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At least 235 records · Page 13

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DOE OSTI2013

An environmental sample chamber for reliable scanning transmission x-ray microscopy measurements under water vapor

We have designed, fabricated, and tested a compact gas-phase reactor for performing in situ soft x-ray scanning transmission x-ray microscopy (STXM) measurements. The reactor accommodates many gas atmospheres, including reactive or corrosive gasses, but was designed specically to address the needs of measurements under water vapor. An on-board sensor measures the relative humidity and temperature inside the reactor, minimizing uncertainties associated with measuring these quantities outside the instrument. The reactor mounts directly to the existing sample holder used in the majority of STXM instruments around the world and installs with minimal instrument reconguration. Using the reactor contributes over 85% less additional absorption compared to lling the STXM chamber with process gas, and results in much more stable imaging conditions. The reactor is in use at the STXM instruments at beamlines 11.0.2 and 5.3.2.2 at the Advanced Light Source.

Environmental Molecular Sciences Laboratory↗

DOE OSTI2022

Practical guide to replica exchange transition interface sampling and forward flux sampling

Path sampling approaches have become invaluable tools to explore the mechanisms and dynamics of the so-called rare events that are characterized by transitions between metastable states separated by sizable free energy barriers. Their practical application, in particular to ever more complex molecular systems, is, however, not entirely trivial. Here, focusing on replica exchange transition interface sampling (RETIS) and forward flux sampling (FFS), we discuss a range of analysis tools that can be used to assess the quality and convergence of such simulations, which is crucial to obtain reliable results. The basic ideas of a step-wise evaluation are exemplified for the study of nucleation in several systems with different complexities, providing a general guide for the critical assessment of RETIS and FFS simulations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2023

The SOUX AGN sample: SDSS– XMM-Newton optical, ultraviolet, and X-ray selected active galactic nuclei spanning a wide range of parameter space – sample definition

Abstract We assemble a sample of 696 type 1 active galactic nuclei (AGN) up to a redshift of z = 2.5, all of which have an SDSS spectrum containing at least one broad emission line (H α, H β, or Mg ii) and an XMM-Newton X-ray spectrum containing at least 250 counts in addition to simultaneous optical/ultraviolet photometry from the XMM Optical Monitor. Our sample includes quasars and narrow-line Seyfert 1s: thus our AGN span a wide range in luminosity, black hole mass, and accretion rate. We determine single-epoch black hole mass relations for the three emission lines and find that they provide broadly consistent mass estimates whether the continuum or emission line luminosity is used as the proxy for the broad emission line region radius. We explore variations of the UV/X-ray energy index αox with the UV continuum luminosity and with black hole mass and accretion rate, and make comparisons to the physical quasar spectral energy distribution model qsosed. The majority of the AGN in our sample lie in a region of parameter space with 0.02 < L/LEdd < 2 as defined by this model, with narrow-line type 1 AGN offset to lower masses and higher accretion rates than typical broad-line quasars. We find differences in the dependence of αox on UV luminosity between both narrow/broad-line and radio-loud/quiet subsets of AGN: αox has a slightly weaker dependence on UV luminosity for broad-line AGN and radio-loud AGN have systematically harder αox.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2025

The XMM Cluster Survey: automating the estimation of hydrostatic mass for large samples of galaxy clusters – I. Methodology, validation, and application to the SDSSRM-XCS sample

ABSTRACT We describe features of the X-ray: Generate and Analyse (xga) open-source software package that have been developed to facilitate automated hydrostatic mass ($M_{\rm hydro}$) measurements from XMM X-ray observations of clusters of galaxies. This includes describing how xga measures global, and radial, X-ray properties of galaxy clusters. We then demonstrate the reliability of xga by comparing simple X-ray properties, namely the X-ray temperature and gas mass, with published values presented by the XMM Cluster Survey (XCS), the Ultimate XMM eXtragaLactic survey project (XXL), and the Local Cluster Substructure Survey (LoCuSS). xga measured values for temperature are, on average, within 1 per cent of the values reported in the literature for each sample. xga gas masses for XXL clusters are shown to be ${\sim }$10 per cent lower than previous measurements (though the difference is only significant at the $\sim 1.8\sigma$ level), LoCuSS $R_{2500}$ and $R_{500}$ gas mass re-measurements are 3 per cent and 7 per cent lower, respectively (representing 1.5$\sigma$ and 3.5$\sigma$ differences). Like-for-like comparisons of hydrostatic mass are made to LoCuSS results, which show that our measurements are $10{\pm }3~{{\rm per\ cent}}$ ($19{\pm }7~{{\rm per\ cent}}$) higher for $R_{2500}$ ($R_{500}$). The comparison between $R_{500}$ masses shows significant scatter. Finally, we present new $M_{\rm hydro}$ measurements for 104 clusters from the Sloan Digital Sky Survey (SDSS) DR8 redMaPPer XCS sample (SDSSRM-XCS). Our SDSSRM-XCS hydrostatic mass measurements are in good agreement with multiple literature estimates, and represent one of the largest samples of consistently measured hydrostatic masses. We have demonstrated that xga is a powerful tool for X-ray analysis of clusters; it will render complex-to-measure X-ray properties accessible to non-specialists.

Turner, D. J. (ORCID:0000000196581396)↗

DOE OSTI2018

The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample: anisotropic clustering analysis in configuration space

We explore the cosmological implications of anisotropic clustering measurements of the quasar sample from Data Release 14 (DR14) of the Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey (eBOSS) in configuration space. The similar to 147000 quasar sample observed by eBOSS offers a direct tracer of the density field and bridges the gap of previous baryon acoustic oscillation measurements between redshift 0.8 < z < 2.2. By analysing the two-point correlation function characterized by clustering wedges xi(wi)(s) and multipolesi xi(l)(S), we measure the angular diameter distance, Hubble parameter, and cosmic structure growth rate. We define a systematic error budget for our measurements based on the analysis of N-body simulations and mock catalogues. Based on the DR14 large-scale structure quasar sample at the effective redshift z(eff) = 1.52, we find the growth rate of cosmic structure f sigma(8)(z(eff)) = 0.396 +/- 0.079, and the geometric parameters Dv(z)/r(d) = 26.47 +/- 1.23, and F-AP(Z) = 2.53 +/- 0.22, where the uncertainties include both statistical and systematic errors. These values are in excellent agreement with the best-fitting standard A cold dark matter model to the latest cosmic microwave background data from Planck.

cosmology↗

DOE OSTI2017

Targeted quantification of functional enzyme dynamics in environmental samples for microbially mediated biogeochemical processes: Targeted quantification of functional enzyme dynamics

Microbially mediated biogeochemical processes are catalyzed by enzymes that control the transformation of carbon, nitrogen, and other elements in environment. The dynamic linkage between enzymes and biogeochemical species transformation has, however, rarely been investigated because of the lack of analytical approaches to efficiently and reliably quantify enzymes and their dynamics in soils and sediments. Herein, we developed a signature peptide-based technique for sensitively quantifying dissimilatory and assimilatory enzymes using nitrate-reducing enzymes in a hyporheic zone sediment as an example. Moreover, the measured changes in enzyme concentration were found to correlate with the nitrate reduction rate in a way different from that inferred from biogeochemical models based on biomass or functional genes as surrogates for functional enzymes. This phenomenon has important implications for understanding and modeling the dynamics of microbial community functions and biogeochemical processes in environments. Our results also demonstrate the importance of enzyme quantification for the identification and interrogation of those biogeochemical processes with low metabolite concentrations as a result of faster enzyme-catalyzed consumption of metabolites than their production. The dynamic enzyme behaviors provide a basis for the development of enzyme-based models to describe the relationship between the microbial community and biogeochemical processes.

Li, Minjing↗

DOE OSTI2014

Calibration of tip and sample temperature of a scanning tunneling microscope using a superconductive sample

The temperature of the electrodes is a crucial parameter in virtually all tunneling experiments. The temperature not only controls the thermodynamic state of the electrodes but also causes thermal broadening, which limits the energy resolution. Unfortunately, the construction of many scanning tunneling microscopes inherits a weak thermal link between tip and sample in order to make one side movable. Such, the temperature of that electrode is badly defined. Here, the authors present a procedure to calibrate the tip temperature by very simple means. The authors use a superconducting sample (Nb) and a standard tip made from W. Due to the asymmetry in the density of states of the superconductor (SC)—normal metal (NM) tunneling junction, the SC temperature controls predominantly the density of states while the NM controls the thermal smearing. By numerically simulating the I-V curves and numerically optimizing the tip temperature and the SC gap width, the tip temperature can be accurately deduced if the sample temperature is known or measureable. In our case, the temperature dependence of the SC gap may serve as a temperature sensor, leading to an accurate NM temperature even if the SC temperature is unknown.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2012

Sample Results from the Integrated Salt Disposition Program Macrobatch 5 Tank 21H Qualification Samples

Savannah River National Laboratory (SRNL) analyzed samples from Tank 21H in support of qualification of Macrobatch (Salt Batch) 5 for the Integrated Salt Disposition Project (ISDP). This document reports partial results of the analyses of samples of Tank 21H. No issues with the projected Salt Batch 5 strategy are identified. Results of the analyses of the Tank 21H samples from this report in conjunction with the findings of the previous report, indicates that the material does not display any unusual characteristics.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2013

Solvent Hold Tank Sample Results for Mcu-12-488, Mcu-12-489, Mcu-12-490, Mcu-12-491, Mcu-12-492 And Mcu-12-493: Quarterly Sample from October 2012

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2013

Solvent Hold Tank Sample Results for MCU-13-143, MCU-13-144, MCU-13-145, MCU-13-146, MCU-13-147 AND MCU-13-148: Quarterly Sample from January 2013

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DOE OSTI2013

C-104 Solid Phase Characterization of Sample 4C-13-1 From Tank 241-C-104 Closure Sampling Event

One solid grab sample from closure sampling in Riser 7 of tank 214-C-I04 (C-I04) was examined to determine the solid phases that were present. The sample was analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The purpose of this analysis was to see if the presence of hydrated phases could provide a possible explanation for the high moisture content obtained from thermogravimetric analysis (TGA).

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2013

Sample Results From The Interim Salt Disposition Program Macrobatch 7 Tank 21H Qualification Samples

Savannah River National Laboratory (SRNL) analyzed samples from Tank 21H in support of qualification of Macrobatch (Salt Batch) 7 for the Interim Salt Disposition Program (ISDP). An ARP and several ESS tests were also performed. This document reports characterization data on the samples of Tank 21H as well as simulated performance of ARP/MCU. No issues with the projected Salt Batch 7 strategy are identified, other than the presence of visible quantities of dark colored solids. A demonstration of the monosodium titanate (0.2 g/L) removal of strontium and actinides provided acceptable 4 hour average decontamination factors for Pu and Sr of 3.22 and 18.4, respectively. The Four ESS tests also showed acceptable behavior with distribution ratios (D(Cs)) values of 15.96, 57.1, 58.6, and 65.6 for the MCU, cold blend, hot blend, and Next Generation Solvent (NGS), respectively. The predicted value for the MCU solvent was 13.2. Currently, there are no models that would allow a prediction of extraction behavior for the other three solvents. SRNL recommends that a model for predicting extraction behavior for cesium removal for the blended solvent and NGS be developed. While no outstanding issues were noted, the presence of solids in the samples should be investigated in future work. It is possible that the solids may represent a potential reservoir of material (such as potassium) that could have an impact on MCU performance if they were to dissolve back into the feed solution. This salt batch is intended to be the first batch to be processed through MCU entirely using the new NGS-MCU solvent.

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DOE OSTI2013

Solvent Hold Tank Sample Results For MCU-13-814, MCU-13-815, MCU-13-816, MCU-13,817, MCU-13-818 And MCU-13-819: Quarterly Sample From May 2013

Savannah River National Laboratory (SRNL) analyzed solvent samples from Modular Caustic-Side Solvent Extraction Unit (MCU) in support of continuing operations. A quarterly analysis of the solvent is required to maintain solvent composition within specifications. Analytical results of the analyses of Solvent Hold Tank (SHT) samples MCU-13-814, MCU-13-815, MCU-13-816, MCU-13-817, MCU-13-818 and MCU-13-819 received May 28, 2013 are reported. The results show that the solvent at MCU does not require an Isopar® L addition, but it will require addition of trioctylamine despite of the 272 g of TOA that was added to the solvent on June 5, 2013 based on the solvent containing a TOA level of 45% of nominal. A new TOA analysis method (HCl titration) has been used and its output was statistically similar to the results from the SVOA-TOA method. This method provides an independent method for measuring TOA and TiDG in MCU-NG solvent. An impurity containing a tert-butyl group was detected in the solvent and further analytical analysis is needed to identify it. SRNL recommends determining the impact of this impurity on the mass transfer ability of the solvent. SRNL also analyzed the SHT sample for 137 Cs content and determined the measured value is above the results observed from the January 2013.

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DOE OSTI2014

Solvent Hold Tank Sample Results for MCU-14-135/136 and MCU-14-214/215/216: February and March 2014 Monthly Samples

SRNL received two sets of SHT samples (MCU-14-135-136 in February 2014 and MCU-14-214-216 in March 2014) for analysis. The samples were analyzed for composition. As with the previous solvent sample results, these analyses indicate that the solvent does not require Isopar ® L trimming at this time. However, the addition of TiDG (suppressor) to the blended solvent is recommended. Evidence of possible (slight) isomerization of the solvent, probably Isopar ® L or TiDG degradation products, was observed.

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DOE OSTI2014

SOLVENT HOLD TANK SAMPLE RESULTS FOR MCU-14-667-672 AND MCU-14-846-847: AUGUST AND SEPTEMBER 2014 MONTHLY SAMPLES

SRNL received two sets of SHT samples (MCU-14-667-672, pulled 8/27/2014 and MCU-14-846-847, pulled on 9/22/2014) for analysis. The samples were analyzed for composition. It is recommended that the solvent receives Isopar® L and TiDG trimming at this time. Analysis of sample MCU-14-846-847 indicates the solvent has evaporated Isopar®L and has lost TiDG to a level below the recommended minimum 1 mM level. Since the addition of MaxCalix to the SHT in early July 2014, the MaxCalix concentration in the solvent has reached nominal values. The laboratory will continue to monitor the quality of the solvent in particular for any new impurity or degradation of the solvent components.

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DOE OSTI2015

Solvent hold tank sample results for MCU-14-1172-1173: December 2014 monthly sample

SRNL received one set of SHT samples (MCU-14-1172-1173 pulled on 12/30/2014) for analysis. The samples were combined and analyzed for composition. Analysis of the composite sample MCU-14-1172- 1173 indicated low concentrations of the suppressor (TiDG), of the extractant (MaxCalix), and of the modifier (CS-7SB) in the solvent relative to their nominal values. This analysis confirms a downward trend of these components. No impurities were found in this solvent. The laboratory will continue to monitor the quality of the solvent in particular for any new impurity or degradation of the solvent components.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2015

Solvent Hold Tank Sample Results for MCU-15-129-130-131: January 2015 Monthly Sample

SRNL received one set of Solvent Hold Tank (SHT) samples (MCU-15-129, MCU-15-130, and MCU-15-131), pulled on 01/25/2015 for analysis. The samples were combined and analyzed for composition. Analysis of the composite sample MCU-15-129-130-131 indicated low concentrations of the suppressor (TiDG), of the extractant (MaxCalix), and of the modifier (CS-7SB) in the solvent relative to their nominal values. This analysis confirms a downward trend of these components. No impurities were found in this solvent. The laboratory will continue to monitor the quality of the solvent in particular for any new impurity or degradation of the solvent components.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2017

Solvent hold tank sample results for MCU-16-1317-1318-1319. September 2016 monthly sample

Savannah River National Laboratory (SRNL) received one set of Solvent Hold Tank (SHT) samples (MCU-16-1317-1318-1319), pulled on 09/12/2016 for analysis. The samples were combined and analyzed for composition. Analysis of the composite sample MCU-16-1317-1318-1319 indicated the Isopar™L concentration is above its nominal level (102%). The extractant (MaxCalix) and the modifier (CS-7SB) are 5% and 10 % below their nominal concentrations. The suppressor (TiDG) is 77% below its nominal concentration. A summary of the concentration of the relevant solvent components is shown below. This analysis confirms the Isopar™ addition to the solvent in August. This analysis also indicates the solvent may require the addition of TiDG, and possibly of modifier to restore them to nominal levels.

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