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1. Simultaneous tracking of ultrafast surface and gas-phase dynamics in solid-gas interfacial reactions

   https://doi.org/10.26434/chemrxiv-2024-v9xnx  

   Blackman, Keith; Segrest, Eric; Machamer, Kai; Turner, George; Gupta, Aakash; Pathan, Md_Afjal Khan; Berriel, S Novia; Banerjee, Parag; Vaida, Mihai (May 2024, ChemRxiv)

   Real-time detection of intermediate species and final products at the surface and near-surface in interfacial solid-gas reactions is critical for an accurate understanding of heterogeneous reaction mechanisms. In this contribution, an experimental method that can simultaneously monitor the ultrafast dynamics at the surface and above the surface in photoinduced heterogeneous reactions is presented. The method relies on a combination of mass spectrometry and femtosecond pump-probe spectroscopy. As a model system, the photoinduced reaction of methyl iodide on and above a cerium oxide surface is investigated. The species that are simultaneously detected from the surface and gas-phase present distinct features in the mass spectra, such as a sharp peak followed by an adjacent broad shoulder. The sharp peak is attributed to the species detected from the surface while the broad shoulder is due to the detection of gas-phase species above the surface, as confirmed by multiple experiments. By monitoring the evolution of the sharp peak and broad shoulder as a function of the pump-probe time delay, transient signals are obtained that describe the ultrafast photoinduced reaction dynamics of methyl iodide on the surface and in gas-phase. Finally, SimION simulations are performed to confirm the origin of the ions produced on the surface and gas-phase. 

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2. Simultaneous tracking of ultrafast surface and gas-phase dynamics in solid–gas interfacial reactions

   https://doi.org/10.1063/5.0217441  

   Blackman, Keith; Segrest, Eric; Turner, George; Machamer, Kai; Gupta, Aakash; Khan_Pathan, Md Afjal; Berriel, S Novia; Banerjee, Parag; Vaida, Mihai E (August 2024, Review of Scientific Instruments)

   Real-time detection of intermediate species and final products at the surface and near-surface in interfacial solid–gas reactions is critical for an accurate understanding of heterogeneous reaction mechanisms. In this article, an experimental method that can simultaneously monitor the ultrafast dynamics at the surface and above the surface in photoinduced heterogeneous reactions is presented. This method relies on a combination of mass spectrometry and femtosecond pump–probe spectroscopy. As a model system, the photoinduced reaction of methyl iodide on and above a cerium oxide surface is investigated. The species that are simultaneously detected from the surface and gas-phase present distinct features in the mass spectra, such as a sharp peak followed by an adjacent broad shoulder. The sharp peak is attributed to the species detected from the surface, while the broad shoulder is due to the detection of gas-phase species above the surface, as confirmed by multiple experiments. By monitoring the evolution of the sharp peak and broad shoulder as a function of the pump–probe time delay, transient signals are obtained that describe the ultrafast photoinduced reaction dynamics of methyl iodide on the surface and in the gas-phase. Finally, SimION simulations are performed to confirm the origin of the ions produced on the surface and in the gas-phase. 

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3. Extend Plastron Longevity on Superhydrophobic Surface Using Gas Soluble and Gas Permeable Polydimethylsiloxane (PDMS)

   https://doi.org/10.3390/biomimetics10010045  

   Gupta, Ankit; Ling, Hangjian (January 2025, Biomimetics)

   The gas (or plastron) trapped between micro/nano-scale surface textures, such as that on superhydrophobic surfaces, is crucial for many engineering applications, including drag reduction, heat and mass transfer enhancement, anti-biofouling, anti-icing, and self-cleaning. However, the longevity of the plastron is significantly affected by gas diffusion, a process where gas molecules slowly diffuse into the ambient liquid. In this work, we demonstrated that plastron longevity could be extended using a gas-soluble and gas-permeable polydimethylsiloxane (PDMS) surface. We performed experiments for PDMS surfaces consisting of micro-posts and micro-holes. We measured the plastron longevity in undersaturated liquids by an optical method. Our results showed that the plastron longevity increased with increasing the thickness of the PDMS surface, suggesting that gas initially dissolved between polymer chains was transferred to the liquid, delaying the wetting transition. Numerical simulations confirmed that a thicker PDMS material released more gas across the PDMS–liquid interface, resulting in a higher gas concentration near the plastron. Furthermore, we found that plastron longevity increased with increasing pressure differences across the PDMS material, indicating that the plastron was replenished by the gas injected through the PDMS. With increasing pressure, the mass flux caused by gas injection surpassed the mass flux caused by the diffusion of gas from plastron to liquid. Overall, our results provide new solutions for extending plastron longevity and will have significant impacts on engineering applications where a stable plastron is desired. 

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4. Working Memory: It’s a Gas, Gas, Gas

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   Zars, Troy (March 2017, Current Biology)
5. Unit Commitment Under Gas-Supply Uncertainty and Gas-Price Variability

   https://doi.org/10.1109/TPWRS.2016.2602659  

   Zhao, Bining; Conejo, Antonio J.; Sioshansi, Ramteen (May 2017, IEEE Transactions on Power Systems)