To overcome the low efficiency of conventional confocal Raman spectroscopy,many efforts have been devoted to parallelizing the Raman excitation and acquisition,in which the scattering from multiple foci is projected o...To overcome the low efficiency of conventional confocal Raman spectroscopy,many efforts have been devoted to parallelizing the Raman excitation and acquisition,in which the scattering from multiple foci is projected onto different locations on a spectrometer's CCD,along either its vertical,horizontal dimension,or even both.While the latter projection scheme relieves the limitation on the row numbers of the CCD,the spectra of multiple foci are recorded in one spectral channel,resulting in spectral overlapping.Here,we developed a method under a com-pressive sensing framework to demultiplex the superimposed spectra of multiple cells during their dynamic processes.Unlike the previous methods which ignore the information connection be-tween the spectra of the cells recorded at different time,the proposed method utilizes a prior that a cell's spectra acquired at different time have the same sparsity structure in their principal components.Rather than independently demultiplexing the mixed spectra at the individual time intervals,the method demultiplexes the whole spectral sequence acquired continuously during the dynamic process.By penalizing the sparsity combined from all time intervals,the collaborative optimization of the inversion problem gave more accurate recovery results.The performances of the method were substantiated by a 1D Raman tweezers array,which monitored the germination of multiple bacterial spores.The method can be extended to the monitoring of many living cells randomly scattering on a coverslip,and has a potential to improve the throughput by a few orders.展开更多
The electroactive materials used in the counter electrode(CE)are of great concern as they influence the photovoltaic performances of dye-sensitized solar cells.The main functions of CE materials are collecting electro...The electroactive materials used in the counter electrode(CE)are of great concern as they influence the photovoltaic performances of dye-sensitized solar cells.The main functions of CE materials are collecting electrons from the external circuit and transferring them to the electrolyte and realizing the catalytic reduction of the redox species(I3^– or Co^3+)present in the electrolyte.The research hotspot of CE materials is seeking functional materials that display high efficiency,low cost,and good electrochemical stability and can substitute the benchmark platinum electrode.Chalcogen compounds of cobalt,nickel,and iron have been widely applied as CE materials and exhibit excellent electrocatalytic performances owing to their unique electrical properties,similar energies of adsorption of I atoms as platinum,excellent catalytic activities,and good chemical stabilities.In this review,we trace the developments and performances of chalcogen compounds of iron,cobalt,and nickel as CE materials and present the latest research directions for improving the electrocatalytic performances.We then highlight the optimization strategies for further improving their performances,such as fabrication of architectures,regulation of the components,synthesis of composites containing carbon materials,and elemental doping.展开更多
Semiconductor combination is one of the most common strategies to obtain high-efficiency photocatalysts;however, the effect mechanism of composition ratio on micro-structure and photocatalytic activity is remaining un...Semiconductor combination is one of the most common strategies to obtain high-efficiency photocatalysts;however, the effect mechanism of composition ratio on micro-structure and photocatalytic activity is remaining unclear. In this study, a case of g-C_(3)N_(4) quantum dots@SnS_(2) (CNQDn@SnS_(2)) heterojunction with different ratio of CNQD is used to uncover the origin of optimum and excess composition for photocatalysts. Research on the functional mechanism of the optimum composition shows that 0.8 wt.% CNQD are completely attached to the non-(001) facets of SnS_(2), which benefits the formation of type-II heterojunction, resulting in an optimal pollutant degradation and mineralization efficiency. For the excess composition, both experiments and theoretical calculations confirm that excess CNQD (the part exceeding of 0.8 wt.%) located on the (001) facet of SnS_(2), leading to the type-I band alignment of this heterojunction, which severely restricts the separation of photo-induced charge carriers, and thus reduces their lifetime. This work makes the functional mechanism of composition ratio on micro-structure and photocatalytic activity clearer. Related research results provide a new insight into semiconductor combination study and take an important step toward the rational design of highly active photocatalysts.展开更多
In order to study the application of gas fire extinguishing agents in civil aircraft fire extinguishing systems,the corrosion characteristics and mechanisms of Halon 1301 and CF_(3)I on AZ80A magnesium alloy were comp...In order to study the application of gas fire extinguishing agents in civil aircraft fire extinguishing systems,the corrosion characteristics and mechanisms of Halon 1301 and CF_(3)I on AZ80A magnesium alloy were comparatively analyzed.The experimental methods combined with density functional theory were applied to explore the corrosion mechanism.The results indicate that Halon 1301 and CF_(3)I exhibit good compatibility with AZ80A magnesium alloy through physical adsorption at room temperature and pressure,where Halon 1301 has a more stable adsorption configuration.However,with increasing temperature,pyrolysis reactions occur leading to the formation of fluorine containing corrosive substances which can react with magnesium alloy to generate the corrosion production of MgF_(2) and coke.Although MgF_(2) and coke can partically reduce reaction rates and protect against corrosion,the presence of MgF_(2) promotes further pyrolysis,generating more corrosion products.Consequently,the accumulation of corrosion products leads to a loss of metallic luster and a decline in mechanical properties of magnesium alloy along with interfacial cracking due to mutual extrusion between MgF_(2) and carbon deposition layers.These studies offer theoretical guidance for utilizing CF_(3)I in civil aircraft fire extinguishing systems while facilitating rapid screening for efficient clean gas extinguishing agents.展开更多
Although nickel-based catalysts display good catalytic capability and excellent corrosion resistance under alkaline electrolytes for water splitting,it is still imperative to enhance their activity for real device app...Although nickel-based catalysts display good catalytic capability and excellent corrosion resistance under alkaline electrolytes for water splitting,it is still imperative to enhance their activity for real device applications.Herein,we decorated Ni0.85Se hollow nanospheres onto reduced graphene oxide(RGO)through a hydrothermal route,then annealed this composite at different temperatures(400℃,NiSe2-400 and 450℃,NiSe2-450)under argon atmosphere,yielding a kind of NiSe2/RGO composite catalysts.Positron annihilation spectra revealed two types of vacancies formed in this composite catalyst.We found that the NiSe2-400 catalyst with dual Ni-Se vacancies is able to catalyze the oxygen evolution reaction(OER)efficiently,needing a mere 241 mV overpotential at 10 mA·cm−2.In addition,this catalyst exhibits outstanding stability.Computational studies show favorable energy barrier on NiSe2-400,enabling moderate OH−adsorption and O2 desorption,which leads to the enhanced energetics for OER.展开更多
基金This work was supported by the National Key R&D Program of China(2019YFC1605500,2018YFF01011700)the National Natural Science Foundation of China(21973111)+1 种基金Guangxi Natural Science Foundation(2017GXNSFAA198029)Scientific Development Fund of Guangxi Academy of Sciences(2018YFJ 403).
文摘To overcome the low efficiency of conventional confocal Raman spectroscopy,many efforts have been devoted to parallelizing the Raman excitation and acquisition,in which the scattering from multiple foci is projected onto different locations on a spectrometer's CCD,along either its vertical,horizontal dimension,or even both.While the latter projection scheme relieves the limitation on the row numbers of the CCD,the spectra of multiple foci are recorded in one spectral channel,resulting in spectral overlapping.Here,we developed a method under a com-pressive sensing framework to demultiplex the superimposed spectra of multiple cells during their dynamic processes.Unlike the previous methods which ignore the information connection be-tween the spectra of the cells recorded at different time,the proposed method utilizes a prior that a cell's spectra acquired at different time have the same sparsity structure in their principal components.Rather than independently demultiplexing the mixed spectra at the individual time intervals,the method demultiplexes the whole spectral sequence acquired continuously during the dynamic process.By penalizing the sparsity combined from all time intervals,the collaborative optimization of the inversion problem gave more accurate recovery results.The performances of the method were substantiated by a 1D Raman tweezers array,which monitored the germination of multiple bacterial spores.The method can be extended to the monitoring of many living cells randomly scattering on a coverslip,and has a potential to improve the throughput by a few orders.
基金supported by the National Science Fund for Distinguished Young Scholars(21425729)from the National Natural Science Foundation of Chinathe National Special S&T Project on Water Pollution Control and Treatment(2017ZX07107002)+1 种基金China Postdoctoral Science Foundation(2018M640209)the Tianjin Science and Technology Support Key Projects(18YFZCSF00500)~~
文摘The electroactive materials used in the counter electrode(CE)are of great concern as they influence the photovoltaic performances of dye-sensitized solar cells.The main functions of CE materials are collecting electrons from the external circuit and transferring them to the electrolyte and realizing the catalytic reduction of the redox species(I3^– or Co^3+)present in the electrolyte.The research hotspot of CE materials is seeking functional materials that display high efficiency,low cost,and good electrochemical stability and can substitute the benchmark platinum electrode.Chalcogen compounds of cobalt,nickel,and iron have been widely applied as CE materials and exhibit excellent electrocatalytic performances owing to their unique electrical properties,similar energies of adsorption of I atoms as platinum,excellent catalytic activities,and good chemical stabilities.In this review,we trace the developments and performances of chalcogen compounds of iron,cobalt,and nickel as CE materials and present the latest research directions for improving the electrocatalytic performances.We then highlight the optimization strategies for further improving their performances,such as fabrication of architectures,regulation of the components,synthesis of composites containing carbon materials,and elemental doping.
基金This work was supported by National Key Research and Development Program of China(No.2018YFB0605101)the National Natural Science Foundation of China(Nos.21701125 and 21403001)+4 种基金Natural Science Foundation of Tianjin(No.20JCQNJC00950)China Postdoctoral Science Foundation(Nos.2020M680869 and 2019TQ0299)Key R&D projects in Hebei Province(No.20373701D)Natural Science Foundation of Hebei Province(B2019202455)Overseas High-level Talents Introduction Plan Foundation of Hebei Province(No.E2019050012).
文摘Semiconductor combination is one of the most common strategies to obtain high-efficiency photocatalysts;however, the effect mechanism of composition ratio on micro-structure and photocatalytic activity is remaining unclear. In this study, a case of g-C_(3)N_(4) quantum dots@SnS_(2) (CNQDn@SnS_(2)) heterojunction with different ratio of CNQD is used to uncover the origin of optimum and excess composition for photocatalysts. Research on the functional mechanism of the optimum composition shows that 0.8 wt.% CNQD are completely attached to the non-(001) facets of SnS_(2), which benefits the formation of type-II heterojunction, resulting in an optimal pollutant degradation and mineralization efficiency. For the excess composition, both experiments and theoretical calculations confirm that excess CNQD (the part exceeding of 0.8 wt.%) located on the (001) facet of SnS_(2), leading to the type-I band alignment of this heterojunction, which severely restricts the separation of photo-induced charge carriers, and thus reduces their lifetime. This work makes the functional mechanism of composition ratio on micro-structure and photocatalytic activity clearer. Related research results provide a new insight into semiconductor combination study and take an important step toward the rational design of highly active photocatalysts.
基金supported by the Joint Funds of the National Natural Science Foundation of China“False alarm immunity fire detection mechanism and key technologies of civil aviation aircraft cargo compartment”[Grant No.U213320003]Science and Technology Program of Tianjin“Research on fire characteristics and advanced halo-carbon fire extinguishing technology of domestic civil aircraft”[Grant No.21JCZDJC00810].
文摘In order to study the application of gas fire extinguishing agents in civil aircraft fire extinguishing systems,the corrosion characteristics and mechanisms of Halon 1301 and CF_(3)I on AZ80A magnesium alloy were comparatively analyzed.The experimental methods combined with density functional theory were applied to explore the corrosion mechanism.The results indicate that Halon 1301 and CF_(3)I exhibit good compatibility with AZ80A magnesium alloy through physical adsorption at room temperature and pressure,where Halon 1301 has a more stable adsorption configuration.However,with increasing temperature,pyrolysis reactions occur leading to the formation of fluorine containing corrosive substances which can react with magnesium alloy to generate the corrosion production of MgF_(2) and coke.Although MgF_(2) and coke can partically reduce reaction rates and protect against corrosion,the presence of MgF_(2) promotes further pyrolysis,generating more corrosion products.Consequently,the accumulation of corrosion products leads to a loss of metallic luster and a decline in mechanical properties of magnesium alloy along with interfacial cracking due to mutual extrusion between MgF_(2) and carbon deposition layers.These studies offer theoretical guidance for utilizing CF_(3)I in civil aircraft fire extinguishing systems while facilitating rapid screening for efficient clean gas extinguishing agents.
基金We acknowledge financial support from the Tianjin science and technology support key projects(No.18YFZCSF00500)the National Natural Science Foundation of China(Nos.21521001,21431006,21225315,21321002,91645202,51702312,and 21975237)+6 种基金the Users with Excellence and Scientific Research Grant of Hefei Science Center of CAS(No.2015HSCUE007)the Key Research Program of Frontier Sciences,CAS(No.QYZDJ-SSW-SLH036)the National Basic Research Program of China(Nos.2014CB931800 and 2018YFA0702001)the Chinese Academy of Sciences(Nos.KGZD-EW-T05 and XDA090301001)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA21000000)the Fundamental Research Funds for the Central Universities(No.WK2340000076)the Recruitment Program of Global Youth Experts.
文摘Although nickel-based catalysts display good catalytic capability and excellent corrosion resistance under alkaline electrolytes for water splitting,it is still imperative to enhance their activity for real device applications.Herein,we decorated Ni0.85Se hollow nanospheres onto reduced graphene oxide(RGO)through a hydrothermal route,then annealed this composite at different temperatures(400℃,NiSe2-400 and 450℃,NiSe2-450)under argon atmosphere,yielding a kind of NiSe2/RGO composite catalysts.Positron annihilation spectra revealed two types of vacancies formed in this composite catalyst.We found that the NiSe2-400 catalyst with dual Ni-Se vacancies is able to catalyze the oxygen evolution reaction(OER)efficiently,needing a mere 241 mV overpotential at 10 mA·cm−2.In addition,this catalyst exhibits outstanding stability.Computational studies show favorable energy barrier on NiSe2-400,enabling moderate OH−adsorption and O2 desorption,which leads to the enhanced energetics for OER.
