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    Remotely sensed atmospheric anomalies of the 2022 Mw 7.0 Bantay, Philippines earthquake
    (2025-02-15)
    Khan, Sohrab
    ;
    Shah, Munawar
    ;
    Jamjareegulgarn, Punyawi
    ;
    El-Sherbeeny, Ahmed M.
    ;
    Abukhadra, Mostafa R.
    Remote sensing satellites have emerged as invaluable tools for surveilling natural disasters with more inevitable insights at various altitudes in atmosphere for various precursors. Moreover, the methods and satellite data before and after any event need more understanding for predicting the main shock due to the complexity of precursors. This study involves data from multiple sensors to assess how atmospheric parameters change in space and time over the Mw 7.0 Bantay, Philippines epicenter. The methods of statistical analysis, Nonlinear Autoregressive Network with Exogenous Inputs (NARX), and Multilayer Perceptron (MLP) are applied to various atmospheric parameters, including Land Surface Temperature (LST), Air Temperature (AT), Relative Humidity (RH), and Outgoing Longwave Radiation (OLR) to identify abnormal atmospheric patterns associated with earthquakes (EQ). These analyses focus on 3–5 days before the earthquake day. For this purpose, we trained daily average indices of atmospheric parameters for the month leading up to and the 15 days following the main shock. Since variations are irregular, detection can be challenging with classical statistics; therefore, we leveraged supervised machine learning to detect anomalies promptly and minimize the chances of missed detection. Thus, these findings support the lithosphere-atmosphere–ionosphere coupling (LAIC) hypothesis and suggest the need for further investigation in future research.
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    Condensation reactions of propanal over CexZr 1-xO2 mixed oxide catalysts
    (2010-09-15)
    Gangadharan, Anirudhan
    ;
    Shen, Min
    ;
    Sooknoi, Tawan
    ;
    Resasco, Daniel E.
    ;
    Mallinson, Richard G.
    Vapor phase condensation reactions of propanal were investigated over Ce<inf>x</inf>Zr<inf>1-x</inf>O<inf>2</inf> mixed oxides as a model reaction to produce gasoline range molecules from short aldehydes found in bio-oil mixtures. Several operating parameters were investigated. These included the type of carrier gas used (H<inf>2</inf> or He) and the incorporation of acids and water in the feed. Propanal is converted to higher carbon chain oxygenates on Ce <inf>x</inf>Zr<inf>1-x</inf>O<inf>2</inf> by two pathways, aldol condensation and ketonization. The major products of these condensation reactions include 3-pentanone, 2-methyl-2-pentenal, 2-methylpentanal, 3-heptanone and 4-methyl-3-heptanone. It is proposed that the primary intermediate for the ketonization path is a surface carboxylate. The presence of acids in the feed inhibits the aldol condensation pathway by competitive adsorption that reduces the aldehyde conversion. Water also promotes ketonization and inhibits aldol condensation by increasing the concentration of surface hydroxyl groups that enhance the formation of surface carboxylates with the aldehyde. Hydrogen enhances cracking and production of light oxygenates and hydrocarbons. The light oxygenates may in turn be reincorporated into the reaction path, giving secondary products. However, the hydrocarbons do not react further. Analysis of the fresh and spent catalysts by XPS showed varying degrees of reduction of the oxide under different operating conditions that were consistent with the reaction results. Changing the proportion of the parent oxides showed that increased Zr favored formation of aldol products while increased Ce favored ketonization. This occurs by shifting the balance of the acid-base properties of the active sites. © 2010 Elsevier B.V.