Oxygen Partial Pressure Values Research Articles

Spatial O2 Profile in Coix lacryma-jobi and Sorghum bicolor along the Gas Diffusion Pathway under Waterlogging Conditions.

While internal aeration in plants is critical for adaptation to waterlogging, there is a gap in understanding the differences in oxygen diffusion gradients from shoots to roots between hypoxia-tolerant and -sensitive species. This study aims to elucidate the differences in tissue oxygen concentration at various locations on the shoot and root between a hypoxia-tolerant species and a -sensitive species using a microneedle sensor that allows for spatial oxygen profiling. Job's tears, a hypoxia-tolerant species, and sorghum, a hypoxia-susceptible species, were tested. Plants aged 10 days were acclimated to a hypoxic agar solution for 12 days. Oxygen was profiled near the root tip, root base, root shoot junction, stem, and leaf. An anatomical analysis was also performed on the roots used for the O2 profile. The oxygen partial pressure (pO2) values at the root base and tip of sorghum were significantly lower than that of the root of Job's tears. At the base of the root of Job's tears, pO2 rapidly decreased from the root cortex to the surface, indicating a function to inhibit oxygen leakage. No significant differences in pO2 between the species were identified in the shoot part. The root cortex to stele ratio was significantly higher from the root tip to the base in Job's tears compared to sorghum. The pO2 gradient began to differ greatly at the root shoot junction and root base longitudinally, and between the cortex and stele radially, between Job's tears and sorghum. Differences in the root oxygen retention capacity and the cortex to stele ratio are considered to be related to differences in pO2.

Oxygen targets and 6-month outcome after out of hospital cardiac arrest: a pre-planned sub-analysis of the targeted hypothermia versus targeted normothermia after Out-of-Hospital Cardiac Arrest (TTM2) trial

BackgroundOptimal oxygen targets in patients resuscitated after cardiac arrest are uncertain. The primary aim of this study was to describe the values of partial pressure of oxygen values (PaO2) and the episodes of hypoxemia and hyperoxemia occurring within the first 72 h of mechanical ventilation in out of hospital cardiac arrest (OHCA) patients. The secondary aim was to evaluate the association of PaO2 with patients’ outcome.MethodsPreplanned secondary analysis of the targeted hypothermia versus targeted normothermia after OHCA (TTM2) trial. Arterial blood gases values were collected from randomization every 4 h for the first 32 h, and then, every 8 h until day 3. Hypoxemia was defined as PaO2 < 60 mmHg and severe hyperoxemia as PaO2 > 300 mmHg. Mortality and poor neurological outcome (defined according to modified Rankin scale) were collected at 6 months.Results1418 patients were included in the analysis. The mean age was 64 ± 14 years, and 292 patients (20.6%) were female. 24.9% of patients had at least one episode of hypoxemia, and 7.6% of patients had at least one episode of severe hyperoxemia. Both hypoxemia and hyperoxemia were independently associated with 6-month mortality, but not with poor neurological outcome. The best cutoff point associated with 6-month mortality for hypoxemia was 69 mmHg (Risk Ratio, RR = 1.009, 95% CI 0.93–1.09), and for hyperoxemia was 195 mmHg (RR = 1.006, 95% CI 0.95–1.06). The time exposure, i.e., the area under the curve (PaO2-AUC), for hyperoxemia was significantly associated with mortality (p = 0.003).ConclusionsIn OHCA patients, both hypoxemia and hyperoxemia are associated with 6-months mortality, with an effect mediated by the timing exposure to high values of oxygen. Precise titration of oxygen levels should be considered in this group of patients.Trial registration: clinicaltrials.gov NCT02908308, Registered September 20, 2016.

Sequential treatment of severe pneumonia with respiratory failure and its influence on respiratory mechanical parameters and hemodynamics.

BACKGROUNDThe pathophysiological characteristics of severe pneumonia complicated by respiratory failure comprise pulmonary parenchymal changes leading to ventilation imbalance, alveolar capillary injury, pulmonary edema, refractory hypoxemia, and reduced lung compliance. Prolonged hypoxia can cause acid-base balance disorder, peripheral circulatory failure, blood-pressure reduction, arrhythmia, and other adverse consequences.AIMTo investigate sequential mechanical ventilation’s effect on severe pneumonia complicated by respiratory failure. METHODSWe selected 108 patients with severe pneumonia complicated by respiratory failure who underwent mechanical ventilation between January 2018 and September 2020 at the Luhe Hospital’s Intensive Care Unit and divided them into sequential and regular groups according to a randomized trial, with each group comprising 54 patients. The sequential group received invasive and non-invasive sequential mechanical ventilation, whereas the regular group received invasive mechanical ventilation. Blood-gas parameters, hemodynamic parameters, respiratory mechanical parameters, inflammatory factors, and treatment outcomes were compared between the two groups before and after mechanical-ventilation treatment. RESULTSThe arterial oxygen partial pressure and stroke volume variation values of the sequential group at 24, 48, and 72 h of treatment were higher than those of the conventional group (P < 0.05). The carbon dioxide partial pressure value of the sequential group at 72 h of treatment and the Raw value of the treatment group at 24 and 48 h were lower than those of the conventional group (P < 0.05). The pH value of the sequential group at 24 and 72 h of treatment, the central venous pressure value of the treatment at 24 h, and the Cst value of the treatment at 24 and 48 h were higher than those of the conventional group (P < 0.05). The tidal volume in the sequential group at 24 h of treatment was higher than that in the conventional group (P < 0.05), the measured values of interleukin-6 and tumor necrosis factor-α in the sequential group at 72 h of treatment were lower than those in the conventional group (P < 0.05), and the total time of mechanical ventilation in the sequential group was shorter than that in the conventional group, with a statistically significant difference (P < 0.05).CONCLUSIONTreating severe pneumonia complicated by respiratory failure with sequential mechanical ventilation is more effective in improving respiratory system compliance, reducing inflammatory response, maintaining hemodynamic stability, and improving patient blood-gas levels; however, from this study’s perspective, it cannot reduce patient mortality.

Randomized controlled trial of low vs high oxygen during neonatal anesthesia: Oxygenation, feasibility, and oxidative stress.

BackgroundTo reduce risk for intermittent hypoxia a high fraction of inspired oxygen is routinely used during anesthesia induction. This differs from the cautious dosing of oxygen during neonatal resuscitation and intensive care and may result in significant hyperoxia.AimIn a randomized controlled trial, we evaluated oxygenation during general anesthesia with a low (23%) vs a high (80% during induction and recovery, and 40% during maintenance) fraction of inspired oxygen, in newborn infants undergoing surgery.MethodThirty‐five newborn infants with postconceptional age of 35–44 weeks were included (17 infants in low and 18 in high oxygen group). Oxygenation was monitored by transcutaneous partial pressure of oxygen, pulse oximetry, and cerebral oxygenation. Predefined SpO2 safety targets dictated when to increase inspired oxygen.ResultsAt start of anesthesia, oxygenation was similar in both groups. Throughout anesthesia, the high oxygen group displayed significant hyperoxia with higher (difference−20.3 kPa, 95% confidence interval (CI)—28.4 to 12.2, p < .001) transcutaneous partial pressure of oxygen values than the low oxygen group. While SpO2 in the low oxygen group was lower (difference − 5.8%, 95% CI –9.3 to –2.4, p < .001) during anesthesia, none of the infants spent enough time below SpO2 safety targets to mandate supplemental oxygen, and cerebral oxygenation was within the normal range and not statistically different between the groups. Analysis of the oxidative stress biomarker urinary F2‐Isoprostane revealed no differences between the low and high oxygen group.ConclusionWe conclude that in healthy newborn infants, use of low oxygen during general anesthesia was feasible, while the prevailing practice of using high levels of inspired oxygen resulted in significant hyperoxia. The trade‐off between careful dosing of oxygen and risks of hypo‐ and hyperoxia in neonatal anesthesia should be further examined.

Room temperature ferromagnetism in oxygen-deficient gallium oxide films with cubic spinel structure

Oxygen-defective gallium oxide (Ga2O3-x with 0.4 < x < 0.7) thin films with cubic spinel structure were deposited on c-cut epi-polished sapphire wafers using thermal evaporation technique by keeping specific values of oxygen partial pressure in the evaporation chamber. The preparation method and post-treatment conditions induced distinct oxygen stoichiometries in the films which exhibit a ferromagnetic-like behavior at room temperature. Despite the measured saturation magnetization values do not exhibit a straightforward correlation to the oxygen stoichiometry of the films, the presence of oxygen vacancies and defects is presumably the origin of the unconventional magnetic behavior. Strong magnetic irreversibility exhibit by the magnetization measurements performed using field-cooling and zero-field-cooling protocols indicate the presence of disordered magnetic moment distributions which are likely non-collinear. Theoretical and experimental results available in the literature corroborate with the assumptions that oxygen vacancies and defects appear as the main reason for room-temperature ferromagnetism. All films exhibit soft magnetic behavior at room temperature, exhibiting remanent magnetizations between 7% and 20% of the saturation magnetization which saturated magnetic moments is estimated as 0.43 and 1.24 Bohr magneton per oxygen vacancy. The present results extend the functionalities of this interesting material, which is already investigated for applications in several technological areas, for possible uses in the areas of spintronics and emerging areas of the optospintronics.

Fabrication and characterization of micro-tubular solid oxide fuel cells with yttria stabilized zirconia and Hafnia-Erbia co-doped bismuth oxide bilayer electrolyte

Current solid oxide fuel cell (SOFC) technology relies on YSZ electrolyte material due to its high stability under SOFC operation conditions. However, the ionic conductivity of YSZ decays as the operation temperature decreases to intermediate or low-temperature range.Commercialization of SOFC systems is hindered by the high manufacturing cost, which is directly related to the use of special and expensive system components because of the high operating temperatures of SOFCs. It is possible to use low-cost materials in system production if the operating temperature of SOFCs is reduced below 600 °C.In this study, we investigated the possibility of using 8% mol Yttria stabilized Zirconia (YSZ) and Hafnia-Erbia Co-doped Bismuth Oxide (HEB, ((Er2O3)0.20(Bi2O3)0.80)0.99-(HfO2)0.01) bilayer electrolyte configuration to lower the operating temperatures of SOFC to 600 °C and below. The cell performances at low-temperature region (T < 600 °C) are aimed to be increased with the additional HEB layer by the increased oxygen reduction kinetics on the air electrolyte side.Using a combination of thermoplastic extrusion and dip coating processes, four distinct cell types were created. Cells with monolayer and bilayer electrolyte were generated for each cathode type using two different cathode types, Lanthanum Strontium Manganate (LSM) and LSM-HEB. On the cell performance and operating temperatures, the impacts of electrolyte configuration and cathode type were examined. It was also explored whether the HEB material would be more effective as a second electrolyte or as a composite cathode if it was added to the LSM. Under various cell operating circumstances (different oxygen partial pressure values), several cell parameters such as the ohmic resistance, exchange current density, and anodic and cathodic saturation current densities were derived by fitting the experimentally recorded current density–voltage curves into the polarization model. The polarization resistances were calculated using cell parameters and four different cells were compared with each other. The performances measurements of both cell configurations showed that the peak power density of the bi-layered electrolyte configuration improved by a factor of 1.45 and reached 0.94 W/cm2 at 600 °C, while it was only 0.51 W/cm2 for the monolayered YSZ electrolyte configuration. Additionally, the effect of HEB addition to LSM cathode resulted in a performance increase of %84 compared to the cell with LSM cathode only. The presence of HEB either as a second electrolyte or ionic conductive phase in the composite cathode is lowered activation polarization of the cells both bi- or monolayered electrolyte cells and resulted in increased performance.

Distribution of Oxygen Partial Pressures in Native Capillary Fingertip Blood Samples From a Large Diabetes Patient Population.

A data set comprising 28 533 oxygen partial pressure (pO2) values gathered from nonarterialized fingertip capillary blood samples of a large diabetes population is reported. Data were gathered routinely as part of the ongoing clinical surveillance activities of a blood glucose monitoring (BGM) system manufacturer. Overall, a mean pO2 level of 75.3 mm Hg was recorded, with a standard deviation (SD) of 10.6 mm Hg and a range of 27.7 to 151.5 mm Hg. This data set, unique in terms of size, gathered more than 14 years at four separate clinical sites, provides a robust and comprehensive representation of an unmanipulated pO2 fingertip capillary sample distribution, which should be of interest for physiological reasons, but also from a medical device development perspective, in which the effect of pO2 on device performance may be an important design consideration.

The interaction of carbon-bonded ceramics with Armco iron

To investigate the possible reactions between carbon-bonded ceramics and liquid Armco iron, three types of carbon (10 wt% C) bonded ceramics Al2O3 rich spinel (C-AR78), MgO rich spinel (C-MR66), and CaO·6Al2O3 (C-CA6) were put into contact with liquid Armco iron at 1625 °C by using the sessile drop method. During the interaction experiments, the oxygen partial pressure values in the experimental chamber were monitored with an oxygen detector. Thereby, the oxygen partial pressures differed based on the used carbon-bonded ceramic. It was found that the iron samples after interaction experiments were covered by newly formed oxide layers, and oxide whiskers have grown at the interface with the ceramic substrates. The compositions of the newly formed oxide layers and whiskers were related to the applied ceramic substrates. Moreover, Al and C pick-up into the iron sample was observed. The obtained results were discussed with a thermodynamic simulation based on the available Al-Fe-Mg-O-database.

Role of the L-Arginine/NO System in Red Blood Cells at Different Values of Oxygen Partial Pressure

Role of the L-Arginine/NO System in Red Blood Cells at Different Values of Oxygen Partial Pressure

Can Noninvasive Oxygen Saturation Index Match Invasive Oxygenation Index to Monitor Respiratory Disease in Critically Ill Children?-A Prospective Study.

Respiratory illnesses are common indications for mechanical ventilation in children. The adequacy of ventilatory support for oxygenation is measured using arterial blood gas analysis and calculation of oxygenation index (OI). Due to invasive nature of arterial blood sampling needed to calculate OI, several researchers have replaced blood gas-derived partial pressure of oxygen values with oxygen saturation (SpO 2 ) obtained from pulse oximetry. This noninvasive index called oxygen saturation index (OSI) is found to be useful in neonates. Studies in pediatric population are lacking. In this prospective study on mechanically ventilated children, both OI and OSI were determined and compared against alveolar-arterial oxygen difference (AaDO 2 ). A total of 29 children were studied. Both OSI and OI had good correlation of 0.787 and 0.792 with AaDO 2 , respectively. OSI of 7.3 and 9.4 had good sensitivity and specificity for AaDO 2 cutoffs of 344 and 498, which represents moderate and severe respiratory illness, respectively. The correlation coefficients of both OSI and OI are similar against AaDO 2 . OSI can be used instead of OI for constant monitoring of children on mechanical ventilation. Arterial blood gas analysis and calculation of OI can be reserved for situations where SpO 2 measurement is unreliable.

The Impact of Protective Ventilation Strategy, Applied in Patients During Prolonged Gynecological Surgery, on Postoperative Oxygenation

&#x0D; &#x0D; &#x0D; Atelectasis occurs in nearly 90% of patients operated under general anaesthesia and persists for about 24 hours after laparoscopic surgery and 3 days after open surgery. According to some randomized studies, intraoperative application of mechanical protective ventilation with a low tidal volume (VT), positive end-expiratory pressure (PEEP) and recruitment maneuvers (RMs) decreases left to right shunting and improves postoperative oxygenation. During these trials statistically significantly higher values of oxygen partial pressure (PaO2) in arterial blood gas analysis and PaO2/FiO2 ratio (FiO2 – fraction of inspired oxygen; FiO2 = 0.21) were observed in patients ventilated with PEEP and RMs.&#x0D; Our purpose is to prove that the application of PEEP in patients during prolonged gynecological surgery can improve postoperative oxygenation and decrease the incidence of postoperative atelectasis.&#x0D; In this observational cohort study we included women, who underwent conventional gynecological surgery with a duration of more than 2 hours. Pa- tients were divided into 2 groups – control group A (35 patients) and exposed group B (35 patients). The ones in the control group were ventilated with a tidal volume (VT) of 8–10 ml/kg, without PEEP and RMs, whereas those in group B were ventilated with VT = 6−8 ml/kg (based on ideal body weight), PEEP = 6 cm H2O and RMs performed after intubation, at every disconnection from the ventilator and at extubation.&#x0D; We proved that the patients in group B had statistically significantly higher values of PaO2 and PaO2/FiO2 on the first postoperative day, therefore intraoperative protective mechanical ventilation improves postoperative oxygenation. We also observed a significantly reduced incidence of newly developed postoperative atelectasis in this patient group. Patients in group A had a significantly longer stay in intensive care unit (ICU) than those in group B. The use of protective ventilation strategy (low VT, PEEP and RMs) in patients during prolonged gynecological surgery can decrease the incidence of postoperative atelectasis and improves oxygenation on the first postoperative day.&#x0D; &#x0D; &#x0D;

Association Between Oxygen Partial Pressure Trajectories and Short-Term Outcomes in Patients With Hemorrhagic Brain Injury.

Objectives: Arterial hyperoxia is reportedly a risk factor for poor outcomes in patients with hemorrhagic brain injury (HBI). However, most previous studies have only evaluated the effects of hyperoxia using static oxygen partial pressure (PaO2) values. This study aimed to investigate the association between overall dynamic oxygenation status and HBI outcomes, using longitudinal PaO2 data.Methods: Data were extracted from the Medical Information Mart for Intensive Care III database. Longitudinal PaO2 data obtained within 72 h of admission to an intensive care unit were analyzed, using a group-based trajectory approach. In-hospital mortality was used as the primary outcomes. Multivariable logistic models were used to explore the association between PaO2 trajectory and outcomes.Results: Data of 2,028 patients with HBI were analyzed. Three PaO2 trajectory types were identified: Traj-1 (mild hyperoxia), Traj-2 (transient severe hyperoxia), and Traj-3 (persistent severe hyperoxia). The initial and maximum PaO2 of patients with Traj-2 and Traj-3 were similar and significantly higher than those of patients with Traj-1. However, PaO2 in patients with Traj-2 decreased more rapidly than in patients with Traj-3. The crude in-hospital mortality was the lowest for patients with Traj-1 and highest for patients with Traj-3 (365/1,303, 209/640, and 43/85 for Traj-1, Traj-2, and Traj-3, respectively; p < 0.001), and the mean Glasgow Coma Scale score at discharge (GCSdis) was highest for patients with Traj-1 and lowest in patients with Traj-3 (13 [7–15], 11 [6–15], and 7 [3–14] for Traj-1, Traj-2, and Traj-3, respectively; p < 0.001). The multivariable model revealed that the risk of death was higher in patients with Traj-3 than in patients with Traj-1 (odds ratio [OR]: 3.3, 95% confidence interval [CI]: 1.9–5.8) but similar for patients with Traj-1 and Traj-2. Similarly, the logistic analysis indicated the worst neurological outcomes in patients with Traj-3 (OR: 3.6, 95% CI: 2.0–6.4, relative to Traj-1), but similar neurological outcomes for patients in Traj-1 and Traj-2.Conclusion: Persistent, but not transient severe arterial hyperoxia, was associated with poor outcome in patients with HBI.

Non-Faradaic Electrochemical Modification of Catalytic Activity: LSCF As Electrocatalyst for Nitrous Oxide Electrochemical Reduction

Nitrous oxide (N2O) mitigation is of high importance as this gas is responsible for several environmental problems, such as photochemical smog, acid rain, ozone layer depletion and global warming. While N2O is not the principal contributor to global warming (~ 6 %), it has 310 and 21 times the Global Warming Potential (GWP) of the most common anthropogenic greenhouse gases, CO2 and CH4, respectively [1]. European Union directives currently aim at a reduction in the emissions of these gases by 42 % from their 2013 levels by 2030 [2].The current work aims to bridge solid-state chemistry and heterogenous catalysis, by studying the electrochemical promotion of catalysis (EPOC), also known as non-Faradaic electrochemical modification of catalytic activity (NEMCA), of the N2O reduction reaction. Here, the catalytic activity of an electrode surface is radically changed upon polarization, typically applying large electrical potentials (> 2 V) that lead to considerable changes in the conversion and the selectivity of the products [3].For this work, the well-known mixed electronic and ionic conductor La0.6Sr0.4Co0.2Fe0.8O3-δ LSCF) was utilised as the electrocatalyst, due to its high availability and excellent performance as a cathode in solid oxide fuel cells (SOFCs). This composition exhibits a very high oxygen surface exchange coefficient (K* = 1.1 x 10-3cm s-1 at 800 °C) as well as high electronic (230 S cm-1 at 900 °C) and ionic conductivities (0.2 S cm-1 at 900 °C), essential requisites for this application [4].A 3-probe cell-based reactor was developed, composed by a solid oxide-ion-conducting electrolyte substrate made of 8 % mol Y2O3 – stabilized ZrO2, a working electrode made of LSCF and counter and reference electrodes made of inert gold (Au), to avoid any influence of the latter parts in the electrocatalytic activity of the main LSCF electrocatalyst. A buffer layer of Ce0.9Gd0.1O2-δ (CGO) was additionally used between the working electrode and the substrate, to prevent the inter-reaction between the YSZ and LSCF.The key aspect of this work was the use of an integrated zirconia oxygen sensor in the studies, to determine variations in the values of oxygen partial pressure (pO2 ) upon polarisation, which were subsequently correlated with the extent of N2O conversion. This methodology proved to be highly effective and avoids the need for additional techniques, such as gas chromatography.From the experiments, it was found that by applying cathodic polarisation (i.e -0.05 and -0.25 A), an increase of the catalytic rate (r O2 mol s-1) was observed, resulting in a significant increase of N2O conversion. An electrophobic behaviour of the electrocatalyst, i.e., a reaction rate that increases upon cathodic polarization, was observed for all temperatures with a maximum rate enhancement ratio (ρ=r/r0) up to 3.47 was achieved at -0.05 A at 600 ºC. The Faradaic efficiency (Λ) was also calculated for the tested experimental conditions, and showed values that exceed unity, evidencing non-Faradaic electrochemical behaviour. The highest Λ value of 8.8 was obtained at the lower temperature and currents tested at 600 °C. The nature of the mechanism was also assessed, showing a completely reversible effect, where the electrochemically promoted reaction rate returns to its open circuit value upon removal of polarisation. This work, therefore, highlights that non-Faradaic activation of heterogenous catalysis can be an effective tool to promote the reductive treatment of this greenhouse gas, with great environmental importance.

The Influence of Combined Physical Therapy Procedures on Oxygen Partial Pressure in Tissues Surrounding Ulcer in Patients With Venous Leg Ulcers.

Venous ulcers in lower legs remain a profound treatment problem in contemporary medicine. Proper healing requires, among other things, sufficient blood supply and provision of suitable amount of oxygen to the treated tissues. The aim of the study was to assess the influence of combined physical therapy applied in patients with chronic venous leg ulcers on the oxygen partial pressure values. Fifty-four patients (25 females and 29 males), in the age range of 38 to 89 years with chronic venous leg ulcers, underwent a cycle of 15 procedures with the use of Laserobaria-S device. During a procedure, the patient's lower limb was simultaneously exposed to oxygen having the pressure of 1.5 ATA, low-frequency magnetic field, and low-energy light radiation. Before procedures, directly after the first procedure, as well as on completion of the entire therapeutic cycle, the patients underwent oxygen partial pressure measurements in the tissues surrounding the ulceration area, by means of transcutaneous oximetry, with the use of Medicap Précise 8008s device. The combined physical therapy shows a statistically significant increase of oxygen partial pressure values in tissues surrounding the ulceration, from the average of 68.63 ± 17.04 mm Hg before commencing the therapeutic cycle, to the average of 74.20 ± 18.92 mm Hg after the first procedure (P < .001) and to the average value of 83.79 ± 20.74 mm Hg (P < .001) after completion of therapeutic cycle. Combined physical therapy procedures cause a statistically significant increase of oxygen partial pressure values in tissues surrounding the ulceration, assessed using the objective method of transcutaneous oximetry, both in women and men.

Bilevel and continuous positive airway pressure and factors linked to all-cause mortality in COVID-19 patients in an intermediate respiratory intensive care unit in Italy

ABSTRACT Objectives: In the present single-centered, retrospective, observational study, we reported findings from 78 consecutive laboratory-confirmed COVID-19 patients with moderate-to-severe acute respiratory distress syndrome (ARDS) hospitalized in an intermediate Respiratory Intensive Care Unit, subdividing the patients into two groups according to their clinical outcome, dead patients and discharged patients. Methods: We further subdivided patients depending on the noninvasive respiratory support used during hospitalization. Results: In those patients who died, we found significant older age and higher multimorbidity and higher values of serum lactate dehydrogenase, C-reactive protein, and D-dimer. Among patients who were submitted to bilevel positive airway pressure (BPAP), those who died had a significant shorter number of days in overall length of stay and lower values of arterial oxygen partial pressure to fractional inspired oxygen ratio (PaO2/FiO2 ratio) compared to those who survived. No difference in all-cause mortality was observed between the two different noninvasive respiratory support groups [48% for continuous positive airway pressure (CPAP) and 52% for BPAP]. Conclusion: In COVID-19 patients with moderate-to-severe ARDS using BPAP in an intermediate level of hospital care had more factors associated to all-cause mortality (shorter length of stay and lower baseline PaO2/FiO2 ratio) compared to those who underwent CPAP.

Oxygen absorption and desorption behavior of Ba0.5La0.5FeO3-δ and its effect on crystal structure and electrical conduction properties

As a new mixed conductor with high property, the preparation of Ba0.5La0.5FeO3-δ with cubic perovskite structure was examined under different values of oxygen partial pressure, P(O2). An almost-single-phase Ba0.5La0.5FeO3-δ with cubic perovskite structure was successfully prepared by sintering at 1200 °C under P(O2) values ranging between 1 and 10−9 atm. The existence of two types of cubic Ba0.5La0.5FeO3-δ phases, one with a smaller δ and paramagnetic Fe with valence between 3+ and 4+ and the other with larger δ and antiferromagnetic Fe with valence of almost 3+, was clarified. Moreover, the above two phases could be interchanged with each other by annealing at 1200 °C under controlled P(O2). It was revealed that the oxygen-deficient cubic phase rapidly absorbed oxygen above 300 °C in air and that δ increased with temperature above 400 °C in air. Rapid oxygen absorption or desorption by switching the gas flow between O2 and N2, as well as its cyclic behavior with high reproducibility, was also observed. Under P(O2) values ranging between 1.0 and 1.02 × 10−2 atm, the temperature dependence of electrical conductivity was small regardless of P(O2), and the difference in electrical conductivity by P(O2) was scarcely observed. Log σ reached approximately 1.5 at 400 °C. With P(O2) decreasing to 1.01 × 10−3 or less, a slight increase in electrical conductivity was observed with an almost constant log σ on temperature.

Влияние кислородной нестехиометрии на фазовое расслоение, структуру и магнитные свойства сложного оксида NdSr2Mn2O7 ± 

To create different oxygen nonstoichiometry in oxide samples of NdSr2Mn2O7 + δ, we have used a two-step method of synthesis, which makes it possible to achieve different oxygen nonstoichiometry of the samples. Oxygen nonstoichiometry is formed by two methods: quenching at certain temperatures and annealing at certain values of oxygen partial pressure. The value of oxygen nonstoichiometry is determined by the mass of oxygen emitted from the sample during the decomposition of samples of NdSr2Mn2O7 + δ to simple oxides. We have determined oxygen nonstoichiometry in NdSr2Mn2O7 + δ when recording external parameters such as pressure and temperature. The study of samples of NdSr2Mn2O7 + δ using thermogravimetry and X-rays revealed phase separation—two phases with the same cation composition, having different oxygen content. By example of a sample of NdSr2Mn2O7 + δ tempered from 1000°C and having oxygen nonstoichiometry of +0.09, we have proposed a crystallographic criterion of manifestation of phase separation in Ruddlesden–Popper (R–P) phases—a sharp change in the manganese-oxygen bond lengths. Measurements of the electrical dc resistance in the samples of NdSr2Mn2O7 have been performed in the temperature range of 5–300 K and magnetic fields up to 7 T using the standard 4-probe method. A magnetoresistive effect up to 400% was found in the studied oxides, which is nonlinearly dependent on their oxygen nonstoichiometry.

Effect of direct-current operation on the electrochemical performance and structural evolution of Ni-YSZ electrodes

The effect of electrolysis operations on Ni-YSZ fuel electrode stability was studied at different current densities and fuel mixtures during 1000 h life tests. For a typical electrolysis mixture of 50% H2/50% H2O and 0.6 A cm−2 current density, cell ohmic resistance values were reasonably stable and no structural changes occurred. However, for more reducing conditions (97% H2/3% H2O), increasing the current density above 0.4 A cm−2 increased the ohmic resistance accompanied by significant electrolyte degradation including fracture and void formation at grain boundaries. Numerical analysis was carried out to determine the effective oxygen partial pressure across the electrolyte. The results show that the oxygen partial pressure values at high current density and low steam content may be low enough to reduce zirconia to form a Ni-Zr alloy product, initiating the observed electrolyte structural degradation.

The effects of the oxygen content on the photoelectrochemical properties of LaFeO3 perovskite thin films obtained by pulsed laser deposition

The physical properties of perovskite oxides are strongly influenced by their stoichiometry and one of the key features of these materials is the tunability of their functionality by controlling the interplay between the compositional and structural properties. Here, the effects on the photoelectrochemical (PEC) water splitting properties of ferroelectric LaFeO3 thin films obtained at different oxygen partial pressures during growth are reported in conjunction with the morphological, optical and structural features. The LaFeO3 thin films have been deposited by pulsed laser deposition on Nb:SrTiO3 substrates. The strong dependence of the photocurrent values Jphoto on the growth conditions is revealed by the photoelectrochemical measurements. Strong variations of the lateral coherence lengths L‖ of LaFeO3/Nb:SrTiO3 with the oxygen partial pressure values are noticed from the X-ray diffraction (XRD) analysis. All the films are heteroepitaxial with small tensile strain levels detected in the crystalline structure, but only for a narrow interval of oxygen partial pressures the LFO/STON thin films show high quality crystalline structure with large lateral coherence length L‖ and photoelectrochemical currents.

Inducing Brain Cooling Without Core Temperature Reduction in Pigs Using a Novel Nasopharyngeal Method: An Effectiveness and Safety Study.

BackgroundAcute brain lesions constitute an alarming public health concern. Neuroprotective therapies have been implemented to stabilize, prevent, or reduce brain lesions, thus improving neurological outcomes and survival rates. Hypothermia is the most effective approach, mainly attributed to the reduction in cellular metabolic activity. Whole-body cooling is currently implemented by healthcare professionals; however, adverse events are frequent, limiting the potential benefits of therapeutic hypothermia. Therefore, selective methods have been developed to reduce adverse events while delivering neuroprotection. Nasopharyngeal approaches are the safest and most effective methods currently considered. Our primary objective was to determine the effects of a novel nasopharyngeal catheter on the brain temperature of pigs.MethodsIn this prospective, non-randomized, interventional experimental trial, 10 crossbred pigs underwent nasopharyngeal cooling for 60 min followed by 15 min of rewarming. Nasopharyngeal catheters were inserted into the left nostril and properly positioned at the nasopharyngeal cavity.ResultsNasopharyngeal cooling was associated with a decrease in brain temperature, which was more significant in the left cerebral hemisphere (p = 0.01). There was a reduction of 1.47 ± 0.86 °C in the first 5 min (p < 0.001), 2.45 ± 1.03 °C within 10 min (p < 0.001), and 4.45 ± 1.36 °C after 1 h (p < 0.001). The brain-core gradient was 4.57 ± 0.87 °C (p < 0.001). Rectal, esophageal, and pulmonary artery temperatures and brain and systemic hemodynamic parameters, remained stable during the procedure. Following brain cooling, values of oxygen partial pressure in brain tissue significantly decreased. No mucosal lesions were detected during nasal, pharyngeal, or oral inspection after nasopharyngeal catheter removal.ConclusionsIn this study, a novel nasopharyngeal cooling catheter effectively induced and maintained exclusive brain cooling when combined with effective counter-warming methods. Exclusive brain cooling was safe with no device-related local or systemic complications and may be desired in selected patient populations.