O2 Pressure Research Articles

PdAg/CoFe2O4 Bimetallic Catalyst with High Selectivity for Glyceraldehyde in Glycerol Selective Oxidation Reaction

The catalytic oxidation of glycerol was investigated in assays with palladium-silver bimetallic nanoparticles (Pd-Ag) immobilized on cobalt ferrite (CoFe2O4). Bimetallic nanoparticles were prepared by the galvanic replacement method, immobilized on CoFe2O4 by wet impregnation. Bimetallic Pd-Ag nanoparticles with 35 wt.% Pd content effectively catalyzed the selective oxidation reaction of glycerol to glyceraldehyde. Catalytic oxidation was carried out at 60-80 °C for 2-4 h in an aqueous NaOH solution (NaOH:glycerol ratio = 4 mol:mol) under O2 pressure of 4 bar; the selectivity of glyceraldehyde reached 99.35% and the conversion of glycerol of 49.07% at a temperature of 60 °C and a reaction time of 2 h. Glyceric acid and traces of tartronic acid and mesoxalic acid were also detected. The catalyst was also very stable, showing activity up to 4 runs without significant loss of activity and selectivity.

The effect of O2 pressure on phase formation and superconductivity properties of Tl-based HTS

Thallium-based high-temperature superconductors exhibit excellent superconductivity performance (Tc, Jc). Formation of the Tl-based superconducting materials critically depends on the used precursor and synthesis conditions. In the present investigation, we used the in situ polymerization method for synthesizing high-purity and reaction-ability precursors. We find the critical dependence of Tl-based superconductor phase formation on the quantity of applied oxygen pressure. The experimental results showed that the Tl-1223 phase formed at an oxygen gas pressure at 1 to 2 atm, Tl-2223 phase at 3 atm, and Tl-2212 phase at 4 to 8 atm.

The sensitivity of the equatorial pacific ODZ to particulate organic matter remineralization in a climate model under pre-industrial conditions

Marine oxygen plays a fundamental role in regulating the transfer of organic carbon and nutrients to their dissolved inorganic forms, serving as the terminal electron acceptor for heterotrophic respiration. Oxygen can become limiting to these processes in coastal and open-ocean oxygen deficient zones (ODZs). The maintenance of ODZs depends on the balance between physical processes such as ventilation and biogeochemical processes such as remineralization. These two processes act in opposing directions on ODZs, with ventilation responsible for transporting oxygen from the surface, where it is near saturation with the partial pressure of O2 in the atmosphere, to deeper oxygen-depleted layers, and remineralization acting to consume oxygen through biogeochemical processes such as microbial degradation throughout the water column. Remineralization is represented in all CMIP6 models, but the actual parameterizations, as well as their magnitude, are widely varying.In this study, we examine the sensitivity to remineralization of the equatorial Pacific ODZ (O2<60μmol/kg) in a model; the NASA GISS Ocean Biogeochemical Model (NOBM-G) embedded in the NASA-GISS coupled atmosphere-ocean model. We find that increasing the remineralization rate shoals the ODZ onset depth (i.e. the regionally averaged upper bound of the ODZ), and decreases ODZ volume and regional-averaged thickness. Changes in biological consumption and vertical convergence of oxygen are identified as the primary contributors to changes in ODZ onset depth. ODZ thickness is mainly influenced by the shoaling of the bottom boundary of the ODZ, which decreases with maximum remineralization rate due to decreasing oxygen consumption and increasing horizontal oxygen convergence in deep waters. On the other hand, vertically-averaged ODZ area has a more complex, non-monotonic relationship with maximum remineralization rate. While these findings suggest an important role for remineralization in determining the shape of the ODZ in our model, the relative importance of remineralization vs. other physical parameterizations remains to be established. While our results reflect the structure of our ocean biogeochemical model, the relationship of remineralization to ODZ characteristics in other models should be examined to better inform model inter-comparisons.

Possibility of metallic cobalt formation in the oxide scale during high-temperature oxidation of Co-27Cr-6Mo alloy in air

Abstract Co-based alloys are known to be high oxidation-resistant material and used in several high temperature applications. During high temperature oxidation, duplex oxides containing Co and Cr were formed. It was thermodynamically elucidated that when the growing scale was thick enough, the partial pressure of O2 in the scale dropped. Then, the reduction of CoO occurred for promoting O2 which was responsible for Cr2O3 production. This work experimentally proved this point by in situ characterising Co-27Cr-6Mo at high temperatures in air by X-ray diffractometer in a grazing incident mode and metallic Co was confirmed to be formed by the reduction of CoO consistent with the image taken and analysed by field emission scanning electron microscope, energy-dispersive X-ray, and electron backscatter diffraction. Furthermore, the change in lattice parameter and the phase transition were observed when the temperature was altered.

A Murine Model of Vesicant-Induced Acute Lung Injury.

Burn injuries including those caused by chemicals can result in systemic effects and acute lung injury (ALI). Cutaneous exposure to Lewisite, a warfare and chemical burn agent, also causes ALI. To overcome the limitations in conducting direct research on Lewisite-induced ALI in a laboratory setting, an animal model was developed using phenylarsine oxide (PAO) as a surrogate for Lewisite. Due to lack of a reliable animal model mimicking the effects of such exposures, development of effective therapies to treat such injuries is challenging. We demonstrated that a single cutaneous exposure to PAO resulted in disruption of the alveolar-capillary barrier as evidenced by elevated protein levels in the bronchoalveolar lavage fluid (BALF). BALF supernatant of PAO-exposed animals had increased levels of high mobility group box 1, a damage associated molecular pattern molecule. Arterial blood-gas measurements showed decreased pH, increased PaCO2, and decreased partial pressure of arterial O2, indicative of respiratory acidosis, hypercapnia, and hypoxemia. Increased protein levels of interleukin (IL)-6, CXCL-1, CXCL-2, CXCL-5, granulocyte-macrophage colony-stimulating factor, CXCL-10, leukemia inhibitory factor, leptin, IL-18, CCL-2, CCL-3, and CCL-7 were observed in the lung of PAO-exposed mice. Further, vascular endothelial growth factor levels were reduced in the lung. Pulmonary function evaluated using a flexiVent showed a downward shift in the pressure-volume loop, decreases in static compliance and inspiratory capacity, increases in respiratory elastance and tissue elastance. These changes are consistent with an ALI phenotype. These results demonstrate that cutaneous PAO exposure leads to ALI and that the model can be used as an effective surrogate to investigate vesicant-induced ALI. SIGNIFICANCE STATEMENT: This study presents a robust model for studying ALI resulting from cutaneous exposure to PAO, a surrogate for the toxic vesicating agent Lewisite. The findings in this study mimic the effects of cutaneous Lewisite exposure, providing a reliable model for investigating mechanisms underlying toxicity. The model can also be used to develop medical countermeasures to mitigate ALI associated with cutaneous Lewisite exposure.

Hypoxia sensing in the body: An update on the peripheral and central mechanisms.

An adequate supply of O2 is essential for the maintenance of cellular activity. Systemic or local hypoxia can be experienced during decreased O2 availability or associated with diseases, or a combination of both. Exposure to hypoxia triggers adjustments in multiple physiological systems in the body to generate appropriate homeostatic responses. However, with significant reductions in the arterial partial pressure of O2, hypoxia can be life-threatening and cause maladaptive changes or cell damage and death. To mitigate the impact of limited O2 availability on cellular activity, O2 chemoreceptors rapidly detect and respond to reductions in the arterial partial pressure of O2, triggering orchestrated responses of increased ventilation and cardiac output, blood flow redistribution and metabolic adjustments. In mammals, the peripheral chemoreceptors of the carotid body are considered to be the main hypoxic sensors and the primary source of excitatory feedback driving respiratory, cardiovascular and autonomic responses. However, current evidence indicates that the CNS contains specialized brainstem and spinal cord regions that can also sense hypoxia and stimulate brain networks independently of the carotid body inputs. In this manuscript, we review the discoveries about the functioning of the O2 chemoreceptors and their contribution to the monitoring of O2 levels in the blood and brain parenchyma and mounting cardiorespiratory responses to maintain O2 homeostasis. We also discuss the implications of the chemoreflex-related mechanisms in paediatric and adult pathologies.

A selection approach using high‑oxygen and pond-mimicking culture conditions increases biomass productivity in the industrially relevant diatom Nitzschia inconspicua str. hildebrandi

To meet the energy and food challenges of the 21st century, renewable and sustainable sources of fuel and nutrients are required. Microalgae offer promise in meeting these challenges but must achieve higher rates of areal productivity to compete with fully scaled, existing industries. In this study, we used selective O2 pressure to attain a ∼90 % increase in areal biomass productivity relative to the parental strain in the diatom Nitzschia inconspicua str. hildebrandi under pond-mimicking conditions with high O2 stress. The resulting culture line (GAI-337) was tested further for dilution time, culture density, CO2 supplementation, pH, temperature, and dissolved O2 concentration under outdoor pond-mimicking conditions to improve areal productivities. These experiments yielded an optimum harvest and dilution time just after sunset, ∼0.45 g AFDW L−1 initial culture density for maximal productivities, no requirement for CO2 gas supplementation or pH control, maximal performance under a diel temperature curve going from 24 °C at night to 36 °C during the day, and benefits from some O2 removal from the culture by bubbling with air. Using pond-mimicking laboratory bioreactors, N. inconspicua GAI-337 achieved ∼42 g AFDW m−2 d−1, placing it among the most productive microalgal strains tested to date. Nutrient limitation experiments resulted in a biomass composition with 36 % of AFDW comprised of lipids (measured as FAMEs) that equated to ∼160 Gallons of Gasoline Equivalent energy per ton AFDW, highlighting the potential of GAI337 as a promising renewable fuel feedstock strain.

Identification of oxidized platinum single atoms on chlorinated γ–alumina support by density functional theory calculations and X-ray absorption spectroscopy

The existence and nature of oxidized Pt single atoms (SA) are unraveled on two γ-Al2O3 supported Pt catalysts (0.3 wt%) containing two chlorine contents (0.1 and 1.4 wt%) characterized by HR-HAADF-STEM and HERFD-XANES/EXAFS after a calcination treatment at 520 °C. Pt SA are revealed as PtOxCly complexes where the number of oxygen (x) and chlorine (y) ligands directly depends on the chlorine content. In order to interpret these experimental observations and provide coherent atomic structures for these PtOxCly complexes, the thermodynamic stability of the oxidized Pt SA species supported on the (100) surface model of γ-Al2O3 is determined by density functional theory (DFT) calculations as a function of the calcination conditions determined by the temperature, and partial pressures of H2O, HCl and O2. It is shown that various ligands such as Cl, OH, O (from the alumina surface or as extra-ligands) and H2O are coordinated to Pt depending on the conditions and chlorine content. Various square planar and square-based pyramidal PtOxCly species such as PtO2, PtOCl2, PtCl4 are found to be stable in calcination conditions, while octahedral Pt(OH)xCl4-x(H2O) are stabilized in XAS recording conditions. The features of these DFT simulated octahedral Pt SA species are successfully compared to XAS data. On one hand, based on thermodynamics arguments, we proposed models of supported complexes in agreement with EXAFS coordination numbers and distances (Pt-O, Pt-Cl and Pt-Al). On the other hand, the simulated XANES spectra at the Pt L3-edge for these complexes match well with the experimental HERFD-XANES and reveal that the bump feature observed between 11575 eV and 11585 eV (post-edge signal) is a tracer of the amount of Cl coordinated to Pt SA.

Enhancing aerobic oxidation of C–H bonds through efficient catalysis of iron MOF–derived Fe3C nanoparticles embedded in porous carbon catalysts

Developing efficient heterogeneous catalysts for the aerobic oxidation of C–H bonds using oxygen molecule as an oxidant to produce value–added aryl ketones is a challenging task. In this study, a series of cementite–iron–carbon composites (referred to as Fe–C–T, where T represents the pyrolysis temperature) were synthesized using a metal–organic–framework–mediated sacrificial template strategy. The Fe–C–T composites consist of highly dispersed Fe/(Fe3C or Fe2O3) nanoparticles surrounded by graphitic carbon on porous carbon supports. Under mild reaction conditions (1 atm of O2 pressure, 353 K, 12 h), with tert–butyl hydroperoxide (0.25 equiv.) as the initiator in a green solvent water, the prepared Fe–C–973 achieved a high conversion of 98.4 % for ethylbenzene and a selectivity of 98.7 % for acetophenone. This performance was markedly superior to the comparable Fe–C–873 and Fe–C–1073, as well as the commercially available Fe–based catalysts. Kinetic studies revealed that the catalytic system followed first–order kinetics for the substrate ethylbenzene, and the activation energy over Fe–C–973 was remarkably low of 40.4 kJ/mol. The highly distributed Fe3C nanoparticles embedded in the porous carbon framework were identified as the most active sites for the reaction.

Insulin resistance without coexisting hyperglycaemia is not independently associated with cardiorespiratory fitness or its components in women

Abstract Background Insulin resistance (IR) is a globally prevalent condition in which tissues’ response to insulin is diminished. Cardiorespiratory fitness (peak O2 uptake (VO2peak)) is determined by Fick’s equation (VO2 = cardiac output (CO) × arteriovenous O2 difference (Ca-vO2) = heart rate × stroke volume (SV) × Ca-vO2) and diffusion law (VO2 = diffusive O2 conductance (DO2) × constant k × venous O2 pressure (PvO2)). Several studies suggest an association between IR and decreased VO2peak, but the association has been questioned by analyses taking account of body size and composition, and potential mechanisms behind the association are unknown. Purpose To test a hypothesis that IR is not independently associated with VO2peak or its components. Methods Fifty of 144 women, who had participated in baseline experiments of three intervention studies, were included in this retrospective cross-sectional study; see Table 1 for subject characteristics. The inclusion criteria were age 18-40 years, body mass index 18.5-40 kg/m2, Caucasian origin, and available data on key measures. The exclusion criteria were diseases, medications, and other factors possibly affecting VO2peak. We measured haemoglobin, fasting glucose, and fasting insulin concentrations (blood), assessed IR (homeostasis model assessment (HOMA-IR)), and measured body size and composition (bioimpedance). The subjects performed an incremental cycling test to volitional fatigue; we measured ventilatory gas exchange (spiroergometry), arterial O2 saturation (oximetry), and SV and CO (impedance cardiography), and calculated Ca-vO2, DO2, and PvO2. We analysed VO2peak and its components as absolute (e.g. L/min) and ratiometrically scaled values (e.g. mL/min/kg), and when appropriate, also as allometrically scaled values (e.g. mL/min/kg^x, where 0 &amp;lt; x &amp;lt; 1) after identifying optimal variable-specific exponents. Results VO2peak scaled to body mass (BM) as well as SVpeak and COpeak scaled to body surface area (BSA) were inversely associated with the body size variables they were scaled to (all P &amp;lt; 0.013). Contrariwise, this was not the case when we optimally scaled VO2peak to fat-free mass (FFM), SVpeak to FFM^0.55, COpeak to FFM^0.50, and DO2peak to FFM (all 0.066 &amp;lt; P &amp;lt; 0.977). HOMA-IR was inversely associated with VO2peak scaled to BM but not in a multivariate analysis, whereas HOMA-IR was not associated with VO2peak scaled to FFM (Table 2); we made alike observations with SVpeak and COpeak (data not shown). Further, VO2peak scaled to BM as well as SVpeak and COpeak scaled to BSA were or tended to be up to 15 % higher in a group with HOMA-IR&amp;lt;3.0 than in a group with HOMA-IR≥3.0, while other peak exercise data did not differ between the groups (Table 1). Conclusion Body size and composition significantly affect conclusions drawn regarding VO2peak and its components. Taking this into account, IR without coexisting hyperglycaemia is not independently associated with VO2peak or its components in women.Table 1Table 2

The Use of Acid Leaching to Recover Metals from Tailings: A Review

Mine tailings deposits are often overlooked by the industry, posing significant environmental challenges due to chemical hazards and inadequate maintenance. Nevertheless, such mineral deposits hold considerable economic potential for processing, and the adoption of innovative technologies may also address critical chemical and physical stability issues. Existing research has demonstrated the feasibility of recovering target metals—i.e., copper, iron, manganese, cobalt, zinc, and others—through the application of acid leaching techniques with consistently high yields and metal recovery rates. Therefore, a compilation was carried out from 2008 onwards, on working conditions such as leaching agent, acid concentration, oxidizing-reducing reagent, particle size, O2 pressure, stirring speed, solid–liquid ratio, temperature, and leaching time. At present, there are no reviews on the recovery of metals via acid leaching in tailings, so this study can serve as support for future researchers who want to project themselves in this area, ordering the procedures and the results obtained by the research carried out. Regarding the evaluation, it can be commented that research has shown that acid leaching of tailings has achieved recoveries of over 90% in different metals, such as Zn, Cu, and Fe, which indicates that the treatment is efficient and recommended for different types of tailings.

Study of reactive electron beam deposited tantalum penta oxide thin films with spectroscopic ellipsometry and atomic force microscopy

The optical and surface morphological properties of thin films are profoundly influenced by the deposition technique and the various process parameters employed. In present work, several tantalum penta oxide thin films have been fabricated using reactive electron beam evaporation at varying oxygen (O2) pressures, ranging from 3 × 10−3 Pa to 8 × 10−2 Pa. Refractive index, extinction coefficient, and voids in thin film microstructure were determined through the analysis of spectroscopic ellipsometric measurements. The refractive index, which exhibits a decreasing trend, varies between 1.859 and 2.067, with the exception being the lowest O2 pressure. The variation has been explained in terms of varying oxygen content and voids in the thin films. The extinction coefficient exhibits a decreasing trend due to the increasing oxidation of tantalum, except at O2 pressure of 8 × 10−2 Pa. Increase in the extinction coefficient at this pressure could be due to porous film microstructure, resulting in dominant light scattering. Variation of film density which is similar to that of refractive index, has been attributed to the varying oxidation of tantalum (Ta) and film porosity. Surface root mean square (rms) roughness, correlation length and Hurst parameter, have been derived from suitable analysis of atomic force microscopy measurements. Variations of correlation length and rms roughness have been explained in terms of varying surface shadowing effects and oxidation of Ta with varying O2 pressure.

Low oxygen in inspired air causes severe cerebrocortical hypoxia and cell death in the cerebral cortex of awake rats

Type 1 respiratory failure (T1RF) is associated with secondary acute brain injury (sABI). The underlying mechanisms of sABI could include injury to brain cells mediated either by hypoxia or by lung injury-triggered inflammation. To elucidate to what extent T1RF causes hypoxia and a consequent hypoxic injury in the brain in the absence of lung injury, we exposed healthy, conscious Sprague-Dawley rats to 48 h long low partial pressure of O2 in inspired air (PiO2) (7.5–8 % O2 in N2, CO2 < 0.5 %, normal barometric pressure) and measured the partial pressure of oxygen in the premotor cortex (PtO2), cerebral blood flow (CBF), lactate concentrations, and cell death. Low PiO2 significantly affected PtO2, which was 52.3 (SD 2.1) mmHg when PiO2 was normal but declined to 6.4 (SD 3.8) mmHg when PiO2 was low for 1 h. This was accompanied by increased lactate concentrations in plasma, CSF, and premotor cortex. Low PiO2 elevated the number of dead cells in the cerebral cortex from 5.6 (SD 4.8) % (when PiO2 was normal) to 20.5 (SD 4.1) % and 32.37 (SD 6.5) % after 24 h and 48 h exposure to low PiO2, respectively. The Mann-Kendall test could not detect any monotonic increase or decrease in pial blood flow during the 48 h exposure to low PiO2. In summary, our findings suggest that exposure to low PiO2 caused a severe hypoxia in the cerebral cortex, which triggers a massive cell death. Since these conditions mimic T1RF, hypoxic injury could be an important underlying cause of T1RF-induced sABI.

Diabetes related phenotypes and their influence on outcomes of patients with corona virus disease 2019 (COVID-19)

IntroductionDiabetes mellitus (DM) is associated with severe forms of COVID-19 but little is known about the diabetes—related phenotype considering pre-admission, on-admission and data covering the entire hospitalization period.MethodsWe analyzed COVID-19 inpatients (n = 3327) aged 61.2(48.2–71.4) years attended from March to September 2020 in a public hospital.ResultsDM group (n = 1218) differed from Non-DM group (n = 2109) by higher age, body mass index (BMI), systolic blood pressure and lower O2 saturation on admission. Gender, ethnicity and COVID-19-related symptoms were similar. Glucose and several markers of inflammation, tissue injury and organ dysfunction were higher among patients with diabetes: troponin, lactate dehydrogenase, creatine phosphokinase (CPK), C-reactive protein (CRP), lactate, brain natriuretic peptide, urea, creatinine, sodium, potassium but lower albumin levels. Hospital (12 × 11 days) and intensive care unit permanence (10 × 9 days) were similar but DM group needed more vasoactive, anticoagulant and anti-platelet drugs, oxygen therapy, endotracheal intubation and dialysis. Lethality was higher in patients with diabetes (39.3% × 30.7%) and increased with glucose levels and age, in male sex and with BMI < 30 kg/m2 in both groups (obesity paradox). It was lower with previous treatment with ACEi/BRA in both groups. Ethnicity and education level did not result in different outcomes between groups. Higher frequency of comorbidities (hypertension, cardiovascular/renal disease, stroke), of inflammatory (higher leucocyte number, RCP, LDH, troponin) and renal markers (urea, creatinine, potassium levels and lower sodium, magnesium) differentiated lethality risk between patients with and without diabetes.ConclusionsComorbidities, inflammatory markers and renal disfunction but not Covid-19-related symptoms, obesity, ethnicity and education level differentiated lethality risk between patients with and without diabetes.

Effect of temperature on the electrode overpotential of molten carbonate electrolysis and fuel cells with inert-gas step addition method

This study explores molten carbonate electrolysis and fuel cell behaviour across temperatures from 823 to 973 K using steady-state polarization (SSP), electrochemical impedance spectroscopy (EIS), and inert-gas step addition (ISA) techniques. The findings reveal that total voltage loss decreases with rising temperature in fuel cell (FC) and electrolysis (EC) modes. The ohmic loss similarly declines as temperature increases. The ISA method determines the gas-phase mass transfer-induced overpotential, which increases as temperature increases in both modes at the hydrogen electrode (HE). This indicates that pore diffusion resistance strongly affects the HE in both modes. The liquid-phase mass transfer-induced overpotential at the oxygen electrode (OE) exhibits a much smaller value in EC mode than in FC mode at all temperatures. The increased O2 and CO2 partial pressures and decomposition of sufficient amounts of carbonate electrolytes to generate O2 in EC mode would reduce the liquid-phase resistance and its induced overpotential at the OE in the temperature range.

Ventilatory responses to independent and combined hypoxia, hypercapnia and hypobaria in healthy pre-term-born adults.

Pre-term birth is associated with physiological sequelae that persist into adulthood. In particular, modulated ventilatory responsiveness to hypoxia and hypercapnia has been observed in this population. Whether pre-term birth per se causes these effects remains unclear. Therefore, we aimed to assess pulmonary ventilation and blood gases under various environmental conditions, comparing 17 healthy prematurely born individuals (mean ± SD; gestational age, 28 ± 2weeks; age, 21 ± 4years; peak oxygen uptake, 48.1 ± 11.2mlkg-1 min-1 ) with 16 well-matched adults born at term (gestational age, 40 ± 1weeks; age, 22 ± 2years; peak oxygen uptake, 51.2 ± 7.7mlkg-1 min-1 ). Participants were exposed to seven combinations of hypoxia/hypobaria (equivalent to ∼3375m) and/or hypercapnia (3% CO2 ), at rest for 6min. Pulmonary ventilation, pulse oxygen saturation and the arterial partial pressures of O2 and CO2 were similar in pre-term and full-term individuals under all conditions. Higher ventilation in hypoxia compared to normoxia was only observed at terrestrial altitude, despite an equivalent (normobaric) hypoxic stimulus administered at sea level (0.138 ). Assessment of oscillations in key variables revealed that combined hypoxic hypercapnia induced greater underlying fluctuations in ventilation in pre-term individuals only. In general, higher pulse oxygen saturation fluctuations were observed with hypoxia, and lower fluctuations in end-tidal CO2 with hypercapnia, despite similar ventilatory oscillations observed between conditions. These findings suggest that healthy prematurely born adults display similar overall ventilation to their term-born counterparts under various environmental stressors, but that combined ventilatory stimuli could induce an irregular underlying ventilatory pattern. Moreover, barometric pressure may be an important factor when assessing ventilatory responsiveness to moderate hypoxic stimuli. KEY POINTS: Evidence exists for unique pulmonary and respiratory function under hypoxic conditions in adult survivors of pre-term birth. Whether pre-term birth per se causes these differences requires a comparison of conventionally healthy prematurely born adults with an appropriately matched sample of term-born individuals. According to the present data, there is no difference between healthy pre-term and well-matched term-born individuals in the magnitude of pulmonary ventilation or arterial blood gases during independent and combined hypobaria, hypoxia and hypercapnia. Terrestrial altitude (hypobaria) was necessary to induce differences in ventilation between normoxia and a hypoxic stimulus equivalent to ∼3375m of altitude. Furthermore, peak power in pulse oxygen saturation was similar between hypobaric normoxia and normobaric hypoxia. The observed similarities between groups suggest that ventilatory regulation under various environmental stimuli is not impaired by pre-term birth per se. Instead, an integrated combination of neonatal treatment strategies and cardiorespiratory fitness/disease status might underlie previously observed chemosensitivity impairments.

Molecular simulation study on permeation behavior of small molecules in graphyne/polypyrrole mixed matrix membrane

AbstractThe research on the permeation behavior of small molecules in mixed matrix membranes (MMMs) is an important part of the research of MMMs. Graphyne, a new two‐dimensional carbon material, was used as the filler, and polypyrrole was used as polymer matrix to construct a MMM. In order to clarify the permeation behavior of common small molecules in MMM at room temperature and constant pressure, the adsorption and diffusion properties of H2O, CO2, and O2 in graphyne/polypyrrole MMM were investigated by combining the Giant Canonical Monte Carlo (GCMC) and molecular dynamics (MD). The results show that: (1) the order of adsorption capacity of the three molecules is H2O &gt; CO2 &gt; O2; (2) the diffusion ability of the three molecules is influenced by the doping content of graphyne. Oxygen diffusion and permeation in MMMs are optimal when the graphyne filling level is 15%. The filling of graphyne affects the permeation of gases. It will shed light on application areas such as coating membranes for electronics in special environments, gas separation membranes, and gas sensor membranes.Highlights A new two‐dimensional carbon nano filler—graphyne was used. A simulation method using a combination of GCMC and MD. The diffusion and permeation behaviors are analyzed from multiple perspectives. The permeation behavior conforms to the solution‐diffusion theory. The graphyne‐filled MMM is conducive to oxygen molecular diffusion.

Under the sea: How can we use heart rate and accelerometers to remotely assess fish welfare in salmon aquaculture?

Recent advances in bio-sensing technologies open for new possibilities to monitor and safeguard the welfare of fishes in aquaculture. Yet before taken into practice, the applicability of all novel biosensors must be validated, and the breadth of their potential uses must be investigated. Here, we investigated how ECG and accelerometry-derived parameters measured using bio-loggers, such as heart rate, acceleration and variance of acceleration, relate to O2 consumption rate (MO2) and blood borne indicators of stress and tissue damage to determine how biologgers may be used to estimate stress and welfare. To do this, we instrumented 13 fish with a biologger and an intravascular catheter and subjected them to a swimming protocol followed by a stress protocol throughout which the physiological parameters were measured and analyzed a posteriori. Additionally, based on the empirical data obtained, we calculated the mathematical relationships between the bio-logger data and the other parameters and tested the relationship between the calculated parameters using the linear regression algorithms and the measured parameters. Our results show that acceleration is a good proxy for swimming activity as it is closely related to tail beat frequency. In addition, we show that heart rate, acceleration and variance of acceleration all can be used as predictors for metabolic rate. Accelerometry based data, especially variance of acceleration, significantly explain some of the variation in venous partial pressure of O2, blood lactate and plasma cortisol concentration. Variance of acceleration also significantly explains some of the variation in pH and mean corpuscular hemoglobin concentration. These relationships are explained by variance of acceleration being a good indicator of the onset of burst-swimming activity, which is often followed by acid-base imbalances and release of catecholamines. The results herein indicate that bio-logger data can be used to extrapolate a range of stress-related physiological events when these are accompanied by increases in activity and highlight the great potential of biosensors for monitoring fish welfare.

Enhanced dual superconducting and ferromagnetic properties of YBCO film tuned with boron and oxygen partial pressures

This study reports the dual enhancement of superconductivity and ferromagnetic properties of YBCO films for the first time. These dual enhanced properties have been achieved by tunning YBCO films with dopant boron and oxygen partial pressures. Thin films of YBa2Cu3-xBxO7-y with different B concentrations and oxygen partial pressures were fabricated by electro-spin coating. The systematic optimization of B concentration and oxygen partial pressure of YBCO films were studied through microstructural, electrical, optical, and magnetic properties. In particular, YBCO film doped with 20 mol% B and 20 SCCM O2 pressure showed excellent superconducting and magnetic properties. The breakthrough of this study in the films YBa2Cu2.4B0.6O7−y/20 SCCM, not only displayed enhanced superconducting properties but also ferromagnetic properties at near transition temperature (Tc) (i.e., 109 K). The magnetic moment values YBa2Cu2.4B0.6O7−y/20 SCCM films achieved ≈ 0.65 μB/mol, which is two order increment of films prepared without oxygen partial pressure. The dopant boron and oxygen partial pressure provide a new pathway for tuning the superconducting and ferromagnetic properties of YBCO thin films.

Optimization of Wall-Conditioning Techniques on the MT-II Tokamak

The MT-II is a small spherical tokamak that is currently under construction at the Pakistan Tokamak Plasma Research Institute. Wall conditioning of the MT-II vacuum vessel (VV) is an essential step to achieve a good quality vacuum for plasma experiments. This study presents an overview of the wall-conditioning techniques implemented on the MT-II VV, including baking and glow discharge cleaning (GDC). Prior to wall conditioning, the system is checked via a helium leak test machine and residual gas analyzer (RGA) to identify and remove leaks. The VV walls are baked at ~180 °C to get rapid desorption of water vapors and other impurities. After the baking process, the partial pressure of most of the carbon- and oxygen-containing impurities is reduced. In particular, the partial pressure of water vapors is reduced by 93%. Consequently, the total leak and outgassing rate is significantly reduced. To further improve the vacuum condition in the vessel, hydrogen GDC is carried out. The fill hydrogen pressure and anode voltage are optimized to get a stable glow discharge. The RGA scan shows that GDC reduces the partial pressure of H2O, O2, and CO2 by 57%, 63%, and 51%, respectively. The results signify that baking and GDC are effective techniques for wall conditioning of the MT-II VV.