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At least 1,567 records · Page 87
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Functional and transcriptional characterization of complex neuronal co-cultures

Brain-on-a-chip systems are designed to simulate brain activity using traditional in vitro cell culture on an engineered platform. It is a noninvasive tool to screen new drugs, evaluate toxicants, and elucidate disease mechanisms. However, successful recapitulation of brain function on these systems is dependent on the complexity of the cell culture. In this study, we increased cellular complexity of traditional (simple) neuronal cultures by co-culturing with astrocytes and oligodendrocyte precursor cells (complex culture). We evaluated and compared neuronal activity (e.g., network formation and maturation), cellular composition in long-term culture, and the transcriptome of the two cultures. Compared to simple cultures, neurons from complex co-cultures exhibited earlier synapse and network development and maturation, which was supported by localized synaptophysin expression, up-regulation of genes involved in mature neuronal processes, and synchronized neural network activity. Also, mature oligodendrocytes and reactive astrocytes were only detected in complex cultures upon transcriptomic analysis of age-matched cultures. Functionally, the GABA antagonist bicuculline had a greater influence on bursting activity in complex versus simple cultures. Collectively, the cellular complexity of brain-on-a-chip systems intrinsically develops cell type-specific phenotypes relevant to the brain while accelerating the maturation of neuronal networks, important features underdeveloped in traditional cultures.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Discovery of Contamination Spread at the Plutonium Finishing Plant during Demolition Activities

Between December 14 and December 18, 2017, contamination was detected outside of the Contamination Area (CA) at the Plutonium Finishing Plant (PFP) demolition zone, including around the PFP offices and on multiple vehicles located outside the radiological boundary. The consequences of this event were personnel exposure and potential radiological contamination leaving the Hanford Site. The scope of this causal analysis is focused at the events leading up to and including the contamination spread outside the PFP CA and development of the corrective actions to prevent recurrence. Specific methods to be used upon resumption of demolition activities are under development at the time that this report is approved and will be fully vetted by the DOE-RL and the DOE Expert Panel. It should also be noted that studies of radiological emissions from Hanford are part of the routine National Emission Standards for Hazardous Air Pollutants Compliance Monitoring (NESHAPS) Program and are not addressed in this report.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Conformational rearrangement of the NMDA receptor amino-terminal domain during activation and allosteric modulation

N-Methyl-D-aspartate receptors (NMDARs) are ionotropic glutamate receptors essential for synaptic plasticity and memory. Receptor activation involves glycine- and glutamate-stabilized closure of the GluN1 and GluN2 subunit ligand binding domains that is allosterically regulated by the amino-terminal domain (ATD). Using single molecule fluorescence resonance energy transfer (smFRET) to monitor subunit rearrangements in real-time, we observe a stable ATD inter-dimer distance in the Apo state and test the effects of agonists and antagonists. We find that GluN1 and GluN2 have distinct gating functions. Glutamate binding to GluN2 subunits elicits two identical, sequential steps of ATD dimer separation. Glycine binding to GluN1 has no detectable effect, but unlocks the receptor for activation so that glycine and glutamate together drive an altered activation trajectory that is consistent with ATD dimer separation and rotation. We find that protons exert allosteric inhibition by suppressing the glutamate-driven ATD separation steps, and that greater ATD separation translates into greater rotation and higher open probability.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRSDate not supplied

On-Orbit Performance of the NOAA-21 Advanced Technology Microwave Sounder (ATMS)

The Advanced Technology Microwave Sounder (ATMS) instrument provides sounding measurements of Earth’s atmosphere to collect temperature and water vapor data for NOAA’s Joint Polar Satellite System (JPSS) program. ATMS is a total-power passive microwave radiometer with 22 channels spanning a frequency range from 22 to 183 GHz. A general description of the ATMS instrument is detailed in [1]. Three ATMS units are currently on-orbit. The Suomi National Polar-orbiting Partnership (SNPP) unit was launched in 2011 and the NOAA-20 (previously JPSS-1) unit was launch in 2017. Both SNPP and NOAA-20 ATMS units are currently operational and the data is used for numerical weather prediction (NWP) models. The NOAA-21 (formerly JPSS-2) ATMS unit was launched on November 10, 2022 from Vandenberg Space Force Base in California [2]. The ATMS instrument began generating radiance data on November 21, 2022. At the time of this abstract NOAA-21 ATMS is currently completing on-orbit commissioning and checkout activities; it is expected that the commissioning activities will be complete by the IGARSS 2023 conference. This paper will focus on the on-orbit performance of the NOAA-21 ATMS instrument based on measurements and activities from the commissioning period. Comparisons will be made to specifications and to expected performance based on pre-launch test activities. Pre-launch JPSS-2 (NOAA-21) ATMS performance is detailed in [4]. Additionally, the NOAA-21 performance will be compared to the on-orbit performance of the SNPP and NOAA-21 ATMS units. The post-launch performance of SNPP ATMS is detailed in [1][5][6][7]. The post-launch performance of NOAA-20 ATMS is detailed in [5][7][8]. On-orbit performance is evaluated through data collects from nominal mission operations as well as specific post-launch tests and spacecraft maneuvers. Nominal mission operations can be used to evaluate parameters such as instrument thermal stability, Noise Equivalent Delta Temperature (NEDT)/radiometric sensitivity, geolocation, inter-channel noise correlation, striping, and radiometric bias and stability. Shortly after instrument activation, the instrument thermal stability as measured from onboard temperature sensors is evaluated to demonstrate stable and steady-state behavior. Methods for computing NEDT are described in [9][10][11]. Passive geolocation measurements are performed using the coastline inflection point (CIP) method, described in [8][12]. The striping index, used as a metric to quantify striping, is the ratio of along-track variance to cross-track variance of the observed brightness temperature [4][8][14]. Inter-channel noise correlation has been previously reported for SNPP and NOAA-20 [1][8]. Dedicated post-launch tests and spacecraft maneuvers are utilized during the commissioning phase for further evaluation of on-orbit instrument performance. These activities provide information on the optimal space view selection, noise power spectral density (PSD), gain stability, scan bias, interference from onboard transmitters, reflector emissivity, active geolocation, and radiometric bias and stability detection methods. The optimal space view selection is used to determine which of ATMS space view sectors is preferred for minimizing contamination of the space view [1]. Point and stare testing is used to generate noise PSD and gain stability information, as described in [1][8]. Spacecraft roll and pitch maneuvers allow the ATMS to view different zones, including deep space, and the data can be used to provide information on scan biases and antenna sidelobe contamination [1][8]. The pitch maneuver can also be used to assess interference from onboard Ka-band transmitters and reflector emissivity [8]. Active geolocation is evaluated as a method for geolocation, described in [15].

Edward Kim↗
DOE OSTI2020

The influence of environmental microseismicity on detection and interpretation of small-magnitude events in a polar glacier setting

Glacial environments exhibit temporally variable microseismicity. To investigate how microseismicity influences event detection, we implement two noise-adaptive digital power detectors to process seismic data from Taylor Glacier, Antarctica. We add scaled icequake waveforms to the original data stream, run detectors on the hybrid data stream to estimate reliable detection magnitudes and compare analytical magnitudes predicted from an ice crack source model. We find that detection capability is influenced by environmental microseismicity for seismic events with source size comparable to thermal penetration depths. When event counts and minimum detectable event sizes change in the same direction (i.e. increase in event counts and minimum detectable event size), we interpret measured seismicity changes as ‘true’ seismicity changes rather than as changes in detection. Generally, one detector (two degree of freedom (2dof)) outperforms the other: it identifies more events, a more prominent summertime diurnal signal and maintains a higher detection capability. We conclude that real physical processes are responsible for the summertime diurnal inter-detector difference. One detector (3dof) identifies this process as environmental microseismicity; the other detector (2dof) identifies it as elevated waveform activity. Our analysis provides an example for minimizing detection biases and estimating source sizes when interpreting temporal seismicity patterns to better infer glacial seismogenic processes.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Radio variability survey of very low luminosity protostars

Ten very low luminosity objects were observed multiple times in the 8.5 GHz continuum in search of protostellar magnetic activities. A radio outburst of IRAM 04191+1522 IRS was detected, and the variability timescale was about 20 days or shorter. The results of this survey and archival observations suggest that IRAM 04191+1522 IRS is in active states about half the time. Archival data show that L1014 IRS and L1148 IRS were detectable previously and suggest that at least 20%-30% of very low luminosity protostars are radio variables. Considering the variability timescale and flux level of IRAM 04191+1522 IRS and the previous detection of the circular polarization of L1014 IRS, the radio outbursts of these protostars are probably caused by magnetic flares. However, IRAM 04191+1522 IRS is too young and small to develop an internal convective dynamo. If the detected radio emission is indeed coming from magnetic flares, the discovery implies that the flares may be caused by the fossil magnetic fields of interstellar origin.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

MAGNETICALLY DRIVEN ACCRETION DISK WINDS AND ULTRA-FAST OUTFLOWS IN PG 1211+143

We present a study of X-ray ionization of MHD accretion-disk winds in an effort to constrain the physics underlying the highly ionized ultra-fast outflows (UFOs) inferred by X-ray absorbers often detected in various sub classes of Seyfert active galactic nuclei (AGNs). Our primary focus is to show that magnetically driven outflows are indeed physically plausible candidates for the observed outflows accounting for the AGN absorption properties of the present X-ray spectroscopic observations. Employing a stratified MHD wind launched across the entire AGN accretion disk, we calculate its X-ray ionization and the ensuing X-ray absorption-line spectra. Assuming an appropriate ionizing AGN spectrum, we apply our MHD winds to model the absorption features in an XMM-Newton/EPIC spectrum of the narrow-line Seyfert, PG 1211+143. We find, through identifying the detected features with Fe Kα transitions, that the absorber has a characteristic ionization parameter of log (ξ{sub c}[erg cm s{sup −1}]) ≃ 5–6 and a column density on the order of N{sub H} ≃ 10{sup 23} cm{sup −2} outflowing at a characteristic velocity of v{sub c}/c ≃ 0.1–0.2 (where c is the speed of light). The best-fit model favors its radial location at r{sub c} ≃ 200 R{sub o} (R{sub o} is the black hole’s innermost stable circular orbit), with an inner wind truncation radius at R{sub t} ≃ 30 R{sub o}. The overall K-shell feature in the data is suggested to be dominated by Fe xxv with very little contribution from Fe xxvi and weakly ionized iron, which is in good agreement with a series of earlier analyses of the UFOs in various AGNs, including PG 1211+143.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

STAT3 signaling pathway is necessary for cell survival and tumorsphere forming capacity in ALDH{sup +}/CD133{sup +} stem cell-like human colon cancer cells

Highlights: Black-Right-Pointing-Pointer The phosphorylated or activated form of STAT3 was expressed in colon cancer stem-like cells. Black-Right-Pointing-Pointer STAT3 inhibitor, FLLL32 inhibits P-STAT3 and STAT3 target genes in colon cancer stem-like cells. Black-Right-Pointing-Pointer Inhibition of STAT3 resulted in decreased cell viability and reduced numbers of tumorspheres. Black-Right-Pointing-Pointer STAT3 is required for survival and tumorsphere forming capacity in colon cancer stem-like cells. Black-Right-Pointing-Pointer Targeting STAT3 in cancer stem-like cells may offer a novel treatment approach for colon cancer. -- Abstract: Persistent activation of Signal Transducers and Activators of Transcription 3 (STAT3) is frequently detected in colon cancer. Increasing evidence suggests the existence of a small population of colon cancer stem or cancer-initiating cells may be responsible for tumor initiation, metastasis, and resistance to chemotherapy and radiation. Whether STAT3 plays a role in colon cancer-initiating cells and the effect of STAT3 inhibition is still unknown. Flow cytometry was used to isolate colon cancer stem-like cells from three independent human colon cancer cell lines characterized by both aldehyde dehydrogenase (ALDH)-positive and CD133-positive subpopulation (ALDH{sup +}/CD133{sup +}). The effects of STAT3 inhibition in colon cancer stem-like cells were examined. The phosphorylated or activated form of STAT3 was expressed in colon cancer stem-like cells and was reduced by a STAT3-selective small molecular inhibitor, FLLL32. FLLL32 also inhibited the expression of potential STAT3 downstream target genes in colon cancer stem-like cells including survivin, Bcl-XL, as well as Notch-1, -3, and -4, which may be involved in stem cell function. Furthermore, FLLL32 inhibited cell viability and tumorsphere formation as well as induced cleaved caspase-3 in colon cancer stem-like cells. FLLL32 is more potent than curcumin as evidenced with lower IC50 in colon cancer stem-like cells. In summary, our results indicate that STAT3 is a novel therapeutic target in colon cancer stem-like cells and inhibition of STAT3 in cancer stem-like cells may offer a potential treatment for colorectal cancer.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Detection of Chymotrypsin by Optical and Acoustic Methods

Chymotrypsin is an important proteolytic enzyme in the human digestive system that cleaves milk proteins through the hydrolysis reaction, making it an interesting subject to study the activity of milk proteases. In this work, we compared detection of chymotrypsin by spectrophotometric dynamic light scattering (DLS) and quartz crystal microbalance (QCM) methods and determined the limit of chymotrypsin detection (LOD), 0.15 ± 0.01 nM for spectrophotometric, 0.67 ± 0.05 nM for DLS and 1.40 ± 0.30 nM for QCM methods, respectively. The sensors are relatively cheap and are able to detect chymotrypsin in 3035 min. While the optical detection methods are simple to implement, the QCM method is more robust for sample preparation, and allows detection of chymotrypsin in non-transparent samples. We give an overview on methods and instruments for detection of chymotrypsin and other milk proteases.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2014

Applicability of rat precision-cut lung slices in evaluating nanomaterial cytotoxicity, apoptosis, oxidative stress, and inflammation

The applicability of rat precision-cut lung slices (PCLuS) in detecting nanomaterial (NM) toxicity to the respiratory tract was investigated evaluating sixteen OECD reference NMs (TiO{sub 2}, ZnO, CeO{sub 2}, SiO{sub 2}, Ag, multi-walled carbon nanotubes (MWCNTs)). Upon 24-hour test substance exposure, the PCLuS system was able to detect early events of NM toxicity: total protein, reduction in mitochondrial activity, caspase-3/-7 activation, glutathione depletion/increase, cytokine induction, and histopathological evaluation. Ion shedding NMS (ZnO and Ag) induced severe tissue destruction detected by the loss of total protein. Two anatase TiO{sub 2} NMs, CeO{sub 2} NMs, and two MWCNT caused significant (determined by trend analysis) cytotoxicity in the WST-1 assay. At non-cytotoxic concentrations, different TiO{sub 2} NMs and one MWCNT increased GSH levels, presumably a defense response to reactive oxygen species, and these substances further induced a variety of cytokines. One of the SiO{sub 2} NMs increased caspase-3/-7 activities at non-cytotoxic levels, and one rutile TiO{sub 2} only induced cytokines. Investigating these effects is, however, not sufficient to predict apical effects found in vivo. Reproducibility of test substance measurements was not fully satisfactory, especially in the GSH and cytokine assays. Effects were frequently observed in negative controls pointing to tissue slice vulnerability even though prepared and handled with utmost care. Comparisons of the effects observed in the PCLuS to in vivo effects reveal some concordances for the metal oxide NMs, but less so for the MWCNT. The highest effective dosages, however, exceeded those reported for rat short-term inhalation studies. To become applicable for NM testing, the PCLuS system requires test protocol optimization. - Highlights: • 16 OECD reference nanomaterials were tested in rat precision-cut lung slices. • Nanomaterial cytotoxicity, apoptose, oxidative stress, and inflammation were detected. • Investigating these early effects is not sufficient to predict in vivo outcome. • Reproducibility was not fully satisfactory in the glutathione and cytokine assays. • Further work is required to adjust effective dosages in vitro to in vivo doses.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

SPATIALLY RESOLVED HCN ABSORPTION FEATURES IN THE CIRCUMNUCLEAR REGION OF NGC 1052

We present the first VLBI detection of HCN molecular absorption in the nearby active galactic nucleus NGC 1052. Utilizing the 1 mas resolution achieved by the Korean VLBI Network, we have spatially resolved the HCN absorption against a double-sided nuclear jet structure. Two velocity features of HCN absorption are detected significantly at the radial velocity of 1656 and 1719 km s{sup −1}, redshifted by 149 and 212 km s{sup −1} with respect to the systemic velocity of the galaxy. The column density of the HCN molecule is estimated to be 10{sup 15}–10{sup 16} cm{sup −2}, assuming an excitation temperature of 100–230 K. The absorption features show high optical depth localized on the receding jet side, where the free–free absorption occurred due to the circumnuclear torus. The size of the foreground absorbing molecular gas is estimated to be on approximately one-parsec scales, which agrees well with the approximate size of the circumnuclear torus. HCN absorbing gas is likely to be several clumps smaller than 0.1 pc inside the circumnuclear torus. The redshifted velocities of the HCN absorption features imply that HCN absorbing gas traces ongoing infall motion inside the circumnuclear torus onto the central engine.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Direct observation of binding stress-induced crystalline orientation change in piezoelectric plate sensors

We have examined the mechanism of the detection resonance frequency shift, Δf/f, of a 1370 μm long and 537 μm wide [Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}]{sub 0.65}[PbTiO{sub 3}]{sub 0.35} (PMN-PT) piezoelectric plate sensor (PEPS) made of a 8-μm thick PMN-PT freestanding film. The Δf/f of the PEPS was monitored in a three-step binding model detections of (1) binding of maleimide-activated biotin to the sulfhydryl on the PEPS surface followed by (2) binding of streptavidin to the bound biotin and (3) subsequent binding of biotinylated probe deoxyribonucleic acid to the bound streptavidin. We used a PMN-PT surrogate made of the same 8-μm thick PMN-PT freestanding film that the PEPS was made of but was about 1 cm in length and width to carry out crystalline orientation study using X-ray diffraction (XRD) scan around the (002)/(200) peaks after each of the binding steps. The result of the XRD studies indicated that each binding step caused the crystalline orientation of the PMN-PT thin layer to switch from the vertical (002) orientation to the horizontal (200) orientation, and most of the PEPS detection Δf/f was due to the change in the lateral Young's modulus of the PMN-PT thin layer as a result of the crystalline orientation change.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

{sup 90}Y -PET imaging: Exploring limitations and accuracy under conditions of low counts and high random fraction

Purpose: {sup 90}Y -positron emission tomography (PET) imaging is becoming a recognized modality for postinfusion quantitative assessment following radioembolization therapy. However, the extremely low counts and high random fraction associated with {sup 90}Y -PET may significantly impair both qualitative and quantitative results. The aim of this work was to study image quality and noise level in relation to the quantification and bias performance of two types of Siemens PET scanners when imaging {sup 90}Y and to compare experimental results with clinical data from two types of commercially available {sup 90}Y microspheres. Methods: Data were acquired on both Siemens Biograph TruePoint [non-time-of-flight (TOF)] and Biograph microcomputed tomography (mCT) (TOF) PET/CT scanners. The study was conducted in three phases. The first aimed to assess quantification and bias for different reconstruction methods according to random fraction and number of true counts in the scan. The NEMA 1994 PET phantom was filled with water with one cylindrical insert left empty (air) and the other filled with a solution of {sup 90}Y . The phantom was scanned for 60 min in the PET/CT scanner every one or two days. The second phase used the NEMA 2001 PET phantom to derive noise and image quality metrics. The spheres and the background were filled with a {sup 90}Y solution in an 8:1 contrast ratio and four 30 min acquisitions were performed over a one week period. Finally, 32 patient data (8 treated with Therasphere{sup ®} and 24 with SIR-Spheres{sup ®}) were retrospectively reconstructed and activity in the whole field of view and the liver was compared to theoretical injected activity. Results: The contribution of both bremsstrahlung and LSO trues was found to be negligible, allowing data to be decay corrected to obtain correct quantification. In general, the recovered activity for all reconstruction methods was stable over the range studied, with a small bias appearing at extremely high random fraction and low counts for iterative algorithms. Point spread function (PSF) correction and TOF reconstruction in general reduce background variability and noise and increase recovered concentration. Results for patient data indicated a good correlation between the expected and PET reconstructed activities. A linear relationship between the expected and the measured activities in the organ of interest was observed for all reconstruction method used: a linearity coefficient of 0.89 ± 0.05 for the Biograph mCT and 0.81 ± 0.05 for the Biograph TruePoint. Conclusions: Due to the low counts and high random fraction, accurate image quantification of {sup 90}Y during selective internal radionuclide therapy is affected by random coincidence estimation, scatter correction, and any positivity constraint of the algorithm. Nevertheless, phantom and patient studies showed that the impact of number of true and random coincidences on quantitative results was found to be limited as long as ordinary Poisson ordered subsets expectation maximization reconstruction algorithms with random smoothing are used. Adding PSF correction and TOF information to the reconstruction greatly improves the image quality in terms of bias, variability, noise reduction, and detectability. On the patient studies, the total activity in the field of view is in general accurately measured by Biograph mCT and slightly overestimated by the Biograph TruePoint.

60 APPLIED LIFE SCIENCES↗
NASA NTRS2011

First Detections of the [N II] 122 micron Line at High Redshift: Demonstrating the Utility of the Line for Studying Galaxies in the Early Universe

We report the first detections of the [N II] 122 micron line from a high-redshift galaxy. The line was strongly (>6(sigma)) detected from SMMJ02399-0136, and H1413 + 117 (the Cloverleaf QSO) using the Redshift (zeta) and Early Universe Spectrometer on the Caltech Submillimeter Observatory. The lines from both sources are quite bright with line to far-infrared (FIR) continuum luminosity ratios that are approx.7.0 x 10(exp -4) (Cloverleaf) and 2.1 x 10(exo -3) (SMMJ02399). With ratios 2-10 times larger than the average value for nearby galaxies, neither source exhibits the line to continuum deficits seen in nearby sources. The line strengths also indicate large ionized gas fractions, approx.8%-17% of the molecUlar gas mass. The [O III]/[N II] line ratio is very sensitive to the effective temperature of ionizing stars and the ionization parameter for emission arising in the narrow-line region (NLR) of an active galactic nucleus (AGN). Using Our previous detection of the [O III] 88 micron line, the [O III]/[N II]line ratio for SMMJ02399-0136 indicates that the dominant source of the line emission is either stellar H II regions ionized by O9.5 stars, or the NLR of the AGN with ionization parameter log(U) = -3.3 to -4.0. A composite system, where 30%-50% of the FIR lines arise in the NLR also matches the data. The Cloverleaf is best modeled by a superposition of approx.200 M82-like starbursts accounting for all of the FIR emission and 43% of the [N II]line. The remainder may come from the NLR. This war!< demonstrates the utility of the [N II] and [O III] lines in constraining properties of the ionized medium.

Ferkinhoff, Carl↗
DOE OSTI2011

FIRST DETECTIONS OF THE [N II] 122 {mu}m LINE AT HIGH REDSHIFT: DEMONSTRATING THE UTILITY OF THE LINE FOR STUDYING GALAXIES IN THE EARLY UNIVERSE

We report the first detections of the [N II] 122 {mu}m line from a high-redshift galaxy. The line was strongly (>6{sigma}) detected from SMMJ02399-0136, and H1413+117 (the Cloverleaf QSO) using the Redshift (z) and Early Universe Spectrometer on the Caltech Submillimeter Observatory. The lines from both sources are quite bright with line to far-infrared (FIR) continuum luminosity ratios that are {approx}7.0 x 10{sup -4} (Cloverleaf) and 2.1 x 10{sup -3} (SMMJ02399). With ratios 2-10 times larger than the average value for nearby galaxies, neither source exhibits the line-to-continuum deficits seen in nearby sources. The line strengths also indicate large ionized gas fractions, {approx}8%-17% of the molecular gas mass. The [O III]/[N II] line ratio is very sensitive to the effective temperature of ionizing stars and the ionization parameter for emission arising in the narrow-line region (NLR) of an active galactic nucleus (AGN). Using our previous detection of the [O III] 88 {mu}m line, the [O III]/[N II] line ratio for SMMJ02399-0136 indicates that the dominant source of the line emission is either stellar H II regions ionized by O9.5 stars, or the NLR of the AGN with ionization parameter log(U) = -3.3 to -4.0. A composite system, where 30%-50% of the FIR lines arise in the NLR also matches the data. The Cloverleaf is best modeled by a superposition of {approx}200 M82-like starbursts accounting for all of the FIR emission and 43% of the [N II] line. The remainder may come from the NLR. This work demonstrates the utility of the [N II] and [O III] lines in constraining properties of the ionized medium.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Detection of oxygen species generated by WO{sub 3} modification fullerene/TiO{sub 2} in the degradation of 1,5-diphenyl carbazide

Highlights: • Reactive oxygen species were detected through oxidation reaction from DPCI to DPCO. • Generated reactive oxygen species and hydroxyl radicals can be analysed by DPCI degradation. • C{sub 60} have good effect in photo/ultrasonic degradation process. • Enhanced adsorption capacity can increase the degradation effect. • Photocatalytic activity attributed to photo-absorption effect by C{sub 60} and cooperative effect of WO{sub 3} and TiO{sub 2}. - Abstract: In the present work, powders with different relative mole ratios of WO{sub 3}-fullerene/TiO{sub 2} were irradiated by visible light and ultrasonic. The composite obtained was characterized by BET surface area measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), fourier transform infrared (FT-IR), transmission electron microscopy (TEM) and UV–vis analysis. A methylene blue (MB) solution under visible light and ultrasonic irradiation was used to determine the catalytic activity. The generation of reactive oxygen species were detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). Finally, we performed experiments to find the optimum relative mole ratio of fullerene for the degradation of MB.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Study of the effect of the stress on CdTe nuclear detectors

CdTe detectors are commonly used for X and γ ray applications. The performance of these detectors is strongly affected by different types of mechanical stress; such as that caused by differential expansion between the semiconductor and its intimate metallic contacts and that caused by applied pressure during the bonding process. The aim of this work was to study the effects of stress on the performance of CdTe detectors. A difference in expansion coefficients induces transverse stress under the metallic contact, while contact pressure induces longitudinal stress. These stresses have been simulated by applying known static pressures. For the longitudinal case, the pressure was applied directly to the metallic contact; while in the transverse case, it was applied to the side. We have studied the effect of longitudinal and transverse stresses on the electrical characteristics including leakage current measurements and γ-ray detection performance. We have also investigated induced defects, their nature, activation energies, cross sections, and concentrations under the applied stress by using photo-induced current transient spectroscopy and thermoelectric effect spectroscopy techniques. The operational stress limit is also given.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Multi-parametric approach towards the assessment of radon and thoron progeny exposures

Conventionally, the dosimetry is carried out using radon and thoron gas concentration measurements and doses have been assigned using assumed equilibrium factors for the progeny species, which is inadequate pertaining to the variations in equilibrium factors and possibly due to significant thoron. In fact, since the true exposures depend upon the intricate mechanisms of progeny deposition in the lung, therefore an integrated approach for the assessment of progeny is essential. In this context, the recently developed deposition based progeny concentration measurement techniques (DTPS: Direct Thoron progeny sensors and DRPS: Direct Radon progeny sensors) appear to be best suited for radiological risk assessments both among occupational workers and general study populations. DTPS and DRPS consist of aluminized mylar mounted LR115 type passive detectors, which essentially detects the alpha particles emitted from the deposited progeny atoms on the detector surface. It gives direct measure of progeny activity concentrations in air. DTPS has a lower limit of detection limit of 0.1 Bq/m{sup 3} whereas that for DRPS is 1 Bq/m{sup 3}, hence are perfectly suitable for indoor environments. These DTPS and DRPS can be capped with 200-mesh type wire-screen to measure the coarse fraction of the progeny concentration and the corresponding coarse fraction deposition velocities as well as the time integrated fine fraction. DTPS and DRPS can also be lodged in an integrated sampler wherein the wire-mesh and filter-paper are arranged in an array in flow-mode, to measure the fine and coarse fraction concentration separately and simultaneously. The details are further discussed in the paper.

61 RADIATION PROTECTION AND DOSIMETRY↗