Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Smectic (4)
- Chiral (2)
- Condensed Matter (2)
- De Vries (2)
- Liquid Crystal (2)
-
- Liquid crystal (2)
- Amorphous (1)
- Atomic physics (1)
- Biophysics (1)
- Bose-Einstein Condensate (1)
- Bragg Reflection (1)
- Bulk electroclinic effect (1)
- Carbon nanotube (1)
- Carrier Recombination (1)
- Chiral Dopants (1)
- Computational Physics (1)
- Critical point (1)
- Density Functional Theory (1)
- Doping (1)
- Drift Diffusion (1)
- Effect (1)
- Electrodynamics (1)
- Environmental testing (1)
- Field Effect Transistor (1)
- Gallium Nitride (1)
- Heterostructure (1)
- Indium Nitride (1)
- Jammed (1)
- Laser cooling (1)
- Light Absorption (1)
- Publication Type
Articles 1 - 14 of 14
Full-Text Articles in Physics
Rigid Aggregation Of Inclusions Embedded In Quasi 2d Fluids, Natalie Xochitl Ryan
Rigid Aggregation Of Inclusions Embedded In Quasi 2d Fluids, Natalie Xochitl Ryan
Physics
Diffusion is a transport process common in several biological systems. In this process particles of different species mix together through random (stochastic) motion at molecular length scales. Diffusion in fluids is unique as the coupling of the flow and fluid have been found to produce giant concentration fluctuations. The molecular length scale of these concentration fluctuations are magnitudes larger than the movement of the particles themselves, earning them the title “giant”. The diffusion of particles in bio-membranes displays a combination of 2D and 3D hydrodynamic properties; the movements of the particles are restricted to the plane of the membrane and …
Using Current-Voltage Characteristics To Probe The Transport Mechanism In Carbon Nanotube Networks, Alejandro Jimenez
Using Current-Voltage Characteristics To Probe The Transport Mechanism In Carbon Nanotube Networks, Alejandro Jimenez
Physics
Carbon nanotube (CNT) random networks have shown great promise in electronic applications. For example, they have been used as the active layer in thin film transistor biosensors and as electrodes in supercapacitors (Hu, 2010). Although CNT networks applications are numerous, some of the key details of their electrical behavior are not fully understood. In particular, it is known that the junctions between tubes in CNT networks play a key role in determining the sensing properties of the network (Thanihaichelvana, et al., 2018), however, the mechanism by which metallic-semiconducting (m-s) tube junctions affect the electrical sensing properties of the network is …
Pseudo Power Law Statistics In A Jammed, Amorphous Solid, Jacob Brian Hass
Pseudo Power Law Statistics In A Jammed, Amorphous Solid, Jacob Brian Hass
Physics
Simulations have shown that in many solid materials, rearrangements within the solid obey power-law statistics. A connection has been proposed between these statistics and the ability of a system to reach a limit cycle under cyclic driving. We study experimentally a 2D jammed solid that reaches such a limit cycle. Our solid consists of microscopic plastic beads adsorbed at an oil-water interface and cyclically sheared by a magnetically driven needle. We track each particles trajectory in the solid to identify rearrangements. By associating particles both spatially and temporally, we can measure the extent of each rearrangement. We study specifically the …
Simulating The Electrical Properties Of Random Carbon Nanotube Networks Using A Simple Model Based On Percolation Theory, Roberto Abril Valenzuela
Simulating The Electrical Properties Of Random Carbon Nanotube Networks Using A Simple Model Based On Percolation Theory, Roberto Abril Valenzuela
Physics
Carbon nanotubes (CNTs) have been subject to extensive research towards their possible applications in the world of nanoelectronics. The interest in carbon nanotubes originates from their unique variety of properties useful in nanoelectronic devices. One key feature of carbon nanotubes is that the chiral angle at which they are rolled determines whether the tube is metallic or semiconducting. Of main interest to this project are devices containing a thin film of randomly arranged carbon nanotubes, known as carbon nanotube networks. The presence of semiconducting tubes in a CNT network can lead to a switching effect when the film is electro-statically …
Critical Point Pairs For Smectic-A* - Smectic-C* Phase Transitions., Ted Cassirer
Critical Point Pairs For Smectic-A* - Smectic-C* Phase Transitions., Ted Cassirer
Physics
Liquid crystals is a class of materials possessing properties from both solids and fluids. Similar to solids the molecules arrange themselves in some sort of order. In the liquid crystal state there are multiple phases, smectic being one of them. In a smectic liquid crystal the molecules are aranged (along $z$) in layers. Of the smectic liquid crystals there exists different phases. In the smectic-A (Sm-A) phase the avarage tilt is $0$ relative to $z$ and in the Smectic-C (Sm-A) phase the avarage tilt is non-zero relative to $z$. Normally the liquid crystal will transition between the two phases by …
Environmental Testing Of Lasers For Jpl's Cold Atom Laboratory, Carey L. Baxter
Environmental Testing Of Lasers For Jpl's Cold Atom Laboratory, Carey L. Baxter
STAR Program Research Presentations
NASA’s Cold Atom Lab (CAL) is a multi-user facility designed to study ultra-cold quantum gases in the microgravity environment of the International Space Station (ISS). One of the main goals of CAL is to explore the unknown territory of extremely low temperatures—possibly as low as the picokelvin range!—where new and fascinating quantum phenomena can be observed. At such temperatures matter stops behaving as particles and instead becomes macroscopic matter waves. CAL will be remotely controlled to perform a multitude of experiments and is scheduled to launch in 2016. In order to anticipate problems that might occur during and post-launch, including …
Optical Properties Of De Vries Liquid Crystals And A Look At Ultra Thin Freely Suspended Smectic Films, Joshua P. Fankhauser
Optical Properties Of De Vries Liquid Crystals And A Look At Ultra Thin Freely Suspended Smectic Films, Joshua P. Fankhauser
Physics
Liquid crystals exist as a fourth state of matter. They are anisotropic and due to this order, they affect light that passes through them, making them ideal candidates for optical study. By employing a basic technique for measuring a liquid crystal's birefringence and tilt angle, one is able to study a number of other properties such as the electroclinic effect. In addition, smectic liquid crystals have been studied intently because of their ability to create stable ultra-thin films of quantized layer thickness. These thin films have been studied due to the fact that they are an ideal system for investigating …
Field Control Of The Surface Electroclinic Effect In Liquid Crystal Displays, Dana Hipolite
Field Control Of The Surface Electroclinic Effect In Liquid Crystal Displays, Dana Hipolite
Physics
Liquid crystals (LCs) are a fascinating class of materials exhibiting a range of phases intermediate between liquid and crystalline. Smectic LCs consist of elongated molecules arranged in a periodic stack (along z) of liquid like layers. In the smectic-A (Sm-A) phase, the average molecular long axis (director) points along z. In the smectic-C (Sm-C) phase, it is tilted relative to z, thus picking out a special direction within the layers. Typically, the Sm-A* to Sm- C* transition will occur as temperature is decreased. In chiral smectics (Sm-*A or Sm-C*) it is possible to induce director titling (i.e. the Sm-C* phase) …
Analysis Of An Unusual Liquid Crystal Phase Transition, Loni Ann Fuller
Analysis Of An Unusual Liquid Crystal Phase Transition, Loni Ann Fuller
Physics
Liquid crystals are a unique phase of matter that resemble a state between a solid and liquid. Within these properties, liquid crystal molecules have the ability to align and create layers. From this phenomenon, many electro-optical effects can be investigated, such as measuring the tilt angle between molecules at different temperatures and applied electric fields and also measuring the birefringence, which is a unique property of liquid crystals in which the index of refraction of the sample behaves differently along different axes. In order to better understand these electro- optical effects, we designed a more precise protocol of measuring this …
Density Functional Theory And The Calculation Of Tcmg2O4 Spinel Lattice Parameters, Jon Karlo Macias
Density Functional Theory And The Calculation Of Tcmg2O4 Spinel Lattice Parameters, Jon Karlo Macias
Physics
The cohesive energy, lattice constant and bulk modulus of two simple HCP crystal structures of magnesium and technetium were calculated using the vienna ab initio simulation package (VASP) which is based on density functional theory (DFT). The same properties were determined for TcMg2O4 spinel. The theoretical results of the lattice constant of the pure crystals were compared to experimental results and found to be in excellent agreement with a difference of less than 2%. The results for the lattice constant of the TcMg2O4 spinel were found to be in excellent agreement as well with …
The Effect Of Polarization And Ingan Quantum Well Shape In Multiple Quantum Well Light Emitting Diode Heterostructures, Patrick M. Mcbride
The Effect Of Polarization And Ingan Quantum Well Shape In Multiple Quantum Well Light Emitting Diode Heterostructures, Patrick M. Mcbride
Master's Theses
Previous research in InGaN/GaN light emitting diodes (LEDs) employing semi-classical drift-diffusion models has used reduced polarization constants without much physical explanantion. This paper investigates possible physical explanations for this effective polarization reduction in InGaN LEDs through the use of the simulation software SiLENSe. One major problem of current LED simulations is the assumption of perfectly discrete transitions between the quantum well (QW) and blocking layers when experiments have shown this to not be the case. The In concentration profile within InGaN multiple quantum well (MQW) devices shows much smoother and delayed transitions indicative of indium diffusion and drift during …
Experiments On De Vries Liquid Crystals: A Software Approach, Austin Havens
Experiments On De Vries Liquid Crystals: A Software Approach, Austin Havens
Physics
This paper describes two programs I developed to facilitate the study of liquid crystals. The first program is a graphical user interface to increase the accuracy of the birefringence measurements , which relates to their orientational order, by using a camera. The second program was designed to help study the effects of time varying fields on liquid crystals by matching data from a recorded video to oscilloscope data in order to attach data from image analysis to the voltage applied to the cell.
Search For Dark Matter Annihilation In M5, Daniel Jackson
Search For Dark Matter Annihilation In M5, Daniel Jackson
Physics
We analyzed the Messier 5 (M5) globular cluster for dark matter annihilation using data from VERITAS (Very Energetic Radiation Imaging Telescope Array System) to improve the flux upper limit previously done by Michael McCutecheon. We used updated software and lower energy thresholds. VERITAS consists of four ground-based gamma-ray telescopes located at the Fred Lawrence Whipple Observatory in southern Arizona. Thirty-five 20 minute observations of M5 from VERITAS are used in our analysis. The observations were collected from February to March in 2009, for a total exposure time of 10.63 hours. Gamma-rays from dark matter annihilation were not found,
but better …
Reflectivity Of A Cholesteric Liquid Crystal, Justin Lawson
Reflectivity Of A Cholesteric Liquid Crystal, Justin Lawson
Physics
In this paper we investigate the light properties of a chiral liquid crystal or a crystal for which the director angle relative to some fixed axis changes as a function of the crystal depth. Sometimes a dopant can introduce a chirality or "twist" in a nematic liquid crystal. For such cases of non-linear depth dependence (where chirality is determined by a diffusion equation) we may use this research to work backwards from a crystal's light properties to intensity and duration of dopant exposure.