Microstructural,magnetic and dielectric performance of rare earth ion(Sm^(3+))-doped MgCd ferrites

The combined effects of Sm^(3+)substitution together with the addition of 3 wt%Bi_(2)O_(3)endow Mg Cd ferrites with excellent magnetic permeability and dielectric permittivity.Various concentrations of Sm^(3+)(x=0,0.03,0.06,0.09,0.12and 0.15)were employed to modify the permeability(μ)and permittivity(ε)of the Mg Cd ferrites.X-ray diffraction,scanning electron microscopy(SEM),vibrating sample magnetometry and vector network analysis techniques were used to characterize the samples.The measurement results reveal that the ferrites processed a saturation magnetization of up to 36.8 emu/g and coercivity of up to 29.2 Oe via the conventional solid-state reaction method.The surface morphology SEM confirms that with increasing Sm^(3+)concentration,the grain shape changes from a polygon to a circle.Moreover,the dielectric permittivity can reach a value of 23.The excellent properties obtained in Sm^(3+)-substituted Mg ferrites suggest that they could be promising candidates for modern high-frequency antenna substrates or multilayer devices.

Janus vortex beams realized via liquid crystal Pancharatnam–Berry phase elements

Emerging as a family of waves,Janus waves are known to have“real”and“virtual”components under inversion of the propagation direction.Although tremendous interest has been evoked in vortex beams featuring spiral wavefronts,little research has been devoted to the vortex beam embedded Janus waves,i.e.,Janus vortex beams.We propose a liquid crystal(LC)Pancharatnam–Berry(PB)phase element to demonstrate the realization of the Janus vortex beams and the modulation of the associated orbit angular momentum(OAM)and spin angular momentum(SAM).The generated Janus vortex beams show opposite OAM and SAM states at two distinct foci,revealing a spin-orbit interaction during propagation enabled by the LC PB phase element,which may play special roles in applications such as optical encryption and decryption.Other merits like reconfigurability and flexible switching between Janus vortex beams and autofocusing or autodefocusing vortex beams additionally increase the degree of freedom of manipulating vortex beams.This work provides a platform for tailoring complex structured light and may enrich the applications of vortex beams in classical and quantum optics.

Constructing arbitrary self-similar Bessel-like beams via transverse-longitudinal mapping

Based on the transverse-longitudinal mapping of Bessel beams,we propose a simple method to construct a self-similar Bessel-like beam whose transverse profile maintains a stretched form during propagation.Specifically,the propagatingvariant width of this beam can be flexibly predesigned.We experimentally demonstrate three types of self-similar Bessellike beams whose width variations are linear,piecewise,and period functions of propagation distance,respectively.The experimental results match well with the theoretical predictions.We also demonstrate that our approach enables the generation of self-similar higher-order vortex Bessel-like beams.

Visible-to-near-infrared spectrum reconstruction with dielectric metasurfaces

The miniaturization of spectrometers has received much attention in recent years.The rapid development of metasurfaces has provided a new avenue for creating more compact and lightweight spectrometers.However,most metasurface-based spectrometers operate in the visible light region,with much less research on near-infrared wavelengths.This is possibly caused by the lack of effective metasurface filters for the near-infrared light.We design and fabricate a polarizationinsensitive amorphous silicon metasurface that exhibits unique transmission spectra in parts of the visible and nearinfrared wavelengths.By passing the light to be measured through a metasurface filter array and measuring the transmitted power,we achieve the precise reconstruction of unknown spectra in the visible and near-infrared range(450-950 nm)using an algorithm matched to the filter model.Our approach is a step towards miniaturized spectrometers within the visible-to-near-infrared range based on metasurface filter arrays.

2021年温州市中小学生近视流行现状及相关影响因素

目的:了解温州市中小学生近视现状及近视发生的影响因素,为中小学生近视防治提供科学依据。方法:横断面调查研究。于2021年10月采用分层整群随机抽样方法,选取温州市瓯海区、瑞安市、泰顺县17所学校的中小学生6500名开展视力和屈光度检查,并进行视力和屈光度的影响因素问卷调查分析。采用χ^(2)检验对近视相关因素进行单因素分析;采用Logistic回归进行多因素分析。结果:最终纳入6342名学生进行调查研究。温州市中小学生近视率为53.67%,其中小学生近视率为34.24%,初中生近视率为70.09%,普高生近视率为87.66%,职高生近视率为75.10%。年级、性别、课间休息活动场所、在过去1周平均每天放学后做作业/读书写字时长(h)、家长限制看电视及玩电脑或电子游戏时间、读写时胸口离桌子边沿超过一拳间、阳光直射下看书、关灯看电子屏幕、躺着或趴着看书或电子屏幕、父母是否近视等影响因素下的近视率比较,差异均有统计学意义(χ^(2)=16.22~1224.70,P<0.05)。Logistic回归分析显示,年级(初中OR=7.80,95%CI:5.45~11.17,P<0.001;普高OR=2.85,95%CI:1.77~4.57,P<0.001;职高OR=1.32,95%CI:1.14~1.53,P<0.001),女生(OR=1.32,95%CI:1.14~1.53,P<0.001),父母是否近视(父母都近视OR=1.81,95%CI:1.32~2.48,P<0.001),视力检查次数(3次OR=2.27,95%CI:1.60~3.23,P<0.001;4次OR=2.17,95%CI:1.47~3.22,P<0.001)均为中小学生近视发生的影响因素。结论:温州市普高生近视率最高,女生近视率高于男生。另外,父母是否近视和视力检查次数也是近视发生的重要影响因素。

CircRNA_Maml2 promotes the proliferation and migration of intestinal epithelial cells after severe burns by regulating the miR-93-3p/FZD7/Wnt/β-catenin pathway

Background:Circular RNA(circRNA)plays key regulatory roles in the development of many diseases.However the biological functions and potential molecular mechanisms of circRNA in the injury and repair of intestinal mucosa in mice after severe burns are yet to be elucidated.Methods:Cell counting kit-8(CCK-8),5-ethynyl-2-deoxyuridine(EdU),wound healing and transwell assays were used to detect cell proliferation and migration ability.Real-time quantitative PCR was used to identify the expression of circRNA,microRNA and messenger RNA.Nuclear and cytoplas-mic separation experiments were employed to perceive the location of circRNA_Maml2.Finally,in vitro and in vivo experiments were conducted to study the repairing effect of circRNA_Maml2 on the intestinal mucosa of mice after severe burns.Results:When compared with the control group,the expression of circRNA_Maml2 was sig-nificantly reduced in the severe burn group.Furthermore,overexpression of circRNA_Maml2 promoted the proliferation and migration of CT26.wt cells in vivo and the repair of damaged intestinal mucosa in vitro.CircRNA_Maml2 acted as a sponge adsorption molecule for miR-93-3p to enhance the expression of frizzled class receptor 7 and activate the downstream Wnt/β-catenin pathway,thereby promoting the repair of the intestinal mucosa.Conclusions:Our findings demonstrate that circRNA_Maml2 regulates the miR-93-3p/FZD7/Wnt/β-catenin pathway and promotes the repair of damaged intestinal mucosa.Hence,circRNA_Maml2 is a potential therapeutic target to promote intestinal mucosal repair.

High-resolution grayscale image hidden in a laser beam

Images perceived by human eyes or recorded by cameras are usually optical patterns with spatially varying intensity or color profiles.In addition to the intensity and color,the information of an image can be encoded in a spatially varying distribution of phase or polarization state.Interestingly,such images might not be able to be directly viewed by human eyes or cameras because they may exhibit highly uniform intensity profiles.Here,we propose and experimentally demonstrate an approach to hide a high-resolution grayscale image in a square laser beam with a size of less than half a millimeter.An image with a pixel size of 300×300 nm is encoded into the spatially variant polarization states of the laser beam,which can be revealed after passing through a linear polarizer.This unique technology for hiding grayscale images and polarization manipulation provides new opportunities for various applications,including encryption,imaging,optical communications,quantum science and fundamental physics.

Light field on a chip: metasurface-based multicolor holograms

Multicolor holography can faithfully record the color,depth,parallax,and other properties of scenes and have thus found numerous applications,for example,in optical document security,nonvolatile data storage,and virtual or augmented reality systems.Nanophotonic metasurfaces present multiple degrees of freedom to manipulate the properties of optical fields at visible wavelengths.These in turn provide opportunities for metasurface-based multicolor holography.We describe recent developments in multicolor metasurface holograms.These are categorized based on their color-separating mechanisms rather than their structural properties,such as whether they are plasmonic or dielectric.We hope this review will provide readers with new insights and thus help extend applications of metasurface-based multicolor holography to other fields.

Metasurface for oscillatory spin splitting along the optical path

Spin splitting of light originates from the interplay between the polarization and spatial degrees of freedom as a fundamental constituent of the emerging spin photonics,providing a prominent pathway for manipulating photon spin and developing exceptional photonic devices.However,previously relevant devices were mainly designed for routing monotonous spin splitting of light.Here,we realize an oscillatory spin splitting of light via metasurface with two channel Pancharatnam–Berry phases.For the incidence of a linearly polarized light,the concomitant phases arising from opposite spin states transition within pathways of the metasurface induce lateral spin splitting of light with alternately changed transport direction during beam guiding.We demonstrate the invariance of this phenomenon with an analogous gauge transformation.This work provides a new insight on steering the photon spin and is expected to explore a novel guiding mechanism of relativistic spinning particles,as well as applications of optical trapping and chirality sorting.