Non-thermal tumor ablation technology based on short pulse strong electric field can overcome the defects of thermal ablation and cryoablation, which provides a new opportunity for the development of tumor therapy. In this study, the CAEP terahertz free electron laser facility was preliminarily used to do the research on non-thermal tumor ablation method because of its unique macro-micro pulse time series. The biological effects of short pulse strong field terahertz radiation on melanoma cells and tissues were studied in vitro and in vivo. In vitro experiments show that the survival rate of tumor cells is significantly different after being irradiated by different frequency, power, and radiation duration of terahertz wave. Strong field terahertz wave can inhibit the proliferation of tumor cells. In vivo experiments showed that compared with the control group, the tumor tissue proliferation of the irradiated experimental group was slowed down, the tumor volume was gradually reduced, and the strong field terahertz pulses could inhibit the growth of tumor tissue. These preliminary results will provide a feasible reference for further research and long-term clinical application.
In this paper, an inverse neural network based on deep learning is constructed to predict the metasurface structure of the designed terahertz metagrating. The transmittance spectra results from the numerical simulation of the metagrating were used as the input datasets for the inverse neural network, and the output is the corresponding metagrating structure parameters. After training, our inverse network can meet our expectations. The results show that some of the structural parameters predicted by the network are roughly consistent with the actual structural parameters, which indicates that the neural network can predict the corresponding structural parameters by given spectra. This has great application value, for example, it can be used to guide the design of metasurfaces for faster and more convenient purposes.
Spinel ferrite has the excellent characteristics of high saturation magnetization, high resistivity and low dielectric loss. It plays an important role in signal isolation, circulation, phase shift, frequency limiting, filtering, delay and amplification. So it is of great significance to study the spectral characteristics of spinel ferrite at different temperatures by using terahertz time-domain spectroscopy. The terahertz spectral characteristics of spinel ferrite under the different temperature condition were measured by terahertz time domain spectroscopy system. The transmittance of the power, absorption rate, absorption coefficient and refractive index of spinel ferrite were obtained by calculation. The experimental results show that the transmittance is positively correlated with temperature and the absorption spectrum of the samples increases with the increase of frequency in the 0-1THz band, and the refractive index of spinel ferrite increases with the increase of temperature.
Terahertz waves have potential of non-thermal regulation of cell physiological activities. Especially, the non-thermal effects of strong field terahertz pulses on the physical and chemical properties of cells and membrane structure need to be studied in detail. Therefore, this article uses the finite element method (FEM) to simulate and study the effects of strong field terahertz pulses on the cell membrane and nucleus membrane of cells. The simulation results show that both the single-frequency terahertz wave generated by CTFEL and wide-band terahertz pulses generated by lithium niobate crystal could cause a huge potential difference between cell membrane and nucleus membrane of the suspended spherical cell, which might lead to electroporation of the cell membrane or nucleus membrane.
In current particle-in-cell (PIC) simulation software, the most important parts are several key technologies. In this paper,
we discuss some technologies based on Yee-grid model and time-leapfrog model. Firstly, we induce 3-D electromagnetic
discrete algorithm formulae, which include the centered-difference algorithm formulae, time-biased algorithm formulae
and high-Q algorithm formulae. The application range of these electromagnetic discrete algorithms is also analyzed.
Secondly, we discuss the phenomenological description technology used in emission simulations and induce the
formulae which represent how to set the charge of macro particles in explosive emission. The charge-conserving
algorithm used to calculate current which is produced by the particle moving and the weight algorithm used to calculate
Lorentz force are also discussed. Thirdly, the ways to realize the common boundary conditions including the ideal
conductor, port boundary, absorption boundaries and metal strut are discussed. The way to calculate the absorption
coefficient of the absorption boundary is described in detail. The formulae of the metal strut's current and inductance
under two-dimensional and three-dimensional coordinates in different orientation in space are induced and realized using finite-difference time-domain (FDTD) method. Then, the iterative process under main FDTD iteration of metal strut is given. At last, the correctness of these technologies is proved by computer simulation on the Vavilov-Cherenkov radiation (VCR) in 2-D photonic crystal. The results show that the THz radiation is excited by electron bunches in photonic crystal.
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