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NASA NTRSDate not supplied

Microstructural Characterization of Felsite Fragments From the Apollo Next Generation Sample Analysis (ANGSA) Double Drive Tube 73001/73002

While the Moon’s surface is dominated by mafic igneous products formed through the crystallization of the lunar magma ocean, and the subsequent eruption of mare basalts – felsic magmatic fragments (variably referred to as felsites, granites, rhyolites or granophyres) have been identified from a number of Apollo samples (e.g. 12013[1], 14321[2], 15405[3] and 73215[4]). Magmatic edifices like the Gruithuisen Domes – silicic constructs sometimes found proximal to the basaltic mare provinces filling nearside basins, may represent a petrogenetic origin. However, this is, is complicated by the fact that they apparently predate mare volcanism (e.g. [5]). Additionally, crater-counting indicates that these silicic surface features also postdate radiogenic ages of Apollo felsites [6]. Various modes of felsic magmatism have been invoked to explain the presence of felsic lithologies on the Moon, including: 1) fractional crystallization and silicate liquid immiscibility; 2) partial melting of lunar crust through basaltic underplating; and 3) fractional crystallization of the mare parent magmas. Although these models are plausible, based on known Apollo samples and lunar meteorites, they are complicated by the lack of sample lithologies with intermediate composition between basaltic magmas and the felsic components, and the fact that partial melting of many crustal rock types on the Moon (e.g., anorthosite, troctolites) are unlikely to form granites. Along with other unique magmatic lithologies, new felsites have been identified within the < 1 mm size fractions of the ANGSA double drive core tube (73001/73002) from Apollo 17 station 3, sampling the light mantle landslide deposit from the South Massif [7]. These additional examples of lunar felsite will help us to better constrain the processes that lead to the formation of these evolved lithologies. To do this, we have employed a gambit of high-resolution scanning electron microscopy (SEM) and scanning transmission electron microscopy (TEM) analytical techniques, including electron backscatter diffraction (EBSD), cathodoluminescence and high-angle annular dark field (HAADF) imaging. These data provide unique insights into the felsite mineralogy and microstructures including the coexistence of quartz and tridymite in many of the fragments. In addition, these analyses provide petrological context and assist targeted in situ secondary ion mass spectrometry (SIMS) measurements of the U-Pb systematics of accessory minerals, and the volatile abundances and D/H ratios of apatite grains identified within the clasts.

lunar↗

NASA NTRSDate not supplied

A Chlorine Isotope Transect Across the Sudbury Impact Deposits Reveals Enigmatic Isotopic Fractionation

Volatile elements play an important role in a variety of cosmochemical and geochemical processes. As such, there has been significant interest in their abundance and isotopic composition. Chlorine is an important element for tracing these processes because it is incompatible in nearly all minerals, extremely volatile, and strongly hydrophilic [1]. The Cl isotope composition ( 37 Cl/ 35 Cl) of meteoritic components, therefore, can provide useful information regarding the isotopic reservoirs that were present in the early Solar System and any secondary processes that may have occurred on different parent bodies (e.g., [2-4]). There is a relatively narrow range in the Cl isotope compositions of terrestrial, Martian, and chondritic meteorites (δ 37 Cl ~ −6 to +4‰) (e.g., [2,3,5,6]), with exceptions to this being the Moon and Vesta (up to ~ +81‰ and ~ +40‰, respectively) [4, 5, 7-10]. One hypothesis for the extreme Cl isotope fractionation observed on the Moon is degassing following large-scale (possibly even crust-breaching) impact events [7-9]. The role of hypervelocity impacts and impact-generated magmatism in the isotopic evolution of planetary materials, however, has been until recently an area of limited published research with the majority of works focusing on the effects of impact shock (e.g., [10-13]). The ~ 1.85 Ga Sudbury impact crater [14] located in Ontario, Canada, is one of the three largest impact craters on Earth with good exposures of its impact melt sheet and overlying breccias [15,16]. The impact melt sheet, called the Sudbury Igneous Complex (SIC), is up to 5 km thick [17], with an estimated original volume of >10 4 km 3 [18], and differentiated. Recent work demonstrated evaporative loss and isotope fractionation of the moderately volatile element zinc and suggest melt sheets produced by impacts could have a significant effect on the Earth’s volatile inventory [19]. In this study we investigate the abundance and isotopic composition of Cl as well the water abundance of apatite from the SIC and the overlying crater-fill to test the hypothesis that large-scale impacts may have generated the extensive Cl isotopic fractionation observed on the Moon.

Sudbury↗

NASA NTRS2020

Cycling phosphorus on the Archean Earth: Part I. Continental weathering and riverine transport of phosphorus

Phosphorus (P) is the key nutrient thought to limit primary productivity on geological timescales. Phosphate levels in Archean marine sediments are low, but quantification of the P cycle and how it changed through a billion years of recorded Archean history remain a challenge, hindering our understanding of the role played by P in biosphere/geosphere co-evolution on the early Earth. Here, we design kinetic and thermodynamic models to quantitatively assess one key component of the early P cycle – continental weathering – by considering the emergence and elevation of continents, as well as the evolution of climate, the atmosphere, and the absence of macroscopic vegetation during the Archean Eon. Our results suggest that the weathering rate of apatite, the major P-hosting mineral in the rocks, was at least five times higher in the Archean Eon than today, attributable to high levels of pCO2,g. Despite this, the weathering flux of P to the oceans was negligible in the early Archean Eon, increasing to a level comparable to or greater than the modern by the end of eon, a consequence of accelerating continental emergence. Furthermore, our thermodynamic calculations indicate high solubilities of primary and secondary P-hosting minerals in the acidic weathering fluids on land, linking to high Archean pCO2,g. Thus, weathering of P was both kinetically and thermodynamically favorable on the Archean Earth, and river water could transport high levels of dissolved P to the oceans, as also supported by the observed P-depletion in our new compilation of Archean paleosols. Lastly, we evaluated the relative rates of physical erosion and chemical weathering of silicates during the Archean Eon. The results suggest that continental weathering on the early and middle Archean Earth might have been transport-limited due to low erosion rates associated with limited subaerial emergence and low plateau elevations; by the late Archean, however, continental weathering would have transited to kinetically-limited state because of continental emergence, increased plateau elevation, and weakening weathering rates. Overall, our weathering calculations together with paleosol evidence indicate an increasing flux of bioavailable P to the oceans through time, associated with late Archean continental emergence, reaching levels comparable to or higher than modern values by the end of the eon. Increased P fluxes could have fueled increasing rates of primary production, including oxygenic photosynthesis, through time, facilitating the irreversible oxidation of the Earth’s atmosphere early in the Proterozoic Eon.

Phosphorus↗

NASA NTRS2024

Constraining the Thermal and Textural Evolution of Evolved Achondrite DOM 10100: Implications for Volatile Loss

Identification of evolved achrondritic clasts suggests that some early planetesimals experienced extensive differentiation and formed chemically evolved crusts. Many of these samples contain volatile-bearing phases (i.e., apatite, merrillite, nominally anhydrous minerals), which can be used to constrain volatile budgets and abundancies via in-situ measurements. These ancient crustal rocks are subject to high heat, moderate pressures, potentially hot mineral-rich fluids, and degassing that has likely modified many of these volatiles, and their abundancies do not represent the composition of the primary magma from which these achondrites formed. In this work we attempt to deconvolve the thermal evolution of these samples to provide petrologic information that can be used for making inferences regarding their volatile history, and ultimately constraining volatile budgets on planetary bodies in the early Solar System. Here, we combine in-situ major element geochemistry, thermodynamic modeling, and detailed textural and microstructural observations to reconstruct the thermal and textural evolution of howardite DOM 10100, which contains a dacite within its matrix. Previous analyses of several sections of DOM 10100 suggest that the dacitic clast is evidence for partial melting of Vesta’s differentiated basaltic crust, making it an ideal candidate for evolved crustal studies. While its igneous petrogenesis has been well constrained, there is still opportunity to better characterize its post-crystallization thermal history, including possible thermal metamorphism and cooling.

J S Gorce↗

NASA NTRS2024

Microstructural Evolution of the Civet Cat Norite (72255)

The ‘Civet Cat Norite’ is a ~ 2.5 cm clast within the Apollo impact melt breccia sample 72255 collected during Apollo 17 EVA 2 at Boulder 1. The norite is primarily composed of plagioclase and orthopyroxene with fine-scale exsolution lamellae of augite. The plagioclase and orthopyroxene (OPX) coexist with minor quartz and augitic clinopyroxene (CPX), and accessory apatite, baddeleyite, chromite, ilmenite, loveringite, merrillite, rutile and zircon. The major minerals range from 1 to 4 mm in size and show a cataclastic texture indicated by banding of the light and dark phases]. The chemical composition of the orthopyroxene, augitic exsolution lamellae, and exsolved oxides suggest the norite crystallized in the lower crust of the Moon (10 – 70 km depth) and was subsequently excavated by impact(s). Shock pressure estimates for the norite range from 15 – 35 GPa based on maskeleynite formation within the plagioclase, kink banding in pyroxenes, and granular recrystallization in the accessory phosphates. Previous Rb-Sr and 40 Ar/ 39 Ar analyses recalculated with modern decay constants yield relatively young ages of 4.16 ± 0.05 Ga and 3.99 ± 0.03 Ga, respectively. However, recent U-Pb analyses of some zircon grains from within the Civet Cat yield an age of 4.45 ± 0.03 Ga. While this is the oldest age for any rock recovered from the Moon, the full age spread of zircon from the Civet Cat range from ca. 4.46 to 4.02 Ga, indicating variable Pb-loss and complicating interpretation of the primary age. Recent atom probe analyses indicate minimal Pb mobilization within the oldest zircon grain from Civet Cat, supporting the interpretation that these ancient zircon ages reflect the age of the norite, rather than an apparent antiquity caused by reverse discordance. To investigate the potential antiquity and deep crustal origin of the Civet Cat norite, we have undertaken high resolution microstructural analyses of the major, minor, and accessory minerals to characterize the primary igneous textures and secondary overprinting by impact and metamorphism. The employed analytical techniques include scanning electron microscope-based electron backscatter diffraction (EBSD) analyses, electron probe microanalyzer (EPMA) chemical analyses, and transmission electron microscopy (TEM) of pyroxene, plagioclase, quartz, zircon, and phosphates.

T M Erickson↗

NASA NTRS2024

The Isotopic Composition of Molecular Water Formed by Hydrogen Reduction of Iron Oxides: A Proxy for Endogenous Water Formed From Solar Wind Implantation

Many workers have successfully utilized a variety of lunar materials to infer the sources and processing history of volatiles on the Moon. In situ techniques via NanoSIMS have enabled a plethora of hydrogen isotope measurements of isolated grains in regolith and apatite within igneous rocks, revealing an extraordinarily large range of δD values from ~ -900 to +1000‰. The lowest of these δD values are related to the incorporation of solar wind hydrogen, which is pure 1 H. Exposure to solar wind results in structural damage to crystalline phases, forming ubiquitous tens-to-hundreds of nanometer thick amorphous rims on mature regolith grains. Solar wind implantation of H + is also is also thought to result in the formation of nanophase Fe 0 (npFe), a quantitative metric of surface exposure time (e.g., Is/FeO). The formation of npFe can be generally described via the reaction: Fe 2+ O + H 2 = Fe 0 + H 2 O, resulting in the formation of endogenous molecular water reservoirs.

lunar water↗

NASA NTRSDate not supplied

Petrologic Comparison of High- and Low-Titanium Basalt Clasts Derived From ANGSA Core 73001

Volatile elements and compounds significantly influence the properties and behavior of magma, including ascent and eruptive processes. Basalts record a complicated history of the volatile species inherent to their parental magma, and the processes, such as degassing, that change these volatile inventories. On the Moon, outstanding questions remain concerning the behavior of magmatic volatiles and their roles in the evolution of lunar magmas and the formation of mare basalts. As part of the Apollo Next Generation Sample Analysis (ANGSA) program, we are investigating the petrogenesis of two basalt clasts collected from the recently processed Apollo 17 drive tube, 73001. Our team is studying the petrology of the two basalt clasts in 2D and 3D. Recent work has highlighted the utility of coupling traditional 2D methods with 3D measurements to better understand the crystallization and degassing histories of lunar lava flows. We are also investigating the volatile inventory of the samples through in situ studies of volatile-bearing phases, like apatite, to understand the eruptive signatures and degassing histories of low-titanium and high-titanium lunar basalts. At the upcoming conference, we will present the first detailed study of the 2D and 3D mineralogy, textures, 3D vesiculation, and chemistry of these basalt clasts to shed light on their magmatic, volcanic, and post-eruptive histories.

Basalt↗

NASA NTRS2024

Revisiting the petrogenesis of pyroclastic glass bead deposits at the Apollo 15 and 17 sites

The Apollo 15 low-titanium and Apollo 17 high-titanium pyroclastic glass beads are amongst the most primitive magmatically derived samples obtained from the Moon. Two key samples, the low-Ti Apollo 15426 green glass clod and the high-Ti Apollo 74220 orange glass are morphologically distinct, where the Apollo 15 beads are larger (~ 107 μm along maximum axis) and more fractured, and the Apollo 17 are smaller (~42 μm) and less fractured. In this study, holohyaline beads as well as crystallized beads were examined from both samples. Crystallized beads show compositional variability in major, minor, and trace elements and enable examination of magmatic mineral fractionation processes during cooling of both deposits. The Apollo 15426 beads experienced variable olivine crystallization, whereas the Apollo 74220 beads experienced both olivine and ilmenite crystallization. Holohyaline beads from both deposits show more limited major, minor, and trace element variability than their crystallized counterparts. Trace element abundance data for individual holohyaline beads show that in Apollo 74220, they are tightly clustered at ~30 × Carbonaceous Ivuna chondrite [CI] with negative Eu anomalies and subchondritic Nb/Ta, and interpreted to reflect the presence of late-stage magma ocean cumulate overturned into an otherwise primitive mantle source. Incompatible trace element abundances for holohyaline beads in 15426 are supra-chondritic from ~8 × CI, to >80 × CI, with pronounced relative depletions in Sr and Eu for the most incompatible element enriched beads, which represent a distinct bead group within the deposit. Apollo 15426 beads have elevated Ni and Co abundances at the edges of the beads compared to their centers. These data are interpreted to reflect a more complex magmatic evolution of the 15426 deposit, beginning with: (i) initial magma generation, storage and assimilation within shallower low-Ca and high-Ca pyroxene bearing magma ocean cumulates (15B,C); (ii) mobilization of the earlier magmas by more recently generated primitive magmas (15A); (iii) eruption and crystallization of some beads (15D,E), and (iv) later jumbling of the deposit, possible impact contamination and addition of exotic bead components (J Group). In contrast, the 74220 data shows no discernable difference between Ni and Co abundances at the edges and centers supporting prior observations for limited melt fractionation and an absence of meteoritic components. It is further suggested that both deposits are likely to have been formed in the presence of a transient atmosphere. Using 74220 melt compositions from this study, post-entrapment crystallization abundances range from 266 to 1130 micrograms/g for H 2 O, 36 to 68 micrograms/g for F, 441 to 832 micrograms/g for S, and zero to 2.31 micrograms/g for Cl, consistent with prior studies and suggesting up to ~0.1 wt.% H 2 O in the melt, with considerably less in the source. The role that late-stage magma ocean cumulates rich in ilmenite, apatite and high-Ca pyroxene might play in modifying this volatile element estimate, however, casts remaining doubt on the volatile element abundance and evolution of the primitive Moon.

Moon↗

DOE OSTI2017

Preparation, Performance and Mechanism of Tc and I Getters in Cementitious Waste Forms - 17124

Cementitious waste forms offer a low temperature, cost effective technology for the solidification of liquid wastes. At the Department of Energy Hanford Site, 99-Tc and 129-I are radionuclides contained within low activity waste (LAW) which contribute significantly to environmental impacts associated with clean-up of the site. Cast Stone, a cementitious waste form comprised of 47 wt% blast furnace slag, 45 wt% fly ash and 8 wt% ordinary Portland cement, has undergone investigation as a possible candidate technology for the solidification of LAW. In screening tests using EPA Method 1315 leach testing of various mixes of Cast Stone with simulated LAW, Tc observed effective diffusivities (Dobs) had an average of 5.3 x 10-11 cm{sup 2}/s and I Dobs had an average of 5.7 x 10-9 cm{sup 2}/s. From these measurements, an opportunity exists to improve retention of Tc and I by Cast Stone. One approach to accomplish this is through the incorporation of Tc and I getters to selectively sequester Tc and I in the waste stream and eventual waste form. Initial testing conducted at PNNL identified potassium metal sulfide (KMS-2) and Sn(II)-apatite (Sn-A) as the strongest performing Tc getters and silver exchanged zeolite (Ag-Z) as the top performing I getter. This research also demonstrated that the Tc and I getters, when added to solution simultaneously, can have deleterious interactions with one another and lower the Tc and I removal levels. However, these interactions can be overcome through sequential treatment of solution with the getters. Cast Stone samples were fabricated using a 6.5 M Na average LAW simulant spiked with Tc and I with the addition of various combinations of Tc and I getters. Through EPA Method 1315 and Method 1313 testing it was found that the KMS-2 Tc getter was most successful at lowering Tc Dobs. The I getters were not effective, as apparent interference from sulfide components of the waste form may have led to dissociation of the AgI formed by the Ag-Z getter in sequestering the I from solution. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2016

Synthesis of Bismuth Functionalized Grapheme Oxide for Radioactive Iodine Gas Removal - 16114

Released radioactive iodine from nuclear reactors and nuclear severe accidents, such as those experienced at Chernobyl and Fukushima, is one of the most hazardous materials and can affect human health. Uptake of radioactive iodine from gaseous and aqueous waste, consisting of mainly organic forms such as methyl iodide and elemental iodine after reacting with organic matter in scrubber process, is a recent concern during nuclear power plant operation. In general, Triethylenediamine (TEDA) or KI-impregnated activated carbons, silver-loaded silica aerogels, and silver-loaded zeolite are used to remove radioactive iodine compounds. However, previous research has shown TEDA and KI-impregnated activated carbons to have some limitations for use in responding to severe accidents or in pressurized-water reactors, because they are easily burned up and the iodine removal efficiency of silver-loaded sorbents is greatly decreased at high temperatures. To improve the capability of synthesized sorbent material used in iodine gas removal, highly efficient sorbents for methyl and elemental iodine removal were prepared through the functionalization of graphene oxide (GO) with bismuth. GO was synthesized from natural graphite powder (99.95%) by the modified Hummers method, and then mixed with Bi(NO{sub 3}){sub 3}.5H{sub 2}O. After developing a sorbent for the removal of iodine, the synthesized sorbent was characterized using x-ray diffraction, a scanning electron microscope/energy dispersive spectrometer, and thermogravimetric analysis/differential scanning calorimetry, and the surface area of sorbents was determined using the BET-N{sub 2} adsorption method. Methyl iodine batch experiments were conducted for 7 days and elemental iodine gas adsorption experiments were conducted at high temperature (190 deg. C) using a carrier gas (air). The final concentration of iodine in batch and off-gas scrubber solutions (0.1 M NaOH) was analyzed using inductively coupled plasma mass spectrometry. The breakthrough curve and decontamination factor values were also investigated using bismuth-functionalized GO and the results were compared with Ag-zeolite, Sn-apatite, and activated carbon. (authors)

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2012

A Signal-Inducing Bone Cement for Magnetic Resonance Imaging-Guided Spinal Surgery Based on Hydroxyapatite and Polymethylmethacrylate

The aim of this study was to develop a signal-inducing bone cement for magnetic resonance imaging (MRI)-guided cementoplasty of the spine. This MRI cement would allow precise and controlled injection of cement into pathologic lesions of the bone. We mixed conventional polymethylmethacrylate bone cement (PMMA; 5 ml methylmethacrylate and 12 g polymethylmethacrylate) with hydroxyapatite (HA) bone substitute (2-4 ml) and a gadolinium-based contrast agent (CA; 0-60 {mu}l). The contrast-to-noise ratio (CNR) of different CA doses was measured in an open 1.0-Tesla scanner for fast T1W Turbo-Spin-Echo (TSE) and T1W TSE pulse sequences to determine the highest signal. We simulated MRI-guided cementoplasty in cadaveric spines. Compressive strength of the cements was tested. The highest CNR was (1) 87.3 (SD 2.9) in fast T1W TSE for cements with 4 {mu}l CA/ml HA (4 ml) and (2) 60.8 (SD 2.4) in T1W TSE for cements with 1 {mu}l CA/ml HA (4 ml). MRI-guided cementoplasty in cadaveric spine was feasible. Compressive strength decreased with increasing amounts of HA from 46.7 MPa (2 ml HA) to 28.0 MPa (4 ml HA). An MRI-compatible cement based on PMMA, HA, and CA is feasible and clearly visible on MRI images. MRI-guided spinal cementoplasty using this cement would permit direct visualization of the cement, the pathologic process, and the anatomical surroundings.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2018

Red and Yellow Luminescence of Eu{sup 3+}/Dy{sup 3+} Co-Doped Hydroxyapatite/β-Tricalcium Phosphate Single Phosphors Synthesized Using Coprecipitation Method

This paper reports the first attempt at the synthesis of single phosphors of europium (Eu{sup 3+}) and dysprosium (Dy{sup 3+}) co-doped hydroxyapatite (HA)/β-tricalcium phosphate (TCP) nanostructures providing strong red and yellow luminescence depending on annealing temperature and holding time. The morphology of the phosphors was observed to have a nanowire structure. The photoluminescence (PL) intensity of the phosphors increases with annealing temperature and time. The luminescent phosphors also showed the typical luminescence of Eu{sup 3+} centered at 610 nm and Dy{sup 3+} centered at 572 nm, which was more efficient for the annealed Eu{sup 3+}/Dy{sup 3+} co-doped HA/TCP phosphors than for as-synthesized ones. These results suggest that the Eu{sup 3+} and Dy{sup 3+} co-doped HA/TCP nanostructures can find potential application in plant cultivation as environment friendly phosphors.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2018

In Situ Synthesized Hydroxyapatite—Cellulose Nanofibrils as Biosorbents for Heavy Metal Ions Removal

The synthesis of hydroxyapatite (HAp) in the presence of cellulose nanofibrils (CNF) or TEMPO-oxidized CNF (TCNF) was performed in situ by wet chemical precipitation process, using chemical precursors, to hybrid a low-cost biosorbents for removal of Co{sup 2+} as a model heavy metal ion. The removal is investigated by batch adsorption method depending on the pH value, the dosage of adsorbent, initial Co{sup 2+} concentration and the contact time of adsorption. The removal of Co{sup 2+} reached the maximum (87%) at pH 6 by using a dosage of 0.5 g L{sup −1}. The TCNFs is shown to increase the nucleation and growth of the HAp synthesized, providing higher surface area (138 m{sup 2} g{sup −1}) with lower pore diameter (11.89 nm), compared to the CNFs based hybrid (135 m{sup 2} g{sup −1}, 14.42 nm) or pure HAp (118 m{sup 2} g{sup −1}, 13.32 nm), however, both resulting to a higher adsorption capacity (25 mg g{sup −1}) of Co{sup 2+} compared to HAp or TCNF (20–22 mg g{sup −1}). The adsorption is follows primarily by pseudo-first and Elovic order kinetic models which is due to the physisorption of Co{sup 2+} and surface ionic interactions with available negative phosphate (from HAp) and/or carboxylic (from TCNF) groups, fitting well with the Freundlich adsorption isotherm, and secondly due to the ion-exchange mechanism of Co{sup 2+} with Ca{sup 2+} from HAp. Both hybrid adsorbents show good adsorption (≥40%) capacity even after third reusing cycle, and high temperature stability (weight loss of 14%) up to 1000 °C, however, the CNF-HAp hybrid represent a high-value alternative to relatively costly TCNF.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2019

Waste Eggshells for the Decoration of Carbon Nanotubes and Graphene Nanosheets with Hydroxyapatite for Preparation of LLDPE Nanocomposites

Waste eggshells were used to decorate functionalized carbon nanotubes (CNT) and graphene oxide (GO) by hydroxyapatite (HAP) using in situ synthesis. The HAP decorated CNT and GO were characterized by X-ray diffraction, SEM, and IR spectroscopic techniques. CNT-HAP and GO-HAP were further used to prepare polymer nanocomposites by addition of different percentages of synthesized CNT-HAP and GO-HAP as fillers into linear low density polyethylene (LLDPE). The prepared nanocomposites specimens were utilized for physical and thermo-mechanical analysis. Mechanical properties of the LLDPE nanocomposites were improved with increasing the percentage of CNT-HAP and GO-HAP fillers compared to the pristine LLDPE. Hardness of hybrid-CNT-HAP/LLDPE composite was increased as compared to the GO-HAP/LLDPE, where as tensile strength of the GO-HAP/LLDPE was higher than that of the CNT-HAP/LLDPE composite. Flammability of CNT-HAP and GO-HAP composites was decreased by 32% as compared to the pristine LLDPE. Graphic Abstract: .

36 MATERIALS SCIENCE↗

DOE OSTI2015

Petro-mineralogical Studies of the Paleoproterozoic Phosphorites in the Sonrai basin, Lalitpur District, Uttar Pradesh, India

The Paleoproterozoic phosphorites constitute an economically significant component of the Sonrai basin of Lalitpur district. These are associated with ferruginous shale, ironstone, limestone and quartz breccia. Petro-mineralogical studies of samples of the phosphorites, using X-ray diffractometry and scanning electron microscopy, reveal that the collophane (carbonate-fluorapatite) is the dominant phosphate mineral. Calcite, dolomite, quartz, mica and haematite are the dominant gangue constituents. The phosphate minerals occur as oolites mutually replaced by carbonate and silica. The presence of iron oxides has been found in most of the thin sections. There is meagre evidence of organic matter in the form of filaments of microbial phosphate laminae in the samples of phosphorite. The mineral assemblages, their texture and various forms in these phosphorites may be due to some environmental vicissitudes followed by replacement processes and biogenic activities.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2018

The complex of zinc with N-(5,6-dihydro-4H-1,3-thiazine-2-yl)benzamide

A complex of zinc with N-(5,6-dihydro-4H-1,3-thiazin-2-yl)benzamide (L) ligand, LZnCl{sub 2}, was synthesized for subsequent medical trials. The molar extinction coefficients were determined for LHBr solutions in water and physiological saline, and for LZnCl{sub 2} ethanol solution. The ligand stability in various solvents was evaluated and the value of its protonation constant was found for the physiological saline solution, logK = 5.3±0.2. The impossibility of determination of the complex stability constant by the potentiometric titration method was demonstrated. The complex exhibited an insufficient stability in aqueous and physiological saline solutions, but was stable as the solution in alcohol. There was no sorption observed upon the treatment of ligand with hydroxyapatite nanoparticles, which could be a potential carrier for the therapeutic form of LZnCl{sub 2}, providing additional degrees of freedom for the interaction of ligand with cell membranes and a prolonged action of zinc ions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2018

The Effect of Titanium Dioxide (TiO{sub 2}) Nanoparticles on Hydroxyapatite (HA)/TiO{sub 2} Composite Coating Fabricated by Electrophoretic Deposition (EPD)

Composite coatings of Hydroxyapatite (HA) with ceramics, polymers and metals are used to modify the surface structure of implants. In this research, HA/TiO{sub 2} composite coating was fabricated by electrophoretic deposition (EPD) on 316 stainless steel substrate. HA/TiO{sub 2} composite coatings with 5, 10 and 20 wt.% of TiO{sub 2}, deposited at 40 V and 90 s as an optimum condition. The samples coated at this condition led to an adherent, continuous and crack-free coating. The influence of TiO{sub 2} content was studied by performing different characterization methods such as scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), corrosion resistance in simulated body fluid (SBF), coating’s dissolution rate in physiological solution and bond strength to the substrate. The results showed that the higher amount of TiO{sub 2} in the composite coating led to increase in bond strength of coating to stainless steel substrate from 3 MPa for HA coating to 5.5 MPa for HA-20 wt.% TiO{sub 2} composite coating. In addition, it caused to reduction of corrosion current density of samples in the SBF solution from 18.92 μA/cm{sup 2} for HA coating to 6.35 μA/cm{sup 2} for HA-20 wt.% TiO{sub 2} composite coating.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Correlation between Antimicrobial Activity and Bioactivity of Na-Mica and Na-Mica/Fluorapatite Glass and Glass-Ceramics and Their Corrosion Protection of Titanium in Simulated Body Fluid

The improvement in bioactivity of titanium (Ti) surface was achieved via coating it with Na-mica and Na-mica/fluorapatite glass and glass-ceramic using the low-cost electrophoretic deposition technique. Two compositions from pure Na-mica (M) and 80 Na-mica/20 fluorapatite glasses (MF) were prepared in the system SiO{sub 2}-Al{sub 2}O{sub 3}-MgO-MgF{sub 2}-Na{sub 2}O-B{sub 2}O{sub 3} using melting–quenching technique. Characterization of the as-prepared glasses and their counterpart glass-ceramics was studied using differential thermal analysis (DTA), x-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform-IR (FTIR) spectroscopy techniques. The bioactivity behavior was proved by studying the XRD, FTIR and SEM after immersing both glass and glass-ceramic samples in simulated body fluid (SBF). Both M and MF glasses and glass-ceramics showed high microhardness measurements and good antibacterial behavior. In vitro biodegradation was studied by using electrochemical corrosion behavior of the prepared glass- and glass-ceramic-coated Ti in SBF. The prepared coated Ti showed good corrosion resistance in SBF at 37 °C using potentiodynamic polarization technique, and the impedance data fitting explained the structure of the coating and the adsorption of SBF ions on the Ti surface. The MFGC provides the best corrosion-resistant coating, especially after sintering it.

36 MATERIALS SCIENCE↗