Alkaline phosphatase(ALP) plays an integral role in the metabolism of liver and development of the skeleton in humans. To date, the interactions between different-duration terahertz(THz) radiation and ALP activities, ...Alkaline phosphatase(ALP) plays an integral role in the metabolism of liver and development of the skeleton in humans. To date, the interactions between different-duration terahertz(THz) radiation and ALP activities, as well as the influence mechanism are still unclear. In this study, using the para-nitro-phenyl-phosphate(p NPP) method, we detect changes in ALP activities during 40-minute THz radiation(0.1 THz, 13 m W/cm^2). It is found that the activity of ALP decreases in the first 25 min, and subsequently increases in the later 15 min. Compared with the activity of ALP being heated, the results suggest that short-term terahertz radiation induces a decrease in enzyme activity through the non-thermal mechanism. In order to explore the non-thermal effects of THz radiation on ALP, we focus on the impacts of 0.1 THz radiation for 20 min on the activity of ALP in different concentrations. The results reveal that the activity of ALP decreases significantly after exposure to THz radiation. In addition, it could be deduced from fluorescence, ultraviolet-visible(UV-vis), and THz spectra results that THz radiation has induced changes in ALP structures. Our study unlocks non-thermal interactions between THz radiation and ALP, as well as suggests that THz spectroscopy is a promising technique to distinguish ALP structures.展开更多
The undulator is the key component in the compact THz radiation source based on FEL.By matching the adjustable period magnetic field of the undulator with the optical resonance cavity,the passing electron beam will ge...The undulator is the key component in the compact THz radiation source based on FEL.By matching the adjustable period magnetic field of the undulator with the optical resonance cavity,the passing electron beam will generate coherent radiation with gain,and the radiation power required by THz source can be achieved finally. Compared with the pure permanent magnet type,the hybrid type undulator can decrease the field errors caused by non-homogeneous magnetization of magnetic blocks,and provide higher magnetic field.The conceptual design of a hybrid undulator used for THz radiation source is introduced.We use the FEM code OPERA/TOSCA to simulate 3D magnetic field of the undulator.After optimizing the end structure of the hybrid undulator,the first field integrals is controlled within 0.01Gs.m,and the deviation of the electron beam is less than 0.02mm.展开更多
Analytical equations of terahertz(THz)radiation generation based on beating of two laser beams in a warm collisional magnetized plasma with a ripple density profile are developed.In this regard,the effects of frequenc...Analytical equations of terahertz(THz)radiation generation based on beating of two laser beams in a warm collisional magnetized plasma with a ripple density profile are developed.In this regard,the effects of frequency chirp on the field amplitude of the terahertz radiation as well as the temperature and collision parameters are investigated.The ponderomotive force is generated in the frequency chirp of beams.Resonant excitation depends on tuning of the plasma beat frequency,magnetic field frequency,thermal velocity,collisional frequency,and effect of the frequency chirp with the plasma density.For optimum parameters of frequency and temperature the maximum THz amplitude is obtained.展开更多
Recently a lot of medical tablets with special packets in the global market are available. For the safety and purity of the tablet, we need to scan it by developed scanner technology, which should be not more expensiv...Recently a lot of medical tablets with special packets in the global market are available. For the safety and purity of the tablet, we need to scan it by developed scanner technology, which should be not more expensive and easily available in the market. The THz technology is one of them. In the proposed work, we have tasted tablet images with the help of the THz super-resolution scanner, which is already available in our lab. The AI machine learning data concept has been investigated. Good resolution of images has been obtained. Furthermore, the challenging research problems are discussed. Finally, it summarizes the recent updates in terahertz technology for drug inspection and medical applications with potential research challenges.展开更多
Emission of THz radiation from air breakdown at focused ultra-short fs-laser pulses(800 nm/35 fs)was investigated for the 3D spatio-temporal control where two pre-pulses are used before the main-pulse.The laser pulse ...Emission of THz radiation from air breakdown at focused ultra-short fs-laser pulses(800 nm/35 fs)was investigated for the 3D spatio-temporal control where two pre-pulses are used before the main-pulse.The laser pulse induced air breakdown forms a~120μm-long focal volume generate shockwaves which deliver a denser air into the focal region of the main pulse for enhanced generation of THz radiation at 0.1-2.5 THz spectral window.The intensity of 162 pre-and main-pulses was at the tunnelling ionisation intensities(1-3)×10 W/cm and corresponded to sub-critical(transparent)plasma formation in air.Polarisation analysis of THz radiation revealed that orientation of the air density gradients generated by pre-pulses and their time-position locations defined the ellipticity of the generated THz electrical field.The rotational component of electric current is the origin of THz radiation.展开更多
The instability of terahertz（THz）plasma waves in two-dimensional（2D）quantum electron gas in a nanometer field effect transistor（FET）with asymmetrical boundary conditions has been investigated.We analyze THz plas...The instability of terahertz（THz）plasma waves in two-dimensional（2D）quantum electron gas in a nanometer field effect transistor（FET）with asymmetrical boundary conditions has been investigated.We analyze THz plasma waves of two parts of the 2D quantum electron gas：gated and ungated regions.The results show that the radiation frequency and the increment（radiation power）in 2D ungated quantum electron gas are much higher than that in 2D gated quantum electron gas.The quantum effects always enhance the radiation power and enlarge the region of instability in both cases.This allows us to conclude that 2D quantum electron gas in the transistor channel is important for the emission and detection process and both gated and ungated parts take part in that process.展开更多
Strong terahertz(THz)radiation provides a powerful tool to manipulate and control complex condensed matter systems.This review provides an overview of progress in the generation,detection,and applications of intense T...Strong terahertz(THz)radiation provides a powerful tool to manipulate and control complex condensed matter systems.This review provides an overview of progress in the generation,detection,and applications of intense THz radiation.The tabletop intense THz sources based on Ti:sapphire laser are reviewed,including photoconductive antennas(PCAs),optical rectification sources,plasma-based THz sources,and some novel techniques for THz generations,such as topological insulators,spintronic materials,and metasurfaces.The coherent THz detection methods are summarized,and their limitations for intense THz detection are analyzed.Applications of intense THz radiation are introduced,including applications in spectroscopy detection,nonlinear effects,and switching of coherent magnons.The review is concluded with a short perspective on the generation and applications of intense THz radiation.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61675151)
文摘Alkaline phosphatase(ALP) plays an integral role in the metabolism of liver and development of the skeleton in humans. To date, the interactions between different-duration terahertz(THz) radiation and ALP activities, as well as the influence mechanism are still unclear. In this study, using the para-nitro-phenyl-phosphate(p NPP) method, we detect changes in ALP activities during 40-minute THz radiation(0.1 THz, 13 m W/cm^2). It is found that the activity of ALP decreases in the first 25 min, and subsequently increases in the later 15 min. Compared with the activity of ALP being heated, the results suggest that short-term terahertz radiation induces a decrease in enzyme activity through the non-thermal mechanism. In order to explore the non-thermal effects of THz radiation on ALP, we focus on the impacts of 0.1 THz radiation for 20 min on the activity of ALP in different concentrations. The results reveal that the activity of ALP decreases significantly after exposure to THz radiation. In addition, it could be deduced from fluorescence, ultraviolet-visible(UV-vis), and THz spectra results that THz radiation has induced changes in ALP structures. Our study unlocks non-thermal interactions between THz radiation and ALP, as well as suggests that THz spectroscopy is a promising technique to distinguish ALP structures.
文摘The undulator is the key component in the compact THz radiation source based on FEL.By matching the adjustable period magnetic field of the undulator with the optical resonance cavity,the passing electron beam will generate coherent radiation with gain,and the radiation power required by THz source can be achieved finally. Compared with the pure permanent magnet type,the hybrid type undulator can decrease the field errors caused by non-homogeneous magnetization of magnetic blocks,and provide higher magnetic field.The conceptual design of a hybrid undulator used for THz radiation source is introduced.We use the FEM code OPERA/TOSCA to simulate 3D magnetic field of the undulator.After optimizing the end structure of the hybrid undulator,the first field integrals is controlled within 0.01Gs.m,and the deviation of the electron beam is less than 0.02mm.
文摘Analytical equations of terahertz(THz)radiation generation based on beating of two laser beams in a warm collisional magnetized plasma with a ripple density profile are developed.In this regard,the effects of frequency chirp on the field amplitude of the terahertz radiation as well as the temperature and collision parameters are investigated.The ponderomotive force is generated in the frequency chirp of beams.Resonant excitation depends on tuning of the plasma beat frequency,magnetic field frequency,thermal velocity,collisional frequency,and effect of the frequency chirp with the plasma density.For optimum parameters of frequency and temperature the maximum THz amplitude is obtained.
文摘Recently a lot of medical tablets with special packets in the global market are available. For the safety and purity of the tablet, we need to scan it by developed scanner technology, which should be not more expensive and easily available in the market. The THz technology is one of them. In the proposed work, we have tasted tablet images with the help of the THz super-resolution scanner, which is already available in our lab. The AI machine learning data concept has been investigated. Good resolution of images has been obtained. Furthermore, the challenging research problems are discussed. Finally, it summarizes the recent updates in terahertz technology for drug inspection and medical applications with potential research challenges.
基金funded by programs 107-2112-M-001-014-MY3,110-2112-M-001-054(K.H.and H-H.H.)partly funded by the Australian Research Council Linkage LP 220100153 grant(S.J.).We are grateful to Prof.Eugene G.Gamaly for the critical comments.
文摘Emission of THz radiation from air breakdown at focused ultra-short fs-laser pulses(800 nm/35 fs)was investigated for the 3D spatio-temporal control where two pre-pulses are used before the main-pulse.The laser pulse induced air breakdown forms a~120μm-long focal volume generate shockwaves which deliver a denser air into the focal region of the main pulse for enhanced generation of THz radiation at 0.1-2.5 THz spectral window.The intensity of 162 pre-and main-pulses was at the tunnelling ionisation intensities(1-3)×10 W/cm and corresponded to sub-critical(transparent)plasma formation in air.Polarisation analysis of THz radiation revealed that orientation of the air density gradients generated by pre-pulses and their time-position locations defined the ellipticity of the generated THz electrical field.The rotational component of electric current is the origin of THz radiation.
基金supported by National Natural Science Foundation of China(No.10975114)
文摘The instability of terahertz（THz）plasma waves in two-dimensional（2D）quantum electron gas in a nanometer field effect transistor（FET）with asymmetrical boundary conditions has been investigated.We analyze THz plasma waves of two parts of the 2D quantum electron gas：gated and ungated regions.The results show that the radiation frequency and the increment（radiation power）in 2D ungated quantum electron gas are much higher than that in 2D gated quantum electron gas.The quantum effects always enhance the radiation power and enlarge the region of instability in both cases.This allows us to conclude that 2D quantum electron gas in the transistor channel is important for the emission and detection process and both gated and ungated parts take part in that process.
基金This work was supported by the National Key R&D Program of China(No.2019YFC1711905)the National Natural Science Foundation of China(Grant Nos.11774243,11774246,and 6167513)+2 种基金the Youth Innovative Research Team of Capital Normal University(No.19530050146)the Capacity Building for Science&Technology Innovation Fundamental Scientific Research Funds(Nos.19530050170 and 19530050180)the Scientific Research Base Development Program of the Beijing Municipal Commission of Education.
文摘Strong terahertz(THz)radiation provides a powerful tool to manipulate and control complex condensed matter systems.This review provides an overview of progress in the generation,detection,and applications of intense THz radiation.The tabletop intense THz sources based on Ti:sapphire laser are reviewed,including photoconductive antennas(PCAs),optical rectification sources,plasma-based THz sources,and some novel techniques for THz generations,such as topological insulators,spintronic materials,and metasurfaces.The coherent THz detection methods are summarized,and their limitations for intense THz detection are analyzed.Applications of intense THz radiation are introduced,including applications in spectroscopy detection,nonlinear effects,and switching of coherent magnons.The review is concluded with a short perspective on the generation and applications of intense THz radiation.
