To guarantee the exact proton dose applied to patients and ensure treatment safety while disrupting and destroying tumor cells,it is essential to accurately monitor the proton beam current in real time during patient ...To guarantee the exact proton dose applied to patients and ensure treatment safety while disrupting and destroying tumor cells,it is essential to accurately monitor the proton beam current in real time during patient treatment.Because clinical treatment requires a proton beam current in the∼nA range,nondestructive beam current monitors(BCMs)are preferred to minimize the degradation of beam quality.However,this poses significant challenges in accurately monitoring such extremely low beam intensities.This study proposes a cavity-type BCM equipped with a dielectric plate to reduce its dimensions and achieve sufficient measurement sensitivity for practical requirements.A prototype cavity BCM was fabricated,and off-line testing was performed using a metal wire to simulate the beam to study its performance.Both the simulation and experi-mental results showed that the cavity BCM could measure ultralow proton beam currents with a resolution up to 0.03 nA.展开更多
Halogens are elements in soil and water that occur as organic and inorganic species.Studies have shown that inorganic halogens are closely related to animal and plant life.Matrix-assisted laser desorption/ionization m...Halogens are elements in soil and water that occur as organic and inorganic species.Studies have shown that inorganic halogens are closely related to animal and plant life.Matrix-assisted laser desorption/ionization mass spectrometry(MALDI-MS)can achieve high-throughput and rapid analysis,which is also an essential characteristic in some environmental studies.However,there is currently no report on MALDI-MS analysis for water-soluble inorganic halogen compounds.In this study,we aimed to develop a reliable and reproductive method to detect inorganic halogens in soil and water by MALDI-MS.Based on sinapic acid(SA)and silver trifluoromethanesulfonate(SA/AgOTf)as the matrix in negative-ion mode,MALDI-MS showed excellent MS signals related to halogens.Under the optimum conditions,the method achieved satisfactory linearity(R^(2)>0.99)and repeatability(RSD<18%).The LODs for Cl^(−),Br^(−)and I^(−)were 0.76,0.11 and 0.10μg/mL,respectively.The concentration of inorganic halogens from 24 samples was successfully determined by MALDI-MS.In summary,an innovative method was developed for the analysis of inorganic halogens by MALDI-MS using a novel SA/AgOTf matrix,extending the application of MALDI-MS in inorganic compounds.展开更多
基金supported by the National Natural Science Foundation of China(No.12235005)the National Key Research and Development Program of China(No.2016YFC0105309).
文摘To guarantee the exact proton dose applied to patients and ensure treatment safety while disrupting and destroying tumor cells,it is essential to accurately monitor the proton beam current in real time during patient treatment.Because clinical treatment requires a proton beam current in the∼nA range,nondestructive beam current monitors(BCMs)are preferred to minimize the degradation of beam quality.However,this poses significant challenges in accurately monitoring such extremely low beam intensities.This study proposes a cavity-type BCM equipped with a dielectric plate to reduce its dimensions and achieve sufficient measurement sensitivity for practical requirements.A prototype cavity BCM was fabricated,and off-line testing was performed using a metal wire to simulate the beam to study its performance.Both the simulation and experi-mental results showed that the cavity BCM could measure ultralow proton beam currents with a resolution up to 0.03 nA.
基金This study was jointly supported by the National Natural Science Foundation of China(21906137)the Science and Technology Program of Zhejiang Province(LGC21B050008).
文摘Halogens are elements in soil and water that occur as organic and inorganic species.Studies have shown that inorganic halogens are closely related to animal and plant life.Matrix-assisted laser desorption/ionization mass spectrometry(MALDI-MS)can achieve high-throughput and rapid analysis,which is also an essential characteristic in some environmental studies.However,there is currently no report on MALDI-MS analysis for water-soluble inorganic halogen compounds.In this study,we aimed to develop a reliable and reproductive method to detect inorganic halogens in soil and water by MALDI-MS.Based on sinapic acid(SA)and silver trifluoromethanesulfonate(SA/AgOTf)as the matrix in negative-ion mode,MALDI-MS showed excellent MS signals related to halogens.Under the optimum conditions,the method achieved satisfactory linearity(R^(2)>0.99)and repeatability(RSD<18%).The LODs for Cl^(−),Br^(−)and I^(−)were 0.76,0.11 and 0.10μg/mL,respectively.The concentration of inorganic halogens from 24 samples was successfully determined by MALDI-MS.In summary,an innovative method was developed for the analysis of inorganic halogens by MALDI-MS using a novel SA/AgOTf matrix,extending the application of MALDI-MS in inorganic compounds.
