Nitrogen Hydrogen Research Articles

Boron modification of AuRh mesoporous nanotubes for electro-reduction of nitrogen to ammonia.

Electrocatalytic nitrogen reduction reaction (NRR) is a prospective tactics for ammonia synthesis. However, the development of highly active NRR electrocatalysts is still challenging owing to the difficult activation of nitrogen and competitive hydrogen evolution reaction (HER). Here, we synthesized boron-doped AuRh mesoporous nanotubes (B-AuRh MNTs) via dual-template method coupled with boron doping. The mesoporous nanotube structure has high specific surface area and excellent surface permeability. Thereby, the B-AuRh MNTs exhibit NH3 yield of 13.3 μg h-1 mg-1cat and Faraday efficiency of 22.5% under 0.1 M Na2SO4. The doping of boron with weak hydrogen adsorption can generate electronic effect, thus stimulating the activation of N2 molecules and effectively inhibiting HER. This study proposes a universal method for the preparation of boron-doped Pd-based catalysts, which is beneficial to improve the NRR performance.&#xD.

S‐Scheme Heterojunction Engineering of CdS/Bi2WO6 in Breakthrough Piezocatalytic Nitrogen Reduction and Hydrogen Evolution: Performance, Mechanism, and DFT Calculations

AbstractHerein, a novel bismuth tungstate and cadmium sulfide (CdS/Bi2WO6）step‐scheme (S‐scheme) heterojunction piezocatalyst for the first time is developed. The exceptional piezocatalytic nitrogen reduction reaction activity (1.37 mmol L−1 g−1 h−1) is delivered, which is significantly higher compared to pure CdS (0.06 mmol L−1 g−1 h−1) and bare Bi2WO6 (0.45 mmol L−1 g−1 h−1), showing an almost 23‐fold and 3‐fold increase, respectively. This performance greatly exceeds previously reported piezocatalysts and piezo‐photocatalysts. Meanwhile, this catalyst also holds outstanding piezocatalytic hydrogen evolution reaction rate of 1.02 mmol g−1 h−1. Relevant experimental and density functional theory (DFT) calculations results demonstrate that the excellent catalytic capacity of CdS/Bi2WO6 is mainly ascribed to the construction of S‐scheme heterojunction, which greatly promotes piezoelectric performance, enhances the segregating efficiency of charge carriers and redox capacity, regulates electronic structure, optimizes the reaction dynamics processes and reduces the reactions barrier, and induces more active sites. Furthermore, a new piezocatalytic mechanism for the CdS/Bi2WO6 S‐scheme heterojunction is proposed. This research extends the applications of S‐scheme heterojunctions in sustainable energy piezocatalysis and offers insights for designing efficient piezocatalytic systems.

AACVD synthesized tungsten oxide-NWs loaded with osmium oxide as a gas sensor array: enhancing detection with PCA and ANNs.

This paper presents the fabrication of sensors based on tungsten trioxide nanowires decorated with osmium oxide nanoparticles using the aerosol-assisted chemical vapor deposition (AACVD) technique. This methodology allows the obtention of different osmium oxide decoration loadings on the tungsten oxide nanowires. The morphological and chemical characteristics; and the structural properties of the sensing layers of the sensors were studied using different techniques such as FESEM, HR-TEM, and ToF-SIMS. The gas sensing properties were analyzed for pure tungsten trioxide sensors and tungsten trioxide loaded with osmium exposed to nitrogen dioxide, hydrogen, and ethanol, thus assessing the impact of the loading on the sensor response. A sensor array comprising pure and osmium-loaded tungsten oxide devices coupled to multivariate pattern recognition techniques is shown to perform well in gas identification and quantification tasks, offering promising implications in the field of gas sensing technology.

Healing properties of natural mineral water of Tajikistan

Aim. To study the composition and medicinal properties of water from natural mineral springs in the Republic of Tajikistan.Materials and Methods. This study analyzed the climatic and geographical regions, as well as the water quality and chemical composition of four mineral springs: Khoja-Obi-Garm, Obi-Garm, Garm-Chashma, and Shoambary. The research also investigated the influence and effectiveness of these mineral waters in treating skin diseases.Results and Discussion. The Republic of Tajikistan has numerous mineral springs that are used for treating skin conditions and other health issues. Mineral waters in Tajikistan are classified into five types based on their chemical composition: bicarbonate, chloride, sulfate, nitrate, and mixed composition waters. In addition, there are waters with active ions and gaseous elements such as hydrogen sulfide, radon, nitrogen, and methane. Based on temperature, these waters are categorized as cold, warm, or hot/thermal waters. The springs at Khoja-Obi-Garm, Obi-Garm, Garm-Chashma, and Shoambary are hot thermal baths of the bicarbonate-chloride-sulfate-sodium type. In addition to the primary salts and gases, these waters contain biologically active trace elements, including aluminum, titanium, manganese, copper, silicon, molybdenum, strontium, barium, boron, fluorine, and others.Conclusion. Tajikistan holds a leading position in Central Asia regarding the abundance of mineral springs, and the mineral waters from these springs meet the requirements for therapeutic use. These waters contain a variety of chemical elements that exert significant biological effects, and, when used appropriately, can effectively treat many diseases.

Investigating the Impact of Hydrogen Bonding on Silicon Nitride (SiNx) Film

The deposition of amorphous hydrogenated silicon nitride (a‐SiNx:H) via plasma‐enhanced chemical vapor deposition is critical for optimizing the performance of crystalline silicon (c‐Si) solar cells. This study investigates the impact of varying gas ratios (GR = NH3/SiH4) on the optical and physical properties of deposited SiNx films. Results show that the refractive index (RI) ranges from 1.8 to 2.3 with changing gas compositions. Fourier transform infrared Spectroscopy reveals shifts in [SiNH] and [SiH] stretching modes, indicating changes in hydrogen passivation and nitrogen incorporation. Hydrogen bonding densities of [SiH] and [SiNH] correlate positively with the RI. For example, the hydrogen bonding density [NH] ranges from 4.53 × 1023 to 6.32 × 1023 cm−3 for [SiNH] bonds while [Si‐H] varies from 6.93 × 1023 to 1.06 × 1024 cm−3. Secondary ion mass spectrometry (SIMS) analysis shows stable hydrogen intensity, contrasting with a decrease in nitrogenhydrogen bonds. These findings highlight the key role of hydrogen bonding in determining SiNx film properties, with significant implications for semiconductor and photovoltaic applications.

Numerical Modeling of the Fluids Petroleum Flow Through the Supersonic Separator

In the context of increasing concerns regarding the amplification of the thermal effects of climate change, the Council of the European Union has proposed the reduction (up to the elimination) of the use of fossil fuels. For this purpose, the implementation of new ecological (renewable) fuels is being analyzed to reduce the carbon dioxide footprint, natural gas being the transition fuel. Also, in the next period, an increase in the demand for methane, the exploitation of condensate deposits, those with natural gas mixed with acid gases (containing hydrogen sulfide, carbon dioxide, and nitrogen), as well as oil deposits with associated natural gas, which will require their treatment (to eliminate saline or non-saline water, mechanical impurities, of condensate and acid gases). At the same time, the exploitation of offshore deposits in deep waters will be emphasized, which will lead to the location of treatment equipment on the seabed. The present work discusses the simulation of natural gas treatment processes, focusing on the separation from methane (in the supersonic field) of water, condensate, and acid gases.

Tunnel silicon oxynitride phase transformation for n-type polysilicon passivating contacts in crystalline silicon solar cells

The study investigates the fabrication and characterization of tunnel oxynitride (TON) layers produced using Plasma-Enhanced Chemical Vapor Deposition (PECVD) at different pressure and power variations. The aim is to explore TON layers as potential substitutes for conventional SiO2 in Tunnel Oxide Passivated Contact (TOPCon) solar cells. Foe this purpose, an effective oxide thickness (EOT) of 1.1–1.2 nm and 1.5–1.6 nm has been achieved by treating the TON samples with NH3 and N2 gas plasma, respectively. Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed critical variations in the chemical bonding within TON layers, which exhibit different properties based on the deposition conditions. The presence of nitrogen-nitrogen and nitrogen–hydrogen bonds is prominently influenced by changes in the PECVD parameters, directly affecting the layer’s optical and electronic properties. Notably, the presence of hydroxyl (O–H) and amino (NH2) groups within the TON structure suggests an improvement in surface passivation, essential for optimizing solar cell performance and durability. A lifetime of 737 and 823 μs has been recorded for N2 and NH3 samples, compared to the NAOS 710 μs reference sample. NH3 plasma-treated samples show an improved iVoc of 736 mV, indicating better phase transformation and passivation quality than N2 plasma treatment and the NAOS reference sample.

A Comparative Review of Graphene and MXene-Based Composites towards Gas Sensing.

Graphene and MXenes have emerged as promising materials for gas sensing applications due to their unique properties and superior performance. This review focuses on the fabrication techniques, applications, and sensing mechanisms of graphene and MXene-based composites in gas sensing. Gas sensors are crucial in various fields, including healthcare, environmental monitoring, and industrial safety, for detecting and monitoring gases such as hydrogen sulfide (H2S), nitrogen dioxide (NO2), and ammonia (NH3). Conventional metal oxides like tin oxide (SnO2) and zinc oxide (ZnO) have been widely used, but graphene and MXenes offer enhanced sensitivity, selectivity, and response times. Graphene-based sensors can detect low concentrations of gases like H2S and NH3, while functionalization can improve their gas-specific selectivity. MXenes, a new class of two-dimensional materials, exhibit high electrical conductivity and tunable surface chemistry, making them suitable for selective and sensitive detection of various gases, including VOCs and humidity. Other materials, such as metal-organic frameworks (MOFs) and conducting polymers, have also shown potential in gas sensing applications, which may be doped into graphene and MXene layers to improve the sensitivity of the sensors.

Hydrothermal synthesis of nanostructured Zn2SnO4 ternary metal oxide semiconductor for toxic gas sensing application and its characterization study

Purpose The study aims to develop an inexpensive metal oxide semiconductor gas sensor with high sensitivity, excellent selectivity for a specific gas and rapid response time. Design/methodology/approach This study synthesized Zn2SnO4 nanostructures using a hydrothermal method with a 1 M concentration of zinc chloride (ZnCl2) as the zinc source and a 0.7 M concentration of tin chloride (SnCl4) as the tin source. Thick films of nanostructured Zn2SnO4 were then produced using screen printing. The structural properties of Zn2SnO4 were confirmed using X-ray diffraction, and the formation of Zn2SnO4 nanoparticles was verified by transmission electron microscopy. Scanning electron microscopy was used to analyse the surface morphology of the fabricated material, while energy dispersive spectroscopy provided insight into the chemical composition of the thick film. These fabricated thick films underwent testing for various hazardous gases, including nitrogen dioxide, ammonia, hydrogen sulphide (H2S), ethanol and methanol. Findings The nanostructured Zn2SnO4 thick film sensor demonstrates a notable sensitivity to H2S gas at a concentration of 500 ppm when operated at 160°C. Its selectivity, response time and recovery time were assessed and documented. Research limitations/implications The primary limitations of this research on metal oxide semiconductor gas sensors include poor selectivity to specific gases, limited durability and challenges in achieving detection at room temperature. Practical implications The nanostructured Zn2SnO4 thick film sensor demonstrates a strong response to H2S gas, making it a promising candidate for commercial production. The detection of H2S is crucial in various sectors, including industries and sewage plants, where monitoring this gas is essential. Social implications Currently, heightened global apprehension about atmospheric pollution stems from the existence of perilous toxic and flammable gases. This underscores the imperative need for monitoring such gases. Toxic and flammable gases are frequently encountered in both residential and industrial environments, posing substantial hazards to human health. Noteworthy accidents involving flammable gases have occurred in recent years. It is crucial to comprehend the presence and composition of these gases in the surroundings for precise detection, measurement and control. Thus, there has been a significant push for extensive research and development in diverse sensor technologies using various materials and methodologies to monitor and regulate these gases effectively. Originality/value In this research, Zn2SnO4 nanostructures were synthesized using a hydrothermal method with ZnCl2 at a concentration of 1 M for zinc and SnCl4 at a concentration of 0.7 M for tin. Thick films of nanostructured Zn2SnO4 were then fabricated via screen printing technique. Following fabrication, all thick films were subjected to testing with various toxic gases, and the results were compared to previously published data. The analysis indicated that the nanostructured Zn2SnO4 thick film sensor demonstrated outstanding performance concerning gas response, gas concentration, selectivity and response time, particularly towards H2S gas.

K and Mg Co-doped perovskite oxide for enhanced anode of direct ammonia protonic ceramic fuel cell

Ammonia (NH₃) is a promising fuel for protonic ceramic fuel cells (PCFCs) due to its favorable liquefaction conditions and high volumetric energy density. However, even state-of-the-art PCFC anodes show insufficient NH₃ decomposition activity at reduced temperatures, compromising PCFC power output and durability. In this study, we report a novel nickel-perovskite-type structured oxide cermet anode with an NH₃ decomposition activity that enables relatively high power output from direct NH₃-PCFCs at 600 °C. We co-dope K and Mg into a perovskite-type structured oxide to produce the Ba0.95K0.05(Zr0.1Ce0.7Y0.1Yb0.1)0.95Mg0.05O3-δ (BZCYYb-KMg) material, which facilitates the rate-limiting steps in NH₃ decomposition: hydrogen transport and nitrogen desorption. Consequently, our modified nickel-perovskite-type structured oxide cermet anode achieves 100% NH₃ conversion at 600 °C. When used as a PCFC anode, this material increased the power output of a PCFC using NH₃ fuel at 600 °C by 25% and lifetime by more than 15 times compared to PCFC containing the unmodified nickel-perovskite-type structured oxide cermet anode.

High-sensitive and fast-responsive In2O3 thin film sensors for dual detection of NO2 and H2S gases at room temperature

In this work, the room-temperature dual gas sensing characteristics of indium oxide (In2O3) thin films towards NO2 and H2S have been studied. In2O3 thin films were synthesized by the thermal oxidation of indium metal films of various thicknesses in the range of 50–250 nm deposited by thermal evaporation method. Grazing incidence X-ray diffraction (GI-XRD) revealed the change in preferred orientation of In2O3 thin films corresponding to varying thickness, while field-emission electron microscopy studies showcased evolving surface morphologies from individual grains to granular network with respect to the increase in film thickness. Investigations were made on the ability of In2O3 thin films to detect various low concentrations of nitrogen dioxide (NO2) and hydrogen sulfide (H2S) gases at ambient temperature. In2O3 thin films synthesized using 100 nm thick In films exhibited good sensing response of around 58 and 68 % towards NO2 and H2S gases of 5 ppm respectively, at room temperature (27 °C) with the response time of 36 and 18 s. Remarkably, the lower experimental detection limit of these toxic gases could be extended up to 100 ppb. Using X-ray photoelectron spectroscopy, a large presence of surface oxygen is observed on the In2O3 thin film. The sensor has demonstrated remarkable sensing abilities, including strong selectivity, quick sensing response, and good repeatability.

Quantitative comparison of the benefits of cracking and nanosecond repetitive pulsed discharges on the lean blow-off, emissions, and topology of ammonia premixed swirl flames

In the last decade, ammonia has gained interest as an alternative fuel for the energy sector. The main advantages include its carbon neutrality and ease of storage at industrial scale. However, to consider ammonia as an alternative carbon-free fuel it is necessary to solve two main issues, namely flame stability and pollutant emission. In this work we compared two promising technologies used to enhance ammonia combustion, specifically partial cracking and plasma assisted combustion (PAC). The experiments were carried out for different blends of ammonia–hydrogen–nitrogen–air that reproduce the conditions of cracking as well as for pure ammonia assisted by nanosecond repetitive pulsed (NRP) discharges for the PAC. The cracking and PAC were compared for the same added power ratio at atmospheric conditions. Different added power ratios, from 0.1% to 4% of the flame’s total thermal power, were tested. The lean blow-off limits were measured for a range of bulk flow velocities between of 4 and 12 m/s. For the pollutant emissions, NOx, NH3, and N2O were considered. The effect of both strategies on the Laminar burning velocity (LBV) was explored by numerical simulations. For the same added power ratio, partial cracking extended the lean blow-off limits further than NRP discharges, even with a high pulse repetition frequency of 30 kHz. This result indicated that cracking was more effective in stabilizing the flame than PAC. Regarding NOx emissions, NRP discharges induced only a third of the increase observed with cracking. However, the reduction in N2O associated with cracking was twice as much as that for NRP discharges. Finally, cracking proved more efficient in reducing the flame height, which was supported by the simulations of LBV. These results suggest that PAC strategies optimized for hydrocarbon flames are less efficient on ammonia combustion, and that more work is needed to develop plasma actuators for NH3 combustion.Novelty and Significance statement This work marks the first one-to-one quantitative comparison between plasma actuation and thermal cracking on ammonia swirl flames. It serves as a pivotal exploration to assess and understand the economic aspects of these strategies, providing valuable insights into their efficiency and potential for practical implementation.

Development of new universal correlations for minimum heat flux point for saturated pool boiling of cryogens

This study addresses the critical need for a reliable database for the minimum heat flux (MHF) point in saturated pool boiling of cryogens. Relying on a comprehensive review of the relatively sparse published literature, a key objective of the study is to amass a MHF database, which is then used to investigate influences of various parameters on MHF, assess the accuracy of published correlations, and develop new correlations specifically tailored to cryogenic fluids. By applying stringent point-by-point evaluation criteria, 165 data points for MHF point temperature (Tmin) and 158 data points for MHF point heat flux (q”min) are aggregated, comprising this study's “Consolidated Database” for MHF. This database includes data for liquid helium (LHe), liquid argon (LAr), liquid hydrogen (LH2), and liquid nitrogen (LN2) and boiling from clean as well as treated (coated or oxidized) surfaces. A total of 9 correlations for Tmin and 10 for q”min are evaluated for accuracy against the new Consolidated Database. Leveraging insights from prior correlation results and trends from the new Consolidated Database, new universal correlations are formulated for both Tmin and q”min. The new correlation for Tmin features Mean Absolute Errors (MAEs) of 9.05 % for clean surfaces and 7.7 % for treated surfaces. Similarly, the new q”min correlation shows MAEs of 21.50 % for clean surfaces and 25.22 % for treated surfaces. While the new correlations represent a significant advancement in the development of predictive tools for cryogens, this study points to a need for more comprehensive experimental investigation of heat transfer aspects of cryogens, which will undoubtedly further improve the robustness and accuracy of the new correlations.

Consideration of fuel and oxidizer combinations for mass and volume limited hybrid rocket motors

AbstractThis research considers different storable oxidizer and fuel combinations for hybrid propulsion, looking for the most adequate candidates for mass and volume limited systems. High specific impulse Isp is the main indication for minimum mass, whereas high density specific impulse ρIsp is a good measure for smaller volume. Other aspects such as safety, handling, toxicity, burn rate, hypergolicity, and the oxidizer to fuel O/F ratio, may affect the final choice of propellant ingredient combination. For mass‐limited systems hydrogen peroxide H2O2 or nitrogen tetroxide N2O4 (the latter is toxic and hard to handle) oxidizers give the best results with most solid fuels (mainly hydroxyl‐terminated polybutadiene HTPB). For volume‐limited systems the same combinations may apply; however, in that case polyester fuel may be an adequate choice as well because of its high density. Nitrous oxide N2O is the most inadequate oxidizer for volume‐limited systems, yielding ρIsp lower by about 40 % compared to other oxidizers. Reducing the structure and insulation mass may result from decreasing the high‐pressure, high‐temperature section (the combustion chamber) and can be achieved from high O/F combinations employing N2O or H2O2 oxidizers. N2O gives relatively safe system, H2O2 enables hypergolic combinations, HNO3 is good for long‐term storage, whereas paraffin wax and expandable graphite additive yield high fuel regression rate and thrust. Overall, H2O2 oxidizer seems optimal for many operational aspects, but it should be chemically stabilized to minimize decomposition.

Nitrogen-rich covalent-organic-framework as a recyclable heterogenous catalyst for the efficient cycloaddition of carbon dioxide with epoxides

Carbon dioxide (CO2) can be chemically converted into high-value products, which is not only helps to ease the environmental problems instigated by global warming and has an optimistic effect on economies around the planet. The production of cyclic carbonates is regarded as a promising approach to convert CO2 through the cycloaddition of CO2 with epoxides. However, a major obstacle in this process is the synthesis of environmentally friendly and highly effective heterogeneous catalysts. Here, a novel nitrogen-rich covalent organic framework (CP-COF) was firstly synthesized through a polymerization method of piperazine and cyanuric chloride with 1, 4‐dioxane and used for the aforesaid reaction. A number of analytical methods were employed to verify the chemical composition and the structure of the catalyst. The CP-COF catalyst possessed a significant amount of active nitrogen sites and hydrogen bond donors in it, resulting in a high level of reactivity for the cycloaddition reaction of CO2 with epichlorohydrin in the absence of any solvent and metals, and the yield of chloropropene carbonate (CPC) reached 99 % at 110 ℃, 6 h and 1 MPa CO2 pressure. The CP-COF sample exhibited commendable activity towards a range of epoxides. Moreover, it showed high reusability for the reaction without any loss in the catalytic efficiency.

Numerical study on collapsing cavitation bubble dynamics in cryogenic fluids

The paper addresses the implementation of a dual distribution function multiphase lattice Boltzmann method (DDF-MLBM) for studying the collapse of cavitation bubbles in cryogenic liquids. The present scheme incorporates the energy equation and imposes interparticle interactions and fluid–solid adhesive forces through the exact difference method (EDM). To accurately model phase changes and the molecular complexities of cryogenic fluids like liquid hydrogen (LH2) and liquid nitrogen (LN2), the Peng-Robinson (PR) equation of state is employed along with an acentric factor. The accuracy of the present numerical technique is evaluated using the Laplace law and the Maxwell equal area construction theorem for a two-phase liquid–vapor system in equilibrium. For transient solutions, the study compares results of heterogeneous cavitation with the analytical solution derived from the thermal Rayleigh-Plesset equation. The research investigates the impact of the distance between a cavitation bubble with an adjacent solid wall on velocity, pressure, temperature, and collapse time. Furthermore, it is assessed how surface wettability influences cavitation bubble collapse intensity. Additionally, the paper examines the collapse of a cavitation bubble cluster and evaluates the effects of different physical parameters on the collapse properties of the bubble cluster. The results underscore the significant influence of the distance between cavitation bubbles in the cluster, the distance between bubbles and the adjacent solid surface on the micro-jet velocity. Moreover, it is found that increasing the contact angle of the solid surface enhances the collapse intensity and micro-jet velocity of the collapsing bubble cluster.

Soil organic matter and total nitrogen as key driving factors promoting the assessment of acid-base buffering characteristics in a tea (Camellia sinensis) plantation habitat.

The issue of soil acidification in tea plantations has become a critical concern due to its potential impact on tea quality and plant health. Understanding the factors contributing to soil acidification is essential for implementing effective soil management strategies in tea-growing regions. In this study, a field study was conducted to investigate the effects of tea plantations on soil acidification and the associated acid-base buffering capacity (pHBC). We assessed acidification, pHBC, nutrient concentrations, and cation contents in the top 0-20cm layer of soil across forty tea gardens of varying stand ages (0-5, 5-10, 10-20, and 20-40years old) in Anji County, Zhejiang Province, China. The results revealed evident soil acidification due to tea plantation activities, with the lowest soil pH observed in tea gardens aged 10-20 and 20-40years. Higher levels of soil organic matter (SOM), total nitrogen (TN), Olsen phosphorus (Olsen-P), available iron (Fe), and exchangeable hydrogen (H+) were notably recorded in 10-20 and 20-40years old tea garden soils, suggesting an increased risk of soil acidification with prolonged tea cultivation. Furthermore, prolonged tea cultivation correlated with increased pHBC, which amplified with tea stand ages. The investigation of the relationship between soil pHBC and various parameters highlighted significant influences from soil pH, SOM, cation exchange capacity, TN, available potassium, Olsen-P, exchangeable acids (including H+ and aluminum), available Fe, and available zinc. Consequently, these findings underscore a substantial risk of soil acidification in tea gardens within the monitored region, with SOM and TN content being key driving factors influencing pHBC.

Design of a mining carbon monoxide sensor and analysis of multi-gas cross-interference performance

Abstract A new type of carbon monoxide sensor is designed to address the issue of cross interference of nitrogen oxide gas in the exhaust emissions of underground diesel engine rubber-tired vehicles with electrochemical carbon monoxide sensors, which leads to frequent false alarm accidents. The hardware circuit design of the DC-DC voltage reduction power supply circuit, display circuit, component signal processing circuit, etc. is detailed, At the same time, the sensitive components used in the sensor adopt a special gas filtration membrane design. Six types of gases, including hydrogen sulfide, nitric oxide, nitrogen dioxide, hydrogen, ethylene, and acetylene, were sequentially introduced in the laboratory for experimental analysis of multi-gas cross-interference performance. The experimental results have shown that the new carbon monoxide sensor can filter out nitrogen oxide gas, thereby solving the impact of underground rubber tire vehicle exhaust on the accuracy of carbon monoxide gas detection. It has broad prospects for promotion and application in coal mines underground.

Comparative Analysis of Indoor Air Quality in Coal Mining Communities During Wet and Dry Seasons in the Coal Mining Belt of Kogi East, Nigeria

This study investigates the indoor air quality in coal mining communities during wet and dry seasons in the coal mining belt of Kogi East, Kogi State, Nigeria. The research was conducted at selected coal mining sites, specifically the Ika-Ogboyaga and Okaba mine sites, using a randomized sampling method. Indoor air quality data were collected from fifteen households in Ika and Odele villages within a 500-meter radius of the mining sites. Monitoring was performed using the Gasman autosampler to measure concentrations of nitrogen dioxide (NO₂), sulphur dioxide (SO₂), carbon monoxide (CO), hydrogen sulphide (H₂S), and particulate matter (PM₂.5 and PM₁₀). Data collection spanned 7 days each for the wet season (October 2022) and the dry season (February 2023), with measurements taken thrice daily. Meteorological parameters such as temperature, wind speed, wind direction, and relative humidity were also recorded. The results indicated higher pollutant concentrations during the dry season. For instance, PM₂.5 levels in Ika during the wet season were 45.3±0.25 μg/m³ (morning), 74.6±0.49 μg/m³ (afternoon), and 56.26±0.1 μg/m³ (evening), while dry season values were 48.32±1.74 μg/m³ (morning), 74.12±0.30 μg/m³ (afternoon), and 56.9±0.75 μg/m³ (evening). Similarly, PM₁₀ levels in Ika during the wet season were 73.61±1.44 μg/m³ (morning), 105.53±0.44 μg/m³ (afternoon), and 99.01±0.5 μg/m³ (evening), whereas dry season values were 75.47±0.70 μg/m³ (morning), 102.08±1.48 μg/m³ (afternoon), and 96.98±1.33 μg/m³ (evening). CO concentrations in Ika during the wet season were 4.22±0.22 ppm (morning), 6.13±0.3 ppm (afternoon), and 3.1±0.05 ppm (evening), and during the dry season, they were 5.55±1.74 ppm (morning), 8.11±1.46 ppm (afternoon), and 7.04±1.184 ppm (evening). Meteorological analysis showed that the dry season had higher wind speeds (2-4 m/s) compared to the wet season (0-2 m/s), and lower relative humidity (mean of 51.18%) compared to the wet season (mean of 77.55%). Air Quality Index (AQI) values indicated that PM₂.5 levels in both seasons were unhealthy (155.8-156.4 in the wet season and 151-200 in the dry season), while PM₁₀ levels were moderate (65.5-66.9 in the wet season and 51-100 in the dry season). CO, NO₂, and SO₂ levels generally remained within permissible limits set by the World Health Organization (WHO). Statistical analysis revealed significant seasonal variations in the concentrations of the monitored pollutants, with higher levels typically recorded during the dry season.

Investigations of the growth and physical characteristics of ZNF2-DOPED GA2O3 thin films

This study began by preparing gallium oxide (Ga2O3) doped with zinc fluoride (ZnF2) and manufacturing a target material. Subsequently, electron beam (e-beam) deposition was employed to coat silicon substrates with the prepared material. Different heat treatment conditions were applied to the deposited films, followed by material and electrical property analyses. The investigation explored the impact of pre-sintering Ga2O3 at 950°C to transform it into a more stable [Formula: see text]-phase. For comparative purposes, some samples underwent annealing at 600°C in a nitrogen–hydrogen (95% N[Formula: see text] H2, abbreviated as N[Formula: see text]) mixed gas, which was used as a reduction atmosphere, to increase oxygen vacancies in the ZnF2-doped Ga2O3 thin films and consequently enhance their conductivity. The deposited ZnF2-doped Ga2O3 thin films initially exhibited an amorphous phase, with diffraction peaks appearing only after a 600°C annealing process. Pre-sintering Ga2O3 powder at 950°C promoted the emergence of the [Formula: see text]-phase, and the bandgap value increased after annealing. Measurements using B1500A revealed that sintering and annealing ZnF2-doped Ga2O3 thin films were essential steps to enhance their conductivity. X-ray photoelectron spectroscopy (XPS) further confirmed a significant correlation between the conductivity variation and the concentration of oxygen vacancies. Additionally, it was observed that the use of an N[Formula: see text] mixed gas further increased the presence of oxygen vacancies in the films. The results of this study provide an important method to make Ga2O3 thin films with conductivity, which can be utilized in the fabrication of Ga2O3 thin-film-based semiconductor devices in the future.