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Electrical stimulation therapy has attracted widespread attention for its advantages of promoting cell proliferation and tissue regeneration, accelerating skin barrier restoration, and reducing scars. Its effect on accelerating wound healing has been clinically proven. However, traditional electrical stimulation therapy requires large power supply devices, which are inconvenient to carry and use. Therefore, self-powered flexible nano-piezoelectric membranes were developed in this work, which can generate electric field under mechanical stimulation to effectively eliminate bacteria and accelerate wound healing. In this work, poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) piezoelectric membranes were fabricated by electrospinning, and better piezoelectric properties were obtained by adding tetrabutylammonium chloride (TBAC), and their antibacterial and pro-healing effects were investigated with or without mechanical stimulation. Results showed that the output voltage of P(VDF-TrFE)/TBAC piezoelectric membrane was about 5.3 times higher than that of P(VDF-TrFE). Furthermore, the P(VDF-TrFE)/TBAC piezoelectric membrane had excellent antibacterial effect against both Escherichia coli and Staphylococcus aureus after mechanical stimulation, and the inhibition rates of Staphylococcus aureus and Escherichia coli were 71.43% and 97.25%, respectively. Meanwhile, the results of in vivo and in vitro healing promotion experiments showed that P(VDF-TrFE)/TBAC piezoelectric membrane was effective in promoting cell growth and wound healing after mechanical stimulation, the wound was almost completely healed on the 7th day, and the healing rate was increased by about 37% compared with the blank. The P(VDF-TrFE)/TBAC flexible piezoelectric membrane is effective in electrical stimulation for wound healing, and it has potential applications in wound treatment. [ABSTRACT FROM AUTHOR]

In this study, the air gap magnetic field characteristics of external rotor permanent magnet synchronous motors (PMSMs) under both the stator and rotor coordinate systems considering low‐order current harmonics and high‐order sideband current harmonics are analysed. A direct measurement technique (DMT) for air‐gap magnetic field is proposed. First, an analytical model of air gap magnetic field of external rotor PMSMs is established. The spatial order and frequency characteristics of stator/rotor air gap magnetic field are revealed. Then, a 24‐pole 27‐slot external rotor PMSM is taken as an example. The analytical and finite element (FE) results are compared and analysed. The difference of the spatial order and frequency characteristics between the stator and rotor air gap magnetic field are verified. Next, a new DMT is proposed, which can detect the precise distribution and local microscopic characteristics on the order of 10−1 mm with high resolution. The accuracy of analytical and FE model are verified by the DMT and an indirect experimental test of no‐load back electromotive force. Finally, the mechanical challenges of in‐wheel motors and the practicablility of DMT for eccentricity detection are further discussed. [ABSTRACT FROM AUTHOR]

Creating a fluidic system with an induced electrical field is regarded as an innovative, eco-friendly practice for the hydrolysis of lignocellulosic biomass at mild conditions. A multi-series, reconfigurable fluidic reactor was developed based on the transformer concept for the efficient hydrolysis of sugarcane bagasse via the interconversion of magnetic and electrical energy. A secondary coil comprised of a mixture of sulfuric acid (or other metal electrolyte) and the sample in continuous flow was exposed to an induced electric field at 400–700 Hz to accelerate the hydrolysis. The results showed that using an induced electric field to assist hydrolysis is indeed beneficial in the production of reducing sugar (RS). The total reducing sugar (TRS) yield is positively impacted by the excitation voltage but is negatively impacted by voltage frequency and the sample solution impedance. The hydrolysis efficiency improves as the number of reactors increases in both series and parallel modes of the system. The mode of connection of the reactors has varying effect on the TRS yield owing to differences in the equivalent impedance, output power, and load power factor. Increased number of secondary coil turns also improves hydrolysis efficiency under the same input power and primary coil turns and thus increasing the TRS yield. Induced-electric-field-assisted hydrolysis (IEFAH) substantially enhances the yield (by 756% approximately, at 300 V, 400 Hz in a 4-series reactors for 24 h) compared to continuous flow heating hydrolysis (CFHH) at mild conditions (50 °C and 1% H 2 SO 4 ). The proposed fluidic system combined with an induced electric field shows remarkable potential as a green technology for the efficient hydrolysis of lignocellulosic biomasses without the use of metal electrodes. [ABSTRACT FROM AUTHOR]

As an emerging electrotechnology, induced electric field has attracted extensive attention in the development of innovative heat treatment equipment. In this study, a resistance heating unit based on induced electric field was built for inner heating of aqueous electrolyte solutions as well as liquid foods, such as vinegar. NaCl solutions and liquid foods with different conductivity were used to investigate the thermal effect and temperature rise of samples. Saline gel composed of 3% agar powder and 20% NaCl acted as a coil of conductor for inducing high-level output voltage. The utilization of the saline gel coil significantly improved the power conversion efficiency of the heating unit as well as the heating rate. The results revealed that duty cycle and applied frequency had immediate impact on the efficiency of inner heating. Additionally, the rate of temperature rise was proportional to the conductivity of the sample. The temperature of 200 mL NaCl solution (0.6%) increased from 25 °C to 100 °C in 3 min at 40% duty cycle and 60 kHz of applied frequency, and it was a circulating-flow process. The maximum temperature rise of black vinegar was 39.6 °C in 15 s at 60 kHz and 60% duty cycle, while that of white vinegar was 32.2 °C in 30 s under same conditions, whereas it was a continuous-flow process. This novel heating system has realized the inner heating of liquid samples. [ABSTRACT FROM AUTHOR]