Co-infections of SARS-CoV-2 with multiple common respiratory pathogens in infected patients

Dear Editor,In late December 2019,an outbreak of severe pneumonia caused by an unknown etiological agent was initially reported in Wuhan,China,and then quickly spread throughout China and even abroad(Zhu et al.,2020).Swift control measures and etiological investigations were conducted by the Chinese government,physicians and researchers,and by using high throughput sequencing and virological testing,the mysterious pneumonia pathogen was shown to be a novel coronavirus(SARS-CoV-2)capable of person-to-person transmission(Zhu et al.,2020).Coronaviruses are a group of non-segmented,enveloped and positive-sense RNA viruses that belong to the subfamily of Coronavirinae in the family of Coronavirdiae and order of Nidovirales.

Effect of Cu content on microstructure and mechanical properties of in-situ β phases reinforced Ti/Zr-based bulk metallic glass matrix composite by selective laser melting(SLM)

In this study,non-toxic in-situβphases of reinforced Ti/Zr-based bulk metallic glass matrix composites(BMGCs)of(Ti_(0.65)Zr_(0.35))100-xCux(x=5,10,15 at.%)are fabricated via selective laser melting.The effect of Cu content on phase formation,microstructure,and mechanical properties is investigated.The average volume fraction and width of theβphase decreases with increasing Cu content,while a more amorphous phase and the(Ti,Zr)_(2)Cu phase forms.In the center zone of the molten pool,theβphase grows in the direction of the temperature gradient,and the amorphous phase distributes among theβphases.This occurs using:sphere morphology(for x=5),a more continuous elongated sphere and network morphology(for x=10),and network morphology(for x=15),respectively.In the edge zone of the molten pool,due to the smaller cooling rate and the existence of a partially molten zone,theβphase becomes coarser,and an amorphous phase forms for more continuous networks.Furthermore,the hardness improves significantly with increasing Cu content.No crack is found for x=5.Although the average volume fraction of theβphase for x=5 is about 90%,the compression yield strength is 1386±64 MPa,reaching to an average level of conventionally fabricated counterparts,due to finer microstructure,and twinning and martensitic transformation of theβphase.

Construction of direct Z-scheme BPQDs-modified BiOBr thin film for enhanced photocatalytic performance under visible light irradiation

Surface modification on photocatalytic thin films is long considered as an effective strategy to improve the degradation performance,which in turn helps to alleviate the worldwide environmental pollution issue.In this study,a direct Z-scheme photocatalytic system is constructed successfully by integrating black phosphorus quantum dots(BPQDs)on the surface of BiOBr thin film prepared by hydrothermal method.The optimal BPQDs/BiOBr-1 thin film presents remarkable enhanced photocatalytic activity for degrading methyl violet(MV)and tetracycline hydrochloride(TC),which is 3 and 3.65 times higher than that of pure BiOBr counterpart.The active species involved in the reaction are ^(+),·O_(2)^(-),and·OH,which determined by radical trapping experiments.The formation of direct Z-scheme photocatalytic system makes electrons assembled in the conduction band(CB)of BPQDs and holes gathered in the valence band(VB)of BiOBr,which supports the generation of h^(+) and·O_(2)^(-) and in turn accelerates the photocatalytic reaction.Besides,the improved efficiency of charge separation,enhanced visible light absorption and enlarged specific surface area also contributed to the enhanced photocatalytic performance of BPQDs/BiOBr.This work provides a feasible strategy for optimizing photocatalytic thin films via detailed analyzing the role of BPQDs in the construction of direct Z-scheme photocatalysts.

Seynergistic effect of Mo and Zr additions on microstructure and mechanical properties of Nb-Ti-Si-based alloys additively manufactured by laser directed energy deposition

The synergistic effect of Mo and Zr additions on microstructure evolution,room-temperature fracture toughness and microhardness of Nb-22Ti-15Si-xMo-yZr(x=4,8,y=3,6)alloys manufactured by laser directed energy deposited(L-DED)have been investigated.The major phases in as-deposited 4Mo-3Zr alloy are Nb solid solution(Nbss),Nb_(3)Si andγ-Nb_(5)Si_(3).The Nb_(3)Si phases disappear with increasing Mo content to 8 at.%or increasing Zr content to 6%.γ-Nb_(5)Si_(3) precipitates formed in the Nbss of as-deposited xMo-yZr alloys due to the cyclic re-heating,and theγ-Nb_(5)Si_(3) precipitates and Nbss matrix exhibits orientation relationship(OR)of[001]Nbss//[1112]γand(110)Nbss//(0110)γin as-deposited 4Mo-6Zr alloy.The microstructure of xMo-yZr alloys became relative homogeneity and the Nbss matrix showed the better continuity after the heat treatment(1400°C/30 h).The Nb_(3)Si phase has transformed into Nbss andαNb_(5)Si_(3) with the OR have been determined as{100}Nbss//{100}αand{111}Nbss//{111}αin the heat-treated 4Mo-3Zr alloy.When Mo content increase to 8at.%,a part ofγ-Nb_(5)Si_(3) phase also transformed into theα-Nb_(5)Si_(3) phase with the OR have been determined as{1120}γ//{110}αand{1010}γ//{111}αafter heat treatment.Among the as-deposited alloys,the 4Mo-6Zr alloy has the highest fracture toughness KQ with the lowest hardness.The average KQ of 4Mo-6Zr and 8Mo-6Zr alloys increased by 28%and 30%after the heat treatment,and reached 13.61 and 11.43 MPa·m^(1/2),respectively.The hardness of Nb-22Ti-15Si-xMoyZr alloys is significantly decreased after the heat treatment.