Physics Commons^™

Laser Induced Ignition With Resonant Multiphoton Absorption In Oxygen, Steven F. Adams

Physics Seminars

A novel resonant laser-induced breakdown scheme has been demonstrated to provide precision spatial guidance of spark formation within an air flow and has been further demonstrated successfully in resonant laser-induced ignition of a moderate-speed flow of an air-propane mixture. This scheme could potentially provide ignition within a combustion system with a laser trigger leading to breakdown of an air-fuel flow within a high-voltage gap using a compact low power laser source. The laser scheme involves resonant enhanced multiphoton ionization (REMPI) in molecular oxygen and subsequent laser field-enhanced electron avalanche to generate a pre-ionized micro-plasma path between high voltage electrodes and …

A Bioinformatics Method For Identifying Rna Structures Within Human Cells, Stephen Donald Huff

Physics Seminars

Single-stranded, negative-sense RNA (ssRNA-) serves many varied roles within the eukaryotic cell. Currently known examples include snRNA (short nuclear), snoRNA (short nucleolar), tRNA (transfer), siRNA (silencing), miRNA (micro), and others [1,2]. Unknown examples are currently being studied, also, including the long, non-coding ssRNA- found in the nuclear paraspeckle, a component of unknown function located within the eukaryotic nucleus and comprised of ssRNA- sequences transcribed from so-called ‘junk’ DNA [3,4]. While a growing list of confirmed physiological functions have been attributed to ssRNA-, additional roles likely exist and have yet to be discovered. Further, since ssRNA- is known to bind to …

Sapling Learning's Online Homework System For Science Courses, Jon Monahan

Physics Seminars

Created and supported by educators, Sapling Learning’s online homework drives student success and saves educators time.

Passionately Crafted Content: Sapling Learning authors are experienced educators. They are passionate about creating problem sets, targeted instructional feedback, and solutions which both challenge and guide students. Student errors are met with more than just hints. Authors write the same quality, detailed feedback that they would deliver to students in person. Multi-step tutorials and engaging, intuitive question types lead students through a dynamic study process with variation that strengthens comprehensive understanding.

Targeted Instructional Feedback: Every question and tutorial from Sapling Learning is embedded with …

Epistemic Games Analysis Of Common Exam Questions Across Course Formats, Jonathan V. Mahadeo, Adrienne L. Traxler, Eric Brewe

Physics Faculty Publications

This study investigates differences in problem-solving performance between three different introductory physics course formats at Florida International University. The course formats--lecture+laboratory (LL), inquiry-based (IQB), and lecture+laboratory+recitation (LLR)--all incorporated two Advanced Placement (AP) questions into their final exams. Students' written responses were evaluated via an AP scoring rubric, and during this scoring, we observed marked differences in solution behavior between the three course formats. To further investigate these differences, we used the framework of epistemic games to analyze student responses. To apply this framework to written work, an epistemic game rubric was created. Application of this rubric yielded game profiles for …

Characterisation Of Core@Shell Nanoparticles Using Advanced Electron Microscopy, Andrew Wheatley

Special Session 5: Carbon and Oxide Based Nanostructured Materials (2013)

No abstract provided.

Cluster Approach To The Electronic Properties Modeling Of Nanocrystal Structures, Malgorzata Makowska-Janusik, Nathalie Herlin-Boime, Johann Boucle, Abdel Hadi Kassiba

Special Session 5: Carbon and Oxide Based Nanostructured Materials (2013)

No abstract provided.

Photo-Electro-Magnetic Or Photo-Thermo-Magneto-Electric Effects In Graphene?, Marian Nowak, Gregory Kozlowski, B. Solecka, M. Jesionek

Special Session 5: Carbon and Oxide Based Nanostructured Materials (2013)

No abstract provided.

Heating Mechanisms Of Magnetic Nanoparticles In Hyperthermia Treatment, Anna Lukawska, Gregory Kozlowski

Special Session 5: Carbon and Oxide Based Nanostructured Materials (2013)

No abstract provided.

On The Catalyst-Free Fabrication Of Carbon Nanotubes And Graphene, Mark Ruemmeli

Special Session 5: Carbon and Oxide Based Nanostructured Materials (2013)

No abstract provided.

Nano-Objects And Nanochemistry By Selective Atom Diffusion At Advanced Semiconductor Surfaces & Interfaces, Patrick Soukiassian

Special Session 5: Carbon and Oxide Based Nanostructured Materials (2013)

No abstract provided.

Dynamics And Kinetics Of Radicals: Combustion To Multiscale Materials Modeling, Amit R. Sharma

Physics Seminars

Current combustion models have been developed and validated with low-pressure experimental data, and they fail at the high pressures of real devices. The goal of my research is to explore the fundamental effects of high pressure on the chemical kinetics of combustion relevant reactions. This knowledge will be used in the development of accurate models for combustion at the high pressures of current and future engines and novel alternate fuels. Some recent experimental studies of the recombination reactions have demonstrated a second-rise in the rate constant for loss of reactants at very high pressures. It has been speculated that this …

Understanding The Magnetic Ground States For Improper Multiferroic Materials, Jason T. Haraldsen

Physics Seminars

Multiferroic materials have the unique multi-functionality of controlling magnetism through electric field and/or electric polarization through magnetic field, which presents possibilities for new technological advances and applications. To fully understand the connection between magnetism and electric polarization, one must have a full understanding of the underlying magnetic ground states within these materials. Through an investigation of the multiferroic material CuFeO2, I examine the effects of anisotropy and magnetic field on the frustrated triangular lattice and determine the magnetic ground states. Through a rotational algorithm of the Holstein-Primakoff expansion for the spin Hamiltonian, the spin-wave dynamics for the multiferroic and high-magnetic-field …

Exploiting Quantum Phenomena Toward Technological Advancement, Deborah Santamore

Physics Seminars

Technological advancement is often associated with scaling down electronic devices. As the size decreases, quantum phenomena start to govern the device performance. Electron transport through real, and artificial, suspended molecular systems have revealed a rich tapestry of physical effects. Single-molecule electronics offer the promise of observing and controlling quantum effects in massive objects. In addition, the molecules provide the benefit of stronger coupling of vibrational and oscillatory modes to the transport process and a large range of practical applications than traditional nanoelectromechanical systems (NEMS). In this talk, I will discuss the steady-state electronic transport through a suspended dimer molecule transistor. …

Slip Flow Regimes And Induced Fluid Structure In Nanoscale Polymer Films: Recent Results From Molecular Dynamics Simulations, Nikolai V. Priezjev

Physics Seminars

Over the last decade, there has been enormous interest in understanding transport phenomena in micro and nanofluidic systems and, in particular, in accurate prediction of fluid flows with slip boundary conditions at liquid-solid interfaces. In this presentation we will discuss recent results obtained from molecular dynamics simulations of fluids that consist of monomers or linear polymer chains confined by crystalline surfaces. The effects of shear rate and wall lattice orientation on the slip behavior are studied for a number of material parameters of the interface, such as fluid and wall densities, wall-fluid interaction energy, polymer chain length, and wall lattice …

Applied Human Factors Research In Minimally Invasive Surgery, Caroline G. L. Cao

Physics Seminars

Health care is probably the last remaining unsafe critical system. A large proportion of reported medical errors occur in the hospital operating room (OR), a highly complex sociotechnical environment. From the technological point of view, there is a natural progression from traditional open surgery to minimally invasive surgery to robotic surgery. However, technology is being introduced into the OR faster than surgeons can learn to use them. Surgical errors have been attributed to the unfamiliar instrumentation, increased motoric, perceptual and cognitive demands on the surgeons, as well as the lack of adequate training. Effective technology design requires an understanding of …

Quantum Tricks In The Shadows Of Relativity And The Coulomb Force: Teaching Devices And Students How To Think Ultra-Fast, Ilias Perakis

Physics Seminars

The technological demand to bump the Gigahertz switching speed limit of today's magnetic memory and logic devices into the Terahertz regime underlies the entire field of spin-electronics and integrated multi-functional nano-devices. In this talk, I use theory and experiment to show how all-optical switching based on the quantum-mechanical manipulation of spins with a train of laser pulses could meet this challenge. The creation of magnetic correlations within femtoseconds, i.e. faster than one period of lattice oscillations, reveals a new temporal regime of magnetism. This field opened new directions for manipulating materials out-of-equilibrium using Terahertz, Mid-infrared, and X-ray pulses.

Nanocomposite Alloy Design For Power Electronic Applications, Michael Mchenry

Physics Seminars

Recent USDOE workshops highlight the need for advanced soft magnetic materials leveraged in novel designs of power electronic components and systems for power conditioning and grid integration. Similarly soft magnetic materials figure prominently in applications in electric vehicles and high torque motors. Dramatic weight and size reductions are possible in such applications by hold potential for applications in active magnetocaloric cooling of such devices. Bulk and thin film soft magnet sensors can contribute to the search for oil and critical materials. Opportunities for state of the art soft magnetic to impact such applications have been furthered by investment by USDOD …

High-Performance Thermal Management, Kirk Yerkes

Physics Seminars

Traditionally thermal management systems are designed for steady-state behavior. Air Force systems tend to be highly complex, coupled, and highly-dynamic. The concept of high-performance thermal management offers a paradigm shift in the technical approach to thermal management to one that addresses the inherent need to develop thermal management systems. This seminar will address the conceptual and philosophical approach to addressing the science and engineering needed to evolve thermal management technologies for high-performance and rapidly responding thermal management systems.

Growth Of Low-Dimensional Carbon Nanomaterials, John J. Boeckl, Weijie Lu, William Mitchel, Howard Smith, Larry Grazulis, Gerry Landis, Said Elhamri, Kurt G. Eyink

Physics Seminars

Low dimensional carbon nanostructures, carbon nanotubes (CNTs) and graphene, have attracted significant interest due to promising applications ranging from high-speed electronics to sensing. However, insight into growth mechanisms of low-dimensional carbon nanomaterials remains a challenge. Metal-free nanocarbon/SiC structures offer an excellent platform to gain a fundamental understanding of carbon nano-materials. In this talk, metal-free nanocarbon/SiC structures are used as a platform to gain a fundamental understanding of the growth mechanisms of CNTs and graphene. Specifically, an understanding and control of the SiC surface graphitization process and interface structure needs to be established. In this review, we focus on graphene growth …

Enhancing Ir Sensor Coupling Using Surface Plasmon Resonances, John S. Cetnar

Physics Seminars

The mid-infrared (mid-IR) region of the electromagnetic spectrum is defined from λ ~ 8 – 14 μm. There are many important applications for mid-IR sensing including military, scientific, medical, and commercial. Unfortunately, the performance of current mid-IR detectors is limited by low optical absorption. Surface plasmons (SPs) can be used to enhance the coupling between mid-IR radiation and mid-IR detectors. There are many structures that can generate SPs in the mid-IR region. Two particular structures, the grating coupler and the Sierpinski carpet, seem particularly interesting. The grating coupler is of interest because of its good performance and simplicity of fabrication. …

From Solute Transport To Chemical Weathering, Allen Hunt, Thomas E. Skinner

Physics Seminars

A theory for conservative solute transport, based on concepts from percolation theory, is applied directly to reactive solute transport. Chemical reactions are assumed to have reached equilibrium at the scale of an individual pore, but at larger length scales, equilibration is limited by solute transport velocities, which are not the same as fluid velocities! The results of this theory already predicted observed dispersivity values for conservative solute transport over ten orders of magnitude of length scale as well as the variation of solute arrival time distributions with medium saturation. We now show that the solute velocity predicts the time-dependence of …

Electromagnetic Characterization Of Af455 With Dna-Ctma In Solvent Blends, Jessica Marie Hendricks

Browse all Theses and Dissertations

This work studies the electromagnetic properties of AF455, a two photon dye, DNA bound with cetyltrimethyl ammonium (CTMA), in liquid solvent blends for use in thin film optical filters. The liquid properties of the materials are believed to be transferred to the films. The solvent blends used are ratios of toluene (T) and dimethyl sulfoxide (DMSO). The complex permittivity and permeability of the samples are measured using the short open coaxial line technique in the frequency range of 1.0 x 107 Hz to 2.0 x 109 Hz. In this frequency range, AF455 does not act as a two photon absorber. …

Extending Positive Class Results Across Multiple Instructors And Multiple Classes Of Modeling Instruction, Eric Brewe, Adrienne L. Traxler, Jorge De La Garza, Laird H. Kramer

Physics Faculty Publications

We report on a multiyear study of student attitudes measured with the Colorado Learning Attitudes about Science Survey in calculus-based introductory physics taught with the Modeling Instruction curriculum. We find that five of six instructors and eight of nine sections using Modeling Instruction showed significantly improved attitudes from pre- to postcourse. Cohen’s d effect sizes range from 0.08 to 0.95 for individual instructors. The average effect was d = 0.45, with a 95% confidence interval of (0.26–0.64). These results build on previously published results showing positive shifts in attitudes from Modeling Instruction classes. We interpret these data in light …

Compensation In Al-Doped Zno By Al-Related Acceptor Complexes: Synchrotron X-Ray Absorption Spectroscopy And Theory, Jiraroj T-Thienprasert, S. Rujirawat, W. Klysubun, J. N. Duenow, T. J. Coutts, S. B. Zhang, David C. Look, Sukit Limpijumnong

Physics Faculty Publications

The synchrotron x-ray absorption near edge structures (XANES) technique was used in conjunction with first-principles calculations to characterize Al-doped ZnO films. Standard characterizations revealed that the amount of carrier concentration and mobility depend on the growth conditions, i.e. H₂ (or  O₂)/Ar gas ratio and Al concentration. First-principles calculations showed that Al energetically prefers to substitute on the Zn site, forming a donor Al_Zn, over being an interstitial (Al_i). The measured Al K-edge XANES spectra are in good agreement with the simulated spectra of Al_Zn, indicating that the majority of Al atoms …

Capturing And Modeling A Three-Dimensional Stationary Noise Source Directivity Pattern With A Dynamic Array In The Near Field, Randy Mieskoski

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The author has studied several legacy landmark methodologies to develop an original measurement technique. Spherical harmonics modeling practices were leveraged to accurately represent a source directivity pattern. In this thesis a lightweight microphone measurement array that was manually maneuvered around a static noise source was employed. The measurement technique consisted of inserting a head-tracker sensor onto the microphone array to allow the location of the captured acoustic Sound Pressure Level (SPL) to be investigated. By leveraging the historical methodologies the acoustic SPL and location data collected with this technique were processes to represent a directivity pattern of the compressor source …