Search

This work describes the plume chemistry of laser-ablated carbon–carbon (C–C) composite samples in vacuum, a range of air pressures, and in pure oxygen. Time-resolved spectra were measured from a plasma plume generated by laser-ablation at 248 nm. The focus of this work was on the detection of three chemical species, C2, CN, and CO in pressures from near vacuum (10−7 Torr) to air at atmospheric pressure (760 Torr). Emission from atomic carbon C I was predominant at 10−7 Torr, while molecular C2 Swan Band emission was observed at 10−7 Torr, at all air pressures, as well as in pure oxygen. Emission from the CN violet bands was observed only when ablating in air, but not in vacuum or pure O2, indicating that CN was the product of a chemical reaction between an ablated carbon species and N2 present in air, and not intrinsically present in the C–C composite targets. High-resolution emission spectra from C2 and CN were measured and fitted to vibrational and rotational temperatures. Time-resolved emission measurements of both these molecules were used to estimate their respective velocities as a function of pressure. No emission from excited state CO could be detected from 180–900 nm, even in pure O2. However, neutral and ground state CO and CO2 were both detected by measuring FTIR absorption spectra following the ablation of a composite target at 248 nm, in dry air at atmospheric pressure. The HITRAN database was used to calculate the concentrations of CO and CO2 produced per laser pulse. [ABSTRACT FROM AUTHOR]

Safety incidents with lithium‐ion batteries have impeded the battery industry's progress. As internal battery reactions often precede visible symptoms, and traditional electrical parameters are insufficient for comprehensive state assessment and hazard prediction, this study utilized multi‐physics simulations to analyze non‐electrical parameters, focusing on temperature and pressure dynamics. Partial validation of the simulation results was achieved through temperature monitoring experiments under varying charge/discharge rates. The findings indicated that internal temperature uniformly increased, with higher rates leading to more pronounced rises, and identified that lithium dendrite formation and mechanical stress could initiate thermal runaway. To mitigate these risks, specific operational guidelines were suggested. The study also established a positive correlation between pressure changes and temperature, influencing the battery's volume. Temperature monitoring further validated the simulations′ precision. This research deepens the understanding of non‐electrical parameter functions during battery operation and provides scientific evidence for the prediction and prevention of lithium‐ion battery safety risks. [ABSTRACT FROM AUTHOR]

The role of internal variability in generating an apparent link between autumn Barents‐Kara sea (BKS) ice and the winter North Atlantic Oscillation (NAO) has been intensely debated. In particular, the robustness and causality of the link has been questioned by showing that BKS‐NAO correlations exhibit nonstationarity in both reanalysis and climate model simulations. We show that the lack of ice observations means nonstationarity cannot be confidently assessed using reanalysis prior to 1961. Model simulations are used to corroborate an argument that forced nonstationarity could result from ice edge changes due to global warming. Consequently, the observed change in BKS‐NAO correlations since 1960 might not be purely a result of internal variability and may also reflect that the ice edge has moved. The change could also reflect the availability of more accurate ice observations. We discuss potential implications for analysis based on coupled climate models, which exhibit large ice edge biases. Plain Language Summary: Does the amount of ice in the Barents‐Kara Sea influence European air pressure or are the patterns we see caused by random changes in the weather? In climate models and in estimates of the atmosphere's history these patterns change depending on which years we look at. This has been interpreted as evidence that the patterns are random. However, there are very few measurements of ice in this region before 1961, so we argue that looking at these years is not helpful. Since 1961, where we have more measurements, the winter sea ice edge has been moving Northwards because of global warming. When the ice in a particular region disappears, it changes the expected relationship with the atmosphere because heat can now quickly leave the ocean. We therefore hypothesize that some of the changes seen in the patterns may therefore not be random, but a result of ice edge changes. We also observe that different climate models put the ice edge in different places, and the same hypothesis therefore implies that models might not get potential ice‐air pressure relationships in specific regions correct. Key Points: A lack of observations means that ice‐NAO links cannot be confidently assessed with reanalysis prior to 1961Nonstationarity since 1961 may reflect forced changes to the ice edge, due to the dependence of heatflux anomalies on ice edge variabilityThe magnitude of this potential forced nonstationarity in the real world is currently unclear [ABSTRACT FROM AUTHOR]

Voice production of humans and most mammals is governed by the MyoElastic-AeroDynamic (MEAD) principle, where an air stream is modulated by self-sustained vocal fold oscillation to generate audible air pressure fluctuations. An alternative mechanism is found in ultrasonic vocalizations of rodents, which are established by an aeroacoustic (AA) phenomenon without vibration of laryngeal tissue. Previously, some authors argued that high-pitched human vocalization is also produced by the AA principle. Here, we investigate the so-called "whistle register" voice production in nine professional female operatic sopranos singing a scale from C6 (≈ 1047 Hz) to G6 (≈ 1568 Hz). Super-high-speed videolaryngoscopy revealed vocal fold collision in all participants, with closed quotients from 30 to 73%. Computational modeling showed that the biomechanical requirements to produce such high-pitched voice would be an increased contraction of the cricothyroid muscle, vocal fold strain of about 50%, and high subglottal pressure. Our data suggest that high-pitched operatic soprano singing uses the MEAD mechanism. Consequently, the commonly used term "whistle register" does not reflect the physical principle of a whistle with regard to voice generation in high pitched classical singing. [ABSTRACT FROM AUTHOR]

The proton exchange membrane fuel cell (PEMFC) air supply system is a complex nonlinear system with strong coupling of air flow and pressure. To avoid oxygen starvation and unstable output performance during rapid load changes, the oxygen excess ratio (OER) and air pressure need to be controlled effectively. To cope with the nonlinearity, coupling and uncertainty of the PEMFC air system, this paper puts forward a coordinated controller regulating OER and air pressure based on the input-output linearization and sliding mode methods. Firstly, a control-oriented third-order model is proposed to describe the dynamic behavior of the air supply system. Secondly, this paper decouples the flow and pressure of the PEMFC air system by using an input-output linearization method to obtain two independent linear subsystems. Moreover, a sliding mode method, effectively coping with the uncertainty of the system model, is designed to regulate the OER and air pressure of the PEMFC, which enhances the robustness of the control system. The overall simulation outcomes show that the proposed controller regulates OER and cathode pressure with smaller root mean square error (RMSE) and mean absolute percentage error (MAPE) compared with the combined proportional integral (PI) and feedforward controller. • A modified model oriented to control of air supply system is proposed. • Input-output linearization and sliding mode are used to develop coordinated control strategies. • The outcomes illustrate that the air supply affects the output performance of the fuel cell. • Control performance in the presence of model uncertainty is verified. [ABSTRACT FROM AUTHOR]

This study continues the discussion on the surface modification of polymers using an atmospheric pressure plasma (APP) reactor in air. These results complement prior research focusing on nonpolar polymers. Polymers, such as polyethylene terephthalate, polyetheretherketone, and polymethyl methacrylate, containing structurally bonded oxygen are studied, representing a range of properties such as oxygen content, crystalline/amorphous structure, polarity, functionality, and aliphatic/aromatic structure. APP induces superior wetting properties on the hydrophilic polymer surfaces with rapid and uniform modification within 0.5 s of exposure. The amorphous structures undergo additional modification for longer exposure. Moreover, the aliphatic chain structures require longer plasma exposure to reach surface modification equilibrium. The polar polymers reach a limit level of modification corresponding to a minimum water contact angle of about 50°. The surface polarity increases on average by a factor of approximately two. The equilibrium values of the adhesion work attained after post-processing recovery fall within a limited range of about 100–120 mJ/m2. The enhancement of surface functionality through the creation of oxidized groups primarily depends on the initial oxygen content and reaches a limit of about 40 at.% oxygen. The surface properties of the treated polar surfaces exhibit good stability, comparable to that of the previously tested nonpolar polymers. [ABSTRACT FROM AUTHOR]

In recent years, the C4F7N mixed gas has attracted considerable attention for its outstanding insulation and arc-extinguishing capabilities, positioning it as a potential substitute for sulfur hexafluoride, SF6. However, there remains a limited understanding of the arc-extinguishing and insulation performance of C4F7N/CO2 mixed gas. In addition, there is limited research on high-current breaking in circuit breakers. Therefore, this study aims to investigate the arc characteristics and breaking behavior of 10%C4F7N/90%CO2 and 15%C4F7N/85%CO2 mixed gases using a magnetohydrodynamic model based on the 252kV air pressure circuit breaker. The dynamic characteristics of this mixed gas are compared with pure SF6 under short-circuit current breaking conditions, while analyzing different parameters of the C4F7N configuration. The results indicate that the mixed gas exhibits lower levels in terms of arc temperature, axial diffusion distance and pressure difference at the moment of arc initiation compared to pure SF6. Furthermore, increasing the inflating pressure can effectively enhance the breaking performance of the circuit breaker with 0.6 MPa, making it more suitable. Additionally, increasing the proportion of C4F7N in the mixed gases will cause the arc temperature to rise slightly at the initial arc and current crossing zero, but decrease at the peak current. The core pressure also rises significantly, with a greater pressure difference established in the compressor at moment of arc initiation. This study provides a reference for the design of an environmentally friendly circuit breaker and the selection of the mixed gas ratio. [ABSTRACT FROM AUTHOR]

Summary: Salmonella contamination of fish after harvest is a significant food safety risk. To control this risk, it was aimed to reduce Salmonella Enteritidis in sea bass by helium and air plasma. Considering that preserving the fresh properties of sea bass is important for industrial applicability, determining the sensory effects of plasma treatments was also aimed. Since air plasma would provide a cheaper and easier alternative to helium plasma, their effects were compared. Additionally, the in vitro effects of these treatments on Salmonella Enteritidis were also investigated. Air and helium plasma completely inhibited the initial load of S. Enteritidis (2.79 Log CFU) inoculated on agar surface after 10 min treatment. Then, the inoculated sea bass samples were exposed to air or helium plasma for durations ranging from 1 to 15 min. Air and helium plasma treatments for 10 min provided 0.90 log cfu g−1 and 1.13 Log CFU/g reductions, respectively, but longer treatments did not lead to further significant reductions. Sensory scores were all above 7 (good) when samples were treated with air or helium plasma for 1–10 min, but longer treatments resulted in lower scores. The reduction of S. Enteritidis and changes in sensory characteristics were interpreted together and it was concluded that 10 min of air or helium plasma provided maximum reduction without causing any significant sensory changes. Overall, the current study showed that atmospheric pressure air and helium plasmas can be useful for ensuring post‐harvest safety in the fish trade. [ABSTRACT FROM AUTHOR]

This paper presents a motion sensor-based haptic master controller capable of static and dynamic force presentation by the newly invented Finger Band Soft Actuator (FBSA). The master controller operates a surgical assist robot using the $ 6 $ 6 degrees of freedom position and posture data tracked by an optical motion capture. The haptic force presentation can be realized by the pneumatic pressure of FBSA, which can be highly integrated into the controller mechanism to maintain precise manipulability. The FBSA can present a pressing force of 3.7 N for a small-sized finger and 5.1 N for a large-sized finger at an internal pressure of 60 kPa, and there is a monotonically increasing and decreasing relationship between the air pressure and the pressing force. The effectiveness of haptic force presentation by the FBSA was experimentally evaluated in the master-follower operation of a surgical assist robot. Ten subjects performed the task of pulling a suture thread and controlled the manipulation to achieve the directed tension. The experimental result shows that with the four levels of force presentation scheme by the FBSA, the error between suture tension and target operating force is significantly smaller than without force presentation. [ABSTRACT FROM AUTHOR]

• Quantifying the impact of peer pressure on environmental improvements among local governments in China. • Investigating cities ' reaction to declining air quality rankings through regression discontinuity design. • Demonstrating the efficacy of political incentives in combating pollution and the catalytic effect of rankings on policy action. • Assessing the benefits resulting from air pollution reductions using an exposure response function. This paper estimates the impact of peer governmental pressure on air quality using a regression discontinuity design inherent in China's air quality ranking system. Because air quality rankings are important for political evaluations, local officials who witnessed a decline in air quality ranking are motivated to enforce more stringent environmental standards compared to their counterparts with increased rankings. By exploiting this regulatory discontinuity with monthly air quality ranking data from 2012 to 2020 of 169 cities, we find that cities experiencing a lower air quality ranking in the current month compared to the previous month exhibit a subsequent improvement in air quality during the following month, as evidenced by decreased pollutant concentrations. Furthermore, our analysis reveals that in cities where pollutant rankings decline more sharply, officials are less likely to encounter fewer promotion opportunities. Importantly, we observe that the discontinuity in individual pollutant concentrations is not solely influenced by their respective rankings but is also impacted by the overall A ir Q uality I ndex (AQI) ranking. Linking the reduction in air pollutants concentration with the economic benefits, a back-of-the-envelope calculation indicates the decrease in premature deaths due to cardiovascular and respiratory diseases amounts to approximately 200 thousand, resulting in an associated economic saving of more than 600 billion Chinese yuan. [ABSTRACT FROM AUTHOR]

Suction stress is one of the most significant factors affecting the serviceability and stability of soil structures. This study presents a framework for analyzing the stability of geosynthetic reinforced soil (GRS) walls and slopes under unsaturated conditions. An analytical formulation of suction stress-based effective stress was implemented into a limit equilibrium solution, namely, the top-down procedure. The developed framework enables the prediction of the tensile load distribution and connection load between the reinforcement and wall face considering the pullout resistance of reinforcements in GRS walls backfilled with granular and marginal soils under unsaturated conditions. The applicability of the framework was demonstrated by providing an illustrative example followed by three series of parametric studies to understand the effects of pore size distribution, air entry pressure, and infiltration rate on the performance of an unsaturated GRS wall. The results quantify the impact of suction, showing that as it increases, the maximum tensile loads and connection loads decrease while pullout resistance increases. Mostly affected by the suction effect are upper reinforcement layers, where combined effects of reduced tensile load and increased pullout resistance decrease connection load and reinforcement length requirements. The current study strongly discourages counting on the contribution of suction for the design of new GRS walls. The suction value cannot be accurately and reliably determined for the entire lifespan of the GRS wall, and it may decrease or diminish in an uncontrolled and random manner under infiltration. However, by quantifying the effect of suction, the proposed framework in this study provides a valuable tool for analysis purposes, enabling a rigorous interpretation of field-measured reinforcement loads during wall service as well as evaluation of the forensics of failed GRS walls. [ABSTRACT FROM AUTHOR]

In diploid organisms, half of the chromosomes in each cell come from the father and half from the mother. Through previous studies, it was found that the paternal chromosome and the maternal chromosome can be regulated and expressed independently, leading to the emergence of allele specific expression (ASE). In this study, we analyzed the differential expression of alleles in the high-altitude population and the normal population based on the RNA sequencing data. Through gene cluster analysis and protein interaction network analysis, we found some changes occurred at the gene level, and some negative effects. During the study, we realized that the calmodulin homology domain may have a certain correlation with long-term survival at high altitude. The plateau environment is characterized by hypoxia, low air pressure, strong ultraviolet radiation, and low temperature. Accordingly, the genetic changes in the process of adaptation are mainly reflected in these characteristics. High altitude generation living is also highly related to cancer, immune disease, cardiovascular disease, neurological disease, endocrine disease, and other diseases. Therefore, the medical system in high altitude areas should pay more attention to these diseases. [ABSTRACT FROM AUTHOR]

In the field of metal-based bone tissue engineering scaffolds, porous Zn-based scaffolds are expected to be one of the most promising biodegradable bone tissue engineering scaffolds due to their acceptable biocompatibility and more suitable degradation rate compared with Mg-based and Fe-based scaffolds. However, the poor mechanical strength of porous pure Zn scaffolds limits their clinical applications. To improve the mechanical properties of porous Zn scaffolds, alloying treatment has become a feasible method. In this work, porous Zn-Mg-Y alloy scaffolds were prepared by an air pressure infiltration (API) method using NaCl particles as spacing holders. The phase structures, microstructures, compressive mechanical properties, degradation properties, antibacterial abilities as well as cytotoxicity of the obtained porous Zn-Mg-Y alloy scaffolds were investigated. The experimental results suggest that the alloy scaffolds contain strengthening phases such as MgZn2 and/or Mg2Zn11 as well as Y-rich phases. Under the action of these strengthening phases, the porous Zn-Mg-Y alloy scaffolds exhibit better mechanical properties. In vitro degradation tests indicate that the strengthening phases such as MgZn2 and Mg2Zn11 in the alloy scaffolds can be preferentially degraded as sacrificial anodes. Correspondingly, the degradation rates of the porous Zn-Mg-Y alloy scaffolds in simulated body fluid (SBF) have been accelerated. Antibacterial tests imply that the porous Zn-Mg-Y alloy scaffolds possess excellent antibacterial ability against Escherichia coli similar to the porous pure Zn scaffolds. Cytotoxicity tests show that the Zn2+ concentrations in the 100% extracts prepared from the porous Zn-Mg-Y alloy scaffolds (not including Zn-3Mg-0.5Y alloy scaffold) were all lower than that prepared from the porous pure Zn scaffold. The 25% and 10% extracts prepared from all the porous Zn-Mg-Y alloy scaffolds exhibit excellent cellular activity on MC3T3-E1 cells. In summary, the porous Zn-Mg-Y alloy scaffolds have the potential to be used as bone tissue engineering scaffolds to withstand relatively large loads. [ABSTRACT FROM AUTHOR]

The escalating concern regarding increasing air pollution and its impact on the health risks associated with PM2.5 in developing countries necessitates attention. Thus, this study utilizes the WRF-CMAQ model to simulate the effects of meteorological conditions on PM2.5 levels in Changchun, a typical city in China, during January 2017 and January 2020. Additionally, it introduces a novel health risk-based air quality index (NHAQI) to assess the influence of meteorological parameters and associated health risks. The findings indicate that in January 2020, the 2-m temperature (T2), 10-m wind speed (WS10), and planetary boundary layer height (PBLH) were lower compared to those in 2017, while air pressure exhibited a slight increase. These meteorological parameters, characterized by reduced wind speed, heightened air pressure, and lower boundary layer height—factors unfavorable for pollutant dispersion—collectively contribute to the accumulation of PM2.5 in the atmosphere. Moreover, the NHAQI proves to be more effective in evaluating health risks compared to the air quality index (AQI). The annual average decrease in NHAQI across six municipal districts from 2017 to 2020 amounts to 18.05%. Notably, the highest health risks are observed during the winter among the four seasons, particularly in densely populated areas. The pollutants contributing the most to the total excess risk (ERtotal) are PM2.5 (45.46%), PM10 (33.30%), and O3 (13.57%) in 2017, and PM2.5 (67.41%), PM10 (22.32%), and O3 (8.41%) in 2020. These results underscore the ongoing necessity for PM2.5 emission control measures while emphasizing the importance of considering meteorological parameters in the development of PM2.5 reduction strategies. [ABSTRACT FROM AUTHOR]

Droplet size is a crucial success factor for increased particle size in the agglomeration process. Thus, this work aimed to analyze the physicochemical properties of maltodextrin solutions used as the binder, their influence on the size of the formed droplets, and their relationship to particle growth. The primary CMC particles had an average size of 295.5 ± 10.0 µm, and at the end of the process, the agglomerates reached chord lengths ranging from 336.5 ± 10.6 µm to 378.3 ± 8.6 µm. Three maltodextrin solutions (5.0%, 20.0%, and 35.0% w/w) were characterized for that in terms of physicochemical properties and droplet size, and following that, the binder concentrations, binder flow rate, and atomizing air pressure were evaluated. The binder liquid concentration is the most outstanding parameter for the agglomeration process regarding particle growth under experimental conditions. [ABSTRACT FROM AUTHOR]

The development of low‐cost and convenient procedure to produce large‐area reconfigurable chiroptical meta‐devices (CMDs) enantiomers with dynamically tunable chiroptical response in the visible band has generated significant interest, owing to its tremendous potential for applications such as optical rotary filtering, color switching, information storage, etc. Currently, many methods, such as phase change material, air pressure, bias, etc., are proposed to reconfigure the chiroptical response of the CMDs enantiomers, but still lack of ability to actively regulate the chiroptical response of the large‐area CMDs. Herein, the centimeter‐scale stressmechanically reconfigurable CMDs enantiomers with actively‐tunable chiroptical response in the visible band is proposed. The chirality sign switching and chirality intensity turning on–off of the CMDs enantiomers can be achieved by bending the flexible substrate to the desired curvature radius to turn the electromagnetic modes resonance of the CMDs enantiomers. The results provide an effective approach to supply the large‐area reconfigurable CMDs enantiomers with actively tunable chiroptical response and will open up new possibilities for chirality nanophotonic applications. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis (RA) is a chronic disease, in which permanent joint deformation is largely preventable with the timely introduction of appropriate treatment strategies. However, there is no consensus for patients with RA to monitor their progress and communicate it to the rheumatologist till the condition progresses to remission. In response to this unmet need, we proposed the design of a self-measuring device based on bioelectrical impedance analysis (BIA) for regular monitoring of inflammation levels. Twenty joints of both hands were measured to monitor trends in inflammation levels. Three electrodes were used to measure two joints of each finger. A central electrode was used for two consecutive measurements. A suitable form factor for the device was proposed for the vertical placement of the hand. To ensure the stability of measurements, an air cushion was incorporated into the back of the hand, hand containers were designed on both sides, and a mobile application was designed. We conducted a convergence-assessment experiment with five air pressures to validate the consistency and convergence of bioimpedance measurements. A heuristic evaluation of the usability around the product and mobile application was conducted in parallel by six subject matter experts and validated the design. This study underscores the significance of considering patients' disease activity during intervals between hospital visits and introduces a novel approach to self-RA care. [ABSTRACT FROM AUTHOR]

Soft pneumatic robotics are designed for safe and compliant interaction with the environment or humans. However, the pneumatic systems used for actuation and protection are still relatively bulky and rely on rigid components such as solenoid valves and pressure regulators. This study presents the design and analysis of soft fibrous valves (SFVs) with internal tiny channels and external helical structures, which could be used in soft pneumatic systems. Made from soft material, SFVs demonstrate unique capabilities in controlling pressure by partial expansion under specific pressure. Three types of SFVs are designed: 1) SFV‐C is designed to protect soft pneumatic actuators by cutting off airflow under excessive pressure; 2) SFV‐M maintains pressure in actuators when the input pressure abruptly drops, preventing potential damage to the operated object; 3) SFV‐O produces oscillating pressure output without electronic control supplied by constant pressure source. Theoretical modeling and experimental validations are conducted to investigate the performance of the SFVs under various stretching, twisting, and pressure conditions. Furthermore, fully flexible SFVs are designed to enhance their compliance and resistance to external impacts. Overall, the SFVs offer promising solutions for pressure control and protection in soft pneumatic systems, enabling safer and more effective operations in various scenarios. [ABSTRACT FROM AUTHOR]

Surface air pressure is one of the most important parameters used in Numerical Weather Prediction (NWP) models. Although it has been measured using weather stations on the ground for many decades, the numbers of measurements are sparse and concentrated on land. Few measurements from buoys and ships are available over ocean. Global measurements can only be achieved by using remote sensing from Space, which is challenging; however, a novel design using Differential Absorption Radar (DAR) can provide a potential solution. The technique relies on two facts: first the electromagnetic fields are absorbed mainly by oxygen and water vapor, and second that oxygen is well mixed. In this work we discuss a space‐borne concept, which aims at providing, over the ocean, consistent, and regular observations for determining surface air pressure from space by a design of a multi‐tone radar operating on the upper wing of the O2 absorption band with tones from 64 to 70 GHz. Simulations of radar vertical profiles based on the output of a state of‐the‐art microphysical retrievals applied to the A‐Train suite of sensors are exploited to establish the performance of such a system for surface pressure determination. In particular the identification and quantification of errors introduced by the presence of water vapor, cloud liquid water and rain water and the potential of a correction via the three‐tone method is discussed. Errors introduced by surface measurement noise and temperature profile uncertainties are discussed as well. Results show that accuracy between 2 and 5 hPa is at reach. Plain Language Summary: Pressure is an important atmospheric variable. A radar‐based remote sensing techinque to measure surface pressure is proposed. The methodology is based on the darkening of the surface return when moving closer to the center of the 60 GHz oxygen absorption line. Results demonstrate that measurements of surface pressure with errors of few hPa are feasible. Key Points: Differential absorption radars with multiple tones within the oxygen band to enable surface pressure measurements with few hPa accuracyCloud, rain and water vapor produce biases in the surface pressure that must be correctedErrors can be minimized by adopting tunable frequencies and frequency diversity [ABSTRACT FROM AUTHOR]

Correcting atmospheric effects in measurements of vertical acceleration is challenging, particularly at frequencies above 0.3 mHz. Corrections based on 4-D atmosphere models should be the most effective, but are limited in temporal and spatial resolutions. So these models are commonly combined with a constant admittance between air pressure and gravity, though the correction can be further improved by allowing a frequency-dependent admittance. This paper studies the effectiveness of such procedures given that air pressure admittance varies with time because of variability in the underlying local atmospheric process, and finds that admittances estimated by cross-spectral analysis gives better results than a constant admittance does. The best results are achieved by combining a 4-D model with admittances estimated from time-series that cover the event of interest. [ABSTRACT FROM AUTHOR]

Meteorological factors and air pollutants are associated with the spread of pulmonary tuberculosis (PTB), but few studies have examined the effects of their interactions on PTB. Therefore, this study investigated the impact of meteorological factors and air pollutants and their interactions on the risk of PTB in Urumqi, a city with a high prevalence of PTB and a high level of air pollution. The number of new PTB cases in eight districts of Urumqi from 2014 to 2019 was collected, along with data on meteorological factors and air pollutants for the same period. A generalized additive model was applied to explore the effects of meteorological factors and air pollutants and their interactions on the risk of PTB incidence. Segmented linear regression was used to estimate the nonlinear characteristics of the impact of meteorological factors on PTB. During 2014–2019, a total of 14,402 new cases of PTB were reported in eight districts, with March to May being the months of high PTB incidence. The exposure–response curves for temperature (Temp), relative humidity (RH), wind speed (WS), air pressure (AP), and diurnal temperature difference (DTR) were generally inverted "U" shaped, with the corresponding threshold values of − 5.411 °C, 52.118%, 3.513 m/s, 1021.625 hPa, and 8.161 °C, respectively. The effects of air pollutants on PTB were linear and lagged. All air pollutants were positively associated with PTB, except for O3, which was not associated with PTB, and the ER values for the effects on PTB were as follows: 0.931 (0.255, 1.612) for PM2.5, 1.028 (0.301, 1.760) for PM10, 5.061 (0.387, 9.952) for SO2, 2.830 (0.512, 5.200) for NO2, and 5.789 (1.508, 10.251) for CO. Meteorological factors and air pollutants have an interactive effect on PTB. The risk of PTB incidence was higher when in high Temp-high air pollutant, high RH-high air pollutant, high WS-high air pollutant, lowAP-high air pollutant, and high DTR-high air pollutant. In conclusion, both meteorological and pollutant factors had an influence on PTB, and the influence on PTB may have an interaction. [ABSTRACT FROM AUTHOR]

The Hunga Tonga–Hunga Ha'apai volcanic eruption on January 15, 2022 generated a tsunami that affected the entire Pacific Ocean. Tsunami waves from the event have been generated both by incoming waves from the source area with a long-wave speed in the ocean of ~200–220 m/s, and by an atmospheric wave propagating at a sound speed of ~315 m/s. Such a dual source mechanism created a serious problem and was a real challenge for the Pacific tsunami warning services. The work of the Russian Tsunami Warning Service (Yuzhno-Sakhalinsk) during this event is considered in detail. The tsunami was clearly recorded on the coasts of the Northwest Pacific and in the adjacent marginal seas, including the Sea of Japan, the Sea of Okhotsk, and the Bering Sea. We examined high-resolution records (1-min sampling) of 20 tide gauges and 8 air pressure stations in this region for the period of January 14–17, 2022. On the Russian coast, the highest waves, with a trough-to-crest wave height of 1.3 m, were recorded at Malokurilskoe (Shikotan Island) and Vodopadnaya (southeastern coast of Kamchatka). Using numerical simulation and data analysis methods, we were able to separate oceanic "gravity" tsunami waves from propagating atmospheric pressure waves. In general, we found that on the outer (oceanic) coasts and southern coast of the Sea of Okhotsk, oceanic tsunami waves prevailed, while on the coast of the Sea of Japan, oceanic and atmospheric tsunami waves had similar heights. [ABSTRACT FROM AUTHOR]

Today, the biggest issue appears to be the increase in drought in some regions brought on by global warming, which has greatly increased the significance of water management. In light of evaporation's effect on drought, this research intends to evaluate the effectiveness of hybrid machine learning (ML) models, such as the Gradient Boosting Machines (GBM) technique paired with Empirical Mode Decomposition (EMD), Robust Empirical Mode Decomposition (REMD), Ensemble Empirical Mode Decomposition (EEMD), and Variational Mode Decomposition (VMD) signal decomposition techniques, for monthly evaporation prediction models in the Southeast Anatolia Project Area. In the design of the models, 80% of the data was used for training and 20% for testing. Furthermore, tenfold cross-validation was applied to solve the overfitting problem, which negatively affected the forecast performance. In the model setup, various combinations of precipitation, average air temperature, minimum air temperature, maximum air temperature, wind speed, actual air pressure, relative humidity, and solar time variables are presented to artificial intelligence models as input. The study revealed that the GBM methodology in combination with the signal decomposition methods REMD, EMD, EEMD, and VMD generally allowed for more accurate evaporation estimations than the GBM model alone. The study's results are essential in relation to agricultural production, irrigation planning, water resources management studies, and hydrological modeling studies in the region. [ABSTRACT FROM AUTHOR]

Nanosecond dielectric barrier discharge (NS-DBD) has emerged as a promising technique for controlling high-speed flows, generating a heated volume that generates strong density and viscosity gradients, thereby perturbing flow dynamics. Since its potential application in low-pressure, high-speed flows, understanding how the size and growth of the heated volume correlate with surrounding pressure is crucial. In this study, we employed typical schlieren and background-oriented schlieren (BOS) techniques to investigate the heated volume's sensitivity to surrounding pressure in quiescent air. The observed heated volume's size variations with surrounding pressure likely stemmed from the increase in thermal diffusivity at lower pressures. BOS findings unveiled a nearly linear decrease in heated volume's core density with energy input. Meanwhile, the heated volume's size augmented with energy input but exhibited gradual saturation, attributable possibly to shear stresses impeding volume expansion as temperature and viscosity rose, or to consumption of energy in vibration excitation and other reactions. In the cases of 100 and 50 kPa, the sensitivity of the heated volume's size to the reduced electric field appeared to be similar. However, at 10 kPa, where the reduced electric field is higher compared to that of the 100 and 50 kPa cases due to the lower air density, the size sensitivity drastically decreased. This suggested a transition in discharge mode from filamentary to diffusive behavior at lower pressures. [ABSTRACT FROM AUTHOR]

The use of direct ink writing technology, combined with in-situ grown whiskers, has facilitated the development of 3D-printed ceramic catalyst supports-aluminum borate porous ceramics (ABPCs) with hierarchical pore structures. The optimal slurry consists of 0.2 wt% polycarboxylate, 19 wt% water addition, and 1.2 wt% sodium alginate. The most effective printing parameters are determined to be a 1.0 mm nozzle diameter, 10 mm/s printing speed, 4.0 kPa air pressure, and 0.4 mm layer height. After sintering at 1100 ℃, pure-phase aluminum borate (Al 18 B 4 O 33) ceramics are achieved, leading to the formation of needle-like aluminum borate whiskers. The aspect ratio of whiskers, flexural strength, BET-specific surface area, and photocatalytic activity of ABPCs increase initially and then decrease with increasing sintering temperature. The ABPCs coated with a titanium oxide layer display a photocatalytic degradation rate of 83.92% for methyl orange solution. These results underscore the immense potential of ABPCs in high-temperature catalyst support applications. [ABSTRACT FROM AUTHOR]

Gas-powered jet nebulizers deliver medications to treat acute and chronic respiratory diseases. Several authors have found large variations in the performance of these nebulizers, and despite numerous attempts, deposition efficiency remains low for both adults and pediatrics. Using a Sympatec laser diffraction system and computational fluid dynamics (CFD) simulations with SolidWorks Flow Simulations and Ansys Fluent, this study uses a comparative analysis to explore the influence of supply air pressure, nozzle orifice diameter, and baffle geometry on jet nebulizer performance. Performance was quantified using critical performance metrics including vacuum levels driving aerosolization rate, Mass Median Aerodynamic Diameter (MMAD), and aerosolization time. Preliminary findings suggest that the authors' 2.54 mm wide, semi-conical bar baffle may produce superior vacuum levels, and surpasses the performance of the leading commercial bar baffle geometry, the SideStream, with a smaller MMAD (1.7 versus 2.3 microns). The study confirms the predicted relationship between supply pressure and nebulizer performance: higher pressure improves airflow rates, jet velocities, and aerosol characteristics, and reduces aerosolization times. Additionally, a larger nozzle orifice diameter increases airflow rates and promotes better aerosol characteristics, highlighting a direct correlation between orifice size and nebulizer performance. This work underscores the importance of expanding research in nebulizer performance beyond the traditional focus on testing paired nebulizer/compressor systems. Copyright © 2024 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

In recent years, railway vehicles have become lighter since it corresponds not only to the improvement of the running speed but also to the reduction of running cost and environmental noise. On the other hand, this causes an increase in the vertical elastic vibration of the car body and the riding comfort has deteriorated. Therefore, various strategies to reduce vertical vibration have been studied. In this study, vertical vibration reduction, by controlling the internal pressure of the air spring using µ-synthesis control, is proposed. The merit of µ-synthesis control is that it can guarantee robust performance. A controller by µ-synthesis was designed for vibration reduction of a 1/6 scale railway model and compared nominal performance and robust performance with H∞ control theory. Moreover, a feasibility study of this strategy was investigated for full-scale railway vehicles through simulation. [ABSTRACT FROM AUTHOR]

Air in the headspace of sewer laterals can be driven by the flowing sewage as well as air pressure. In this study, the openings on manholes for air flow are approximated as a thin continuous slot at the laterals. In this way, the governing equations can be solved analytically for infinitely long laterals without water flow. For cases with water flow, a numerical solution is developed. It is found that the air flow pattern in a long lateral can be categorized into three zones. The zone closest to the trunk is defined as the "zone of influence," where the air flow in the lateral is dominated by air pressure, and the air pressure and air velocity decay exponentially in the lateral. The second zone is named as "zone of equilibrium" where the air pressure gradient is zero and the air flow is only driven by the drag of water and can be calculated analytically. The air flow zone farthest from the trunk is defined as the "zone of induction" where the air is inducted into the system for mass balance in the system. An explicit fitting expression on the air velocity and water velocity in a long lateral is provided. A graphic solution for air velocity and zone of influence is also developed for a quick estimation on the air movement in sewer laterals. [ABSTRACT FROM AUTHOR]

Symmetric Aerostatic Cavities Bearing (SACB) systems have attracted increasing attention in the field of high-precision machinery, particularly rotational mechanisms applied at ultra-high speeds. In an air bearing system, the air bearing serves as the main support, and the load-carrying capacity is not as high as that of oil film bearings. However, the aero-spindle can operate at considerably high rotational speeds with relatively lower heat generated from rotation compared with that of oil film bearings. In addition, the operating environment of air bearings does not easily cause the rotor to deform. Hence, through adequate design, air pressure systems exhibit a certain level of stability. In general, the pressure distribution function of air bearings exhibits strong nonlinearity when there are changes in the rotor mass or rotational speed, or when the bearing system is inadequately designed. These issues may lead to instabilities in the rotor, such as unpredictable nonperiodic movements, rotor collisions, or even chaotic movements under certain parameters. In this study, rotor oscillation was analyzed using the maximum Lyapunov exponent to identify whether chaotic behavior occurred. Machine learning methods were then used to establish models and predict the rotor behavior. Especially, random forest and extreme gradient boosting were combined to develop a new model and confirm whether this model offered higher prediction performance and more accurate results in predicting tendencies with considerable changes compared with other models. The results can be effectively used to predict the SACB system and prevent nonlinear behavior from occurring. [ABSTRACT FROM AUTHOR]

Iatrogenic stomach perforation is a detrimental, irreversible, and fatal condition. Traditional surgery and endoscopic suturing clips and devices have been introduced to seal holes and prevent sepsis and disease progression. However, the development of endoscopic devices for perforations remains challenging, with no standard device available. This study investigates the superficial layer approximation strengths of the newly designed ENDOCRAB system for gastric wall defects. Thirty porcine stomachs were prepared ex vivo for the perforation model and distributed equally into three groups: ENDOCRAB system, Through-the-Scope Clip (TTSC), and hand suturing (HS). Both ENDOCRAB and TTSC achieved mucosal–submucosal layer apposition, whereas HS allowed a full-thickness layer. Their air leakage pressure and procedural duration were measured. The analysis of air-leakage pressure demonstrated comparable suture strength between ENDOCRAB (118.5 ± 41.7 mmHg) and HS (127.4 ± 30.2 mmHg, P = 0.812), but inferior strength with TTSC (73.6 ± 21.6 mmHg, P = 0.012). HS achieved the shortest procedural duration, whereas ENDOCRAB and TTSC showed no significant differences. The ENDOCRAB system showed significantly greater strength than the TTSC, was comparable to HS in strength, and required a procedural duration similar to that of the TTSC. Furthermore, long-term in vivo experiments and histological evaluations are essential. [ABSTRACT FROM AUTHOR]

Ebullition transports large amounts of the potent greenhouse gas methane (CH 4 ) from aquatic sediments to the atmosphere. River beds are a main source of biogenic CH 4 , but emission estimates and the relative contribution of ebullition as a transport pathway are poorly constrained. This study meets a need for more direct measurements with a whole-year data set on CH 4 ebullition from a small stream in southern Germany. Four gas traps were installed in a cross section in a river bend, representing different bed substrates between undercut and slip-off slope. For a comparison, diffusive fluxes were estimated from concentration gradients in the sediment and from measurements of dissolved CH 4 in the surface water. The data revealed highest activity with gas fluxes above 1000 ml m - 2 d - 1 in the center of the stream, sustained ebullition during winter, and a larger contribution of ebullitive compared to diffusive CH 4 fluxes. Increased gas fluxes from the center of the river may be connected to greater exchange with the surface water, thus increased carbon and nutrient supply, and a higher sediment permeability for gas bubbles. By using stable isotope fractionation, we estimated that 12-44% of the CH 4 transported diffusively was oxidized. Predictors like temperature, air pressure drop, discharge, or precipitation could not or only poorly explain temporal variations of ebullitive CH 4 fluxes. [ABSTRACT FROM AUTHOR]

In this study, the relationship between PM2.5 and ambient temperature, humidity, air pressure, wind speed and air indices was investigated by combining specific facilities at uranium mine with villages and cities. Humidity, atmospheric pressure and air quality index were positively correlated with PM2.5 concentration, whereas temperature and wind speed were negatively correlated, while altitude had no correlation with PM2.5 concentration. By constructing the corresponding PMF model data analysis, this study obtained six sources of eight metallic elements (U, Th, Al, Cu, Pb, Cd, Ti, Zn) in PM2.5 around a decommissioned uranium mine. [ABSTRACT FROM AUTHOR]

The effects of meteorological conditions on asthma in Haikou, a tropical city in China, are still unclear. This study aimed to determine the relationships between meteorological factors and the number of asthma hospital visits in Haikou. A Poisson generalized additive model combined with a distributed lag nonlinear model is used to model the nonlinear exposure–response relationship between the daily mean temperature and asthma hospital visits. The daily mean pressure and air quality are used as covariates and simultaneously control the mixed effects of holiday effects, weekend effects, and long-term trends. The results indicate that there is a significant statistical relationship between the daily mean temperature and asthma hospital visits, which shows an inverted J-shaped relationship. When the daily mean temperature is below the reference value (29.3 °C), the number of asthma patients increases considerably, and there is a marked lag in the prevalence of asthma. The longest lag is 9 days, and the most pronounced impact of the daily mean temperature on the number of asthma hospital visits can be found when the lag time is 1–4 days. When the daily mean temperature is 10 °C, the cumulative effect of the relative risk of asthma is 2.204, an increase of 120.4% (95% CI 1.294–3.755). If the daily mean temperature is below the 2.5th percentile value (14.8 °C), the relative risk significantly increases by more than 5.3% (95% CI 1.000–1.110), and the longest lasting impact time is 5 days. This indicates that increases in asthma hospital visits in Haikou, China, are significantly correlated with low-temperature weather. We suggest that preventive measures for asthma should take low-temperature weather into account. Additionally, we also found that extremely high temperatures have a certain impact on the increase in asthma hospital visits, but that the correlation is not significant. [ABSTRACT FROM AUTHOR]

This research focuses on the analysis of vibration of a compression ignition engine (CIE), specifically examining potential failures in the Fuel Rail Pressure (FRP) and Mass Air Flow (MAF) sensors, which are critical to combustion control. In line with current trends in mechanical system condition monitoring, we are incorporating information from these sensors to monitor engine health. This research proposes a method to validate the correct functioning of these sensors by analysing vibration signals from the engine. The effectiveness of the proposal is confirmed using real data from a Common Rail Direct Injection (CRDi) engine. Simulations using a GT 508 pressure simulator mimic FRP sensor failures and an adjustable potentiometer manipulates the MAF sensor signal. Vibration data from the engine are processed in MATLAB using frequency domain techniques to investigate the vibration response. The results show that the proposal provides a basis for an efficient predictive maintenance strategy for the MEC engine. The early detection of FRP and MAF sensor problems through a vibration analysis improves engine performance and reliability, minimizing downtime and repair costs. This research contributes to the advancement of monitoring and diagnostic techniques in mechanical engines, thereby improving their efficiency and durability. [ABSTRACT FROM AUTHOR]

Background: The combination of magnetic resonance imaging and proton therapy offers the potential to improve cancer treatment. The magnetic field (MF)‐dependent change in the dosage of ionization chambers in magnetic resonance imaging‐integrated proton therapy (MRiPT) is considered by the correction factor kB⃗,M,Q$k_{\vec{B},M,Q}$, which needs to be determined experimentally or computed via Monte Carlo (MC) simulations. Purpose: In this study, kB⃗,M,Q$k_{\vec{B},M,Q}$ was both measured and simulated with high accuracy for a plane‐parallel ionization chamber at different clinical relevant proton energies and MF strengths. Material and methods: The dose‐response of the Advanced Markus chamber (TM34045, PTW, Freiburg, Germany) irradiated with homogeneous 10 ×$\times$ 10 cm 2$^2$ quasi mono‐energetic fields, using 103.3, 128.4, 153.1, 223.1, and 252.7 MeV proton beams was measured in a water phantom placed in the MF of an electromagnet with MF strengths of 0.32, 0.5, and 1 T. The detector was positioned at a depth of 2 g/cm 2$^2$ in water, with chamber electrodes parallel to the MF lines and perpendicular to the proton beam incidence direction. The measurements were compared with TOPAS MC simulations utilizing COMSOL‐calculated 0.32, 0.5, and 1 T MF maps of the electromagnet. kB⃗,M,Q$k_{\vec{B},M,Q}$ was calculated for the measurements for all energies and MF strengths based on the equation: kB⃗,M,Q=MQMQB⃗$k_{\vec{B},M,Q}=\frac{M_\mathrm{Q}}{M_\mathrm{Q}^{\vec{B}}}$, where MQB⃗$M_\mathrm{Q}^{\vec{B}}$ and MQ$M_\mathrm{Q}$ were the temperature and air‐pressure corrected detector readings with and without the MF, respectively. MC‐based correction factors were determined as kB⃗,M,Q=DdetDdetB⃗$k_{\vec{B},M,Q}=\frac{D_\mathrm{det}}{D_\mathrm{det}^{\vec{B}}}$, where DdetB⃗$D_\mathrm{det}^{\vec{B}}$ and Ddet$D_\mathrm{det}$ were the doses deposited in the air cavity of the ionization chamber model with and without the MF, respectively. Furthermore, MF effects on the chamber dosimetry are studied using MC simulations, examining the impact on the absorbed dose‐to‐water (DW$D_{W}$) and the shift in depth of the Bragg peak. Results: The detector showed a reduced dose‐response for all measured energies and MF strengths, resulting in experimentally determined kB⃗,M,Q$k_{\vec{B},M,Q}$ values larger than unity. For all energies and MF strengths examined, kB⃗,M,Q$k_{\vec{B},M,Q}$ ranged between 1.0065 and 1.0205. The dependence on the energy and the MF strength was found to be non‐linear with a maximum at 1 T and 252.7 MeV. The MC simulated kB⃗,M,Q$k_{\vec{B},M,Q}$ values agreed with the experimentally determined correction factors within their standard deviations with a maximum difference of 0.6%. The MC calculated impact on DW$D_{W}$ was smaller 0.2 %. Conclusion: For the first time, measurements and simulations were compared for proton dosimetry within MFs using an Advanced Markus chamber. Good agreement of kB⃗,M,Q$k_{\vec{B},M,Q}$ was found between experimentally determined and MC calculated values. The performed benchmarking of the MC code allows for calculating kB⃗,M,Q$k_{\vec{B},M,Q}$ for various ionization chamber models, MF strengths and proton energies to generate the data needed for a proton dosimetry protocol within MFs and is, therefore, a step towards MRiPT. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of different air diffusers on the oxygen transfer rate, water quality, and growth performance of the whiteleg shrimp, Penaeus vannamei, for 60 days using a recirculating aquaculture system. The first experiment was conducted with six treatments applying two different air diffusers regarding two treatments (TRT): (i) rubber aeration tube and (ii) airstone at three different air pressures (0.025, 0.05, and 0.075 Mpa), respectively. Based on the first experiment's results, the second experiment was designed with two treatments: TRT1 - rubber aeration tube and TRT2 - airstone. Results indicated that the standard oxygen transfer rate increased as the pressure increased. The rubber aeration tube and air stone showed no significant difference at pressure levels. Therefore, the second experiment used a pressure level of 0.025 Mpa for TRT1 and TRT2. The results from the second trial showed that the dissolved oxygen in TRT1 did not differ significantly from that in TRT2. At the same time, the other parameters, such as temperature, pH, and alkalinity, remained steady throughout the culture period. The survival rate and biomass had the highest values in TRT2, but no significant differences were found in growth performance compared to TRT1. The results of this study suggest that either rubber aeration tubes or air stones are feasible and effective alternatives to improve the water quality and growth performance of P. vannamei in experimental conditions. [ABSTRACT FROM AUTHOR]

Many scientific teams are currently studying the effects of plasma generated by nanosecond diffuse discharges on the surfaces of various materials in order to modify their properties. To achieve this, uniform plasma is required to act on the target being treated, which is often an electrode in a discharge system. Previously, the surface treatment uniformity of flat electrodes during a nanosecond discharge in a point-to-plane gap was studied by applying a carbon black layer, and a discharge mode was identified in which there was no erosion on the treated electrode. In this study, it was established that during a nanosecond discharge in air at atmospheric pressure in a non-uniform electric field, carbon black deposited on the surface of a flat anode can ignite. The conditions and dynamics of carbon black ignition during the nanosecond discharge were determined. It was observed that the carbon black is ignited on the surface and continues to combust in the gap in the form of flame plumes for tens of milliseconds. It was also found that the combustion of carbon black can occur in both diffuse and spark discharges. [ABSTRACT FROM AUTHOR]

Metrics to quantify regulation of plant water status at the daily as opposed to the seasonal scale do not presently exist. This gap is significant since plants are hypothesised to regulate their water potential not only with respect to slowly changing soil drought but also with respect to faster changes in air vapour pressure deficit (VPD), a variable whose importance for plant physiology is expected to grow because of higher temperatures in the coming decades. We present a metric, the stringency of water potential regulation, that can be employed at the daily scale and quantifies the effects exerted on plants by the separate and combined effect of soil and atmospheric drought. We test our theory using datasets from two experiments where air temperature and VPD were experimentally manipulated. In contrast to existing metrics based on soil drought that can only be applied at the seasonal scale, our metric successfully detects the impact of atmospheric warming on the regulation of plant water status. We show that the thermodynamic effect of VPD on plant water status can be isolated and compared against that exerted by soil drought and the covariation between VPD and soil drought. Furthermore, in three of three cases, VPD accounted for more than 5 MPa of potential effect on leaf water potential. We explore the significance of our findings in the context of potential future applications of this metric from plant to ecosystem scale. [ABSTRACT FROM AUTHOR]

Lamalunga Cave (Altamura, Southern Italy) is renowned for the discovery in 1993 of an excellently preserved Neanderthal skeleton. Given the importance of the findings and the potential use of Lamalunga speleothems for paleoclimate reconstructions, a detailed monitoring program was undertaken to investigate the connections between microclimate parameters and speleothem growth. The cave air temperature is characterized by annual sinusoidal cycles with increasing phase shift and decreasing thermal amplitude from ± 2.1°C to ± 0.04°C as a function of increasing rock overburden, and daily to sub-daily cycles induced by surface air pressure (SAP) variations characterized by strong 24-hour and 12-hour solar harmonic frequencies, with thermal amplitude decreasing from 0.0054°C to 0.0021°C in the deeper parts of the cave. The ventilation regime is mainly controlled by SAP fluctuations. Fast SAP rises can trigger "emptying events" during which most of the cave air is replaced and the CO2 concentration falls towards near-atmospheric values. The steady and gentle ventilation created by SAP fluctuations also influences the growth and morphology of calcite coralloids, with larger popcorn assemblages concentrated in the northern galleries and delicate branching morphologies prevailing along the South Gallery where stable temperature and relative humidity conditions occur. The study is a seminal example of how high-precision measurements of cave air temperature can provide a wealth of information on cave ventilation and thermal regime and provide valuable support for robust paleoclimate reconstruction from speleothems. [ABSTRACT FROM AUTHOR]

Directional changes in cutting maneuvers are critical in sports, where shoe torsional stiffness (STS) is an important factor. Shoes are designed based on different constructions and movement patterns. Hence, it is unclear how adjustable spacers into the sole constructions of air pressure chambers (APC) affect the STS in side-step cutting. Therefore, this study investigated the effects of altered STS through adjustable sole spacers on ground reaction force (GRF) and ankle and knee joint moments in side-step cutting. Seventeen healthy recreational athletes performed side-step cutting with experimental conditions including (i) barefoot (BF), (ii) unaltered shoes (UAS): soles consisting of APC, and (iii) altered shoes (AS): modified UAS by inserting elastomeric spacers into cavities formed by APC. Mechanical and biomechanical variables were measured. Significant differences were revealed across shoe conditions for impact peak (p = 0.009) and impulse (p = 0.018) in vertical GRF, time to achieve peak braking (p = 0.004), and peak propulsion (p = 0.025) for anterior-posterior GRF in ANOVA test. No significant differences were observed in GRF peaks and impulses between UAS and AS except for a trend of differences in impact peak (p = 0.087) for vertical GRF. At the ankle and knee joint, peak ankle power absorption (p = 0.019), peak knee internal rotation moment (p = 0.042), peak knee extension moment (p = 0.001), peak knee flexion moment (0.000), peak knee power absorption (p = 0.047) showed significant difference across three shoe conditions. However, no significant differences between the UAS and AS were noticed for peak joint moments and power. Altered shoe torsional stiffness did not significantly affect the peak forces and peak ankle and knee joint moments or powers; hence sole adjustment did not influence the cutting performance. This study might be insightful in sports footwear design, and adjusting shoe torsional stiffness by sole modification might be advantageous for athletes playing sports with cutting maneuvers to reduce the risk of injuries by controlling the twisting force at the ankle that frequently happens during cutting maneuvers. [ABSTRACT FROM AUTHOR]

Chemosensor technology for trace gases in the air always aims to identify these compounds and then measure their concentrations. For identification, traceable methods are sparse and relate to large appliances such as mass spectrometers. We present a new method that uses the alternative traceable measurement of the ionization energies of trace gases in a way that can be miniaturized and energetically tuned. We investigate the achievable performance. Since tunable UV sources are not available for photoionization, we take a detour via impact ionization with electrons, which we generate using the photoelectric effect and bring to sharp, defined energies on a nanoscale in the air. Electron impact ionization is thus possible at air pressures of up to 900 hPa. The sensitivity of the process reaches 1 ppm and is equivalent to that of classic PID. With sharpened energy settings, substance identification is currently possible with an accuracy of 30 meV. We can largely explain the experimental observations with the known quantum mechanical models. [ABSTRACT FROM AUTHOR]

Gas‐insulated switchgears (GIS) are crucial components of high‐voltage power transmission and distribution systems. Internal discharges within GIS have garnered significant attention in the field of power engineering. This study investigates the characteristics of internal discharge shock waves in GIS under an air pressure of 0.3 MPa and three different discharge gap conditions: 1, 1.5, and 2 mm. High‐speed shadowing techniques are used to analyse the propagation speed, morphology, and post‐wave parameters. The study findings reveal that although the characteristics of internal discharge shock waves in GIS noticeably change with the gap size, they also exhibit a consistent trend: as the gap size increases, the initial shock wave accelerates, intensifying the discharge. Simultaneously, the rate of attenuation rises, with the shock wave becoming weaker after ≈30 µs. Furthermore, the post‐wave parameters follow a similar pattern, with an increase in gap size leading to higher parameter values but also a faster decay rate. The parameters decay more rapidly between 10 and 20 µs, slow down between 20 and 30 µs, and ultimately stabilize after around 30 µs. The results of this study hold significant theoretical and practical implications for the monitoring, diagnosis, and prevention of internal discharges in GIS. [ABSTRACT FROM AUTHOR]

The development of a surface barrier discharge driven by a negative steplike voltage pulse with an amplitude of V = –8 kV in air at the atmospheric pressure and a pulse with an amplitude of V = –15 kV in nitrogen at a pressure of 6 atm is simulated numerically. Calculations for V = –8 kV were carried out using the local-electric-field and the local-electron-energy approximations. It is demonstrated that both approximations yield similar results on the dynamics of discharge development as a whole, the cathode-layer structure, and the field distribution at the front of the discharge. Substantial differences are observed in parameters of the discharge layer adjacent to the dielectric surface, which allowed to simulate an effect similar to filamentation of the discharge in nitrogen at a pressure of 6 atm and voltage of V = –15 kV in the local-energy approximation. [ABSTRACT FROM AUTHOR]

With more infrastructures being built in high-altitude regions, the impact of low atmospheric pressure on the stability of air bubbles in cementitious materials has aroused extensive attention. However, its influence is still inconclusive since it is difficult to isolate the factor of air pressure and study it. To solve this problem, the study investigated the bubble dynamic evolution in cement paste at standard atmospheric pressure (P = 0.1 MPa) and low atmospheric pressure (LAP = 0.8P, 0.6P, 0.4P, 0.2P) and revealed the mechanism of bubble instability under low atmospheric pressure. We established the bubble dynamic evolution equation in cement paste, computed the real-time bubble radius, resultant force, and critical time at different air pressure by MATLAB software. Results show that the maximum resultant force decreases by 50.0–57.7% when air pressure drops from P to 0.2P; both critical time (t ) and radius increment ( Δ R ) increase with the reduction of air pressure and the increase of initial radius. It indicates that when at 0.2P, the resultant force which inhibits bubble expansion is reduced, the time required to prevent bubble expansion increases by 94–137%, and Δ R grows 122–140% larger than that at P, and the bubble is more prone to instability and rupture than that at P. The key to improving bubble stability in low atmospheric pressure is to reduce the initial radius of bubbles and increase the strength of the bubble film. This work firstly discovered the impact of low atmospheric pressure on bubble dynamic evolution in cement paste and proposed a new perspective to explore bubble stability at low atmospheric pressure. [ABSTRACT FROM AUTHOR]