The outbreak of coronavirus disease 2019 has seriously threatened human health.Rapidly and sensitively detecting SARSCoV-2 viruses can help control the spread of viruses.However,it is an arduous challenge to apply sem...The outbreak of coronavirus disease 2019 has seriously threatened human health.Rapidly and sensitively detecting SARSCoV-2 viruses can help control the spread of viruses.However,it is an arduous challenge to apply semiconductor-based substrates for virus SERS detection due to their poor sensitivity.Therefore,it is worthwhile to search novel semiconductor-based substrates with excellent SERS sensitivity.Herein we report,for the first time,Nb2C and Ta2C MXenes exhibit a remarkable SERS enhancement,which is synergistically enabled by the charge transfer resonance enhancement and electromagnetic enhancement.Their SERS sensitivity is optimized to 3.0×10^6 and 1.4×10^6 under the optimal resonance excitation wavelength of 532 nm.Additionally,remarkable SERS sensitivity endows Ta2C MXenes with capability to sensitively detect and accurately identify the SARS-CoV-2 spike protein.Moreover,its detection limit is as low as 5×10^−9 M,which is beneficial to achieve real-time monitoring and early warning of novel coronavirus.This research not only provides helpful theoretical guidance for exploring other novel SERS-active semiconductor-based materials but also provides a potential candidate for the practical applications of SERS technology.展开更多
Grain growth inhibitors can effectively suppress the grain size of tungsten carbide(WC),and consequently improve the hardness and strength of the cemented carbides;however,the toughness,one of the most important prope...Grain growth inhibitors can effectively suppress the grain size of tungsten carbide(WC),and consequently improve the hardness and strength of the cemented carbides;however,the toughness,one of the most important properties,usually deteriorates with inhibitors.Here,(Cr,Mo,Ta)_(2)(C,N) synthesized by carbothermal reductionnitridation was used as a novel inhibitor,and its effects on the microstructure and mechanical properties of the cemented carbides were investigated.The results showed that the cemented carbides containing(Cr,Mo,Ta)_(2)(C,N)outperformed its counterpart comprising the traditional inhibitors in comprehensive mechanical properties,which was mainly attributed to the better inhibition performance provided by the(Cr,Mo,Ta)_(2)(C,N) solid-solution powders.With the content of(Cr,Mo,Ta)_(2)(C,N) increasing from 0 wt% to 1.25 wt%,the average grain size of WC in the cemented carbides decreased from 0.85 to 0.60 μm firstly,and then increased to 0.64 μm.With 1.00 wt%(Cr,Mo,-Ta)_(2)(C,N) addition,the cemented carbides with the best performance of hardness(HV_(30)) of 15.55 GPa,transverse rupture strength of 4272 MPa,fracture toughness of13.91 MPa·m1/2 were obtained.The electron backscattered diffraction(EBSD) measurements showed that cemented carbides with(Cr,Mo,Ta)_(2)(C,N) processed more amount of∑2 boundary compared with the other specimens,which contributed to better fracture resistance.展开更多
基金The authors gratefully acknowledge the finical support of the National Key Research and Development Project(No.2017YFB0310600)this work is also supported by Shanghai International Science and Technology Cooperation Fund(Nos.17520711700 and 18520744200).
文摘The outbreak of coronavirus disease 2019 has seriously threatened human health.Rapidly and sensitively detecting SARSCoV-2 viruses can help control the spread of viruses.However,it is an arduous challenge to apply semiconductor-based substrates for virus SERS detection due to their poor sensitivity.Therefore,it is worthwhile to search novel semiconductor-based substrates with excellent SERS sensitivity.Herein we report,for the first time,Nb2C and Ta2C MXenes exhibit a remarkable SERS enhancement,which is synergistically enabled by the charge transfer resonance enhancement and electromagnetic enhancement.Their SERS sensitivity is optimized to 3.0×10^6 and 1.4×10^6 under the optimal resonance excitation wavelength of 532 nm.Additionally,remarkable SERS sensitivity endows Ta2C MXenes with capability to sensitively detect and accurately identify the SARS-CoV-2 spike protein.Moreover,its detection limit is as low as 5×10^−9 M,which is beneficial to achieve real-time monitoring and early warning of novel coronavirus.This research not only provides helpful theoretical guidance for exploring other novel SERS-active semiconductor-based materials but also provides a potential candidate for the practical applications of SERS technology.
基金financially supported by the National Key Research and Development Plan of China(No.2017YFB0305900)the Sichuan Provincial Science Research Program of China(No.2017GZ0120)the Zigong/Sichuan University Science and Technology Cooperation Special Project(No.2018CDZG-14)。
文摘Grain growth inhibitors can effectively suppress the grain size of tungsten carbide(WC),and consequently improve the hardness and strength of the cemented carbides;however,the toughness,one of the most important properties,usually deteriorates with inhibitors.Here,(Cr,Mo,Ta)_(2)(C,N) synthesized by carbothermal reductionnitridation was used as a novel inhibitor,and its effects on the microstructure and mechanical properties of the cemented carbides were investigated.The results showed that the cemented carbides containing(Cr,Mo,Ta)_(2)(C,N)outperformed its counterpart comprising the traditional inhibitors in comprehensive mechanical properties,which was mainly attributed to the better inhibition performance provided by the(Cr,Mo,Ta)_(2)(C,N) solid-solution powders.With the content of(Cr,Mo,Ta)_(2)(C,N) increasing from 0 wt% to 1.25 wt%,the average grain size of WC in the cemented carbides decreased from 0.85 to 0.60 μm firstly,and then increased to 0.64 μm.With 1.00 wt%(Cr,Mo,-Ta)_(2)(C,N) addition,the cemented carbides with the best performance of hardness(HV_(30)) of 15.55 GPa,transverse rupture strength of 4272 MPa,fracture toughness of13.91 MPa·m1/2 were obtained.The electron backscattered diffraction(EBSD) measurements showed that cemented carbides with(Cr,Mo,Ta)_(2)(C,N) processed more amount of∑2 boundary compared with the other specimens,which contributed to better fracture resistance.
