Oxygen Concentration Ratio Research Articles

NO Emission Characteristics of Pulverized Coal Combustion in O2/N2 and O2/H2O Atmospheres in a Drop-Tube Furnace.

Oxy-steam combustion is a new oxy-fuel combustion technology. This paper focuses on the NO emission characteristics during the combustion of SF (Shen Fu) coal in O2/N2 and O2/H2O mixtures. Experiments were performed in a drop-tube furnace. Combustion tests were carried out in O2/N2 and O2/H2O atmospheres for various O2 concentrations (21%, 30%, 40%, and 60%) at different temperatures (1173 K, 1273 K, and 1373 K). In addition, combustion experiments at different excess oxygen ratios (λ) were conducted in O2/N2 and O2/H2O atmospheres. The influences of the atmosphere, oxygen concentration, temperature, and excess oxygen ratio on NO emissions were analyzed. The results show that the NO concentrations of SF coal combustion in the 21% O2/79% H2O atmosphere were much lower than those in the 21% O2/79% N2 atmosphere at the three temperatures considered. This was because a large amount of NO was decomposed during the SF coal combustion in the O2/H2O atmospheres. The reasons for the decomposition of NO include the selective non-catalytic reaction (SNCR) mechanism and char's important role as a catalyst for the destruction of NO, either directly or by reacting with CO or H2. In oxy-steam combustion, the NO concentrations significantly increased with the increase in the oxygen concentration from 21 vol.% to 60 vol.% and the temperature from 1173 K to 1373 K. The excess oxygen ratio (λ) slightly impacted the NO emissions in the O2/H2O atmosphere.

Pulsatile Right Ventricle to Pulmonary Artery Extracorporeal Membrane Oxygenation in a Pigs

Background: We investigated the impact of right ventricle to pulmonary artery extracorporeal membrane oxygenation in acute respiratory dysfunction with or without pulsatile flow. Methods: We used bronchoalveolar lavage with intrapulmonary administration of warm saline to establish a severe acute respiratory distress syndrome model (ratio of partial pressure of oxygen in arterial blood to the fraction of inspiratory oxygen concentration ratio <200) in eight piglets (mean body weight: 8.45±1.24 kg). The piglets were categorized into the pulsatile (N=4) and non-pulsatile extracorporeal membrane oxygenation groups (N=4). We started right ventricle to pulmonary artery extracorporeal membrane oxygenation with a 60 mL/kg/min flow to support the animals for 6 hours. We monitored hemodynamic data and blood gas levels for assessing base excess, and performed arterial blood sampling and electrocardiogram. Interleukin-6 and endotherlin-1 concentrations in blood plasma were evaluated before and after right ventricle to pulmonary artery extracorporeal membrane oxygenation. We compared the lung wet/dry weight ratio as a measure of pulmonary edema and collected lung tissue samples for the pathologically evaluating pneumocytes before and after right ventricle to pulmonary artery extracorporeal membrane oxygenation. Results: We maintained stable hemodynamics and extracorporeal membrane oxygenation flow above an arterial oxygen saturation of 85% in both groups. Pneumocyte evaluation showed clearly less pulmonary edema, pulmonary fibrosis, and inflammation. Interleukin-6 concentration was less in the pulsatile group than in the non-pulsatile group. Conclusions: Pulsatile right ventricle to pulmonary artery extracorporeal membrane oxygenation was less vasoconstrictive and maintained more effective oxygenated pulmonary flow. It ameliorates pulmonary circulation and facilitates recovery from acute respiratory failure.

A case of self-limiting respiratory distress in a postpartum mother – transfusion related acute lung injury

A 37-year-old woman, treated for postpartum haemorrhage, developed sudden-onset acute respiratory distress characterised by tachypnoea, desaturation and widespread crepitations, on the first day postpartum. She had low partial pressure of oxygen to the fractional inspired oxygen concentration (PaO2/FiO2) ratio and bilateral patchy opacities in chest radiograph. Despite having a high oxygen requirement, her clinical and radiographic abnormalities spontaneously resolved in 30 hours, after a conservative treatment approach. This case report delves into the rare, yet serious entity of transfusion-related acute lung injury (TRALI) and underscores the importance of considering it among other potential causes of shortness of breath following blood transfusion in postpartum patients.

Changes in physicochemical parameters of the alpine/mountain stream influenced by summer flash flood in Tatra Mountains (Western Carpathians)

taChanges to the physicochemical parameters of water in alpine/mountain streams can provide evidence of ongoing natural and anthropogenic processes in their catchment. In this study, we analysed a mountain stream (Javorinka) on the north-eastern side of the Tatra Mountains (Western Carpathians), which is minimally influenced by human activity. The stream was monitored weekly for 5 years (2017–2021) and evaluated for its seasonal variations in physicochemical parameters. These seasonal variations were influenced by the large summer flash flood in July 2018. We hypothesise that floods are essential for the oligotrophic profile of alpine/mountain streams. To support this idea, our main objective was to compare the seasonal trends of the main physicochemical parameters in the stream before and after floods or periods of high flow. We found evidence to support our hypothesis. For example, there was a significant decrease in the chemical consumption of oxygen and ammonia, and, conversely, an increase in the ratio of saturated oxygen and nitrate concentrations. Stream bed erosion also resulted in increased phosphates (over the next 2 years) and high enrichment of the water by dissolved solids in the spring. Interestingly outside of the main objectives, we observed a significant decrease in sulphates, especially in the summer and autumn of 2020 and 2021, which may be related to suppressed emissions due to the restriction of the COVID-19 lockdown. The observed trends and their changes therefore support the idea that alpine/mountain streams are excellent indicators of ongoing environmental processes, and that occasional summer flash floods support the oligotrophic profile of the stream system.

NO emission during the co-combustion of biomass and coal at high temperature: An experimental and numerical study

Biomass/coal co-combustion presents a promising avenue for reducing carbon dioxide emissions. However, the mechanism of NO generation during co-combustion in pulverized coal-fired furnaces remains unclear. Herein, this study investigates NO emission characteristics at elevated temperatures, emphasizing mechanistic understanding. The experiments and simulations were conducted across temperatures ranging from 1000 °C to 1600 °C. In addition to exploring how fundamental conditions (temperature, oxygen concentration, and biomass blending ratio (BBR)) affect NO generation, the study also investigates the interactions between biomass and coal, as well as between fuel NO and thermal NO. The results indicate that the change in NO production with increasing temperature is non-monotonic, attributable to the combined contribution of fuel NO and thermal NO. Moreover, the interaction between biomass and coal manifests predominantly during the char combustion stage, owing to the disparate combustion characteristics and reactivity of biomass char and coal char. Numerical simulations were highly consistent with the experimental findings, underscoring a reduction in the rate of production (ROP) for major elementary reactions leading to NO formation as the BBR increased, consequently mitigating NO emissions. By integrating experimental insights with reaction kinetics calculations, this study proposes pathways for fuel NO and thermal NO generation during co-combustion at high temperatures, involving precursors such as NCO, HNO, and NH. These findings offer a deeper understanding of the mechanism of fuel NO and thermal NO emission during co-combustion at high temperatures.

Determination of the optimal total oxygen concentration and oxygen partitioning ratio based on the heat transfer characteristics of oxy-coal combustion in a swirl burner

Oxy-coal combustion is an attractive option for CO2 capture from coal-fired power plants due to high carbon capture efficiency and favorable economic performance. It is critical for the operation of the power plants to maintain similar heat transfer characteristics by rationalizing the partitioning strategy of the oxidant streams when retrofitting coal-fired power plants with oxy-fuel combustion technology. In the present work, the oxy-coal combustion characteristics under various total oxygen concentrations XO2,total of 21 %–32 % and oxygen partitioning ratio conditions in a 100 kW vertical swirl burner were numerically investigated by using computational fluid dynamics (CFD) models. And the effects of the XO2,total and oxygen partitioning ratio on the heat transfer characteristics of oxy-coal combustion were numerically simulated to quantitatively obtain the optimal oxygen supply partitioning strategy for the retrofitting of coal-fired power plants. Then the flame structure, heat transfer flux, and char burnout rate at different oxygen partitioning ratios between the primary and secondary streams were systematically analyzed to further determine the optimal oxygen partitioning ratio. The results showed that the maximum flue gas temperature Tmax increased by 220 K and the total heat transfer flux on the furnace wall increased by 42 % when the XO2,total was increased from 21 % to 32 %, respectively. Under oxy-coal combustion conditions, the Tmax at the XO2,total of 32.4 % was consistent with that under air combustion condition, while the total heat transfer flux at the XO2,total of 29.4 % matched with that under air combustion condition. Moreover, the total heat transfer flux and the flame length were increased by 17.3 % and 46.3 %, respectively, as the oxygen concentration of the primary stream XO2,Pri was increased from 6.5 % to 45 % at the XO2,total of 29 %. More importantly, the total heat transfer flux at the XO2,Pri of 31.9 % under oxy-coal combustion condition matched with that under air combustion condition. The optimal total oxygen concentration and oxygen partitioning ratio of oxy-coal combustion based on the heat transfer characteristics were quantitatively determined, which gave an important reference for the oxy-coal combustion retrofitting of traditional coal-fired power plants.

Combustion characteristics and nitrogen conversion mechanism in ammonia/coal Co-firing process

The coupled combustion of coal with the carbon-free fuel NH3 is an effective technology for reducing CO2 emissions. Based on elemental analysis, proximate analysis, Fourier Transform infrared spectroscopy (FTIR), Carbon-13 Nuclear Magnetic Resonance (13C NMR), and X-ray photoelectron spectroscopy (XPS) characterizations, a coal macromolecular model was constructed. The combustion characteristics of coal/NH3 co-firing were investigated by reactive force field molecular dynamics simulations (ReaxFF MD). The transformation mechanism of elemental N was elucidated. The influence of temperature, oxygen concentration, and NH3 co-firing ratio (CR) on products was investigated. The results showed that during the non-isothermal combustion phase, the coal macromolecules decomposed more rapidly when the heating rate was low. In the isothermal phase, high temperatures promoted secondary reactions. The production of inorganic gases increased with increasing temperature. As the molar fraction of NH3 increased, the production of CO2 and CO was effectively reduced. There were three main pathways for NO formation. As NH3 decomposed to form NH2, NH2 was subsequently converted to NH, and NH reacted with O2 to form NO. The NH2 could also react with O radicals to form HNO, which was then converted to NO. Besides, both thermal NOx and prompt NOx were generated since the N2 was involved in the reaction. In addition, the production of NOx increased significantly at oxygen concentrations greater than 1.4.

Performance and Emission Optimisation of an Ammonia/Hydrogen Fuelled Linear Joule Engine Generator

This paper presents a Linear Joule Engine Generator (LJEG) powered by ammonia and hydrogen co-combustion to tackle decarbonisation in the electrification of transport propulsion systems. A dynamic model of the LJEG, which integrates mechanics, thermodynamics, and electromagnetics sub-models, as well as detailed combustion chemistry analysis for emissions, is presented. The dynamic model is integrated and validated, and the LJEG performance is optimised for improved performance and reduced emissions. At optimal conditions, the engine could generate 1.96 kWe at a thermal efficiency of 34.3% and an electrical efficiency of 91%. It is found that the electromagnetic force of the linear alternator and heat addition from the external combustor and engine valve timing have the most significant influences on performance, whereas the piston stroke has a lesser impact. The impacts of hydrogen ratio, oxygen concentration, inlet pressure, and equivalence ratio of ammonia-air on nitric oxide (NO) formation and reduction are revealed using a detailed chemical kinetic analysis. Results indicated that rich combustion and elevated pressure are beneficial for NO reduction. The rate of production analysis indicates that the equivalence ratio significantly changes the relative contribution among the critical NO formation and reduction reaction pathways.

A Good Prognosis of Patients with Acute Pancreatitis Combined with Pulmonary Embolism: Early Identification and Intervention.

Pulmonary embolism (PE) is a relatively rare vascular complication of acute pancreatitis (AP), and its mortality rate is high. To our knowledge, relevant literature reports still need to be summarized. In this study, we analyzed the clinical characteristics, treatment, and prognosis of five patients with AP complicated by PE and summarized and reviewed the relevant literature. Clinical data of patients with AP complicated by PE treated in Taizhou Hospital of Zhejiang Province between January 2017 and September 2022 were retrospectively collected. Combined with the relevant literature, the clinical characteristics, treatment, and prognoses of patients with AP combined with PE were analyzed and summarized. Five patients were eventually enrolled in this study. Among the five patients with AP complicated by PE, all (100%) had symptoms of malaise, primarily chest tightness, shortness of breath, and dyspnea. All patients (100%) had varied degrees of elevated D-dimer levels and a significant decrease in the pressure of partial oxygen (PO2) and pressure of arterial oxygen to fractional inspired oxygen concentration ratio (PaO2/FiO2). Computed tomographic angiography (CTA) or pulmonary ventilation/perfusion imaging revealed a pulmonary artery filling defect in these patients. One patient (20%) had left calf muscular venous thrombosis before the occurrence of PE. Four patients (80%) were treated with lowmolecular- weight heparin (LMWH), and one patient (20%) was treated with rivaroxaban during hospitalization; all continued oral anticoagulant therapy after discharge. All patients (100%) were cured and discharged. No patients showed recurrence of AP or PE. PE is a rare but life-threatening complication of AP. However, once diagnosed, early treatment with anticoagulation or radiological interventional procedures is effective, and the prognosis is good. Core Tips: Pulmonary embolism (PE) is a rare but life-threatening complication of acute pancreatitis (AP). Its early diagnosis and timely anticoagulation or radiological intervention can reduce mortality. However, only nine cases have been reported in the English literature thus far, and they are all case reports. Our study is the first systematic analysis of patients with AP combined with PE with a review of the relevant literature. Our patients and those reported in the literature were discharged with good prognoses under treatment such as anticoagulation and vascular intervention. These cases remind clinicians that, in patients with AP, especially those with risk factors for venous thrombosis, it is necessary to monitor the D-dimer level dynamically. Clinicians should pay attention to AP patients' symptoms and related examinations to reduce the chance of a missed diagnosis or misdiagnosis of PE.

A Multiscale Modeling Approach to Identify and Quantify the Transport Limitations in Proton Exchange Membrane Fuel Cells

The reduction of platinum loading is essential for lowering the cost of Proton Exchange Membrane Fuel Cells (PEMFCs). However, low platinum loadings typically lead to performance losses due to reduced electrochemical active surface area as well as additional local transport losses within the catalyst layer. Experimentally, limiting current analysis provides a helpful tool to investigate the oxygen transport limitations. In this method the limiting current (obtained at cell voltages of about 0.2 V) is measured for different oxygen concentrations and total pressures. The oxygen transport resistance is then calculated from the ratio of oxygen concentration and limiting current. The pressure variation allows separating the pressure dependent and pressure independent parts of this resistance, which are related to transport in the channels, molecular diffusion in the Gas Diffusion Layer (GDL), Knudsen diffusion through the Micro Porous Layer (MPL) and cathode catalyst layer (CCL) plus local transport losses within the CCL, respectively. However, the method does not allow to easily break down the contributions of each cell component and processes to the total resistance, which requires the variation of the components[1].Therefore, within the project FURTHER-FC[2] we develop a multiscale modeling approach for interpreting the experimentally observed transport losses and to quantify the contributions of the different cell components based on their microstructure. On the sub-µm scale a Lattice Boltzmann model is developed to describe the transport within the CCL on the agglomerate scale, taking into account the transport through the ionomer film. This model is used to parametrize the effective local transport resistance[3] for calculation of the reaction kinetics in the cell model. For the GDL/MPL Direct Numerical Simulation (DNS) applied to the real microstructures[4] is used to obtain the effective diffusion coefficients, which are then applied in the cell model. The 2D PEMFC model considers the multicomponent transport, i.e., free flow in the gas channels and transport through the porous media according to Darcy’s law, charge transport, water transport in the ionomer, energy transport as well as the electrochemical reactions. Model validation is performed with limiting current analysis on MEAs with different platinum loading under various pressures and relative humidity. By analyzing the local concentrations within the cell, the model is then used to quantify the contributions of each cell component to the overall oxygen transport resistance. The project FURTHER-FC [2] has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under Grant Agreement No 875025. This Joint Undertaking receives support from the European Union’s Horizon 2020 Research and Innovation program, Hydrogen Europe and Hydrogen Europe Research. [1] Daniel R. Baker et al, J. Electrochem. Soc. (2009) 156 B991[2] https://further-fc.eu/[3] T. Jahnke and A. Baricci, J. Electrochem. Soc. 169 (2022) 094514[4] M. Ahmed-Maloum et al., Journal of Power Sources 561 (2023) 232735 Figure 1

Co-combustion strategy of waste energetic materials with pine sawdust for efficient NOx emissions reduction

Excessive NOx emissions during incineration of waste energetic materials (EMs) is harmful to the environment. Co-combustion technologies with biomass have demonstrated remarkable advantages in reducing NOx emissions. Herein, the co-combustion characteristics and NOx emission behaviors of waste double-base propellant (DP) and pine sawdust (PS) were investigated via thermogravimetric (TG) and fixed-bed experiments firstly. Meanwhile, the general full factorial design (GFFD) was performed to explore the effects of different factors on the NOx emissions of co-combustion. The interaction mechanism between DP and PS was discussed as well. Moreover, the interaction of three other typical waste EMs (RDX, TNT, and triple-base propellant) co-combustion with PS in NOx emissions was studied utilizing orthogonal experiments. The kinetics under air atmosphere indicated that the mixing of PS slightly diminished the combustion reactivity of DP, conversely, the remaining residue of DP combustion promoted the combustion of PS. Oxygen concentration, temperature and mixing ratio all had significant effects on NOx emissions of co-combustion between DP and PS, the degree of effect decreased in turn. Overall, the mixing of PS all suppressed the NOx emissions with significant synergistic effects, optimal synergistic effect at 20 wt% of PS mixing. The synergistic effect in oxygen environment was lower than that in oxygen-free environment. Meanwhile, increasing temperature contributed to enlarging the synergistic effect. Additionally, there was synergistic effect of TNT and PS co-combustion, whereas RDX, TP exerted inhibition effect of co-combustion with PS. Therefore, the co-combustion strategy of waste EMs with PS provides reliable data support and guidance for the control of NOx emissions during the incineration of waste EMs.

Experimental Studies on Preheating Combustion Characteristics of Low-Rank Coal with Different Particle Sizes and Kinetic Simulation of Nitrogen Oxide

Low-rank coal, accounting for 45% of the global coal reserves, is easier to use in terms of realizing ignition and stable combustion due to its relatively high levels of volatile content. But the problem of low-rank coal combustion is that its NO formation is in the range of 300–600 mg/m3, which makes the emission’s meeting of the environmental regulation quite difficult or uneconomic. Preheating combustion was a prospective combustion technology which involved preheating in a circulating fluidized bed (CFB) first and then combustion in a combustor for preheated fuel. With three particle sizes (0–0.355 mm, 0–0.5 mm, and 0–1 mm), some experiments were carried out in a 30 kW test rig. The results showed that, in the CFB preheating, a particle size of 0–1 mm had the highest coal-gas heating value due to a long residence time. The release of species in the CFB preheating always followed the order H > N > C > S. For preheated fuel combustion, a particle size of 0–0.355 mm showed the fastest combustion velocity, with the highest temperature point near the nozzle. For all three particle sizes, the combustion of preheated fuel showed a uniform temperature distribution with a small temperature difference. The lowest NO emission was 105 mg/m3 for the particle size of 0–0.5 mm. A GRI-Mech 2.11 mechanism was used to simulate the formation of NO with different influencing factors, such as temperature, oxygen concentration, and secondary-air ratio. There was a good agreement between the experimental data and the simulation’s results. The simulation showed that the NO formation could be further decreased with an optimal secondary-air ratio. This investigation provides support for the basic understanding of preheating-combustion technology and potential industrial applications in the future.

Analysis of the Partial Nitrification/Anammox Performance and Microbial Structure of Low C/N Wastewater by A2/O Process

Given the carbon limitation of low C/N wastewater, the improvement of nitrogen-removal efficiency remains a challenging task of municipal wastewater treatment plants (WWTPs) in China. In this study, a partial nitrification/anammox (PN/A) system was established to facilitate the anaerobic-anoxic-aerobic (A2/O) treatment of low C/N (C/N = 3) wastewater with insufficient carbon sources. Effects of dissolved oxygen (DO) concentration and internal reflux ratio on nitrogen-removal efficiency and pathway were investigated. Under the optimal DO (0.5–0.8 mg·L−1) and internal reflux ratio (250%), the highly efficient NH4+-N removal (97.21%) and TN removal (80.92%) were achieved based on PN/A. Moreover, the relative abundance of ammonia-oxidizing bacteria (Nitrosomonas) was 3 times higher than the abundance of nitrite-oxidizing bacteria (Nitrospira) in phase V, which was the main cause of PN in the reactor. Anaerobic ammonia-oxidizing bacteria (Candidatus Brocadia, Pirellula, and Gemmata) were also found and considered as the key microbes involved in anammox. This study reports that the A2/O process can achieve advanced nitrogen removal of low C/N wastewater based on PN/A by optimizing conventional process parameters. The outcomes of this study may provide practical engineering applications as a reference for nitrogen removal based on the A2/O process.

CONVERSION OF PROPANE TO FORMALDEHYDE ON IRON PHOSPHATE

Phosphates represent diverse complex systems, whose basic structural unit is tetrahedron. They are widely applied as catalysts, carriers of catalytic active substances, adsorbents and ion exchangers. Phosphoric acid and phosphates act as catalyst for reactions of alkylation, cracking, izomerization, polymerization, hydrogenation and dehydrogenation. Phosphates of some metals promote oxidation of normal alkanes with derivation of aldehydes, acids, spirits and maleic anhydride.
 The process of propane and propylene oxidation on iron phosphate is investigated, as well as the influence of such factors as temperature, contact time of the reacting mixture with the catalyst t, the ratio of oxygen and hydrocarbon concentration in a mixture, and the influence of hydrogen concentration on the given process is shown.
 It is demonstrated that the optimum conditions for the realization of propane oxidation process is the temperature of 973 K and t = 0.17 s. It is established that with excess propane in the reaction mixture propylene is the predecessor of formaldehyde. On the contrary, at small concentration of propane in the mixture formaldehyde will be derived immediately from propane. The schemes of propane and propylene oxidation in formaldehyde are offered.
 Keywords: catalyst; oxidatio; рhosphates; propane; propylene; formaldehyde.

Numerical Simulation of Carbon Oxygen Ratio Logging Response in Natural Gas Hydrate Reservoirs

In the process of oil and gas field development, in order to identify the gas hydrate reservoir more accurately, we try to use the carbon oxygen ratio spectrum logging technology to study the log response law of this reservoir, and compare it with the reservoir response law to better guide the oil field production. Firstly, the theoretical response law of carbon and oxygen concentration ratio of natural gas hydrate reservoir and oil layer is deduced according to the petrophysical model, and then the response law of carbon and oxygen concentration ratio of two types of reservoirs simulated by Monte Carlo numerical simulation is studied, and the similarity law and difference between the two types of reservoirs are summarized. The results show that the carbon oxygen ratio has a regular change relationship with the porosity and saturation of the reservoir. The carbon oxygen ratio can be used to preliminarily distinguish and qualitatively identify the two types of reservoirs.

Association of Conventional Ultrafiltration on Postoperative Pulmonary Complications

BackgroundPostoperative pulmonary complications increase mortality after cardiac surgery. Conventional ultrafiltration may reduce pulmonary complications by removing mediators of bypass-induced inflammation and countering hemodilution. We tested the primary hypothesis that conventional ultrafiltration reduces postoperative pulmonary complications, and secondarily, improves early pulmonary function assessed by the ratio of PaO2 to fractional inspired oxygen concentration. MethodsThis retrospective analysis compared the incidence of postoperative pulmonary complications in adult patients who underwent cardiac surgery, with and without the use of conventional ultrafiltration, by using logistic regression with adjustment for confounding variables. The primary outcome was a composite of reintubation, prolonged ventilation, pneumonia, or pleural effusion. Secondarily, we examined early postoperative lung function using a quantile regression model. We also explored whether red blood cell transfusion differed between groups. ResultsOf 8026 patients, 1043 (13%) received conventional ultrafiltration. After adjustment for confounding variables, the incidence of the composite primary outcome was higher in the conventional ultrafiltration group (12.1% vs 9.9%; P = .03), with an estimated odds ratio of 1.25 (95% CI, 1.02-1.53; P = .03). The median (quantiles) PaO2–to–fractional inspired oxygen concentration ratio was 373 (303-433) vs 368 (303-428), with the estimated adjusted difference in medians of 5 (95% CI, −5.9 to 16; P = .37). The estimated odds ratio of intraoperative transfusion was 1.38 (95% CI, 1.19-1.60; P < .0001) and for postoperative transfusion was 1.30 (95% CI, 1.14-1.49; P = .0001). ConclusionsUse of conventional ultrafiltration was not associated with a reduction in the composite of postoperative pulmonary complications or improved early pulmonary function. We found no evidence of benefit from use of conventional ultrafiltration during cardiac surgery.

Minimizing Lung Injury During Laparoscopy in Head-Down Tilt: A Physiological Cohort Study.

Increased intra-abdominal pressure during laparoscopy induces atelectasis. Positive end-expiratory pressure (PEEP) can alleviate atelectasis but may cause hyperinflation. Cyclic opening of collapsed alveoli and hyperinflation can lead to ventilator-induced lung injury and postoperative pulmonary complications. We aimed to study the effect of PEEP on atelectasis, lung stress, and hyperinflation during laparoscopy in the head-down (Trendelenburg) position. An open-label, repeated-measures, interventional, physiological cohort trial was designed. All participants were recruited from a single tertiary Belgian university hospital. Twenty-three nonobese patients scheduled for laparoscopy in the Trendelenburg position were recruited.We applied a decremental PEEP protocol: 15 (high), 10 and 5 (low) cm H 2 O. Atelectasis was studied with the lung ultrasound score, the end-expiratory transpulmonary pressure, the arterial oxygen partial pressure to fraction of inspired oxygen concentration (P ao2 /Fi o2 ) ratio, and the dynamic respiratory system compliance. Global hyperinflation was evaluated by dead space volume, and regional ventilation was evaluated by lung ultrasound. Lung stress was estimated using the transpulmonary driving pressure and dynamic compliance. Data are reported as medians (25th-75th percentile). At 15, 10, and 5 cm H 2 O PEEP, the respective measurements were: lung ultrasound scores (%) 11 (0-22), 27 (11-39), and 53 (42-61) ( P < .001); end-expiratory transpulmonary pressures (cm H 2 O) 0.9 (-0.6 to 1.7), -0.3 (-2.0 to 0.7), and -1.9 (-4.6 to -0.9) ( P < .001); P ao2 /Fi o2 ratios (mm Hg) 471 (435-538), 458 (410-537), and 431 (358-492) ( P < .001); dynamic respiratory system compliances (mL/cm H 2 O) 32 (26-36), 30 (25-34), and 27 (22-30) ( P < .001); driving pressures (cm H 2 O) 8.2 (7.5-9.5), 9.3 (8.5-11.1), and 11.0 (10.3-12.2) ( P < .001); and alveolar dead space ventilation fractions (%) 10 (9-12), 10 (9-12), and 9 (8-12) ( P = .23). The lung ultrasound score was similar between apical and basal lung regions at each PEEP level ( P = .76, .37, and .76, respectively). Higher PEEP levels during laparoscopy in the head-down position facilitate lung-protective ventilation. Atelectasis and lung stress are reduced in the absence of global alveolar hyperinflation.

Interactions between polypropylene microplastics (PP-MPs) and humic acid influenced by aging of MPs

As an emerging pollutant, microplastics (MPs) may interact with dissolved organic matter (DOM) which is prevalent in the aqueous environment. Meanwhile, the aging of MPs in the actual environment increases the uncertainty of their environmental fate. Here, the interaction mechanisms between pristine and aged polypropylene microplastics (PP-MPs) and humic acid (HA) at pH 7.0 were explored. Microstructural changes of HA were examined by fluorescence and Fourier transformation infrared (FT-IR) spectroscopy. Atomic force microscopy coupled with infrared (AFM-IR) and micro-Raman techniques were used to characterize and analyze the interacted PP-MPs. The addition of HA increased the surface roughness of both pristine and aged PP-MPs. Results of AFM-IR and Raman spectra showed that the interaction of PP-MPs with HA accelerated their surface oxidation and enhanced the characteristic signals. XPS spectra showed that the oxygen content ratio of pristine and aged PP-MPs increased by 0.95% and 1.48% after the addition of HA, respectively. PP-MPs after aging interacted more strongly with HA and there was a higher affinity between them. Two-dimensional correlation spectroscopy (2D-COS) combined with FT-IR spectra further elucidated the interaction mechanism at the molecular level. This work will help to evaluate the environmental impact of MPs in ecosystems and understand their interactions with DOM.

Influence of oxygen content on the manifestation of hazardous properties of coal seams

Purpose. To improve the regulatory framework for the safe conduct of mining operations, to establish the effect of mineral impurities and moisture on the accuracy of determining the oxygen content, under conditions close to those of coal seams. Methodology is based on the fact that practically for all coal seams of Donbass and the Lvov-Volyn basin indicators of consumer qualities of solid fuels have been established, but they characterize only one organic (combustible) part per dry ash-free state. In this case, the effect of mineral impurities (their content for many reservoirs exceeds 30-40%) and moisture on the change in oxygen content is not taken into account. The manifestation of many hazardous properties of coal seams depends on the ratio of oxygen content with other components of the organic mass and mineral impurities. To bring the quality indicators of coals to a state close to the conditions of mining operations, they were recalculated for each coal seams, taking into account the actual yield of ash and total moisture. Findings. The indicator of the release of volatile substances used in the normative documents for the safe conduct of mining operations for assessing the metamorphic transformations of coal seams does not determine the type of coal by their reduction. Restorability determines the properties of the organic mass based on the ratio of oxygen to its other main components. In addition to the organic mass in the dry ash-free state, the composition of solid fuels includes mineral impurities and moisture. They significantly affect the change in the ratio between the main components. The carbon content in the organic (combustible) mass is more informative in comparison with the yield of volatile substances, an indicator. It functionally controls the sum of the remaining components - hydrogen, nitrogen, sulfur and oxygen. To a lesser extent, but rather high, the closeness of the correlation interdependence was established between the content of oxygen and carbon in the dry ash-free state of the fuel. Such interdependence is completely eliminated when considering the fuel for its working condition, which indicates the random nature of the relationship between the main components of the organic mass and mineral impurities, including moisture, for each considered coal seams. Originality. For the first time, on the basis of statistical processing of experimental data on the quality of coals for almost all coal seams of the Donbass and the Lviv-Volyn basins, the possible limits of the oxygen content for the working state of the fuel were established, which makes it possible to individually consider for each coal seam the ratio between the main components of the organic mass and mineral impurities, including the presence of moisture. Practical implications. The research results make it possible to develop proposals for improving the regulatory framework in terms of predicting the hazardous properties of coal seams during mining operations.

Clinical study of awake prone positioning treatment in patients with common coronavirus disease 2019 caused by Omicron variant

To evaluate the clinical effect of awake prone positioning (APP) for common coronavirus disease 2019 (COVID-19) caused by Omicron variant. Retrospectively analyze the clinical data of patients with COVID-19 caused by Omicron variant admitted by medical team of Tianjin Third Central Hospital during the period of supporting Tianjin COVID-19 designated hospital from January 8 to February 20, 2022. Patients who met the diagnostic criteria for common COVID-19 and had risk factors for developing severe disease or had pulse oxygen saturation (SpO2) ≤ 0.93 after exercise without supplementary oxygen were enrolled. Patients were divided into APP group and control group according to whether they completed the daily 12-hours APP in the first three days after enrollment. Demographic characteristics, clinical symptoms, COVID-19 vaccination status, laboratory examination, disease progression (progression to severe), time to nucleic acid negative conversion, length of hospital stay, and adverse reactions and tolerability [visual analog scale (VAS) score (the higher the score, the worse the tolerability] during APP were evaluated in two groups. Interleukin-6 (IL-6), C-reactive protein (CRP), SpO2/inhaled oxygen concentration (FiO2) ratio and ROX index (ROXI) were compared between two groups at enrollment, 3rd and 7th day after enrollment. There were no significant differences in demographic characteristics, clinical symptoms, vaccination rates of COVID-19 and laboratory tests between the two groups. There were no statistically significant differences in IL-6, CRP, SpO2/FiO2 ratio and ROXI between two groups at the time of enrollment. Compared with the group at the time of enrollment, SpO2/FiO2 ratio and ROXI in APP group increased significantly at the 3rd day after enrollment [SpO2/FiO2 ratio: 461.90 (457.10, 466.70) vs. 446.67 (437.14, 457.10), ROXI: 25.40 (23.33, 25.93) vs. 22.57 (21.86, 24.40), all P < 0.05], and the levels of IL-6 and CRP in control group were significantly increased [IL-6 (ng/L): 18.30 (6.50, 37.75) vs. 7.40 (5.10, 11.15), CRP (mg/L): 11.46 (2.11, 17.96) vs. 4.11 (1.72, 9.05), all P < 0.05]. At the 3rd day of enrollment, the levels of IL-6 and CRP in APP group were significantly lower than those in control group [IL-6 (ng/L): 7.35 (4.35, 12.80) vs. 18.30 (6.50, 37.75), CRP (mg/L): 4.52 (1.98, 9.66) vs. 11.46 (2.11, 17.96), all P < 0.05], while SpO2/FiO2 ratio and ROXI were significantly higher than those in control group [SpO2/FiO2 ratio: 461.90 (457.10, 466.70) vs. 446.67 (441.90, 459.52), ROXI: 25.40 (23.33, 25.93) vs. 23.31 (22.10, 24.66), all P < 0.05]. At the 7th day of enrollment,there were no significant differences in IL-6, CRP, SpO2/FiO2 ratio and ROXI between two groups. There were no severe cases in both groups. The time of nucleic acid negative conversion and length of hospital stay in APP group were significantly shorter than those in control group [10.0 (8.0, 12.0) days vs. 11.0 (9.0, 13.0) days, 12.0 (10.0, 14.0) days vs. 14.0 (12.0,16.0) days, respectively, all P < 0.05]. The main adverse reaction during APP was back pain, and the incidence in APP group was slightly lower than that in control group, but the difference was not statistically significant [17.9% (17/95) vs. 26.5% (27/102), P = 0.149]. VAS score in control group was significantly higher than that in APP group [score: 2.5 (2.0, 4.0) vs. 2.0 (1.0, 3.0), P = 0.004]. In common COVID-19 patients caused by Omicron variant with high risk factors for progression to severe disease or decreased oxygen reserve capacity, early APP can shorten the time of nucleic acid negative conversion and the length of hospital stay, but its effect on preventing disease progression cannot be determined.