Gas Molecules Research Articles

Adsorbtive removal of HF toxic gas via tinsulfide monolayer modification: A molecular perspective

Hydrofluoric Acid (HF) is considered one of the most hazardous chemicals used in industrial plants. Even small exposures to HF can have fatal consequences if not promptly and properly treated. Various research teams have presented numerous substances with the objective of capturing or detecting toxic HF gas. In this study, we explore the impact of HF gas on a single layer of SnS by employing density functional theory (DFT). The interaction nature between the gas molecule and the adsorbent is elucidated by analyzing the related adsorption energy, electronic structure properties and differential charge transfer. The findings indicate that HF is physically adsorbed on the pristine SnS with an adsorption energy value of −0.63 eV. By introducing a Sn mono vacancy defect, the modification of SnS enhances the adsorption energy to −1.26 eV, resulting in a chemisorption process. Molecular fluorine (F2) was discovered to undergo a barrierless reaction with SnS, resulting in the formation of fluorine-substituted SnS. It has been discovered that the substitution of fluorine atoms enhances the reactivity of SnS towards hydro-gen fluoride gas. The adsorption potential of the studied structures towards HF gas was determined to be in the following order: F2SnS > VSn–SnS > VS-SnS ∼ SnS. The current study is anticipated to offer new molecular insights that could lead to the creation of innovative devices for detecting or eliminating HF toxic gas from a specific atmosphere.

Hydrogen sulfide mitigates mitochondrial dysfunction and cellular senescence in diabetic patients: Potential therapeutic applications.

Diabetes induces a pro-aging state characterized by an increased abundance of senescent cells in various tissues, heightened chronic inflammation, reduced substance and energy metabolism, and a significant increase in intracellular reactive oxygen species (ROS) levels. This condition leads to mitochondrial dysfunction, including elevated oxidative stress, the accumulation of mitochondrial DNA (mtDNA) damage, mitophagy defects, dysregulation of mitochondrial dynamics, and abnormal energy metabolism. These dysfunctions result in intracellular calcium ion (Ca2+) homeostasis disorders, telomere shortening, immune cell damage, and exacerbated inflammation, accelerating the aging of diabetic cells or tissues. Hydrogen sulfide (H2S), a novel gaseous signaling molecule, plays a crucial role in maintaining mitochondrial function and mitigating the aging process in diabetic cells. This article systematically explores the specific mechanisms by which H2S regulates diabetes-induced mitochondrial dysfunction to delay cellular senescence, offering a promising new strategy for improving diabetes and its complications.

Coaxially covalent grafted strategy for core-shell structured CMP-CNTs hybrid membranes to enhance permeability and selectivity

The utilization of Mixed Matrix Membranes (MMMs) has been extensively employed to enhance the adsorption and separation performance by integrating the advantageous properties of polymers with organic/inorganic fillers. Conjugated microporous polymers (CMPs), distinguished by their hierarchical porous structure and abundant heteroatom adsorption sites, enable efficient and robust gas adsorption and separation in intricate surroundings. We proposed the concept of constructing a carbon nanotube (CNTs) network-supported CMPs membrane, which consists of CNTs with a three-dimensional network structure as the core and CMPs with a hierarchical pore structure and abundant heteroatom adsorption sites as the shell, aiming to address the challenging issue of membrane formation during the preparation process. The CMP-CNTs membrane prepared retain the three-dimensional network structure of CNTs and the hierarchical porous structure of CMPs, resulting in a significant reduction in permeation resistance while ensuring efficient adsorption and separation of particulate matter (PM) as well as carbon dioxide/nitrogen (CO2/N2). CMP-CNTs have an interception efficiency of over 99.9% for PM3.0 in acid-base environments. The ESP calculations reveal that the pore characteristics similar to the gas molecule kinetic diameters and the polarity-induced environment by nitrogen and oxygen heteroatoms bestow CMP-CNTs with exceptional CO2/N2 separation capabilities. CMP-CNTs exhibit an impressive IAST selectivity of up to 123 for the mixed CO2/N2 fractions (at 273 K and 1.0 bar). We proposed organic/inorganic hybrid membranes with core-shell structure formed by coaxial covalent grafting of CMPs on the surface of CNTs, this processing method with complementary advantages of organic/inorganic materials has design flexibility and process universality.

Gas hydrate technological applications: From energy recovery to carbon capture and storage

Hydrates are crystalline structures that trap small gas molecules inside hydrogen-bonded water cages. These structures form at high pressure and low temperature. In recent years, there has been a growing interest in gas hydrates for technological applications, specifically in energy recovery, as well as carbon dioxide capture and storage. In the CO2/CH4 exchange using gas hydrates, researchers have reported a large amount of natural gas trapped in the form of gas hydrates under the ocean seafloor and permafrost regions. This large amount of natural gas trapped inside hydrate cages in oceanic and permafrost deposits has driven interest in the energy sector to investigate the possibility of safely harvesting gas hydrates as one of energy resources. However, there are still unanswered fundamental questions including the mechanism of natural gas recovery from gas hydrates. Another gas hydrate-based technology that has a growing interest is the use of gas hydrates for separation including carbon dioxide capture and storage. Carbon dioxide molecules have been shown to be preferentially trapped in the hydrate phase, demonstrating the possibility of the usage for carbon capture technology. Similarly, there are still underlying concerns of these applications, such as thermodynamics and stability of gas hydrates in porous materials, and the crystallization kinetics and mechanism of hydrate formation. This paper provides an overview of laboratory investigations conducted to understand the mechanism and evaluate the feasibility of energy recovery as well as discussion on recent advances in laboratory investigations on gas hydrate-based technology.

Locating gas molecules in MOFs by cryo-3D electron diffraction

Locating gas molecules in MOFs by cryo-3D electron diffraction

Comprehensive analysis of normal shock wave propagation in turbulent non-ideal gas flows with analytical and neural network methods

Shock wave propagation in gases through turbulent flow has wide-reaching implications for both theoretical research and practical applications, including aerospace engineering, propulsion systems, and industrial gas processes. The study of normal shock propagation in turbulent flow over non-ideal gas investigates the changes in pressure, density, and flow velocity across the shock wave. The Mach number is derived for the system and explored across various gas molecule quantities and turbulence intensities. This study analytically investigated the normal shock wave propagation in turbulent flow of adiabatic gases with modified Rankine–Hugoniot conditions. Artificial neural network (ANN) techniques are used to estimate the solutions for shock strength and Mach number training validation phases of back-propagated neural networks with the Levenberg–Marquardt algorithm. The results reveal that pressure ratio with density ratio increase for higher values of increase in the turbulence level as well as intermolecular forces. A reverse trend is observed in velocity coefficient after shock in the presence of adiabatic gas. The regression coefficient values obtained using the network model ranged from 0.999 99 to 1, indicating an almost perfect correlation. These findings demonstrate that the ANN can predict the Mach number with high accuracy.

Reactive molecular dynamics simulations of poly(vinyl alcohol) gasification in supercritical carbon dioxide

Supercritical fluid gasification technology, as an environmentally friendly technology, can convert organic components of plastic waste into fuels and chemical materials. Moreover, the utilization of CO2 as the gasification environment holds significant importance for reducing carbon emissions. To better comprehend the microscopic mechanism of plastic gasification in supercritical environment, this sthdy used the Reactive Force Field (ReaxFF) molecular dynamics method to study the gasification process of long-chain poly(vinyl alcohol) molecule in supercritical H2O/CO2 under different reaction conditions. The result illustrated that during the gasification process, poly(vinyl alcohol) initially depolymerized into multiple long carbon chain (C5+) molecular fragments. Subsequently, these fragments underwent cleavage into short carbon chains and various gaseous small molecules. In this reaction, O radicals generated by CO2 decomposition play a crucial role in promoting the cleavage of plastic C–C bonds. In addition, through the analysis of the products and chemical bonds, we found that increasing temperature and prolonging reaction time significantly enhance the gasification efficiency and hydrogen production of plastics. Conversely, exceedingly high pressure inhibits the gasification reaction.

Effect of surface roughness on methane adsorption in shale organic nanopores from the perspective of molecular simulations

Understanding the shale gas adsorption behavior within organic nanopores is crucial for its development. The pore surfaces commonly exhibit random inherent roughness, which can significantly impact gas adsorption, while it’s still in debate about whether the roughness could enhance the gas adsorption or not. To clarify the underlying mechanisms of the effect of surface roughness, in this study, the Grand Canonical Monte Carlo and Molecular Dynamic simulations are used to investigate the methane adsorption in wrinkled graphene nanochannels with various roughness. The heterogeneity of the adsorption layer along the rough topology is described in detail. The adsorption is enhanced near the concave region and weakened near the convex region. Additionally, increased surface roughness shifts the gas molecules’ aggregation modes in the concave region from a gradual gradient to oscillatory “adsorption points”. We observe that wall roughness due to the wrinkle can enhance the adsorption amount overall, attributed to the increased surface area and the increased unit adsorption capacity due to potential energy overlap. However, the contributions of both factors differ under various pressure and roughness conditions. Then a new mathematical method to estimate the gas adsorption amounts is provided and aligns well with molecular simulation results for a wide range of pressure and roughness conditions. And a potential answer the current debate about the positive or negative impact of adsorption due to roughness is promoted. The key may lie in the dominant role of the co-existed roughness caused by the fragment basal or edge surface. Our work could shed light on the underlying effect of surface roughness on the gas adsorption in shale, and have significant implications for the reserve estimation of shale gas formations.

Insights into the pore size distribution of amorphous silica membranes using gas permeation activation energies

Silica-based membranes exhibit significant promise for the separation of hydrogen from other larger gas molecules based on size sieving mechanism, particularly when employed in membrane reactors. Nevertheless, the migration of silanol bonds (Si–OH) formed under hydrothermal conditions leads to alterations in pore size, ultimately compromising the performance of the membrane. Therefore, this study focuses on determining the pore size of cobalt-doped silica membranes before and after hydrothermal treatment by the apparent activation energy of gas permeation. The Oscillator model and the effective medium theory are employed to estimate the potential pore size distribution, as well as to calculate the apparent activation energy and permeability. The calculated apparent activation energy is compared with experimental data to identify the most probable pore size distribution, which showed the minimum activation energy error to the experimental value. The calculated permeability based on the identified pore size distribution is in line with experimental permeability, which validated the identified pore size distribution. Since silica-based membrane is generally applied in hydrothermal conditions, our model successfully identifies the changes in pore size of silica-based membranes after hydrothermal treatment. The results demonstrated that hydrothermal treatment significantly impacts the pore size of silica-based membranes. Specifically, 5-membered rings are prevalent in the intact membrane, but after hydrothermal treatment, there is a gradual shift of the pore size distribution towards larger pores, potentially leading to a decrease in sieving performance. This methodology presents a promising approach for determining intriguing pore size information of porous materials.

Theoretical simulation study of laser-induced plasma bombardment on bacteria

With the rapid advancement of laser decontamination technology and growing awareness of microbial hazards, it becomes crucial to employ theoretical model to simulate and evaluate decontamination processes by laser-induced plasma. This study employs a two-dimensional axisymmetric fluid dynamics model to simulate the power density of plasma bombardment on bacteria and access its decontamination effects. The model considers the transport processes of vapor plasma and background gas molecules. Based on the destructive impact of high-speed moving particles in the plasma on bacteria, we investigate the bombardment power density under various conditions, including different laser spot sizes, wavelengths, plate’s tilt angles, and plate-target spacing. The results reveal that the bombardment power density increases with a decrease in laser spot size and wavelength. For instance, when the plate is parallel to the target surface with a 1 mm spacing, the bombardment power density triples as the laser spot size decreases from 0.8 mm to 0.5 mm and quadruples as the wavelength decreases from 1064 nm to 266 nm. Notably, when the plate is parallel to the target with a relatively close spacing of 0.5 mm, the bombardment power density at 0° inclination increases sevenfold compared to 45°. This simulation study is essential for optimizing optical parameters and designing component layouts in decontamination devices using laser-induced plasma. The reduction of laser spot size, wavelength, plate-target spacing and aligning the plate parallel to the target, collectively contribute to achieving precise and effective decontamination.

A Comprehensive Study on Electrospun Cholesteric Liquid Crystal Core Fibers for Detecting Volatile Organic Compounds

Encapsulation of the cholesteric liquid crystal (CLC) into the core of poly(vinylpyrrolidone) (PVP) microfibers is accomplished via coaxial electrospinning technology and is applied to detect volatile organic compounds (VOCs). The impacts of various process parameters on the morphology of CLC fibers are deeply explored. The periodic arrangement of CLC molecules within the fibers enables the reflection of specific wavelengths. Consequently, changes in the reflected color of the CLC fiber membrane allow for the measurement and analysis of targeted gas molecules. The dynamic response of CLC fibers upon exposure to organic vapor is observed by a polarizing optical microscope, and its gray scale is used to quantitatively analyze the changes of reflected light signals of CLC fibers. Furthermore, the study investigates the reaction time for the failure of CLC molecular planar alignment in the CLC fiber membrane when subjected to perturbations induced by organic gases. The CLC fiber sensor exhibits heightened sensitivity to gases characterized by greater polarity. In light of potential future advancements, it is suggested that the spun fibers imbued with responsive properties through the incorporation of a liquid crystal core exhibit promise as a next-generation sensor technology in textile form, well-suited for applications in wearable technology.

Memristive gas sensor (gasistor) based on Ag/ordered TiO2 nanorods/FTO sandwich structure for evaluation of ethanol concentration in mixed ambient

Herein, we designed a memoristor-type gas sensor (gasistor) with Ag/ordered TiO2 nanorods/FTO sandwich structure for recognizing ethanol concentration in ethanol-methanol mixtures. The gas adsorption characteristics of different TiO2 substrates were first investigated by first-principle calculations. The results showed that the TiO2 surface in the low resistance state exhibited better immunity to other interfering gas molecules. However, similar adsorption energies and charge transfers calculated for adsorption of methanol and ethanol mean that the interference of methanol to the response of ethanol cannot be completely ignored. In next experiments, the Ag/TiO2/FTO gasistor with well-aligned TiO2 nanorods as the resistive layer was constructed successfully and demonstrated the stable resistive switching function and excellent retention characteristic. Further device tests confirm the ability of the gasistor in the low resistance state to discriminate between ethanol and methanol, as well as better anti-interference for other organic vapors. Also, an ultra-short recovery time (∼1.8 s) was observed by applying a direct current scanning voltage to the gasistor. Finally, to improve the recognition rate of ethanol in ethanol-methanol mixed atmosphere, a neural network algorithm based on back-propagation was incorporated and good prediction accuracy was obtained at ethanol concentrations ≥ 5 ppm.

Bismuth oxyiodide as a highly efficient room temperature NOx gas sensor: Role of surface orientations on sensing performance

In the pursuit of developing fast and reliable gas sensors, a new ternary oxide semiconductor, a bismuth oxyiodide (BiOI)-based sensing material, has been reported with desirable adsorption energy, short recovery time, and high sensitivity and selectivity for detecting nitrogen oxide mixtures (NOx, typically NO and NO2). The structural, electronic, and transport properties of both (001) and (012) planes of BiOI surfaces upon the adsorption of six environmentally relevant gases (NO, NO2, SO2, SO3, O2, and H2O) are systematically explored using a combination of density functional theory (DFT) and non-equilibrium Green's function (NEGF) methods. The results indicate that BiOI (001) exhibits weak interaction with these gases, with the highest adsorption energy observed for NO. In contrast, the BiOI (012) surface shows enhanced adsorption stability for these gases, particularly acceptable strong adsorption to NO2, indicating its promising capability for detecting these gases with high specificity. Moreover, it demonstrates the most intense chemisorption for SO3, suggesting it to be a reliable SO3 adsorbent/cleaner. The obtained transport characteristics, including current-voltage (I-V) and resistance-voltage (R-V) curves, further highlight the higher selectivity of the BiOI (001) device towards NO and the BiOI (012) device towards NO2 against the other gases. Furthermore, the transmission spectra analyses reveal that the BiOI-based sensor can electrically discriminate the target gas molecules from other considered gas molecules. Besides, the practical application possibilities of both orientations are explored by estimating their recovery time, and the results show that the BiOI sensor has excellent recovery times at room temperature (NO/BiOI (001) = 0.158 ns, and NO2/BiOI (012) = 3.89 s), highlighting its potential as an ideal reversible gas-sensing material for detecting NOx gases.

Constructing sodium alginate/carboxymethyl chitosan coating capable of catalytically releasing NO or CO for improving the hemocompatibility and endothelialization of magnesium alloys

Although significant progress in developing biodegradable magnesium alloy materials in cardiovascular stents has been achieved recently, they still face challenges such as rapid in vivo corrosion degradation, inferior blood compatibility, and limited re-endothelialization after the implantation. Hydrogel coating that can catalyze the liberation of gas signal molecules offers a good solution to alleviate the corrosion rate and enhance the biocompatibility of magnesium and its alloys. In this study, based on alkaline heat treatment and construction of polydopamine coating on the surface of magnesium alloy, sodium alginate/carboxymethyl chitosan (SA/CMCS) gel was simultaneously covalently grafted onto the surface to build a natural polymer hydrogel coating, and selenocystamine (SeCA) and CO release molecules (CORM-401) were respectively immobilized on the surface of the hydrogel coating to ameliorate the anticoagulant performance and accelerate endothelial cells (ECs) growth by catalyzing the release of endogenous gas signal molecules (NO or CO). The findings verified that the as-prepared hydrogel coating can catalyze the liberation of CO or NO and significantly improve the corrosion resistance of magnesium alloy. At the same time, owing to the excellent hydrophilicity of the hydrogel coating, the good anticoagulant property of sodium alginate, and the ability of CMCS to promote the ECs growth, the modified magnesium alloy could significantly improve the albumin adsorption while preventing the adsorption of fibrinogen, hence significantly augmenting the anticoagulant properties and promoting the ECs growth. Under the catalytic release of NO or CO, the released gas molecules further enhanced hemocompatibility and promoted endothelial cell (EC) growth and the expression of vascular endothelial growth factor (VEGF) and NO of ECs. Therefore, the bioactive coatings that can catalyze the release of NO or CO have potential applications in constructing surface bioactive coatings for magnesium alloy materials used for intravascular stents.

First-Principles study on proton transfer in triazole molecules

Triazole can be used as an effective proton carrier because it has one proton donor and two proton acceptors. Density functional theory calculations were performed to explore the proton transfer mechanism of the triazole molecules in gas and solvents. We employed implicit solvent method to analyze the increase of proton donor–acceptor distance (PDAD) in proton transfer mechanism. The solvents reduce the relative energy in tautomers of 1,2,4-triazole molecules, and their protonated form. Proton transfer occurs only at symmetric pairs in the gas, small PDAD, whereas proton transfer in an asymmetric pair is possible in solvents as the PDAD increases.

C-doped [formula omitted] monolayer as toxic gas scavenger or sensor based on first-principles study

The selective adsorption mechanism of C-CdS2 monolayer was revealed using density functional theory. The results show that C-CdS2 has good adsorption properties for SO2, NO, NH3, NO2 and Cl2, and all of them are chemisorbed. Under the adsorption of different gas molecules, the electronic structure of C-CdS2 changed to varying degrees, which provided a theoretical basis for the use of C-CdS2 as a gas sensor or scavenger for these gases.

Adsorption and gas sensitivity of Janus SnSSe monolayers doped with transition metals to harmful gases: First principles studies

Sensitivity detection of toxic gases has always been a very needed technology, and it is particularly important to prevent the gas from causing damage to the human body. To meet the demand, we propose TM atom-doped Janus SnSSe monolayers as a promising gas sensing material for the detection of three typical hazardous gases (CO, NO and CO2). In this paper, density functional theory is used to systematically study the adsorption process of the target gas on the surface of the pristine and modified substrate. By comparing the formation energy of the two sides of the TM-SnSSe monolayer, the TM atom doped on the surface of Se is more stable. Compared with SnSSe monolayers, the Os-SnSSe system has the best adsorption performance for CO and the Ru-SnSSe system has the best adsorption performance for NO and CO2. By calculating the density of state, charge density difference, work function and recovery time of each adsorption system, the interaction mechanism between gas molecules and TM-SnSSe is described, and the function and reusability of the sensor materials are explored. The results show that the SnSSe monolayer modified with TM can be used as a kind of gas detection and purification material. The research work in this paper can predict new sulfide sensing materials, increase their application possibility in the field of environmental monitoring, and provide theoretical guidance for the development of promising new sensors.

Confining Thiolysis of Dinitrophenyl Ether to a Luminescent Metal-Organic Framework with a Large Stokes Shift for Highly Efficient Detection of Hydrogen Sulfide in Rat Brain.

Hydrogen sulfide (H2S) is a gaseous signaling molecule that regulates various physiological and pathological processes in the central nervous system. It is vital to develop an effective method to detect H2S in vivo to elucidate its critical role. However, current fluorescent probes for accurate quantification of H2S still face big challenges due to complicated fabrication, small Stokes shift, unsatisfactory selectivity, and especially delayed response time. Herein, based on simple postsynthetic modification, we present an innovative strategy by confining H2S-triggered thiolysis of dinitrophenyl (DNP) ether within a luminescent metal-organic framework (MOF) to address those issues. Due to the cleavage of the DNP moiety by H2S, the nanoprobe gives rise to a remarkable fluorescence turn-on signal with a large Stokes shift of 190 nm and also provides high selectivity to H2S against various interferents including competing biothiols. In particular, by virtue of the unique structural property of the MOF, it exhibits an ultrafast sensing ability for H2S (only 5 s). Moreover, the fluorescence enhancement efficiency displays a good linear correlation with H2S concentration in the range of 0-160 μM with a detection limit of 0.29 μM. Importantly, these superior sensing performances enable the nanoprobe to measure the basal value and monitor the change of H2S level in the rat brain.

Persulfide Dioxygenase from Pseudomonas aeruginosa unveils a novel crosstalk mechanism between the bioenergetically-relevant gaseous signaling molecules nitric oxide and hydrogen sulfide

Persulfide Dioxygenase from Pseudomonas aeruginosa unveils a novel crosstalk mechanism between the bioenergetically-relevant gaseous signaling molecules nitric oxide and hydrogen sulfide

Hydrogen Sulfide Modulation of Matrix Metalloproteinases and CD147/EMMPRIN: Mechanistic Pathways and Impact on Atherosclerosis Progression.

Atherosclerosis is a chronic inflammatory condition marked by endothelial dysfunction, lipid accumulation, inflammatory cell infiltration, and extracellular matrix (ECM) remodeling within arterial walls, leading to plaque formation and potential cardiovascular events. Key players in ECM remodeling and inflammation are matrix metalloproteinases (MMPs) and CD147/EMMPRIN, a cell surface glycoprotein expressed on endothelial cells, vascular smooth muscle cells (VSMCs), and immune cells, that regulates MMP activity. Hydrogen sulfide (H₂S), a gaseous signaling molecule, has emerged as a significant modulator of these processes including oxidative stress mitigation, inflammation reduction, and vascular remodeling. This systematic review investigates the mechanistic pathways through which H₂S influences MMPs and CD147/EMMPRIN and assesses its impact on atherosclerosis progression. A comprehensive literature search was conducted across PubMed, Scopus, and Web of Science databases, focusing on studies examining H₂S modulation of MMPs and CD147/EMMPRIN in atherosclerosis contexts. Findings indicate that H₂S modulates MMP expression and activity through transcriptional regulation and post-translational modifications, including S-sulfhydration. By mitigating oxidative stress, H₂S reduces MMP activation, contributing to plaque stability and vascular remodeling. H₂S also downregulates CD147/EMMPRIN expression via transcriptional pathways, diminishing inflammatory responses and vascular cellular proliferation within plaques. The dual regulatory role of H₂S in inhibiting MMP activity and downregulating CD147 suggests its potential as a therapeutic agent in stabilizing atherosclerotic plaques and mitigating inflammation. Further research is warranted to elucidate the precise molecular mechanisms and to explore H₂S-based therapies for clinical application in atherosclerosis.