Atmospheric Pressure Research Articles

Association between periodic variation of air temperature, humidity, atmospheric pressure and hospital admissions for acute occlusive mesenteric ischaemia

Referring to the intestinal ischemic injury caused by sudden interruption of the blood supply, acute mesenteric ischemia (AMI) is a highly fatal emergency with mortality rates varying from 58 to 80%. The aim of this study was to explore the effect of temperature on AMI admission. This was a retrospective, multicentric study. The medical records of 1477 patients with verified AMI who were consecutively admitted to 3 hospitals anytime between January 2010 and December 2020 were included in the study. Distributed lag non-linear model was applied, the model was adjusted for temperature, atmospheric pressure, relative humidity, year, holiday, day of the week, time and seasonality. AMI exhibited obvious sex preference, AMI patients tended to be male (M/F ratio = 2.3:1) and in their late 50 s. Hospital admissions of acute mesenteric arterial thromboembolism (AMAT) increased significantly with high temperatures on day of exposure and lag 0–14 day. The effect curve of daily average temperature on acute mesenteric venous thromboembolism (AMVT) admission was J-shaped, and the duration of cold effect was longer, while the duration of heat effect was shorter. An increase in hospital admissions of AMVT was found above 20 °C at lag 0–30. For the first time, our study indicated that temperature is significantly associated with the risk of AMI. Although it is not possible to always avoid exposure to extreme temperatures, one should be aware of dramatic temperature fluctuations and take appropriate precautions.

Collision dynamics of binary equal-size droplets at high pressures: a focus on stretching separation and reflexive separation

ABSTRACT Stretching separation and reflexive separation are two collision regimes that give rise to satellite droplets, significantly impacting the droplet size distribution. However, the influence of high pressure on these regimes remains unclear. This paper investigates the collision dynamics of binary equal-size droplets under varying ambient pressures using the volume of fluid method and adaptive mesh refinement. The results show that vortices, generated during droplet motion changes or ligament ruptures, facilitate mass transport within the droplet–droplet deformation. Additionally, this paper summarizes four phases of droplet deformation in the separation regimes, which are delayed in stretching separation and advanced in reflexive separation with increasing ambient pressure. Elevated ambient pressure restricts droplet movement, resulting in tougher ligament fractures, smaller satellite droplets, and an expanded coalescence regime boundary. Unlike previous works, this paper incorporates gas kinetic and dissipation energies during droplet collisions at high pressures, revealing that at 7 MPa, the gas dissipation energy is comparable to the liquid dissipation energy and cannot be neglected. To account for these effects, a pressure-dependent formula is integrated into the composite collision model under the Lagrangian framework, offering enhanced predictions of droplet size within the stretching separation regime.

Mega El Niño instigated the end-Permian mass extinction.

The ultimate driver of the end-Permian mass extinction is a topic of much debate. Here, we used a multiproxy and paleoclimate modeling approach to establish a unifying theory elucidating the heightened susceptibility of the Pangean world to the prolonged and intensified El Niño events leading to an extinction state. As atmospheric partial pressure of carbon dioxide doubled from about 410 to about 860 ppm (parts per million) in the latest Permian, the meridional overturning circulation collapsed, the Hadley cell contracted, and El Niños intensified. The resultant deforestation, reef demise, and plankton crisis marked the start of a cascading environmental disaster. Reduced carbon sequestration initiated positive feedback, producing a warmer hothouse and, consequently, stronger El Niños. The compounding effects of elevated climate variability and mean state warming led to catastrophic but diachronous terrestrial and marine losses.

Polymer-Supported Pd Nanoparticles for Solvent-Free Hydrogenation.

Breaking the trade-off between activity and stability of supported metal catalysts has been a long-standing challenge in catalysis, especially for metal nanoparticles (NPs) with high hydrogenation activity but poor stability. Herein, we report a porous poly(divinylbenzene) polymer-supported Pd NP catalyst (Pd/PDVB) with both high activity and excellent stability for the solvent-free hydrogenation of nitrobenzene, even at ambient temperature (25 °C) and H2 pressure (0.1 MPa). Pd/PDVB gave a turnover frequency as high as 22,632 h-1 at 70 °C and 0.4 MPa, exceeding 5556 h-1 of the classical Pd/C catalyst under equivalent conditions. Mechanistic studies reveal that the polymer support benefits the desorption of the aniline product from the Pd surface, which is crucial for rapid hydrogenation under solvent-free conditions. In addition, the polymer support in Pd/PDVB efficiently hindered Pd leaching, resulting in good stability.

Rapid ambient pressure drying preparation of bulk ZrO2-SiO2 aerogels with high thermal stability

In this study, the sol-gel stage co-precursor method was used to hydrophobically modify the gel and increase the content of alkali catalyst in the gel, thereby reducing the capillary force generated during ambient pressure drying and enhancing the strength of the gel skeleton. This improvement makes the gel skeleton structure not easy to destroy during the rapid drying process, thus greatly reducing the preparation time of atmospheric pressure drying, which could be as short as 10 h. It is worth mentioning that this method does not require extensive use of modifiers and organic solvents, so it has low cost, high efficiency, and broad industrial production application prospects. The experimental results show that the DDS/ZSA aerogel exhibits the lowest thermal conductivity (0.035 W m−1 K−1) when the dilute ammonia content is 5 ml. However, it should be noted that too low or too high an amount of dilute ammonia will lead to a decrease in aerogel performance, so it needs to be controlled within the appropriate range. In addition, the prepared aerogel has excellent hydrophobic properties with a contact angle greater than 140° and excellent thermal stability at 1000 °C, which can be used in harsh, humid, and high-temperature environments.

Isotopic fractionation of methane on Mars via diffusive separation in the subsurface

Many processes have been identified in the Martian subsurface which may produce or release methane that eventually can be emitted into the atmosphere. Given the wide range of isotopic values for source carbon reported on Mars and the importance of atmospheric methane isotopologues as a tracer for subsurface processes, it is critical to quantify the level of isotopic fractionation that can occur during subsurface transport. On Earth, isotopic fractionation occurs when methane transport is dominated by Knudsen diffusion through small pores. However, unlike the Earth, on Mars the low atmospheric pressure and commensurate longer mean free path suggest that most subsurface transport of methane occurs in the Knudsen regime, amplifying this effect. Here, we report on simulations of diffusion through the martian subsurface and report on the level of fractionation that would be expected under two end-member scenarios. For Interplanetary Dust Particles (IDPs) incorporated in near-surface sediments in which methane is released quickly upon generation, atmospheric emissions of methane are expected to be representative of the reservoir isotopic ratio. However, for deeper sources in which methane accumulates as trapped gas, subsurface transport will result in depletions of 13CH4 compared to reservoir concentrations by approximately −31‰. Over time, both the reservoir and the emitted gas will evolve to become isotopically enriched in 13CH4 compared to a standard of constant isotopic ratio. This necessitates temporal measurements of emitted methane to understand the δ13C of the reservoir and depth of the release, preferably with hourly or better frequency. Finally, a seasonal cycle in δ13C with an amplitude of 5.3‰ is expected with adsorption acting to create small temporary reservoirs that are filled and emptied over the year by the subsurface thermal wave. This effect may provide a way to probe near-surface thermophysical properties.

Vulnerability to extreme weather events: mapping future hazards in Wielkopolska region, Poland

The aim of this study is to assess future hazards due to extreme meteorological events in the Wielkopolska region, Poland, based on five climate model projections and three scenarios: SSP126, 370, and 585. The paper analyzes the changes of mean and extreme precipitation, mean and extreme temperatures, and humidity index, as well as changes in difference between maximum temperatures observed from day to day and changes in difference between mean atmospheric pressure at the sea level observed from day to day. Additionally, we look at possible future occurrence of wildfires due to changes in fire weather conditions. Based on climate model projections, future hazard due to extreme meteorological events in Wielkopolska region is to be more serious and will be most noticeable in the end of twenty-first century and for two higher scenarios: SSP370 and SSP585. For near future, 2021–2050, projected conditions of meteorological extremes for analyzed scenarios are quite consistent. Therefore, there is a strong need for implementing adaptation actions. Nevertheless, such activities are so far lacking, and several adaptation options are not present in local and national legislation, even though they are recognized as effective.

Deformation-induced gas adsorption and self-desorption dynamics of a carbon nano-network: Molecular dynamics modeling focusing on CO2 capture

Gas adsorption and separation/desorption are two pivotal stages in gas capture, demanding additional energy for liberating gas molecules from the adsorbent. Hence, it’s essential to engineer an adsorbent with minimal energy consumption yet effective gas adsorption–desorption characteristics. Accordingly, this research introduces a carbon nano-network (CNN) material capable of inhaling and exhaling gases via self-deformation. Molecular dynamics simulations demonstrate that the gas adsorption–desorption capabilities of CNN can be efficiently regulated by its deformation. While the size of CNN minimally affects the gas sorption rate, a larger CNN necessitates a prolonged duration to achieve saturation under identical gas conditions. Incorporating elongated appendages in CNN enhances both its stability during contraction and its efficiencies in gas adsorption and desorption. We discerned that attaining a critical gas density within a confined space is imperative to initiate self-desorption of CNN. Specifically, if the gas density dips below this critical threshold–set at 5.2 times that of CO2 at room temperature (300 K) and atmospheric pressure (1 Bar)–CNN exhibits no self-desorption capability. Nevertheless, even a marginal elevation in gas density triggers and maintains self-desorption with a consistently surpassing desorption ratio of 98 %. This discovery offers valuable insights for designing automatic self-desorption materials or apparatuses.

CoAl composite catalysts derived from hydrotalcite-like compounds for CH4 efficient dry reforming

In this study, CoAlx-LDH hydrotalcite-like was used as the precursors to prepare the CoAlx-LD composite catalysts for the DRM reaction. The transition metal Co was the main catalytic active centers for the DRM reaction. The layered structure of the hydrotalcite-like CoAlx-LDH precursors promoted the highly dispersed Co0 active centers to be formed in the CoAlx-LD catalysts. In addition, synergistic effects between active sites, basic sites and oxygen vacancies can promote the DRM catalytic performances of CoAl composite catalysts. Meanwhile, the Co/Al mole ratio can regulate the active sites, basic sites and oxygen vacancies in the catalysts, thereby affecting its catalytic performances. The CoAl12-LD catalyst with a Co/Al mole ratio of 1/2 exhibited excellent DRM catalytic performances. The CH4 and CO2 conversions on the prepared CoAl12-LD catalyst achieved 86.8% and 53.4% at atmospheric pressure and 700 °C, respectively. In addition, the catalyst also showed excellent use stability in the DRM reaction.

Actual reliance of catalytic activities tuned oxygen vacancies on VOx/Ce1-xZrxO2 catalyst for selective oxydehydrogenation of methanol to dimethoxymethane

Metal oxide catalysts like ceria-supported vanadia (VOx/Ce1-xZrxO2) with different Zr contents were prepared by coupling ceria-zirconia solid solution and vanadia. Characterization revealed that the insertion of zirconia into ceria significantly improved catalytic activity due to the generation of more oxygen vacancies and distortion of the composite structure. The oxygen vacancy concentration initially increased with the increase of Zr (x= wt%) and peaked at x=0.7 and then decreased. The reliance of oxygen vacancy concentration in VOx/Ce1-xZrxO2 catalyst on their catalytic activity in methanol oxydehydrogenation was further investigated. Results indicated that oxygen vacancies not only activated oxygen species but also cleaved C–H bonds alongside V5+ active site contained terminal oxygen atoms for cleaving O–H and C–H bonds within the adsorbed methanol. The VOx/Ce0.3Zr0.7O2 exhibited the best catalytic activity with the methanol conversion of 76 % and the dimethoxymethane selectivity of 96 % at 200 ℃ and atmospheric pressure in a fixed-bed reactor.

On atmospheric pressure and temperature correlation across various terrain types

Temperature (T), pressure (p), and density (ρ) are fundamental variables describing the atmospheric behavior. This study investigates the interdependence of these variables near Earth's surface in real-world conditions, by evaluating data from different European weather stations. It has been found that the correlation between pressure and temperature is strongly related to the dynamics of the PBL that facilitates a two-group classification. The first group includes all the stations in the plain or in the valley-floor and exhibits a weak correlation, R(p,T). 2D density plots representing hourly pressure against temperature have a distinctive triangular shape at these stations. Regardless of location, the upper boundary of this triangle consistently fits a linear equation with a constant slope and an intercept that scales with the average pressure of the station. This finding holds promising implications for enhancing the quality check of pressure and temperature data, enabling the identification of implausible measurements using a unified equation. In contrast, the second group includes stations with a strongly positive correlation R(p,T) and a more linear density plot; it includes all stations near a mountain-top. Their correlations exhibit identical features when compared to radiosounding data extracted at corresponding heights. The study concludes that: i) the first group of stations is significantly influenced by non-hydrostatic processes such as turbulence, friction and surface radiative heating/cooling in the PBL, resulting in weakly negative R(p,T) for shorter timescales that become null over longer durations; ii) the second group of stations has R(p,T) characteristics similar to the free atmosphere, predominantly regulated by hydrostatic balance and the advection of sensible heat.

CO2 capture using red mud & mechanically-activated red mud and its kinetics under ambient conditions

Greenhouse gas emissions and the growing stockpiles of red mud, an alkaline industrial waste with potential for CO2 sequestration, present significant environmental challenges. This article aims to enhance the CO2 sequestration capacity of red mud by mechanically activating its surface using a high-energy planetary ball mill for extended grinding periods. The novelty of the study lies in investigating the CO2 sequestration capacity and evaluating its kinetics includingadsorption and desorption on feed and mechanically-activated red mud under atmospheric temperature and pressure for the first time via a direct gas–solid carbonation route using a fixed bed column. The effect of ball size (10,8 and 6 mm) used in high-energy planetary ball mills while mechanical activation, CO2 flow rate (20–80 ml/min), and reaction time (1–5 h) on the CO2 capture has been studied. Apart from this, experimental data on CO2 sequestered (1–5 h) and the extent of CO2 desorption (7–35 days) are fitted to various kinetic models, including pseudo-first-order, pseudo-second-order, and Avrami’s fractional order models. Results showed that the CO2 sequestration capacity of feed red mud is 3.75 mg/g, while the capacity of mechanically-activated red mud increased to 18.28 mg/g, with an adsorption time of 5 h at ambient temperature and pressure. The most suitable fit is attained with Avrami’s fractional order model, suggesting that both physisorption and chemisorption contribute to enhancing the CO2 sequestration capacity of red mud. The mechanism for this process has also been proposed along with the suitable characterizations.

Laboratory measurements of water saturation effects on the acoustic velocity and attenuation of sand packs in the 1–20 kHz frequency range

AbstractWe present novel experimental measurements of acoustic velocity and attenuation in unconsolidated sand with water saturation within the sonic (well‐log analogue) frequency range of 1–20 kHz. The measurements were conducted on jacketed sand packs with 0.5‐m length and 0.069‐m diameter using a bespoke acoustic pulse tube (a water‐filled, stainless steel, thick‐walled tube) under 10 MPa of hydrostatic confining pressure and 0.1 MPa of atmospheric pore pressure. We assess the fluid distribution effect on our measurements through an effective medium rock physics model, using uniform and patchy saturation approaches. Our velocity and attenuation (Q−1) are accurate to ±2.4% and ±5.8%, respectively, based on comparisons with a theoretical transmission coefficient model. Velocity decreases with increasing water saturation up to ∼75% and then increases up to the maximum saturation. The velocity profiles across all four samples show similar values with small differences observed around 70%–90% water saturation, then converging again at maximum saturation. In contrast, the attenuation increases at low saturation, followed by a slight decrease towards maximum saturation. Velocity increases with frequency across all samples, which contrasts with the complex frequency‐dependent pattern of attenuation. These results provide valuable insights into understanding elastic wave measurements over a broad frequency spectrum, particularly in the sonic range.

Solubility and thermodynamic analysis of aceclofenac in different {Carbitol + water} mixtures at various temperatures

The solubility and thermodynamic properties of the anti-inflammatory drug aceclofenace (ACF) have been assessed in a range of {2-(2-ethoxyethoxy)ethanol (Carbitol) + water} combinations at temperatures ranging from 298.2 K to 318.2 K and atmospheric pressure of 101.1 kPa. The shake flask method was employed to determine the solubility of ACF, and various models including “van’t Hoff, Apelblat, Buchowski-Ksiazczak λh, Yalkowsky-Roseman, Jouyban-Acree, and Jouyban-Acree-van’t Hoff models” were used to validate the results. The computational models demonstrated a strong correlation with the experimental ACF solubility data, as indicated by the error values of < 3.0%. In the compositions of {Carbitol + water}, the ACF mole fraction solubility was enhanced by temperature and Carbitol mass fraction. The solubility of ACF in mole fraction was found to be lowest in pure water (1.07 × 10− 6 at 298.2 K), and highest in pure Carbitol (1.04 × 10− 1 at 318.2 K). Based on the positive values of the calculated thermodynamic parameters, the dissolution of ACF was determined to be “endothermic and entropy-driven” in all of the {Carbitol + water} solutions that were studied. It was also observed that enthalpy controls the solvation of ACF in solutions containing {Carbitol + water}. ACF-Carbitol had the strongest molecular interactions in contrast to ACF-water. Based on the results of this study, Carbitol holds significant potential for enhancing the solubility of ACF in water.

Modification of the Surface Crystallinity of Polyphenylene Sulfide and Polyphthalamide Treated by a Pulsed-Arc Atmospheric Pressure Plasma Jet.

Atmospheric plasma jets generated from air or nitrogen using commercial sources with relatively high energy densities are commonly used for industrial applications related to surface treatments, especially to increase the wettability of polymers or to deposit thin films. The heat fluxes to which the substrates are subjected are typically in the order of 100-300 W/cm2, depending on the treatment conditions. The temperature rise in the treated polymer substrates can have critical consequences, such as a change in the surface crystallinity or even the surface degradation of the materials. In this work, we report the phase transitions of two semicrystalline industrial-grade polymer resins reinforced with glass fibers, namely polyphenylene sulfide (PPS) and polyphthalamide (PPA), subjected to plasma treatments, as well as the modeling of the associated heat transfer phenomena using COMSOL Multiphysics. Depending on the treatment time, the surface of PPS becomes more amorphous, while PPA becomes more crystalline. These results show that the thermal history of the materials must be considered when implementing surface engineering by this type of plasma discharge.

Development and characterization of atmospheric pressure gliding Arc plasma jet

In this work, we present the development and comprehensive characterization of an atmospheric pressure gliding arc plasma jet (GAPJ) operating in ambient air to generate non-thermal plasma. Through systematic investigation, the relationship between jet length and airflow rate indicates a positive correlation. Electrical and optical techniques are utilized to characterize the discharge, revealing an impact of applied voltage and gas flow rate on discharge parameters. Calculations are made for parameters such as electron density ((0.62−3.44)×1019) m −3, average power dissipation (9.85−40.50) W, and root mean square values of current and voltage. The impacts of applied voltages and gas flow rate on these parameters are also examined. Electron excitation temperature is determined using the Boltzmann plot method, yielding values within the range of (1.36−1.44) eV. Rotational and vibrational temperatures of discharge are analyzed, revealing values of (1373−2065) K and (2700−2405) K, respectively, under different operational conditions. The generated non-thermal plasma is confined to form a plasma plume although it consists of two diverging electrodes and offers promising applications for specified areas of sterilization and decontamination in the medical, pharmaceutical, and food processing industries.

Main-group compounds selectively activate natural gas alkanes under room temperature and atmospheric pressure

Most C–H bond activations of natural gas alkanes rely on transition metal complexes. Activations by using main-group systems have been reported but required heating or photo-irradiation under high atmospheric pressure with rather low regioselectivity. Here we report that Lewis acid-carbene adducts facilely undergo oxidative additions to C–H bonds of ethane, propane and n-butane with high selectivity under room temperature and atmospheric pressure. The Lewis acids can be moved by the addition of a base and the carbene-derived products can be easily converted into aldehydes. This work offers a route for main-group element compounds to selectively functionalise C–H bonds of natural gas alkanes and other small molecules.

Conductometric Properties and UV–Vis Spectroscopic Study of L-Glutamic Acid in Aqueous Solutions of L-Arabinose and D-Xylose in the Temperature Range of 293.15–313.15 K at Atmospheric Pressure

Conductometric Properties and UV–Vis Spectroscopic Study of L-Glutamic Acid in Aqueous Solutions of L-Arabinose and D-Xylose in the Temperature Range of 293.15–313.15 K at Atmospheric Pressure

Experimental study on effect of pressure on ADS-4 liquid entrainment characteristics in T-junction

Liquid entrainment phenomenon can occur in the T-junction formed by the vertical ADS-4 pipeline and the hot pipe section during SBLOCA process in AP1000 reactor. At present, most of the studies on the liquid entrainment phenomenon in T-junction with large branch pipe concentrate on the atmospheric pressure condition, which is difficult to accurately reflect the real state of the accident process. The liquid entrainment experiments were carried out at 0.1–0.4 MPa on ADETEL facility. The results show that there will be obvious reverse flow phenomenon in the branch at 0.1 MPa and the phenomenon disappears gradually with the increase of pressure. Furthermore, the occurrence of intermittent two-phase slug flow in the horizontal tube was observed at lower pressures. As pressure increases, the entrainment process will become more continuous and stable, with a concomitant reduction in intermittency. The steady-state entrainment liquid level and the onset of entrainment liquid level both decrease with increasing pressure, indicating that increasing pressure can facilitate the liquid entrainment amount. The existing correlations cannot accurately estimate the entrainment amount during SBLOCA in nuclear reactor with a deviation of more than +100% between the predictions and experimental data.

Elucidating the bacterial inactivation mechanism by argon cold atmospheric pressure plasma jet through spectroscopic and imaging techniques.

This study aims to assess the potential bacterial inactivation pathway triggered by argon (Ar) cold atmospheric pressure plasma jet (CAPJ) discharge using spectroscopic and imaging techniques. Electrical and reactive species of the Ar CAPJ discharge was characterized. The chemical composition and morphology of bacteria pre- and post-CAPJ exposure were assessed using Fourier transform infrared (FTIR), Raman micro-spectroscopy, and transmission electron microscopy (TEM). A greater than 6 log reduction of E. coli and S. aureus was achieved within 60 and 120 s of CAPJ exposure, respectively. Extremely low D- values (< 20 s) were recorded for both the isolates. The alterations in the FTIR spectra and Raman micro-spectra signals of post-CAPJ exposed bacteria revealed the degree of destruction at the molecular level, such as lipid peroxidation, protein oxidation, bond breakages, etc. Further, TEM images of exposed bacteria indicated the incurred damages on cell morphology by CAPJ reactive species. Also, the inactivation process varied for both isolates, as evidenced by the correlation between the inactivation curve and FTIR spectra. It was observed that the identified gas-phase reactive species, such as Ar I, O I, OH•, NO+, OH+, NO2-, NO3-, etc. played a significant role in bacterial inactivation. This study clearly demonstrated the effect of CAPJ exposure on bacterial cell morphology and molecular composition, illuminating potential bacterial inactivation mechanisms.