In Vitro Antiviral Activity of a New Indol-3-carboxylic Acid Derivative Against SARS-CoV-2.

The coronavirus disease (COVID-19) pandemic has brought into sharp relief the threat posed by coronaviruses and laid the foundation for a fundamental analysis of this viral family, as well as a search for effective anti-COVID drugs. Work is underway to update existent vaccines against COVID-19, and screening for low-molecular-weight anti-COVID drug candidates for outpatient medicine continues. The opportunities and ways to accelerate the development of antiviral drugs against other pathogens are being discussed in the context of preparing for the next pandemic. In 2012-2015, Tsyshkova et al. synthesized a group of water-soluble low-molecular-weight compounds exhibiting an antiviral activity, whose chemical structure was similar to that of arbidol. Among those, there were a number of water-soluble compounds based on 5-methoxyindole-3-carboxylic acid aminoalkyl esters. Only one member of this rather extensive group of compounds, dihydrochloride of 6-bromo-5-methoxy-1-methyl-2-(1-piperidinomethyl)-3-(2-diethylaminoethoxy) carbonylindole, exhibited a reliable antiviral effect against SARS-CoV-2 in vitro. At a concentration of 52.0 µM, this compound completely inhibited the replication of the SARS-CoV-2 virus with an infectious activity of 106 TCID50/mL. The concentration curves of the analyzed compound indicate the specificity of its action. Interferon-inducing activity, as well as suppression of syncytium formation induced by the spike protein (S-glycoprotein) of SARS-CoV-2 by 89%, were also revealed. In view of its synthetic accessibility - high activity (IC50 = 1.06 µg/mL) and high selectivity index (SI = 78.6) - this compound appears to meets the requirements for the development of antiviral drugs for COVID-19 prevention and treatment.

Picosecond solid-state generator with a peak power of 50 GW.

This article describes a picosecond solid-state pulsed system, where the input pulse from the generator with a semiconductor opening switch (SOS) is amplified in power and decreases in duration by ferrite gyromagnetic lines. The lines operate in the Magnetic Compression Line (MCL) mode, which occurs at close values of the input pulse duration and the period of the oscillations generated in the line. The energy compression system contains three successive stages-MCL1-MCL3 lines. For an input pulse power of 6 GW (490 kV, 40 Ω) and a duration of 7 ns, pulses of 54 GW (1.62 MV, 48 Ω) and a duration of 170 ps have been achieved at the MCL3 output. Compared to the parameters of the input pulse, the voltage rise rate has been increased ∼130 times up to 14.8 MV/ns, and the power rise rate has been increased ∼350 times up to 0.7 TW/ns. A numerical simulation of the MCL3 line operation in which the maximum electric and magnetic fields are realized (>2 MV/cm and >500 kA/m, respectively) has been carried out. The inner structure of the process of power amplification during the electromagnetic wave passage along the line has been demonstrated. First, the front of the input pulse is sharpened, and then, after the excitation of the oscillations, the process of power amplification begins, followed by the pulse amplitude reaching the saturation region.

Semiconductor opening switch generator with a primary thyristor switch triggered in impact-ionization wave mode.

The results of the investigation involving a thyristor switch triggered in the impact ionization wave mode are presented. This switch is intended for operation as a primary switch in a nanosecond pulse generator with a semiconductor opening switch (SOS). The thyristor switch is based on commercial low-frequency tablet thyristors stacked in a joint assembly of up to 6 pieces connected in series. At a charging voltage of 2-12 kV and switching energy of up to 16 J, the switch operates with a discharge current of up to 8 kA, a current rise rate in the range from 14 to 54 kA/µs, and a switching efficiency of ∼0.9. It is shown that an increase in a voltage rise rate on thyristors at the triggering stage reduces energy loss in the thyristor switch during the current flow. The SOS pumping circuit contains one magnetic element-a pulse transformer, which simplifies the generator and increases its efficiency. The SOS generator has an output voltage of up to 300 kV and a peak power of up to 250 MW with a pulse duration of ∼50 ns. The thyristor switch in the generator operates at a voltage of 12 kV and provides current flow with the amplitude of up to 7.5 kA with a duration of ∼500 ns and a current rise rate of ∼54 kA/µs. The pulse repetition frequency of the generator is 1 kHz in the burst mode of operation.

A 30 GW subnanosecond solid-state pulsed power system based on generator with semiconductor opening switch and gyromagnetic nonlinear transmission lines.

This article describes a subnanosecond solid-state pulsed power system in which an input pulse from a generator with a semiconductor opening switch (generator) is amplified in power and is shortened in time by a two-stage magnetic compressor based on gyromagnetic nonlinear transmission lines. In this approach, the line of each stage operates as a magnetic compression line (MCL) which is realized when the duration of the input pulse is close to the period of oscillations generated by the line. The compression system contains two series connected lines MCL1 and MCL2 with a wave impedance of 40 Ω. The input pulse has a duration of 7 ns and an amplitude of 500 kV. After two compression stages, the pulse amplitude increases to 1.1 MV and the peak power increases from 6 to 30 GW, while the pulse duration transits into subnanosecond range (0.65 ns). In the burst mode, the system operates at a pulse repetition frequency up to 1 kHz.

Oscillons: an encounter with dynamical chaos in 1953?

We discuss the works of one of electronic art pioneers, Ben F. Laposky (1914-2000), and argue that he might have been the first to create a family of essentially nonlinear analog circuits that allowed him to observe chaotic attractors.

Thermal equilibration between two quantum systems.

Two identical finite quantum systems prepared initially at different temperatures, isolated from the environment, and subsequently brought into contact are demonstrated to relax towards Gibbs-like quasiequilibrium states with a common temperature and small fluctuations around the time-averaged expectation values of generic observables. The temporal thermalization process proceeds via a chain of intermediate Gibbs-like states. We specify the conditions under which this scenario occurs and corroborate the quantum equilibration with two different models.

[The training of Zemstvo low-grade medical workers in Middle Volga Gubernia].

The article deals with the input of zemstvo self-management into establishment and development of secondary professional medical education in the Middle Volga region in second half of XIX-early XX centuries. The activities of zenmstvo is discussed concerning the organization and support of the infrastructure of feldsher schools, midwifes schools, the admission rules, the requirements to feldsher school graduates being the zemstvo scholarship grant holders. The activity of feldsher schools is reflected concerning the advanced training of low-grade medical workers.

Mapping the Arnold web with a graphic processing unit.

The Arnold diffusion constitutes a dynamical phenomenon which may occur in the phase space of a non-integrable Hamiltonian system whenever the number of the system degrees of freedom is M ≥ 3. The diffusion is mediated by a web-like structure of resonance channels, which penetrates the phase space and allows the system to explore the whole energy shell. The Arnold diffusion is a slow process; consequently, the mapping of the web presents a very time-consuming task. We demonstrate that the exploration of the Arnold web by use of a graphic processing unit-supercomputer can result in distinct speedups of two orders of magnitude as compared with standard CPU-based simulations.

ac-driven atomic quantum motor.

We propose an ac-driven quantum motor consisting of two different, interacting ultracold atoms placed into a ring-shaped optical lattice and submerged in a pulsating magnetic field. While the first atom carries a current, the second one serves as a quantum starter. For fixed zero-momentum initial conditions the asymptotic carrier velocity converges to a unique nonzero value. We also demonstrate that this quantum motor performs work against a constant load.

Electron beam treatment of textile dyeing wastewater: operation of pilot plant and industrial plant construction.

A pilot plant for treating 1000 m3/day of dyeing wastewater with e-beam has been constructed and operated since 1998 in Daegu, Korea together with the biological treatment facility. The wastewater from various stages of the existing purification process has been treated with an electron beam in this plant, and it gave rise to elaborating the optimal technology of the electron beam treatment of wastewater with increased reliability for instant changes in the composition of wastewater. Installation of the e-beam pilot plant resulted in decolorizing and destructive oxidation of organic impurities in wastewater, appreciable reduction of chemical reagent consumption, in reduction of the treatment time, and in increase in the flow rate limit of existing facilities by 30-40%. Industrial plant for treating 10,000 m3/day each, based upon the pilot experimental result, is under construction and will be finished by 2005. This project is supported by the International Atomic Energy Agency (IAEA) and Korean Government.