DEAR EDITOR,The COVID-19 pandemic caused by SARS-CoV-2 continues to pose a tremendous threat to human society. SARS-CoV-2is airborne and transmits primarily through social contact;however, whether cold chain-related t...DEAR EDITOR,The COVID-19 pandemic caused by SARS-CoV-2 continues to pose a tremendous threat to human society. SARS-CoV-2is airborne and transmits primarily through social contact;however, whether cold chain-related transmission has occurred remains highly debated(Han & Liu, 2022;Lewis,2021;Ma et al., 2021;Mallapaty et al., 2021;Pang et al.,2020;Wu et al., 2021). Here, we present a novel method and identify two transmission routes based on lineage-specific reductions in the SARS-CoV-2 evolutionary rate.展开更多
Temperature is one of the most important environmental factors that affect organisms,especially ectotherms,due to its effects on protein stability.Understanding the general rules that govern thermostability changes in...Temperature is one of the most important environmental factors that affect organisms,especially ectotherms,due to its effects on protein stability.Understanding the general rules that govern thermostability changes in proteins to adapt high-temperature environments is crucial.Here,we report the amino acid substitutions of phosphoglucose isomerase(PGI)related to thermostability in the Glanville fritillary butterfly(Melitaea cinxia,Lepidoptera:Nymphalidae).The PGI encoded by the most common allele in M.cinxia in the Chinese population(G3-PGI),which is more thermal tolerant,is more stable under heat stress than that in the Finnish population(D1-PGI).There are 5 amino acid substitutions between G3-PGI and D1-PGI.Site-directed mutagenesis revealed that the combination of amino acid substitutions of H35Q,M49T,and I64V may increase PGI thermostability.These substitutions alter the 3D structure to increase the interaction between 2 monomers of PGI.Through molecular dynamics simulations,it was found that the amino acid at site 421 is more stable in G3-PGI,confining the motion of theα-helix 420-441 and stabilizing the interaction between 2 PGI monomers.The strategy for hightemperature adaptation through these 3 amino acid substitutions is also adopted by other butterfly species(Boloria eunomia,Aglais urticae,Colias erate,and Polycaena lua)concurrent with M.cinxia in the Tianshan Mountains of China,i.e.,convergent evolution in butterflies.展开更多
This paper presents a method to realize compact broadband low-RCS ReflectArray(RA)antenna based on a Frequency Selective Surface(FSS)absorber and a reflective metasurface.Such an FSS absorber consists of a resistance-...This paper presents a method to realize compact broadband low-RCS ReflectArray(RA)antenna based on a Frequency Selective Surface(FSS)absorber and a reflective metasurface.Such an FSS absorber consists of a resistance-loaded lossy layer and an FSS layer,which is utilized to reach an absorption-transmission response.The bottom reflective metasurface works as a phase array,reshaping the quasi-sphere wave from the feeding antenna into the quasi-plane wave.As a demonstration,the low-RCS RA antenna is simulated,fabricated,and measured.The simulated and measured results show that the developed low-RCS RA antenna has an aperture efficiency of 42.7%and a gain of 25.4 dBi in the X band.In the meantime,it simultaneously reaches the 10 dB RCS reduction for the orthogonal polarizations at the S and C bands,corresponding to a fractal bandwidth of 120%.Specifically,the adopted patch-feeding antenna makes the RA antenna more compact than the horn-feed conventional ones.Furthermore,the proposed RA antenna uses a few layers of substrates,making it lower in cost and easier for fabrication.The proposed design may have potential application in integrated stealth communication systems.展开更多
基金supported by the National Key Research and Development Project (2020YFC0847000,2021YFC0863300, 2020YFC0845900)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDPB17)+1 种基金the National Natural Science Foundation of China (31100273, 91731304,31172073)Shandong Academician Workstation Program#170401 (to G.P.Z.)。
文摘DEAR EDITOR,The COVID-19 pandemic caused by SARS-CoV-2 continues to pose a tremendous threat to human society. SARS-CoV-2is airborne and transmits primarily through social contact;however, whether cold chain-related transmission has occurred remains highly debated(Han & Liu, 2022;Lewis,2021;Ma et al., 2021;Mallapaty et al., 2021;Pang et al.,2020;Wu et al., 2021). Here, we present a novel method and identify two transmission routes based on lineage-specific reductions in the SARS-CoV-2 evolutionary rate.
基金the Grant 31772446 from the National Natural Science Foundation of China.
文摘Temperature is one of the most important environmental factors that affect organisms,especially ectotherms,due to its effects on protein stability.Understanding the general rules that govern thermostability changes in proteins to adapt high-temperature environments is crucial.Here,we report the amino acid substitutions of phosphoglucose isomerase(PGI)related to thermostability in the Glanville fritillary butterfly(Melitaea cinxia,Lepidoptera:Nymphalidae).The PGI encoded by the most common allele in M.cinxia in the Chinese population(G3-PGI),which is more thermal tolerant,is more stable under heat stress than that in the Finnish population(D1-PGI).There are 5 amino acid substitutions between G3-PGI and D1-PGI.Site-directed mutagenesis revealed that the combination of amino acid substitutions of H35Q,M49T,and I64V may increase PGI thermostability.These substitutions alter the 3D structure to increase the interaction between 2 monomers of PGI.Through molecular dynamics simulations,it was found that the amino acid at site 421 is more stable in G3-PGI,confining the motion of theα-helix 420-441 and stabilizing the interaction between 2 PGI monomers.The strategy for hightemperature adaptation through these 3 amino acid substitutions is also adopted by other butterfly species(Boloria eunomia,Aglais urticae,Colias erate,and Polycaena lua)concurrent with M.cinxia in the Tianshan Mountains of China,i.e.,convergent evolution in butterflies.
基金supported by the China Postdoctoral Science Foundation(No.2021M693712)the National Natural Science Foundation of China(Nos.62205038 and 62031006)the Chongqing Postdoctoral Science Foundation(Special Funding),China(No.XmT20200020).
文摘This paper presents a method to realize compact broadband low-RCS ReflectArray(RA)antenna based on a Frequency Selective Surface(FSS)absorber and a reflective metasurface.Such an FSS absorber consists of a resistance-loaded lossy layer and an FSS layer,which is utilized to reach an absorption-transmission response.The bottom reflective metasurface works as a phase array,reshaping the quasi-sphere wave from the feeding antenna into the quasi-plane wave.As a demonstration,the low-RCS RA antenna is simulated,fabricated,and measured.The simulated and measured results show that the developed low-RCS RA antenna has an aperture efficiency of 42.7%and a gain of 25.4 dBi in the X band.In the meantime,it simultaneously reaches the 10 dB RCS reduction for the orthogonal polarizations at the S and C bands,corresponding to a fractal bandwidth of 120%.Specifically,the adopted patch-feeding antenna makes the RA antenna more compact than the horn-feed conventional ones.Furthermore,the proposed RA antenna uses a few layers of substrates,making it lower in cost and easier for fabrication.The proposed design may have potential application in integrated stealth communication systems.
