Reactive oxygen species production in atmospheric-pressure low-temperature He+O2+H2O plasmas

Low-temperature atmospheric pressure plasmas have received growing interest in recent years, due to their increasing popularity in technological and biological applications. There are many advantages to using these plasmas, for example, they are relatively cheap to run as they do not require expensive vacuum equipment, they are portable, they can be run at near room temperature and they can create complex reactive chemistries inside and outside the discharge region

Double-layer structures in low-temperature atmospheric-pressure electronegative RF microplasmas: separation of electrons and anions

Stratification of negatively charged species in electronegative discharges is a well-known phenomenon that can lead to various double-layer structures. Here, we report on the separation of electrons and anions in atmospheric-pressure electronegative microdischarges. In these discharges, electrons oscillate between the electrodes, moving across and beyond an electronegative core. As a result of this motion, positively charged regions form between the oscillating electron ensemble and the central electronegative discharge

Dynamics of atmospheric pressure He/H2O microplasmas: a new double layer structure

Dynamics of atmospheric pressure He/H2O microplasmas: a new double layer structur

Generation and loss of reactive oxygen species in low-temperature atmospheric-pressure RF He + O2 + H2O plasmas

This study focuses on the generation and loss of reactive oxygen species (ROS) in low-temperature atmospheric-pressure RF (13.56 MHz) He + O2 + H2O plasmas, which are of interest for many biomedical applications. These plasmas create cocktails of ROS containing ozone, singlet oxygen, atomic oxygen, hydroxyl radicals, hydrogen peroxide and hydroperoxyl radicals, i.e. ROS of great significance as recognized by the free-radical biology community. By means of one-dimensional fluid simulations (61 species, 878 reactions), the key ROS and their generation and loss mechanisms are identified as a function of the oxygen and water content in the feed gas. Identification of the main chemical pathways can guide the optimization of He + O2 + H2O plasmas for the production of particular ROS. It is found that for a given oxygen concentration, the presence of water in the feed gas decreases the net production of oxygen-derived ROS, while for a given water concentration, the presence of oxygen enhances the net production of water-derived ROS. Although most ROS can be generated in a wide range of oxygen and water admixtures, the chemical pathways leading to their generation change significantly as a function of the feed gas composition. Therefore, care must be taken when selecting reduced chemical sets to study these plasmas

Atmospheric pressure plasmas: generation and delivery of reactive oxygen species for biomedical applications

Reactive oxygen species (ROS) that can trigger biological responses are readily attainable in atmospheric pressure plasma sources. Admixtures of oxygen and water can act as precursors for the generation of these ROS and lead to the production of O, OH, O3, 1 O2, OOH and H2O2. The dynamics and chemistry in these discharges is complex and result in intricate spatiotemporal profiles of the species that cannot be accurately captured by zero dimensional analysis. Besides fluxes of neutral ROS, ionic fluxes including anions are also observed. The high reactivity of most of the ROS, however, limits their penetration into the treated sample and therefore encapsulation of the ROS and/or triggering of a secondary chemistry is required for the plasma treatment to reach beyond the first layers of biomolecules

Generation and loss of reactive oxygen species in low-temperature atmospheric-pressure RF He+O2+H2O plasma

This study focuses on the generation and loss of reactive oxygen species (ROS) in lowtemperature atmospheric‐pressure rf (13.56MHz) He+O2+H2O plasmas, which are of interest for many biomedical applications. Pure He+O2 plasmas are a good source of ozone, singlet oxygen and atomic oxygen, with densities of these species increasing as oxygen content increases1. He+H2O plasmas offer an interesting alternative to He+O2 plasmas as a source of reactive oxygen species (ROS), and they produce significant amounts of hydrogen peroxide, hydroxyl radicals and hydroperoxyl radicals, which increase with increasing water content2. Admixtures of O2 and H2O lead to richer cocktails of ROS that combine all these species

Electron-anion separation in electronegative rf microdischarges

Several types of double-layer structures have been reported previously in the literature and the stratification of negatively charged species in electronegative discharges is a well known phenomena. Here we report on the evolution of a different type of double layer structure found in electronegative microplasmas. In these microdischarges, the electron ensemble oscillates between the electrodes forming sheaths that are larger than half the discharge gap. As the electrons oscillate, they move across and beyond a central electronegative core formed by anions. As a result of their different motion, electrons and anions are completely separated and regions of positive space charge form between the oscillating electron ensemble and the central electronegative discharge

Chemical pathways governing the production of Reactive Oxygen Species (ROS) in atmospheric pressure He+O2+H2O plasmas

It is well-known that atmospheric-pressure plasmas can be engineered to produce reactive oxygen species (ROS) and reactive nitrogen species (RNS) known to play important roles in biological systems. Here we concentrate on the generation of ROS, and in particular on the chemical pathways that govern the generation and loss of ROS in atmospheric pressure rf (13.56MHZ) plasmas sustained in helium with admixtures of O2 and H2O

Managing female athlete health : Auditing the representation of female versus male participants among research in supplements to manage diagnosed micronutrient issues

Micronutrient deficiencies and sub-optimal intakes among female athletes are a concern and are commonly prevented or treated with medical supplements. However, it is unclear how well women have been considered in the research underpinning current supplementation practices. We conducted an audit of the literature supporting the use of calcium, iron, and vitamin D. Of the 299 studies, including 25,171 participants, the majority (71%) of participants were women. Studies with exclusively female cohorts (37%) were also more prevalent than those examining males in isolation (31%). However, study designs considering divergent responses between sexes were sparse, accounting for 7% of the literature. Moreover, despite the abundance of female participants, the quality and quantity of the literature specific to female athletes was poor. Just 32% of studies including women defined menstrual status, while none implemented best-practice methodologies regarding ovarian hormonal control. Additionally, only 10% of studies included highly trained female athletes. Investigations of calcium supplementation were particularly lacking, with just two studies conducted in highly trained women. New research should focus on high-quality investigations specific to female athletes, alongside evaluating sex-based differences in the response to calcium, iron, and vitamin D, thus ensuring the specific needs of women have been considered in current protocols involving medical supplements

Effect of Menstrual Cycle Phase and Hormonal Contraceptives on Resting Metabolic Rate and Body Composition

The cyclical changes in sex hormones across the menstrual cycle (MC) are associated with various biological changes that may alter resting metabolic rate (RMR) and body composition estimates. Hormonal contraceptive (HC) use must also be considered given their impact on endogenous sex hormone concentrations and synchronous exogenous profiles. The purpose of this study was to determine if RMR and dual-energy X-ray absorptiometry body composition estimates change across the MC and differ compared with HC users. This was accomplished during a 5-week training camp involving naturally cycling athletes (n = 11) and HC users (n = 7 subdermal progestin implant, n = 4 combined monophasic oral contraceptive pill, n = 1 injection) from the National Rugby League Indigenous Women's Academy. MC phase was retrospectively confirmed via serum estradiol and progesterone concentrations and a positive ovulation test. HC users had serum estradiol and progesterone concentrations assessed at the time point of testing. Results were analyzed using general linear mixed model. There was no effect of MC phase on absolute RMR (p = .877), relative RMR (p = .957), or dual-energy X-ray absorptiometry body composition estimates (p > .05). There was no effect of HC use on absolute RMR (p = .069), relative RMR (p = .679), or fat mass estimates (p = .766), but HC users had a greater fat-free mass and lean body mass than naturally cycling athletes (p = .028). Our findings suggest that RMR and dual-energy X-ray absorptiometry body composition estimates do not significantly differ due to changes in sex hormones in a group of athletes, and measurements can be compared between MC phases or with HC usage without variations in sex hormones causing additional noise