We theoretically investigated the generation progress of high-order harmonics utilizing Bohmian trajectories, which are calculated from the accurate numerical wave function. It is found that the harmonic emission spectrum from atoms in an intense laser field calculated by Bohmian trajectories agrees well with that found by numerically solving the time-dependent Schrödinger equation. Through the analysis of the dynamic behavior of Bohmian trajectories, we investigated the ionization process, the acceleration of the ionized electron in the laser field, and its recollision with the parent ion in the progress. Furthermore, the individual behavior and the coherent contribution of these trajectories to the harmonic emission are discussed.

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Abstract. Traditional Chinese medicine (TCM) is important in the provision of anti-tumor drugs. Recently, studies have shown that certain types of TCM agents are able to control the growth of tumors, enhance the body's immune function and enhance the therapeutic effect of chemotherapeutic drugs. In women, breast carcinoma is the most common tumor type and the second most common cause of death from cancer. Polygonatum odoratum (P. odoratum) is commonly used in TCM. The aim of the present study was to investigate the effects of P. odoratum extract on the proliferation and apoptosis of MDA-MB-231 breast cancer cells. Cell proliferation was assessed using MTT and colony formation assays. In addition, propidium iodide (PI)/Annexin V-FITC staining was used to investigate the apoptosis of MDA-MB-231 cells following treatment with P. odoratum extract. The protein expression levels of B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax) were also detected using western blot analysis, while a JC-1 staining assay was used to assess the mitochondrial membrane potential (ΔΨm). The results of the MTT assay showed that the proliferation and colony formation of MDA-MB-231 cells were inhibited following treatment with the extract. Furthermore, the PI/Annexin-V staining showed that the apoptosis of MDA-MB-231 cells was enhanced by the extract, in a concentration-dependent manner. The extract also lowered the ΔΨm of MDA-MB-231 cells, upregulated the expression of Bax and inhibited the expression of Bcl-2. In conclusion, these results showed that the P. odoratum extract inhibited the proliferation and induced apoptosis of breast cancer MDA-MB-231 cells.

In vivo studies of tumor-cell apoptosis induced by nanosecond pulsed electric field require high-voltage nanosecond pulses delivered to the biological tissues. In this paper, a newly developed all-solid-state nanosecond pulse generator based on the Marx generator concept is proposed for this application. The generator comprises four parts: a dc charging power, a solid-state Marx circuit using metal-oxide-semiconductor field-effect transistors, a control circuit using a field-programmable gate array, and the load. This generator has the capability of producing repetitive pulses with a voltage up to 8 kV, pulsewidth of 200-1000 ns, rise time of 35 ns, and repetition rate of 1-1000 Hz with various resistive loads and 1-kV dc input voltage. The all-solid-state design makes the generator compact and reliable. Initial experiments were carried out to verify the performances of the proposed generator.Index Terms-All-solid state, control, field-programmable gate array (FPGA), Marx circuit, nanosecond pulsed electric field (nsPEF), pulse generator.