O2 Flow Research Articles

59: PREDICTION MODEL TO IDENTIFY SEPSIS PATIENTS FOR MINIMALLY INVASIVE MANAGEMENT OUTSIDE THE ICU

Introduction: Patients with sepsis who need intensive care unit (ICU) admission for short-term monitoring (< 48 hr) with low-dose vasopressors could be candidates for minimally invasive sepsis (MIS) approach outside the ICU. We aimed to describe such patients and develop a prediction model to find candidates for MIS approach. Methods: In a secondary analysis of institutional data, we identified adults (≥18 yr) with septic shock admitted to the Mayo Clinic medical ICU from emergency. MIS approach candidates were with < 48 hr of ICU stay, without advanced respiratory support or renal replacement therapy and alive at ICU & hospital discharge. Comparison group consisted of septic shock patients with an ICU stay of >48 hr who didn’t need advanced respiratory support before ICU admission. Wilcoxon rank, Chi Square, and Fisher’s exact tests were used to compare baseline characteristics. Logistic regression and prediction profiler were used to select predictive variables and assign cut-offs. Using points assigned to variables based on OR and clinical rational, a nominal logistic regression model was created. Model discrimination & calibration were assessed by receiver operating characteristic (ROC) curves and Hosmer-Lemeshow (H-L) goodness-of-fit test. Results: Out of 1795 MICU admissions, 109 patients (6 %) met MIS approach criteria and 97 in comparison group. MIS group was younger with lower respiratory rate, temperature, lactate, creatinine, BUN, and WBCs (p < 0.05 for all). Predictive variables (age >65 yr, O2 flow >4 L/mint, temperature < 37℃, creatinine >1.6 mg/dL, lactate >3 mmol/L, WBCs >15x109, heart rate >100 beats/mint, and respiration rate >25 breaths/ mint) were translated into an 8-point score. Model discrimination yielded ROC: AUC of 80%. Model fit was confirmed by agreement between observed and predicted probability and was well calibrated (H-L p = 0.94). MIS score cut-off of 3 resulted in a predictive model OR of 0.15 (CI: 0.08–0.28) and a negative predictive value of 91% [(CI: 88.69-92.92) (using prevalence of MIS patients ~20%)] Conclusions: Study implies that a significant minority of sepsis patients can be managed outside the ICU. Once validated in an independent, prospective sample our prediction model can be used to identify candidates for minimally invasive management outside of ICU

Observation and Modeling of a Sharp Oxygen Threshold in Aqueous Free Radical and RAFT Polymerization.

It is known that oxygen (O2) stops radical polymerization (RP). Here, it was found that the reaction turn-off occurs abruptly at a threshold concentration of O2, [O2]t, for both free RP and reversible addition-fragmentation chain-transfer polymerization (RAFT). In some reactions, there was a spontaneous re-start of conversion. Three cases were investigated: RP of (i) acrylamide (Am) and (ii) sodium styrene sulfonate (SS) and (iii) Am RAFT polymerization. A controlled flow of O2 into the reactor was employed. An abrupt turn-off was observed in all cases, where polymerization stops sharply at [O2]t and remains stopped when [O2] > [O2]t. In (i), Am acts as a catalytic radical-transfer agent during conversion plateau, eliminating excess [O2], and polymerization spontaneously resumes at [O2]t. In no reaction, the initiator alone was capable of eliminating O2. N2 purge was needed to re-start reactions (ii) and (iii). For (i) and (ii), while [O2] < [O2]t, O2 acts a chain termination agent, reducing the molecular weight (Mw) and reduced viscosity (RV). O2 acts as an inhibitor for [O2] > [O2]t in all cases. The radical-transfer rates from Am* and SS* to O2 are >10,000× higher than the initial chain propagation step rates for Am and SS, which causes [O2]t at very low [O2].

Termination Control of (001) and (110) NdGaO3 Single-Crystal Substrates by Selective Chemical Etching

Controlling the surface morphology and composition of the perovskite substrates is a critical aspect in tuning the final properties of the deposited films and of their interfaces. The paper reports on a chemical etching method developed for (110) and (001) NdGaO3 single crystal substrates in order to obtain a well-defined GaO2−x-terminated surface. The etching process is based on a HF + NH4OH solution and includes an annealing step performed in air or under O2 flow at temperatures of 800–1000 °C. In order to obtain the desired composition and surface morphology, the etching procedure was optimized for the vicinal step density at the surface and substrate crystal orientation. Growth nucleation studies of one-unit-cell MeO films (Me = Ti, Sr, Ba) on chemically etched and on only annealed substrates were performed in order to determine the composition of the substrate topmost layer. The results indicate that the chemically etched NdGaO3 substrate surface has a predominantly GaO2−x termination, with a lower free surface energy compared to the NdO1+x termination.

Oxygen-rich hierarchical activated coke-based gas diffusion electrode enables highly efficient H2O2 synthesis via O2 electroreduction

Large-scale application of H2O2 production through 2-electron oxygen reduction reaction (2eORR) greatly depends on the cost of electrode materials and configuration. In this work, engineered coal-derived oxygen-rich hierarchical activated coke (AC), which is low-cost and highly tunable in porosity and surface chemistry, was used as catalyst to fabricate gas diffusion electrodes (GDEs) for efficient H2O2 production. Results showed that Fenton’s reagents treatment could significantly increase the contents of CO and –COOH on AC, leading to an increased hydrophilicity. However, the higher O contents do not necessarily enhance the selectivity of AC towards 2eORR (i.e., F-5-AC, F-10-AC), especially that F-20-AC exhibited a complete 4e pathway. GDEs were then fabricated with AC and oxidized AC as catalyst, key fabrication parameters including the PTFE binder and AC particle size, and operating parameters such as current intensity, electrolyte pH, and O2 flow rate were optimized. Up to 747 mg/L H2O2 were generated within 90 min. Results showed that oxidized AC exhibited a decreased H2O2 yield, due to the flooding of GDEs caused by super-hydrophilicity property. Finally, DFT calculations were employed to reveal the synergistic effect of different O groups considering the fact of high O contents on AC.

Study of oxidation behaviour of Ruthenium thin film after thermal annealing in oxygen environment

In the present study, 20 nm thick Ru film ion beam sputtered on Si substrate is annealed at different temperatures ranging from 100 °C to 600 °C for 2 hours in an oxygen environment. The sample was characterized by grazing incidence x-ray reflectivity and grazing incidence x-ray diffraction techniques that revealed that there is no oxidation of Ru below 400 °C in 150 standard cubic centimetre O2 flow environment. At 400 °C, the oxidation of the Ru thin film starts and at 500 °C both Ru and RuO2 phases co-exists. At higher temperature (600 °C), the Ru thin film oxidized into RuO2 phase and an intermixed layer of Ru and Si at the film substrate interface is revealed.

Removal of methylene blue and azo reactive dyes from aqueous solution and textile effluent via modified pulsed low-frequency ultrasound cavitation process.

Organic dyes in the aqueous solutions and textile effluents cause severe environmental pollution due to their carcinogenic and mutagenic nature. Ultrasound (US) cavitation is one of the promising advanced oxidation processes (AOP) to remove the organic dyes from the aqueous solutions and textile effluents. Nevertheless, the conventional low-frequency US cavitation process exhibits very low efficiency in the dye removal process and demands effective modification to improve its performance. In this investigation, a conventional pulsed low-frequency (22 ± 2kHz) US cavitation process has been modified by varying the US power (50-150W), initial solution pH (2-10), and O2 flow rate (1-4 L min-1) to enhance the decomposition of cationic methylene blue (MB) dye in an aqueous solution. The operation of the classic Haber-Weiss reaction, both in the forward and backward directions, and the ozone effect have been observed, for the first time, under the modified US cavitation process, as confirmed via the radical trapping experiments. Moreover, the hydrothermally synthesized hydrogen titanate (H2Ti3O7) nanotubes (HTN) have been utilized as sonocatalyst, for the first time, for 100% dye removal, with effective regeneration obtained via an in-situ thermal activation of persulfate (PS, S2O82-). The most optimum values of US power, initial solution pH, O2 flow rate, HTN, and PS concentrations for 100% MB decomposition are observed to be 150W, 2, 2 L min-1, 0.3g L-1, and 10mM, respectively. The decomposition of industrial azo reactive dyes in an aqueous solution as well as in a textile effluent has also been demonstrated using a modified pulsed low-frequency US cavitation process involving the thermal activation of PS without the use of HTN, which justifies its suitability for a commercial application.

Electrical instabilities in amorphous Si-Zn-sn-O thin film transistors under ultra-violet irradiation depending on oxygen content

The effect of different oxygen (O2) flow rates during the radio-frequency (RF) sputter deposition of amorphous silicon-zinc-tin-oxide (a-SZTO) thin film transistors (TFTs) has been studied. The threshold voltage (Vth) shifts towards the positive bias by increasing the O2 flow rate during the deposition, which decreases the electron concentration by reducing oxygen vacancies (VOs). The post-treatment of the devices under ultraviolet (UV) irradiation in the air atmosphere has been performed to analyze the reliability of light. The post-treatment of UV irradiation on the a-SZTO TFT for different time intervals significantly shifts the threshold voltage (Vth) from enhance- to depletion mode owing to the creation of VOs. Interestingly, we observed that UV irradiation is more effective on the parameters of Vth and the current ON/OFF (ION/OFF) ratio for the TFTs prepared at lower O2 flow rates. The reason may be that by introducing more oxygen flow, the de-trapping of electrons is reduced under UV irradiation due to the reduced VOs. UV irradiation does not significantly impact the field-effect mobility (µFE) for different O2 flow rates. The negative bias stress measurement of the devices was performed and analyzed for different O2 flow rates under UV irradiation treatment.

Abstract 167: Nasal Sensor Capnographic Differences In Major Traumatic Brain Injury Patients Receiving Non-rebreather Mask Versus Nasal Cannula Oxygen Delivery

Background: The advent of highly sensitive End-Tidal CO2 (ETCO2) sensors allows effective monitoring of intubated patients in EMS. Previous work has explored the use of ETCO2 monitoring in non-intubated patients with sensors placed in the nares. However, little is known about the effect of passive O2 delivery [nasal cannula (NC) or high-flow, non-rebreather mask (NRB)] on ETCO2 measurement. Objective: To compare ETCO2 measurements in non-intubated Traumatic Brain Injury (TBI) patients receiving O2 via NC vs. NRB in the field. Methods: A subset of cases from the EPIC EMS TBI Study (NIH-1R01NS071049) were evaluated (4/13-4/18). Non-intubated cases from 5 EMS agencies providing monitor data, including continuous ETCO2. Start and end segments were excluded to remove artifact from initiation (“ramp-up”) or termination of monitoring. Statistics: Wilcoxon rank-sum test, two-sample t-test, and Chi-squared test were used as appropriate. Linear regression compared continuous variables in adjusted analyses (α = 0.05). Results: Included were 151 cases [median age: 52 (range: 9-91; 66% male)]. Of those, 62 (41%) received NCO2 and 89 (59%) via NRB. Patient-level mean ETCO2 was slightly lower in the NC group (mean = 26.9 mmHg; SD 6.7) compared to NRB (mean 30.2; SD 8.1; p=0.007). Differences in the mean were: Unadjusted: 3.3 (95% CI 0.9-5.7); Adjusted 2.7 (0.2-5.2). There were no significant differences in means of the patient-level lowest or highest recorded values. Conclusion: While there was a statistically lower ETCO2 in the NC versus NRB-oxygenated patients, it was around 3 mmHg and, thus, not clinically significant. This is surprising since: 1) the O2 flow rates and 2) the open-air (NC) versus mask (NRB) delivery methods are so dramatically different. Future study is needed to identify the clinical implications of using noninvasive ETCO2 measurement as a tool for monitoring ventilatory status and changes in non-intubated TBI (and other) patients in emergency settings.

A new pathway to produce hydrogen with COx capture from blast furnace gas via SOFC-SOEC integration

As a low calorific value fuel, blast furnace gas (BFG) is worthy of utilization in a clean, efficient, and low-carbon manner. In this study, a new approach that can achieve value-added recycling of BFG, BFG → SOFC-SOEC → H2, is put forward with hydrogen production and carbon oxides capture. The system mainly consists of blast furnace (including upper, middle, and lower units), SOFC, and SOEC modules, which can convert low-grade chemical energy of BFG into electricity and then into hydrogen. Feasibility verification and parameter optimization of the proposed system is conducted using ASPEN Plus software. The effects of C and CaCO3 feeding rates, blast furnace temperature, air flow rate, and O2 flow rate are comprehensively investigated. Results indicate the feasibility of integrating SOFC with SOEC for value-added hydrogen production. Moreover, carbon oxides capture efficiency of 99.92 %, BFG lower heating value of 2209 kcal/m3, SOFC efficiency of 61.1 %, SOFC power of 65 kW, and H2 production rate of 0.24 kmol/kmol·BFG can be obtained under the conditions of C/CaCO3 = 42.6 and oxygen feeding rate = 11.58 kmol/ton·ore. These findings provide valid strategies for BFG-to-hydrogen production with COx capture via SOFC-SOEC integration, which may substantially promote the low-carbon BFG conversion and diversified utilization.

Li(Ni x Mn y Co z )O2 with high specific surface area prepared by electrospinning

ABSTRACT Reaction polarization of the Li(Ni x Mn y Co z )O2 (NMC) cathode materials can be significantly alleviated by depolarization and pre-lithiation, which respectively produce electrolyte protective layer and double-layer lithium structure. These structures can not only prevent Ni ions from dissolution but also increase the discharge capacity. However, as the size of the regular NMC particles is relatively large, the effect of depolarization and pre-lithiation is not significant. This work tries to prepare NMC with nanoscale structure and high specific surface area by electrospinning, and studies the effect on NMC morphology caused by calcination atmosphere, oxidation temperature, decarburization temperature and calcination temperature. It is hoped that the polarization can be further eliminated by optimizing the size, and the proportion of double-layer lithium formed in the pre-lithiation can be increased. The results reveal that after several steps including pre-oxidation at 200°C, decarburization at 550°C and calcination at 750°C, nano lamellar structures with size of about 1–3 μm and thickness of about 30 nm can be produced under O2 flow of 200 SCCM. NMC with nano lamellar structures will further alleviate the polarization and produce a higher proportion of double-layer lithium structure by pre-lithiation, resulting in a significant improvement of the discharge capacity.

Oxidation of Cu3N thin films obtained from Cu annealed under NH3:O2 flow: A Raman and N-K-edge NEXAFS study

Cu3N layers prepared by annealing, under NH3:O2 flow, of Cu sputtered on Si, fused SiO2, and soda-lime-glass were studied by Raman and N-K-edge Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. The annealing temperatures were ranging from 300° to 800°C. Benefiting from resonance effects on the Raman peak intensities when different excitation wavelengths are used, the contribution in the Raman signal of copper oxides, which provide peaks lying close to those of Cu3N, is more easily discriminated. The formation of Cu2O surface oxide is observed in almost all the samples even for annealing at low temperatures. CuO is generally formed at higher temperatures with the onset depending on the amount of O2 in the NH3:O2 mixture. However, high temperature is necessary to grow larger crystallites, as it is deduced from the decrease in the width of the high-frequency Raman peak (at ca. 650 cm−1) of Cu3N, in accordance with Scanning Electron Microscopy observations. The formation of CuO is accompanied by the creation of N2 trapped in the sample, which is directly detected by the NEXAFS measurements. N2 is most probably formed by the N atoms originating from the dissociation of the Cu-N bonds.

Experimental optical and structural properties of ZnS, MgF2, Ta2O5, Al2O3 and TiO2 deposited by electron beam evaporation for optimum anti-reflective coating designs

MgF2, ZnS, Ta2O5, Al2O3 and TiO2 are some of the most common dielectric materials actually used in solar cells as anti-reflective coatings. For such purpose, they have been deposited by electron beam evaporation, which is one of the preferred technique in industrial settings. In this work we aim to understand the relationship between their optical and physical properties and deposition parameters and thicknesses, being spectroscopic ellipsometry the main technique used for such issue. MgF2 and ZnS have demonstrated rather good optical quality except for the thinnest samples. For Ta2O5, O2 flow during growth has been revealed as critical parameter for ensuring the proper composition of the layer. Al2O3 samples showed a very important amount of Al hydroxide, which is detrimental of the optical quality of these layers. TiO2 samples have also contamination problems, in this case due to oxygen species and Ti3+ oxide presence. For all these oxides, optical properties are clearly influenced by layer thickness. The layer optical parameters n and k have been determined as a function of wavelength (300–1800 nm) and validated against experimental reflectance and transmittance data. Finally, the impact that the proper knowledge of n and k values have when designing broad-band anti-reflective coatings for III-V multijunction solar cells is quantified in terms of short-circuit current relative increase.

Modulation of the conductive behavior of NiO thin film deposited by HiPIMS through varying the O2 flow ratio

Nickel oxide (NiO) films were prepared through High Power Impulse Magnetron Sputtering (HiPIMS). The influence of O2/(Ar + O2) flow ratio (oxygen flow ratio) from 0.5% to 3% on structural and optoelectronic qualities of NiO films were studied. The results indicate that deposition rate of NiO film reduces as increase of oxygen flow ratio. Atomic force microscopy shows that as oxygen flow ratio increases, surface roughness of NiO films decrease. The transmittances of the NiO films are over 60% in the visible wavelengths. Hall effect measurements suggested that by adjusting the oxygen flow ratio NiO films with different type of conduction can be obtained. The carrier concentration of NiO films increase significantly as oxygen flow ratio goes up, which is caused by the fact that more nickel vacancies and interstitial oxygen are formed in NiO films. Therefore, the electrical conductivity enhances accordingly. The XPS analysis demonstrates the presence of both Ni2+ and Ni3+ oxidation states and also confirms the transition of conductive type of the NiO films. HiPIMS is a potential approach for depositing n type or p type transparent conductive oxide NiO films.

Controlling the crystalline orientation and textual morphologies of the VO2 film and the effect on insulator–metal transition properties

Monoclinic VO2 films were prepared over quartz substrates through thermal oxidation of sputtered vanadium films under continuous O2 flow in a vacuum. It was found that an additional vacuum pre-heating before the thermal oxidation could have a great effect on film crystalline orientation and textual morphologies. The film exhibits a preferable growth along [011] direction and consists of uniform small inter-connected nanoparticles, while the untreated film shows (200) orientation and is composed of large irregular nanoparticles that connect via disorder boundaries. The (011) orientated film shows slightly higher full solar and IR light modulations. The electric resistance results also show that the metal–insulator transition (MIT) of the (011) orientated film presents a larger amplitude, higher sharpness, and narrower hysteresis as compared to the (200) orientated film. The difference in textual structures of the orientated films is the main physical reason that affects the MIT of m-VO2 films.

High-flow nasal oxygen therapy in patients after esophageal interventions: аdvantages and disadvantages

BACKGROUND: Pulmonary complications in patients who underwent esophagectomy with one-stage esophagoplasty are a frequent cause of death in the intensive care unit (ICU). However, the use of noninvasive ventilation (NIV) in these patients is not indicated because of the failure of esophagogastric anastomosis. Compared with NIV and standard oxygen therapy, high-flow oxygen therapy (HFOT) reduces the rate of transfer to mechanical ventilation (MV) in the case of acute respiratory failure.&#x0D; AIM: This study aimed to assess the clinical advantages and disadvantages of HFOT in patients with respiratory failure after esophagectomy.&#x0D; MATERIALS AND METHODS: Ninety patients with esophagectomy were examined. Two groups were formed by randomization: group 1 (n=45) with standard respiratory therapy, incentive spirometry, and nasal oxygen therapy with NIV sessions and low end-expiratory pressure (up to 6 mmHg) and group 2 (n=45) with HFOT. Therapy parameters were selected according to oxygenation (PaO2/FiО2) and saturation (SaО2) index values. Parameter changes, session duration, patients tolerance to respiratory therapy methods (from 1 to 10 points), dynamics of chest X-ray pattern, and duration of treatment in ICU were analyzed.&#x0D; RESULTS: The advantages of HFOT were the absence of discomfort during the session, possibility to decrease O2 flow required for an adequate level of oxygenation, high flow with controlled O2 fraction allowed to reach target values of oxygenation index, decreased frequency of patients transfer to MV, and time spent in ICU.&#x0D; CONCLUSIONS: The use of HFOT is justified as part of the complex respiratory therapy in patients with moderate respiratory failure. In patients with severe respiratory failure, HFOT is an alternative to other high-flow techniques and NIV. The choice between these methods should be individualized and depend on the patients condition and ventilation requirement.

Cardiorespiratory parameters monitoring during moderate sedation at different oxygen flow rates in patients undergoing endoscopic intervention

Background: Cardiorespiratory parameters before, during and after administration of sedation/analgesia in patients undergone endoscopic procedure should have monitored. Aim of the study: In this study we evaluated the effect of different O2 flow rates on the non-invasive CO2 monitoring (EtCO2) in patients that are breathing spontaneously under moderate sedation undergoing endoscopic procedures. Methods: 120 patients of both sexes aged between 25 and 60 years with ASA- I and II scheduled for undergoing upper GIT endoscopy for gastric ulcer patients. Patients were randomized to three equal groups. Group I: 40 patients will receive O2 supply at rate of 2 liters per minute and then cabnographic and other measures will be recorded throughout the procedure. Group II: 40 patients will receive O2 supply at rate 4 liters per minute and then cabnographic and other measures will be recorded throughout the procedure. Group III: 40 patients will receive O2 supply at rate 6 liters per minute and then cabnographic and other measures will be recorded throughout the procedure. Results: EtCO2 differences between the three studied groups were statistically significant at preoperative, induction, 5, 10, 20 and 30 min but with no any clinical significance or adverse outcome. HR, MBP, RR and Spo2 difference between group were statistically insignificant throughout the procedure with no serious complications were recorded and patients satisfaction results were comparable between the three studied groups. Conclusion: Our study demonstrated that different O2 flow rates did not affect noninvasive EtCO2 measurement during moderate sedation in patients undergoing upper GIT endoscopy for gastric ulcer patients.

Polydopamine-assisted coating layer of a fast Li-ion conductor Li6.25La3Zr2Al0.25O12 on Ni-rich cathodes for Li-ion batteries

Ni-rich cathode materials have promising applications in lithium-ion batteries owing to their high energy density and reasonable cost. The surface stabilization of these materials is vital for achievingexcellent electrochemical performance. In this study, a fast ionic conductor, Li6.25La3Zr2Al0.25O12 (LLZAO), was successfully coated on the surface of LiNi0.88Co0.05Mn0.07O2 (LNCM) using a polydopamine (PDA) modification method. The abundant catechol groups of the intermediate PDA layer on the Ni0.88Co0.05Mn0.07(OH)2 (NCM(OH)2) precursor attracted metal ions in an aqueous solution, and a uniform LLZAO coating layer was formed after calcination under an O2 flow. The presence of the LLZAO protective film on the surface of LNCM was confirmed using several characterization techniques. The LLZAO-coated LNCM exhibited superior electrochemical properties compared to those of the pristine LNCM. Moreover, the LLZAO-coated LNCM demonstrated excellent electrochemical stability even at a high temperature (60 ℃). The deterioration of the surface structure of LNCM was significantly suppressed by the formation of the LLZAO coating layer, and LLZAO improved the Li+ ion transport at the electrode/electrolyte interface.

Highly transparent conductive F-doped SnO2 films prepared on polymer substrate by radio frequency reactive magnetron sputtering

F-doped SnO2 (FTO) films have excellent optical-electrical properties and have been widely used, but the preparation of FTO film on the surface of flexible polymer substrate by magnetron sputtering has not been reported. In this study, Sn-SnF2 mixture was used as the target, and then the FTO film was prepared by reactive magnetron sputtering on the surface of the polyethylene terephthalate substrate at substrate temperature of room temperature, 60 and 100 °C. The results show that highly transparent conductive FTO films can be obtained by optimizing the O2 flow rate at each substrate temperature. In general, as the substrate temperature increases, the optimized range of O2 flow rate shifts to the direction of lower O2 flow rate and the corresponding transparent conductive properties are slightly enhanced. Currently, the films show sheet resistance of 209–423 Ω/sq., transmittance in visible-light range of 84.4–90.3% and figure of merit of 5.09–12.9 × 10–4 Ω–1, which is comparable with those of previously reported SnO2-based films. At the same time, the films have better bending performance at the bending radius of 20 mm, but they have poor damp-heat stability. In addition, the influence of substrate temperature and O2 flow rate on structure (thickness, crystallinity and surface roughness) and energy gap of the films is also investigated.

837-P: Hypoxemic COVID-Pneumonia, Diabetes Mellitus: Combination of Tailored Prednisone, Colchicine, Antithrombotics, Diuretic Improves Prognosis (CocAA-CoLa PLUS Study)

In patients (pts) with diabetes mellitus (DM) , Covid-pneumonia mortality rate &amp;gt;20% has been reported. A low fixed dose of intravenous dexamethasone (Dx) for days (RECOVERY study, 6 mg/d, i.e 0.5 mg/kg/d prednisone equivalent) has been shown to effectively reduce Covid-pneumonia mortality. In an observational study, prognosis was improved with an oral combination of prednisone fixed dose (1mg/kg/d) , direct anticoagulant/aspirin/colchicine/furosemide (DOAACF) . We hypothesized prednisone tailored doses driven by clinical evolution (extra 1mg/kg/d for every increase of O2 flow) added-on DOAACF for days would decrease morbi-mortality. In our monocentric, retrospective study (03.2020-05.2021) , pts with Covid-pneumonia requiring O2 out of the Intensive Care Unit (ICU) were included. According to the Physicians discretionary caring decisions, a control group (no corticoid) , a Dx group, an oral tailored prednisone ≥1mg/kg/d-DOAACF group were compared. The primary endpoint was Day 28 ICU requirement or mortality. Out of 3pts included for hypoxemic Covid-pneumonia, 132 pts had DM (43%) (control n = 28; Dx n = 46; tailored prednisone-DOAACF n = 58) : median age 69y; Males/Females 2.8; BMI 28 kg/m2; cardiovascular history 40%; median SpO2 at room air 92%; median maximal O2 flow 4L/min. Pts characteristics were non statistically different. Prednisone median dose (1.5mg/kg/d) and aspirin-colchicine-furosemide use were significantly higher in the tailored prednisone-DOAACF group in which events rate (12%) was significantly lower (control 50%, p = 0.0003, Dx 37%, p = 0.004) . In the tailored group, no statistical difference observed with pts without DM (13.3%, p = 1) . Out of the ICU, in pts with DM, a five oral drugs combination made of tailored prednisone ≥1mg/kg/d, anti-inflammatory, antithrombotics, diuretic improves hypoxemic Covid-pneumonia prognosis. A randomized trial is needed. Disclosure J.Kevorkian: None. B.Mégarbane: None. F.Féron: None. J.Riveline: None. F.Mauvais-jarvis: Consultant; Mithra Pharmaceutical. J.Gautier: Other Relationship; Novo Nordisk, Sanofi, Speaker's Bureau; Eli Lilly and Company.

Low irradiance disrupts the internal O2 dynamics of seagrass (Thalassia testudinum) leading to shoot meristem H2S intrusion

Hypoxia and hydrogen sulfide (H2S) intrusion at night contribute to large-scale seagrass mortality events world-wide. Declining water quality has lowered irradiance and enhanced hypoxia in seagrass ecosystems, but linkages between low irradiance and seagrass internal pO2in situ are not well understood. We examined low irradiance effects on leaf and meristem pO2 dynamics of a dominant tropical seagrass, Thalassia testudinum, using microsensors over multiple diurnal cycles. Further, we determined how O2 dynamics affect H2S intrusion into shoot meristems under low irradiance. Sequential days of low irradiance disrupted internal leaf O2 status in three ways: i) causing a longer lag in morning O2 pressurization, ii) depressing maximum pO2 during the day, and iii) shortening the time where maximum pO2 was sustained into the afternoon. There was a close relationship between leaf and water column pO2 during the day (R2 = 0.93 ± 0.09); thus, internal O2 dynamics appear more dependent on water column pO2 under low irradiance. The nighttime minimum of leaf and meristem pO2 (1.2 and 0.4 kPa, respectively) were very low and the length of time the meristem sustained hypoxia (< 1.5 kPa pO2) at night was high (9:40 h:min). H2S intrusion into the meristem at night following 24–48 h of shading was persistent, likely the combined effect of limited internal O2 flow without saturating irradiances for photosynthesis, and a breakdown of the sediment oxic microshield. Under low irradiance, more frequent intrusions of H2S to the meristems increases the chances of large-scale seagrass mortality events at night.