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Stellar Nucleosynthesis: Direct Measurement Of The Neutron-Capture Cross Sections Of Stable Germanium Isotopes And Design Of A Next Generation Ion Trap For The Study Of Beta-Delayed Neutron Emission, Alexander Laminack

LSU Doctoral Dissertations

Knowledge of stellar nuclear reaction rates is critical to understanding the cosmic origins of the abundances of elements. In order to determine these reaction rates, accurate measurements of nuclear cross sections are needed. This thesis presents the results of an experiment to directly measure the neutron capture cross sections of 70-Ge, 72-Ge, 74-Ge, and 76-Ge. These measurements were performed at the Los Alamos Neutron Science CEnter (LANSCE) using the Detector for Advanced Neutron Capture Experiments (DANCE). This is the first direct measurement for many of these isotopes across the neutron energy spectrum of 10 eV to 1 MeV using the …

Nanoscale Colocalization Of Fluorogenic Probes Reveals The Role Of Oxygen Vacancies In The Photocatalytic Activity Of Tungsten Oxide Nanowires, Meikun Shen, Tianben Ding, Steven T. Hartman, Fudong Wang, Christina Krucylak, Zheyu Wang, Che Tan, Bo Yin, Rohan Mishra, Matthew D. Lew, Bryce Sadtler

Electrical & Systems Engineering Publications and Presentations

Defect engineering is a strategy that has been widely used to design active semiconductor photocatalysts. However, understanding the role of defects, such as oxygen vacancies, in controlling photocatalytic activity remains a challenge. Here, we report the use of chemically triggered fluorogenic probes to study the spatial distribution of active regions in individual tungsten oxide nanowires using super-resolution fluorescence microscopy. The nanowires show significant heterogeneity along their lengths for the photocatalytic generation of hydroxyl radicals. Through quantitative, coordinate-based colocalization of multiple probe molecules activated by the same nanowires, we demonstrate that the nanoscale regions most active for the photocatalytic generation of …

Monitoring Of The Radio Galaxy M 87 During A Low-Emission State From 2012 To 2015 With Magic, V. A. Acciari, S. Ansoldi, Juan P. Madrid

Physics & Astronomy Faculty Publications

M87 is one of the closest (z = 0.004 36) extragalactic sources emitting at very high energies (VHE, E > 100 GeV). The aim of this work is to locate the region of the VHE gamma-ray emission and to describe the observed broad-band spectral energy distribution (SED) during the low VHE gamma-ray state. The data fromM87 collected between 2012 and 2015 as part of aMAGIC monitoring programme are analysed and combined with multiwavelength data from Fermi-LAT, Chandra, HST, EVN, VLBA, and the Liverpool Telescope. The averaged VHE gamma-ray spectrum can be fitted from ∼100 GeV to ∼10 TeV with a simple …

Dynamics And Stability Of The Two Body Problem With Yukawa Correction, Eli Cavan, Ioannis Haranas, Ioannis Gkigkitzis

Physics and Computer Science Faculty Publications

We explore the dynamics and stability of the two body problem by modifying the Newtonian potential with the Yukawa potential. This model may be considered a theory of modified gravity; where the interaction is not simply the kepler solution for large distance. The stability is investigated by deriving the Jacobian of the linearized matrix equation and evaluating the eigenvalues of the various equilibrium points calculated during the analysis. The subcases of a purely Yukawa and purely Newtonian potential are also explored.

Non-Tropical Cyclone Related Winter Heavy Rainfall Events Over The Philippines: Climatology And Mechanisms, Lyndon Mark Olaguera, Jun Matsumoto, Julie Mae Dado, Gemma T. Narisma

Physics Faculty Publications

This study investigates non-tropical cyclone (TC) related boreal winter heavy rainfall events that lead to extensive flooding (HRF) over the Philippines through a case study and composite analysis. The HRF event examined occurred during January 16–22, 2017 over Cagayan de Oro City (CDO) in Mindanao Island (122–127°E, 5–10°N). The accumulated rainfall over CDO reached by about 180 mm from 00 UTC January 16 to 00 UTC January 17, 2017, exceeding the climatological maximum daily rainfall in January over this area. The interaction of a westward propagating cyclonic circulation over Mindanao Island (MCC) and a shearline that is associated with an …

Imaging The Stochastic Microstructure And Dynamic Development Of Correlations In Perpendicular Artificial Spin Ice, Susan Kempinger, Robert D. Fraleigh, Paul E. Lammert, Sheng Zhang Zhang, Vincent H. Crespi, Peter Schiffer, Nitin Samarth

Advanced Science Research Center

We use spatially resolved magneto-optical Kerr microscopy to track the complete microstates of arrays of perpendicular anisotropy nanomagnets during magnetization hysteresis cycles. These measurements, along with our statistical methodology, allow us to disentangle the intertwined effects of nearest-neighbor interactions, disorder, and stochasticity on magnetization switching. We find that the nearest-neighbor correlations depend on both interaction strength and disorder. We also find that although the global characteristics of the hysteretic switching are repeatable, the exact microstate sampled is stochastic with the behavior of individual islands varying between nominally identical runs. These protocols provide another way of understanding the relationship between macrohistory …

Dual-Axis Solar Tracker, Bryan Kennedy

All Undergraduate Projects

Renewable energies, and fuels that are not fossil fuel-based, are one of the prolific topics of debate in modern society. With climate change now becoming a primary focus for scientists and innovators of today, one of the areas for the largest amount of potential and growth is that of the capturing and utilization of Solar Energy. This method involves using a mechanical system to track the progression of the sun as it traverses the sky throughout the day. A dual-axis solar tracker such as the one designed and built for this project, can follow the sun both azimuthally and in …

Luminescence Emission In A Nanocrystal Doped By A Transition Metal Impurity, George Chappell Jr.

Theses, Dissertations and Capstones

In this thesis we consider the structure of magnetic ion centers with 3d-electrons in quantum dots under the effects of Coulomb and exchange interaction between the 3d-electrons of the impurity centers and the confined electrons (or holes) existing inside the nanocrystals. In particular, we are interested how this interaction changes the photoluminescence properties of those materials. We will make use of representation theory and the symmetry of the crystal structure to find the orthonormal wave functions that make up the wave functions of the outer, 3d-electrons inside our dot. The Coulomb and exchange interaction …

Performing Near Field Acoustic Holography Scans For The Purpose Of Finding The Acoustic Impedance Of A Violin, Zamara Tomko

Student Research, Papers, and Creative Works

This project aimed to measure the acoustic impedance of the violin so that the violin can be better understood from an acoustic standpoint. Near field acoustic holography scans are to be conducted at the open A string resonance of the violin (440 Hz). Pressure microphones along the back plate of the violin allow pressure and particle velocity to be measured, and with that, the acoustic impedance to be calculated and mapped in 1 cm x 1cm increments. This work presents a guide for this procedure. The set-up method and materials used are detailed and the analysis and computations of values …

Development Of Embedded Atom Method Interatomic Potentials For Ge-Sn-Si Ternary And Constituent Binary Alloys For Modeling Material Crystallization, Sudip Acharya

Browse all Theses and Dissertations

Group IV elements based nanoelectronics devices (mainly Si and Ge based devices) have been developed and improved over a long period of time and are the most influencing materials of semiconductor electronics, but due to their indirect bandgap their use in optoelectronics is limited. Alternatively, new Group IV alloys comprised of Ge, Si, and Sn semiconductor materials have emerged as attractive options for various electronic and optoelectronic applications. The binary and ternary alloys provide strain and energy bandgap engineering by controlling element content, a route for realizing direct-transition semiconductors, improvement in interface and defect properties, and a reduction of the …

Launching A New Dimension With 3d Magnetic Nanostructures, Peter Fischer, Dédalo Sanz-Hernández, Robert Streubel, Amalio Fernández-Pacheco

Robert Streubel Papers

The scientific and technological exploration of three-dimensional magnetic nanostructures is an emerging research field that opens the path to exciting novel physical phenomena, originating from the increased complexity in spin textures, topology, and frustration in three dimensions. One can also anticipate a tremendous potential for novel applications with those systems in a magnetic sensor and information processing technologies in terms of improved energy efficiency, processing speed, functionalities, and miniaturization of future spintronic devices. These three-dimensional structures are distinct from traditional bulk systems as they harness the scientific achievements of nanomagnetism, which aimed at lowering the dimensions down to the atomic …

Examining Artifacts Of The Watershed Segmentation, Emily Jo Armitage

Electronic Theses and Dissertations

The watershed segmentation is an algorithm used to systematically track cell intercalary behaviors during germ band extension of the Drosophila embryo. Neighboring cells share a contracting vertical interface, called a T1, which continues contracting to a single point, a T2, and extending in the horizontal direction to create what is called a T3 interface (Fig. 1). Additionally, higher order vertices called rosettes occur when five or more cells meet at a common vertex. Simulated T2 events demonstrate that cell angle and not noise level in the image contributes to the incorrect detection of artifactual T1s in more acute angled cells …

Gas Adsorption In Carbon Nanohorns: Equilibrium And Kinetics, Justin Matthew Petucci

Electronic Theses and Dissertations

A study of gas adsorption has been carried out with the focus of better understanding the relationships between the individual properties of the adsorbent/adsorbate (e.g. material structure, interactions, gas size and shape, etc.) and the overall adsorptive properties of the combined system (e.g. capacity, binding strength, equilibration time, etc.) as a function of thermodynamical variables. This is useful from the perspective of a comprehensive and fundamental understanding as well as for practical applications. The equilibrium regime of adsorption on carbon nanostructure materials (nanohorns, nanotubes, and graphite) is investigated using molecular statics (MS) and grand canonical monte carlo (GCMC) methods for …

Reflection And Reverberation In Neutron Star Low-Mass X-Ray Binaries, Benjamin Coughenour

Wayne State University Dissertations

Neutron star low-mass X-ray binaries (NS LMXBs) are systems which consist of a NS and a low-mass companion star. They are naturally variable on a variety of timescales, and are even classified by their X-ray spectral variability on the timescales of hours to days. The most luminous NS LMXB sources are known as ‘Z’ sources, because they trace out a characteristic ‘Z’ shape when plotted on a color-color or hardness-intensity diagram. The physical mechanisms causing this variability are not well understood. To try to address this, we model spectra taken from different positions on a hardness-intensity diagram of two Z …

Spectroscopic Study On Pseudomonas Aeruginosa Biofilm In The Presence Of The Aptamer-Dna Scaffolded Silver Nanoclusters, Bidisha Sengupta, Prakash Adhikari, Esther Mallet, Ronald Havner, Prabhakar Pradhan

Faculty Publications

We report the effectiveness of silver nanocluster (Ag-NC) against the biofilm of Pseudomonas aeruginosa (PA). Two DNA aptamers specific for PA and part of their sequences were chosen as templates for growing the Ag-NC. While circular dichroism (CD) studies determined the presence of secondary structures, UV/Vis absorption, and fluorescence spectroscopic studies confirmed the formation of the fluorescent Ag-NC on the DNA templates. Furthermore, mesoscopic physics-based partial wave spectroscopy (PWS) was used to analyze the backscattered light signal that can detect the degree of nanoscale mass density/refractive index fluctuations to identify the biofilm formation, comparatively among the different aptamers with respect …

Predicting Structures Of 2d Materials Enabled By Machine Learning, Sonali Joshi

Honors Undergraduate Theses

Prediction of stable structures of two-dimensional (2D) materials that have not been experimentally realized is an important pre-requisite step for the development of these materials for various technological uses without the extensive trial-error experiments. Traditional methods such as density functional theory (DFT) can be used to find the energies of structures computationally, however, calculating the energies of the total number of structures possible would be daunting timewise as well. We propose using machine learning methods to reduce the search time for 2D materials’ geometric structures. Our case study for this process consists of hexagonal graphene-like boron–carbon–nitrogen (h-BCN). Our …

Holographic Security, Vincent Toal

Books/Book Chapters

This chapter is concerned with the security applications of holographic techniques. Holograms are used in product authentication, product branding and brand protection, and personal and other documents. Serialization to ensure the uniqueness of each hologram for added security is briefly discussed. The theory of optical character recognition and joint transform correlation methods is outlined. Holographic recording using encrypted reference waves enables secure storage of information. Several methods are considered for encrypting optical data as well as holographic recording of encrypted images and their reconstruction and decryption. Millimeter and microwave holographic imaging techniques for the detection of hidden contraband, narcotics, firearms, …

Studies On Secondary Electron Emission Induced Charging In Dielectric Materials: Novel Methods And Applications For Space And Plasma Technologies, Leandro Olano Garcia

Theses and Dissertations

The interaction of ionizing radiation with matter is of critical importance in many areas of science and technology such as space and plasma technology. Secondary electron emission is a direct consequence of electron irradiation on materials. To characterize materials in terms of secondary electron emission, the secondary emission yield (SEY) and the energy spectra of the secondary electrons are key physical properties. Secondary emission yields of materials are usually too high to avoid Multipactor effect or other related phenomena in applications for space. In addition, the measurement of electron energy spectra of secondary electrons in dielectric materials is a challenge …

A Semi-Kinetic Model Of Plasmasphere Refilling Following Geomagnetic Storms And Comparison With Hydrodynamic Results, Kausik Chatterjee, Robert W. Schunk

All Physics Faculty Publications

The objective of this paper is the development of a kinetic model for plasmasphere refilling following geomagnetic storms. The kinetic model is based on the ‘particle-in-cell’ method, a method based on the simulation of particle motion and thus well-suited to high altitude, low-density regimes, where the plasma transport equations are not valid. The model was validated with exact, analytical benchmarks, which are provided in this paper. The refilling results obtained from the kinetic model were then compared with results from a recently developed hydrodynamic solution methodology based on the ‘flux-corrected transport’ (FCT) method, and the limitations of hydrodynamic modeling for …

Inexpensive Fluid Flow Visualization In A Microfluidic Channel Experiment Overview, Maoling Chu

Bridges: A Journal of Student Research

Flow visualization is vital to describe the motion of a fluid in microfluidic channels. This paper summarizes and lists systems based on two common visualization technique categories: particle-based techniques and scalar-based techniques. For this experiment, microfluidic channels were created using PDMS (polydimethylsiloxane). Based on our results and many fabrication trials, it was difficult to say whether this experiment was easy or inexpensive. If the first channel made by the researchers had successfully worked, it would have been clear that utilizing PDMS to fabricate a microfluidic channel for flow visualization was cheap and easy. However, no fully successful microfluidic chips were …

Long-Range Aerosol Transport And Impacts On Size-Resolved Aerosol Composition In Metro Manila, Philippines, Rachel A. Braun, Mojtaba Azadi Aghdam, Paola Angela Bañaga, Grace Betito, Maria Obiminda L. Cambaliza, Melliza Templonuevo Cruz, Genevieve Rose Lorenzo, Alexander B. Macdonald, James Bernard Simpas, Connor Stahl, Armin Sorooshian

Physics Faculty Publications

This study analyzes long-range transport of aerosol and aerosol chemical characteristics based on instances of high- and low-aerosol-loading events determined via ground-based size-resolved aerosol measurements collected at the Manila Observatory in Metro Manila, Philippines, from July to October 2018. Multiple data sources, including models, remote sensing, and in situ measurements, are used to analyze the impacts of long-range aerosol transport on Metro Manila and the conditions at the local and synoptic scales facilitating this transport. Through the use of case studies, evidence of long-range transport of biomass burning aerosol and continental emissions is identified in Metro Manila. Long-range transport of …

Quantification Of Dynamic Epithelial Sheet Architecture In Botryllus Schlosseri Using 2-D & 3-D Image Analysis, Roopa Madhu

Electronic Theses and Dissertations

Epithelial tubules form critical structures in various body tissues; how- ever, since they are difficult to access experimentally, their architecture and dynamics are not well understood. Here we examine the dynamic remodeling of epithelial tubes in vivo using a novel and uniquely accessible model system: the extracorporeal vasculature of Botryllus schlosseri (sea squirt). In Botryllus, massive retraction of blood vessels can be triggered without loss of barrier function, through (i) disrupting collagen crosslinking in the basement membrane using β-aminopropionitrile (BAPN); or (ii) disrupting the integrin pathway through inhibition of focal adhesion kinase (FAK). We performed stereographic projections of 3-dimensional …

Evaluating Thermoelectric Properties Of Batis3 By Density Functional Theory, Tula R. Paudel, Evgeny Y. Tsymbal

Evgeny Tsymbal Publications

BaTiS₃ is a semiconductor with a small bandgap of ∼0.5 eV and strong transport anisotropy caused primarily by structural anisotropy; it contains well-separated octahedral columns along the [0001] direction and low lattice thermal conductivity, appealing for thermoelectric applications. Here, we evaluate the prospect of BaTiS₃ as a thermoelectric material by using the linearized electron and phonon Boltzmann transport theory based on the firstprinciples density functional band structure calculations. We find sizable values of the key thermoelectric parameters, such as the maximum power factor PF = 928 μWK⁻² and the maximum figure of merit ZT = 0.48 for …

Epitaxial Antiperovskite/Perovskite Heterostructures For Materials Design, Camilo X. Quintela, Kyung Song, Ding-Fu Shao, Lin Xie, Tianxiang Nan, Tula R. Paudel, Neil Campbell, Xiaoqing Pan, Thomas Tybell, Mark S. Rzchowski, Evgeny Y. Tsymbal, Si-Young Choi, Chang-Beom Eom

Evgeny Tsymbal Publications

Engineered heterostructures formed by complex oxide materials are a rich source of emergent phenomena and technological applications. In the quest for new functionality, a vastly unexplored avenue is interfacing oxide perovskites with materials having dissimilar crystallochemical properties. Here, we propose a unique class of heterointerfaces based on nitride antiperovskite and oxide perovskite materials as a previously unidentified direction for materials design. We demonstrate the fabrication of atomically sharp interfaces between nitride antiperovskite Mn₃GaN and oxide perovskites (La_0.3Sr_0.7)(Al_0.65Ta_0.35)O₃ and SrTiO₃. Using atomic-resolution imaging/ spectroscopic techniques and first-principles calculations, …

Size And Density Of Upside-Down Jellyfish, Cassiopea Sp., And Their Impact On Benthic Fluxes In A Caribbean Lagoon, Chester B. Zarnoch, Noshin Hossain, Erika Fusco, Mary Alldred, Timothy J. Hoellein, Sophia Perdikaris

School of Global Integrative Studies: Faculty Publications

Anthropogenic disturbances may be increasing jellyfish populations globally. Epibenthic jellyfish are ideal organisms for studying this phenomenon due to their sessile lifestyle, broad geographic distribution, and prevalence in near-shore coastal environments. There are few studies, however, that have documented epibenthic jellyfish abundance and measured their impact on ecological processes in tropical ecosystems. In this study, the density and size of the upside-down jellyfish (Cassiopea spp.) were measured in Codrington Lagoon, Barbuda. A sediment core incubation study, with and without Cassiopea, also was performed to determine their impact on benthic oxygen and nutrient fluxes. Densities of Cassiopea were 24–168 …

Data Analysis Of Large Angle Beamstrahlung Monitor, Samuel Doeg Izaguirre Gamez

Wayne State University Dissertations

The first experimental evidence of large angle beamstrahlung at SuperKEKB is discussed in this Thesis. Beamstrahlung is the tn radiation emitted by particles belonging to one beam when they are accelerated transversely by the electro-magnetic field of the other beam. The properties of the radiation are related to the beam interaction topologyand can be used to optimize the beam-beam collision. This, in turn, makes the machine’s luminosity, and therefore the number of produced events, higher. A device entirely built at WSU, the Large Angle Beamstrahlung Monitor, or LABM, has been deployed in the SuperKEKB accelerator since 2015. A five Institutions …

Visual Storytelling Of Scientific Data: Collaborations Between Physics And Graphic Design In The College Classroom, Eric M. Edlund, Szilvia Kadas

The SUNY Journal of the Scholarship of Engagement: JoSE

The Common Problem Pedagogy (CPP) project, a learning initiative implemented in four SUNY schools, aims to provide students with multidisciplinary, project-based experiences, and to foster a culture of such pedagogy among faculty. This work describes one CPP project that was conducted at SUNY Cortland during the Spring 2019 semester that brought together students from physics and graphic design disciplines. The goal of this project was to identify issues of environmental and social concern, develop numerical models to represent the effects of possible policy actions, and to communicate the meaning of this work as infographics suitable for a non-expert, public audience. …

Exploring Jet Transport Coefficients In The Quark-Gluon Plasma, Amit Kumar

Wayne State University Dissertations

The modifications of hard jets play an essential role as multi-scale probes of the properties of the Quark-Gluon Plasma (QGP) produced in high-energy heavy-ion collisions. In this thesis, we explore the interplay between the soft and hard scales involved in the modification of jet partons as they propagate through the QGP. First, we focus on a regime where the exchanged momenta between the hard parton and the medium are at a high enough scale that QCD perturbation theory can be applied. Based on the assumption that the multiple scatterings inside the plasma are incoherent in the high-energy and high-virtuality phase …

Chiral Magnetism And High-Temperature Skyrmions In B20-Ordered Co-Si, Balamurugan Balasubramanian, Priyanka Manchanda, Rabindra Pahari, Zhen Chen, Wenyong Zhang, Shah R. Valloppilly, Xingzhong Li, Anandakumar Sarella, Lanping Yue, Ahsan Ullah, Pratibha Dev, David A. Muller, Ralph Skomski, George C. Hadjipanayis, David J. Sellmyer

Nebraska Center for Materials and Nanoscience: Faculty Publications

Magnets with chiral crystal structures and helical spin structures have recently attracted much attention as potential spin-electronics materials, but their relatively low magnetic-ordering temperatures are a disadvantage. While cobalt has long been recognized as an element that promotes high-temperature magnetic ordering, most Co-rich alloys are achiral and exhibit collinear rather than helimagnetic order. Crystallographically, the B20-ordered compound CoSi is an exception due to its chiral structure, but it does not exhibit any kind of magnetic order. Here, we use nonequilibrium processing to produce B20-ordered Co_1+xSi_1−x with a maximum Co solubility of x = 0.043. Above a critical …

Effective Field Theory And Machine Learning Approaches To Controlling Nonperturbative Uncertainties In Flavor Physics, Ayesh Gunawardana

Wayne State University Dissertations

The radiative decay $\bar{B}\to X_s\gamma$ and semileptonic heavy meson decay $D\to \pi l \nu$ are important flavor physics probes of new physics. However, these decays are plagued with nonperturbative uncertainties that are needed to be controlled to obtain a theoretically clean description. In this dissertation, we provide effective field theory and machine learning approaches to controlling these uncertainties.\par

In $\bar B\to X_s\gamma$, the largest uncertainty on the total rate and the CP asymmetry arises from resolved photon contributions. These appear first at order $1/m_b$ and are related to operators other than $Q_{7\gamma}$ in the effective weak Hamiltonian. One of the …