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All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Investigating Sintering Mechanisms for Additive Manufacturing of Conductive Traces

Additive Manufacturing (AM) processes enable the fabrication of miniaturized and flexible devices on complex geometries. This paper explores a hybrid additive manufacturing technology that integrates micro-extrusion and PICO-jetting methods. Conductive slurries and colloidal inks were optimized for their rheological properties to aid their precise deposition. A variety of conductive materials which include carbon, silver, nano-particle silver and nickel were deposited on both rigid (glass) and flexible (Kapton) substrates. The deposited traces were cured using two sintering mechanisms which include furnace heating and in situ laser irradiation. The effect of curing mechanism on the conductance of deposited traces was evaluated. The results indicated that traces could be cured successfully with the laser curing mechanism. Nickel and silver laser cured traces had lower resistivity than the furnace sintered traces. An increase in the laser power resulted in lower resistivity of the traces. The lowest resistivity was achieved at 40W laser power with a single laser pass. Scanning electron microscopy and energy dispersive spectroscopy were used to characterize the trace morphology and elemental compositions. Higher power laser curing resulted in better bonding of the particles. Laser cured samples had minimal oxidation to the cross-section region of the traces as compared to furnace cured samples. Furthermore, this research lays the foundation for the fabrication of electronic components for a high level of freeform 3D electronics using a hybrid additive manufacturing technology.

42 ENGINEERING↗
DOE OSTI2015

Determination of elements in ayurvedic medicinal plants by AAS

India has a rich country for the uses of Ayurvedic medicinal plants for treatment and also the north- Karnataka boasts an unparallel diversity of medicinal plants. The present study attempts to estimate and compare the level of trace and heavy metals in some selected leaves and root samples of Ayurvedic medicinal plants such as Mg, Al, K, Cr, Mn, Fe, Cu, Zn, and Cd. The samples are collected from different places of North-Karnataka regions and sample solutions prepared as the ratio of 1:25:25+950ml=1000ppm.the trace and heavy elemental concentration was estimated using Atomic Absorption Spectrometric (AAS) Method. The average concentrations of Mg, Mn, Fe and Zn, are ranging from 2ppm to 5250.2ppm and potassium (K) has more concentration as compare to all other. The other elements likes Al, Cr, Cu, and Cd were also estimed and presented in the table. Therefore, these medicinal plants are rich in some essential minerals, especially K, Mg, Mn, Fe and Zn which are essential for human health.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Measurement of Actinides in Molybdenum-99 Solution Analytical Procedure

This document is a companion report to a previous report, PNNL 24519, Measurement of Actinides in Molybdenum-99 Solution, A Brief Review of the Literature, August 2015. In this companion report, we report a fast, accurate, newly developed analytical method for measurement of trace alpha-emitting actinide elements in commercial high-activity molybdenum-99 solution. Molybdenum-99 is widely used to produce 99m Tc for medical imaging. Because it is used as a radiopharmaceutical, its purity must be proven to be extremely high, particularly for the alpha emitting actinides. The sample of 99 Mo solution is measured into a vessel (such as a polyethylene centrifuge tube) and acidified with dilute nitric acid. A gadolinium carrier is added (50 µg). Tracers and spikes are added as necessary. Then the solution is made strongly basic with ammonium hydroxide, which causes the gadolinium carrier to precipitate as hydrous Gd(OH) 3 . The precipitate of Gd(OH) 3 carries all of the actinide elements. The suspension of gadolinium hydroxide is then passed through a membrane filter to make a counting mount suitable for direct alpha spectrometry. The high-activity 99 Mo and 99m Tc pass through the membrane filter and are separated from the alpha emitters. The gadolinium hydroxide, carrying any trace actinide elements that might be present in the sample, forms a thin, uniform cake on the surface of the membrane filter. The filter cake is first washed with dilute ammonium hydroxide to push the last traces of molybdate through, then with water. The filter is then mounted on a stainless steel counting disk. Finally, the alpha emitting actinide elements are measured by alpha spectrometry.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
NASA NTRS1981

Lunar volcanic glasses and their constraints on mare petrogenesis

The compositional properties of volcanic glasses from the Apollo 11, 14, 15 and 16 landing sites are examined and implications of the results for mare basalt petrogenesis and deep lunar structures are discussed. Major-element and nickel analyses were performed on the glasses using electron probe techniques, and R-mode principal component analysis was performed on the 19 different compositions of glass distinguished. The glasses are found to form two distinct chemical arrays based on the major elements and Ni. The presence of two chemically isolated cumulate systems in the mantle at different depths is thus inferred, and a model is developed for mare petrogenesis in which each system was itself composed of two lithologic components that underwent hybridization, assimilation or mixing to generate the large compositional range of magmas represented by the lunar volcanic glasses. The surface-correlated elements associated with the volcanic glasses are attributed to another reservoir in the deep interior which may be responsible for gas emissions causing lunar transient phenomena. The model developed allows predictions to be made concerning the liquidus phase relations, trace and radiogenic element distributions, nonradiogenic isotope compositions and sample ages.

Delano, J. W.↗
NASA NTRS2012

Precision Subsampling System for Mars Surface Missions

The ability to analyze heterogeneous rock samples at fine spatial scales would represent a powerful addition to our planetary in situ analytical toolbox. This is particularly true for Mars, where the signatures of past environments and, potentially, habitability are preserved in chemical and morphological variations across sedimentary layers and among mineral pr.ases in a given rock specimen. On Earth, microbial life often associates with surfaces at the interface of chemical nutrients, and ultimately retains sub-millimeter to millimeter-scale layer confinement in fossilization. On Mars, and possibly other bodies, trace chemical markers (elemental, organic/molecular, isotopic, chiral, etc.) and fine-scale morphological markers (e.g., micro-fossils) may he too subtle, degraded, or ambiguous to be detected, using miniaturized instrumentation, without some concentration or isolation. This is because (i) instrument sensitivity may not be high enough to detect trace markers in bulk averages; and (ii) instrument s~lectiviry may not be sufficient to distinguish such markers from interfering/counteracting signals from the bulk. Moreover from a fundamental chemostratigraphic perspective there would be a great benefit to assessing specific chemical and stable isotopic gradients, over millimeter-to-centimeter scales and beyond, with higher precision than currently possible in situ. We have developed a precision subsampling system (PSS) that addresses this need while remaining relatively flexible to a variety of instruments that may take advantage of the capability on future missions. The PSS is relevant to a number of possible lander/rover missions, especially Mars Sample Return. Our specific PSS prototype is undergoing testing under Mars ambient conditions, on a variety of natural analog rocks and rock drill cores, using a set of complementary flight-compatible measurement techniques. The system is available for testing with other contact instruments that may benefit from precision sampling.

Mahaffy, P. R.↗
NASA NTRS1991

A geometric nonlinear degenerated shell element using a mixed formulation with independently assumed strain fields

A mixed formulation is chosen to overcome deficiencies of the standard displacement-based shell model. Element development is traced from the incremental variational principle on through to the final set of equilibrium equations. Particular attention is paid to developing specific guidelines for selecting the optimal set of strain parameters. A discussion of constraint index concepts and their predictive capability related to locking is included. Performance characteristics of the elements are assessed in a wide variety of linear and nonlinear plate/shell problems. Despite limiting the study to geometric nonlinear analysis, a substantial amount of additional insight concerning the finite element modeling of thin plate/shell structures is provided. For example, in nonlinear analysis, given the same mesh and load step size, mixed elements converge in fewer iterations than equivalent displacement-based models. It is also demonstrated that, in mixed formulations, lower order elements are preferred. Additionally, meshes used to obtain accurate linear solutions do not necessarily converge to the correct nonlinear solution. Finally, a new form of locking was identified associated with employing elements designed for biaxial bending in uniaxial bending applications.

Graf, Wiley E.↗
DOE OSTI2026

Enrichment by the first stars in a relic dwarf galaxy

Stars that contain trace amounts of elements heavier than helium (that is, ‘metallicity’) preserve the chemical fingerprints of the first stars. In the Milky Way, nearly all of the lowest-metallicity stars show an extreme over-abundance of carbon. The origin of this signature has remained a mystery owing to the lack of observational constraints on the environments in which it originates. Here, in this work, we present observations of a star in the >10-billion-year-old ultrafaint dwarf galaxy Pictor II, showing the lowest iron and calcium abundances outside the Milky Way (<1/43,000th solar and ~1/160,000th solar), with >3,000× relative carbon enhancement. The star’s exceptional paucity in iron and calcium make it clearly preserve enrichment from the first stars in a relic dwarf galaxy; Pictor II is one of the smallest, most chemically primordial systems known. This star supports the hypothesis that extreme carbon enhancement results from low-energy supernovae from the first stars, as the yields of energetic supernovae are harder to retain in small-scale environments. This signature of enrichment by the first stars may trace a regime inaccessible to current high-redshift observations, which can hardly detect the initial enrichment of the smallest galaxies.

chemical evolution↗
DOE OSTI2019

Enhancement factor of nuclear reactions in partially ionized plasmas and asymmetric mixtures

When hydrogen is mixed with heavy (high‐ Z ) elements, even as traces, such as iron in the sun, the plasma mixture transits from a weakly coupled state to the intermediate coupling regime of simultaneous weak and strong couplings due to charge asymmetry. In those circumstances, partial ionization is an important aspect to consider. We present a global approach for evaluating enhancement factors for thermonuclear reactions in such mixtures. We grounded our approach on extensive orbital free molecular dynamics (OFMD) simulations of hydrogen‐silver mixtures, chosen as a prototype of hydrogen—high‐ Z mixtures, in a large range of temperature (100 < T < 1600 eV). By comparing a series of OFMD simulations to hyper‐netted chain calculations of effective binary ionic mixtures (eBIM), we set a general procedure for computing enhancement factors. The electron screening contribution is also included implicitly in the definition of the effective ionizations within the average atom framework. The agreement between the pair distribution functions of OFMD and eBIM validates a prescription in which each average atom representing a given species shares the same external electron density with the others (iso‐ n e rule). We checked that an interpolation formula between weak and strong couplings in BIM, due to Chugunov and DeWitt, is accurate enough to address the limit of extreme dilution of a heavy element.

Arnault, Philippe↗
NASA NTRSDate not supplied

In Situ Geochronology for the Next Decade

Geochronology, or determination of absolute ages for geologic events, underpins many inquiries into the formation and evolution of planets and our Solar System. The bombardment chronology inferred from lunar samples has played a significant role in the development of models of early Solar System and extrasolar planet dynamics, as well as the timing of volatile, organic, and siderophile element delivery. Absolute ages of ancient and recent magmatic products provide strong constraints on the dynamics of magma oceans and crustal formation, and the longevity and evolution of interior heat engines and distinct mantle/crustal source regions. Absolute dating also relates habitability markers to the timescale of evolution of life on Earth. The number of geochronologically-significant terrains across the inner Solar System far exceeds our ability to conduct sample return to all of them. Therefore NASA has invested in the development of in situ dating techniques; several such instruments will be TRL 6 by the time of the next Decadal Survey. We formulated a set of medium-class (New Frontiers) mission concepts to three different locations (the Moon, Mars, and Vesta) with a notional payload consisting of the CDEX and KArLE instruments to measure radiometric ages, an imaging spectrometer and optical cameras to provide site geologic context and sample characterization, an ICP-MS to augment sample contextualization, and a sample acquisition and handling system. A Vesta hopper and single-site lunar and Mars landers to advance Solar System chronology fit into the New Frontiers cost cap in our study. Such missions would also enable a broad suite of geologic investigations such as basic geologic characterization, geomorphologic analysis, establishing ground truth for remote sensing analyses, analyses of major, minor, trace, and volatile elements, atmospheric and other long-lived monitoring, organic molecule analyses, and soil and geotechnical properties.

Barbara A Cohen↗
NASA NTRS2014

Phosphates at the Surface of Mars: Primary Deposits and Alteration Products

Phosphorus is an essential element in terrestrial organisms and thus characterizing the occurrences of phosphate phases at the martian surface is crucial in the assessment of habitability. The Alpha Particle X-Ray Spectrometers onboard Spirit, Opportunity and Curiosity discovered a variety of primary and secondary phosphate phases allowing direct comparisons across the three landing sites. The Spirit rover at Gusev Crater encountered the "Wishstone/Watchtower" class of P-rich (up to 5.2 wt% P2O5) rocks interpreted to be alkaline volcanic rocks with a physical admixture of approximately 10 to 20% merrillite [Usui et al 2008]. These rocks are characterized by elevated Ti and Y and anomalously low Cr and Ni, which could largely reflect the nature of the protoliths: Evolved magmatic rocks. Many of these chemical signatures are also found in pyroclastic deposits at nearby "Home Plate" and in phosphate precipitates derived from fluid interactions with these rocks ("Paso Robles" soils). The Opportunity rover at Meridiani Planum recently analyzed approximately 4 cm clast in a fine-grained matrix, one of numerous rocks of similar appearance at the rim of Endeavour Crater. This clast, "Sarcobatus," has minor enrichments in Ca and P relative to the matrix, and like the P-rich rocks at Gusev, Sarcobatus also shows elevated Al and Ti. On the same segment of the Endeavour rim, subsurface samples were found with exceptional levels of Mn (approximately 3.5 wt% MnO). These secondary and likely aqueous deposits contain strong evidence for associated Mg-sulfate and Ca-phosphate phases. Finally, the Curiosity traverse at Gale crater encountered P-rich rocks compositionally comparable to Wishstone at Gusev, including elevated Y. Phosphorous-rich rocks with similar chemical characteristics are prevalent on Mars, and the trace and minor element signatures provide constraints on whether these are primary deposits, secondary products of physical weathering or secondary products of chemical weathering.

Yen, Albert S.↗
DOE OSTI2017

Aqueous Rare Earth Element Patterns and Concentration in Thermal Brines Associated With Oil and Gas Production

This study is part of a joint effort by the University of Wyoming (UW) School of Energy Resources (SER), the UW Engineering Department, Idaho National Laboratories (INL), and the United States Geological Survey (USGS) to describe rare earth element concentrations in oil and gas produced waters and in coal-fired power station ash ponds. In this work we present rare earth element (REE) and trace metal behavior in produced water from four Wyoming oil and gas fields and surface ash pond water from two coal-fired power stations. The concentration of REEs in oil and gas produced waters is largely unknown. For example, of the 150,000 entries in the USGS National Produced Waters Geochemical Database less than 5 include data for REEs. Part of the reason for this scarcity is the analytical challenge of measuring REEs in high salinity, hydrocarbon-bearing waters. The industry standard for water analysis struggles to detect REEs in natural waters under ideal conditions. The detection of REEs in oil and gas field samples becomes all but impossible with the background noise and interferences caused by high concentrations of non-REE ions and residual hydrocarbons. The INL team members have overcome many of these challenges (e.g. McLing, 2014), and continue to develop their methods. Using the methods of the INL team members we measured REEs in high salinity oil and gas produced waters. Our results show that REEs exist as a dissolved species in all waters measured for this project, typically within the parts per trillion range. The samples may be grouped into two broad categories analytically, and these categories match their genesis: Wyoming oil and gas brines contain elevated levels of Europium, and Wyoming industrial pond waters show elevation in heavy REEs (HREEs). While broadly true, important variations exist within both groups. In the same field Europium can vary by more than an order of magnitude, and likewise HREEs in industrial ponds at the same site can vary by more than an order of magnitude. Future work will investigate the reasons for these variations.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2016

A high order characteristic discontinuous Galerkin scheme for advection on unstructured meshes

A new characteristic discontinuous Galerkin (CDG) advection scheme is presented. In contrast to standard discontinuous Galerkin schemes, the test functions themselves follow characteristics in order to ensure conservation and the edges of each element are also traced backwards along characteristics in order to create a swept region , which is integrated in order to determine the mass flux across the edge. Both the accuracy and performance of the scheme are greatly improved by the use of large Courant–Friedrichs–Lewy numbers for a shear flow test case and the scheme is shown to scale sublinearly with the number of tracers being advected, outperforming a standard flux corrected transport scheme for 10 or more tracers with a linear basis. Moreover the CDG scheme may be run to arbitrarily high order spatial accuracy and on unstructured grids, and is shown to give the correct order of error convergence for piecewise linear and quadratic bases on regular quadrilateral and hexahedral planar grids. Using a modal Taylor series basis, the scheme may be made monotone while preserving conservation with the use of a standard slope limiter, although this reduces the formal accuracy of the scheme to first order. The second order scheme is roughly as accurate as the incremental remap scheme with nonlocal gradient reconstruction at half the horizontal resolution. Furthermore, the scheme is being developed for implementation within the Model for Prediction Across Scales (MPAS) Ocean model, an unstructured grid finite volume ocean model.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Noble gas adsorption to tuff

For this report a method was developed to measure trace noble gas element adsorption to the surfaces of geologic materials in the presence of a background gas that could potentially compete for surface adsorption sites. Adsorption of four noble gas elements (Ne, Ar, Kr, and Xe) at a concentration of 100 ppm in helium and nitrogen were measured on a sample of crushed tuff at 0, 15, 30, and 45°C. In addition, Ne, Ar, Kr, and Xe at 250 ppm and 500 ppm in nitrogen at 15°C were measured. Noble gas adsorption was found to increase with increasing atomic mass and decreasing temperature. It was also observed that the relative increase in noble gas element adsorption with decreasing temperature tends to increase with increasing atomic mass. Noble gas adsorption from nitrogen was approximately an order of magnitude greater than for the noble gases in helium. As the noble gas concentrations in nitrogen increased, adsorption increased in a slightly non-linear fashion which could be modeled using a Freundlich isotherm. For noble gas concentrations that were ≤100 ppm Henry's Law constant were calculated.

58 GEOSCIENCES↗
DOE OSTI2016

Effect of nitrogen ion implantation on the structural and optical properties of indium oxide thin films

: We report here synthesis and subsequent nitrogen ion implantation of indium oxide (In{sub 2}O{sub 3}) thin films. The films were implanted with 25 keV N{sup +} beam for different ion doses between 3E15 to 1E16 ions/cm{sup 2}. The resulting changes in structural and optical properties were investigated using XRD, SEM-EDAX and UV-Vis Spectrometry. XRD studies reveal decrease in crystallite size from 20.06 to 12.42 nm with increase in ion dose. SEM micrographs show an increase in the grain size from 0.8 to 1.35 µm with increase in ion dose because of the agglomeration of the grains. Also, from EDAX data on pristine and N-implanted thin films the presence of indium and oxygen without any traces of impurity elements could be seen. However, at lower ion doses such as 3E15 and 5E15 ions/cm{sup 2}, no evidence of the presence of nitrogen ion was seen. However, for the ion dose of 1E16 ions/cm{sup 2}, evidence of presence of nitrogen can be seen in the EDAX data. Band gap calculations reveal a decrease in band gap from 3.54 to 3.38 eV with increasing ion dose. However, the band gap was found to again show an increase to 3.58 eV at the highest ion dose owing to quantum confinement effect.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Synchrotron X-radiolysis of l -cysteine at the sulfur K-edge: Sulfurous products, experimental surprises, and dioxygen as an oxidoreductant

In-situ inventory of sulfurous products from the sulfur K-edge synchrotron X-radiolysis of L-cysteine, in solid-phase and anaerobic (pH 5) and air-saturated (pH 5, pH 7, and pH 9) solutions without and with 40% glycerol is reported. Sequential K-edge X-ray Absorption Spectroscopic (XAS) spectra were acquired. L-cysteine degraded systematically in the X-ray beam. Radiolytic products were inventoried by fits using the XAS spectra of sulfur model compounds. Solid L-cysteine declined to 92% fraction after a single K-edge XAS scan. After six scans 60 % remained, accompanied by 14 % cystine, 16 % thioether, 5.4 % of elemental sulfur, and smaller fractions of more highly oxidized products. In air-saturated pH 5 solution, 73 % of L-cysteine remained after ten scans, with 2 % cystine and 19 % elemental sulfur. Oxidation increased with 40% glycerol, yielding 67 %, 5 % and 23 % fractions, respectively, after ten-scans. Higher pH solutions exhibited less radiolytic chemistry. All the reactivity followed first-order kinetics. The anaerobic experiment displayed two reaction phases, with sharp changes in kinetics and radiolytic chemistry. Unexpectedly, the radiolytic oxidation of L-cysteine was increased in anaerobic solution. After ten-scans only 60% of the L-cysteine remained, along with 17 % cystine, 22 % elemental sulfur, and traces of more highly oxidized products. A new aerobic reaction cycle is hypothesized, wherein dissolved dioxygen captures radiolytic H• or e$-\atop{aq}$, enters HO 2 •/O 2 •-, reductively quenches cysteine thiyl radical, and cycles back to O 2 . This cycle is suggested to suppress the radiolytic production of cystine in aerobic solution.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Fast attenuation of high-frequency acoustic waves in bicontinuous nanoporous gold

We studied the formation and attenuation of GHz elastic waves in free-standing nanoporous gold films by MeV ultrafast electron diffraction and finite element simulations. By tracing the evolution of the high frequency acoustic waves in time domain, we found that the bicontinuous nanoporous structure in nanoporous gold films results in three-dimensionally acoustic response with low coherence, leading to fast attenuation of the elastic waves in comparison with solid gold films. The morphologically dominated dynamics indicates the nanoporosity plays an important role in the high-frequency acoustic energy relaxation, which shines a light on the applications of dealloyed nanoporous materials in nanodevices and sensors as GHz and THz acoustic filters and dampers.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Performance of Low-Complexity Spectrally Selective One-Dimensional Mirrors for Photovoltaic Thermal Management

Operation at elevated temperatures is detrimental to the performance of crystalline Si solar modules. One method of reducing module operating temperature is selective reflection of sub-bandgap photons, which can otherwise only be absorbed parasitically. We numerically optimize the design of a series of multilayer photonic mirrors based on real materials using a previously developed optimization routine. Combined ray tracing and finite element simulations reveal the ability of each mirror to increase energy yield and decrease operating temperature. The best design outperforms a conventional glass antireflection coating, contains only nine layers, and maintains performance regardless of geographic location.

14 SOLAR ENERGY↗
DOE OSTI2018

Two-Layer Anti-Reflection Coatings with Optimized Sub-Bandgap Reflection for Solar Modules

The efficiency of a crystalline silicon solar module decreases as its operating temperature rises. Module cooling is possible via selective reflection of sub-bandgap photons so that they are not parasitically absorbed. Selecting from a library of common dielectrics, we numerically optimize the design of two-layer mirrors at the outer glass surface of a crystalline Si solar cell module. The mirrors are designed to maximize the annual energy yield of a module by both reflecting light below the bandgap and enhancing the transmission of light above the bandgap. Combined ray-tracing and finite element simulations determine the power output and temperature of the module over time. Since any two-layer mirror would replace a conventional single-layer glass anti-reflection coating on the module glass, we study the ability of a two-layer structure to improve on a single-layer coating. The best two-layer designs improve the annual energy yield over a module with a glass anti-reflection coating and reduce the module operating temperature.

14 SOLAR ENERGY↗