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Creators/Authors contains: "Shields, George C"

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  1. Free, publicly-accessible full text available May 30, 2025
  2. Insight into the origin of prebiotic molecules is key to our understanding of how living systems evolved into the complex network of biological processes on Earth. 
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  3. One of the main sources of uncertainty for understanding global warming is understanding the formation of larger secondary aerosols. 
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  4. Secondary aerosols form from gas-phase molecules that create prenucleation complexes, which grow to form aerosols. Understanding how secondary aerosols form in the atmosphere is essential for a better understanding of global warming. 
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  5. How secondary aerosols form is critical as aerosols' impact on Earth's climate is one of the main sources of uncertainty for understanding global warming. The beginning stages for formation of prenucleation complexes, that lead to larger aerosols, are difficult to decipher experimentally. We present a computational chemistry study of the interactions between three different acid molecules and two different bases. By combining a comprehensive search routine covering many thousands of configurations at the semiempirical level with high level quantum chemical calculations of approximately 1000 clusters for every possible combination of clusters containing a sulfuric acid molecule, a formic acid molecule, a nitric acid molecule, an ammonia molecule, a dimethylamine molecule, and 0–5 water molecules, we have completed an exhaustive search of the DLPNO-CCSD(T)/CBS//ωB97X-D/6-31++G** Gibbs free energy surface for this system. We find that the detailed geometries of each minimum free energy cluster are often more important than traditional acid or base strength. Addition of a water molecule to a dry cluster can enhance stabilization, and we find that the (SA)(NA)(A)(DMA)(W) cluster has special stability. Equilibrium calculations of SA, FA, NA, A, DMA, and water using our quantum chemical Δ G ° values for cluster formation and realistic estimates of the concentrations of these monomers in the atmosphere reveals that nitric acid can drive early stages of particle formation just as efficiently as sulfuric acid. Our results lead us to believe that particle formation in the atmosphere results from the combination of many different molecules that are able to form highly stable complexes with acid molecules such as SA, NA, and FA. 
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  6. Undergraduate research and education are critical parts of the scientific ecosystem. Professors at primarily undergraduate institutions ({PUIs}) bear responsibility for molding young scientists while carrying out high quality research. In this Voices piece, researchers offer inspiring replies to the following prompt: in your role as a professor, what are the challenges and opportunities when conducting research at a {PUI}?}, 
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