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15 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Nuclear Data Sheets for A = 44

The experimental data are evaluated for known nuclides of mass number A=44 (Si,P,S,Cl,Ar,K,Ca,Sc,Ti,V, Cr,Mn). Detailed evaluated level properties and related information are presented, including adopted values of level and {gamma}-ray energies, decay data (energies, intensities and placement of radiations), and other spectroscopic data. This work supersedes earlier full evaluations of A=44 published by 1999Ca45 and 1990En08 (also 1998En04 update). No excited states are known in {sup 44}Si, {sup 44}P, {sup 44}Cr, {sup 44}Mn. Only one excited state is known in 44V and its Isobaric Analog State (IAS) has been observed but with the level energy not known. Information for {sup 44}S, {sup 44}Cl and {sup 44}Ar is limited and their radioactive decay schemes seem incomplete in view of large Q values and known excitations much below than allowed by Q values. The {sup 44}Ca, {sup 44}Sc and {sup 44}Ti nuclides remain as the most extensively studied from many different reactions and decays.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

ISOCHRONS IN PRESOLAR GRAPHITE GRAINS FROM ORGUEIL

Primitive meteorites contain tiny dust grains that condensed in stellar outflows and explosions. These stardust grains can be extracted from their host meteorites and studied in detail in the laboratory. We investigated depth profiles of the Al-Mg, Ca-K, and Ti-Ca isotopic systems obtained during NanoSIMS isotopic analysis of presolar graphite grains from the CI carbonaceous meteorite Orgueil. Large {sup 26}Al/{sup 27}Al, {sup 41}Ca/{sup 40}Ca, and {sup 44}Ti/{sup 48}Ti ratios, inferred from {sup 26}Mg, {sup 41}K, and {sup 44}Ca excesses from the decay of the short-lived radioisotopes {sup 26}Al, {sup 41}Ca, and {sup 44}Ti, indicate a supernova (SN) origin. From the depth distribution of the radiogenic isotopes and the stable isotopes of their parent elements we constructed isochron-type correlation plots. The plots indicate quantitative retention of radiogenic {sup 26}Mg, {sup 41}K, and {sup 44}Ca in most grains. Deviations from straight lines in the Al-Mg and Ca-K plots can be explained by contamination with {sup 27}Al and isotopically normal Ca, respectively. For the Ti-Ca system in some grains, the lack of parent-daughter correlation indicates either redistribution of radiogenic {sup 44}Ca or heterogeneity in the initial {sup 44}Ti/{sup 48}Ti ratio. We also obtained Si isotopic depth profiles in three graphite grains with large {sup 29}Si and {sup 30}Si excesses, for which a SN origin has been proposed. In two grains no Si-rich subgrains are observed; in the third grain with an apparent Si-rich subgrain the anomalous Si isotopic ratios in the subgrain are the same as in the rest of the graphite host. Our studies show that by measuring depth profiles, information on presolar grains can be obtained that cannot be obtained by whole-grain analysis.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Flooding and ecological restoration promote wetland microbial communities and soil functions on former cranberry farmland

Microbial communities are early responders to wetland degradation, and instrumental players in the reversal of this degradation. However, our understanding of soil microbial community structure and function throughout wetland development remains incomplete. We conducted a survey across cranberry farms, young retired farms, old retired farms, flooded former farms, ecologically restored former farms, and natural reference wetlands with no history of cranberry farming. We investigated the relationship between the microbial community and soil characteristics that restoration intends to maximize, such as soil organic matter, cation exchange capacity and denitrification potential. Among the five treatments considered, flooded and restored sites had the highest prokaryote and microeukaryote community similarity to natural wetlands. In contrast, young retired sites had similar communities to farms, and old retired sites failed to develop wetland microbial communities or functions. Canonical analysis of principal coordinates revealed that soil variables, in particular potassium base saturation, sodium, and denitrification potential, explained 45% of the variation in prokaryote communities and 44% of the variation in microeukaryote communities, segregating soil samples into two clouds in ordination space: farm, old retired and young retired sites on one side and restored, flooded, and natural sites on the other. Heat trees revealed possible prokaryotic ( Gemmatimonadetes ) and microeukaryotic ( Rhizaria ) indicators of wetland development, along with a drop in the dominance of Nucletmycea in restored sites, a class that includes suspected mycorrhizal symbionts of the cranberry crop. Flooded sites showed the strongest evidence of wetland development, with triple the soil organic matter accumulation, double the cation exchange capacity, and seventy times the denitrification potential compared to farms. However, given that flooding does not promote any of the watershed or habitat benefits as ecological restoration, we suggest that flooding can be used to stimulate beneficial microbial communities and soil functions during the restoration waiting period, or when restoration is not an option.

Rubin, Rachel L. (ORCID:0000000284326811)↗
DOE OSTI2017

Young Stars with SALT

We present a spectroscopic and kinematic analysis of 79 nearby M dwarfs in 77 systems. All of these dwarfs are low-proper-motion southern hemisphere objects and were identified in a nearby star survey with a demonstrated sensitivity to young stars. Using low-resolution optical spectroscopy from the Red Side Spectrograph on the South African Large Telescope, we have determined radial velocities, H-alpha, lithium 6708 Å, and potassium 7699 Å equivalent widths linked to age and activity, and spectral types for all of our targets. Combined with astrometric information from literature sources, we identify 44 young stars. Eighteen are previously known members of moving groups within 100 pc of the Sun. Twelve are new members, including one member of the TW Hydra moving group, one member of the 32 Orionis moving group, 9 members of Tucana-Horologium, one member of Argus, and two new members of AB Doradus. We also find 14 young star systems that are not members of any known groups. The remaining 33 star systems do not appear to be young. This appears to be evidence of a new population of nearby young stars not related to the known nearby young moving groups.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

Intracellular segment between transmembrane helices S0 and S1 of BK channel α subunit contains two amphipathic helices connected by a flexible loop

Highlights: •The loop between S0 and S1 of BK channel was overexpressed and purified in DPC. •NMR studies indicated BK-IS1 contained two helices connected by a flexible loop. •Mg{sup 2+} titration of BK-IS1 indicated two possible binding sites of divalent ions. -- Abstract: The BK channel, a tetrameric potassium channel with very high conductance, has a central role in numerous physiological functions. The BK channel can be activated by intracellular Ca{sup 2+} and Mg{sup 2+}, as well as by membrane depolarization. Unlike other tetrameric potassium channels, the BK channel has seven transmembrane helices (S0–S6) including an extra helix S0. The intracellular segment between S0 and S1 (BK-IS1) is essential to BK channel functions and Asp99 in BK-IS1 is reported to be responsible for Mg{sup 2+} coordination. In this study, BK-IS1 (44–113) was over-expressed using a bacterial system and purified in the presence of detergent micelles for multidimensional heteronuclear nuclear magnetic resonance (NMR) structural studies. Backbone resonance assignment and secondary structure analysis showed that BK-IS1 contains two amphipathic helices connected by a 36-residue loop. Amide {sup 1}H–{sup 15}N heteronuclear NOE analysis indicated that the loop is very flexible, while the two amphipathic helices are possibly stabilized through interaction with the membrane. A solution NMR-based titration assay of BK-IS1 was performed with various concentrations of Mg{sup 2+}. Two residues (Thr45 and Leu46) with chemical shift changes were observed but no, or very minor, chemical shift difference was observed for Asp99, indicating a possible site for binding divalent ions or other modulation partners.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Experimental and theoretical investigation of a mesoporous K x WO 3 material having superior mechanical strength

Mesoporous materials with tailored properties hold great promise for energy harvesting and industrial applications. Here we have synthesized a novel tungsten bronze mesoporous material (K x WO 3 ; x ~ 0.07) having inverse FDU-12 type pore symmetry and a crystalline framework. In situ small angle X-ray scattering (SAXS) measurements of the mesoporous K 0.07 WO 3 show persistence of a highly ordered meso-scale pore structure to high pressure conditions (~18.5 GPa) and a material with remarkable mechanical strength despite having ~35% porosity. Pressure dependent in situ SAXS measurements reveal a bulk modulus κ = 44 ± 4 GPa for the mesoporous K x WO 3 which is comparable to the corresponding value for the bulk monoclinic WO 3 (γ-WO 3 ). Evidence from middle angle (MAXS) and wide angle X-ray scattering (WAXS), high-resolution transmission electron microscopy (HR-TEM) and Raman spectroscopy shows that the presence of potassium leads to the formation of a K-bearing orthorhombic tungsten bronze (OTB) phase within a monoclinic WO 3 host structure. Our ab initio molecular dynamics calculations show that the formation of the OTB phase provides superior strength to the mesoporous K 0.07 WO 3 .

36 MATERIALS SCIENCE↗
DOE OSTI2018

Potassium and Calcium Isotopic Fractionation by Plants (Soybean [Glycine max], Rice [Oryza sativa], and Wheat [Triticum aestivum])

Here, we conducted hydroponic experiments growing soybean (Glycine max), rice (Oryza sativa), and wheat (Triticum aestivum) under K and Ca replete conditions to establish the degree of K isotopic fractionation by plants, and compare the isotopic fractionation of Ca and K. Each of the test plants displays fractionation relative to the growth solution favoring the light isotopes of K and Ca. The average δ 41 K values of the roots from the three plant species were similar, and have an overall average of -0.55 ± 0.24‰ 2s, while the overall average δ 44 Ca for roots is -0.67 ± 0.44. For leaves, the overall average of δ 41 K is -0.97 ± 0.4‰, compared to an overall average leaf δ 44 Ca of -0.83 ± 0.09‰. In the case of the soybean plants, the lightest K and Ca occurs in the stems with average δ 41 K of -1.31 ± 0.40‰ 2s and average δ 44 Ca of -1.20 ± 0.19 ‰ 2s. We present a simple box model involving the relative fluxes of K and its isotopic fractionation that reproduces our K isotopic observations and suggests a fractionation of ~0.8‰ with K uptake from solution by roots. Finally, directly comparing the per amu fractionation of K and Ca reveals an average factor of 2.05 ± 0.50 2s greater fractionation of K isotopes which may reflect their different roles and behaviors in plants.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Greenhouse gas emissions from production chain of a cigarette manufacturing industry in Pakistan

This study quantified greenhouse gas (GHG) emissions from the Pakistan Tobacco Company (PTC) production using a life cycle approach. The PTC production chain comprises of two phases: agricultural activities (Phase I) and industrial activities (Phase II). Data related to agricultural and industrial activities of PTC production chain were collected through questionnaire survey from tobacco growers and records from PTC manufacturing units. The results showed that total GHG emissions from PTC production chain were 44,965, 42,875, and 43,839 tCO{sub 2}e respectively in 2009, 2010, and 2011. Among the agricultural activities, firewood burning for tobacco curing accounted for about 3117, 3565, and 3264 tCO{sub 2}e, fertilizer application accounted for 754, 3251, and 4761 tCO{sub 2}e in 2009, 2010, and 2011, respectively. Among the industrial activities, fossil fuels consumption in stationary sources accounted for 15,582, 12,733, and 13,203 tCO{sub 2}e, fossil fuels used in mobile sources contributed to 2693, 3038, and 3260 tCO{sub 2}e, and purchased electricity consumed resulted in 15,177, 13,556, and 11,380 tCO{sub 2}e in 2009, 2010, and 2011, respectively. The GHG emissions related to the transportation of raw materials and processed tobacco amounted to 6800, 6301, and 7317 respectively in 2009, 2010, and 2011. GHG emissions from energy use in the industrial activities constituted the largest emissions (i.e., over 80%) of GHG emissions as PTC relies on fossil fuels and fossil fuel based electrical power in industrial processes. The total emissions of carbon footprint (CFP) from PTC production were 0.647 tCO{sub 2}e per million cigarettes produced in 2009, 0.675 tCO{sub 2}e per million cigarettes in 2010 and 0.59 tCO{sub 2}e per million cigarettes in 2011. Potential strategies for GHG emissions reductions for PTC production chain include energy efficiency, reducing reliance on fossil fuels in non-mobile sources, adoption of renewable fuels including solar energy, energy from crop residues, and promotion of organic fertilizers. - Highlights: • We quantified greenhouse gas (GHG) emissions from the Pakistan Tobacco Company (PTC). • PTC production chain comprises of two phases: agricultural and industrial activities. • GHG emissions accounts to 44,965, 42,875 and 43,839 tCO{sub 2}e in 2009, 2010, and 2011, respectively. • GHG emissions from energy use in the industrial activities constituted the largest emissions i.e. 80%. • Implications for GHG emissions mitigation strategies for PTC are also discussed in detail.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Synthesis and characterization of uranium trichloride in alkali-metal chloride media

Given a growing interest in uranium salts for pyrochemical processing of used fuel and uranium-fueled molten salt reactors, the synthesis of uranium trichloride in alkali-metal chloride media was investigated in a series of four experiments. Specifically, uranium metal powder and uranium hydride powder were prepared and separately blended with ammonium chloride and lithium chloride – potassium chloride eutectic in two runs, while the same powders were separately blended with ammonium chloride and sodium chloride in two additional runs. Each of the lithium chloride – potassium chloride containing blends was slowly heated to 923 K, while those containing sodium chloride were heated to 1123 K. During each heat up, the ammonium chloride sublimed into gaseous ammonia and hydrogen chloride, leading to the chlorination of uranium metal or uranium hydride and the formation of molten salt solutions of the respective chlorides. Experimental conditions were incorporated in the runs to promote formation of uranium trichloride over uranium tetrachloride in the respective media. Molten samples of each run product were taken and characterized via chemical analyses, diffractometry, and microscopy. The final products from each run were dark dense ingots of the respective salt systems with uranium concentrations ranging from 44 to 51 wt%. Finally, chemical analyses and diffractometry identified the predominant presence of uranium trichloride in these systems; however, a possible minor presence of uranium tetrachloride could not be conclusively dismissed.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Synthesis and characterization of uranium trichloride in alkali-metal chloride media

Given a growing interest in uranium salts for pyrochemical processing of used fuel and uranium-fueled molten salt reactors, the synthesis of uranium trichloride in alkali-metal chloride media was investigated in a series of four experiments. Specifically, uranium metal powder and uranium hydride powder were prepared and separately blended with ammonium chloride and lithium chloride – potassium chloride eutectic in two runs, while the same powders were separately blended with ammonium chloride and sodium chloride in two additional runs. Each of the lithium chloride – potassium chloride containing blends was slowly heated to 923 K, while those containing sodium chloride were heated to 1123 K. During each heat up, the ammonium chloride sublimed into gaseous ammonia and hydrogen chloride, leading to the chlorination of uranium metal or uranium hydride and the formation of molten salt solutions of the respective chlorides. Experimental conditions were incorporated in the runs to promote formation of uranium trichloride over uranium tetrachloride in the respective media. Molten samples of each run product were taken and characterized via chemical analyses, diffractometry, and microscopy. The final products from each run were dark dense ingots of the respective salt systems with uranium concentrations ranging from 44 to 51 wt%. Chemical analyses and diffractometry identified the predominant presence of uranium trichloride in these systems; however, a possible minor presence of uranium tetrachloride could not be conclusively dismissed.

D Herrmann, Steven↗
DOE OSTI2016

Development of a Smart Signal Detection Method for Cyclic Voltammetry via Artificial Neural Intelligence

The electrorefiner (ER) is the heart of pyroprocessing technology which is a high-temperature method for separating uranium from Used Nuclear Fuel (UNF). It is important to improve this technology with respect to nuclear materials detection and accountability. Artificial Neural Intelligence (ANI) is a novel data analysis and simulation method that can be applied to electrochemical data sets. This computational code, which has been performed using the commercial software MATLAB, can be trained to generalize adequate electrical current and potential simulated data sets for the unseen data with a high accuracy of prediction. For this purpose, a massive collection of cyclic voltammetry (CV) data sets by Hoover (2014), for 0.5, 1, 2.5, and 5 wt% of zirconium chloride in LiCl-KCl molten salt with different scan rates at 773 K has been considered. The computer is trained via ANI to predict the unseen data after providing suitable hidden layers and validation numbers. In addition, this work can trace the CV plot for a blind condition by interpolating between two simulated data set. The different hidden layers with various neurons (from 5 to 30) at several validation numbers (from 5 to 30) has been studied and the average percent error between experimental and theoretical data for 0.5 wt% with 200 and 450 mV/s has been calculated. Preliminary results demonstrate that if the number of hidden layers increases from one to three, the average error falls down from 44% to around 8%. The best condition which gives a minimum average percent error has been discovered and the simulated CV graph has been compared with the experimental data. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2011

Effect of Boron doping on the electronic properties of the fullerenes of different sizes

We report the results of the effect of Boron doping in C{sub n}; n = 28, 32, 36, 40, 44, 50 and 60 using the first principle calculation based on density functional theory. The HOMO-LUMO gap changes significantly with the decreasing fullerene size below C{sub 60}, with maximum gap observed for C{sub 32}. The HOMO-LUMO gap of Boron doped fullerenes varies significantly w.r.t. pure fullerenes. Also, the gap decreases for C{sub n-m}B{sub m}X, the boron doped fullerenes with exohedral alkali metals for n = 28, 32, 36, 40, 44, 50 and 60; m = 1 to 4; X = Li, Na and K. The Mulliken charge transfer from the exohedral alkali metals towards the various fullerene cages is altered marginally by the boron doping in fullerenes and follows the order K>Na>Li.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Potassium-Promoted Reduction of Cu 2 O/Cu(111) by CO

In situ X-ray photoelectron spectroscopy (XPS), infrared reflection absorption spectroscopy (IRRAS), and scanning tunneling microscopy (STM) were used to study the reduction of potassium-modified Cu 2 O/Cu(111) by CO. By following the time evolution of the O 1s peak of Cu 2 O, we determined that the apparent activation energy for Cu 2 O reduction by 2 × 10 –4 Torr CO is decreased by ~30% in the presence of K. On the K-modified surface, both XPS and IRRAS data show the formation of a surface species identified by IRRAS as carbonate (CO 3 2– ), likely forming a K + -CO 3 2– complex, which is stable up to 500 K. STM images show that K + -CO 3 2– complexes form chains around reduced Cu islands, thereby hindering the mass transfer of Cu atoms and preventing the reconstruction of the surface. Theoretical calculations show that the formation of carbonate on the K-modified “44” Cu 2 O structure is thermodynamically favorable compared to the formation of CO 2 on either the bare or K-modified surfaces.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Soil fertility management for sustainable Miscanthus × giganteus production: Increased tiller weight from nitrogen management explains yield gains in aged miscanthus

Aging-related yield decline in Miscanthus × giganteus (miscanthus) remains a major constraint to sustainable biomass production. This study evaluated how nitrogen (N) management and soil fertility influence yield-component traits and productivity in aging miscanthus. Trials were conducted at two sites established in 2008 at the University of Illinois Energy Farm, Urbana, IL. (i) The Sun Grant trial received 0, 60, and 120 kg N ha −1 annually until 2015. Starting 2021, half of each plot received 60 or 120 kg N ha −1 , resulting in six legacy-contemporary treatments: 0N–0N, 0N–120N, 60N–0N, 60N–60N, 120N–0N, 120N–120N. (ii) The Energy Farm trial remained unfertilized until 2014, when one half of each plot received 56 kg N ha −1 , forming two treatments: 0N–0N, 0N–56N. Sun Grant trial results showed N fertilization increased tiller density (tillers m −2 ) and tiller weight (g tiller −1 ) in juvenile to early-mature miscanthus (2011–2015). After N withdrawal, both traits declined (20 % and 40 %), though legacy effects persisted in tiller weight in the aging stands (2020–2023). Contemporary N had little effect on tiller density but increased tiller weight by 34 %–77 %, resulting in 23 %–106 % higher machine-harvested biomass yield in 0–120N, 60-60N, and 120-120N plots. At the Energy Farm trial, 0N–56N plots yielded 59 %–108 % more biomass than 0N–0N. Soil total N increased (Sun Grant: 47 % by 2020; Energy Farm: 58 % by 2023), while Mehlich-3 P (42 %–44 %) and K (21 %–46 %) declined. These findings identify tiller weight as a key determinant of biomass yield in aging miscanthus and highlight the need for P and K management for long-term productivity.

09 BIOMASS FUELS↗
DOE OSTI2015

Theoretical calculations of rotationally inelastic collisions of He with NaK(A {sup 1}Σ{sup +}): Transfer of population, orientation, and alignment

We have performed extensive calculations to investigate thermal energy, rotationally inelastic collisions of NaK (A{sup 1}Σ{sup +}) with He. We determined a potential energy surface using a multi-reference configuration interaction wave function as implemented by the GAMESS electronic structure code, and we have performed coupled channel scattering calculations using the Arthurs and Dalgarno formalism. We also calculate the Grawert coefficients B{sub λ}(j, j′) for each j → j′ transition. These coefficients are used to determine the probability that orientation and alignment are preserved in collisions taking place in a cell environment. The calculations include all rotational levels with j or j′ between 0 and 50, and total (translational and rotational) energies in the range 0.0002–0.0025 a.u. (∼44–550 cm{sup −1}). The calculated cross sections for transitions with even values of Δj tend to be larger than those for transitions with odd Δj, in agreement with the recent experiments of Wolfe et al. (J. Chem. Phys. 134, 174301 (2011)). The calculations of the energy dependence of the cross sections and the calculations of the fraction of orientation and alignment preserved in collisions also exhibit distinctly different behaviors for odd and even values of Δj. The calculations also indicate that the average fraction of orientation or alignment preserved in a transition becomes larger as j increases. We interpret this behavior using the semiclassical model of Derouard, which also leads to a simple way of visualizing the distribution of the angles between the initial and final angular momentum vectors j and j′. Finally, we compare the exact quantum results for j → j′ transitions with results based on the simpler, energy sudden approximation. That approximation is shown to be quite accurate.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗