Density functional theory (DFT) calculations with a PBE+U functional and a larger supercell than used previously find that that the (100) and (001) surfaces reconstruct. These reconstructions involve fairly extensive rearrangements of the surface atoms and lead to changes in the density of states and the energies of oxygen-vacancy formation.

Molten lithium chloride, supported on various oxides, promotes the catalytic activity for oxidative dehydrogenation (ODH) of ethane. As a first step toward understanding these systems, we use ab initio molecular dynamics to examine the solvation of ethane, ethylene, oxygen, and water in molten lithium chloride supported on magnesium oxide. Among these molecules, only water dissolves readily in molten LiCl. Possible reactions between O2 and LiCl(l) have been studied in an effort to identify an intermediate for the ODH mechanism. We found that the formation of LiClO, LiO2, Li2O, LiOH, and Cl2 requires a substantial increase in the free energy; therefore, we propose that they are not reaction intermediates for ODH. The only process that cannot be ruled out is molecular adsorption of O2 at the LiCl/MgO interface.

Constant-temperature ab initio molecular dynamics is used to study reactions between molten LiI and gas phase molecules (O2, H2O, and I2) in an attempt to elucidate some aspects of the alkane oxidative dehydrogenation activity performed in the presence of molten LiI. We investigate the energy of reactions that produce LiIO, LiIO3, LiIO4, Li2O2, Li2O, LiOH, and I2. We find that the most favorable process is the formation of gaseous I2, coproduced with LiOH or Li2O (depending on the availability of water). If water is absent, then some LiIO4 will also be formed. However, this is unlikely to happen during oxidative dehydrogenation, because LiI is very hydroscopic and the oxidative dehydrogenation reaction produces water.

Coadsorbed water is often unavoidable in electrochemistry and low-temperature catalysis. In addition, water influences the adsorption of biomolecules on surfaces. We use ab initio DFT molecular dynamics and ground-state calculations to study the adsorption of HCl and catechol on the rutile TiO2(110) surface and at a water-rutile interface. We find that a coadsorbed water film reduces the adsorption energy of both catechol and HCl significantly because water molecules must be displaced from the surface before catechol or HCl can adsorb. The adsorption energy of catechol (or HCl) at the water-rutile interface can be estimated as the adsorption energy in vacuum minus the energy to remove two water molecules (respectively, one water molecule) from the rutile surface in vacuum and place them in liquid water. This estimate predicts the effect of a surface water film on adsorption without the need of molecular dynamics.

We report a computational fluid dynamics (CFD) study of containment of airborne hazardous materials in a ventilated room containing a downdraft table. Specifically, we investigated the containment of hazardous airborne material obtainable under a range of ventilation configurations. The desirable ventilation configuration should ensure excellent containment of the hazardous material released from the workspace above the downdraft table. However, increased airflow raises operation costs, so the airflow should be as low as feasible without compromising containment. The airflow is modeled using Reynolds Averaged Navier Stokes equations with a high Reynolds number k-epsilon turbulence model. CFD predictions are examined for several ventilation configurations. Based on this study, we find that substantial improvements in containment are possible concurrent with reduction in airflow, compared with the existing design of ventilation configuration.

The marine environment is a rich source of biodiversity, including microorganisms that have proven to be prolific producers of bioactive secondary metabolites. Arctic seas are less explored than warmer, more accessible areas, providing a promising starting point to search for novel bioactive compounds. In the present work, an Arctic marine Pseudomonas sp. belonging to the Pseudomonas (P.) fluorescence group was cultivated in four different media in an attempt to activate biosynthetic pathways leading to the production of antibacterial and anticancer compounds. Culture extracts were pre-fractionated and screened for antibacterial and anticancer activities. One fraction from three of the four growth conditions showed inhibitory activity towards bacteria and cancer cells. The active fractions were dereplicated using molecular networking based on MS/MS fragmentation data, indicating the presence of a cluster of related rhamnolipids. Six compounds were isolated using HPLC and mass-guided fractionation, and by interpreting data from NMR and high-resolution MS/MS analysis; the structures of the compounds were determined to be five mono-rhamnolipids and the lipid moiety of one of the rhamnolipids. Molecular networking proved to be a valuable tool for dereplication of these related compounds, and for the first time, five mono-rhamnolipids from a bacterium within the P. fluorescence group were characterized, including one new mono-rhamnolipid.