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Modeling of the production of nitrogen oxide molecules in DC discharges in laminar longitudinal flows of atmospheric‐pressure air is performed. Two‐dimensional nonequilibrium discharge model includes the system of gas dynamic equations and balance equations for various plasma components. Simulations are performed for the discharge currents 50–600 mA and gas flow velocities 1–10 m/s. In considered conditions, the gas temperature in the discharge core varies in the range of 3000–6000 K. Spatial profiles of the densities and fluxes of produced species are obtained, both inside the discharge and in the afterglow region. The energy cost for the production of nitrogen oxides is calculated, depending on the discharge current, gap length, and gas flow velocity. The results of the simulation are compared with available experimental data. [ABSTRACT FROM AUTHOR]

Polycystic ovary syndrome (PCOS) is a highly prevalent disorder in women, and its diagnosis rests on three principal features: ovulatory/menstrual dysfunction, clinical and/or biochemical hyperandrogenism, and polycystic ovarian morphology (PCOM). Currently, data on age- and ethnicity-dependent features of PCOM remain insufficient. We aimed to estimate ethnicity- and age-dependent differences in ovarian volume (OV) and follicle number per ovary (FNPO) in a healthy, medically unbiased population of Caucasian and Asian premenopausal women, who participated in the cross-sectional Eastern Siberia PCOS epidemiology and phenotype (ESPEP) study (ClinicalTrials.gov ID: NCT05194384) in 2016–2019. The study population consisted of 408 non-hirsute, normo-androgenic, eumenorrheic premenopausal women aged 18–44 years. All participants underwent a uniform evaluation including a review of their medical history and a physical examination, blood sampling, and pelvic ultrasonography. The statistical analysis included non-parametric tests and the estimation of the upper normal limits (UNLs) by 98th percentiles for OV and FNPO. In the total study population, the upper OV percentiles did not differ by ethnicity or age group. By contrast, the UNL of FNPO was higher in Caucasian women than in Asian women, and women aged <35 years demonstrated a higher UNL of FNPO compared to older women. In summary, these data suggest that the estimation of FNPO, but not OV, should take into account the ethnicity and age of the individual in estimating the presence of PCOM. [ABSTRACT FROM AUTHOR]

In this paper, we report results from the computational study of the intersection of the atmospheric pressure plasma jet with a dielectric surface having high conductivity and high dielectric constant. In this case, multiple reflections of the ionization wave (IW) between the jet tube and the surface are observed. We consider the mixture of helium with a small percentage of oxygen (He/O2 = 99.8/0.2), which flows through the jet tube into the ambient humid room air (N2/O2/H2O = 79.5/20/0.5). We evaluate the production and delivery of main ions and reactive oxygen and nitrogen species, which are important for applications in biomedicine. The fluxes and fluences of these species to the dielectric surface are recorded during a single plasma jet pulse of negative polarity. We show that the electron density behind the IW front increases with each passage of the IW between the tube and the surface. With the forward, reflected, and secondary forward IW, there is an essential increase of ions and radicals behind the IW front. The highest increase of radicals and their fluxes is observed after the secondary forward wave bridges the gap and touches the surface. [ABSTRACT FROM AUTHOR]

Abnormalities in gut microbiota diversity are considered important mechanisms in metabolic disorders in polycystic ovarian syndrome (PCOS). However, the data on the association of these disorders with the PCOS phenotype remain controversial. The objectives of this study were to estimate the alpha diversity of the gut microbiota of healthy women and PCOS patients depending on phenotype. The study participants (184 premenopausal women: 63 with PCOS, 121 without PCOS) were recruited during the annual employment assessment in the Irkutsk Region and the Buryat Republic (Russia) in 2016–2019. For PCOS diagnosis, we used the Rotterdam (2003) criteria and definitions of PCOS phenotypes. Five indexes of alpha diversity (ASV, Shannon, Simpson, Chao, and ACE) were estimated for the gut microbiota in all participants using amplicon metasequencing. As a result, two out of five alpha diversity indexes showed a statistical difference between the non-PCOS and PCOS groups. We did not find a significant difference in the alpha diversity of gut microbiota in the subgroups of women with hyperandrogenic PCOS phenotypes vs non-androgenic phenotype D and the group of women with the presence of only one of the PCOS criteria. Nevertheless, "classic" PCOS phenotypes demonstrated the most significant decrease in alpha diversity compared with healthy women without any signs of PCOS. [ABSTRACT FROM AUTHOR]

The penetration of plasma into the wafer-focus ring gap of a capacitatively coupled discharge is examined. It is shown that the penetration of plasma into the gap and under the wafer level has increased as the size of the gap approaches and exceeds the Debye length in the vicinity of the gap.

A study is conducted to determine if multidimensional considerations affect energy scalings for production of O2((super 1) DELTA). The findings reveal that O2((super 1) DELTA) production generally does scale linearly with energy loading, however, the saturation of O2((super 1) DELTA) production occurs at lower-energy loadings than predicted with global and one-dimensional models.

The process of a dust-grain charging in developing air plasma with an external source S ([cm.sup.-3] [s.sup.-1]) is studied analytically and numerically in drift-diffusion approximation. It is shown that, when the source is turned on, the steady-state level of electron concentration in the bulk plasma is attained rather quickly (the time being determined by the attachment rate). The time of establishing the ion concentration depends on the source intensity as [S.sup.-1/2]. In the steady state, the ratio of ion-to-electron concentrations is proportional to the source intensity as [S.sup.-1/2] and can be very large for low-intensity sources. As a consequence, the process of a dust-grain charging in developing plasma differs significantly for low- and high-intensity sources. At sufficiently high rates of ionization, the grain charge in air is comparable to that in electropositive gases. For low-intensity sources when the ion concentration exceeds that of electron by several orders of magnitude, the grain charge is of the order of several tens of electron charges. The oscillating regime of a dust-grain charging is observed for low-intensity sources. Index Terms--Air plasma, attachment, dust grain, external source intensity.

For a single-frequency capacitively coupled radio-frequency discharge, the detailed examination has been carried out of plasma density and sheath width, average potential profiles, ion-energy distribution at the electrodes and electron-energy distribution in the bulk plasma as a function of pressure, voltage, and frequency using particle-in-cell/Monte Carlo simulation. The results for Ar gas are presented. Scaling of plasma parameters with external parameters is determined. The characteristics of dual-frequency argon discharge are studied for different ratio of high/low frequencies. Nonmonotonons behavior of plasma density versus low-frequency voltages is attributed to the increase of sheath width and, as a consequence, to the increase of energy absorbed by ions in the sheath region. Subsequent decrease of energy absorbed by electrons results in the decrease of plasma density. For certain frequency ratio with the further increase of power, the plasma density increases again until the collapse of the bulk occurs. Index Terms--Capacitively-coupled plasmas, dual frequency, ion-energy distribution (IED), particle-in-cell (PIC) simulation, plasma potential.

A needle-circular electrode structure helium plasma jet driven by microsecond pulsed power is studied. Spatially resolved emission results show that the emission intensity of He(33S1) line decreases monotonically along the axial direction, while those of N2(C3Πu), N2 + (B2 Σ+ u), and O (3p5P) reach their maxima at 3 cm, 2.6 cm, and 1.4 cm, respectively. The plasma plume of the four species shows different characteristics: The N2 emission plume travels at a fast speed along the entire plasma jet; the N2 + emission plume is composed of a bright head and relatively weak tail and travels a shorter distance than the N2 emission plume; the He emission plume travels at a slower speed for only a very short distance; propagation of the O emission plume is not observed. Results of calculation of radiation fluxes emitted by positive streamers propagating along helium plasma jets are presented. It is shown, in agreement with the results of the present experiment and with other available experimental data, that the intensities of radiation of N2(C3Πu) molecules and He(33S1) atoms vary with time (along the plasma jet) quite differently. The factors resulting in this difference are discussed. [ABSTRACT FROM AUTHOR]

Chemical oxygen-iodine lasers (COILs) oscillate on the 2P1/2→2P3/2 transition of atomic iodine at 1.315 μm by a series of excitation transfers from O2(1Δ). In electrically excited COILs (eCOILs), the O2(1Δ) is produced in a flowing plasma, typically He/O2, at a few to tens of Torr. Many system issues motivate operating eCOILs at higher pressures to obtain larger absolute densities of O2(1Δ) for a given yield and to provide higher back pressure for expansion. In this paper, we discuss results from a computational investigation of O2(1Δ) production in flowing plasmas sustained at moderate pressures (≤50 Torr). Power deposition and flow rates were scaled such that in the absence of second order effects, yield should be constant and absolute O2(1Δ) production should scale linearly with pressure. We found in many cases that absolute O2(1Δ) production scaled sublinearly with pressure. Ozone is found to be one of the major quenchers of O2(1Δ) and its production increases with pressure. Gas heating also increases with increasing pressure due to exothermic three-body reactions. The gas heating reduces O3 production, increases O3 destruction and, for certain conditions, restores yields. With increasing pressure and increasing absolute densities of atomic oxygen and pooling reactions of O2(1Δ), quenching by these species also becomes important, though the influence of O-atom quenching can be controlled by managing the density of O atoms with additives. The yield of O2(1Δ) is also determined by discharge stability which becomes problematic at higher pressure. [ABSTRACT FROM AUTHOR]

In chemical oxygen iodine lasers (COILs), oscillation at 1.315 μm in atomic iodine (2P1/2→2P3/2) is produced by collisional excitation transfer of O2(1Δ) to I2 and I. Plasma production of O2(1Δ) in electrical COILs (eCOILs) eliminates liquid phase generators. For the flowing plasmas used for eCOILs (He/O2, a few to tens of torr), self-sustaining electron temperatures, Te, are 2–3 eV whereas excitation of O2(1Δ) optimizes with Te=1–1.5 eV. One method to increase O2(1Δ) production is by lowering the average value of Te using spiker-sustainer (SS) excitation where a high power pulse (spiker) is followed by a lower power period (sustainer). Excess ionization produced by the spiker enables the sustainer to operate with a lower Te. Previous investigations suggested that SS techniques can significantly raise yields of O2(1Δ). In this paper, we report on the results from a two-dimensional computational investigation of radio frequency (rf) excited flowing He/O2 plasmas with emphasis on SS excitation. We found that the efficiency of SS methods generally increase with increasing frequency by producing a higher electron density, lower Te, and, as a consequence, a more efficient production of O2(1Δ). [ABSTRACT FROM AUTHOR]

In conventional chemical oxygen-iodine lasers (COIL) the 1.315 μm transition in atomic iodine is pumped by a sequence of reactions of I2 and I with O2(1Δ) which is generated using liquid chemistry. Ongoing studies are investigating means to produce the O2(1Δ) precursor with an electric discharge (eCOIL) to enable a totally gas phase system. Due to the thermodynamic and power loading requirements, the plasma in eCOIL systems is sustained in a flow of a rare-gas diluent and the O2. In previous investigations, the scaling of production of O2(1Δ) was investigated using global-kinetics and one-dimensional (1D) models. It was found that the production of O2(1Δ) scaled linearly with energy deposition for moderate loadings (a few eV/O2 molecule). In this paper, these previous investigations are extended to two-dimensions using a plasma hydrodynamics model. The goal of this investigation is to determine if multidimensional considerations affect energy scalings for production of O2(1Δ). We found that O2(1Δ) production generally does scale linearly with energy loading, however, the saturation of O2(1Δ) production occurs at lower-energy loadings than predicted with global and 1D models. This trend is a result of the more accurately depicted and more localized energy deposition afforded by the two-dimensional model, and emphasizes the need for volumetrically uniform power deposition to optimize O2(1Δ) production. [ABSTRACT FROM AUTHOR]

Plug-flow and two-dimensional (2D) plasma hydrodynamics models are used for examining pressure scaling of the absolute densities and yields of [O.sub.2]([super 1][DELTA]) in flowing He/[O.sub.2] plasmas. The densities and yields of [O.sub.2]([super 1][DELTA]) have significant sublinear scaling and pressure.

The branching of streamers in atmospheric-pressure air, dense gases, and liquids is a common occurrence whose origins are likely found with many causes, both deterministic and stochastic. In this paper, we investigate the consequences of stochastic inhomogeneities on the propensity of branching of streamers in high-pressure gases. Index Terms--Branching, corona, streamers.