Thermal rate constants and kinetic isotope effects of the H + H2O2 reactions: barrier height and reaction energy from single- and multireference methods.

CONTEXT: One of the more significant sub-mechanisms of H2/O2 combustion involves the reaction of hydrogen peroxide with hydrogen atoms (H + H2O2), resulting in the production of OH + H2O (R1) and H2 + HO2 (R2) paths. Previous experimental and ab initio calculations reveal some variations in the barrier height for (R1). To improve the energetics of both (R1) and (R2), single reference and multireference ab initio methods are employed, and the rate constants and H/D kinetic isotope effects (KIEs) are calculated as a function of temperature. For (R1), the best results for the barrier height and reaction energies computed with the CASPT2(15,11)/aug-cc-pV6Z are 5.2 and - 70.3 kcal.mol-1, respectively. CCSD(T)/aug-cc-pV5Z + CV (core-valence) calculations for (R2) give 9.7 and - 15.6 kcal.mol-1 to those parameters. The CVT/SCT rate constants of both paths agree well with the fitted rate constants from uncertainty-weighted statistical analysis of the 14-mechanism of H2/O2. The kinetic isotopic effect (kH/kD) for the reaction D + H2O2 → DH + HO2 was found to be 0.47, which is in excellent agreement with the experimental value of 0.43. METHODS: The structures of reactants, transition state, and products of (R1) and (R2) are calculated with the aug-cc-pVTZ basis set and M062X DFT, CCSD(T), and CASSCF methods. The barrier heights and reaction energies of (R1) and (R2) are computed using the M06-2X, CCSD(T), MRCI, and CASPT2 methods and various basis sets. The rate constants are calculated with the variational transition state theory including multidimensional tunneling corrections (VTST-MT), with potential energy surfaces built by the M06-2X/aug-cc-pVTZ approach.

Carbohydrate mouth rinse failed to reduce central fatigue, lower perceived exertion, and improve performance during incremental exercise.

We examined if carbohydrate (CHO) mouth rinse may reduce central fatigue and perceived exertion, thus improving maximal incremental test (MIT) performance. Nine recreational cyclists warmed up for 6 min before rinsing a carbohydrate (CHO) or placebo (PLA) solution in their mouth for 10 s in a double-blind, counterbalanced manner. Thereafter, they performed the MIT (25 W·min-1 increases until exhaustion) while cardiopulmonary and ratings of perceived exertion (RPE) responses were obtained. Pre- to post-MIT alterations in voluntary activation (VA) and peak twitch torque (Tw) were determined. Time-to-exhaustion (p = 0.24), peak power output (PPO; p = 0.45), and V̇O2MAX (p = 0.60) were comparable between conditions. Neither treatment main effect nor time-treatment interaction effect were observed in the first and second ventilatory threshold when expressed as absolute or relative V̇O2 (p = 0.78 and p = 0.96, respectively) and power output (p = 0.28 and p = 0.45, respectively) values, although with moderate-to-large effect sizes. RPE increased similarly throughout the tests and was comparable at the ventilatory thresholds (p = 0.56). Despite the time main effect revealing an MIT-induced central and peripheral fatigue as indicated by the reduced VA and Tw, CHO mouth rinse was ineffective in attenuating both fatigues. Hence, rinsing the mouth with CHO was ineffective in reducing central fatigue, lowering RPE, and improving MIT performance expressed as PPO and time-to-exhaustion. However, moderate-to-large effect sizes in power output values at VT1 and VT2 may suggest some beneficial CHO mouth rinse effects on these MIT outcomes.

Study of the Chemical Activities of Carbon Monoxide, Carbon Dioxide, and Oxygen Traces as Critical Inhibitors of Polypropylene Synthesis.

This study outlines the investigation into how the compounds CO2, CO, and O2 interact with the active center of titanium (Ti) on the surface of MgCl2 and how these interactions impact the productivity of the Ziegler-Natta catalyst, ultimately influencing the thermal stability of the produced polypropylene. The calculations revealed that the adsorption energies of Ti-CO2-CO and O2 were -9.6, -12.5, and -2.32 Kcal/mol, respectively. Using the density functional theory in quantum calculations, the impacts of electronic properties and molecular structure on the adsorption of CO, O2, and CO2 on the Ziegler-Natta catalyst were thoroughly explored. Additionally, the Gibbs free energy and enthalpy of adsorption were examined. It was discovered that strong adsorption and a significant energy release (-16.2 kcal/mol) during CO adsorption could explain why this gas caused the most substantial reductions in the ZN catalyst productivity. These findings are supported by experimental tests showing that carbon monoxide has the most significant impact on the ZN catalyst productivity, followed by carbon dioxide, while oxygen exerts a less pronounced inhibitory effect.

Application of artificial intelligence for the optimization of advanced oxidation processes to improve the water quality polluted with pharmaceutical compounds.

Sulfamethoxazole and metronidazole are emerging pollutants commonly found in surface water and wastewater. These compounds have a significant environmental impact, being necessary in the design of technologies for their removal. Recently, the advanced oxidation process has been proven successful in the elimination of this kind of compounds. In this sense, the present work discusses the application of UV/H2O2 and ozonation for the degradation of both molecules in single and binary systems. Experimental kinetic data from O3 and UV/H2O2 process were adequately described by a first and second kinetic model, respectively. From the ANOVA analysis, it was determined that the most statistically significant variables were the initial concentration of the drugs (0.03 mmol L-1) and the pH = 8 for UV/H2O2 system, and only the pH (optimal value of 6) was significant for degradation with O3. Results showed that both molecules were eliminated with high degradation efficiencies (88-94% for UV/H2O2 and 79-98% for O3) in short reaction times (around 30-90 min). The modeling was performed using a quadratic regression model through response surface methodology representing adequately 90 % of the experimental data. On the other hand, an artificial neural network was used to evaluate a non-linear multi-variable system, a 98% of fit between the model and experimental data was obtained. The identification of degradation byproducts was performed by high-performance liquid chromatography coupled to a time mass detector. After each process, at least four to five stable byproducts were found in the treated water, reducing the mineralization percentage to 20% for both molecules.

"Impact of aging on maximal oxygen uptake adjusted for lower limb lean mass, total body mass, and absolute values in runners".

Performance in endurance sports decreases with aging, which has been primarily attributed to cardiovascular and musculoskeletal aging; however, there is still no clear information on the factors that are most affected by aging. The aim of this study was to compare two groups of runners (< 50 and > 50 years of age) according to their absolute, weight-adjusted maximal oxygen uptake (V̇O2max), lower limb lean mass-adjusted V̇O2max, ventilatory threshold, and respiratory compensation point (RCP). A total of 78 male recreational long-distance runners were divided into Group 1 (38.12 ± 6.87 years) and Group 2 (57.55 ± 6.14 years). Participants were evaluated for body composition, V̇O2max, VT, and RCP. Group 1 showed higher absolute and body mass-adjusted V̇O2max (4.60 ± 0.57 l·min-1 and 61.95 ± 8.25 ml·kg-1·min-1, respectively) than Group 2 (3.77 ± 0.56 l·min-1 and 51.50 ± 10.22 ml·kg-1·min-1, respectively), indicating a significant difference (p < 0.001, d = - 1.46 and p < 0.001, d = - 1.16). Correspondingly, Group 1 showed a significantly higher lower limb lean mass-adjusted V̇O2max (251.72 ± 29.60 ml·kgLM-1·min-1) than Group 2 (226.36 ± 43.94 ml·kgLM-1·min-1) (p = 0.008, d = - 0.71). VT (%V̇O2max) (p = 0.19, d = 0.19) and RCP (%V̇O2max) (p = 0.24, d = 0.22) did not differ between the groups. These findings suggest that both variables that are limited by central or peripheral conditions are negatively affected by aging, but the magnitude of the effect is higher in variables limited by central conditions. These results contribute to our understanding of how aging affects master runners.

Hydrogen peroxide in attenuation of salt stress effects on physiological indicators and growth of soursop / Peróxido de hidrogênio na atenuação do estresse salino nos indicadores fisiológicos e crescimento da gravioleira

To mitigate the deleterious effects of salt stress, substances capable of acting as mitigators and/or inducers of tolerance to stress have been used, enabling the use of saline waters and contributing to the development of irrigated agriculture. In this context, the aim of the present study was to evaluate the effect of foliar spraying with hydrogen peroxide as an attenuator of salt stress effects on soursop morphophysiology. The experiment was conducted under greenhouse conditions in Campina Grande - PB, Brazil, using a randomized block design, in a 4 × 4 factorial arrangement, whose treatments resulted from the combination of four levels of electrical conductivity of irrigation water - ECw (0.8 ­ control, 1.6, 2.4, and 3.2 dS m-1) and four concentrations of hydrogen peroxide - H2O2 (0, 10, 20, and 30 µM), with three replicates. Foliar application of hydrogen peroxide at a concentration of 10 µM increased growth, chlorophyll synthesis, and relative water content in the leaves and consequently reduced the foliar water saturation deficit of soursop irrigated with ECw up to 1.6 dS m-1. The concentration of hydrogen peroxide of 30 µM intensified the salt stress on the electrolyte leakage in the leaf blade and the photosynthetic pigments of soursop, 270 days after transplanting.

Para mitigar os efeitos deletérios do estresse salino, tem se utilizado substâncias capazes de atuar como atenuantes e/ou indutoras de tolerância ao estresse, viabilizando o uso de águas salinas e contribuindo para desenvolvimento da agricultura irrigada. Neste contexto, objetivou-se com presente estudo, avaliar o efeito da pulverização foliar com peróxido de hidrogênio como atenuante do estresse salino sobre a morfofisiologia da gravioleira. O estudo foi conduzido sob condições de casa de vegetação, em Campina Grande - PB, utilizando-se o delineamento de blocos casualizados, no arranjo fatorial 4 × 4, cujos tratamentos resultaram da combinação de quatro níveis de condutividade elétrica da água de irrigação - CEa (0,8 ­ controle; 1,6; 2,4 e 3,2 dS m-1) e quatro concentrações de peróxido de hidrogênio - H2O2 (0; 10; 20 e 30 µM), com três repetições. A aplicação foliar de peróxido de hidrogênio na concentração de 10 µM aumentou o crescimento, a síntese de clorofila e o teor relativo de água nas folhas e consequentemente reduziu o déficit de saturação hídrica foliar da gravioleira irrigada com CEa de até 1,6 dS m-1. A concentração de peroxido de hidrogênio de 30 µM intensificou o estresse salino sobre o extravasamento de eletrólitos no limbo foliar e os pigmentos fotossintéticos da gravioleira, aos 270 dias após o transplantio.

Altitude Diving on a Closed Circuit Oxygen Rebreather.

Closed-circuit rebreather diving is becoming more common. Rebreathers are complicated, adding to the stress of diving. Also adding to this complexity in the presented case is diving at a high-altitude, cold-water reservoir in Colorado. One diver experienced an oxygen-induced seizure at depth. The other diver had a rapid ascent with loss of consciousness. In this case, two experienced divers recovered from a possible devastating dive. Fortunately, they both returned to their pre-dive baseline health. Dive plan- ning is important, but as in this case, dive execution is paramount. This is a clinical case for an uncommon event presenting to an emergency department.

Electrochemically enhanced iron oxide-modified carbon cathode toward improved heterogeneous electro-Fenton reaction for the degradation of norfloxacin.

In this work, different iron-based cathode materials were prepared using two different approaches: a novel one-step approach, which involved the incorporation of iron oxide with Printex® L6 carbon/PTFE (PL6C/PTFE) on bare carbon felt (CF) and a two-step approach, where iron oxide is deposited onto CF previously modified with PL6C/PTFE. The results obtained from the physical characterization indicated that the presence of iron oxide homogeneously dispersed on the felt fibers with the CF 3-D network kept intact in the one-step approach; whereas the formation of iron oxide aggregates between the felt fibers for material obtained using the two-step approach. Among the iron oxide-based cathodes investigated, the iron-incorporated electrode exhibited the greatest efficiency in terms of the removal and mineralization of norfloxacin (NOR) under neutral pH (complete NOR removal in less than 30 min with around 50% mineralization after 90 min). The findings of this study show that the low cost and simple-to-prepare iron-modified carbon-based materials in HEF process led to the enhanced degradation of organic contaminants in aqueous solutions.

Comparative transcriptome analysis of high- and low-embryogenic Hevea brasiliensis genotypes reveals involvement of phytohormones in somatic embryogenesis.

BACKGROUND: Rubber plant (Hevea brasiliensis) is one of the major sources of latex. Somatic embryogenesis (SE) is a promising alterative to its propagation by grafting and seed. Phytohormones have been shown to influence SE in different plant species. However, limited knowledge is available on the role of phytohormones in SE in Hevea. The anther cultures of two Hevea genotypes (Yunyan 73477-YT and Reken 628-RT) with contrasting SE rate were established and four stages i.e., anthers (h), anther induced callus (y), callus differentiation state (f), and somatic embryos (p) were studied. UPLC-ESI-MS/MS and transcriptome analyses were used to study phytohormone accumulation and related expression changes in biosynthesis and signaling genes. RESULTS: YT showed higher callus induction rate than RT. Of the two genotypes, only YT exhibited successful SE. Auxins, cytokinins (CKs), abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), gibberellins (GAs), and ethylene (ETH) were detected in the two genotypes. Indole-3-acetic acid (IAA), CKs, ABA, and ETH had notable differences in the studied stages of the two genotypes. The differentially expressed genes identified in treatment comparisons were majorly enriched in MAPK and phytohormone signaling, biosynthesis of secondary metabolites, and metabolic pathways. The expression changes in IAA, CK, ABA, and ETH biosynthesis and signaling genes confirmed the differential accumulation of respective phytohormones in the two genotypes. CONCLUSION: These results suggest potential roles of phytohormones in SE in Hevea.

The serine-arginine (SR) protein UmRrm75 from Ustilago maydis is a functional ortholog of yeast ScHrb1.

The Basidiomycete fungus Ustilago maydis is a biotrophic pathogen of maize. The U. maydis UmRrm75 gene encodes an RNA-binding protein (RBP). In a previous study, we reported that ΔUmRrm75 null mutant strains accumulate H2O2, exhibit slow growth, and have decreased virulence in maize. Herein, we describe UmRrm75 as an ortholog of the ScHrb1, a serine-arginine (SR) protein identified in the yeast Saccharomyces cerevisiae, which plays a role in nuclear quality control, specifically in mRNA splicing and export processes. The yeast ScHrb1 mutant (ΔScHrb1) exhibits an increased sensitivity to elevated levels of boron. We noticed that the ΔScHrb1 displayed sensitivity to H2O2, which is consistent with previous findings in the ΔUmRrm75 mutant. We reversed the sensitivity phenotypes of boron and H2O2 by introducing the UmRrm75 gene into the ΔScHrb1 mutant. Furthermore, we generated complementary strains of U. maydis by expressing UmRrm75-GFP under its native promoter in the ∆UmRrm75 mutants. The UmRrm75-GFP/∆UmRrm75 complementary strains successfully recovered their growth capability under stressors, H2O2 and boron, resembling the parental strains FB2 and AB33. The subcellular localization experiments conducted in U. maydis revealed that the UmRrm75 protein is localized within the nucleus of both yeast and hyphae. The nuclear localization of the UmRrm75 protein remains unaltered even under conditions of heat or oxidative stress. This suggests that UmRrm75 might perform its RBP activity in the nucleus, as previously reported for ScHrb1. Our data contribute to understanding the role of the nuclear RBP UmRrm75 from the corn smut fungus U. maydis.

Sympathetic and angiotensinergic activity in spontaneously hypertensive rats treated with 3-amino-1,2,4-triazole.

Previous studies from our laboratory have shown that the pressor response to intracerebroventricular (icv) administered ANG II in normotensive rats or spontaneously hypertensive rats (SHRs) is attenuated by increased central H2O2 concentration, produced either by direct H2O2 icv injection or by increased endogenous H2O2 centrally in response to local catalase inhibition with 3-amino-1,2,4-triazole (ATZ). In the present study, we evaluated the effects of ATZ administered peripherally on arterial pressure and sympathetic and angiotensinergic activity in SHRs. Male SHRs weighing 280-330 g were used. Mean arterial pressure (MAP) and heart rate (HR) were recorded in conscious freely moving SHRs. Acute intravenous injection of ATZ (300 mg/kg of body weight) did not modify MAP and HR during the next 4 h, however, the treatment with ATZ (300 mg/kg of body weight twice per day) for 3 days reduced MAP (144 ± 6, vs. saline, 183 ± 13 mmHg), without changing HR. Intravenous hexamethonium (ganglionic blocker) produced a smaller decrease in MAP 4 h after ATZ (-25 ± 3, vs saline -38 ± 4 mmHg). Losartan (angiotensinergic AT1 receptor blocker) produced a significant depressor response 4 h after ATZ (-22 ± 4, vs. saline: -2 ± 4 mmHg) and in 3-day ATZ treated SHRs (-25 ± 5, vs. saline: -9 ± 4 mmHg). The results suggest that the treatment with ATZ reduces sympathetic activity in SHRs and simultaneously increases angiotensinergic activity.

Sex Differences in Maximal Oxygen Uptake Adjusted for Skeletal Muscle Mass in Amateur Endurance Athletes: A Cross Sectional Study.

Male athletes tend to outperform female athletes in several endurance sports. Maximum cardiac output can be estimated by maximal oxygen consumption (V˙O2max), and it has been established that men present V˙O2max values about 20% higher than women. Although sex differences in V˙O2max have already been well studied, few studies have assessed sex differences with regard to muscle oxidative capacity. The aim of this study was to compare aerobic muscle quality, accessed by V˙O2max and adjusted by lower limb lean mass, between male and female amateur triathletes. The study also aimed to compare sex differences according to V˙O2 submaximal values assessed at ventilatory thresholds. A total of 57 participants (23 women and 34 men), who had been training for Olympic-distance triathlon races, underwent body composition evaluation by dual-energy X-ray absorptiometry and performed a cardiorespiratory maximal test on a treadmill. Male athletes had significantly higher V˙O2max, both absolutely and when adjusted to body mass. Conversely, when V˙O2max was adjusted for lean mass, there was no significant difference between sexes. The same was observed at submaximal exercise intensities. In conclusion, differences in V˙O2max adjusted to body mass but not lean mass may explain, at least in part, sex differences in performance in triathlons, marathons, cycling, and other endurance sports.

The antihyperglycemic and hypolipidemic activities of a sulfur-oxidovanadium(IV) complex.

This study describes the synthesis, characterization, and biological activity of a new class of antidiabetic oxidovanadium(IV)-complexes with S2O2 coordination mode. The target complex 3,6-dithio-1,8-octanediolatooxidovanadium(IV), abbreviated as ([VIVO(octd)]), where octd = 3,6-dithio-1,8-octanediol, is formed from the reaction between the 3,6-dithio-1,8-octanediol and vanadyl sulfate (VIVOSO4). The effects of treatment with ([VIVO(octd)] on blood glucose, lipidic profile, body weight, food intake, water intake, urinary volume, glycogen levels, and biomarkers for liver toxicity were investigated using a streptozotocin (STZ)-induced diabetic Wistar rats model. The results have shown that the [VIVO(octd)] complex caused a significant decrease in blood glucose (247.6 ± 19.3 mg/dL vs 430.1 ± 37.6 mg/dL diabetic group, p < 0.05), triglycerides (TG, 50%) and very low-density cholesterol (VLDL-C, 50%) levels in STZ-diabetic rats after 3 weeks of treatment. The [VIVO(octd)] has shown antihyperglycemic activity in diabetic rats as well as a reduction in elevated lipid levels. Time-dependent studies using EPR and 51V NMR spectroscopy of [VIVO(octd)] were done in aqueous solutions to determine the complex stability and species present in the oral gavage solution used for complex administration. The spectroscopic studies have shown that the antidiabetic/hypolipidemic activity could be attributed to [VIVO(octd)], vanadium species resulting from redox processes, the hydrolysis of [VIVO(octd)] and its decomposition products, or some combination of these factors. In summary, the oxidovanadium(IV) complex containing the S2O2 donor ligand has desirable antidiabetic properties eliminating the symptoms of Diabetes mellitus and its comorbidities.

Amateur Female Athletes Perform the Running Split of a Triathlon Race at Higher Relative Intensity than the Male Athletes: A Cross-Sectional Study.

Maximal oxygen uptake (V˙O2max), ventilatory threshold (VT) and respiratory compensation point (RCP) can be used to monitor the training intensity and the race strategy, and the elucidation of the specificities existing between the sexes can be interesting for coaches and athletes. The aim of the study was to compare ventilatory threshold (VT), respiratory compensation point (RCP), and the percentage of the maximal aerobic speed (MAS) that can be maintained in a triathlon race between sexes. Forty-one triathletes (22 men and 19 women), 42.1 ± 8.4 (26 to 60) years old, that raced the same Olympic triathlon underwent a cardiorespiratory maximal treadmill test to assess their VT, RPC, and MAS, and race speed. The maximal oxygen uptake (V˙O2max) (54.0 ± 5.1 vs. 49.8 ± 7.7 mL/kg/min, p < 0.001) and MAS (17 ± 2 vs. 15 ± 2 km/h, p = 0.001) were significantly higher in male than in female athletes. Conversely, there were no sex differences according to the percentage of V˙O2max reached at VT (74.4 ± 4.9 vs. 76.1 ± 5.4%, p = 0.298) and RCP (89.9 ± 3.6 vs. 90.6 ± 4.0%, p = 0.560). The mean speed during the race did not differ between sexes (12.1 ± 1.7 km/h and 11.7 ± 1.8 km/h, p = 0.506, respectively). Finally, men performed the running split at a lower percentage of speed at RCP than women (84.0 ± 8.7 vs. 91.2 ± 7.0%, respectively, p = 0.005). Therefore, male and female athletes accomplished the running split in an Olympic triathlon distance at distinct relative intensities, as female athletes run at a higher RCP percentage.

Role of Pel and Psl polysaccharides in the response of Pseudomonas aeruginosa to environmental challenges: oxidative stress agents (UVA, H2O2, sodium hypochlorite) and its competitor Staphylococcus aureus.

Pseudomonas aeruginosa is a versatile bacterium capable of adapting to a wide range of stress factors, including solar UVA radiation (400-315 nm). High UVA doses produce lethal effects due to the action of reactive oxygen species. Sublethal UVA doses also induces oxidative damage, but, in addition, it triggers a variety of adaptive responses, including the overexpression of pelA and pslA genes in P. aeruginosa. These genes encode the synthesis of Pel and Psl, which are essential polysaccharides in biofilm formation. The present study analysed the role of Pel and Psl in the adaptive responses generated by exposure to low UVA doses, and their importance in the response to lethal doses of UVA, hydrogen peroxide (H2O2), and sodium hypochlorite, in both planktonic cells and submerged and air-liquid interface (ALI) biofilms. It also studied the roles of Pel and Psl in P. aeruginosa-Staphylococcus aureus interaction. The results demonstrate that the capacity of sublethal UVA exposure to increase cell hydrophobicity and cell attachment and generate cross-protection phenomena in P. aeruginosa depends on the presence of Pel and Psl. The study also shows that Pel and Psl have a key role in the tolerance to lethal doses of UVA radiation, sodium hypochlorite and H2O2, in both biofilms and planktonic cells. Finally, co-culture assays showed total inhibition of S. aureus growth in presence of P. aeruginosa. This phenomenon depends, at least in part, on the simultaneous presence of Pel and Psl in planktonic cells and biofilms, suggesting a relevant role of these polysaccharides in the interaction between these species.

Study of the oxidation process of bismuth nanoparticles using NaClO.

Bismuth nanoparticles (NPs) colloids synthesized in deionized water by laser ablation of solids in liquids technique (LASL) were oxidized using NaClO solutions at different concentrations. Oxidized nanomaterials were characterized using several techniques. The crystalline phases of the bismuth compound were determined using Raman microspectroscopy, and the crystallographic structure was identified by x-ray diffraction (XRD). The size and morphology of the obtained nanomaterials were studied by transmission electron microscopy (TEM). The chemical states were determined using x-ray photoelectron spectroscopy (XPS), and the optical properties of the colloids were characterized by UV-vis spectroscopy. The absorption spectra were analyzed using the Tauc method to determine the band gaps of the obtained nanomaterials. Our results showed morphological changes, starting from small nanoparticles to nanosheets and a mixture of nanosheets with hollow nanoparticles. Two kinds of nanomaterials were found depending on the NaClO solution concentration: Bi2O2CO3single phase and a mixture ofδ-Bi2O3and Bi2O2CO3. Some samples were tested as photocatalysts and showed good performance in the degradation of methylene blue in solution. To the best of our knowledge, this is the first study on the oxidation process of bismuth colloidal nanoparticles at room temperature.

Combined reverse osmosis and UV/H2O2 treatment of aqueous solutions of bisphenol A and 17α-ethinylestradiol: assessment of estrogenic activity.

Bisphenol-A (BPA) and 17α-ethinylestradiol (EE2) are considered endocrine disrupting compounds (EDC) and they may be harmful to the normal functioning of endocrine systems of humans and animals. Moreover, the presence of these compounds in superficial and groundwater may represent serious risks, even in low concentrations like ng·L-1. The objectives of this study were to remove BPA and EE2 from solutions containing a mixture of these compounds in ultrapure water at low concentrations through reverse osmosis (RO) membrane combined with a UV/H2O2 process. Furthermore, to assess the estrogenic activity reduction after such treatments, in vitro recombinant yeast-estrogen screen (YES) assay was used. The removal efficiencies of target micropollutants increased with the increase of H2O2 dosage. For RO permeate stream, they enhanced from 91% to 96% for EE2 and from 76% to 90% for BPA while, for the concentrate stream, from 70% to 81% for EE2 and 41% to 84% for BPA as the H2O2 concentration were increased from 100 to 1000 µg·L-1. The OH radicals' generation was the dominant factor in the degradation of EDC during the UV/H2O2 treatment since the photolysis itself was not enough to degrade BPA or EE2. The estrogenic activity reduction after UV/H2O2 treatment was high, ranging from 92% to 98% for the permeate stream and from 50% to 93% for the concentrate stream. The EE2 was responsible for the whole observed estrogenic activity since BPA does not present estrogenicity, by in vitro YES assay, in the concentrations observed.

Stoichiometric excesses of H2O2 as dosimetry strategy: proof of concept for UVC-H2O2, dark-Fenton, and UVC-Fenton.

Hydrochlorothiazide (HCT) is a pharmaceutical micropollutant highly toxic to the environment, being absolutely necessary to oxidize it completely to CO2. Here, the variables stoichiometric H2O2 excess for (a) degradation and (b) mineralization are defined and used as metric to quantify the dosimetry of the H2O2. So that, dose of H2O2 qualifies being under- and over-dose respectively for values below and above such standards. In this work, these concepts have been elucidated across AOPs regarding the H2O2 degradation excess, whereas only UVC-Fenton was used regarding the H2O2 mineralization excess. At a H2O2 mineralization excess of 0.68 (equivalent to degradation excess of 36.74), oxidation via UVC-H2O2 enables absolute (100%) HCT degradation within 60 min; however, the mineralization of HCT demonstrated limited optimization for all AOPs employed in the beaker-like reactor of this work, being the underlying reasons investigated hereby. At best, 26.70% HCT mineralization was observed within 60 min of UVC photo-Fenton using an initial 2.00 H2O2 mineralization excess. Such mineralization of 26.7% is unexpectedly low considering that, in addition, the residual H2O2 concentration almost fully depletes within 30 min of UVC-Fenton oxidation. Taken all that together, the loss of H2O2 due its decomposition induced by the risen temperature from 28 to 70ºC very likely were the underlying reason preventing better mineralization performance. We successfully demonstrated 18% of mean efficiency of radical •OH consumption signals that the overheating is indeed a designer problem with the photo-reactor since a well-refrigerated photo-reactor shows a mean efficiency of 38% for the same H2O2 excess.

A Detailed Study of Electronic and Dynamic Properties of Noble Gas-Oxygen Molecule Adducts.

In this work, the binding features of adducts formed by a noble gas (Ng = He, Ne, Ar, Kr, Xe, and Rn) atom and the oxygen molecule (O2) in its ground Σg-3, in the past target of several experimental studies, have been characterized under different theoretical points of view to clarify fundamental aspects of the intermolecular bond. For the most stable configuration of all Ng-O2 systems, binding energy has been calculated at the theory's CCSD(T)/aug-cc-pVTZ level and compared with the experimental findings. Rovibrational energies, spectroscopic constants, and lifetime as a function of temperature were also evaluated by adopting properly formulated potential energy curves. The nature of the interaction involved was deeply investigated using charge displacement analysis, symmetry-adapted perturbation theory (SAPT), and natural bond orbital (NBO) methods. In all adducts, it was found that the charge transfer plays a minor role, although O2 is an open shell species exhibiting a positive electron affinity. Obtained results also indicate that the dispersion attraction contribution is the main responsible for the complex stability.