Precipitation Dynamics at the Solution-Solution Interface in Confined Geometries, and the Effects of Organics on Precipitate Evolution

Precipitate produced by the interaction of aqueous reactant solutions in a microchannel is evaluated through instrumental analysis and numerical modeling. Instrumental analysis of analogs of iron sulfide, iron carbonate, and iron phosphate minerals and the effect of modeled ionic strength and mass transport mechanisms are presented. Implications on fluid dynamics due the production of colloids at a solution-solution interface is developed. A phenomenon of electroless reduction in this system transitioning to self-catalyzed electrodeposition is presented in light of the dynamics previously discussed and is used as an example of the convergent effects of coupled physiochemical systems on the microscale. All three of the above results (precipitate analysis, fluid and mass transport dynamics, and coupled physiochemical systems) are leveraged to present results of the interaction of organic species with precipitating iron sulfide material. It is found that the presence of organic species has a strong impact on the morphology of iron sulfide mineral analogs, and that morphology may be diagnostic for the presence of organics during formation even when Raman spectra show no signs of extant organic material. This has profound implications for the use of autonomous rovers in exploring the organic-mineral interactions of ancient aqueous systems such as Mars’s Jezero Crater.Ph.D

The C. elegans ephrin EFN-4 functions non-cell autonomously with heparan sulfate proteoglycans to promote axon outgrowth and branching

The Eph receptors and their cognate ephrin ligands play key roles in many aspects of nervous system development. These interactions typically occur within an individual tissue type, serving either to guide axons to their terminal targets or to define boundaries between the rhombomeres of the hindbrain. We have identified a novel role for the Caenorhabditis elegans ephrin EFN-4 in promoting primary neurite outgrowth in AIY interneurons and D-class motor neurons. Rescue experiments reveal that EFN-4 functions non-cell autonomously in the epidermis to promote primary neurite outgrowth. We also find that EFN-4 plays a role in promoting ectopic axon branching in a C. elegans model of X-linked Kallmann syndrome. In this context, EFN-4 functions non-cell autonomously in the body wall muscle, and in parallel with HS biosynthesis genes and HSPG core proteins, which function cell autonomously in the AIY neurons. This is the first report of an epidermal ephrin providing a developmental cue to the nervous system

Scraping Meaning from Technical Information: Semantic Mining of Chemical Information From Non-Chemistry Disciplines

Presented at the Georgia Tech Career, Research, and Innovation Development Conference (CRIDC), January 27-28, 2020, Georgia Tech Global Learning Center, Atlanta, GA.The Career, Research, and Innovation Development Conference (CRIDC) is designed to equip on-campus and online graduate students with tools and knowledge to thrive in an ever-changing job market.Aaron Pital, in the School of Chemistry and Biochemistry at Georgia Tech, was the winner of a College of Science Travel Award.The pace of publication in the sciences has long since outstripped human ability to read and synthesize information. While interdisciplinary work can mitigate some of this burden, there remain fundamental questions about whether attentional blindness and the opportunity cost of reaching beyond the comfort of one’s expertise hold back innovation in speculative fields such as the origins of life. I present a brief model of associative information in scientific publication and propose tools derived from information theory, natural language processing, and data science to search for physical and chemical contexts embedded in literature from fields as diverse as soil science and drug design. The goals of these efforts are 1) to identify physical and chemical information of interest to select communities which would otherwise be unlikely to rise to the community’s attention and 2) to define rules for correlated information generally to improve literature cataloging, cross-referencing and searching

Characterization of Polyhydroxybutyrate-Based Composites Prepared by Injection Molding

The waste generated by single-use plastics is often non-recyclable and non-biodegradable, inevitably ending up in our landfills, ecosystems, and food chain. Through the introduction of biodegradable polymers as substitutes for common plastics, we can decrease our impact on the planet. In this study, we evaluate the changes in mechanical and thermal properties of polyhydroxybutyrate-based composites with various additives: Microspheres, carbon fibers or polyethylene glycol (2000, 10,000, and 20,000 MW). The mixtures were injection molded using an in-house mold attached to a commercial extruder. The resulting samples were characterized using microscopy and a series of spectroscopic, thermal, and mechanical techniques. We have shown that the addition of carbon fibers and microspheres had minimal impact on thermal stability, whereas polyethylene glycol showed slight improvements at higher molecular weights. All of the composite samples showed a decrease in hardness and compressibility. The findings described in this study will improve our understanding of polyhydroxybutyrate-based composites prepared by injection molding, enabling advancements in integrating biodegradable plastics into everyday products

The Caenorhabditis elegans Ephrin EFN-4 Functions Non-cell Autonomously with Heparan Sulfate Proteoglycans to Promote Axon Outgrowth and Branching

The Eph receptors and their cognate ephrin ligands play key roles in many aspects of nervous system development. These interactions typically occur within an individual tissue type, serving either to guide axons to their terminal targets or to define boundaries between the rhombomeres of the hindbrain. We have identified a novel role for theCaenorhabditis elegans ephrin EFN-4 in promoting primary neurite outgrowth in AIY interneurons and D-class motor neurons. Rescue experiments reveal that EFN-4 functions non-cell autonomously in the epidermis to promote primary neurite outgrowth. We also find that EFN-4 plays a role in promoting ectopic axon branching in a C. elegansmodel of X-linked Kallmann syndrome. In this context, EFN-4 functions non-cell autonomously in the body wall muscle, and in parallel with HS modification genes and HSPG core proteins. This is the first report of an epidermal ephrin providing a developmental cue to the nervous system