[Objectives]This study was conducted to establish a method for the determination of aspartame in liquor by high performance liquid chromatography.[Methods]The liquor samples having volumes fixed with ultrapure water w...[Objectives]This study was conducted to establish a method for the determination of aspartame in liquor by high performance liquid chromatography.[Methods]The liquor samples having volumes fixed with ultrapure water were filtered by 0.22μm water phase,and then the content of aspartame in liquor was determined by high performance liquid chromatography using methanol(A)and ultrapure water(B)as mobile phase for isocratic elution.[Results]The results showed that a good linearity was obtained for the standard curve(R^(2)=99.98%)in the method,and its quantitative limit was 5.34 mg/kg.Its recovery was 91.26%,91.92%,and 90.55%,respectively.[Conclusions]The method has high sensitivity,high recovery and low quantitative limit,and it was a suitable method for the determination of aspartame in liquor.展开更多
A new amplitude-only synthesis approach in quintuple electric dipoles(EDs)is proposed to enable the regulation of power flow in the azimuthal plane.The regulation methodology is investigated analytically with double E...A new amplitude-only synthesis approach in quintuple electric dipoles(EDs)is proposed to enable the regulation of power flow in the azimuthal plane.The regulation methodology is investigated analytically with double ED,triple ED and quintuple ED models.First,when the phase difference between the EDs switches,the double ED model,acting as a reconfigurable source,can work in two modes with different power flow directions,i.e.,unidirectional mode and bidirectional mode.Then,from the triple ED model,it is verified that the power flow in the two working modes can be regulated to the desired direction in the azimuthal plane with high precision by controlling the feeding amplitudes of the dipoles.Moreover,a quintuple ED model is developed to enhance the symmetry and consistency of the power flow regulation in the plane.Finally,a prototype of the azimuthal beam steering system,including digitally controlled radio-frequency(RF)frontend tuning circuits,optimized practical feeding elements,and an end-fire radiator,is designed,fabricated and measured.Both unidirectional and bidirectional modes are observed,and satisfactory single-beam and dual-beam steering performance in the azimuthal plane is achieved.Unlike most phased arrays that realize beam steering by configuring phases,the beam steering of the proposed reconfigurable source in each mode can be arbitrarily synthesized only by the amplitudes of the quintuple feeding elements,which provides a new route for realizing low-cost and multifunctional beam-steering systems.展开更多
Nowadays,carbon frameworks derived from natural biomaterials have attracted extensive attention for electromagnetic interference(EMI)shielding due to their renewability and affordability.However,it is critical and cha...Nowadays,carbon frameworks derived from natural biomaterials have attracted extensive attention for electromagnetic interference(EMI)shielding due to their renewability and affordability.However,it is critical and challenging to achieve effective regulation of shielding effectiveness(SE)as well as weaken the strong EM reflection of highly conductive biomass-based carbon materials.Herein,commercial cotton pads with oriented structure were selected as carbonaceous precursor to fabricate aligned carbon networks by pyrolysis,and the EMI SE of the samples with increased temperature of 800-1000℃ can be accurately controlled in the effective range of~21.7-29.1,~27.7-37.1 and~32.7-43.3 d B with high reflection coefficient of>0.8 by changing the cross-angle between the electric-field direction of incident EM waves and the fiber-orientation direction due to the occurrence of opposite internal electric field.Moreover,the further construction of Salisbury absorber-liked double-layer structure could result in an ultralow reflection coefficient of only~0.06 but enhanced SE variation range up to~38.7-49.3 d B during the adjustment of cross-angle,possibly due to the destructive interference of EM waves in the double-layer carbon networks.This work would provide a simple and effective way for constructing high-performance biomass carbon materials with adjustable EMI shielding and ultra-low reflectivity.展开更多
文摘[Objectives]This study was conducted to establish a method for the determination of aspartame in liquor by high performance liquid chromatography.[Methods]The liquor samples having volumes fixed with ultrapure water were filtered by 0.22μm water phase,and then the content of aspartame in liquor was determined by high performance liquid chromatography using methanol(A)and ultrapure water(B)as mobile phase for isocratic elution.[Results]The results showed that a good linearity was obtained for the standard curve(R^(2)=99.98%)in the method,and its quantitative limit was 5.34 mg/kg.Its recovery was 91.26%,91.92%,and 90.55%,respectively.[Conclusions]The method has high sensitivity,high recovery and low quantitative limit,and it was a suitable method for the determination of aspartame in liquor.
文摘A new amplitude-only synthesis approach in quintuple electric dipoles(EDs)is proposed to enable the regulation of power flow in the azimuthal plane.The regulation methodology is investigated analytically with double ED,triple ED and quintuple ED models.First,when the phase difference between the EDs switches,the double ED model,acting as a reconfigurable source,can work in two modes with different power flow directions,i.e.,unidirectional mode and bidirectional mode.Then,from the triple ED model,it is verified that the power flow in the two working modes can be regulated to the desired direction in the azimuthal plane with high precision by controlling the feeding amplitudes of the dipoles.Moreover,a quintuple ED model is developed to enhance the symmetry and consistency of the power flow regulation in the plane.Finally,a prototype of the azimuthal beam steering system,including digitally controlled radio-frequency(RF)frontend tuning circuits,optimized practical feeding elements,and an end-fire radiator,is designed,fabricated and measured.Both unidirectional and bidirectional modes are observed,and satisfactory single-beam and dual-beam steering performance in the azimuthal plane is achieved.Unlike most phased arrays that realize beam steering by configuring phases,the beam steering of the proposed reconfigurable source in each mode can be arbitrarily synthesized only by the amplitudes of the quintuple feeding elements,which provides a new route for realizing low-cost and multifunctional beam-steering systems.
基金financial supports from Natural Science Foundation of Ningbo(202003N4026)S&T Innovation 2025 Major Special Programme of Ningbo(2018B10054)National Natural Science Foundation of China(62001065 and 51603218)。
文摘Nowadays,carbon frameworks derived from natural biomaterials have attracted extensive attention for electromagnetic interference(EMI)shielding due to their renewability and affordability.However,it is critical and challenging to achieve effective regulation of shielding effectiveness(SE)as well as weaken the strong EM reflection of highly conductive biomass-based carbon materials.Herein,commercial cotton pads with oriented structure were selected as carbonaceous precursor to fabricate aligned carbon networks by pyrolysis,and the EMI SE of the samples with increased temperature of 800-1000℃ can be accurately controlled in the effective range of~21.7-29.1,~27.7-37.1 and~32.7-43.3 d B with high reflection coefficient of>0.8 by changing the cross-angle between the electric-field direction of incident EM waves and the fiber-orientation direction due to the occurrence of opposite internal electric field.Moreover,the further construction of Salisbury absorber-liked double-layer structure could result in an ultralow reflection coefficient of only~0.06 but enhanced SE variation range up to~38.7-49.3 d B during the adjustment of cross-angle,possibly due to the destructive interference of EM waves in the double-layer carbon networks.This work would provide a simple and effective way for constructing high-performance biomass carbon materials with adjustable EMI shielding and ultra-low reflectivity.
