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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 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Development of the Electromagnetic Boom and MOP System (EMOP)

Several large-scale oil spills typically occur in the USA and other places around the world. Such events threaten the Great Lakes as well. The cleanup process is not necessarily efficient or environmentally safe. In addition, the remediation and recovery process is time consuming, expensive and can lead to harmful environmental effects. An innovative electromagnetic approach by Natural Science, LLC uses materials that are reusable, recoverable, and environmentally safe. When micron-sized magnetite (Fe3O4) particles are dispersed in oil on water, the particles form a unique and preferential bond with the oil due to a combination of forces, e.g. Van der Waals. Magnetic fields can then be used to manipulate, trap and remove the oil in an environmentally safe manner with high efficiency. In the case of oil spills on water, the water becomes the primary transport medium for manipulating the oil. Videos demonstrating the process will be shown. Both the particles and the oil are recaptured and separated for reuse. This process is being applied to electromagnetic systems that can replace and/or increase the efficiency of the passive boom and skimmer systems used today.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

An alphavirus temperature-sensitive capsid mutant reveals stages of nucleocapsid assembly

Alphaviruses have a nucleocapsid core composed of the RNA genome surrounded by an icosahedral lattice of capsid protein. An insertion after position 186 in the capsid protein produced a strongly temperature-sensitive growth phenotype. Even when the structural proteins were synthesized at the permissive temperature (28 °C), subsequent incubation of the cells at the non-permissive temperature (37 °C) dramatically decreased mutant capsid protein stability and particle assembly. Electron microscopy confirmed the presence of cytoplasmic nucleocapsids in mutant-infected cells cultured at the permissive temperature, but these nucleocapsids were not stable to sucrose gradient separation. In contrast, nucleocapsids isolated from mutant virus particles had similar stability to that of wildtype virus. Our data support a model in which cytoplasmic nucleocapsids go through a maturation step during packaging into virus particles. The insertion site lies in the interface between capsid proteins in the assembled nucleocapsid, suggesting the region where such a stabilizing transition occurs. - Highlights: • We characterize an alphavirus capsid insertion mutation. • These capsid mutants are highly temperature sensitive for growth. • The insertion affects nucleocapsid stability. • Results suggest that the nucleocapsid is stabilized during virus budding.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Coarse-grained discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers [Discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers]

Vortex chambers allow the generation of rotating fluidized beds, offering high-G intensified gas-solid contact, gas-solids separation and solids-solids segregation. Focusing on binary particle mixtures and fixing the density and diameter of the heavy/large particles, transient batch CFD-coarse-grained DPM simulations were carried out with varying densities or sizes of the light/small particles to evaluate to what extent combining these three functionalities is possible within a vortex chamber of given design. Both the rate and quality of segregation were analyzed. Within a relatively wide density and size range, fast and efficient segregation takes place, with an inner and slower rotating bed of the lighter/small particles forming within the outer and faster rotating bed of the heavier/large particles. Simulations show that the contamination of the outer bed with lighter particles occurs more easily than contamination of the inner bed with heavier particles and increases with decreasing difference in size or density of the particles. Bubbling in the inner bed is observed with an inner bed of very low density or small particles. Porosity plots show that vortex chambers with a sufficient number of gas inlet slots have to be used to guarantee a uniform gas distribution and particle bed. Lastly, the flexibility of particle segregation in vortex chambers with respect to the gas flow rate is demonstrated.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1983

The structure of particle-laden jets and nonevaporating sprays

Mean and fluctuating gas velocities, liquid mass fluxes and drop sizes were in nonevaporating sprays. These results, as well as existing measurements in solid particle-laden jets, were used to evaluate models of these processes. The following models were considered: (1) a locally homogeneous flow (LHF) model, where slip between the phases was neglected; (2) a deterministic separated flow (DSF) model, where slip was considered but effects of particle dispersion by turbulence were ignored; and (3) a stochastic separated flow (SSF) model, where effects of interphase slip and turbulent dispersion were considered using random-walk computations for particle motion. The LHF and DSF models did not provide very satisfactory predictions over the present data base. In contrast, the SSF model performed reasonably well - including conditions in nonevaporating sprays where enhanced dispersion of particles by turbulence caused the spray to spread more rapidly than single-phase jets for comparable conditions. While these results are encouraging, uncertainties in initial conditions limit the reliability of the evaluation. Current work is seeking to eliminate this deficiency.

Shuen, J. S.↗
DOE OSTI2021

Selecting XFEL single-particle snapshots by geometric machine learning

A promising new route for structural biology is single-particle imaging with an X-ray Free-Electron Laser (XFEL). This method has the advantage that the samples do not require crystallization and can be examined at room temperature. However, high-resolution structures can only be obtained from a sufficiently large number of diffraction patterns of individual molecules, so-called single particles. Here, we present a method that allows for efficient identification of single particles in very large XFEL datasets, operates at low signal levels, and is tolerant to background. This method uses supervised Geometric Machine Learning (GML) to extract low-dimensional feature vectors from a training dataset, fuse test datasets into the feature space of training datasets, and separate the data into binary distributions of “single particles” and “non-single particles.” As a proof of principle, we tested simulated and experimental datasets of the Coliphage PR772 virus. We created a training dataset and classified three types of test datasets: First, a noise-free simulated test dataset, which gave near perfect separation. Second, simulated test datasets that were modified to reflect different levels of photon counts and background noise. These modified datasets were used to quantify the predictive limits of our approach. Third, an experimental dataset collected at the Stanford Linear Accelerator Center. The single-particle identification for this experimental dataset was compared with previously published results and it was found that GML covers a wide photon-count range, outperforming other single-particle identification methods. Moreover, a major advantage of GML is its ability to retrieve single particles in the presence of structural variability.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

Mechanochemical synthesis of tungsten carbide nano particles by using WO{sub 3}/Zn/C powder mixture

Graphical abstract: Display Omitted Highlights: ► Nano particles of WC are synthesized by mechanochemical process. ► Zn was used to reduce WO{sub 3}. ► By removing ZnO from the milling products with an acid leaching, WC will be the final products. ► XRD results showed that the reduction reactions were completed after 36 h. ► TEM and SEM images showed that the morphology of produced powder is nearly spherical like. -- Abstract: In this research we introduce a new, facile, and economical system for fabrication of tungsten carbide (WC) nano particle powder. In this system WO{sub 3}, Zn, and C have been ball-milled for several hours, which led to the synthesis of tungsten carbide nano particles. The synthesized WC can successfully be separated from the ball-milled product by subjecting the product powder to diluted HCl for removing ZnO and obtaining WC. X-ray diffraction (XRD) analysis indicates that the reduction of WO{sub 3} will be completed gradually by increasing milling time up to 36 h. Scanning electron microscope (SEM), and transmission electron microscope (TEM) images show that after 36 h of milling the particle size of the fabricated powder is nano metric (about 20 nm). Results have shown that this system can surmount some main problems occurred in previous similar WC synthesizing systems. For example carbothermic reduction reactions, which lead to the synthesis of W{sub 2}C instead of WC, would not be activated because in this system reactions take place gradually.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Relativistic electron scattering by magnetosonic waves: Effects of discrete wave emission and high wave amplitudes

In this paper, we study relativistic electron scattering by fast magnetosonic waves. We compare results of test particle simulations and the quasi-linear theory for different spectra of waves to investigate how a fine structure of the wave emission can influence electron resonant scattering. We show that for a realistically wide distribution of wave normal angles θ (i.e., when the dispersion δθ≥0.5{sup °}), relativistic electron scattering is similar for a wide wave spectrum and for a spectrum consisting in well-separated ion cyclotron harmonics. Comparisons of test particle simulations with quasi-linear theory show that for δθ>0.5{sup °}, the quasi-linear approximation describes resonant scattering correctly for a large enough plasma frequency. For a very narrow θ distribution (when δθ∼0.05{sup °}), however, the effect of a fine structure in the wave spectrum becomes important. In this case, quasi-linear theory clearly fails in describing accurately electron scattering by fast magnetosonic waves. We also study the effect of high wave amplitudes on relativistic electron scattering. For typical conditions in the earth's radiation belts, the quasi-linear approximation cannot accurately describe electron scattering for waves with averaged amplitudes >300 pT. We discuss various applications of the obtained results for modeling electron dynamics in the radiation belts and in the Earth's magnetotail.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Safety shutdown separators

The present invention pertains to electrochemical cells which comprise (a) an anode; (b) a cathode; (c) a solid porous separator, such as a polyolefin, xerogel, or inorganic oxide separator; and (d) a nonaqueous electrolyte, wherein the separator comprises a porous membrane having a microporous coating comprising polymer particles which have not coalesced to form a continuous film. This microporous coating on the separator acts as a safety shutdown layer that rapidly increases the internal resistivity and shuts the cell down upon heating to an elevated temperature, such as 110.degree. C. Also provided are methods for increasing the safety of an electrochemical cell by utilizing such separators with a safety shutdown layer.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2021

Standing Shock Regulates Sparks in Explosive Flows

Electric sparks and explosive flows have long been associated with each other. Flowing dust particles originate charge through contact electrification and separate based on inertia, resulting in strong electric fields supporting sparks. These sparks can cause explosions in dusty environments, especially those rich in carbon, such as coal mines and grain elevators. Recent observations of explosive events in nature and decompression experiments indicate that supersonic flows of explosions may alter the electrical discharge process. Shocks may suppress parts of the hierarchy of the discharge phenomena, such as leaders. In our decompression experiments, a shock tube ejects a flow of gas and particles into an expansion chamber. We imaged an illuminated plume from the decompression of a mixture of argon and < 100 mg of diamond particles. We also performed hydrodynamics simulations of the decompression event that provide insight into the conditions supporting the observed behavior. The sparks occur below the sharp boundary of a condensation cloud. These results agree closely with the Mach disk shock shape and height in the simulation. This represents direct evidence that the sparks are sculpted by the outflow. The spatial and temporal scale of the sparks transmit an impression of the shock tube flow, a connection that could enable novel instrumentation to diagnose currently inaccessible supersonic granular phenomena.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Statistical dynamics of classical systems: A self-consistent field approach

We develop a self-consistent field theory for particle dynamics by extremizing the functional integral representation of a microscopic Langevin equation with respect to the collective fields. Although our approach is general, here we formulate it in the context of polymer dynamics to highlight satisfying formal analogies with equilibrium self-consistent field theory. An exact treatment of the dynamics of a single chain in a mean force field emerges naturally via a functional Smoluchowski equation, while the time-dependent monomer density and mean force field are determined self-consistently. As a simple initial demonstration of the theory, leaving an application to polymer dynamics for future work, we examine the dynamics of trapped interacting Brownian particles. For binary particle mixtures, we observe the kinetics of phase separation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Drift and separation in collisionality gradients

Here we identify a single-particle drift resulting from collisional interactions with a background species, in the presence of a collisionality gradient and background net flow. We also analyze this drift in different limits, showing how it reduces to the well known impurity pinch for high-Zi impurities. We find that in the low-temperature, singly ionized limit, the magnitude of the drift becomes mass-dependent and energy-dependent. Furthermore, by solving for the resulting diffusion-advection motion, we propose a mass-separation scheme that takes advantage of this drift, and analyze the separative capability as a function of collisionally dissipated energy.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2016

T-1075: Large Area Fast Timing Beam Time of Flight (LAFTBToF) for ProtoDUNE

Large-area Picosecond Photodetectors (LAPPDs), developed at Argonne National Laboratory (ANL), present an opportunity to provide identification of charged particles in the 2-10 GeV/c range. Traditional methods using ionization or Cherenkov detectors require large amounts of material or pathlength for the particle to traverse in order to get a clean measurement, and are ill suited for particle beam identification in fixed-target experiments. The 6x6 cm 2 LAPPD uses mm-thick borosilicate glass micro-channel plates with a resistive surface coating added via atomic layer deposition. An electrical connection schematic of the LAPPD is shown in Figure 1. Electrons emitted by the photocathode are accelerated through the MCPs, which have µm-sized capillaries, and an avalanche of electrons is created as the electrons collide against the walls of the capillaries of the MCPs. The resulting electron avalanche is collected on anode strip lines and the signal may be read out on both ends of the stipline. The resistive coating of the thin MCPs and the short path length of the electrons to the readout results in fast rise times, gains of greater than 10 6 and typical timing resolutions of 50 ps. Differential timing on the ends of the strip lines can provide mm-level position measurements. The material of the bare LAPPD presents less than 0.05 of an interaction length and approximately 0.12 of a radiation length for a charged particle of I GeV/c. In our application, two large-area photodetectors separated by 5-10 meters can be used in a time-of-flight (ToF) measurement for 3σ separation of2-7 GeV/c charged pions, kaons and protons with minimal impact on the particle's trajectory and momentum.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

The Fifth International Workshop on Ice Nucleation phase 2 (FIN-02): laboratory intercomparison of ice nucleation measurements

Abstract. The second phase of the Fifth International Ice Nucleation Workshop (FIN-02)involved the gathering of a large number of researchers at the KarlsruheInstitute of Technology's Aerosol Interactions and Dynamics of the Atmosphere(AIDA) facility to promote characterization and understanding of icenucleation measurements made by a variety of methods used worldwide.Compared to the previous workshop in 2007, participation was doubled,reflecting a vibrant research area. Experimental methods involved sampling ofaerosol particles by direct processing ice nucleation measuring systems fromthe same volume of air in separate experiments using different ice nucleatingparticle (INP) types, and collections of aerosol particle samples ontofilters or into liquid for sharing amongst measurement techniques thatpost-process these samples. In this manner, any errors introduced bydifferences in generation methods when samples are shared across laboratorieswere mitigated. Furthermore, as much as possible, aerosol particle sizedistribution was controlled so that the size limitations of different methodswere minimized. The results presented here use data from the workshop toassess the comparability of immersion freezing measurement methods activatingINPs in bulk suspensions, methods that activate INPs in condensation and/orimmersion freezing modes as single particles on a substrate, continuous flowdiffusion chambers (CFDCs) directly sampling and processing particles wellabove water saturation to maximize immersion and subsequent freezing ofaerosol particles, and expansion cloud chamber simulations in which liquidcloud droplets were first activated on aerosol particles prior to freezing.The AIDA expansion chamber measurements are expected to be the closestrepresentation to INP activation in atmospheric cloud parcels in thesecomparisons, due to exposing particles freely to adiabatic cooling. The different particle types used as INPs included the minerals illite NX andpotassium feldspar (K-feldspar), two natural soil dusts representative of arable sandy loam(Argentina) and highly erodible sandy dryland (Tunisia) soils, respectively,and a bacterial INP (Snomax ® ). Consideredtogether, the agreement among post-processed immersion freezing measurementsof the numbers and fractions of particles active at different temperaturesfollowing bulk collection of particles into liquid was excellent, withpossible temperature uncertainties inferred to be a key factor in determiningINP uncertainties. Collection onto filters for rinsing versus directly intoliquid in impingers made little difference. For methods that activatedcollected single particles on a substrate at a controlled humidity at orabove water saturation, agreement with immersion freezing methods was good inmost cases, but was biased low in a few others for reasons that have not beenresolved, but could relate to water vapor competition effects. AmongstCFDC-style instruments, various factors requiring (variable) highersupersaturations to achieve equivalent immersion freezing activation dominatethe uncertainty between these measurements, and for comparison with bulkimmersion freezing methods. When operated above water saturation to includeassessment of immersion freezing, CFDC measurements often measured at orabove the upper bound of immersion freezing device measurements, but oftenunderestimated INP concentration in comparison to an immersion freezingmethod that first activates all particles into liquid droplets prior tocooling (the PIMCA-PINC device, or Portable Immersion Mode Cooling chAmber–Portable Ice Nucleation Chamber), and typically slightly underestimated INPnumber concentrations in comparison to cloud parcel expansions in the AIDAchamber; this can be largely mitigated when it is possible to raise therelative humidity to sufficiently high values in the CFDCs, although this isnot always possible operationally. Correspondence of measurements of INPs among direct sampling andpost-processing systems varied depending on the INP type. Agreement was bestfor Snomax ® particles in the temperature regimecolder than −10 ∘ C, where their ice nucleation activity is nearlymaximized and changes very little with temperature. At temperatures warmer than −10 ∘ C, Snomax ® INP measurements (allvia freezing of suspensions) demonstrated discrepancies consistent withprevious reports of the instability of its protein aggregates that appear tomake it less suitable as a calibration INP at these temperatures. ForArgentinian soil dust particles, there was excellent agreement across allmeasurement methods; measures ranged within 1 order of magnitude for INPnumber concentrations, active fractions and calculated active site densitiesover a 25 to 30 ∘ C range and 5 to 8 orders of correspondingmagnitude change in number concentrations. This was also the case for alltemperatures warmer than −25 ∘ C in Tunisian dust experiments. Incontrast, discrepancies in measurements of INP concentrations or active sitedensities that exceeded 2 orders of magnitude across a broad range of temperaturemeasurements found at temperatures warmer than −25 ∘ C in a previous study werereplicated for illite NX. Discrepancies also exceeded 2 orders of magnitude attemperatures of −20 to −25 ∘ C for potassium feldspar (K-feldspar), but these coincidedwith the range of temperatures at which INP concentrations increase rapidly atapproximately an order of magnitude per 2 ∘ C cooling forK-feldspar. These few discrepancies did not outweigh the overall positive outcomes of theworkshop activity, nor the future utility of this data set or future similarefforts for resolving remaining measurement issues. Measurements of the samematerials were repeatable over the time of the workshop and demonstratedstrong consistency with prior studies, as reflected by agreement of databroadly with parameterizations of different specific or general (e.g., soildust) aerosol types. The divergent measurements of the INP activity of illiteNX by direct versus post-processing methods were not repeated for otherparticle types, and the Snomax ® datademonstrated that, at least for a biological INP type, there is no expectedmeasurement bias between bulk collection and direct immediately processedfreezing methods to as warm as −10 ∘ C. Since particle size rangeswere limited for this workshop, it can be expected that for atmosphericpopulations of INPs, measurement discrepancies will appear due to thedifferent capabilities of methods for sampling the full aerosol sizedistribution, or due to limitations on achieving sufficient watersupersaturations to fully capture immersion freezing in direct processinginstruments. Overall, this workshop presents an improved picture of presentcapabilities for measuring INPs than in past workshops, and providesdirection toward addressing remaining measurement issues.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1986

Sediment-transport (wind) experiments in zero-gravity

The carousel wind tunnel (CWT) can be a significant tool for the determination of the nature and magnitude of interparticlar forces at threshold of motion. By altering particle and drum surface electrical properties and/or by applying electric potential difference across the inner and outer drums, it should be possible to separate electrostatic effects from other forces of cohesion. Besides particle trajectory and bedform analyses, suggestions for research include particle aggregation in zero and subgravity environments, effect of suspension-saltation ratio on soil abrasion, and the effects of shear and shearfree turbulence on particle aggregation as applied to evolution of solar nebula.

Iverson, J.↗
NASA NTRS2012

Comprehensive T-matrix Reference Database: A 2009-2011 Update

The T-matrix method is one of the most versatile and efficient theoretical techniques widely used for the computation of electromagnetic scattering by single and composite particles, discrete random media, and particles in the vicinity of an interface separating two half-spaces with different refractive indices. This paper presents an update to the comprehensive database of peer-reviewed T-matrix publications compiled by us previously and includes the publications that appeared since 2009. It also lists several earlier publications not included in the original database.

electromagnetic scattering↗
NASA NTRS1992

Energetic and magnetosheath energy particle signatures of the low-latitude boundary layer at low altitudes near noon

The low-latitude boundary layer (LBL) and its separation from the cusp have previously been identified using observations of particle precipitation at magnetosheath energies. Using S3-3 satellite observations, we have determined that these identifications can also be made from energetic particle observations on polar-orbiting satellites. It is found that the equatorward boundary of the LBL is identifiable as an approximately discontinuous decrease in 33-keV electron fluxes from low to high latitudes. Both the energetic ion and electron fluxes decrease discontinuously at the boundary between the LBL and the cusp or polar cap. A distinct LBL is nearly always identifiable in energetic particle measurements in the 10-14 MLT region when counting rates are statistically significant. The identifications obtained using the energetic particle measurements have been compared to those obtained using criteria developed by Newell and Meng (1988, 1989) for magnetosheath energy particle precipitation. In this way, we have evaluated the accuracy of both techniques and used the energetic particle measurements to supplement the identifications obtained using the Newell and Meng criteria. We propose that the Newell and Meng threshold on ion energy flux can be reduced by a factor of 6. This modification provides identification of the LBL for lower ion intensity levels than has previously been thought possible. Source, acceleration, and scattering processes have also been studied within and in the vicinity of the LBL. Observed trapped pitch angle distributions of energetic electrons imply that the LBL is at least partially on closed field lines. Strong scattering of energetic protons is found within and equatorward of the LBL and thus must occur at least partially along closed field lines. Field-aligned electron acceleration by parallel electric fields can be discerned within and poleward of the LBL, but a more detailed analysis is necessary for a statistical study. Conical ion acceleration was seen relatively frequently within the LBL and about half as often poleward of the LBL. Neither acceleration process could be identified anywhere equatorward of the LBL.

Roeder, J. L.↗
NASA NTRS1983

A theoretical and experimental study of turbulent particle-laden jets

Mean and fluctuating velocities of both phases, particle mass fluxes, particle size distributions in turbulent particle-laden jets were measured. The following models are considered: (1) a locally homogeneous flow (LHF) model, where slip between the phases was neglected; (2) a deterministic separated flow (DSF) model, where slip was considered but effects of particle dispersion by turbulence were ignored; and (3) a stochastic separated flow (SSF) model. The SSF model performed reasonably well with no modifications in the prescriptions for eddy properties from its original calibration. A modified k- model, incorporating direct contributions of interphase transport on turbulence properties (turbulence modulation), was developed within the framework of the SSF model.

Shuen, J. S.↗
DOE OSTI2019

High-precision α -particle energies in the decay of Es, Fm, and Md Isotopes

Energies of α particles in the decay of heavy Es, Fm and Md isotopes were reevaluated by analyzing previously published and unpublished data. The α-particle spectra were measured in 1970s at the Argonne National Laboratory with a magnetic spectrometer and with silicon detectors using very thin, mass-separated sources. The new values for the α-particle energies were determined with respect to the precise values of 6632.51±0.05 keV for the 253 Es α0 group and 6118.10±0.04 keV for the 252 Cf α0 group, as well as those of 7040.0±1.0 keV and 7022.0±0.5 keV for the 252 Fm α0 and 255 Fm α106 groups, respectively, evaluated in the present work. Furthermore, the deduced uncertainties in the α-particle energies were reduced compared to earlier measurements.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗