Carbon nitride(CN) photocatalysts have attracted much attention due to their excellent photocatalytic properties.And hydrothermal fluorination is a common method to improve the photocatalytic effect of CN photocatalys...Carbon nitride(CN) photocatalysts have attracted much attention due to their excellent photocatalytic properties.And hydrothermal fluorination is a common method to improve the photocatalytic effect of CN photocatalyst.Here,the influence of the band gap was first revealed of fluorination and hydroxylation of CN photocatalyst based on the first theoretical principle.Here,the effect of fluorination and hydroxylation on the CN band gap was discussed for the first time using the first theoretical principle.With F atoms and OH doping,the band gap of CN was significantly improved,conduction band and valence band moved up.Then,F-CN photocatalyst with F atoms and OH was successfully synthesized by a hydrothermal fluorinated method.Next,the reasons why F-CN photocatalyst was more effective than that of traditional CN photocatalyst were fully discussed.From the photocatalytic effect of photocatalyst(12,593.2 μmolg^(-1) h^(-1)to the morphology(super-small nanosheets),structure(homojunctions),composition(metal-free),specific surface area(54.1 m^(2)/g),visible light absorption response(AQE is10.9% at 420 nm) and photo-induced carrier life(14.13 ns).Therefore,this work has a great guiding effect on the development of CN photocatalyst.展开更多
目的探讨TOF-PET(time of flight-positron emission tomography)对于评价小肿瘤病灶(病灶最长径<2cm)的临床应用价值。方法临床明确诊断肿瘤患者28例,共58个小病灶。PET-CT检查使用联影u MI S-96R进行全身扫描,扫描结束后使用UIdea...目的探讨TOF-PET(time of flight-positron emission tomography)对于评价小肿瘤病灶(病灶最长径<2cm)的临床应用价值。方法临床明确诊断肿瘤患者28例,共58个小病灶。PET-CT检查使用联影u MI S-96R进行全身扫描,扫描结束后使用UIdeal工作站进行图像重建,分别选用TOF和非TOF重建,均采用点扩展函数(point spread function,PSF)、最大期望值算法(ordered subsets expectation maximization,OSEM)、半高宽(full width at half maximum,FWHM)4.0。测量58个病灶的18F-FDG摄取,分别测量TOF与非TOF图像病灶的18F-FDG标准摄取率平均值(standard uptake value mean,SUVmean)、肝脏SUVmean和肝脏SD值,并计算图像的信噪比(signal-to-noise ratio,SNR)。应用SPSS 21统计软件包对数据进行统计学分析,采用配对t检验比较TOF-PET与非TOF-PET图像的测量值差异。结果 28例患者TOF-PET和非TOF-PET图像肝脏的SUVmean值无显著性差异(P>0.05)。FDG摄取增高的58个病灶,TOF-PET与非TOF-PET图像的SUVmean、SNR值均有显著性差异(P<0.01),TOF-PET图像测量值显著增高,SUVmean、SNR分别提高10.26%、11.96%。结论 TOF-PET技术较非TOF-PET技术可以明显提高小肿瘤病灶的SUVmean、SNR值,有助于提高临床小病灶的诊断能力。展开更多
Negative refraction and subwavelength imaging properties of a two-dimensional （2D） photonic crystal （PC） slab are studied by the finite-difference time-domain method. The PC consists of a triangular lattice of air...Negative refraction and subwavelength imaging properties of a two-dimensional （2D） photonic crystal （PC） slab are studied by the finite-difference time-domain method. The PC consists of a triangular lattice of air holes immersed in a dielectric. For a certain frequency range in the third photonic band, the directions of the group velocities and the phase velocities can be opposite, so the PC can work as a kind of negative refractive-index material. The light radiated from a point source can form a subwavelength image spot through the PC slab. Negative refraction and an effective refractive index of the PC slab n = -1 can be achieved for the incident wave with its incident angle within a certain range.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51802177,51672109)Independent Cultivation Program of Innovation Team of Ji’nan City(No.2019GXRC011)+1 种基金the Major Basic Program of the Natural Science Foundation of Shandong Province(Contract ZR2018ZC0842)Natural Science Foundation of Shandong Province(No.ZR2018BEM019)。
文摘Carbon nitride(CN) photocatalysts have attracted much attention due to their excellent photocatalytic properties.And hydrothermal fluorination is a common method to improve the photocatalytic effect of CN photocatalyst.Here,the influence of the band gap was first revealed of fluorination and hydroxylation of CN photocatalyst based on the first theoretical principle.Here,the effect of fluorination and hydroxylation on the CN band gap was discussed for the first time using the first theoretical principle.With F atoms and OH doping,the band gap of CN was significantly improved,conduction band and valence band moved up.Then,F-CN photocatalyst with F atoms and OH was successfully synthesized by a hydrothermal fluorinated method.Next,the reasons why F-CN photocatalyst was more effective than that of traditional CN photocatalyst were fully discussed.From the photocatalytic effect of photocatalyst(12,593.2 μmolg^(-1) h^(-1)to the morphology(super-small nanosheets),structure(homojunctions),composition(metal-free),specific surface area(54.1 m^(2)/g),visible light absorption response(AQE is10.9% at 420 nm) and photo-induced carrier life(14.13 ns).Therefore,this work has a great guiding effect on the development of CN photocatalyst.
基金supported by the National Key Basic Research Special Foundation of China(Nos.2006CB921702 and 2007CB310403)the National Natural Science Foundation of China(Nos.10674185 and 10801017) the Youth Foundation of Minzu University of China.
文摘Negative refraction and subwavelength imaging properties of a two-dimensional （2D） photonic crystal （PC） slab are studied by the finite-difference time-domain method. The PC consists of a triangular lattice of air holes immersed in a dielectric. For a certain frequency range in the third photonic band, the directions of the group velocities and the phase velocities can be opposite, so the PC can work as a kind of negative refractive-index material. The light radiated from a point source can form a subwavelength image spot through the PC slab. Negative refraction and an effective refractive index of the PC slab n = -1 can be achieved for the incident wave with its incident angle within a certain range.
