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DOE OSTI2026

Emergent pair density wave order across a Lifshitz transition

We numerically investigate the telltale signs of pair-density-wave order (PDW) in the Kondo-Heisenberg chain by focusing on the momentum resolved spectrum in different parameter regimes. Density matrix renormalization group calculations reveal that this phase is characterized by a dispersion with two minima and four Fermi points, indicating the emergence of an effective next-nearest-neighbor hopping that arises as a second-order effect to avoid magnetic frustration. The pairs appear in the spectrum as in-gap bound states with weight concentrated in the hole pockets. The low-energy physics can be understood by means of a generalized t−J model with next-nearest-neighbor hopping. Our results offer a guide for searching for experimental signatures, and for other models that can realize PDW physics.

Yang, Luhang [University of Tennessee Knoxville]↗

NASA NTRS1975

Effect of fuel properties on performance of a single aircraft turbojet combustor

The performance of a single-can JT8D combustor was investigated with a number of fuels exhibiting wide variations in chemical composition and volatility. Performance parameters investigated were combustion efficiency, emissions of CO, unburned hydrocarbons and NOx, as well as liner temperatures and smoke. At the simulated idle condition no significant differences in performance were observed. At cruise, liner temperatures and smoke increased sharply with decreasing hydrogen content of the fuel. No significant differences were observed in the performance of an oil-shale derived JP-5 and a petroleum-based Jet A fuel except for emissions of NOx which were higher with the oil-shale JP-5. The difference is attributed to the higher concentration of fuel-bound nitrogen in the oil-shale JP-5.

Butze, H. F.↗

NASA NTRS1975

Effect of fuel properties on performance of a single aircraft turbojet combustor

Butze, H. F.↗

NASA NTRS1973

Condensation in CO2 free jet expansions. I - Dimer formation.

A theoretical and experimental investigation of the kinetics of CO2 dimer formation in the adiabatically expanding core of a free jet expansion has been carried out. The theoretical analysis is based on dimer formation by an efficient termolecular process and dimer destruction by bimolecular collisions. Account is taken of the expected variation of the specific heat ratio during the expansion and of the effective increase in the termolecular collision rate at low temperatures due to the presence of loosely bound orbiting pairs. Experimental dimer concentrations were measured mass spectrometrically by forming a molecular beam from the expanded gas mixture after the onset of molecular flow. Observed dimer concentrations, for a range of pre-expansion conditions of 400 to 900 torr pressure and room temperature, are in good agreement with the theoretical analysis, provided that account is taken of the effect of loosely bound orbiting pairs at low temperatures.

Dorfeld, W. G.↗

DOE OSTI2022

Use of diffusive gradients in thin films (DGT) to measure potentially bioavailable metals in southeastern USA blackwater streams

Here, we used diffusive gradients in thin films (DGT) to measure potentially bioavailable metals in coastal plain streams in the southeastern USA that exhibited strong to moderate blackwater characteristics. Metals were partitioned into particulate metals, DGT-inert metals (i.e., colloidal and refractory organic complexes not accumulated by DGT), and DGT-labile metals (i.e., free metal ions, small inorganic complexes, and labile organic complexes). We also examined the influence of different DGT deployment times using data collected from the field and a follow-up laboratory study. The DGT-measured fraction of dissolved metals in the streams was 15% for Cd, 21% for Zn, 33% for Cu, 37% for Pb, and 98% for Mn. Metals bound to particulates predominated only for Pb. Most of the Cd, Pb, Zn, and Cu were associated with colloids, refractory organic complexes, or particles. Relatively small amounts were in free ion or labile complexes likely to be bioavailable through respiratory surfaces. Modeled concentrations of free and inorganically bound Cu and Pb were lower than the DGT fraction indicating that DGT accumulated some organically bound Cu and Pb that might not have been bioavailable. DGT-exposure times in excess of 5 days may have contributed to the accumulation of partly labile organic–metal complexes and were associated with substantial biofouling that caused metal uptake by DGT to depart from linearity.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2026

Variations in lithium vapor cave performance predictions due to radial transport and recycling assumptions

The lithium vapor cave is a detached divertor design that uses a single private flux region baffle to contain a dense cloud of lithium vapor to dissipate heat flux. Plasma flows are created via fuel gas puffing in order to minimize lithium contamination of the main plasma. Significant modeling using the 2D edge code SOLPS-ITER has already been performed, predicting that sufficient target heat flux reductions (q$^{max}_{Target}$ MW m −2 ) with ( $n$ Li /$n$ e ) LCFS < 0.05 is possible in a case with 90 MW m −2 unmitigated heat flux in NSTX-U. Low heat flux and low upstream concentration was found with a variety of combinations of divertor geometries, target recycling coefficients, upstream plasma parameters, lithium evaporation locations and deuterium fueling locations, with variations in performance found for each design choice. However, the most universal uncertainty of SOLPS-ITER simulations has until now remained unaddressed systematically, namely the cross-field anomalous particle and heat diffusivities. This article aims to bound the uncertainty in lithium concentration prediction as a result of the assumed deuterium cross-field transport and recycling. For the simulations presented here, a factor of 2.1 increase in the upstream lithium density prediction across a factor of four decrease to the assumed deuterium radial particle diffusivity is found. This result is compared across different assumed deuterium recycling coefficients, known to reduce with lithium injection. Upstream lithium density is found to vary by a factor of 2.4 across a feasible range of recycling coefficients at similar $n$$^{OMP,sep}_{e}$.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2024

High-Fidelity and High-Performance Computational Simulations for Rapid Design Optimization of Sulfur Thermal Energy Storage

Industrial process heating (IPH) accounts for approximately 70% of US manufacturing energy use and is primarily produced by fossil fuel combustion. Approximately 1500 TWht (approximately 60%) of IPH demand is in the temperature range of 100-300. Industrial applications in this temperature range include drying, hydrothermal processing, thermal enhanced oil recovery, food and beverage, bioethanol production, etc. Cost-effective thermal energy storage (TES) that increases the utilization of waste and renewable heat (solar, geothermal, etc.) could provide significant energy savings and reliable heat sources, decrease emissions, and increase US manufacturing competitiveness through reductions in fuel consumption. TES development has historically been dominated by technologies suitable for deployment with concentrating solar power (CSP). State-of-the-art thermal storage deployed commercially with power tower CSP plants uses a 60%/40% NaNO3/KNO3 molten salt and operates between temperatures of approximately 280 degrees Celsius and 570 degrees Celsius using a two-tank configuration. However, these nitrate salts are unsuitable for operation outside of this temperature range due to a high freezing point of approximately 220 degrees Celsius, and limits on high-temperature salt stability and corrosion resistance of containment alloys. Other materials being investigated for TES include those based on: (1) sensible energy storage (various molten salt compositions, inert solid particles, rocks or pebble beds, sulfur, water, concrete, graphite, etc.), (2) latent energy storage in materials that undergo solid-liquid phase change at relevant temperatures (organic materials for low-temperature applications, inorganic salts and/or metals for high-temperature applications), or (3) thermochemical energy storage (hydrides, hydroxides, carbonates, metal oxides, etc.). The application temperature and challenges pertaining to storage material and/or containment cost, energy density, long-term thermal and cyclic stability, and charge/discharge heat transfer effectiveness drive material selection for a given IPH or electricity generation application. Sulfur is a cheap commodity at $80/ton compared to $1100 - 1300/ton for conventional salts. When using a metric of storage cost per kWh, sulfur costs around 2-3 $/kWh. Previous sulfur TES development focused on high temperature (>600 degrees) concentrated solar power applications with sulfur encapsulated in pipes and flow of gaseous HTF (air) in the shell side. However, for lower-temperature IPH applications in the range of approximately 100-300 degrees Celsius Element 16 adopted a compact and scalable TES design with molten sulfur in the shell and HTF pipes submerged in the molten sulfur bath. The low-cost molten sulfur TES for dispatchable IPH has deployment potential for broad applications. The spatial and temporal evolution of the HTF and sulfur temperature is critical to the TES system performance, and thus detailed modeling can improve understanding of the performance and facilitate design improvements. Using high performance computing and computational fluid dynamics (CFD) a low-cost molten sulfur thermal energy storage (TES) system for industrial process heating (IPH) applications was developed. The unique challenges in CFD modeling of sulfur TES are the sharp property changes of sulfur relevant to the working temperatures. Above 159, liquid sulfur undergoes polymerization, and the viscosity of sulfur rapidly increases by several orders of magnitude between 159 degrees Celsius and 188 degrees Celsius, followed by a decrease in viscosity beyond 188 degrees Celsius due to thermal bound dissociation. In addition, various concentrations of H2S impurities can also modify sulfur viscosity. This numerical challenge is especially relevant to transient simulation of the sulfur TES charging and discharging processes as the extreme property variations limit the applicability of traditional heat transfer correlations. Transient CFD simulations including the temperature-dependent sulfur properties and geometric complexity of the TES design were used to predict the effect of natural convection during charging and discharging on the heat transfer process, sulfur temperature uniformity, charge/discharge rates, and performance of the storage devices. The CFD model was validated with experimental results for a full charge and discharge cycle. The work will show 3D and 2D simulation comparisons aimed to facilitate rapid design iterations and a machine learning based design optimization approach.

CFD↗

DOE OSTI2020

Transfer and Flushing Evaluation for Potential Precipitated Solids in the 241-AP-106 to EMF Transfer Pipeline for DFLAW

Waste transfer pipeline flushing is necessary to maintain pipeline performance, but added flush fluid increases the nuclear waste inventory. During the Direct Feed Low-Activity Waste (DFLAW) mission, waste transfer lines from the Interim Low-Activity Waste Storage Tank (i.e., 241-AP-106) to the Hanford Waste Treatment and Immobilization Plant (WTP) Low-Activity Waste (LAW) Facility must have the capability of being flushed to prevent accumulation of solids and to mitigate corrosion concerns. Operational experience at Hanford has shown that the solids precipitation occurs during processing operations from dilute Hanford liquids. Pacific Northwest National Laboratory was requested to evaluate the potential precipitated solid particle transport and flushing operational capabilities of the AP-106 through the Effluent Management Facility (EMF) low-point drain LAW feed pipeline. The evaluation results do not provide operational requirements, but rather provide a scoping basis for understanding the potential operational significance of solids precipitation in the pipeline. The salt and aluminum phase solids most likely to precipitate from the LAW feeds during cooling, evaporation, or mixing have particle densities that are estimated to range from 1.62 to 2.78 g/mL and a spherical particle size range of 8 to 2100 μm, depending on the solid phase considered. Application of the method to calculate the critical deposition velocity required by TFC-ENG-STD-26 at conservatively bounding estimates for the solids concentrations demonstrates that potentially precipitated solids may deposit on the bottom of the transfer pipe invert at the lower LAW feed pipeline flow rate, but the upper LAW feed pipeline flow rate will likely prevent deposition. The system pressure limit for the AP-106 through the EMF low-point drain LAW feed pipeline likely exceeds any pressure loss at a calculated critical deposition velocity even for the most adverse potential precipitated solid. However, should solids settle as a result of no-flow conditions, the flow capabilities of the AP-106 through the EMF low-point drain LAW feed pipeline are shown, based on the available literature, to be potentially inadequate for effective flushing operations to remove solids, even at solids concentrations below the maximum specified for LAW feed. Thus, stepwise solids accumulations over multiple transfers may be an issue, and eventual line plugging may occur. Further inadequacies may potentially be realized should the cohesive nature of certain precipitates be accounted for.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

NASA NTRS1978

Lunar KREEP volcanism - Geologic evidence for history and mode of emplacement

The history of KREEP basalt emplacement in the Fra Mauro and Imbrium basin regions was investigated on the basis of the petrologic and geochemical characteristics of Apollo 14 and 15 samples and data from photogeologic, site geology and remote sensing studies. Results suggest that KREEP emplacement began after the excavation of the South Imbrium basin more than 4.0 to 4.1 billion years ago, continued into early to mid-Imbrium, and was in part sychronous with mare volcanism. Surface KREEP activity appears to be concentrated in a triangular area bounded by the Apollo 15 site, southern Procellarum and the Aristarchus region. Most of the Apollo 15 igneous KREEP basalts are products of post-Imbrium KREEP volcanism within the Imbrium basis, whereas the Apollo 14 KREEP-rich breccias represent extensively reworked KREEP volcanics extruded prior to about 4.0 to 4.1 billion years ago.

Hawke, B. R.↗

NASA NTRS2003

Intercomparisons of Airborne Measurements of Aerosol Ionic Chemical Composition during TRACE-P and ACE-Asia

As part of the two field studies, Transport and Chemical Evolution over the Pacific (TRACE-P), and the Asian Aerosol Characterization Experiment (ACEAsia), the inorganic chemical composition of tropospheric aerosols was measured over the western Pacific from three separate aircraft using various methods. Comparisons are made between the rapid online techniques of the Particle Into Liquid Sampler (PILS) for measurement of a suite of fine particle ionic compounds and a mist chamber (MC/IC) measurement of fine sulfate, and the longer time-integrated filter and multi-orifice impactor (MOI) measurements. Comparisons between identical PILS on two separate aircraft flying in formation showed that they were highly correlated (e.g., sulfate r(sup 2) of 0.95), but were systematically different by 10 +/- 5% (linear regression slope and 95% confidence bounds), and had generally higher concentrations on the aircraft with a low turbulence inlet and shorter inlet-to-instrument transmission tubing. Comparisons of PILS and mist chamber measurements of fine sulfate on two different aircraft during formation flying had an 3 of 0.78 and a relative difference of 39% +/- 5%. MOI ionic data integrated to the PILS upper measurement size of 1.3 pm sampling from separate inlets on the same aircraft showed that for sulfate, PILS and MOI were within 14% +/- 6% and correlated with an r(sup 2) of 0.87. Most ionic compounds were within f 30%, which is in the range of differences reported between PILS and integrated samplers from ground-based comparisons. In many cases, direct intercomparison between the various instruments is difficult due to differences in upper-size detection limits. However, for this study, the results suggest that the fine particle mass composition measured from aircraft agree to within 30-40%.

Ma, Y.↗

NASA NTRS2012

Statistical Theory of the Ideal MHD Geodynamo

A statistical theory of geodynamo action is developed, using a mathematical model of the geodynamo as a rotating outer core containing an ideal (i.e., no dissipation), incompressible, turbulent, convecting magnetofluid. On the concentric inner and outer spherical bounding surfaces the normal components of the velocity, magnetic field, vorticity and electric current are zero, as is the temperature fluctuation. This allows the use of a set of Galerkin expansion functions that are common to both velocity and magnetic field, as well as vorticity, current and the temperature fluctuation. The resulting dynamical system, based on the Boussinesq form of the magnetohydrodynamic (MHD) equations, represents MHD turbulence in a spherical domain. These basic equations (minus the temperature equation) and boundary conditions have been used previously in numerical simulations of forced, decaying MHD turbulence inside a sphere [1,2]. Here, the ideal case is studied through statistical analysis and leads to a prediction that an ideal coherent structure will be found in the form of a large-scale quasistationary magnetic field that results from broken ergodicity, an effect that has been previously studied both analytically and numerically for homogeneous MHD turbulence [3,4]. The axial dipole component becomes prominent when there is a relatively large magnetic helicity (proportional to the global correlation of magnetic vector potential and magnetic field) and a stationary, nonzero cross helicity (proportional to the global correlation of velocity and magnetic field). The expected angle of the dipole moment vector with respect to the rotation axis is found to decrease to a minimum as the average cross helicity increases for a fixed value of magnetic helicity and then to increase again when average cross helicity approaches its maximum possible value. Only a relatively small value of cross helicity is needed to produce a dipole moment vector that is aligned at approx.10deg with the rotation axis.

Shebalin, J. V.↗

NASA NTRS2012

Bound-free Spectra for Diatomic Molecules

It is now recognized that prediction of radiative heating of entering space craft requires explicit treatment of the radiation field from the infrared (IR) to the vacuum ultra violet (VUV). While at low temperatures and longer wavelengths, molecular radiation is well described by bound-bound transitions, in the short wavelength, high temperature regime, bound-free transitions can play an important role. In this work we describe first principles calculations we have carried out for bound-bound and bound-free transitions in N2, O2, C2, CO, CN, NO, and N2+. Compared to bound ]bound transitions, bound-free transitions have several particularities that make them different to deal with. These include more complicated line shapes and a dependence of emission intensity on both bound state diatomic and atomic concentrations. These will be discussed in detail below. The general procedure we used was the same for all species. The first step is to generate potential energy curves, transition moments, and coupling matrix elements by carrying out ab initio electronic structure calculations. These calculations are expensive, and thus approximations need to be made in order to make the calculations tractable. The only practical method we have to carry out these calculations is the internally contracted multi-reference configuration interaction (icMRCI) method as implemented in the program suite Molpro. This is a widely used method for these kinds of calculations, and is capable of generating very accurate results. With this method, we must first of choose which electrons to correlate, the one-electron basis to use, and then how to generate the molecular orbitals.

Schwenke, David W.↗

DOE OSTI2020

Groundwater and Intruder Radionuclide Screening

Solid Waste Management (SWM) operates the E-Area Low-Level Waste Facility (ELLWF) where low level on-site and off-site solid waste streams are buried. The facility has been in operation since late 1994 and is currently projected to remain in operation until 2065. This facility can accommodate a broad range of waste forms resulting from the six different types of disposal unit options (i.e., varying degrees of engineered barriers → trenches to concrete vaults). This facility is currently operating under a Performance Assessment (PA) issued back in 2008, along with several subsequent supporting Special Analyses (SA). The Savannah River National Laboratory (SRNL) developed the prior PAs and SAs and has been tasked to update the facility’s PA. For operating the E-Area facility, a Waste Inventory Tracking System (e.g., WITS) is actively employed by waste generators where every radionuclide entering the facility (to be buried in one of its many disposal units1) must be either directly or indirectly accounted for. Since there is a large number of radionuclides in existence (>3,000), the International Commission on Radiological Protection (ICRP-107) has provided guidance on the subset of radionuclides requiring further assessment in landfills such as the E-Area LLWF. The ICRP-107 publication provides critical radiological information on 1,252 radionuclides of 97 elements. This database is the critical starting point for developing a consistent inventory limit system. The explicit measurement and tracking of all 1,252 ICRP-107 radionuclides can be reduced when process knowledge, burial history, and radiological aspects are factored into conservative groundwater and intruder screening processes. Across the DOE complex these screening processes have been historically performed using the methodology suggested by the National Council on Radiation Protection and Measurements (NCRP) as presented in their original report (NCRP 1984) and then refined in a later report (NCRP 1996). In the recommended screening models employed within this report the traditional NCRP models are updated to better handle progeny and better reflect the known characteristics of E-Area. This improved screening process is referred to as the “NCRP-like” method. Various upgrades to the traditional NCRP methodology have been used by others (e.g., NRC funded effort by Kennedy and Strenge 1992). The more detailed models by Kennedy and Strenge (1992) were considered in this effort and are compared to the results from the more traditional NCRP-like models. The groundwater and inadvertent intruder screening analyses presented in this report start with this 1,252 radionuclide list and reduces it down to more manageable lists that are applicable to the various disposal unit types contained within E-Area. In order to reduce this starting list, some level of exposure risk must be considered acceptable. Historically, a dose (or concentration level) has been compared with a screening criterion set to 1% of a performance measure (e.g., a betagamma dose not to exceed the 4 mrem/yr beta-gamma performance measure x 0.01 = 0.04 mrem/yr). Thus, if a radionuclide produced a bounding or screening-level dose (or concentrations) less than the screening criterion, it could be safely removed from further consideration. Several tiers of screening and bounding level analyses have been considered in this report.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2020

Groundwater and Intruder Radionuclide Screening

Solid Waste Management (SWM) operates the E-Area Low-Level Waste Facility (ELLWF) where low level on-site and off-site solid waste streams are buried. The facility has been in operation since late 1994 and is currently projected to remain in operation until 2065. This facility can accommodate a broad range of waste forms resulting from the six different types of disposal unit options (i.e., varying degrees of engineered barriers → trenches to concrete vaults). This facility is currently operating under a Performance Assessment (PA) issued back in 2008, along with several subsequent supporting Special Analyses (SA). The Savannah River National Laboratory (SRNL) developed the prior PAs and SAs and has been tasked to update the facility’s PA. For operating the E-Area facility, a Waste Inventory Tracking System (e.g., WITS) is actively employed by waste generators where every radionuclide entering the facility (to be buried in one of its many disposal units) must be either directly or indirectly accounted for. Since there is a large number of radionuclides in existence (>3,000), the International Commission on Radiological Protection (ICRP-107) has provided guidance on the subset of radionuclides requiring further assessment in landfills such as the E-Area LLWF. The ICRP-107 publication provides critical radiological information on 1,252 radionuclides of 97 elements. This database is the critical starting point for developing a consistent inventory limit system. The explicit measurement and tracking of all radionuclides are not necessary when process knowledge, burial history, and radiological aspects are factored into conservative groundwater and intruder screening processes. Across the DOE complex these screening processes have been historically performed using the methodology suggested by the National Council on Radiation Protection and Measurements (NCRP) as presented in their original report (NCRP 1984) and then refined in a later report (NCRP 1996). In the recommended screening models employed within this report the traditional NCRP models are updated to better handle progeny and better reflect the known characteristics of E-Area. This improved screening process is referred to as the “NCRP-like” method. Various upgrades to the traditional NCRP methodology have been used by others (e.g., NRC funded effort by Kennedy and Strenge 1992). The more detailed models by Kennedy and Strenge (1992) were considered in this effort and are compared to the results from the more traditional NCRP-like models. The groundwater and inadvertent intruder screening analyses presented in this report start with this 1,252 radionuclide list and reduces it down to more manageable lists that are applicable to the various disposal unit types contained within E-Area. In order to reduce this starting list, some level of exposure risk must be considered acceptable. Historically, a dose (or concentration level) has been compared with a screening criterion set to 1% of a performance measure (e.g., a beta-gamma dose not to exceed the 4 mrem/yr beta-gamma performance measure x 0.01 = 0.04 mrem/yr). Thus, if a radionuclide produced a bounding or screening-level dose (or concentrations) less than the screening criterion, it could be safely removed from further consideration. Several tiers of screening and bounding level analyses have been considered in this report.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2020

Assessment of the MACCS Code Applicability for Nearfield Consequence Analysis

Three codes are used for comparisons in this report to evaluate the adequacy of MACCS in the nearfield, AERMOD, ARCON96 and QUIC. Test cases were developed to give a broad range of weather conditions, building dimensions and plume buoyancy. Based on the comparisons of MACCS with AERMOD, ARCON96 and QUIC across the test cases, the following observations are made: MACCS calculations configured with point-source, ground-level, nonbuoyant plumes provide nearfield results that bound the centerline, ground-level air concentrations from AERMOD, ARCON96, and QUIC. MACCS calculations with ground-level, nonbuoyant plumes that include the effects of the building wake (area source) provide nearfield results that bound the results from AERMOD and QUIC and the results from ARCON96 at distances >250 m. If using a point-source is too conservative and it is desired to bound the results from all three codes, another alternative is to use area source parameters in MACCS that are less than the standard values, i.e., an area source intermediate between the standard recommendation and a point source. All these options provide results from MACCS that are bounding for the test cases evaluated. Based on these observations, it appears that MACCS is adequate for use in nearfield calculations, given the correct parameterization.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

DOE OSTI2023

Application of Time-Domain 1 H NMR for Investigating Dynamics of Vegetative Lipids in Bioenergy Crops at Different Developmental Stages

Sweet sorghum is typically cultivated for the food and fodder market. Recently, sweet sorghum varieties are being metabolically transitioned to enhance energy density by accumulating oil droplets in their vegetative tissues for bioenergy applications. Owing to the high biomass yield of sorghum, the transgenic lines can compete with oil-seed crops for biodiesel yield per unit area. In the initial phase of transgenic development, a high-throughput phenotyping method can bridge the gap between the production pipeline and analysis to improve the efficiency of the process. To meet the requirement, the present study extends the application of time-domain 1 H-NMR spectroscopy for rapid quantification and characterization of the total in-situ lipids of sweet sorghum ‘ramada’ to lay the groundwork for analyzing the upcoming large quantity of transgenic samples. NMR technology has been successfully established for analyzing lipid contents of vegetative tissues of non-transgenic variety. The multiexponential analysis of spin-lattice (T 1 ) relaxation spectra obtained from TD-NMR aided the investigation of the dynamics of the free and bound lipid fraction with plant development. The total lipid concentration of bagasse and leaves of non-transgenic sweet sorghum remained unchanged throughout the plant development. Leaves displayed a higher percentage of bound lipids as compared to bagasse. Here, a significant variation in the lipid concentration of juice was observed at the different growth stages with a maximum lipid accumulation of 1.21 ± 0.04% w/w at the boot stage that decreased with further maturity of the plant.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2023

Data for Application of Time-Domain 1H NMR for Investigating Dynamics of Vegetative Lipids in Bioenergy Crops at Different Developmental Stages

Sweet sorghum is typically cultivated for the food and fodder market. Recently, sweet sorghum varieties are being metabolically transitioned to enhance energy density by accumulating oil droplets in their vegetative tissues for bioenergy applications. Owing to the high biomass yield of sorghum, the transgenic lines can compete with oil-seed crops for biodiesel yield per unit area. In the initial phase of transgenic development, a high-throughput phenotyping method can bridge the gap between the production pipeline and analysis to improve the efficiency of the process. To meet the requirement, the present study extends the application of time-domain 1H-NMR spectroscopy for rapid quantification and characterization of the total in-situ lipids of sweet sorghum ‘ramada’ to lay the groundwork for analyzing the upcoming large quantity of transgenic samples. NMR technology has been successfully established for analyzing lipid contents of vegetative tissues of non-transgenic variety. The multiexponential analysis of spin-lattice (T1) relaxation spectra obtained from TD-NMR aided the investigation of the dynamics of the free and bound lipid fraction with plant development. The total lipid concentration of bagasse and leaves of non-transgenic sweet sorghum remained unchanged throughout the plant development. Leaves displayed a higher percentage of bound lipids as compared to bagasse. A significant variation in the lipid concentration of juice was observed at the different growth stages with a maximum lipid accumulation of 1.21 ± 0.04% w/w at the boot stage that decreased with further maturity of the plant.

Biomass Analytics↗

DOE OSTI2022

External charge compensation in etched gallium nitride measured by x-ray photoelectron spectroscopy

Electronic states at GaN surfaces and at regrowth and heteroepitaxy interfaces inhibit electronic device performance. Understanding electronic state configuration at the GaN surface is, therefore, crucial for the development of GaN-based devices, which are currently of considerable interest in power electronic applications. GaN and other wurtzite III-nitrides possess large spontaneous polarization along the c-axis, producing a bound sheet charge at the surface, which affects the electronic state configuration through the formation of internal and external compensation charges. Defects induced by conventional plasma-based dry etching methods may inhibit the internal screening of this bound charge and thus increase the concentration of external charged states. The surface band bending of n-type Ga-face GaN (0001) was measured with x-ray photoelectron spectroscopy after inductively coupled plasma etching to investigate the impact of dry etching on external charge compensation. GaN samples were etched using inductively coupled plasma with varying rf power and a novel plasma-enhanced atomic layer etching method using an oxidation, fluorination, and ligand-exchange mechanism. The band bending varied from 0.0 to 0.8 ± 0.1 eV for the samples measured.

Hatch, Kevin A. (ORCID:0000000283118623)↗