Preliminary Results of Solid Gas Generator Micropropulsion

A decomposing solid thruster concept, which creates a more benign thermal and chemical environment than solid propellant combustion, while maintaining, performance similar to solid combustion, is described. A Micro-Electro-Mechanical (MEMS) thruster concept with diode laser and fiber-optic initiation is proposed, and thruster components fabricated with MEMS technology are presented. A high nitrogen content solid gas generator compound is evaluated and tested in a conventional axisymmetric thrust chamber with nozzle throat area ratio of 100. Results show incomplete decomposition of this compound in both low pressure (1 kPa) and high pressure (1 MPa) environments, with decomposition of up to 80% of the original mass. Chamber pressures of 1.1 MPa were obtained, with maximum calculated thrust of approximately 2.7 N. Resistively heated wires and resistively heated walls were used to initiate decomposition. Initiation tests using available lasers were unsuccessful, but infrared spectra of the compound show that the laser initiation tests used inappropriate wavelengths for optimal propellant absorption. Optimal wavelengths for laser ignition were identified. Data presented are from tests currently in progress. Alternative solid gas generator compounds are being evaluated for future tests

Obesity, comorbidities, and treatment selection in Black and White women with early breast cancer

Background: This study investigates obesity and comorbidity in Black and White women with early breast cancer (stages I-III) and their potential impact on treatment decisions for patients with hormone receptor–positive (HR+)/human epidermal growth factor receptor 2–negative (HER2–) tumors. Methods: In this retrospective chart review, comparisons of frequencies for Black and White patients were calculated with the Fisher exact test. Log binomial regression was used to estimate prevalence ratios (PRs) with 95% confidence intervals for total and individual comorbidities, and multivariable modeling was used to estimate PRs adjusted for age and body mass index (BMI). Results: In a sample of 548 patients, 26% were Black, and 74% were White. Sixty-two percent of Black patients and 32% of White patients were obese (BMI ≥ 30 kg/m2; P <.0001). Seventy-five percent of Black patients and 87% of White patients had HR+ tumors (P =.001). Significant intergroup differences were seen for 2 or more total comorbidities (62% of Blacks vs 47% of Whites; P =.001), 2 or more obesity-related comorbidities (33% vs 10%; P <.0001), hypertension (60% vs 32%; P <.0001), diabetes mellitus (23% vs 6%; P <;.0001), hypercholesterolemia or hyperlipidemia (28% vs 18%; P =.02), and hypothyroidism (4% vs 11%; P =.012). In women with HR+/HER2– tumors, there were no intergroup differences in treatment decisions regarding the type of surgery, chemotherapy regimen, radiation, or endocrine treatment despite significant differences in the prevalence of obesity and comorbidities. Conclusions: This study documents significant disparities between Black and White women with early breast cancer with regard to high rates of obesity, overall comorbidities, and obesity-related comorbidities, and it highlights the prevalence of competing risks that may complicate outcomes in breast cancer

Patient-reported symptom severity, interference with daily activities, and adverse events in older and younger women receiving chemotherapy for early breast cancer

Background: To the authors' knowledge, it is unknown whether patient-reported symptom severity and symptom interference with daily activities differ between younger (aged <65 years) and older (aged ≥65 years) women receiving similar chemotherapy regimens for early breast cancer (EBC). Methods: Study participants rated 17 side effects of chemotherapy regimens currently in use in clinical practice (2014-2019). Results: Of 284 women with EBC (stage I-III), approximately 57% were aged <65 years and 43% were aged ≥65 years. For anthracycline-based regimens, a higher percentage of younger women reported moderate, severe, or very severe (MSVS) hot flashes (49% vs 18%) (P <.001). For nonanthracycline regimens, a higher percentage of younger women reported MSVS hot flashes (38% vs 19%) (P =.009) and a lower percentage reported MSVS arthralgia (28% vs 49%) (P =.005). With regard to symptom interference with daily activities, a higher percentage of younger women being treated with anthracycline-based regimens reported MSVS hot flashes (32% vs 7%) (P =.001) and myalgia (38% vs 18%) (P =.02). For nonanthracycline chemotherapy, a higher percentage of younger women reported MSVS interference for hot flashes (26% vs 9%) (P =.006) and lower percentages reported abdominal pain (13% vs 28%) (P =.02). Overall, there were no significant differences noted among younger versus older patients with regard to hospitalizations (19% vs 12%; P =.19), dose reductions (34% vs 31%; P =.50), dose delays (22% vs 25%; P =.59), or early treatment discontinuation (16% vs 16%; P =.9546). Conclusions: Older and younger women with EBC who were treated with identical chemotherapy regimens generally experienced similar levels of symptom severity, symptom-related interference with daily activities, and adverse events. Lay Summary: In this study, women receiving chemotherapy for early breast cancer rated the severity of 17 symptoms and symptom interference with their activities of daily living. Older (aged ≥65 years) and younger (aged <65 years) women who received identical chemotherapy regimens generally experienced similar levels of symptom severity, symptom-related interference with daily activities, and adverse events

Neutron Radioscopic Measurement of Water Adsorption Coefficients in Aerogels

Abstract. In this work, neutron radioscopy was utilized to investigate water vapor uptake by a hydrophilic silica aerogel. Aerogel is an unusual porous material, produced by a sol-gel process that results in a solid material with a unique microstructure composed of nanometer-size particles and pores. Aerogels have an extraordinarily large internal surface area which is accessible via open pores, making them candidates for filters and gas adsorption media. The water vapor deposition was modeled both analytically and computationally, and an estimate for adsorption coefficients for water vapor in aerogel yielded 1.08 × 10 −3 ± 2.58 × 10 −4 cm 2 /s. Initial tests to measure water vapor uptake from moist air were very successful. Dry air was bubbled through water and then flowed past an aerogel. The aerogel was shown to uptake the water vapor readily from moist air. After uptake, the aerogel dried out rapidly in dry air. This phenomenon was repeatable, indicating that the aerogel could be reused with little change in its sorption properties. Neutron radiography was shown to be an effective nondestructive method for evaluating the realtime movement of water vapor in aerogel, as deposition patterns can be analyzed quantitatively as a function of time and penetration distance into the aerogel

FUELCELL2005-74051 THE NATURE OF FLOODING AND DRYING IN POLYMER ELECTROLYTE FUEL CELLS

ABSTRACT Two different 50 cm 2 fuel cells operated at high current density (1.3A/cm 2 -1.5A/cm 2 ) were visualized using neutron imaging, and the liquid water content in the flow channels and diffusion media under the lands and channels was calculated and compared. At high current density with fully humidified inlet flow, a direct comparison between flooded and nonflooded conditions was achieved by increasing the fuel cell temperature over a small range, until voltage loss from flooding was alleviated. Results indicate that a surprisingly small mass of liquid water is responsible for a significant voltage loss. The deleterious effects of flooding are therefore more easily explained with a locally segregated flooded pore model, rather than a homogeneously flooded pore and blockage phenomenon. Anode dryout was similarly observed and quantified, and results indicate that an exceedingly small mass of water is responsible for significant voltage loss, which is consistent with expectations. The results presented help to form a more complete vision of the flooding loss and anode dryout phenomena in PEFCs

Study of a Loop Heat Pipe Using Neutron Radiography

An explanation is given of what a loop heat pipe (LHP) is, and how it works. It is then shown that neutron imaging (both real time neutron radioscopy and single exposure neutron radiography) is an effective experimental tool for the study of LHPs. Specifically, neutron imaging has helped to identify and correct a cooling water distribution problem in the condenser, and has enabled visualization of two-phase flow (liquid and vapor) in various components of the LHP. In addition, partial wick dry-out, a phenomenon of great importance in the effective operation of LHPs, has been identified with neutron imaging. It is anticipated that neutron radioscopy and radiography will greatly contribute to our understanding of LHP operation, and will lead to improvement of LHP modeling and design