Temperature Extrapolation of Henry’s Law Constants and the Isosteric Heat of Adsorption

Computational screening of adsorbent materials often uses the Henry’s law constant (KH) (at a particular temperature) as a first discriminator metric due to its relative ease of calculation. The isosteric heat of adsorption in the limit of zero pressure (qst∞) is often calculated along with the Henry’s law constant, and both properties are informative metrics of adsorbent material performance at low-pressure conditions. In this article, we introduce a method for extrapolating KH as a function of temperature, using series-expansion coefficients that are easily computed at the same time as KH itself; the extrapolation function also yields qst∞. The extrapolation is highly accurate over a wide range of temperatures when the basis temperature is sufficiently high, for a wide range of adsorbent materials and adsorbate gases. Various results suggest that the extrapolation is accurate when the extrapolation range in inverse-temperature space is limited to |β – β0 | < 0.5 mol/kJ. Application of the extrapolation to a large set of materials is shown to be successful provided that KH is not extremely large and/or the extrapolation coefficients converge satisfactorily. The extrapolation is also able to predict qst∞ for a system that shows an unusually large temperature dependence. The work provides a robust method for predicting KH and qst∞ over a wide range of industrially relevant temperatures with minimal effort beyond that necessary to compute those properties at a single temperature, which facilitates the addition of practical operating (or processing) conditions to computational screening exercises

Temperature Extrapolation of Henry’s Law Constants and the Isosteric Heat of Adsorption

Computational screening of adsorbent materials often uses the Henry’s law constant (KH) (at a particular temperature) as a first discriminator metric due to its relative ease of calculation. The isosteric heat of adsorption in the limit of zero pressure (qst∞) is often calculated along with the Henry’s law constant, and both properties are informative metrics of adsorbent material performance at low-pressure conditions. In this article, we introduce a method for extrapolating KH as a function of temperature, using series-expansion coefficients that are easily computed at the same time as KH itself; the extrapolation function also yields qst∞. The extrapolation is highly accurate over a wide range of temperatures when the basis temperature is sufficiently high, for a wide range of adsorbent materials and adsorbate gases. Various results suggest that the extrapolation is accurate when the extrapolation range in inverse-temperature space is limited to |β – β0 | < 0.5 mol/kJ. Application of the extrapolation to a large set of materials is shown to be successful provided that KH is not extremely large and/or the extrapolation coefficients converge satisfactorily. The extrapolation is also able to predict qst∞ for a system that shows an unusually large temperature dependence. The work provides a robust method for predicting KH and qst∞ over a wide range of industrially relevant temperatures with minimal effort beyond that necessary to compute those properties at a single temperature, which facilitates the addition of practical operating (or processing) conditions to computational screening exercises

Computational Study of the Stability of the Miniprotein Trp-Cage, the GB1 β‑Hairpin, and the AK16 Peptide, under Negative Pressure

Although hot, cold, and high pressure denaturation are well characterized, the possibility of negative pressure unfolding has received much less attention. Proteins under negative pressure, however, are important in applications such as medical ultrasound, and the survival of biopoloymers in the xylem and adjacent parenchyma cells of vascular plants. In addition, negative pressure unfolding is fundamentally important in obtaining a complete understanding of protein stability and naturally complements previous studies of high pressure denaturation. We use extensive replica-exchange molecular dynamics (REMD) simulations and thermodynamic analysis to obtain folding/unfolding equilibrium phase diagrams for the miniprotein trp-cage (α-structure, 20-residue), the GB1 β-hairpin (β-structure, 16-residue), and the AK16 peptide (α-helix, 16-residue). Although the trp-cage is destabilized by negative pressure, the GB1 β-hairpin and AK16 peptide are stabilized by this condition

Monte Carlo simulation of cylinders with short-range attractions

Cylindrical or rod-like particles are promising materials for the applications of fillers in nanocomposite materials and additives to control rheological properties of colloidal suspensions. Recent advances in particle synthesis allows for cylinders to be manufactured with short-ranged attractions to study the gelation as a function of packing fraction, aspect ratio and attraction strength. In order to aid in the analysis of small-angle scattering experiments of rod-like particles, computer simulation methods were used to model these particles with specialized Monte Carlo algorithms and tabular superquadric potentials. The attractive interaction between neighboring rods increases with the amount of locally-accessible surface area, thus leading to patchy-like interactions. We characterize the clustering and percolation of cylinders as the attractive interaction increases from the homogenous fluid at relatively low attraction strength, for a variety of aspect ratios and packing fractions. Comparisons with the experimental scattering results are also presented, which are in agreement