Physical Sciences and Mathematics Commons^™

Identification Of An Active Site-Bound Nitrile Hydratase Intermediate Through Single Turnover Stopped-Flow Spectroscopy, Natalie Gumataotao, Misty L. Kuhn, Natalia Hajnas, Richard C. Holz

Richard C. Holz

Stopped-flow kinetic data were obtained for the iron-type nitrile hydratase from Rhodococcus equi TG328-2 (ReNHase) using methacrylonitrile as the substrate. Multiple turnover experiments suggest a three-step kinetic model that allows for the reversible binding of substrate, the presence of an intermediate, and the formation of product. Microscopic rate constants determined from these data are in good agreement with steady state data confirming that the stopped-flow method used was appropriate for the reaction. Single turnover stopped-flow experiments were used to identify catalytic intermediates. These data were globally fit confirming a three-step kinetic model. Independent absorption spectra acquired between 0.005 …

Spectroscopic Investigation Of The Chemical And Electronic Properties Of Chalcogenide Materials For Thin-Film Optoelectronic Devices, Kimberly Horsley

UNLV Theses, Dissertations, Professional Papers, and Capstones

Chalcogen-based materials are at the forefront of technologies for sustainable energy production. This progress has come only from decades of research, and further investigation is needed to continue improvement of these materials.

For this dissertation, a number of chalcogenide systems were studied, which have applications in optoelectronic devices, such as LEDs and Photovoltaics. The systems studied include Cu(In,Ga)Se2 (CIGSe) and CuInSe2 (CISe) thin-film absorbers, CdTe-based photovoltaic structures, and CdTe-ZnO nanocomposite materials. For each project, a sample set was prepared through collaboration with outside institutions, and a suite of spectroscopy techniques was employed to answer specific questions about the system. These …

Laser-Induced Breakdown Spectroscopy For Analysis Of High Density Methane-Oxygen Mixtures, Matthew Dackman

Masters Theses

The applicability of laser-induced breakdown spectroscopy (LIBS) toward greater than atmospheric density combustion diagnostics is examined. Specifically, this involves ascertaining the feasibility of measuring chemical equivalence ratios directly from atomic emission spectra at high density. The need for such measurement arises from the desire to quantify real time, localized combustion performance in weakly mixed flows. Insufficiently mixed flows generally result in unwanted byproducts, possess the propensity for overall combustion instability, and are increasingly likely to experience localized flame extinction.

We simulate methane/oxygen combustion in ambient pressures ranging 1 to 4 atmospheres, demonstrating these results to be analogous to what would …

The Power Of Principled Bayesian Methods In The Study Of Stellar Evolution, Ted Von Hippel, David Van Dyk, David Stenning, Elliot Robinson, Elizabeth Jeffery, Nathan Stein, William Jefferys, Erin M. O'Malley

Publications

It takes years of effort employing the best telescopes and in- struments to obtain high-quality stellar photometry, astrometry, and spectroscopy. Stellar evolution models contain the experience of life- times of theoretical calculations and testing. Yet most astronomers fit these valuable models to these precious datasets by eye. We show that a principled Bayesian approach to fitting models to stellar data yields substantially more information over a range of stellar astrophysics. We highlight advances in determining the ages of star clusters, mass ratios of binary stars, limitations in the accuracy of stellar models, post-main-sequence mass loss, and the ages of individual …

Direct Determination Of Multiple Ligand Interactions With The Extracellular Domain Of The Calcium Sensing Receptor, Chen Zhang, You Zhuo, Heather A. Moniz, Shuo Wang, Kelley W. Moremen, James H. Prestegard, Edward M. Brown, Jenny J. Yang

Chemistry Faculty Publications

Numerous in vivo functional studies have indicated that the dimeric extracellular domain (ECD) of the CaSR plays a crucial role in regulating Ca2+ homeostasis by sensing Ca2+ and L-Phe. However, direct interaction of Ca2+ and Phe with the receptor’s ECD and the resultant impact on its structure and associated conformational changes have been hampered by the large size of the ECD, its high degree of glycosylation, and the lack of biophysical methods to monitor weak interactions in solution. In the present study, we purified the glycosylated extracellular domain of CaSR (ECD) (residues 20~612), containing either complex or high mannose N-glycan …

Optical Spectroscopy Of Xenon-Related Defects In Diamond, Yury Dziashko

Dissertations, Theses, and Capstone Projects

The work presents the results of optical studies of Xe-related defect in diamond. This defect is one of a few having narrow zero-phonon line in the near-infrared part of the photo-luminescence spectra. It appears in diamond after Xe+ ion implantation followed by thermal annealing. Given unique physical properties of diamond (hardness, optical transparency in wide spectral range, chemical inertness, high thermal conductivity, low thermal expansion coefficient) and stability of Xe-related center it can be viewed as an potential candidate for the source of single-photons, or as optically manipulated qubit, not unlike nitrogen-vacancy center. However, compared to the latter Xe-related center …

Thermodynamic And Structural Characterization Of Amino Acid-Linked Dialkyl Lipids., Stephanie Tristram-Nagle, Ruthven Lewis, Joseph Blickenstaff, Michael Diprima, Bruno Marques, Ronald Mcelhaney, John Nagle, James Schneider

Prof. Stephanie Tristram-Nagle Ph.D.

Using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), we determined some thermodynamic and structural parameters for a series of amino acid-linked dialkyl lipids containing a glutamic acid-succinate headgroup and di-alkyl chains: C12, C14, C16 and C18 in CHES buffer, pH 10. Upon heating, DSC shows that the C12, C14 and annealed C16 lipids undergo a single transition which XRD shows is from a lamellar, chain ordered subgel phase to a fluid phase. This single transition splits into two transitions for C18, and FTIR shows that the upper main transition is predominantly the melting of …

Optimization Of Plasmon Decay Through Scattering And Hot Electron Transfer, Drew Dejarnette

Graduate Theses and Dissertations

Light incident on metal nanoparticles induce localized surface oscillations of conductive electrons, called plasmons, which is a means to control and manipulate light. Excited plasmons decay as either thermal energy as absorbed phonons or electromagnetic energy as scattered photons. An additional decay pathway for plasmons can exist for gold nanoparticles situated on graphene. Excited plasmons can decay directly to the graphene as through hot electron transfer. This dissertation begins by computational analysis of plasmon resonance energy and bandwidth as a function of particle size, shape, and dielectric environment in addition to diffractive coupled in lattices creating a Fano resonance. With …

Electron-Ion Equilibrium And Shock Precursors In The Northeast Limb Of The Cygnus Loop, Amber A. Medina, John C. Raymond, Richard J. Edgar, Nelson Caldwell, Robert A. Fesen, Dan Milisavljevic

Dartmouth Scholarship

We present an observational study using high-resolution echelle spectroscopy of collisionless shocks in the Cygnus Loop supernova remnant. Measured Hα line profiles constrain pre-shock heating processes, shock speeds, and electron-ion equilibration (T_e /T_i ). The shocks produce faint Hα emission line profiles, which are characterized by narrow and broad components. The narrow component is representative of the pre-shock conditions, while the broad component is produced after charge transfer between neutrals entering the shock and protons in the post-shock gas, thus reflecting the properties of the post-shock gas. We observe a diffuse Hα region extending about 25 …

Basic Astronomy Labs, Terry L. Smith, Michael D. Reynolds, Jay S. Huebner

Jay S Huebner

Providing the tools and know-how to apply the principles of astronomy first-hand, these 43 laboratory exercises each contain an introduction that clearly shows budding astronomers why the particular topic of that lab is of interest and relevant to astronomy. About one-third of the exercises are devoted solely to observation, and no mathematics is required beyond simple high school algebra and trigonometry.Organizes exercises into six major topics—sky, optics and spectroscopy, celestial mechanics, solar system, stellar properties, and exploration and other topics—providing clear outlines of what is involved in the exercise, its purpose, and what procedures and apparatus are to be used. …

Analysis Of Atmospheric Aerosols Collected In An Urban Area In Upstate Ny Using Proton Induced X-Ray Emission (Pixe) Spectroscopy, Jeremy Smith

Honors Theses

We have performed a PIXE analysis of atmospheric aerosol samples collected in Schenectady, NY, to study airborne pollution in an urban environment. The samples were collected using a PIXE International, 9-stage, cascade impactor that separates the airborne particles according to aerodynamic diameter and deposits them on thin Kapton foils. The impacted foils were bombarded with 2.2-MeV proton beams from the Union College 1.1-MV Pelletron accelerator and the emitted X-rays were detected with an Amptek silicon drift detector. The X-ray energy spectra were analyzed using GUPIX software to determine the elemental concentrations in the samples. A broad range of elements from …

Mechanical Routes To Biocontinuous Conductive Polymer Networks For Solar Cell Applications, Erin Waterman

Honors Theses

We have successfully created the first example of a bicontinuous conductive polymer network for use in hybrid QD-polymer solar cells via a mechanochemical route. Heterometallic dicyanoaurate coordination polymers were used as intercalative hosts to promote in situ growth of emeraldine polyaniline (PANI), which provides electron conduction pathways within the active layer. Cu2+-excanged Laponite RD nanodiscs were used to direct the self-assembly of the bicontinuous polymer networks and nanomorphology within the nanocomposites. These PANI/Laponite coordination polymers were extensively characterized by scanning electron microscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, and ultraviolet-visible absorption spectroscopy in order to probe polymer-nanoparticle and polymer-polymer interactions. …

A Comparative Study Of Gupix And Geopixe Software In The Analysis Of Pixe Spectra Of Aerosol Samples, Sean Collison

Honors Theses

Proton-induced X-ray emission (PIXE) spectroscopy is a powerful tool used in the Union College Ion-Beam Analysis Laboratory for the elemental analysis of environmental pollution. Samples are bombarded with proton beams from the 1.1‐MV Pelletron accelerator and characteristic X-rays emitted from the samples are detected, resulting in X-ray energy spectra. These spectra are analyzed using software packages that fit the data and calculate the concentrations of elements in the samples. I have performed a comparative study of two of the most popular software packages, GUPIX and GeoPIXE, in the analysis of atmospheric aerosol samples to assess the strengths and weaknesses of …

Gemini Long-Slit Observations Of Luminous Obscured Quasars: Further Evidence For An Upper Limit On The Size Of The Narrow-Line Region, Kevin N. Hainline, Ryan C. Hickox, Jenny E. Greene, Adam D. Myers

Dartmouth Scholarship

We examine the spatial extent of the narrow-line regions (NLRs) of a sample of 30 luminous obscured quasars at 0.4 < z < 0.7 observed with spatially resolved Gemini-N GMOS long-slit spectroscopy. Using the [O III] λ5007 emission feature, we estimate the size of the NLR using a cosmology-independent measurement: the radius where the surface brightness falls to 10^–15 erg s^–1 cm^–2 arcsec^–2. We then explore the effects of atmospheric seeing on NLR size measurements and conclude that direct measurements of the NLR size from observed profiles are too large by 0.1-0.2 dex on average, as compared to measurements made to best-fit Sérsic or Voigt profiles convolved with the seeing. These data, which span a full order of magnitude in IR luminosity (log (L _{8 μm}/erg s^–1) = 44.4-45.4), …

Development Of Optical Sensors For Chemical Detection, Jonathan Kelly Fong

Doctoral Dissertations

Detection of biodiesel at low and high concentrations in diesel is highly desired in the aviation and fuel industries. Cross contamination of jet fuel with biodiesel may impact the thermal stability and freezing point which can cause deposits in the fuel system or cause the fuel to gel, leading to jet engine operability problems and possible engine flameout. A dye doped optical sensor utilizing the dye Nile Blue Chloride has been developed for quick and direct detection of biodiesel which mainly contains fatty acid methyl esters (FAME). The sensing mechanism relies on the solvatochromatic properties of the dye which undergoes …

In-Package Atmospheric Pressure Cold Plasma Treatment Of Cherry Tomatoes, N. Misra, Kevin Keener, Paula Bourke, J Mosnier, Patrick Cullen

Articles

Cold plasma is increasingly under research for decontamination of foods, especially fresh fruits and vegetables. The effect of cold plasma on food quality, however, remains under researched. This study investigates the effects of cold plasma generated within a sealed package from a dielectric barrier discharge on the physical quality parameters and respiration rates of cherry tomatoes. Respiration rates and weight loss were monitored continuously, while other parameters are reported at the end of storage period. Differences among weight loss, pH and firmness for control and treated cherry tomatoes were insignificant towards the end of storage life. Changes in respiration rates …

Interaction Between The Broad-Lined Type Ic Supernova 2012ap And Carriers Of Diffuse Interstellar Bands, Dan Milisavljevic, Raffaella Margutti, Kyle N. Crabtree, Jonathan B. Foster, Alicia M. Soderberg, Robert A. Fesen, Jerod T. Parrent

Dartmouth Scholarship

Diffuse interstellar bands (DIBs) are absorption features observed in optical and near-infrared spectra that are thought to be associated with carbon-rich polyatomic molecules in interstellar gas. However, because the central wavelengths of these bands do not correspond to electronic transitions of any known atomic or molecular species, their nature has remained uncertain since their discovery almost a century ago. Here we report on unusually strong DIBs in optical spectra of the broad-lined Type Ic supernova SN 2012ap that exhibit changes in equivalent width over short ( 30 days) timescales. The 4428 Å and 6283 Å DIB features get weaker with …

Spectroscopic Analysis Of Seasonal Changes In Live Fuel Moisture Content And Leaf Dry Mass, Yi Qi, Philip E. Dennison, W. Matt Jolly, Rachael C. Kropp, Simon C. Brewer

School of Natural Resources: Faculty Publications

No abstract provided.

A New Set Of Spectroscopic Metallicity Calibrations For Rr Lyrae Variable Stars, Eckhart Spalding

Theses and Dissertations--Physics and Astronomy

RR Lyrae stars are old, iron-poor, Helium-burning variable stars. RR Lyraes are extremely useful for tracing phase-space structures and metallicities within the galaxy because they are easy to identify, have consistent luminosities, and are found in large numbers in the galactic disk, bulge, and halo. Here we present a new set of spectroscopic metallicity calibrations that use the equivalent widths of the Ca II K, Hγ, and Hδ lines to calculate metallicity values. Applied to spectroscopic survey data, these calibrations will help shed light on the evolution of the Milky Way and other galaxies.

Spectroscopic Analyses Of Factors Affecting Formation And Stability Of I-Motif Dna, Samantha Michelle Reilly

Electronic Theses and Dissertations

The four-stranded i-motif (iM) conformation of DNA has importance to a variety of biochemical systems that include nanomaterials and oncogene regulation. Fundamental studies to understand iM formation and its structure in solution still remain to be done. In this dissertation, we will discuss the use of the fluorescent base analog tC° to determine the structural state of DNA in solution. We will also demonstrate the use of tC° to determine both the hydrodynamic properties and the folding mechanism of an iM. We also determined the loop length dependence on iM formation and stability. Our hydrodynamic studies show that the iM …