Asymmetric electric field distribution enhanced hierarchical metamaterials for radar-infrared compatible camouflage

Metamaterials are widely used in electromagnetic radiation and camouflage for their flexible wavefront manipulation and polarization over a broad spectrum ranging from microwaves to optics.However,multispectral compatible camouflage faces significant challenges due to tremendous scale differences of unit cells and desired radiative properties in various spectral regimes.This study assembles a micron-scale infrared emitter,a millimeter-scale microwave absorber,and a metal reflector to propose a hierarchical metamaterial that reduces microwave scattering and reflects low-infrared waves.As a proof of concept,laser etching micro-manufactures an upper infrared shielding layer with a periodic metal pattern.At the same time,bottom square frustum metastructure composites are fabricated and optimized based on genetic algorithms.Under the normal incidence transverse electromagnetic wave with a 90°azimuth angle,the hierarchical strategy and infrared unit create an asymmetric electric field distribution of local near-field coupling,which is conducive to generating additional resonance for broadening the absorption bandwidth.Experiments verify the multispectral camouflage,which shows a high absorption efficiency of more than 90%,ranging from 3.6 to 6.2 and from 8.4 to 18 GHz with a total thickness of 4.05 mm(0.049λmax).Due to the non-reflection of surrounding thermal signals in the infrared 2-22μm region,low-infrared emissivity(0.29)metamaterials can adapt to various thermal backgrounds.This methodology can provide a novel route for fabricating multispectral camouflage devices.

An inactivated recombinant rabies virus chimerically expressed RBD induces humoral and cellular immunity against SARS-CoV-2 and RABV

Many studies suggest that severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)can infect various animals and transmit among animals,and even to humans,posing a threat to humans and animals.There is an urgent need to develop inexpensive and efficient animal vaccines to prevent and control coronavirus disease 2019(COVID-19)in animals.Rabies virus(RABV)is another important zoonotic pathogen that infects almost all warmblooded animals and poses a great public health threat.The present study constructed two recombinant chimeric viruses expressing the S1 and RBD proteins of the SARS-CoV-2 Wuhan01 strain based on a reverse genetic system of the RABV SRV9 strain and evaluated their immunogenicity in mice,cats and dogs.The results showed that both inactivated recombinant viruses induced durable neutralizing antibodies against SARS-CoV-2 and RABV and a strong cellular immune response in mice.Notably,inactivated SRV-nCoV-RBD induced earlier antibody production than SRV-nCoV-S1,which was maintained at high levels for longer periods.Inactivated SRV-nCoV-RBD induced neutralizing antibodies against both SARS-CoV-2 and RABV in cats and dogs,with a relatively broadspectrum cross-neutralization capability against the SARS-CoV-2 pseudoviruses including Alpha,Beta,Gamma,Delta,and Omicron,showing potential to be used as a safe bivalent vaccine candidate against COVID-19 and rabies in animals.

Incorporation of Escherichia coli heat-labile enterotoxin B subunit into rabies virus particles enhances its immunogenicity in mice and dogs

Although inactivated vaccines against rabies have the advantage of high safety,effective protection against rabies virus(RABV)infection often requires multiple,high-dose immunization.Incorporating a molecular adjuvant into the viral particles has been found to be a useful strategy to promote the immune effectiveness of inactivated vaccines.In this study,we constructed a recombinant virus,rCVS11-LTB,which chimerically expresses a molecular adjuvant heat-labile enterotoxin B subunit(LTB)protein on the surface of the RABV particles.Immunogenicity in vivo was found to be promoted by rCVS11-LTB through the activation of dendritic cells(DCs).Our results demonstrated that inactivated rCVS11-LTB was able to induce higher levels of virusneutralizing antibodies(VNAs)in both mice and dogs than the parent virus rCVS11,to enhance the cellular immune response and T cell immune memory in mice,and was also able to provide 100%protection in mice from lethal doses of rabies virus,indicating its potential as a safe and effective inactivated rabies vaccine candidate.