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1. Dielectrophoresis of air

   https://doi.org/10.1063/5.0002286  

   Soffer, Lucas; Rendos, Abigail; Zosuls, Aleksandrs L.; Walsh, Brian M.; Brown, Keith A. (February 2020, Applied Physics Letters)
2. Evaluation of Neural Network Verification Methods for Air-to-Air Collision Avoidance

   https://doi.org/10.2514/1.D0255  

   Manzanas Lopez, Diego; Johnson, Taylor T.; Bak, Stanley; Tran, Hoang-Dung; Hobbs, Kerianne L. (January 2023, Journal of Air Transportation)

   Neural network approximations have become attractive to compress data for automation and autonomy algorithms for use on storage-limited and processing-limited aerospace hardware. However, unless these neural network approximations can be exhaustively verified to be safe, they cannot be certified for use on aircraft. An example of such systems is the unmanned Airborne Collision Avoidance System (ACAS) Xu, which is a very popular benchmark for open-loop neural network control system verification tools. This paper proposes a new closed-loop extension of this benchmark, which consists of a set of 10 closed-loop properties selected to evaluate the safety of an ownship aircraft in the presence of a co-altitude intruder aircraft. These closed-loop safety properties are used to evaluate five of the 45 neural networks that comprise the ACAS Xu benchmark (corresponding to co-altitude cases) as well as the switching logic between the five neural networks. The combination of nonlinear dynamics and switching between five neural networks is a challenging verification task accomplished with star-set reachability methods in two verification tools. The safety of the ownship aircraft under initial position uncertainty is guaranteed in every scenario proposed. 

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3. Air entrapment, internal structure, and density of hydrophobic particle–water–air mixtures

   https://doi.org/10.1680/jenge.25.00003  

   Ma, Wenpei; Tomac, Ingrid (November 2025, Environmental Geotechnics)

   This paper investigates internal structure-driven density changes of post-wildfire and natural debris flows resulting from sand hydrophobicity and shearing. Hydrophobic sand particles entrap air by way of an armoured bubble/gas marble mechanism in water. Although individual armoured bubbles have already been broadly investigated, the effects of fluid drag and collisions in multiphase water–air–sand mixtures remain largely unexplored. The armoured bubbles’ stability in water depends on the force balance on the air bubble–particle boundary, which largely defines the mixture’s internal structure. Gravity, relative armoured bubble and fluid velocities govern the collision forces, local changes in mixture concentration, and the separation or attachment of hydrophobic particles to air bubbles in water. The initially large entrapped air volume decreases due to degassing and large armoured bubble breakdowns downstream. Experimental and theoretical approaches quantify the air entrapment under different sand-water volumetric concentrations, as well as the effects of mixing speed, duration, and sand particle size on the final mixture’s internal structure. Since hydrophobic sand particles can effectively entrap many air bubbles in the final debris flow-like mixture, the densities of debris flows that sweep over hydrophobic soil will accordingly reduce. Therefore, this paper proposes empirical estimates of density reductions resulting from air entrapment. 

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4. High Performance Air Breathing Flexible Lithium–Air Battery

   https://doi.org/10.1002/smll.202102072  

   Ahmad Jaradat, Chengji Zhang (January 2021, Small)

   null (Ed.)

   Lithium–oxygen (Li–O2) batteries possess the highest theoretical energy density (3500 Wh kg−1), which makes them attractive candidates for modern electronics and transportation applications. In this work, an inexpensive, flexible, and wearable Li–O2 battery based on the bifunctional redox mediator of InBr3, MoS2 cathode catalyst, and Fomblin-based oxygen permeable membrane that enable long-cycle-life operation of the battery in pure oxygen, dry air, and ambient air is designed, fabricated, and tested. The battery operates in ambient air with an open system air-breathing architecture and exhibits excellent cycling up to 240 at the high current density of 1 A g−1 with a relative humidity of 75%. The electrochemical performance of the battery including deep-discharge capacity, and rate capability remains almost identical after 1000 cycle in a bending fatigue test. This finding opens a new direction for utilizing high performance Li–O2 batteries for applications in the field of flexible and wearable electronics. 

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5. Distributed direct air capture by carbon nanofiber air filters

   https://doi.org/10.1126/sciadv.adv6846  

   Wu, Ronghui; Delgado, Hernan E; Xie, Yi; Chen, Yuanke; Yan, Gangbin; Luo, Edward; Li, Qizhang; Fan, Qingsong; Han, Yu; Higueros, Genesis M; et al (October 2025, Science Advances)

   The rising atmospheric CO₂concentration is one of the biggest challenges human civilization faces. Direct air capture (DAC) that removes CO₂from the atmosphere provides great potential in carbon neutralization. However, the massive land use and capital investment of centralized DAC plants and the energy-intensive process of adsorbent regeneration limit its wide employment. We develop a distributed carbon nanofiber (CNF)–based DAC air filter capable of adsorbing CO₂downstream in ventilation systems. The DAC air filter not only has the potential to remove 596 MtCO₂year⁻¹globally but can also decrease energy consumption in existing building systems. The CNF-based adsorbent has a capacity of 4 mmol/g and can be regenerated via solar thermal or electrothermal methods with low carbon footprints. Through life cycle assessment, the CNF air filter shows a carbon removal efficiency of 92.1% from cradle to grave. Additionally, techno-economic analysis estimates a cost of $209 to 668 in capturing and storing 1 tonne of CO₂from direct air. 

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