Gas Mixture Research Articles

DOCOL 1100M WELDING IN THE CONSTRUCTION OF ELECTRIC MEANS OF TRANSPORT

Advanced high-strength steels are important for the automotive sector. Metal active gas (MAG) is the most popular method for joining grades of steel. The goal of the paper is to analyze the mechanical properties of the MAG welding joint made of high-strength DOCOL 1100M intended for the construction of electric vehicles. The manuscript shows a basic understanding of the properties of DOCOL joints. This type of material is characterized by a martensitic microstructure, which makes it difficult to make a proper joint. The tensile strength, metallographic structure, and type of non-metallic inclusions were analyzed as a function of the oxygen amount in the protective gas mixture. Investigations of oxide non-metallic inclusions were carried out using scanning electron microscopy. This article attempts to obtain high joint strength of the electric vehicle structure by controlling the average size of non-metallic inclusions in the weld, which is influenced by shielding gas in the MAG welding process. The solution has application potential for the automotive industry, especially for electric vehicles.

The dual action of N2 on morphology regulation and mass-transfer acceleration of CO2 hydrate film

The morphology characteristics of CH4, CO2 and CO2+N2 hydrate film forming on the suspending gas bubbles are studied using microscopic visual method at supercooling conditions from 1.0 to 3.0 K. The hydrate film vertical growth rate and thickness along the planar gas-water interface are measured to study the hydrate formation kinetics and mass transfer process. Adding N2 in the gas mixture plays the same role as lowering the supercooling conditions, both retarding the crystal nucleation and growth rates, which results in larger single crystal size and rough hydrate morphology. N2 in the gas mixture helps to delay the secondary nucleation on the hydrate film, which is beneficial to maintain the pore-throat structure and enhance the mass transfer. The vertical growth rate of hydrate film mainly depends on the supercooling conditions and gas compositions but has weak dependence with the experimental temperature and pressure. Under the same gas composition condition, the final film thickness shows a linear relationship with the supercooling conditions. The mass transfer coefficient of CH4 molecules in hydrates ranges from 4.54 to 7.54×10–8 mol·cm–2·s–1·MPa–1. The maximum mass transfer coefficient for CO2+N2 hydrate occurs at the composition of 60% CO2+40% N2, which is 3.98×10–8 mol·cm–2·s–1·MPa–1.

The roles of different migration mechanisms in the transport of H2O–CH4 gas mixture in shales

Studying the roles of different migration mechanisms in shale matrix gas transport is beneficial for shale gas extraction and CO2 sequestration. The roles of different transport mechanisms in shale H2O–CH4 gas mixture transport were investigated considering their contributions to fluid flux. A permeability model coupling multiple gas migration mechanisms was developed by combining the pore network-related effective medium approximation, which was validated using process data from simultaneous H2O–CH4 transport in shales. The results showed that the gas transport mechanisms dominating methane and water vapor migration in shale differed. Slip flow and Knudsen diffusion contributed approximately 99% to methane migration. Water vapor surface diffusion as well as slip flow and Knudsen diffusion primarily contributed to the water vapor permeability before and after a time point, respectively. Water vapor and methane permeability generally decreased with time. The equilibrium water vapor and methane permeabilities ranged from 2.7699×10−22–12.312×10−22 m2 and 0.2640×10−21–4.9036×10−21 m2, respectively. The methane surface diffusion permeability increased slowly with time before approaching methane monolayer adsorption (before ∼100 s). An increase in relative humidity (approximately 300–3600 s) can promote the transport of water vapor. Water vapor and methane adsorption, especially the condensation of adsorbed water, could largely explain the decrease in shale gas permeability.

Numerical investigation of hydrogen ignition induced by unsteady flow phenomena

The purpose of the present study is to evaluate the possibility of using a gas dynamic heater as an igniter of the combustible gas mixtures. The impacts of some operating and geometrical parameters on average temperature of the gas dynamic heater are investigated by numerical simulation of axisymmetric turbulent flow in the resonance tube. The operating gas of the heater is air which is completely decoupled from the ignition chamber. The combustible mixtures under consideration is stoichiometric hydrogen-oxygen at atmospheric pressure, in which the ignition is studied solving the governing equations for one dimensional reacting flow using detailed chemistry. The finite volume method is used in the presently developed flow solver for numerical simulations. The results show that despite highly fluctuating temperature of the end wall of the resonance tube as a hot surface, it can provide proper condition for gas mixture ignition in the chamber, by adjusting an inlet pressure and geometry of the gas dynamic heater. The end wall average temperature depends on the nozzle inlet pressure and convergence angle of the resonance tube, and the results demonstrate that the characteristics of temperature time history of repeating cycles are so effective on ignition process.

Understanding adsorption selectivity in zirconium-pillared clays for biogas upgradation: the role of metal/clay ratio.

Biogas, as a sustainable energy source, encounters challenges in practical applications due to impurities, notably carbon dioxide (CO2), and nitrogen (N2). This study investigates the effect of metal/clay ratio on the adsorption selectivity of porous zirconium-pillared clay adsorbents for biogas upgradation. Comprehensive analyses including nitrogen adsorption/desorption, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) were conducted to evaluate the physicochemical properties. Adsorption properties for Zr-pillared clays for biogas components such as CO2, CH4, and N2, at 25 °C under different pressures were investigated. The ideal adsorbed solution theory (IAST) was employed to assess selectivity for three binary gas mixtures (CO2/CH4, CO2/N2, and CH4/N2). Results revealed the substantial impact of Zr/Clay ratio on both adsorption capacity and selectivity of the prepared materials. For instance, the maximum adsorption capacity of gases varies as ZrPILC-4 > ZrPILC-2 > ZrPILC-8 > ZrPILC-1, whereas the adsorption selectivity for CO2/CH4 separation (at 1000kPa) varies as ZrPILC-1 > ZrPILC-2 > ZrPILC-8 > ZrPILC-4. Interestingly, the ZrPILC-8 with maximum surface area (147 m2∙g-1) did not show maximum adsorption capacity for all the three gases, which was attributed to its lower pore volume, and basal spacing, as compared to ZrPILC-4. Amongst all the pillared samples, the ZrPILC-1 exhibited highest selectivity for all binary mixtures (at 1000kPa), signifies increased nonspecific interactions due to its lower surface area. Its separation performance, particularly for CO2/CH4 mixture exceeded that of the parent clay by 1.5 times. A significant increase in the working capacity of the prepared samples underscores the efficacy of these pillared materials in separating biogas components. This study provides valuable insights into effects of Zr/clay ratio for developing robust pillared adsorbents, contributing to the advancement of sustainable biomethane production.

Self-Modification of Defective TiO2 under Controlled H2/Ar Gas Environment and Dynamics of Photoinduced Surface Oxygen Vacancies.

In recent years, defective TiO2 has caught considerable research attention because of its potential to overcome the limits of low visible light absorption and fast charge recombination present in pristine TiO2 photocatalysts. Among the different synthesis conditions for defective TiO2, ambient pressure hydrogenation with the addition of Ar as inert gas for safety purposes has been established as an easy method to realize the process. Whether the Ar gas might still influence the resulting photocatalytic properties and defective surface layer remains an open question. Here, we reveal that the gas flow ratio between H2 and Ar has a crucial impact on the defective structure as well as the photocatalyic activity of TiO2. In particular, transmission electron microscopy (TEM) in combination with electron energy loss spectroscopy (EELS) revealed a larger width of the defective surface layer when using a H2/Ar (50 %-50 %) gas mixture over pure H2. A possible reason could be the increase in dynamic viscosity of the gas mixture when Ar is added. Additionally, photoinduced enhanced Raman spectroscopy (PIERS) is implemented as a complementary approach to investigate the dynamics of the defective structures under ambient conditions which cannot be effortlessly realized by vacuum techniques like TEM.

Consuming the redundant renewable energy by injecting hydrogen into the gas network: A case study of electricity-gas-hydrogen coupled system of Ireland

Converting surplus electricity into hydrogen is considered a promising way for accommodating large-scale wind or solar power. However, it is expensive to establish a new-built hydrogen network or storage facilities at the current stage. Hydrogen-enriched compressed natural gas (HCNG), a mixture of natural gas and hydrogen, can be an alternative approach to consuming surplus renewable energy in the short-medium term. This paper investigates the feasibility of establishing an electricity-gas-hydrogen coupled energy system by modeling the HCNG network, power grid, and hydrogen electrolyzer in Ireland with consideration of pipeline characteristics. The economic analysis based on the planning results of the coupled system is presented in detail. When the hydrogen injection ratio reaches 20% at the HCNG stations, the system operating cost and carbon emission can be reduced by 24.2% and 6.4%, and 100% wind can be consumed.

An olfactory figure-ground segregation: The resistance fluctuation analysis of acetone gas for acetone/random gas mixtures recognition

Recognizing the disease-specific odor in human breath is a feasible non-invasive disease detection strategy. The most critical issue of olfactory diagnosis lies in recognizing the target gas among complex respiration compounds accurately. This paper demonstrated a novel approach to binary gas mixture recognition, exploring nature-related features of the target “odor object” (acetone gas) regardless of its “noisy background” (ethanol or methanol gases). Those features were extracted from time-series resistance fluctuations collected with one conventional SnO2 thin film gas sensor (TF) or our sensitivity-controllable lines gas sensor (TL). 6 features (variance, root mean square, band power, relative band power, entropy, and the number of values crossing mean value) were selected and analyzed with k-Nearest Neighbor regressor (KNN) and Support Vector Regressor (SVR). 18 types of acetone/ethanol mixtures and 3 acetone/methanol mixtures were tested with the proposed models and further explained with SHAP (SHapley Additive exPlanations). The model of TL and KNN achieved the optimal performance of regressing acetone concentrations with the coefficient of determination (R2) of 0.97 and 0.95 in individual gas and binary gas mixtures, respectively. Entropy was found to be the key feature that was linked to sensor properties. Finally, acetone gas data mixed with simulated gas and random noise data were experimented to evaluate our models’ potential for acetone/random gas mixture recognition and robustness.

Variation Law of Hybrid Explosion Characteristic Parameters of Gas and Coal Dust Coupled with Multiple Factors.

This study aims at extensively investigating the explosion characteristics of a hybrid mixture of gas and coal dust. Accordingly, the standard 20 L spherical explosion system was applied to measure parameters such as the lower explosion limit, maximum explosion pressure, and index of the hybrid mixture of different concentrations of gas and coal dust. Moreover, different coal dust particle sizes and components were measured. With regard to coal dust with different particle sizes and components, the obtained results revealed that, while the addition of gas significantly reduced the lower explosion limit, the maximum explosion pressure and index were increased; that is to say, the presence of gas will increase the explosion risk of coal dust. However, under conditions in which the particle size of the coal dust was large or the volatile content was low, the addition of gas was found to lead to a higher decrease of the lower explosion limit; this is, while the maximum explosion pressure and explosion index were increased. Consequently, gas can be argued to have a greater influence on the explosion risk of coal dust with a large particle size or low volatile content. Furthermore, regardless of the particle size or the volatile content of coal dust, the maximum explosion pressure and explosion index of the hybrid mixture were observed to be higher than that of the pure coal dust but lower than that of the pure gas. That is to say, the explosion intensity of the gas/coal dust composite system is higher than that of pure coal dust but less than that of pure gas. The research results can provide theoretical basis for coal mine explosion disaster prevention and control and have important significance.

IMPROVING THE TEMPERATURE IN THE METAL CONVERTER AGGREGATE, WITH USING OF THE MULTI-TIERED TUYERE

The oxygen-converter method is the most common of the industrial production of steel in both Ukraine and the world. According to scientific and statistical sources, from 2017 the fate of oxygen-converting steel in the Ukraine was more than 70 % of the total steel production. To date, in the face of invasion of our sovereign state and a full-scale liberation war in Ukraine, the metallurgical enterprises operating with the oxygen converting way of obtaining steel has conditions for significant resource limitations and increasing the cost of energy, fuel resources. Therefore, there is a need for technological solutions that will increase the energy efficiency of blowing in the bath of converter without the use of external fuel resources and energy. Accordingly was developed and tested in the laboratory with physical high temperature modeling, of the tuyere with multi-tiered construction. The developed technological solution allows to organizeted blowing in the melt for help of supersonic oxygen jets through Laval’s nozzles and forming torches flame of the {CO} to {CO2}, which directly act on the surface of the melt, due to their formation with curtain sonic oxygen jets, who organizated with help of two separate groups of the cylindrical nozzles. Thanks to the video and photography and chemical selection of the melt samples, out gases from the converter and the measurement of the melt temperature, during the entire purification blowing of the melt, established the peculiarities of the conversion of the melt with using of the multi-tiered tuyere in the space of the converter bath. It is confirmed that with the use of the multi-tiered tuyere the course of converting of the melt, as with the classical multi-nozzle tuyere, consists of three main technological periods: the first — slag formation and “ignition of the melt”; the second — intense carbon oxidation; the third — getting of final chemical composition and temperature of the melt. It is established that the main difference in the use of multi-tiered tuyere lies in the more intensive begining and progress of thermodynamic, hydrogasodynamic and cerculation heating processes, along with the appearance of forming torches flame of the {CO} to {CO2} from the moment of “ignition of the melt”. Directly burning {CO} to {CO2} in a mixture of waste gases leads to a release of the large amount of heat 565 kJ/mol O2. At the same time, it should be noted that the temperature during burning {CO} to {CO2} in a mix of the waste converter gases with oxygen streams reaches up to 3000 °C in a created combustion flame torch. The predominant formation of the flame torches {CO} to {CO2} was observed after the “ignition of the melt” at the first period at the expense a lower group of cylindrical nozzles. The highest intensity of the formation of the flame torches {CO} to {CO2} was obtained in the second period at the blowing in the melt in the conditions of intense oxidation of carbon of melt, until the carbon in the melt was from 1.2 % to 0.9 % it is value of the transition concentration. Formation of the flames torches {CO} to {CO2} was be for all sonic jets from cylindrical nozzles of the lower and upper block of the blowing. At the same time, the location of the blowing blocks and the angle of inclination of the cylindrical nozzles to the vertical axis of the multi-tiered tuyere in these blocks are calculated so as to ensure the interaction of the flames torches {CO} to {CO2} with the layers of melt and transfer up to 65 % of the heat formed from flames torches {CO} to {CO2} to the melt. It is established that the use of the multi-tiered tuyere with group of Laval’s nozzles and two groups of cylindrical nozzles was use to create sonic oxygen jets, that allows increases the burning {CO} to {CO2} in the range from 29 % to 43 %, it is exceeding corresponding indicators with the use of a two-tiered tuyere in the range of 14 % to 28 %, and compared to the multi-nozzles tuyere of the classic conctruction from 24 % to 38 %. At the same initial temperature of liquid cast iron and other conditions in laboratory experiments of the high-temperature physical modeling with using a multi-tiered tuyere with group Laval’s nozzels and with two groups of cylindrical nozzles for blowing, the finaly temperature of the liquid semiproduct of the steel was higher comparatively with use classic multi-nozzles tuyere, only thanks to increasing burning {CO} to {CO2} without the use of external fuel resources and energy during blowing of the melt. Accordingly, this indicates an improvement in the energy efficiency of the converter process with helps of the multi-tiered tuyere. Bibl. 23, Fig. 4.

CLIMATE AND ENVIRONMENTAL BACKGROUNDS OF FUEL UTILIZATION, INFLUENCING UPON ALTERATION THE EUROPEAN AND UKRAINIAN TRENDS OF GAS SUPPLY. PART 2. PROVIDING THE EFFICIENCY OF FUEL USE IN CONDITIONS OF DECARBONIZATION OF ENVIRONMENT

The paper is dedicated to power and environmental aspects of option the most appropriate types of fuel for supplying the economics of European countries and Ukraine. Accordingly notions about influence of C-containing fuels on greenhouse effect and on warming of environment, the existing tendency of substitution the fossil fuels — generally — and the natural gas — particularly — for methane-hydrogen mixtures is discussed as a controversial point. The problem of advancement the national fuel complexes is under consideration and has been studied with approach based upon the example of Ukrainian pre-war state of economics. An attention has been paid up on reduction of production and consumption of all types of the fossil fuels in the last decades, mainly due lowering the industrial using constituent. An enhancement of fuel using efficiency due improvement of furnace equipment basis provides an successive solution the fuel problems. The thermodynamic background for evaluation the efficiency of fuel using with account of the furnace’s non-ideality has been developed. The problem of “wet combustion” takes of special significance by the reason of weather and climate conditions’ account, on the one hand, and an opportunity to control the efficiency of fuel using, on the other hand, with new combined technique. The contemporary approach consists in combination the direct method of decrease the CO2 emission due exclusion of using the C-containing fuels (firstly — the fossil fuels) and with enhancement the efficiency of using the fossil fuels, for example due erection the recuperative heat recovery facilities with preliminary preheating of combustion air, in some advanced cases by combination with an air, humidification. The perspective ways of provision the decarbonization of environment consists in substitution the fossil fuels (mainly the natural gas NG) for hydrogen or H2-containing gas mixtures. The thermodynamic analysis of relevant technique has been carried out to estimate the opportunities of control the efficiency of hydrogen admixture to NG. Taking into account the variety of technologies of hydrogen production, the engineering method with giving of conditional coloration of hydrogen as a fuel has been considered. The “green” H2 makes the most valuable type of fuel (compared with “blue”, “turquoise”, “yellow”, “rose” colored and especially to the “grey” H2) as a substituting fuel from the standpoint of H2 fitness to process and plant. Particularly for high-temperature melting furnaces a provision of maximum emissivity of flame requires an using of carbon containing fuels to organize thermal pyrolysis of gas and soot formation within the combustion zone. Ref. 44, Fig. 5, Tab. 3.

STUDY ON KINETICS OF BIOMASS PYROLYSIS IN THE FIXED BED. 2. ANALYSIS OF THE RESULTS OF CALCULATING THE THERMAL DECOMPOSITION OF DIFFERENT TYPES OF SOLID FUEL

Using the constructed non-stationary model of the dynamics of the release of volatile substances in a fixed bed [1], extensive numerical studies on three types of biomass pyrolysis Wood Birch, Wood quebracho and Bagasse were performed in order to determine the light gas composition satisfactorily coinciding with experimental data. As a result of research, the following composition of light gas (in mass fractions) was determined for the first time: CO = 0.464, CO2 = 0.101, H2 = 0.01, H2O = 0.23, C6H6.2O0.2 = 0.058, and C1.16H4 = 0.137, which differs from the light gas composition given in modern sources copies [2−4] (in mass fractions): CO = 0.396, CO2 = 0.209, H2 = 0.019, H2O = 0.249, and C6H6.2O0.2 = 0.127 [3], also CO = 0.46, CO2 = 0.08, H2 = 0.015, H2O = 0.23, C6H6.2O0.2 = 0.058, and CH4 = 0.157 [2]. Obtained calculation results for Wood quebracho with refined composition of light gas in terms of dry mass at a temperature of 800 °С: H2 = 15.56 %, CO2 = 7.134 %, CO = 51.4 %, C1.16H4 = 23.71 % (CH4 = 16.6 %, C2H4 = 7.46 %), and C6H6.2O0.2 = 2.21 % — agree satisfactorily with the experimental data. At the exit from the retort, mixed pyrolysis gas composition changes little over time and differs in the values of the gas components from the pyrolysis gases compositions obtained in the elementary volumes of the retort. This discrepancy is explained by the fact that the initial gas mixture contains components obtained at low temperatures with a high content of H2 and CO2 and a low concentration of CO and C1.16H4. Bibl. 20, Fig. 11, Tab. 4.

Implementation of various injection rate shapes in an ammonia/diesel dual-fuel engine with special emphasis on combustion and emissions characteristics

As the problem of global warming continues to intensify, carbon-free fuel ammonia is crucial for internal combustion engines, and a potential ammonia combustion route is dual-fuel mode. The impact of various injection rate shapes (trapezoid, wedge, slope, triangle, and rectangle) on engine combustion and emissions performance with 0 %, 20 %, and 40 % ammonia energy fractions were estimated. Under the identical ratio of the ammonia-doped schemes, the fuel injection gross mass and fuel injection duration are the same. The results indicate that the triangle injection rate shape can make the mixture of diesel and ammonia gas more uniform, leading to combustion in the combustion chamber closer to homogeneous combustion. When the injection shape is the triangle, the indicated mean effective pressure in the cylinder is the highest at 10.29 bar, which is 4.04 % higher than that of the pure diesel original injection shape. The triangle injection shape makes the ammonia-diesel dual fuel burn more concentrated, resulting in lower unburned ammonia loss and higher thermal efficiency. Under the 40 % ammonia energy fraction and triangle injection shape, the highest thermal efficiency reaches 40.57 %, 1.58 % higher than the pure diesel original injection shape. Additionally, it significantly reduces unburned ammonia emissions. The injection rate shapes have a minor impact on CO2 emissions. The rapid increase in-cylinder average temperature can substantially reduce N2O emissions, thereby lowering total greenhouse gas emissions. Among them, the total greenhouse gas emissions of 40 % ammonia energy fraction and triangle injection shape are the lowest, at 81619 ppm, which is 11.3 % lower than that of pure diesel original injection shape. On the contrary, it will increase NOx emissions. Conversely, the slopes exhibit the lowest NOx emissions at 220.8 ppm, representing an 88 % reduction compared to the pure diesel original injection shape.

External and internal ignition of a hydrogen-air gas mixture induced by a recombiner

External and internal ignition of a hydrogen-air gas mixture induced by a recombiner

Pressure swing adsorption of Li exchange hierarchical X zeolite for pure hydrogen from binary gas mixture

This study reports the separation of pure hydrogen (H2) employing pressure swing adsorption (PSA). The Li-X and Li-hierarchical X (Li–H-X) zeolite were prepared by an ion exchange process. The sorbents were evaluated through several experiments including, breakthrough, empty bed contact time (EBCT), single-bed, and two-bed PSA with different steps. The effect of pressure, purity, and recovery relationship was developed. The high-pressure PSA study was performed at 4, 6, and 10 bar with varying feed flow rates to assess their efficacy in pure H2 separation using binary gas stream (H2/CO2, 75/25 vol.%). The breakthrough adsorption capacity of Li–H-X exhibited 3.4 mmol g−1 and 0.212 mmol g−1 of CO2 and H2, respectively. Li–H-X shows ∼8% higher CO2 sorption capacity than the Li-X sorbent at 1 bar and 300 K due to the large meso-microporous structure of the sorbent. The two-bed PSA purity and recovery were found higher than single-bed PSA. Using two-bed PSA, the Li–H-X achieved a 99.5% of purity, 92.9% of recovery, and 10.4 mL min−1 g−1 of productivity, which was ∼16% higher recovery and productivity than single-bed PSA at a flow rate of 1200 mL min−1 at 6 bar. With increasing the pressure and flow rate, the recovery of Li–H-X was enhanced up to 93.7% with 99.1%–99.9% H2 purity. The long-term PSA was run using Li–H-X sorbent for 7.5 h with 230 cycles with H2 purity between 98.5 and 99.5% at 6 bar. Interestingly, the adsorbent shows the scalability of PSA for efficient H2 separation for a binary mixture of H2/CO2.

In-flight iron ore reduction and nanoparticle formation in an atmospheric pressure hydrogen microwave plasma

The in-flight reduction of iron ore particles using an atmospheric pressure hydrogen plasma is investigated. Iron ore particles with a size less than 75 µm are aerosolized and carried with an argon-hydrogen (90%–10%) gas mixture through an atmospheric pressure microwave plasma. After the treatment, the collected particles are observed to follow three distinct populations: (i) fully reduced nanoparticles, (ii) partially reduced spheres, larger than the feedstock, and (iii) partially melted, partly reduced agglomerates. A model is developed to explain the possible mechanism for the origin of the three populations. The nanoparticles (i) are found to be likely formed from the previously evaporated material whereas the particles (ii) and (iii) result from the partial/complete melting of the particles and agglomerates flowing through the reactor. The gas temperature is estimated to be more than 2000 K, which enables the rapid melting, evaporation, and reduction of these particles within residence times of only a few 10 ms.

AI-Enabled Portable E-Nose Regression Predicting Harmful Molecules in a Gas Mixture.

The biomimetic electronic nose (e-nose) technology is a novel technology used for the identification and monitoring of complex gas molecules, and it is gaining significance in this field. However, due to the complexity and multiplicity of gas mixtures, the accuracy of electronic noses in predicting gas concentrations using traditional regression algorithms is not ideal. This paper presents a solution to the difficulty by introducing a fusion network model that utilizes a transformer-based multikernel feature fusion (TMKFF) module combined with a 1DCNN_LSTM network to enhance the accuracy of regression prediction for gas mixture concentrations using a portable electronic nose. The experimental findings demonstrate that the regression prediction performance of the fusion network is significantly superior to that of single models such as convolutional neural network (CNN) and long short-term memory (LSTM). The present study demonstrates the efficacy of our fusion network model in accurately predicting the concentrations of multiple target gases, such as SO2, NO2, and CO, in a gas mixture. Specifically, our algorithm exhibits substantial benefits in enhancing the prediction performance of low-concentration SO2 gas, which is a noteworthy achievement. The determination coefficient (R2) values of 93, 98, and 99% correspondingly demonstrate that the model is very capable of explaining the variation in the concentration of the target gases. The root-mean-square errors (RMSE) are 0.0760, 0.0711, and 3.3825, respectively, while the mean absolute errors (MAE) are 0.0507, 0.0549, and 2.5874, respectively. These results indicate that the model has relatively small prediction errors. The method we have developed holds significant potential for practical applications in detecting atmospheric pollution detection and other molecular detection areas in complex environments.

Performance of a Wearable Ring in Controlled Hypoxia: A Prospective Observational Study.

Over recent years, technological advances in wearables have allowed for continuous home monitoring of heart rate and oxygen saturation. These devices have primarily been used for sports and general wellness and may not be suitable for medical decision-making, especially in saturations below 90% and in patients with dark skin color. Wearable clinical-grade saturation of peripheral oxygen (SpO2) monitoring can be of great value to patients with chronic diseases, enabling them and their clinicians to better manage their condition with reliable real-time and trend data. This study aimed to determine the SpO2 accuracy of a wearable ring pulse oximeter compared with arterial oxygen saturation (SaO2) in a controlled hypoxia study based on the International Organization for Standardization (ISO) 80601-2-61:2019 standard over the range of 70%-100% SaO2 in volunteers with a broad range of skin color (Fitzpatrick I to VI) during nonmotion conditions. In parallel, accuracy was compared with a calibrated clinical-grade reference pulse oximeter (Masimo Radical-7). Acceptable medical device accuracy was defined as a maximum of 4% root mean square error (RMSE) per the ISO 80601-2-61 standard and a maximum of 3.5% RMSE per the US Food and Drug Administration guidance. We performed a single-center, blinded hypoxia study of the test device in 11 healthy volunteers at the Hypoxia Research Laboratory, University of California at San Francisco, under the direction of Philip Bickler, MD, PhD, and John Feiner, MD. Each volunteer was connected to a breathing apparatus for the administration of a hypoxic gas mixture. To facilitate frequent blood gas sampling, a radial arterial cannula was placed on either wrist of each participant. One test device was placed on the index finger and another test device was placed on the fingertip. SaO2 analysis was performed using an ABL-90 multi-wavelength oximeter. For the 11 participants included in the analysis, there were 236, 258, and 313 SaO2-SpO2 data pairs for the test device placed on the finger, the test device placed on the fingertip, and the reference device, respectively. The RMSE of the test device for all participants was 2.1% for either finger or fingertip placement, while the Masimo Radical-7 reference pulse oximeter RMSE was 2.8%, exceeding the standard (4% or less) and the Food and Drug Administration guidance (3.5% or less). Accuracy of SaO2-SpO2 paired data from the 4 participants with dark skin in the study was separately analyzed for both test device placements and the reference device. The test and reference devices exceeded the minimum accuracy requirements for a medical device with RMSE at 1.8% (finger) and 1.6% (fingertip) and for the reference device at 2.9%. The wearable ring meets an acceptable standard of accuracy for clinical-grade SpO2 under nonmotion conditions without regard to skin color. ClinicalTrials.gov NCT05920278; https://clinicaltrials.gov/study/NCT05920278.

Comparative Analysis of Particulate Content in Cigarette Smoke: Implications for Respiratory Health of Active and Passive Smokers

Cigarette smoke is a heterogeneous mixture of gases, uncondensed vapours and liquid particulate matter with millions of particles per cubic centimetre. Cigarette smoking can negatively impact the health of smokers and non-smokers. As such, there is a need to constantly assess the quantity of toxic substances emanating from smoking cigarettes. This study investigated the total amount of particulates to which smokers and non-smokers are exposed and identified the chemical compositions of total particulates in cigarette smoke from some selected cigarette brands obtained from Nagongera town council shops in Uganda. To achieve this, we made use of an apparatus that mimics the smoking process of a human being and a passive smoker by connecting this set to another set-up containing a cigarette to be burnt. Qualitative tests for chemical composition were conducted using conventional tests for organic functional groups. It was found that Sportsman and locally cured tobacco had the highest total particulate content (116 mg and 73 mg) while Supermatch and Safari had the lowest total amount of particulates 45.5 mg and 40.3 mg, respectively. The investigated cigarettes were found to be composed of the following functional groups: aromatics, phenolics, nitrosamines and alkaloids. However, aldehyde and ketonic groups were not identified. The cigarette composition results in cigarette smoke composition either in the mainstream or the side stream causing disease to a respiratory system like lung cancer, emphysema and cancers in the mouth cavity and oesophagus. This study confirmed that the brand of cigarette smoked could determine the quantity of particulate smokers and non-smokers of cigarettes might be exposed to and that functionalities and/or chemical compositions vary amongst Ugandan cigarette brands

On the CO2 Harvesting from N2 Using Grazyne Membranes.

The separation of carbon dioxide (CO2) from nitrogen (N2) is at the core of any global warming remediation technology aimed at reducing the CO2 content in the atmosphere. Chemical membranes designed to differentially permeate both molecules have become quite appealing due to their simple use, although many membrane-based separations stand out as a promising solution for CO2 separation. These are environmentally friendly, with high active surface areas, compact design, easy to maintain and cost-effective, although the field is still growing due to the difficulties in the CO2/N2 separation. The present study poses grazynes, two-dimensional C-based materials with sp and sp2 C atoms, aligned along stripes, as suited membranes for the CO2/N2 separation. The combination of density functional theory (DFT) and molecular dynamics (MD) simulations allow tackling the energetics, kinetics, and dynamics of the membrane effectiveness of grazynes with engineered pores for such a separation in a holistic fashion. The explored grazynes are capable of physisorbing CO2 and N2, thus avoiding material poisoning by molecular decoration, while the diffusion of CO2 through the pores is found to be rapid, yet easier than that of N2, in the rate order of the s-1 in the 100-500 K temperature range. In particular, low-temperature CO2 separation even for CO2 contents below 0.5 % are found for [1],[2]{2}-grazyne when controlling the membrane exposure contact to the gas mixture, paving the way for exploring and using grazynes for air CO2 remediation.