Search

The mechanism of biological effects of environmental electromagnetic radiation is still not completely clear. The chelation of biological small molecule peptides with metal ions plays a very important role in human metabolism. In this paper, a special experimental system was designed to measure the conductivity of carnosine and zinc chloride mixed aqueous solutions under different concentration ratios, microwave powers, and temperatures. The experimental results show that, first, different concentration ratios can alter the conductivity change rate of the mixed aqueous solution. The conductivity of the solution always increases under microwave irradiation at a concentration ratio of 1:1. However, the conductivity is reduced by −0.04% with a 1:5 concentration ratio and 6 W microwave power at 10 °C. Second, temperature can alter the conductivity change rate of the aqueous mixture. The higher the temperature, the smaller the conductivity change rate. Third, different microwave powers can alter the conductivity change rate of the mixed aqueous solution. In general, the conductivity change rate increases with an increase in microwave power. Experimentally observed reduction of the conductivity change rate in carnosine and zinc chloride aqueous solution under low microwave power and low temperature indicates that microwaves do affect the chelation of carnosine with zinc chloride. This work provides a new perspective for the mechanism of explanation of microwave biological effects.

This article introduces a polarization-insensitive rectifying surface for 2.4 GHz WLAN band RF energy harvesting. The unit cell of the rectifying surface is formed by combining an interdigital structure with a square ring structure, optimized for high RF harvest efficiency over a wide band. For optimal performance, our design employs a direct matching of the Schottky diodes to the rectifying surface, minimizing signal loss and enhancing rectification effectiveness. To demonstrate the concept, a $4\times 4$ element rectifying surface array was fabricated and measured, yielding a total efficiency of 21% at an incident power density of $2.62~\mu $ W/cm2. The measured total efficiency remains higher than 18.9% over the 2.4–2.57 GHz range, covering the 2.4 GHz WLAN band. Furthermore, the total efficiency remains constant despite variations in the polarization angle of the incident wave. Our design demonstrates a highly efficient rectifying surface for harvesting low-power energy within the 2.4 GHz WLAN band, offering a promising solution for powering wireless devices.

Microwave heating is a promising technology widely used to enhance chemical processes in multiphase catalytic reactions. The design of the microwave reactor is crucial for microwave-assisted multiphase catalysis. However, assessing the reactor design’s impact on catalytic performance is often based on experiments and experience. In this study, we propose a method based on multiphysics simulation to evaluate and guide the design and scale-up of microwave cavities. First, we conduct multiphysics calculations by establishing an enlarged microwave reactor model to obtain the heating situation and gas flow stats on the catalyst support. Subsequently, by integrating parameters such as flow rate, temperature, and effectiveness, we construct the effective flow coefficient (EFC) to characterize and guide the reactor’s design quantitatively. Based on this method, we calculated four reactor models with different internal structures and obtained EFC values of 0.17, 0.19, 0.1, and 0.69, respectively. The results show that this method can quantitatively guide and optimize the reactor design from aspects such as the reactor structure, catalyst support structure, reactant feed configuration, and microwave feed configuration. This study contributes to the promotion of scale-up in microwave-assisted gas–solid catalytic reactors.