Breidenbaugh to Zinn: The Evolution of Chemistry at Gettysburg College

For students at Gettysburg College, there are many departments from which one can chose to make their major course of study. Included among these courses of study is the chemistry department. Though the chemistry department might seem like a stagnant, fixed part of the Gettysburg curriculum, it has not always been that way. For about the past 125 years, the chemistry department has seen a world of change from the time that it finally separated from the physical sciences and became its own department to the changing of omnipresent faculty, the chemistry department has evolved over time to become what it is today. Through an examination of how the department developed when its leadership changed from that of Dr. Edward S. Breidenbaugh to Dr. John B. Zinn, a greater understanding of chemistry at Gettysburg can be reached. [excerpt] Course Information: Course Title: HIST 300: Historical Method Academic Term: Spring 2010 Course Instructor: Dr. Michael J. Birkner \u2772 Hidden in Plain Sight is a collection of student papers on objects that are hidden in plain sight around the Gettysburg College campus. Topics range from the Glatfelter Hall gargoyles to the statue of Eisenhower and from historical markers to athletic accomplishments. You can download the paper in pdf format and click View Photo to see the image in greater detail.https://cupola.gettysburg.edu/hiddenpapers/1032/thumbnail.jp

Spectroscopic Imaging of Aluminum Containing Plasma

This dissertation aims to characterize laser-induced plasma from a physics point of view as warm, dense matter. Use of nominal nanosecond pulsed laser radiation initiates a plasma with electron temperatures of the order of 10 electron volts and electron densities of the order of air species densities at standard ambient temperature and pressure. For laser ablation and/or optical breakdown at or near a solid surface, the electron density can amount to be 1000 times greater. Spectroscopic investigations of the plasma emissions provide a method by which the electron density, temperature, and shockwave expansion may be determined. Of particular interest are the earliest of times following ablation of an aluminum target sample. At these times, observed spectral line profiles become distorted due to self-absorption affects. Here, experimental corrections to self-absorbed Al 394.4 and 396.15 nm, ground state transitions and the hydrogen Balmer series alpha, beta, and gamma lines are calculated by retro-reflecting the plasma emission back through the plasma volume. The plasma are initiated by laser ablating an Al alloy 6061 target sample in a 90 percent hydrogen and 10 percent nitrogen gas atmosphere at 840 Torr with 1064 nm Nd:YAG 14 ns laser pulses. Electron densities are calculated by fitting the corrected profiles to Voigt profiles. The widths of the lines are used with empirically developed formulas to infer the electron density. The temperature of the plasma is found by using the Boltzmann plot method constructed from the Balmer series lines. Spatially resolved, diatomic molecular aluminum monoxide spectra are fit to theory spectra to infer the plasma temperature along the axis of the laser incidence at time delays greater than 2.5 microseconds following target ablation. Computer tomography methods, including Abel inversion, are used to find the radial profile of the inferred temperatures. Finally, a series of measurements of the plasma shockwave are presented to determine the geometry of the shock front expansion using the shadowgraph imaging technique

Aluminum Monoxide Emission Measurements Following Laser-Induced Breakdown for Plasma Characterization

In this work, spectroscopic emissions from laser ablated aluminum samples are used to characterize the time dependent decay of laser-induced plasma. The plasma is created by tightly focusing nanosecond pulsed laser radiation. Time resolved measurements of the plasma are made with a gated, intensified linear diode array coupled to an optical multichannel analyzer and/or an intensified charged coupled device. Time resolution is achieved by synchronizing the laser with the measurement rate of the array detector. Computed diatomic molecular aluminum monoxide emissions were used to infer the temperature of the plasma as a function of time. This was completed by comparing experimentally collected spectra to theoretical calculations with a Nelder-Mead algorithm. The theoretical spectra were calculated from accurate line strengths for selected aluminum monoxide bands. The temperature of the plasma was found to decrease from typically 5100 Kelvin to 3600 Kelvin from 10 to 90 microseconds after optical breakdown. The temperature appears to plateau to a temperature of 3800 Kelvin after 90 microseconds. Error analysis in the inferred temperature is accomplished with the fitting algorithm and the precision was found to be between 45 and 75 Kelvin. Gated camera measurements were performed to infer the temperature along the height of the plasma and found the temperature profile of the plasma to increase above the plasma edge. Superposition of hydrogen Balmer series beta emissions with aluminum monoxide spectra allow one to infer electron number densities from the plasma at time delays preceding 20 microseconds

Tracking Temporal Development of Optical Thickness of Hydrogen Alpha Spectral Radiation in a Laser-Induced Plasma

In this paper, we consider the temporal development of the optical density of the H α spectral line in a hydrogen laser-induced plasma. This is achieved by using the so-called duplication method in which the spectral line is re-imaged onto itself and the ratio of the spectral line with it duplication is taken to its measurement without the duplication. We asses the temporal development of the self-absorption of the H α line by tracking the decay of duplication ratio from its ideal value of 2. We show that when 20% loss is considered along the duplication optical path length, the ratio is 1.8 and decays to a value of 1.25 indicating an optically thin plasma grows in optical density to an optical depth of 1.16 by 400 ns in the plasma decay for plasma initiation conditions using Nd:YAG laser radiation at 120 mJ per pulse in a 1.11 × 10 5 Pa hydrogen/nitrogen gas mixture environment. We also go on to correct the H α line profiles for the self-absorption impact using two methods. We show that a method in which the optical depth is directly calculated from the duplication ratio is equivalent to standard methods of self-absorption correction when only relative corrections to spectral emissions are needed

Symblepharon in kittens: a retrospective study of 40 kittens and 54 eyes (2002–2022)

Objectives: The aim of this study was to retrospectively evaluate the signalment, treatment, surgical technique and outcomes for feline symblepharon. Methods: A retrospective medical record review and standardized grading of clinical descriptions and photographs was undertaken. Results: Forty kittens (54 eyes) aged 3–46 weeks had symblepharon of five types in various combinations: eyelid deformation (24 kittens; 32 eyes); ankyloblepharon (four kittens; four eyes); conjunctiva-to-conjunctiva (11 kittens; 12 eyes); third eyelid-to-conjunctiva (24 kittens; 29 eyes); and corneoconjunctival adhesions (14 kittens; 16 eyes). At initial presentation, 23 (43%) eyes were affected by one type of symblepharon, 25 (46%) eyes by two types and six (11%) eyes by three types; 11 (20%) corneas were ulcerated. Twenty-four (44%) eyes of 18 (45%) kittens were managed medically. Surgery was performed under general anesthesia/sedation (30 occasions) or topical anesthesia (21 occasions) on 30 (56%) eyes of 22 kittens; 12 eyes (40%) underwent multiple surgeries. Four techniques were commonly employed: separation of conjunctival-to-conjunctival adhesions ± eyelid margins (14 eyes); resection of third eyelid adhesions ± temporary tacking of the third eyelid (modified Arlt’s pterygium technique; 18 eyes); en bloc resection of the third eyelid (two eyes); and separation of corneoconjunctival adhesions (14 eyes). Median duration of follow-up was 55 days (range 1–1051). Median symblepharon grade in kittens treated surgically improved for all types except corneoconjunctival symblepharon. Median symblepharon grade in kittens receiving medical management remained the same or improved. Corneoconjunctival symblepharon opacity decreased for eyes treated surgically but increased for eyes treated medically. Three eyes were enucleated due to complications of corneoconjunctival symblepharon. At final presentation, symblepharon persisted in 46 (85%) eyes; however, menace response was evident in 13/16 eyes and dazzle reflex in 23/23 eyes. Conclusions and relevance: Symblepharon is a heterogeneous group of conditions with diverse anatomic involvement, clinical appearance and impact, optimal treatment and prognosis for vision.This article is published as Shiraishi, Hikaru, Karen M. Vernau, Soohyun Kim, Kathryn L. Good, Steven R. Hollingsworth, Lionel Sebbag, Elizabeth Montgomery et al. "Symblepharon in kittens: a retrospective study of 40 kittens and 54 eyes (2002–2022)." Journal of Feline Medicine and Surgery 25, no. 2 (2023). DOI: 10.1177/1098612X221150160. Copyright 2023 The Author(s). Attribution-NonCommercial 4.0 International (CC BY-NC 4.0). Posted with permission