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Results for “permeability”

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.

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At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Development of a CNS-permeable reactivator for nerve agent exposure: an iterative, multi-disciplinary approach

Nerve agents have experienced a resurgence in recent times with their use against civilian targets during the attacks in Syria (2012), the poisoning of Sergei and Yulia Skripal in the United Kingdom (2018) and Alexei Navalny in Russia (2020), strongly renewing the importance of antidote development against these lethal substances. The current standard treatment against their effects relies on the use of small molecule-based oximes that can efficiently restore acetylcholinesterase (AChE) activity. Despite their efficacy in reactivating AChE, the action of drugs like 2-pralidoxime (2-PAM) is primarily limited to the peripheral nervous system (PNS) and, thus, provides no significant protection to the central nervous system (CNS). This lack of action in the CNS stems from their ionic nature that, on one end makes them very powerful reactivators and on the other renders them ineffective at crossing the Blood Brain Barrier (BBB) to reach the CNS. In this report, we describe the use of an iterative approach composed of parallel chemical and in silico syntheses, computational modeling, and a battery of detailed in vitro and in vivo assays that resulted in the identification of a promising, novel CNS-permeable oxime reactivator. Additional experiments to determine acute and chronic toxicity are ongoing.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Dynamic permeability in metastable droplet interfacial bilayers

Membrane pores are implicated in several critical functions, including cell fusion and the transport of signaling molecules for intercellular communication. However, these structural features are often difficult to probe directly. Droplet interfacial bilayers offer a synthetic platform to study such membrane properties. We develop a theory that links size-selective transport across a metastable membrane with its transient structural properties. The central quantity of our theory is a dynamic permeability that depends on the mechanism of pore growth, which controls the transient distribution of pore sizes in the membrane. We present a mechanical perspective to derive pore growth dynamics and the resulting size distribution for growth via Ostwald ripening and discuss how these dynamics compare to other growth mechanisms such as coalescence and growth through surfactant desorption. We find scaling relations between the transported particle size, the pore growth rate, and the time for a given fraction of particles to cross the membrane, from which one may deduce the dominant mechanism of pore growth, as well as material properties and structural features of the membrane. Finally, we suggest experiments using droplet interfacial bilayers to validate our theoretical predictions.

Sarma, Nivedina A↗
DOE OSTI2014

Alternating current loss reduction for rectangular busbars by covering their edges with low permeable magnetic caps

A method to reduce ac conductive losses in a thin rectangular busbar made of copper is presented. The method is based on a technique, which makes the distribution of the ac current in the cross section of a busbar flatter. Edges of a thin busbar are covered with low permeability magnetic thin layers as caps. The magnetic cap makes the impedance experienced by the current flowing near the edge comparatively larger so that currents cannot get crowded near the edges of a busbar. This method is numerically verified.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Intrinsic delay of permeable base transistor

Permeable base transistors (PBTs) fabricated by vacuum deposition or solution process have the advantages of easy fabrication and low power operation and are a promising device structure for flexible electronics. Intrinsic delay of PBT, which characterizes the speed of the transistor, is investigated by solving the three-dimensional Poisson equation and drift-diffusion equation self-consistently using finite element method. Decreasing the emitter thickness lowers the intrinsic delay by improving on-current, and a thinner base is also preferred for low intrinsic delay because of fewer carriers in the base region at off-state. The intrinsic delay exponentially decreases as the emitter contact Schottky barrier height decreases, and it linearly depends on the carrier mobility. With an optimized emitter contact barrier height and device geometry, a sub-nano-second intrinsic delay can be achieved with a carrier mobility of ∼10 cm{sup 2}/V/s obtainable in solution processed indium gallium zinc oxide, which indicates the potential of solution processed PBTs for GHz operations.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Microwave and millimeter wave dielectric permittivity and magnetic permeability of epsilon-gallium-iron-oxide nano-powders

In millimeter wave frequency range, hexagonal ferrites with high uniaxial anisotropic magnetic fields are used as absorbers. These ferrites include M-type barium ferrite (BaFe{sub 12}O{sub 19}) and strontium ferrite (SrFe{sub 12}O{sub 19}), which have natural ferromagnetic resonant frequency range from 40 GHz to 60 GHz. However, the higher frequency range lacks suitable materials that support the higher frequency ferromagnetic resonance. A series of gallium-substituted ε-iron oxides (ε-Ga{sub x}Fe{sub 2−x}O{sub 3}) are synthesized, which have ferromagnetic resonant frequencies appearing over the frequency range of 30 GHz to 150 GHz. The ε-Ga{sub x}Fe{sub 2−x}O{sub 3} is synthesized by the sol-gel method. The particle sizes are observed to be smaller than 100 nm. In this paper, in-waveguide transmission and reflection method and the free space magneto-optical approach have been employed to study these newly developed ε-Ga{sub x}Fe{sub 2−x}O{sub 3} particles in millimeter waves. These techniques enable to obtain precise transmission spectra to determine the dielectric and magnetic properties of both isotropic and anisotropic ferrites in the microwave and millimeter wave frequency range from single set of direct measurements. The complex dielectric permittivity and magnetic permeability spectra of ε-Ga{sub x}Fe{sub 2−x}O{sub 3} are shown in this paper. Strong ferromagnetic resonances at different frequencies determined by the x parameter are found.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Measurement of gas-concentration-driven permeation for the examination of permeability, solubility, and diffusivity in varying materials

This manuscript describes the development and operation of an apparatus for the measurement of steady-state and transient gas permeation through different types of solid materials with varying geometries. It is capable of operation from 293 K to 673 K and could theoretically be used with any non-corrosive gas or a mix of gases, although only hydrogen isotopes are used in the current study. A quadrupole mass spectrometer is used to measure permeation fluxes as low as 1011 molecules/s. This unique test setup allows for the simultaneous measurement of diffusivity, solubility, and permeability. Furthermore, varying the pressure in the fore-sample volume allows for tests of Sievert’s law and can give information on surface effects.

Young, Katherine T. (ORCID:0000000285845576)↗
DOE OSTI2016

Permeability and kinetic coefficients for mesoscale BCF surface step dynamics: Discrete two-dimensional deposition-diffusion equation analysis

Here, a discrete version of deposition-diffusion equations appropriate for description of step flow on a vicinal surface is analyzed for a two-dimensional grid of adsorption sites representing the stepped surface and explicitly incorporating kinks along the step edges. Model energetics and kinetics appropriately account for binding of adatoms at steps and kinks, distinct terrace and edge diffusion rates, and possible additional barriers for attachment to steps. Analysis of adatom attachment fluxes as well as limiting values of adatom densities at step edges for nonuniform deposition scenarios allows determination of both permeability and kinetic coefficients. Behavior of these quantities is assessed as a function of key system parameters including kink density, step attachment barriers, and the step edge diffusion rate.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Crystal structure of the mouse innate immunity factor bacterial permeability-increasing family member A1

Bacterial permeability-increasing family member A1 (BPIFA1) is an innate immunity factor and one of the most abundantly secreted proteins in the upper airways. BPIFA1 is multifunctional, with antimicrobial, surfactant and lipopolysaccharide-binding activities, as well as established roles in lung hydration. Here, the 2.5 Å resolution crystal structure of BPIFA1 from Mus musculus (mBPIFA1) is presented and compared with those of human BPIFA1 (hBPIFA1) and structural homologs. Structural distinctions between mBPIFA1 and hBPIFA1 suggest potential differences in biological function, including the regulation of a key pulmonary ion channel.

Little, Michael S.↗
DOE OSTI2019

Enhancing Microbial Sulfate Reduction of Hydrocarbons in Groundwater Using Permeable Filled Borings

At a service station closed in 1993, groundwater contained benzene that persisted above the cleanup goal of 1 mg/L in zones depleted of background sulfate. The benzene and other petroleum hydrocarbons (PHCs) were present as much as 36 feet (11 m) below the water table and therefore remediation of a thick saturated zone interval was required. Microcosms using site sediments demonstrated that anaerobic benzene biodegradation occurred only if sulfate was added, suggesting sulfate addition as a remediation approach. Twenty-four boreholes (9.1" diameter and 56' deep) were drilled around four monitoring wells, in which benzene concentrations exceeded 1 mg/L. The boreholes were backfilled with a mixture of gravel and 15,000 pounds of gypsum (which releases sulfate as it dissolves) to create “Permeable Filled Borings” (PFBs). Concurrently, nine high pressure injections (HPIs) of gypsum slurry were conducted in other site locations (312 pounds of gypsum total). PFBs were expected to release sulfate for up to 20 years, whereas HPIs were expected to produce a short-lived plume of sulfate. Concentrations of benzene and sulfate in groundwater were monitored over a 3-year period in six monitoring wells. In two wells near PFBs, benzene concentrations dropped below the cleanup goal by two to three orders of magnitude; in one well, sulfate concentrations exceeded 500 mg/L for the most recent 18 months. Benzene concentrations in two other PFB monitoring wells declined by a factor of 2 to 4, but remained above 1 mg/L, presumably due to high-dissolved PHC concentrations and possibly greater residual PHC mass in adjacent sediments, and therefore greater sulfate demand. However, hydrogen and sulfur isotopic enrichment in benzene and sulfate, respectively, confirmed biodegradation of benzene and stimulation of sulfate-reducing conditions. Thus, it is hypothesized that the PHC mass in adjacent sediments will decline over time, as will dissolved PHC concentrations, and eventually benzene concentrations will decrease below the cleanup goal. Benzene in two HPI monitoring wells was below the cleanup goal for all but one sampling event before HPIs were conducted and remained below the cleanup goal after HPIs; there was no stimulation of sulfate-reducing conditions. It is concluded that sulfate released from PFBs contributed to declining benzene concentrations.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Permeability of the HIV-1 capsid to metabolites modulates viral DNA synthesis

Reverse transcription, an essential event in the HIV-1 life cycle, requires deoxynucleotide triphosphates (dNTPs) to fuel DNA synthesis, thus requiring penetration of dNTPs into the viral capsid. The central cavity of the capsid protein (CA) hexamer reveals itself as a plausible channel that allows the passage of dNTPs into assembled capsids. Nevertheless, the molecular mechanism of nucleotide import into the capsid remains unknown. Employing all-atom molecular dynamics (MD) simulations, we established that cooperative binding between nucleotides inside a CA hexamer cavity results in energetically favorable conditions for passive translocation of dNTPs into the HIV-1 capsid. Furthermore, binding of the host cell metabolite inositol hexakisphosphate (IP 6 ) enhances dNTP import, while binding of synthesized molecules like benzenehexacarboxylic acid (BHC) inhibits it. The enhancing effect on reverse transcription by IP 6 and the consequences of interactions between CA and nucleotides were corroborated using atomic force microscopy, transmission electron microscopy, and virological assays. Collectively, our results provide an atomistic description of the permeability of the HIV-1 capsid to small molecules and reveal a novel mechanism for the involvement of metabolites in HIV-1 capsid stabilization, nucleotide import, and reverse transcription.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

W3 Is a New Wax Locus That Is Essential for Biosynthesis of β-Diketone, Development of Glaucousness, and Reduction of Cuticle Permeability in Common Wheat

The cuticle plays important roles in plant development, growth and defense against biotic and abiotic attacks. Crystallized epicuticular wax, the outermost layer of cuticle, is visible as white-bluish glaucousness. In crops like barley and wheat, glaucousness is trait of adaption to the dry and hot cultivation conditions, and hentriacontane-14,16-dione (β-diketone) and its hydroxy derivatives are the major and unique components of cuticular wax in the upper parts of adult plants. But their biosynthetic pathway and physiological role largely remain unknown. In the present research, we identified a novel wax mutant in wheat cultivar Bobwhite. The mutation is not allelic to the known wax production gene loci W1 and W2, and designated as W3 accordingly. Genetic analysis localized W3 on chromosome arm 2BS. The w3 mutation reduced 99% of β-diketones, which account for 63.3% of the total wax load of the wild-type. W3 is necessary for β-diketone synthesis, but has a different effect on β-diketone hydroxylation because the hydroxy-β-diketones to β-diketone ratio increased 11-fold in the w3 mutant. Loss of β-diketones caused failure to form glaucousness and significant increase of cuticle permeability in terms of water loss and chlorophyll efflux in the w3 mutant. Transcription of 23 cuticle genes from five functional groups was altered in the w3 mutant, 19 down-regulated and four up-regulated, suggesting a possibility that W3 encodes a transcription regulator coordinating expression of cuticle genes. Biosynthesis of β-diketones in wheat and their implications in glaucousness formation and drought and heat tolerance were discussed.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Associations between regional blood-brain barrier permeability, aging, and Alzheimer’s disease biomarkers in cognitively normal older adults

Background Increased blood-brain barrier permeability (BBBp) has been hypothesized as a feature of aging that may lead to the development of Alzheimer’s disease (AD). We sought to identify the brain regions most vulnerable to greater BBBp during aging and examine their regional relationship with neuroimaging biomarkers of AD. Methods We studied 31 cognitively normal older adults (OA) and 10 young adults (YA) from the Berkeley Aging Cohort Study (BACS). Both OA and YA received dynamic contrast-enhanced MRI (DCE-MRI) to quantify K trans values, as a measure of BBBp, in 37 brain regions across the cortex. The OA also received Pittsburgh compound B (PiB)-PET to create distribution volume ratios (DVR) images and flortaucipir (FTP)- PET to create partial volume corrected standardized uptake volume ratios (SUVR) images. Repeated measures ANOVA assessed the brain regions where OA showed greater BBBp than YA. In OA, K trans values were compared based on sex, Aβ positivity status, and APOE4carrier status within a composite region across the areas susceptible to aging. We used linear models and sparse canonical correlation analysis (SCCA) to examine the relationship between K trans and AD biomarkers. Results OA showed greater BBBp than YA predominately in the temporal lobe, with some involvement of parietal, occipital and frontal lobes. Within an averaged ROI of affected regions, there was no difference in K trans values based on sex or Aβ positivity, but OA who were APOE4carriers had significantly higher K trans values. There was no direct relationship between averaged K trans and global Aβ pathology, but there was a trend for an Ab status by tau interaction on K trans in this region. SCCA showed increased K trans was associated with increased PiB DVR, mainly in temporal and parietal brain regions. There was not a significant relationship between K trans and FTP SUVR. Discussion Our findings indicate that the BBB shows regional vulnerability during normal aging that overlaps considerably with the pattern of AD pathology. Greater BBBp in brain regions affected in aging is related to APOE genotype and may also be related to the pathological accumulation of Aβ.

Science & Technology - Other Topics↗
DOE OSTI2024

Utah FORGE 5-2565: Evolution of Permeability and Strength Recovery of Shear Fractures Under Hydrothermal Conditions - 2024 Annual Workshop Presentation

This is a presentation on the Evolution of Permeability and Strength Recovery of Shear Fractures Under Hydrothermal Conditions by United States Geological Survey, presented by Tamara Jeppson. This video slide presentation, by the USGS, discusses the determination of how thermal, hydrologic, mechanical, and chemical (THMC) processes affect the sustainability of fracture networks in geothermal reservoirs. This includes (1) the qualification of rates of change of fracture properties, (2) the parameterization of modes of reaction, (3) the development of micromechanical and empirical fracture models, and (4) extended THMC models for laboratory- and reservoir-scale models. This presentation was featured in the Utah FORGE R&D Annual Workshop on August 15, 2024.

15 GEOTHERMAL ENERGY↗
DOE OSTI2012

Evaluation of two-phase relative permeability and capillary pressure relations for unstable displacements in a pore network

A series of displacement experiments was conducted using five wetting-nonwetting immiscible fluid pairs in a homogenous and uniform pore network. The micromodel was initially saturated with either polyethylene glycol 200 (PEG) or water as a wetting fluid, which was subsequently displaced by a nonwetting fluid (dodecane, hexadecane, or mineral oil) at different flow rates. The experiments were designed to allow determinations of nonwetting fluid relative permeabilities ( ), fluid saturations ( ), and capillary pressure heads ( ). In the displacements, nonwetting fluid saturations increased with increasing flow rates for all five fluid pairs, and viscous fingering, capillary fingering, and stable displacement were observed. Viscous fingering occurred when PEG was displaced by either dodecane or hexadecane. For the water displacements, capillary fingers were observed at low capillary numbers. Due to unstable fingering phenomena, values for the PEG displacements were smaller than for the water displacements. A fitting exercise using the Brooks-Corey (1964) relationship showed that the fitted entry pressure heads are reasonably close to the computed entry pressure head. The fitted pore geometry factor, S n values for the displacements are considerably lower than what is expected for displacements in homogeneous, highly uniform, porous systems, demonstrating the impact of unstable displacement on the apparent value of S n . It was shown that a continuum-based multiphase model could be used to predict the average behavior for wetting fluid drainage in a pore network as long as independently fitted - and - relations are used. The use of a coupled approach through the Brooks-Corey pore geometry factor underpredicts observed values.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Report on Hydrologic Flow in Low-Permeability Media

We demonstrate that under normal conditions (under which there are no intersections between tunnels/drifts and conductive geological structures, such as faults), the water flow velocity in the damage zone, as a result of non-Darcian flow behavior, is extremely small such that solute transport is dominated by diffusion, rather than advection. We show that unless non-Darcian flow behavior is considered, significant errors can occur in the “measured” relative-permeability values. We propose a hypothesis to consider the temperature impact based on limited test results from the petroleum literature. To consider the bedding effects, we present an empirical relationship between water flux and hydraulic gradient for non-Darcian water flow in anisotropic cases.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗