually occurs.

Graphene plasmonics for surface enhancement near-infrared absorptivity.

Monolayer graphene has poor absorption in the near-infrared region. Its layer is only as thick as a single atom so it cannot have a high absorptivity. In this paper, in order to form a hybrid system, the absorption characteristics of monolayer graphene covering a metal/dielectric/metal substrate has been theoretically analyzed.

Transient/time-dependent radiative transfer in a two-dimensional scattering medium considering the polarization effect.

Transient/time-dependent radiative transfer in a two-dimensional scattering medium is numerically solved by the discontinuous finite element method (DFEM). The time-dependent term of the transient vector radiative transfer equation is discretized by the second-order central difference scheme and the space domain is discretized into non-overlapping quadrilateral elements by using the discontinuous finite element approach. The accuracy of the transient DFEM model for the radiative transfer equation considering the polarization effect is verified by comparing the time-resolved Stokes vector component distributions against the steady solutions for a polarized radiative transfer problem in a two-dimensional rectangular enclosure filled with a scattering medium.

Nanoparticle-crystal towards an absorbing meta-coating.

In this paper, a double layer nanoparticle-crystal has been proposed, which shown incident and polarization angle, substrate independences for spectral absorptivity. Such phenomenon originates from the near-field light redistribution and excitation of internal collective oscillating. This kind of nanoparticle-crystal can be made of various types of metal with similar optical responses.

Multi-focused microlens array optimization and light field imaging study based on Monte Carlo method.

Plenoptic cameras are used for capturing flames in studies of high-temperature phenomena. However, simulations of plenoptic camera models can be used prior to the experiment improve experimental efficiency and reduce cost. In this work, microlens arrays, which are based on the established light field camera model, are optimized into a hexagonal structure with three types of microlenses.

Transient polarized radiative transfer analysis in a scattering medium by a discontinuous finite element method.

Transient (time-dependent) polarized radiative transfer in a scattering medium exposed to an external collimated beam illumination is conducted based on the time-dependent polarized radiative transfer theory. The transient term, which persists the nanosecond order time and cannot be ignored for the time-dependent radiative transfer problems induced by a short-pulsed beam, is considered as well as the polarization effect of the radiation. A discontinuous finite element method (DFEM) is developed for the transient vector radiative transfer problem and the derivation of the discrete form of the governing equation is presented.