Physics Commons^™

Study Of The Etaprimepi0 System In Gluex, Rupesh Dotel

FIU Electronic Theses and Dissertations

The η′π is an important decay channel for the potentially exotic hybrid meson π1(1600) that has been detected in the COMPASS, VES and E852 experiments. These previous experiments used a charged pion beam as a probe. In contrast, the GlueX experiment is designed to search for the exotic hybrid mesons using a linearly polarized photon beam. This thesis project analyzes the η′π0 system produced in GlueX by the reaction γp → η′π0p. After optimizing the event selection to minimize background contributions, a mass independent partial wave analysis is performed in search of an exotic signature. Within the currently available statistical …

The Role Of Conformational Changes In Viral And Bacterial Protein Functions, Md Lokman Hossen

FIU Electronic Theses and Dissertations

Proteins do versatile work in cells. They require a cascade of structural changes to perform different tasks like binding to the other neighboring biomolecules, transporting small chemicals, activating a chemical reaction, etc. The structural conformations of proteins can be critical in changing their working ability. In this dissertation, I investigated the role of conformational changes of viral protein, e.g., spike and envelope protein of SARS-CoV-2, and bacterial protein, e.g., multidrug transporter and toxic extrusion protein- PfMATE from Pyrococcus furiosus. Also, I performed molecular docking-based drug screening targeting the E protein to suggest a set of drugs that can be repurposed …

The Valence Quark Structure Of The Nucleon, Christopher A. Leon

FIU Electronic Theses and Dissertations

The nucleon is a composite object, formed from a sea of quarks, anti-quarks and gluons being continuously created and annihilated. Among this complexity, however, there are three valence quarks that give the nucleon its baryon and flavor numbers. Here we investigate the dynamical structure of valence quarks inside the nucleon. The primary tool used will be patron distribution functions (PDFs), which give the distribution of momentum fraction, x, of the quarks and gluons inside the nucleon. By examining the PDFs of the valence quarks from phenomenological fits, we derive a new model-independent relation of PDF peaks and connect it to …

Many-Body Effects In Atomic Ensembles Probed By Optical Two-Dimensional Coherent Spectroscopy, Danfu Liang

FIU Electronic Theses and Dissertations

Quantum information science provides humankind with post-Moore era technology and advanced principles and methods in the development of information science. Implementing practical quantum simulations through many-body quantum systems is a fundamental goal in quantum information science. Therefore, the demand for the achievement of quantum information processing devices inevitably requires the study of the many-body effect in the multi-atom system. Due to the transition-induced dipole moment, neutral atoms can interact without a permanent dipole moment. The interaction plays an essential role in many-body effects, such as energy shifts and changes in dephasing rates. In addition, its long-range nature has confirmed the …

In Silico Identification Of Vaccine Candidates Against Viral Infections, Prabin Baral

FIU Electronic Theses and Dissertations

There are many viral diseases without effective treatments or vaccines. These viruses can cause catastrophic epidemics such as the Lassa, Ebola, and Marburg viruses. Similarly, the recent coronavirus pandemic is of great concern as new variants are continuously emerging with decreased susceptibility to antibodies and vaccines that were developed for earlier strains. A critical step in the immune system’s fight against viruses involves an immunological protein molecule binding to a viral protein molecule. I investigate the atomic and molecular details of binding site recognition and binding interactions and dynamics for three important viruses.

Antigens are molecules, such as viral proteins, …

Temperature Dependent Protein-Chromophore Hydrogen Bond Dynamics In The Far-Red Fluorescent Proteins By Using Molecular Dynamics Simulation And Quantum Calculationtemperature Dependent Protein-Chromophore Hydrogen Bond Dynamics In The Far-Red Fluorescent Proteins By Using Molecular Dynamics Simulation And Quantum Calculation, Chandra Prasad Dhakal

FIU Electronic Theses and Dissertations

Fluorescent proteins are valuable tools as biochemical markers in molecular and cell biology research for studying cellular processes. Red Fluorescent Proteins (RFPs) are highly desirable for in vivo applications in living cell imaging because they absorb and emit light in the red region of the spectrum where cellular autofluorescence. Naturally occurring fluorescent proteins with emission peaks in this region of the spectrum occur in dimeric or tetrameric forms. For their use as biochemical markers, several monomeric variants of RFP have been developed which include mCherry, dsRed, and mStrawberry. Far red-emitting FPs with large Stokes shift are especially valuables for in …

Optical Two-Dimensional Coherent Spectroscopy Of Many-Body Dynamics In Quantum Materials, Maria Fernanda Munoz

FIU Electronic Theses and Dissertations

Since the rise of the concept of quantum materials (QM), these materials described as many-body quantum systems (interacting atoms, molecules, or electrons) have been suitable for many optoelectronic and quantum applications. Additionally, there has been significant interest in the research of QM to understand the underlying physics behind their extraordinary optical properties. Examples of QM are ultracold atoms, layered 2D semiconductors, supramolecular materials, and more. In 2012, a high energy conversion efficiency of over 10% was reported for the first time for metal-halide perovskite (MHP) solar cells, opening a new era for photovoltaics research. The reported efficiencies have been improved …

Probing The Structure Of Deuteron At Very Short Distances, Frank Vera

FIU Electronic Theses and Dissertations

We study the electro-disintegration of deuteron at quasi-elastic kinematics and high transferred momentum as a probe for the short distance structure in nuclei. In this reaction, an electron hits a nucleus of deuterium, which breaks up into a pair of nucleons (proton-neutron). We focus our attention on events where fast nucleons emerge, corresponding to nuclear configurations where the bound nucleons have a high relative momentum (exceeding 700 MeV/c). The present research is relevant to physical systems where high-density nuclear matter is present. This condition covers a wide range of physics, from neutron stars to nuclei stability and the repulsive nuclear …

A Study Of Magnetism And Possible Mixed-State Superconductivity In Phosphorus-Doped Graphene, Julian E. Gil Pinzon

FIU Electronic Theses and Dissertations

Evidence of superconducting vortices, and consequently mixed-state superconductivity, has been observed in phosphorus-doped graphene at temperatures as high as 260 K. The evidence includes transport measurements in the form of resistance versus temperature curves, and magnetic measurements in the form of susceptibility and magnetic Nernst effect measurements. The drops in resistance, periodic steps in resistance, the appearance of Nernst peaks and hysteresis all point to phosphorus-doped graphene having a broad resistive region due to flux flow as well as a Berezinskii-Kosterlitz-Thouless (BKT) transition at lower temperatures.

The observation of irreversible behavior in phosphorus-doped graphene under the influence of a thermal …

Structural Dynamics Of Membrane Interacting Viral Proteins, Nisha Bhattarai

FIU Electronic Theses and Dissertations

Viruses do not possess complete cellular machinery but have the ability to reproduce by utilizing cellular machinery inside host cells. They are nanoscale machines that rapidly modify (evolve) their molecular components to cause disease and death. Therefore, emergence of deadly infectious viruses is a monumental health concern and understanding how viruses are able to enter, replicate, assemble and egress from the host cell is important to mitigate the threat.

A fully active, infectious viral structure is known as a virion. A virion contains genetic material and is enclosed by a capsid. The capsid is a protein shell and some viruses …

Electron Field Emission And Electrochemical Lithiation Properties Of Vertically Aligned Carbon Nanotube Arrays Grown Directly On Metal Substrates, Arun Thapa

FIU Electronic Theses and Dissertations

Carbon nanotubes (CNTs) represent one of the critical inventions that have triggered new science and technology in many fields because of their distinctive mechanical, thermal, electrical, electrochemical, and optical properties. Despite the tremendous potential of CNTs, challenges in synthesizing and processing continue to hinder their applications. This dissertation is devoted to synthesizing vertically aligned CNT arrays on metal substrates via plasma-enhanced chemical vapor deposition and the study of their electron field emission (FE) and electrochemical lithiation properties.

Vertically aligned CNTs (VACNTs) are promising electron field emitters for vacuum micro/nano-electronics. Improved control over the morphology and a successful direct-growth of the …

Photo-Production Of Eta Mesons, Mahmoud Mohamed Kamel

FIU Electronic Theses and Dissertations

In this work we present the GlueX experiment extensive high statistics measurements of the η meson photo-production differential cross sections at beam energies between 3 GeV and 11.6 GeV. We compared the low energy (2.9 GeV< Eγ < 5.9 GeV) differential cross section (dσ/dΩ) results to previous experimental results from the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) collaboration. These (dσ/dΩ) results are also compared to the theoretical isobar model EtaMAID2018 by Tiator et. al., and the Regge model by Nys et. al. The differential cross section dσ/dt is also presented and compared to the previous experimental results, and to the above models, in addition to a model by J. M. Laget. The high energy (6.2 GeV< Eγ < 11.6 GeV) cross section results (dσ/dΩ, and dσ/dt) are compared to the isobar model EtaMAID2018. These results will provide new constraints on η photo-production mechanisms and high energy t- channel processes.

Organic-Inorganic Halide Perovskite Nanocrystals And Solar Cells, Rui Guo

FIU Electronic Theses and Dissertations

A great challenge facing humanity in the 21^st century is finding inexhaustible and inexpensive energy sources to power the planet. Renewable energies are the best solutions because of their abundance, diversity, and pollution-free emission. Solar energy is the cleanest and most abundant renewable energy source available. In the continuing quest for efficient and low-cost solar cells, perovskite solar cells (PSCs) have emerged as a potential replacement for silicon solar cells. Since 2009, the record efficiencies of PSCs have been skyrocketing from 3.8 % to 25.2 % and are now approaching the theoretical limit. Along with the three-dimensional perovskites used …

Surface-Enhanced Raman Spectroscopy For Single Molecule Analysis And Biological Application, Jing Guo

FIU Electronic Theses and Dissertations

Surface-enhanced Raman spectroscopy (SERS) is a surface analytical technique, which enhances the Raman signal based on the localized surface plasmon resonance (LSPR) phenomenon. It has been successfully used for single molecule (SM) detection and has extended SERS to numerous applications in biomolecular detection. However, SM detection by SERS is still challenging especially with traditional SERS substrates and detection methods. In addition, the fundamental understanding of the SERS enhancement mechanism is still elusive. Furthermore, the application of SERS in biological field is still in the early stage. To address these challenges, there are two main aspects of SERS studied in my …

Investigations Of Cell-Penetrating And Membrane-Pore Forming Peptides, Rudramani Pokhrel

FIU Electronic Theses and Dissertations

Cell-penetrating and membrane-pore forming peptides are a class of membrane-active peptides. They are short sequence peptides having both hydrophilic and lipophilic combinations of amino acids. These peptides can have contrast functional diversity. Peptides encoded by viruses function as viroporins and play a critical role in viral replication, propagation, and pathogenesis. One such peptide is the Ebola virus delta peptide, which forms a pore in the host cell membrane. Another set of pore-forming peptides are antimicrobial Lantibiotic peptides that may be useful for killing antibiotic resistant bacteria by disrupting the bacterial membrane through two different possible mechanisms. Not only can they …

Cross Section Measurements Of Deuteron Electro-Disintegration At Very High Recoil Momenta And Large 4-Momentum Transfers (Q2), Carlos Yero

FIU Electronic Theses and Dissertations

The ²H(e,e′p)n cross sections have been measured at negative 4-momentum transfers of Q² = 4.5±0.5 (GeV/c)² and Q² = 3.5±0.5 (GeV/c)² reaching neutron recoil (missing) momenta up to p_r ∼1.0 GeV/c. The data have been obtained at fixed neutron recoil angles 5^o ≤ θ_nq ≤ 95^o with respect to the 3-momentum transfer q. The new data agree well with the previous data which reached p_r ∼ 500 MeV/c. At θ_nq = 35^o and 45^o, final state interactions (FSI), meson exchange currents (MEC) and isobar configurations (IC) …

Multifunctional Nanopipette For Single Nanoparticles And Proteins Analysis, Popular Pandey

FIU Electronic Theses and Dissertations

Complex biological processes occur in the nanoscale (1-100 nm) regime. ‘DNA’ which is just 2 nm in dimension is a fundamental building block of all life. ‘Hemoglobin’, a blood protein that transports oxygen throughout our body is only 5 nm in diameter. Importantly, the structure, composition, and dynamics of these nanoscale entities determine their biological function. A slight alteration in the structure and composition can lead to the malfunction of the protein which is key to various diseases including cancer. Therefore, the single-molecule measurement approach is essential to characterize both the average properties and the rare …

The Impacts Of Small Group Interactions And Social Interdependence In Introductory Physics, Miguel Angel Rodriguez Velazquez

FIU Electronic Theses and Dissertations

The collected works in my dissertation are centered around the dynamics and impacts of small group learning in introductory physics. It is motivated by a desire to better understand which classroom practices and learning processes may lead to students achieving greater understanding or affinity to physics. Several theoretical frameworks are leveraged in my work including physics identity theory, social interdependence theory and social metacognition. The research design employed quantitative and qualitative methods including regression analysis, descriptive statistics, and observational analysis.

Firstly, students across the U.S. enrolled in first semester introductory physics courses were surveyed at the beginning and end of …

Charged Fusion Product Plasma Diagnostics In Spherical Tokamaks, Alexander Netepenko

FIU Electronic Theses and Dissertations

Charged fusion products from the D(d,p)t reaction, protons (p) and tritons (t), can be detected to obtain time and position dependent information on the fusion reaction profile in plasmas heated with neutral particles beams. We have developed a prototype instrument consisting of charged particle detectors with ion-implanted-silicon surface barrier detectors. Each detector is combined with two replaceable collimators in such a way that it can accept protons and tritons emitted from a well-defined area inside the plasma. The detectors thus provide curved views across the plasma volume.

Combining the data of all six detectors allows one to study changes in …

Impact Of Out-Of-Class Science And Engineering Activities On Physics Identity And Career Intentions, Robynne M. Lock, Zahra Hazari, Geoff Potvin

Department of Teaching and Learning

The number of physics bachelor’s degrees that are awarded in the United States annually is small compared to most other science, technology, engineering, and mathematics fields, and only about one-fifth of these degrees are awarded to women. Understanding the influence of students’ science and engineering experiences on career choices is critical in order to improve future efforts to increase the number of physics majors and the participation of women. In this work, we use a physics identity framework to examine the impact of out-of-class science and engineering activities on three identity dimensions and the relationship between these dimensions and physics …

Numerical Determination Of Monopole Scaling Dimension In Parity-Invariant Three-Dimensional Noncompact Qed, Nikhil Karthik, Rajamani Narayanan

Department of Physics

We present a direct Monte Carlo determination of the scaling dimension of a topological defect operator in the infrared fixed point of a three-dimensional interacting quantum field theory. For this, we compute the free energy to introduce the background gauge field of the Q=1 monopole-antimonopole pair in three-dimensional noncompact QED with N=2, 4 and 12 flavors of massless two-component fermions, and study its asymptotic logarithmic dependence on the monopole-antimonopole separation. We estimate the scaling dimension in the N=12 case to be consistent with the large-N (free fermion) value. We find the deviations from this large-N value for N=2 and 4 …

Understanding The Importance Of Graduate Admissions Criteria According To Prospective Graduate Students, Deepa Chari, Geoff Potvin

Department of Physics

Understanding perceptions of graduate admissions from multiple stakeholders can cultivate an improved understanding about the process of graduate induction, the role that admissions plays in restricting diversity in physics, and contribute to more informed practices for all involved. Prior studies in graduate admissions have reported on how certain admission criteria weigh in the consideration of applicants primarily from faculty perspectives. Motivated by the concept of multivocal knowledge, in this article, we report on prospective students’ perspectives of the importance of the same admission criteria—a stakeholder group that is critical but underempowered in the admissions process. We identify a substantial agreement …

Qcd Evolution Of Superfast Quarks, Adam J. Freese, Wim Cosyn, Misak M. Sargsian

Department of Physics

Recent high-precision measurements of nuclear deep inelastic scattering at high x and moderate 6superfast region, in which the momentum fraction of the nucleon carried by its constituent quark is larger than the total fraction of the nucleon at rest, x>1. We derive the leading-order QCD evolution equation for such quarks with the goal of relating the moderate-Q2 data to the two earlier measurements of superfast quark distributions at large 601.1 region is somewhat in the middle of the neutrino-nuclear and muon-nuclear scattering data.

Lz-101, A Novel Derivative Of Danofloxacin, Induces Mitochondrial Apoptosis By Stabilizing Foxo3a Via Blocking Autophagy Flux In Nsclc Cells, Yongjian Guo, Yue Zhao, Yuxin Zhou, Xiaoqing Tang, Zhiyu Li, Xiaotang Wang

Department of Chemistry and Biochemistry

Non-small-cell lung carcinoma (NSCLC) continues to be a vital disease worldwide for its high incidence and consequent mortality rate. In this study, we investigated the anti-cancer effect of LZ-101, a new derivative of danofloxacin, against non-small-cell lung cancer and the underlying mechanisms. In vitro, LZ-101 inhibited the viability of human non-small cell lung cancer cell lines. We demonstrated that LZ-101 induced mitochondrial-mediated apoptosis by increasing Bax/Bcl-2 ratio, loss of mitochondrial membrane potential (ΔΨm), release of cytochrome c (Cyt c) and apoptosis-inducing factor (AIF) in A549 cells. Further research illuminated that LZ-101 induced apoptosis was related to the …

Automated, Efficient, And Accelerated Knowledge Modeling Of The Cognitive Neuroimaging Literature Using The Athena Toolkit, Michael C. Riedel, Taylor P. Salo, Jason Hays, Matthew D. Turner, Matthew T. Sutherland, Jessica A. Turner, Angela Laird

Department of Physics

Neuroimaging research is growing rapidly, providing expansive resources for synthesizing data. However, navigating these dense resources is complicated by the volume of research articles and variety of experimental designs implemented across studies. The advent of machine learning algorithms and text-mining techniques has advanced automated labeling of published articles in biomedical research to alleviate such obstacles. As of yet, a comprehensive examination of document features and classifier techniques for annotating neuroimaging articles has yet to be undertaken. Here, we evaluated which combination of corpus (abstract-only or full-article text), features (bag-of-words or Cognitive Atlas terms), and classifier (Bernoulli naïve Bayes, k-nearest …

Sexual Harassment Reported By Undergraduate Female Physicists, Lauren M. Aycock, Zahra Hazari, Eric Brewe, Kathryn B.H. Clancy, Theodore Hodapp, Renee Michelle Goertzen

Department of Physics

Sexual harassment occurs more frequently in male-dominated fields and physics is a more male-dominated field than most other science, technology, engineering, and mathematics (STEM) fields. Thus, it is important to examine the occurrence and impact of sexual harassment on women in physics. A survey of undergraduate women, who attended a conference for undergraduate women in physics, revealed that approximately three quarters (74.3%; 338/455) of survey respondents experienced at least one type of sexual harassment. This sample was recruited from a large fraction of undergraduate women in physics in the United States. We find that certain types of sexual harassment predict …

Coherent And Incoherent Dynamics Of Quasiparticles In Monolayer Molybdenum Diselenide, Michael Titze

FIU Electronic Theses and Dissertations

Monolayer Materials, especially single-layer graphite, called graphene, as the first synthesized and most prominent representative, have attracted significant research interest since its discovery in 2004. The efforts were rewarded with a Nobel prize in 2010 for the discovery of graphene, the same year in which the first monolayer transition metal dichalcogenide (ML-TMD) was found to have a direct bandgap. In contrast to graphene ML-TMDs have a direct bandgap in the visible or near-infrared spectral range, making them ideally suited for optoelectronic device applications. Explicit inversion symmetry breaking of the unit cell in ML-TMDs furthermore leads to a new interesting property, …

Exploring The Neural Mechanisms Of Physics Learning, Jessica E. Bartley

FIU Electronic Theses and Dissertations

This dissertation presents a series of neuroimaging investigations and achievements that strive to deepen and broaden our understanding of human problem solving and physics learning. Neuroscience conceives of dynamic relationships between behavior, experience, and brain structure and function, but how neural changes enable human learning across classroom instruction remains an open question. At the same time, physics is a challenging area of study in which introductory students regularly struggle to achieve success across university instruction. Research and initiatives in neuroeducation promise a new understanding into the interactions between biology and education, including the neural mechanisms of learning and development. These …

Polarization Observables For Γp −> K+Λ At Photon Energies Up To 5.45 Gev, Shankar Dayal Adhikari

FIU Electronic Theses and Dissertations

Excited nucleon states are established as an important milestone to understand quantum chromodynamics in the non-perturbative region. Even after decades of study, not all of the excited states predicted by different theoretical approaches have been verified. The disparity between the predicted states and the verified states is known as the “missing baryon problem". The verified states were mostly established using pion beam data or through Nπ decay channels, but are not sufficient to address the missing baryon problem. In recent years, new experiments were conducted worldwide at CLAS in Jefferson Lab, ELSA in Bonn, MAMI in Mainz, and so on, …

Qcd Process In Few Nucleon Systems, Dhiraj Maheswari

FIU Electronic Theses and Dissertations

One of the important issues of Quantum Chromodynamics (QCD) - the fundamental theory of strong interaction, is the understanding of the role of the quark-gluon interactions in the processes involving nuclear targets. One direction in such studies is to explore the onset of the quark gluon degrees of freedom in nuclear dynamics. The other direction is using the nuclear targets as a “micro-labs” in studies of the QCD processes involving protons and neutrons bound in the nucleus. In the proposed research, we work in both directions considering high energy photo- and electro-production reactions involving deuteron and 3 He nuclei.

In …