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At least 937 records · Page 52

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DOE OSTI2020

Materials Data on Sr3Hg by Materials Project

Sr3Hg is Cementite structured and crystallizes in the orthorhombic Pnma space group. The structure is two-dimensional and consists of two Sr3Hg sheets oriented in the (0, 0, 1) direction. there are two inequivalent Sr sites. In the first Sr site, Sr is bonded in a distorted water-like geometry to two equivalent Hg atoms. There are one shorter (3.37 Å) and one longer (3.41 Å) Sr–Hg bond lengths. In the second Sr site, Sr is bonded in a bent 150 degrees geometry to two equivalent Hg atoms. There are one shorter (3.28 Å) and one longer (3.32 Å) Sr–Hg bond lengths. Hg is bonded in a 6-coordinate geometry to six Sr atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on SmYHg2 by Materials Project

SmYHg2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Sm is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Sm–Hg bond lengths are 3.27 Å. Y is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Y–Hg bond lengths are 3.27 Å. Hg is bonded in a body-centered cubic geometry to four equivalent Sm and four equivalent Y atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on BaSnHg2 by Materials Project

BaHg2Sn crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two BaHg2Sn ribbons oriented in the (1, 0, 0) direction. Ba is bonded in a linear geometry to two equivalent Hg atoms. Both Ba–Hg bond lengths are 3.43 Å. Hg is bonded in a linear geometry to one Ba and one Sn atom. The Hg–Sn bond length is 2.89 Å. Sn is bonded in a linear geometry to two equivalent Hg atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on YbAgHg2 by Materials Project

YbAgHg2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Yb is bonded in a distorted body-centered cubic geometry to six equivalent Ag and eight equivalent Hg atoms. All Yb–Ag bond lengths are 3.56 Å. All Yb–Hg bond lengths are 3.09 Å. Ag is bonded in a 8-coordinate geometry to six equivalent Yb and eight equivalent Hg atoms. All Ag–Hg bond lengths are 3.09 Å. Hg is bonded in a body-centered cubic geometry to four equivalent Yb and four equivalent Ag atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Mg5Hg by Materials Project

Mg5Hg crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded to ten Mg and two equivalent Hg atoms to form distorted MgMg10Hg2 cuboctahedra that share corners with eighteen equivalent MgMg10Hg2 cuboctahedra, edges with four equivalent HgMg12 cuboctahedra, edges with fourteen MgMg10Hg2 cuboctahedra, faces with four equivalent HgMg12 cuboctahedra, and faces with sixteen MgMg10Hg2 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.07–3.18 Å. Both Mg–Hg bond lengths are 3.16 Å. In the second Mg site, Mg is bonded to nine Mg and three equivalent Hg atoms to form distorted MgMg9Hg3 cuboctahedra that share corners with nine equivalent MgMg9Hg3 cuboctahedra, corners with nine equivalent HgMg12 cuboctahedra, edges with eighteen MgMg10Hg2 cuboctahedra, faces with three equivalent HgMg12 cuboctahedra, and faces with seventeen MgMg10Hg2 cuboctahedra. All Mg–Mg bond lengths are 3.12 Å. All Mg–Hg bond lengths are 3.12 Å. Hg is bonded to twelve Mg atoms to form HgMg12 cuboctahedra that share corners with eighteen equivalent MgMg9Hg3 cuboctahedra, edges with six equivalent HgMg12 cuboctahedra, edges with twelve equivalent MgMg10Hg2 cuboctahedra, faces with two equivalent HgMg12 cuboctahedra, and faces with eighteen MgMg10Hg2 cuboctahedra.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on LiHfHg2 by Materials Project

LiHfHg2 crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two LiHfHg2 ribbons oriented in the (1, 0, 0) direction. Li is bonded in a linear geometry to two equivalent Hg atoms. Both Li–Hg bond lengths are 2.74 Å. Hf is bonded in a linear geometry to two equivalent Hg atoms. Both Hf–Hg bond lengths are 2.96 Å. Hg is bonded in a linear geometry to one Li and one Hf atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on ErCdHg2 by Materials Project

ErHg2Cd is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Er is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Er–Hg bond lengths are 3.11 Å. Hg is bonded in a body-centered cubic geometry to four equivalent Er and four equivalent Cd atoms. All Hg–Cd bond lengths are 3.11 Å. Cd is bonded in a distorted body-centered cubic geometry to eight equivalent Hg atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on LiAcHg2 by Materials Project

LiAcHg2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Li is bonded in a distorted body-centered cubic geometry to eight equivalent Hg atoms. All Li–Hg bond lengths are 3.30 Å. Ac is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Ac–Hg bond lengths are 3.30 Å. Hg is bonded in a body-centered cubic geometry to four equivalent Li and four equivalent Ac atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on TlCdHg2 by Materials Project

Hg2CdTl crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two Hg2CdTl ribbons oriented in the (0, 1, 0) direction. Hg is bonded in a linear geometry to one Cd and one Tl atom. The Hg–Cd bond length is 3.11 Å. The Hg–Tl bond length is 3.27 Å. Cd is bonded in a linear geometry to two equivalent Hg atoms. Tl is bonded in a linear geometry to two equivalent Hg atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Branching ratio and γ -ray emission probabilities in the decay of the J π = 13 / 2 + isomer in 197Hg

Gamma rays following the decay of the 197 g Hg and 197 m Hg radionuclides were measured using chemically-purified sources and a planar HPGe detector. In the case of 197 m Hg, precise values of 94.68 (9)% and 5.32 (9)% were confirmed for the IT and EC branches, respectively, the latter discovered to differ significantly from previously published data. The half-lives of 197 g Hg and 197 m Hg were also measured as 64.81 (24) h and 23.82 (4) h.

197𝑔Hg↗

DOE OSTI2020

Analysis of alternative climate datasets and evapotranspiration methods for the Upper Mississippi River Basin using SWAT within HAWQS

This study reports the application of Soil andWater Assessment Tool (SWAT) within the Hydrologic andWater Quality System(HAWQS) on-line platform, for the UpperMississippi River Basin (UMRB). TheUMRB is an important ecosystem located in the north central U.S. that is experiencing a range of ecological stresses. Specifically, testing of SWAT was performed for: (1) Hargreaves (HG) and Penman-Monteith (PM) PET methods, and (2) Livneh, National Climatic Data Center (NCDC) and Parameter-elevation Regressions on Independent Slopes Model (PRISM) climate datasets. The Livneh-PM combination resulted in the highest average annual water yield of 380.6 mm versus the lowest estimated water yield of 193.9 mm for the Livneh-HG combination, in response to 23-year uncalibrated simulations. Higher annual ET and PET values were predicted with HG method versus the PM method for all three weather datasets in response to the uncalibrated simulations, due primarily to higher HG-based estimates during the growing season. Based on these results, it was found that the HG method is the preferred PET option for the UMRB. Initial calibration of SWAT was performed using the Livneh data and HGmethod for threeMississippi Rivermain stem gauge sites, which was followed by spatial validation at 10 other gauge sites located within the UMRB streamnetwork. Overall satisfactory results were found for the calibration and validation gauge sites, with the majority of R2 values ranging between 0.61 and 0.82, Nash- Sutcliffe modeling efficiency (NSE) values ranging between 0.50 and 0.79, and Kling-Gupta efficiency (KGE) values ranging between 0.61 and 0.84. The results of an additional experimental suite of six scenarios,which represented different combinations of climate data sets and calibrated parameters, revealed that suggested statistical criteria were again satisfied by the different scenario combinations. Overall, the PRISM data exhibited the strongest reliability for the UMRB.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2021

Hyperglycemia alters mitochondrial respiration efficiency and mitophagy in human podocytes

Highlights: • Impairment of mitochondrial dynamics underlies the pathogenesis of type 2 diabetes. • Mitochondrial respiration is altered in glomeruli isolated from diabetic STZ-rats. • High glucose induces mitochondrial fission and fragmentation in human podocytes. • Mitochondrial fusion, biogenesis and mitophagy are reduced in HG-treated podocytes. • HG can injure the kidney by alteration of podocytes and glomerular bioenergetics. Podocytes constitute the outer layer of the renal glomerular filtration barrier. Their energy requirements strongly depend on efficient oxidative respiration, which is tightly connected with mitochondrial dynamics. We hypothesized that hyperglycemia modulates energy metabolism in glomeruli and podocytes and contributes to the development of diabetic kidney disease. We found that oxygen consumption rates were severely reduced in glomeruli from diabetic rats and in human podocytes that were cultured in high glucose concentration (30 mM; HG). In these models, all of the mitochondrial respiratory parameters, including basal and maximal respiration, ATP production, and spare respiratory capacity, were significantly decreased. Podocytes that were treated with HG showed a fragmented mitochondrial network, together with a decrease in expression of the mitochondrial fusion markers MFN1, MFN2, and OPA1, and an increase in the activity of the fission marker DRP1. We showed that markers of mitochondrial biogenesis, such as PGC-1α and TFAM, decreased in HG-treated podocytes. Moreover, PINK1/parkin-dependent mitophagy was inhibited in these cells. These results provide evidence that hyperglycemia impairs mitochondrial dynamics and turnover, which may underlie the remarkable deterioration of mitochondrial respiration parameters in glomeruli and podocytes.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2021

Unsaturated Sulfur Crown Ethers Can Extract Mercury(II) and Show Promise for Future Copernicium(II) Studies: A Combined Experimental and Computational Study

The unsaturated hexathia-18-crown-6 (UHT18C6) molecule was investigated for the extraction of Hg(II) in HCl and HNO3 media. This extractant can be directly compared to the recently studied saturated hexathia-18-crown-6 (HT18C6). The default conformation of the S lone pairs in UHT18C6 is endodentate, where the pocket of the charge density, according to the crystal structures, is oriented toward the center of the ring, which should allow better extraction for Hg(II) compared to the exodentate HT18C6. Batch study experiments showed that Hg(II) had better extraction at low acid molarity (ca. 99% in HCl and ca. 95% in HNO 3 ), while almost no extraction was observed above 0.4 M HCl and 4 M HNO 3 (<5%). Speciation studies were conducted with the goal of delineating a plausible extraction mechanism. Density functional theory calculations including relativistic effects were carried out on both Hg(II)-encapsulated HT18C6 and UHT18C6 complexes to shed light on the binding strength and the nature of bonding. Our calculations offer insights into the extraction mechanism. In addition to Hg(II), calculations were performed on the hypothetical divalent Cn(II) ion, and showed that HT18C6 and UHT18C6 could extract Cn(II). Finally, the extraction kinetics were explored to assess whether this crown can extract the short-lived Cn(II) species in a future online experiment.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

DOE OSTI2024

Tree foliage as a net accumulator of highly toxic methylmercury

Tree canopies are known to elevate atmospheric inputs of both mercury (Hg) and methylmercury (MeHg). While foliar uptake of gaseous Hg is well documented, little is known regarding the temporal dynamics and origins of MeHg in tree foliage, which represents typically less than 1% of total Hg in foliage. In this work, we examined the foliar total Hg and MeHg content by following the growth of five individual trees of American Beech (Fagus grandifolia) for one growing season (April–November, 2017) in North Carolina, USA. We show that similar to other studies foliar Hg content increased almost linearly over time, with daily accumulation rates ranging from 0.123 to 0.161 ng/g/day. However, not all trees showed linear increases of foliar MeHg content along the growing season; we found that 2 out of 5 trees showed elevated foliar MeHg content at the initial phase of the growing season but their MeHg content declined through early summer. However, foliar MeHg content among all 5 trees showed eventual increases through the end of the growing season, proving that foliage is a net accumulator of MeHg while foliar gain of biomass did not “dilute” MeHg content.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2023

How does Mercury Methylation Respond to Intensive Forest Management and the Creation of Anoxia in Floodplain Soils

This research endeavor, entitled “How does Mercury Methylation Respond to Intensive Forest Management and the Creation of Anoxia in Floodplain Soils?” represents a collaborative effort undertaken by the University of North Carolina at Greensboro, led by Principal Investigator Dr. James S. Coleman, the United States Forest Service Santee Experimental Forest (SEF) Station Director Dr. Carl C. Trettin as Co-Principal Investigator, and The Chinese University of Hong Kong Dr. Martin Tsz-Ki Tsui and Dr. Alex T. Chow serving as Co-Principal Investigators. The overarching objective of this proposed project was to capture and elucidate the immediate and short-term effects of forest disturbances, namely clear-cutting and thinning, on the biogeochemical cycling of mercury (Hg) within the SEF in Huger, South Carolina. To accomplish this objective, a two-year exploratory study was proposed to conduct soil sampling and measurements of Hg and toxic methylmercury (MeHg), and soil physiochemical data within the experimental watershed (WS77) at SEF, following the clear-cutting process initiated for the preparation of the native longleaf pine restoration project by the USFS. Based on our mercury and hydrological data assessment, we concluded that the implementation of forest management practices, particularly mechanical thinning and clear-cutting, appears to enhance the potential for Hg methylation. Furthermore, these forest management practices may disrupt and alter the storage, mobility, and transformations of atmospherically deposited Hg in these lowland forests. We advocate for further research to comprehensively evaluate the impact of forest management on Hg cycling within forest ecosystems.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2024

Mercury trophic transfer in Bear Creek

Mercury (especially when transformed by environmental microbes into methylmercury [MeHg]) is one of the only metals known to biomagnify in aquatic food webs, leading to elevated concentrations of this toxicant in fish. However, because Hg is predominantly accumulated in fish via dietary rather than aqueous exposure, the link between aqueous Hg concentrations and concentrations in fish is not always straightforward. This is particularly confounding for remediation efforts at contaminated sites because although reducing aqueous Hg concentrations may be achievable, concentrations in fish may not respond to these reductions in aqueous concentrations if a sufficient amount of Hg remains within the food web or if conditions favor Hg methylation in the environment.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2024

Mercury Trophic Transfer in Bear Creek

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2022

Genome-Wide Association Study Reveals Complex Genetic Architecture of Cadmium and Mercury Accumulation and Tolerance Traits in Medicago truncatula

Heavy metals are an increasing problem due to contamination from human sources that and can enter the food chain by being taken up by plants. Understanding the genetic basis of accumulation and tolerance in plants is important for reducing the uptake of toxic metals in crops and crop relatives, as well as for removing heavy metals from soils by means of phytoremediation. Following exposure of Medicago truncatula seedlings to cadmium (Cd) and mercury (Hg), we conducted a genome-wide association study using relative root growth (RRG) and leaf accumulation measurements. Cd and Hg accumulation and RRG had heritability ranging 0.44 – 0.72 indicating high genetic diversity for these traits. The Cd and Hg trait associations were broadly distributed throughout the genome, indicated the traits are polygenic and involve several quantitative loci. For all traits, candidate genes included several membrane associated ATP-binding cassette transporters, P-type ATPase transporters, oxidative stress response genes, and stress related UDP-glycosyltransferases. The P-type ATPase transporters and ATP-binding cassette protein-families have roles in vacuole transport of heavy metals, and our findings support their wide use in physiological plant responses to heavy metals and abiotic stresses. We also found associations between Cd RRG with the genes CAX3 and PDR3, two linked adjacent genes, and leaf accumulation of Hg associated with the genes NRAMP6 and CAX9. When plant genotypes with the most extreme phenotypes were compared, we found significant divergence in genomic regions using population genomics methods that contained metal transport and stress response gene ontologies. Several of these genomic regions show high linkage disequilibrium (LD) among candidate genes suggesting they have evolved together. Minor allele frequency (MAF) and effect size of the most significant SNPs was negatively correlated with large effect alleles being most rare. This is consistent with purifying selection against alleles that increase toxicity and abiotic stress. Conversely, the alleles with large affect that had higher frequencies that were associated with the exclusion of Cd and Hg. Overall, macroevolutionary conservation of heavy metal and stress response genes is important for improvement of forage crops by harnessing wild genetic variants in gene banks such as the Medicago HapMap collection.

59 BASIC BIOLOGICAL SCIENCES↗