High Oxygen Concentrations Research Articles

Analysis of Oxygen Concentration in the Oral Cavity During Intravenous Sedation with Intranasal Oxygen Administration for Dental Treatment.

Intravenous sedation (IVS) with propofol (PPF) is commonly performed in dental treatment, particular in patients with dentophobia, with gag reflex, or undergoing implant surgeries, as PPF has the advantages of rapid induction and recovery. However, PPF and other intravenous sedatives may cause respiratory depression. Thus, IVS with PPF requires oxygen administration. But airway burn may occur when high-concentration oxygen is stored in the oral cavity and catches fire. For these reasons, the present study aimed to elucidate the changes in oxygen concentration (OC) under IVS with PPF and oxygen administration. Nineteen healthy male volunteers participated in the study. None of them had missing teeth, nasal congestion, or temporomandibular joint dysfunction. They were sedated with a continuous PPF infusion dose of 6 mg/kg/hr for 25 min, followed by administration of 3 L/min oxygen via a nasal cannula. The OC was measured at two sites, namely, the median maxillary anterior teeth (MMAT) and median maxillary soft palate (MMSP), before PPF infusion (baseline) and 14, 15-18 (Term 1), 19, and 20-23 (Term 2) min after the start of infusion. Compared with the values at baseline, the OC in the MMSP significantly increased at each time point, whereas the OC in the MMAT significantly increased at Term 2. Furthermore, in the comparison of the OC before and after the use of a mouth prop, the OC exhibited an upward trend, but no statistically significant differences were observed between the two time points in the MMAT and MMSP. In IVS with PPF and oxygen administration, the OC in the pharynx increases as the sedative level deepens. Oxygen administration should be temporarily discontinued, and suction should be performed to decrease the OC in the oral cavity when sparking procedures during IVS with PPF and oxygen administration are performed.

Characterization of aerosol composition: Insights from SEM-EDX analysis and CALIPSO overpasses

The effect of atmospheric aerosols on the earth’s radiation budget is primarily through their direct effects. Understanding aerosols’ morphology and elemental composition is crucial in this context. For two years, from January 2017 to December 2018, aerosol samples (PM10) were collected on quartz filter papers using a high-volume sampler (PM10) in Chennai, a semi-urban coastal environment located at 12.81°N, 80.03°E. These filter papers were stored under ambient laboratory conditions and were subsequently subjected to ultrasonication using ethanol as the solvent to separate the aerosols from the filters. The extracted samples were then analyzed using scanning electron microscopy (SEM) for the morphology and energy dispersive X-ray analysis (EDX) for elemental composition. The EDX analysis of the samples revealed the presence of various elements such as carbon (C), oxygen (O), aluminum (Al), silicon (Si), sulfur (S), potassium (K), iron (Fe), magnesium (Mg), calcium (Ca), vanadium (V), bismuth (Bi), sodium (Na), chlorine (Cl), phosphorus (P), and technetium (Tc). High concentrations of carbon, oxygen, and aluminum–silicate particles indicated the presence of carbonaceous aerosols and wind-blown dust particles. Concentration-weighted trajectory (CWT) analysis was carried out to assess the transport pathways of aerosols in the region. CALIPSO overpasses during the study period were selected, and the Vertical Feature Mask (VFM) identifiers for different aerosol types were compared with the local experimental results. The findings show that CALIPSO possess a reasonably effective capability in detecting and characterizing the local aerosol types. CALIPSO detected Dusty marine, Clean marine, Elevated smoke and Polluted dust in the study area across all four seasons. These findings closely match the characteristics of such aerosol types obtained from SEM/EDX analysis, HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) modeling, and the Angstrom exponent derived from sunphotometer readings.

Mechanism Analysis and Potential Applications of Atomic Oxygen Erosion Protection for Kapton-Type Polyimide Based on Molecular Dynamics Simulations.

Polyimide (PI) is widely used in aerospace applications due to its excellent properties. However, the high concentration of atomic oxygen (AO) in low-earth orbit (LEO) significantly degrades its performance. This study employs reactive molecular dynamics (MD) simulations to analyze the AO erosion resistance of fluorinated polyimide (FPI) and polyhedral oligomeric silsesquioxane (POSS) composite polyimide models. The 35 ps simulation results indicate that the PI/POSS composite exhibits the best protective performance. The protection mechanism involves the formation of an SiO2 carbonized layer that prevents the transmission of AO and heat to the polyimide matrix, resulting in a normalized mass of 84.1% after erosion. The FPI model shows the second-best protective effect, where the introduction of -CF3 groups enhances the thermal stability of the polyimide matrix, resulting in a normalized mass of 80.7% after erosion. This study explores the protective effects and mechanisms of different polyimide protection methods at the molecular level, providing new insights for the design of AO erosion protection systems.

Induced Power Scaling Alone Cannot Explain Griffenfly Gigantism.

Paleozoic skies were ruled by extinct odonatopteran insects called "griffenflies," some with wingspans 3 times that of the largest extant dragonflies and 10 times that of common extant dragonflies. Previous studies suggested that flight was possible for larger fliers because of higher atmospheric oxygen levels, which would have increased air density. We use actuator disk theory to evaluate this hypothesis. Actuator disk theory gives similar estimates of induced power as have been estimated for micro-air vehicles based on insect flight. We calculate that for a given mass of griffenfly, and assuming isometry, a higher density atmosphere would only have reduced the induced power required to hover by 11%, which would have supported a flyer 3% larger in linear dimensions. Steady-level forward flight would have further reduced induced power but could only account for a flier 5% larger in linear dimensions. Further accounting for the higher power available due to high-oxygen air and assuming isometry, we calculate that the largest flyer hovering would have been only 1.19times longer than extant dragonflies. We also consider known allometry in dragonflies and estimated allometry in extinct griffenflies. But such allometry only increases flyer size to 1.22times longer while hovering. We also consider profile and parasite power, but both would have been higher in denser air and thus would not have enhanced the flyability of larger griffenflies. The largest meganeurid griffenflies might have adjusted flight behaviors to reduce power required. Alternatively, the scaling of flight muscle power may have been sufficient to support the power demands of large griffenflies. In literature estimates, mass-specific power output scales as mass0.24 in extant dragonflies. We need only more conservatively assume that mass-specific muscle power scales with mass0, when combined with higher oxygen concentrations and induced power reductions in higher-density air to explain griffenflies 3.4times larger than extant odonates. Experimental measurement of flight muscle power scaling in odonates is necessary to test this hypothesis.

Oxygenation and Carbon Dioxide Rebreathing of a Well-fitting Non-rebreathing EcoLite™ Mask with a Reservoir: A Single-center Prospective Observational Study in Healthy Volunteers.

The fitting of oxygen mask affects the performance of it such as oxygenation or CO₂ elimination. The intersurgical EcoLite™ adult high-concentration oxygen mask (EcoLite with a reservoir, Intersurgical, UK) was developed to give well-fitting. The purpose of this study is to evaluate the performance of EcoLite with a reservoir compared to the conventional mask. Ten healthy volunteers were included in this study. EcoLite with a reservoir and conventional mask were given to patients at different oxygen flow rates (5, 8, 10, 12, and 15 L/min). Fraction of inspiratory O₂ (FIO₂) and partial pressure of inspiratory CO₂ (PICO₂) were measured by a sampling tube at the middle pharynx inserted via nose. The EcoLite with a reservoir had a significantly higher FIO₂ than the control reservoir mask. However, the PICO₂ was significantly higher in the EcoLite with a reservoir than in the control reservoir mask, especially when the oxygen flow rate was low. The EcoLite with a reservoir provided improved oxygenation and a better fit than the conventional reservoir masks in healthy volunteers. However, the EcoLite with a reservoir might cause higher CO₂ rebreathing at low oxygen flow rates.

Diffusion characteristics of vertical oxygenic-thermal coupled jet and indoor oxygenic-thermal environment regulation in high-altitude areas

The Qinghai-Tibet Plateau has typical climatic phenomena such as low temperatures and oxygen deficiency, which have a great impact on the health of local residents. In order to improve the indoor oxygenic-thermal environment, this paper explored the flow characteristics of a vertical oxygenic-thermal coupled jet by CFD numerical simulation and experimental verification in high-altitude areas. The results found that the oxygenic-thermal diffusion range moved up by 0.17m–1.02 m in the vertical direction as the jet temperature increased by 3K–9K, and this process could enhance the synergistic effect of the oxygenic-thermal diffusion, while the oxygen flow supply reduced this effect, and the diffusion range shifted down by 0.87m–1.90 m as the jet oxygen concentration increased by 20%–60%. The indoor airflow uniformity with ΔT = 3K was more desirable than that with ΔT = 9K, and a high oxygen concentration was detrimental to temperature elevation, so a slight variation in temperature and concentration could be selected when meeting the demand for indoor heating and oxygen supply. The air inlet position has a more significant effect on the thermal environmental distribution than the oxygen environment, and the coupled airflow non-uniformity coefficient is minimized when the air inlet is located at the top center of the room. This study would provide some recommendations for regulating the indoor oxygenic-thermal environment in high-altitude areas under vertical jet mode.

Conductivity and chemical stability of co-doped LaScO3 ceramics

New materials based on LaScO3, namely, were synthesized by the solid-phase method. The structure of the resulting complex oxides was refined. The electrical properties of the undoped, mono- and co-doped samples were determined by varying the temperature T and pH2O. All substituted samples were found to have the conductivity of several orders of magnitude higher relative to the parent phase. The maximum conductivity was observed for the Ba2+/Mg2+-co-doped sample due to high concentration of oxygen vacancies The possibility of phase formation and its electrical properties are greatly influenced by geometric parameters such as the ratio of the radii of the host- and the dopant-ion, the free cell volume, the critical radius. It has been demonstrated that the nature of the dopant affects the porosity of the samples. The investigated phases demonstrate good chemical stability in a CO2-saturated atmosphere.

A Deep Dive into the Role of Hyperbaric Oxygen Therapy in Enhancing Burn Wound Healing

Burn injuries are a significant cause of admissions to burn and plastic surgery units. One treatment modality for burn injury patients is hyperbaric oxygen therapy (HBOT). HBOT exposes patients to high concentrations of oxygen at increased atmospheric pressure levels. It can enhance burn wound healing by promoting cellular response, inflammatory cytokines, neovascularization, and collagen formation. This review explores the role of HBOT in enhancing burn wound healing, particularly in plastic surgery. We gathered and analyzed information from various web databases, using specific keywords related to burn wound injuries and HBOT. Inclusion criteria encompassed open-access journals and articles relevant to the subject matter. This review revealed that despite some controversial findings and the absence of treatment guidelines for burn patients, HBOT can complement other modalities. Side effects may include neurological and ophthalmic toxicity, as well as mild effects such as nausea and gastrointestinal disturbance. In conclusion, HBOT serves as an adjunctive therapy for promoting wound healing, including in burn patients. Evidence suggests its effectiveness in plastic surgery, potentially reducing hospital stays, costs, and recovery times. Further prospective randomized controlled trials with larger sample sizes and blinding are necessary to address remaining controversies and evaluate the full benefits of HBOT.

Quantitive HAZOP and D-S evidence theory-fault tree analysis approach to predict fire and explosion risk in inert gas system on-board tanker ship

Tanker ships carry volatile cargo, presenting inherent risks of fire and explosion. Inert gas systems (IGS) are pivotal in mitigating risks by displacing oxygen in cargo tanks. However, failure of IGS components may lead to fatal consequences such as loss of life and marine pollution. This paper prompts a systematic approach integrating Quantitative Hazard and Operability (HAZOP) analysis under D-S (Dempster–Shafer) evidence theory and Fault Tree Analysis (FTA) to predict and quantify the fire and explosion risk associated with IGS malfunction on tanker ships. The methodology systematically evaluates failure probabilities, and consequences using HAZOP to identify critical scenarios. D-S evidence theory is employed to address uncertainties and incorporate expert knowledge into the analysis. FTA is applied to model fault propagation and assesses the likelihood of fire and explosion events based on the identified failure scenarios. A case study is presented to demonstrate the application of the proposed methodology, illustrating effectiveness in identifying high-risk scenarios and providing insights for enhancing operational safety minimising the risk of IGS on tanker ships. The findings show that the risk of fire and explosion in the inert gas system due to the high concentration of oxygen entering the tank was found to be 2.86E-01. Besides its robust theoretical background, the findings of the paper provide the utmost contribution to ship crew, ship inspectors, HSEQ managers and safety professionals for proactive risk mitigation strategies, contributing to the advancement of safety management practices in the maritime industry.

Microbial central carbon metabolism in a tidal freshwater marsh and an upland mixed conifer soil under oxic and anoxic conditions.

The central carbon (C) metabolic network is responsible for most of the production of energy and biosynthesis in microorganisms and is therefore key to a mechanistic understanding of microbial life in soil communities. Many upland soil communities have shown a relatively high C flux through the pentose phosphate (PP) or the Entner-Doudoroff (ED) pathway, thought to be related to oxidative damage control. We tested the hypothesis that the metabolic organization of the central C metabolic network differed between two ecosystems, an anoxic marsh soil and oxic upland soil, and would be affected by altering oxygen concentrations. We expected there to be high PP/ED pathway activity under high oxygen concentrations and in oxic soils and low PP/ED activity in reduced oxygen concentrations and in marsh soil. Although we found high PP/ED activity in the upland soil and low activity in the marsh soil, lowering the oxygen concentration for the upland soil did not reduce the relative PP/ED pathway activity as hypothesized, nor did increasing the oxygen concentration in the marsh soil increase the PP/ED pathway activity. We speculate that the high PP/ED activity in the upland soil, even when exposed to low oxygen concentrations, was related to a high demand for NADPH for biosynthesis, thus reflecting higher microbial growth rates in C-rich soils than in C-poor sediments. Further studies are needed to explain the observed metabolic diversity among soil ecosystems and determine whether it is related to microbial growth rates.IMPORTANCEWe observed that the organization of the central carbon (C) metabolic processes differed between oxic and anoxic soil. However, we also found that the pentose phosphate pathway/Entner-Doudoroff (PP/ED) pathway activity remained high after reducing the oxygen concentration for the upland soil and did not increase in response to an increase in oxygen concentration in the marsh soil. These observations contradicted the hypothesis that oxidative stress is a main driver for high PP/ED activity in soil communities. We suggest that the high PP/ED activity and NADPH production reflect higher anabolic activities and growth rates in the upland soil compared to the anaerobic marsh soil. A greater understanding of the molecular and biochemical processes in soil communities is needed to develop a mechanistic perspective on microbial activities and their relationship to soil C and nutrient cycling. Such an increased mechanistic perspective is ecologically relevant, given that the central carbon metabolic network is intimately tied to the energy metabolism of microbes, the efficiency of new microbial biomass production, and soil organic matter formation.

Performance of ammonia catalytic combustion over Cu-CeOx catalyst and the impact of oxygen concentration

Ammonia has long been regarded as a high-quality zero-carbon fuel; however, limitations in its combustion characteristics have restricted its practical applications. Catalytic combustion is considered an effective solution to overcome the challenges associated with ammonia combustion. In this study, we successfully synthesized a copper-cerium binary catalyst (Cu-CeOx) using the sol-gel method, demonstrating outstanding performance for NH3 catalytic combustion. Through in-situ DRIFTS results, we observed that the 15Cu-CeOx catalyst exhibits both i-SCR and -NH mechanisms. The oxygen concentration affects the N2 selectivity by modulating the overoxidation of NH3. Under high oxygen concentrations, high temperatures promote the excessive oxidation of NH3, and ammonia combustion through the i-SCR mechanism. Conversely, the oxygen concentration was equal to NH3 reaction stoichiometry, the overoxidation of NH3 is limited, and ammonia combustion proceeds through the NH mechanism, resulting in higher N2 selectivity.

Effects of in-cylinder water injection on knocking and combustion stability generated by expanding the lean burn limit

The integration of direct water injection (DWI) with the lean burn (LB) process can significantly enhance engine performance. This study reveals that an increase in the water-fuel (W/F) ratio suppressed knocking by extending the ignition delay time. Specifically, the knocking of stoichiometric combustion was suppressed, while that of deeper LB (excess air ratio (λ)˃1.5) was sensitive to a larger W/F ratio. The intensity of knocks during stoichiometric combustion decreased significantly (more than twofold) when the W/F ratio increased from 0.1 to 0.2. Under identical W/F conditions, a shorter ignition delay (CA0–10) and combustion duration (CA10–90) of the main combustion flame were identified as important factors for knocking when λ increased from 1 to 1.5. However, for λ values exceeding 1.5, CA10–90 emerged as the primary knocking determinant. Faster flame propagation and higher oxygen concentration caused by LB and an early spark promoted autoignition of the end-gas and increased the autoignition heat release rate, thus strengthening knock intensity (KI). Furthermore, a minimal amount of water (W/F ≤ 0.3) exerted negligible influence on the stoichiometric combustion stability. As the LB approached its limit, the average KI remained relatively consistent, with combustion stability emerging as the key factor in elevating the LB performance. A 0.3 W/F ratio and precise spark timing ensured that a balance exists between combustion stability and knocking, while simultaneously elevating λ to 2.0.

Thermodynamic and exergy assessment of a biomass oxy-fuel combustion with supercritical carbon dioxide cycle under various recycle flue gas conditions

The ongoing development of second-generation oxy-fuel combustion system with higher oxygen concentration have presented a potential pathway for efficient biomass utilization. It also signified the meticulous role of recycled flue gas in altering the combustion behaviour in the combustor. Accordingly, investigation into different recirculation modes focusing on recycle ratio, wet/dry conditions, and excess oxygen ratio are conducted with an indirect supercritical power cycle integrated biomass oxy-fuel combustion system. Energy and exergy analyses, as well as composition of flue gas produced are presented. Energy and exergy efficiencies increased with reducing recycle ratio, with respective highest efficiency of 31.33% and 44.37% obtained at excess oxygen ratio of 1.01 and recycle ratio of 0.5 under wet condition. Investigation of CO2 and H2O concentration in produced flue gas depicted a separated stage profile under dry recycle condition, different from the slight diverging profile observed under wet condition when the recycle ratio varied. Concentration of NOx and SOx increased with decreasing recycle ratio and are generally higher under dry condition. Selective exergy analyses of the proposed power cycle presented highest exergy loss in the combustor, followed by the air separation unit, heat exchanger, CO2 compression and purification unit, and turbine generator. Based on the obtained result, wet recycle flue gas enhanced the combustion performance in the combustor but slightly impaired the convective heat transfer in the heat exchanger. The performance of proposed biomass power cycle is optimized at low recycle ratio of 0.5 under wet recycle condition.

Biological degradation of organic micropollutants in GAC filters–temporal development and spatial variations

The capacity for organic micropollutant removal in granular activated carbon (GAC) filters for wastewater treatment changes over time. These changes are in general attributed to changes in adsorption, but may in some cases also be affected by biological degradation. Knowledge on the degradation of organic micropollutants, however, is scarce. In this work, the degradation of micropollutants in several full-scale GAC and sand filters was investigated through incubation experiments over a period of three years, using 14C-labeled organic micropollutants with different susceptibilities to biological degradation (ibuprofen, diclofenac, and carbamazepine), with parallel 16S rRNA gene sequencing. The results showed that the degradation of diclofenac and ibuprofen in GAC filters increased with increasing numbers of bed volumes when free oxygen was available in the filter, while variations over filter depth were limited. Despite relatively large differences in bacterial composition between filters, a degradation of diclofenac was consistently observed for the GAC filters that had been operated with high influent oxygen concentration (DO >8 mg/L). The results of this comprehensive experimental work provide an increased understanding of the interactions between microbial composition, filter material, and oxygen availability in the biological degradation of organic micropollutants in GAC filters.

Influence of powder surface chemistry on the defect formation in AlSi10Mg alloy processed via laser powder bed fusion additive manufacturing

In laser powder bed fusion(LPBF) additive manufacturing(AM) of Al alloys, surface chemistry and dissolved gas composition(oxygen/oxides/hydroxides, hydrogen and moisture) of AM powders is a major influencing factor for porosity formation. Therefore, in the present investigation, this aspect is addressed using two sets of virgin AM AlSi10Mg powders, namely, Hi-Ox (2770 ppm oxygen) and Lo-Ox (660 ppm oxygen), to assess the printability under various processing parameters and defect formation in printed parts. Comprehensive and in-depth metallurgical analysis of both powders utilizing multiple characterisation techniques established the presence of various types of oxides/hydroxides with different complex chemistries on the powders’ surface. Enhanced spherical gas porosity and oxide inclusions were witnessed in Hi-Ox print coupons in contrast to the least defects in Lo-Ox coupons rationalized due to surface chemistry difference between the virgin powders. Consequently, the mechanical properties of the Hi-Ox print coupons, even with minimum defect density, are significantly inferior to Lo-Ox specimens. These observations suggest a competing influence of surface chemistry/dissolved gas composition and laser parameters for the processing of both powders. Overall, by correlating the microstructures with processing conditions and oxide concentration, defects morphology, the probable melt pool formation mechanism in LPBF of AlSi10Mg alloy (for high and low oxygen concentration) is elucidated.

Multi-physical effects induced by spatiotemporal corrosion of T91 cladding in oxygen-controlled LBE environment

T91, a pivotal candidate material for cladding in lead-based fast reactors (LFRs), demonstrates considerable potential for corrosion resistance in liquid lead-bismuth eutectic (LBE) corrosion experiments. However, the multi-physics characteristics of T91 cladding corrosion in its operational environment remain unclear, posing an obstacle to its practical application. This study focuses on the spatiotemporal corrosion of T91 cladding in multi-physics coupling scenarios by means of COMMA (Cladding/Oxidation corrosion Multi-physics Modeling and Analysis code), in which, modules of cladding oxidation, cladding oxide removal, heat transfer, mechanical deformation, and fission gas release are integrated and collaboratively solved. The corrosion patterns of T91 cladding with different oxygen concentrations and the underlying multi-physics behavior of the corrosion processes under operational conditions simulating are summarized. For the lower oxygen concentration of 1.8e-9 wt% in LFRs, the results indicate a 0.2 m axial zone with base material exposed to LBE reveals the presence of the oxidation protection failure. An exacerbation of cladding heat transfer degradation is observed after oxygen concentration reaching the oxygen-dominant region, due to the enhanced temperature positive feedback of oxidation corrosion. For the high oxygen concentration of 1.4e-6 wt%, an axial offset of 0.24 m for the location of the minimum gap size is observed. This study identifies a trend of the reduction thickness of cladding that first decreasing and then increasing with an elevated oxygen concentration, attributed to a transition in corrosion patterns. The temperature and mechanical analyses indicate that the optimal oxygen concentration for corrosion inhibition and fuel safety is located around the critical oxygen-dominant concentration.

Nitrate and oxygen significantly changed the abundance rather than structure of sulphate-reducing and sulphur-oxidising bacteria in water retrieved from petroleum reservoirs.

Sulphate-reducing bacteria (SRB) are the main culprits of microbiologically influenced corrosion in water-flooding petroleum reservoirs, but some sulphur-oxidising bacteria (SOB) are stimulated when nitrate and oxygen are injected, which control the growth of SRB. This study aimed to determine the distributions of SRB and SOB communities in injection-production systems and to analyse the responses of these bacteria to different treatments involving nitrate and oxygen. Desulfovibrio, Desulfobacca, Desulfobulbus, Sulfuricurvum and Dechloromonas were commonly detected via 16S rRNA gene sequencing. Still, no significant differences were observed for either the SRB or SOB communities between injection and production wells. Three groups of water samples collected from different sampling sites were incubated. Statistical analysis of functional gene (dsrB and soxB) clone libraries and quantitative polymerase chain reaction showed that the SOB community structures were more strongly affected by the nitrate and oxygen levels than SRB clustered according to the sampling site; moreover, both the SRB and SOB community abundances significantly changed. Additionally, the highest SRB inhibitory effect and the lowest dsrB/soxB ratio were obtained under high concentrations of nitrate and oxygen in the three groups, suggesting that the synergistic effect of nitrate and oxygen level was strong on the inhibition of SRB by potential SOB.

The predictive and prognostic value of risk factors in patients receiving hybrid coronary revascularization with postoperative pulmonary complications.

The mortality rate of coronary artery disease ranks first in developed countries, and coronary revascularization therapy is an important cornerstone of its treatment. The postoperative pulmonary complications (PPCs) in patients receiving one-stop hybrid coronary revascularization (HCR) aggravate the dysfunction of multiple organs such as the heart and lungs, therefore increasing mortality. However, the risk factors are still unclear. The objective of this study was to explore the risk factors of PPCs after HCR surgery. In this study, the perioperative data of 311 patients undergoing HCR surgery were reviewed. All patients were divided into two groups according to whether the PPCs occurred. The baseline information and surgery-related indicators in preoperative laboratory examination, intraoperative fluid management, and anesthesia management were compared between the two groups. Advanced age [odds ratio (OR): 1.065, 95% confidence interval (CI): 1.030-1.101, P<0.001], high body mass index (BMI; OR: 1.113, 95% CI: 1.011-1.225, P=0.02), history of percutaneous coronary intervention (PCI) surgery (OR: 2.831, 95% CI: 1.388-5.775, P=0.004), one-lung volume ventilation (OR: 3.804, 95% CI: 1.923-7.526, P<0.001), inhalation of high concentration oxygen (OR: 3.666, 95% CI: 1.719-7.815, P=0.001), the application of positive end-expiratory pressure (PEEP; OR: 2.567, 95% CI: 1.338-4.926, P=0.005), and long one-lung ventilation time (OR: 1.015, 95% CI: 1.006-1.023, P=0.001) may be risk factors for postoperative PPCs in patients undergoing one-stop coronary revascularization surgery. Using the above seven factors to jointly predict the risk of PPCs in patients undergoing one-stop coronary revascularization surgery, the receiver operating characteristic (ROC) curve showed an area under the curve (AUC) =0.873, 95% CI: 0.835-0.911, sensitivity: 84.81%, and specificity: 75.82%; the predictive model was shown to be effective. Patients undergoing HCR surgery with advanced age, high BMI, a history of PCI surgery, one-lung volume ventilation, inhalation of high concentration oxygen, use of PEEP, and prolonged single lung ventilation are more prone to PPCs.

NOx emissions during oxygen-enriched combustion of sewage sludge and corresponding hydrochar

This study proposed an oxygen-enriched combustion technology for the resource utilization of hydrochar prepared from sewage sludge (SS) through hydrothermal carbonization (HTC). However, its application potential relies heavily on NOx emissions. To investigate NOx emissions during oxygen-enriched combustion of hydrochars prepared at different temperatures (200 °C, 240 °C, and 280 °C), real-time NOx concentrations were recorded under varying conditions, including different carrier gases (N2 and CO2), temperatures (600 °C, 800 °C, and 1000 °C), and oxygen concentrations (20 %, 30 %, and 40 %). In comparison to air combustion processes, the NOx emissions during the devolatilization stage were considerably depressed in oxygen-enriched combustion. A high concentration of CO2 inhibited NH3 production and HCN oxidation, and generated increased amounts of CO to facilitate NOx reduction. Elevated temperatures also reduced the NOx release during the oxygen-enriched combustion of SS and hydrochar, as the accelerated oxygen consumption weakened the oxidation reactions of HCN and NH3; the enhanced reduction reaction rate and increased CO production also promoted NOx reduction. Elevated oxygen concentrations, however, promoted NOx release owing to the increased NH3 and HCN oxidation by an increased number of oxidizing groups. Additionally, the reduction of reducing gases and rapid char combustion hindered NOx reduction. The NOx-N conversion of the hydrochars was much lower than that of SS under different conditions. HTC effectively reduced the nitrogen content of SS, with nitrogen in HC-280 existing as stable heterocyclic -N. HC-280 showed significantly less nitrogen conversion at low temperatures (9.03 % reduction at 600 °C) and high oxygen concentrations (2.01 % reduction at 40 % O2) compared to SS, highlighting the potential of combining HTC and oxygen-enriched combustion.

Oxygen and HIF1α-dependent SDF1 expression in primary astrocytes.

In the naturally hypoxic in utero fetal environment of preterm infants, oxygen and oxygen-sensitive signaling pathways play an important role in brain development, with hypoxia-inducible factor-1α (HIF1α) being an important regulator. Early exposure to nonphysiological high oxygen concentrations by birth in room can induce HIF1α degradation and may affect neuronal and glial development. This involves the dysregulation of astroglial maturation and function, which in turn might contribute to oxygen-induced brain injury. In this study, we investigated the effects of early high oxygen exposure on astroglial maturation and, specifically, on astroglial stromal cell-derived factor 1 (SDF1) expression in vivo and in vitro. In our neonatal mouse model of hyperoxia preterm birth brain injury in vivo, high oxygen exposure affected astroglial development and cortical SDF1 expression. These results were further supported by reduced Sdf1 expression, impaired proliferation, decreased total cell number, and altered expression of astroglial markers in astrocytes in primary cultures grown under high oxygen conditions. Moreover, to mimic the naturally hypoxic in utero fetal environment, astroglial Sdf1 expression was increased after low oxygen exposure in vitro, which appears to be regulated by HIF1α activity. Additionally, the knockdown of Hif1α revealed HIF1α-dependent Sdf1 expression in vitro. Our results indicate HIF1α and oxygen-dependent chemokine expression in primary astrocytes and highlight the importance of oxygen conditions for brain development.