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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

STRUCTURAL TRANSITION IN THE NGC 6251 JET: AN INTERPLAY WITH THE SUPERMASSIVE BLACK HOLE AND ITS HOST GALAXY

The structure of the NGC 6251 jet on the milliarcsecond scale is investigated using images taken with the European VLBI Network and the Very Long Baseline Array. We detect a structural transition of the jet from a parabolic to a conical shape at a distance of (1–2) × 10{sup 5} times the Schwarzschild radius from the central engine, which is close to the sphere of gravitational influence of the supermassive black hole (SMBH). We also examine the jet pressure profiles with the synchrotron minimum energy assumption to discuss the physical origin of the structural transition. The NGC 6251 jet, together with the M87 jet, suggests a fundamental process of structural transition in the jets of active galactic nuclei (AGNs). Collimated AGN jets are characterized by their external galactic medium, showing that AGN jets interplay with the SMBH and its host galaxy.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

Detection of anomalous reactor activity using antineutrino count evolution over the course of a reactor cycle

This paper analyzes the sensitivity of antineutrino count rate measurements to changes in the fissile content of civil power reactors. Such measurements may be useful in IAEA reactor safeguards applications. We introduce a hypothesis testing procedure to identify statistically significant differences between the antineutrino count rate evolution of a standard 'baseline' fuel cycle and that of an anomalous cycle, in which plutonium is removed and replaced with an equivalent fissile worth of uranium. The test would allow an inspector to detect anomalous reactor activity, or to positively confirm that the reactor is operating in a manner consistent with its declared fuel inventory and power level. We show that with a reasonable choice of detector parameters, the test can detect replacement of 82 kg of plutonium in 90 days with 95% probability, while controlling the false positive rate at 5%. We show that some improvement on this level of sensitivity may be obtained by various means, including use of the method in conjunction with existing reactor safeguards methods. We also identify a necessary and sufficient minimum daily antineutrino count rate and a maximum tolerable background rate to achieve the quoted sensitivity, and list examples of detectors in which such rates have been attained.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2014

WE-G-BRF-09: Force- and Image-Adaptive Strategies for Robotised Placement of 4D Ultrasound Probes

Purpose: To allow continuous acquisition of high quality 4D ultrasound images for non-invasive live tracking of tumours for IGRT, image- and force-adaptive strategies for robotised placement of 4D ultrasound probes are developed and evaluated. Methods: The developed robotised ultrasound system is based on a 6-axes industrial robot (adept Viper s850) carrying a 4D ultrasound transducer with a mounted force-torque sensor. The force-adaptive placement strategies include probe position control using artificial potential fields and contact pressure regulation by a PD controller strategy. The basis for live target tracking is a continuous minimum contact pressure to ensure good image quality and high patient comfort. This contact pressure can be significantly disturbed by respiratory movements and has to be compensated. All measurements were performed on human subjects under realistic conditions. When performing cardiac ultrasound, rib- and lung shadows are a common source of interference and can disrupt the tracking. To ensure continuous tracking, these artefacts had to be detected to automatically realign the probe. The detection is realised by multiple algorithms based on entropy calculations as well as a determination of the image quality. Results: Through active contact pressure regulation it was possible to reduce the variance of the contact pressure by 89.79% despite respiratory motion of the chest. The results regarding the image processing clearly demonstrate the feasibility to detect image artefacts like rib shadows in real-time. Conclusion: In all cases, it was possible to stabilise the image quality by active contact pressure control and automatically detected image artefacts. This fact enables the possibility to compensate for such interferences by realigning the probe and thus continuously optimising the ultrasound images. This is a huge step towards fully automated transducer positioning and opens the possibility for stable target tracking in ultrasoundguided radiation therapy requiring contact pressure of 5–10 N. This work was supported by the Graduate School for Computing in Medicine and Life Sciences funded by Germany's Excellence Initiative [DFG GSC 235/1].

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Constraints on the emission region of 3C 279 during strong flares in 2014 and 2015 through VHE γ -ray observations with H.E.S.S.

The flat spectrum radio quasar 3C 279 is known to exhibit pronounced variability in the high-energy (100 MeV < E < 100 GeV) γ-ray band, which is continuously monitored with Fermi-LAT. During two periods of high activity in April 2014 and June 2015 target-of-opportunity observations were undertaken with the High Energy Stereoscopic System (H.E.S.S.) in the very-high-energy (VHE, E> 100 GeV) γ-ray domain. While the observation in 2014 provides an upper limit, the observation in 2015 results in a signal with 8.7σ significance above an energy threshold of 66 GeV. No VHE variability was detected during the 2015 observations. The VHE photon spectrum is soft and described by a power-law index of 4.2 ± 0.3. The H.E.S.S. data along with a detailed and contemporaneous multiwavelength data set provide constraints on the physical parameters of the emission region. The minimum distance of the emission region from the central black hole was estimated using two plausible geometries of the broad-line region and three potential intrinsic spectra. The emission region is confidently placed at r≳1.7 × 10 17 cm from the black hole, that is beyond the assumed distance of the broad-line region. Time-dependent leptonic and lepto-hadronic one-zone models were used to describe the evolution of the 2015 flare. In conclusion, neither model can fully reproduce the observations, despite testing various parameter sets. Furthermore, the H.E.S.S. data were used to derive constraints on Lorentz invariance violation given the large redshift of 3C 279.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Search for Exoplanets around Northern Circumpolar Stars. II. The Detection of Radial Velocity Variations in M Giant Stars HD 36384, HD 52030, and HD 208742

We present the detection of long-period RV variations in HD 36384, HD 52030, and HD 208742 by using the high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) for the precise radial velocity (RV) survey of about 200 northern circumpolar stars. Analyses of RV data, chromospheric activity indicators, and bisector variations spanning about five years suggest that the RV variations are compatible with planet or brown dwarf companions in Keplerian motion. However, HD 36384 shows photometric variations with a period very close to that of RV variations as well as amplitude variations in the weighted wavelet Z-transform (WWZ) analysis, which argues that the RV variations in HD 36384 are from the stellar pulsations. Assuming that the companion hypothesis is correct, HD 52030 hosts a companion with minimum mass 13.3 M {sub Jup} orbiting in 484 days at a distance of 1.2 au. HD 208742 hosts a companion of 14.0 M {sub Jup} at 1.5 au with a period of 602 days. All stars are located at the asymptotic giant branch (AGB) stage on the H–R diagram after undergoing the helium flash and leaving the giant clump.With stellar radii of 53.0 R {sub ⊙} and 57.2 R {sub ⊙} for HD 52030 and HD 208742, respectively, these stars may be the largest yet, in terms of stellar radius, found to host substellar companions. However, given possible RV amplitude variations and the fact that these are highly evolved stars, the planet hypothesis is not yet certain.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

The ultraviolet-bright, slowly declining transient PS1-11af as a partial tidal disruption event

We present the Pan-STARRS1 discovery of the long-lived and blue transient PS1-11af, which was also detected by Galaxy Evolution Explorer with coordinated observations in the near-ultraviolet (NUV) band. PS1-11af is associated with the nucleus of an early type galaxy at redshift z = 0.4046 that exhibits no evidence for star formation or active galactic nucleus activity. Four epochs of spectroscopy reveal a pair of transient broad absorption features in the UV on otherwise featureless spectra. Despite the superficial similarity of these features to P-Cygni absorptions of supernovae (SNe), we conclude that PS1-11af is not consistent with the properties of known types of SNe. Blackbody fits to the spectral energy distribution are inconsistent with the cooling, expanding ejecta of a SN, and the velocities of the absorption features are too high to represent material in homologous expansion near a SN photosphere. However, the constant blue colors and slow evolution of the luminosity are similar to previous optically selected tidal disruption events (TDEs). The shape of the optical light curve is consistent with models for TDEs, but the minimum accreted mass necessary to power the observed luminosity is only ∼0.002 M {sub ☉}, which points to a partial disruption model. A full disruption model predicts higher bolometric luminosities, which would require most of the radiation to be emitted in a separate component at high energies where we lack observations. In addition, the observed temperature is lower than that predicted by pure accretion disk models for TDEs and requires reprocessing to a constant, lower temperature. Three deep non-detections in the radio with the Very Large Array over the first two years after the event set strict limits on the production of any relativistic outflow comparable to Swift J1644+57, even if off-axis.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

X-Ray Superflares on CC Eri

We present an in-depth study of two superflares (F1 and F2) detected on an active binary star CC Eridani by the Swift observatory. These superflares triggered the Burst Alert Telescope (BAT) in the hard X-ray band on 2008 October 16 and 2012 February 24. The rise phases of both the flares were observed only with BAT, whereas the decay phases were observed simultaneously with the X-ray Telescope. It has been found that the flares decay faster in the hard X-ray band than in the soft X-ray band. Both flares F1 and F2 are highly energetic with respective peak X-ray luminosities of ∼10{sup 32.2} and ∼10{sup 31.8} erg s{sup −1} in 0.3–50 keV energy band, which are larger than any other flares previously observed on CC Eri. The time-resolved spectral analysis during the flares shows the variation in the coronal temperature, emission measure, and abundances. The elemental abundances are enhanced by a factor of ∼8 to the minimum observed in the post-flare phase for the flare F1. The observed peak temperatures in these two flares are found to be 174 and 128 MK. Using the hydrodynamic loop modeling, we derive loop lengths for both the flares as 1.2 ± 0.1 × 10{sup 10} cm and 2.2 ± 0.6 × 10{sup 10} cm, respectively. The Fe Kα emission at 6.4 keV is also detected in the X-ray spectra and we model the Kα emission feature as fluorescence from the hot flare source irradiating the photospheric iron. These superflares are the brightest, hottest, and shortest in duration observed thus far on CC Eri.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Feasibility study of prompt gamma neutron activation for NDT measurement of moisture in stone and brick

The conservation of stone and brick architecture or sculpture often involves damage caused by moisture. The feasibility of a NDT method based on prompt gamma neutron activation (PGNA) for measuring the element hydrogen as an indication of water is being evaluated. This includes systematic characterization of the lithology and physical properties of seven building stones and one brick type used in the buildings of the Smithsonian Institution in Washington, D.C. To determine the required dynamic range of the NDT method, moisture-related properties were measured by standard methods. Cold neutron PGNA was also used to determine chemically bound water (CBW) content. The CBW does not damage porous masonry, but creates an H background that defines the minimum level of detection of damaging moisture. The CBW was on the order of 0.5% for all the stones. This rules out the measurement of hygric processes in all of the stones and hydric processed for the stones with fine scale pore-size distributions The upper bound of moisture content, set by porosity through water immersion, was on the order of 5%. The dynamic range is about 10–20. The H count rates were roughly 1–3 cps. Taking into account differences in neutron energies and fluxes and sample volume between cold PGNA and a portable PGNA instrument, it appears that it is feasible to apply PGNA in the field.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

HAT-P-31b,c: A TRANSITING, ECCENTRIC, HOT JUPITER AND A LONG-PERIOD, MASSIVE THIRD BODY

We report the discovery of HAT-P-31b, a transiting exoplanet orbiting the V = 11.660 dwarf star GSC 2099-00908. HAT-P-31b is the first planet discovered with the Hungarian-made Automated Telescope (HAT) without any follow-up photometry, demonstrating the feasibility of a new mode of operation for the HATNet project. The 2.17 M{sub J} , 1.1 R{sub J} planet has a period of P{sub b} = 5.0054 days and maintains an unusually high eccentricity of e{sub b} = 0.2450 {+-} 0.0045, determined through Keck, FIbr-fed Echelle Spectrograph, and Subaru high-precision radial velocities (RVs). Detailed modeling of the RVs indicates an additional quadratic residual trend in the data detected to very high confidence. We interpret this trend as a long-period outer companion, HAT-P-31c, of minimum mass 3.4 M{sub J} and period {>=}2.8 years. Since current RVs span less than half an orbital period, we are unable to determine the properties of HAT-P-31c to high confidence. However, dynamical simulations of two possible configurations show that orbital stability is to be expected. Further, if HAT-P-31c has non-zero eccentricity, our simulations show that the eccentricity of HAT-P-31b is actively driven by the presence of c, making HAT-P-31 a potentially intriguing dynamical laboratory.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

The NASA-UC-UH Eta-Earth program. IV. A low-mass planet orbiting an M dwarf 3.6 PC from Earth

We report the discovery of a low-mass planet orbiting Gl 15 A based on radial velocities from the Eta-Earth Survey using HIRES at Keck Observatory. Gl 15 Ab is a planet with minimum mass Msin i = 5.35 ± 0.75 M {sub ⊕}, orbital period P = 11.4433 ± 0.0016 days, and an orbit that is consistent with circular. We characterize the host star using a variety of techniques. Photometric observations at Fairborn Observatory show no evidence for rotational modulation of spots at the orbital period to a limit of ∼0.1 mmag, thus supporting the existence of the planet. We detect a second RV signal with a period of 44 days that we attribute to rotational modulation of stellar surface features, as confirmed by optical photometry and the Ca II H and K activity indicator. Using infrared spectroscopy from Palomar-TripleSpec, we measure an M2 V spectral type and a sub-solar metallicity ([M/H] = –0.22, [Fe/H] = –0.32). We measure a stellar radius of 0.3863 ± 0.0021 R {sub ☉} based on interferometry from CHARA.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2010

Marine Corps Base Camp Lejeune Green Loss time series Zipcode

Critical military training and testing on lands along the nation’s coastal and estuarine shorelines are increasingly placed at risk because of development pressures in surrounding areas, impairments due to other anthropogenic disturbances, and increasing requirements for compliance with environmental regulations. The U.S. Department of Defense (DoD) intends to enhance and sustain its training and testing assets and to optimize its stewardship of natural resources through the development and application of an ecosystem-based management approach on DoD installations. To accomplish this goal, particularly for installations in estuarine/coastal environments, the Strategic Environmental Research and Development Program (SERDP) launched the Defense Coastal/Estuarine Research Program (DCERP) as a minimum 10-year effort at Marine Corps Base Camp Lejeune (MCBCL) in North Carolina. The results of the first six years of the program (DCERP1) are presented here.The overarching objectives of DCERP are to: (1) understand the effects of military training activities, infrastructure development, and other coastal military installations; (2) develop models, tools, and indicators to evaluate ecosystem health; and (3) recommend adaptive management strategies to sustain ecosystem natural resources within the context of an active military installation.Green Loss time series 'Zipcode' Input files are 5 pixel minimum area, MCBCL only data from the individual green loss change periods. These were converted from categories of intensity 2,3,4 to simple binary 'change' and 'no-change'. These files were then converted to the following: 84-90 loss: 0,1 84-98 loss: 0,10 84-05 loss: 0,100 84-07 loss: 0,1000 84-09 loss: 0,10000 Files then simply added together to create change time series. This results in a range of possible values from 11111 (loss detected during each time period) to 00001 (change in the 1984-1990 period, but not observed as green loss by 1998, 05,07 or 09 - probably a temporary impact that 'revegetated').

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2010

Marine Corps Base Camp Lejeune Green Gain time series Zipcode

Critical military training and testing on lands along the nation’s coastal and estuarine shorelines are increasingly placed at risk because of development pressures in surrounding areas, impairments due to other anthropogenic disturbances, and increasing requirements for compliance with environmental regulations. The U.S. Department of Defense (DoD) intends to enhance and sustain its training and testing assets and to optimize its stewardship of natural resources through the development and application of an ecosystem-based management approach on DoD installations. To accomplish this goal, particularly for installations in estuarine/coastal environments, the Strategic Environmental Research and Development Program (SERDP) launched the Defense Coastal/Estuarine Research Program (DCERP) as a minimum 10-year effort at Marine Corps Base Camp Lejeune (MCBCL) in North Carolina. The results of the first six years of the program (DCERP1) are presented here.The overarching objectives of DCERP are to: (1) understand the effects of military training activities, infrastructure development, and other coastal military installations; (2) develop models, tools, and indicators to evaluate ecosystem health; and (3) recommend adaptive management strategies to sustain ecosystem natural resources within the context of an active military installation.Green Gain time series 'Zipcode' Input files are 5 pixel minimum area, MCBCL only data from the individual green loss change periods. These were converted from categories of intensity 2,3,4 to simple binary 'change' and 'no-change'. These files were then converted to the following: 84-90 loss: 0,1 84-98 loss: 0,10 84-05 loss: 0,100 84-07 loss: 0,1000 84-09 loss: 0,10000 Files then simply added together to create change time series. This results in a range of possible values from 11111 (loss detected during each time period) to 00001 (change in the 1984-1990 period, but not observed as green loss by 1998, 05,07 or 09 - probably a temporary impact that 'revegetated').

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Assessment of Tritium Activities in Bailed versus Pumped Samples from Wells at the Nevada National Security Site

The Underground Test Area (UGTA) Activity uses a variety of methods to collect groundwater samples to identify radionuclide migration from underground nuclear tests. These include depth-discrete bailing, pumping with low-volume rod pumps, and pumping with electrical submersible pumps. The Nevada National Security Site (NNSS) Integrated Groundwater Sampling Plan specifies that when sampling with a pump, a minimum of three effective well volumes are withdrawn and then samples are collected after water-quality parameters have stabilized. In locations where pumping is not feasible, depth-discrete bailing is used and purging prior to sampling is usually not required. A recent study evaluated three sampling technologies and recommended that historical tritium results be evaluated where both pumped and bailed samples are available to identify preferred sampling protocols for the collection of tritium samples. The tritium ( 3 H) activities were obtained from the UGTA chemistry data base. Wells were identified with known 3 H activities above method detection limits, and then evaluated if both bailed and pumped samples had been collected. Twenty two wells and piezometers with bailed samples, pumped samples, and 3 H activities above background were identified for further consideration. The conclusions from this analysis are: Bailed samples collected for 3 H analysis near the water surface in a well are lower in 3 H activity than bailed samples from within screened intervals and pumped samples. Depth-discrete bailed samples from within the screened intervals are generally in good agreement with pumped samples from developed wells and piezometers. Depth-discrete bailed samples from undeveloped wells and piezometers are in good agreement with the first pumped samples. However, the next pumped samples increased in 3 H activity, resulting in a greater percent difference between the undeveloped bailed samples and later pumped samples. Continuous pumping over extended periods removing large purge volumes from wells can perturbate the surrounding groundwater system for long periods of time. These perturbations can cause large changes in 3 H activities in the aquifer near the well because of the mixing of groundwater with variable 3 H activities. Recommendations include: Bailed samples for 3 H should not be collected near the water surface in the well. Bailed samples should be collected from within the well screen. Logs of temperature, chemistry, and thermal flow should be evaluated to identify optimal depths within the well screen to collect depth-discrete bailer samples. Purging of large volumes of water from the well over extended periods of time should be avoided when collecting 3 H samples. Sufficient time should be allowed after pumping large volumes of water from the well (e.g., after well development) for the surrounding aquifer and 3 H activities to return to ambient conditions

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

EMIC waves and associated relativistic electron precipitation on 25-26 January 2013

Using measurements from the Van Allen Probes and the Balloon Array for RBSP Relativistic Electron Losses (BARREL), we perform a case study of electromagnetic ion cyclotron (EMIC) waves and associated relativistic electron precipitation (REP) observed on 25–26 January 2013. Among all the EMIC wave and REP events from the two missions, the pair of the events is the closest both in space and time. The Van Allen Probe-B detected significant EMIC waves at L = 2.1–3.9 and magnetic local time (MLT) = 21.0–23.4 for 53.5 min from 2353:00 UT, 25 January 2013. Meanwhile, BARREL-1T observed clear precipitation of relativistic electrons at L = 4.2–4.3 and MLT = 20.7–20.8 for 10.0 min from 2358 UT, 25 January 2013. Local plasma and field conditions for the excitation of the EMIC waves, wave properties, electron minimum resonant energy E min , and electron pitch angle diffusion coefficient D αα of a sample EMIC wave packet are examined along with solar wind plasma and interplanetary magnetic field parameters, geomagnetic activity, and results from the spectral analysis of the BARREL balloon observations to investigate the two types of events. The events occurred in the early main phase of a moderate storm (min. Dst* = -51.0 nT). The EMIC wave event consists of two parts. Finally, unlike the first part, the second part of the EMIC wave event was locally generated and still in its source region. It is found that the REP event is likely associated with the EMIC wave event.

58 GEOSCIENCES↗
DOE OSTI2011

STRUCTURE AND DYNAMICS OF THE 2010 JULY 11 ECLIPSE WHITE-LIGHT CORONA

The white-light corona (WLC) during the total solar eclipse on 2010 July 11 was observed by several teams in the Moon's shadow stretching across the Pacific Ocean and a number of isolated islands. We present a comparison of the WLC as observed by eclipse teams located on the Tatakoto Atoll in French Polynesia and on Easter Island, 83 minutes later, combined with near-simultaneous space observations. The eclipse was observed at the beginning of the solar cycle, not long after solar minimum. Nevertheless, the solar corona shows a plethora of different features (coronal holes, helmet streamers, polar rays, very faint loops and radial-oriented thin streamers, a coronal mass ejection, and a puzzling 'curtain-like' object above the north pole). Comparing the observations from the two sites enables us to detect some dynamic phenomena. The eclipse observations are further compared with a hairy-ball model of the magnetic field and near-simultaneous images from the Atmospheric Imaging Assembly on NASA's Solar Dynamics Observatory, the Extreme Ultraviolet Imager on NASA's Solar Terrestrial Relations Observatory, the Sun Watcher, using Active Pixel System Detector and Image Processing on ESA's PRoject for Onboard Autonomy, and the Naval Research Laboratory's Large Angle and Spectrometric Coronagraph on ESA's Solar and Heliospheric Observatory. The Ludendorff flattening coefficient is 0.156, matching the expected ellipticity of coronal isophotes at 2 Rs{sub un}, for this rising phase of the solar-activity cycle.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

A PLANETARY SYSTEM AROUND THE NEARBY M DWARF GJ 667C WITH AT LEAST ONE SUPER-EARTH IN ITS HABITABLE ZONE

We re-analyze 4 years of HARPS spectra of the nearby M1.5 dwarf GJ 667C available through the European Southern Observatory public archive. The new radial velocity (RV) measurements were obtained using a new data analysis technique that derives the Doppler measurement and other instrumental effects using a least-squares approach. Combining these new 143 measurements with 41 additional RVs from the Magellan/Planet Finder Spectrograph and Keck/High Resolution Echelle Spectrometer spectrometers reveals three additional signals beyond the previously reported 7.2 day candidate, with periods of 28 days, 75 days, and a secular trend consistent with the presence of a gas giant (period {approx}10 years). The 28 day signal implies a planet candidate with a minimum mass of 4.5 M{sub Circled-Plus} orbiting well within the canonical definition of the star's liquid water habitable zone (HZ), that is, the region around the star at which an Earth-like planet could sustain liquid water on its surface. Still, the ultimate water supporting capability of this candidate depends on properties that are unknown such as its albedo, atmospheric composition, and interior dynamics. The 75 day signal is less certain, being significantly affected by aliasing interactions among a potential 91 day signal, and the likely rotation period of the star at 105 days detected in two activity indices. GJ 667C is the common proper motion companion to the GJ 667AB binary, which is metal-poor compared to the Sun. The presence of a super-Earth in the HZ of a metal-poor M dwarf in a triple star system supports the evidence that such worlds should be ubiquitous in the Galaxy.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

SU-F-J-07: Evaluating the Adequacy of Biopsy Specimens for Genetic Signature Assessment by Measuring the Metabolic Activity in Specimens Obtained Under 18F-FDG PET/CT Guidance

Purpose: Genetic profiling of biopsied tissue is the basis for personalized cancer therapy. However biopsied materials may not contain sufficient amounts of DNA needed for analysis. We propose a method to determine the adequacy of specimens for performing genetic profiling by quantifying metabolic activity. Methods: We measured the response of two radiation detectors to the activity contained in the minimum amount of tumor cells needed for genetic profiling in biopsy specimens obtained under 2-deoxy-2-({sup 18}F)fluoro-D-glucose ({sup 18}F-FDG) PET/CT guidance. The expected tumor cell concentration in biopsy specimens was evaluated from the amount of DNA needed (∼100 µg) and the number of pathology sections typically used for the analysis. The average {sup 18}F-FDG uptake per cell was measured by incubating KPC-4662 pancreatic tumor cells and HT-29 colorectal adenocarcinoma tumor cells in {sup 18}F-FDG containing solution (activity concentrations between 0.0122 and 1.51 MBq/mL and glucose concentrations of 3.1 and 1 g/L) for 1 to 1.75 hours and then measuring the activity of a known number of cells. Measurements of surrogate specimens obtained using 18G needle biopsies of gels containing these cells in expected concentrations (∼10{sup 4} µL{sup −1}) were performed using an autoradiography CCD based device (up to 20 min exposure) and a scintillation well counter (∼1 min measurements) about 3 and 5 hours after the end of incubation respectively. Results: At start of autoradiography there were between 0.16 and 1.5 {sup 18}F-FDG molecules/cell and between 1.14 and 5.43×10{sup 7} {sup 18}F-FDG molecules/mL. For the scintillation well counter, sample to minimum-detectable-count rate ratios were greater than 7 and the counting error was less than 25% for ≤80 s measurement times. Images of the samples were identifiable on the autoradiograph for ∼10 min and longer exposure times. Conclusion: Scintillation well counter measurements and CCD based autoradiography have adequate sensitivity to detect the tumor burden needed for genetic profiling in 18G core needle biopsies. Supported in part through the NIH/NCI Cancer Center Support Grant P30 CA008748 and by a sponsored research agreement with Biospace Lab S.A.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Potential Activities and Long Lifetimes of Organic Carbon-Degrading Extracellular Enzymes in Deep Subsurface Sediments of the Baltic Sea

Heterotrophic microorganisms in marine sediments produce extracellular enzymes to hydrolyze organic macromolecules, so their products can be transported inside the cell and used for energy and growth. Therefore, extracellular enzymes may mediate the fate of organic carbon in sediments. The Baltic Sea Basin is a primarily depositional environment with high potential for organic matter preservation. The potential activities of multiple organic carbon-degrading enzymes were measured in samples obtained by the International Ocean Discovery Program Expedition 347 from the Little Belt Strait, Denmark, core M0059C. Potential maximum hydrolysis rates (V max ) were measured at depths down to 77.9mbsf for the following enzymes: alkaline phosphatase, β- d -xylosidase, β- d -cellobiohydrolase, N-acetyl-β- d -glucosaminidase, β-glucosidase, α-glucosidase, leucyl aminopeptidase, arginyl aminopeptidase, prolyl aminopeptidase, gingipain, and clostripain. Extracellular peptidase activities were detectable at depths shallower than 54.95mbsf, and alkaline phosphatase activity was detectable throughout the core, albeit against a relatively high activity in autoclaved sediments. β-glucosidase activities were detected above 30mbsf; however, activities of other glycosyl hydrolases (β-xylosidase, β-cellobiohydrolase, N-acetyl-β-glucosaminidase, and α-glucosidase) were generally indistinguishable from zero at all depths. These extracellular enzymes appear to be extremely stable: Among all enzymes, a median of 51.3% of enzyme activity was retained after autoclaving for an hour. We show that enzyme turnover times scale with the inverse of community metabolic rates, such that enzyme lifetimes in subsurface sediments, in which metabolic rates are very slow, are likely to be extraordinarily long. A back-of-the-envelope calculation suggests enzyme lifetimes are, at minimum, on the order of 230days, and may be substantially longer. These results lend empirical support to the hypothesis that a population of subsurface microbes persist by using extracellular enzymes to slowly metabolize old, highly degraded organic carbon.

54 ENVIRONMENTAL SCIENCES↗