Powering OSCAR

Recycling waste has been an issue on Earth for decades. The OSCAR project seeks to find ways to make sure that it does not become an issue in space. The main focus of OSCAR is the combustion of waste and reclamation of gaseous products in microgravity. The first phase of testing relies on a ground rig that operates both under normal (Earth) gravity and in drop tower tests that briefly simulate a microgravity environment. In the second phase, a test will be performed during a suborbital flight were the experiment will be carried out in microgravity. Throughout the spring term, interns have played an integral part in continuing the progress made by the project. They performed work in upgrading the electrical and mechanical systems that make up OSCAR. They made multiple improvements to the test rig's operating software to improve readability and usability. They prepared and edited documents that were vital to the engineering process. And, they were responsible for performing lab tests and refining the lab operations document and procedure. The interns were a big help in maintaining the rigorous test schedule. OSCAR, which stands for Orbital Syngas Commodity Augmentation Reactor, is to find a way to turn astronaut waste into chemical energy. The two parts of this are important: finding a way to dispose of waste generated in space, and seeing if there is a way to recycle that waste into chemical energy. The importance of the disposal aspect is that there is currently no way to dispose of, or recycle, waste that is created in space other than jettisoning it (which is what the ISS does via empty supply capsules). As manned missions go deeper into space, that method will no longer be viable, as a craft would essentially be littering the space and planets that they visit. Energy reclamation is also important because of the high monetary and spatial costs of sending supplies on space missions. Every little bit extra that can be reused out of what is sent can save room and funds for other supplies. The facet of this problem that the OSCAR project is focusing on is how to combust waste in zero gravity. Combustion in the presence of gravity is one of those things that is taken for granted. When something burns on Earth, the flames rise above the fuel as oxygen flows from underneath. In microgravity, the flames surround the object completely, which restricts the amount of oxygen that can reach the fuel, and retards the combustion. OSCAR uses a vortex reaction chamber to counter this phenomenon. The OSCAR test rig will eventually be tested on a suborbital flight to see if it is an effective solution to the issue in real-world conditions. Currently, there is a prototype test rig that is fully functional. This rig has been previously tested in a 2 second drop test at Glenn Research Centers (GRC) Zero Gravity Facility (ZGF). (The free-fall conditions of the drop mimic microgravity, if only for a brief period of time). This sessions focus was on upgrading the test rig and software, updating the paperwork, performing additional lab tests, and readying the rig for the five second drop test, again at GRC. II. Upgrades The state of the testing rig at the start of the session was in between its configurations for the two second drop tower and the five second drop tower. The rig needed upgrades to address various insufficiencies that either were discovered during the two second campaign or were a direct result of the differences between the two drop tower setups. The main differences that had to be handled were the increase in shock loads from 30g to 65g, a difference in drop indicating signal (on the falling edge of a pulse instead of a change from high to low), and the ambient pressure of the test apparatus (the two second tower dropped the rig in atmosphere, while the five second tower drops in vacuum)

Designing a Biomimetic Primary Cell-Based 3D Culture System for Neurotoxicity Screening

Culturing neurons in vitro is a challenging task because they are a highly specialized cell type that reside in a complex and unique environment in the body. The aim of the research presented in the following thesis was to design a biomimetic, three-dimensional scaffold capable of (1) promoting primary neuron maturation and axonal outgrowth and (2) serving as a system for toxicology screening. In the system presented here, neurons were cultured in three-dimensional hydrogels, simulating the physiological environment that these cells experience within the body. In doing so, a biologically relevant response was elicited upon their exposure to acrylamide, a known neurotoxin. Primary neurons were isolated from embryonic chick spinal cords and seeded in alginate or collagen hydrogels. Initial cell viability assays and qualitative microscopy observations confirmed that primary neurons not only survive in the system, but also exhibit positive axon growth. Next, neuronal response to acrylamide was evaluated through cytotoxicity assays and axon outgrowth measurement through immunocytochemistry. The study of neurotoxic effects on neuron maturation in collagen gels yielded two key observations: (1) the level of cell death in neurons exposed to acrylamide is dependent on the density and availability of attachment proteins in the collagen hydrogel environment and (2) the axonal retraction response is more sensitive to acrylamide than the lethal cellular response is. The ability of the collagen scaffold to provide insight into neuronal response to toxin in a biomimetic, three-dimensional environment suggests the system’s potential for increasing the accuracy of early stage cytotoxicity testing for safe and efficient pharmaceutical candidates. Additionally, this research has further implications in neurodegenerative disease modeling, spinal cord injury recovery studies, and basic research in neuroscience and neural tissue engineering

From Clinic to Kenya

This is the final draft of a magazine article I submitted to Anthropology News. The article details my undergraduate research experience during the summer of 2023. I joined the established Olosho Ethnobotany Project, and collaborated with Dr. Kristin Hedges to produce an ethnoveterinary component. Dr. Hedges and I, spent two weeks in Narok, Kenya documenting traditional medicine for livestock. The traditional medicine was specific to the Purko Maasai community. The research trip was transformational, and helped guide my scholarly aspirations as a future graduate student of veterinary medicine. This article has been accepted by Anthropology News and pending press early 2024

Proton conductivity versus acidic strength of one-pot synthesized acidic functionalized SBA-15 Mesoporous silica

International audienceThis paper reports the one-pot synthesis and characterization of functionalized mesoporous SBA-15 silica, containing two loadings of different acid groups (-CO2H, -PO(OH)2 and -SO3H). The thermodynamic features of the water confined in these porous silicas is investigated by Differential Scanning Calorimetry (DSC). The results show that the melting behaviour of the confined water is mainly governed by the pore diameter and, as a consequence, indicate that the chemical "decoration" of the porous surface does not play any key role on water thermodynamics in that case. On the contrary, the proton conductivity of the hydrated mesoporous materials, examined in a wide range of temperatures (-100 to 70°C), turns out to be strongly dependent on both the physical state of the confined water and the acidity of the functions located at the porous surface. The proton conductivity is shown to be directly related to the pKa and the density of the functional groups attached to the mesopore surface. The high conductivity values obtained at low temperature when the confined water is frozen, let us think that the -SO3H functionalized SBA-15 investigated here could be promising candidates for electrolyte solids applications in fuel cells

Selective Binding, Self-Assembly and Nanopatterning of the Creutz-Taube Ion on Surfaces

The surface attachment properties of the Creutz-Taube ion, i.e., [(NH3)5Ru(pyrazine)Ru(NH3)5]5+, on both hydrophilic and hydrophobic types of surfaces were investigated using X-ray photoelectron spectroscopy (XPS). The results indicated that the Creutz-Taube ions only bound to hydrophilic surfaces, such as SiO2 and –OH terminated organic SAMs on gold substrates. No attachment of the ions on hydrophobic surfaces such as –CH3 terminated organic SAMs and poly(methylmethacrylate) (PMMA) thin films covered gold or SiO2 substrates was observed. Further ellipsometric, atomic force microscopy (AFM) and time-dependent XPS studies suggested that the attached cations could form an inorganic analog of the self-assembled monolayer on SiO2 substrate with a “lying-down” orientation. The strong electrostatic interaction between the highly charged cations and the anionic SiO2 surface was believed to account for these observations. Based on its selective binding property, patterning of wide (∼200 nm) and narrow (∼35 nm) lines of the Creutz-Taube ions on SiO2 surface were demonstrated through PMMA electron resist masks written by electron beam lithography (EBL)

Valorization of rice husk silica waste:Organo-amine functionalized castor oil templated mesoporous silicas for biofuels synthesis

Rice husk is a rich source of waste silica which has potential for application in the preparation of porous materials for use as catalyst supports or sorbents. Here we report on the synthesis of rice husk silica (RHS) and mesoporous templated rice husk silica (MT-RHS) using sodium silicate, obtained from rice husk ash, and castor oil as a pore directing agent. The resulting silicas were functionalized with 3-aminopropyltriethoxysilane (APTS) or 3-diethylaminopropyltrimethoxysilane (DEPA), and their catalytic activity evaluated in the transesterification of model C4–C12 triglycerides (TAG) to their corresponding fatty acid methyl esters, of relevance to biodiesel synthesis. Castor oil templating enhances the surface area of rice husk silica, and introduces uniform 4 nm mesopores, albeit as a disordered pore network. Post-synthetic grafting of silica by APTS or DEPA resulted in base site loadings of 0.5 and 0.8 mmolg−1 respectively on RHS and MT-RHS. Turnover frequencies of amine-functionalized MT-RHS were 45–65% greater than those of their amine-functionalized RHS counterparts for tributyrin transesterification. Switching from a primary (APTS) to tertiary (DEPA) amine increased activity three-fold, delivering 80% tributyrin conversion to methyl butyrate in 6 h. DEPA-MT-RHS was effective for the transesterification of C8 and C12 triglycerides, with methyl caproate and methyl laurate selectivities of 93% and 71% respectively in 24 h

The Neo-Goodwinian model, reconsidered

This paper estimates the relationship between aggregate demand and the functional distribution of income in the U.S. economy using a series of aggregative VAR models. Like most previous aggregative studies, it finds evidence of Goodwin cycle effects - i.e. profit-led demand and a profit-squeeze effect - for the U.S. economy in baseline estimates using assumptions traditionally used in the aggregative literature. However, the results of other specifications suggest that these observed Goodwin cycle effects likely reflect a misinterpretation of procyclical variation in labor productivity - one of the main components of the wage share. When correcting for the cyclical effects of demand on productivity, the results differ dramatically; estimates are indicative of wage-led demand, and the effects of demand on distribution are mixed or insignificant. These findings suggest that evidence of Goodwin cycle effects is likely the result of biased estimates. Instead, it appears that the short-run relationship between the wage share and demand should be viewed as a combination of wage-led demand and procyclical productivity effects

The neo-Goodwinian model reconsidered

This paper examines the relationship between aggregate demand and the wage share in the US using a vector autoregression methodology. It finds evidence of Goodwin-cycle effects – that is, profit-led demand and a profit-squeeze effect – in baseline estimates using assumptions traditionally used in the aggregative literature. However, estimates that examine the relationship between demand and the two components of the wage share (the real wage rate and labor productivity) indicate that these results are highly sensitive to ordering restrictions relating demand and labor productivity and that different types of shocks to the wage share may have differing effects on demand. The results suggest two possible interpretations of the initial Goodwin-cycle finding, depending on the assumptions used to identify the demand–productivity relationship. One suggests that the initial estimates reflect a causal relationship in which the effects are driven by a positive effect of productivity on demand and a negative effect of demand on productivity. The other suggests that the initial Goodwin-cycle finding may be spurious, as it interprets contemporaneous pro-cyclical variation in labor productivity as a profit-led demand effect, thereby obscuring an underlying wage-led relationship