Atomic partial charges obtained from computed wavefunctions are widely used for interpreting quantum chemistry simulations and chemical reactivities of molecules, solids, surfaces, and nanoparticles. In many cases, partial charge alone gives an incomplete picture of reactivity: PhS(-) is a better nucleophile compared to PhO(-) in SN2 reactions with MeI, though PhO(-) has a more negative charge on the nucleophilic atom, the carbons of benzene and cyclobutadiene, or those of diamond, graphene, and C60, possess nearly identical partial charges and very different reactivities, deprotonated amides perform nucleophilic attack via the less negative nitrogen, rather than the more negative oxygen, in anionic cyclization of o-alkynyl benzamides, halide anions F(-), Cl(-), Br(-) and I(-) have identical charges but different nucleophilicities, carbons in aromatic benzene and anti-aromatic cyclobutadiene have nearly identical partial charges, but different reactivities. Our atomic overlap distance complements computed partial charges by measuring the size of orbital lobes that best overlap with the wavefunction around an atom. Compact, chemically stable atoms tend to have overlap distances smaller than chemically soft, unstable atoms. Combining atomic charges and overlap distances captures trends in aromaticity, nucleophilicity, allotrope stability, and substituent effects. Applications to recent experiments in organic chemistry (counterintuitive Lewis base stabilization of alkenyl anions in anionic cyclization), nanomaterials chemistry (facile doping of the central atom in Au7 hexagons) and selective binding of ligands in proteins illustrate this combination’s predictive power.

Amaryllidaceae isoquinoline alkaloids, as well as their analogs, have long been of interest in research for drug discovery due to their biologically active nature. Many of these compounds have been found to be anti-tumor agents.1 Moreover, there have also been studies that show the effectiveness of these molecules against diseases such as Yellow Fever and other RNA-containing flaviviruses.2 Though these compounds are pharmaceutical drug prospects, their low natural abundance lowers that potential.3 For this reason, many synthetic chemists have pursued novel routes to synthesize a wide variety of these compounds.
Techniques toward the synthesis of Pancratistatin-type natural products are presented herein. Manipulations were tested and optimized on a model system to save both time and funds while developing a synthetic pathway to be utilized in the formation of more complex compounds. Setbacks such as controlling the stereochemistry of a tetrasubstituted alkene reduction have been encountered. However, adjustments are being made to avoid such difficulties. Ideally, the proposed scheme will ultimately allow for the synthesis of multiple biologically active Phenanthridone analogs.

Hippadine and pratosine are lycorine-type pharmacologically active Amaryllidaceae alkaloids. Various total syntheses of these natural products have been developed. However, most of these synthetic routes require prohibitively expensive materials and/or achieve yields that are subpar, making these schemes unlikely to be used in an industrial setting. Current research involves developing better synthetic methods for these two alkaloids starting with a 6,7-disubstituted isoquinoline. These syntheses are appealing since they utilize readily available starting materials and avoid expensive catalysts. The key step in the synthetic scheme centers around an intramolecular de Mayo photocyclization which involves a reaction between an alkene moiety in the isocarbostyril system and a 1,3-diketone (a functionalized tether on nitrogen), which forms a third ring in the structure of the molecule. When the photochemical reaction was attempted, an unexpected cyclic photoproduct was obtained; fortunately, this product is a cyclic hemiketal of the expected 1,5-dicarbonyl compound. A base-catalyzed aldol addition affords the final ring in the system; dehydration of this product affords a β-enone that can be transformed to a diene. Oxidation of the diene with DDQ affords the target natural products after simple chromatographic purification. This new synthetic pathway circumvents the need for catalysts that are either expensive or contain metals such as palladium or iridium; moreover, our method allows for the synthesis of various natural and unnatural alkaloids in high yields by modification of the N-tether.

South Africa is unique in that the majority of its wildlife is managed in privately owned game reserves. One major challenge for reserves is maintaining healthy stable populations, particularly large species, such as the big five (white rhinoceros (Ceratotherium simum), African elephant (Loxodonta africana), Cape buffalo (Syncerus caffer), African leopard (Panthera pardus), and lion (Panthera leo)). Nevertheless, there has been very little research on management of these charismatic species in such size restricted reserves. To address this need, we are studying the impacts of megaherbivores on the structure and spatial distribution of vegetation in Amakhala Game Reserve. The reserve was created in 1999 from 7,500 ha of agricultural land. Since the formation of the reserve, succession of vegetation has been encouraged to create a more natural environment. However, the introduction of large herbivores, such as elephants and rhinos, may have altered or slowed down this succession. To explore this hypothesis, we conducted a GIS analysis using Landsat imagery and megaherbivore GPS tacking data. Vegetation type was classified to quantify historic changes, and we performed kernel densities and an emerging hotspot analysis with the tracking data (2011-2018) to determine megaherbivore distribution. We determined that the megaherbivores hindered the natural succession of vegetation by maintaining grasslands and preventing woodland encroachment. These findings will facilitate game reserve management by identifying Amakhala’s limitations for increasing browsing herbivores as well as the potential for the addition of grazing herbivores.

Large numbers of migratory tree bats are killed at wind turbines globally. Recent studies have predicted potential population-level impacts as a result, highlighting the need for strategies alleviating bat-wind turbine collisions. Research has shown bats active in close proximity to turbines, approaching and interacting with tower surfaces as if they provided resources, such as water sources and foraging opportunities. Evidence indicates that the smooth surface of the towers can be misperceived by bats as water, and it can also create an acoustic mirror that can enhance foraging success. We hypothesized that a textured coating would disrupt the smooth tower surfaces. Thus, the focus of our study was to determine if texture application would result in decreased bat activity in proximity to tower surfaces, which in turn would reduce collision risk. From May to September 2017, we used thermal cameras, night vision technology, and ultrasonic acoustic bat detectors to assess bat activity at two pairs of wind turbines in north central Texas. Each pair comprised a texture-treated turbine and a control, and bat proximity and behavior at towers were compared. In this first year of testing, we conducted 76 survey nights, observed 1030 confirmed bats on video, and recorded 1215 acoustic calls from 7 bat species. To fully assess the effectiveness of the texture coating, we will be repeating surveys from June to September 2018.

Although multiple localized chemostratigraphic and strength studies have been completed on the organic-rich Barnett Shale in the Fort Worth basin (Montgomery et al., 2005; Pollastro et al., 2007; Jarvie et al., 2007; Rowe et al., 2008; Williams et al., 2016; Taylor, 2017; Alsleben, unpublished), basin-wide correlations have not been completed. Basin-wide correlation of chemostratigraphy and mechanical stratigraphy could enhance the understanding of regional variations in chemical composition and rock competence. Therefore, this study is going to test multiple hypotheses to identify regional trends and correlations within the Barnett Shale, based on variations in the formations chemical makeup and rock strength. The purpose is to start establishing a more comprehensive, basin-wide characterization of the mechanical stratigraphy and chemostratigraphic framework of the Barnett Shale in the Fort Worth Basin. Results will start to establish possible regional variations such as rock strength and help determine what controls those variations. Ultimately, the data compilation may provide a better understanding of the Barnett Shale and start to address the complex interactions between marine sediment flux, terrestrial sediment flux, and geochemistry throughout the basin at the time of deposition.

Silica oxides (SiO2) come in a variety of forms including quartz, opal, silica gel and phytoliths. This study will focus on the binding and debinding energetics of sodium benzoate, sodium butyrate and sodium acetate on these various silica oxides. The direct measurement and analysis of binding and debinding energies should provide valuable data and insights into the dynamics of organic molecules at the oxide-water interface. The study will focus on the systematic collection and analysis of experimental data that can be used to support the development, validation and refinement of computational models of interactions involving natural organic matter at the metal oxide-water interface, while facilitating the further development of experiment-driven understanding of binding-debinding dynamics of organic molecules onto mineral surfaces.

METASOMATIC FEATURES IN EUCRITES. R. L. Funderburg1, R. G. Mayne, N. G. Lunning2, and S. Sin-gletary3, 1Monnig Meteorite Collection, 2950 West Bowie Street, SWR 244, Texas Christian University, Fort Worth, TX 76109. (r.funderburg@tcu.edu), 2Department of Mineral Sciences, Smithsonian Institution, National Museum of Natural History, 10th and Constitution NW, Washington, DC 20560-0119. 3Robeson Community College, 5160 Fayetteville Road, Lumberton, NC 28360.

Introduction: The breakdown of pyroxene to silica and troilite was first identified as an alteration process in eucrites by Duke and Silver [1]; however, metasomatism was not iden-tified as a potential cause of these features until the 1990s [2] and has been increasingly identified in the last 10 years [3, 4, 5, 6, 7]. Many eucrite studies were conducted prior to this time and, while metasomatic features may have been identified, they were not attributed to this process.

Barrat et al. [4] proposed a three-stage alteration process to explain the products of metasomatic alteration found in eu-crites:
(1) Fe-enrichments along cracks in pyroxenes
(2) Fe-rich olivine deposits in cracks and troilite
(3) Al-depletion coincident with Fe-enrichment of pyroxene

While metasomatism within eucrites is now commonly identified within the literature, the mechanism for this altera-tion is not well understood. Possible mechanisms proposed in-volve hydrous fluid alteration [4] or sulfurization from a S-rich vapor [6, 7]. The addition of sulfur is required to produce troilite from the breakdown of pyroxene, which has been ob-served in several eucrites [3, 4, 5, 6, 7]. Zhang et al. [5] sug-gested that the sulfur may have been present in the form of a dry S-O-P vapor, formed by the volatilization of pre-existing S- and P-rich material as a result of impacts. Additional petro-logical studies are needed to test if metasomatism was consist-ently driven by S-O-P vapors or if some metasomatism lacks the P-component expected for impact derived vapor.

Metasomatism has been directly investigated for only a handful of eucrites. This study will investigate metasomatism in both Stannern and Main-Group-Nuevo-Laredo (MGNL) eucrites to investigate the com-position of the altering fluid/vapor and overarching processes that drive metasoma-tism on the eucrite parent body. Our preliminary work is fo-cused on the Stannern-trend eucrites Bouvante and LEW 88010, the main group eucrite Béréba, and the polymict eu-crite NWA 4834.

Methods: The samples from this study are on loan from the following: Béréba (USNM 5745-2, USNM 6003-2; Na-tional Meteorite Collection, Smithsonian Institution), Lewis Hills 88010 (LEW 88010) (LEW 88010,4; Meteorite Working Group), Bouvante and Northwest Africa 4834 (NWA 4834) (M1224.3, M1224.5, and M2049.2; Monnig Meteorite Collection). Petrographic analysis was conducted via optical micros-copy with an Olympus BX51 polarizing light microscope at the Oscar Monnig Meteorite Collection at Texas Christian University. Backscatter electron (BSE) maps and major ele-ment data for pyroxenes in Bouvante, LEW 88010, and NWA 4834 were measured by a JEOL JXA-8530F HyperProbe elec-tron microprobe analyzer (EMPA) at Fayetteville State Uni-versity’s Southeastern North Carolina Regional Microanalyti-cal and Imaging Consortium. Backscatter maps were gener-ated for each thin section and energy dispersive x-ray spec-trometry (EDS) point analyses were performed.

Results and Discussion: Of the four samples selected for this study so far, one is unbrecciated (LEW 88010), two are monomict (Béréba and Bouvante), and one is polymict (NWA 4834). These samples were selected as they were observed to contain possible metasomatic features during our petrographic survey, but have not been included in the current literature re-garding metasomatism. They include members of both the Stannern- and MGNL- trends (S: Bouvante and LEW 88010; MGNL: Béréba). All samples are either falls or were observed to show little to no terrestrial alteration. Mineralogically, they are typical eucrites, being dominated by pyroxene and plagio-clase, with lesser phases including troilite, chromite, ilmenite, Fe-rich olivine, and silica.
Preliminary results suggest that Fe-enrichment of pyrox-ene rims, along with an associated Al-depletion, is occurring due to metasomatism in the three samples examined using EMPA. Fe-rich olivine was observed in NWA 4834. Petrographic analysis identified the breakdown of pyroxene into troilite and silica in all four samples.

Future Work: Quantitative pyroxene and plagioclase data for all four samples will be collected prior to the conference. This will allow for further assessment of the Al-depletion along with Fe-enrichment in pyroxenes. We will also investigate the presence of phosphates in these samples to investigate the P-component that would be present in an impact derived vapor. We will assess if there are any differences in metasomatism between MGNL and Stannern-trend eucrites. A survey of previously identified residual eucrites for metasomatic features will also be conducted, so that all three geochemical groupings are represented, if possible.

The Raton Basin of Colorado and New Mexico is a Laramide foreland basin that has been important to coal geology since its first identification as a coal resource in 1821, and as a major Coal Bed Methane resource in the modern era. Raton Basin contains Cretaceous to Paleogene strata representative of the major transgression and subsequent regression of the Western Interior Seaway. The interaction between the distal and proximal lithosomes of strata within the Raton Basin is not fully understood. The coaly, fine-grained rocks of the lower and upper coal zones of the Upper Cretaceous to Paleogene Raton Formation are indicative of deposition in wet, distal lowlands, whereas the coarser grains of the barren series of the Raton Formation indicate that this unit was deposited in a highland setting proximal to the source. While the basin has been explored and produced for petroleum and coal in the past (specifically the Cretaceous Vermejo Formation and Raton Formation), vertical and lateral interaction, geometries, and potential communication between the coal deposits and surrounding fluvial deposits is not well-understood. This project has served as an investigation into the depositional model of the coal deposits and their surrounding fluvial deposits, specifically by: analyzing outcrops using architecture analysis, performing core descriptions and interpretations, conducting coal palynology, organic petrology, and chemical analysis. It has been proposed that the Upper Cretaceous to Paleogene strata of the Raton Basin were deposited within a Distributive Fluvial System (DFS), and that the coal-rich zone is the down-dip expression of this system. Initial results (vertical and lateral relation of facies in core and outcrop, organic petrology, and palynology) reveal that the extensive and laterally continuous coals formed in a woody low-lying fluvio-lacustrine depositional environment, and humid subtropical climate.

The Raton Basin of Colorado and New Mexico is a Laramide foreland basin that has been important to coal geology since its first identification as a coal resource in 1821, and as a major Coal Bed Methane resource in the modern era. Raton Basin contains Cretaceous to Paleogene strata representative of the major transgression and subsequent regression of the Western Interior Seaway. The interaction between the distal and proximal lithosomes of strata within the Raton Basin is not fully understood. The coaly, fine-grained rocks of the lower and upper coal zones of the Upper Cretaceous to Paleogene Raton Formation are indicative of deposition in wet, distal lowlands, whereas the coarser grains of the barren series of the Raton Formation indicate that this unit was deposited in a highland setting proximal to the source. While the basin has been explored and produced for petroleum and coal in the past (specifically the Cretaceous Vermejo Formation and Raton Formation), vertical and lateral interaction, geometries, and potential communication between the coal deposits and surrounding fluvial deposits is not well-understood. It has been proposed that the Upper Cretaceous to Paleogene strata of the Raton Basin were deposited within a Distributive Fluvial System (DFS), and that the coal-rich zone is the down-dip expression of this system. This hypothesis was tested by integrating results from well log correlations, measured sections, architecture analysis of outcrops from drone photogrammetry, core descriptions, and coal palynology and microscopy. Initial results reveal the presence of three distinct, repeating lithosomes (valley-fill sandstones, mixed terminal splays, and very extensive and laterally continuous coals) that are identifiable and correlatable in well logs, are cyclically represented, and suggest basin-scale swings in depositional environment consistent with shifting components within a basin-wide DFS system, consistent with the DFS hypothesis.

The ~1.2 billion-year-old-Barby Formation is located in SW Namibia and has been argued to represent a continental volcanic arc. Previous studies on these rocks primarily relied on mobile-element data, which can be altered by secondary processes and therefore is unreliable for constraining petrologic processes. In an effort to establish the Barby Formation's petrotectonic history, 20 samples were analyzed using XRF and ICP-MS to determine whole-rock major and trace element concentrations. These data were used to answer two questions: (1) Do the samples represent one unique magma series that came from a single source? (2) If the Barby Formation is indeed a volcanic arc, did it form from normal, flat-slab, or oblique subduction? These questions were answered using a combination of geostatisical analyses (distribution, cluster, and outlier analyses), trace-element tectonic discrimination diagrams, and geospatial analyses (see other poster by Lehman et al.). This study supports previous interpretations that the Barby Formation formed in a continental arc setting, with rock samples displaying steeply dipping, light-rare-earth-element enriched patterns, negative Nb/Ta anomalies, and calc-alkaline andesitic to shoshonitic compositions. Major and trace element data indicate at least two magma series from two distinct mantle sources. These two groups are controlled by enrichment differences and variations in the high-field-strength element ratios. The presence of shoshonitic rocks is consistent with flat-slab or oblique subduction.

The ~1.2 billion-year-old-Barby Formation located in SW Namibia has been argued to represent a continental volcanic arc. Recent research by our group (see other poster by Lehman et al.) has supported these arguments with data exhibiting steeply dipping, light-rare-earth-element enriched patterns, negative Nb/Ta anomalies, and calc-alkaline andesitic to shoshonitic compositions. The shoshonitic rocks are particularly interesting as these compositions often form in unusual arc settings (i.e., flat-slab subduction, oblique subduction, ridge subduction). Pearce et al. (2005) showed that the relative plate depth, and in turn, subduction angle and orientation can be interpreted by mapping diagnostic trace element ratios. The spatial distribution of the geochemical ratios could potentially also differentiate between shoshonitic volcanic rocks formed as a result of unusual plate geometries as opposed to a slab tear. If the map displays a tight cluster of shoshonitic composition rocks, the samples more likely formed above a slab tear, while a dispersed arrangement would be more suggestive of either a flat-slab or oblique subduction origin. ArcGis Pro was used to map and analyze XRF and ICP-MS data from 20 samples of the Barby Formation. The samples are from lava flows or sills and range from calc-alkaline to shoshonitic in composition. Both spatial tools and statistical analysis tools were used in an effort to explore potential geospatial relationships of key trace element ratios and previously established geochemical clusters. These results were then employed to attempt to recreate the subduction conditions that formed this volcanic arc.

The depositional model of the Festningen Member of the Barremian Helvetiafjellet Formation is that fluvial to inner deltaic-plain conditions were established as deltas that built southeastward into the Barents Sea basin from an unknown source northwest of present-day Svalbard. Currently, models of Artic drainage provinces are nascent to non-existent. Here, evidence for a large artic drainage basin into the Cretaceous Barents Sea is suggested by using established scaling relationships and the fulcrum method in the Festningen Sandstone.
Data from several locations in Svalbard: Konusdalen, Revneset, Criocerasaksla, and Hanaskogdalen. The Festningen Member sandstone sections were all initially photographed by drone in order to determine channel body dimensions and architecture in the sandstone as well as to record data for 3D photogrammetric construction of virtual outcrop models. Paleohydraulic estimates based on the fulcrum method use bankfull channel dimensions, specifically the height and width, and the D16, D50, D84, and D90 grainsizes to develop basin-process models and infer past catchment constraints. Festningen Member sandstone sections were logged and found to represent braided fluvial systems with mid-channel bars up to 3 m thick and channel-fills up to 4 m thick. Representative bedload samples were taken from approximately 10 cm above the base of channel scours for analysis and model input. The coarse grainsize and large clasts, frequently 3-4 cm and up to 15 cm in diameter, in the Festningen Member sandstone samples show that this was a large river capable of moving a coarse bedload. Scaling relationships equivalent to 4 m channels and coarse grained D-values is on the order of the modern braided Missouri River, on the South Dakota/Nebraska border.
The Bjarmeland Platform and Fingerdjupet Subbasin in the western Barents Sea have a potential petroleum play in the Lower Cretaceous strata, which are, in part, considered to have been fed by the same Festningen fluvial system that is represented in cliff sections on Svalbard. Seismic profiles show clinoforms that may suggest deltaic facies, but remains unknown due to lack of well data.
Seismic data shows that the Cretaceous Festningen fluvial system was able to deliver enough sediments onto the Bjarmeland Platform area to build clinoforms. The size of the source area sufficient to produce a trunk river on this scale remains unconstrained, but an area of at least 100,000 km2 is necessary to produce the river found in the rock record, if the Fulcrum method is applied. Existing Arctic tectonic reconstructions do not consistently show a land area of sufficient size to accommodate this magnitude of drainage area, but results from this study may provide further input to the discussion on timing and land-mass configuration in the present day arctic during the Early Cretaceous.

Unconventional shale plays have been a significant source of natural gas, gas condensates, and crude oil through much of North America. The Eagle Ford Shale in south Texas has been a prolific unconventional play since the mid-2000’s. It was deposited in the Gulf Coast basin along the southern rim of Texas. This play covers a vast area that stretches approximately 7 million acres (2.8 hectares) and extends from the College Station to the USA-Mexico Border near Del Rio. The majority of the Eagle Ford has been thoroughly studied and analyzed, however, there is much to learn about the basal member, the Maness Shale.
The Maness Shale was deposited 97 million years ago; it is the basal member of the Eagle Ford Group and lies directly above the Buda Limestone. The formation does not occur continuously throughout the entire Eagle Ford deposition and varies in thickness. Whereas the lateral extent still remains unknown, it has previously been mapped across the San Marcos Arch. The geophysical and geochemical properties of this member create drilling stability issues if encountered while drilling horizontal Eagle Ford wells. To further understand its geomechanical properties, two hand-held devices will be used on cores taken near the San Marcos Arch that contain the Maness Shale to determine rock strength variations of the Eagle Ford section. The Equotip Bambino is a micro-rebound hammer that provides hardness data values that can be used to estimate unconfined compressive strength. The dimpler is a micro-indentation device that infers rock strength by generating a “dimple” created by the tool and then measuring the depth and diameter of the dimple. These measurements are then correlated on graphs against the unconfined compressive strength for the regional Eagle Ford. The Maness has a neutron density range of 20-30%, indicating a high clay content. The x-ray diffraction (XRD) will be used to determine the content of the clay minerals. Geophysical well logs have been collected and correlated across the San Marcos Arch region; the initial maps identified the thickest Maness interval within the Karnes trough.

The sequence stratigraphy of Middle to Upper Pennsylvanian strata in the Appalachian Basin is complex, partly owing to the icehouse co-response to climate and sea level change during the late Paleozoic. The Breathitt Group resembles a traditional marine-to-terrestrial sequence stratigraphic model. The overlying Conemaugh Group also exhibits sequences, but they are more fluvial-dominated. Sequence stratigraphy largely presumes sea-level drive for sequences and accommodation. We present a model that is driven by both sea level and climate. We hypothesize that once the land surface is built up high enough above the water table, it is not required that sea level drop to induce valley incision, and in fact there is no evidence for a shelf slope break that would promote incision. Instead, we offer that climate change may be the main driver of valley incision.
This model is tested using strata in the Breathitt and Conemaugh Groups in the Northern and Central Appalachian Basin. Measured sections along a basin cross section in outcrop and 3D models built from UAV photographs help reveal this past environment to address the potential of climate change as a sequence driver.
The Breathitt to Conemaugh Group shift records a composite of sequences that are a progradational basin-fill and define a switch from a mixed marine and fluvial to fluvial fill. The Conemaugh sequences record upward shifts from a low-accommodation, valley-incised tributive to a high-accommodation, un-incised distributive systems tract. As a marine transgression tops the low-accommodation valleys below, it lays a basal peat which floods the tributive system. Next, the rivers in the distributive fluvial system prograde and push out the shore, as well as build a slope above sea level. This aggradation creates an elevated coastal prism. Continued progradation creates the elevation needed for valley incision, but this progradation need not cause incision, even if sea level falls. A climate change will eventually spur water table reduction owing to a locally drier climate, or an upstream water-sediment ratio change. Valley incision begins at that time, and possibly with no change in sea level. In this model, regression with or without sea level drop sets up the conditions needed for valley incision, but does not cause incision itself. Incision waits for adequate climate change to generate buffer valleys. The valleys record regression but are climate driven and do not have to define sea-level change.

Due to the logistical challenges and the dynamic nature of fluvial systems, studying modern point bar deposits over formative time periods is difficult. Seasonal and annual changes in precipitation can greatly influence the rate at which deposition is recorded. The lack of accurate sediment-package dating makes it difficult to compare sedimentation rates to actual chronostratigraphic events such as floods. This study combines photogrammetry, mapped surface migration, a survey of sediment elevation change, a trench, and water discharge rates to develop a more complete understanding of how a point bar forms on an annual scale. The Powder River, Montana, USA, which has little influence from engineering, offers a unique opportunity to study a seasonally exposed point bar and how its internal architecture and surface features form through time.
The study area is along the Powder River between Moorhead, Montana, USA, and Broadus, Montana, USA. The Powder River is a northward flowing, meandering river that is sourced from the Bighorn Mountains in northeast Wyoming, USA and is a tributary to the Yellowstone River. Point bar PR141A, the focus of this study, is the result of the neck cut-off of point bar PR141 during a 50 year flood in 1978. The sediment elevation survey is conducted annually, with a few exceptions, at centimeter scale to determine sediment elevation change and the building and erosion of the point bar. The survey is applied to the architectural-element analysis of the sediment packages within the point bar to compare time with sediment deposition.
This study reconstructs the growth of point bar PR141A, its discrete accretionary architecture at the scale of years, and determines the inter-relationship between annual flooding events and bar accretion. The sediment survey timeline shows that on average the river builds one accretionary body per yearly flood cycle. On occasion, the river builds multiple bodies during the year or can take several years to build one accretion set. The change in the accretion set building period is attributed to changes in river flow. The continual change of deposit direction, grain size distribution, erosion, and reshaping of the bar surface between accretion events leads to fragmentation of the point bar body, vastly different from the textbook model of a point bar. The detailed study of how a modern point bar forms lends insight into the fragmentation of fluvial hydrocarbon reservoir bodies.

The Eagle Ford Shale (EFS) was deposited on the South Texas Shelf in the Late Cretaceous, during a time of widespread marine transgression. With industry interest in the EFS, an understanding of the geology and depositional environment of these rocks is imperative to maximize well results. For the study, a section of the EFS was measured and described in detail in Heath Canyon, Brewster County, Texas. Lithostratigraphy, biostratigraphy, and mechanical stratigraphy were determined via outcrop and elemental composition was determined from sample collection and lab analysis. Data suggests the EFS was deposited in a potentially anoxic environment below storm-wave base on the South Texas Shelf.

Quantifying source-to-sink sediment flux for stratigraphic systems is critical for accurate basin models, but all available methods are hampered by low precision and most require data not readily attained by common subsurface studies. The Fulcrum approach uses the variables of channel bankfull thickness and grain size to calculate sediment bankfull discharge and converts this to an annual sediment volume. The Fulcrum approach uses commonly collected data but similarly yields only approximate flux estimates. In order to calculate a more precise source-to-sink estimate for long basin durations, the amount of time the fluvial systems runs at bankfull flow and the annual proportion of sediment discharged during this bankfull flow must also be determined. By categorizing fluvial systems by attributes such as drainage area and paleoclimate at the time of discharge, a more specified and accurate bankfull flow duration and total bankfull sediment discharge is estimated. We constructed a database that stores and categorizes these data and a user interface (RAFTER: River Analogue and Fulcrum Transport Estimates Repository) to query and display this data. Daily stream gauge data spanning decades is used in conjunction with measured bankfull values from literature to populate the datasets for the database and derive stream specific data attributes. This bankfull flux searchable database evaluates stream gauge data for modern fluvial systems according to classes such as climate setting and is also a useful tool for identifying analog stream data scaled to drainage basin and channel size. It evaluates designated parameters of days within a year that the river runs at bankfull flow, as well as the yearly proportion of sediment discharged over bankfull duration. The database can thus yield a more accurate value for duration at bankfull flow and sediment discharge at bankfull from modern rivers that can be used as an analog for stratigraphic rivers with interpreted climate and size parameters. Results show a key breakdown in bankfull duration, with arid and tropical rivers on the order of a fraction of a day per year, boreal climates tending to be an order of magnitude longer, and temperate climates still longer. Categorizing stratigraphic rivers by known climate and other parameters can lower the total error in sediment flux from paleohydrology by a geometric factor.

Understanding of the wound healing process can be used to make more tailor-made medicine and to determine the nature of this healing process. In this research we use MATLAB software along with the ADI method to solve a partial differential equation that models wound healing by treating keratin as a diffusion process. A significant hurdle to overcome is finding the appropriate initial conditions, that is to accurately extract boundary data from photos taken with different equipment, lighting, or resolution.

An algebraic curve is a one-dimensional set defined by polynomial equations, such as a parabola in the plane (given by y-x^2=0) or the z-axis in the space (given by x=y=0). Let Y be an algebraic curve. Then a multiplicity structure on Y is another curve Z, which as a set has the same points as Y but with a higher and fixed multiplicity at each point. For example, the y-axis in the plane is given by the equation x=0 and if we intersect it with horizontal lines, say with y-b=0, we get the points (0,b) on the y-axis. Now if we take the line given by x^2=0 and intersect it with the horizontal lines as above we get the points (0,b) with multiplicity 2. Hence we call the later curve a double structure on the previous one. Similarly the equation x^3=0 gives a triple structure on the y-axis in the plane and so on. Structures like these might sound naive but they are crucial to understand the behaviors of families of curves. For example, the family of parabolas ty-x^2=0 deforms into the double line x^2=0 as t approaches 0. Although the notion of multiplicity is pretty geometric, we can use tools from abstract algebra to make it rigorous. This makes the subject challenging and yet very interesting at the same time. Classifying the multiplicity structures on a curve is still a wide open field in algebraic geometry. It is now well understood how the double and triple structures on a line look. A natural question then arises how do the double and triple structures look on conics? It turns out that the answers are much more complicated than for lines. In this poster I am going to show some of my research in that direction.

An algebraic integer is a complex number that is a root of a polynomial with integer coefficients and a leading coefficient of 1. This includes numbers like the square root of 2 and the cube root of 10, for example. A field is a set in which we can add, subtract, multiply, and divide (among other details). Consider the set of all algebraic integers in any given field containing the rational numbers. The index of an algebraic integer in this set is a natural number that measures how close the algebraic integer is to generating the set. For instance, the imaginary number i (the square root of -1) is an algebraic integer which generates the set of all complex numbers of the form a + bi where a and b are integers, and so has index 1. The closer the index is to 1, the closer the algebraic integer is to generating the set. We investigate these indices in cubic fields, determining not only which numbers occur as indices in given families, but also that the minimal index is unbounded as one traverses the set of all cubic fields in those families.

Nearby, the Large Magellanic Cloud galaxy (LMC), has ejected massive amounts of gaseous material, some of which is headed toward the Milky Way. The material consists of ionized hydrogen gas which is a consequence of significantly energetic events that have occurred in the LMC. Such events are not only the cause of the ionized material, but also the immense amount of material being thrown out. This ejected wind holds a substantial amount of information regarding both galaxies in general and the LMC’s physical processes. Studying this ionized outflow will reveal new details concerning the internal processes that produce such massive ejections, the potential for galactic outflows to replenish gas reservoirs for future star formation, and the environments surrounding galaxies. The latter will influence our view of a galaxy’s environment and how it may interact with nearby neighbors such as our Milky Way galaxy.

Fluorescence anisotropy is a common measurement that helps provides important information on molecular mobility, solvent (environment) viscosity, or/and molecular size. Fluorescence anisotropy involves measurement of two orthogonally polarized light emission intensities. One of the common issues of fluorescence anisotropy measurements is that most optical detection systems respond differently to the parallel and perpendicular polarization of light. The challenging task is to estimate the calibration curve, often called as the instrumental G-factor (grating factor), a parameter indicates the contributions and/or distortion of the optical detection system to the parallel and/or perpendicular light polarization, so that one can correct their polarized emission intensity and obtain a proper fluorescence anisotropy result. Here we present novel techniques that we have been developed in our laboratory that help achieve the G-Factor curves for different instruments.

Despite living inside the Milky Way, we do not know well basic quantities such as its detailed chemical makeup at the level needed to fundamentally tie the Milky Way to studies of evolution in other galaxies. One key observable is the radial chemical abundance gradient. Open star clusters provide an age datable sample by which to measure this gradient. This measurement has previously been made using a diverse and regularly conflicting compilation of clusters from various literature studies. We present the first measurement using a large (462 stars in 28 open clusters), uniform sample of open clusters abundances. Our measurements show a general agreement with recent studies of the overall metallicity gradient, with a measured ∆ [Fe/H]/∆ RGC of -0.050 ± 0.004 dex/kpc. We also explore trends with distance from the galactic plane and cluster age, and finally investigate the existence of a "knee" in the overall abundance gradient, between 12-14 kpc, within the range suggested by previous work. We show strong evidence for this phenomenon.

Since a number of medical conditions require simultaneous treatment and diagnostics, the field of molecular therapeutics has recently turned to multifunctional approaches allowing for both therapy and biomedical imaging. A number of such molecular and nanoformulations are combined with fluorophores that allow for imaging of the delivery pathways of the drug in the visible. This is optimal for in-vitro or ex-vivo work, however, cannot be utilized well in-vivo. Thus, there is a need in nanoformulations optimized for both in-vitro and in-vivo studies. Graphene quantum dots, possessing intrinsic stable fluorescence in the visible and near-IR stand out as candidates for such complex application.

In this work, we for the first time produce biocompatible graphene quantum dots (GQDs) that exhibit multi-color emission both in visible and NIR possess a capability for biological pH sensing. These GQDs show the crystalline graphitic structure in TEM and average sizes of c.a. 5 nm beneficial for cellular internalization. They show no cytotoxicity even at high doses of 1 mg/mL that are used for imaging. As opposed to related structures such as graphene oxide and other graphene derivatives GQDs show high quantum yield in green (~500 nm) of ~50%. Near-IR emission at ~860 nm is located in the water window with reduced absorption and lower autofluorescence backgrounds providing a promising potential route for in-vivo studies. Emission of GQDs also depends on pH of the surrounding medium. The change in pH of as-prepared GQDs from 2.70 to 8.0 yields an increase of fluorescence intensity up to ~60%. Additionally, pH-dependent shifts of the spectral features allow differentiating between acidic cancerous and neutral healthy exocellular environments allowing to use GQDs for cancer detection. Therefore, our results indicate that GQDs have a significant potential in bio-applications because of their capacity for multi-color green/near-IR imaging for in-vitro/in-vivo studies, pH sensitivity, water solubility, low cytotoxicity and high capacity for cellular internalization.