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Articles 1 - 11 of 11
Full-Text Articles in Physics
Charge Effects In Bilayer Electric Transport, Christopher Czech
Charge Effects In Bilayer Electric Transport, Christopher Czech
All Theses
The mathematical isomorphism between the layer index in a bilayer system and the spin index in a spin-polarized system is used to draw an analogy between phenomena that occur in the two systems as a result of the electron-electron (e-e) interaction. First, the classical case of the Coulomb drag, a phenomenon resulting from momentum transfer through e-e collisions, is reviewed for both bilayer systems and spin-polarized systems. Then, the spin-backflow phenomenon, a result of the interaction-induced changes in the local quasiparticle energy that affects the charge transport in spin-polarized systems is presented. Finally, the iso-spin correlation is exploited to establish …
Spin Density Wave Phases In Semiconductor Superlattice, Liqiu Zheng
Spin Density Wave Phases In Semiconductor Superlattice, Liqiu Zheng
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We discuss the existence of spin instabilities and of possible ground states with broken spin symmetry in the presence of a tilted magnetic field for several semiconductor heterostructures. In each instance, the fundamental premise of our study is the existence of a spin degeneracy, controlled by tuning various experimentally controllable parameters, that permits the apparition of spin-flip processes driven entirely by the many-body Coulomb interaction. If in the case of a single quantum well, the spin instabilities trigger an abrupt paramagnetic to ferromagnetic phase transition, we demonstrate that in superlattices, at low temperatures, a stable spin density wave ($SDW$) ground …
Optimization Of Electrostatic Interactions In Protein-Protein Complexes, Kelly Brock, Kemper Talley, Kacey Coley, Petras Kundrotas, Emil Alexov
Optimization Of Electrostatic Interactions In Protein-Protein Complexes, Kelly Brock, Kemper Talley, Kacey Coley, Petras Kundrotas, Emil Alexov
Publications
In this article, we present a statistical analysis of the electrostatic properties of 298 protein-protein complexes and 356 domain-domain structures extracted from the previously developed database of protein complexes (ProtCom, http://www.ces.clemson.edu/compbio/protcom). For each structure in the dataset we calculated the total electrostatic energy of the binding and its two components, Coulombic and reaction field energy. It was found that in a vast majority of the cases (>90%), the total electrostatic component of the binding energy was unfavorable. At the same time, the Coulombic component of the binding energy was found to favor the complex formation while …
The Thermoelectric Properties Investigation Of Ir3Ge7 Typed Representatives, Huqin Zhang
The Thermoelectric Properties Investigation Of Ir3Ge7 Typed Representatives, Huqin Zhang
All Theses
Energy conversion is employed to power generation utilizing the Seebeck effect or cooling utilizing the Peltier effect. Herein, we study several Ir3Ge7 typed semiconductor materials for potential thermoelectric energy conversion. Mo3Sb7, crystallizing in Ir3Ge7 type, can be rendered semiconducting by a partial Sb-Te substitution without noticeable structure changes, resulting in Mo3Sb5Te2 with 55 valence electrons per formula unit. Meanwhile, large cubic voids in the Mo3Sb5Te2 crystal structure provide the possibility of filling the voids with small cations to decrease the …
Comparison Of Thermoelectric Properties Of Arc-Melted And Hot-Pressed Half-Heuslers, Brad Edwards
Comparison Of Thermoelectric Properties Of Arc-Melted And Hot-Pressed Half-Heuslers, Brad Edwards
All Theses
Relatively low thermal conductivity and great electrical properties in combination with wide tuning parameters through doping make half-Heuslers high potential thermoelectric materials. In this study we plan to investigate the effects of hot-pressing and arc-melting on the thermoelectric properties of ZrNiSn0.975Sb0.025, and Hf0.75Zr0.25NiSn0.975Sb0.025 samples. Also, the effects of electron and phonon scattering due to the insertion of small 50 nm particles within the sample were investigated in ZrNiSn0.975Sb0.025 +4% Al2O3 and Hf0.75Zr0.25NiSn0.975Sb0.025 +4% Al2O …
Comparison Between Steady State And Laser Flash Techniques, Justine Andrews
Comparison Between Steady State And Laser Flash Techniques, Justine Andrews
All Theses
Thermoelectrics is a promising avenue of energy conservation. A material is deemed a good thermoelectric material when it portrays certain material characteristics. These characteristics include a high thermopower and electrical conductivity and a low thermal conductivity. This thesis focuses on the methods of measuring a material's thermal conductivity.
The steady state method is a measurement technique used in the low temperature thermal conductivity measurements. This technique assures that the system and sample are at equilibrium before a measurement point is taken. As a result the measurements are both precise and accurate.
The laser flash technique measures a sample's thermal conductivity …
Carbon Nanomaterials In Biological Systems, Sijie Lin
Carbon Nanomaterials In Biological Systems, Sijie Lin
All Theses
ABSTRACT
This thesis intends to present, from the biophysical viewpoint, my study on understanding carbon nanomaterials in biological and environmental systems. Carbon nanotubes and fullerenes represent a major family of carbon nanoparticles which possess distinct electrical, optical and mechanical properties. However, the major hurdle for making carbon nanomaterials bioavailable lies in their tendency toward bundling, driven by hydrophobic interaction, van der Waals force, and pi-stacking. To overcome this problem, we used non-covalent binding of zwitterionic lysophopholipids (LPL) onto the external surfaces of single-walled carbon nanotubes (SWNTs). This method affords superior SWNT solubility in aqueous solution. The stability of SWNT-LPL complex …
Electronic Structure Of Mos2 Nanotubes, Lingyun Xu
Electronic Structure Of Mos2 Nanotubes, Lingyun Xu
All Dissertations
First-principles methods enable one to study the electronic structure of solids, surfaces, or clusters as accurately as possible with moderate computational effort.
So we used a first-principles electronic structure method to calculate the electronic structure of free-standing layer of MoS2 with ABA and ABC stacking. Our results suggest MoS2 with ABA stacking which appears as an insulator has an energy gap of 1.64 eV. The covalent bonds between molybdenum and sulfur atoms are strong enough to form this gap. The ABC stacking will break the symmetry and becomes metallic. The valance and impurities calculations show the rigid-band picture …
Quantitative Methods And Detection Techniques In Hyperspectral Imaging Involving Medical And Other Applications, Ankita Roy
All Dissertations
This research using Hyperspectral imaging involves recognizing targets through spatial and spectral matching and spectral un-mixing of data ranging from remote sensing to medical imaging kernels for clinical studies based on Hyperspectral data-sets generated using the VFTHSI [Visible Fourier Transform Hyperspectral Imager], whose high resolution Si detector makes the analysis achievable. The research may be broadly classified into (I) A Physically Motivated Correlation Formalism (PMCF), which places both spatial and spectral data on an equivalent mathematical footing in the context of a specific Kernel and (II) An application in RF plasma specie detection during carbon nanotube growing process. (III) Hyperspectral …
Raman Spectroscopic Evidence For Anharmonic Phonon Lifetimes And Blueshifts In 1d Structures, Rahul Rao
Raman Spectroscopic Evidence For Anharmonic Phonon Lifetimes And Blueshifts In 1d Structures, Rahul Rao
All Dissertations
Anharmonic effects in two different quasi-1D systems were probed via micro-Raman spectroscopy. In the first system, we observed upshifts of peaks in the Raman spectra for b-Ga2O3 nanowires grown along the [110] growth direction compared those present in bulk b-Ga2O3. Contrary to our Raman studies on -Ga2O3 nanowires, downshifts in the Raman spectrum for b-Ga2O3 nanowires grown along [401] direction has also been reported by other research groups. We attribute these Raman shifts to the growth direction-induced lattice strains (compressive and tensile) present in the nanowires, and present a model based on the quasi-harmonic density functional theory to support our …
Poisson-Boltzmann Calculations Of Nonspecific Salt Effects On Protein-Protein Binding Free Energies, Claudia Bertonati, Barry Honig, Emil Alexov
Poisson-Boltzmann Calculations Of Nonspecific Salt Effects On Protein-Protein Binding Free Energies, Claudia Bertonati, Barry Honig, Emil Alexov
Publications
The salt dependence of the binding free energy of five protein-protein hetero-dimers and two homo-dimers/tetramers was calculated from numerical solutions to the Poisson-Boltzmann equation. Overall, the agreement with experimental values is very good. In all cases except one involving the highly charged lactoglobulin homo-dimer, increasing the salt concentration is found both experimentally and theoretically to decrease the binding affinity. To clarify the source of salt effects, the salt-dependent free energy of binding is partitioned into screening terms and to self-energy terms that involve the interaction of the charge distribution of a monomer with its own ion atmosphere. In six of …