Gas Formation Research Articles

The interfacial trapped charge of quintuple-layers Al2O3 induced by point defect

For two-dimensional (2D) polar semiconductors with out-of-plane polarization, as the number of stacked layers increases, the electronic properties could change from single-layer semiconductor to multi-layer metal. The metallic characteristic manifests as the formation of 2D conductive electron and hole gas on the surfaces. In this study, we investigate the mechanism behind the formation of a two-dimensional electron gas (hole gas) on the surface and interlayer directional charge transfer process of polar quintuple-layers (QLs)-Al2O3 through first-principles calculations. The accumulated polarized electric field acts as the thermodynamic driving force for directional charge transfer between QL-Al2O3 layers, involving all Al and O atoms in the charge transfer process. However, the point defects in 2QLs-Al2O3, including different effective charge, significantly influence the dynamic process of directional interlayer charge transfer. The presence of unsaturated oxygen atoms at the interface contributes to the formation of interface trapped charges in 2QLs-Al2O3.

Decompression venous gas formation intensity scale

Relevance. Severe decompression sickness is the most common diving disorder; therefore, its diagnosis and prevention is considered important aspects of hyperbaric physiology and diving medicine. Diver’s susceptibility to gas bubble formation under decompression is most critical for decompression sickness prevention. Doppler bubble detection is the most common procedure to identify divers who are most susceptible to gas bubble formation under decompression; nevertheless, a more comprehensive examination including pulse pressure and 2D visualization of gas bubbles provide valuable advantages.The objective is to provide justify the implementation of the decompression risk and venous gas bubble formation scale.Methods. The study enrolled 42 divers who were examined for tolerance to gas bubble formation under decompression; gas bubbles were visualized using Doppler ultrasound. Next, the developed decompression risk and venous gas bubble formation scale was used to verify its efficiency and practical value.Results and discussion. After hyperbaric exposure, 2D gas bubble visualization data were analyzed showing that 6 subjects (14.3 %) had no decompression-caused gas bubble formation (0 points); 9 subjects (21.4 %) scored up to 5 points, showing a small amount of gas bubbles during exercise; 22 subjects (52.4 %) scored between 6 and 15; whereas the remaining 5 subjects presented with gas bubbles at rest and a sharp increase in bubble formation during mild exercise. The obtained data suggest that the examined diver cohort included 13 subjects (31 %) with very high tolerance to gas bubble formation, 21 divers (50 %) showing average tolerance and 8 highly susceptible subjects (19 %).Conclusion. During decompression, venous gas bubble formation scale has significant diagnostic value providing a tool to measure individual diver’s susceptibility to gas bubble formation. The scale allows to reduce the hyperbaric load by decreasing exposure on the ground at threshold pressure (0.4 MPa) and thus reduce the decompression time, based on sufficient evidence regarding individual susceptibility to gas bubble formation under decompression

On the Effectiveness of Aerosol Extinguishing Agents for Battery Vent Gases and Hydrogen

Abstract It is well known that Lithium-ion batteries in thermal runaway can emit gases with high hydrogen concentrations which, in case of delayed ignition, can cause a gas explosion. Aerosol suppression agents are sometimes used to suppress fires and/or prevent ignition of released gases in such situations. The agent has been studied for suppression of fires (diffusion flames), but less is known about the ability of such aerosols to inert highly reactive gas mixtures. In this paper, a commercially available aerosol suppression agent is mixed with a highly reactive gas mixture representing the gas composition from an NCA battery in thermal runaway as well as with pure hydrogen, and the effect on burning velocity is assessed based on OH-PLIF measurements on a Bunsen-burner type setup. The experiments were complemented by 1D flame simulations using a detailed chemical kinetics scheme including relevant combustible gases and the suppression agent. The results show that, although the agent is highly effective in gaseous form, evaporation of aerosols in the pre-flame-zone is prevented by the lower radiative fraction and results in higher burning velocity of hydrogen-rich mixtures. The local cooling induced by the evaporation of the aerosol in the flame leads to an increased flame area and thereby total burning velocity. This effect is further exaggerated by the preferential diffusion of hydrogen. Therefore, modification of the system is needed before applying for this purpose.

A COMPARATIVE STUDY OF ANTIMICROBIAL SENSITIVITY IN PATIENTS WITH ACUTE PYELONEPHRITIS AND EMPHYSEMATOUS PYELONEPHRITIS

Background: Urinary tract infections (UTIs) commonly affect men and can lead to serious complications such as acute pyelonephritis (APN) and emphysematous pyelonephritis (EPN). APN typically impacts the renal pelvis and parenchyma, often exacerbated by conditions like obesity, diabetes, or immunosuppression. EPN, characterized by gas formation within the renal tissues, is predominantly caused by Escherichia coli and Klebsiella pneumoniae. Objective: This study aims to identify the pathogens responsible for emphysematous pyelonephritis, compare their prevalence with acute pyelonephritis, and evaluate their antimicrobial sensitivity patterns. Methods: A comparative study was conducted over twelve months, from July 2023 to June 2024, involving 145 patients diagnosed with APN and EPN at the Institute of Kidney Disease, Peshawar. Urine samples were collected and cultured to determine the causative microorganisms and assess their antibiotic sensitivities. Data analysis was performed using SPSS 23. Results: Among the patients, 72.4% (n=105) were diagnosed with APN and 27.6% (n=40) with EPN. Escherichia coli was the most common pathogen in both conditions. Antimicrobial sensitivity testing showed high effectiveness of colistin (90.4%), amikacin (88.0%), piperacillin/tazobactam (82.4%), imipenem (82.4%), and gentamicin (82.4%) for APN. However, sensitivities were lower in EPN, reflecting a concerning rise in antimicrobial resistance. Conclusion: The prevalence of antimicrobial resistance, especially in EPN cases, poses significant challenges. Although colistin, aminoglycosides, and carbapenems remain largely effective, their misuse is contributing to increased resistance. Adhering to WHO guidelines for antimicrobial prescriptions is critical to manage and prevent the escalation of multidrug resistance.

Deep Learning for Identification and Characterization of Ca ii Absorption Lines: A Multitask Convolutional Neural Network Approach

Quasar absorption lines are a powerful tool for studying the Universe, enabling us to probe distant gas, dust, and galaxy formation and evolution. However, detecting these lines, particularly Ca ii absorption lines, is a time-consuming and laborious process. Existing deep learning methods are prone to false positives and still require extensive manual verification and parameter measurement. This work presents three multitask convolutional neural network models and identifies the ResNet-CBAM model, which incorporates residual learning and an attention mechanism as the most effective. The results show that the ResNet-CBAM model achieves an accuracy of 99.7% in detecting Ca ii absorbers and excels in predicting critical parameters such as equivalent width and full width at half-maximum, with average correlation coefficients of 0.98 and 0.85, respectively. Furthermore, its remarkable generalization ability significantly improves detection precision on unseen data, rising from 20.3% of the cutting-edge model to 92.6%. In addition, with our numerous optimizations, our method can directly search for nonnormalized data, still achieving an accuracy of 98.6%. This translates to a dramatic reduction in manual inspection workload, paving the way for efficient and automated Ca ii absorber identification. In real-world applications on the Sloan Digital Sky Survey DR7 and DR12, our model successfully rediscovered 321 known Ca ii absorbers while identifying potential candidates in an additional 381 spectra. The codes used in this paper are available on Zenodo at doi:10.5281/zenodo.13953656.

Processing of reactive acrylic thermoplastic resin at elevated temperatures for rapid composite and fiber metal laminate manufacturing

Thermoplastic polymers are increasingly being used as matrix materials for composites because they offer the advantage of recyclability and joinability over thermoset matrix systems. The polymerization kinetics and gas formation of different precursor mixtures of the liquid acrylic matrix system Elium® were investigated with different initiator contents and at different temperatures for accelerated processing of composites and fiber metal laminates. The mechanical and thermal properties of the resulting polymers showed no significant difference between the investigated parameters. However, the polymerization time was successfully reduced to under 15 minutes with higher temperatures and initiator contents in laminates with 1 mm thickness. In bulk polymerization and thicker laminates, the right parameters must be chosen to balance polymerization time and matrix heating to avoid gas formation leading to voids in the matrix. A combination of 75 wt% Elium® 130 and 25 wt% Elium® 190 with 1.25 wt% peroxide initiator at 50 °C was found to be optimal for reducing gas formation while simultaneously accelerating the polymerization reaction in 3-5 mm thick layers.

The Resurging of Hydrocarbon Gas as Early Sign of Battery Rollover Degradation.

Gas analysis offers real-time critical insights into the various processes occurring within batteries. However, monitoring battery degradation through gas formation remains relatively underexplored. Traditional coin cell setups pose challenges for long-cycle experiments and do not accurately reflect real-life battery usage. In this study, online electrochemical mass spectrometry (OEMS) was used to monitor gas evolution in a 4500 mAh NMC/graphite 21700 cylindrical battery throughout its cycling life. By tracking gas species and quantities, we identified distinct phases of gas evolution corresponding to different stages of degradation. Notably, the resurgence of hydrocarbon gases such as C2H4 emerged as an early indicator of rollover degradation. Furthermore, the continuous dissolution and reformation of the solid-electrolyte interphase (SEI) layer was identified as the primary driver of battery degradation. This study demonstrates the potential for integrating miniature gas sensors into battery systems for real-time health monitoring and early degradation detection.

Small-molecule organic ice microfibers.

Small organic molecules are essential building blocks of our universe, from cosmic dust to planetary surfaces to life. Compared to their well-known gaseous and liquid forms that have been extensively studied, small organic molecules in the form of ice at low temperatures receive much less attention. Here, we show that supercooled small-molecule droplets can be drawn into highly uniform amorphous ice microfibers with lengths up to 5 cm and diameters down to 200 nm. In the experimental test, these fiber-like ices manifest excellent mechanical flexibilities with elastic strain up to 3.3%. Meanwhile, they can guide light with loss down to 0.025 dB/cm that approaches the material absorption limit and offer high optical nonlinearity for low-threshold supercontinuum generation. Notable temperature-dependent Young's modulus and icing-induced refractive-index increase are also found. These results may open a promising category of low-temperature materials for both scientific research and technological applications.

Recent advances in high-efficiency formation of gas hydrates within fixed beds: Classification, mechanism, applications and challenges

Recent advances in high-efficiency formation of gas hydrates within fixed beds: Classification, mechanism, applications and challenges

Advances in Dental Treatments: Benefits of Ozone Therapy

Introduction: Ozone therapy is a medical technique used since 1840 with positive results in various disciplines, including dentistry. This method uses ozone, a molecule composed of three oxygen atoms, known for its high oxidizing potential. Its ability to destroy bacteria, fungi and viruses without harming human cells makes it a promising tool, especially in the management of oral and periodontal infections.Development: In dentistry, ozone is applied in gaseous, aqueous and oily forms, standing out for its antimicrobial, immunostimulant, antioxidant and analgesic efficacy. Its oxidizing action deactivates antibiotic-resistant microorganisms in seconds, which positions it as a safe and effective alternative against infectious agents. For example, ozonated water is used as an irrigant in non-surgical periodontal treatment, promoting tissue healing and reducing inflammation and gingival bleeding.Ozone also stimulates the production of biologically active substances such as interleukins and prostaglandins, strengthening the body's immune response. In addition, it improves oxygen transport in tissues and activates cell metabolism, contributing to tissue regeneration and patient recovery. Its biocompatibility and minimal side effects position it as an innovative and non-invasive solution in dentistry.Conclusion: Ozone therapy represents a valuable complementary tool in dentistry. Its antimicrobial capacity, together with anti-inflammatory and regenerative effects, makes it an efficient and safe option for the management of oral and periodontal infections. Its proper implementation maximizes its benefits, improving patient experience and clinical outcomes.

Generation of highly stable electron beam via the control of hydrodynamic instability

By employing the stabilizer in the supersonic gas nozzle to produce the plasma density profile with a sharp downramp, we have experimentally demonstrated highly stable electron beam acceleration based on the shock injection mechanism in laser wakefield acceleration with the use of a compact Ti:sapphire laser. A quasi-monoenergetic electron beam with a peak energy of 315 MeV ± 12.5 MeV per shot is generated. The electron pointing fluctuations are less than 1 mrad, which is a significant improvement over previous results. This is due to the precise control of the target density distribution and the relative distance between the shock and the laser focal position. The Particle-in-cell simulations demonstrate the sensitivity of electron acceleration to the target profile, while the computational fluid dynamics prove the stabilizer’s effect on gas formation. Further developments of this scheme have the potential to deliver a high repetition rate gas target. The corresponding reproducibility of the accelerated electron beam paves the way for the realisation of compact laser plasma accelerators and the potential application of free electron lasers.

Performance Study of Ultraviolet AlGaN/GaN Light-Emitting Diodes Based on Superlattice Tunneling Junction.

In this study, we aim to enhance the internal quantum efficiency (IQE) of AlGaN-based ultraviolet (UV) light-emitting diodes (LEDs) by using the short-period AlGaN/GaN superlattice as a tunnel junction (TJ) to construct polarized structures. We analyze in detail the effect of this polarized TJ on the carrier injection efficiency and investigate the increase in hole and electron density caused by the formation of 2D hole gas (2DHG) and 2D electron gas (2DEG) in the superlattice structure. In addition, a dielectric layer is introduced to evaluate the effect of stress changes on the tunneling probability and current spread in TJ. At a current of 140 mA, this method demonstrates effective current expansion. Our results not only improve the performance of UV LEDs but also provide an important theoretical and experimental basis for future research on UV LEDs based on superlattice TJ. In addition, our study also highlights the key role of group III nitride materials in achieving efficient UV luminescence, and the polarization characteristics and band structure of these materials are critical for optimizing carrier injection and recombination processes.

Structural Characteristics of the Turning End of the Kaiping Syncline and Its Influence on Coal Mine Gas

Frequent coal mine gas disasters pose significant threats to the safety of miners and the continuity of coal mining operations. Understanding and mastering the patterns of gas occurrence is the foundation for controlling gas outbursts. This study, drawing on previous theories, research, and practical coal mine production data, analyzes the structural characteristics of the Kaiping syncline, with particular emphasis on the structural differentiation at its northeastern uplifted end. The study examines how gas generation and storage are influenced by progressively layered structures and their effect on coal mine gas management. The results indicate that the Kaiping syncline has a NE-SW axial orientation, which gradually shifts to an asymmetric syncline with a nearly EW trend, rising towards the northeastern end. At the turning end, the strata on the northwest limb are steep—locally vertical or overturned—gradually transitioning into the gentler southeast limb with dips of 10° to 30°, further complicated by a series of sub-parallel secondary folds. The gas formation process in coal seams has undergone multiple stages, regulated by structural burial and thermal evolution. The current gas storage characteristics result from the combined effects of these structural factors. The Kaiping syncline can be divided into two gas zones: a high-gas zone in the northwest limb and a shallow low-gas zone paired with a deep high-gas zone in the southeast limb. At the turning end, structural differentiation results in significant variations and gradations in the gas storage conditions of the coal seam. This differentiation directly causes a transition from coal and gas outburst mines in the northwest limb to low-gas mines in the southeast limb, highlighting the significant influence of structural factors on gas generation, preservation, and mine gas emissions. This study integrates theoretical analysis with measured data to enhance the understanding of structural evolution and its influence on gas storage. It offers guidance for preventing coal seam gas disasters and ensuring the safe production of coal mines in the Kaiping coalfield.

Hierarchically Porous Microgels with Interior Spiral Canals for High-Efficiency Delivery of Stem Cells in Wound Healing.

Chronic wound poses a serious risk to diabetic patients, primarily due to damaged skin microvasculature and prolonged inflammation at the wound site. Mesenchymal stem cell (MSC) therapy utilizing microgels as a cell delivery system has shown promise in promoting wound healing by enhancing cell viability and the secretion of bioactive factors. Retaining sufficient MSCs at injury sites is crucial for optimal therapeutic outcomes. However, inadequate hierarchical structure and limited use of the microgel's interior space significantly reduce cell proliferation and infiltration efficiency, thereby compromising the therapeutic effect. To address this, a microfluidic approach is developed for fabricating porous hierarchical interconnected microgels with interior spiral canals (PHIGels) by employing a fluidic "viscous instability" effect and gas formation reaction during the microfluidic synthesis. These MSC-laden PHIGel scaffolds facilitate rapid proliferation and infiltration into the interior spiral canals through a hierarchical pore network, significantly increasing the number of viable cells that can be carried by the microgels. It is proved that these microgel-based deliveries of MSCs promote re-epithelialization, collagen synthesis, angiogenesis, and reduction in inflammation, thus enhancing cutaneous wound repair in a rat model of type I diabetes. The microporosity and hierarchical design of these microgels offer novel routes for tissue regeneration and repair.

Assessment of Dielectric Strength for 3D Printed Solid Materials in Terms of Insulation Coordination

Insulating materials can be classified into solid, liquid, and gaseous forms. Solid insulation materials are divided into different types such as organic, inorganic, and polymer types. In electrical circuits, solid insulation materials are generally used as components that provide insulation and mechanical support. In recent years, as a result of developing technologies, the production of participation insulation materials with 3D printing technology has become widespread. Three-dimensional printing technology enables the rapid creation of objects by combining materials based on digital model data. It is important to evaluate the materials produced with 3D printing in terms of insulation coordination. Studies have shown that the electrical breakdown strength of solid dielectrics varies depending on factors such as sample type, thickness, the magnitude of applied voltage, and the temperature of the physical environment. According to IEC-60243 standards, there are various methods to measure the breakdown strength of solid insulators applied to different voltage types. In this study, the behavior of PLA, ABS, ASA, PETG, and PC/ABS materials produced with 3D printing and having the potential to be used as insulation materials when exposed to high voltage within the scope of insulation coordination was investigated. The breakdown strengths of solid insulation materials produced with 3D printing were measured in the high-voltage laboratory within the scope of IEC-60243. Breakdown strength was statistically evaluated with the Weibull distribution. Damage analysis of the breakdowns in the test specimens was examined in detail with ImageJ software. With the comparative analysis, the behaviors of PLA, ABS, ASA, PETG, and PC/ABS solid insulation materials were revealed and their superiority over each other was determined.

Ferruginous mineral waters of Western Transbaikalia: formation of gas, trace elements, and dissolved organic matter composition

The article presents the results of study of ferruginous mineral waters. The waters under consideration are discharged on the territory of Western Transbaikalia and belong to the anoxic sulfide-free and acidic types. The peculiarities of the formation features of gas, major and trace elements, and dissolved organic substance composition have been established using modern methods. It has been shown that the chemical composition of the water is greatly influenced by acid-base conditions. Acidic ferruginous waters contain large amounts of heavy metals; organic matter is mainly represented by low molecular weight organic compounds. The only metals present in significant amounts in ferruginous waters are manganese and zinc. Dissolved organic matter is represented by diverse types of high-molecular weight compounds that are formed as a result of biotic processes.

DEPOSITION OF PRIORITY POLLUTANTS FROM MOTOR VEHICLE EMISSIONS BY SNOW COVER IN THE ROADSIDE SPACE

The microzone of chemical pollution is crucial for the level of environmental safety of road operation and their interaction with the environment – the transfer of pollutants generated by the combustion of fuels in engines and substances used in road maintenance by air and water. The chemical composition of exhaust gases entering the lower atmosphere in the human breathing zone is dangerous not only for human health but also for the formation of greenhouse gases. The environmental hazard of nitrogen compound emissions is caused by the formation of fine particulate matter (PM2.5) in the atmosphere and nitrogen deposition in ecosystems. Roadside snow cover is an extremely informative substrate for monitoring the level and characteristics of roadside pollution by motor vehicle emissions. It adsorbs emission components, which are identified in melted snow as nitrogen compounds – nitrates and ammonium ion, particles in the form of suspended solids, hydrocarbons in the form of petroleum products. These contaminants form an environmental hazard of surface wastewater generated on the roadside for soils and natural water bodies. The aim of the study is to experimentally determine the contamination of snow in the roadside area of urban and suburban roads by the main environmentally hazardous pollutants of exhaust gases immobilized in the snow cover: particles (suspended solids), hydrocarbons (petroleum products), and nitrogen compounds. An experimental study of the contamination of the snow cover in the roadside area with priority pollutants (ammonium, nitrates, suspended particles, petroleum products) from vehicle emissions was carried out. It was found that in the process of exposure of the snow cover, the concentration of all studied pollutants in it increased steadily compared to the content in atmospheric snow. With increasing distance from urban and suburban roads, snow contamination with suspended solids and petroleum products was negatively correlated. This demonstrates the level of anthropogenic load created by motor vehicle traffic in the studied areas. The concentration of nitrogen-containing compounds – ammonium nitrogen and nitrates – had a positive correlation and increased with increasing distance from the road. Thus, on the studied road sections, there was a simultaneous emission of ammonium nitrogen and nitrogen oxides, which creates a particularly dangerous environmental situation in urban areas due to the formation of PM2.5.

Methane Fluxes from a Rich Fen: Relations with the Hydrochemistry and the Dissolved Carbon Isotopic Composition

The article presents the results of study of ferruginous mineral waters. The waters under consideration are discharged on the territory of Western Transbaikalia and belong to the anoxic sulfide-free and acidic types. The peculiarities of the formation of gas, major and trace elements, and dissolved organic substance composition have been established using modern methods. It has been shown that the chemical composition of the waters is greatly influenced by acid–base conditions. Acidic ferruginous waters contain large amounts of heavy metals; organic matter is mainly represented by low molecular weight organic compounds. The only metals present in significant amounts in ferruginous waters are manganese and zinc. Dissolved organic matter is represented by diverse types of high-molecular weight compounds that are formed as a result of biotic processes.

ANÁLISE DA CARACTERIZAÇÃO DE UM ALUMÍNIO RECICLADO ESTUDO DE CASO

The main objective of this study is to carry out a microstructural and mechanical analysis of a cast aluminium alloy, focusing mainly on its mechanical strength and defects, with the aim of optimizing the process, finding the cause of the main defects and proposing improvements in the process to reduce defects. The casting method used was gravity casting, in a fixed metal mold, the analysis methodology was carried out in a microstructural analysis by metallography with the Keller chemical attack; then a Rockwell F hardness analysis was carried out where the average was 54 HRF. The chemical analysis revealed impurities such as iron (Fe) and titanium (Ti), which contribute to the formation of coarse particles of the AlFeSi phase, impairing the mechanical properties of these materials. The aluminum alloy was chosen for this research because it is a versatile alloy whose main characteristic is its low melting point and low viscosity and high heat transfer coefficient, short molding time, and the disadvantage is that it presents, during the process, the formation of hydrogen gas, which can be controlled by the degassing process, and the advantage is that the alloys do not present interactions or reactions, metal - mold, having an excellent finish.

Operation of solid municipal waste landfills in northern climates

The author considers specific features of operation of solid municipal waste landfills at the post-operation stage in northern climate conditions. It is emphasized that safe operation of landfills requires efficient management of landfill gas and leachate formation. Increased precipitation leads to increased waste moisture content and, as a consequence, to methane generation during different seasons. The author presents the results of measuring methane concentrations and calculating leachate volumes at a landfill located in the north-west of Russia. The conclusion is made about the need to control and manage leachate formation, as well as to take measures for its treatment to prevent environmental and sanitary-hygienic problems associated with evaporation and accumulation of leachate.