Partial Pressure Range Research Articles

Oxygen Nonstoichiometry, Electrical Conductivity, Chemical Expansion and Electrode Properties of Perovskite-Type SrFe0.9V0.1O3−δ

X-ray diffraction analysis of the pseudo-binary SrFe1−xVxO3−δ system showed that the solid solution formation limit at atmospheric oxygen pressure corresponds to x ≈ 0.1. SrFe0.9V0.1O3−δ has a cubic perovskite-type structure with the Pm3¯m space group. The oxygen nonstoichiometry variations in SrFe0.9V0.1O3−δ, measured by coulometric titration in the oxygen partial pressure range of 10−21 to 0.5 atm at 1023–1223 K, can be adequately described using an ideal solution approximation with V5+ as the main oxidation state of vanadium cations. This approach was additionally validated by statistical thermodynamic modeling. The incorporation of vanadium decreases both oxygen deficiency and the average iron oxidation state with respect to undoped SrFeO3−δ. As a result, the electrical conductivity, thermal expansion and chemical expansivity associated with the oxygen vacancy formation all become lower compared to strontium ferrite. At 923 K, the conductivity of SrFe0.9V0.1O3−δ is 14% lower than that of SrFeO3−δ but 21% higher compared to SrFe0.9Ta0.1O3−δ. The area-specific polarization resistance of the porous SrFe0.9V0.1O3−δ electrode deposited onto 10 mol.% scandia- and 1 mol.% yttria-co-stabilized zirconia solid electrolyte with a protective Ce0.9Gd0.1O2−δ interlayer, was 0.34 Ohm×cm2 under open-circuit conditions at 1173 K in air.

Experimental and kinetic study of pressurized CO2 gasification of biomass chars

Pressurized CO2 gasification of biomass represents an effective approach for the utilization of biomass and the reduction of CO2 emissions. The impact of CO2 partial pressure on the gasification kinetics of biomass chars was examined on a pressurized thermogravimetric analyzer at temperatures between 750 and 950 °C and elevated pressures (up to 1MPa). The findings demonstrated that the gasification rates of corn stalk char (CSC), toonasinesis sawdust char (TSC), and rice husk char (RHC) exhibited an increase with rising CO2 partial pressure. The reaction order exhibited variability with respect to CO2 partial pressure, gasification temperature, and biomass type. The reaction order associated with biomass char exhibited a higher value at the elevated CO2 partial pressure range (0.25–1.0MPa) relative to the low CO2 partial pressure range (0.025–0.1MPa). The nth-order model was employed to elucidate the gasification behaviors of biomass chars. The results indicated that the modified random pore model was successfully applied to model the gasification of CSC and TSC. The grain model was effective in predicting the gasification behavior of RHC. The gasification rates of the three biomass chars were accurately predicted by the Langmuir-Hinshelwood model at both low and high CO2 partial pressures. This study presents information on the effect of CO2 partial pressure on biomass char gasification and methods for predicting biomass char gasification under pressurized conditions.

Thermodynamic Modeling of an Aqueous N, N-Dimethyldipropylenetriamine and Benzylamine Blend for Efficient CO2 Capture.

This study evaluates the carbon dioxide (CO2) capture capabilities of a novel aqueous blend of N,N-dimethyldipropylenetriamine (DMDPTA) and benzylamine (BA). The solvent properties such density, vapor- liquid equilibrium (VLE) of CO2 in the solvent, CO2 absorption enthalpy are evaluated experimentally for solvent composition of (5 mass % DMDPTA+25 mass % BA), (10 mass % DMDPTA+20 mass % BA), and (15 mass % DMDPTA+15 mass % BA). Solvent density were measured in the temperature range of 303 K-333 K and correlated using Redlich-Kister excess molar volume model, with a low average absolute relative deviation (AARD) of 0.014. VLE data was measured using a custom-made stirred VLE cell, within CO2 partial pressure range of 2-200 kPa and at temperatures 313 K, 323 K and 333 K. Equilibrium CO2 solubility data were correlated using a modified Kent-Eisenberg model, achieving an AARD of 1.5 %. Enthalpy of CO2 absorption was measured at 313 K using a Meter Toledo reaction calorimeter. Results indicated that under similar process conditions and solvent composition, (DMDPTA+BA) blends exhibited significantly higher CO2 loading and low absorption enthalpy compared to aqueous BA and monoethanolamine solvent alone indicating the potential of (DMDPTA+BA) blend as efficient CO2 capture solvent.

Influence of oxygen partial pressure on the passivation and depassivation of super 13Cr stainless steel in high temperature and CO2 rich environment

The passivation and depassivation characteristics of Super 13Cr stainless steel were examined under a range of oxygen partial pressures within a high-temperature (120 ℃) and high-pressure (3 MPa) CO2 atmosphere. We performed comprehensive electrochemical assessments, encompassing open-circuit potential monitoring, electrochemical impedance spectroscopy, and linear polarization resistance analysis, to evaluate the corrosion resistance and passive film stability. The results demonstrate that the addition of low O2 partial pressures enhanced the stability of the passive film, while higher O2 levels led to the loss of the passivation properties of Super 13Cr stainless steel. The study elucidates the pivotal role of oxygen in the corrosion mechanisms affecting Super 13Cr stainless steel, presenting valuable data to enhance for integrity management in severe environmental conditions.

Surface-enhanced CO2 capture in ionic liquid-silica nanocomposites via sol-gel synthesis in the low partial pressure range

Ionic liquid-containing silica nanocomposites enable the capture of carbon dioxide from gas mixtures containing nitrogen, oxygen, and methane. Synthesis methods explored for such nanocomposites include impregnating porous silica and one-pot synthesis via a sol-gel process. This research investigates a non-hydrolytic sol-gel route for nanocomposite materials enabling CO2 capture at low partial pressures (0.1–0.4 bar). The tetraethyl orthosilicate (TEOS) precursor condensation resulted in a silica matrix formed around ionic liquid domains, for bis(trifluorosulfonylimide) (TFSI−)-based ionic liquids with 1-butyl-1-methylpyrrolidinium (BMP+), 1-butyl-3-methylimidazolium (BMI+), 1-ethyl-3-methylimidazolium (EMI+) and 1-hexyl-3-methylimidazolium (HMI+) cations. Using a one-pot synthesis method enables exploring CO2 sorption in such nanocomposites for ionic liquid-to-silica contents up to fourteen times higher than in previously reported studies. Moreover, the selected synthesis method provides greater tunability in deposition methods and their control. The silica host matrix was characterized by N2 adsorption isotherms at 77 K after solvent extraction and supercritical drying of the material for ionic liquid removal. The pore size distribution of the freestanding silica network was observed via Scanning Electron Microscope (SEM) imaging and assessed with the Barrett-Joyner-Halenda (BJH) method for nanocomposites of different [BMP][TFSI]-to-silica ratio. The CO2 uptake at pressures down to 0.1 bar was evaluated from CO2 adsorption isotherms at 303 K. The confinement of [BMP][TFSI] resulted in a beneficial effect for the CO2 uptake at lower partial pressures, with an uptake five times higher than the sum of the individual uptake expected from the contained ionic liquid and silica. The reported results show the advantage of a one-pot synthesis method for broader tunability of the nanocomposite, both regarding its content and application, as well as increased performance at lower partial pressures compared to the nanocomposite's individual constituents.

Effect of Temperature and Oxygen Concentration on Corrosion of J55 Steel in an O2/CO2 Environment

ABSTRACTThe corrosion product competition and transformation process of J55 under an O2/CO2 environment in the temperature range of 50–350°C and 0–1 MPa oxygen partial pressure range, respectively, were studied using electrochemical and surface analysis techniques as well as thermodynamic calculations to determine its corrosion rate change law and pitting corrosion phenomenon. This study demonstrates that the uniform corrosion rate of J55 with increasing temperature shows a trend of first increasing, then decreasing, and finally increasing. The transformation of its corrosion products, from FeCO3 into Fe3O4, is consistent with the altering corrosion rate law with increasing temperatures. J55 corrodes faster at 350°C as the O2 partial pressure increases. When the O2 partial pressure is low, the predominant kind of corrosion product that is obtained is FeCO3; when the O2 partial pressure exceeds 0.2 MPa, all corrosion products are transformed into iron oxides. As the oxygen partial pressure increases, J55's corrosion product film becomes increasingly less protective of the substrate, making the substance more vulnerable to corrosion reactions.

Enabling defect control or polyiodide formation regimes in halide perovskites

Defect engineering in oxide materials is typically achieved through manipulation of oxygen pressure and temperature, followed by quenching which freezes the concentration of point defects. Unlike oxides, halide perovskites equilibrate with gaseous atmosphere at room temperature. Information on defect engineering in halide perovskites that utilize the concentration of gaseous species is scarce and controversial. In this report we address this controversy by studying the interaction of MAPbI3 with molecular iodine over a wide range of partial pressures and reveal the two regimes of such interaction: defect control regime and polyiodide formation regime switching at ∼20 % of the saturated iodine pressure. In defect control regime the material undergoes reversible changes in semiconductor properties, while in polyiodide formation regime the material undergoes irreversible changes in crystallinity and microstructure. These findings emphasize the manifold role of molecular iodine for this class of materials and provides researchers with the experimental framework that can be utilized to tune stoichiometry and conductivity of halide perovskites to further enhance the performance and stability metrics of the corresponding devices.

MODELLING OF HYDROGEN FLOW FROM GAS MIXTURES THROUGH NICKEL CAPILLARIES CONSIDERING THE NONUNIFORMITY OF TEMPERATURE DISTRIBUTION

A mathematical model of the flow of hydrogen from gas mixtures through the walls of capillary tubes made of metallic nickel has been developed, taking into account the inhomogeneity of the partial pressure of hydrogen along a long tube, as well as temperature nonuniformity in different regions of the tube. Using the model and relying on experimental data, the kinetic parameters of hydrogen transport were calculated within the temperature range of 600-850 °С and the hydrogen partial pressure range of 0.3-0.8 atm. The model can be used in the design of membrane modules for hydrogen separation from gas mixtures to calculate the length of individual membranes, their number, and the optimal flow rate of the hydrogen-containing gas mixture through the membrane.

Development of V2O3 Nanostructures for Alkali Metal Ion Batteries: A Novel Approach through Mild Metal Vapor Reduction and Interface Engineering.

V2O3 has been extensively researched as a battery electrode material due to its ample reserves and high theoretical capacity. However, the synthesis of valence-sensitive V2O3 presents technical challenges as it requires a strict combination of high-temperature treatment and a narrow range of oxygen partial pressures. This study proposes a gentle Li vapor-assisted thermal reduction method to synthesize pure-phase V2O3 at a relatively low temperature of 480 °C without any hazardous gases. It has been discovered that reducing the temperature also improves the specific surface area of the nanoto-mesoscale hierarchical structures and enhances the reactive sites between their secondary grains. These advantages enable the V2O3 micronano particles to store higher levels of Li+, Na+, and K+, increase ionic transport, and tolerate volume expansion. It demonstrates a significant capacity of 767 mA h g-1 in lithium-ion batteries, 393 mA h g-1 in sodium-ion batteries, and 209 mA h g-1 in potassium-ion batteries. It has also been discovered that the crystal structure of V2O3 is easily adjustable by varying the synthesis temperature, which significantly affects the electrochemical storage mechanism. The V2O3 synthesized at 480 °C with low crystallinity exhibits a notable intercalation reaction, facilitating the electrochemical kinetics of reversible insertion/extraction of Li+, Na+, and K+. In contrast, the highly crystalline sample synthesized at 580 °C displays pseudocapacitance behavior instead of an intercalation reaction. The highly crystalline sample synthesized at 680 °C exhibits a thorough pseudocapacitance reaction possessing the capacitive functionality for the electrochemical storage of Na+ or K+ with larger ion radii. This study describes a new synthesis strategy and rational modification of vanadium-based electrodes for alkali metal ion batteries, leading to the development of reasonably priced rechargeable battery systems with applications extending beyond lithium-ion batteries.

H2-D2 Exchange Activity and Electronic Structure of Ag x Pd1-x Alloy Catalysts Spanning Composition Space.

Many computational studies of catalytic surface reaction kinetics have demonstrated the existence of linear scaling relationships between physical descriptors of catalysts and reaction barriers on their surfaces. In this work, the relationship between catalyst activity, electronic structure, and alloy composition was investigated experimentally using a Ag x Pd1-x Composition Spread Alloy Film (CSAF) and a multichannel reactor array that allows measurement of steady-state reaction kinetics at 100 alloy compositions simultaneously. Steady-state H2-D2 exchange kinetics were measured at atmospheric pressure on Ag x Pd1-x catalysts over a temperature range of 333-593 K and a range of inlet H2 and D2 partial pressures. X-ray photoelectron spectroscopy (XPS) was used to characterize the CSAF by determining the local surface compositions and the valence band electronic structure at each composition. The valence band photoemission spectra showed that the average energy of the valence band, ε̅v, shifts linearly with composition from -6.2 eV for pure Ag to -3.4 eV for pure Pd. At all reaction conditions, the H2-D2 exchange activity was found to be highest on pure Pd and gradually decreased as the alloy was diluted with Ag until no activity was observed for compositions with x Pd < 0.58. Measured H2-D2 exchange rates across the CSAF were fit using the Dual Subsurface Hydrogen (2H') mechanism to extract estimates for the activation energy barriers to dissociative adsorption, ΔE ads ‡, associative desorption, ΔE des ‡, and the surface-to-subsurface diffusion energy, ΔE ss, as a function of alloy composition, x Pd. The 2H' mechanism predicts ΔE ads ‡ = 0-10 kJ/mol, ΔE des ‡ = 30-65 kJ/mol, and ΔE ss = 20-30 kJ/mol for all alloy compositions with x Pd ≥ 0.64, including for the pure Pd catalyst (i.e., x Pd = 1). For these Pd-rich catalysts, ΔE des ‡ and ΔE ss appeared to increase by ∼5 kJ/mol with decreasing x Pd. However, due to the coupling of kinetic parameters in the 2H' mechanism, we are unable to exclude the possibility that the kinetic parameters predicted when x Pd ≥ 0.64 are identical to those predicted for pure Pd. This suggests that H2-D2 exchange occurs only on bulk-like Pd domains, presumably due to the strong interactions between H2 and Pd. In this case, the decrease in catalytic activity with decreasing x Pd can be explained by a reduction in the availability of surface Pd at high Ag compositions.

MiR-18a affects hypoxia induced glucose metabolism transition in HT22 hippocampal neuronal cell line through the Hif1a gene

Hypoxia can cause a variety of diseases, including ischemic stroke and neurodegenerative diseases. Within a certain range of partial pressure of oxygen, cells can respond to changes in oxygen. Changes in oxygen concentration beyond a threshold will cause damage or even necrosis of tissues and organs, especially for the central nervous system. Therefore, it is very important to find appropriate measures to alleviate damage. MiRNAs can participate in the regulation of hypoxic responses in various types of cells. MiRNAs are involved in regulating hypoxic responses in many types of tissues by activating the hypoxia-inducible factor (HIF) to affect angiogenesis, glycolysis and other biological processes. By analyzing differentially expressed miRNAs in hypoxia and hypoxia-related studies, as well as the HT22 neuronal cell line under hypoxic stress, we found that the expression of miR-18a was changed in these models. MiR-18a could regulate glucose metabolism in HT22 cells under hypoxic stress by directly regulating the 3’UTR of the Hif1a gene. As a small molecule, miRNAs are easy to be designed into small nucleic acid drugs, so this study can provide a theoretical basis for the research and treatment of nervous system diseases caused by hypoxia.Graphical

Mass transfer and kinetic measurement and modeling for CO2 absorption into aqueous EAE and water-lean EAE/NMP solvents

Chemical absorption using amine solvent is currently available technology for CO2 capture from post-combustion flue gas. It is hindered by high operating cost and high capital cost due to high regeneration energy and slow CO2 absorption rate of amine solvent. Water-lean solvent of 2-(ethylamino) ethanol (EAE)/1-methyl-2-pyrrolidinone (NMP)/water could be a potential solution as it achieved significantly low regeneration energy of 2.3 GJ/tCO2 tested in a pilot plant. However, kinetics of CO2 reaction with EAE and mass transfer rate of CO2 absorption into EAE/NMP solvent are not fully understood. In this work, kinetics of CO2 absorption into unloaded aqueous EAE in 1–5 mol/L at 300–313 K and mass transfer of CO2 absorption into CO2-loaded EAE/NMP water-lean solvent in 5 mol/L with equilibrium CO2 partial pressure (PCO2*) range of 0.3–7 kPa at 312 K were studied in a wetted wall column. Kinetic data of aqueous EAE is interpreted by zwitterion mechanism, and the reaction is of first order with respect to EAE concentration in 1–5 mol/L at 300–313 K. CO2 absorption rate (kg’) of EAE/NMP water-lean solvent is 1.3–2.1 times greater than aqueous EAE due to the greater CO2 physical solubility. At lean and rich loading conditions, 5 M EAE in 3NMP/1water and 9NMP/1water show 2–7 times faster kg’ than 30 % MEA, and 1.4–2.5 times faster kg’ than 30 % PZ. It is found that EAE activity coefficient may increase in the presence of NMP in the solvent, and the estimated EAE activity coefficient in 1NMP/1water, 3NMP/1water, and 9NMP/1water are 2.13, 3.50, and 4.72, respectively. CO2 capacity of EAE/NMP solvent is 2–3.7 times greater than 30 % MEA and 1.2–2 times greater than 30 % PZ.

Behavior of calcium lignosulfonate under oxygen pressure acid leaching condition

The behavior of calcium lignosulfonate (CLS) in the oxygen pressure acid leaching process of ZnS concentrate was investigated using total organic carbon assessment (TOC), UV–visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR), and gas chromatography-coupled mass spectrometry (GC–MS) as characterization methods. The effect of the CLS degradation products on zinc electrowinning was also discussed. The results showed that the temperature was positively correlated with the degradation of CLS, while the initial acidity had only significant effects in the range of 0–50 g/L and oxygen partial pressure range of 0–0.1 MPa. At an oxygen partial pressure of 0.2 MPa, an acidity of 160 g/L, and a reaction temperature of 150 °C, about 82.4% of CLS was degraded. In the oxygen pressure acid leaching process, CLS underwent polymerization and decomposition reactions, and its aromatic rings and side chain groups were damaged to varying degrees. At 120 °C, CLS was partially converted into sulfonic acids, phenols, and esters of higher molecular weights. At 150 °C, CLS further degraded into lower-molecular-weight aromatic ethers and sulfonic acids with shorter carbon chains. These organics were relatively stable and were the main sources of organic compounds during the oxygen pressure leaching process of zinc concentrates. The addition of CLS had a significant negative impact on zinc electrowinning, which was related to the adsorption of CLS on the cathode surface, enhancing cathodic polarization and inhibiting zinc reduction kinetics.

Elucidation of the Transport Properties of Calcium-Doped High Entropy Rare Earth Aluminates for Solid Oxide Fuel Cell Applications.

Solid oxide fuel cells (SOFCs) are paving the way to clean energy conversion, relying on efficient oxygen-ion conductors with high ionic conductivity coupled with a negligible electronic contribution. Doped rare earth aluminates are promising candidates for SOFC electrolytes due to their high ionic conductivity. However, they often suffer from p-type electronic conductivity at operating temperatures above 500°C under oxidizing conditions caused by the incorporation of oxygen into the lattice. High entropy materials are a new class of materials conceptualized to be stable at higher temperatures due to their high configurational entropy. Introducing this concept to rare earth aluminates can be a promising approach to stabilize the lattice by shifting the stoichiometric point of the oxides to higher oxygen activities, and thereby, reducing the p-type electronic conductivity in the relevant oxygen partial pressure range. In this study, the high entropy oxide (Gd,La,Nd,Pr,Sm)AlO3 is synthesized and doped with Ca. The Ca-doped (Gd,La,Nd,Pr,Sm)AlO3 compounds exhibit a higher ionic conductivity than most of the corresponding Ca-doped rare earth aluminates accompanied by a reduction of the p-type electronic conductivity contribution typically observed under oxidizing conditions. In light of these findings, this study introduces high entropy aluminates as a promising candidate for SOFC electrolytes.

A First-Principles Thermodynamic Model for the Ba-Zr-S System in Equilibrium with Sulfur Vapor.

The chalcogenide perovskite BaZrS3 has strong visible light absorption and high chemical stability, is nontoxic, and is made from earth-abundant elements. As such, it is a promising candidate material for application in optoelectronic technologies. However, the synthesis of BaZrS3 thin-films for characterization and device integration remains a challenge. Here, we use density functional theory and lattice dynamics to calculate the vibrational properties of elemental, binary, and ternary materials in the Ba-Zr-S system. This is used to build a thermodynamic model for the stability of BaZrS3, BaS x , and ZrS x in equilibrium with sulfur gas across a range of temperatures and sulfur partial pressures. We highlight that reaction thermodynamics are highly sensitive to sulfur allotropes and the extent of allotrope mixing. We use our model to predict the synthesis conditions in which BaZrS3 and the intermediate binary compounds can form. At a moderate temperature of 500 °C, we find that BaS3, associated with fast reaction kinetics, is stable at pressures above 3 × 105 Pa. We also find that BaZrS3 is stable against decomposition into sulfur-rich binaries up to at least 1 × 107 Pa. Our work provides insights into the chemistry of this promising material and suggests the experimental conditions required for the successful synthesis of BaZrS3.

Reduction of Cofed Carbon Dioxide Modifies the Local Coordination Environment of Zeolite-Supported, Atomically Dispersed Chromium to Promote Ethane Dehydrogenation.

The reduction of CO2 is known to promote increased alkene yields from alkane dehydrogenations when the reactions are cocatalyzed. The mechanism of this promotion is not understood in the context of catalyst active-site environments because CO2 is amphoteric, and even general aspects of the chemistry, including the significance of competing side reactions, differ significantly across catalysts. Atomically dispersed chromium cations stabilized in highly siliceous MFI zeolite are shown here to enable the study of the role of parallel CO2 reduction during ethylene-selective ethane dehydrogenation. Based on infrared spectroscopy and X-ray absorption spectroscopy data interpreted through calculations using density functional theory (DFT), the synthesized catalyst contains atomically dispersed Cr cations stabilized by silanol nests in micropores. Reactor studies show that cofeeding CO2 increases stable ethylene-selective ethane dehydrogenation rates over a wide range of partial pressures. Operando X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine-structure (EXAFS) spectra indicate that during reaction at 650 °C the Cr cations maintain a nominal 2+ charge and a total Cr-O coordination number of approximately 2. However, CO2 reduction induces a change, correlated with the CO2 partial pressure, in the population of two distinct Cr-O scattering paths. This indicates that the promotional effect of parallel CO2 reduction can be attributed to a subtle change in Cr-O bond lengths in the local coordination environment of the active site. These insights are made possible by simultaneously fitting multiple EXAFS spectra recorded in different reaction conditions; this novel procedure is expected to be generally applicable for interpreting operando catalysis EXAFS data.

Cross-Validation of the Remarkably High Surface Oxygen Exchange Kinetics of PrBa0.5Sr0.5Co1.5Fe0.5O5+δ: A Combined Thin-Film Mass Relaxation and Bulk Electrical Conductivity Relaxation Study.

In this work, we measure the oxygen kinetic properties of double perovskite PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF), a material widely used as the air electrode in solid oxide electrochemical cells, by mass relaxation (MR) and electrical conductivity relaxation (ECR) experiments. MR studies are carried out using thin films deposited on a gallium phosphate piezocrystal microbalance, and ECR studies are performed using a bulk bar sample with 97% theoretical density. Measurements are performed at 600 °C over the temperature oxygen partial pressure range from 10-4 to 0.21 atm. Despite the differences in experimental formats and surface microstructural features, the ks values extracted from the two methods are found to be in good agreement with one another. The rate constant is found to increase with oxygen partial pressure with a power law dependence, rising from 1.0 × 10-6 cm/s at 3.2 × 10-4 atm to 1.2 × 10-4 cm/s at 0.24 atm, as averaged over the oxidation and reduction directions. The rates in the oxidation direction are observed to be slightly higher than those in the reduction direction for a given pair of pO2 values, suggesting that the final pO2 value controls the overall relaxation behavior. The power law exponent describing the dependence of ks on pO2 is found to be 0.74 ± 0.01. The ECR study of the bulk sample reveals that even with a diffusion length of 1.8 mm, the relaxation process is largely free of diffusion limitations, indicating that PBSCF has the high bulk transport properties required for a double-phase boundary oxidation/reduction pathway.

Experimental study on the dissolution characteristics of ethane into oil‐based mud in complex oil and gas wellbore environments

AbstractAccurately determining the solubility of ethane in oil‐based mud is crucial for assessing the severity of gas kicks and implementing appropriate well control procedures. The key factors influencing the solubility of ethane gas in oil‐based drilling fluids include the content of base oil, pressure, temperature, and the viscosity of the drilling fluid. This study aims to test the solubility of high‐purity ethane in oil‐based mud under simulated downhole conditions in a 5000 m deep well. The test covers a temperature range of 40–140°C and a partial pressure range of 0.17–5.92 MPa. The effects of temperature, pressure, base oil content, and drilling fluid viscosity on the solubility of ethane are analyzed using various experimental data processing methods. The results show that the variation in ethane solubility with pressure and temperature is nearly linear within the specified ranges. Furthermore, the impact of pressure (1.24–2.78%/MPa) on solubility is approximately 50 times greater than that of temperature (−0.013 to −0.049%/°C) in oil‐based drilling mud. Additionally, ethane's solubility decreases as the drilling fluid's viscosity increases. The ethane solubility in 80% and 90% oil‐based muds is roughly 1.6 times and 2.0 times higher than in 70% oil‐based mud under the same testing conditions. Models for predicting ethane solubility have been developed using screening procedures and statistical regression. These models can be incorporated into gas–liquid flow models to analyze flow behavior during gas kicks.

Hypercapnia Causes Injury of the Cerebral Cortex and Cognitive Deficits in Newborn Piglets.

In critically ill newborns, exposure to hypercapnia (HC) is common and often accepted in neonatal intensive care units to prevent severe lung injury. However, as a "safe" range of arterial partial pressure of carbon dioxide levels in neonates has not been established, the potential impact of HC on the neurodevelopmental outcomes in these newborns remains a matter of concern. Here, in a newborn Yorkshire piglet model of either sex, we show that acute exposure to HC induced persistent cortical neuronal injury, associated cognitive and learning deficits, and long-term suppression of cortical electroencephalogram frequencies. HC induced a transient energy failure in cortical neurons, a persistent dysregulation of calcium-dependent proapoptotic signaling in the cerebral cortex, and activation of the apoptotic cascade, leading to nuclear deoxyribonucleic acid fragmentation. While neither 1 h of HC nor the rapid normalization of HC was associated with changes in cortical bioenergetics, rapid resuscitation resulted in a delayed onset of synaptosomal membrane lipid peroxidation, suggesting a dissociation between energy failure and the occurrence of synaptosomal lipid peroxidation. Even short durations of HC triggered biochemical responses at the subcellular level of the cortical neurons resulting in altered cortical activity and impaired neurobehavior. The deleterious effects of HC on the developing brain should be carefully considered as crucial elements of clinical decisions in the neonatal intensive care unit.

Catalytic Metal‐Gated Nano‐Sheet Field Effect Transistor and Nano‐Sheet Tunnel Field Effect Transistor Based Hydrogen Gas Sensor‐ A Design Perspective

AbstractIn this work, for the first time, the catalytic metal gate (CMG) based nanosheet Field Effect Transistor (NSFET) and nanosheet Tunnel Field Effect Transistor (NSTFET) are proposed for nano‐scale device dimensions, and the different design aspects of catalytic metal gate (CMG)‐based transduction for Hydrogen (H2) sensing are extensively investigated using numerical device simulation. The influence of applied biasing conditions and structural parameter specifications on the sensing performance of CMG‐NSFET and CMG‐NSTFET are methodically analyzed from device electrostatics and carrier transport mechanisms. Furthermore, the relative maximum sensitivity variations with H2‐partial pressure, ambient temperature, and the presence of ambient Oxygen are comprehensively studied. The study reveals that compared to CMG‐NSFET, the CMG‐NSTFET demonstrates a high immunity against bias and doping variations, with a notably higher (&gt; 50%) sensitivity within low H2 partial pressures (10−15 – 10−10 Torr). Next, the sensing performance of CMG‐NSTFET is systematically optimized through a band‐gap and gate‐stack engineering approach, leading to a 180% to 650% sensitivity improvement from lower (10−15 Torr) to higher (10−5 Torr) range of H2 partial pressure. Finally, the performance of optimized CMG‐NSFET and CMG‐NSTFET are extensively benchmarked against other reported nanostructured CMG‐FET and TFET‐based H2 gas sensors, exhibiting a notably higher sensitivity in the proposed sensors.