Events in physical chemistry.

Urban Air Quality in the Anthropocene

Abstract: Urban air quality in the U.S. has generally been improving for many decades. Decreasing emissions of nitrogen oxides (NOx) and anthropogenic volatile organic compounds (VOCs) have caused decreases in ozone concentrations, albeit in a highly non-linear fashion. In this seminar, I will present results from a summer 2022 study in the LA basin. We observed lower VOC emissions than during previous studies. However, concentrations of secondary pollutants had not decreased, indicative of changes in the NOx-VOC regime.

How does interfacial tension affect droplet nucleation and melting point depression in nanoparticles?

Interfacial tension controls many important nanoparticle physicochemical properties. As the particle diameter decreases the vapor pressure over a curved particle increases and the melting point decreases. This, in turn, influences phase transitions (nucleation of new particles, deliquescence and efflorescence, ice nucleation, and cloud droplet nucleation), the degree to which particles take up water at elevated relative humidity, and the tendency of particles to evaporate. Current theories are based on Gibbs’ thermodynamics, which yield the Kelvin equation and Gibbs-Thomson equation.

Inviting “Time" to Non-equilibrium Thermodynamics: Universal Laws and Design Principles

Traditional chemical theories often fall short when describing living systems, which operate far from equilibrium. This talk introduces two novel frameworks that incorporate time-dependent processes into non-equilibrium thermodynamics, aiming to bridge the gap between inert and living matter. (1) We reveal how certain catalytic reaction networks can perform counter-intuitive tasks under dynamically changing environments, such as inverting a spontaneous reaction, which is impossible in steady states.

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