183 Matching Results

Results open in a new window/tab. Unexpected Results? Search the Catalog Instead.

Study of Novel Ion/surface Interactions Using Soft-landing Ion Mobility (open access)

Study of Novel Ion/surface Interactions Using Soft-landing Ion Mobility

Preparative mass spectrometry is a gas-phase ion deposition technique aimed at deposition of monodisperse ion beams on a surface. This is accomplished through the implementation of a soft-landing ion mobility system which allows for high ion flux of conformationally selected ion packets. The soft-landing ion mobility system has been applied to a number of unique chemical problems including the deposition of insulators on graphene, the preparation of reusable surface enhanced Raman spectroscopic substrates, and the deposition of uranium nanoparticles. Soft-landing ion mobility provided a platform for the quick deposition of usable amounts of materials, which is the major objective of preparative mass spectrometry. Soft-landing ion mobility is unique when compared to other preparative mass spectrometric techniques in that the ion packets are conformationally separated, not separated on mass to charge ratio. This provides orthogonal complementary data to traditional mass spectrometric techniques and allows for the study of conformationally monodisperse surfaces. The diversity of problems that have been and continued to be explored with soft-landing ion mobility highlight the utility of the technique as a novel tool for the study of multiple ion/surface interactions.
Date: December 2012
Creator: Hoffmann, William Darryle
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Uniting Commedia Dell’arte Traditions with the Spieltenor Repertoire (open access)

Uniting Commedia Dell’arte Traditions with the Spieltenor Repertoire

Sixteenth century commedia dell’arte actors relied on gaudy costumes, physical humor and improvisation to entertain audiences. the Spieltenor in the modern operatic repertoire has a similar comedic role. Would today’s Spieltenor benefit from consulting the commedia dell’arte’s traditions? to answer this question, I examine the commedia dell’arte’s history, stock characters and performance traditions of early troupes. the Spieltenor is discussed in terms of vocal pedagogy and the fach system. I reference critical studies of the commedia dell’arte, sources on improvisatory acting, articles on theatrical masks and costuming, the commedia dell’arte as depicted by visual artists, commedia dell’arte techniques of movement, stances and postures. in addition, I cite vocal pedagogy articles, operatic repertoire and sources on the fach system. My findings suggest that a valid relationship exists between the commedia dell’arte stock characters and the Spieltenor roles in the operatic repertoire. I present five case studies, pairing five stock characters with five Spieltenor roles. Suggestions are provided to enhance the visual, physical and dramatic elements of each role’s performance. I conclude that linking a commedia dell’arte stock character to any Spieltenor role on the basis of shared traits offers an untapped resource to create distinctive characterizations based on theatrical traditions.
Date: May 2012
Creator: Trahan, Corey
Object Type: Thesis or Dissertation
System: The UNT Digital Library
The Express-Star (Chickasha, Okla.), Ed. 1 Friday, June 15, 2012 (open access)

The Express-Star (Chickasha, Okla.), Ed. 1 Friday, June 15, 2012

Daily newspaper from Chickasha, Oklahoma that includes local, state, and national news along with advertising.
Date: June 15, 2012
Creator: DeSilver, Debi
Object Type: Newspaper
System: The Gateway to Oklahoma History
Dynamic Stabilization of the Ablative Rayleigh-Taylor Instability for Heavy Ion Fusion (open access)

Dynamic Stabilization of the Ablative Rayleigh-Taylor Instability for Heavy Ion Fusion

Dynamic stabilization of the ablative Rayleigh-Taylor instability of a heavy ion fusion target induced by a beam wobbling system is studied. Using a sharp-boundary model and Courant-Synder theory, it is shown, with an appropriately chosen modulation waveform, that the instability can be sta- bilized in certain parameter regimes. It is found that the stabilization e ect has a strong dependence on the modulation frequency and the waveform. Modulation with frequency comparable to the instability growth rate is the most e ective in terms of stabilizing the instability. A modulation with two frequency components can result in a reduction of the growth rate larger than the sum of that due to the two components when applied separately.
Date: October 4, 2012
Creator: Hong Qin, Ronald C. Davidson and B. Grant Logan
Object Type: Report
System: The UNT Digital Library
Cornell Fuel Cell Institute: Materials Discovery to Enable Fuel Cell Technologies (open access)

Cornell Fuel Cell Institute: Materials Discovery to Enable Fuel Cell Technologies

The discovery and understanding of new, improved materials to advance fuel cell technology are the objectives of the Cornell Fuel Cell Institute (CFCI) research program. CFCI was initially formed in 2003. This report highlights the accomplishments from 2006-2009. Many of the grand challenges in energy science and technology are based on the need for materials with greatly improved or even revolutionary properties and performance. This is certainly true for fuel cells, which have the promise of being highly efficient in the conversion of chemical energy to electrical energy. Fuel cells offer the possibility of efficiencies perhaps up to 90 % based on the free energy of reaction. Here, the challenges are clearly in the materials used to construct the heart of the fuel cell: the membrane electrode assembly (MEA). The MEA consists of two electrodes separated by an ionically conducting membrane. Each electrode is a nanocomposite of electronically conducting catalyst support, ionic conductor and open porosity, that together form three percolation networks that must connect to each catalyst nanoparticle; otherwise the catalyst is inactive. This report highlights the findings of the three years completing the CFCI funding, and incudes developments in materials for electrocatalyts, catalyst supports, materials with structured and …
Date: June 29, 2012
Creator: Abruna, H. D. & DiSalvo, Francis J.
Object Type: Report
System: The UNT Digital Library
Real-structure effects: Band gaps of Mg_xZn_{1-x}O, Cd_xZn_{1-x}O, and n-type ZnO from ab-initio calculations (open access)

Real-structure effects: Band gaps of Mg_xZn_{1-x}O, Cd_xZn_{1-x}O, and n-type ZnO from ab-initio calculations

Many-body perturbation theory is applied to compute the quasiparticle electronic structures and the optical-absorption spectra (including excitonic effects) for several transparent conducting oxides. We discuss HSE+G{sub 0}W{sub 0} results for band structures, fundamental band gaps, and effective electron masses of MgO, ZnO, CdO, SnO{sub 2}, SnO, In{sub 2}O{sub 3}, and SiO{sub 2}. The Bethe-Salpeter equation is solved to account for excitonic effects in the calculation of the frequency-dependent absorption coefficients. We show that the HSE+G{sub 0}W{sub 0} approach and the solution of the Bethe-Salpeter equation are very well-suited to describe the electronic structure and the optical properties of various transparent conducting oxides in good agreement with experiment.
Date: February 15, 2012
Creator: Schleife, A & Bechstedt, F
Object Type: Article
System: The UNT Digital Library
Ab-initio description of quasiparticle band structures and optical near-edge absorption of transparent conducting oxides (open access)

Ab-initio description of quasiparticle band structures and optical near-edge absorption of transparent conducting oxides

None
Date: February 14, 2012
Creator: Schleife, A & Bechstedt, F
Object Type: Article
System: The UNT Digital Library
Single-cycle Terahertz Pulses with >0.2 V/A Field Amplitudes via Coherent Transition Radiation (open access)

Single-cycle Terahertz Pulses with >0.2 V/A Field Amplitudes via Coherent Transition Radiation

We demonstrate terahertz pulses with field amplitudes exceeding 0.2 V/{angstrom} generated by coherent transition radiation. Femtosecond, relativistic electron bunches generated at the Linac Coherent Light Source are passed through a beryllium foil, and the emitted radiation is characterized as a function of the bunch duration and charge. Broadband pulses centered at a frequency of 10 THz with energies of 140 {mu}J are measured. These far-below-bandgap pulses drive a nonlinear optical response in a silicon photodiode, with which we perform nonlinear autocorrelations that yield information regarding the terahertz temporal profile. Simulations of the spatiotemporal profile agree well with experimental results.
Date: February 15, 2012
Creator: Daranciang, Dan; Goodfellow, John; Fuchs, Matthias; Wen, Haidan; Ghimire, Shambhu; Reis, David A. et al.
Object Type: Article
System: The UNT Digital Library
Workshops on Science Enabled by a Coherent, CW, Synchrotron X-ray Source, June 2011 (open access)

Workshops on Science Enabled by a Coherent, CW, Synchrotron X-ray Source, June 2011

In June of 2011 we held six two-day workshops called "XDL-2011: Science at the Hard X-ray Diffraction Limit". The six workshops covered (1) Diffraction-based imaging techniques, (2) Biomolecular structure from non-crystalline materials, (3) Ultra-fast science, (4) High-pressure science, (5) Materials research with nano-beams and (6) X-ray photon correlation spectroscopy (XPCS), In each workshop, invited speaker from around the world presented examples of novel experiments that require a CW, diffraction-limited source. During the workshop, each invited speaker provided a one-page description of the experiment and an illustrative graphic. The experiments identified by the workshops demonstrate the broad and deep scientific case for a CW coherent synchrotron x-ray source. The next step is to perform detailed simulations of the best of these ideas to test them quantitatively and to guide detailed x-ray beam-line designs. These designs are the first step toward developing detailed facility designs and cost estimates.
Date: January 3, 2012
Creator: Brock, Joel
Object Type: Article
System: The UNT Digital Library
Rational Design of Metal-organic Electronic Devices: a Computational Perspective (open access)

Rational Design of Metal-organic Electronic Devices: a Computational Perspective

Organic and organometallic electronic materials continue to attract considerable attention among researchers due to their cost effectiveness, high flexibility, low temperature processing conditions and the continuous emergence of new semiconducting materials with tailored electronic properties. In addition, organic semiconductors can be used in a variety of important technological devices such as solar cells, field-effect transistors (FETs), flash memory, radio frequency identification (RFID) tags, light emitting diodes (LEDs), etc. However, organic materials have thus far not achieved the reliability and carrier mobility obtainable with inorganic silicon-based devices. Hence, there is a need for finding alternative electronic materials other than organic semiconductors to overcome the problems of inferior stability and performance. In this dissertation, I research the development of new transition metal based electronic materials which due to the presence of metal-metal, metal-?, and ?-? interactions may give rise to superior electronic and chemical properties versus their organic counterparts. Specifically, I performed computational modeling studies on platinum based charge transfer complexes and d10 cyclo-[M(?-L)]3 trimers (M = Ag, Au and L = monoanionic bidentate bridging (C/N~C/N) ligand). The research done is aimed to guide experimental chemists to make rational choices of metals, ligands, substituents in synthesizing novel organometallic electronic materials. Furthermore, the …
Date: December 2012
Creator: Chilukuri, Bhaskar
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Ota-quadrotor: An Object-tracking Autonomous Quadrotor for Real-time Detection and Recognition (open access)

Ota-quadrotor: An Object-tracking Autonomous Quadrotor for Real-time Detection and Recognition

The field of robotics and mechatronics is advancing at an ever-increasing rate and we are starting to see robots making the transition from the factories to the workplace and homes as cost is reduced and they become more useful. In recent years quadrotors have become a popular unmanned air vehicle (UAV) platform. These UAVs or micro air vehicles (MAV) are being used for many new and exciting applications such as aerial monitoring of wildlife, disaster sites, riots and protests. They are also being used in the film industry, as they are significantly cheaper means of getting aerial footage. While quadrotors are not extremely expensive a good system can cost in the range of $3000 - $8000 and thus too costly as a research platform for many. There are a number of cheaper open source platforms. The ArduCopter is under constant development, has the largest community and is inexpensive making it an ideal platform to work with. The goal of this thesis was to implement video processing on a ground control station allowing for the ArduCopter to track moving objects. This was achieved by using the OpenCV video-processing library to implement object tracking and the MAVLink communication protocol, available on the …
Date: May 2012
Creator: Coelho, Gavin
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Fermi LAT Observations of LS 5039 (open access)

Fermi LAT Observations of LS 5039

The first results from observations of the high-mass X-ray binary LS 5039 using the Fermi Gamma-ray Space Telescope data between 2008 August and 2009 June are presented. Our results indicate variability that is consistent with the binary period, with the emission being modulated with a period of 3.903 {+-} 0.005 days; the first detection of this modulation at GeV energies. The light curve is characterized by a broad peak around superior conjunction in agreement with inverse Compton scattering models. The spectrum is represented by a power law with an exponential cutoff, yielding an overall flux (100 MeV-300 GeV) of 4.9 {+-} 0.5(stat) {+-} 1.8(syst) x 10{sup -7} photon cm{sup -2} s{sup -1}, with a cutoff at 2.1 {+-} 0.3(stat) {+-} 1.1(syst) GeV and photon index {Gamma} = 1.9 {+-} 0.1(stat) {+-} 0.3(syst). The spectrum is observed to vary with orbital phase, specifically between inferior and superior conjunction. We suggest that the presence of a cutoff in the spectrum may be indicative of magnetospheric emission similar to the emission seen in many pulsars by Fermi.
Date: March 29, 2012
Creator: Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Axelsson, M.; Baldini, L. et al.
Object Type: Article
System: The UNT Digital Library
Review of lattice studies of resonances (open access)

Review of lattice studies of resonances

None
Date: November 1, 2012
Creator: Mohler, Daniel
Object Type: Article
System: The UNT Digital Library
2013 Plant Lipids Gordon Research Conference and Gordon Research Seminar (January 27-February 1, 2013 - Hotel Galvez, Galveston TX) (open access)

2013 Plant Lipids Gordon Research Conference and Gordon Research Seminar (January 27-February 1, 2013 - Hotel Galvez, Galveston TX)

Presenters will discuss the latest advances in plant and algal lipid metabolism, oil synthesis, lipid signaling, lipid visualization, lipid biotechnology and its applications, the physiological and developmental roles of lipids, and plant lipids in health. Sessions include: Producing Nutritional Lipids; Metabolic biochemistry in the next decade; Triacylglycerols: Metabolism, function, and as a target for engineering; Lipids in Protection, Reproduction, and Development; Genetic and Lipidomic Approaches to Understanding Lipid Metabolism and Signaling; Lipid Signaling in Stress Responses; New Insights on the Path to Triacylglycerols; Membrane Lipid Signaling; Lipid Visualization; Development of Biofuels and Industrial Lipids.
Date: November 1, 2012
Creator: Welti, Ruth
Object Type: Article
System: The UNT Digital Library
Evaluating Use of Satellite Observations for Detecting Large CO2 Leaks and Carbon Sequestration Monitoring (open access)

Evaluating Use of Satellite Observations for Detecting Large CO2 Leaks and Carbon Sequestration Monitoring

None
Date: July 18, 2012
Creator: Brewer, W; Hoffman, G; Silver, E; DiLeonardo, C; Henderson, J R & Vigil, S
Object Type: Report
System: The UNT Digital Library
Distinct Effects of Reduced Sulfur Compounds on Pd-catalytic Hydrodechlorination of TCE in Groundwater Using Cathodic H2 under Electrochemically-induced Oxidizing Conditions (open access)

Distinct Effects of Reduced Sulfur Compounds on Pd-catalytic Hydrodechlorination of TCE in Groundwater Using Cathodic H2 under Electrochemically-induced Oxidizing Conditions

None
Date: June 27, 2012
Creator: Yuan, S.; Chen, M.; Mao, X. & Alshawabkeh, A. N.
Object Type: Article
System: The UNT Digital Library
The Gas That Wouldn't Burn (open access)

The Gas That Wouldn't Burn

Article describing how Alpha Chi Sigma members were involved with the events described on a pictured Kansas historical marker relating to the discovery of helium in a deposit of natural gas.
Date: Summer 2012
Creator: Marshall, James L., 1940- & Marshall, Virginia R.
Object Type: Article
System: The UNT Digital Library
The Hexagon, Volume 103, Number 2, Summer 2012 (open access)

The Hexagon, Volume 103, Number 2, Summer 2012

Quarterly publication of the Alpha Chi Sigma chemistry fraternity containing articles related to chemistry research and the activities of the organization, including local chapters and groups.
Date: Summer 2012
Creator: Alpha Chi Sigma
Object Type: Journal/Magazine/Newsletter
System: The UNT Digital Library
2012 ELECTRONIC PROCESSES IN ORGANIC MATERIALS GORDON RESEARCH SEMINAR, JUNE 2-8, 2012 (open access)

2012 ELECTRONIC PROCESSES IN ORGANIC MATERIALS GORDON RESEARCH SEMINAR, JUNE 2-8, 2012

This meeting focuses on the latest progress and challenges regarding organic electronics devices, artificial light-harvesting systems, and inorganic/organic hybrid nanoscale systems and especially on the synergy between these fields.
Date: June 8, 2012
Creator: Eisele, Dorthe
Object Type: Article
System: The UNT Digital Library
The University News (Irving, Tex.), Vol. 37, No. 21, Ed. 1 Tuesday, April 17, 2012 (open access)

The University News (Irving, Tex.), Vol. 37, No. 21, Ed. 1 Tuesday, April 17, 2012

Weekly student newspaper from the University of Dallas in Irving, Texas that includes campus news and commentaries along with advertising.
Date: April 17, 2012
Creator: unknown
Object Type: Newspaper
System: The Portal to Texas History

Journal of Applied Rehabilitation Counseling, Volume 43, Number 4, Winter 2012

Access: Use of this item is restricted to the UNT Community
Official, quarterly journal of the National Rehabilitation Counseling Association (NRCA) containing articles, opinions, and research in professional rehabilitation counseling regarding the needs of individuals employed in a wide variety of work settings and with wide-ranging professional interests. Author and subject indexes for volume 43 start on page 50.
Date: Winter 2012
Creator: National Rehabilitation Counseling Association (U.S.)
Object Type: Journal/Magazine/Newsletter
System: The UNT Digital Library
Hadronic Vacuum Polarization Contribution to g-2 from the Lattice (open access)

Hadronic Vacuum Polarization Contribution to g-2 from the Lattice

We give a short description of the present situation of lattice QCD simulations. We then focus on the computation of the anomalous magnetic moment of the muon using lattice techniques. We demonstrate that by employing improved observables for the muon anomalous magnetic moment, a significant reduction of the lattice error can be obtained. This provides a promising scenario that the accuracy of lattice calculations can match the experimental errors.
Date: May 1, 2012
Creator: Dru Renner, Xu Feng, Marcus Petschlies, Karl Jansen
Object Type: Article
System: The UNT Digital Library
Observation of Laser Induced Magnetization Dynamics in Co/Pd Multilayers with Coherent X-ray Scattering (open access)

Observation of Laser Induced Magnetization Dynamics in Co/Pd Multilayers with Coherent X-ray Scattering

We report on time-resolved coherent x-ray scattering experiments of laser induced magnetization dynamics in Co/Pd multilayers with a high repetition rate optical pump x-ray probe setup. Starting from a multi-domain ground state, the magnetization is uniformly reduced after excitation by an intense 50 fs laser pulse. Using the normalized time correlation, we study the magnetization recovery on a picosecond timescale. The dynamic scattering intensity is separated into an elastic portion at length scales above 65 nm which retains memory of the initial domain magnetization, and a fluctuating portion at smaller length scales corresponding to domain boundary motion during recovery.
Date: April 5, 2012
Creator: Wu, Benny
Object Type: Article
System: The UNT Digital Library
Coprologic survey of endoparasites from Darwin’s fox (Pseudalopex fulvipes) in Chiloé, Chile (open access)

Coprologic survey of endoparasites from Darwin’s fox (Pseudalopex fulvipes) in Chiloé, Chile

Article on parasite presence in the critically endangered Darwin's fox (Pseudalopex fulvipes) in Chile. Parasites found include species and genera reported for the first time in Darwin's fox.
Date: January 1, 2012
Creator: Jiménez, Jaime E.; Briceño, C.; Alcaíno, H.; Vásquez, P.; Funk, S. & González-Acuña, D.
Object Type: Article
System: The UNT Digital Library