Graphene oxide (GO) inherits high transparency, substantial conductivity, high tensile strength from its parent materials graphene. Apart from these properties, it emits fluorescence which makes it a potential material to use in optoelectronics and bio-sensing applications. In this work, we have utilized systematic ozone treatment to alter the optical band gap of single-layered graphene oxide in aqueous suspensions. Due to controlled ozonation, additional functionalization takes place in GO graphitic sheet which changes GO electronic structure. This is confirmed by the increase in vibrational transitions of a number of oxygen-containing functional groups with treatment and the appearance of the prominent carboxylic group feature at c.a. 1700 1/cm. Albeit, timed ozone induction introduces only slight change in color and absorption spectra of GO samples, the emission spectra show a gradual increase in intensity with a significant blue shift up to 100 nm from deep red to green. This large blue shift suggests an increase in optical band gap with additional functionalization introduced by ozone treatment. We utilize a semi-empirical theoretical approach to describe the effects of functionalization-induced changes. This model attributes the origins of fluorescence emission to the quantum confined sp² carbon islands in GO encircled by the functional groups. As we decrease the graphitic carbon cluster size on the GO sheet, the optical bandgap calculated via HyperChem molecular modeling increases, which supports the experimentally observed blue shifts in emission. This theoretical result is further supported by the TEM measurement of ozone-treated samples, which shows a decreasing trend of average ordered graphitic carbon cluster size on GO sheets with treatment time. Theoretical modeling, as well as the experimental results, indicate that the optical bandgap and emission intensity of GO are alterable with controlled ozone treatment, which allows tailoring the optical properties of GO for specific applications in optoelectronics and bio-sensing.

The Open Cluster Chemical Abundances and Mapping (OCCAM) survey is a systematic survey of Galactic open clusters using data primarily from the SDSS-III/APOGEE-1 survey. However, neutron capture elements are limited in the IR region covered by APOGEE. In an effort to fully study detailed Galactic chemical evolution, we are conducting a high resolution (R~60,000) spectroscopic abundance analysis of neutron capture elements for OCCAM clusters in the optical regime to complement the APOGEE results. As part of this effort, we present Ba II, La II, Ce II and Eu II results for a few open clusters without previous abundance measurements using data obtained at McDonald Observatory with the 2.1 m Otto Struve telescope and Sandiford Echelle Spectrograph.

The goal of this study was to conduct a survey of 913 M-dwarf stars from the Lepine and Shara Proper Motion(LSPM) catalog within 33 parsecs. This research was conducted to improve upon the statistics of nearby multiple M-dwarf star systems. Identifying and confirming multiple systems at both wide and small separations will expand understanding of M-dwarf formation by comparing these results to existing star formation models. Data for these targets was collected with the Robo-AO camera on the Palomar 60in telescope. Separation and position angles were determined and compared for two epochs of the images containing multiple stars, one taken in 2012 and the other taken in 2014, to look for changes in these values. Stars with little change in position with respect to one another suggest they are common proper motion pairs. The Washington Double Star(WDS) catalog and other resources were used to further determine binarity. There were 50 multiple star system candidates found with a multiplicity fraction of 28.6±3.0 and a companion star fraction of 34.7±2.1.

A galaxy environment influences its internal properties. All galaxies start out small and grow bigger after merging with other galaxies. We are conducting a statistical study on isolated and interacting galaxies to determine how their environment impacts on their star-formation ability. We are using observations from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which has already observed more than 3000 galaxies. We are examining the differences and similarities of the gas and stars in isolated and interacting galaxies to explore their past and current star formation activity. From these comparisons, we will identify which conditions promote and hinder star formation to learn how different types of galaxies evolved. An example of an isolated galaxy is shown here.

Birdsong, like human speech, is a vocal behavior that requires birds to precisely coordinate the activation of respiratory and vocal organ motor systems in order to generate sufficient subsyringeal air pressure for phonation. In both juvenile and adult songbirds, ablation or inactivation of HVC (proper name) neural activity disrupts temporal features of song. Consistent with the role of respiration in controlling song tempo, we have previously demonstrated that HVC contributes to song respiratory features in adult male Bengalese finches (Lonchura striata domestica, Urbano & Cooper, 2015). Here we further explored these findings by recording subsyringeal air sac pressure in singing birds prior to, during, and following recovery from HVC inactivation. Dialysis probes were implanted into either left or right HVC in adult male Bengalese finches (N=5), allowing for reversible suppression of neural activity (muscimol, 1.5 mg/mL, 1.125mg/mL, 0.75 mg/mL, 0.375 mg/mL). In all animals, mean air sac pressure and initial (10 ms) slope of song-related expiratory pulses (EPs) dropped significantly during HVC inactivation and recovered (Amplitude: F(2,8) = 12.8, p = 0.003; Slope: F(2,8) = 15.3, p = 0.002). We observed that, independent of the drug concentration, peak song EP amplitude exhibited a similar pattern of non-linear recovery over time while muscimol remained in the dialysis probe and continued to diffuse into HVC. In a subset of the data, we used an already established measure of efficacy (Beggs & Dobrovolny 2015) to model the change in peak song EP amplitude during HVC inactivation and we were able to produce consistent estimates for the variables in our model. We then ran a Monte Carlo simulation and parameter stability analysis to determine that the chosen model is robust and truth-conducive in predicting future values for peak EP amplitude under continued diffusion of muscimol into the tissue. We tested this model against simpler models to rule out alternative explanations. These results suggest that prolonged exposure to muscimol (4-6 h) induces mechanisms that reduce the efficacy of muscimol and result in gradual recovery of peak song EP amplitude.