Physics Commons^™

A Review On Antibacterial Activity Of Nanoparticles, Badr-Edine Sadoq, Mohammed Reda Britel, Adel Bouajaj, Ramzi Maâlej, Ahmed Touhami, Marwa Abid, Hanen Douiri, Fakhita Touhami, Amal Maurady

Physics and Astronomy Faculty Publications and Presentations

The increasing resistance of bacteria to antibiotic agents is a main global public health problem. The use of nanoparticles is one of the promising ways to overcome microbial resistance to antimicrobial agents. Metal nanoparticles are increasingly used to target bacterial strains. Advances in nanotechnology, in particular the ability to synthesize nanoparticles of specific size and shape, are likely to lead to the development of new antibacterial agents. The antibacterial activities of nanoparticles are largely influenced by their sizes and large surface area/mass ratio. The antibacterial mechanisms of nanoparticles are poorly understood, but the currently accepted mechanisms include oxidative stress induction, …

Signatures Of Black Holes, Alexandra B. Chanson

All Graduate Theses and Dissertations

In this defense I will describes three approaches to learn more about the relationship between the dynamics of black-holes and the distinctive signatures of a black hole systems: infinitesimal changes in the black hole background producing field excitations relating new fundamental black hole thermodynamic relations, mechanisms powering relativistic black hole jets and spontaneous symmetry breaking in five space-time dimensions, and physical signatures of black hole event horizons as conformal field theory duals (in both d=4,5 dimensional axisymmetric spacetimes).

Spectral Broadening Effects On Pulsed-Source Digital Holography, Steven A. Owens, Mark F. Spencer, Glen P. Perram

Faculty Publications

Using a pulsed configuration, a digital-holographic system is setup in the off-axis image plane recording geometry, and spectral broadening via pseudo-random bit sequence is used to degrade the temporal coherence of the master-oscillator laser. The associated effects on the signal-to-noise ratio are then measured in terms of the ambiguity and coherence efficiencies. It is found that the ambiguity efficiency, which is a function of signal-reference pulse overlap, is not affected by the effects of spectral broadening. The coherence efficiency, on the other hand, is affected. As a result, the coherence efficiency, which is a function of effective fringe visibility, is …

The Influence Of Allostery Governing The Changes In Protein Dynamics Upon Substitution, Joseph Hess

All Dissertations

The focus of this research is to investigate the effects of allostery on the function/activity of an enzyme, human immunodeficiency virus type 1 (HIV-1) protease, using well-defined statistical analyses of the dynamic changes of the protein and variants with unique single point substitutions ¹. The experimental data¹ evaluated here only characterized HIV-1 protease with one of its potential target substrates. Probing the dynamic interactions of the residues of an enzyme and its variants can offer insight of the developmental importance for allosteric signaling and their connection to a protein’s function. The realignment of the secondary structure elements can …

The Derivation Of Sodium Density In The Mesosphere And Lower Thermosphere From The Na Lidar Photon Counting Profiles, Xiaoqi Xi

All Graduate Theses and Dissertations

Derivation of Sodium (Na) number density from the Na lidar observations requires the in situ temperature and wind information because the absorption cross-section of the Na atom is a function of these dynamic parameters. The Na number density above ~ 110 km altitude was difficult to derive with the conventional algorithm, however. The standard output of the Na number density that utilizes the lidar-measured wind and temperature information falls short at ~ 110 km altitude and above due to the relatively large measurement uncertainties in the two critical parameters (low signal-to-noise ratio). Therefore, an innovative algorithm that may drive the …

Enhanced Acousto-Optic Properties Of Silicon Carbide Based Layered Structure, Namrata Dewan Soni

Al-Bahir Journal for Engineering and Pure Sciences

This study investigates the feasibility of using silicon carbide-based layered surface acoustic wave (SAW) devices in acousto-optic applications. The acousto-optic properties of the temperature-stable layered structure TeO3/SiC/128oY-X LiNbO3 are investigated through theoretical analysis. This analysis includes the evaluation of key parameters such as the overlap integral, figure of merit, and diffraction efficiency. The SAW propagation characteristics and field profiles required for these calculations are obtained using SAW software. Results show that the layered structure has high diffraction efficiency of nearly 96% and a promising value for the acousto-optic figure of merit, indicating potential use in low driving power acousto-optic devices. …

Entanglement In The Hawking Effect: From Astrophysical To Optical Black Holes, Dimitrios Kranas

LSU Doctoral Dissertations

The Hawking effect is an exciting physical prediction lying at the intersection of the two most successful theories of the past century, namely, Einstein’s theory of relativity and quantum mechanics. In this dissertation, we put special emphasis on the quantum aspects of the Hawking process encoded in the entanglement shared by the emitted fluxes of created quanta. In particular, we employ sharp tools from quantum information theory to quantify the entanglement produced by the Hawking effect throughout the black hole evaporation process. Our framework allows us to extend previous calculations of entanglement to a larger set of cases, for instance, …

Application Of A Diatomic Molecule Model Potential To A Series Of Homo- And Heterodiatomic Molecules, Dorien E. Carpenter, Javier E. Hasbun

Georgia Journal of Science

We apply a one-dimensional classical model of a diatomic molecule model potential with modifications to H₂, HF, LiF, N₂, and CO. We obtain the unknown parameters of this model by digitizing plots of the potential curves for the molecules from a published, Hartree-Fock based theoretical electron correlation calculation (Piris 2017). We then apply the method of successive approximations to the model in order to calculate the wavenumber for each molecule in the series. The wavenumber depends on a parameter which in turn depends on the initial conditions. The value of this parameter for each individual molecule …

Size Effect On The Optical Response Of Cylindrical Palladium Nanoparticles, Salem Marhaba, Mohammed Khalaf

BAU Journal - Science and Technology

In this work, a computational study is carried out to investigate the optical response of palladium nano-cylinders. The Finite Element Method (FEM) is employed using the COMSOL MULTIPHYSICS simulation program to calculate the scattering, absorption, and extinction cross-sections. The influence of the size of the cylindrical nanoparticles on their optical properties is discussed. The results are plotted for a broad spectral range of wavelengths from ultra-violet to infra-red of the incident electromagnetic wave on the cylindrical nanoparticles.

Climate Of A Cave Laboratory Representative For Rock Art Caves In The Vézère Area (South-West France), Delphine Lacanette, Léna Bassel, Fabien Salmon, Jean-Christophe Portais, Bruno Bousquet, Rémy Chapoulie, Faten Ammari, Philippe Malaurent, Catherine Ferrier

International Journal of Speleology

Leye Cave (Dordogne, France) is a laboratory cave in the Vézère area, a region that contains some of the most famous rock art caves in the world such as Lascaux, Font-de-Gaume and Combarelles, and is listed as Human World Heritage by UNESCO. Leye Cave was selected because it is representative of painted caves, with respect to parameters such as its geological stage, the presence of water and carbon dioxide, the geological state of its walls, and the size of the cave. These wall states are studied to better understand the conditions of conservation of rock art caves without damaging them. …

Fractional Charge Concept Opened Gates For New Ideas On Composition Of Matter, Polievkt Perov

College of Arts & Sciences Faculty Works

Before the concept of quarks with fractional electric charges was introduced, the electron charge magnitude e was considered as the smallest amount of charge in nature so the charge of any object could be only an integer number of ± e. Then it was suggested that the proton and neutrons are composed of quarks with the fractional charges, combined in such a way that the total charge of a proton occurred to be that same known charge +e, and the charge of a neutron was zero. We suggest expanding that fruitful concept of fractional charges to build structural models of …

New Reaction Of Neutron-Proton Conversion, Polievkt Perov

College of Arts & Sciences Faculty Works

Using our models of composite particles as consisting just of two types of elementary basic charges, +e/3 and -e/3, we suggest that in any nuclear reaction the total numbers of basic charges of each of the two types are conserved. That means that in any nuclear reaction, the basic elementary charges present in the reactants can join in different combinations to form the products of the reaction. This is like a balanced chemical equation where the number of atoms of each element is conserved. We apply this suggested principle of conservation of basic elementary charges in any nuclear reaction to …

Adaptive Quantum Information Processing In Non-Equilibrium Environments, Arshag Danageozian

LSU Doctoral Dissertations

Solid state and condensed matter systems, such as diamond impurities, superconductors, quantum dots, and ion traps, constitute important physical platforms for various applications in quantum information processing (QIP). However, it has consistently been shown that all such modern platforms suffer from non-equilibrium behavior on timescales that are relevant for many important QIP tasks. The causes range from intrinsic non-equilibrium dynamics (e.g. in diamond) to the presence of various impurities with their own internal dynamics (e.g. in superconductors and quantum dots) or variations in the control fields used to stabilize the quantum matter (e.g. in ion traps). When reserving degrees of …

Intrinsic Point Defects (Vacancies And Antisites) In Cdgep2 Crystals, Timothy D. Gustafson, Nancy C. Giles, Peter G. Schunemann, Kevin T. Zawilski, Kent L. Averett, Jonathan E. Slagle, Larry E. Halliburton

Faculty Publications

Cadmium germanium diphosphide (CdGeP₂) crystals, with versatile terahertz-generating properties, belong to the chalcopyrite family of nonlinear optical materials. Other widely investigated members of this family are ZnGeP₂ and CdSiP₂. The room-temperature absorption edge of CdGeP₂ is near 1.72 eV (720 nm). Cadmium vacancies, phosphorous vacancies, and germanium-on-cadmium antisites are present in as-grown CdGeP₂ crystals. These unintentional intrinsic point defects are best studied below room temperature with electron paramagnetic resonance (EPR) and optical absorption. Prior to exposure to light, the defects are in charge states that have no unpaired spins. Illuminating a CdGeP_{2 …}

Application Of Photoacoustic Imaging For Pneumonia Detection, Caesarany Maqfiroh, Rini Widyaningrum, Ahmad Mujtahid Anas, Mitrayana Mitrayana

Makara Journal of Science

We used photoacoustic imaging (PAI) to visualize and compare acoustic intensity levels in pneumonia-affected and healthy chicken lungs. After histological confirmation of pneumonia, the samples were scanned and subjected to a 532-nm diode laser in a photoacoustic imaging system. The acoustic intensity level of pneumonia-affected tissue was examined and compared with that of healthy lung samples. The optimum laser frequency and duty cycle for imaging the samples were 17 kHz and 30%, respectively. The acoustic intensity levels of pneumonia-affected tissue and healthy lungs were −82.5 ± 1.8 dB and −79.9 ± 1.3 dB, respectively. We found that a simple PAI …

Effect Of Ag2o Nanosheets Thickness On The Performance Of Al/Geo2/Ag2o/Geo2/C Multifunctional Electronic Devices, Atef Fayez Qasrawi Prof. Dr., Hazem Kh Khanfar Prof. Dr.

Journal of the Arab American University مجلة الجامعة العربية الامريكية للبحوث

Herein, stacked layers of germanium oxide comprising silver oxide nanosheets are used to fabricate multifunctional electronic devices. The performance of these devices is enhanced by altering the thickness of Ag2O nanosheets. The effect of

Ag2O nanosheets on the electronic performance of stacked layers of GeO2 is reported. The three stacked layers (GeO2/Ag2O/GeO2; named GAG) which are coated onto Al substrates under a vacuum pressure of 10-5 mbar are subjected to measurements by X-ray diffraction, X-ray photoelectron, X-ray fluorescence, impedance spectroscopy, capacitance –voltage and current-voltage characteristics techniques. The impedance spectroscopy analysis indicates that altering the thickness of the Ag2O layer in …

Anderson Localization Of Electromagnetic Waves In Three Dimensions, Alexey Yamilov, Sergey E. Skipetrov, Tyler W. Hughes, Momchil Minkov, Zongfu Yu, Hui Cao

Physics Faculty Research & Creative Works

Anderson localization is a halt of diffusive wave propagation in disordered systems. Despite extensive studies over the past 40 years, Anderson localization of light in three dimensions has remained elusive, leading to the question of its very existence. Recent advances have enabled finite-difference time-domain calculations to be sped up by orders of magnitude, allowing us to conduct brute-force numerical simulations of light transport in fully disordered three-dimensional systems with unprecedented dimension and refractive index difference. We show numerically three-dimensional localization of vector electromagnetic waves in random aggregates of overlapping metallic spheres, in sharp contrast to the absence of localization for …

Optical Characterisation Of Holographic Diffusers And Bangerter Foils For Treatment Of Amblyopia, Matthew Hellis, Suzanne Martin, Matthew Sheehan, Kevin Murphy

Articles

Amblyopia is a significant issue for children worldwide, and current treatment methods have drawbacks that can hinder treatment effectiveness and/or patient experience. This study proposes a new treatment method using holographic diffusers while also comparing their optical characteristics to a current treatment method (Bangerter foils). Holographic diffusers were developed by optically patterning thin polymer layers on a micron scale. Two compositions of photopolymer (acrylamide and diacetone acrylamide based) are analysed herein. Characterisation shows that holographic diffusers of either composition can achieve a wide range of on-axis intensity reductions, allowing for precise and customisable treatment levels by altering recording exposure time …

Optical Variability Of Green Pea Galaxies, Julissa Marie Sarmiento

College of Science and Health Theses and Dissertations

In this thesis, I am investigating the optical variability of Green Pea galaxies (GPs). GPs are good analogs to high-redshift galaxies, enabling us to learn more about the first galaxies in the universe. One of their key properties is their strong emission lines, some of which indicate the presence of an active galactic nucleus (AGN). An effective way to identify AGN is to look for stochastic variability in the optical light from the galaxy. Finding AGN in these galaxies would help us learn more about the formation and evolution of the supermassive black holes that power AGN. In this thesis, …

Development Of A Particle-In-Cell/Monte Carlo Simulation For Weakly Ionized Plasmas, Xiaochuan (Chloe) Zheng, James Doyle

Macalester Journal of Physics and Astronomy

A plasma is a gaseous system that contains large numbers of electrons and ions that are subject to forces produced by electric and magnetic fields. Weakly ionized plasmas, where the plasma density is much lower than the background gas density, are common in laboratory, atmospheric, and astrophysical situations. Theoretical calculations of plasma properties are challenging due to the complexity of the differential equations used to characterize fundamental physics. Particle-in-cell (PIC) simulations bypass the mathematical difficulties associated with analytic models, at the expense of more complex and time-consuming computer calculations. In this work we developed a one dimensional PIC simulation of …