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Alamethicin In Lipid Bilayers: Combined Use Of X-Ray Scattering And Md Simulations, Jianjun Pan, D. Peter Tieleman, John F. Nagle, Norbert Kučerka, Prof. Stephanie Tristram-Nagle Ph.D. 2016 Carnegie Mellon University

Alamethicin In Lipid Bilayers: Combined Use Of X-Ray Scattering And Md Simulations, Jianjun Pan, D. Peter Tieleman, John F. Nagle, Norbert Kučerka, Prof. Stephanie Tristram-Nagle Ph.D.

John Copeland Nagle

We study fully hydrated bilayers of two di-monounsaturated phospholipids diC18:1PC (DOPC) and diC22:1PC with varying amounts of alamethicin (Alm). We combine the use of X-ray diffuse scattering and molecular dynamics simulations to determine the orientation of alamethicin in model lipids. Comparison of the experimental and simulated form factors shows that Alm helices are inserted transmembrane at high humidity and high concentrations, in agreement with earlier results. The X-ray scattering data and the MD simulations agree that membrane thickness changes very little up to 1/10 Alm/ DOPC. In contrast, the X-ray data indicate that the thicker diC22:1PC ...


Low-Dimensional Materials For Organic Electronic Applications, Sumit Beniwal 2016 University of Nebraska-Lincoln

Low-Dimensional Materials For Organic Electronic Applications, Sumit Beniwal

Theses, Dissertations, and Student Research: Department of Physics and Astronomy

This thesis explores the self-assembly, surface interactions and electronic properties of functional molecules that have potential applications in electronics. Three classes of molecules - organic ferroelectric, spin-crossover complex, and molecules that assemble into a 2D semiconductor, have been studied through scanning tunneling microscopy and surfacesensitive spectroscopic methods. The scientific goal of this thesis is to understand the self-assembly of these molecules in low-dimensional (2D) configurations and the influence of substrate on their properties. First, a H-bonded organic ferroelectric, the 3-Hydroxyphenalenone, is studied on two noble metal substrates. It is demonstrated how a variety of different assemblies including 1D chains, p-p stacked ...


Vibrational And Structural Signatures Of The Crossover Between Dense Glassy And Sparse Gel-Like Attractive Colloidal Packings, Matthew A. Lohr, Tim Still, Raman Ganti, Matthew D. Gratale, Zoey S. Davidson, Kevin B. Aptowicz, Carl P. Goodrich, Daniel M. Sussman, A. G. Yodh 2016 University of Pennsylvania

Vibrational And Structural Signatures Of The Crossover Between Dense Glassy And Sparse Gel-Like Attractive Colloidal Packings, Matthew A. Lohr, Tim Still, Raman Ganti, Matthew D. Gratale, Zoey S. Davidson, Kevin B. Aptowicz, Carl P. Goodrich, Daniel M. Sussman, A. G. Yodh

Kevin Aptowicz

We investigate the vibrational modes of quasi-two-dimensional disordered colloidal packings of hard colloidal spheres with short-range attractions as a function of packing fraction. Certain properties of the vibrational density of states (vDOS) are shown to correlate with the density and structure of the samples (i.e., in sparsely versus densely packed samples). Specifically, a crossover from dense glassy to sparse gel-like states is suggested by an excess of phonon modes at low frequency and by a variation in the slope of the vDOS with frequency at low frequency. This change in phonon mode distribution is demonstrated to arise largely from ...


Preparation And Characterization Of Van Der Waals Heterostructures, Horacio Coy Diaz 2016 University of South Florida

Preparation And Characterization Of Van Der Waals Heterostructures, Horacio Coy Diaz

Graduate Theses and Dissertations

In this dissertation different van der Waals heterostructures such as graphene-MoS2 and MoTe2-MoS2 were prepared and characterized. In the first heterostructure, polycrystalline graphene was synthesized by chemical vapor deposition and transferred on top of MoS2 single crystal. In the second heterostructure, MoTe2 monolayers were deposited on MoS2 by molecular beam epitaxy.

Characterization of graphene-MoS2 heterostructures was conducted by spin and angle resolve spectroscopy which showed that the electronic structure of the bulk MoS2 and graphene in this van der Waals heterostructures is modified. For MoS2 underneath the graphene, a band structure renormalization and spin polarization are observed. The band structure ...


Raman Scattering And Anomalous Stokes–Anti-Stokes Ratio In Mote2 Atomic Layers, Yan Jun 2016 University of Massachusetts Amherst

Raman Scattering And Anomalous Stokes–Anti-Stokes Ratio In Mote2 Atomic Layers, Yan Jun

Jun Yan

Stokes and anti-Stokes Raman scattering are performed on atomic layers of hexagonal molybdenum
ditelluride (MoTe2), a prototypical transition metal dichalcogenide (TMDC) semiconductor. The data
reveal all six types of zone center optical phonons, along with their corresponding Davydov splittings,
which have been challenging to see in other TMDCs. We discover that the anti-Stokes Raman intensity
of the low energy layer-breathing mode becomes more intense than the Stokes peak under certain
experimental conditions, and find the effect to be tunable by excitation frequency and number of
atomic layers. These observations are interpreted as a result of resonance effects arising from the ...


Classical Transport In Disordered Systems, Antonios Papaioannou 2016 Graduate Center, City University of New York

Classical Transport In Disordered Systems, Antonios Papaioannou

All Graduate Works by Year: Dissertations, Theses, and Capstone Projects

This thesis reports on the manifestation of structural disorder on molecular transport and it consists of two parts. Part I discusses the relations between classical transport and the underlying structural complexity of the system. Both types of molecular diffusion, namely Gaussian and non-Gaussian are presented and the relevant time regimes are discussed. In addition the concept of structural universality is introduced and connected with the diffusion metrics. One of the most robust techniques for measuring molecular mean square displacements is magnetic resonance. This method requires encoding and subsequently reading out after an experimentally controlled time, a phase ϕ to the ...


Modeling The Behavior Of The Graphene To Liquid Interfaces In An Electrolytic Liquid, Caitlin Duffner 2016 Linfield College

Modeling The Behavior Of The Graphene To Liquid Interfaces In An Electrolytic Liquid, Caitlin Duffner

Senior Theses

Understanding the mechanism for charge transfer between a graphene biosensor and its electrodes within an electrolyte solution is vital to better understand the sources of electrical noise in the system. By measuring the effective resistance and capacitance of the system at different frequencies, it is possible to develop a circuit model of the system's electrical behavior. This model provides a deeper understanding of the fundamental interactions that occur in a top-­gated graphene device and provides opportunities to improve a signal. To reduce noise created at the liquid to graphene interface, a buffer layer of Yttrium Oxide was applied ...


Effect Of Electrolyte Concentration On The Capacitance And Mobility Of Graphene, Flint A. Martino 2016 Linfield College

Effect Of Electrolyte Concentration On The Capacitance And Mobility Of Graphene, Flint A. Martino

Senior Theses

The use of graphene field-effect transistors as a biosensor is increasingly being used to study biological phenomena, due to the sensitivity and low reactivity of graphene. To further improve sensitivity in biological environments, we examined how different salt concentrations affect the mobility of capacitance of the graphene. Samples were also measured after an annealing process. We report on the positive correlation between sensitivity and electrolyte concentration and speculate on methods to improve future detectors. Mobility of the device was found to change from 1.07*103cm2/ (V*s) in de-ionized water to 2.78*103cm ...


Reflective Efficiencies Of Materials For Applications Of Bifacial Solar Cells, Michael Metter 2016 Linfield College

Reflective Efficiencies Of Materials For Applications Of Bifacial Solar Cells, Michael Metter

Senior Theses

The bifacial solar cell is superior to its monofacial predecessor due to its ability to convert both incident light on top and reflected light from below into energy. The scattering of the reflected light is affected by the property of the material on which it is interacting. To date, little work has been contributed to studying the properties of these materials to determine optimal quantities for bifacial solar cells. In the first experiment, reflective efficiencies compared to the angle of reflection were explored for different grit of sandpaper in order to develop an understanding of how surface texture impacts reflectivity ...


Searching To Distinguish Defects And The Presence Of Negative Capacitance, Thaddeus Cox 2016 Linfield College

Searching To Distinguish Defects And The Presence Of Negative Capacitance, Thaddeus Cox

Senior Theses

In the search for solar cells with lower manufacturing costs, thin film technology was developed. These thin films are only micrometers thick and are grown at relatively low temperatures, resulting in films with imperfections known as defects. Defects can cause thin film solar cells to have lower efficiencies than their single crystalline counterparts. In order to create more efficient thin film solar cells the physical mechanisms behind defects need to be investigated by sensitive techniques. Capacitance measurements of solar cells detect minute changes in charge in the material. For that reason, capacitance is used to electrically characterize the solar cell ...


Ferromagnetic Resonance Studies Of Coupled Magnetic Systems, Daniel J. Adams 2016 University of New Orleans

Ferromagnetic Resonance Studies Of Coupled Magnetic Systems, Daniel J. Adams

University of New Orleans Theses and Dissertations

The high-frequency properties of coupled magnetic systems have been investigated using vector network analyzer ferromagnetic resonance (VNA-FMR) spectroscopy. SAF structures consist of two ferromagnetic layers separated by a non-magnetic spacer, coupled through the indirect exchange interaction. The ferromagnetic layers of our samples were composed of FeCoB separated by a layer of Ru. The thickness of Ru was varied in the range of 8 to 18 Å among the samples studied. Antiferromagnetic coupling can be quickly identified by the major hysteresis loop (MHL).

A new way of displaying FMR data for these trilayer samples is presented which completely preserves the anisotropy ...


Giant Enhancement Of Magnetic Anisotropy In Ultrathin Manganite Films Via Nanoscale 1d Periodic Depth Modulation, A. Rajapitamahuni, L. Zhang, Mark A Koten, V. R. Singh, J. D. Burton, Evgeny Y. Tsymbal, Jeffrey E. Shield, Xia Hong 2016 University of Nebraska - Lincoln

Giant Enhancement Of Magnetic Anisotropy In Ultrathin Manganite Films Via Nanoscale 1d Periodic Depth Modulation, A. Rajapitamahuni, L. Zhang, Mark A Koten, V. R. Singh, J. D. Burton, Evgeny Y. Tsymbal, Jeffrey E. Shield, Xia Hong

Evgeny Tsymbal Publications

The relatively low magnetocrystalline anisotropy (MCA) in strongly correlated manganites (La,Sr)MnO3 has been a major hurdle for implementing them in spintronic applications. Here we report an unusual, giant enhancement of in-plane MCA in 6 nm La0.67Sr0.33MnO3 (LSMO) films grown on (001) SrTiO3 substrates when the top 2 nm is patterned into periodic stripes of 100 or 200 nm width. Planar Hall effect measurements reveal an emergent uniaxial anisotropy superimposed on one of the original biaxial easy axes for unpatterned LSMO along (110) directions, with a 50-fold enhanced anisotropy energy ...


Synthesis, Characterization, And Electronic Properties Of Novel 2d Materials : Transition Metal Dichalcogenides And Phosphorene., George Anderson 2016 university of louisville

Synthesis, Characterization, And Electronic Properties Of Novel 2d Materials : Transition Metal Dichalcogenides And Phosphorene., George Anderson

Electronic Theses and Dissertations

Scaling electronic devices has become paramount. The current work builds upon scaling efforts by developing novel synthesis methods and next generation sensing devices based on 2D materials. A new combination method utilizing thermal evaporation and chemical vapor deposition was developed and analyzed to show the possibilities of Transition Metal Dichalcogenide monolayers and heterostructures. The materials produced from the above process showed high degrees of compositional control in both spatial dimensions and chemical structure. Characterization shows controlled fabrication of heterostructures, which may pave the way for future band gap engineering possibilities. In addition, Phosphorene based field effect transistors, photodetectors, and gas ...


Breakdown Analysis Of Electrostatic Discharge, Sam Hansen, Allen Andersen, JR Dennison 2016 Utah State University

Breakdown Analysis Of Electrostatic Discharge, Sam Hansen, Allen Andersen, Jr Dennison

Allen Andersen

Electrostatic discharge (ESD) and the associated material breakdown is the primary cause for spacecraft damage due to space environment interactions. This phenomenon occurs when the space plasma fluxes charge a craft to high voltages where insulating materials then break down. This failure allows current to flow freely through the material which; can damage or destroy onboard electrical systems. My work focuses on the effects of these breakdowns on suspect materials commonly used for electrical insulation in space. The USU Material Physics Group has performed ESD tests on hundreds of samples to date. The ESD damage sites of these samples have ...


Thermal Analysis Of Borosilicate Glass For Its Biological Applications, Gregory Humble 2016 Southern Polytechnic State University

Thermal Analysis Of Borosilicate Glass For Its Biological Applications, Gregory Humble

Symposium of Student Scholars

Borosilicate glass doped with varying wt% of cerium oxide is investigated for biological applications. Thermal studies of each formulation were conducted using an SDT Q600 differential scanning calorimeter. 30mg samples of 350 - 425 μm particle size of each type of glass were heated to 1200°C in order to obtain the glass transition, crystallization, and melting temperatures. Samples were then heated to 900°C at several heating rates, ranging from 2°C/min to 100°C/min, then compared against each other as well as against an undoped borosilicate glass.


Simulation Of Heterogeneous Colloidal Particles Immersed In Liquid Crystals, Setarehalsadat Changizrezaei 2016 The University of Western Ontario

Simulation Of Heterogeneous Colloidal Particles Immersed In Liquid Crystals, Setarehalsadat Changizrezaei

Electronic Thesis and Dissertation Repository

This thesis describes an investigation of interactions between colloidal particles immersed in a liquid crystal. The presence of colloidal particles in the liquid crystal distorts the director field distorted from its uniform orientation. These elastic distortions produce topological defects around the particles, which induce anisotropic interactions between them, and these anisotropic interactions can be used to manufacture non-closed packed colloidal crystals, such as diamond lattices, which are interesting in photonic applications. First, different types of liquid crystals, the mathematical tools to describe the anisotropic nature of liquid crystals, the Landau-de Gennes free-energy model to investigate the particle’s interaction, and ...


On The Structural Origin Of The Single-Ion Magnetic Anisotropy In Lufeo3, Shi Cao, Xiaozhe Zhang, Tula R. Paudel, Kishan Sinha, Xiao Wang, Xuanyuan Jiang, Wenbin Wang, Stuart Brutsche, Jian Wang, Philip J. Ryan, Jong-Woo Kim, Xuemei Cheng, Evgeny Y. Tsymbal, Peter A. Dowben, X. S. Xu 2016 University of Nebraska-Lincoln

On The Structural Origin Of The Single-Ion Magnetic Anisotropy In Lufeo3, Shi Cao, Xiaozhe Zhang, Tula R. Paudel, Kishan Sinha, Xiao Wang, Xuanyuan Jiang, Wenbin Wang, Stuart Brutsche, Jian Wang, Philip J. Ryan, Jong-Woo Kim, Xuemei Cheng, Evgeny Y. Tsymbal, Peter A. Dowben, X. S. Xu

Evgeny Tsymbal Publications

Electronic structures for the conduction bands of both hexagonal and orthorhombic LuFeO3 thin films have been measured using x-ray absorption spectroscopy at oxygen K (O K) edge. Dramatic differences in both the spectra shape and the linear dichroism are observed. These differences in the spectra can be explained using the differences in crystal field splitting of the metal (Fe and Lu) electronic states and the differences in O 2p-Fe 3d and O 2p-Lu 5d hybridizations. While the oxidation states has not changed, the spectra are sensitive to the changes in the local environments of the Fe3+ and Lu ...


Isotope Effect On Electron-Phonon Interaction In Multiband Superconductor Mgb2, Adam Kaminski, Daixiang Mou, Paul C. Canfield, Serguei Budko, Lunan Huang, Valentin Taufour, Yun Wu, Soham Manni 2016 Ames Laboratory

Isotope Effect On Electron-Phonon Interaction In Multiband Superconductor Mgb2, Adam Kaminski, Daixiang Mou, Paul C. Canfield, Serguei Budko, Lunan Huang, Valentin Taufour, Yun Wu, Soham Manni

Ames Laboratory Datasets

We investigate the effect of isotope substitution on electron-phonon interaction in multi-band superconductor MgB$_2$ using tunable laser based Angle Resolved Photoemission Spectroscopy. The kink structure around 70 meV in Sigma band, which is caused by electron coupling to E_2g phonon mode, is shifted to higher binding energy by ~3.5 meV in Mg^10B2. The changes of the kink energy reported here suggest that the anharmonicity of the E2g phonon in MgB2 is very small, which reopens the debate about the unusually small isotope coefficient in this material. These results are the benchmark for investigation of isotope effect in ...


Intramolecular Cross-Linking Of Beta Subunits And Pegylation Of Bovine Stroma Free Hemoglobin For Use As A Hemoglobin Based Oxygen Carrier, Gil Salazar 2016 Georgia Southern University

Intramolecular Cross-Linking Of Beta Subunits And Pegylation Of Bovine Stroma Free Hemoglobin For Use As A Hemoglobin Based Oxygen Carrier, Gil Salazar

Georgia Southern University Research Symposium

Purified Bovine Stroma-Free Hemoglobin's (BSFHb) two beta subunits where intramolecularly cross-linked (BXLHb) using bis(3,5-dibromosalicyl) fumarate (DBBF) and further modified with Polyethylene glycol (BPEGXLHb) for possible use as a Hemoglobin Based Oxygen Carrier (HBOC). Each stage of modification was characterized by size exclusion chromatography and fluorescence methods. We prepared several different molar ratios of DBBF and BSFHb to acquire the highest yield of BXLHb. Cross-linking of the beta subunits will stabilize the whole Hb tetramer from dissociation and prevent unwanted degradation of the HBOC. We prepared a sample modified with PEG (PEGylation) that had a molecular weight of ...


Uv Degradation Effects: Terrestrial Versus Space Environment, Katie Gamaunt, Krysta Moser, Alex Souvall, JR Dennison 2016 Utah State University

Uv Degradation Effects: Terrestrial Versus Space Environment, Katie Gamaunt, Krysta Moser, Alex Souvall, Jr Dennison

Posters

The decrease in visible and ultraviolet transmission spectra of polymeric and glass spacecraft materials has been measured to determine the extent of degradation due to high energy UV radiation similar to the solar spectrum (both above and below the stratosphere). This project looked at the effects that the atmosphere has in regards to blocking UV radiation and thus, slowing down the UV degradation process. Materials such as quartz, borosilicate glass, sodium glasses, polyethylene, polyimide, and polyethylene terephthalate polymers were exposed to radiation from a focused high intensity deuterium lamp source, which generates radiation in the UVA and UVB spectrum. Duplicates ...


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