Master of Science

thesisRecent discoveries demonstrate that Campanian dinosaur assemblages across the western North American subcontinent (Laramidia) exhibit basin-scale endemism, with each sedimentary basin possessing its own unique assemblage, and an apparent higher-level biogeographic boundary between northern and southern Laramidia. Subsequently, during the Maastrichtian, most taxa are present in multiple basins, with some forms supporting the presence of distinct northern/southern provinces, whereas others are more cosmopolitan. Despite these dinosaur biogeographic data, little attention has been paid to other vertebrate groups. To test these biogeographic hypotheses, I examined the alpha taxonomy, evolution, and paleobiogeography of the paracryptodiran turtle clade Baenidae using a newly-generated species-level phylogeny. Baenids were one of the most diverse and abundant turtle clades during the Late Cretaceous, are restricted to North America, and have a well-sampled fossil record, making them an ideal study system for examining Laramidian biogeography. I first assessed the taxonomic affinities of newly discovered baenid turtles from the Upper Cretaceous (Campanian) Kaiparowits Formation of southern Utah. I found that at least five distinct baenid species inhabited the Kaiparowits Basin during the Campanian. These taxa include Denazinemys nodosa, previously known from Texas and New Mexico, Boremys grandis, previously known from New Mexico only, and three new iv taxa that appear to have been endemic to southern Utah. These newly described taxa include two new species of Neurankylus and a morphologically unique pig-nosed taxon. Using new morphologic data from the Kaiparowits specimens, I conducted a comprehensive phylogenetic analysis on the clade, utilizing 106 characters and 32 ingroup taxa. Based on occurrences alone, Campanian baenid assemblages display distinct northern and southern provinces with no taxonomic overlap. To investigate the evolutionary patterns of this biogeographic signal, I applied a dispersal-extinction-cladogenesis model to the strict consensus tree and three randomly selected most parsimonious trees from my phylogenetic analysis. This study reveals that the ancestral ranges for basal baenid branches were cosmopolitan across either Laramidia or all of North America. More derived baenids (i.e., subclade Baenodda) possessed ancestral ranges in the area of Montana, Wyoming, and the Dakotas, and the analysis reconstructs multiple individual lineages then dispersing to southern Laramidia and Alberta

Vapor phase infiltration for transforming polymers into organic-inorganic hybrid materials: Processing science, structural complexity, and emerging applications

Vapor phase infiltration (VPI) exposes polymers to gaseous metalorganic molecules that sorb, diffuse, and become entrapped in the bulk polymer, transforming it into a complex organic-inorganic hybrid material.1 This process is pictured in Figure 1. While VPI’s gaseous dosing sequences may appear similar to other vapor deposition techniques (e.g., atomic layer deposition) the set of atomic scale processes occurring during synthesis constitute a fundamentally different process that results in not just a simple coating on the polymer but rather a complete alteration of the polymer’s bulk chemistry. Please click Additional Files below to see the full abstract

Apparatus, Methods and Systems For Fabricating Thin Nanoporous Membranes

Embodiments of the present disclosure provide apparatuses, methods and systems for scalable fabrication of thin, nanoporous membranes useful in industrial applications. One embodiment of the present disclosure provides a molecular separation device configured to efficiently separate molecular species. In this particular embodiment, porous hollow fibers form a supporting scaffold for synthesis of a molecular organic framework (MOF) membrane. The MOF membrane may be synthesized on the inner or outer porous hollow fiber surface as well as within the porous fiber wall. Embodiments of the present disclosure provide a variety of methods for producing the aforementioned molecular separation devices as well as methods for producing MOF membranes

Hollow fiber sorbents for post-combustion CO₂ capture

As concerns mount about the rise in atmospheric CO₂ concentrations, many different routes to reduce CO₂ emissions have been proposed. Of these, post-combustion CO₂ capture from coal-fired power stations is often the most controversial, as the CO₂ capture system will remove generating capacity from the grid whereas many of the other solutions involve increasing the generating capacity of the grid with low CO₂-emission plants. Despite this, coal-fired power stations represent a major point source for CO₂ emissions, and if a consensus is reached on the need to reduce CO₂ emissions, a low-cost method for capturing and storing the CO₂ released by these power plants needs to be developed. The overarching goal of this research is to design and develop a novel hollow fiber sorbent system for post-combustion CO₂ capture. To achieve this goal, three objectives were developed to guide this research: i) develop a conceptual framework for hollow fiber sorbents that focuses on the energetic requirements of the system, ii) demonstrate that hollow fiber sorbents can be created, and a defect-free lumen layer can be made, iii) perform proof-of-concept CO₂ sorption experiments to confirm the validity of this approach to CO₂ capture. Each of these objectives is addressed in the body of this dissertation. Work on the first objective showed that fiber sorbents can combine the energetic advantages of a physi-/chemi-sorption process utilizing a solid sorbent while mitigating the process deficiencies associated with using solid sorbents in a typical packed bed. All CO₂ capture technologies--including fiber sorbents--were shown to be highly parasitic to a host power plant in the absence of effective heat integration. Fiber sorbents have the unique advantage that heat integration is enabled most effectively by the hollow fiber morphology: the CO₂-sorbing fibers can behave as "adsorbing heat exchangers." A dry-jet, wet-quench based hollow fiber spinning process was utilized to spin fibers that were 75wt% solid sorbent (zeolite 13X) and 25wt% support polymer (cellulose acetate). The spinning process was consistent and repeatable, allowing for production of large quantities of fibers. The fibers were successfully post-treated with an emulsion-based polymer (polyvinylidene chloride) to create a defect-free lumen side coating that was an excellent barrier to both water and gas permeation. A film study was conducted to elucidate the dominant factors in the formation of a defect-free film, and these factors were used for the creation of defect-free lumen layers. The work discussed in this thesis shows that the second objective of this work was definitively achieved. For the third objective, sorption experiments conducted on the fiber sorbents indicated that the fiber sorbents CO₂ uptake is simply a weighted average of the support material CO₂ uptake and the solid sorbent uptake. Furthermore, kinetic experiments indicate that CO₂ access to the sorbents is not occluded noticeably by the polymer matrix. Using the fiber sorbents in a simulated rapid thermal swing adsorption cycle provided evidence for the fiber sorbents ability to capture the sorption enthalpy released by the CO₂-13X interaction. Finally, a slightly more-pure CO₂ product was able to be generated from the fiber sorbents via a thermal swing/inert purge process.PhDCommittee Chair: William J. Koros; Committee Member: Christopher W.. Jones; Committee Member: John D. Muzzy; Committee Member: Ronald R. Chance; Committee Member: Ronald W. Roussea

A New CO₂ Capture Platform: Hollow Fiber Adsorbents for Post-Combustion Recovery

2009 program of the “Open Forum on Energy and the Environment”, presented on September 3, 2009, from 4:30 PM-6:00 PM in room L1255, Ford Environmental Science & Technology Building (ES&T) on the Georgia Tech campus.The Impact of CO₂ on Global Climate ChangeRuntime: 45:02 minute

Macroevolution in the greenhouse : morphological disparity of Mosasauridae and the evolution of Late Cretaceous marine ecosystems

Climate researchers assert that our planet is not only entering an interglacial period, but potentially a time of prolonged warming, or even a greenhouse climate. The fossil record provides the opportunity to better understand the effects of prolonged warming on the evolution of the Earth’s biota because we can examine species and lineages across their entire stratigraphic range. I examined the macroevolutionary dynamics of mosasaurs with a focus on new mosasaurines from the Western Interior Seaway (WIS). Mosasaurs represent the dominant marine tetrapod predators of the latest Cretaceous. Because they both originated and reached peak diversity during the Late Cretaceous, mosasaurs are an excellent study system for understanding macroevolutionary dynamics during a greenhouse interval. My work combined phylogenetic comparative methods, analysis of anatomical diversity (disparity) using discrete morphological features, analysis of intraspecific variation, and insights from new mosasaur genera to better understand the diversification of mosasaurs. The mosasaur Prognathodon stadtmani was originally named in 1999 based on fragmentary material from the Mancos Shale of Colorado. New cranial elements that have been prepared since its original description helped to elucidate its phylogenetic position. My analyses support the placement of this taxon outside of the genus Prognathodon, in spite of many gestalt features that suggest otherwise. I also described a new mosasaur from the lowermost Campanian of Texas and Alabama. This new animal, which in many respects resembles the early-diverging mosasaurine Clidastes propython, exhibits derived character states observed in later mosasaurines, including Prognathodon overtoni. Including this animal in a global disparity analysis of Mosasaurinae demonstrates that the lineage exhibited low morphological diversity throughout the first 8 million years of its evolution, followed by a significant increase in disparity during the early Campanian. Based on the phylogenetic position and chronostratigraphic distribution of this new taxon, that diversification was preceded by an expansion in the feeding ecology of this clade. I also modeled disparity across all mosasaur clades within the WIS. Within the seaway, mosasaurs exhibit two significant diversification events; the first of those occurred during the Santonian with the diversification of Plioplatecarpinae. The second period of diversification occurred during the Campanian, with a significant increase in disparity of mosasaurines. To contextualize the role of intraspecific variation in the macroevolution of mosasaurs, I collected discrete character data from a large number of Clidastes propython and plioplatecarpines from the Coniacian-early Campanian of the WIS and quantified variation within these two lineages. Early members of the Mosasaurinae exhibited significantly higher levels of variation in tooth-bearing elements than their contemporaries from the Plioplatecarpinae. This is notable because while the plioplatecarpines retain relatively low diversity throughout their evolutionary history, mosasaurines diversified into at least five separate lineages during the Campanian, filling a number of predatory niches within the marine ecosystem. Early mosasaurines like Clidastes propython potentially represent a zone of variability in the clade’s evolution, with variation exhibited by that taxon becoming fixed interspecifically within later members of the cladeGeological Science

Separations: The Forgotten Science

Efficient systems to separate substances is of critical importance in our lives, despite the fact that the general public is typically unaware of this important field. Ryan Lively, from the School of Chemical & Biomolecular Engineering joins us to describe the importance of separation processes, and the impact of modern separation systems on important fields including energy production

The Closing Door on 450 ppm CO or 2° C Rise in Global Temperature

Presented on April 4, 2012 from 2:00 – 300 pm in the Georgia Tech Library, Neely Lobby, 1 West.Runtime: 57:02 minutes.Dr. Ryan Lively, a Postdoctoral Scholar in Chemical and Biomolecular Engineering, at Georgia Tech, delivered a presentation on novel low-energy intensity separations for biofuels, focusing the potential of Algenol processes for alternative energy production. Mr. Mark Simpson, doctoral student in Mechanical Engineering at Georgia Tech, presented: “The Solar Vortex: Electrical Power Generation Using Buoyancy-Induced Vortices.” Mr. Simpson explored how artificially induced vortices could be harnessed to capture thermal energy. He presented his prototype technology for this purpose, identified the low environmental impact of this novel technology, and presented preliminary findings of its energy efficiency relative to traditional energy sources. Dr. Marilyn Brown delivered a presentation entitled: “The Closing Door on 450 ppm CO or 2° C Rise in Global Temperature.” Dr. Brown addressed the critical role of energy efficiency in meeting national and international energy consumption and CO emissions reductions. Georgia Tech and Duke University have collaborated to advance research in this area and are the only two universities in the U.S. that utilize the National Energy Modeling System (NEMS) to model and forecast energy consumption. The NEMS is the major system utilized by the U.S. Energy Information Administration for such energy modeling and forecasting