The recent rapid growth of the semiconductor industry in development of high power microwave source has open a new promising avenue by full electronic control over the electromagnetic field towards improve the microwave heating performance. In this paper, a coupled electromagnetic and heat transfer model was built to simulate microwave heating of multiple chicken blocks with temperature-dependent dielectric properties dependent on a solid-state microwave oven. Owing to the ability of solid-state source to precisely control the frequency, the temperature distribution simulated for the fixed frequency was compared with different frequency-shifted rates increasing process and decreacsing process between 2.4GHz and 2.5GHz. The simulated temperature distribution was validated by comparing with experimental temperature profiles obtained using a thermal imaging camera at the end of microwave heating. The results demonstrated the heating uniformity and efficiency is highly influenced by the head and tail frequency but also the frequency shifted rate. And a specific frequency-shifted rate decreasing process between 2.4GHz and 2.5GHz was proposed in improving the heating performance.
This paper simulates Ca2+ transmembrane transport through voltage-gated Ca2+ channels in response to terahertz electromagnetic irradiation. The active transport of Ca2+ ions is taken into considerations in the Ca2+ transport. Temperature variations due to terahertz electromagnetic loss in physiological medium are simulated. The electromagnetic interaction between terahertz fields and physiological mobile ions at the cellular level is deduced from relativistic electrodynamics. It shows that effects of 0.1 ~ 3 THz electromagnetic fields on cell mobile ions are primarily due to effects of electric fields, and effects of magnetic fields at the cellular level are insignificant. In addition, numerical simulation reveals that terahertz irradiation causes vibration of membrane potential, which is able to activate voltage-gated Ca2+ channels. Besides, bioeffects of terahertz frequency, irradiation duration and electric intensity on the increment of intracellular Ca2+ concentration due to activation of voltage-gated Ca2+ channels are revealed. Meanwhile, numerical results show that temperature rises are inconsequential in the case of different irradiation parameters, indicating the non-thermal bioeffects of voltage-gated Ca2+ transmembrane transport due to terahertz irradiation. Furthermore, the results also reveal that thermal bioeffect can be significant if the irradiation duration is raised long enough for high-dose terahertz irradiation. The numerical simulations lay the basis for understanding the bioeffects of terahertz irradiation on Ca2+ transmembrane transport and pave the way for further exploration in modulation of intracellular Ca2+ concentration with terahertz electromagnetic wave.
In this paper, we performed and designed a new rectangular cavity to identify and analyze the complex permittivity of two cancer cells (Breast-MDA231, Uveal melanoma) that have a high dielectric constant and dielectric loss. The rectangular cavity device is based on the improved cavity perturbation technology. The sample of the improved cavity perturbation device is placed at the position of a/n close to the wall of the cavity, where a is the wide side of the cavity and n is the positive even number. For high-loss biological materials, the improved cavity perturbation method has higher accuracy than the traditional cavity perturbation method. The results present that the relative dielectric constants of a single cell at Ka-band (26.5–40 GHz) are in the range 8–15, and the relative dielectric loss is 24–31. The information of the cancer cells at Ka-band waves can be helpful for further cancer detection and clinical treatment.
26 February 2017 in Microwave and Optical Technology Letters
Local oriented intense electric fields play a vital role in biochemical reactions such as enzyme catalysis. Many researchers have gradually applied external oriented electric fields to control specific chemical reactions. The rapidly developing intense field of terahertz technology can provide a strong enough oriented electric field with specific polarization direction on a sub-picosecond timescale, which matches the timescale and intensity requirements for affecting specific ultrafast chemical reactions. Inspired by this, this paper theoretically studied the full quantum model of the proton transfer process in DNA base pair hydrogen bonds induced by intense terahertz radiation (ITR) with a sub-picosecond-oriented electric field through simulation based on density functional theory (DFT) and the Schrodinger equation. The result shows that the ITR with an electric field intensity up to 10 GV m−1 in a specific polarization direction can precisely control the proton transfer process in the base pair hydrogen bonds. Based on flexible optical methods, the ITR is expected to go beyond the traditional techniques for applying strong electric fields to chemical systems through solid electrodes and become a catalyst for controlling chemical reactions or a scalpel to manipulate molecular structures.