Digital Commons Network^™

Exploration And Synthesis Of Half-Heusler And Disordered Ternary Intermetallic Single Crystals, Md Fahel Bin Noor

Graduate Theses/Dissertations

Due to their distinct physical and chemical characteristics, half-Heusler compounds are intermetallic materials that have undergone substantial research. The general formula for these compounds is XYZ, where X and Y are transition metals and Z is a p-block element. Thermoelectricity is among the half-Heusler compounds' most exciting potential uses, but additional possible applications include spintronics, magnetic refrigeration, and superconductivity, among others. Recently, half-Heuslers (and Heuslers) have emerged as candidates for catalysts for hydrogenation. The CoNbSn half-Heusler compound, as well as another unique intermetallic ternary compound, the disordered Mn_4-xCr_xAl₁₁, were successfully grown as single crystals …

Synthesis And Characterization Of Cage-Structured Compounds As Promising Thermoelectric Materials, Nusrat Yasmin

Graduate Theses/Dissertations

The development of new thermoelectric materials is of great interest due to their potential to convert waste heat into useful electricity. The primary problem is that the physical factors that are utilized to assess thermoelectric performance conflict with one another. One way to improve their performance is to hinder the lattice from conducting heat through its vibrations while maintaining the heat conduction via the electrons. This can be done by creating cage structures that allow heavy atoms to jiggle. In this study, we report the synthesis of a group of such compounds, using the self-flux method. They all belong to …

On The Gaussian-Core Vortex Lattice Model For The Analysis Of Wind Farm Flow Dynamics, Apurva Baruah

Dissertations, Master's Theses and Master's Reports

Wind power science has seen tremendous development and growth over the last 40 years. Advancements in design, manufacturing, installation, and operation of wind turbines have enabled the commercial deployment of wind power generation systems. These have been due, in a large part, to the expertise in the simulation and modeling of individual wind turbines. The new generation of wind energy systems calls for a need to accurately predict and model the entire wind farm, and not just individual turbines. The commercial deployment of these wind farms depends on model's ability to accurately capture the different physics involved, each at its …

Fabrication And Optical Properties Of Two-Dimensional Transition Metal Dichalcogenides, Manpreet Boora

Dissertations, Master's Theses and Master's Reports

Two-dimensional layered materials such as graphene and transition metal dichalcogenides have gained a lot of attention because of their distinctive chemical, optical, and electronic properties. Transition metal dichalcogenides can have a tunable bandgap in the range of 1 − 3 eV (visible), which enables their applications in ultrathin field effect transistors, photovoltaics, sensors, and optoelectronic devices. They exhibit an indirect-to-direct band gap transition when thinned down from bulk to a single layer. They show strong photoluminescence, electron–photon interaction, valley pseudospin, nonlinear optical response, and lack of dangling bonds. Many exotic phenomena appear when materials are thinned to nanoscale size because …

Physical, Optical, And Chemical Properties Of Light Absorbing Aerosols And Their Climatic Impacts, Susan Mathai

Dissertations, Master's Theses and Master's Reports

Aerosols are particles suspended in the atmosphere; they are emitted during natural phenomena such as dust storms, wildfires, and volcanic eruptions, and during anthropogenic activities like household wood burning, vehicles operations, and industrial productions, or they can form in the atmosphere from gas to particle partition. Aerosols impact earth’s weather and climate by absorbing and scattering the incoming solar and the outgoing earth thermal radiation and interacting with clouds. The optical properties of aerosols evolve as the chemical and physical properties vary during their residence in the atmosphere. In addition, the aerosols’ properties strongly depend on the vertical distribution in …

Large Cloud Droplets And The Initiation Of Ice By Pressure Fluctuations: Molecular Simulations And Airborne In-Situ Observations, Elise Rosky

Dissertations, Master's Theses and Master's Reports

From the molecular dynamics of water molecules to the global processes that control atmospheric circulation: describing the evolution of atmospheric clouds necessitates physics that spans vast spatial scales. In this work, steps are taken towards connecting the molecular physics of ice-nucleation to the growth and subsequent freezing of cloud droplets in convective cumulus clouds. Motivated by experimental evidence of ice nucleation triggered by agitation and distortion of a water droplet surface, the first study in this dissertation uses molecular dynamics simulations to demonstrate that negative Laplace pressure from a curved water surface leads to heterogeneous ice nucleation at higher temperatures. …

An Exploration Of Cloud Droplet Growth By Condensation And Collision-Coalescence In A Convection-Cloud Chamber, Jacob T. Kuntzleman

Dissertations, Master's Theses and Master's Reports

Atmospheric clouds are crucial to weather and climate, and the rate at which droplets collide and coalesce to form precipitation is one of the fundamental controlling processes. The convection-cloud chamber allows the interactions between aerosols and cloud droplets produced by condensation to be investigated within a turbulent environment. Studying the full range of microphysical conditions in atmospheric clouds is not possible, however, unless conditions for droplet growth by collision and coalescence are also achieved. In this study, we explore the conditions favorable to collision-coalescence growth in convection-cloud chambers, extending previous work on steady-state droplet size distributions due to condensation alone. …

Tracing The Most Powerful Galactic Cosmic-Ray Accelerators With The Hawc Observatory, Dezhi Huang

Dissertations, Master's Theses and Master's Reports

Since Victor Hess's groundbreaking detection of cosmic rays in the Earth's atmosphere in 1912, the origins of these charged particles have remained an enduring mystery. Recent studies suggest that these cosmic rays are accelerated beyond Peta electronvolts by powerful astrophysical sources within our own galaxy. While the cosmic rays themselves are being deflected in all directions by magnetic fields, the gamma rays produced by them, being electrically neutral, travel to the observer in a straight line. They carry crucial information, allowing us to trace cosmic-ray accelerators within our galaxy. The High Altitude Water Chrenkov (HAWC) Observatory, located on the slopes …

Diffusion Of Carbon Nanoparticles Intercalated Into Layered Materials, Madelyn Johnson

Honors Program Theses

Using electron beam radiation, as found in a scanning electron microscope, it is possible to induce the local intercalation of carbon nanoparticles into two dimensional layered materials. This technique can be used to form insulating and optically active nanostructures in samples ranging from graphite to BSSCO. In this study, the evolution of these features with time is explored to determine the stability of such nanoparticles in layered materials.

Over the course of days and weeks, the nanostructures created this way broaden and change height. In general, it appears that material buried deep within the layers diffuses upwards to increase the …

Evidence For Kinetic Range Turbulence In The Bryn Mawr Experiment, Carlos A. Cartagena-Sanchez

Bryn Mawr College Dissertations and Theses

No abstract provided.

Experimental Uncertainty In Measurements Of Violin Impulse Response, Andrew Piacsek, Seth Lowery

All Faculty Scholarship for the College of the Sciences

Experiments that investigate how an individual musical instrument changes in response to subtle alterations must contend with measurement uncertainty, which typically arises from inconsistencies in the measurement setup. We quantify uncertainty in violin response measurements by measuring bridge admittance and radiatively of a single instrument that is repeatedly removed and reinstalled in our measurement apparatus. From this set of baseline measurements, we calculate the average and standard deviation of admittance and radiativity. The amount of variation observed in the baseline data is compared to the change in bridge admittance that occurred over several days due to a large and abrupt …

The Lagrangian Formulation For Wave Motion With A Shear Current And Surface Tension, Conor Curtin, Rossen Ivanov

Articles

The Lagrangian formulation for the irrotational wave motion is straightforward and follows from a Lagrangian functional which is the difference between the kinetic and the potential energy of the system. In the case of fluid with constant vorticity, which arises for example when a shear current is present, the separation of the energy into kinetic and potential is not at all obvious and neither is the Lagrangian formulation of the problem. Nevertheless, we use the known Hamiltonian formulation of the problem in this case to obtain the Lagrangian density function, and utilising the Euler-Lagrange equations we proceed to derive some …

Long-Range Aceo Phenomena In Microfluidic Channel, Diganta Dutta, Keifer Smith, Xavier Palmer

Electrical & Computer Engineering Faculty Publications

Microfluidic devices are increasingly utilized in numerous industries, including that of medicine, for their abilities to pump and mix fluid at a microscale. Within these devices, microchannels paired with microelectrodes enable the mixing and transportation of ionized fluid. The ionization process charges the microchannel and manipulates the fluid with an electric field. Although complex in operation at the microscale, microchannels within microfluidic devices are easy to produce and economical. This paper uses simulations to convey helpful insights into the analysis of electrokinetic microfluidic device phenomena. The simulations in this paper use the Navier–Stokes and Poisson Nernst–Planck equations solved using COMSOL …

College Of Natural Sciences 2022 Year-End Publication, College Of Natural Sciences

College of Natural Sciences Newsletters and Reports

This is the 2022 issue of the annual College of Natural Sciences year-end publication.

Contents:
[Page] 2 Dean's message
[Page] 3 Department highlights
[Page] 4 Overview of Bold & Blue Campaign
[Page] 5 Dr. Edward Hogan recognition & endowment
[Page] 6 Career milestones
[Page] 7 Student travel and research
[Page] 8 $11 million COBRE grant
[Page] 9 Professional Science Masters & Research highlights
[Page]10 Outreach highlights throughout the state
[Page] 11 2022 events recap – join us in 2023!
[Page] 12 Updates on our VR initiative
[Page] 14 Overview of awards and recognitions from 2022

Emission Spectroscopy Of Ingaas Quantum Dots Via High-Resolution Fabry-Perot Interferometer, Raju Bhai Kc

Graduate Theses, Dissertations, and Problem Reports (ETD)

Single photons emitted from self-assembled quantum dots have been widely studied to use as a promising qubit for quantum information processing. Therefore, it is critical to fully understand the emission spectra from the quantum dot's excitation if we want to use a single photon as a quantum bit. It is almost impossible to produce rotationally symmetric quantum dots due to various growth conditions and restrictions. So the real quantum dots do not have a perfectly symmetric structure. A broken rotational symmetry causes an asymmetric exchange interaction between electron and hole, leading to a fine structure splitting between two excited states. …

Methods For Analyzing Physics Student Retention And Physics Curricula, John Darrell Hansen

Graduate Theses, Dissertations, and Problem Reports (ETD)

Retention of students in college has been a concern of academic institutions for many years. In the last two decades, the focus on student retention in STEM fields has intensified. The current graduation rate of students in science, technology, engineering and mathematics (STEM) fields is well below that required to fill the projected need of STEM professionals. The work presented in this dissertation investigates the problem of student retention in physics programs. Four studies were performed. The first identifies the relationships between student retention and pre-college and early-college academic factors at an eastern U.S. university using logistic regression and Bayesian …

Discovering And Understanding High Performance Materials Using Density Functional Theory: Quantum Mechanical Simulations And The Consequences Of Symmetry, Olivia M. Pavlic

Graduate Theses, Dissertations, and Problem Reports (ETD)

There are two primary ways that atomic level modeling data is used: materials prediction and understanding materials properties. This dissertation work encom- passes two studies, each of which explore one application. Both studies rely on the highly successful density functional theory (DFT) formalism but differ in that two different implementations of DFT are used on two different high performance materials. The first study on bulk magnesium (Mg) metal alloys explores materials prediction and relies on VASP, a commercially maintained plane-wave DFT code which has been used extensively to successfully study a wide range of materials. [1] The approach used in …

Particle Swarm Optimization For High Rigidity Spectrometer, Yicheng Wang

Honors Theses

The goal of this project is to find reliable parameter settings for a multi-dimensional global optimizer to optimize the performance of a large acceptance ion optical system for the requirements of nuclear physics experiments. We develop and test the Particle Swarm Optimization (PSO), a global optimization algorithm designed for continuous multi-dimensional problems, on a large acceptance particle beam separator, the High Rigidity Spectrometer (HRS) at the Facility for Rare Isotope Beams (FRIB), which is a laboratory specializing in the production and experimental study of short-lived nuclear matter. We split the HRS into two sections, the High-Transmission Beamline (HTBL) and the …

Accurate Oxygen Abundance Of Interstellar Gas In Mrk 71 From Optical And Infrared Spectra, Yuguang Chen, Tucker Jones, Ryan Sanders, Dario Fadda, Jessica Sutter, Robert Minchin, Erin Huntzinger, Peter Senchyna, Daniel Stark, Justin Spilker, Benjamin J. Weiner, Guido Roberts-Borsani

Physics and Astronomy Faculty Publications

The heavy element content (“metallicity”) of the Universe is a record of the total star formation history. Gas-phase metallicity in galaxies, as well as its evolution with time, is of particular interest as a tracer of accretion and outflow processes. However, metallicities from the widely-used electron temperature (Te) method are typically ∼ 2× lower than the values based on the recombination line method. This “abundance discrepancy factor” (ADF) is well known and is commonly ascribed to bias due to temperature fluctuations. We present a measurement of oxygen abundance in the nearby (3.4 Mpc) system, Mrk 71, using a combination of …

Excitation And Ionization Properties Of Star-Forming Galaxies At Z = 2.0-9.3 With Jwst/Nirspec, Ryan L. Sanders, Alice E. Shapley, Michael W. Topping, Naveen Reddy, Gabriel B. Brammer

Physics and Astronomy Faculty Publications

We utilize medium-resolution JWST/NIRSpec observations of 164 galaxies at z = 2.0-9.3 from the Cosmic Evolution Early Release Science (CEERS) survey to investigate the evolution of the excitation and ionization properties of galaxies at high redshifts. Our results represent the first statistical constraints on the evolution of the [O III]/Hβ versus [N II]/Hα, [S II]/Hα, and [O I]/Hα “BPT” diagrams at z > 2.7, and the first analysis of the O₃₂ versus R₂₃ diagram at z > 4 with a large sample. We divide the sample into five redshift bins containing 30-40 galaxies each. The subsamples at z ∼ 2.3, …

Study Of Electronic And Magnetic Properties Of Bilayer Graphene Nanoflakes And Bimetallic Chalcogenides Using First-Principles Density Functional Theory And Machine Learning, Dharmendra Pant

Dissertations, Master's Theses and Master's Reports

Graphene, a one-atom-thick material, has been a wonder material since its discovery because of its superlative electronic, mechanical, and optical properties. When a layer of graphene is rotated over another layer, it exhibits many intriguing behaviors, ranging from superconductivity to the anomalous Hall effect to ferromagnetism at a magic angle of 1°, and hence the twisted bilayer graphene has been the subject of intense research in recent years. The surge in interest in this moiré structure can be attributed to the emergence of electronic flat minibands near the magic angle. Here, we studied the electronic and magnetic properties of twisted …

Integration Host Factor Binds Dna Holliday Junctions, Shawn H. Lin, Dacheng Zhao, Vivian Deng, Veronica K. Birdsall, Suzanne Ho, Olga Buzovetsky, Candice M. Etson, Ishita Mukerji

Physics: Faculty Publications

Integration host factor (IHF) is a nucleoid-associated protein involved in DNA packaging, integration of viral DNA and recombination. IHF binds with nanomolar affinity to duplex DNA containing a 13 bp consensus sequence, inducing a bend of ~160° upon binding. We determined that IHF binds to DNA Four-way or Holliday junctions (HJ) with high affinity regardless of the presence of the consensus sequence, signifying a structure-based mechanism of recognition. Junctions, important intermediates in DNA repair and homologous recombination, are dynamic and can adopt either an open or stacked conformation, where the open conformation facilitates branch migration and strand exchange. Using ensemble …

Editorial: Professional And Scientific Societies Impacting Diversity, Equity And Inclusion In Stemm, Verónica A. Segarra, Candice M. Etson

Physics: Faculty Publications

No abstract provided.

การพัฒนาบล็อกคอนกรีตปูพื้นจากกากของเสียในกระบวนการเผาไหม้แบบฟลูอิไดซ์เบด, ณัฐวรรณ ดวงแก้ว

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้ศึกษาการใช้ประโยชน์เถ้าลอย และทรายของเสีย (ขนาดละเอียดและหยาบ) จากกระบวนการเผาไหม้แบบฟลูอิไดซ์เบดเพื่อนำความร้อนมาใช้ในการอบแห้งในกระบวนการผลิตกระดาษ มาใช้เป็นวัตถุดิบในการเตรียมบล็อกคอนกรีต 2 ประเภทวัสดุ คือ คอนกรีตฐานปูนซีเมนต์ปอร์ตแลนด์ และคอนกรีตฐานจีโอพอลิเมอร์ สำหรับการเตรียมคอนกรีตฐานปูนซีเมนต์ปอร์ตแลนด์ ได้ศึกษาผลของการใช้เถ้าลอยทดแทนส่วนของปูนซีเมนต์ปอร์ตแลนด์ (วัสดุประสาน) และศึกษาอัตราส่วนของทรายของเสีย (มวลรวม) ต่อวัสดุประสาน ที่มีต่อสมบัติของคอนกรีต ขึ้นรูปด้วยวิธีการอัด บ่มชิ้นงานเป็นเวลา 1 7 และ 28 วัน พบว่าตัวอย่างที่มีเถ้าลอยทดแทนปูนซีเมนต์ปอร์ตแลนด์ร้อยละ 15 โดยน้ำหนักของวัสดุประสาน และมีอัตราส่วนของ มวลรวมต่อวัสดุประสาน เท่ากับ 1:1 โดยน้ำหนัก ที่อายุ 7 วัน มีค่ากำลังอัด 45 MPa เป็นไปตามมาตรฐาน มอก.827-2531 นอกจากนั้นยังได้นำส่วนผสมดังกล่าวมาเตรียมบล็อกประสานปูพื้นฐานปูนซีเมนต์ปอร์ตแลนด์ที่มีขนาดและรูปทรงตามมาตรฐานดังกล่าวด้วยเครื่องผลิตบล็อกคอนกรีต พบว่าสามารถเตรียมบล็อกประสานปูพื้นฐานปูนซีเมนต์ปอรต์แลนด์ที่มีเถ้าลอยทดแทนส่วนของปูนซีเมนต์ปอร์ตแลนด์ได้ ในส่วนของการศึกษาความเป็นไปได้ในการผลิตบล็อกฐานจีโอพอลิเมอร์เป็นการทดลองเตรียมจีโอพอลิเมอร์แบบส่วนเดียว โดยใช้เถ้าลอยร่วมกับสารแอลคาไลซึ่งประกอบด้วย โซเดียมซิลิเกตและโซเดียมไฮดรอกไซด์ (วัสดุประสาน) และผสมกับมวลรวมในสัดส่วนของวัสดุประสานต่อมวลรวมเท่ากับ 1:1 เช่นเดียวกับการเตรียมบล็อกคอนกรีตฐานซีเมนต์ ใช้อัตราส่วนผสมน้ำต่อวัสดุประสานเท่ากับ 0.31 ขึ้นรูปด้วยวิธีการอัด โดยศึกษาผลของสัดส่วนของเถ้าลอยต่อสารอัลคาไล และสัดส่วนของโซเดียมซิลิเกตต่อโซเดียมไฮดรอกไซด์ ที่มีต่อสมบัติของคอนกรีต พบว่าชิ้นงานที่ใช้เถ้าลอยร้อยละ 80 โดยน้ำหนักของวัสดุประสาน และใช้สารอัลคาไล (โซเดียมซิลิเกตต่อโซเดียมไฮดรอกไซด์เท่ากับ 60:40 โดยน้ำหนัก) ร้อยละ 20 โดยน้ำหนักของวัสดุประสาน ที่อายุ 28 วัน มีกำลังอัด 5.45 MPa ซึ่งเป็นค่าที่ต่ำกว่าค่าตามมาตรฐาน มอก.827-2531 จึงไม่สามารถใช้ทำบล็อกประสานปูพื้นได้ แต่ค่ากำลังอัดของบล็อกฐานจีโอพอลิเมอร์ก็สูงมากพอสำหรับผลิตบล็อกกลวงไม่รับน้ำหนักตาม มอก.58-2560

High Energy Blue Light Induces Oxidative Stress And Retinal Cell Apoptosis, Jessica Malinsky

Capstone Showcase

Blue light (BL) is a high energy, short wavelength spanning 400 to 500 nm. Found in technological and environmental forms, BL has been shown to induce photochemical damage of the retina by reactive oxygen species (ROS) production. Excess ROS leads to oxidative stress, which disrupts retinal mitochondrial structure and function. As mitochondria amply occupy photoreceptors, they also contribute to oxidative stress due to their selectively significant absorption of BL at 400 to 500 nm. ROS generation that induces oxidative stress subsequently promotes retinal mitochondrial apoptosis. BL filtering and preventative mechanisms have been suggested to improve or repair BL-induced retinal damage, …

Optical Tweezers: Exerting Force With Light, Gabriella Seifert

Scripps Senior Theses

Photons carry momentum. When a tightly-focused beam of photons hit a particle, they transfer some of their momentum to the particle, exerting a force. Optical tweezers take advantage of this phenomenon to trap (or “tweeze”) a spherical bead just after the focus of a diverging laser beam, creating a potential well that pulls in beads. In this thesis, I predict the force exerted on trapped beads and measure the actual force using an optical tweezers setup that I built. To predict the force, I follow the path of all possible rays from a diverging beam incident on a spherical bead …

Delivering Broadband Light Deep Into Diffusive Media, Rohin Mcintosh, Nicholas Bender, Alexey Yamilov, Arthur Goetschy, Chia Wei Hsu, Hasan Yilmaz, Hui Cao

Physics Faculty Research & Creative Works

Waves propagate diffusively through disordered media, such as biological tissue, clouds, and paint, due to random scattering. Recent advances in optical wavefront shaping techniques have enabled controlling coherent light propagation in multiple-scattering samples. We overcome wave diffusion to deliver optical energy into a target region of arbitrary size and shape anywhere inside a strong-scattering system. This is particularly important for applications such as photoacoustic microscopy and optogenetics, where light needs to be deposited deep into biological tissue. For monochromatic light, we previously introduced the deposition matrix (DM) Z(ω), which maps its input wavefront to the field distribution in the target …

Solitons And Their Applications In Physics, B. A. Yount

EWU Masters Thesis Collection

No abstract provided.

Compact And High Optical Efficiency Near-Eye Displays With Liquid Crystal Flat Optics, Junyu Zou

Electronic Theses and Dissertations, 2020-2023

Since the concepts of augmented reality (AR) and virtual reality (VR) were introduced, they have attracted people's attention worldwide, both in the industry and research areas. As the most promising hardware architecture that can bring AR/VR into daily life, near eye displays (NEDs) have been studied and investigated heavily over the past half-century, especially the concept of "Metaverse" introduced by some top companies in recent years. However, the form factor and optical efficiency are two major bottlenecks for the current NEDs before they can become the major platform. Liquid crystal (LC) flat optics have several advantages, including compact, high diffraction …

ℼ± -,ℼ0-Meson Electroweak Decays Within Relativistic Quark Model Based On Point Form Of Poincaré-Invariant Quantum Mechanics, Vadzim Haurysh, Viktor Andreev

Turkish Journal of Physics

In the course of work the integral representation of ℼ⁰-meson form-factor of ℼ⁰ → γγ process has been obtained within relativistic quark model based on point form of Poincaré-invariant quantum mechanics taking into account anomalous magnetic moments of κ_υ and κ_ⅾ quarks. The parameters obtained using pseudoscalar density constant g_ℼ± , current masses of υ- and ⅾ-quarks as well as decay constant ℼ^± → ℓ^±_νℓ were used for numerical modeling of F_ℼ0γ(t) form-factor in time-like region. Similar calculations for ℼ⁰ → γγ decay characteristics with reference to quark …