Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “High salinity”

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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

NASA Tech Briefs, April 2013

Topics covered include: Fully Integrated, Miniature, High-Frequency Flow Probe Utilizing MEMS Leadless SOI Technology; Nanoscale Surface Plasmonics Sensor With Nanofluidic Control; Advanced Dispersed Fringe Sensing Algorithm for Coarse Phasing Segmented Mirror Telescopes; Neural Network Back-Propagation Algorithm for Sensing Hypergols; Bulk Moisture and Salinity Sensor; Change-Based Satellite Monitoring Using Broad Coverage and Targetable Sensing; Circularly Polarized Microwave Antenna Element with Very Low Off-Axis Cross-Polarization; Ultra-Low Heat-Leak, High-Temperature Superconducting Current Leads for Space Applications; Flash Cracking Reactor for Waste Plastic Processing; An Automated Safe-to-Mate (ASTM) Tester; Wireless Chalcogenide Nanoionic-Based Radio-Frequency Switch; Compute Element and Interface Box for the Hazard Detection System; DOT Transmit Module; Composite Aerogel Multifoil Protective Shielding; Li-Ion Electrolytes with Improved Safety and Tolerance to High-Voltage Systems; Polymer-Reinforced, Non-Brittle, Lightweight Cryogenic Insulation; Controlled, Site-Specific Functionalization of Carbon Nanotubes with Diazonium Salts; Regenerable Sorbent for CO2 Removal; Sprayable Aerogel Bead Compositions With High Shear Flow Resistance and High Thermal Insulation Value; Lexan Linear Shaped Charge Holder with Magnets and Backing Plate; Robotic Ankle for Omnidirectional Rock Anchors; Wind, Wave, and Tidal Energy Without Power Conditioning; An Active Heater Control Concept to Meet IXO Type Mirror Module Thermal-Structural Distortion Requirement; Waterless Clothes-Cleaning Machine; Integrated Electrical Wire Insulation Repair System; LVGEMS Time-of-Flight Mass Spectrometry on Satellites; Surface Inspection Tool for Optical Detection of Surface Defects; Per-Pixel, Dual-Counter Scheme for Optical Communications; Certification-Based Process Analysis; Surface Navigation Using Optimized Waypoints and Particle Swarm Optimization; Smart-Divert Powered Descent Guidance to Avoid the Backshell Landing Dispersion Ellipse; Estimating Foreign-Object-Debris Density from Photogrammetry Data; Adaptive Sampling of Spatiotemporal Phenomena with Optimization Criteria; Building a 2.5D Digital Elevation Model From 2D Imagery; Eyes on the Earth 3D; Target Trailing With Safe Navigation for Maritime Autonomous Surface Vehicles; Adams-Based Rover Terramechanics and Mobility Simulator - ARTEMIS; ISTP CDF Skeleton Editor; Uplink Summary Generator (ULSGEN) Version 1.0; Robotics On-Board Trainer (ROBoT); Software Engineering Tools for Scientific Models; Automatic Data Filter Customization Using a Genetic Algorithm; Tracker Toolkit; Towards Efficient Scientific Data Management Using Cloud Storage; On a Formal Tool for Reasoning About Flight Software Cost Analysis; A Nanostructured Composites Thermal Switch Controls Internal and External Short Circuit in Lithium Ion Batteries; Spacecraft Crew Cabin Condensation Control; and Functional Near-Infrared Spectroscopy Signals Measure Neuronal Activity in the Cortex.

Source record↗
DOE OSTI2023

High-Performance Hemofiltration via Molecular Sieving and Ultra-Low Friction in Carbon Nanotube Capillary Membranes

Conventional dialyzer membranes typically comprise of unevenly distributed polydisperse, tortuous, rough pores, embedded in relatively thick ≈20–50 µm polymer layers wherein separation occurs via size exclusion as well as differences in diffusivity of the permeating species. However, transport in such polymeric pores is increasingly hindered as the molecule size approaches the pore dimension, resulting in significant retention of undesirable middle molecules (≥15–60 kDa) and uremic toxins. Enhanced removal of middle molecules is usually accompanied by high albumin loss (≈66 kDa) causing hypoalbuminemia. Here, the scalable bottom-up fabrication of wafer-scale carbon nanotube (CNT) membranes with highly aligned, low-friction, straight-channels/capillaries and narrow pore-diameter distributions (≈0.5–4.5 nm) is demonstrated, to overcome persistent challenges in hemofiltration/hemodialysis. Using fluorescein isothiocyanate (FITC)-Ficoll 70 and albumin in phosphate buffered saline (PBS) as well as in bovine blood plasma, it is shown that CNT membranes can allow for significantly higher hydraulic permeability (more than an order of magnitude when normalized to pore area) than commercial high-flux hemofiltration/hemodialysis membranes (HF 400), as well as greatly enhance removal of middle molecules while maintaining comparable albumin retention. These findings are rationalized via an N-pore transport model that highlights the critical role of molecular flexing and deformation during size-selective transport within nanoscale confinements of the CNTs. In conclusion, the unique transport characteristics of CNTs coupled with size-exclusion and wafer-scale fabrication offer transformative advances for hemofiltration, and the obtained insight into molecular transport can aid advancements in several other bio-systems/applications beyond hemofiltration/hemodialysis.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Salinization and sedimentation drive contrasting assembly mechanisms of planktonic and sediment‐bound bacterial communities in agricultural streams

Abstract Agriculture is the most dominant land use globally and is projected to increase in the future to support a growing human population but also threatens ecosystem structure and services. Bacteria mediate numerous biogeochemical pathways within ecosystems. Therefore, identifying linkages between stressors associated with agricultural land use and responses of bacterial diversity is an important step in understanding and improving resource management. Here, we use the Mississippi Alluvial Plain (MAP) ecoregion, a highly modified agroecosystem, as a case study to better understand agriculturally associated drivers of stream bacterial diversity and assembly mechanisms. In the MAP, we found that planktonic bacterial communities were strongly influenced by salinity. Tolerant taxa increased with increasing ion concentrations, likely driving homogenous selection which accounted for ~90% of assembly processes. Sediment bacterial phylogenetic diversity increased with increasing agricultural land use and was influenced by sediment particle size, with assembly mechanisms shifting from homogenous to variable selection as differences in median particle size increased. Within individual streams, sediment heterogeneity was correlated with bacterial diversity and a subsidy‐stress relationship along the particle size gradient was observed. Planktonic and sediment communities within the same stream also diverged as sediment particle size decreased. Nutrients including carbon, nitrogen, and phosphorus, which tend to be elevated in agroecosystems, were also associated with detectable shifts in bacterial community structure. Collectively, our results establish that two understudied variables, salinity and sediment texture, are the primary drivers of bacterial diversity within the studied agroecosystem, whereas nutrients are secondary drivers. Although numerous macrobiological communities respond negatively, we observed increasing bacterial diversity in response to agricultural stressors including salinization and sedimentation. Elevated taxonomic and phylogenetic bacterial diversity likely increases the probability of detecting community responses to stressors. Thus, bacteria community responses may be more reliable for establishing water quality goals within highly modified agroecosystems that have experienced shifting baselines.

DeVilbiss, Stephen E.↗
DOE OSTI2023

High methane concentrations in tidal salt marsh soils: Where does the methane go?

Abstract Tidal salt marshes produce and emit CH 4 . Therefore, it is critical to understand the biogeochemical controls that regulate CH 4 spatial and temporal dynamics in wetlands. The prevailing paradigm assumes that acetoclastic methanogenesis is the dominant pathway for CH 4 production, and higher salinity concentrations inhibit CH 4 production in salt marshes. Recent evidence shows that CH 4 is produced within salt marshes via methylotrophic methanogenesis, a process not inhibited by sulfate reduction. To further explore this conundrum, we performed measurements of soil–atmosphere CH 4 and CO 2 fluxes coupled with depth profiles of soil CH 4 and CO 2 pore water gas concentrations, stable and radioisotopes, pore water chemistry, and microbial community composition to assess CH 4 production and fate within a temperate tidal salt marsh. We found unexpectedly high CH 4 concentrations up to 145,000 μmol mol −1 positively correlated with S 2− (salinity range: 6.6–14.5 ppt). Despite large CH 4 production within the soil, soil–atmosphere CH 4 fluxes were low but with higher emissions and extreme variability during plant senescence (84.3 ± 684.4 nmol m −2 s −1 ). CH 4 and CO 2 within the soil pore water were produced from young carbon, with most Δ 14 C‐CH 4 and Δ 14 C‐CO 2 values at or above modern. We found evidence that CH 4 within soils was produced by methylotrophic and hydrogenotrophic methanogenesis. Several pathways exist after CH 4 is produced, including diffusion into the atmosphere, CH 4 oxidation, and lateral export to adjacent tidal creeks; the latter being the most likely dominant flux. Our findings demonstrate that CH 4 production and fluxes are biogeochemically heterogeneous, with multiple processes and pathways that can co‐occur and vary in importance over the year. This study highlights the potential for high CH 4 production, the need to understand the underlying biogeochemical controls, and the challenges of evaluating CH 4 budgets and blue carbon in salt marshes.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1999

Evaluation of Factors Affecting Powdered Drug Reconstitution in Microgravity

Owing to the high cost of transporting mass into space, and the small volume available for equipment in the Space Shuttle Orbiter and the International Space Station, refrigeration space is extremely limited. For this reason, there exists strong motivation for transporting certain drugs in powdered form so that they do not require refrigeration. When needed, the powdered drug will be mixed with saline to obtain a liquid form that may be injected intravenously. While this is a relatively simple task in a 1-G environment, there are some difficulties that may be encountered in 0-G. In non-accelerated spaceflight, gravitational and inertial forces are eliminated allowing other smaller forces, such as capillary forces and surface tension, to dominate the behavior of fluids. For instance, water slowly ejected from a straw will tend to form a sphere, while fluid in a container will tend to wet the inside surface forming a highly rounded meniscus. Initial attempts at mixing powdered drugs with saline in microgravity have shown a tendency toward forming foamy emulsions instead of the desired homogeneous solution. The predominance of adhesive forces between the drug particles and the interface tensions at the gas/liquid and solid/liquid interfaces drastically reduce the rate of deaggregation of the drug powder and also reduce the rate of absorption of saline by the powder mass. In addition, the capillary forces cause the saline to wet the inside of the container, thus trapping air bubbles within the liquid. The rate of dissolution of a powder drug is directly proportional to the amount of surface area of the solid that is exposed to liquid solvent. The surface area of drug that is in contact with the liquid is greatly reduced in microgravity and, as a result, the dissolution rate is reduced as well. The KC-135 research described here was aimed at evaluating the extent to which it is possible to perform drug reconstitution in the weightlessness of parabolic flight using standard pharmacological supplies. The experiment included a parametric assessment of possible factors affecting the reconstitution process. The specific questions that we wished to answer were: (1) Is it possible to reconstitute powdered drugs in weightlessness using standard pharmacological equipment? (2) What are the differences between drug reconstitution in a 1-G and a 0-G environment? (3) What techniques of mixing the drug powder and diluent are more successful? (4) What physical and chemical factors play a role in determining the success of mixing and dissolution? (5) Is it necessary to employ crewmember and equipment restraints during the reconstitution process?

Schaffner, Grant↗
NASA NTRS2000

Arctic Ocean

The Arctic Ocean is the smallest of the Earth's four major oceans, covering 14x10(exp 6) sq km located entirely within the Arctic Circle (66 deg 33 min N). It is a major player in the climate of the north polar region and has a variable sea ice cover that tends to increase its sensitivity to climate change. Its temperature, salinity, and ice cover have all undergone changes in the past several decades, although it is uncertain whether these predominantly reflect long-term trends, oscillations within the system, or natural variability. Major changes include a warming and expansion of the Atlantic layer, at depths of 200-900 m, a warming of the upper ocean in the Beaufort Sea, a considerable thinning (perhaps as high as 40%) of the sea ice cover, a lesser and uneven retreat of the ice cover (averaging approximately 3% per decade), and a mixed pattern of salinity increases and decreases.

Parkinson, Claire L.↗
NASA NTRS2013

Assessing Habitability: Lessons from the Phoenix Mission

The Phoenix mission's key objective was to search for a habitable zone. The Phoenix lander carried a robotic arm with digging scoop to collect soil and icy material for analysis with an instrument payload that included volatile mineral and organic analysis(3) and soil ionic chemistry analysis (4). Results from Phoenix along with theoretical modeling and other previous mission results were used to evaluate the habitability of the landing site by considering four factors that characterize the environments ability to support life as we know it: the presence of liquid water, the presence of an energy source to support metabolism, the presence of nutrients containing the fundamental building blocks of life, and the absence of environmental conditions that are toxic to or preclude life. Phoenix observational evidence for the presence of liquid water (past or present) includes clean segregated ice, chemical etching of soil grains, calcite minerals in the soil and variable concentrations of soluble salts5. The maximum surface temperature measured was 260K so unfrozen water can form only in adsorbed films or saline brines but warmer climates occur cyclically on geologically short time scales due to variations in orbital parameters. During high obliquity periods, temperatures allowing metabolism extend nearly a meter into the subsurface. Phoenix discovered ~1%w/w perchlorate salt in the soil, a chemical energy source utilized by a wide range of microbes. Nutrient sources including C, H, N, O, P and S compounds are supplied by known atmospheric sources or global dust. Environmental conditions are within growth tolerance for terrestrial microbes. Summer daytime temperatures are sufficient for metabolic activity, the pH is 7.8 and is well buffered and the projected water activity of a wet soil will allow growth. In summary, martian permafrost in the north polar region is a viable location for modern life. Stoker et al. presented a formalism for comparing the habitability of various regions visited to date on Mars that involved computing a habitability probability, defined as the product of probabilities for the presence of liquid water (P(sub lw)), energy (P(sub e)), nutrients (P(sub ch)), and a benign environment (P(sub b)). Using this formalism, they argued that the Phoenix site was the most habitable of any site visited to date by landed missions and warranted a follow up mission to search for modern evidence of life. This paper will review that conclusion in view of more recent information from the Mars Exploration Rovers and Mars Science Lander missions.

Stoker, Carol R.↗
NASA NTRS2013

Intravenous Fluid Generation System

The ability to stabilize and treat patients on exploration missions will depend on access to needed consumables. Intravenous (IV) fluids have been identified as required consumables. A review of the Space Medicine Exploration Medical Condition List (SMEMCL) lists over 400 medical conditions that could present and require treatment during ISS missions. The Intravenous Fluid Generation System (IVGEN) technology provides the scalable capability to generate IV fluids from indigenous water supplies. It meets USP (U.S. Pharmacopeia) standards. This capability was performed using potable water from the ISS; water from more extreme environments would need preconditioning. The key advantage is the ability to filter mass and volume, providing the equivalent amount of IV fluid: this is critical for remote operations or resource- poor environments. The IVGEN technology purifies drinking water, mixes it with salt, and transfers it to a suitable bag to deliver a sterile normal saline solution. Operational constraints such as mass limitations and lack of refrigeration may limit the type and volume of such fluids that can be carried onboard the spacecraft. In addition, most medical fluids have a shelf life that is shorter than some mission durations. Consequently, the objective of the IVGEN experiment was to develop, design, and validate the necessary methodology to purify spacecraft potable water into a normal saline solution, thus reducing the amount of IV fluids that are included in the launch manifest. As currently conceived, an IVGEN system for a space exploration mission would consist of an accumulator, a purifier, a mixing assembly, a salt bag, and a sterile bag. The accumulator is used to transfer a measured amount of drinking water from the spacecraft to the purifier. The purifier uses filters to separate any air bubbles that may have gotten trapped during the drinking water transfer from flowing through a high-quality deionizing cartridge that removes the impurities in the water before entering the salt bag and mixing with the salt to create a normal saline solution.

McQuillen, John↗
DOE OSTI2021

PREPARATION OF CLAY-COATED GLASS SURFACES FOR MICROFLUIDICS-BASED STUDY ON CLAY-FLUID INTERACTIONS

Unique characteristics of clay, even though make any clay abundant shales a good source of adsorbed gas, make them equally difficult to produce. The clay-water interaction can cause significant swelling and fines migration in the shale formation, both of which can significantly impair the overall hydrocarbon recovery from shale. Geomaterial micromodels, developed by functionalizing traditional glass or PDMS surface with geomaterials (e.g., calcite, quartz, clay) can represent the physico-chemical properties of the natural porous media and have been used during the last few years to understand and evaluate the solid-fluid physicochemical interactions. This study focuses on developing a clay-coated geomaterial surface and investigates the effect of base fluid's salinity on clay adsorption to the glass surface. Glass capillary tubes and straight channel borosilicate glass micromodels are coated with Illite clay minerals to represent the pore-scale clay chemistry of Caney Shale, a Mississippian unconventional play in Southern Oklahoma, USA. 10 wt.% of Illite clay slurries made with brines of four different salinities are used to coat the glass-capillary tubes to understand the effect of salinity in clay adsorption on the glass surface and overall coating quality. To achieve a stable coating and evaluate the impact of heat treatment on coating's stability, straight channel glass flow cells coated with Illite clay are heat-treated at low (25 °C) and high temperature (125 °C). Dynamic flooding tests were carried out with brines on the coated surface to evaluate the stability of the coating. The experiments' outcome indicated a strong relationship between the brine's salinity and the adsorption of clay particles on the glass surface. An increase in brine concentration resulted in improved adsorption of clay particles on the glass surface. Experiments involving heat treating the glass surface following the coating demonstrated significant improvement in the stability of the coating.

02 PETROLEUM↗
NASA NTRS2019

Predictability of Ocean Heat Content From Electrical Conductance

Ocean heat content (OHC) is a key climate variable that needs to be monitored to know how Earth's energy imbalance is changing, yet observing OHC remains a challenge. The present study examines whether a depth integral of the ocean's electrical conductivity (“conductance”), which may be inferred from both in situ methods and satellite magnetometers over the global ocean, could help monitor OHC. The ocean's electrical conductivity locally depends on temperature, salinity, and pressure, but it is not as well known how the conductance depends on OHC and ocean salt content. By examining the output of an ocean state estimate shown to agree well with observations that have not been assimilated, this study evaluates the fundamental limitations of using perfectly known ocean conductance to predict OHC, rather than the challenges associated with accounting for observational error. It is found that the ocean's conductance and OHC fields are nonlinearly related but nevertheless highly correlated. A statistical framework tends to predict OHC more accurately than ocean salt content from ocean conductance in regions where conductivity is more sensitive to salinity than temperature. The annually (bidecadally) averaged OHC can be predicted from a combination of conductance and depth‐averaged conductivity ocean fields to within nearly 0.1% (1%) error globally and even more accurately in many poorly observed (e.g., ice‐covered) regions. Practical application of this statistical framework to monitor OHC requires examination of the effect of uncertainties in the observed bathymetry and ocean conductance, which vary with application.

Trossman, D. S.↗
DOE OSTI2024

Review of solar-enabled desalination and implications for zero-liquid-discharge applications

Abstract The production of freshwater from desalinating abundant saline water on the planet is increasingly considered a climate change adaptation measure. Yet, there are challenges associated with the high cost, intensive energy demand, and environmental implications of desalination. Effective integration of solar energy generation and freshwater production can address both issues. This review article highlights recent key advances in such integration achieved in a joint-research university-national laboratory partnership under the auspices of the United States Department of Energy and parallel efforts worldwide. First, an overview of current and emerging desalination technologies and associated pretreatment, brine treatment, and valorization technologies that together can result in zero-liquid-discharge systems is presented, and their technological readiness levels are evaluated. Then, advanced modeling techniques and new software platforms that enable optimization of solar-desalination applications with the dual objective of cost and environmental impact minimization are discussed.

14 SOLAR ENERGY↗
NASA NTRS1993

Phase aligner for the Electronically Scanned Thinned Array Radiometer (ESTAR) instrument

A prototype Phase Aligner (PA) or the Electronically Scanned Thinned Array Radiometer instrument has been designed and tested. Implemented in a single Xilinx XC3042PC84-125 Field Programmable Gate Array (FPGA), it is a dual-port register file which allows independent storage and phase coherent retrieval of antenna array data by the Central Processing Unit (CPU). It has dimensions of 4 x 20 bits and can be used at clock frequencies as high as 25 MHz. The ESTAR is a passive synthetic-aperture radiometer designed to sense soil moisture and ocean salinity at L-band.

Chren, William A., Jr.↗
NASA NTRS2021

Indicators of Climate Change Impacts on the Water Cycle and Water Management

Managing water is a top social and economic responsibility and is expected to become even more critical as climate change, in addition to other human activities, alters water availability and quality. Robust indicators reflecting the effects of climate change on the U.S. and global water cycles are needed in order to appropriately manage water resources. Here, we describe a suite of seventeen water cycle and management indicators, which are based on synthesis of available datasets. These indicators include: average and heavy precipitation, standardized precipitation index, annual, 7-day low and 3-day high streamflow volume, streamflow timing, snow cover, snow water equivalent, groundwater level, lake water temperature, stream water temperature, dissolved oxygen, salinity, Palmer Drought Severity Index, water withdrawals and water use. We also identify three indicators that could be included in the suite of water cycle and management indicators with some additional, directed work: snowfall, evapotranspiration and soil moisture. Our conceptual framework focuses on known water cycle changes in addition to potential effects on management, and addresses water quantity and quality, as well as water use and related interactions with freshwater ecosystems, societal impacts, and management. Water cycle indicators are organized into three categories: (1) hydrologic processes, (2) water quality processes, and (3) water quality and quantity impacts. Indicators described here are recommended to serve as critical references for periodic climate assessments. As such, these indicators support analyses of the effects of global change on the natural environment, agriculture, energy, and water resources, among other sectors. Additionally, we identify research gaps and needs that can be addressed to advance the development of future indicators.

Christa D Peters-Lidard↗
DOE OSTI2021

Scaling plant responses to high temperature from cell to ecosystem

Plant survival and productivity decrease with exposure to less favourable environments. The negative effects of environmental factors such as water-deficit and salinity stress on vegetation are relatively well studied, primarily due to the large losses in crop yield and forest biomass caused by these stresses. Although the impact of combined heat and drought on plants has received considerable interest in recent years due to climate change, there has been less focus on ascertaining the impact of heat stress alone at a range of temporal and spatial scales. The steady increase in global mean temperatures and (more importantly) variability in extreme temperatures is translating into more frequent and extreme heat stress episodes, which in turn reduce plant productivity. Further, projected increases in both day and night temperatures and the predicted impact of these changes on agricultural and forest productivity have drawn attention to the need to better address the direct effects of heat on plants. In particular, there has been tremendous interest in understanding the short- and long-term effects of heat at the cellular and whole-plant levels, including work on crops of agricultural importance and species from less managed ecosystems. Hence, we made a concerted effort in this Special Issue to capture recent progress in our ability to quantify the impact of heat stress, and identify new tools and approaches that have been developed and implemented to capture a wide range of responses in plants. The series of reviews and research articles presented here captures our current understanding of plant physiological and molecular responses to heat stress, as well as covering phenotyping methods, genetic diversity and potential routes through which plants can acclimate and adapt to warming climates.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Site Selection and Cost Estimation of Pilot-Scale CO2 Saline Storage Study in the Gulf of Mexico

Presentation at NETL Carbon Management Project Review Meeting held in Pittsburgh, Pennsylvania, August 15–19, 2022. The presentation provides a high-level overview of initial conceptual analysis evaluating site selection, geologic assessment, infrastructure, and project cost considerations associated with the development of pilot-scale CO2 storage projects in the offshore Gulf of Mexico.

Wijaya, Nur↗
NASA NTRS2000

Southern Ocean Response to NADW Changes

The possibility of North Atlantic Deep Water (NADW) changes in both past and future climates has raised the issue of how the Southern Ocean would respond. Recent experiments with the GISS coupled atmosphere-ocean model have shown that a "bipolar see-saw" between NADW production and Antarctic Bottom Water (AABW) production in the Weddell Sea can occur in conjunction with freshening of the North Atlantic. However, this effect operates not through a slow ocean response but via a rapid atmospheric mechanism. As NADW reduces, colder temperatures in the North Atlantic, and Northern Hemisphere in general, are associated with higher surface pressure (increased atmospheric mass). Reduced mass in the Southern Hemisphere occurs in response, with lower pressure over the South Pole (an EOF #1 effect, the "high phase" of the Antarctic Oscillation).The lower pressure is associated with stronger west winds that generate an intensified Antarctic Circumpolar Current (ACC), which leads to longitudinal heat divergence in the South Atlantic (and heat convergence in the Southern Indian Ocean). Colder temperatures in the Weddell Sea region lead to sea ice growth, increased salinity and surface water density, and greater Weddell Sea Bottom Water production. Increased poleward transport of heat occurs in the South Atlantic in conjunction with increased bottom water production, but its convergence at high latitudes is not sufficient to offset the longitudinal heat divergence due to the intensified ACC. The colder temperatures at high latitudes in the South Atlantic increase the latitudinal temperature gradient, baroclinic instability, eddy energy and eddy poleward transport of momentum, helping to maintain the lower pressure over the pole in an interactive manner. The heat flux convergence in the Indian Ocean provides a warming tendency in that region, and overall global production of AABW remains unchanged. These results have implications for the interpretation of the ice core records of the last deglaciation, but may also be relevant for changes during the Holocene and perhaps even in response to increased CO2 forcing,

Rind, David↗
DOE OSTI2021

Biomass and salt-dependent effects of Bacillus spores on radionuclide migration from the Waste Isolation Pilot Plant

Spores of a Bacillus sp., isolated from radioactive waste, were tested for their ability to influence the fate and transport of neodymium (Nd3+) under high salt conditions expected at the Waste Isolation Pilot Plant (WIPP) nuclear waste repository. Spores were suspended in neodymium-spiked saline solutions up to 4 M NaCl, and concentrations of Nd and the complexing agent dipicolinic acid (DPA), a component of spores, were monitored along with optical densities and spore numbers. Overall, results support neodymium bioassociation that is dependent upon biomass, with more apparent adsorption occurring at higher spore concentrations. However, probable spore lysis in 2 and 4 M NaCl solutions and possible germination at 0.15 M NaCl appear to drive the release of DPA and subsequent return of Nd to solution. The implications of this work for the WIPP will depend on actual biomass levels and the ionic strength of the repository brines.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1988

Cytoplasmic membrane changes during adaptation of the fresh water cyanobacterium Synechococcus 6311 to salinity

In this investigation, changes were characterized in cell structure and cytoplasmic membrane organization that occur when the freshwater cyanobacterium Synechococcus 6311 is transferred from 'low salt' (0.03 molar NaCl) to 'high salt' (0.5 molar NaCl) media (i.e. sea water concentration). Cells were examined at several time points after the imposition of the salt stress and compared to control cells, in thin sections and freeze fracture electron microscopy, and by flow cytometry. One minute after exposure to high salt, i.e. 'salt shock', virtually all intracellular granules disappeared, the density of the cytoplasm decreased, and the appearance of DNA material was changed. Glycogen and other granules, however, reappeared by 4 hours after salt exposure. The organization of the cytoplasmic membrane undergoes major reorganization following salt shock. Freeze-fracture electron microscopy showed that small intramembrane particles (diameter 7.5 and 8.5 nanometers) are reduced in number by two- to fivefold, whereas large particles, (diameters 14.5 and 17.5 nanometers) increase two- to fourfold in frequency, compared to control cells grown in low salt medium. The changes in particle size distribution suggest synthesis of new membrane proteins, in agreement with the known increases in respiration, cytochrome oxidase, and sodium proton exchange activity of the cytoplasmic membrane.

NASA Discipline Number 61-10↗