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To carry out cell experiments for the pulsed magnetic field treatment of tumor cells, a high dB/dt pulsed magnetic field generator based on a printed circuit board (PCB) Archimedes spiral coil and a self-breakdown air switch is developed. The magnetic field and the induced electric field around the Archimedes spiral coil are calculated. Using COMSOL Multiphysics software, the magnetic field distribution characteristics of the coil are optimally designed. Then, the performance of the generator is measured. Ultimately, the PCB Archimedean spiral coil has seven turns, and it has a diameter of 21 mm. The coil can produce the following pulse magnetic field parameters in a cell culture liquid: an amplitude of 0.92 T, a rise time of 78 ns, a pulsewidth of 1.8 \mu \text{s} , a rate of magnetic field change that reaches 1.1\times 10^{7} T/s, a maximum-induced electric field of 55.9 kV/m, a degree of electric field uniformity of 84%, and a maximum-induced current density of 1.7 \times 10^4 A/ \textm^2 . The coil can be used to deliver pulsed magnetic field and induced electric field to biological objects. [ABSTRACT FROM AUTHOR]

Objective The application of picosecond pulsed electric field (psPEF) is a new biomedical engineering technique used in cancer therapy. However, its effects on cervical cancer angiogenesis are not clear. Therefore, the aim of the present study is to investigate the effects of psPEF on angiogenesis in cervical cancer xenograft models. Methods Xenograft tumors were created by subcutaneously inoculating nude mice (athymic BALB/c nu/nu mice) with HeLa cells, then were placed closely between tweezer-type plate electrodes and subjected to psPEF with a gradually increased electric field intensity (0 kV/cm, 50 kV/cm, 60 kV/cm, 70 kV/cm). The direct effect on tumor tissue was observed by hematoxylin and eosin (H&E) staining and transmission electron microscopy (TEM). The changes of blood vessels and oxygen saturation (sO 2 ) of tumors were monitored in vivo by photoacoustic tomography (PAT). The microvessel density (MVD), vascular endothelial growth factor (VEGF) and hypoxia-inducible transcription factors (HIF-1α and HIF-2α) were detected by immunohistochemical technique (IHC). Their protein expressions and gene transcription levels were evaluated using western blot (WB) and quantitative reverse transcription and polymerase chain reaction (RT-PCR). Results PsPEF induced obvious necrosis of cervical cancer tissue; with the increasing of electric field intensity, the MVD, vascular PA signal and sO 2 values declined significantly. The protein expression and gene transcription levels of VEGF, HIF1α and HIF2α were significantly decreased at the same time. Conclusion PsPEF exhibited dramatic anti-tumor and anti-angiogenesis effects in cervical cancer xenograft models by exerting direct effect on cancer cells and vascular endothelial cells and indirect effect on tumor angiogenesis-related factors. [ABSTRACT FROM AUTHOR]

Digital audio recording has become more prevalent than its analog predecessor. When a digital audio recording is presented as forensic evidence in legal proceedings, the party introducing it must show that it has not been altered since the time of its production. This kind of originality and integrity examination is a complex task in the field of forensic science and has become an important function of a forensic audio laboratory. [ABSTRACT FROM PUBLISHER]

From the microscopic electroporation to the irregular distribution of cell populations, the inactivation efficacy of pulsed electric fields (PEFs) from in vitro experiments has lacked a unified physical model due to its cross-scale complexity. Inspired by a coarse-grained approach from the percolation theory, the inactivation process is simulated from a simple yet robust lattice model, where the spatiotemporal heterogeneity of the collective structure and the stochastic PEF strike are portrayed as random matrices, while also accounting for the rules of single-cell electroporation and subsequent death. Beyond successfully simulating the inactivation of monolayer adherent cells and suspended cells, which are in good agreement with in vitro results, our model reveals that (1) macroscopically three-staged inactivation pattern originates from the "accelerate–uniform–decelerate" transition of inactivation velocity, and (2) the inactivation patterns obey a universal scaling law under varied field strength, which is not satisfied under varied pulsed widths. The simulation not only sheds light on the PEF inactivation of the macroscopic cell collectives but also provides a simple and generalized numerical method for predicting PEF efficacy in experiments or engineering. [ABSTRACT FROM AUTHOR]

Electroporation (i.e., reversible electrical breakdown) has been used for biomedicine such as electroporation therapy, transdermal drug delivery, cellular drug carrier systems, and gene transfer therapy. However,, little research on the biological effect of irreversible electrical breakdown has been published. In this paper, the Wiling and inhibiting effects of pulsed electric field, whose rising edge is 100 ns level (we call it steep pulsed electric field, SPEF), to target cancer cell and solid tumor were successfully observed. The SPEF consists of two parts: the rising process containing ample high-frequency components, and the falling process containing lots of low-frequency components. Cell exposed to the pulse presented multiple changes: destructed membrane, swollen nucleus, disintegrated. karyotheca, and cavitated, swollen' mitochondria in histological and ultrastructure observations. SPEF blocked cell transition from G0/G1 phase to S + G2/M phase in flow cytometry analysis, and tumor growth retardation was observed in tumor-bearing mice. These experimental results show SPEF have a certain function to generate irreversible electrical breakdown in tumor cells, and might provide a new promising therapeutic approach for tumor treatment. [ABSTRACT FROM AUTHOR]

The reactive species-independent nature of cold plasma's electric field is pivotal in biomedical applications. This work proposes to connect the plasma fluid model and the asymptotic Smoluchowski model for electroporation, providing a unified framework to investigate the evolution of the electric field in the biological substrate and the multi-stage electroporation response of the human cell. Two common substrates with distinct dielectric properties, namely, the cultivation medium and epidermis, are selected to report three stages of ionization wave (IW)–substrate interaction. The three-stage streamer discharge dynamics (restrike, axial-radial transition, and radial expansion of IW) induce three-stage cell electroporation dynamics (slow charging, fast charging, and electroporation), though the two processes are asynchronous. Specifically, the inner membrane covered the cell nucleus with ultra-short charging time that undergoes only the first two discharge stages in both substrates. Whether the cell membrane is exposed to the third stage of discharge depends on the permittivity of the substrate. The asynchrony can be attributed to the difference in the charging time of the cell membranes and substrates affected by the substrate permittivity. The presented model can provide quantitative insights into the cell electroporation induced by the IW–substrate interaction and theoretical guidance for plasma biomedical applications. [ABSTRACT FROM AUTHOR]

In the irreversible electroporation (IRE) therapy, the absorbed energy is normally characterized as the applied dose and assumed to be distributed in the homogeneous dielectric. By employing statistical analyses, we have studied the absorbed energy distribution in the porous multicellular dielectric, with the geometric patterns randomly generated from the following statistical quantities: system size, cell size, cell concentration, and cell flattening ratio. Parametric formulas regarding the mean and standard deviation of the absorbed energy are obtained through numerical simulations and iterative fitting. Our statistical results reveal that the mean value of absorbed energy with cell concentration exhibits a "conductance" to "resistance" transition, similar to the percolation of two-phase materials, and the direction of the transition flips as cell diameter increases. The standard deviation of energy, however, follows a bell-shaped curve under varied concentration, indicating a shift in energy distribution from an "aggregation" to a "dispersion" state. Based on the parametric formulation, we quantitatively explore the critical threshold of the transition, as well as the general scaling laws of the geometric variables on the mean and standard deviation of the absorbed energy. Our work could help to quantitatively explain the lethality variation in IRE ablation targeting monolayer cell collectives with different geometrical characteristics. [ABSTRACT FROM AUTHOR]

• Cellular morphology influences electroporation induced by µs-PEFs. • ns pulses target the nuclear membrane and are not affected by cell irregularity. • ns + µs pulses enhance the destruction of nuclear and cell membranes. The decrease in killing sensitivity of the cell membrane to microsecond pulse electric fields (μs-PEFs) is ascribed mainly to the aberrant morphology of cancer cells, with clear statistical correlations observed between cell size and shape defects and the worsening of the electrical response to the PEF. In this paper, nanosecond pulsed electric fields (ns-PEFs) inducing the nucleus effect and μs-PEFs targeting the cell membrane were combined to enhance destruction of irregular cells. The fluorescence dissipation levels of the nuclear membrane and cell membrane exposed to the μs, ns, and ns + μs pulse protocols were measured and compared, and a dynamic electroporation model of irregular cells was established by the finite element software COMSOL. The results suggest that the cell membrane disruption induced by μs-PEFs is worse for extremely irregular cells and depends strongly on cellular morphology. However, the nuclear membrane disruption induced by ns-PEFs does not scale with irregularity, suggesting the use of a combination of ns-PEFs with μs-PEFs to target the nuclear and cell membranes. We demonstrate that ns + μs pulses can significantly enhance the fluorescence dissipation of the cell and nuclear membranes. Overall, our findings indicate that ns + μs pulses may be useful in the effective killing of irregular cells. [ABSTRACT FROM AUTHOR]