Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Microbial”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

A solid phase enzyme-linked immunosorbent assay for the antigenic detection of Legionella pneumophila (serogroup 1): A compliment for the space station diagnostic capability

It is necessary that an adequate microbiology capability be provided as part of the Health Maintenance Facility (HMF) to support expected microbial disease events and environmental monitoring during long periods of space flight. The application of morphological and biochemical studies to confirm the presence of certain bacterial and fungal disease agents are currently available and under consideration. This confirmation would be facilitated through employment of serological methods to aid in the identification of bacterial, fungal, and viral agents. A number of serological approaches are currently being considered, including the use of Enzyme Linked Immunosorbent Assay (ELISA) technology, which could be utilized during microgravity conditions. A solid phase, membrane supported ELISA for the detection of Legionella pneumophila, an expected disease agent, was developed to show a potential model system that would meet the HMF requirements and specifications for the future space station. These studies demonstrate the capability of membrane supported ELISA systems for identification of expected microbial disease agents as part of the HMF.

Hejtmancik, Kelly E.↗
NASA NTRS1987

Nitrogen transformations following tropical forest felling and burning on a volcanic soil

Nitrogen transformations and loss were measured following forest clearing in a relatively fertile tropical forest site. Nitrogen mineralization, nitrification, and amounts of ammonium and nitrate increased substantially in surface soils during the 6 mo following burning, then returned to background levels. The nitrogen content of microbial biomass declined to half its original value 6 mo after clearing and remained low in the cleared sites. Plant uptake of nitrogen was substantial on cleared plots (50 g/sq m), but it accounted for only 18 percent of N-15 label added to field plots. MIcrobial immobilization of N-15 was small relative to that in a cleared temperate site, and measurements of denitrification potentials suggested that relatively little mineralized nitrogen was lost to the atmosphere. Substantial amounts of nitrogen (40-70 g/sq m) were retained as exchangeably bound nitrate deep in the soils of a cleared plot on which revegetation was prevented; this process accounted for 12 percent of the N-15 label added to field plots.

Matson, Pamela A.↗
NASA NTRS1988

Search for Martian fossil communities: Science strategies, sediment sites, and sample handling

The strategy for locating and sampling possible fossilized Martian organisms benefits from our experience with fossil microbial ecosystems on Earth. Evidence of early life is typically preserved as stromatolites in carbonates and cherts, and as microfossils in cherts, carbonates and shales. Stromatolites, which are laminated flat or domal structures built by microbial communities, are very likely the oldest and most widespread relics of early life. These communities flourished in supratidal to subtidal coastal benthic environments, wherever sunlight was available and where incoming sediments were insufficient to bury the communities before they became established. A logical site for such communities on Mars might be those areas in an ancient lake bed which were furthest from sediment input, but were still sufficiently shallow to have received sunlight. Therefore, although some sites within Valles Marineris might have contained ponded water, the possibly abundant sediment inputs might have overwhelmed stromatolite-like communities. Localized depressions which acted as catchment basins for ancient branched valley systems might be superior sites. Perhaps such depressions received drainage which, because of the relatively modest water discharges implied for these streams, was relatively low in transported sediment. Multiple streams converging on a single basin might have been able to maintain a shallow water environment for extended periods of time.

Desmarais, David J.↗
NASA NTRS1990

The biogeochemistry of metal cycling

The results of the Planetary Biology and Microbial Ecology's summer 1987 program are summarized. The purpose of the interdisciplinary PBME program is to integrate, via lectures and laboratory work, the contributions of university and NASA scientists and student interns. The 1987 program examined various aspects of the biogeochemistry of metal cycling, and included such areas as limnology, metal chemistry, metal geochemistry, microbial ecology, and interactions with metals. A particular area of focus was the use of remote sensing in the study of biogeochemistry. Abstracts and bibliographies of the lectures and reports of the laboratory projects are presented.

Nealson, Kenneth H.↗
NASA NTRS1989

Electrochemical control of iodine disinfectant for space transportation system and space station potable water

An electrochemical microbial check valve method (EC-MCV) for controlling the iodine disinfectant in potable water (PW) for NASA's space operations was proposed. The factors affecting the design and performance of the unit were analyzed. This showed that it would be feasible to construct a recyclable unit in a small volume that will operate in either an iodine removal or addition mode. The EC-MCV should remove active iodine species rapidly from PW, but the rapid delivery rates at end-use may make complete removal of excess I(-) difficult under some conditions. Its performace change with AgI buildup needs to be investigated, as this controls the time for recycling the unit. The EC-MCV has advantages over the passive microbial check valve (MCV) method currently in use, as it would allow precise control of the I2 level and would not introduce excess I(-) to the water. The presence of oxygen in the EC-MCV needs to be investigated as it could affect the efficiency of I2 addition and excess I(-) removal.

Geer, Richard D.↗
NASA NTRS1990

Utilization of the water soluable fraction of wheat straw as a plant nutrient source

Recovery of water soluble, inorganic nutrients from the inedible portion of wheat was found to be an effective means of recycling nutrients within hydroponic systems. Through aqueous extraction (leaching), 60 percent of the total inorganic nutrient weight was removed from wheat straw and roots, although the recovery of individual nutrients varied. Leaching also removed about 20 percent of the total organic carbon from the biomass. In terms of dry weight, the leachate was comprised of approximately 60 percent organic and 40 percent inorganic compounds. Direct use of wheat straw leachate in static hydroponic systems had an inhibitory effect on wheat growth, both in the presence and absence of microorganisms. Biological treatment of leachate either with a mixed microbial community or the oyster mushroom Pleurotus ostreatus L., prior to use in hydroponic solutions, significantly reduced both the organic content and the inhibitory effects of the leachate. The inhibitory effects of unprocessed leachate appear to be a result of rapidly acting phytotoxic compounds that are detoxified by microbial activity. Leaching holds considerable promise as a method for nutrient recycling in a Controlled Ecological Life Support System (CELSS).

Mackowiak, C. L.↗
NASA NTRS1990

Space Station Freedom ECLSS: A step toward autonomous regenerative life support systems

The Environmental Control and Life Support System (ECLSS) is a Freedom Station distributed system with inherent applicability to extensive automation primarily due to its comparatively long control system latencies. These allow longer contemplation times in which to form a more intelligent control strategy and to prevent and diagnose faults. The regenerative nature of the Space Station Freedom ECLSS will contribute closed loop complexities never before encountered in life support systems. A study to determine ECLSS automation approaches has been completed. The ECLSS baseline software and system processes could be augmented with more advanced fault management and regenerative control systems for a more autonomous evolutionary system, as well as serving as a firm foundation for future regenerative life support systems. Emerging advanced software technology and tools can be successfully applied to fault management, but a fully automated life support system will require research and development of regenerative control systems and models. The baseline Environmental Control and Life Support System utilizes ground tests in development of batch chemical and microbial control processes. Long duration regenerative life support systems will require more active chemical and microbial feedback control systems which, in turn, will require advancements in regenerative life support models and tools. These models can be verified using ground and on orbit life support test and operational data, and used in the engineering analysis of proposed intelligent instrumentation feedback and flexible process control technologies for future autonomous regenerative life support systems, including the evolutionary Space Station Freedom ECLSS.

Dewberry, Brandon S.↗
NASA NTRS1989

Ecology of micro-organisms in a small closed system - Potential benefits and problems for Space Station

The probable sources and implications of microbial contamination on the proposed Space Station are discussed. Because of the limited availability of material, facilities and time on the Space Station, we are exploring the feasibility of replacing traditional incubation methods for assessing microbial contamination with rapid, automated methods. Some possibilities include: ATP measurement, microscopy and telecommunications, and molecular techniques such as DNA probes or monoclonal antibodies. Some of the important ecological factors that could alter microbes in space include microgravity, exposure to radiation, and antibiotic resistance.

Rodgers, E. B.↗
NASA NTRS1989

Biofilm formation and control in a simulated spacecraft water system - Interim results

The ability of iodine to control microbial contamination and biofilm formation in spacecraft water distribution systems is studied using two stainless steel water subsystems. One subsystem has an iodine level of 2.5 mg/L maintained by an iodinated ion-exchange resin. The other subsystem has no iodine added. Stainless steel coupons are removed from each system to monitor biofilm formation. Results from the first six months of operation indicate that 2.5 mg/L of iodine has limited the number of viable bacteria that can be recovered from the iodinated subsystem. Epifluorescence microscopy of the coupons taken from this subsystem, however, indicates some evidence of microbial colonization after 15 weeks of operation. Numerous bacteria have been continually removed from both the water samples and the coupons taken from the noniodinated subsystem after only 3 weeks of operation.

Schultz, John R.↗
NASA NTRS1990

Recent experiences with iodine water disinfection in Shuttle

Microbial proliferation in the STS potable water system is prevented by maintaining a 2-5 ppm iodine residual. The iodine is added to fuel cell water by an iodinated ion exchange resin in the Microbial Check Valve (MCV). Crew comments indicated excessive iodine in the potable water. To better define the problem, a method of in-flight iodine analysis was developed. Inflight analysis during STS-30 and STS-28 indicated iodine residuals were generally in the 9-13 ppm range. It was determined that the high iodine residual was caused by MCV influent temperatures in excess of 120 F. This is well above the MCV operating range of 65-90 F. The solution to this problem was to develop a resin suitable for the higher temperatures. Since 8 months were required to formulate a MCV resin suitable for the higher temperatures, a temporary solution was necessary. Two additional MCV's were installed on the chilled and ambient water lines leading into the galley to remove the excess iodine. These reduced the iodine residual to 3-4 ppm during STS-33, STS-34, STS-36 and STS-32. A high-temperature resin was formulated and initially flown on STS-31.

Gibbons, Randall E.↗
NASA NTRS1990

Spacelab 3 mission

Spacelab-3 (SL-3) was the first microgravity mission of extended duration involving crew interaction with animal experiments. This interaction involved sharing the Spacelab environmental system, changing animal food, and changing animal waste trays by the crew. Extensive microbial testing was conducted on the animal specimens and crew and on their ground and flight facilities during all phases of the mission to determine the potential for cross contamination. Macroparticulate sampling was attempted but was unsuccessful due to the unforseen particulate contamination occurring during the flight. Particulate debris of varying size (250 micron to several inches) and composition was recovered post flight from the Spacelab floor, end cones, overhead areas, avionics fan filter, cabin fan filters, tunnel adaptor, and from the crew module. These data are discussed along with solutions, which were implemented, for particulate and microbial containment for future flight facilities.

Dalton, Bonnie P.↗
NASA NTRS1992

Long-term corrosion evaluation of stainless steels in Space Shuttle iodinated resin and water

The effects of stainless steel exposure to iodinated water is a concern in developing the Integrated Water System (IWS) for Space Station Freedom. The IWS has a life requirement of 30 years, but the effects of general and localized corrosion over such a long period have not been determined for the candidate materials. In 1978, Umpqua Research Center immersed stainless steel 316L, 321, and 347 specimens in a solution of deionized water and the Space Shuttle microbial check valve resin. In April 1990, the solution was chemically analyzed to determine the level of corrosion formed, and the surface of each specimen was examined with scanning electron microscopy and metallography to determine the extent of general and pitting corrosion. This examination showed that the attack on the stainless steels was negligible and never penetrated past the first grain boundary layer. Of the three alloys, 316L performed the best; however, all three materials proved to be compatible with an aqueous iodine environment. In addition to the specimens exposed to aqueous iodine, a stainless steel specimen (unspecified alloy) was exposed to moist microbial check valve resin and air for a comparable period. This environment allowed contact of the metal to the resin as well as to the iodine vapor. Since the particular stainless steel alloy was not known, energy dispersive spectroscopy was used to determine that this alloy was stainless steel 301. The intergranular corrosion found on the specimen was limited to the first grain boundary layer.

Krohn, Douglas D.↗
NASA NTRS1992

Purification system

A system for prolonging the life of a granulated activated charcoal (GAC) water treatment device is disclosed in which an ultraviolet light transparent material is used to constrain water to flow over carbon surfaces. It is configured to receive maximum flux from a UV radiation source for the purpose of preventing microbial proliferation on the carbon surfaces; oxidizing organic contaminants adsorbed from the water onto the carbon surfaces and from biodegradation of adsorbed microbial forms; disinfecting water; and oxidizing organic contaminants in the water.

Flanagan, David T.↗
NASA NTRS1991

Water quality program elements for Space Station Freedom

A strategy is outlined for the development of water-quality criteria and standards relevant to recycling and monitoring the in-flight water for the Space Station Freedom (SSF). The water-reclamation subsystem of the SSF's ECLSS is described, and the objectives of the water-quality are set forth with attention to contaminants. Quality parameters are listed for potable and hygiene-related water including physical and organic parameters, inorganic constituents, bactericides, and microbial content. Comparisons are made to the quality parameters established for the Shuttle's potable water and to the EPA's current standards. Specific research is required to develop in-flight monitoring techniques for unique SSF contaminants, ECLSS microbial control, and on- and off-line monitoring. After discussing some of the in-flight water-monitoring hardware it is concluded that water reclamation and recycling are necessary and feasible for the SSF.

Sauer, Richard L.↗
NASA NTRS1992

Microbiological analysis of debris from STS-42 IML-1 by direct plating of rinse waters

Microbial analysis of air filter debris from the Spacelab International Microgravity Laboratory-1 (IML-1) mission was performed via direct plating of rinse waters on a battery of selective and nonselective nutrient agars. Microbial isolates were identified using Minitek and Biolog technologies. Twenty-four types of bacteria were recovered and classified; a similar number of fungal types was observed, but these were not identified. This procedure can provide information about the proportions of organism types present at the time of debris collection.

Smithers, G. A.↗
NASA NTRS1992

UPT scenarios: Implications for system reliability

The objective of this project was to examine the corrosion resistance of 316L stainless steel in several urine pre-treat solutions. Four solutions were examined: untreated urine (control); urine pretreated with oxone (potassium peroxymonosulfate sulfate); urine pretreated with sodium hypochlorite (NaOCl); and urine pretreated with ozone (O3). In accordance with current procedures, all solutions but the control were acidified to a pH of 2.5 using sulfuric acid--this suppresses the generation of ammonia in the solutions and is intended to limit microbial growth. Welded and unwelded coupons were exposed to each solution. In addition, Titanium coupons (welded and unwelded) were exposed to biologically active environmental control and life support system (ECLSS) water. Microbial attachment and biofilm growth were monitored. Ozone was examined as a biocide/oxidizer/corrosion preventative (simultaneous addition) and as a remediation method (added one week after exposure). In an unrelated effort, HP 9-4-30 coupons were exposed to biologically active solutions. Corrosion rates for welded and unwelded samples were determined--results were correlated to the ongoing HP 9-4-30 weldment stress corrosion study.

Walsh, Daniel W.↗
NASA NTRS1993

Reactive control and reasoning assistance for scientific laboratory instruments

Scientific laboratory instruments that are involved in chemical or physical sample identification frequently require substantial human preparation, attention, and interactive control during their operation. Successful real-time analysis of incoming data that supports such interactive control requires: (1) a clear recognition of variance of the data from expected results; and (2) rapid diagnosis of possible alternative hypotheses which might explain the variance. Such analysis then aids in decisions about modifying the experiment protocol, as well as being a goal itself. This paper reports on a collaborative project at the NASA Ames Research Center between artificial intelligence researchers and planetary microbial ecologists. Our team is currently engaged in developing software that autonomously controls science laboratory instruments and that provides data analysis of the real-time data in support of dynamic refinement of the experiment control. the first two instruments to which this technology has been applied are a differential thermal analyzer (DTA) and a gas chromatograph (GC). coupled together, they form a new geochemicstry and microbial analysis tool that is capable of rapid identification of the organiz and mineralogical constituents in soils. The thermal decomposition of the minerals and organics, and the attendance release of evolved gases, provides data about the structural and molecular chemistry of the soil samples.

Thompson, David E.↗
NASA NTRS1990

The ECLSS Advanced Automation Project Evolution and Technology Assessment

Viewgraphs on Environmental Control and Life Support System (ECLSS) advanced automation project evolution and technology assessment are presented. Topics covered include: the ECLSS advanced automation project; automatic fault diagnosis of ECLSS subsystems descriptions; in-line, real-time chemical and microbial fluid analysis; and object-oriented, distributed chemical and microbial modeling of regenerative environmental control systems description.

Dewberry, Brandon S.↗