Low Atmospheric Pressure Research Articles

Design, Optimization, and Autonomous Construction of Martian Infrastructure including Slabs Using In-situ CO2-Based Polyethylene

A crucial development in 21st-century space exploration is the establishment of human settlements on Mars. In recent years, Mars exploration rovers have been deployed, and studies investigating human journeys to Mars have been conducted, with the objective of a human-crewed mission to Mars before 2050. This study presents an innovative approach to designing and optimizing Martian habitats by using in-situ CO2-based polyethylene (PE) as a construction material for Martian buildings and greenhouses. It seeks to develop sustainable and resilient habitats on Mars, leveraging local resources to address the environmental challenges specific to the Martian environment. The research targets several key areas: realistic construction techniques, effective utilization of in-situ materials, and building resilience under the harsh Martian conditions. These conditions include radiation, micrometeoroid impacts, low atmospheric pressure, low gravity, wind storms, temperature extremes, Paschen discharge, and marsquakes. Finite element analysis (FEA) of several pressurized spherical structures is used to design and optimize for minimum material usage, inspired by soap bubbles that naturally stick together with separating walls. The proposed habitat design features a central spherical structure surrounded by nine smaller spheres, optimized for material efficiency. It is demonstrated that utilizing two layers of 0.1 m thick PE and a 0.5 m thick CO2 layer in between them offers significant protection against Martian environmental loads such as radiation shielding and thermal insulation. It facilitates light transmission into the building. This study offers a realistic structural system for buildings and greenhouses that can be constructed using in-situ materials and is suitable for an optimal 539-day stay on Mars. The proposed autonomous robotic arm technology can perform all necessary tasks, from producing PE to automatically assembling the Mars Spherical Building (MSB), including in-place slab printing.

Hydrogen production capabilities of lichens micro-ecosystem under extreme salinity, crystalline salt exposure, and simulated Mars-like conditions

This work aims to demonstrate the extremophilic behavior of the lichen Pleurosticta acetabulum at extreme salinities, while maintaining its metabolic capacity to produce hydrogen. Lichen is a special micro-ecosystem that includes mostly a fungus and a green alga or cyanobacterium, as well as a microbiome. The peculiarity of this symbiotic system is its ability to dry out completely and stay inactive to survive harsh conditions. Lichens that had been dehydrated for six months revived quickly when rehydrated, restoring their photosynthetic efficiency and ability to produce hydrogen. The lichen microbiome was crucial for hydrogen production, especially through dark fermentation. The experiments of this work showed that lichen during its exposure to different salinity conditions (0%NaCl – control, 3,5%NaCl – sea salt concentration, 36%NaCl – saturated salt concentration), but also after exposure to crystalline salt (100%NaCl) could maintain the structure and the functionality of its photosynthetic apparatus. This was tested using chlorophyll a fluorescence induction measurements. Based on the results of thermal conductivity gas chromatography (GC-TCD) for the determination of hydrogen production, it was shown that despite being exposed to extreme salinity conditions, lichens maintained its ability to produce hydrogen. The experimental combination of lichen exposure to extreme salinities (up to 100% NaCl), with an extreme atmosphere (100% CO2) and low atmospheric pressure (<10mbar), simulating Mars conditions, highlighted the functional potential of the lichen for survival in a Mars-like environment. This lichen’s ability to withstand extreme conditions and to produce large amounts of hydrogen, makes it a promising candidate for future biotechnological applications, even in challenging environments like Mars, opening new astrobiological and astrobiotechnological perspectives.

Advanced Dual Mixed Refrigerant (DMR) Natural Gas Liquefaction Plant with Liquid Air: Focus on Configuration and Optimization

This study introduces a novel approach to integrating LNG cold energy into the dual mixed refrigerant (DMR) process, employing liquid air as a cold energy carrier. The DMR process is chosen for natural gas liquefaction due to its flexibility in adjusting mixed refrigerant compositions when external cold sources are utilized. Two configurations are investigated: the low-pressure liquid air (LPLA) process, which relies solely on heat exchange, and the high-pressure liquid air (HPLA) process, which involves the pressurization and expansion of liquid air. Additionally, two optimization strategies are explored: 'With Composition' (WC) optimization, which includes refrigerant composition as a variable, and 'Without Composition' (WOC) optimization, which does not. Utilizing liquid air reduces the load on the refrigeration cycle, leading to improved performance compared to the conventional DMR process. The air expansion generates additional power and cold energy, while WC optimization further reduces the flow rate of low-boiling-point components, significantly lowering compression energy consumption. As a result, the DMR-HPLA-WC process achieves a 44.17% reduction in energy consumption, an 8.7% improvement in exergy efficiency, and a 37.63% decrease in specific costs.

Local two-group bubble size model for adiabatic air–water flow in a large diameter pipe using CFD code

Accurate prediction of bubble behavior in large diameter pipes is crucial for evaluating the performance of safety systems, steam generators, and heat exchangers in nuclear systems. Bubble behavior in large diameter pipes under two-phase flow significantly differs from that in small pipes. With the increasing use of computational fluid dynamics (CFD) codes, predicting interfacial area concentration (IAC) is critical for understanding multi-dimensional bubble behavior. This study developed a two-group local bubble size model for bubbly, slug, and churn flows under adiabatic conditions. The model includes correlations for void fraction and bubble sizes of two groups, which were implemented into CFD codes and validated against experimental data from large diameter pipes with low-pressure air–water flow. Results show the model's prediction accuracy surpasses existing correlations. The developed correlations are applicable across a range of flow conditions covering pipe diameters in the range 0.05–0.152 m, pressures from atmospheric to 300 kPa, superficial liquid velocities from 0.25 m/s to 2.85 m/s, and superficial gas velocities from 0.04 m/s to 5.48 m/s. The model is expected to enhance the prediction capabilities of CFD codes for the adiabatic two-group two-phase flows in the large diameter pipes.

Effect of steam curing regime on the mechanical properties, drying shrinkage, and microstructure of mortar in high-altitude areas with low air pressure

Low air pressure in plateau regions impacts the microstructure and macroscopic properties of cement-based materials by altering water transport. However, the efficiency of steam curing, a frequently-used curing approach, under these conditions has been inadequately studied. This work compares the effects of steam curing on the mechanical properties, drying shrinkage, and microstructure of cement-based materials at low air pressure. Results show that low air pressure decreases the compressive strength and increases the drying shrinkage of steam-cured mortar due to reduced hydration and increased total pore volume. Optimally, a steam curing temperature of 40°C to 60°C minimizes thermal damage, and a pre-curing time of 3 hours yields the best mechanical properties and drying shrinkage. Additionally, a field case confirms the effectiveness of the proposed steam curing regime; the demolding strength of precast beams meets engineering standards, and drying shrinkage fluctuates significantly with daily temperature changes. Notably, a 25.30 % difference in 90-day drying shrinkage between steam-cured and non-steam-cured specimens underscores the necessity of steam curing in high-altitude areas. These findings are crucial for optimizing steam curing practices in low-pressure environments.

Highly sensitive low-temperature, low-pressure ultra-thin microbubble FPI sensors

We present an ultrathin microbubble Fabry-Perot interferometer (FPI) sensor designed for low-pressure and low-temperature sensing applications. The preparation of the ultrathin microbubbles was achieved through an improved arc discharge technique. Consequently, a pressure sensitivity of 63 pm/kPa and a temperature sensitivity of 220 pm/°C at room temperature (20°C) and low air pressure (110–200 kPa) were attained, a performance that is highly commendable for a sensor of its kind. Furthermore, the use of a Bragg grating was employed to eliminate the effect of temperature on pressure, thereby enhancing the accuracy of the measured pressure. Experimental findings indicate that this ultrathin microbubble FPI sensor exhibits ultra-high sensitivity to pressure and temperature at low temperatures and pressures, offering what we believe to be a novel solution for the measurement of low temperatures and low-pressure environments.

The influence of unconventional assembly techniques on the comfort indicators of waterproof materials

The present paper aims to highlight the correlations between the comfort indicators of waterproof cotton-based fabrics, and the specific parameters of unconventional assembly technology. The materials considered include layers of Gore-Tex film, serving as substitutes for waterproof materials, intended to manufacture outerwear products such as protective equipment (jackets and overalls), which are breathable waterproof membranes. The comfort indicator values were obtained through standardised methods, and data processing and representation in two-dimensional (2D) and three-dimensional (3D) systems using correlation/graphing methods were carried out in Excel software, and using Jandel Table Curve 3D v2. Although experimental research can be extended to include specific functions related to durability indicators, this study focused theoretically and experimentally on how the variation in temperature of the low-pressure hot air jet can lead to changes in the vaporization coefficient, air permeability index, and thermal conductivity coefficient. The relationship between the comfort indicator values (thermal conductivity coefficient, air permeability index, and vapour permeability coefficient) of the considered materials and the treatment parameters of the installation (pressure, temperature, velocity) is expressed through statistically adequate mathematical models, highlighted by a correlation coefficient R = 0.983, with significance certified by the Fischer test. The study of comfort indicators was conducted under optimized treatment parameters, ensuring durability and presentation value functions in the treatment zone remain unchanged compared to those of the base materials.

Effect of porous defects on mechanical behavior of functionally graded materials

Porous defects in functionally graded materials (FGMs) significantly change their mechanical behavior, in particular, affecting the displacement of the neutral plane and stress distribution. Defects such as porosity reduce material bending strength while enhancing compression strength and can lead to significant transverse effects. The purpose of this study is to clarify the influence of porosity on transverse effects based on new kinematic model. This research consider in detail a particular case of this model, that allows take into account two Poisson`s effects separately. This study examines the influence of porosity on FGM, highlighting the critical role of changes in Poisson’s ratio through thickness. The theory used for analytical solution satisfies the nullity of the shear stresses at the upper and lower surfaces of the plate without using the shear correction factor. The network of pores proposed to be empty or filled with low-pressure air and material properties graded by thickness according to power-law and exponential models. Navier solution method is used to solve the governing differential equations of equilibrium. The concentration of porosity at the center of the plate or in separate layers results in a reduction in normal tensile stresses along the longitudinal coordinate, suggesting that strategic placement of porosity can be used to reduce stress concentrations, potentially enhancing the structural integrity and performance of functionally graded materials under mechanical loading.

Impact of typical environments in China's western mountainous areas on the durability of railway concrete: a review

PurposeThis study aims to analyze the impact mechanism of typical environments in China's western mountainous areas on the durability of railway concrete and propose measures to improve durability.Design/methodology/approachWith the continuous promotion of infrastructure construction, the focus of China's railway construction has gradually shifted to the western region. The four typical environments of large temperature differences, strong winds and dryness, high cold and low air pressure unique to the western mountainous areas of China have adverse effects on the durability of typical railway structure concrete (bridges, ballastless tracks and tunnels). This study identified the characteristics of four typical environments in the western mountainous areas of China through on-site research. The impact mechanism of the four typical environments on the durability of concrete in different structural parts of railways has been explored through theoretical analysis and experimental research; Finally, a strategy for improving the durability of railway concrete suitable for the western mountainous areas of China was proposed.FindingsThe daily temperature difference in the western mountainous areas of China is more than twice that of the plain region, which will lead to significant temperature deformation and stress in the multi-layered structure of railway ballastless tracks. It will result in cracking. The wind speed in the western plateau region is about 2.5 to 3 times that of the plain region, and the average annual rainfall is only 1/5 of that in the plain region. The drying effect on the surface of casting concrete will significantly accelerate its cracking process, leading to serious durability problems. The environmental temperature in the western mountainous areas of China is generally low, and there are more freeze-thaw cycles, which will increase the risk of freeze-thaw damage to railway concrete. The environmental air pressure in the western plateau region is only 60% of that in the plain region. The moisture inside the concrete is more likely to diffuse into the surrounding environment under the pressure difference, resulting in greater water loss and shrinkage deformation of the concrete in the plateau region. The above four issues will collectively lead to the rapid deterioration of concrete durability in the western plateau region. The corresponding durability improvement suggestions from theoretical research, new technology development and standard system was proposed in this paper.Originality/valueThe research can provide the mechanism of durability degradation of railway concrete in the western mountainous areas of China and corresponding improvement strategies.

Air infiltration characteristics in oxygen-enhanced and heated chambers on the Qinghai-Xizang Plateau

The Qinghai-Xizang Plateau is characterized by a low-pressure and oxygen-deficient environment due to its high altitude, causing discomfort and major safety problems for the inhabitants. To address this, oxygen-enriched chambers can be used to alleviate the plateau reaction. However, little consideration has been given to air infiltration in these chambers, with a lack of information on the corresponding infiltration heat loss phenomenon. This paper addresses this by investigating the phenomenon of air flow in an oxygen-enriched chamber using experiments and simulations. The results highlight that when there is a difference in oxygen concentration between the interior and exterior of the chamber, mass transfer occurs due to both the molecular diffusion in addition to a flow due to the air density difference caused by the variation in concentration. Also, the simultaneous stack effect is roughly equivalent to 10 times the oxygen pressure, and the two pressure effects act in opposite directions. It is also noted that both the oxygen pressure and the stack effect decrease as the atmospheric pressure decreases. Overall, the oxygen-enriched chambers exhibit less infiltration in plateau areas with a low atmospheric pressure compared to plains areas with a relatively high atmospheric pressure. Finally, this study establishes formulas that can be used to calculate air infiltration rates in oxygen-enriched chambers. This study fills a gap in the existing literature regarding the air infiltration mechanism in oxygen-enriched chambers at high altitudes and low pressures, providing a theoretical foundation for improving indoor environments in the Qinghai-Xizang Plateau and other high-altitude regions.

High-performance Multi-stage Baffled A2O Treatment Process for Domestic Sewage on Plateaus

At high altitudes, the low air pressure, low atmospheric oxygen content, and cryogenic environment during the cold season greatly limit the treatment efficiency of wastewater treatment plants (WWTPs). A novel pilot-plant configuration of the multi-stage baffled A2O wastewater treatment process was proposed and tested in Xizang. Different operational conditions involving at different influent loads and at low temperatures (10.0–11.0°C) were tested. When the influent flowrate increased to 4 m3∙d−1, the hydraulic retention time (HRT), internal and external reflux ratio, dissolved oxygen (DO), and aeration demands (gas to water ratio) all decreased to 34.2 h, 3.5/7, a stable 2.0–2.5 mg∙L−1, and 17.5, respectively. The effluent chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen (NH+4−N), and total phosphorus (TP) all met the requirements of Class 1 Grade A of the China National Municipal Wastewater Discharge Standards (GB 18918-2002). The contribution of denitrifying phosphorus removal (DPR) to the removal of both nitrogen and phosphorus was over 50%. The alpha diversity and abundance of the top genera in the microbial community structure were both higher than the plateau WWTP. The reaction activity of the DPR process was significantly enhanced via the increased abundance of key functional genes within the metabolism pathway of ammonia-oxidizing bacteria (AOB) and nitrogen-oxidizing bacteria (NOB). The special multi-stage baffled structure featured a strategy of high sludge storage that improved the system tolerance for low temperatures and ensured favorable and stable performance for nitrogen and phosphorus removal at low temperatures. A short, periodic, and cyclically intermittent operation mode, with each cycle lasting only 20 minutes, effectively inhibited filamentous bacteria sludge bulking, resulting in a sludge volume index (SVI) that decreased to within 120 mL∙g−1 during the first 15 days of system start-up. A long sludge retention time (SRT) with no sludge discharging over 169 days and reduced aeration demands contributed to lower operation costs. The investigation revealed that the system had a high capacity for storing sludge phosphorus, possessing a TP content within a range of 23.45–28.99 mg∙g−1. This study provides a feasible solution for efficiently and economically treating wastewater in high-altitude areas.

Pressure effects on superconductivity in EuSr2Bi2S2.5Se1.5F4 at 1 K

We performed electrical resistivity and X-ray diffraction measurements on the BiS2-based compound, EuSr2Bi2S2.5Se1.5F4, under high pressure using cubic and diamond anvil cells, respectively. We have also measured electrical resistivity at low temperatures and ambient pressures. The superconducting transition temperature (T c) was 1.13 K at ambient pressure and EuSr2Bi2S2.5Se1.5F4 was found to behave like a superconductor. Upon the application of increased pressure, T c increased and then decreased again, which was attributed to the structural phase transitions that accompany increased pressure in EuSr2Bi2S2.5Se1.5F4 superconductors.

An Indoor Air Quality Analysis in Newly Constructed Apartments

This study analyzes the indoor air quality inspections of newly constructed apartments by the Busan Institute of Health and Environment for the last three years (2021-2023). Of the 41 inspections, 33 exceeded the recommended standard, and the average excess rate was 80.5%. When classified by measuring households, 148 out of 332 exceeded the standards, whereas, the average excess rate by household was 44.6%. Benzene was exceeded in two out of the 332 households; therefore, the excess rate was only 0.6%. However, the relative standard deviation was the largest, showing as the highest item in the scattergram. The average concentration of toluene was 1,006.0 µg/m3, which was 100.6% of the recommended standard and was exceeded by 138 households; hence, the excess rate was 41.6%. All six items(Formaldehyde, Benzene, Toluene, Ethylbenzene, Xylene, Styrene) reached the highest concentration in spring or summer when the indoor temperature increased. The average concentration of toluene in July was 1,922 µg/m3, close to 1.9 times the recommended standard; toluene is considered an item of particular concern in summer. In the correlation analysis with indoor temperature, the formaldehyde coefficient of determination was 0.4855, regarded as somewhat significant; it was difficult to confirm the correlation with temperature for the other five items, including benzene. In correlation with relative humidity, formaldehyde showed the same tendency as indoor temperature, with a coefficient of determination of 0.4404, which is believed to be due to its small molecular weight and high solubility. Due to the chimney effect, high concentrations of volatile organic compounds could be confirmed at low atmospheric pressure in the upper floors, and this trend was most evident for formaldehyde. For most items(Formaldehyde, Benzene, Toluene, Ethylbenzene, Styrene), a negative correlation was confirmed in which the emission amount decreased as the number of households increased. For large apartment houses, it is believed that it is due to sufficient bake-out and flush-out according to the adequate construction period and the use of eco-friendly and high-end building materials. Small apartments are classified together with many small houses. The emission concentration of small houses is relatively high because the proportion of the surface area where pollutants are released is high.

Kinetic study on cyclopentane hydrates in the presence of sodium chloride

Water is an important resource for human life. The lack of clean water in the world now becomes more serious. As a result, seawater desalination to produce fresh water is becoming indispensable. In recent years, hydrate-based desalination is a potential solution for the drinking water shortage issue. Recently, Cyclopentane (CP) is used as a hydrate former for desalination process via crystallization at low temperature and atmospheric pressure. The objective of this study is to provide the new kinetic data of CP hydrates in the presence of sodium chloride with a concentration of 3.5 wt.%. The experimental data for CP hydrates in the presence of sodium chloride are obtained in a batch reactor system with a setup temperature range of -2.5 to -0.5 oC and at atmospheric pressure. The effects of temperature, agitation speed and amount of CP on kinetics of CP hydrate formation are also performed.

Study on the Impact of Air Pressure on the Laser-Induced Breakdown Spectroscopy of Intumescent Fireproof Coatings

Intumescent fireproof coatings protect steel structures and cables by forming a thick, fire-resistant layer under high temperatures. These coatings can deteriorate over time, impacting their fire resistance. Current testing methods are largely lab-based, lacking in-service evaluation platforms. Laser-Induced Breakdown Spectroscopy (LIBS) is emerging as a promising in situ detection technology but is influenced by low air pressure in high-altitude areas. This study investigates how air pressure affects LIBS signals in intumescent coatings on galvanized steel. Using pressures between 35 and 101 kPa, a linear model was developed to correlate laser pulses to ablation depth for characterizing coating thickness. Results show that spectral intensity decreases with lower air pressure. However, a strong linear relationship persists between laser pulses and ablation depth, with a fitting accuracy above 0.9. The coating thickness is identified by the number of laser pulses required to detect the Zn spectral line from the underlying galvanized steel. As air pressure decreases, the ablation depth increases. The study effectively models and corrects for air pressure effects on LIBS data, enabling its application for field detection of fireproof coatings. This advancement enhances the reliability of LIBS technology in assessing the fire performance of these materials, providing a reference for their in situ evaluation and ensuring better fire safety standards for building steel structures and cables.

Visualization of Injected Fuel Vaporization Using Background-Oriented Schlieren Method

In this experimental study, ethanol, an eco-friendly fuel used to reduce harmful exhaust emissions from internal combustion engines, was blended with gasoline. To optimize the combustion and the shape of the combustion chamber, the spray development and spray behavior of ethanol and gasoline were visualized and compared. Droplets of injected fuel were visualized using a high-speed camera. Because it is difficult to experimentally observe fuel vaporization using only high-speed cameras, the vaporization characteristics of the spray were compared and analyzed by using the background-oriented schlieren (BOS) method with density variation and image displacement in the spray flow field to visualize the vaporized fuel. The experimental results indicate that the fuel vaporization phenomenon could be observed during the spray development and that more fuel vaporization occurred at higher ambient temperatures and lower ambient pressures. Additionally, the dependence of the differences in the vaporization characteristics of the fuel and the wall-wetting phenomenon caused by the vaporized fuel was analyzed.

Numerical simulations of a low-pressure electrodeless ion source intended for air-breathing electric propulsion

Abstract Air breathing electric propulsion (ABEP) systems offer a promising solution to extend the lifetime of very low earth orbit (VLEO) missions by using residual atmospheric particles as propellants. Such systems would operate in very low-pressure environments where plasma ignition and confinement prove challenging. In this contribution, we present results of a global plasma model (GPM) of a plasma ignited in a very low-pressure air mixture. The results are validated against experimental measurements acquired using a laboratory electrodeless ion source utilizing a resonator for plasma ignition. The device is specifically designed to operate within low-pressure environments as it holds potential applications in ABEP systems for VLEO missions. Parametric studies are carried out via GPM to investigate the resonant behavior and its implications. The potential of the model serving as a predictive tool is assessed through experimental validation against measured data, mainly investigating the extracted ion current dependency on operational pressure and external magnetic field strength. The verified model is further utilized to extrapolate additional information about the resonant plasma such as ion composition or a degree of ionization.

PSIV-24 Evaluation of different colostrum feeding volumes on serum immunoglobulin G concentration and metabolic profiles of calves in high altitude area

Abstract Qinghai-Tibet Plateau is the highest plateau in the world, reputed as “the roof of the world” and “the world’s third pole”. Its ecological environment is characterized by low atmospheric oxygen pressure, cold, and limited feed supplies. This study aimed to investigate the serum immunoglobulin G (IgG) concentration and metabolic profiles of calves in high altitude area (3,650 m) fed different volumes of colostrum [8, 12, or 15% of birth body weight (BW)] using untargeted metabolomics strategies. Neonatal Holstein hybrid heifer calves (n = 44) were randomly divided into 1 of the 3 colostrum feeding amounts: 8% of birth BW (Low volume, L), 12% of birth BW (Middle volume, M), and 15% of birth BW (High volume, H) in colostrum. To safeguard the efficiency of colostrum intake, the colostrum was fed to calves within 0.5 h and 6 h after birth. The serum samples at 24 h after birth were collected for IgG concentration determination by indirect enzyme-linked immunosorbent assay (ELISA) and for LC-MS/MS metabonomic analysis. As the volumes of colostrum increased, there was a linearly increased in the serum IgG concentration (P &amp;lt; 0.01). Differential metabolites were selected according to the following 3 conditions: minimum fold change (FC) &amp;gt; 2, P-value &amp;lt; 0.01 in single-dimensional statistical analysis, and variable importance in projection (VIP) &amp;gt; 1 in the OPLS-DA model. Multivariate statistical analyses were performed to visualize differences among groups. Based on the screening criteria, a total of 3 differential metabolites (22 alpha-Hydroxy-campesterol, N-Myristoyl Histidine, and Calcitetrol) were detected between L and M, of which all differential metabolites were down-regulated. Six differential metabolites were detected between M and H, of which PC[P-18:1(11Z)/18:1(12Z)-2OH(9,10)] was up-regulated and 5 differential metabolites including 1-arachidonoyl-2-hydroxy-sn-glycero-3-phosphate, propanoyl phosphate, ascorbic acid 6-palmitate, 20-hydroxyecdysone, and 6’’’-deamino-6’’’-hydroxyparomomycin II were down-regulated. There were 28 differed metabolites (including leucyl-tryptophan, calcitetrol, 3’’-Oxoribostamycin) between L and H, of which 9 differential metabolites were up-regulated and 19 differential metabolites were down-regulated (Figure 1). Based on KEGG metabolic enrichment pathway analysis and pathway topology analysis, porphyrin metabolism was identified as the most impacted pathway between L and H (Figure 2). In conclusion, increasing colostrum volumes significantly increased serum IgG concentrations at 24 h after birth, favoring the success of the transfer of passive immunity. Alterations in serum metabolome of calves in the Qinghai-Tibet Plateau fed different volumes of colostrum were successfully revealed by untargeted metabolomics. The role of the identified differential metabolites and enriched pathway in the transfer of passive immunity in calves at high altitude deserves further investigation. Keywords: calf, colostrum volumes, high altitude area

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.

A Pneumatic Flexible Linear Actuator Inspired by Snake Swallowing.

Soft robots spark a revolution in human-machine interaction. However, developing high-performance soft actuators remains challenging due to trade-offs among output force, driving distance, control precision, safety, and compliance. Here, addressing the lack of long-distance, high-precision flexible linear actuators, an innovative pneumatic flexible linear actuator (PFLA) is introduced, inspired by the smooth and controlled process observed in snakes ingesting sizable food, such as eggs. This PFLA combines a soft tube, emulating the snake's body cavity, with a pneumatically driven piston. Through the joint modulation of moving resistance and driving force by pneumatic pressure, the PFLA exhibits exceptional motion control capabilities, including self-holding without pressure supply, smooth low-speed motion (down to 0.004 m s-1), high-speed motion (up to 5.6 m s-1) with low air pressure demand, and a self-protection mechanism. Highlighting its adaptability and versatility, the PFLA finds applications in various settings, including a wearable assistive devices, a manipulator capable of precise path tracking and positioning, and rapid transportation in diverse environments for pipeline inspection and firefighting. This PFLA combines biomimetic principles with sophisticated fluidic actuation to achieve long-distance, flexible, precise, and safe actuation, offering a more adaptive solution for force/motion transmission, particularly in challengingenvironments.