CONSEQUENCES OF ARYL HYDROCARBON RECEPTOR ACTIVATION IN STEADY-STATE AND INFLAMMATORY DENDRITIC CELLS

The aryl hydrocarbon receptor (AhR) is a steroid-like transcription factor that mediates the toxicity of various environmental pollutants, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and TCDD-like compounds. Exposure to environmentally relevant levels of TCDD and TCDD congeners has been shown to cause immune suppression, yet the mechanisms underlying TCDD-induced immune suppression remain poorly understood. Dendritic cells (DCs) are professional antigen presenting cells (APCs) that play an integral role in both innate and adaptive immune responses. DCs constitutively express AhR and represent a highly sensitive immune cell population to AhR activation by environmental pollutants. In a murine inflammatory bone marrow-derived DC (BMDC) model, AhR activation has been shown to alter surface molecule expression and induce immnuoregulatory genes. To further these studies, we examined AhR activation in murine steady-state BMDCs, DCs that in vitro closely resemble DCs found in peripheral immune tissues in vivo. We found that similar to inflammatory BMDCs, TCDD-induced AhR activation disrupts steady-state BMDC differentiation, responsiveness to innate danger signals, and induces immunoregulatory gene expression. AhR activation has been implicated in the polarization of regulatory T cells (Tregs), which are capable of inhibiting immune responses and may contribute to the observed immune suppression following exposure to TCDD. Because both inflammatory and steady-state BMDCs upregulated immunoregulatory gene expression in response to TCDD, their potential to suppress CD4+ T cells responses was examined in antigen-specific DC:CD4+ T cell co-cultures in vitro. Both inflammatory and steady-state AhR activated BMDCs altered antigen-specific CD4+ T cell responses and induced Foxp3+ Tregs when compared to vehicle-treated BMDCs. These in vitro studies were followed by a series of in vivo studies, in which we demonstrated that TCDD-exposed mice immunized with antigen-laden BMDCs, or antigen with adjuvant generated an increased frequency of Foxp3+ Tregs and subsequently dampened antigen-specific CD4+ effector T cell responses. Furthermore, DCs from TCDD-treated mice displayed increased expression of immunoregulatory genes, suggesting that they may be contributing to deficient CD4+ effector T cells responses and the generation of Tregs as observed in our in vitro studies. Overall, these studies significantly advance our understanding of how AhR activation by TCDD and TCDD-like chemicals induces immune suppression

Measuring Noble Gases in Coma Samples from Comet Wild 2

Since comets originated during the formation of the solar system, the processes of solar system formation can be better understood through compositional analysis of cometary material. A low density, silicon-based substance called aerogel was used by NASA’s Stardust spacecraft to collect coma samples from comet Wild 2. Aerogel not from the spacecraft (“non-flight”) was investigated to determine the possibility of measuring noble gases in Stardust samples. Gas evolved from heated, non-flight aerogel was measured initially using a residual gas analyzer, then a high-sensitivity massspectrometer. Levels of helium and neon isotopes observed from both instruments were sufficiently low that noble gases from Stardust samples were measured using the same technique. Intrinsic helium and neon was not identified in flight aerogel without apparent cometary material. Helium and neon were detected above background in flight samples containing impact particle tracks

Alien Registration- Simones, Marie (Auburn, Androscoggin County)

https://digitalmaine.com/alien_docs/30473/thumbnail.jp

Survey of innovative materials and techniques of teaching reading to promote visual and auditory discrimination at the primary level

The purpose of this paper was to survey the innovative materials and techniques available for the primary teacher to be used as a reference to new approaches in presenting lessons in auditory and visual discrimination

Alien Registration- Simones, John (Auburn, Androscoggin County)

https://digitalmaine.com/alien_docs/30472/thumbnail.jp

Alien Registration- Simones, Nicholas J. (Lewiston, Androscoggin County)

https://digitalmaine.com/alien_docs/28156/thumbnail.jp

Application of the TDMA Technique Toward the Size and Charge Distribution Measurement of Graphite, Gold, Palladium, and Silver Aerosols

The knowledge of charge distributions among aerosol particles has been an important topic for many years because of the strong electrostatic interactions which can greatly influence aerosol transport and evolution. Theoretical models have been developed although experimental verification has been limited because of the difficulty in measuring charged aerosols. Recently a method utilizing a tandem differential mobility analyzer (TDMA) has been shown to be applicable toward measuring both the size and charge distributions of nanosized combustion aerosols. The goal of this work is on further exploration of this method toward the measurement of non-combustion aerosols and in particular those associated with very high temperature reactors (VHTRs). The complete bipolar charge and size distributions of spark generated graphite, gold, silver, and palladium aerosol have been measured with a TDMA apparatus assembled and calibrated during this study. In addition, an electrostatic precipitator has been designed and constructed for measuring the size distributions of neutrally charged particles associated with these aerosols. The results show charge asymmetry in all measured aerosols with higher concentrations of positively charged particles than negative at the same charge level. These results differ from equilibrium charge distributions of both Boltzmann and Fuchs showing that charge equilibrium may not always be an appropriate assumption. The TDMA technique should find applications in characterizing VHTR aerosols and rate processes such as coagulation, deposition, and resuspension which will be important for both reactor design, and accident modeling and simulation

Alien Registration- Simones, Stella J. (Auburn, Androscoggin County)

https://digitalmaine.com/alien_docs/30474/thumbnail.jp

Measurement of coagulating silver and carbon aerosols using a tandem differential mobility analyzer

One of the unresolved technical issues associated with the high temperature gas-cooled reactor (HTGR) is the production of carbonaceous dust (e.g. by abrasion, corrosion, radiation damage, gas-to-particle conversion) and the subsequent transport of sorbed fission products via aerosol transport. Diffusion charging and/or self-charging of these aerosols is likely to occur which will affect how the aerosol evolves in time and ultimately deposits on surfaces. At present, nuclear reactor safety codes, such as MELCOR, do not account for these electrostatic effects and there is currently no consensus on their importance. Further experimentation and modeling of these effects are therefore important and ongoing to resolve these issues. The purpose of this research is to experimentally investigate the coagulation of charged aerosols closely associated with HTGRs by measuring the evolution of size and charge distributions over time and to compare the experimental results with available numerical models. Measurements have been completed for both silver and carbon ultrafine aerosols using a tandem differential mobility analyzer and an open flow coagulation chamber with a residence time of nearly 400 seconds. Results for both aerosols indicate that coagulation occurs faster than predicted by the model, at times differing by an order of magnitude. Overall, the apparatus developed here will support future coagulation studies of charged ultrafine aerosols at the Nuclear Science and Engineering Institute by providing data for validation of computer codes and guiding model development.Includes bibliographical references (pages 72-75)

Exploring the Impact of Grit and Sponsorship on Female Leadership and Aspirations

This mixed methods case study explored the impact of grit and sponsorship experiences of millennial females on their leadership aspirations and attainment of leadership positions. Six females in the same field of occupation in New England served as the participants. The case study focused on the experiences of two participants (one with the highest grit score and one with the lowest grit score). The participant with the highest grit score demonstrated both the attainment of a leadership position and aspirations for greater leadership positions in the future, as compared to the less gritty individual who had attained a leadership position but did not aspire to any future leadership positions beyond the current one. Both participants cited that their confidence increased when they had a sponsor and decreased when they did not have a supportive superior in the workplace. The combination of high grit and sponsorship led to the attainment of a leadership position and future leadership aspirations. The participant with low grit and a sponsorship experience attained a leadership position, but had no aspirations for future leadership positions beyond the present one. This study provides empirical data about grit and sponsorship for millennial females and identifies that sponsorship is a driver of success for leadership attainment and grit is a driver of success for increased leadership aspirations