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Phillip Durachinsky with Timothy Atherton and Robert Brown

Simulating the Self-Assembly of Magnetic Nanoparticles

Magnetic nanoparticles are a functional material with many potential applications, including medical imaging. Due to their magnetic properties, they can self-assemble in solution into a variety of structures when a magnetic field is applied. One imaging modality that has been proposed is Magnetic Particle Imaging (MPI), which detects the nonlinear response of the particles to an applied radio-frequency magnetic field. The self-assembled structures have been produced experimentally, with techniques and results published. However, a nanoscopic theoretical description of the particles and their agglomeration has not been developed, and is essential for optimizing materials. The goal of this project is to develop a particle based simulation capable of predicting the phase diagrams of these self-assembled structures based on parameters such as the applied magnetic field strength and concentration. These predictions will be compared with experimental data. Ultimately, we would like to extend the simulation to calculate the signal produced by an MPI machine directly.

* Prof. Atherton has left CWRU for Tufts Univ., June, 2011

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Bill Flaherty with Glenn Starkman

Accounting for the sun's gravity in dark matter detection

      Dark matter is thought to compose a large fraction of the energy density of the universe, and in particular of our galaxy. The favored candidate for dark matter is weakly interacting massive particles (WIMPs), particles tens to hundreds of times the mass of ordinary protons and neutrons and that would be streaming through our solar system. Scientists have built and are building detectors to look for such WIMPs passing through the Earth. An important factor in determining the signal of the WIMPs is their velocity distribution. Various models for the velocity distribution of WIMPs in the Galaxy have been used. It has also been noted that as the earth moves around the sun, the velocity of the Earth through the galaxy either adds to the sun's or subtracts from it, depending on the time of year. This modulates the actual velocity distribution of the WIMPS passing through the Earth, and our detectors. Surprisingly, the fact that as the WIMPs approach the Earth they must fall deep into the Sun's gravitational potential well has not apparently been taken into account in determining the WIMPs' velocity distribution. Since that should cause an approximately few to ten percent change in the WIMP velocity it is not a negligible effect. In particular since it will increase the velocity of the fastest WIMPs, it should increase the detectability of WIMPs. It may also increase the detectability of the annual modulation of the WIMP signal as the Earth moves around the sun. Our plan is first to calculate the effect of falling into the Sun's gravitational well on the WIMP velocity distribution as seen by an observer on the Earth, and then, to determine the influence on dark matter detector signals.

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Wesley Gould with Philip Taylor

The effects of flexible side chains on the behavior of ions within a Nafion membrane

      NafionTM membranes have been known for years to hold potential for use in hydrogen fuel cells, as well as in some battery technologies. Currently the inner workings of NafionTM , as used in fuels cells, are not as well understood as would be desired. The water channel model has NafionTM forming parallel networks of approximately cylindrical pores about 2 nm in radius. In previous work, Gould and Taylor simulated the ion concentration and electric potential within these pores and compared them against theoretical predictions. These simulations were done with sulfonate groups arranged in a fixed lattice grid that was not allowed to move. The new work that we propose for the Senior Project is to extend our previous work and to compare it with the recent theoretical predictions of Berg and Findlay [1] The extensions will involve adding the effects of flexible side chains on the behavior of ions within a Nafion membrane. The sulfonates will then no longer be in fixed positions. We also propose to model the current of ions under various conditions of proton concentration gradient and applied field.

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Jessica Marie Hatch with Roger Quinn, Dept. of Mechanical and Aerospace Engineering

Model of Neural Networks: Centralized Pattern Generator Comparator

      Dr. Roger Quinn's robotic's laboratory is creating a robot controller capable of gait control and adaptation based on biological principles. In order to create mechanical analogues of biological systems, accurate physical and neural models are needed. These systems consist of a complex network of muscles, sensors and sensory neurons, interneurons, and centralized pattern generators (CPG). There is biological evidence to suggest that there is a spinal CPG (the origin of the desired signal) that works in conjunction with the output CPG (modulated by all the sensory signals and directly in control of the muscles) through a comparator element that makes corrections using a proportional-derivative type controller. In the simple case the model takes one signal input and compares that to the desired signal using the CPGs. The output of the comparator is the error between the two signals and corrections are then sent back to the muscles. The goal of this project will be to create a dynamic model the CPG Comparator by investigating combinations of control responses in order to optimize behavior and performance. Ultimately, we would like to have inputs at the low-level from multiple receptors and incorporate filters as part of the CPG Comparator.

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Jason Jones with Robert Deissler and Robert Brown

Studying the Magnetic and Optical Properties of Malaria for Use in Early Detection

When the Malaria parasite ingests the hemoglobin of the red blood cell, it sequesters the toxic iron inside of its abdominal vacuole for safety. The iron atoms reside in a carbon structure to make up the hemozoin crystals. The iron structure of the hemozoin form thin needle shapes, leading to a noticeable paramagnetism. This project will study the effect of magnetic fields on the alignment of the hemozoin. Hemozoin blood samples will be subjected to a polarized laser beam in combination with a time-varying external magnetic field produced by moving magnets. Using the optical dichroism of the aligned crystals, the relationship between the magnetic field strength, the polarization of the laser and the transmitted intensity will be investigated. A goal of the project is to develop a detection device sensitive to the concentration levels relevant to infected blood.

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Peter Lee with Colleen Croniger, Dept. of Nutrition

Genetic Factors in the Progression of Liver Fibrosis

Alcoholic liver disease (ALD) is the leading cause of illness and death from liver complications in the United States. Specifically, alcoholic steatohepatitis (ASH) is a type of liver disease characterized by the accumulation of fat in liver (steatosis) in conjunction with liver inflammation (hepatitis). Previous studies have provided evidence to suggest that the development and progression of ASH is a polygenic disease, involving multiple genetic and environmental risk factors. To develop a better understanding of the factors involved with ASH, we have determined a candidate gene modulating liver fibrosis, Nlrc4. In this project, we will be using mutant mice and cell lines to examine severity of liver damage under various conditions. Liver damage is evaluated using multiple factors, including quantitative analysis of qPCR data, gene expression values, and various enzyme assays. Determining the roles of Nlrc4 in the progression of ASH may provide valuable targets for future medical treatment of alcoholic liver disease.

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Joseph Lesnefsky with Rolfe Petschek

Optimization of the Static First Hyperpolarizibility of One or Many Non-Interacting Fermions in One Dimension

Large non-linear electronic polarizabilities would be advantageous for a variety of devices and have been intensely studied for around three decades. This project will examine theoretical limits on the static first non-linear electronic susceptibility of a material, β, known as the hyperpolarizability. Kuzyk et. al [1] suggests that there is a theoretical maximum to the hyperpolarizability of N fermions. Numerical optimizations for a single fermion in a one-dimensional potential [1,2] strongly suggest that the actual value converges to 0.708951 times the theoretical limit. We will continue the study of a single electron problem [2] by modeling the potential starting from the simple quantum harmonic oscillator (SHO) and modifying the Hamiltonian with linear combinations of Hermite polynomials to maximize the hyperpolarizability. We will then examine the Hessian curvature near the maximum to deduce what parts of the wave function and the potential are integral to attaining this maximized hyperpolarizability. The hyperpolarizability for multiple non-interacting fermions will then be investigated using similar techniques. This may suggest significantly stronger limits on the hyperpolarizability of many electron systems.

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Elizabeth McNany with Corbin Covault

Properties of Cosmic Ray Air Showers as Measured by a Prototype Cherekov Detector System

When high energy cosmic rays interact with the upper atmosphere, a shower of particles is created that generate Cherenkov radiation as their travel towards the surface of the earth. To study this radiation, a new prototype detector has been constructed with four scintillation panels and a central photomultiplier tube to detect the visible Cherenkov light. This detector will be deployed so as to collect data from real cosmic ray particle showers in the field. The results collected from this detector will be compared in detail to a computer simulation that has been designed to predict the measured properties of air showers and Cherenkov radiation. The simulation will predict the distribution of incoming particles, taking into account various sources, directions, and energies of particles corresponding to individual cosmic rays. By comparing the output to actual results we may verify the operation of our prototype. These results will ultimately be used to design and fabricate a larger detector system that can be used to study the the astrophysical origin of the cosmic rays.

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Matthew McPheeters with Andrew Rollins and Michael Jenkins, Dept. of Biomedical Engineering

Optical Mapping of Embryonic Heart Electrophysiology

Optical Mapping is a powerful technique used to map conduction in the heart, and has recently been proven in the embryonic heart. A voltage-sensitive fluorescent dye is used to visualize changes in membrane potential. A high-speed CCD camera must be used in order to achieve good temporal sampling of the upstroke of the action potential, but also causes the fluorescent signal detected with each pixel to be small compared to background. We will post-process our image data because of the resulting low SNR. After normalizing and filtering the data, we will extract various measurements, including action potential durations, activation maps and conduction velocity vectors.

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Lauren Nicholson with Idit Zehavi, Dept. of Astronomy

A Zoo of Galaxies

I will be investigating and quantifying the morphological properties of a group of strongly clustered galaxies found in the Galaxy Zoo project and the Sloan Digital Sky Survey's Data Release 7. Galaxy Zoo is an interactive project that utilizes the public to classify the millions of galaxies found in the SDSS, which I can use to pair the observations of the galaxies with the data that is normally considered in order to learn more about these faint red smudges. I will also be working with the Shafran Planetarium at the Cleveland Museum of Natural History, designing and encoding a planetarium show using the Galaxy Zoo project and results.

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Eric Nied with Charles Rosenblatt

Rayleigh-Taylor Instability for At~1

The Rayleigh-Taylor instability occurs when a dense fluid falls into a less dense fluid under the influence of gravity. Understanding its evolution through time can help us better understand how immiscible fluids interact. However, most research previously performed concerning the Rayleigh-Taylor instability has been at low Atwood Numbers (At < 0.3) and suffered from the problems of jitter due to the difficulty of establishing initial conditions in the presence of Earth's gravity. In this experiment I will aim for an Atwood Number approximately equal to 1 by levitating a magnetically permeable liquid solution above air. I will then induce a perturbation at the fluid interface before allowing the RT instability to take its course. My objectives are to measure quantitatively the growth rate of the fastest growing wave vector while the instability is in the linear regime, and observe the long-time behavior in the non-linear regime. I will also touch on other issues such as perfection of experimental design for future work.

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Ravin Pandey with Harsh Mathur

Dynamics of the q-model

The q-model was introduced by Coppersmith et al. to simulate how force distributes through bead packs. Closely related models have been used to describe river networks, quantum Hall multilayers and other problems of non-equilibrium statistical mechanics. Previous work has shown that the q-model has a critical point, and, close to the critical point, exhibits scaling behavior analogous to thermodynamical critical phenomena. Lewandowska et al. obtained the dynamics of the entire distribution right at the critical point and made a scaling hypothesis about the form of this distribution close to the critical point. In this project we will study the dynamics of the entire distribution of load on a single bead by analytic

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Sam Richardson with Dr. Roger H. French, Dept. of Materials Science and Engineering

Laser light scattering for characterization of degradation of photovoltaic materials and mirrors

Angle resolved laser light scattering, to determine the power spectral density, and the spatial frequencies of surface roughness involved in light scattering in photovoltaic systems represents a new tool to characterize environmental degradation. Using bidirectional reflectance and transmission distribution functions (BRDF and BTDF), one can quantitatively observe changes in surface scattering in PV materials and components. The goal of this project will be to perform BRDF measurements on a variety of PV materials and components, with differing amounts of solar or environmental exposure, and then extract quantitiative insights from the changes in the power spectral density of the BRDF, into the length scales and characteristics of surface structure. These can then also be quantitatively used in computational optics modeling to reproduce the resulting optical effects arising from surface structural changes.

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Andrew Richenderfer with Xuan Gao

Exfoliation of Graphene

Graphene has a molecular structure made up of one single layer of carbon atoms in a honeycomb formation, and is the first two-dimensional (2D) crystalline material identified. It is of significant research interest as it possesses a range of exceptional and potentially beneficial properties such as mechanical strength, electrical and thermal properties and unusual quantum effects. The biggest challenge facing graphene towards application is the availability of the material and the lack of synthesis method on any reasonable scale. The objective of this project is to explore new methods besides the mechanical exfoliation ('Scotch tape' method) to extract graphene from commercially available graphite products such as pyrolytic graphite (PG) or highly ordered thermal pyrolytic graphite (TPG). The electrical transport quality of the exfoliated single layer or few layer graphene will be studied by field effect transistor characterization.

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Andrew Ruesch with Daniel S.Akerib and Thomas Shutt

Titanium Spark Purifier for Xenon

Dark matter is one of the most pressing mysteries of modern science. One of the current experiments, which is expected to put a new lower limit on scattering cross-section vs. WIMP mass, is the dark matter detector designed and run by the LUX collaboration, of which Case is a member. This detector is a two-phase liquid xenon detector, which relies on scintillation events in order to detect WIMPS, the most promising of the proposed dark matter particles. In order to do this, the xenon must be ultra pure. The xenon is currently purified on site using a commercial getter, the SAES MonoTorr, but it would be beneficial to have a simple way to cost-effectively purify the xenon in situ. The proposed spark purifier, combined with a pump and filtration system, would be designed to fit inside the detector and could be used to continuously purify the xenon, thus ensuring the best possible conditions at all times. Though the xenon is pure when it is introduced into the detector and great care is taken to keep the detector parts clean during assembly, there are plastics in the system that off-gas and present a continual source of contamination, hence the need to regular purify the xenon The spark purifier consists of two electrodes that are placed in the xenon to be purified (which will be in the gaseous phase for purification). A circuit charges a capacitor, which then discharges a spark from one electrode to the other, and in the process spatters titanium dust inside the chamber. The titanium dust chemically attracts impurities, which can then be filtered out. Additionally, the sparking process produces UV light which breaks down organic molecules, thereby enhancing the purification process. The titanium spark purifier has been previously used successfully with a detector similar to LUX, though the literature on the subject is not very extensive. To our knowledge, a spark purifier system has not been deployed directly in a detector with the same specific low radioactivity and other mechanical constraints as LUX. The overall goal of this work is to (a) develop the spark chamber and demonstrate production of Ti dust with an efficiency comparable to that described in the literature and (b) develop a method for capturing and filtering the Ti dust and, (c), time permitting, combine the spark chamber, pump, and filter into a fully working system.

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Matthew Sheffield with Charles Rosenblatt

Chiral Properties of Carbon Nanotubes in a Liquid Crystal

In the field of Liquid Crystals (LCs), when mixing equal portions of left-handed and right-handed chiral solutions, a racemic solution is produced, as expected. However, when adding a supposedly racemic solution of carbon nanotubes (CNT) to a LC solution, an unexpected chirality appears in the CNT-LC mixture. In order to explore this peculiar circumstance, I will measure the optical rotatory power of the CNT-LC mixture as a function of temperature in the isotropic LC phase. The temperature will be lowered toward the nematic phase transition to observe the pre-transitional behavior of the optical-rotatory power. By measuring the optical-rotatory power of the CNT-LC, one can gain an understanding of how the net chirality of the CNTs is transmitted to the liquid crystal.

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Gregory Stewart with Walter Lambrecht

Calculate the full Raman Spectrum and Infrared Spectrum of Vanadium Pentoxide (V2O5)

Vanadium pentoxide is a layered material from which possibly monolayers could be fabricated in similar way as graphene. The purpose of this project is to theoretically explore if this would be of any interest: e.g. are there interesting changes in the band structure or vibrational properties? The ABINIT software will be used to calculate the difference between the mono-layer and full crystal electronic band structures and vibrational normal modes (phonons) in Vanadium Pentoxide. Eventually the calculations can be extended to calculate the full Raman spectrum and infrared spectrum to compare with currently available experimental data in the literature and preliminary data on thin layers in Prof. Jie Shan's group.

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Vijay Edwin with Philip Feng, Dept. of Electrical Engineering and Computer Science

Exploring the Physics and Engineering of Drum Vibrations for a New Drum Trigging Technology

Currently drum triggering technology works by using piezoelectric transducers to generate a voltage when a pad of mesh material is struck. The appropriate tones are then generated by external hardware from the piezo output signal and sent to an amplifier. While sound quality has steadily been improving over the last 30 years many drummers complain that the drums do not "feel" like acoustic drums even though they produce high quality drum sounds. This project aims to design a digital drum triggering system that captures information about stick force and the position of the hit on the drumhead and incorporate this into an algorithm that then triggers a drum sample that more accurately characterizes how the hit would have sounded on an acoustic drum. The new system incorporates information about how hard the hand moves the drumstick, this being done using an accelerometer mounted directly to the stick. This will generate a varying waveform that would indicate how hard the drum is being played. The piezoelectric sensors would be placed on various parts of the drumhead and would be used to extract information about the duration, and location of the hit on the drumhead. This information would be used to trigger the appropriate sample of a hit of an acoustic drum during signal processing. Both sensors would feed to an A/D converter and processing will occur using various DSP chips if possible or a separate piece of software. Depending on the sensitivity of the accelerometer a very wide range drum sounds from full force hit to light taps could possibly be triggered as a given sample would be chosen using information extracted from the motion of the stick as well as location of contact with the drum. This would hopefully result in a more responsive electronic drum.

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Jacob Wagner with João Maia, Dept. of Macromolecular Science and Engneering

Simulation of Droplet Breakup by dissipative particle dynamics (DPD)

Coarse grained (CG) simulation methods, such as CG molecular dynamics and Stokesian dynamics, are normally used to gain a better understanding of mesoscopic phenomena. Hoogerbrugge and Koelman proposed a new simulation method called Dissipative Particle Dynamics (DPD) in 1992, which has a variety of applications, including Newtonian fluids, colloidal suspensions, emulsion, polymer solutions, polymer melts, polymer blend, diblock copolymer, polymer nano-composites, and so on. Recently, shear thickening of dense colloidal suspension have been reported by resorting to core-potential. As to polymeric systems, phase separation of polymer blend and diblock copolymer is reasonably reproduced, whereas the dynamics of polymer chains of polymer melts cannot be reproduced well due to soft potential used in DPD. Entanglement forces have been considered for entanglement effect, which should be the key for dynamics. Lahmar et al. recently proposed a simulation DPD method coupled with Monte Carlo (MC) method that provides Gaussian statistics and 3.2-power law on viscosity, which are reasonable, but shows unphysical properties such as non-Gaussian bond length distribution and no sign of entangled structures in the radius of gyration. This thesis will apply a new DPD simulation method recently developed by the Maia group [1], whose coarse-grained level is tunable, to capture the Physics of droplet break-up in micro- and nano-emulsions. We will focus on the interplay between droplet size and the stress level in shear and extensional flows to determine the break-up dynamics and will try, in particular, to correctly predict computationally the well-known Grace plot.

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Bryan T. Weinstein with Jesse Berezovsky

Simulating Magnetization Dynamics of Ferromagnetic Vortices

Using the "Object Oriented Micro-Magnetic Framework" (OOMMF), we will show that ferromagnetic vortices naturally create localized magnetic fields capable of inducing "Electron Spin Resonance" (ESR). To determine how to control the vortices' magnetic fields, we will study their magnetization dynamics in response to static and time-varying external fields. Using this information, we hope to control electron spins in neighboring semiconductor structures. Future technologies will be able to use this data to create ferromagnetic vortexes to induce ESR and thus control and communicate between electrons.