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The microwave electrothermal thruster (MET) utilizes wave-exited microdischarges to heat gas flows, enhancing the specific impulse of the thruster. Our computational study investigates a 17.5 GHz helium-propellant MET, employing a two-dimensional, axisymmetric fluid model of plasma coupled with electromagnetic wave and gas flows. The discharges operate in the glow regime, remaining weakly ionized, and in thermal non-equilibrium. The plasma densities reach approximately 10 20 m − 3 , and the gas temperature is around 2000 K. Even a slight off-resonant frequency operation results in a significantly lower plasma density and gas temperature. Gas heating, primarily driven by electromagnetic Joule heating, plays a critical role in influencing the overall discharge behavior. The measured peak thrust and specific impulse are 8.24 mN and 292 s, respectively, at a mass flow rate of 3.2 mg/s with 30 W of power. Compared to a cold gas thruster, there is a significant increase in the specific impulse by a factor of approximately 1.7. The enhanced performance trades off with propulsive efficiency, which decreases by a factor of 1.5 from the peak 65% at 10 W. This is due to higher energy losses to cavity walls from heat conduction with increased power. These findings underscore the critical balance between the input power and mass flow rate to improve the MET performance, highlighting the importance of power management to maximize thrust and efficiency. Furthermore, the predicted thrust and specific impulse agree well with experimental values for nominally similar MET thruster studies in the literature. [ABSTRACT FROM AUTHOR]

Photothermal spectroscopy, and more specifically photothermal interferometry (PTI), is a highly sensitive technique for measuring gas and aerosol concentrations. Numerous implementations of different PTI configurations have demonstrated the versatility of the technique. This theoretical study presents a comprehensive analysis and an optimization of the PTI optical path length (OPL) amplitude using characteristic times. We investigate how the OPL amplitude depends on the dimensions and orientations of the interferometer laser beam and the continuous-wave excitation laser beam. This analysis quantifies the impact of advection on the OPL amplitude based on the relative orientation of the two laser beams and the gas flow direction. It is analytically shown that the possibilities for photothermal OPL amplitude optimization are limited when thermal diffusion is dominant. Theoretically, advection has the potential to double or cancel the OPL amplitude, depending on the specific configurations. In summary, we provide an in-depth understanding of the design and parameter considerations required when tailoring and optimizing a PTI sensor for different fields of applications. [ABSTRACT FROM AUTHOR]

Equilibrium thermodynamics describes the energy exchange of a body with its environment. Here, we describe the global energy exchange of an ideal gas in the Coutte flow in a thermodynamic-like manner. We derive a fundamental relation between internal energy as a function of parameters of state. We analyze a non-equilibrium transition in the system and postulate the extremum principle, which determines stable steady states in the system. The steady-state thermodynamic framework resembles equilibrium thermodynamics. [ABSTRACT FROM AUTHOR]

We demonstrate similarity rules for inductively coupled plasmas with thermohydrodynamic coupling effects using two-dimensional fluid simulations and theoretical analyses of the gas flow and heat transfer equations. The results confirm the validity of conventional similarity laws, e.g., the similarity relation for electron density, which can be violated by the nonlinear gas heating effects from exothermic and endothermic reactions. The nonlinear gas heating can obviously perturb the invariance of spatial distributions of the gas flow velocity, resulting in the electron density decreasing nonproportionally with different scaling factors. Adding an external heat source can mitigate the violation of the gas temperature scaling law, thus maintaining the validity of similarity relations to some extent. In addition, two kinds of scaling relations for excited-state argon atoms are identified with and without the consideration of nonlinear collisions. [ABSTRACT FROM AUTHOR]

In this study, we developed a shallow defect layer formation process using moderate-pressure H2 plasma at 3.3 kPa for an extrinsic gettering layer of ultra-thin Si chips aimed at three-dimensional integrated circuits. This process can be conducted in the presence of trivial amounts of air impurities (∼0.01 vol. %), thereby avoiding the use of high-vacuum equipment. We investigated the dependence of defect formation behavior on various processing parameters such as H2 flow rate, processing time, substrate temperature, and input power. It was determined that the absence of H2 gas flow was favorable for the defect layer formation because Si etching by hydrogen atoms was suppressed. A low Si temperature and high input power are desirable for a high defect density in the shallow surface region of the extrinsic gettering layer. When pulse-modulated plasma irradiation was attempted, the defect layer that formed became thinner and had a higher defect density than that obtained by continuous plasma, demonstrating good Cu gettering performance. Without using harmless chemicals, or high-cost equipment, a shallow gettering layer can be formed using inexpensive H2 gas. [ABSTRACT FROM AUTHOR]

In this research, zinc sulfide (ZnS) nanostructure powder was successfully synthesized via two-stage annealing (Ar + H 2 S). The annealing under argon medium was responsible for eliminating impurities such as SO 4 , SO 3 and SO 2. The annealing under hydrogen sulfide (H 2 S) medium also led to compensation of sulfur and establishment of Zn to S stoichiometric ratio following sintering. Investigation of different flow rates of H 2 S gas indicated that 30 mL/min would contribute to optimal Zn to S stoichiometric ratio. The Zn to S stoichiometric ratio before sintering under H 2 S medium was 1.28, which increased to 1.55 after annealing under H 2 S medium. The ceramic obtained from ZnS powder annealed under H 2 S medium at 30 mL/min had density of 99.98% and IR transmission of 62% within 8–12 μm range (wavenumbers of 1250–850 cm−1). [ABSTRACT FROM AUTHOR]

Background: A critical parameter of extracorporeal CO2 removal (ECCO2R) applications is the CO2 removal rate (VCO2). Low‐flow venovenous extracorporeal support with large‐size membrane lung remains undefined. This study aimed to evaluate the VCO2 of a low‐flow ECCO2R with large‐size membrane lung using a renal replacement therapy platform in an experimental animal model. Methods: Twelve healthy pigs were placed under mechanical ventilation and connected to an ECCO2R‐CRRT system (surface area = 1.8 m2; OMNIset®, BBraun, Germany). Respiratory settings were reduced to induce two degrees of hypercapnia. VCO2 was recorded under different combinations of PaCO2 (50–69 or 70–89 mm Hg), extracorporeal blood flow (ECBF; 200 or 350 mL/min), and gas flow (4, 6, or 10 L/min). Results: VCO2 increased with ECBF at all three gas flow rates. In severe hypercapnia, the increase in sweep gas flow from 4 to 10 L/min increased VCO2 from 86.38 ± 7.08 to 96.50 ± 8.71 mL/min at an ECBF of 350 mL/min, whereas at ECBF of 200 mL/min, any increase was less effective. But in mild hypercapnia, the increase in sweep gas flow result in significantly increased VCO2 at two ECBF. VCO2 increased with PaCO2 from 50–69 to 70–89 mm Hg at an ECBF of 350 mL/min, but not at ECBF of 200 mL/min. Post‐membrane lung PCO2 levels were similar for different levels of premembrane lung PCO2 (p = 0.08), highlighting the gas exchange diffusion efficacy of the membrane lung in gas exchange diffusion. In severe hypercapnia, the reduction of PaCO2 elevated from 11.5% to 19.6% with ECBF increase only at a high gas flow of 10 L/min (p < 0.05) and increase of gas flow significantly reduced PaCO2 only at a high ECBF of 350 mL/min (p < 0.05). Conclusions: Low‐flow venovenous extracorporeal ECCO2R‐CRRT with large‐size membrane lung is more efficient with the increase of ECBF, sweep gas flow rate, and the degree of hypercapnia. The influence of sweep gas flow on VCO2 depends on the ECBF and degree of hypercapnia. Higher ECBF and gas flow should be chosen to reverse severe hypercapnia. [ABSTRACT FROM AUTHOR]

This study aims to analyze two-phase flow patterns of water and air in a vertical column using experimental tests, and investigate the effect of pulsed gas flow on the characteristics of the Taylor bubble under different inlet conditions. First, three patterns of bubble, slug, and churn were observed with above hundred tests and a flow patterns map was drawn. Then, the effect of the pulsed gas flow on the length of the Taylor bubble was investigated in 150 different experiments. The ranges of superficial velocity of liquid and gas phases were 0.12–0.28 m/s and 0.05–0.25 m/s, respectively. The frequency of pulsed gas feed was 0.25–4 Hz. The results of this study showed that the length of the Taylor bubble in pulsed gas feed decreases with increasing the frequency. In addition, at a fixed gas frequency, the bubble length increases with increasing gas velocity. Present study prove that the pulsed gas flow technique can reduce the length of Taylor bubbles, which will be useful for future industrial applications in two-phase gas-liquid columns. [ABSTRACT FROM AUTHOR]

Background and Objective: Interstitial lung disease (ILD) is characterized by dyspnoea on exertion and exercise‐induced hypoxaemia. High‐flow nasal cannula (HFNC) therapy reduces the respiratory workload through higher gas flow and oxygen supplementation, which may affect exercise tolerance. This study aimed to examine the effects of oxygen and gas flow rates through HFNC therapy on exercise tolerance in ILD patients. Methods: We conducted three‐treatment crossover study. All ILD patients performed the exercises on room air (ROOM AIR setting: flow, 0 L/min; fraction of inspired oxygen [FiO2], 0.21), HFNC (FLOW setting: flow 40 L/min, FiO2 0.21), and HFNC with oxygen supplementation (FLOW + OXYGEN setting: flow 40 L/min, FiO2 0.6). The primary endpoint was the endurance time, measured using constant‐load cycle ergometry exercise testing at a peak work rate of 80%. Results: Twenty‐five participants (10 men, 71.2 ± 6.7 years) were enrolled. The increase in exercise duration between the ROOM AIR and FLOW was 46.3 s (95% CI, −6.1 to 98.7; p = 0.083), and the FLOW and FLOW + OXYGEN was 91.5 s (39.1–143.9; p < 0.001). The percutaneous oxygen saturation (SpO2) at rest was significantly higher with the FLOW + OXYGEN setting than with the ROOM AIR and FLOW settings, and the difference persisted during exercise. At equivalent time points during exercise, the SpO2 with the FLOW setting was significantly higher than that with the ROOM AIR setting. Conclusion: Oxygen supplementation in HFNC therapy improved exercise tolerance and SpO2. We found that gas flow alone did not improve exercise tolerance, but improved SpO2 during exercise. [ABSTRACT FROM AUTHOR]

Summary: High‐flow nasal oxygen can be administered at induction of anaesthesia for the purposes of pre‐oxygenation and apnoeic oxygenation. This intervention is claimed to enhance carbon dioxide elimination during apnoea, but the extent to which this occurs remains poorly quantified. The optimal nasal oxygen flow rate for gas exchange is also unknown. In this study, 114 patients received pre‐oxygenation with high‐flow nasal oxygen at 50 l.min‐1. At the onset of apnoea, patients were allocated randomly to receive one of three nasal oxygen flow rates: 0 l.min‐1; 70 l.min‐1; or 120 l.min‐1. After 4 minutes of apnoea, all oxygen delivery was ceased, tracheal intubation was performed, and oxygen delivery was recommenced when SpO2 was 92%. Mean (SD) PaCO2 rise during the first minute of apnoea was 1.39 (0.39) kPa, 1.41 (0.29) kPa, and 1.26 (0.38) kPa in the 0 l.min‐1, 70 l.min‐1 and 120 l.min‐1 groups, respectively; p = 0.16. During the second, third and fourth minutes of apnoea, mean (SD) rates of rise in PaCO2 were 0.34 (0.08) kPa.min‐1, 0.36 (0.06) kPa.min‐1 and 0.37 (0.07) kPa.min‐1 in the 0 l.min‐1, 70 l.min‐1 and 120 l.min‐1 groups, respectively; p = 0.17. After 4 minutes of apnoea, median (IQR [range]) arterial oxygen partial pressures in the 0 l.min‐1, 70 l.min‐1 and 120 l.min‐1 groups were 24.5 (18.6–31.4 [12.3–48.3]) kPa; 36.6 (28.1–43.8 [9.8–56.9]) kPa; and 37.6 (26.5–45.4 [11.0–56.6]) kPa, respectively; p < 0.001. Median (IQR [range]) times to desaturate to 92% after the onset of apnoea in the 0 l.min‐1, 70 l.min‐1 and 120 l.min‐1 groups, were 412 (347–509 [190–796]) s; 533 (467–641 [192–958]) s; and 531 (462–681 [326–1007]) s, respectively; p < 0.001. In conclusion, the rate of carbon dioxide accumulation in arterial blood did not differ significantly between apnoeic patients who received high‐flow nasal oxygen and those who did not. [ABSTRACT FROM AUTHOR]

• A subcooler reduces the total mass flow rate for a given operation conditions. • Reduced evaporator superheat improves the evaporator heat transfer. • The coefficient of performance increases using a subcooling system. • Flash gas mass flow rate used to reduce the superheat at the compressor inlet. A new position of an internal heat exchanger within the thermodynamic cycle is proposed to improve the performance of CO 2 refrigeration systems in warm climates, specifically in supermarket applications. The proposed configuration uses the saturated vapor from the liquid receiver to recover the heat that is rejected by a subcooler positioned after the gas cooler. This system results in a reduced evaporator superheat. This configuration is compared with a reference system. The experimental study is conducted on a CO 2 laboratory cooling system reproducing a commercial plant. The cooling capacity of the system is 30 kW. The water inlet temperature in the gas cooler (hot source) varies from 15 °C to 35 °C, while the mono-ethylene glycol outlet temperature of the evaporator (cold source) is fixed at -8 °C. The setup is validated through an energy balance. Using a subcooler in this new position improves the coefficient of performance by 10.2 % under transcritical conditions and 6.3 % under subcritical conditions when compared with the reference system. [ABSTRACT FROM AUTHOR]

Simultaneous ventilation of two patients may lead to hypoventilation in one patient and hyperinflation in the other patient. In a simulation of ventilation in two patients using artificial lungs, we voluntarily directed gas flow to one patient by using three-dimensional-printed Y-adapters and stenosis adapters during volume- and pressure-controlled ventilation in the first set up. We continuously modified the model using a special one-way valve on the flow-limited side and measured it in pressure-controlled ventilation with the flow sensor of the ventilator adjusted on both sides in a second and third setup. In the first setup, volume- or pressure-controlled ventilation resulted in comparable minute volumes in both lungs, even when one side was obstructed to 3 mm. In the second setup, with a 3-mm flow limitation, we had a minute ventilation of 9.4 ± 0.3 vs. 3.5 ± 0.1 L/min. In the third setup, ventilation with a 3-mm flow limitation resulted in minute ventilation of 7.2 ± 0.2 vs. 5.70 L/min at a compliance of 30 vs. 70 mL/mbar. It is possible to override the safety features of a modern intensive care ventilator and thus direct tidal volumes in different lung conditions to one lung using three-dimensional-printed flow limiters. While this ventilation setting was technically feasible in a bench model, it would be unstable, if not dangerous, in a clinical situation. [ABSTRACT FROM AUTHOR]

[Display omitted] • The void fraction (41.31%) formed by large-particle size gravel was rapidly reduced. • High rate of gas flow in the pipeline made landfill gas diluted rapidly. • A larger void fraction (44.62%) led to formation of a smaller anaerobic zone. The main disposal method for municipal solid waste (MSW), including the growing worldwide volumes of kitchen waste, involves transport to landfills. Because kitchen waste is mainly composed of organic matter and has a high moisture content, large amounts of leachate and landfill gas are generated when it is sent to landfills. Therefore, rapid waste stabilization is essential. In this study, four semi-aerobic bioreactors (named NS, SS, MS, and LS) were established with void fractions of 33.76%, 39.84%, 44.62%, and 41.31%, respectively. The results showed that the void fractions of landfill directly affected the gas flow path. When the landfill void fraction was small (e.g., NS), most airflow traveled directly through the pipeline and minimal airflow entered the waste layer. When the landfill void fraction was large (e.g., MS), air easily entered the waste layer and some air flowed into the gas vent with the landfill gas. As the reaction proceeded, the void fraction gradually decreased due to gravity-induced sedimentation. During the water addition experiment, the voids were occupied by water, leading to formation of an anaerobic area. Among the four bioreactors, only MS had negligible formation of an anaerobic zone in the center. Methane (CH 4) generation was detected only at the connection between the gas vent and the leachate collection pipe. A larger void fraction led to formation of a smaller anaerobic zone. The ratio of air flowing in pipeline was lowest in MS. These results indicated that a large void fraction promotes the decomposition of organic matter. [ABSTRACT FROM AUTHOR]

We study the ionized gas kinematics of 293 Active Galactic Nucleus (AGN) hosts as compared to that of 485 control galaxies from the MaNGA–SDSS survey using measurements of the [O  iii ] |$\lambda$| 5007 Å emission-line profiles, presenting flux, velocity, and W |$_{80}$| maps. In 45 per cent of the AGN, a broad component was needed to fit the line profiles wings within the inner few kpc, that we have identified with an outflow. But in most AGN, the profiles are broader than that of their controls over a much more extended region, identified as the 'kinematically disturbed regions' (KDRs). We find a positive correlation between the mean |$\langle$| W |$_{80}\rangle$| and L[O  iii ], supporting that the KDR is due to heating and turbulence of the ISM by outflows and radiation from the AGN. The extent R |$_{KDR}$| reaches up to 24 kpc, with a mean ratio to that of the ENLR of 57 per cent. We estimate ionized gas mass flow rates (⁠|$\dot{M}_{\rm out}$|⁠) and kinetic powers (⁠|$\dot{E}_{\rm out}$|⁠) both from the AGN broad components and from the W |$_{80}$| values, that can be obtained for the whole AGN sample. We find values for |$\dot{M}_{\rm out}$| and |$\dot{E}_{\rm out}$| that correlate with the AGN luminosity |$L_{\mathrm{ bol}}$|⁠ , populating the low-luminosity end of these known correlations. The mean coupling efficiency between |$\dot{E}_{\rm out}$| and AGN luminosity is |$\approx$| 0.02 per cent from the W |$_{80}$| values and lower from the broad component. But the large extent of the KDR shows that even low-luminosity AGN can impact the host galaxy along several kpc in a "maintenance mode" feedback. [ABSTRACT FROM AUTHOR]

The ejector is a crucial component of the hydrogen circulation system of proton exchange membrane fuel cell (PEMFC), which is widely used because of its simple structure, reliable operation, and no additional power consumption. However, the current research on pulsed ejectors is still lacking and in-depth. In this study, CFD modeling is conducted on the ejector, and the pulsed gas flow is simulated by user define function (UDF), and the influence of the pulsed gas flow on the entrainment performance of the ejector is analyzed. The results show that, compared with the steady-state condition, the entrainment performance of the ejector using pulsed gas flow under different primary flow pressures is improved, and the maximum entrainment ratio is 3.195 under steady-state conditions and 3.507 under transient conditions, which is increased by 9.8%. The effect is especially pronounced at low pressure, where the entrainment ratio increases by 16.6%. And by comparing the gas flow of different pulse frequencies, it is found that when the pulse frequency is 1Hz, the ejector has the best entrainment performance. • The ejector with pulsed gas flow has significantly better entrainment performance. • At the low primary inlet pressure, the pulsed gas flow has a good effect on the entrain ment performance. • Pulsed gas flow can form a lower low-pressure area at the nozzle exit. • When the frequency of the pulsed gas flow is 1Hz, the entrainment ratio is maximum. [ABSTRACT FROM AUTHOR]

This review article provides a comprehensive overview of the fundamentals, modelling approaches, experimental studies, and challenges associated with hydrogen gas flow in pipelines. It elucidates key aspects of hydrogen gas flow, including density, compressibility factor, and other relevant properties crucial for understanding its behavior in pipelines. Equations of state are discussed in detail, highlighting their importance in accurately modeling hydrogen gas flow. In the subsequent sections, one-dimensional and three-dimensional modelling techniques for gas distribution networks and localized flow involving critical components are explored. Emphasis is placed on transient flow, friction losses, and leakage characteristics, shedding light on the complexities of hydrogen pipeline transportation. Experimental studies investigating hydrogen pipeline transportation dynamics are outlined, focusing on the impact of leakage on surrounding environments and safety parameters. The challenges and solutions associated with repurposing natural gas pipelines for hydrogen transport are discussed, along with the influence of pipeline material on hydrogen transportation. Identified research gaps underscore the need for further investigation into areas such as transient flow behavior, leakage mitigation strategies, and the development of advanced modelling techniques. Future perspectives address the growing demand for hydrogen as a clean energy carrier and the evolving landscape of hydrogen-based energy systems. [Display omitted] • Hydrogen gas characteristics are useful to model flow in pipelines. • Flammability, embrittlement, and leak risks associated with hydrogen pose challenges in transportation. • Temperature variation and pressure drop across critical components are important aspects of pipeline design. [ABSTRACT FROM AUTHOR]

A “closed” perforated plate distributor was proposed to improve the gas distribution in an industrial adsorption tower. Compared with the industrial perforated plate distributor, the designed distributor restricts the space for the disordered movement of gas under the perforated plate. The new distributor effectively converts the gas from the initial axial flow on the inlet section to the axial flow on the tower section to improve the gas uniformity. In addition, the gas velocity at the edge of the inlet cross section of the adsorbent bed is increased by opening holes on the bottom plate. The uniformity of gas distribution is further improved. The simulation method in this study and the distribution performance of the “closed” perforated plate distributor have been verified by experiments. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDs), particularly monolayer TMDs with direct bandgap properties, are key to advancing optoelectronic device technology. WSe2 stands out due to its adjustable carrier transport, making it a prime candidate for optoelectronic applications. This study explores monolayer WSe2 synthesis via H2-assisted CVD, focusing on how carrier gas flow rate affects WSe2 quality. A comprehensive characterization of monolayer WSe2 was conducted using OM (optical microscope), Raman spectroscopy, PL spectroscopy, AFM, SEM, XPS, HRTEM, and XRD. It was found that H2 incorporation and flow rate critically influence WSe2's growth and structural integrity, with low flow rates favoring precursor concentration for product formation and high rates causing disintegration of existing structures. This research accentuates the significance of fine-tuning the carrier gas flow rate for optimizing monolayer WSe2 synthesis, offering insights for fabricating monolayer TMDs like WS2, MoSe2, and MoS2, and facilitating their broader integration into optoelectronic devices. [ABSTRACT FROM AUTHOR]

Graphite substrate, as one of metal-organic chemical vapor deposition (MOCVD) equipment, often fails due to corrosion and powder loss during service. SiC is an ideal protective coating on graphite substrate surfaces due to its excellent properties. Currently, the preparation of SiC coating on large-size graphite substrates by chemical vapor deposition (CVD) in batches is extensively concerned. The coating was affected by various deposition processes during deposition due to the complexity of CVD. The deposition process of CVD needed to be optimized for batch preparation of large-size graphite plate/SiC coating. However, the temperature field and airflow field distribution inside the CVD equipment and the variation of SiC deposition mass fraction were challenging to obtain by instrumental measurement in the experiments. Herein, the optimization of the CVD process was guided by using Computational Fluid Dynamics (CFD) simulation. Five deposition processes, such as graphite plate placement, diameter, deposition temperature, reaction gas flow, and graphite plate rotational speed, were selected for the investigation. The simulation results were validated by CVD experiments. Optimal process parameters for the batch preparation of large-size graphite plate/SiC coating by CVD were obtained. Guidance for future batch production of coating on a large-size substrate by CVD was provided. [ABSTRACT FROM AUTHOR]

This article presents a detailed examination of the methodology and modeling tools utilized to analyze gas flows in pipelines, rooted in the fundamental principles of gas dynamics. The methodology integrates numerical simulations with modern neural network techniques, particularly focusing on the PINN utilizing the continuous symmetry data inherent in PDEs, which is called the symmetry-enhanced Physics-Informed Neural Network. This innovative approach combines artificial neural networks (ANNs) integrating physical equations, which provide enhanced efficiency and accuracy when modeling various complex processes related to physics with a symmetric and asymmetric nature. The presented mathematical model, based on the system of Euler equations, has been carefully implemented using Python language. Verification with analytical solutions ensures the accuracy and reliability of the computations. In this research, a comparative and comprehensive analysis was carried out comparing the outcomes obtained using the symmetry-enhanced PINN method and those from conventional computational fluid dynamics (CFD) approaches. The analysis highlighted the advantages of the symmetry-enhanced PINN method, which produced smoother pressure and velocity fluctuation profiles while reducing the computation time, demonstrating its capacity as a revolutionary modeling tool. The estimated results derived from this study are of paramount importance for ensuring ongoing energy supply reliability and can also be used to create predictive models related to gas behavior in pipelines. The application of modeling techniques for gas flow simulations has the potential to improve the integrity of our energy infrastructure and utilization of gas resources, contributing to advancing our understanding of symmetry principles in nature. However, it is crucial to emphasize that the effectiveness of such models relies on continuous monitoring and frequent updates to ensure alignment with real-world conditions. This research not only contributes to a deeper understanding of compressible gas flows but also underscores the crucial role of advanced modeling methodologies in the sustainable management of gas resources for both current and future generations. The numerical data covered the physics of the process related to the modeling of high-pressure gas flows in pipelines with regard to density, velocity and pressure, where the PINN model was able to outperform the classical CFD method for velocity by 170% and for pressure by 360%, based on L ∞ values. [ABSTRACT FROM AUTHOR]

The hydrodynamics of a conical spouted bed was simulated utilizing the Eulerian–Eulerian Two-Fluid Model (TFM) incorporating a kinetic theory of granular flows. The simulations were confirmed with experimental data. To accurately examine the pyrolysis process, the hydrodynamics of the solid bed as well as the heat transfer inside it were analysed separately by considering a precise synthetic model. The effects of gas velocity, particle size, bed length, and temperature were thoroughly investigated. The results indicated that the amount of relative standard deviation increases with an increase in the inlet velocity into the bed. This amount of deviation at the inlet velocity (0.6 m/s for tar and gas flow to its maximum value of 9.1 and 9.4) is not desirable in product production and should be modified so that the amount of gas flow increases and the tar produced reaches the minimum possible amount. Also, the graphs of the relative standard deviation in terms of temperature indicate that the increase in temperature from 730 to 950 K is associated with a relatively smaller fluctuation of the relative standard deviation so that at the temperature of 730 K, it is 7.2 % for tar and 6.4 % for gas flow, while at temperature of 950 K, it is 6.5 % for wire and 6.8 % for gas flow. Finally, the results determined that small-diameter particles have a more significant fountain height and also higher velocity in the spout section. [ABSTRACT FROM AUTHOR]

As a unique subclass of metal‐organic frameworks (MOFs), MOFs with open metal site (OMS) are demonstrated efficient gas separation performance through pi complexation with unsaturated hydrocarbons. However, their practical application faces the challenge of humidity that causes structure degradation and completive binding at the OMS. In this work, the effect of linker methylation of a copper MOF (BUT‐155) on the C2H2/CO2 separation performance under humid condition is evaluated. The water adsorption isotherm, adsorption kinetics, and breakthrough under dry and humid conditions are performed. The BUT‐155 with methylated linker exhibits lower water uptake and adsorption kinetics under humid condition (RH = 20%), in comparison with HKUST‐1. Therefore, the C2H2/CO2 separation performance of BUT‐155 is much less affected by water, especially under higher gas flow rate. Moreover, the dynamic C2H2/CO2 separation performance of BUT‐155 can maintain five breakthrough cycles under humid conditions (RH = 20% and RH = 80%) without obvious performance degradation. [ABSTRACT FROM AUTHOR]

The structure of viscous shock-front has been investigated in a van der Waals gas between the boundary conditions for x = −ε and x = +ε considering the flow of a gas to be viscous and one-dimensional. The exact solutions for the flow parameters, fluid velocity, pressure, temperature, and change-in-entropy in the shock transition region have been found in view of the equation of state for van der Waals gases. The effects due to the coefficient of viscosity, shock strength, and nonidealness parameter have been analyzed on the structure and flow variable in the shock transition region. The results confirm that the thickness of shock-front increases with increasing value of the coefficient of viscosity and decreases with increasing value of the shock strength and nonidealness parameter of the gases. [ABSTRACT FROM AUTHOR]

Groundwater monitoring to measure a variety of indicator parameters including dissolved gas concentrations, total dissolved gas pressure (TDGP), and redox indicators is commonly used to evaluate the impacts of gas migration (GM) from energy development in shallow aquifer systems. However, these parameters can be challenging to interpret due to complex free‐phase gas source architecture, multicomponent partitioning, and biogeochemical reactions. A series of numerical simulations using a gas flow model and a reactive transport model were conducted to delineate the anticipated evolution of indicator parameters following GM in an aquifer under a variety of physical and biogeochemical conditions. The simulations illustrate how multicomponent mass transfer processes and biogeochemical reactions create unexpected spatial and temporal variations in several analytes. The results indicate that care must be taken when interpreting measured indicator parameters including dissolved hydrocarbon concentrations and TDGP, as the presence of dissolved gases in background groundwater and biogeochemical processes can cause potentially misleading conclusions about the impact of GM. Based on the consideration of multicomponent gas partitioning in this study, it is suggested that dissolved background gases such as N2 and Ar can provide valuable insights on the presence, longevity and fate of free‐phase natural gas in aquifer systems. Overall, these results contribute to developing a better understanding of indicators for GM in groundwater, which will aid the planning of future monitoring networks and subsequent data interpretation. Article impact statement: A modeling study to develop better understanding of groundwater indicators of gas migration from energy development. [ABSTRACT FROM AUTHOR]

Diazo compounds are gathering interest for their potential in promoting greener synthesis routes. We investigate, at a lab‐scale, the continuous synthesis of diazo acetonitrile (DAN) using a micro‐structured flow reactor and a flow reaction calorimeter. Data concerning DAN formation in the former, and relative to reaction heat and gas flow rate in the latter, are collected. We present a physical and a grey‐box model, both of which are calibrated to our data. Compared to the physical model, the grey‐box approach allows to better incorporate the complex chemical reaction pathways of DAN. [ABSTRACT FROM AUTHOR]

To improve the uniformities of the flow distributions in radial beds, different design methods for conical channels were developed, that is, proportional method, traditional linear method for minimizing the pressure difference between two ends of the channel, newly proposed improved linear method for minimizing the pressure axial variation in the whole channel, and improved multi-segment linear method that divide the channel into multi-segments with different inclination angles. The flow fields under different design methods and gas flow rates are then investigated by numerical simulation. The designation of the angle of the conical channel is particularly significant. Compared to the original structure, the proportional method has difficulty obtaining a proper inclination angle, whose inhomogeneity indices of the distributions of pressure drop ηp and gas velocity ηv may increase or decrease. The traditional linear method has lower inhomogeneity indices, for example, ηv will decrease by ≥7.02%, which denotes more uniform flow distributions, while the improved linear and multi-stage linear methods have the lowest inhomogeneity indices, for example, ηv will decrease by ≥12.12 and 13.60%, respectively. Besides, the latter two methods have good adaptability and robustness to fluctuations in the gas flow rate. Two new design methods of conical channel are proposed. Inhomogeneity indices are introduced to quantify the uniformity of flow distribution. Robustness of different design methods are evaluated. [ABSTRACT FROM AUTHOR]

Spray pyrolysis of magnesium nitrate is a way to prepare magnesium oxide solid particles. The gas–solid flow process after the generation of solid particles inside the pyrolysis furnace was studied in this article. Six different inlet modes of hot-carrier gas were designed, and the hot-carrier gas enters the pyrolysis furnace at the same flow rate through the six different inlet modes. The influence of varying inlet methods on the actual running distance of gas flow and the particle sedimentation rate was deeply studied in this article. The longer the distance the hot-carrier gas runs in the pyrolysis furnace, the more conducive it is to full contact with the material. The higher the particle settling rate, the more magnesium oxide particles are collected in the pyrolysis furnace. ANSYS Fluent was used for numerical simulation in this study. The results indicate that when using a tangential inlet, the actual running distance of the hot-carrier gas in the pyrolysis furnace is longer than that of the normal inlet. The actual running distance of the thermal carrier gas at the three tangential inlets is 46.5 m, and that at a single normal inlet is 24.7 m. The former is 88% more than the latter. The sedimentation rate of solid particles at three tangential inlets is 32.24%, and that at a single normal inlet is 12.06%. The former is 167% higher than the latter. The three tangential inlet mode is the best way to increase the actual running distance of the hot-carrier gas and improve the solid particle settling rate in the pyrolysis furnace. The pyrolysis furnace with multiple tangential inlets has two advantages. On the one hand, increasing the running distance of the hot-carrier gas in the furnace is conducive, thereby making the contact between the hot-carrier gas and the material more sufficient. On the other hand, it can increase the capture rate of product particles, improve the product yield, and reduce the dust content of pyrolysis tail gas. [ABSTRACT FROM AUTHOR]

We present observations of the central 9 kpc of the Antennae merger (NGC 4038/9) at 55 pc resolution in the CO (2–1) line obtained with the Atacama Large Millimeter/submillimeter Array (ALMA). We use a pixel-based analysis to compare the gas properties in the Antennae to those in 70 nearby spiral galaxies from the PHANGS-ALMA survey, as well as the merger and nearest luminous infrared galaxy NGC 3256. Compared to PHANGS-ALMA galaxies at matched spatial resolution, the molecular gas in the Antennae exhibits some of the highest surface densities, velocity dispersions, peak brightness temperatures, and turbulent pressures. However, the virial parameters in the Antennae are consistent with many of the PHANGS-ALMA galaxies. NGC 3256 has similar gas surface densities but higher nuclear velocity dispersions than the Antennae, as well as higher system-wide peak brightness temperatures and virial parameters. NGC 3256 is at a later stage in the merging process than the Antennae, which may result in more intense merger-driven gas flows that could drive up the turbulence in the gas. The high virial parameters in NGC 3256 may indicate that this increased turbulence is suppressing future star formation as NGC 3256 moves out of the starburst phase. In comparison, the relatively normal virial parameters in the Antennae may imply that it is about to undergo a new burst of star formation. [ABSTRACT FROM AUTHOR]

In thermal protection systems (TPS), Darcy's law or Darcy-Forchheimer's law is employed to model the pyrolysis gas flow within the anisotropic porous ablator depending on the flow regime considered. A key challenge with using these laws is first, the knowledge of the validity domain of each flow regime in terms of a critical Reynolds number (R e c ). Secondly, the lack of data on macroscopic properties, namely, the permeability and Forchheimer tensors is particularly challenging for the relevance of the models. The objective of this work is to contribute to overcoming these challenges by performing experimental and X-ray tomographic image-based characterization of Calcarb, a commercial carbon preform used for manufacturing TPS. For this purpose, fluid flow within Calcarb was studied experimentally in the Through-Thickness (TT) and the In-Plane (IP) directions for Reynolds numbers of 0.05 to 10.46 -representative of the TPS application. Tomography image-based micro-scale simulations, involving the direct resolution of the Navier–Stokes equations under both flow regimes, were also performed. Experimental results exhibit the anisotropic nature of Calcarb, namely through R e c values, corresponding to the Darcy flow regime limit, slightly different in the two directions (R e c of 0.31 and 0.43) with measured permeability values of 1. 248 × 1 0 − 10 m 2 and 1. 615 × 1 0 − 10 m 2 for TT and IP directions respectively. In the Forchheimer regime, experimental Forchheimer coefficients β were 2. 0010 × 1 0 5 m−1 (TT) and 1. 4948 × 1 0 5 m−1 (IP). During the simulation process, a numerical strategy was defined to obtain the permeability tensor yielding values within 8% of the experimental ones. The comparison of experimental results vs simulation results in the Forchheimer regime was performed through the analysis of the pressure gradients as functions of R e in the x , y , and z directions. The numerical estimations were compared successfully with experimental measurements, with a discrepancy of 5.2%, for R e values up to 2.4. [Display omitted] • Experimental investigation and tomography analysis of the parameters of a carbon preform. • It is applied in Darcy-Forchheimer flows in thermal protection systems. • The permeability is calculated via direct resolution of the Navier–Stokes equations. • The Darcy flow regime limit in Calcarb is observed at a Reynolds number of 0.43. [ABSTRACT FROM AUTHOR]

The fouling of a commercial stainless steel (AISI 316L) during the manufacture of polymeric methylene diphenyl diisocyanate (pMDI) has been studied using laboratory‐based fouling apparatus that simulates commercial production conditions. The goal of the work is to understand the mechanisms behind the corrosion and fouling during isocyanate production with a view to improving process efficiency, not only in this process, but also others using similar plant and processes. Steel coupons were exposed to a solution of pMDI and solid amine hydrochloride, with hydrogen chloride gas being bubbled through the reaction cell. A number of different conditions were investigated, the variables being pMDI concentration, HCl gas flow duration, immersion time and temperature. Following the fouling experiments the coupons were removed from the fouling rig, photographed, and examined by XPS and ToF‐SIMS; principal component analysis was used to extend the ToF‐SIMS analysis to identify organic fouling products. The extent of fouling is shown to be relatively insensitive to pMDI concentration, but significantly influenced by continual HCl flow and increased temperature, features which increase the extent of substrate corrosion thought to be a precursor to the fouling process itself. Both XPS and ToF‐SIMS confirm the formation of various nickel chlorides in the corrosion process. Urea and metal corrosion products are found to co‐exist on certain (random) areas of the coupon surface. [ABSTRACT FROM AUTHOR]

Here we demonstrate the use of magnetic resonance imaging for monitoring a laser-polarized xenon ( 129 Xe) gas working as a fluidizing phase for a glass bead pack, inside a straight circular tube, simulating a granular gas-fluidized bed. The imaging method enabled encoding spatially resolved velocity and diffusion 2D-axial maps of the gas vertical upflow at variable flow regimes. From these maps one could identify gas flow transitions, hysteresis loops, regions of stagnation, and reversed flow, all of which associated, as well as complementary, to reported flow dynamics probing the particles inside the bed. In particular, we focused on the initial stage of bubbling where quantitative data on gas flow spatial maps and their potential correlation with the granular particles dynamics are scarce. [ABSTRACT FROM AUTHOR]

It is imperative to minimize radioiodine release to the environment through gaseous emissions of spent fuel reprocessing facilities, thereby mitigating its potential impact on the general public. One effective and widely adopted strategy for achieving this objective is caustic scrubbing, a method that involves the absorption of molecular iodine from gaseous streams using caustic soda ( NaOH ) solution in a packed column. In-depth laboratory-scale experiments were conducted to ascertain the overall volumetric mass transfer coefficient K G a for the absorption of dilute iodine vapor from air into a caustic soda solution in a packed column and to establish optimum performance parameters for this process. The investigation yielded noteworthy findings: K G a increased proportionately to (Gas phase Reynolds number)1.0 at constant liquid flow rates across all types of packing tested. K G a displayed relative independence from liquid velocities for high and moderate NaOH concentrations. However, this coefficient varied proportionately to (Liquid phase velocity)0.26 to 0.42 at lower NaOH concentrations under conditions of high gas flow rates NaOH . As the height of the column increased, K G a was found to decrease slightly. The presence of NOx at an inlet concentration of 9000 ppm in the gaseous stream led to a reduction in the mass transfer coefficient of iodine, particularly at low NaOH concentrations. In summary, the study underscores the importance of caustic scrubbing as an effective means to minimize the release of radioiodine. The investigation's results provide valuable insights into optimizing performance parameters for this process, contributing to enhanced environmental protection. [ABSTRACT FROM AUTHOR]

In the prevailing model of galaxy formation and evolution, the process of gas accretion on to central galaxies undergoes a transition from cold-dominated to hot-dominated modes. This shift occurs when the mass of the parent dark matter haloes exceeds a critical threshold known as M shock. Moreover, cold gas usually flows on to central galaxies through filamentary structures, currently referred to as cold streams. However, the evolution of cold streams in haloes with masses around M shock, particularly how they are disrupted, remains unclear. To address this issue, we conduct a set of idealized hydrodynamic simulations. Our simulations show that (1) for a gas metallicity |$Z=0.001{\!-\!}0.1\, \mathrm{Z}_{\odot }$|⁠ , cold stream with an inflow rate |$\sim 3\, {\rm {M}_{\odot }}\, \mathrm{yr}^{-1}$| per each can persist and effectively transport cold and cool gas to the central region (<0.2 virial radius) in haloes with mass |$10^{12}\, {\rm {M}_{\odot }}$|⁠ , but is disrupted at a radius around 0.2 virial radius due to compression heating for haloes with mass |$3 \times 10^{12}\, {\rm {M}_{\odot }}$|⁠. (2) At z ∼ 2, the maximum halo mass that capable of hosting and sustaining cold streams M stream is between 1 × 1012 M⊙ and |$1.5\times 10^{12}\,\rm {{M}_{\odot }}$| for gas metallicity |${\it Z}=0.001\, \mathrm{Z}_{\odot }$|⁠ , while for a higher gas metallicity |${\it Z}=0.1\, \mathrm{Z}_{\odot }$|⁠ , this value increases to |$\sim 1.5\times 10^{12}\,\rm {{M}_{\odot }}$|⁠. (3) The evolution and ultimate fate of cold streams are determined primarily by the rivalry between radiative cooling and compression. Stronger heating due to compression in haloes more massive than M stream can surpass cooling and heat the gas in cold streams to the hot (⁠|$\ge 10^6\,$|  K) phase. [ABSTRACT FROM AUTHOR]

The emerging all-d-metal Ni(Co)MnTi-based Heusler compounds attract extensive attention because it can potentially be employed for solid-state refrigeration. However, in comparison to the abundant physical functionalities in bulk conditions, the hidden properties related to the NiCoMnTi-based Heusler nanoparticles (NPs) have not yet been investigated experimentally. Here, we present NiCoMnTi Heusler NPs that have been manufactured by spark ablation under Ar gas flow, and the related magnetic and microstructural properties have been studied. Compared with the bulk sample, it is found that the magneto-structurally coupled transition in the bulk sample has collapsed into a magnetic transition for the NPs sample. Superparamagnetic NPs with widely distributed dislocations have directly been observed by high-resolution transmission electron microscopy. For the NPs, the magnetocrystalline anisotropy constant is 3.54 × 104 J/m3, while the saturation magnetization after post-treatment has been estimated to be around 26 Am2 kg−1. Our current research reveals that Ni-Co-Mn-Ti-based quaternary NPs could show interesting properties for future nano-application, and the produced NPs will further expand the functionalities of this material family. [ABSTRACT FROM AUTHOR]

Electrically heated tobacco products (EHTPs) could release effective aerosol components from tobacco materials at relatively low temperatures without a burning phenomenon. It is essential to grasp the temperature distribution and release mechanism of key components in heated tobacco materials. The existing experimental studies have provided initial insights into the thermodynamic behavior of tobacco materials under various conditions. However, current numerical models are still in their early stages of development, with the majority failing to correlate heat transfer with component release. Based on this, a coupled numerical model of gas flow, heat transfer, and the release of key components in the electrically heated tobacco product is established in this study, which exhibits improvements in revealing the internal heat and mass transfer characteristics in the porous media of tobacco and is capable of evaluating the influence of component contents and product design parameters. The release rates of water, glycerol, and nicotine components are quantitatively described by the first-order Arrhenius formula, and the transport of heat and gas flow is simulated using the Navier-Stokes equation. The accuracy of the model is validated through experiments, including temperature monitoring at multiple measurement points and determination of residual contents in the tobacco substrate after each puff. The simulation results suggest that an appropriate component ratio and tobacco filler mass can enhance both the release amount and release efficiency of key components, and reducing either the diameter or length of the tobacco section can help to improve the heat transfer performance. A slower heating rate matched with longer preheating times enables the complementary release of water and glycerol components, which helps to regulate the uniformity of component content in the aerosol to some extent. This study helps to provide suggestions for the design and optimization of electrically heated tobacco products. [ABSTRACT FROM AUTHOR]

We develop a numerically stable sequential formulation of thermoporomechanics for largely deformable gas hydrate deposits, extended from the fixed stress split of infinitesimal transformation. Constitutive equations are based on the total Lagrangian approach for both flow and geomechanics, including dynamic full tensor permeability and thermal conductivity updated from the deformation gradient. For space discretization, we take the cell‐centered finite volume and node‐based finite element method for flow and geomechanics, respectively. Then, we propose a sequential implicit method for all‐way coupled thermoporomechanics, where the nonisothermal multiphase flow problem of gas hydrates is solved implicitly first and then the geomechanics problem is solved implicitly at the next step. During solution of the flow problem, we fix the rate of first Pioal total stress for numerical stability as well as apply porosity correction and entropy correction to account for geomechanical effects. We test numerical examples where flow and geomechanics parameters are based on deep oceanic gas hydrate deposits. When applying depressurization, even though the results between the infinitesimal transformation and finite strain geomechanics are similar in the early stages due to small deformation, we find differences between them in the late times as deformation becomes large. Accordingly, permeability and thermal conductivity tensors become nonisotropic full tensors although they are initially isotropic. We identify numerical stability of the developed sequential method from the test cases that exhibit the highly complex coupled gas hydrate systems with large deformation. Thus, the proposed sequential formulation can be applied in largely deformable gas hydrate systems. [ABSTRACT FROM AUTHOR]

The interaction of rarefied gases with functionalized surfaces is of great importance in technical applications such as gas separation membranes and catalysis. To investigate the influence of functionalization and rarefaction on gas flow rate in a defined geometry, pressure-driven gas flow experiments with helium and carbon dioxide through plain and alkyl-functionalized microchannels are performed. The experiments cover Knudsen numbers from 0.01 to 200 and therefore the slip flow regime up to free molecular flow. To minimize the experimental uncertainty which is prevalent in micro flow experiments, a methodology is developed to make optimal use of the measurement data. The results are compared to an analysis-based hydraulic closure model (ACM) predicting rarefied gas flow in straight channels and to numerical solutions of the linearized S-model and BGK kinetic equations. The experimental data shows that if there is a difference between plain and functionalized channels, it is likely obscured by experimental uncertainty. This stands in contrast to previous measurements in smaller geometries and demonstrates that the surface-to-volume ratio of 0.4 μ m - 1 seems to be too small for the functionalization to have a strong influence and highlights the importance of geometric scale for surface effects. These results also shed light on the molecular reflection characteristics described by the TMAC. [ABSTRACT FROM AUTHOR]

The mechanochemical hydrogenation of 4-nitrophenol was examined in a ball mill reactor. Hydrogen gas flows through the reactor at ambient temperature and pressure in the presence of Pd/C catalyst and acetic anhydride. Under optimized conditions, simultaneous hydrogenation and acetylation in one pot increased paracetamol selectivity by avoiding undesirable side reactions of 4-aminophenol. Side product formation was further reduced through a novel bubbler configuration allowing for the delivery of acetic anhydride vapor to the reaction vessel. Ball mill results were compared to traditional stirred tank hydrogenations in a Parr reactor and shown to have superior yield and process mass intensity. [ABSTRACT FROM AUTHOR]

The initial stage of argon condensation at discharge to vacuum has been studied experimentally. Mass-spectrometry measurements of the spectrum of clusters at outflow from a long pipe with laminar and turbulent flow regimes in it have been carried out. It has been found experimentally that the turbulent flow regime in the pipe suppresses the nucleation of a condensed phase. [ABSTRACT FROM AUTHOR]

The study presents a novel setup for measuring the flow regime of hydrate particles in a gas-dominated flow, which is of interest for applications such as natural gas transportation. A closed-flow loop, driven by a novel internal fan, enables continuous observation of hydrate particle behavior in a gas flow. The experimental setup allows the production and insertion of HFC134a gas hydrate particles with diameters of 10–50 μm into the gas flow loop via a bypass loop. The performance curve of the internal fan is validated, and its suitability for achieving the required flow speed (5 m/s) is demonstrated. Through an observation window using camera systems, the flow regime of glass beads is successfully visualized and analyzed. To validate the experimental data, a coupled computational fluid dynamics–discrete element method model is used to simulate the particle flow density distribution. The study findings demonstrate the effectiveness of the experimental setup in characterizing the flow regime of hydrate particles in a gas-dominated flow. [ABSTRACT FROM AUTHOR]

Ion implanters have extensively been employed to simulate the irradiation effects of neutrons on relevant nuclear materials. In this study, a 50 kV hydrogen–helium mixed ion beam implanter was developed to generate H2+ and He+ ion beams, with a beam current of 20 µA, while keeping the impurity ion content below 2%. The ions are generated by an antenna-type 2.45 GHz electron cyclotron resonance ion source, and the hydrogen-to-helium ion beam ratio was controlled using two gas mass flow controllers to ensure long time stability of the beam current. As a result, the H2+/He+ ratio, beam size, and homogeneity of the beam spot can be maintained at a stable level. The beam line consisted of four Wien filters, a movable dual-slit plate, and an accelerator tube. The experimental results demonstrated successful transport of more than 20 µA of H2+ and He+ ion beams onto the target, with a beam axis deviation of less than 0.5 mm. [ABSTRACT FROM AUTHOR]

This study investigates the initial acceleration process of low-speed flames in curved channels. It also examines how the curvature and width of the channels influence flame propagation patterns and mechanisms. Previous research has highlighted the advantages of curved channels in facilitating flame acceleration. Subsequent studies have explored the interaction between pressure waves and flames, particularly in the later stages of flame propagation, leading to a high-speed flame phase. However, the effects of curvature and channel width on the initial acceleration phase of low-speed flames remain unclear. To address this gap, the present study utilizes theoretical methods to analyze the early acceleration phase of flames in curved channels with fixed curvature and width, from the closed end to the open end. Semi-analytical theoretical solutions are derived to determine the shape of the unburned gas flow field, flame front, and flame acceleration rate. The results demonstrate that the flow field shape deviates from axial symmetry to conserve angular momentum, favoring the inner wall of the curved channel and causing the flame front to adhere to it. In channels with small curvature, increasing the width leads to a decrease in the flame acceleration rate. Conversely, in channels with large curvature, widening the channel results in an increased flame acceleration rate. These findings provide theoretical insights for optimizing the design of the front-stage structure of curved detonation channels. [ABSTRACT FROM AUTHOR]

A microscale lubrication flow of a gas between eccentric circular cylinders with an arbitrary temperature difference is studied on the basis of kinetic theory. The dimensionless curvature, defined as the mean clearance divided by the radius of the inner cylinder, is small, whereas the temperature ratio and the Knudsen number based on the mean clearance take arbitrary values. The Bhatnagar–Gross–Krook–Welander (BGKW) model of the Boltzmann equation in bipolar coordinates is studied analytically using the slowly varying approximation. The leading-order term of the perturbation, which ought to be the solution of the nonlinear heat transfer problem, is replaced by the free molecular solution or an equilibrium solution at rest. Two macroscopic lubrication models are derived, along with a numerical database that enables one to use the models quickly. Direct numerical analysis of the BGKW equation is also conducted, and the validity of the lubrication models is assessed. The heating of either cylinder enhances both the eccentric force and the torque acting on the inner cylinder. When the Knudsen number is small, there is little difference in the eccentric force between the cases in which the rotating inner cylinder is heated and the stationary outer cylinder is heated. However, this difference becomes significant as the Knudsen number increases, with heating of the outer cylinder yielding the greater eccentric force. If the two lubrication models are applied complementarily depending on the Knudsen number, they provide a reasonable result for the eccentric force over a wide range of the Knudsen number. [ABSTRACT FROM AUTHOR]

Enhancing photoluminescence (PL) in single-layer transition metal dichalcogenides has garnered significant interest, particularly for advancing high-performance 2D electronics and optoelectronics. The combination of surface engineering and contemporary growth methods has provided a platform for investigating optical signals. In this study, we present variations in PL and Raman signals of single-layer MoS2 flakes grown conformally using the glass-assisted CVD method on squarepatterned surfaces with varying well depths. PL spectroscopy revealed a systematic and pronounced enhancement in intensities as the valley thickness decreased from 285 nm to 225 nm. Conversely, for the hill regions of the samples, the PL intensity initially increased with decreasing valley thickness and then decreased, despite the hill regions having a constant thickness of 300 nm. On the other hand, PL maps did not exhibit a systematic dependence of intensities on the hill-valley thickness distinction, contrary to expected results based on literature data for similar materials on flat surfaces. The origin of the intensity oscillations was attributed to possible mechanisms, including thickness-dependent interference and strain-related exciton funneling effects. Additionally, Raman measurements revealed irregular variations in intensity in hill regions, dependent on the thicknesses of the underlying SiO2 layers. Furthermore, we observed that the sizes of the flakes increased as the well depths of the underlying patterned surface decreased. This phenomenon might be attributed to alterations in the carrier gas flow pattern and varying temperature gradients between the hills and valleys. These results hold substantial potential to open new avenues for the integration of 2D transition metal dichalcogenides into onchip electronic and optoelectronic devices. [ABSTRACT FROM AUTHOR]

High flow oxygen (HFO) therapy is a well-established treatment in respiratory disease. Concurrent aerosol delivery can greatly expediate their recovery. The aim of this work was to complete a comprehensive characterisation of one such HFO therapy system, the Airvo2TM, used in combination with the Aerogen SoloTM vibrating mesh nebuliser. Representative adult, infant, and paediatric head models were connected to a breathing simulator via a collection filter placed at the level of the trachea. A tracheostomy interface and nasal cannulas were used to deliver the aerosol. Cannula size and gas flow rate were varied across the full operating range recommended by the manufacturer. The tracheal and emitted doses were quantified via UV-spectrophotometry. The aerosol droplet diameter at the exit of the nares and tracheal interface was measured via cascade impaction. High gas flow rates resulted in low emitted and tracheal doses (%). Nasal cannula size had no significant effect on the tracheal dose (%) available in infant and paediatric models. Higher gas flow rates resulted in smaller aerosol droplets at the exit of the nares and tracheostomy interface. Gas flow rate was found to be the primary parameter affecting aerosol delivery. Thus, gas flow rates should be kept low and where possible, delivered using larger nasal cannulas to maximise aerosol delivery. [ABSTRACT FROM AUTHOR]