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At least 127 records · Page 7

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DOE OSTI2026

Sampling Microbial Dynamics in the Salish Sea Estuary: Evaluating Methods to Capture Cyanobacteria and Cyanophage

Introduction: Picocyanobacteria from the genera Prochlorococcus and Synechococcus thrive across the globe in aquatic environments, have relatively small genomes, and have growth dynamics regulated by both viral interactions and abiotic conditions, making them excellent model organisms for exploring host-pathogencoevolution. Methods: We developed and refined methods to sample and sequence cyanobacteria, cyanophages, and measured features of their abiotic environment. Results: The protocol described herein can successfully discriminate large-cell eukaryotic organisms, but size fractionation of picocyanobacteria appears to be affected by the presence of free DNA, multicellular structures, and abundant tycheposons. Our preferred final protocol from this exploratory effort included a combination of in-line and single vacuum flask filtrations, which reduced filtration processing time by over threefold in some cases compared to other tested methods, such as a fully in-line sequence or in-site filtrations. We successfully extracted an average of approximately 400–1200 ng for all filter fractions, with some variations between kits. Discussion: The protocol described herein can successfully discriminate large-cell eukaryotic organisms, but size fractionation of picocyanobacteria appears to be affected by the presence of free DNA, multicellular structures, and abundant tycheposons.

Salish Sea↗

NASA NTRS1977

Effluent characterization from a conical pressurized fluid bed

To obtain useable corrosion and erosion results it was necessary to have data with several levels of particulate matter in the hot gases. One level of particulate loading was as low as possible so that ideally no erosion and only corrosion occurred. A conical fluidized bed was used to obtain some degree of filtration through the top of the bed which would not be highly fluidized. This would minimize the filtration required for the hot gases or conversely the amount of particulate matter in the hot gases after a given level of filtration by cyclones and/or filters. The data obtained during testing characterized the effluent from the bed at different test conditions. A range of bed heights, coal flows, air flows, limestone flows, and pressure are represented. These tests were made to determine the best operating conditions prior to using the bed to determine erosion and corrosion rates of typical turbine blade materials.

Priem, R. J.↗

NASA NTRS1977

Renal sodium reabsorption following induction of and recovery from volume expansion

In the rat, infusion of a volume of isotonic saline equal to 2% of body weight resulted in an 82% increase in the delivery of filtrate out of the proximal tubule but little or, in some animals, no change in the urinary excretion of sodium. By contrast, further degrees of volume expansion resulted in lesser increases in the distal delivery of filtrate, but were associated with a marked increase in the urinary excretion of sodium. Sixty minutes following completion of volume expansion, while the animals were still in positive sodium balance, the urinary excretion of sodium decreased 52% compared to a decrease of only 24% in the distal delivery of filtrate. During the course of progressive volume expansion and during the recovery phase, there was a dissociation between alterations in sodium reabsorption in the proximal convoluted tubule and in the whole kidney. These studies indicate that although the proximal tubule is more sensitive to changes in the extracellular fluid volume, distal nephron sites are ultimately responsible both for the natriuresis of volume expansion and the relative antinatriuresis of the recovery periods.

Knight, T. F.↗

NASA NTRS1987

Reduction of temperature rise in high-speed photography

Information is provided on filtration with glass and infrared absorbing and reflecting filters. Glass and infrared filtration is a simple and effective method to reduce the radiation heat transfer associated with continuous high intensity tungsten lamps. The results of a filtration experiment are explained. The figures provide starting points for quantifying the effectiveness of various filters and associated light intensities. The combination of a spectrally selective reflector (hot or cold mirror) based on multilayer thin film principles and heat absorbing or infrared opaque glass results in the maximum reduction in temperature rise with a minimum of incident light loss. Use is recommended of a voltage regulator to further control temperature rise and incident light values.

Slater, Howard A.↗

NASA NTRS1988

Reduction of temperature rise in high-speed photography

Slater, Howard A.↗

NASA NTRS1995

Alterations in glomerular and tubular dynamics at 1 and 14 days simulated microgravity and after acute return to orthostasis

Head-down tilt (HDT) is utilized to simulate microgravity and produces a cephalad fluid shift, which results in alterations in fluid and electrolyte balance. These changes in volume homeostasis are due, in part, to alterations in multiple volume control mechanisms in which renal function is a major participant. We have previously demonstrated that glomerular filtration rate increases early in HDT and eventually returns to values not different from non-tilt measurements. This early increase in glomerular filtration rate was also demonstrated during days 2 and 8 of the SLS-1 mission. However, urine flow and electrolyte excretion does not parallel the alternations in glomerular filtration rate and the site of this change in nephron fluid reabsorption pattern has not been previously examined. Through determination of the location of alterations in tubular fluid reabsorption within the nephron, a more detailed hypothesis can be forwarded as to which specific neuro-humoral agents participating in control or renal function in microgravity conditions. the importance of this type of examination is that measurements in circulating neuro-humoral agents and urinary excretion patterns alone are not accurate predictors of how renal functional response may alter to head-down tilt or other models of simulated weightlessness. To examine this issue, renal micropuncture techniques were utilized in Munich-Wistar rats submitted 24 hour and 14 day head-down tilt, measuring all the determinants of glomerular ultrafiltration and obtaining data regarding segmental tubular fluid reabsorption. Following these measurements, the rats were returned to an orthostatic position and after 60 minutes, the measurements were repeated.

Tucker, Bryan J.↗

NASA NTRS2000

Diffusion Driven Combustion Waves in Porous Media

Filtration of gas containing oxidizer, to the reaction zone in a porous medium, due, e.g., to a buoyancy force or to an external pressure gradient, leads to the propagation of Filtration combustion (FC) waves. The exothermic reaction occurs between the fuel component of the solid matrix and the oxidizer. In this paper, we analyze the ability of a reaction wave to propagate in a porous medium without the aid of filtration. We find that one possible mechanism of propagation is that the wave is driven by diffusion of oxidizer from the environment. The solution of the combustion problem describing diffusion driven waves is similar to the solution of the Stefan problem describing the propagation of phase transition waves, in that the temperature on the interface between the burned and unburned regions is constant, the combustion wave is described by a similarity solution which is a function of the similarity variable x/square root of(t) and the wave velocity decays as 1/square root of(t). The difference between the two problems is that in the combustion problem the temperature is not prescribed, but rather, is determined as part of the solution. We will show that the length of samples in which such self-sustained combustion waves can occur, must exceed a critical value which strongly depends on the combustion temperature T(sub b). Smaller values of T(sub b) require longer sample lengths for diffusion driven combustion waves to exist. Because of their relatively small velocity, diffusion driven waves are considered to be relevant for the case of low heat losses, which occur for large diameter samples or in microgravity conditions, Another possible mechanism of porous medium combustion describes waves which propagate by consuming the oxidizer initially stored in the pores of the sample. This occurs for abnormally high pressure and gas density. In this case, uniformly propagating planar waves, which are kinetically controlled, can propagate, Diffusion of oxidizer decreases the wave velocity. In addition to the reaction and diffusion layers, the uniformly propagating wave structure includes a layer with a pressure gradient, where the gas motion is induced by the production or consumption of the gas in the reaction as well as by thermal expansion of the gas. The width of this zone determines the scale of the combustion wave in the porous medium.

Aldushin, A. P.↗

NASA NTRS2004

Rotating Reverse Osmosis for Wastewater Reuse

Membrane filtration such as Reverse Osmosis (RO) removes ions, proteins, and organic chemicals which are generally very difficult to remove using conventional treatment. Moreover, membrane is an absolute filtration method, so its treatment efficiency and performance are stable and predictable. We are currently working on the development of rotating RO membrane system. Dynamic rotating membrane filtration, which can produce a high shear rate, may be helpful to obtain high rejection of organic pollutants.The goal of our current work is to improve the flux of the device by increasing pressure by a factor of 3 to 4. In addition, the rejections for a wider variety of inorganic and organic compounds typically found in space mission wastewater are measured.

Lueptow, Richard M.↗

NASA NTRS1998

Measurement of net whole-body transcapillary fluid transport and effective vascular compliance in humans

BACKGROUND: Net whole-body transcapillary fluid transport (TFT) between the circulation and the interstitial (extravascular) space may be calculated as: IV - deltaPV - UV - IL, where IV=infused or ingested volume (when applicable), deltaPV = change in plasma volume, UV=urine volume, and IL=insensible loss. RESULTS: Infusion of 30 mL/kg isotonic saline over 25 minutes increased supine TFT from a basal capillary reabsorption of -106+/-24 mL/h (mean+/-SE) to a net filtration of 1,229+/-124 mL/h. One hour after infusion, reabsorption of -236+/-102 mL/h was seen, and control reabsorption levels returned by 3 hours. Four hours of 30 mm Hg lower body negative pressure (LBNP) elicited no net TFT, probably because of upper body reabsorptive compensation for lower body capillary filtration. When ingestion of 1 L of isotonic saline accompanied LBNP, filtration of 145+/-10 mL/h occurred. Reabsorption of extravascular fluid into the circulation always followed LBNP. CONCLUSION: Application of this technique could aid understanding of physiologic conditions, experimental interventions, disease states, and therapies that cause or are influenced by fluid shifts between intravascular and interstitial compartments.

NASA Center JSC↗

NASA NTRS1992

Glomerular hemodynamic alterations during acute hyperinsulinemia in normal and diabetic rats

Treatment of insulin dependent diabetes invariably requires exogenous insulin to control blood glucose. Insulin treatment, independent of other factors associated with insulin dependent diabetes, may induce changes that affect glomerular function. Due to exogenous delivery of insulin in insulin dependent diabetes entering systemic circulation prior to the portal vein, plasma levels of insulin are often in excess of that observed in non-diabetics. The specific effects of hyperinsulinemia on glomerular hemodynamics have not been previously examined. Micropuncture studies were performed in control (non-diabetic), untreated diabetic and insulin-treated diabetic rats 7 to 10 days after administration of 65 mg/kg body weight streptozotocin. After the first period micropuncture measurements were obtained, 5 U of regular insulin (Humulin-R) was infused i.v., and glucose clamped at euglycemic values (80 to 120 mg/dl). Blood glucose concentration in non-diabetic controls was 99 +/- 6 mg/dl. In control rats, insulin infusion and glucose clamp increased nephron filtration rate due to decreases in both afferent and efferent arteriolar resistance (afferent greater than efferent) resulting in increased plasma flow and increased glomerular hydrostatic pressure gradient. However, insulin infusion and glucose clamp produced the opposite effect in both untreated and insulin-treated diabetic rats with afferent arteriolar vasoconstriction resulting in decreases in plasma flow, glomerular hydrostatic pressure gradient and nephron filtration rate. Thromboxane A2 (TX) synthetase inhibition partially decreased the vasoconstrictive response due to acute insulin infusion in diabetic rats preventing the decrease in nephron filtration rate.(ABSTRACT TRUNCATED AT 250 WORDS).

NASA Discipline Cardiopulmonary↗

NASA NTRS2008

Portable Nanomesh Creates Safer Drinking Water

Providing astronauts with clean water is essential to space exploration to ensure the health and well-being of crewmembers away from Earth. For the sake of efficient and safe long-term space travel, NASA constantly seeks to improve the process of filtering and re-using wastewater in closed-loop systems. Because it would be impractical for astronauts to bring months (or years) worth of water with them, reducing the weight and space taken by water storage through recycling and filtering as much water as possible is crucial. Closed-loop systems using nanotechnology allow wastewater to be cleaned and reused while keeping to a minimum the amount of drinking water carried on missions. Current high-speed filtration methods usually require electricity, and methods without electricity usually prove impractical or slow. Known for their superior strength and electrical conductivity, carbon nanotubes measure only a few nanometers in diameter; a nanometer is one billionth of a meter, or roughly one hundred-thousandth the width of a human hair. Nanotubes have improved water filtration by eliminating the need for chemical treatments, significant pressure, and heavy water tanks, which makes the new technology especially appealing for applications where small, efficient, lightweight materials are required, whether on Earth or in space. "NASA will need small volume, effective water purification systems for future long-duration space flight," said Johnson Space Center s Karen Pickering. NASA advances in water filtration with nanotechnology are now also protecting human health in the most remote areas of Earth.

Source record↗

NASA NTRS2012

Use of Aquaporins to Achieve Needed Water Purity on the International Space Station for the Extravehicular Mobility Unit Space Suit System

With the retirement of the U.S. Space Shuttle fleet, the supply of extremely high quality water required for the Extravehicular Mobility Unit (EMU) space suit cooling on the International Space Station (ISS) will become a significant operational hardware challenge in the very near future. One proposed solution is the use of a filtration system consisting of a semipermeable membrane embedded with aquaporin proteins, a special class of transmembrane proteins that facilitate passive, selective transport of water in vivo. The specificity of aquaporins is such that only water is allowed through the protein structure, and it is this novel property that invites their adaptation for use in water filtration systems, specifically those onboard the ISS for the EMU space suit system. These proteins are also currently being developed for use in terrestrial filtration systems.

Hill, Terry R.↗

NASA NTRS2012

Hybrid Filter Membrane

Cabin environmental control is an important issue for a successful Moon mission. Due to the unique environment of the Moon, lunar dust control is one of the main problems that significantly diminishes the air quality inside spacecraft cabins. Therefore, this innovation was motivated by NASA s need to minimize the negative health impact that air-suspended lunar dust particles have on astronauts in spacecraft cabins. It is based on fabrication of a hybrid filter comprising nanofiber nonwoven layers coated on porous polymer membranes with uniform cylindrical pores. This design results in a high-efficiency gas particulate filter with low pressure drop and the ability to be easily regenerated to restore filtration performance. A hybrid filter was developed consisting of a porous membrane with uniform, micron-sized, cylindrical pore channels coated with a thin nanofiber layer. Compared to conventional filter media such as a high-efficiency particulate air (HEPA) filter, this filter is designed to provide high particle efficiency, low pressure drop, and the ability to be regenerated. These membranes have well-defined micron-sized pores and can be used independently as air filters with discreet particle size cut-off, or coated with nanofiber layers for filtration of ultrafine nanoscale particles. The filter consists of a thin design intended to facilitate filter regeneration by localized air pulsing. The two main features of this invention are the concept of combining a micro-engineered straight-pore membrane with nanofibers. The micro-engineered straight pore membrane can be prepared with extremely high precision. Because the resulting membrane pores are straight and not tortuous like those found in conventional filters, the pressure drop across the filter is significantly reduced. The nanofiber layer is applied as a very thin coating to enhance filtration efficiency for fine nanoscale particles. Additionally, the thin nanofiber coating is designed to promote capture of dust particles on the filter surface and to facilitate dust removal with pulse or back airflow.

Laicer, Castro↗

NASA NTRS2001

Nonwoven Fabric Uses and Prospects in Human Space Flight

The US space shuttle fleet has been flying for over 20 years. Although the shuttle operates in a unique exterior environment, the interior is intentionally made to be as close to the "normal" human environment as possible. The filtration needs of the shuttle are not substantially different from those of a large mobile home or camper, supporting the needs of a family of seven for up to two weeks. Therefore, most of the materials that are used to filter the air, water, and other fluids on the Shuttle are similar or identical to those employed in other sectors of the transportation industry. The only significantly different feature of the space environment is the unique "three-phase" nature of the air (with suspended liquids and solids ranging in size from aerosol droplets to binoculars). Such suspended debris contributes to the air filtration and waste management problem. Careful flow management and cleanliness practices help to mitigate the effect of debris, and liquid spills are rare, seldom making it to the filters. (It has been common on all spacecraft to look first for lost items on the air intake filters, since all objects ultimately migrate there in the flow. Liquids tend to seep rather than "spill", and so tend to aggregate in a ball near the source.) In addition to the basic fluids of the interior environment (water and water wastes, air, and its constituent supply gasses) the shuttle also has unfiltered fluid systems for Freon, hydrogen, helium, ammonia, hydraulic fluid, and propellants. Only the propellant system, owing to its uncommon chemistry, represents a fluid system that is not typical of household or medical applications. Careful external filtration prior to flight assures the cleanliness in these closed systems.

Bacon, Jack↗

NASA NTRS2018

Development of a Multi-Stage Filter System for Cabin Ventilation Systems on the ISS and Future Deep Space Missions

The National Aeronautics and Space Administration's (NASA's) deep space exploration missions will be of significant duration requiring long-life and reliably performing spacecraft cabin ventilation filters. A particulate filter system is being developed at NASA Glenn Research Center (GRC) to meet the challenges of these remote and long duration missions. The capabilities and features of the filter system are expected to expand the life and reduce the maintenance requirements over that of the current ISS (International Space Station) filter by providing pre-filtration stages with novel self-cleaning and regenerable techniques. The filter provides two regenerable pre-filtration stages using a screen mesh media and an impactor collection system, and also provides intermediate stage filtration employing self-replacing filter media. The filter system is also designed to be compatible with the interfaces and performance requirements of the ISS distributed ventilation architecture in the US modules to facilitate testing on ISS type test or mock up platforms. Currently, a prototype of the filter system is undergoing tests in a custom configured filter test stand at the NASA GRC. The test stand provides the same range of flow rates produced on the ISS distributed architecture, and is equipped and instrumented to perform filter tests based on industrial test standards. The test stand has been used successfully to perform filter and flow performance test on returned ISS Bacterial Filter Elements. Similar test protocols were used to characterize the performance of the current filter system. Different performing grades of filter media will be installed and tested on the filter system, and different test particle standards will be used to simulate the range of particulate matter particles and debris the filter will see during a mission. This paper will present results and analysis of the test data to guide and provide input to the next generation filter system.

ISS↗

NASA NTRS2019

Scroll Filter System Development for Crewed Deep Space Missions

On board the International Space Station, particulate HEPA filters known as Bacterial Filter Elements (BFE's) are used as the main ventilation filters on the US modules. They consist of two stages of filtration, a static screen filter and a HEPA filter element. Historically, these filters have performed well during the life of the ISS. However, as NASA sets its sights towards mission beyond low earth orbit, or deep space, more capable filters requiring minimal maintenance will be essential because of the nature of these remote and of long duration missions. Therefore NASA is currently developing new filter systems for these mission. One of the filter designs being considered is a new filter system, coined the Scroll BFE. This filter provides two stages of filtration. The first stage is a pre-filter stage using a roll of screen media on a motorized spooling, or scrolling, mechanism to automate the change-out of the screen media in the flow. The second and finishing stage is a static HEPA filter element similar to the ones used on the ISS BFE's. The volume and dimensional format of the filter matches that of the ISS BFE which facilitates is deployment as potential future flight technology demonstration on board the ISS. Ground tests are underway to assess the filter system's performance under industrial standard test protocols applied in a custom designed filtration test stand. In addition, a method of generating relevant particulate matter loads, such as loose fibrous matter, is also being devised to challenge the filter in testing. The latter test challenge will help determine the pre-filter's capacity for handling layers of lint, or fibrous, particulate matter. Early results confirm HEPA efficiency performance of the HEPA stage. This paper will present the results of ground testing of the Scroll Filter System prototype.

Agui, Juan H.↗

NASA NTRSDate not supplied

Inertial Centrifugal-Based Pre-filter for Spacecraft Life Support Systems

The intrusion of planetary dust inside space vehicles on future Lunar missions may lead to performance compromises of the cabin air-filtration system. The evasive character of the fine planetary dust, in particular lunar dust, could enable the dust to make its way through the seals and barriers of the EVA hatches and become airborne in the cabin. This can result in performance and capacity overload of the high efficiency filter media and particle separation systems. Adequate pre-filtration can substantially reduce the load on the higher efficiency components leading to smaller dust loads during surge and nominal dust loading conditions, thereby protecting and extending the life of these components. A particle separation concept, based on centrifugal separation, is being investigated for its application as a pre-filter. The concept has previously been proposed for application in the aircraft engine industry, as means of capturing corrosive dust and salt deposits that may harm the engine. The technique has the advantages of being passive, integrable to HVAC and space vehicle architecture, and has the potential for high degree of particle separation with proper fluid dynamic design. Computational Fluid Dynamics (CFD) and particle tracing modeling were used to arrive at an initial design for rapid prototyping and testing. If feasible, the concept can be integrated to the Scroll Filter System which is being developed by NASA to address the filtration demands on long during spaceflight and surface missions. This paper will describe the modeling results of this concept.

Life Support Systems↗

NASA NTRSDate not supplied

Inertial Centrifugal-Based Pre-filter for Spacecraft Life Support Systems

Life Support Systems↗