O2 Ratio Research Articles

Temperature dependent polaronic contribution on conduction mechanism in ceria-based devices

The role of temperature dependent polaron density in current conduction mechanism of CeO2-based devices is investigated where CeO2−x films were deposited at different Ar:O2 ratios at room temperature using rf sputtering. I–V measurements on metal–oxide–semiconductor (MOS) devices at different temperatures show a three order current change in unipolar and bipolar switching having triggering voltages ranging from ±0.7 V at 80–100 °C to ∼±1.0 V at 150 and 200 °C and are reproducible in repeat cycles. Temperature dependent x-ray photoelectron spectroscopy (XPS) and grazing incidence x-ray diffraction (GIXRD) studies indicate along with stoichiometry dependent polaron contribution, the change in lattice parameters of polycrystalline CeO2 film also contributes to the resistive switching properties of CeO2-based devices with temperature. Oxygen vacancy movements in the form of hopping of polarons between the nearest neighbours and next to nearest neighbour sites as well facilitate the transitions at elevated temperatures. As predicted in the theoretical model, it is experimentally verified here that the conduction path created at elevated temperature vanishes at relatively higher temperatures due to too frequent polaron hopping. It is further observed that the density of polarons also increases with temperature that in turn hinders the switching behaviour of the devices at elevated temperatures.

Numerical simulation of nano-aluminum ignition in oxygen and steam environments

The ignition characteristics of nano-aluminum (nano-Al) in oxygen and steam environments were numerically studied in this work. A detailed kinetic mechanism of nano-Al combustion was developed, and the effects of initial reaction temperature, ignition pressure, the phase of reactant, and the ratio of O2 and H2O in the oxidizer on the oxidation performance of aluminum (Al) were analyzed in detail. Numerical results show that increasing the initial temperature promotes the ignition of liquid-phase Al, while the promotion is not significant for gas-phase Al ignition. The oxidation of liquid-phase Al is significantly slower than that of gas-phase Al, and the phase transition reaction of liquid-phase Al exhibits a typical endothermic process, which results in a temperature drop before ignition. The increase of initial reaction pressure can accelerate the consumption of both liquid-phase Al and gas-phase Al in the ignition process. The oxidizability of O2 is much larger than that of H2O, and the oxidation of Al becomes slower by adding H2O in the oxidizer. The rate of production (ROP) was performed to deeply realize the reaction pathways of Al consumption and main products formation. The reaction Al + O2 = AlO + O is the key reaction pathway in the Al-O2 ignition process, while the reaction Al + H2O = AlOH + O plays a more important role in the Al-H2O ignition process. In the all ignition cases, Al2O2 is a key intermediate species since it is the main precursor of gaseous Al2O3, and liquid-phase Al2O3 formed by the phase transition reaction of gaseous Al2O3 is the dominant final product.

Influence of oxygen on solid carbon formation during arcing of eco-friendly SF6-alternative gases

During the arc breaking process of high-voltage circuit breakers, the eco-friendly SF6-alternative gases will inevitably decompose and generate various decomposition products. In some cases, this will contain solid by-products such as solid carbon, which will have a deterioration effect on the electrical insulation performance of the equipment. It has been found that adding a proper amount of O2 can effectively inhibit the formation of solid carbon. In this paper, based on the improved Gibbs free energy minimization method, a calculation model considering the solid decomposition products was established, and the arc plasma composition of CO2/O2 mixtures with the new eco-friendly gases, such as C4F7N, C5F10O, HFO-1234ze(E) and HFO-1336mzz(E), in local thermodynamic equilibrium state was calculated. The change of decomposition products with the initial O2 ratio is studied, and the criterion expression of inhibiting solid carbon formation is obtained. We also applied the method to the calculation of other SF6-alternative gases containing sulfur atoms such as NSF3 and CF3SO2F. Finally, we showed that solid carbon can be inhibited when a proper molecule formula is satisfied. This work may provide new ideas for further exploring the potential of SF6-alternative gases.

Microbial protein production from sulfide-rich biogas through an enrichment of methane- and sulfur-oxidizing bacteria

This study evaluated the possibility of combining methane oxidizing bacteria (MOB) with sulfur oxidizing bacteria (SOB) to enable the utilization of sulfide-rich biogas for microbial protein production. For this purpose, a MOB-SOB mixed-culture enriched by feeding both methane and sulfide was benchmarked against an enrichment of solely MOB. Different CH4:O2 ratios, starting pH values, sulfide levels and nitrogen sources were tested and evaluated for the two enrichments. The MOB-SOB culture gave promising results in terms of both biomass yield (up to 0.07 ± 0.01 g VSS/g CH4-COD) and protein content (up to 73 ± 5% of VSS) at 1500 ppm of equivalent H2S. The latter enrichment was able to grow also under acidic pH (5.8–7.0), but as inhibited outside the optimal CH4:O2 ratio of 2:3. The obtained results show the capability of MOB-SOB mixed-cultures to directly upcycle sulfide-rich biogas into microbial protein potentially suited for feed, food or biobased product applications.

Efficacy and Safety of Anakinra Plus Standard of Care for Patients With Severe COVID-19

COVID-19 pneumonia is often associated with hyperinflammation. The efficacy and safety of anakinra in treating patients with severe COVID-19 pneumonia and hyperinflammation are still unclear. To assess the efficacy and safety of anakinra vs standard of care alone for patients with severe COVID-19 pneumonia and hyperinflammation. The Clinical Trial of the Use of Anakinra in Cytokine Storm Syndrome Secondary to COVID-19 (ANA-COVID-GEAS) was a multicenter, randomized, open-label, 2-group, phase 2/3 clinical trial conducted at 12 hospitals in Spain between May 8, 2020, and March 1, 2021, with a follow-up of 1 month. Participants were adult patients with severe COVID-19 pneumonia and hyperinflammation. Hyperinflammation was defined as interleukin-6 greater than 40 pg/mL, ferritin greater than 500 ng/mL, C-reactive protein greater than 3 mg/dL (rationale, ≥5 upper normal limit), and/or lactate dehydrogenase greater than 300 U/L. Severe pneumonia was considered if at least 1 of the following conditions was met: ambient air oxygen saturation 94% or less measured with a pulse oximeter, ratio of partial pressure O2 to fraction of inspired O2 of 300 or less, and/or a ratio of O2 saturation measured with pulse oximeter to fraction of inspired O2 of 350 or less. Data analysis was performed from April to October 2021. Usual standard of care plus anakinra (anakinra group) or usual standard of care alone (SoC group). Anakinra was given at a dose of 100 mg 4 times a day intravenously. The primary outcome was the proportion of patients not requiring mechanical ventilation up to 15 days after treatment initiation, assessed on an intention-to-treat basis. A total of 179 patients (123 men [69.9%]; mean [SD] age, 60.5 [11.5] years) were randomly assigned to the anakinra group (92 patients) or to the SoC group (87 patients). The proportion of patients not requiring mechanical ventilation up to day 15 was not significantly different between groups (64 of 83 patients [77.1%] in the anakinra group vs 67 of 78 patients [85.9%] in the SoC group; risk ratio [RR], 0.90; 95% CI, 0.77-1.04; P = .16). Anakinra did not result in any difference in time to mechanical ventilation (hazard ratio, 1.72; 95% CI, 0.82-3.62; P = .14). There was no significant difference between groups in the proportion of patients not requiring invasive mechanical ventilation up to day 15 (RR, 0.99; 95% CI, 0.88-1.11; P > .99). In this randomized clinical trial, anakinra did not prevent the need for mechanical ventilation or reduce mortality risk compared with standard of care alone among hospitalized patients with severe COVID-19 pneumonia. ClinicalTrials.gov Identifier: NCT04443881.

Effect of the Nanorough Surface of TiO2 Thin Films on the Compatibility with Endothelial Cells.

The cytocompatibility of titanium oxides (TiO2) and oxynitrides (N-TiO2, TiOxNy) thin films depends heavily on the surface topography. Considering that the initial relief of the substrate and the coating are summed up in the final topography of the surface, it can be expected that the same sputtering modes result in different surface topography if the substrate differs. Here, we investigated the problem by examining 16 groups of samples differing in surface topography; 8 of them were hand-abraded and 8 were machine-polished. Magnetron sputtering was performed in a reaction gas medium with various N2:O2 ratios and bias voltages. Abraded and polished uncoated samples served as controls. The surfaces were studied using atomic force microscopy (AFM). The cytocompatibility of coatings was evaluated in terms of cytotoxicity, adhesion, viability, and NO production. It has been shown that the cytocompatibility of thin films largely depends on the surface nanostructure. Both excessively low and excessively high density of peaks, high and low kurtosis of height distribution (Sku), and low rates of mean summit curvature (Ssc) have a negative effect. Optimal cytocompatibility was demonstrated by abraded surface with a TiOxNy thin film sputtered at N2:O2 = 1:1 and Ub = 0 V. The nanopeaks of this surface had a maximum height, a density of about 0.5 per 1 µm2, Sku from 4 to 5, and an Ssc greater than 0.6. We believe that the excessive sharpness of surface nanostructures formed during magnetron sputtering of TiO2 and N-TiO2 films, especially at a high density of these structures, prevents both adhesion of endothelial cells, and their further proliferation and functioning. This effect is apparently due to damage to the cell membrane. At low height, kurtosis, and peak density, the main factor affecting the cell/surface interface is inefficient cell adhesion.

Investigating the properties of nickel oxide thin films prepared via DC reactive magnetron sputtering for potential application in gas sensing

Nanocrystalline nickel oxide (NiO) thin films were developed on Si substrate using DC reactive magnetron sputtering. The goal of our study was to investigate the impact of O2/Ar gas ratios (varied from 10% to 20%) on the properties of sputtered NiO thin films. Further, after the deposition, all the samples were annealed at 400 ℃ in air. The prepared thin films were characterized by GIXRD, UV–visible spectroscopy, and FESEM to investigate the structural, optical, and morphological properties, respectively. The GIXRD results demonstrated the formation of the polycrystalline nature of sputtered NiO films with the FCC phase. As the O2 ratio was increased, the preferred orientation of NiO thin film was found to change from (111) to (200) plane with an average crystallite size of ∼ 14 nm. The UV–visible spectroscopy measurements show the semi-transparent nature of the deposited NiO films with a decreasing trend in the transmittance value from ∼ 83% to ∼ 77% with an increase in the O2 to Ar gas ratio. This behavior could be due to the poor crystallization of the film. However, the change in the calculated band gap of NiO films with respect to O2 partial pressure was found to be negligible and lay between 3.82 eV and 3.84 eV. The surface morphology was studied using FESEM, which depicted the uniform and homogenous distribution of grains with cracks on the film that improve the gas permeability; hence it may prove beneficial for gas sensing applications. Besides, the observed contact angle, as measured by the wettability test for the NiO films at different oxygen partial pressure, was greater than 90°, which shows that all the deposited NiO thin films are hydrophobic. Additionally, we have tested the CO gas sensor responses of the NiO sample deposited at a 15% O2/Ar ratio due to the high hydrophobic nature among all three ratios.

A nano-sized precipitate strengthened medium entropy alloy with superior strength-ductility synergy and exceptional corrosion resistance

Herein, a novel alloy system, namely CoNiVSix MEAs, was proposed. The addition of Si remarkably promoted strength-ductility synergy, and favourably ameliorated the corrosion resistance of CoNiV MEAs. As for CoNiVSi0.1 MEA, the grain refinement effect prevails in strengthening the MEAs. The improved work-hardening capability caused by the reduction of SFE and the formation of DSBs contributed to a highly sustained strain hardening of CoNiVSi0.1 MEA, which expounded a simultaneous increase in the strength and ductility. Besides, electrochemical results and XPS analyses indicated that CoNiVSi0.1 MEA had better corrosion resistance, and bivalent Si oxides perhaps dominated the film barrier effect from aggressive medium for CoNiVSi0.1 MEA in view of the large atomic ratio of O2−/OH− and Si/V. This work provides a new and significant approach towards designing corrosion-resistant materials with superior strength-ductility synergy.

Piezo-ferroelectric response of bismuth ferrite based thin films and their related photo/piezocatalytic performance

Bismuth ferrite based thin films were grown by RF magnetron sputtering under different experimental conditions. The effects of substrate temperature, Ar:O2 mass flow ratio and gas mixture pressure on the films’ microstructure, phase evolution, optic, ferroelectric and magnetic properties were systematically investigated. The structural analysis results revealed an amorphous phase for the films deposited at a substrate temperature below 500 °C, while for the thin films deposited at 700 °C, a ε-Fe2O3 secondary phase was detected. The diffraction lines of the samples deposited at 600 °C were associated with Bi2Fe4O9 and Bi25FeO40 phases. The increase in the mixture gas pressure up to 1 Pa showed an improved crystallinity of the deposited films, while, at higher working gas pressures, the films were found to be amorphous. The use of low O2 to Ar mass flow ratio during the deposition led to a phase transformation process. EDX and RBS measurements exposed a uniform distribution of the main elements, revealing some stoichiometry changes induced by the pressure variation. The optical band gap values were influenced by the substrate temperature and pressure of the Ar:O2 gas. The magnetic properties were correlated with the structural features, the highest magnetic response being observed for the sample deposited at 600 °C, 1 Pa and 3:1 Ar:O2 gas pressure. According to the PFM results, the film deposited at 700 °C, Ar:O2 ratio 3:1 and total gas pressure 1 Pa clearly outperformed the others due to their excellent ferroelectric properties and outstanding piezo-response. The sample deposited at 700 °C showed both visible light-driven degradation and piezodegradation activities. The piezocatalytic and photocatalytic activities were ascribed to the high piezoresponse and to a more efficient separation of electrons and holes induced by a built-in electric field that is caused by the larger remnant polarization of Bi2Fe4O9 and Bi2Fe4O9/ε-Fe2O3 hetero-junction.

Effect of Ar:O2 ratio on magnetic properties of ZnO:Y thin films

4 at.% Y-doped ZnO (4YZO) thin film was fabricated by RF magnetron sputtering, on Si(111) substrate upon varying Ar:O2 ratios (75:25, 50:50, and 40:60). The effect of Ar:O2 ratio on morphological, structural, magnetic, and optical properties of these films have been investigated in detail. The films orientated along the (002) diffraction plane were confirmed by X-ray diffraction pattern. The defect centres in the prepared films were analysed using visible band emission from Photoluminescence spectra which showed the presence of oxygen vacancy (VO+) and zinc interstitial (Zni+). The number of donor defects (VO+ and Zni+) in the films were reduced with an increase in O2 content. The vibrating sample magnetometer results indicated that 4 at.% Y-doped ZnO thin film deposited at an Ar:O2 ratio of 75:25 exhibited ferromagnetic property with a saturation magnetization value of 2.01 emu/cm3. The observed magnetic coercivity value of 500 Oe, makes it suitable for non-volatile magnetic memory storage applications. The films prepared using an Ar:O2 ratio of 50:50 and 40:60 showed a blend of paramagnetic and weak ferromagnetic behaviour. The donor defects present in the films were responsible for the ferromagnetism in 4YZO thin films. The magnetic properties of 4YZO thin films have been explained using the bound magnetic polaron (BMP) model.

ASSOCIATION OF SERUM C-REACTIVE PROTEIN AND D-DIMER CONCENTRATION WITH CLINICAL SEVERITY CAUSED BY CORONAVIRUS IN HOSPITALIZED PATIENTS WITH DIABETES

BACKGROUND: The aim of this research was to compare the levels of inammatory markers (D-dimers and Creactive protein) in diabetic and non-diabetic patients depending on severity of clinical manifestation, therefore based on such, dene them as potential predictors of lethal outcome and clinical severity. A total of 422 subjects were included in this METHODS: research by retrospective review of the documentation at the Clinic for Infectious Diseases of University Clinical Hospital Mostar. While reviewing the medical records, the following data were lled in: demographic (age, sex, diabetes mellitus), oxygen saturation and paO2/O2 ratio, inammatory markers (C-reactive protein and D-dimers), used therapy (non-invasive ventilation, oxygen therapy, invasive mechanical ventilation) and nal outcome of disease. Based on the presence of diabetes mellitus the patients were divided into two groups: diabetic and nondiabetic patients. Data entry into tables was followed by statistical data processing using IBM SPSS Statistics v.26 and Microsoft Excel 2016. RESULTS: Out of total number of subjects, 161 had diabetes and 261 did not. Surprisingly, women statistically had a higher average value of Ddimers in comparison to men and they had a higher percetage of lethal outcome compared to men. Deceased patients had a higher average value of CRP (126,25) and D-dimers (2,20) in comparison to survivors. Also, the deceased had a lower average of oxygen saturation (83,07), lowered paO2/O2 ratio (131,5) and more liters of oxygen used in oxygen therapy (11,59). Statistically signicant higher lethality was noted in patients with diabetes compared to non-diabetic patients. Levels of C-reactive protei CONCLUSION: n and D-dimers were higher in patients with a more severe clinical manifestation. Since lethal outcome was more statistically prevalent in those subjects, CRP and D-dimers are stated as prognostic factors of clinical severity and lethal outcome in patients with COVID-19. Lastly, there was no notably increased difference in CRP and D-dimer levels between diabetic and non-diabetic patients.

Ignition and combustion of Al and ammonium perchlorate-coated Al particles in a double oxidizing air–H2O–Ar atmosphere

Aluminum is a promising energy-containing material that can satisfy both aerospace and underwater thermodynamic propulsion systems. A high-temperature pressurized combustion chamber and a CO2 laser were adopted to investigate the ignition and combustion characteristics of 2, 5, and 40 μm aluminum particles in a 1.0 MPa air–H2O–Ar mixed atmosphere (with varying O2 and H2O concentrations). The combustion-promoting effect of the ammonium perchlorate-coated modification (namely, the AP@Al sample) was evaluated. The results show that Al melts and agglomerates into millimeter-sized droplets (covered with a gas-phase flame) after ignition, and its nonhomogeneous combustion is dominated by diffusion. The flame propagation is greatly enhanced by the AP combustion-promoting effect of oxygen/heat supply and particle dispersion, resulting in a significant decrease in the ignition delay time (ti, approximately 55–85%) and combustion time (tc, approximately 32–96%), whereas an extraordinary increase in the maximum combustion temperature (Tmax, approximately 170–224 K) and pressure changes (approximately 1.7–8.5 kPa, approximately 10.6–136.5 kPa/s) are also observed. Excess water vapor inhibits the flame propagation for AP@Al, viz. the flame area and number of ejected burning particles is decreased. The main factor affecting the combustion temperature is the oxidant rather than the particle size, which may be related to the small difference in the active aluminum content of the samples and the diffusion-controlled combustion mechanism. Due to the advantage of O2 for oxidation and the diffusion rate, the gradual replacement of H2O by air (similar to conversion to a fuel-lean system) leads to a decrease in ti, whereas Tmax is increased for all the samples, and the tc and self-sustaining combustion time are increased for the Al samples, whereas tc is decreased for AP@Al samples for both the equal-molar oxidizing gas concentration and equivalence ratio of O2–H2O control groups in this work. Since O2 creates a new pathway for AlO production, the ignition and combustion performance of Al and AP@Al samples is significantly improved when H2O is replaced by a small amount of air.

Experimental and numerical study on laminar premixed NH3/H2/O2/air flames

Adding the product of water electrolysis (i.e. 2:1 volume of H2 and O2) is an effective strategy to enhance the combustion intensity of NH3/air mixtures. In this work, the laminar burning velocity (LBV) of the obtained NH3/H2/O2/air mixtures was measured at 303 K, 0.1 MPa and compared with the values predicted by seven mechanisms. To improve the prediction performance, a new mechanism is developed based on the existing mechanism and adopted for numerical simulation. The results of this study show that the LBV of NH3 is significantly increased by additional H2 and O2. By comparison, it is found that H2 shows a more significant promoting effect on LBV when the volume ratio of additional H2 and O2 is 2. The concentration of key radicals and the flame temperature increase remarkably due to the addition of H2 and O2, which promote the flame propagation. Furthermore, the experimental results also indicated that the additional H2 and O2 make the burned gas Markstein length decrease on the lean side and increase on the rich side.

Effect of oxygen enrichment of Biogas-Hydrogen mixtures in a premixed combustor on the combustion instability and emissions

The effect of enrichment of a low calorific (50 % CH4-50 % CO2) biogas mixture with hydrogen and oxygen has been investigated on combustion stability and exhaust emissions in a premixed burner. The thermal power was kept constant at 5 kW, the equivalence ratio of 0.8, and a swirl generator (1) was placed at the burner outlet. Initially, hydrogen (H2) was added to the biogas at intervals of 10 % up to 40 % by volume. The addition of hydrogen to the biogas increased the heating value of the mixture and reduced the instabilities. It has been determined that biogas/hydrogen mixtures containing 20 % and 30 % H2 showed the lowest combustion instability and pollutant emissions. It has been observed that with the addition of 30 % hydrogen to the biogas, the CO emission value, which was 5532 ppm, decreased to 130 ppm. Also, 23 % and 25 % O2 enrichment were applied to fuel mixtures. It was observed that combustion instabilities increased with oxygen enrichment in both fuel mixtures and flashbacks occurred under acoustic perturbation. It has been determined that the mixture containing 20 % H2 as the flame, which has the lowest emission and is resistant to acoustic perturbation, is burned at the 23 % O2 ratio by volume.

A computationally efficient and high-fidelity 1D steady-state performance model for PEM fuel cells

The performance of a proton exchange membrane (PEM) fuel cell is determined by many factors, including operating conditions, component specifications, and system design, making it challenging to predict its performance over a wide range of operating conditions. Existing fuel cell models can be complex and computationally demanding or may be over-simplified by neglecting many transport phenomena. Therefore, a high-fidelity and computationally efficient model is urgently needed for the model-based control of fuel cells. In this study, semi-implicit multi-physics numerical models have been established, taking the mass, momentum, reactants, liquid water, membrane water, electrons, ions, and energy in all fuel cell components into account. The developed 1D model is of high fidelity by incorporating the two-phase flow, non-isothermal effect, and convection, and is still computationally efficient. These models are validated against data from an auto manufacturer with good agreements, and the computing efficiency is evaluated on a modest laptop computer. The modeling results suggest that the two-phase flow model exhibits better prediction accuracy than the single-phase flow model when reactants are fully humidified, while under low humidity conditions, the two models present equivalent performance as liquid water does not exist in the fuel cell components. The results also suggest that the maximum convective/diffusive ratio of H2, O2, and vapor mass fluxes can be 12%, 5.3%, and 35%, respectively, which are ignored in most diffusion-dominant models. The developed models are computationally efficient, requiring only 0.56 s and 0.26 s to simulate a steady-state operation of fuel cells for the two- and single-phase flow models, respectively. This implies that the developed models are suitable for the control of PEM fuel cells.

Study of methane oxycondensation reaction (mn2o3)x∙ (na2moo4)y ∙ (zro2)z and textural characteristics of the catalyst

In the study, the effect of temperature, methane: air ratio, specific volume velocity, and various other factors on the yield of target products, methane conversion, and process selectivity of the methane catalytic oxycondensation reaction were studied. The effect of volumetric velocity was studied at a temperature of 800°C and a volumetric ratio of CH4:air = 1:2. The effect of temperature on the oxycondensation reaction of methane was studied in the presence of a catalyst of optimal composition at intervals of 50°C in the range of 600–850°C, at a constant volumetric velocity (1000 h-1) and a ratio of CH4:air = 1:2. CN4: The effect of air ratio was studied at a temperature of 800°C and a volumetric velocity = 1000 h-1. As a result of kinetic studies, an improvement in process performance was observed with increasing contact time and temperature rise. An increase in the CH4:O2 ratio leads to a decrease in methane and oxygen conversion. The addition of ethane, ethylene, СО, and СО2 to the reactor has been shown to reduce the formation of products. The work aims to study the kinetic laws of the reaction of oxidation of methane in a catalyst containing (Mn2O3)x·(Na2MoO4)y ·(ZrO2)z and to evaluate the texture characteristics of the catalyst.

Plasma-assisted deflagration to detonation transition in a microchannel with fast-frame imaging and hybrid fs/ps coherent anti-Stokes Raman scattering measurements

This study examines kinetic enhancement by nanosecond dielectric barrier discharge (ns-DBD) plasma on fuel-lean, Φ = 0.7, dimethyl ether (DME), oxygen (O2), and argon (Ar) premixture during deflagration to detonation transition (DDT) experiments in a microchannel. Nonequilibrium plasma produces active species and radicals as well as fast and slow heating of a mixture to promote ignition due to energetic electrons, ions, and electronic and vibrational excitations. Experiments are conducted to examine the influence of the plasma discharge on the premixture and on the resultant deflagration to detonation transition (DDT) onset time and distance through the use of high-speed imaging and one-dimensional, two-beam, femtosecond/picosecond, coherent anti-Stokes Raman scattering (CARS). A high-speed camera is used to trace the time histories of flame front position and velocity and to identify the dynamics and onset of DDT. The results show that plasma discharge can nonlinearly affect the onset time and distance of DDT. It is shown that a small number of plasma discharge pulses prior to ignition result in reduced DDT onset time and distance by 60% and 40%, respectively, when compared to the results without pre-excitation by ns discharges. The results also show that an increase of number of the plasma discharge pulses results in an extended DDT onset time and distance of 224% and 94%, respectively. Time history of the deflagration wave speed of DME and the analysis of ignition timescale under the choking condition of the burned gas of the deflagration wave suggest low temperature ignition may play a role for DME near the isobaric choking condition of the burned gas and the DDT. Plasma-induced low temperature oxidation of the reactive mixture is assessed via the CO2 to O2 ratio as measured through fs/ps CARS during the gas excitation in discharges. CARS measurements also confirm negligible vibrational and rotational heating of the gas by discharge. The present experiments demonstrate the ability of nonequilibrium plasma to alter the chemistry of DME/O2/Ar premixtures in order to control DDT for applications in advanced propulsion engines.

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.

Synthesis of amorphous Li3BO3 nanoparticles as solid electrolyte for all-solid-state battery by induction thermal plasma

Synthesis of amorphous Li3BO3 by induction thermal plasma was conducted systematically with the investigation of formation mechanism. The TEM, XRD, Raman and XPS were conducted to understand the morphology and chemical composition of products. The formation mechanism was investigated based on experiment results and thermodynamic analysis. Crystalline Li3BO3 was injected into plasma as raw material. Different mole ratios of Ar and O2 were selected as plasma sheath gas to understand O2 effect on the composition and amorphous degree of products. Ar was selected as quenching gas injected into the plasma to understand quenching rate effect on amorphous Li3BO3 generation. Amorphous Li3BO3 was synthesized successfully with agglomerated state. The products contained Li6B4O9 and Li4B2O5 besides Li3BO3. Higher amorphous Li3BO3 degree was obtained at higher O2 and quenching gas flow rates. The experiment results indicate that the high quenching rate promotes amorphous Li3BO3 generation but increases the possibility of by-product generation.

Integral Algorithms to Evaluate TiO2 and N-TiO2 Thin Films’ Cytocompatibility

Titanium oxide (TiO2) and oxynitride (N-TiO2) coatings can increase nitinol stents' cytocompatibility with endothelial cells. Methods of TiO2 and N-TiO2 sputtering and cytocompatibility assessments vary significantly among different research groups, making it difficult to compare results. The aim of this work was to develop an integral cytocompatibility index (ICI) and a decision tree algorithm (DTA) using the "EA.hy926 cell/TiO2 or N-TiO2 coating" model and to determine the optimal cytocompatible coating. Magnetron sputtering was performed in a reaction gas medium with various N2:O2 ratios and bias voltages. The samples' morphology was studied by scanning electron microscopy (SEM) and Raman spectroscopy. The cytocompatibility of the coatings was evaluated in terms of their cytotoxicity, adhesion, viability, and NO production. The ICI and DTA were developed to assess the cytocompatibility of the samples. Both algorithms demonstrated the best cytocompatibility for the sample sputtered at Ubias = 0 V and a gas ratio of N2:O2 = 2:1, in which the rutile phase dominated. The DTA provided more detailed information about the cytocompatibility, which depended on the sputtering mode, surface morphology, and crystalline phase. The proposed mathematical models relate the cytocompatibility and the studied physical characteristics.