Benefiting from the large Stokes shift between fluorescence and phosphorescence,fluorescence/phosphorescence dual-emitting carbon dots(CDs)have gradually entered at the stage of single-phase white light-emitting diode...Benefiting from the large Stokes shift between fluorescence and phosphorescence,fluorescence/phosphorescence dual-emitting carbon dots(CDs)have gradually entered at the stage of single-phase white light-emitting diodes(WLEDs)as‘green material'.However,most of the developed dual-emitting CDs have weak phosphorescence,short emission wavelength and narrow emission band,resulting in relatively bluish white light emission and low color rendering index(CRI).Herein,an ultrabroad-band fluorescence/phosphorescence dual-emitting CD-based material(UB-CD@BA)is prepared by thermal treatment of boric acid(BA)and CDs with large conjugated structure.The stable covalent bonding between CDs and BA,as well as three-dimensional spatial restriction effect of selfpolymerization BA molecules around CDs during long-term heating efficiently rigidified the single/triplet excited states of CDs from non-radiative deactivation,thus producing strong dual emissive materials with the high phosphorescence quantum yield of 21%.Remarkable,the prepared UB-CD@BA powders exhibit bright pure white light emission with Commission Internationale de l'Eclairage(CIE)coordinates of(0.32,0.33)and the highest reported full width at half maximum of 250 nm.Based on the unique characteristics of UB-CD@BA,it was used as a color conversion layer to prepare a WLED with CIE coordinates of(0.35,0.33)and the CRI value of 87.展开更多
Aiming to address the issues of inconvenience and low efficiency associated with manual harvesting of safflower silk and the high damage rate of cutting harvesting machinery,the effect of manual grasping and drawing w...Aiming to address the issues of inconvenience and low efficiency associated with manual harvesting of safflower silk and the high damage rate of cutting harvesting machinery,the effect of manual grasping and drawing was simulated and a safflower drawing and harvesting device was designed based on flexible clamping.A quadratic regression orthogonal rotation combination design was implemented,adopting clamping frequency,spring installation angle,and flower board angle as factors while targeting removal and damage rates as performance metrics.Analysis identified clamping frequency as the predominant factor governing device recovery rate,with spring installation angle and flower board angle exerting secondary influence.Spring installation angle emerged as the dominant factor affecting device damage rate,followed sequentially by flower board angle and clamping frequency.The optimal parameters of the harvesting device are as follows:clamping frequency of 50 times/min,initial installation angle of the spring of 3.2°,and an initial angle of the flower board of 25°.Field tests with optimized parameters demonstrated a 96.28%removal rate and a 2.29%damage rate.The research findings can provide theoretical guidance for the structural design and optimization of the mechanized harvesting device for safflower filaments.展开更多
Biosensors are a focus of research on terahertz metasurfaces. However, reports of ultra-sensitive biosensors based on Dirac points are rare. Here, a new terahertz metasurface is proposed that consists of patterned gra...Biosensors are a focus of research on terahertz metasurfaces. However, reports of ultra-sensitive biosensors based on Dirac points are rare. Here, a new terahertz metasurface is proposed that consists of patterned graphene and perovskites. This serves as an ultra-sensitive Dirac-point-based biosensor for qualitative detection of sericin.Theoretically, sericin may make graphene n-doped and drive the Fermi level to shift from the valence band to the Dirac point, causing a dramatic decrease in conductivity. Correspondingly, the dielectric environment on the metasurface undergoes significant change, which is suited for ultra-sensitive biosensing. In addition, metal halide perovskites, which are up-to-date optoelectronic materials, have a positive effect on the phase during terahertz wave transmission. Thus, this sensor was used to successfully detect sericin with a detection limit of 780 pg/m L, achieved by changing the amplitude and phase. The detection limit of this sensor is as much as one order of magnitude lower than that of sensors in published works. These results show that the Dirac-pointbased biosensor is a promising platform for a wide range of ultra-sensitive and qualitative detection in biosensing and biological sciences.展开更多
基金the support from the National Natural Science Foundation of China(Nos.52002152 and 62005106)the Natural Science Foundation of Jiangsu Province(Nos.BK20190864 and BK20190865)the Primary Research&Development Plan of Zhenjiang-Modern Agriculture(No.NY2021007)。
文摘Benefiting from the large Stokes shift between fluorescence and phosphorescence,fluorescence/phosphorescence dual-emitting carbon dots(CDs)have gradually entered at the stage of single-phase white light-emitting diodes(WLEDs)as‘green material'.However,most of the developed dual-emitting CDs have weak phosphorescence,short emission wavelength and narrow emission band,resulting in relatively bluish white light emission and low color rendering index(CRI).Herein,an ultrabroad-band fluorescence/phosphorescence dual-emitting CD-based material(UB-CD@BA)is prepared by thermal treatment of boric acid(BA)and CDs with large conjugated structure.The stable covalent bonding between CDs and BA,as well as three-dimensional spatial restriction effect of selfpolymerization BA molecules around CDs during long-term heating efficiently rigidified the single/triplet excited states of CDs from non-radiative deactivation,thus producing strong dual emissive materials with the high phosphorescence quantum yield of 21%.Remarkable,the prepared UB-CD@BA powders exhibit bright pure white light emission with Commission Internationale de l'Eclairage(CIE)coordinates of(0.32,0.33)and the highest reported full width at half maximum of 250 nm.Based on the unique characteristics of UB-CD@BA,it was used as a color conversion layer to prepare a WLED with CIE coordinates of(0.35,0.33)and the CRI value of 87.
基金supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region(Grant No.2022D01B30).
文摘Aiming to address the issues of inconvenience and low efficiency associated with manual harvesting of safflower silk and the high damage rate of cutting harvesting machinery,the effect of manual grasping and drawing was simulated and a safflower drawing and harvesting device was designed based on flexible clamping.A quadratic regression orthogonal rotation combination design was implemented,adopting clamping frequency,spring installation angle,and flower board angle as factors while targeting removal and damage rates as performance metrics.Analysis identified clamping frequency as the predominant factor governing device recovery rate,with spring installation angle and flower board angle exerting secondary influence.Spring installation angle emerged as the dominant factor affecting device damage rate,followed sequentially by flower board angle and clamping frequency.The optimal parameters of the harvesting device are as follows:clamping frequency of 50 times/min,initial installation angle of the spring of 3.2°,and an initial angle of the flower board of 25°.Field tests with optimized parameters demonstrated a 96.28%removal rate and a 2.29%damage rate.The research findings can provide theoretical guidance for the structural design and optimization of the mechanized harvesting device for safflower filaments.
基金National Natural Science Foundation of China(61675147, 61701434, 61735010)Special Funding of the Taishan Scholar Project (tsqn201909150)+6 种基金Natural Science Foundation of Guangxi Province (ZR2020FK008)National Key Research and Development Program of China(2017YFA0700202, 2017YFB1401203)Qingchuang Science and Technology Plan of Shandong Universities(2019KJN001)Shandong Province Higher Education Science and Technology Program (J17KA087)Natural Science Foundation of Jiangsu Province (BK20180862)China Postdoctoral Fund (2019M651725)Natural Science Foundation of Shandong Province (ZR202102180769)。
文摘Biosensors are a focus of research on terahertz metasurfaces. However, reports of ultra-sensitive biosensors based on Dirac points are rare. Here, a new terahertz metasurface is proposed that consists of patterned graphene and perovskites. This serves as an ultra-sensitive Dirac-point-based biosensor for qualitative detection of sericin.Theoretically, sericin may make graphene n-doped and drive the Fermi level to shift from the valence band to the Dirac point, causing a dramatic decrease in conductivity. Correspondingly, the dielectric environment on the metasurface undergoes significant change, which is suited for ultra-sensitive biosensing. In addition, metal halide perovskites, which are up-to-date optoelectronic materials, have a positive effect on the phase during terahertz wave transmission. Thus, this sensor was used to successfully detect sericin with a detection limit of 780 pg/m L, achieved by changing the amplitude and phase. The detection limit of this sensor is as much as one order of magnitude lower than that of sensors in published works. These results show that the Dirac-pointbased biosensor is a promising platform for a wide range of ultra-sensitive and qualitative detection in biosensing and biological sciences.
