The first stars in the Universe, Pop III stars, formed out of the primordial hydrogen and helium sometime during the first billion years of cosmic time. Their formation ended the Cosmic Dark Ages. Despite their critical role in kick starting the formation of all “metals,” (ie. the carbon in our bodies and the oxygen we breathe), we do not know how massive these first stars were, and when and how the era of the first stars ended. While Pop III stars are too faint for a direct detection, their deaths are potentially visible by James Webb Space Telescope (JWST). A subset of Pop III stars end their lives as Pair Instability Supernova (PISN), explosions 100 times more powerful than a typical supernova. However, determining the astrophysics of the first stars will require combining the detection of PISN with theoretical work on the mass distribution of Pop III stars. In this theoretical work, we need to fully explore the range of mass distribution of Pop III stars to determine how dependent the PISN rate is on the masses of Pop III stars. In this work, we present results from a new model which explores the distribution of Population III masses with a set free parameters. We find an order magnitude difference in the PISN rates for various Pop III mass distribution. In addition, we find that PISN rates may provide one of the first independent probes of the maximum mass of Pop III stars.

It has been well established that ZnO is a versatile material with multiple existing and potential applications owing to its numerous and unique properties. ZnO in the nano- and microscale forms has been a focus of attention in recent years due to demonstrated utilities in pharmaceutics, bioengineering and medical diagnostics. Of particular interest is the utilization of ZnO as an antibacterial agent. With growth inhibition observed for both gram-positive and gram-negative bacteria as well as antibiotic strains, the antibacterial action of ZnO is well documented. Yet, there exists much debate over the fundamental mechanisms underlying the antibacterial action of ZnO. Commonly proposed mechanisms include the generation of various reactive oxygen species, release of Zn ions, surface-to-surface interactions, etc. In this work, we investigate the surface and near-surface optoelectronic properties of ZnO microcrystals as they relate to the antibacterial figures of merit. As microscale ZnO particles exhibit comparable antibacterial action to those at the nanoscale, while minimizing effects related to internalization, they are well-suited to serve as a platform to investigate the role of the crystalline free surfaces in this behavior. A bottom-up hydrothermal growth method was employed to synthesize ZnO microcrystals with tunable morphology and a well-controlled relative abundance of polar and non-polar surfaces. The quality of the crystalline lattice and free surfaces as well as the predominant morphology of these samples were confirmed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and surface photovoltage spectroscopy. The antibacterial efficacy of these particles was characterized via minimum inhibitory concentration assays, performed using Staphylococcus Aureus in a Mueller Hinton broth media. We performed a series of optoelectronic experiments including temperature dependent photoluminescence spectroscopy as well as spectroscopic and transient surface photovoltage as a means to observe changes occurring at the ZnO surface during these assays. We detected significant spectral changes due to interactions with bacteria and growth media. In particular, we showed that interactions with s.aureus resulted in considerable modifications of the excitonic luminescence.

CRISPR Cas9 is a programmable single guided RNA (sgRNA) ribonucleic protein (RNP) that has demonstrated their ease and practical use as a gene editing tool for in vitro and ex vivo applications. For in vivo applications of the Cas9 RNP, physiological barriers must be overcome and gene editing to occur transiently, demonstrating the need to develop biocompatible imaging agents to protect and locate Cas9 RNP in vivo. Graphene quantum dots (GQDs) are biocompatible carbon-based nanomaterials that have served as delivery and imaging agents for drug and gene medicine due to their ease in synthesis and repertoire of complexation capabilities arising from the choice of precursor materials. In this work, we have synthesized visible and near infrared emitting GQDs with glucosamine HCl and polyethylenimine (PEI) using a bottom-up approach to use them as non-viral delivery vehicles for the Cas9 RNP. PEI increases the net positive charge of GQDs allowing their electrostatic complexation with the net negatively charged RNP. We further demonstrate their complexation with gel retardation assay and TEM. The GQDs+PEI+RNP in vitro editing capability is shown by targeting the TP53 414delC frameshift mutation locus present in PC3 cancer cell line for prostate cancer. This form of editing serves as a guide for future cancer therapy using GQDs as non-viral delivery of Cas9 RNP to mutant TP53 genes overexpressed in about 50% of cancers.

One of the large unanswered questions in astronomy is: How does the Milky Way galaxy evolve, chemically and dynamically? Of all the objects that we could use to probe this question, groups of stars which were all born from the same gas cloud, known as open clusters, are the most reliable. This makes open clusters ideal for exploring the evolution of our Galaxy because we can determine not only the distance, position, velocity, and chemistry of the cluster, but we can also pin a reliable age to the cluster as well. Historically, assembling a statistically significant dataset of open clusters has proved to be challenging without inducing large systematic uncertainties by collecting data from multiple sources. The Open Cluster Chemical Abundance and Mapping (OCCAM) survey is a uniform dataset of star clusters that uses dynamical data from the Gaia space telescope and 16 different chemical abundances from the APOGEE survey, which is a part of the Sloan Digital Sky Survey. This new update to OCCAM includes uniformly measured data for 153 open clusters and a total of 2061 member stars, which we use to investigate the chemical evolution of the Milky Way.

Through the use of large-scale surveys, astronomers are able to investigate Milky Way galaxy evolution, both dynamically and chemically; however, determining reliable stellar ages has been elusive.  Star clusters are the most reliable way to measure ages of stars, and new surveys are measuring detailed chemistry for cluster stars that may be able to be correlated with age. For our study, we are using carbon and nitrogen abundances within red giant stars as age indicators. Using the Open Cluster Chemical Abundances and Mapping (OCCAM) survey, we utilized stellar parameters and abundances, and created a uniform empirical relationship between stellar ages and carbon-to-nitrogen abundances using star clusters. This new calibration will allow us to determine reliable ages for over 100,000 stars across the Milky Way galaxy, allowing us to measure the chemical evolution of the Galaxy.

With the development of personalized cancer medicine and moving away from a conventional biopsy, there is a need in creating a multifunctional platform for cancer diagnosis and treatment monitoring. Sonography offers many advantages over standard methods of therapeutic imaging due to its non-invasiveness, deep penetration, high spatial and temporal resolution, low cost, and portability. The benefits of the ultrasound method make contrast agents an ideal platform for the efficient strategy of cancer diagnostic and therapy. In this work, we developed metal-doped graphene quantum dots that demonstrate high-contrast properties in ultrasound brightness mode. The successful imaging enhancement was observed in tissue phantom and chicken breasts tissue. The relatively small size of the metal-doped graphene quantum dots makes them easily be internalized into the cells, while functional groups on their surface allow binding a cancer-targeted marker and therefore be used as a cancer-targeted delivery. By a combination of imaging and targeting capabilities, ultrasound contrast agents based on metal-doped graphene quantum dots enable desired cancer-focused nanotherapeutic and imaging approaches.

For billions of years, our Milky Way galaxy has churned out countless stars. However, the best star-forming days of our galaxy are long gone and our galaxy is in a midlife crisis! It’s running out of gas to make new stars, and extraneous resources are scarce. Worse yet, high stellar winds might eject some gaseous material, such as the Smith Cloud. After it was ejected, the Milky Way’s gravity caused this cloud to reverse course and fall back toward our Galaxy. The Smith Cloud is now only 40,000 light-years away and carries with it the equivalent of over 1 million Suns worth of material. As it makes the journey back to our Galactic Plane, it must endure heavy winds that have temperatures in excess of 1 million degrees Celsius from the Milky Way galaxy’s coronal gas. I have already measured the amounts of various ions in adjacent cloud fragments positioned on the side of the Smith Cloud using Hubble Space Telescope observations. These ions include C+, Si+, Si2+, Si3+ , and S+. I will then determine the effects that these high winds have on the adjacent fragments and the trailing wake of the Smith Cloud to better understand the perils that gas clouds must undergo to reach massive galaxies.

Dwarf galaxies are the building blocks larger galaxies. Their shallow gravitational potentials makes them extremely sensitive to explosions of stars. To understand how dwarf galaxies form and evolve, we must study their formation, evolution and fate in a range of environments. Located 13 million light years away, Centaurus A is the closest massive elliptical galaxy making it ideal for investigating the effects of local environment on the formation and evolution of dwarf galaxy populations. We model the dwarf satellite populations of Centaurus using a suite of high resolution N-body simulations and the semi-analytic model (SAM) Galacticus (Benson, 2010). We determine the best fit parameters for well studied Milky Way satellite, before applying those parameters to generate simulated satellites around our Centaurus A's analog. Given the relatively low computational cost of N-body simulations and SAMs, we are able to explore the effects of uncertainties in the Centaurus A system, including its relatively unconstrained mass. Here we present initial results from our study for the first Centaurus A like galaxy.

Research suggests that cannabidiol (CBD) can act as an anxiolytic when injected (Blessing et al, 2015). We investigated whether these findings could be replicated in rats using chronic (12 day) voluntary oral consumption of non-pharmaceutical grade CBD oil at 20mg/kg. A control group consumed distilled water. An elevated plus maze (Test 1), open field (center vs. outer, light vs. dark, Test 2 and 3), and running wheel (Test 4) were used to examine the anxiolytic effect of CBD beginning on day 12 of administration and two hours after consumption. One test occurred each day. It was hypothesized that CBD rats would spend more time in the open arms of the elevated plus maze than the control group, and more time in the center and lit areas of the open field compared to the control rats. For the running wheel, we expected the CBD rats to turn the wheel more times than the control group. Results revealed that in the open field, the CBD group spent more time in the center compared to the control group, as was expected. There were no other differences between groups. These results are discussed with respect to administration route, timing of test, and type of test.

Varied practice, or studying many different examples of a given topic, can be a more effective method for learning a concept compared to studying one example repeatedly, as demonstrated in motor learning (e.g., Kerr & Booth, 1978) and category learning (e.g., Wahlheim et al., 2012). The present study examined how varied practice affects learning vocabulary from examples used in sentences. Although potentially beneficial for long-term understanding, varied practice can make initial vocabulary learning challenging because the example sentences for a given term may vary greatly. The current study presented participants with a sentence and asked them to select the correct vocabulary word that completed the sentence. For half of the vocabulary terms, participants were tested on that vocabulary word in the same sentence repeatedly (constant practice); for the other half of the words, participants were tested on that vocabulary word in different sentences (varied practice). Participants were also asked to answer questions about their attention during the task. After a short delay, participants took a final test to investigate how well they could identify the studied vocabulary words in novel sentences. The results will be discussed in terms of desirable difficulties, the distinction between learning and performance, and whether the type of practice may influence attention.

Background
Autism spectrum disorder (ASD) is a neurodevelopmental disorder that causes deficits in reciprocal social communication and restricted and repetitive patterns of behaviors, interests, and activities (APA, 2013).
Previous work has found disagreement between parents in their perception of characteristics of their child (Duhig et al., 2000). These differences in perception have been termed ‘informant discrepancies’ and have been linked, in neurotypical (NT) families, to phenomena within the family system such as maternal depression and family distress levels (Christensen et al., 1992; Whiffen et al., 1990). Previous work with NT and ADHD children also found that mothers rated their child’s symptoms as more severe than fathers did (Langberg et al., 2010; Christensen et al., 1992). There is, however, a paucity of research examining possible discrepancies between parents of autistic children (Stratis & Lecavalier, 2015). Because the entire family is impacted by characteristics of each individual member, parents of children with autism may differ from parents of NT children and consequently, research utilizing parents of NT children may not generalize to parents of ASD children.
The current study seeks to examine possible patterns of discrepancies in parents’ perception of their child’s internalizing and externalizing behaviors in parents with ASD children. I aim to determine the rate at which parents agree about their child’s internalizing and externalizing behaviors and to determine which parent perceives behaviors as more severe when parents disagree. Lastly, I aim to determine whether discrepancies in parent perception of child behavior predict depression for either parent.
Method
Participants in this multi-site study included 117 mothers and fathers with a child between 10 and 17 years old with autism. Parents were required to be married or cohabitating for at least one year, to be living with their child at least 50% of the time, and to be able to read and speak English. Their children were required to have a community diagnosis of ASD and must not have a co-occurring intellectual disability. Mothers’ average age was 43.15 years (SD = 6.42) and fathers’ average age was 44.99 years (SD = 6.90). The majority of parents were White and reports of annual family income revealed that 47% earned more than $100,000. Families came to the testing site and completed a series of questionnaires.
The Child Behavior Checklist (CBCL: Achenbach, 1999) was used to measure parents’ perceptions of their child’s internalizing and externalizing behaviors. The CBCL contains a total of 73 items and two subscales; one for internalizing behaviors (mothers, α = .87; fathers, α = .86) and one for externalizing behaviors (mothers, α =.92; fathers, α = .91). Using a three-point Likert-type scale, parents were asked whether statements about their children were not true, somewhat true, or always true in the last two months. Parent depression was measured using the Inventory of Depression and Anxiety Symptoms (IDAS; Watson et al., 2007). This 64 item measure uses a five point Likert-type scale (1 = not at all, 5 = extremely) to measure how true statements are of the participant in the previous two weeks.
Results
Parent scores were considered to be discrepant if they were more than half of a standard deviation apart. Raw scores were converted to Z scores in SPSS and the difference between Z scores was calculated. Analyses revealed that about half of parents agreed about their child’s symptoms while half disagreed for both internalizing and externalizing symptoms. Additionally, when parent did disagree, fathers rated behavior as more severe about half of the time, while mothers rated behavior as more severe the other half of the time (see Table 1 for precise descriptives).
Table 1. Percentage of instances of parent agreement, mother rating higher than father, and father rating higher than mother for internalizing and externalizing behaviors.
Externalizing Behaviors Internalizing Behaviors
Agreement groups Percentage Agreement groups Percentage
In agreement 50.90 In agreement 50.90
Mothers > fathers 24.10 Mothers > fathers 24.10
Fathers > mothers 25.00 Fathers > mothers 25.00

Further analyses will be conducted using polynomial regression with response surface analysis to determine whether discrepancies in parent perception of their child’s internalizing or externalizing symptoms predict depression for either parent.
Discussion
Results revealed that parents agreed about their child’s symptoms about half of the time for both internalizing and externalizing behaviors. Additionally, in instances where parents disagreed, mothers rated behaviors higher than fathers half of the time and lower than fathers half of the time for both internalizing and externalizing behaviors. This is inconsistent with prior work using parents of NT children, which found that mothers tended to rate child behavior higher than fathers. Further work needs to assess both the potential factors contributing to each discrepancy type and possible individual and family outcomes associated with each type.
Analyses will be run before the conference to determine whether the discrepancies in parents’ perception of their child’s symptoms predict depression for the mothers or fathers included in our sample.
 
References

Achenbach, T. M. (1999). The Child Behavior Checklist and related instruments. In M. E. Maruish (Ed.), The use of psychological testing for treatment planning and outcomes assessment., 2nd ed. (pp. 429–466). Lawrence Erlbaum Associates Publishers.
American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Arlington, VA: American Psychiatric Publishing.
Christensen, A., Margolin, G., & Sullaway, M. (1992). Interparental agreement on child behavior problems. Psychological Assessment, 4, 419–425.
Duhig, A. M., Renk, K., Epstein, M. K., & Phares, V. (2000). Interparental agreement on internalizing, externalizing, and total behavior problems: A meta-analysis. Clinical Psychology: Science and Practice, 7(4), 435–453. https://doi.org/10.1093/clipsy.7.4.435
Stratis, E. A., & Lecavalier, L. (2015). Informant agreement for youth with autism spectrum disorder or intellectual disability: A meta-analysis. Journal of Autism and Developmental Disorders, 45(4), 1026–1041. https://doi.org/10.1007/s10803-014-2258-8
Watson, D., O'Hara, M. W., Simms, L. J., Kotov, R., Chmielewski, M., McDade-Montez, E. A., & Stuart, S. (2007). Development and validation of the Inventory of Depression and Anxiety Symptoms (IDAS). Psychological assessment, 19(3), 253.

In a feature-positive discrimination, responding to a target stimulus (A) is reinforced only when presented with a feature stimulus (X), but not when presented alone (XA+/A-). The manner in which animals solve this type of discrimination is affected by the temporal arrangement of the feature-target compound. Presenting the compound in a serial fashion (X --> A) results in X acquiring the ability to set the occasion to respond to A. When the compound is presented simultaneously (X:A), X could either directly control responding or X and A could form a unique stimulus configuration (i.e., configural learning). The present experiment used a spatial occasion setting procedure with pigeons to examine the ability of a feature (a diffuse background color) to modulate responding to a landmark (LM). For two of the feature-positive trial types, the feature and LM were presented simultaneously, and the LM and goal were always in the same spatial location (simultaneous/static). During other trial types, the feature preceded the presentation of the LM and the location of the LM and goal varied across trials (serial/dynamic). Responding was reinforced at the location to right or left of the landmark when presented with an occasion setter (static: +<-- WA, XB -->+, dynamic: +<--YC, ZD-->+), but not on LM-only trials. Transfer tests (WB, XA, YD, ZC) were used to differentiate between the features as occasion setters or direct control/configurations. The results of LM transfer tests will be discussed with respect to the mechanisms of feature-positive discrimination learning.

The reintroduction of captive-bred animals has been increasingly utilized for the conservation of many species. However, few studies have focused on the importance of environmental factors and resource availability in the success of wildlife reintroductions. The goal of this study was to see if location influences the short-term reintroduction success of captive-bred Texas horned lizards (Phrynosoma cornutum). Specifically, I monitored diets, growth rates, and survival of over 250 lizards reintroduced to 2 locations in Mason Mountain Wildlife Management Area (Mason County, TX) for 3 months. Diet, growth rates, and survival all differed between the two locations. The findings of this study suggest that environmental factors can play an important role in the reintroduction success of Texas horned lizards. Future research will focus on identifying specific habitat characteristics that may contribute to the observations of this study such as prey availability, vegetation, thermal habitat quality, and soil permeability.

Changes in thyroid hormones levels have been associated with alterations in somatic development and growth. However, recent studies have shown that alterations in thyroid hormone levels during early life stage (ELS) development can lead to long-term changes in reproduction. Specifically, fathead minnows that have been exposed to propylthiouracil (PTU) experienced a 50% reduction in fecundity. The purpose of this study was to determine if ELS thyroid disruption led to an alteration of reproductive behaviors in male fathead minnows. To accomplish this, larval fathead minnows were exposed to PTU and reproductive behaviors were quantified. Results showed that PTU-exposed fish demonstrated significantly fewer reproductive behaviors than those in the control group. This data provides an explanation for the previously observed 50% decrease in fecundity in the fathead minnows exposed to PTU and provides further evidence that ELS thyroid disruption can interfere with the display of key and ecologically-relevant behaviors later in life.

The rainbow trout, Oncorhynchus mykiss, is a partially migratory organism, that has been used recently to study the genetic control of migration. Much of this research has taken place at a unique site in Sashin Creek, Alaska, where the resident O. mykiss population is completely isolated from the migratory population. However, it is unknown the extent to which findings here are shared with other populations. Here we used a fine-scale genome-wide sequencing approach known as pooled sequencing to gather genetic data from 174 fish in two locations – Sashin Creek, Alaska and Little Sheep Creek, Oregon. Four sequenced pools were developed based on phenotype and population. We then measured differentiation between the populations to identify regions that may be correlated with the resident or migratory phenotype in both populations. We were able to locate 8 genes in 16 regions of shared elevated FST, and 17 genes over 16 regions with a significant Tajima’s D value that were specific to either the migratory or resident phenotype. These findings indicate specific genes and chromosomal regions that may be important in the regulation of migratory tendency in this species.

The student hasn't submitted any abstract yet.

For this project, I mapped potential river otter habitat in the Dallas/Fort Worth metroplex based on literature data on known river otter habitat preferences in Texas. I will use this data along with GIS data on land use/cover/vegetation and distance from suitable water bodies, to determine where in the DFW river otters may prefer to live. This project is interesting and informative because in recent years more urban run-ins with river otters have been documented in the DFW. So knowing where they might like to be is good information for citizens to have, as river otters continue to make a comeback in numbers in the state of Texas.

Carnivorous plants inhabit nutrient-poor environments and supplement nutrient acquisition by capturing and digesting insect prey. Carnivorous adaptations have been hypothesized to be beneficial only in environments with high water and light availability. We hypothesized that plant morphology would change in response to resource availability, exhibiting traits that increase carnivory when light is abundant and exhibiting traits that increase photosynthesis when light is limited. In a field manipulation in Leon County, Texas, we examined the effects of feeding, shading, and their interaction on the morphology of the pitcher plant, Sarracenia alata. We employed a two-factor, cross-classified design, with shading (two levels, shaded and unshaded) and prey capture (two levels, fed and unfed) as factors. Eighty plants were haphazardly assigned to one of four treatments: (1) unshaded and fed (control); (2) shaded and fed; (3) unshaded and unfed; and (4) shaded and unfed. When light availability was reduced, plants produced pitchers that had smaller diameters, which is reflective of a photosynthetic morphology. Unfed plants exhibited reduced growth (produced fewer pitchers and had lower sum of pitcher heights). There was a significant interaction effect on estimated seasonal aboveground biomass: shading had no effect on the mass of unfed plants, but shading reduced the mass of fed plants. As the season progressed, competing vegetation reduced light availability to all pitchers. Plants in all treatments began to produce pitchers that were blade-like with a small, non-functional opening and a widened keel. This morphology would maximize light capture at the expense of prey capture. This experiment provides support for a theoretical model that suggests that carnivorous traits are only beneficial under conditions of high light availability. It also emphasizes the importance of periodic burns of carnivorous plant bogs to remove vegetation, thereby reducing light competition.

Micellization is a phenomenon of central importance in surfactant solutions. Here, we demonstrate that the diffusion-based spreading of the free boundary between a micellar aqueous solution and pure water yields a one-dimensional spatial profile of surfactant concentration that can be used to identify the critical micelle concentration, here denoted as C*. This can be achieved because dilution of micelles into water leads to their dissociation at a well-defined position along the concentration profile and an abrupt increase in diffusion coefficient. Rayleigh interferometry was successfully employed to determine C* values for three well-known surfactants in water at 25 ºC: Triton X-100 (TX-100), Sodium Dodecyl Sulfate (SDS), and Polyoxyethylene(4)Lauryl Ether (Brij-30). The dependence of C* on salt concentration was also characterized for TX-100 in the presence of Na2SO4, NaCl, and NaSCN. Accurate values of C* can be directly identified by visual inspection of the corresponding concentration-gradient profiles. To apply the method of least squares to experimental concentration profiles, a mathematical expression was derived from Fick’s law and the pseudo-phase separation model of micellization with the inclusion of appropriate modifications. While Rayleigh interferometry was employed in our experiments, this approach can be extended to any experimental technique that yields one-dimensional profiles of surfactant concentration. Moreover, diffusion-driven surfactant disaggregation is precise, non-invasive, requires single-sample preparation, and applies to both non-ionic and ionic surfactants. Thus, this work provides the foundation of diffusion-driven dilution methods, thereby representing a valuable addition to existing techniques for the determination of C*.

Oxidative stress is a result of an imbalance between reactive oxygen species (ROS) and the availability/activity of antioxidants. The catalase family of enzymes mitigate the risk from ROS by facilitating the disproportionation of hydrogen peroxide into molecular oxygen and water. Manganese containing catalase (MnCAT) consists of a binuclear manganese core bridged by carboxylate and single-atom ligands, likely water or hydroxide. In this work, hydrogen peroxide disproportionation using complexes of manganese with cyclen and pyclen were investigated due to the spectroscopic similarities of the latter with the native MnCAT enzyme. Potentiometric titrations were used to construct speciation curves to identify what complex compositions were present at different pH values. Based on these results, the complexes were made in situ by mixing stock solutions of ligand, buffer, and metal. The hydrogen peroxide disproportionation reaction was carried out in a sealed cell and PO2 measured using a microsensor (Unisense). When hydrogen peroxide was injected into the cell, disproportionation activity of the complexes was evident by (1) appearance of bubbles in solution, and (2) noticeable increase in PO2 as measured by the sensor. Spectroscopic investigation before, during, and after the reaction was used to follow changes in the UV-visible absorption of the complexes to collect information about the structure of the initial catalyst and any possible intermediate. Both, pyclen and cyclen were determined to form a dimeric structure under the reaction conditions used.

The aptamer domain of a naturally occurring glycine riboswitches was randomized to generate a library containing billions of different variants. The dual genetic selection of this library was performed for sarcosine, a prostate cancer marker, and successfully led to the identification of sarcosine-specific synthetic riboswitches. When a chloramphenicol-resistance gene was expressed under control of these riboswitches, E. coli cells showed chloramphenicol resistance only in the presence of sarcosine. For a colorimetric assay, the sarcosine riboswitch gene was inserted upstream of the lacZ gene. When tested with various concentrations of sarcosine, the enzymatic activity of LacZ was proportional to the amount of sarcosine, clearly indicating the sarcosine-dependent gene regulation by the sarcosine riboswitch.

Triazines appear in pharmaceuticals, agrochemicals, and as building blocks for polymers used in materials science and medicine. Predicting the structure and dynamics in water as a function of pH requires reliable simulations of the pKa values for different sites for protonation. We present the initial DFT methods and continuum solvent for pKa of amines, ring nitrogens, and 2,4,6-triamino-1,3,5-triazine (melamine) derivatives. These M06-2X/6-311++G(2d,2p) calculations in SMD continuum solvent provide consistent accuracy for tested systems, use for future studies of more complex structures.

Owing to the increasing importance of manganese(II) complexes in the field of magnetic resonance imaging (MRI), large efforts have been devoted to find an appropriate ligand for Mn(II) ion encapsulation by providing balance between the seemingly contradictory requirements (i.e., thermodynamic stability and kinetic inertness vs low ligand denticity enabling water molecule(s) to be coordinated in its metal center). Among these ligands, a large number of pyridine or pyridol based open-chain and macrocyclic chelators have been investigated so far. As a next step in the development of these chelators, 15-pyN3O2Ph and its transition metal complexes were synthesized and characterized using established methods. The 15-pyN3O2Ph ligand incorporates both pyridine and ortho-phenylene units to decrease ligand flexibility. The thermodynamic properties, protonation and stability constants, were determined using pH-potentiometry; the solid-state structures of two protonation states of the free ligand and its manganese complex were obtained by single crystal X-ray diffractometry. The results show a seven-coordinate metal center with two water molecules in the first coordination sphere. The longitudinal relaxivity of [Mn(15-pyN3O2Ph)]2+ was found to be 5.16 mM−1 s−1 at 0.49 T (298 K). Furthermore, the r2p value of 11.72 mM−1 s−1 (0.49 T), which is doubled at 1.41 T field, suggests that design of this Mn(II) complex does achieve some characteristics required for contrast imaging. In addition, 17O NMR measurements were performed in order to access the microscopic parameters governing this key feature (e.g., water exchange rate). Finally, manganese complexes of ligands with analogous polyaza macrocyclic scaffold have been investigated as low molecular weight Mn(CAT) mimics. Here, we report the H2O2 disproportionation study of [Mn(15-pyN3O2Ph)]2+ to demonstrate the versatility of this platform as well.

Fmoc-protected and propargyl-containing thymine and Cbz-protected cytosine monomers were synthesized for possible use in the pre- or post-functionalization of PNA oligomers via click chemistry. The monomers should be suitable for incorporation in normal automated solid phase PNA synthesis. The synthesis is suitable for the preparation of gram-quantities of monomers and uses reductive amination as the key step.

Do edge effects influence wildlife distributions in a small game reserve in South Africa?
Lyall A. Blanché*1 and Victoria J. Bennett1
1Department of Environmental Science, Texas Christian University, Fort Worth, TX 76129 USA
Physical boundaries in the landscape can influence the abundance and distribution of species through edges effects, which are characterized as a behavioral response to features or boundaries, creating an area of avoidance known as edge habitat. The implication is a reduction in the amount of available habitat for an individual and/or its population. Studies have shown that anthropogenic features, such as roads and fences, can cause edge effects. Thus, should we be considering the consequences of anthropogenic edge effects when managing wildlife populations in game reserves? To address this, we used Global Positioning System point locations collected from 2004-2020 on cheetah, elephant, leopard, and lion in Amakhala Game Reserve, a 66 km2 fenced reserve in the Eastern Cape of South Africa. This reserve is bordered by a national highway and bisected by a public road. We used regression analysis to determine any relationship between the proportion of locations within 5 m increments and 1) the national highway, 2) public road, 3) boundary fence, 4) a river on the reserve, and 5) control sections of the reserve. Our analysis revealed a significant positive correlation between elephant locations and distance from the national highway, with elephants avoiding a 600 m wide section of the reserve next to the highway. Our study highlights the importance of identifying potential edge effects to better inform the management of small reserves.