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Articles 2461 - 2490 of 34100
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Mechanistic Investigation Of C—C Bond Activation Of Phosphaalkynes With Pt(0) Complexes, Roberto M. Escobar, Abdurrahman C. Ateşin, Christian Müller, William D. Jones, Tülay Ateşin
Mechanistic Investigation Of C—C Bond Activation Of Phosphaalkynes With Pt(0) Complexes, Roberto M. Escobar, Abdurrahman C. Ateşin, Christian Müller, William D. Jones, Tülay Ateşin
Research Symposium
Carbon–carbon (C–C) bond activation has gained increased attention as a direct method for the synthesis of pharmaceuticals. Due to the thermodynamic stability and kinetic inaccessibility of the C–C bonds, however, activation of C–C bonds by homogeneous transition-metal catalysts under mild homogeneous conditions is still a challenge. Most of the systems in which the activation occurs either have aromatization or relief of ring strain as the primary driving force. The activation of unstrained C–C bonds of phosphaalkynes does not have this advantage. This study employs Density Functional Theory (DFT) calculations to elucidate Pt(0)-mediated C–CP bond activation mechanisms in phosphaalkynes. Investigating the …
Spectroscopic End Point Detection With An Electron Beam Evaporator, Ryan Mcgraw
Spectroscopic End Point Detection With An Electron Beam Evaporator, Ryan Mcgraw
University Honors Theses
Spectroscopic end point detection is a common tool used for measuring slope changes in wavelength intensity. Using algorithms able to apply this concept, coatings will be able to be dynamically measured in real time and stopped at the appropriate level to ensure process uniformity. It is currently applied to reductive processes such as etching, where the surface will start to be eaten away, creating a plasma. When the entire amount of a material on a substrate has been eaten away, the plasma will change color as it is beginning to etch a different material. Using a spectrometer, this point where …
Estimating Polarization Purity With Noise, Alex Kostinski, Dan Kestner, Jothiram Vivekanandan
Estimating Polarization Purity With Noise, Alex Kostinski, Dan Kestner, Jothiram Vivekanandan
Michigan Tech Publications
We formulate a problem of estimating and monitoring mismatch (unwanted departure from orthogonality) of two ostensibly orthogonal polarization channels in a fully polarimetric general device such as a polarimetric weather radar. A statistical approach is proposed by using thermal noise or, more generally, a 'polarimetric noise' class of sources. The suitable noise class of distributions is shown to be rooted in the complex multivariate Gaussian probability density function (pdf), the latter possessing a uniform pdf on the Poincare sphere (PS), with a probability measure given by a fractional surface area. To that end, we develop a parameter to estimate polarization …
Second Inflection Point Of Supercooled Water Surface Tension Induced By Hydrogen Bonds: A Molecular-Dynamics Study, Fawaz Hrahsheh, Inshad Jum'h, Gerald Wilemski
Second Inflection Point Of Supercooled Water Surface Tension Induced By Hydrogen Bonds: A Molecular-Dynamics Study, Fawaz Hrahsheh, Inshad Jum'h, Gerald Wilemski
Physics Faculty Research & Creative Works
Surface Tension Of Supercooled Water Is A Fundamental Property In Various Scientific Processes. In This Study, We Perform Molecular Dynamics Simulations With The TIP4P-2005 Model To Investigate The Surface Tension Of Supercooled Water Down To 220 K. Our Results Show A Second Inflection Point (SIP) In The Surface Tension At Temperature TSIP ≈ 267.5 ± 2.3 K. Using An Extended IAPWS-E Functional Fit For The Water Surface Tension, We Calculate The Surface Excess Internal-Energy And Entropy Terms Of The Excess Helmholtz Free Energy. Similar To Prior Studies [Wang Et Al., Phys. Chem. Chem. Phys. 21, 3360 (2019); Gorfer Et Al., …
Doubly Charged Dimers And Trimers Of Heavy Noble Gases, Gabriel Schöpfer, Stefan Bergmeister, Milan Ončák, Ianessa Stromberg, Masoomeh Mahmoodi-Darian, Paul Scheier, Olof Echt, Elisabeth Gruber
Doubly Charged Dimers And Trimers Of Heavy Noble Gases, Gabriel Schöpfer, Stefan Bergmeister, Milan Ončák, Ianessa Stromberg, Masoomeh Mahmoodi-Darian, Paul Scheier, Olof Echt, Elisabeth Gruber
Faculty Publications
Many doubly charged heteronuclear dimers are metastable or even thermodynamically stable with respect to charge separation. Homonuclear dicationic dimers, however, are more difficult to form. He22+ was the first noble gas dimer predicted to be metastable and, decades later, observed. Ne22+ is the only other dicationic noble gas dimer that has been detected so far. Here, we present a novel approach to form fragile dicationic species, by post-ionization of singly charged ions that are embedded in helium nanodroplets (HNDs). Bare ions are then extracted by colliding the HNDs with helium gas. We detect homonuclear doubly charged …
Strengthen Establishment Of Application-Supported Major Science And Technology Infrastructure To Enhance Basic Capacity Of Science And Technology For High-Quality Development, Congli Huang, Feite Zhou, Xiang Xu, Lingling Zhang
Strengthen Establishment Of Application-Supported Major Science And Technology Infrastructure To Enhance Basic Capacity Of Science And Technology For High-Quality Development, Congli Huang, Feite Zhou, Xiang Xu, Lingling Zhang
Bulletin of Chinese Academy of Sciences (Chinese Version)
From “Two Bombs and One Satellite” to Five-hundred-meter Aperture Spherical Radio Telescope (FAST), from ground zero to the center stage of the world, China has unswervingly followed the path of independent innovation with distinctive characteristics. After the development of nearly half a century, breakthroughs have been made in several key areas. The position, implication, and classification of major scientific and technological infrastructures are constantly changing under the new situation. Based on an in-depth investigation of major scientific and technological infrastructure such as high-efficiency and low-carbon gas turbine research facility, it is believed that the construction of application-supported major scientific and …
The Infrared Absorption Spectrum Of Phenylacetylene And Its Deuterated Isotopologue In The Mid- To Far-Ir, Vincent J. Esposito, Pierro Ferrari, Wybren Jan Buma, Ryan C. Fortenberry, Christiaan Boersma, Alessandra Candian, Alexander G. G. M. Tielens
The Infrared Absorption Spectrum Of Phenylacetylene And Its Deuterated Isotopologue In The Mid- To Far-Ir, Vincent J. Esposito, Pierro Ferrari, Wybren Jan Buma, Ryan C. Fortenberry, Christiaan Boersma, Alessandra Candian, Alexander G. G. M. Tielens
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Anharmonicity strongly influences the absorption and emission spectra of polycyclic aromatic hydrocarbon (PAH) molecules. Here, IR–UV ion-dip spectroscopy experiments together with detailed anharmonic computations reveal the presence of fundamental, overtone, as well as 2- and 3-quanta combination band transitions in the far- and mid-infrared absorption spectra of phenylacetylene and its singly deuterated isotopologue. Strong absorption features in the 400–900 cm−1 range originate from CH(D) in-plane and out-of-plane wags and bends, as well as bending motions including the C≡C and CH bonds of the acetylene substituent and the aromatic ring. For phenylacetylene, every absorption feature is assigned either directly or …
Surface And Bulk Properties Of Multi-Component Metal Alloys, Frank A. Mckay Iii
Surface And Bulk Properties Of Multi-Component Metal Alloys, Frank A. Mckay Iii
LSU Doctoral Dissertations
While HEAs have been studied extensively for their material properties, their potential as catalysts remains widely unexplored. To explore the feasibility of CoCrFeNi as a catalyst for the hydrogen evolution reaction, the results of X-ray photoelectron spectroscopy (XPS) and high-resolution electron energy loss spectroscopy (HREELS) experiments are compared to electrochemical experiments and theoretical calculations. XPS shows that this surface forms passive oxides with a propensity of Cr > Fe > Co, with no evidence of Ni oxidation. From comparison to calculations, it is shown that the electrochemical activity is enhanced in a partially oxidized state. The lack of Ni oxidation suggests that …
Development And Evaluation Of Novel Applications For The Ethos Cbct-Guided Online Adaptive Radiotherapy System, Nour Nasser
Development And Evaluation Of Novel Applications For The Ethos Cbct-Guided Online Adaptive Radiotherapy System, Nour Nasser
USF Tampa Graduate Theses and Dissertations
Radiation therapy (RT) is an important pillar of modern cancer treatment, in neoadjuvant, curative, adjuvant, and palliative settings. The physics underlying RT is ionizing radiation that produces charged particles, which deposit their energy in the tissues they pass through. This energy results in unrepairable DNA damage resulting in the death of cancer tissue. The aim of RT is to deliver the desired radiation dose to the tumor while maximizing normal tissue sparing. Over the past decades, physics, engineering, and computational improvements has allowed advancement of external beam RT techniques, for example from 2D RT to 3D RT to now intensity …
Neutrino’S Non-Zero Electric Potential As An Origin Of Gravitation, Domain Structure And Expansion Of The Universe., Polievkt Perov
Neutrino’S Non-Zero Electric Potential As An Origin Of Gravitation, Domain Structure And Expansion Of The Universe., Polievkt Perov
College of Arts & Sciences Faculty Works
The axial electric potentials of neutrinos as neutral composite structures, while being very small at large distances, do not vanish, and the same can be said about the neutrino “asymmetric dipoles” (paired neutrinos of not the same kind). Depending on the orientation of the “asymmetric dipole”, its far-field electric potential in some direction can be positive or negative, interacting with other “dipoles” at that large distance attractively or repulsively depending on their mutual orientation. The mutual orientation of the dipoles locally (inside a galaxy) might be such that they are aligned and experience the attractive force toward the local center …
Beyond Standard Model: Neutrino-Antineutrino Pairs In Nuclear Reactions Of Beta-Decay And Proton-Neutron Transmutation., Polievkt Perov
Beyond Standard Model: Neutrino-Antineutrino Pairs In Nuclear Reactions Of Beta-Decay And Proton-Neutron Transmutation., Polievkt Perov
College of Arts & Sciences Faculty Works
On examples of different beta-decay reactions, we show that the neutrino-antineutrino pairs should be added as necessary reagents to the equations of the decay reactions where a neutrino or an antineutrino is among the products of the reaction. In our models, quarks and leptons are all made of basic fractional +-e/3 charges. Transfer of basic charges between reagents forms the products of the reaction. We suggest that there is no direct conversion of u-quark to d-quark and visa versa. Each transmutation involves a transfer of basic charges from a neutrino to a quark so the structure of remaining charges in …
Alternative Robust Ways Of Witnessing Nonclassicality In The Simplest Scenario, Massy Khoshbin, Lorenzo Catani, Matthew Leifer
Alternative Robust Ways Of Witnessing Nonclassicality In The Simplest Scenario, Massy Khoshbin, Lorenzo Catani, Matthew Leifer
Mathematics, Physics, and Computer Science Faculty Articles and Research
In this paper we relate notions of nonclassicality in what is known as the simplest nontrivial scenario (a prepare and measure scenario composed of four preparations and two binary-outcome tomographically complete measurements). Specifically, we relate the established method developed by Pusey [M. F. Pusey, Phys. Rev. A 98, 022112 (2018)] to witness a violation of preparation noncontextuality, that is not suitable in experiments where the operational equivalences to be tested are specified in advance, with an approach based on the notion of bounded ontological distinctness for preparations, defined by Chaturvedi and Saha [A. Chaturvedi and D. Saha, Quantum …
Resolving The Nanoscale Structure Of Β-Sheet Peptide Self-Assemblies Using Single-Molecule Orientation–Localization Microscopy, Weiyan Zhou, Conor L. O'Neill, Tianben Ding, Oumeng Zhang, Jai S. Rudra, Matthew D. Lew
Resolving The Nanoscale Structure Of Β-Sheet Peptide Self-Assemblies Using Single-Molecule Orientation–Localization Microscopy, Weiyan Zhou, Conor L. O'Neill, Tianben Ding, Oumeng Zhang, Jai S. Rudra, Matthew D. Lew
Electrical & Systems Engineering Publications and Presentations
Synthetic peptides that self-assemble into cross-β fibrils are versatile building blocks for engineered biomaterials due to their modularity and biocompatibility, but their structural and morphological similarities to amyloid species have been a long-standing concern for their translation. Further, their polymorphs are difficult to characterize using spectroscopic and imaging techniques that rely on ensemble averaging to achieve high resolution. Here, we utilize Nile red (NR), an amyloidophilic fluorogenic probe, and single-molecule orientation-localization microscopy (SMOLM) to characterize fibrils formed by the designed amphipathic enantiomers KFE8L and KFE8D and the pathological amyloid-beta peptide Aβ42. Importantly, NR SMOLM reveals the helical (bilayer) …
6d Single-Fluorogen Orientation-Localization Microscopy For Elucidating The Architecture Of Beta-Sheet Assemblies And Biomolecular Condensates, Tingting Wu, Weiyan Zhou, Jai S. Rudra, Rohit V. Pappu, Matthew D. Lew
6d Single-Fluorogen Orientation-Localization Microscopy For Elucidating The Architecture Of Beta-Sheet Assemblies And Biomolecular Condensates, Tingting Wu, Weiyan Zhou, Jai S. Rudra, Rohit V. Pappu, Matthew D. Lew
Electrical & Systems Engineering Publications and Presentations
We develop six-dimensional single-molecule orientation-localization microscopy (SMOLM) to measure the 3D positions and 3D orientations simultaneously of single fluorophores. We show how careful optimization of phase and polarization modulation components can encode phase, polarization, and angular spectrum information from each fluorescence photon into a microscope’s dipole-spread function. We used the transient binding and blinking of Nile red (NR) to characterize the helical structure of fibrils formed by designed amphipathic peptides, KFE8L and KFE8D, and the pathological amyloid-beta peptide Aβ42. We also deployed merocyanine 540 to uncover the interfacial architectures of biomolecular condensates.
Vibrational Spectrum Of Granular Packings With Random Matrices, Harsh Mathur
Vibrational Spectrum Of Granular Packings With Random Matrices, Harsh Mathur
Faculty Scholarship
Abstract: The vibrational spectrum of granular packings can be used as a signature of the jamming transition, with the density of states at zero frequency becoming nonzero at the transition. It has been proposed previously that the vibrational spectrum of granular packings can be approximately obtained from random matrix theory. Here, we show that the autocorrelation function of the density of states shows good agreement between dynamical numerical simulations of frictionless bead packs near the jamming point and the analytic predictions of the Laguerre orthogonal ensemble of random matrices; there is clear disagreement with the Gaussian orthogonal ensemble, establishing that …
Spectralomics – Towards A Holistic Adaptation Of Label Free Spectroscopy, Hugh Byrne
Spectralomics – Towards A Holistic Adaptation Of Label Free Spectroscopy, Hugh Byrne
Articles
Vibrational spectroscopy, largely based on infrared absorption and Raman scattering techniques, is much vaunted as a label free approach, delivering a high content, holistic characterisation of a sample, with demonstrable applications in a broad range of fields, from process analytical technologies and preclinical drug screening, to disease diagnostics, therapeutics, prognostics and personalised medicine. However, in the analysis of such complex systems, a trend has emerged in which spectral analysis is reduced to the identification of individual peaks, based on reference tables of assignments derived from literature, which are then interpreted as biomarkers. More sophisticated analysis attempts to unmix the spectrum …
Instability And Quantization In Quantum Hydrodynamics, Yakir Aharonov, Tomer Shushi
Instability And Quantization In Quantum Hydrodynamics, Yakir Aharonov, Tomer Shushi
Mathematics, Physics, and Computer Science Faculty Articles and Research
We show how the quantum hydrodynamical formulation of quantum mechanics converts the nonlocality in the standard wave-like description of quantum systems by an instability of the quantum system, which opens the door to a new way for studying quantum systems based on known methodologies for studying the stability of fluids. As a second result, we show how the Madelung equations describe quantized energies without any external quantization conditions.
Extremely Red Galaxies At Z = 5-9 With Miri And Nirspec: Dusty Galaxies Or Obscured Active Galactic Nuclei?, Guillermo Barro, Pablo G. Pérez-González, Dale D. Kocevski, Elizabeth J. Mcgrath, Jonathan R. Trump, Raymond C. Simons, Rachel S. Somerville, L. Y. Aaron Yung, Pablo Arrabal Haro, Hollis B. Akins, Michaela B. Bagley, Nikko J. Cleri, Luca Costantin, Kelcey Davis, Mark Dickinson, Steve L. Finkelstein, Mauro Giavalisco, Carlos Gómez-Guijarro, Nimish P. Hathi, Michaela Hirschmann, Benne W. Holwerda
Extremely Red Galaxies At Z = 5-9 With Miri And Nirspec: Dusty Galaxies Or Obscured Active Galactic Nuclei?, Guillermo Barro, Pablo G. Pérez-González, Dale D. Kocevski, Elizabeth J. Mcgrath, Jonathan R. Trump, Raymond C. Simons, Rachel S. Somerville, L. Y. Aaron Yung, Pablo Arrabal Haro, Hollis B. Akins, Michaela B. Bagley, Nikko J. Cleri, Luca Costantin, Kelcey Davis, Mark Dickinson, Steve L. Finkelstein, Mauro Giavalisco, Carlos Gómez-Guijarro, Nimish P. Hathi, Michaela Hirschmann, Benne W. Holwerda
Pacific Faculty Work
We study a new population of extremely red objects (EROs) recently discovered by the James Webb Space Telescope (JWST) based on their NIRCam colors F277W − F444W > 1.5 mag. We find 37 EROs in the Cosmic Evolution Early Release Science Survey (CEERS) field with F444W < 28 mag and photometric redshifts between 5 < z < 7, with median z = 6.9 − 1.6 + 1.0 . Surprisingly, despite their red long-wavelength colors, these EROs have blue short-wavelength colors (F150W − F200W ∼ 0 mag) indicative of bimodal spectral energy distributions (SEDs) with a red, steep slope in the rest-frame optical, and a blue, flat slope in the rest-frame UV. Moreover, all these EROs are unresolved, point-like sources in all NIRCam bands. We analyze the SEDs of eight of them with MIRI and NIRSpec observations using stellar population models and active galactic nucleus (AGN) templates. We find that dusty galaxies or obscured AGNs provide similarly good SED fits but different stellar properties: massive and dusty, log M ⋆ / M ⊙ ∼ 10 and A V ≳ 3 mag, or low mass and obscured, log M ⋆ / M ⊙ ∼ 7.5 and A V ∼ 0 mag, hosting an obscured quasi-stellar object (QSO). SED modeling does not favor either scenario, but their unresolved sizes are more suggestive of AGNs. If any EROs are confirmed to have log M ⋆ / M ⊙ ≳ 10.5, it would increase the pre-JWST number density at z > 7 by up to a factor ∼60. Similarly, if they are QSOs with luminosities in the L bol > 1045-46 erg s−1 range, their number would exceed that of bright blue QSOs by more than three orders of magnitude. Additional photometry at mid-infrared wavelengths will reveal the true nature of the red continuum emission …
Laboratory Exercise For The Radiometry Student, Michael A. Marciniak
Laboratory Exercise For The Radiometry Student, Michael A. Marciniak
Faculty Publications
The U.S. Air and Space Forces require optical expertise among their personnel. The Air Force Institute of Technology offers a graduate optics curriculum, which includes a three-course sequence to educate students in the optical concepts of radiometry and radiometric instrumentation. We find radiometry is often a deceptively difficult concept for students to master. To address this, we have developed an experiment in our optics-laboratory coursework to help them gain this mastery. A Fourier-transform infrared spectrometer (FTS) is used to collect spectral data from an unknown sample. FTS calibration and data collection are discussed here, as are the two specific samples …
Beyond Standard Model: Neutrino Dipoles And Proto Hydrogen Bundles., Polievkt Perov
Beyond Standard Model: Neutrino Dipoles And Proto Hydrogen Bundles., Polievkt Perov
College of Arts & Sciences Faculty Works
In our composite models of elementary particles as consisting of just two types of elementary basic charges, +e/3 and -e/3, the axial electric potential of any elementary particle is a function of a distance from the particle, and this function differs from the Coulomb potential of a point total charge of the particle. The electric potential of neutrinos is not zero at close distances from neutrinos. Neutrinos can form dipoles and bundles of 3 or more neutrinos. The three-neutrino bundle (a proto-hydrogen) can be converted to a hydrogen atom. As we suggested in our previous paper [4], the total numbers …
Beyond Standard Model: Electrostatic Potential Energy Of Quarks, Electron, And Neutrinos As Spinning Composite Structures, Polievkt Perov
Beyond Standard Model: Electrostatic Potential Energy Of Quarks, Electron, And Neutrinos As Spinning Composite Structures, Polievkt Perov
College of Arts & Sciences Faculty Works
The potential energy of any composite structure is related to the binding energy of the structure. The equations for the electrostatic potential energy of quarks, electron-like structures, and neutrinos are presented for our models of elementary particles as spinning composite structures. The structures consist of up to 3 basic elementary charges of magnitude e/3 on the axis of rotation and N charges revolving about the axis. We applied these general equations specifically to the models of different quarks, electron and electron-like particles (muon and tau), and neutral particles (neutrinos). It is shown that the electrostatic potential energies of all considered …
Adsorption Of Crystal Violet Dye From Synthetic Wastewater By Ball-Milled Royal Palm Leaf Sheath, Neloy Sen, Nawrin Rahman Shefa, Kismot Reza, Sk Md Ali Zaker Shawon, Md. Wasikur Rahman
Adsorption Of Crystal Violet Dye From Synthetic Wastewater By Ball-Milled Royal Palm Leaf Sheath, Neloy Sen, Nawrin Rahman Shefa, Kismot Reza, Sk Md Ali Zaker Shawon, Md. Wasikur Rahman
Physics & Astronomy Faculty Publications
The current study shows that using a batch approach to remove crystal violet dye from synthetic wastewater is feasible when using royal palm leaf sheath powder as an adsorbent. In order to investigate the effects of many parameters, including starting concentration, pH effect, dye concentration, adsorbent dose, contact time, and temperature, experiments were carried out under various operating conditions. Maximum removal was obtained at pH 6 and at a concentration of 100 ppm, which are considered as ideal values. The influence of pH and dye concentration was shown to be substantial. Langmuir, Freundlich, and Temkin isotherm models were fitted to …
Development Of An Integrated Workflow For Nucleosome Modeling And Simulations, Ran Sun
Development Of An Integrated Workflow For Nucleosome Modeling And Simulations, Ran Sun
Doctoral Dissertations
Nucleosomes are the building blocks of eukaryotic genomes and thus fundamental to to all genetic processes. Any protein or drug that binds DNA must either cooperate or compete with nucleosomes. Given that a nucleosome contains 147 base pairs of DNA, there are approximately 4^147 or 10^88 possible sequences for a single nucleosome. Exhaustive studies are not possible. However, genome wide association studies can identify individual nucleosomes of interest to a specific mechanism, and today's supercomputers enable comparative simulation studies of 10s to 100s of nucleosomes. The goal of this thesis is to develop and present and end-to-end workflow that serves …
Non-Relativistic Limit Of Selected Terms From The Sme Dirac Lagrangian, Quinn Reece
Non-Relativistic Limit Of Selected Terms From The Sme Dirac Lagrangian, Quinn Reece
Physics
We examine a selection of individual CPT/Lorentz violating terms present in the relativistic lagrangian for a free spin- 1 2 Dirac fermion of mass m in the Standard Model Extension. Euler-Lagrange relations will be applied to give Dirac-like equations including these terms and a novel procedure will be used to generate non-relativistic limits of these equations which are Schr¨odinger-Pauli-like equations. These equations will be analyzed using classical quantum mechanics toy problems to gain physical intuition for the effects of the CPT violating terms, and the results will be discussed. We will conclude with discussion on future work will include the …
The Interplay Of Spin, Charge, And Heat: From Metal/Insulator Heterostructures To Perovskite Bilayers, Sam M. Bleser
The Interplay Of Spin, Charge, And Heat: From Metal/Insulator Heterostructures To Perovskite Bilayers, Sam M. Bleser
Electronic Theses and Dissertations
In this dissertation begin with an investigation of non-local spin transport in an amorphous germanium (a-Ge) sample via the inverse spin Hall effect (ISHE). In that study we show that commonly used techniques such as differential conductance and delta mode of a paired Keithley 6221/2182a for non-local resistance measurements can lead to false indicators of spin transport. Next, we turn out attention to a thickness dependent study in thermally-evaporated chromium (Cr) thin films on a bulk polycrystalline yttrium-iron-garnet (YIG) substrate. This project analyzed the spin transport in the Cr films versus thickness via the longitudinal spin Seebeck effect (LSSE). This …
Thermal, Electrical, And Spin Transport: Encompassing Low-Damping Ferromagnets And Antiferromagnetic/Ferromagnetic Heterostructures, Matthew Ryan Natale
Thermal, Electrical, And Spin Transport: Encompassing Low-Damping Ferromagnets And Antiferromagnetic/Ferromagnetic Heterostructures, Matthew Ryan Natale
Electronic Theses and Dissertations
Continuing technological advancements bring forth escalating challenges in global energy consumption and subsequent power dissipation, posing significant economic and environmental concerns. In response to these difficulties, the fields of thermoelectrics, spintronics, and spincaloritronics emerge as contemporary solutions, each presenting unique advantages. Thermoelectric devices, based on the Seebeck effect, other a passive, carbon-free energy generating solution from waste heat. Although current thermoelectric technology encounters hurdles in achieving optimal efficiencies without intricate designs or complex materials engineering, recently research into low-damping metallic ferromagnetic thin films have provided a new method to enhance spin wave lifetimes, thus contributing to thermoelectric voltage improvements. As …
Highly Sensitive On-Chip Grating-Based Optical Sensor On Glass Substrate: Cost-Effective Design, Hesham A. Attia, Mulan E. Ahmed, Adel Shaaban Awad Elsharkawi, Mohamed A. Swillam
Highly Sensitive On-Chip Grating-Based Optical Sensor On Glass Substrate: Cost-Effective Design, Hesham A. Attia, Mulan E. Ahmed, Adel Shaaban Awad Elsharkawi, Mohamed A. Swillam
Faculty Journal Articles
This paper presents a novel on-chip optical sensing system using ion exchange technology and phase-shifted Bragg grating design. The sensor geometry has been optimized using a finite difference time domain (FDTD) solver to achieve maximum sensitivity and figure of merit (FOM). The proposed design offers high sensitivity to changes in refractive index and low fabrication costs. The ion exchange process used to create the sensor allows for precise refractive index control, optimizing the sensor’s sensitivity and FOM. A graded-index waveguide and a phase-shifted Bragg grating structure also contribute to the sensor’s high sensitivity. The proposed sensor design was tested for …
Designing An Optical Router Based On A Multimode-Interference Silicon-On-Insulator Coupler With Tunable Power Transmittance, Dana S. Akil, Muhammad A. Othman, Sherif M. Sherif, Mohamed A. Swillam
Designing An Optical Router Based On A Multimode-Interference Silicon-On-Insulator Coupler With Tunable Power Transmittance, Dana S. Akil, Muhammad A. Othman, Sherif M. Sherif, Mohamed A. Swillam
Faculty Journal Articles
The demand on fast and high-bandwidth data transmission is in continuous increase. These demands are highly dependent on optical signal manipulation, including switching, modulation, and routing. We demonstrate a two-port silicon optical router based on the multimode interferometer (MMI) configuration. The same MMI structure was used for both inward and backward waveguiding to reduce the total length of the device. A phase shifter consisting of two ring-like waveguides made of silicon p-n junctions was used to introduce the phase shift needed for optical routing upon voltage application. Two designs for the MMI optical router were studied: Firstly, a conventional MMI …
Ionization Cross Sections Of Hydrogen Molecule By Electron And Positron Impact, Károly Tőkési, Robert D. Dubois
Ionization Cross Sections Of Hydrogen Molecule By Electron And Positron Impact, Károly Tőkési, Robert D. Dubois
Physics Faculty Research & Creative Works
We Present Ionization Cross Sections of Hydrogen Molecules by Electron and Positron Impact for Impact Energies between 20 and 1000 EV. a Three-Body Classical Trajectory Monte Carlo Approximation is Applied to Mimic the Collision System. in This Approach, the H2 Molecule is Modeled by a Hydrogen-Type Atom with One Active Electron Bound to a Central Core of Effective Charge with an Effective Binding Energy. Although This Model is Crude for Describing a Hydrogen Molecule, We Found that the Total Cross Sections for Positron Impact Agree Reasonably Well with the Experimental Data. for the Electron Impact, Our Calculated Cross Sections Are …
3F4 Hypergeometric Functions As A Sum Of A Product Of 2F3 Functions, Jack C. Straton
3F4 Hypergeometric Functions As A Sum Of A Product Of 2F3 Functions, Jack C. Straton
Physics Faculty Publications and Presentations
This paper shows that certain 3F4 hypergeometric functions can be expanded in sums of pair products of 2F3 functions, which reduce in special cases to 2F3 functions expanded in sums of pair products of 1F2 functions. This expands the class of hypergeometric functions having summation theorems beyond those expressible as pair-products of generalized Whittaker functions, 2F1 functions, and 3F2 functions into the realm of pFq functions where p < q for both the summand and terms in the series. In addition to its intrinsic value, this result has a specific application in calculating the response of the atoms to laser stimulation in the Strong Field Approximation.