Water Ice Films in Cryogenic Vacuum Chambers

The space simulation chambers at Arnold Engineering Development Complex (AEDC) allow for the testing and calibration of seeker sensors in cryogenic, high vacuum environments. During operation of these chambers, contaminant films can form on the components in the chamber and disrupt operation. Although these contaminant films can be composed of many molecular species, depending on the species outgassed by warm chamber components and any leaks or virtual leaks (pockets of gas trapped within a vacuum chamber) that may be present, water vapor is most common, and it will be the focus of this dissertation. In this dissertation, some properties of the water molecule and low pressure ice are reviewed with a focus on the optical properties. The method of angular coefficients is utilized to calculate flux distributions for general three dimensional situations and the program written is applied to a model of the AEDC 10V space simulation chamber. The optical effects of varying amounts of contamination on a generic germanium window and gold mirror, along with the effects on two components specific to the space chambers, is determined. Also, an experiment to measure the thickness and other properties of contaminant films is discussed, and initial results are given for the first two tests of the experimental setup

Cortisol Regulation of Aquaglyceroporin HC-3 Protein Expression in the Erythrocytes of the Freeze Tolerant Tree Frog Dryophytes chrysoscelis

Dryophytes chrysoscelis, commonly known as Cope’s gray treefrog, is a freeze tolerant anuran that freezes up to 65% of extracellular fluid during winter to survive. Glycerol is presumably used as a cryoprotectant during a period of cold-acclimation to protect cells from permanent damage due to hypoosmotic stress upon freezing and thawing. The passage of glycerol and water during cold-acclimation is mediated through aquaglyceroporin HC-3 in the nucleated erythrocytes (RBCs) of D. chrysoscelis. This thesis analyzes the mechanisms in which D. chrysoscelis prepares for cold-acclimation and glycerol synthesis. Cortisol is a stress hormone known to respond to osmolarity and metabolic challenges and regulate aquaporins; however, the role of cortisol in regulating anuran HC-3 protein expression and subcellular localization, and implications for mediating anticipatory glycerol synthesis and freeze tolerance remain to be determined. We hypothesize that cortisol exposure regulates HC-3 protein expression and subcellular localization. Freshly isolated RBCs were cultured in complete cell culture media (CCCM) and cortisol for 2, 4, and 6 hours at two separate concentrations, 1.0 and 0.1 μg/ml. Another group of RBCs was incubated with CCCM for 24 hours in culture before the 4 and 8-hour incubation with cortisol concentrations of 0.01, 0.1, and 1.0 μg/ml. Densitometric analyses of immunoblots specific for HC-3 for RBCs that had undergone the 24-hour incubation before cortisol exposure showed a 3.7-fold increase in native HC3 from RBCs cultured in 0.01 μg/ml cortisol for 4 hours, 40-fold increase in native HC-3 from RBCs cultured in 0.1 μg/ml cortisol for 4 hours, and 21-fold increase in native HC3 from RBCs cultured in 1.0 μg/ml cortisol for 4 hours compared to RBCs cultured in 0 μg/ml for 4 hours. HC-3 protein abundance increased in RBCs exposed to 0.01 μg/ml cortisol for 8 hours by 2.4-fold from the 4-hour time point. The abundance of Page | ii glycosylated HC-3 (60-150kDa) increased by 3.1-fold, 5.8-fold, and 5.3-fold for RBCs exposed to 0.01, 0.1, and 1.0 μg/ml cortisol for 4 hours. The abundance of glycosylated HC-3 increased by 0.8-fold for RBCs treated with 0.01 μg/ml cortisol for 8 hours. A variation in HC-3 protein abundance was observed for freshly isolated RBCs. The subcellular localization and fluorescent intensity (arbitrary units) of the HC-3 protein were analyzed via scanning laser confocal microscopy and immunocytochemistry using ImageJ software. Perinuclear localization of the HC-3 protein was oberved in RBCs exposed to 0.1 and 1.0 μg/ml cortisol for 4 hours and membrane localization for RBCs exposed to 0.1 μg/ml cortisol for 8 hours. Fluorescent analysis of RBCs exposed to 0.01 and 1.0 μg/ml cortisol for 8 hours exhibit enhanced HC-3 intensity in the cytosol compared to control RBCs. Therefore, there is a potential correlation between cryoprotective glycerol, freeze tolerance, and the role of cortisol in regulating HC-3 protein expression and subcellular localization

Characterization of the Temperature Dependence of Optical Components in a Cryo-Vacuum Chamber used for Space Sensor Testing

The space sensor cryo-vacuum chambers at Arnold Air Force Base are world class sensor characterization and calibration facilities. The chambers provide a simulated deep space background and accurate infrared projections. Several large optical systems are used within the chambers to accomplish this. Calibration of the chambers requires the use of a database of the measured optical properties of these components to simulate the output. However, as the information in the database is room temperature information and the chambers run near 20K, some discrepancies exist between the actual output and the model output. The purpose of this work is to translate the room temperature spectral information to cryogenic information as correctly as possible. To achieve this, the relevant temperature dependent material information was collected from literature. A program was written using this information that calculated spectral performance with temperature as a parameter. An ambient calculation and a cryogenic calculation were performed where necessary for each component of interest. The translation between the two calculations was then measured and applied to the measured ambient data of the components to obtain their expected cryogenic performance

Potential energy surface of the 2A' Li2+Li doublet ground state

The lowest doublet electronic state for the lithium trimer (2A') is calculated for use in three-body scattering calculations using the valence electron FCI method with atomic cores represented using an effective core potential. It is shown that an accurate description of core-valence correlation is necessary for accurate calculations of molecular bond lengths, frequencies and dissociation energies. Interpolation between 2A' ab initio surface data points in a sparse grid is done using the global interpolant moving least squares method with a smooth radial data cutoff function included in the fitting weights and bivariate polynomials as a basis set. The Jahn-Teller splitting of the 2E' surface into the 2A1 and 2B2 states is investigated using a combination of both CASSCF and FCI levels of theory. Additionally, preliminary calculations of the 2A'' surface are also presented using second order spin restricted open-shell Moller-Plesset perturbation theory.Comment: 7 pages, 5 figure

Long-range three-body atom-diatom potential for doublet Li3{}_3

An accurate long-range {\em ab initio} potential energy surface has been calculated for the ground state ${}^2A'$ lithium trimer in the frozen diatom approximation using all electron RCCSD(T). The {\em ab initio} energies are corrected for basis set superposition error and extrapolated to the complete basis limit. Molecular van der Waals dispersion coefficients and three-body dispersion damping terms for the atom-diatomic dissociation limit are presented from a linear least squares fit and shown to be an essentially exact representation of the {\em ab initio} surface at large range

A longitudinal study of <i>Caenorhabditis elegans</i> larvae reveals a novel locomotion switch, regulated by G_αs signaling

Despite their simplicity, longitudinal studies of invertebrate models are rare. We thus sought to characterize behavioral trends of Caenorhabditis elegans, from the mid fourth larval stage through the mid young adult stage. We found that, outside of lethargus, animals exhibited abrupt switching between two distinct behavioral states: active wakefulness and quiet wakefulness. The durations of epochs of active wakefulness exhibited non-Poisson statistics. Increased G signaling stabilized the active wakefulness state before, during and after lethargus. In contrast, decreased Gαs signaling, decreased neuropeptide release, or decreased CREB activity destabilized active wakefulness outside of, but not during, lethargus. Taken together, our findings support a model in which protein kinase A (PKA) stabilizes active wakefulness, at least in part through two of its downstream targets: neuropeptide release and CREB. However, during lethargus, when active wakefulness is strongly suppressed, the native role of PKA signaling in modulating locomotion and quiescence may be minor

Personagens em Dostoiévski: complexidade, tensão e ardor apaixonantes

As personagens desempenham, junto com o enredo, papel fundamental na ficção. Quando bem construídas, são capazes de gerar convencimento e empatia no leitor. Esse é o caso das complexas personagens de Dostoiévski. Para o crítico Leonid Grossman, Dostoiévski foi capaz de desenvolver um método de criação destinado a retratar da maneira mais absoluta e verdadeira o homem de seu tempo. Este trabalho, na intenção de fornecer uma pequena amostra das criações literárias do autor ao longo da sua trajetória, faz uma breve análise de quatro personagens que compõem a fase inicial e a considerada fase de maturidade de Dostoiévski: Makar Dievúchkin, de Gente Pobre; Niétotchka Niezvânova, do romance homônimo; e Páviel Pávlovitch e Vieltchâninov, de O Eterno Marido

President P. Barry Butler

Dr. P. Barry Butler, the sixth president of Embry-Riddle Aeronautical University.https://commons.erau.edu/db-read-posters/1111/thumbnail.jp