Radiation Damage and Recovery Properties of Common Plastics PEN (Polyethylene Naphthalate) and PET (Polyethylene Terephthalate) Using a 137Cs Gamma Ray Source Up To 1 MRad and 10 MRad

Polyethylene naphthalate (PEN) and polyethylene teraphthalate (PET) are cheap and common polyester plastics used throughout the world in the manufacturing of bottled drinks, containers for foodstuffs, and fibers used in clothing. These plastics are also known organic scintillators with very good scintillation properties. As particle physics experiments increase in energy and particle flux density, so does radiation exposure to detector materials. It is therefore important that scintillators be tested for radiation tolerance at these generally unheard of doses. We tested samples of PEN and PET using laser stimulated emission on separate tiles exposed to 1 MRad and 10 MRad gamma rays with a 137Cs source. PEN exposed to 1 MRad and 10 MRad emit 71.4% and 46.7% of the light of an undamaged tile, respectively, and maximally recover to 85.9% and 79.5% after 5 and 9 days, respectively. PET exposed to 1 MRad and 10 MRad emit 35.0% and 12.2% light, respectively, and maximally recover to 93.5% and 80.0% after 22 and 60 days, respectively

Instability and noise-induced thermalization of Fermi–Pasta–Ulam recurrence in the nonlinear Schrödinger equation

We investigate the spontaneous growth of noise that accompanies the nonlinear evolution of seeded modulation instability into Fermi–Pasta–Ulam recurrence. Results from the Floquet linear stabilityanalysis of periodic solutions of the three-wave truncation are compared with full numerical solutions of the nonlinear Schrödinger equation. The predicted initial stage of noise growth is in a goodagreementwith simulations, and is expected to provide further insight intothe subsequent dynamics of the fieldevolution after recurrence breakup

Toward reliable morphology assessment of thermosets via physical etching: Vinyl ester resin as an example

The morphology of peroxide-cured, styrene crosslinked, bisphenol A-based vinyl ester (VE) resin was investigated by atomic force microscopy (AFM) after ‘physical’ etching with different methods. Etching was achieved by laser ablation, atmospheric plasma treatment and argon ion bombardment. Parameters of the etching were varied to get AFM scans of high topography resolution. VE exhibited a nanoscaled nodular structure the formation of which was ascribed to complex intra- and intermolecular reactions during crosslinking. The microstructure resolved after all the above physical etching techniques was similar provided that optimized etching and suitable AFM scanning conditions were selected. Nevertheless, with respect to the ‘morphology visualization’ these methods follow the power ranking: argon bombardment > plasma treatment > laser ablation

Design and Creation of a Device to Induce Vergence Eye Movements

Automated eye-tracking systems can detect and analyze eye movements as a means to accurately diagnose more than 20 neurological diseases including mild traumatic brain injury. Mild traumatic brain injury is an occurrence of injury to the head resulting from blunt trauma or from acceleration or deceleration forces. Eye movement refers to the voluntary or involuntary movement of the eyes, helping in acquiring, fixating and tracking visual stimuli. There are three types of voluntary eye movement to track objects: smooth pursuit, vergence shifts and saccades. Vergence shifts are eye movements where the eyes move in opposite directions: moving to the midline in convergence or moving away in divergence. This project focused on creating a device to induce vergence eye movements via a laser source and a mirror galvanometer. The laser pointer is directed at the mirror galvanometer which then projects the laser point onto a screen that lies horizontally in front of the observer. As the laser dot moves back and forth from the viewer, the eyes converge as the dot moves toward the viewer and diverge as the dot moves away. The device will be used to develop a baseline of control data that can eventually be used to diagnose mild traumatic brain injury. Different eye trackers will be tested to determine the optimum technique for gathering vergence eye movement data.https://scholarscompass.vcu.edu/uresposters/1192/thumbnail.jp

Uptake of dissolved inorganic and organic bphosphorus compounds by phytoplankton and bacterioplankton

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109807/1/lno19923720232.pd

A case study in collaboration: Assessing academic librarian/faculty partnerships

Undergraduates attending The George Washington University are required to take courses in the University Writing Program. When it was introduced in 2004, this innovative program institutionalized collaboration between librarians and writing professors. The program was designed to support the university’s strategic goal to enhance challenge, discovery, and quality in student education. Beginning in 2005, instruction librarians crafted a survey to elicit anonymous feedback from their faculty partners to measure the impact of the library partnership on student learning. The survey is administered annually to explore faculty perceptions and monitor trends. Responses to the survey identify significant strengths resulting from this collaboration as well as specific topics needing further attention