Interpretable Machine Learning Models for Practical Antimonate Electrocatalyst Performance.

Computationally predicting the performance of catalysts under reaction conditions is a challenging task due to the complexity of catalytic surfaces and their evolution in situ, different reaction paths, and the presence of solid-liquid interfaces in the case of electrochemistry. We demonstrate here how relatively simple machine learning models can be found that enable prediction of experimentally observed onset potentials. Inputs to our model are comprised of data from the oxygen reduction reaction on non-precious transition-metal antimony oxide nanoparticulate catalysts with a combination of experimental conditions and computationally affordable bulk atomic and electronic structural descriptors from density functional theory simulations.

Stochastic paleoclimatology: Modeling the EPICA ice core climate records.

We analyze and model the stochastic behavior of paleoclimate time series and assess the implications for the coupling of climate variables during the Pleistocene glacial cycles. We examine 800 kiloyears of carbon dioxide, methane, nitrous oxide, and temperature proxy data from the European Project for Ice Coring in Antarctica (EPICA) Dome-C ice core, which are characterized by 100 ky glacial cycles overlain by fluctuations across a wide range of timescales. We quantify this behavior through multifractal time-weighted detrended fluctuation analysis, which distinguishes near-red-noise and white-noise behavior below and above the 100 ky glacial cycle, respectively, in all records.

Bond dissociation energy of Au : A guided ion beam and theoretical investigation.

Guided ion beam tandem mass spectrometry was employed to measure the kinetic energy-dependent product ion cross sections for the collision induced dissociation of Au with Xe. Gold dimer cations were formed in a glow discharge flow tube source that should create ions in their ground electronic state with thermal internal energies. Analysis of the endothermic kinetic energy dependent cross section accounts for multiple collisions, lifetime effects, and the internal energy of the reactant ion.

Surprising behaviors in the temperature dependent kinetics of diatomic interhalogens with anions and cations.

Rate constants and product branching fractions of reactions between diatomic interhalogens (ICl, ClF) and a series of anions (Br, I) and cations (Ar, N) are measured using a selected ion flow tube apparatus and reported over the temperature range 200-500 K. The efficiency of both anion reactions with ICl is 2%-3% at 300 K to yield Cl, increasing with temperature in a manner consistent with the small endothermicities of the reactions. The anion reactions with ClF are 10%-20% efficient at 300 K to yield Cl and also show a positive temperature dependence despite being highly exothermic.

Temperature and Pressure Dependences of the Reactions of Fe with Methyl Halides CHX (X = Cl, Br, I): Experiments and Kinetic Modeling Results.

The pressure and temperature dependences of the reactions of Fe with methyl halides CHX (X = Cl, Br, I) in He were measured in a selected ion flow tube over the ranges 0.4 to 1.2 Torr and 300-600 K.