How the state of living muscles modulates the features of nonlinear elastic waves generated by external dynamic loads remains unclear because of the challenge of directly observing and modeling nonlinear elastic waves...How the state of living muscles modulates the features of nonlinear elastic waves generated by external dynamic loads remains unclear because of the challenge of directly observing and modeling nonlinear elastic waves in skeletal muscles in vivo,considering their active deformation behavior.Here,this important issue is addressed by combining experiments performed with an ultrafast ultrasound imaging system to track nonlinear shear waves(shear shock waves)in muscles in vivo and finite element analysis relying on a physically motivated constitutive model to study the effect of muscle activation level.Skeletal muscle was loaded with a deep muscle stimulator to generate shear shock waves(SSWs).The particle velocities,second and third harmonics,and group velocities of the SSWs in living muscles under both passive and active states were measured in vivo.Our experimental results reveal,for the first time,that muscle states have a pronounced effect on wave features;a low level of activation may facilitate the occurrence of both the second and third harmonics,whereas a high level of activation may inhibit the third harmonic.Finite element analysis was further carried out to quantitatively explore the effect of active muscle deformation behavior on the generation and propagation of SSWs.The simulation results at different muscle activation levels confirmed the experimental findings.The ability to reveal the effects of muscle state on the features of SSWs may be helpful in elucidating the unique dynamic deformation mechanism of living skeletal muscles,quantitatively characterizing diverse shock wave-based therapy instruments,and guiding the design of muscle-mimicking soft materials.展开更多
Iodine-131 is a highly toxic and volatile artificial radionuclide that is easily inhaled or ingested by the human body and selectively accumulates in thyroid tissue.With the development of nuclear medicine and nuclear...Iodine-131 is a highly toxic and volatile artificial radionuclide that is easily inhaled or ingested by the human body and selectively accumulates in thyroid tissue.With the development of nuclear medicine and nuclear power plants,the unintended release of ^(131)I has been widely studied,and the in vivo measurement of ^(131)I in the thyroid has become a research hotspot in the field of radiation protection.In recent decades,several methods and devices have been developed for in vivo measurements with respect to different measurement purposes and requirements.In this work,for more accurate determinations of individual ^(131)I in the thyroid in the field,the uncertainties of measurements by using portable gamma spectrometers were reviewed and analyzed,and monitoring strategies for improving the accuracy were proposed and prospected.展开更多
The significance and research status of tooth mobility (TM) measurement are introduced. There are many methods to measure the TM, but up to now no one does vivo dynamic TM measurement. An optical-electronic method is ...The significance and research status of tooth mobility (TM) measurement are introduced. There are many methods to measure the TM, but up to now no one does vivo dynamic TM measurement. An optical-electronic method is raised to measure it in this paper. The measurement theory is introduced and a measurement system is setup. Special proceeding is done for this measurement because of the small oral cavity measurement area. It is the first time to get vivo dynamic TM measurement result at last. The measurement result is analysed and a new movement period is discovered. It shows that this method satisfies for the dynamical tooth movement. Further research is suggested.展开更多
In vivo measurement of radioactivity based on various body counters is arguably the leading measure used to determine the distribution and activity of radionuclides in human subjects,such as I-131 in the thyroid,Am-24...In vivo measurement of radioactivity based on various body counters is arguably the leading measure used to determine the distribution and activity of radionuclides in human subjects,such as I-131 in the thyroid,Am-241 in the lungs,and Pb-210 in the skull.Throughout the measurements,the radiation background is the key factor that determines the sensitivity of the counter.Therefore,to facilitate in vivo measurements,a well-designed shielding room is required to create a low-background environment.However,because the compositions of the radiation background are quite complicated,the respective contributions from each source remain obscure,which places a considerable burden on seeking an optimized design of shielding rooms that strikes the optimum balance between the construction cost and background suppression effect.In this study,we conducted a systematic experimental investigation on the radiation background outside and inside four representative body counters with assorted designs using a variety of radiation detectors,including high-purity germanium detectors,CdZnTe detector,radon emanometer,and gamma-ray dosimeter.By carefully controlling the experimental conditions and synergetic analysis of the measurement results,in conjunction with previous studies,we separated and determined the relative contributions induced by environmental radiation(4%),airborne radon and its daughters(2%),the normal radioactivity of human subjects arising from K-40(58%),cosmic rays(12%),and radioactivity in shielding materials and measuring instruments(24%).Furthermore,based on these results,we discuss practical guidelines to design a shielding room for body counters.展开更多
目的:探讨枳实挥发油对慢传输型便秘(STC)大鼠的治疗作用及可能的作用机理。方法:应用盐酸吗啡制作STC模型大鼠,采用活性炭悬液推进法测定枳实挥发油干预前后大鼠肠道推进功能,并采用在体结肠肌电测定法测定枳实挥发油干预前后大鼠结肠...目的:探讨枳实挥发油对慢传输型便秘(STC)大鼠的治疗作用及可能的作用机理。方法:应用盐酸吗啡制作STC模型大鼠,采用活性炭悬液推进法测定枳实挥发油干预前后大鼠肠道推进功能,并采用在体结肠肌电测定法测定枳实挥发油干预前后大鼠结肠的肌电活动情况。结果:与模型对照组相比,枳实挥发油组STC大鼠肠道推进率增加(26.33±7.71%vs 19.74±3.94%,P<0.05),结肠慢波振幅减小、频率加快(0.35±0.05vs 0.43±0.05,8.38±0.96 vs 6.02±1.10,P<0.05),振幅及频率变异系数均减小(11.07±1.21 vs 12.27±1.51,16.35±3.25 vs 23.43±3.02,P<0.05)。结论:枳实挥发油可增强STC结肠推进功能,其治疗作用机制之一是纠正STC异常的结肠慢波,为其用于STC的治疗提供了一定的实验学参考。展开更多
基金supported by the National Students Training Program for Innovation(Grant No.202210007029)。
文摘How the state of living muscles modulates the features of nonlinear elastic waves generated by external dynamic loads remains unclear because of the challenge of directly observing and modeling nonlinear elastic waves in skeletal muscles in vivo,considering their active deformation behavior.Here,this important issue is addressed by combining experiments performed with an ultrafast ultrasound imaging system to track nonlinear shear waves(shear shock waves)in muscles in vivo and finite element analysis relying on a physically motivated constitutive model to study the effect of muscle activation level.Skeletal muscle was loaded with a deep muscle stimulator to generate shear shock waves(SSWs).The particle velocities,second and third harmonics,and group velocities of the SSWs in living muscles under both passive and active states were measured in vivo.Our experimental results reveal,for the first time,that muscle states have a pronounced effect on wave features;a low level of activation may facilitate the occurrence of both the second and third harmonics,whereas a high level of activation may inhibit the third harmonic.Finite element analysis was further carried out to quantitatively explore the effect of active muscle deformation behavior on the generation and propagation of SSWs.The simulation results at different muscle activation levels confirmed the experimental findings.The ability to reveal the effects of muscle state on the features of SSWs may be helpful in elucidating the unique dynamic deformation mechanism of living skeletal muscles,quantitatively characterizing diverse shock wave-based therapy instruments,and guiding the design of muscle-mimicking soft materials.
基金partially supported by the National Natural Science Foundation of China(No.11775053).
文摘Iodine-131 is a highly toxic and volatile artificial radionuclide that is easily inhaled or ingested by the human body and selectively accumulates in thyroid tissue.With the development of nuclear medicine and nuclear power plants,the unintended release of ^(131)I has been widely studied,and the in vivo measurement of ^(131)I in the thyroid has become a research hotspot in the field of radiation protection.In recent decades,several methods and devices have been developed for in vivo measurements with respect to different measurement purposes and requirements.In this work,for more accurate determinations of individual ^(131)I in the thyroid in the field,the uncertainties of measurements by using portable gamma spectrometers were reviewed and analyzed,and monitoring strategies for improving the accuracy were proposed and prospected.
基金The CAS fund for choosing excellent student abroad going back China to work(2 0 0 10 5 130 935 0 9)
文摘The significance and research status of tooth mobility (TM) measurement are introduced. There are many methods to measure the TM, but up to now no one does vivo dynamic TM measurement. An optical-electronic method is raised to measure it in this paper. The measurement theory is introduced and a measurement system is setup. Special proceeding is done for this measurement because of the small oral cavity measurement area. It is the first time to get vivo dynamic TM measurement result at last. The measurement result is analysed and a new movement period is discovered. It shows that this method satisfies for the dynamical tooth movement. Further research is suggested.
基金supported by the Central University Basic Scientific Research Business Expenses Special Funds under the project name Research on Applied Physics under Low 385 Radiation Background(No. 2018NTST07)2021 Nuclear and Radiation Safety Technic Evaluation Project,Ministry of Ecology and Environment (No.NSCCG2021-052)
文摘In vivo measurement of radioactivity based on various body counters is arguably the leading measure used to determine the distribution and activity of radionuclides in human subjects,such as I-131 in the thyroid,Am-241 in the lungs,and Pb-210 in the skull.Throughout the measurements,the radiation background is the key factor that determines the sensitivity of the counter.Therefore,to facilitate in vivo measurements,a well-designed shielding room is required to create a low-background environment.However,because the compositions of the radiation background are quite complicated,the respective contributions from each source remain obscure,which places a considerable burden on seeking an optimized design of shielding rooms that strikes the optimum balance between the construction cost and background suppression effect.In this study,we conducted a systematic experimental investigation on the radiation background outside and inside four representative body counters with assorted designs using a variety of radiation detectors,including high-purity germanium detectors,CdZnTe detector,radon emanometer,and gamma-ray dosimeter.By carefully controlling the experimental conditions and synergetic analysis of the measurement results,in conjunction with previous studies,we separated and determined the relative contributions induced by environmental radiation(4%),airborne radon and its daughters(2%),the normal radioactivity of human subjects arising from K-40(58%),cosmic rays(12%),and radioactivity in shielding materials and measuring instruments(24%).Furthermore,based on these results,we discuss practical guidelines to design a shielding room for body counters.
文摘目的:探讨枳实挥发油对慢传输型便秘(STC)大鼠的治疗作用及可能的作用机理。方法:应用盐酸吗啡制作STC模型大鼠,采用活性炭悬液推进法测定枳实挥发油干预前后大鼠肠道推进功能,并采用在体结肠肌电测定法测定枳实挥发油干预前后大鼠结肠的肌电活动情况。结果:与模型对照组相比,枳实挥发油组STC大鼠肠道推进率增加(26.33±7.71%vs 19.74±3.94%,P<0.05),结肠慢波振幅减小、频率加快(0.35±0.05vs 0.43±0.05,8.38±0.96 vs 6.02±1.10,P<0.05),振幅及频率变异系数均减小(11.07±1.21 vs 12.27±1.51,16.35±3.25 vs 23.43±3.02,P<0.05)。结论:枳实挥发油可增强STC结肠推进功能,其治疗作用机制之一是纠正STC异常的结肠慢波,为其用于STC的治疗提供了一定的实验学参考。
