Development of a Deep UV Resonance Raman Spectrometer

UV resonance Raman spectroscopy is well-suited for studies of protein structure and dynamics due to its high sensitivity and selectivity. This has allowed for equilibrium as well as kinetic studies of protein folding, investigations of DNA-protein interactions, and characterization of explosive species. This thesis is focused on a plan for the development of a deep UV resonance Raman spectrometer for excitation wavelengths from 197 nm – 240 nm. This spectrometer will utilize two gratings in a subtractive dispersion mode, giving a theoretical reciprocal linear dispersion of 0.424 nm/mm. This gives a theoretical limiting resolution of ~6 cm-1. The gratings stages are equipped with motors, one of which drives a lead screw, and the other is a motorized linear actuator, which gives both stages high angular resolution. The stage controlled by the lead screw has sufficient resolution to shift the spectrum of a particular analyte by a single pixel. The expected efficiency of this spectrometer is ~15%, which is comparable to the efficiency of other double spectrometers. The development of this spectrometer will allow the continuation of incisive studies of protein and peptide structure

After Gettysburg: Cavalry Operations in the Eastern Theater July 14, 1863 to December 31, 1863

An In-Depth Perspective to Cavalry History The Gettysburg Campaign exacted a cost from both armies. The Confederate Army of Northern Virginia’s casualty rate approached forty percent, while the Union Army of the Potomac’s losses amounted to one-fourth of its rank and file. In the campa...

The Colors of Courage: Gettysburg\u27s Forgotten History: Immigrants, Women, and African Americans in the Civil War\u27s Defining Battle

Gettysburg A Different Look at a Famous Battle When The Colors of Courage appeared in 2005, it received solid praise from reviewers for its breadth of research and graceful writing on a neglected subject. The book recounts the experiences of the German soldiers of the Uni...

Did Lincoln Own Slaves?: and Other Frequently Asked Questions About Abraham Lincoln

Answering Questions about Lincoln The purpose of this book, according to Gerald J. Prokopowicz, is to answer questions about Abraham Lincoln posed by the public, not by historians and professors. In all, Prokopowicz has offered more than 325 questions. As would be expected in such a boo...

Unflinching Personal Bravery: Bryan Grimes Was At Lee\u27s Side From Manassas To Appomattox

Bryan Grimes was a successful planter in Pitt County, North Carolina, when the Civil War began. An avowed secessionist, Grimes voted in the convention for his state\u27s withdrawal from the Union and then resigned his political position to serve in its and the Confederacy\u27s defense. Unschooled in mili...

The Battle of Brandy Station: North America\u27s Largest Cavalry Battle

Studying the Largest Cavalry Battle On June 9, 1863, in Culpeper County, Virginia, nine thousand Union cavalrymen and three thousand Union infantry clashed with ten thousand Confederate horsemen in the battle of Brandy Station. The fighting lasted for roughly twelve hours and covered d...

On Jackson\u27s Flank: A First Biography Of Confederate Officer Robert Rodes

Robert Emmett Rodes strode across Douglas Southall Freeman\u27s Lee\u27s Lieutenants as if he stepped out from the pages of Beowulf. A tall, blond-haired man, Rodes emerges in the hands of Freeman as one of the Army of Northern Virginia\u27s finest warriors and as a romantic figure. The unforgettab...

Usefulness of the Lang Stereotest with an infant population

Sixty-four healthy full term infants between 6 and 24 months of age were tested using the Lang Stereotest. A full vision examination including visual acuity assessment using the Teller acuity card preferential looking procedure, near point of convergence, Worth test for eccentric fixation, Hirschberg test, and monocular estimate method to measure accommodative posture was performed. Ocular health was also assessed to rule out pathology. Results showed that 90% of the 6.0 to 12.0 month age group, 100% of both the 12.0 to 18.0 and 18.0 to 24.0 month age groups were able to respond positively to at least one stereo image on the Lang Stereotest. Performance showed improvement with age

Thermal Behavior in the Lens Process

Direct laser metal deposition processing is a promising manufacturing technology which could significantly impact the length oftime between initial concept and finished part. For adoption ofthis technology in the manufacturing environment, further understanding is required to ensure robust components with appropriate properties are routinelyfabricated. This requires a complete understanding ofthe thermal history.during part fabrication and control ofthis behavior. This paper will describe our research to understand the thermal behavior for the Laser Engineered Net Shaping (LENS) process!, where a component is fabricated by focusing a laser beam onto a substrate to create a molten pool in which powder particles are simultaneously injected to build each layer. The substrate is moved beneath the l~ser beam to deposit a thin cross section, thereby creating the desired geometry for each layer. After deposition of each layer, the powder delivery nozzle and focusing lens assembly is incremented in the positive Z-direction, thereby building a three dimensional component layer additively. It is important to control the thermal behavior to reproducibly fabricate parts. The ultimate intent is to monitor the thermal signatures and to incorporate sensors and feedback algorithms to control part fabrication. With appropriate control, the geometric properties (accuracy, surface finish, low warpage) as well as the materials' properties (e.g. strength, ductility) of a component can be dialed into the part through the fabrication parameters. Thermal monitoring techniques will be described, and their particular benefits highlighted. Preliminary details in correlating thermal behavior with processing results will be discussed.Mechanical Engineerin

Photochemistry in the arctic free troposphere: NOx budget and the role of odd nitrogen reservoir recycling

The budget of nitrogen oxides (NOx) in the arctic free troposphere is calculated with a constrained photochemical box model using aircraft observations from the Tropospheric O3 Production about the Spring Equinox (TOPSE) campaign between February and May. Peroxyacetic nitric anhydride (PAN) was observed to be the dominant odd nitrogen species (NOy) in the arctic free troposphere and showed a pronounced seasonal increase in mixing ratio. When constrained to observed acetaldehyde (CH3CHO) mixing ratios, the box model calculates unrealistically large net NOx losses due to PAN formation (62pptv/day for May, 1-3km). Thus, given our current understanding of atmospheric chemistry, these results cast doubt on the robustness of the CH3CHO observations during TOPSE. When CH3CHO was calculated to steady state in the box model, the net NOx loss to PAN was of comparable magnitude to the net NOx loss to HNO3 (NO2 reaction with OH) for spring conditions. During the winter, net NOx loss due to N2O5 hydrolysis dominates other NOx loss processes and is near saturation with respect to further increases in aerosol surface area concentration. NOx loss due to N2O5 hydrolysis is sensitive to latitude and month due to changes in diurnal photolysis (sharp day-night transitions in winter to continuous sun in spring for the arctic). Near NOx sources, HNO4 is a net sink for NOx; however, for more aged air masses HNO4 is a net source for NOx, largely countering the NOx loss to PAN, N2O5 and HNO3. Overall, HNO4 chemistry impacts the timing of NOx decay and O3 production; however, the cumulative impact on O3 and NOx mixing ratios after a 20-day trajectory is minimal. © 2003 Elsevier Science Ltd. All rights reserved