Dear Editor,Omicron(B.1.1.529)was designated a variant of concern(VOC)on November 26,2021(Callaway,2021),and its subvariants BA.1,BA.2,and BA.3 emerged and circulated almost simultaneously(Desingu et al.,2022).BA.2 wa...Dear Editor,Omicron(B.1.1.529)was designated a variant of concern(VOC)on November 26,2021(Callaway,2021),and its subvariants BA.1,BA.2,and BA.3 emerged and circulated almost simultaneously(Desingu et al.,2022).BA.2 was more efficient in transmission and quickly overtook BA.1 to become the variant most frequently detected worldwide(Yamasoba et al.,2022a).Compared to the prototype SARS-CoV-2 spike protein(S),the BA.1 and BA.2 spike proteins harbor more than 30 mutations,of which 21 are identical between the two subvariants,while the BA.3 spike differs from BA.1 and BA.2 by 3 mutations in the receptor binding domain(RBD)(Fig.1A).More recently,BA.4 and BA.5(hereafter BA.4/5)emerged,sharing the same spike sequence and containing four additional mutations,Del69–70,L452R,F486V,and R493Q,compared with BA.2.BA.4/5 were detected first in South Africa and evolved independently of BA.2;they have spread widely and replaced BA.2 as the predominant VOC(Gruell et al.,2022b;Tegally et al.,2022).In addition,BA.2.75,derived from the BA.2 subvariant,harbors nine additional mutations in the spike protein compared with BA.2(Fig.1A).BA.4/5 and BA.2.75 have led to the continuous emergence of novel Omicron subvariants,including BF.7 and BQ.1.These new subvariants may be driving waves of pandemics.展开更多
In this paper,we proposed a novel ultra・flat broadband microwave frequency comb(MFC)generation based on optical frequency comb(OFC)with a multiplequantum-well electroabsorption modulator(MQW-EAM)in critical state.The ...In this paper,we proposed a novel ultra・flat broadband microwave frequency comb(MFC)generation based on optical frequency comb(OFC)with a multiplequantum-well electroabsorption modulator(MQW-EAM)in critical state.The scheme is simple and easy to adjust.The performance of the MFC generation scheme is investigated using software Optisystem.The results show that the comb spacing of MFC can be adjusted from 5 to 20 GHz by changing RF signafs frequency and the MFC is almost independent on the linewidth of the tunable laser diode.The performance of the MFC can be improved by reasonably increasing the voltage of the RF,the smallsignal gain of the Erbium-doped fiber amplifier(EDFA)and the responsivity of the photodetector.The MFC generated by this scheme has 300 GHz effective bandwidth with 15 comb lines,whose power variation is 0.02 dB,when the components9 parameters in the Optisystem are set as follows:the power of tunable laser diode(TLD)is 0 dBm,the wavelength is 1552.52 nm,and linewidth is 1 MHz;RF signaPs frequency is 20 GHz and the voltage is 10 V;the reverse bias voltage of MQW-EAM is 6.92 V;the small-signal gain of the EDFA is 40 dB;the responsivity of the photodetector(PD)is 1 A/W.展开更多
基金supported by the National Natural Science Foundation of China(82061138020,32270996,82102365)The Science and Technology Innovation Program of Hunan Province of China(2022RC3079)+5 种基金the Educational Commission of Hunan Province of China(21A0529)the Natural Science Foundation of Hunan Province of China(2021JJ40006,2022JJ30095)the Clinical Medical Innovation Technology Guide Project of Hunan Province(2021SK50304,2021SK50306 and 2021SK50312)“SC1-PHE-CORONAVIRUS-2020:Advancing knowledge for the clinical and public health response to the 2019-nCoV epidemic”from the European Commission(CORONADX,no.101003562)(to Y-P.L.)approved by the Institutional Ethical Review Board of The Central Hospital of Shaoyang,Hunan Province,China(V.1.0,20200301)The First People's Hospital of Chenzhou,Hunan Province,China(V.3.0,2021001).
文摘Dear Editor,Omicron(B.1.1.529)was designated a variant of concern(VOC)on November 26,2021(Callaway,2021),and its subvariants BA.1,BA.2,and BA.3 emerged and circulated almost simultaneously(Desingu et al.,2022).BA.2 was more efficient in transmission and quickly overtook BA.1 to become the variant most frequently detected worldwide(Yamasoba et al.,2022a).Compared to the prototype SARS-CoV-2 spike protein(S),the BA.1 and BA.2 spike proteins harbor more than 30 mutations,of which 21 are identical between the two subvariants,while the BA.3 spike differs from BA.1 and BA.2 by 3 mutations in the receptor binding domain(RBD)(Fig.1A).More recently,BA.4 and BA.5(hereafter BA.4/5)emerged,sharing the same spike sequence and containing four additional mutations,Del69–70,L452R,F486V,and R493Q,compared with BA.2.BA.4/5 were detected first in South Africa and evolved independently of BA.2;they have spread widely and replaced BA.2 as the predominant VOC(Gruell et al.,2022b;Tegally et al.,2022).In addition,BA.2.75,derived from the BA.2 subvariant,harbors nine additional mutations in the spike protein compared with BA.2(Fig.1A).BA.4/5 and BA.2.75 have led to the continuous emergence of novel Omicron subvariants,including BF.7 and BQ.1.These new subvariants may be driving waves of pandemics.
基金Related studies were supported by the National Natural Science Foundation of China(Grant No.61275067).
文摘In this paper,we proposed a novel ultra・flat broadband microwave frequency comb(MFC)generation based on optical frequency comb(OFC)with a multiplequantum-well electroabsorption modulator(MQW-EAM)in critical state.The scheme is simple and easy to adjust.The performance of the MFC generation scheme is investigated using software Optisystem.The results show that the comb spacing of MFC can be adjusted from 5 to 20 GHz by changing RF signafs frequency and the MFC is almost independent on the linewidth of the tunable laser diode.The performance of the MFC can be improved by reasonably increasing the voltage of the RF,the smallsignal gain of the Erbium-doped fiber amplifier(EDFA)and the responsivity of the photodetector.The MFC generated by this scheme has 300 GHz effective bandwidth with 15 comb lines,whose power variation is 0.02 dB,when the components9 parameters in the Optisystem are set as follows:the power of tunable laser diode(TLD)is 0 dBm,the wavelength is 1552.52 nm,and linewidth is 1 MHz;RF signaPs frequency is 20 GHz and the voltage is 10 V;the reverse bias voltage of MQW-EAM is 6.92 V;the small-signal gain of the EDFA is 40 dB;the responsivity of the photodetector(PD)is 1 A/W.
