Due to habitat loss the Texas horned lizard (THL) (Phrynosoma cornutum) population has declined across its historic range. To date, reintroduction attempts for the species have been unsuccessful, calling into question the suitability of the habitat. Texas horned lizards require suitable thermal habitat to meet their thermoregulatory needs, because of this, understanding the thermal habitat requirements of THLs is important. While the critical temperature limits and preferred body temperatures of THLs are established from laboratory studies, thermal habitat preferences for THLs in the wild are poorly understood. The objective of this study was to determine thermal habitat preferences and home range sizes of reintroduced THLs at Mason Mountain WMA compared to a nearby natural population of THLs on the White Ranch. We also compare the thermal conditions of different microhabitats between the two sites. To compare thermal conditions between the two sites, we used thermal dataloggers to record the temperatures in different microhabitats throughout the day at each study site, then compared how much of the time these data loggers were within the lizard’s optimal temperature range between the two study sites. Home ranges were calculated for lizards from the two study sites and average home range sizes between the two study sites were compared for significant differences. The ground temperature selected by the lizards versus random points were compared between the two study sites. These findings will improve our understanding of THL thermal ecology and reintroduction requirements.

Metal Halide Perovskites (MHPs) are an emerging type of semiconductor for use in electronic devices that produce or utilize light. MHPs have shown advantages over traditional semiconductors such as silicon due to ease of solution processing, high defect tolerance (defects are strained chemical bonds and/or missing atoms in the crystal lattice) and tunable emission of light color. MHPs have the chemical structure ABX3 where A is a monovalent cation (+1) such as cesium, methylammonium or formamidinium; B is a divalent cation (+2) such as lead or tin, and X is a halide such as chloride, bromide, or iodide. Their favorable properties have resulted in solar cells capable of 32.5% power conversion efficiency in a tandem perovskite/silicon solar cell. However, MHPs suffer from issues with long term stability brought about by exposure to air and moisture, as well as ion migration under illumination.
Crystal engineering and chemical passivation using small molecules have been implemented to improve the long-term stability and reduce ion migration. Incorporation of small molecules with charged groups onto a MHP helps to mitigate surface defects by occupying surface sites of missing atoms or strained bonds. Recent work has shown incorporation of these small molecules during MHP synthesis results in the formation of two dimensional layers on top of the three-dimensional perovskite crystal resulting in increased long-term stability, resistance to heat and moisture, and reduction in ion migration at grain boundaries. Current work in our lab involves synthesizing thin films of methylammonium lead tribromide by spin coating and incorporating a macrocycle based on triazine molecules for this purpose. This presentation focuses on the effects of triazine treatment on the above perovskite, as evaluated by photoluminescence microscopy, powder x-ray diffraction, and scanning electron microscopy.

Salt-induced diffusiophoresis is the migration of a colloidal particle in water caused by a salt concentration gradient. Recent studies have shown that diffusiophoresis can be used for controlling particle motion, with potential applications in separation science, microfluidics, and enhanced oil recovery. These applications are especially appealing for nanoparticles with host-guest properties such as micelles. In this work, Rayleigh interferometry was used to experimentally characterize diffusiophoresis of tyloxapol micelles in the presence of the strong salting-out agent, sodium sulfate, in water at 25oC. Our results show that micelle diffusiophoresis occurs from high to low salt concentration. A model based on micelle preferential hydration was used to quantitatively explain our findings. At relatively high salt concentrations, liquid-liquid phase separation (LLPS) was observed. Near this phase transition, micelle Brownian mobility was found to dramatically decrease, making micelle diffusiophoresis the dominant transport mechanism. Our work suggests that salting-out agents and proximity to LLPS can be used to control the motion of micelles and hydrophilic nanoparticles in general.

Catalases are a class of metalloenzymes responsible for the protection of cells from damage caused by hydrogen peroxide by converting it into water and oxygen. Manganese-based catalase (MnCAT) has been identified in different organisms as an antioxidant, raising the interest in developing small molecules as biomimetic models. A Mn(III) complex of pyclen, a 12-membered ring pyrinophane macrocycle, has previously shown to be a functional mimic of MnCAT in our laboratory. In the present study, modifications of the pyridinophane macrocycle were used to evaluate their impact on the catalytic disproportionation of hydrogen peroxide. Two series of ligands were studied: (1) varying the number of pyridine moieties within the macrocycle, and (2) substitutions in the 4-position of the pyridine ring. pH-potentiometric titrations were used to determine the formation constants (log ß) of each manganese complex, which allowed us to derive speciation curves in solution. The initial rates method was used to calculate the kinetic-relevant parameters for the disproportionation reaction. The results emphasize the effect of structural differences of the ligand on modulating the reactivity of manganese, which are the basis of a mechanistic study of the reaction that is currently underway.

N-alkylation of amino acid-containing pharmaceuticals has been shown to increase their respective oral availability and membrane diffusion. Macrocycles, too, have been an interest in modern drug design due to their ability to have a dynamic conformation and adopt a chameleon-like property to enhance the ability for the drug to be properly delivered in a multitude of environments, and similarly macrocycle's ability to fully envelope an active site to block enzymatic activity. In this project, four novel N-alkylated amino acid-linked triazine macrocycles were synthesized from cyanuric chloride using BOC-hydrazine, an N-alkylated amino acid, and dimethylamine. Coupling of the amino acids with EDC to form the acetal product and further acidification and removal of protecting groups with trifluoroacetic acid yielded macrocycles in good yield. Characterization via 1D and 2D NMR reveals the emergence of different conformations in varying proportions. These conformations result from by the restricted rotation around the Ar-N bonds of both the hydrazine and amino acid of the macrocycles. A previous, non N-alkylated, glycine macrocycle was used as a reference compound, and the emergence of the different conformations was not observed for this molecule. Furthermore, the N-methylated glycine macrocycle displayed an asymmetric configuration, whereas the proline macrocycle was too rigid around the Ar-N of the amino acid to form the different rotamers. The successful synthesis of these N-alkylated amino acid macrocycles shows that further customization of these triazine macrocycles is possible.