Reduction of Mixture Stratification in a Constant-Volume Combustor

Indiana University-Purdue University Indianapolis (IUPUI)This study contributes to a better working knowledge of the equipment being used in a well-established combustion lab. In particular, several constant-volume combustion properties (e.g., time ignition delay, flame propagation, and more) are examined to deduce any buoyancy effects between fuel and air mixtures and to develop a method aimed at minimizing such effects. This study was conducted on an apparatus designed to model the phenomena occurring within a single channel of a wave rotor combustor, which consists of a rotating cylindrical pre-chamber and a fixed rectangular main combustion chamber. Pressure sensors monitor the internal pressures within the both chambers at all times, and two slow-motion videography techniques visually capture combustion phenomena occurring within the main chamber. A new recirculation pump system has been implemented to mitigate stratification within the chamber and produce more precise, reliable results. The apparatus was used in several types of experiments that involved the combustion of various hydrocarbon fuels in the main chamber, including methane, 50%-50% methane-hydrogen, hydrogen, propane, and 46.4%-56.3% methane-argon. Additionally, combustion products created in the pre-chamber from a 1.1 equivalence ratio reaction between 50%-50% methane-hydrogen and air were utilized in the issuing pre-chamber jet for all hot jet ignition tests. In the first set of experiments, a spark plug ignition source was used to study how combustion events travel through the main chamber after different mixing methods were utilized – specifically no mixing, diffusive mixing, and pump circulation mixing. The study reaffirmed that stratification between fuel-air mixtures occurs in the main chamber through the presence of asymmetrical flame front propagation. Allowing time for mixing, however, resulted in more symmetric flame fronts, broader pressure peaks, and reduced combustion time in the channel. While 30 seconds of diffusion helped, it was found that 30 seconds of pumping (at a rate of 30 pumps per 10 seconds) was the most effective method at reducing stratification effects in the system. Next, stationary hot jet ignition experiments were conducted to compare the time between jet injection and main chamber combustion and the speed of the resulting shockwaves between cases with no mixing and 30 seconds of pump mixing. Results continued to show an improvement with the pump cases; ignition delay times were typically shorter, and shock speeds stayed around the same, if not increased slightly. These properties are vital when studying and developing wave rotor combustors, and therefore, reducing stratification (specifically by means of a recirculation system) should be considered a crucial step in laboratory models such as this one. Lastly, experiments between a fueled main chamber and rotating pre-chamber helped evaluate the leakage rate of the traversing hot jet ignition experimental setup paired with the new pump system. In its current form, major leaks are inevitable when attempting traversing jet experiments, especially with the pump’s suction action drawing sudden large plumes of outside air into the main chamber. To minimize leaks, gaps between the pre-chamber and main chamber should be reduced, and the contact surface between the two chambers should be more evenly distributed. Also, the pump system should only be operated as long as needed to evenly distribute the fuel-air mixture, which approximately happens when the main chamber’s total volume has been circulated through the system one time. Therefore, a new pump system with half of the original system’s volume was developed in order to decrease the pumping time and lower the risk of leaks

Investigation into the Use of the Concept Laser QM System as an In-Situ Research and Evaluation Tool

No abstract availabl

Escher-FBA: a web application for interactive flux balance analysis

Abstract Background Flux balance analysis (FBA) is a widely-used method for analyzing metabolic networks. However, most existing tools that implement FBA require downloading software and writing code. Furthermore, FBA generates predictions for metabolic networks with thousands of components, so meaningful changes in FBA solutions can be difficult to identify. These challenges make it difficult for beginners to learn how FBA works. Results To meet this need, we present Escher-FBA, a web application for interactive FBA simulations within a pathway visualization. Escher-FBA allows users to set flux bounds, knock out reactions, change objective functions, upload metabolic models, and generate high-quality figures without downloading software or writing code. We provide detailed instructions on how to use Escher-FBA to replicate several FBA simulations that generate real scientific hypotheses. Conclusions We designed Escher-FBA to be as intuitive as possible so that users can quickly and easily understand the core concepts of FBA. The web application can be accessed at https://sbrg.github.io/escher-fba

Priorities for Patient‐Centered Outcomes Research: The Views of Minority and Underserved Communities

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136533/1/hesr12505_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136533/2/hesr12505.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136533/3/hesr12505-sup-0001-AppendixSA1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136533/4/hesr12505-sup-0002-AppendixSA2.pd

Alpha- and beta- adrenergic receptors regulate inflammatory responses to acute and chronic sleep fragmentation in mice

Sleep is a recuperative process, and its dysregulation has cognitive, metabolic, and immunological effects that are largely deleterious to human health. Epidemiological and empirical studies have suggested that sleep fragmentation (SF) as result of obstructive sleep apnea (OSA) and other sleep abnormalities leads to pronounced inflammatory responses, which are influenced by the sympathetic nervous system (SNS). However, the underlying molecular mechanisms contributing to SNS regulation of SF-induced inflammation are not fully understood. To assess the effects of the SNS upon inflammatory responses to SF, C57BL/6j female mice were placed in automated SF chambers with horizontally moving bars across the bottom of each cage at specified intervals to disrupt sleep. Mice were first subjected to either control (no bar movement), acute sleep fragmentation (ASF), or chronic sleep fragmentation (CSF) on a 12:12-h light/dark schedule. ASF involved a bar sweep every 120 s for 24 h, whereas CSF involved a bar sweep every 120 s for 12 h (during 12 L; resting period) over a period of 4 weeks. After exposure to these conditions, mice received an intraperitoneal injection of either phentolamine (5 mg/kg BW; an α-adrenergic receptor blocker), propranolol (5 mg/kg BW; a β-adrenergic receptor blocker), or vehicle (saline). Serum corticosterone concentration, brain and peripheral cytokine (IL1β, TNFα, and TGFβ) mRNA expression, and body mass were assessed. ASF and CSF significantly elevated serum corticosterone concentrations as well as cytokine mRNA expression levels compared with controls, and mice subjected to CSF had decreased body mass relative to controls. Mice subjected to CSF and treated with phentolamine or propranolol had a greater propensity for a decrease in cytokine gene expression compared with ASF, but effects were tissue-specific. Taken together, these results suggest that both α- and β-adrenergic receptors contribute to the SNS mediation of inflammatory responses, and adrenergic antagonists may effectively mitigate tissue-specific SF-mediated inflammation

Members of Minority and Underserved Communities Set Priorities for Health Research

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146820/1/milq12354.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146820/2/milq12354_am.pd

NLTT 41135: a field M-dwarf + brown dwarf eclipsing binary in a triple system, discovered by the MEarth observatory

We report the discovery of an eclipsing companion to NLTT 41135, a nearby M5 dwarf that was already known to have a wider, slightly more massive common proper motion companion, NLTT 41136, at 2.4 arcsec separation. Analysis of combined-light and radial velocity curves of the system indicates that NLTT 41135B is a 31-34 +/- 3 MJup brown dwarf (where the range depends on the unknown metallicity of the host star) on a circular orbit. The visual M-dwarf pair appears to be physically bound, so the system forms a hierarchical triple, with masses approximately in the ratio 8:6:1. The eclipses are grazing, preventing an unambiguous measurement of the secondary radius, but follow-up observations of the secondary eclipse (e.g. with the James Webb Space Telescope) could permit measurements of the surface brightness ratio between the two objects, and thus place constraints on models of brown dwarfs.Comment: 15 pages, 6 figures, 10 tables, emulateapj format. Accepted for publication in Ap

Community-Based Participatory Research: Lessons Learned from the Centers for Children’s Environmental Health and Disease Prevention Research

Over the past several decades there has been growing evidence of the increase in incidence rates, morbidity, and mortality for a number of health problems experienced by children. The causation and aggravation of these problems are complex and multifactorial. The burden of these health problems and environmental exposures is borne disproportionately by children from low-income communities and communities of color. Researchers and funding institutions have called for increased attention to the complex issues that affect the health of children living in marginalized communities—and communities more broadly—and have suggested greater community involvement in processes that shape research and intervention approaches, for example, through community-based participatory research (CBPR) partnerships among academic, health services, public health, and community-based organizations. Centers for Children’s Environmental Health and Disease Prevention Research (Children’s Centers) funded by the National Institute of Environmental Health Sciences and U.S. Environmental Protection Agency were required to include a CBPR project. The purpose of this article is to provide a definition and set of CBPR principles, to describe the rationale for and major benefits of using this approach, to draw on the experiences of six of the Children’s Centers in using CBPR, and to provide lessons learned and recommendations for how to successfully establish and maintain CBPR partnerships aimed at enhancing our understanding and addressing the multiple determinants of children’s health