Category: Undergraduate

Naphthol reds are a group of widely used pigments with prominent historical, commercial, and cultural significance and are frequently characterized as part of a wider group called azo pigments. Azo pigments have two fundamental properties, they have the vibrant colors and low solubilities characteristic of pigments, and the presence of an azo group within their structure. The latter property, however, as other studies have found is oftentimes completely unfounded. Some of these pigments do not even possess azo groups at all, rather they possess a similar, but fundamentally different group known as a hydrazone group. In other cases these pigments can possess both the azo and hydrazone forms at the same time or undergo an enol/keto tautomeric shift under certain conditions. There are however still many common pigments which are still marketed and referred to as azo pigments with frequently little to no evidence. In this study by using the capabilities afforded to us by X-ray diffraction techniques as well as Rietveld refinement it was possible to determine not only the presence of the hydrazone group but also to elucidate the crystal structures of two pigments. Ultimately these results can fundamentally change both how we refer to these pigments from now on and how these pigments may be better used and applied in the future.

A concussion is a traumatic injury that affects brain function. Although sports-related concussions are so common, the physiology of concussions is still not yet fully understood. Nonetheless, several types of research are focusing on this study to explain the physiology of concussion and identify possible biological markers. Since blood vessels in the brain behave similarly to those in the other parts of the body, one can further study the brain and the concussion by measuring the blood pressure and flow. With this idea, a research study has found nitric oxide (NO) as an important biological marker for concussion, indicating either possible inhibition or stimulation of nitric oxide synthase (NOS) in our body. By incorporating this information into my project, I have performed Griess assay to measure nitrate and nitrite in blood samples extracted from SMU athletes who have experienced concussions.

Light-Oxygen-Voltage (LOV) domains, present in all kingdoms of life, facilitate regulation of light dependent events in organisms by transducing light input into physiological signals. Examination of plant and fungal circadian networks has revealed that signaling mechanisms differ even within homologs of closely related species. Structural and computational studies of LOV-allostery have identified key signaling “hot-spots” that allow modification of the direction and amplitude of signal output. One key regulatory site was identified in Plant LOV domain proteins ZTL and FKF1, in which the amino acid residue at position 46 differentiates ZTL and FKF1 signaling mechanisms. Notably, the residue at this position differentiates FKF1-based signaling in monocots and dicots (Ala and Ser, respectively). An analogous residue substitution is observed in the LOV domain photoreceptors of two closely related filamentous fungi, Neurospora crassa VIVID and Trichoderma reesei ENVOY, where divergent signaling mechanisms gate adaptation to oxidative stress. Herein, we sought to test whether residue identity at the position equivalent to ZTL G46 (VIVID A72 and ENVOY S99) alters signal transduction in VIVID and ENVOY. To propagate signal transduction of blue-light, wildtype VVD forms a rapidly dissociating dimer whereas wildtype ENV requires oxidative conditions to form an irreversible disulfide dimer. Size exclusion chromatography (SEC) characterization revealed VVD A72S exhibits reduced dimerization capability and dimerizes at high concentrations only. Furthermore, ENV S99A dimerized under reducing conditions with a similar concentration-dependent increase in dimeric fraction. This altered dimerization capacity demonstrates evolutionary selection of G46 equivalent residues in differentiating LOV-domain photoreceptors and their signal transduction mechanisms.

A cross-linked degradable plastic network will be created by mixing and curing varying ratios of monomers derived from silicon. Properties that will be tested include biodegradability, thermal, and mechanical strength.