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The curtaining effect is a common challenge in focused ion beam (FIB) surface preparation. This study investigates methods to reduce this effect during plasma FIB milling of Inconel 718 (nickel‐based superalloy). Platinum deposition, silicon mask and XeF2 gas injection were explored as potential solutions. These methods were evaluated for two ion beam current conditions; a high ion beam intensity condition (30 kV–1 µA) and a medium one (30 kV–100 nA) and their impact on curtaining reduction and resulting cross‐section quality was assessed quantitatively thanks to topographic measurements done by atomic force microscopy (AFM). XeF2 assistance notably improved cross‐section quality at medium current level. Pt deposition and Si mask individually mitigated the curtaining effect, with greater efficacy at 100 nA. Both methods also contributed to reducing cross‐section curvature, with the Si mask outperforming Pt deposition. However, combining Pt deposition and Si mask with XeF2 injection led to deterioration of these protective layers and the reappearance of the curtaining effect after a quite short exposure time. LAY DESCRIPTION: The so‐called curtaining effect is a common challenge in focused ion beam (FIB) surface preparation. It is characterised by a relief occurring on the FIB prepared surface whereas a perfectly flat surface would ideally be expected. The issue of FIB‐induced curtaining effect represents a significant challenge in large‐scale 3D analysis applications, notably in methodologies reliant on FIB serial sectioning, such as 3D electron backscatter diffraction (3D EBSD). A strong curtaining effect can alter data quality and so their interpretation after 3D reconstruction. This study investigates methods to reduce this effect during plasma FIB milling of Inconel 718 (nickel‐based superalloy). Platinum deposition, silicon mask and XeF2 gas injection were explored as potential solutions. These methods were evaluated for two ion beam current conditions: a high ion beam intensity condition (30 kV–1 µA) and a medium one (30 kV–100 nA) and their impact on curtaining reduction, and resulting cross‐section quality was assessed quantitatively thanks to topographic measurements done by atomic force microscopy (AFM). XeF2 assistance notably improved cross‐section quality at medium current level. Pt deposition and Si mask individually mitigated the curtaining effect, with greater efficacy at 100 nA. Both methods also contributed to reducing cross‐section curvature, with the Si mask outperforming Pt deposition. However, combining Pt deposition and Si mask with XeF2 injection led to deterioration of these protective layers and the reappearance of the curtaining effect after a quite short exposure time. [ABSTRACT FROM AUTHOR]

To study the smelting reduction behavior of methane in the HIsarna process, the isothermal reduction experiments of HIsarna slag with 6 wt% of FeO were conducted at the temperatures of 1450, 1475, and 1550 °C, using 5 vol% CH4‐Ar. The effect of the gas injection flow rate on the overall reduction rate was investigated in the range of 0.5–1.5 L min−1. The results confirm that the decomposed carbon black acts as the dominant reductant in the reduction process compared to hydrogen. Increased gas flow rate increases the reaction rate, while temperature shows no significant effect. The reduction process could be described by the JMAEK model: by fixing the gas flow rate at 1.0 L min−1 with different temperatures, the exponent n value is around 1.5, indicating FeO mass transfer is the limiting step since there are sufficient carbon blacks as nucleation sites. The reduction process follows the first‐order model controlled by the reactant concentration with the gas flow rate being at 0.5 L min−1 and in the second reaction stage of the gas flow rate at 1.5 L min−1. The determined activation energy for the methane reduction is 59.8 kJ mol−1. [ABSTRACT FROM AUTHOR]

Background: Dark eye circle (DEC) is one of the most common cosmetic problems. It has a great impact on the patients' quality of life. Carboxytherapy is a cosmetic technique using pure carbon dioxide for different uses in different areas of the body. The goal of this study is to evaluate the efficacy and tolerability of carboxytherapy in the cosmetic correction of DECs. Methods: This study was conducted on 27 patients requesting the correction of DEC. The treatment was performed using a carboxy device in medical grade. The gas injection was performed intradermal after local anesthesia, with a pressure of one tenth bar and a speed of 20 cc/min, 1 cc in each upper and lower eyelid. The treatment sessions were done every 2 weeks for four sessions. Results: The mean physicians' score of DECs before and after treatment was 8.7 ± 0.81 and 4.6 ± 1.1, respectively. The mean patients' score before and after treatment was 9.2 ± 0.5 versus 5.41 ± 1.37. The mean scores showed a significant reduction of skin discoloration without major side effects (p < 0.00001). Conclusion: Carboxytherapy seems to be an effective treatment option for dark circles around the eyes with a good safety profile and patient satisfaction. [ABSTRACT FROM AUTHOR]

Enhanced coalbed methane (ECBM) recovery by gas injection is regarded as a feasible method for ECBM recovery. To investigate the mechanism of CH4 displacement by N2 injection, a series of physical experiments were conducted in the laboratory under different N2 injection pressures. The experimental results showed a continuous increase in the N2 volume fraction and a decrease in the CH4 volume fraction with the N2 injection pressure. The CH4 displacement efficiency increases rapidly in the initial stage and then gradually stabilizes. Given the effect of matrix shrinkage and effective stress on coal permeability, a dynamic multi‐field coupling model of ECBM recovery by N2 injection (N2‐ECBM) was proposed in this work. Then, numerical simulations were implemented by the coupling model to analyze the key factors affecting coal permeability, N2 injection pressure and CH4 pressure during the N2–ECBM process. Furthermore, the Response Surface Methodology (RSM) was used to investigate the interactions of multiple factors, the results reveal that an increase in one factor would weaken the influence of another factor. In addition, a RSM regression model was obtained and verified by the experimental data, with a well‐fitting outcomes. Therefore, the RSM model can be used in practical engineering applications to optimize specific extraction parameters for ECBM recovery at minimum cost in a limited extraction period. [ABSTRACT FROM AUTHOR]

For field development and drilling decisions, production assets and reservoir engineers require dynamic reservoir properties, such as saturation and pressure changes of a reservoir from the pre‐production virgin state. To date, geophysicists have produced time‐lapse (4D) seismic attributes (mostly on stacked seismic data) rather than dynamic parameters directly. In this paper, we present a new method to estimate saturation and pressure properties from time‐lapse seismic data to provide to reservoir engineers. This new three‐step method is demonstrated over the Edvard Grieg field in the North Sea. We can realize this method thanks to advanced seismic multi‐component acquisition via PP and PS seismic data and processing that allows accurate estimation of amplitude‐variation‐with‐offset parameters P‐ and S‐impedances. With time‐lapse P‐ and S‐impedances optimally resolved, we estimate a stable set of axes identifying water saturation increase (water replacing oil), gas saturation increase (gas injection or gas out of solution), pressure increase (at injectors) and pressure decrease (at producers). Once these axes are obtained, we convert every 4D P‐ and S‐impedance data points into 4D pseudo‐saturation and pseudo‐pressure using a transformation of coordinates. We next use the rock physics relationships of this field to show that a linear relationship can be used to map any 4D change in the field from impedances to saturations and pressures. Key locations in the field with largest saturation and pressure changes are used to find calibration values at these extreme points. Next, from the pseudo‐seismic 4D data, a linear mapping is used to calculate actual reservoir property changes (fractions for saturation and bars for pressure). This allows us to obtain fieldwide dynamic values for water and gas saturations and injection and production related pressure changes. The results are shown, and dynamic changes are interpreted on the Edvard Grieg field data. [ABSTRACT FROM AUTHOR]

The objective of this study is to develop an analytical model for 1D gas‐water flow with evaporation of water into the mobile gas phase. The evaporation rate is proportional to the fluid‐fluid interfacial area, which is a function of the water saturation. Introduction of saturation‐dependent potential allows reducing the 2 × 2 non‐linear system of PDEs to one hyperbolic equation. The saturation distribution is obtained by non‐linear method of characteristics. The first integral allows for explicit expression of the vapor concentration versus saturation. It was shown that typical properties of rock‐CO2‐water system, the evaporation time has order of magnitude of millions of pore volumes injected. Close match was observed between a series of three corefloods and the analytical model, and the tuned model coefficients belong to their common intervals. This validates the developed model for 1D gas‐water flow with water evaporation into the injected gas. Plain Language Summary: During injection of carbon dioxide or other gases into porous media containing small fractions of water, the water phase will slowly evaporate into the injected gas. This process is important as the gradual drying of the porous media near the injection site can lead to formation damage processes such as fines migration and salt precipitation, resulting in a significant decline in the ability to inject more gas. The evaporation process is dependent on the interfacial area between the gas and water. As the evaporation process progresses, this area gets smaller, and the evaporation rate slows down. In this work, we account for this effect directly, and solve the resulting differential equations, providing simple equations that can be used to predict the rate of water evaporation during gas injection. Key Points: Exact solution of gas transport in porous media with non‐equilibrium evaporation kinetics is obtainedThe new solution relies on introducing a new potential function, which reduces the system of non‐linear PDEs to one equationThe resulting exact solution shows good agreement with laboratory data and can predict accurately the evaporation time [ABSTRACT FROM AUTHOR]

To solve the problems of high sampling requirements and low predictive accuracy resulting from the complexity, uniqueness, and randomness of predicting the risk of the CO2 and N2 injection to enhance coal seam gas drainage (CO2/N2–ECGD) technology. The principal component analysis (PCA) method to reduce the dimensionality of the factor data that contribute to the effect risk of the technology was adopted. And the particle swarm optimization (PSO) method was implemented to search for optimal hyperparameters in support vector machine (SVM) by particle search, as a solution to the traditional SVM hyperparameters optimization problem. A novel risk prediction model using machine learning algorithms for gas injection displacement technology was constructed. The prediction results were tested and compared with those of backpropagation (BP), Random Forest (RF), and Decision Tree (DT) models using data from 29 gas injection displacement field projects in China. The results demonstrated that the SVM model had greater accuracy in prediction than the other three models. Additionally, after PSO optimization and dimensionality reduction, the PCA–PSO–SVM model reached 100% prediction accuracy, while requiring less modeling and operation time. The study provided a reliable and reasonable model for predicting technical effects, along with a theoretical basis for risk management and prevention. First, the technology's influencing indicators were analyzed by examining its mechanisms. Second, we utilized the PCA method to reduce the dimensionality of the factor data that contribute to the risk of the technology's effects. Third, we implemented the PSO method to search for optimal hyperparameters in the SVM through particle search, as a solution to the traditional SVM hyperparameters optimization problem. Finally, the prediction results were tested and compared with those of BP, RF, and DT models using data from 29 gas injection displacement field projects in China. The SVM model was found to have greater accuracy in prediction than the other three models. After PSO optimization and dimensionality reduction, the PCA–PSO–SVM model achieved 100% prediction accuracy while requiring less modeling and operation time. The study presents a valid and reasonable model for predicting technical effects and a theoretical basis for risk management and prevention. [ABSTRACT FROM AUTHOR]

The long‐term cyclic gas injection and production mode of the gas storage will lead to accelerated deformation of the surrounding rock of the old cavity, and even the instability and failure of the cavity. Considering the geological conditions and cavity measurement data of the old cavity of the horizontal butted‐well in China, the deformation and failure characteristics of the long‐term cyclic injection‐production process of the surrounding rock of the old cavity under different internal pressure difference and injection‐production frequency are studied. The long‐term stability of the gas storage is predicted by six indexes: the deformation of surrounding rock, dilatancy safety factor, volume shrinkage rate, plastic zone volume, equivalent strain, and no tensile stress. The results show that with the increase of operation duration and cycle times, the deformation, volume shrinkage rate, and plastic zone volume of the surrounding rock gradually increase after the old cavity is reconstructed into the gas storage and the difference of results under different UGS and CAES gradually expands. The stability of the surrounding rock of the old cavity under the cycle action of CAES will be lower. The number of cycles has a limited impact on the stability of the surrounding rock of the old cavity, while the operation duration and injection‐production pressure are the main determinants of the stability of the surrounding rock of the old cavity. If the old cavity of the salt mine is reconstructed into CAES, the parameters such as the number of cycles, the operation duration, and the injection‐production pressure still need to be considered comprehensively. The research results can provide reference value for the reasonable design of the gas storage pressure range of the old cavity and the safety and stability evaluation of the surrounding rock. [ABSTRACT FROM AUTHOR]

This study focuses on analyzing parameter identifiability in foam displacement models during two‐phase flow in porous media, with a particular emphasis on calibrating relative permeability and foam parameters. We employ the profile likelihood technique and Bayesian inference for identifiability analysis. Successful parameter estimation is demonstrated through steady‐state experiments for relative permeability and foam quality scan experiments when both types of experimental data are available and obtained from the same core sample. However, non‐identifiability issues arise when only foam quality scan data is accessible. Additionally, we investigated a standard practice that fits foam parameters using foam quality scan data obtained from one core sample and permeability values obtained from another core sample, but from the same reservoir. Our results show that this practice is ineffective in correctly estimating foam parameters, leading to misestimation of crucial foam model parameters. These findings underscore the importance of a mandatory relative permeability experiment on a representative core sample from the reservoir for accurate characterization of foam parameters. Without it, misestimation of foam model parameters hinders the proper understanding of foam effects on sweeping porous media. Plain Language Summary: Using foam during water and gas injection in porous media enhances efficiency but requires careful parameter calibration. Computer simulations aid understanding, but when relying on limited data, some parameters may be challenging to estimate accurately. Our study focuses on identifying parameters in foam displacement models, crucial for correctly characterizing foam effects. We show that fitting relative permeability on unrelated core samples is ineffective, leading to misestimation. To accurately understand the impact of foam on porous media, a mandatory relative permeability experiment on a representative core from the reservoir is essential. Non‐identifiable parameters hinder proper foam model characterization, emphasizing the importance of comprehensive experimental approaches. Key Points: Parameter misestimation and non‐identifiability issues hinders foam flow models in porous media when working with limited experimental dataDifferent scenarios underscore the importance of Bayesian inference and profile likelihood in parameter identifiability analysisIt is essential to characterize relative permeability on a representative core sample before estimation of foam model parameters [ABSTRACT FROM AUTHOR]

Glycol‐based antifreeze liquids, commonly composed of ethylene glycol or propylene glycol, have important uses in automotive cooling, but they should be handled with care due to their toxicity. Ethylene glycol is highly toxic to humans and animals. A fast, accurate, precise, and robust method was developed for the simultaneous quantification of seven most important glycols and their isomers. Methods: Glycols were analyzed from diluted sample solution of coolants using gas chromatography coupled with mass spectrometry (GC–MC) in single ion monitoring mode. Results: The method was developed and validated for seven individual glycols (ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol). Limits of detection (1–2 μg/mL) and limits of quantification (10 μg/mL) obtained were appropriate. The present method was applied for the determination of glycols in 10 different antifreeze liquids commercially available on the Romanian market, proving to be reliable. Conclusions: A method that requires only a two‐step dilution of antifreeze samples combined with direct liquid injection GC–MS was validated for the simultaneous quantification of seven glycols (and their isomers) in 10 different types of antifreeze liquids. The results obtained in the validation procedure proved that the GC–MS method is sensitive and precise for the quantification of glycols. [ABSTRACT FROM AUTHOR]

The para spin isomer of hydrogen gas possesses high nuclear spin order that can enhance the NMR signals of a variety of molecular species. Hydrogen is routinely enriched in the para spin state by lowering the gas temperature while flowing through a catalyst. Although parahydrogen enrichments approaching 100% are achievable near the H2 liquefaction temperature of 20 K, many experimentalists operate at liquid nitrogen temperatures (77 K) due to the lower associated costs and overall simplicity of the parahydrogen generator. Parahydrogen that is generated at 77 K provides an enrichment value of ~51% of the para spin isomer; while useful, there are many applications that can benefit from low‐cost access to higher parahydrogen enrichments. Here, we introduce a method of improving parahydrogen enrichment values using a liquid nitrogen‐cooled generator that operates at temperatures less than 77 K. The boiling temperature of liquid nitrogen is lowered through internal evaporation into helium gas bubbles that are injected into the liquid. Changes to liquid nitrogen temperatures and parahydrogen enrichment values were monitored as a function of helium gas flow rate. The injected helium bubbles lowered the liquid nitrogen temperature to ~65.5 K, and parahydrogen enrichments of up to ~59% were achieved; this represents an ~16% improvement compared with the expected parahydrogen fraction at 77 K. This technique is simple to implement in standard liquid nitrogen‐cooled parahydrogen generators and may be of interest to a wide range of scientists that require a cost‐effective approach to improving parahydrogen enrichment values. [ABSTRACT FROM AUTHOR]

It is necessary to improve oil production from reservoirs. Various methods have been proposed to increase oil extraction from reservoir. Each method has specific challenges. In this research, the effect of water and gas injection in to Azadegan reservoir has been analyzed. Azadegan oil field is located south of Iran. In this study, water, immiscible gas and water alternating gas injected to reservoir and its effect on enhanced oil recovery have been investigated. Finally, a comparison between results of methods is provided. Results show that effective method for enhanced oil recovery is immiscible gas injection with 46% oil production efficiency and water alternating gas injection with 36% oil production efficiency. This study shows that oil production efficiency can be increased if duration of gas injection is increased. This study shows, increasing viscosity of water in water alternating gas scenario did not improve the production of Azadegan reservoir. [ABSTRACT FROM AUTHOR]

This study aims to simulate the process of enhanced oil recovery (EOR) during gas injection along with nanoparticles and investigate the affecting parameters in a conventional carbonate oil reservoir. Ansys Fluent software with a suitable multiphase model was used to simulate natural gas injection with a nanoparticle into a core sample. The simulation model was validated with a laboratory test of natural gas injection. Then, to obtain the optimal values of each of the parameters affecting the process of EOR during the natural gas injection along with nanoparticles, the design of the experiment was carried out with the help of Qualitek‐4 software and the Taguchi method. Therefore, three factors, including nanoparticle type (clay, titanium oxide, and silica nanoparticles), nanoparticle diameter (2–50 nm), and the volume fraction of nanoparticles in the base fluid (0.5–5 vol.%), as influential factors on the EOR during natural gas injection along with nanoparticles were chosen. The results of the numerical study indicated that silica nanoparticles significantly affect EOR more than clay and titanium oxide nanoparticles. Moreover, the smaller the diameter of nanoparticles (close to 2 nm) and the more significant the volume fraction of nanoparticles in the base fluid (close to 5 vol.%), the higher the oil recovery factor will be. This phenomenon occurs due to changes in the density and viscosity of the base fluid and, consequently, improves the mobility ratio of the injected fluid. On the other hand, the tiny size of nanoparticles allows them to easily enter the pores of the reservoir rock without entrapping and producing oil from them. Eventually, the highest oil recovery factor (59%) was obtained using silica nanoparticles with a diameter of 2 nm and a volume fraction of 5 vol.% in natural gas injection. [ABSTRACT FROM AUTHOR]

Foam injection has been suggested and demonstrated as a potential gas‐based solution for enhancing oil recovery from underground reservoirs. While the pore‐scale behavior of foam has been investigated for many years, most of those studies were done at room temperature and pressure. A high‐pressure high‐temperature (HPHT) cell was constructed to relax this contributing simplification and evaluate foam behavior under reservoir conditions. The performance of foam injection into a fractured reservoir was investigated experimentally at vertical and horizontal pathways utilizing a 2D microfluidic device. The results showed foam had a higher lamellae density in the fracture network and could direct fluids to the matrix. This was mainly attributed to the created pressure drop in the fractured media dictated by foam self‐tuning ability, which is a higher viscosity in areas with higher conductivity. Generating a viscous crossflow in horizontal tests leads to enhanced recovery relative to gas injection. But the presence of gravity in the vertical tests causes the drainage of the foam film and the segregation of the gas and surfactant solution due to gravity, which ultimately reduces the stability of the foam. Comparing the performance of gas and foam in the vertical injection scenario reveals that foam injection results in a considerably more enhanced oil recovery. The oleic phase had a detrimental impact on foam strength and reduced fluids diversion from fracture to matrix. The sizes of gas bubbles were also larger in the presence of the oleic phase. [ABSTRACT FROM AUTHOR]

Bath stirring, degassing, and decarburization in steel refining are strongly related to flow behaviors. The bubble plume produced in Ruhrstahl–Heraeus (RH) up‐snorkel plays an important role during refining, since it not only acts as a bubble pump, but also provides the reaction interface. Herein, it is aimed to form a new flow pattern in the up‐snorkel by using a nonradially arranged gas‐injection nozzle to enhance the 260 ton RH refining process. The results show that an upward spiral steel flow is produced, when nonradial gas‐injection nozzles are used in the up‐snorkel. Meanwhile, some bubbles moved toward the center region of the up‐snorkel, which may be caused by the centripetal effect in a rotational steel flow. This leads to a more uniform bubble distribution on the cross section of the snorkel, compared to that of the conventional case. Specifically, the circulation flow rate is increased by about 18.0%, and the mixing time are shortened by about 26.2% (criteria of ±5%), compared to that of the conventional case. In addition, the inclusion removal rate is increased by 0.5%, 4.8%, and 11.3% for the inclusion size of 20, 50, and 100 μm, respectively, compared to the conventional radial nozzle case. [ABSTRACT FROM AUTHOR]

The coalescence of two growing bubbles presents unique characteristics compared to static bubble coalescence. The gas injection flowrate significantly affects the different stages of bubble evolution, which is poorly understood. In this study, we investigate the flowrate effects on the lateral coalescence of two growing bubbles experimentally. The synchronous bubbling from adjacent needles is achieved using water to push air. During the bubble growth process, we find that the initial nonlinear evolution of bubble volume is because the bubble emerges as a small spherical cap with a large curvature radius and apparent contact angle. As the neck expands after bubble coalescence, the injection flowrate accelerates the neck evolution compared to the case without air injection. We find the neck expansion time decreases linearly with increasing flowrate, while the expansion speed increases with flowrate, but only in the early stage. Moreover, we propose a new theoretical expression that predicts the neck radius well at all the flowrates. At the post‐coalescence oscillation stage, the average projection area of the coalesced bubble increases linearly with time, except for periodic oscillations. Besides, we find that the injected air primarily influences the coalesced bubble's height, which in turn affects the projection area. [ABSTRACT FROM AUTHOR]

The development of renewable and low‐carbon gases for injection into the gas grid obtained by different processes such as anaerobic digestion, pyrogasification, hydrothermal gasification, and methanation, followed by upgrading steps, increases the demand for analysis and characterization in order to fully manage their integration into the gas value chain. If the analysis of the main compounds (methane, carbon dioxide, hydrogen, and carbon monoxide) is well described, the analysis of impurities in renewable gases remains more challenging due to their various natures and quantities. After a brief description of renewable and low‐carbon methane production processes, the review focuses on the methods used for the analysis of the different compounds in renewable gases, from the main ones to impurities at ppbv levels. Gas chromatography (GC), coupled with different detectors, is the preferred technique, enabling the analysis and quantification of siloxanes, terpenes, oxygenates, and sulfur compounds. Recently, comprehensive two‐dimensional GC has been applied to renewable gases, increasing the number of compounds detected. Non‐chromatographic techniques are also reviewed. As sampling is of major importance in the search for reliable analyses, a whole section is devoted to this aspect. Among the available methods, pre‐concentration on adsorbent tubes emerges as the most relevant solution. [ABSTRACT FROM AUTHOR]

Gas exchange between streams and overlying air is an important physical‐chemical environmental process that is typically determined by injecting a tracer gas into a stream at a steady rate and sampling steady‐state tracer gas concentrations in the stream water. Previous modes of tracer gas injection allow gas‐water partitioning of the tracer gas, making the rate of gas injection and thus the measured gas transfer velocity potentially sensitive to temperature variation. Presented here is a modification to the tracer solution injection method in which a tracer gas solution was prepared in Tedlar® bags from which all headspace was removed before injecting the solution into the stream. Along with four other strategies to prevent a headspace from forming in the bags during tracer injection in the field, this zero‐headspace tracer solution method prevents gas‐water partitioning anywhere in the injection system, allowing a steady delivery of tracer gas to the stream even in the presence of variation in air and/or stream water temperature. A field test of the method in Nebraska yielded a gas transfer velocity of 4.1 m/day, within the range found in the literature for similarly‐sized streams. Plain Language Summary: This paper reports on the development and testing of a method that allows injection of tracer gases into streams and rivers at a constant rate even if the temperature of the air or water is changing over time. The new method allows accurate estimation of gas transfer velocities from injected tracer gases at times and places with significant temporal variation in temperature. Key Points: Steady tracer gas injections are regularly used to measure the gas exchange velocity (v) between streams and the overlying airTemperature variation affects tracer gas solubility, which can lead to unsteady gas injection rate and error in measured vA zero‐headspace tracer solution method was field tested and is proposed to measure v in the presence of large temperature variation [ABSTRACT FROM AUTHOR]

Foamed materials play an important role in a lightweight design. Foam injection molding (FIM) is an advanced and convenient way to fabricate lightweight structural materials. Recently, a new foam injection molding machine is developed, which only needs ultra‐low gas pressure to fabricate microcellular foam. As a universal plastic, polypropylene (PP) is widely used due to its good mechanical properties. But after foaming, the toughness of the PP tends to decrease. Herein, a lightweight and high‐impact polypropylene foam is fabricated via the new FIM technology with an ultra‐low nitrogen pressure of 6.5 MPa. PP/polyolefin elastomer (POE) foam with a tiny cell size of 4.13 µm and high cell density of 2.7 × 109 cm−3 is successfully obtained. Owing to the superior cellular structure, compared with the pure PP foam, after adding the POE component, the maximum impact performance is increased by 465%. In this work, an easy‐to‐industrialized method for preparing lightweight and high‐impact injection‐molded PP foams are presented. [ABSTRACT FROM AUTHOR]

The gas lift in the offshore M field will be performed with high CO2‐content associated gas, but the change of wellbore temperature and pressure during the injection process will lead to the change of phase and physical parameters of associated gas, which has a great impact on the design of gas lift. To ensure the smooth implementation of gas lift in the offshore M field, this paper conducts a study on the physical parameters of associated gas considering the change of CO2 phase state. We obtained the density, viscosity, compression factor, constant pressure specific heat capacity, thermal conductivity, and Joule Thomson coefficient at each temperature and pressure by Hysys calculation, and regression analysis to obtain the regression model of the physical parameters; finally, the regression model was compared with the flash experiment and Hysys calculation results. The results show that the CO2 phase change has a large influence on the physical parameters; R2 > 0.8, which indicates that the regression model has sufficient reliability; the results of the comparison show that the empirical formulas of all physical properties have sufficient accuracy and superiority except Joule–Thomson coefficients. In addition, the empirical formula of the Joule–Thomson coefficient also has good accuracy and superiority at the pressure not exceeding 22 MPa. The study of phase changes and physical parameters of associated gas with high CO2 content provides a basis for subsequent gas lift design in the offshore M field and multiphase flow calculations in the wellbore during the gas lift. Although this study is only applicable to this sample, it also provides a feasible research method for other samples. [ABSTRACT FROM AUTHOR]

BACKGROUND: The ozonation of grains in a closed system at low pressure is a strategy with the potential for treating packaged products. Research is necessary to characterize the reaction kinetics of ozone in this type of injection system so that it is possible to design chambers and determine the ozone concentrations suitable for commercial-scale applications. The objective of this study was therefore to characterize the low-pressure ozone injection system in relation to the physical properties of the grains and determine possible changes in their quality. Samples (5 kg each) of common beans, cowpea beans, corn, popcorn kernels, paddy rice, and polished rice were exposed to ozone in a 70 L hypobaric chamber. Initially, the internal pressure of the chamber was reduced to 500 hPa. Then, ozone was injected at a concentration of 32.10 g m-3 at a volumetric flow rate of 1 L min-1 until reaching a pressure of 1000 hPa. To relate the decomposition of ozone to the grains that were being evaluated, different physical properties were determined, and quality analysis was conducted. RESULTS: Ozone gas half-life outside and inside the package depended on the grain type. Ozone decomposition was quickest in polished rice and slowest in common beans. The half-life of the different grains ranged from 17.8 to 52.9 and 16.4 to 52.9 min, outside and inside the package, respectively. Considering the physical properties, specific surface (Ss), surface area (SA), and sphericity (φ) exhibited a significant correlation with the decomposition rate constant (k) of ozone. However, the variables volume (V), permeability (K), porosity (ε), and specific mass (ρ) showed no correlation with k. CONCLUSION: The physical properties of grain influenced the reaction kinetics of ozone gas during the low-pressure injection process. Ozone gas injection at low pressures did not alter the quality attributes of the grains under study. [ABSTRACT FROM AUTHOR]

We present a detailed multi‐level investigation of steady‐state three‐phase flow processes in a water‐wet Berea sandstone sample. We use high‐resolution micro‐computed tomography images acquired during micro‐scale core‐flooding experiments which include successive gas injection, waterflooding, and nonspreading oil flooding steps. We develop and employ robust techniques to comprehensively characterize and probe the complex interrelationships between the pore‐scale three‐phase capillary pressures, fluid occupancy, displacement events, and the macroscopic flow behavior. The results demonstrate that the local capillary pressures involving the invading phase rise or drop in compliance with the changes in the macroscopic flow ratios. For instance, the gas‐oil capillary pressures were at their highest levels during the gas injection process (highest gas/oil fractional flow) and dropped during the subsequent processes. More importantly, the oil‐water capillary pressure is found to sharply rise during the gas injection process, implying that the gas‐displacing‐oil‐displacing‐water double displacements are the dominant double displacement mechanism during this experiment. For the waterflooding test, the local gas‐oil capillary pressures consistently decrease due to water‐displacing‐oil‐displacing‐gas double displacement events. Moreover, the results show that the variations in the gas‐liquid capillary pressures are more significant than those in the oil‐water capillary pressures. Also, the variations in all capillary pressures during gas injection are higher than in the subsequent processes. The higher variations in capillary pressure values are attributed to more localized and less uniform pore‐scale events across the medium. Finally, the capillary pressure gradients along the flow direction are incorporated in the three‐phase relative permeability measurements. Key Points: Three‐phase in‐situ capillary pressures and their variations in response to various flooding processes are investigatedThe interrelationships between pore‐scale capillary pressures, displacement mechanisms, and fluid occupancy are studiedCapillary pressure gradients are incorporated in the three‐phase relative permeability measurements [ABSTRACT FROM AUTHOR]

This paper reports an experimental study on the changes in the equivalent diameter and sphericity of flying molten slag particles in terms of heating temperature and nitrogen injection pressure. A high‐speed camera is used to continuously take images of the flying molten particles. Then the images are analyzed by mathematical image processing. With increasing heating temperature, the lower the viscosity, the stronger the fluidity, and the easier it is to be granulated into small particles under the spray of nitrogen. The results show that the equivalent diameter and sphericity of the particles with equivalent diameters remain the same during the flight. During the granulation of the particles, however, rod‐shaped particles gradually change to spherical ones, and the sphericity keeps increasing until it reaches a level. The average flying speed of the studied slag particles at the temperatures of 1400, 1450, 1475, 1500, and 1510°C is 4.0, 4.3, 4.5, 4.3, and 4.2 m/s, respectively. In addition, the higher the temperature, the longer the flight distance of the particles. By changing the gas injection pressure to 0.2, 0.3, 0.4, and 0.5 MPa, the average flying speeds of the studied slag particles are 2.8, 3.7, 5.5, and 8.4 m/s, respectively. This result proves that the higher the injection pressure, the greater the average flying speed of the particles. [ABSTRACT FROM AUTHOR]

Gas‐viscous liquid bubbly and slug flow are very common in petroleum, chemical, bioengineering, polymer, and food processing. However, there is a major knowledge gap in two‐phase flow research in the design of gas injectors/distributers in very high viscosity oil systems. The present study investigates the effect of gas injection methods in columns containing very high viscosity oils (i.e., realistic liquids), and more specifically using 360 Pa · s viscosity oil in a 240‐mm diameter column. The effects that the radial positioning, number of gas nozzles, and their distance from each other have on the structure of the flow in viscous liquids are presented in detail. Electrical capacitance tomography (ECT) is used to extract experimental data. Void fraction, bubble velocity, frequency, liquid film thickness, and bubble length were measured and analyzed at different radial gas injection positions. It has been observed that bubble length increases significantly by 0.3 m when the injection nozzle is located next to the wall of the pipe. Bubble velocity and length also increase by 0.217 m/s and 3.6 m, respectively, with increasing gas flowrate when multiple injection points are used. Increasing the distance between the gas injection points increased bubbles' length by 1.2 m. Bubbles' velocity and frequency (at higher gas flow rate) were also increased. [ABSTRACT FROM AUTHOR]

A novel creep testing machine was designed to test austenitic steel foil AISI 347 under the elevated temperature of 700°C. The creep test was repeated in five stress levels from low‐stress 55 MPa to severe applied stress 220 MPa for 0.25 mm thickness samples. The machine was equipped with a shield inert gas injection system, and tests were repeated in a nonoxidative area. The creep rupture behavior of the foil is well represented using the modified three‐parameter Theta Projection Concept model. Each model parameter is best represented as a function of the applied stress. Comparison between the results of creep life in different mediums shows that the oxidation effect was the dominant phenomenon in the creep process. Moreover, avoiding oxidation affects the steady‐state stage growth, and afterward, the creep life was increased by more than 40%. Post analyses of ruptured creep samples compare the creep cavitation at triple grain boundaries in a different environment. Highlights: Novel testing machine and method to measure the creep deformation of metal foils.Creep behavior of AISI 347 steel foil under various stresses at laboratory air and in argon environments.The use of shielding inert gas and its capability to protect the foil surfaces from oxidation.Stablish relationship between the creep life and axial creep conditions using modified theta projection concept. [ABSTRACT FROM AUTHOR]

Following the Hunga Tonga eruption (20.6°S, 175.4°W, mid‐January 2022), we present a balloon‐borne characterization of the stratospheric aerosol plume one week after its injection (on 23 and 26 January 2022, La Réunion island at 21.1°S, 55.3°E). Satellite observations show that flight (a) took place during the overpass of a denser plume of sulfate aerosols (SA) compared to a more diluted plume during flight. (b) Observations show that the sampled plumes (at around 22, 25 and 19 km altitude, respectively) consist exclusively of very small particles (with radius <1 µm). Particles with radii between 0.5 and 1.0 µm show optically transparent features pointing to predominant SA. Particles with radii below 0.5 µm are partly absorbing, which could point to small sulfate coated ash particles, a feature not identified with space‐borne observations. This shows that in situ observations are necessary to fully characterize the microphysical properties of the plumes tracked by space‐borne instruments. Plain Language Summary: The Hunga Tonga‐Hunga Ha'apai volcano (at 20.6°S, 175.4°W) erupted on 13 and 15 January 2022 with injection of gases and aerosols up to 55 km altitude. Here, we present a study based on in situ aerosol observations on weather balloons on La Réunion (21.1°S, 55.3°E) within the injected Hunga Tonga aerosol plume one week after the eruption (23 and 26 January 2022). With respective satellite observations, we show that the first measurement flight took place during the overpass of a denser aerosol plume compared to the second flight. We find that the plume exhibits only small particles <1 μm, mainly consisting of sulfate aerosols (for particles between 0.5 and 1 μm in size) and an absorbing component for very small particles (<0.5 μm), possibly pointing to small ash particles coated by sulfur. This letter "absorbing" feature is a unique contribution brought by in situ measurements that fills a gap left by space‐borne instruments. Key Points: Predominant particle size range of <1 μm within the stratospheric aerosol plume of the Hunga Tonga eruptionOptically absorbing particles within the plume for particles <0.5 μm point to fractured, very small ash particlesMostly optically semi‐transparent particles, for particle sizes between 0.5 and 1.0 μm result from small sulfur coated ash particles [ABSTRACT FROM AUTHOR]

A mathematical model based on the Eulerian–Eulerian–Lagrangian method is developed to investigate the two‐phase flow, temperature distribution, and inclusion transport, considering the effect of argon gas injection (AGI) and mold electromagnetic stirring (M‐EMS) in the bloom mold. The magnetic resistance force is adopted to account for the effect of the magnetic field on bubbles. It is demonstrated in the results that when AGI is applied, plumes form near the submerged entry nozzle (SEN) and increase the velocity in the upper part of the mold. While M‐EMS is applied, the swirl flow significantly increases the overall flow velocity and superheat dissipation. In addition, AGI and M‐EMS increase the fluctuation and temperature of the free surface, lower the peak heat flow, and promote inclusions removal. When AGI is applied with M‐EMS, the swirl flow and plumes in the upper part of the mold are weakened due to the interaction between them, and the level fluctuation is lower than that of applying AGI or M‐EMS separately. The heat flow and free surface temperature are more uniform, and the inclusion removal rate further increases. Meanwhile, M‐EMS drives bubble columns to the location between the two ports of SEN and gathers bubbles around the SEN. [ABSTRACT FROM AUTHOR]

Excessive water production from natural reservoirs is a major challenge in oil and gas industry. Relative permeability modifiers (RPM) are used to selectively reduce water production with minimum effect on the hydrocarbon production. This work examined the performance of polyacrylamide in terms of its water control efficiency at prolonged water‐gas flowing cycles. During each cycle, as the volume of injected water increased, the RPM demonstrated stronger performance in terms of reducing water permeability. This is attributed to the swelling of polymer layer adsorbed to the pore surfaces. Conversely, during each cycle, higher volume of gas injection led to less reduction in the gas effective permeability (PRg) which is due to polymer shrinkage. The reduction in water absolute permeability (PRw) of the treated micromodel in each injection cycle was significantly greater than the reduction in gas permeability. Interestingly, as water‐gas cycles progressed, a significant increase in water permeability reduction was observed. It is also found that polymer expansion and shrinkage are reversible. As such, the RPM performance depends on the injected fluid, injected fluid volumes and water‐gas injecting cycling. We thus conclude that that polymer swelling, and shrinkage and polymer‐gas interaction play a vital role in RPM performance. [ABSTRACT FROM AUTHOR]

This study is in line with two previous studies by the same authors on gas injection in yield stress fluids. Gas is injected toward the bottom wall of a prismatic tank containing a yield stress fluid. When rising toward the free surface, trains of bubbles generate fluid recirculation in the tank. Two experimental colorimetric methods are introduced and validated in order to quantify the recirculation liquid flow rate as well as the time evolution of the extent and shape of the mixed volume. The influences of the injection flow rate, fluid rheology, and reactor size have been quantified. Correlations based on the characteristic nondimensional numbers of the flow have been developed to predict the downward liquid flow rate as well as the mixed volume. A model for estimating the mixing time is also developed and compared to experimental results. [ABSTRACT FROM AUTHOR]

The export of grapes from one country to another is dependent on the grape's quality that should pass the strict phytosanitary requirements of the importing country. There is a requirement of fumigation of grapes with CO2 and SO2 at specified concentrations for a certain period besides the other pack‐house protocols and export standards. This study was focused to develop and establish an electronically controlled model fumigation chamber for the treatment of grapes in the grapes‐producing region. The gas injection and evacuation systems are electronically operated, and the fumigant concentration can be varied according to the requirement. Heaters of 2 kW are fitted inside the chamber to maintain the treatment temperature above 16°C for grapes fumigation. The fumigation chamber was found leak‐proof during pressurized helium leak testing. The CO2 and SO2 gas concentrations can be maintained between 600 and 60,000 ± 100 ppmv and 10 and 10,000 ± 2 ppmv, respectively, for 1–90 min (1% is equivalent to 10,000 ppmv). The fumigation of grapes with 6% CO2 for 30 min followed by fumigation with 1% SO2 for 30 min ensured 100% mortality of the adult fruit fly (Drosophilla melanogaster). This chamber may also be used for the fumigation treatment of other fruits, vegetables, nuts, and so on, as per the time and concentration of gases required for the 100% mortality of target pest. Nevertheless, the protocol for such treatments should be developed for other fruits, and the effect of the gases on the quality of the products should be studied. Practical Applications: The developed automated fumigation chamber for treatment of grapes with CO2 and SO2 is an effective measure for disinfesting the grapes from invasive pests like Drosophilla suzukii, spiders, and so on. This would help in overcoming phytosanitary measures put in place by many grapes importing countries like New Zealand, Australia, and so on. These countries offer huge market potential for export of Indian grapes, and if the trade barriers are overcome, it would lead to earning huge foreign exchange. Furthermore, the developed automated fumigation chamber can be used as an integral part of horticultural pack houses both for domestic as well as international trade as it would eliminate most of the adult field pests at preliminary stages before pack‐house operation. [ABSTRACT FROM AUTHOR]

Ordering the bubbles of closed‐cell aluminum foams can contribute to decorative esthetics and create directional mechanical properties that disordered foams do not have. High‐porosity (>80%) aluminum foams prepared by the traditional static gas injection method usually have large and polyhedral cells, which do not form an ordered stacking. Aluminum foams with relatively uniform and small cells (cell size ≈1.2 mm) have been recently obtained by gas injection through a nozzle rotating at high speed. Herein, the stacking of aluminum foams with different cell sizes and a monodisperse aqueous foam are characterized by X‐ray tomography and compared with an ideal face‐centered cubic (FCC) structure. The aluminum foam featuring the smallest cells has a concentrated distribution of cell coordination number with a peak of 12 and the first peaks of the radial distribution function are found to be consistent with those of the monodisperse aqueous foam and an ideal FCC structure. Furthermore, many aligned bubble chains with more than five bubbles are observed on cross‐sectional images. Therefore, aluminum foam can become short‐range ordered whenever the cell size is uniform enough and reduced to around 1.2 mm. Methods for further improving the order of aluminum foam are discussed. [ABSTRACT FROM AUTHOR]

Mitigating the hazard of fault reactivation during CO2$_2$ injection and oil production is important for ensuring environmental sustainability of geologic carbon sequestration and hydrocarbon recovery. Currently, we do not know how the Coulomb Failure Stress (CFS), which is a commonly used metric to assess the potential of inducing slip on a fault, evolves differently for gas injection and oil production scenarios. Using high‐resolution simulations of CO2$_2$ injection‐induced and oil production‐induced fault slip and theories of Coulomb failure and poroelasticity, we address this gap in knowledge. We analyze the fault tractions, slip, and reservoir pressure to understand how a fault is destabilized in successive steps, how hypocenter locations are selected, and how these processes differ between injection and production. We extract and summarize the characteristic features of induced fault activation in terms of the dependence of CFS and the Fault Stress Ratio (FSR) on the dimensionless reservoir pressure perturbation caused by injection or production. We apply the framework to the Farnsworth oilfield in Texas, which is undergoing CO2$_2$ injection and oil production, to disambiguate observations related to fault stability. Finally, we discuss how our framework can inform models that aim to forecast fluid flow‐induced slip and mitigate the induced seismicity hazard in oilfields and gas storage sites. [ABSTRACT FROM AUTHOR]

Summary: Baker's yeast produces carbon dioxide during dough fermentation, which gives bakery foods with expanded volume. This review covers gas sources other than baker's yeast according to information disclosed in patents and supported by scientific literature. Inventors had more interest in gas injection in dough, mainly carbon dioxide, than gas‐releasing agents available in chemical leavening, so‐called baking powder, with 58 and 43 patented inventions, respectively. For chemical leavening, 20 gas‐releasing agents were proposed, including 11 patented and 9 non‐patented agents like sodium bicarbonate, the most popular. Other gas‐releasing agents included miscellaneous salts of carbonate and bicarbonate (ammonium; calcium; magnesium; potassium) as well as compounds like hydrogen peroxide and, more recently, glutamic acid. Coatings were patented to protect sodium bicarbonate towards moisture and delay its action in dough. Recent trends include aerosol dough and flavourful sodium‐free gas‐releasing agents. [ABSTRACT FROM AUTHOR]

Mixing by gas injection is an operation used in industrial processes such as wastewater treatment, metallurgy, or methanization in which pressurized gas is injected into a fluid in order to reduce concentrations and temperatures gradients. This study demonstrates how the CFD toolbox OpenFOAM can be used to simulate such flows. Experimental measurements and observations have been performed on a pilot‐scale reactor where pressurized air is injected in a yield stress fluid. The volume of fluid method and an adaptive mesh with refinement at the interface have been used to track the gas inclusions. The numerical model accuracy has been assessed by comparing experimental and numerical results related to the bubble's frequency, dimensions, and rising velocities as well as the fluid recirculation, yielded, and unyielded regions in the tank. The influence of injection parameters such as the injection flow rate and the fluid rheological parameters has been quantified. [ABSTRACT FROM AUTHOR]

In marine fossil energy production, annular pressure buildup (APB) caused by temperature increase is a widely concerned problem and needs to be solved urgently in subsea wells. To study and predict APB and avoid consequent safety accidents and economic losses, a novel model is proposed to predict APB considering the effect of cement. The model has a wider application range by considering the dynamic change of thermal properties and mass change of the annular fluid. Laboratory experiments were conducted to verify the accuracy of the proposed model. Then a case study and mitigation evaluation were conducted to make the further analysis. Research results show that cement has a significant effect on APB, ignoring the cement may bring potential danger. The height of cement affects APB differently when the top of cement (TOC) is above and below the previous casing shoes. Making the TOC below the previous casing shoe could provide a leakage surface for annular fluid. It is an effective method for APB mitigation but a balance needs to be struck between wellbore integrity and mitigation effect. Gas or foam injection is another effective method to mitigate APB. The necessary gas volume varies with the annular pressure and initial gas pressure and needs to be determined according to the actual condition, especially in deepwater wells. [ABSTRACT FROM AUTHOR]

Summary: The aim of this study was to review general trends in the patent literature on baker's yeast substitutes, including chemical leavening and gas injection. Overall, 494 unique inventions were described in patents filed over about 200 years, between 1833 and 2019. About two‐thirds of patented inventions targeted acid‐reacting materials, and the rest was on non‐specific protection of active ingredients (13%), gas injection such as in the aerated bread process (12%), gas‐releasing agents like sodium bicarbonate (9%) and miscellaneous dough improvers, including flavouring agents and nutrients (4%). Drawbacks included off‐taste and potentially non‐healthy residues such as aluminium. Most baker's yeast substitutes were dry chemical preparations, so‐called baking powders, that mainly allowed easy and cheap production of miscellaneous fat‐ and sugar‐rich foods such as cakes, and probably contributed to the popularity of the latter. Applications included ready‐to‐use dry bakery mixes and refrigerated doughs. Yeast substitutes were originally developed for bread in England and perfected later for fat‐rich bakery foods, mainly in the United States. where inventors owned 59% of total patents. Specific aspects of baker's yeast substitutes will be fully covered in companion articles. [ABSTRACT FROM AUTHOR]

Subcooling is the process of bringing down the temperature of liquids lower than that of the boiling point of the corresponding vapor pressure. The performance of subcooling of cryogenic liquids mainly depends on the heat-inleak of the system, the helium injection mass flow rate, helium injection temperature, and helium injection nozzle pattern. This paper presents an alternative method, by making use of the least heat in the leakage of the liquid hydrogen storage container, which is quite possible because containers with excellent thermal insulation are commercially available nowadays. The process involved is rapid evacuation through gas ejectors, thus reducing the effect of temperature. The advantage and the process of evacuation leading to subcooling in a unique manner are the objective of this article. The experimental results are discussed in comparison with the thermophysical process involved in the subcooling operation. A comparative study is also carried out with the theoretical heat exchange process in which helium is used as a medium for the economy of the stated process. It is stated that the current process of subcooling through evacuation is superior to the conventional heat exchange process. [ABSTRACT FROM AUTHOR]

Microcapillary films (MCFs) are microextrusion‐processed plastic films containing an array of parallel microcapillaries, and have been widely utilized as microfluidic platforms. However, the nonuniform size distribution within a single MCF strip limits the application of MCFs in monodisperse droplet generation. In this paper, the mechanisms that lead to uneven microcapillary dimensions in conventional MCFs whose gas pressures in all channels are the same is first clarified. The effect of gas pressure in a single channel on the microcapillary dimensions in the film is then studied. Finally, the size uniformity of the microcapillaries is improved by separate gas injection in different channels, providing new possibilities for the generation of highly monodisperse microdroplets. [ABSTRACT FROM AUTHOR]

In acid gas injection, the solubility and residual trapping of acid gas can be effectively improved by optimizing the acid gas injection, which is important for short‐term storage of acid gas and reducing the risk of acid gas leakage. The current study numerically investigates three different acid gas injection schemes, namely continuous acid gas injection, intermittent acid gas injection, and water alternating gas injection. The results suggest that the continuous acid gas injection with higher injection rate is slightly conducive to the solubility and residual trapping of acid gas. In particular, Continuous injection‐Case1 with a rate of 19 200 Nm3 d−1 reduces mobile acid gas by 1.82% and enhances residual trapping by 1.25%. While the intermittent acid gas injection can hardly improve the solubility and residual trapping of acid gas. Water alternating gas injection scheme shows superior behavior over other schemes. Specially, the Water alternating gas injection‐Case3 with higher water injection rate is the most effective, which can reduce mobile acid gas by 13.66% and enhance solubility trapping by 23.95%. The acid gas plume is funnel‐shaped in the acid gas injection stage. However, in the subsequent water injection stage, the acid gas plume gradually becomes fan shaped. This is because the injected water accelerates the dissolution of the acid gas, causing almost all the rear of the acid gas plume to dissolve in the water. Thus, we conclude that water alternating gas injection scheme can significantly enhance the acid gas trapping and Water alternating gas injection Case 3 is the preferred injection scheme. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Antimony triselenide (Sb2Se3) nanoflake‐based nitrogen dioxide (NO2) sensors exhibit a progressive bifunctional gas‐sensing performance, with a rapid alarm for hazardous highly concentrated gases, and an advanced memory‐type function for low‐concentration (<1 ppm) monitoring repeated under potentially fatal exposure. Rectangular and cuboid shaped Sb2Se3 nanoflakes, comprising van der Waals planes with large surface areas and covalent bond planes with small areas, can rapidly detect a wide range of NO2 gas concentrations from 0.1 to 100 ppm. These Sb2Se3 nanoflakes are found to be suitable for physisorption‐based gas sensing owing to their anisotropic quasi‐2D crystal structure with extremely enlarged van der Waals planes, where they are humidity‐insensitive and consequently exhibit an extremely stable baseline current. The Sb2Se3 nanoflake sensor exhibits a room‐temperature/low‐voltage operation, which is noticeable owing to its low energy consumption and rapid response even under a NO2 gas flow of only 1 ppm. As a result, the Sb2Se3 nanoflake sensor is suitable for the development of a rapid alarm system. Furthermore, the persistent gas‐sensing conductivity of the sensor with a slow decaying current can enable the development of a progressive memory‐type sensor that retains the previous signal under irregular gas injection at low concentrations. [ABSTRACT FROM AUTHOR]

Gas‐assisted injection molding is a polymer processing technology in which a penetrating gas bubble hollows out a plastic part as it cools and solidifies within a mold. In this study, non‐isothermal gas injection experiments at high capillary number illustrate the effects of delay time in gas injection, tube diameter, capillary number, and temperature‐sensitive fluid viscosity and flow activation energy on coating thickness. Experiments with polybutene H‐300 and Dow Corning silicon oil (DC‐200) in stainless steel tubing (1.27 and 0.635 cm) demonstrated fractional coverage increasing from 0.6 to a maximum in the range of 0.63–0.83 at short delay times, then decaying toward 0.6 at long delay times upon approaching the cooled isothermal state. Further analysis is drawn from simulations based on a simple theoretical model incorporating one‐dimensional heat transfer with convection at the outer surface of the mold, non‐isothermal behavior of the viscous fluid, and radial velocity profiles in the one‐phase fluid flow region. Quantitative agreement is found between experimental and simulated results. Two‐dimensional modeling and simulation methods extend the prior results to illustrate transient axial and radial heat transfer as well as flow behavior with respect to the penetrating gas bubble within the fluid flow region. [ABSTRACT FROM AUTHOR]

We develop novel locally defined diagnostics for the efficiency of the ocean's biological pump by tracing carbon throughout its lifetime in the ocean from gas injection to outgassing and counting the number of passages through the soft‐tissue and carbonate pumps. These diagnostics reveal that the biological pump's key controls on atmospheric pCO2 are the mean number of lifetime pump passages per dissolved inorganic carbon (DIC) molecule at the surface and the mean aphotic sequestration time of regenerated DIC. We apply our diagnostics to an observationally constrained carbon‐cycle model that features spatially varying stoichiometric ratios and is embedded in a data‐assimilated global ocean circulation. We find that for the present‐day ocean an average of 44 ± 4% of DIC in a given water parcel makes at least one lifetime passage through the soft tissue pump, and about 4% makes at least one passage through the carbonate pump. The global mean number of lifetime pump passages per molecule, including the fraction with zero passages, is N¯soft=0.65±0.08 and N¯carb∼0.04 for the soft‐tissue and carbonate pumps. Using idealized perturbations to sweep out a sequence of states ranging from zero biological activity (pCO2atm=493±1 ppmv) to complete surface nutrient depletion (pCO2atm=207±1 ppmv), we find that fractional changes in pCO2atm are dominated by fractional changes in the number of soft‐tissue pump passages. At complete surface nutrient depletion, the mean fraction of DIC that has at least one lifetime passage through the soft‐tissue pump increases to 69 ± 5% with N¯soft=1.6±0.3. Plain Language Summary: Tiny plants floating near the ocean surface use sunlight to convert nutrients and dissolved CO2 into organic matter. A fraction of this organic matter sinks, transferring carbon from the surface to the deep ocean, a process known as the biological pump. The biological pump reduces atmospheric CO2 and is thus important for moderating climate. The organic matter is oxidized by microbes, which regenerates inorganic carbon that can then pass through the biological pump again or return to the atmosphere. Here, we calculate, for the first time, the number of passages through the biological pump that a typical carbon molecule makes during its lifetime in the ocean. This carbon‐based measure of pump efficiency is useful for quantifying the biological pump's control on atmospheric CO2. We find that in the current state of the ocean 44 ± 4% of the dissolved inorganic carbon makes at least one lifetime passage through the biological pump, with a mean number of 0.65 ± 0.08 passages per molecule. In numerical experiments that stimulate the biological pump to utilize all available nutrients, the fraction with at least one passage increases to 69 ± 5% with 1.6 ± 0.3 passages per molecule, which draws down atmospheric CO2 by about 70 ppmv. Key Points: The mean number of passages through the biological pump per carbon molecule is a natural metric of pump efficiencyGlobally averaged 44 ± 4% of the dissolved carbon in a given water parcel is biologically pumped with 0.65 ± 0.08 lifetime passages per moleculeChanges in atmospheric CO2 are related to changes in the mean number of pump passages and the mean injection‐tagged sequestration time [ABSTRACT FROM AUTHOR]

To tackle the problem that wells that are deployed in a specific pattern based on the requirements of gas reservoir development are not suitable for gas storage, we have conducted concentrically circular injection and production simulation experiments for gas storage, discovered the existence of a threshold radius, denoted by Rt, and derived the expression for Rt. Based on the analysis and discussion results, we propose a strategy for deploying gas storage wells in specific patterns. The expression for Rt shows that it is affected by factors such as the gas storage gas production/injection time, the upper pressure limit, the lower pressure limit, the bottomhole flow pressure at the ends of injection and production, the and permeability. The analysis and discussion results show that the Rt of a gas storage facility is much smaller than the Rt for gas reservoir development. In the gas storage facilities in China, the Rt for gas production is less than the Rt for the gas injection, and Rt increases with the difference in the operating pressure and with permeability K. Based on the characteristics of Rt, we propose three suggestions for gas storage well pattern deployment: (1) calculate Rt according to the designed functions of the gas storage facility and deploy the well pattern according to Rt; (2) deploy sparser, large‐wellbore patterns in high‐permeability areas and denser, small‐wellbore patterns in high‐permeability areas; and (3) achieve the gas injection well pattern by new drilling, and the gas production well pattern through a combination of the gas injection well pattern and old wells. By assessing a gas storage facility with a perfect well pattern after a number of adjustments, we found that the Rt of the 12 wells calculated in this paper is basically close to the corresponding actual radius, which validates our method. The results of this study provide a methodological basis for well pattern deployment in new gas storage construction. [ABSTRACT FROM AUTHOR]

A mathematical model of the COREX process with a top gas recycling technology is developed based on mass and heat balances. Herein, the influence of top gas recycling on the operation parameters of the COREX process is investigated. The results show that the theoretical combustion temperature is significantly affected by gas injection, and the theoretical combustion temperature can be reduced by 116.11 and 72.94 °C, respectively, by injecting the gas without CO2 removal and the gas after CO2 removal. Also, injecting the gas without CO2 removal obviously reduces the dome temperature, but injecting the gas after CO2 removal has no obvious effect on the dome temperature. The fuel rate and integrated fuel rate can be reduced by injecting the two kinds of gas, and the fuel rate can be reduced by 2.84 and 2.86 kg t−1, respectively, by injecting the gas without CO2 removal and the gas after CO2 removal, but the decrease in the integrated fuel rate by injecting the gas after CO2 removal is relatively small, only 0.31 kg t−1. [ABSTRACT FROM AUTHOR]

The historical literature on the treatment of rhegmatogenous retinal detachment (RRD) was reviewed from 1911 to the present, focusing on the role of intravitreal air and gas. The history of the pneumatic retinopexy (PnR) technique is described from its original roots to the current day procedure. The treatment of RRD has evolved tremendously over the past century. The introduction of intravitreal gas as a tamponade to reattach the retina was critical in the development of modern day PnR. Although PnR is not a new technique, relatively recent randomized trials have demonstrated the numerous advantages of this procedure compared to pars plana vitrectomy (PPV) and scleral buckle. From a historical perspective, PnR has its origin in 1911 when Ohm performed intravitreal air injection after external subretinal fluid drainage in an attempt to treat RRD. The evolution of the procedure was driven by the introduction and experience with inert expansile intravitreal gas injections, and several great surgeons made critical contributions to the development of the procedure. There is substantial controversy pertaining to the original description of PnR in the literature. Credit has generally been given to Hilton and Grizzard from the United States, although Alfredo Dominguez from Spain published the first description of the procedure and he went to great lengths in an attempt to be rightfully recognized for this. The first randomized trial in retinal detachment repair was led by Dr. Paul Tornambe, comparing PnR to scleral buckle and an additional randomized trial was subsequently carried out demonstrating functional advantages of PnR compared to PPV. [ABSTRACT FROM AUTHOR]

Electroreduction carbon dioxide into formate has been regarded as a hopeful measure to relieve global warming. Copper‐based hollow fibers demonstrated good performances on converting carbon dioxide in previous researches. Herein Cu−Sn alloy hollow fibers were synthesized in an innovative way, combining the structure advantages of hollow fiber and high selectivity towards formate on η′ bronze. Tests under different gas injection conditions were conducted to analyze the contribution of the hollow fiber structure on suppression of hydrogen evolution and promotion on kinetics. Strikingly, Cu−Sn45 % hollow fiber, the optimal catalyst in this work, achieved a highest faradaic efficiency towards formate of 90.96 % at a lower potential of −0.75 V vs. RHE than most non‐noble catalysts, and the FE of H2 was below 4 %. [ABSTRACT FROM AUTHOR]

The dynamic operation of a power‐to‐gas plant powered by wind energy is theoretically studied by coupling an empirical model of an alkaline water electrolyzer with a 1D heterogeneous model of a methanation reactor. H2 produced by the electrolyzer follows the wind power profile, but operation in the part‐load range can raise safety concerns. The dynamically generated methane quality comes close to the required value for injection into the gas grid, if the stoichiometric ratio is controlled. To satisfy the gas quality at all times, it is necessary to design a more tolerant reactor. [ABSTRACT FROM AUTHOR]

Hydraulic methods have been extensively employed to improve the production rate of commercially viable coalbed methane and prevent potential mining disasters resulting from the production of this methane by increasing the permeability of coal seams. In this paper, an experimental system with a stirrer was utilized to study the effects of water injection on the gas desorption characteristics of coal seams. Pressure‐released desorption values and total gas desorption values under conditions of different adsorption equilibrium pressures and water contents were determined. The results show that both the free gas and the adsorbed gas could be replaced by the injected water, causing the system pressure to increase significantly. When releasing the system pressure, the gas desorption value of the water‐injected coal sample was reduced. After water injection, the total desorption value of the coal was increased. Thus, water injection could help to promote coal gas desorption. [ABSTRACT FROM AUTHOR]

For more than three decades, the depleted Rongchang gas reservoir in China's Sichuan Basin was used for the disposal of unwanted water, which resulted in induced earthquakes, with magnitudes as high as 5.2. After all wells were closed, the frequency of seismic activity was observed to decay following a modified Omori law, and since April 2015, seismic activity again began to increase, and a M4.9 earthquake occurred on 27 December. The results of an epidemic‐type aftershock sequence (ETAS) model analysis show that forced seismicity accounted for more than 70% of the total events. For most M ≥ 3.5 earthquakes, including two M ≥ 4 events, the estimated overpressure was lower than the maximum injection pressure. These results, coupled with the fact that postinjection seismic activity has similar characteristics to seismicity during injection, indicate that the injected overpressure fluid was still the driving factor for postinjection seismic activity. Plain Language Summary: Prior to 2013, unwanted water was intermittently pumped into the depleted Rongchang gas reservoir at a depth of 3 km for approximately three decades, inducing many earthquakes with a magnitude up to 5.2. Although all nearby injection wells were closed in 2013, the seismicity in the area has remained relatively high. At this location, M4.9 and M4.0 earthquakes occurred in December 2016. In order to assess the situation, we carried out an integrated study focused on the area's seismicity before and after the injections ceased. The results, including the overpressure required for major earthquakes and various statistical features, suggest that the postinjection seismicity, which was the same as that during injection, was caused by the delayed rupture of preexisting faults within the reservoir and its surrounding faults. Therefore, at an injection site, at which significant injection‐induced earthquakes occurred during injections, there is still a high probability of continuous occurrence of relatively large earthquakes after injection ends. Key Points: Long‐term injection for wastewater disposal into the depleted Rongchang gas reservoir induced earthquakes with magnitudes as large as 5.2After shutting down of injection, seismicity decayed following a modified Omori law with some major eventsPostinjection seismicity demonstrates features similar to that during injection except for a change in event rate [ABSTRACT FROM AUTHOR]

To effectively prevent and control the spontaneous combustion of residual coal at the bottom of a large fully mechanized gob space, we proposed a targeted inertization technology based on the injection of power plant flue gas. Based on the real onsite conditions of the gob, the three‐dimensional distributions of the overburden fractures, gas emission, and residual coal were added to the multiphysics coupled model of spontaneous coal combustion. The simulation method based on moving coordinates was used to complete the risk evaluation and the locating of the spontaneous combustion in the fully mechanized gob, and the key control factors of the inerted zone and the fire prevention effect of the flue gas injection were analyzed. The results showed that the mismatch between the inerted zone and the spontaneous combustion risk zone was the root cause of the poor fire prevention effect of the inert gas injection. Because the density of the flue gas was greater than that of the leaked air, the flue gas mainly migrated and diffused in the lower part of the gob. At a distance of 100 m from the working face, the flue gas with 3%‐9% oxygen content injected at a rate of 2000 m3/h completely covered the high‐temperature residual coal. This caused the maximum temperature (Tmax) to drop from 334.2 K upon nitrogen injection to below 310 K. Additionally, the effect of the oxygen content fluctuation on Tmax was controlled within 2.6 K. The methods and the results in this study can serve as a reference for efficiently preventing and controlling local spontaneous combustion hazards in large spaces for underground coal mining. [ABSTRACT FROM AUTHOR]