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All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Mechanical Testing Results on Core from Borehole U-15n, NNSS, in support of SPE

The Nevada National Security Site (NNSS) will serve as the geologic setting for a Source Physics Experiment (SPE) program. The SPE will provide ground truth data to create and improve strong ground motion and seismic S-wave generation and propagation models. The NNSS was chosen as the test bed because it provides a variety of geologic settings ranging from relatively simple to very complex. Each series of SPE testing will comprise the setting and firing of explosive charges (source) placed in a central bore hole at varying depths and recording ground motions in instrumented bore holes located in two rings around the source positioned at different radii. Modeling using advanced simulation codes will be performed both a priori and after each test to predict ground response and to improve models based on acquired field data, respectively. A key component in the predictive capability and ultimate validation of the models is the full understanding of the intervening geology between the source and the instrumented bore holes including the geomechanical behavior of the site rock/structural features. This report presents a limited scope of work for an initial phase of primarily unconfined compression testing. Samples tested came from the U-15n core hole, which was drilled in granitic rock (quartz monzonite). The core hole was drilled at the location of the central SPE borehole, and thus represents material in which the explosive charges will be detonated. The U-15n location is the site of the first SPE, in Area 15 of the NNSS.

58 GEOSCIENCES↗
DOE OSTI2016

STRUCTURAL STUDIES OF EIGHT BRIGHT RIMMED CLOUDS IN THE SOUTHERN HEMISPHERE

We carried out deep- and wide-field near- and mid-infrared observations for a sample of eight bright-rimmed clouds (BRCs). Supplemented with the Spitzer archival data, we have identified and classified 44 to 433 young stellar objects (YSOs) associated with these BRCs. The Class I sources are generally located toward the places with higher extinction and are relatively closer to each other than the Class II sources, confirming that the young protostars are usually found in regions with denser molecular material. On the other hand the comparatively older population, Class II objects, are more randomly found throughout the regions, which can be due to their dynamical evolution. Using the minimal sampling tree analyses, we have extracted 13 stellar cores of eight or more members, which contain 60% of the total YSOs. The typical core is ∼0.6 pc in radii and somewhat elongated (aspect ratio of 1.45), of relatively low stellar density (surface density 60 pc{sup −2}), consisting of a small (35) number of YSOs of relatively young sources (66% Class I), and partially embedded (median A{sub K} = 1.1 mag). But the cores show a wide range in their mass distribution (∼20 to 2400 M {sub ⊙}), with a median value of around 130 M {sub ⊙}. We found the star-formation efficiencies in the cores to be between 3% and 30% with an average of ∼14%, which agrees with the efficiencies needed to link the core mass function to the initial mass function. We also found a linear relation between the density of the clouds and the number of YSOs. The peaked nearest neighbor spacing distributions of the YSOs and the ratio of Jeans lengths to the YSO separations indicates a significant degree of non-thermally driven fragmentation in these BRCs.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1982

Petrology of Apollo 15 station 9A surface and drive tube soils

Modal analysis data are presented for six samples from the upper part of the Apollo 15 lunar core 15010/011 in order to further investigate the maturation profile of the core and to estimate the source rock contribution. The core data are compared with those of the adjacent soils 15531 and 15601. The soils analyzed are relatively immature and remarkably homogeneous. Surface soil 15531 is the most immature one, which is attributed to the fact that it was sampled from the rim of a relatively recent 3 m-diameter crater and thus contains an admixture of fresh bedrock material ejected by this cratering event. The major source of rock contribution to the soils is from petrographically identifiable mare basalts (about 89% to the core and to 15601 and about 87% to 15531). Olivine basalts and quartz normative basalts occur in an approximate ratio of 3:1; contributions of KREEP basalts and the Front are relatively minor.

Griffiths, S. A.↗
NASA NTRS2016

Metabolic Potential and Activity in Fluids of the Coast Range Ophiolite Microbial Observatory, California, USA

Metabolic potential and activity associated with hydrogen and carbon monoxide were characterized in fluids sampled from the the Coast Range Ophiolite Microbial Observatory (CROMO). CROMO consists of two clusters of science-dedicated wells drilled to varying depths up to 35m in the actively serpentinizing, Jurassic-age Coast Range Ophiolite of Northern California, along with a suite of pre-existing monitoring wells at the same site. Consistent with the fluid chemistry observed in other serpentinizing systems, CROMO fluids are highly alkaline, with pH up to 12.5, high in methane, with concentrations up 1600 micromolar, and low in dissolved inorganic carbon (DIC), with concentrations of 10's to 100's of micromolar. CROMO is conspicuous for fluid H2 concentrations that are consistently sub-micromolar, orders of magnitude lower than is typical of other systems. However, higher H2 concentrations (10's -100's of micromolar) at an earlier stage of fluid chemical evolution are predicted by, or consistent with: thermodynamic models for fluid chemistry based on parent rock composition equivalent to local peridotite and with water:rock ratio constrained by observed pH; the presence of magnetite at several wt% in CROMO drill cores; and concentrations of formate and carbon monoxide that would require elevated H2 if formed in equilibrium with H2 and DIC. Calculated Gibbs energy changes for reaction of H2 and CO in each of several metabolisms, across the range of fluid composition encompassed by the CROMO wells, range from bioenergetically feasible (capable of driving ATP synthesis) to thermodynamically unfavorable. Active consumption relative to killed controls was observed for both CO and H2 during incubation of fluids from the pre-existing monitoring wells; in incubations of freshly cored solids, consumption was only observed in one sample set (corresponding to the lowest pH) out of three. The specific metabolisms by which H2 and CO are consumed remain to be determined.

Hydrogen↗
DOE OSTI2019

Investigation of Accessible Pore Structure Evolution under Pressurization and Adsorption for Coal and Shale Using Small-Angle Neutron Scattering

Pore structure is an important parameter to quantify the reservoir rock adsorption capability and diffusivity, both of which are fundamental reservoir properties to evaluate the gas production and carbon sequestration potential for coalbed methane (CBM) and shale gas reservoirs. In this study, we applied small-angle neutron scattering (SANS) to characterize the total and accessible pore structures for two coal and two shale samples. We carried out in situ SANS measurements to probe the accessible pore structure differences under argon, deuterated methane (CD 4 ), and CO 2 penetrations. The results show that the total porosity ranges between 0.25 and 5.8% for the four samples. Less than 50% of the total pores are accessible to CD 4 for the two coals, while more than 75% of the pores were found to be accessible for the two shales. This result suggests that organic matter pores tend to be disconnected compared to mineral matter pores. Argon pressurization can induce pore contraction because of the mechanical compression of the solid skeleton in both the coal and shale samples. Hydrostatic compression has a higher effect on the nanopores of coal and shale with a higher accessible porosity. Both methane and CO 2 injection can reduce the accessible nanopore volume due to a combination of mechanical compression, sorption-induced matrix swelling, and adsorbed molecule occupation. CO 2 has higher effects on sorption-induced matrix swelling and pore filling compared to methane for both the coal and shale samples. Gas densification and pore filling could occur at higher pressures and smaller pore sizes. In conclusion, the compression and adsorption could create nanopores in the San Juan coal and Marcellus shale drilled core but could have an opposite effect in the other samples, namely, the processes could damage the nanopores in the Hazleton coal and Marcellus shale outcrop.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2014

Core-halo age gradients and star formation in the Orion Nebula and NGS 2024 young stellar clusters

We analyze age distributions of two nearby rich stellar clusters, the NGC 2024 (Flame Nebula) and Orion Nebula cluster (ONC) in the Orion molecular cloud complex. Our analysis is based on samples from the MYStIX survey and a new estimator of pre-main sequence (PMS) stellar ages, Age{sub JX} , derived from X-ray and near-infrared photometric data. To overcome the problem of uncertain individual ages and large spreads of age distributions for entire clusters, we compute median ages and their confidence intervals of stellar samples within annular subregions of the clusters. We find core-halo age gradients in both the NGC 2024 cluster and ONC: PMS stars in cluster cores appear younger and thus were formed later than PMS stars in cluster peripheries. These findings are further supported by the spatial gradients in the disk fraction and K-band excess frequency. Our age analysis is based on Age{sub JX} estimates for PMS stars and is independent of any consideration of OB stars. The result has important implications for the formation of young stellar clusters. One basic implication is that clusters form slowly and the apparent age spreads in young stellar clusters, which are often controversial, are (at least in part) real. The result further implies that simple models where clusters form inside-out are incorrect and more complex models are needed. We provide several star formation scenarios that alone or in combination may lead to the observed core-halo age gradients.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

SAIL Storm Boards 2022-2023

“Storm Boards” are simple installations comprised of a horizontal white plastic board that is placed in situ on the surface of the snowpack with a 1 m vertical marker pole for identifying the board center and approximate new snow height. Storm boards allow newly fallen snow to accumulate on them while staying separated from moisture and energy exchange with the snowpack, thus creating a discrete sample of newly fallen snow depth & SWE (snow water equivalent) that can be measured to calculate the net moisture input of individual or multiple storm events to the seasonal snowpack. Samples are measured with a 2” diameter plastic tube that allows the observer to non destructively take a snow core of the newly deposited snow; this core is weighed with a small hand scale - then the mass of the sample is converted to SWE. Depth of the snow sample is obtained with a snow depth probe or from graduated marks on the plastic tube. 3 or more replicate samples are taken for each board measurement and averaged. Total snow height (HS) of the snowpack is measured with a snow depth probe for each site & timepoint to track snowpack accumulation/ablation.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

The reduced genomes of Parcubacteria (OD1) contain signatures of a symbiotic lifestyle

Candidate phylum OD1 bacteria (also referred to as Parcubacteria) have been identified in broad range of anoxic environments through community survey analysis. Although none of these species have been isolated in the laboratory, several genome sequences have been reconstructed from metagenomic sequence data and single-cell sequencing. The organisms have small (generally <1 Mb) genomes with severely reduced metabolic capabilities. We have reconstructed 8 partial to near-complete OD1 genomes from oxic groundwater samples, and compared them against existing genomic data. The conserved core gene set comprises 202 genes, or ~28% of the genomic complement. ‘Housekeeping’ genes and genes for biosynthesis of peptidoglycan and Type IV pilus production are conserved. Gene sets for biosynthesis of cofactors, amino acids, nucleotides and fatty acids are absent entirely or greatly reduced. The only aspects of energy metabolism conserved are the non-oxidative branch of the pentose-phosphate shunt and central glycolysis. These organisms also lack some activities conserved in almost all other known bacterial genomes, including signal recognition particle, pseudouridine synthase A, and FAD synthase. Pan-genome analysis indicates a broad genotypic diversity and perhaps a highly fluid gene complement, indicating historical adaptation to a wide range of growth environments and a high degree of specialization. The genomes were examined for signatures suggesting either a free-living, streamlined lifestyle or a symbiotic lifestyle. The lack of biosynthetic capabilities and DNA repair, along with the presence of potential attachment and adhesion proteins suggest the Parcubacteria are ectosymbionts or parasites of other organisms. The wide diversity of genes that potentially mediate cell-cell contact suggests a broad range of partner/prey organisms across the phylum.

candidate phyla↗
DOE OSTI2019

NGEE Arctic Plant Traits: Soil Cores, Kougarok Road Mile Marker 64, Seward Peninsula, Alaska, 2016

Soil cores were collected from twelve vegetation biomass plots at the Kougarok hillslope in late July of 2016. The sampled plots were located across six ecotypes present at this site (n=2 replicates per ecotype). Soil cores were separated into depth intervals in the field and frozen for transport to Oak Ridge National Laboratory. Laboratory sample processing of these soils generated data on soil texture, pH, gravimetric water content, bulk density, bulk soil %C and %N. Water extracts were performed on subsamples for determination of extractable total nitrogen, inorganic nitrogen, organic nitrogen, phosphorus, and dissolved organic carbon. This dataset contains 1 csv, and 1 pdf.The Next-Generation Ecosystem Experiments: Arctic (NGEE Arctic), was a research effort to reduce uncertainty in Earth System Models by developing a predictive understanding of carbon-rich Arctic ecosystems and feedbacks to climate. NGEE Arctic was supported by the Department of Energy's Office of Biological and Environmental Research.The NGEE Arctic project had two field research sites: 1) located within the Arctic polygonal tundra coastal region on the Barrow Environmental Observatory (BEO) and the North Slope near Utqiagvik (Barrow), Alaska and 2) multiple areas on the discontinuous permafrost region of the Seward Peninsula north of Nome, Alaska.Through observations, experiments, and synthesis with existing datasets, NGEE Arctic provided an enhanced knowledge base for multi-scale modeling and contributed to improved process representation at global pan-Arctic scales within the Department of Energy's Earth system Model (the Energy Exascale Earth System Model, or E3SM), and specifically within the E3SM Land Model component (ELM).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

EXTERNALLY HEATED PROTOSTELLAR CORES IN THE OPHIUCHUS STAR-FORMING REGION

We present APEX 218 GHz observations of molecular emission in a complete sample of embedded protostars in the Ophiuchus star-forming region. To study the physical properties of the cores, we calculate H{sub 2}CO and c -C{sub 3}H{sub 2} rotational temperatures, both of which are good tracers of the kinetic temperature of the molecular gas. We find that the H{sub 2}CO temperatures range between 16 K and 124 K, with the highest H{sub 2}CO temperatures toward the hot corino source IRAS 16293-2422 (69–124 K) and the sources in the ρ Oph A cloud (23–49 K) located close to the luminous Herbig Be star S1, which externally irradiates the ρ Oph A cores. On the other hand, the c -C{sub 3}H{sub 2} rotational temperature is consistently low (7–17 K) in all sources. Our results indicate that the c -C{sub 3}H{sub 2} emission is primarily tracing more shielded parts of the envelope whereas the H{sub 2}CO emission (at the angular scale of the APEX beam; 3600 au in Ophiuchus) mainly traces the outer irradiated envelopes, apart from in IRAS 16293-2422, where the hot corino emission dominates. In some sources, a secondary velocity component is also seen, possibly tracing the molecular outflow.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2017

Externally Heated Protostellar Cores in the Ophiuchus Star-Forming Region

We present APEX 218 GHz observations of molecular emission in a complete sample of embedded protostars in the Ophiuchus star-forming region. To study the physical properties of the cores, we calculate H2CO and c-C3H2 rotational temperatures, both of which are good tracers of the kinetic temperature of the molecular gas. We find that the H2CO temperatures range between 16K and 124K, with the highest H2CO temperatures toward the hot corino source IRAS 16293-2422 (69-124 K) and the sources in the rho Oph A cloud (23-49 K) located close to the luminous Herbig Be star S1, which externally irradiates the rho Oph A cores. On the other hand, the c-C3H2 rotational temperature is consistently low (7-17 K) in all sources. Our results indicate that the c-C3H2 emission is primarily tracing more shielded parts of the envelope whereas the H2CO emission (at the angular scale of the APEX beam; 3600 au in Ophiuchus) mainly traces the outer irradiated envelopes, apart from in IRAS16293-2422, where the hot corino emission dominates. In some sources, a secondary velocity component is also seen, possibly tracing the molecular outflow.

CH3OH↗
NASA NTRS1997

Lithological Variation with Depth and Decoupling of Maturity Parameters in Apollo 16 Regolith Core 68001/2

Using FerroMagnetic Resonance (FMR) and Instrumental Neutron Activation Analysis (INAA), we have determined the maturity (surface exposure) parameter I(sub s)/FeO and concentrations of twenty- five chemical elements on samples taken every half centimeter down the 61-cm length of the 68001/2 regolith core (double drive tube) collected at station 8 on the Apollo 16 mission to the Moon. Contrary to premission expectations, no ejecta or other influence from South Ray crater is evident in the core, although a small inflection in the I(sub s)/FeO profile at 3 cm depth may be related the South Ray crater impact. Regolith maturity generally decreases with depth, as in several previously studied cores. We recognize five compositionally distinct units in the core, which we designate A through E, although all are similar in composition to each other and to other soils from the Cayley plains at the Apollo 16 site. Unit A (0-33 cm) is mature to submature throughout (I(sub s)/FeO: 89-34 units) and is indistinguishable in composition from surface soils collected at station 8. Unit B (33-37 cm) is enriched slightly in a component of anorthositic norite composition. Unit D (42-53 cm) is compositionally equivalent to 80 wt% Unit-A soil plus 20 wt% Apollo-16-type dimict breccia consisting of subequal parts anorthosite and impact-melt breccia. Compared to Unit A, Unit E (53-61 cm) contains a small proportion (up to 4%) of some component compositionally similar to Apollo 14 sample 14321. Unit C (37-42 cm) is unusual. For lithophile and siderophile elements, it is similar to Units A and D. However, I(sub s)/FeO is low throughout the unit (less than 30 units) and in a bluish-gray zone at 41 cm depth I(sub s)/FeO drops to 1.6 units, the lowest value that we have observed in several hundred Apollo 16 soil samples. Samples from the bluish-gray zone also have low Zn concentrations, less than 10 micro g/g, compared to 20-30 micro g/g for the rest of the core. Although both values are consistent with fragmented rock material that has received virtually no surface exposure, the abundance of agglutinates in the bluish-gray soil of Unit C is moderately high, typical of a submature soil that would ordinarily have I(sub s)/FeO - 30. We believe that the anomalously low values of I(sub s)/FeO and Zn concentration result because the soil was heated to -800-1000 'C, probably during an impact. This temperature range is sufficient to volatize the surface-correlated Zn and agglomerate the nanophase metal giving rise to the FMR signal but is not great enough to sinter the soil. Alternatively, the unusual soil interval may represent a disaggregated or incipient regolith breccia, although there is no significant difference in the texture or clast-matrix relationships between Unit C and adjacent units.

Korotev, Randy L.↗
DOE OSTI2021

Meanders as a scaling motif for understanding of floodplain soil microbiome and biogeochemical potential at the watershed scale

Abstract Background Biogeochemical exports from watersheds are modulated by the activity of microorganisms that function over micron scales. Here, we tested the hypothesis that meander-bound regions share a core microbiome and exhibit patterns of metabolic potential that broadly predict biogeochemical processes in floodplain soils along a river corridor. Results We intensively sampled the microbiomes of floodplain soils located in the upper, middle, and lower reaches of the East River, Colorado. Despite the very high microbial diversity and complexity of the soils, we reconstructed 248 quality draft genomes representative of subspecies. Approximately one third of these bacterial subspecies was detected across all three locations at similar abundance levels, and ~ 15% of species were detected in two consecutive years. Within the meander-bound floodplains, we did not detect systematic patterns of gene abundance based on sampling position relative to the river. However, across meanders, we identified a core floodplain microbiome that is enriched in capacities for aerobic respiration, aerobic CO oxidation, and thiosulfate oxidation with the formation of elemental sulfur. Given this, we conducted a transcriptomic analysis of the middle floodplain. In contrast to predictions made based on the prominence of gene inventories, the most highly transcribed genes were relatively rare amoCAB and nxrAB (for nitrification) genes, followed by genes involved in methanol and formate oxidation, and nitrogen and CO 2 fixation. Within all three meanders, low soil organic carbon correlated with high activity of genes involved in methanol, formate, sulfide, hydrogen, and ammonia oxidation, nitrite oxidoreduction, and nitrate and nitrite reduction. Overall, the results emphasize the importance of sulfur, one-carbon and nitrogen compound metabolism in soils of the riparian corridor. Conclusions The disparity between the scale of a microbial cell and the scale of a watershed currently limits the development of genomically informed predictive models describing watershed biogeochemical function. Meander-bound floodplains appear to serve as scaling motifs that predict aggregate capacities for biogeochemical transformations, providing a foundation for incorporating riparian soil microbiomes in watershed models. Widely represented genetic capacities did not predict in situ activity at one time point, but rather they define a reservoir of biogeochemical potential available as conditions change.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Percutaneous Biopsy of Retrobulbar Masses: Anatomical Considerations and MRI Guidance

PurposeObtaining adequate tissue from retrobulbar masses remains a challenge. To this end, a new method of retrobulbar mass biopsy using MRI guidance is presented.Materials and MethodsTwo patients (7- and 71-year-old male) with indeterminate retrobulbar masses underwent bioptic and cytological samplings using MR-compatible 18G and 20–22G needles, and multi-planar MR fluoroscopy. An inferior approach was taken to avoid injury to the optic nerve and ophthalmic arteries.ResultsThe two biopsies were completed without complication. The core biopsy resulted in a final diagnosis, whereas the cytological sampling was non-diagnostic.ConclusionPercutaneous MR-guided retrobulbar mass biopsy proved to be feasible and safe in the two cases described in this report.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS1988

Compositional study of a suite of samples from the 28-t Armanty (Xinjiang) iron meteorite

Neutron activation analysis of 15 samples from widely separated locations on the surface of the 28-t Armanty (Xinjiang) group-IIIE iron meteorite showed no compositional variations attributable to magmatic fractionation processes such as fractional crystallization. The homogeneity contrasts with that observed in the Cape York IIIAB iron, in keeping with the idea that the latter is an exceptional case. From the maximum compositional gradients the radius of the IIIE core is estimated at greater than 1 km. One sample taken from a surface formed by fracture associated with its fall to Earth is slightly anomalous in composition. It is suggested that this region is near the border between two parental gamma crystals and has a high content of minor phases.

Wasson, John T.↗
NASA NTRS2003

Determination of Mercury Content in a Shallow Firn Core from Summit, Greenland by Isotope Dilution Inductively Coupled Plasma Mass Spectrometry

The total mercury Hg content was determined in 6 cm sections of a near-surface 7 m firn core and in surrounding surface snow from Summit, Greenland (elevation: 3238 m, 72.58 N, 38.53 W) in May 2001 by isotope dilution cold-vapor inductively coupled plasma mass spectrometry (ID-CV-ICP-MS). The focus of this research was to evaluate the capability of the ID-CV-ICPMS technique for measuring trace levels of Hg typical of polar snow and firn. Highly enriched Hg-201 isotopic spike is added to approximately 10 ml melted core and thoroughly mixed. The Hg(+2) in the sample is reduced on line with tin (II) chloride (SnCl2) and the elemental Hg (Hg(0)) vapor pre-concentrated on to gold gauze using a commercial amalgam system. The Hg is then thermally desorbed and introduced into a quadrupole ICP-MS. The blank corrected Hg concentrations determined for all samples ranged from 0.25 ng/L to 1.74 ng/L (ppt) (average 0.59 ng/L plus or minus 0.28 ng/L) and fall within the range of those previously determined by Boutron et al., 1998 (less than or equal to 0.05 ng/L to 2.0 ng/L) for the Summit site. The average blank value was 0.19 ng/L plus or minus 0.045 ng/L (n=6). The Hg values specifically for the firn core range from 0.25 ng/L to 0.87 ng/L (average 0.51 ng/L plus or minus 0.13 ng/L) and show both values declining with time and larger variability in concentration in the top 1.8 m.

Mann, Jacqueline L.↗
DOE OSTI2025

Coupled Thermo-Hydrological-Mechanical-Chemical Behavior of Anisotropic Granite for Geologic Disposal of High-Level Radioactive Waste: A Core-Scale Laboratory Investigation

The coupled thermo-hydrological-mechanical-chemical (THMC) behavior of rock within an Excavation Damaged Zone (EDZ) is critical for the safety and long-term performance of a geological repository for high-level radioactive wastes. While many laboratory experiments have been conducted to investigate EDZ rocks, the flow and deformation characteristics resulting from anisotropic rock textures and microcrack distribution under triaxial loading and elevated temperatures remain poorly understood. Particularly, cracks at various scales serve as fast paths for fluid flow and solute transport and present as focal points of mechanical weakness, which complicate the coupled THMC processes in anisotropic EDZ rocks and challenge modeling predictions. Here, in this study, a series of core-scale experiments was conducted on three granite samples under repository-relevant conditions. These rock samples were obtained from the Grimsel Underground Research Laboratory (URL), featured by anisotropic minerals (represented by bedding layers) and microcrack distributions and coarse cm-scale grain sizes. During the experiments, samples were subjected to an elevated temperature at 90 °C and different triaxial loading conditions either by radial (normal to bedding layers) or axial (parallel to bedding layers) compaction. Water was injected into the samples, and the rock permeability evolutions and effluent water chemistry were monitored closely. For intact samples, thermal expansion of minerals at 90 °C resulted in a large, 75% irreversible permeability reduction and rock strengthening under radial compaction, while thermal impact was limited to a 15% permeability reduction under axial compaction. In contrast, for a sample containing open cracks, the growth of fractures during the experiment resulted in an abrupt permeability increase and fast failure at 90 °C. The effluent water chemistry indicates much more considerable mineral dissolution from large shear sliding than that in rocks dominated by mechanical compaction. These results helped better understand the coupled THMC processes in anisotropic rocks containing cracks, evaluate the behaviors of EDZ rocks, and predict the long-term evolution of EDZ for the performance of the repositories.

Coupled THMC processes↗
DOE OSTI2013

High coercivity sized controlled cobalt–gold core–shell nano-crystals prepared by reverse microemulsion

Graphical abstract: - Highlights: • Calculating the crystallinity percentage and percentage of phases presented in Co–Au core–shell nanoparticles. • Magnetic properties of four groups nanogarin: 5, 10, 15, 20 nm. • Single domain ferromagnetic materials with high coercivity at room temperature. • Intrinsic blocking temperature measured in zero field cooled-warmed (ZFC-W). - Abstract: Size-controlled cobalt–gold core–shell nanoparticles were synthesized via the reverse-micelle microemulsion method. In order to control the size of the nanoparticles, the nucleation and growth process were performed within a confined space by adjusting the water to surfactant ratio of reverse micelles solution during synthesis. The crystallinity percentage and percentage of phases presented in Co–Au core–shell nanoparticles were calculated using X-ray diffraction data. The results from transmission electron microscopy provide direct evidence for core–shell structure nanomaterials. Magnetic properties of the samples were investigated using a vibrating sample magnetometer. The as-prepared samples showed significant coercivity at room temperature. The intrinsic blocking temperature was experimentally deduced from zero-field-cooled warmed (ZFC-W) curves by a simple method without employing an external magnetic field. The B-field dependence temperature data of Co–Au nanoparticles exhibited an intrinsic blocking temperature at 45 K. Annealing these samples at 400 °C caused an increase in particle size, crystallinity percentage and further enhanced their magnetic properties.

36 MATERIALS SCIENCE↗