AI for Technoscientific Discovery: A Human-Inspired Architecture
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97 MATHEMATICS AND COMPUTING↗
Engineering topics
Johnson, C. M.
Publications and source records attributed to Johnson, C. M..
Microgreens for Human Nutrition in Spaceflight
For long-duration spaceflight missions, providing adequate nutritional needs of the crew is a documented risk. This can be mitigated with dietary supplementation of nutrient-dense young vegetables including microgreens. Why microgreens? Traditional crops can take months to mature, but microgreens are ready to harvest in within two weeks, and they can be grown in small volumes. This rapid turn-around time makes them practical for any spaceflight scenario where crew time is limited, or when power, mass, and volume limitations prevent growing crops to maturity. In this literature review we will introduce microgreens that have been screened by the USDA for nutritional content, and discuss their nutritional benefits in relation to the specific needs of astronauts, as defined by the NASA Human Research Program. We will specifically highlight the benefits of iron, magnesium, potassium, and carotenoids. We also discuss potential lighting and fertilizer regimens that could be used to further improve nutrient content of microgreens grown in microgravity. Developing microgreens for spaceflight will give us access to crops that are specifically designed to meet crew nutritional needs for future exploration missions.
Johnson, C. M.↗
Baseline Microbial Assessment of Fresh Produce
Currently no standards or requirements exist for microbial food safety for space grown produce (fresh plant foods). Without standards it is difficult to assess produce handling and sanitization options for the ISS and future exploration missions. We are conducting a literature review of microbial levels on fresh food and then carrying out measurements (microbial counts) of grocery store purchased and controlled environment-grown crops. Testing will include lettuce, mizuna, cherry tomato, pepper, and radish, all candidate crops for pick-and-eat testing on ISS and near term exploration missions. Growth chamber conditions will be set to mimic an ISS or spacecraft environment. Assays will include specific pathogens (Enterobacteriacea, Salmonella sp., and Aspergillus flavus) and total culturable microorganisms using aerobic plate counts, and total yeast and mold counts. Analyses will follow the FDA Bacteriological Analytical Manual methods. The goal of the project is to establish a baseline for expected microbial levels found on fresh plant foods that might be grown on ISS and near term missions, and develop risk assessment and microbial safety recommendations for these types of fresh foods.
Hummerick, M. E.↗
Iron isotope biosignatures
The (56)Fe/(54)Fe of Fe-bearing phases precipitated in sedimentary environments varies by 2.5 per mil (delta(56)Fe values of +0.9 to -1. 6 per mil). In contrast, the (56)Fe/(54)Fe of Fe-bearing phases in igneous rocks from Earth and the moon does not vary measurably (delta(56)Fe = 0.0 +/- 0.3 per mil). Experiments with dissimilatory Fe-reducing bacteria of the genus Shewanella algae grown on a ferrihydrite substrate indicate that the delta(56)Fe of ferrous Fe in solution is isotopically lighter than the ferrihydrite substrate by 1.3 per mil. Therefore, the range in delta(56)Fe values of sedimentary rocks may reflect biogenic fractionation, and the isotopic composition of Fe may be used to trace the distribution of microorganisms in modern and ancient Earth.
NASA Center JPL↗
Current economic and sensitivity analysis for ID slicing of 4 inch and 6 inch diameter silicon ingots for photovoltaic applications
The economics and sensitivities of slicing large diameter silicon ingots for photovoltaic applications were examined. Current economics and slicing add on cost sensitivities are calculated using variable parameters for blade life, slicing yield, and slice cutting speed. It is indicated that cutting speed has the biggest impact on slicing add on cost, followed by slicing yield, and by blade life as the blade life increases.
Roberts, E. G.↗
Continuous Czochralski growth: Silicon sheet growth development of the large area sheet task of the low cost silicon solar array project
The growth of 100 kg of silicon single crystal material, ten cm in diameter or greater, and 150 kg of silicon single crystal material 15 cm or greater utilizing one common silicon container material (one crucible) is investigated. A crystal grower that is recharged with a new supply of polysilicon material while still under vacuum and at temperatures above the melting point of silicon is developed. It accepts large polysilicon charges up to 30 kg, grows large crystal ingots (to 15 cm diameter and 25 kg in weight), and holds polysilicon material for recharging (rod or lump) while, at the same time, growing crystal ingots. Special equipment is designed to recharge polysilicon rods, recharge polysilicon lumps, and handle and store large, hot silicon crystal ingots. Many continuous crystal growth runs were performed lasting as long as 109 hours and producing as many as ten crystal ingots, 15 cm with weights progressing to 27 kg.
Johnson, C. M.↗
Investigation of the role of selenium in the nutrition and physiology of neural tissues of chickens and turkeys
Endogenous selenium concentrations in selected tissue of chickens, turkeys, and coturnix
Johnson, C. M.↗