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At least 1,693 records · Page 94
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Characterization of zein assemblies by ultra-small-angle X-ray scattering

Zein, a protein of corn, has an amphiphilic molecule capable of self-assembly into distinctly different structures. In this work, ultra-small-angle X-ray scattering (USAXS) was applied to investigate the formation of self-assembled zein structures in binary solvent systems of ethanol and water. Our study included observing structural changes due to aging. Three hierarchical structures were identified in zein-solvent systems, molecular zein 2D films, believed to be formed by zein rods assembled first into one-dimensional fibers and then into two-dimensional films, and 3D spherical aggregates. Aging did not change the size or shape of primary units, but promoted their self-assembly into intermediate 2D structures and shaped 3D structures into well19 defined spheres. We found that the rheological parameters, consistency index (K) and behavior index (n), storage and loss moduli (G’ and G”) were also measured. K and n, changed markedly with aging, from nearly Newtonian low consistency fresh samples to highly viscous pseudoplastic aged samples. G’ and G” increased with aging for all samples reflecting increased interactions among zein self-assembled structures. Furthermore, viscoelastic parameters indicated that zein dispersions formed gels upon aging. It was observed that USAX reported on molecular scale self-assembly processes, while rheological measurements reported on the macroscale interaction between self-assembled particles. Raman spectra suggested that α-helix to β-sheet transformations prompted zein self-assembly, which influenced the size and morphology of molecular assemblies and ultimately the rheological properties of zein dispersions.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Machine learning-assisted profiling of a kinked ladder polymer structure using scattering

Ladder polymers consisting of fused rings in the backbone have very limited conformational freedom, which results in very different properties from traditional linear polymers. However, accurately determining their size and chain conformations from solution scattering remains a challenge. Their chain conformations of kinked ladder polymers are largely governed by the structures and relative orientations or configurations of the repeat units, unlike conventional polymer chains whose bending angles between repeat units follow a unimodal Gaussian distribution. Meanwhile, traditional scattering models for polymer chains do not account for these unique structural features. This work introduces a novel approach that integrates machine learning with Monte Carlo simulations to construct a model that can describe the geometry of a type of kinked CANAL ladder polymers. We first develop a Monte Carlo simulation model for sampling the configuration space of CANAL ladder polymers, where each repeat unit is modeled as a biaxial segment. Then, we establish a machine learning-assisted scattering analysis framework based on Gaussian Process Regression. Finally, we conduct small-angle neutron scattering experiments on a CANAL ladder polymer solution to apply our approach. Our method uncovers structural features of such ladder polymers that conventional methods fail to capture.

Ding, Lijie [Oak Ridge National Laboratory (ORNL),↗
DOE OSTI2012

THE MISSING CAVITIES IN THE SEEDS POLARIZED SCATTERED LIGHT IMAGES OF TRANSITIONAL PROTOPLANETARY DISKS: A GENERIC DISK MODEL

Transitional circumstellar disks around young stellar objects have a distinctive infrared deficit around 10 {mu}m in their spectral energy distributions, recently measured by the Spitzer Infrared Spectrograph (IRS), suggesting dust depletion in the inner regions. These disks have been confirmed to have giant central cavities by imaging of the submillimeter continuum emission using the Submillimeter Array (SMA). However, the polarized near-infrared scattered light images for most objects in a systematic IRS/SMA cross sample, obtained by HiCIAO on the Subaru telescope, show no evidence for the cavity, in clear contrast with SMA and Spitzer observations. Radiative transfer modeling indicates that many of these scattered light images are consistent with a smooth spatial distribution for {mu}m-sized grains, with little discontinuity in the surface density of the {mu}m-sized grains at the cavity edge. Here we present a generic disk model that can simultaneously account for the general features in IRS, SMA, and Subaru observations. Particularly, the scattered light images for this model are computed, which agree with the general trend seen in Subaru data. Decoupling between the spatial distributions of the {mu}m-sized dust and mm-sized dust inside the cavity is suggested by the model, which, if confirmed, necessitates a mechanism, such as dust filtration, for differentiating the small and big dust in the cavity clearing process. Our model also suggests an inwardly increasing gas-to-dust ratio in the inner disk, and different spatial distributions for the small dust inside and outside the cavity, echoing the predictions in grain coagulation and growth models.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Dynamical mean field theory simulations with the adaptive sampling configuration interaction method

In the pursuit of accurate descriptions of strongly correlated quantum many-body systems, dynamical mean field theory (DMFT) has been an invaluable tool for elucidating the spectral properties and quantum phases of both phenomenological models and ab initio descriptions of real materials. Key to the DMFT process is the self-consistent map of the original system into an Anderson impurity model, the ground state of which is computed using an impurity solver. The power of the method is thus limited by the complexity of the impurity model the solver can handle. Simulating realistic systems generally requires many correlated sites. By adapting the recently proposed adaptive sampling configuration interaction (ASCI) method as an impurity solver, we enable much more efficient zero-temperature DMFT simulations. The key feature of the ASCI method is that it selects only the most relevant Hilbert space degrees of freedom to describe the ground state. This reduces the numerical complexity of the calculation, which will allow us to pursue future DMFT simulations with more correlated impurity sites than in previous works. Here, we present the ASCI-DMFT method and example calculations on the one- and two-dimensional Hubbard models that exemplify its efficient convergence and timing properties. We show that the ASCI approach is several orders of magnitude faster than the current best published ground-state DMFT simulations, which allows us to study the bath discretization error in simulations with small clusters, as well as to address cluster sizes beyond the current state of the art. Finally, our approach can also be adapted for other embedding methods such as density matrix embedding theory and self-energy embedding theory.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Robust Predictive Control for Modular Solid-State Transformer With Reduced DC Link and Parameter Mismatch

This paper presents the analysis and implementation of a predictive control method for dc-link regulation and voltage balance in a cascaded modular reduced dc-link solid-state transformer (SST). Passive components like bulky dc links limit the power density of power converters, especially medium-voltage (MV) SST. Reduced dc-link or low-inertia converters can dramatically reduce the size, cost, and weight by tolerating larger dc-link ripples and improve the reliability with electrolytic capacitor-less dc link. However, a small dc link leads to tight coupling between the input and the output stages, which is a challenge for control design. In stacked low-inertia converters (SLIC), the low-inertia converter modules are stacked for MV applications, resulting in coupling between the modules and making the control more challenging. A new model predictive control method which can achieve deadbeat regulation on the dc link without weighting factors has been proposed to address this novel problem. This paper focuses on analyzing the condition of the low-inertia dc link up to 80% ripple, the robustness of the control under parameter mismatches, high-order terms, and important implementation issues such as model-based sampling and computation delay compensation. Significantly, the high-order terms are introduced because of the large dc-link ripple. These high-order terms are unique to the SLIC and negligible in conventional high-inertia converters. A discrete-time large-signal model is built to capture the dc-link’s nonlinear dynamics, and the eigenvalues of a small-signal Jacobian matrix are analyzed with Floquet theory to evaluate stability, using the modular soft-switching solid-state transformer (M-S4T) as an example of the SLIC. Simulation and experimental results of an MVDC M-S4T verify the analysis and the predictive control method. Finally, the general application of the predictive control to low-inertia converters is compared against a conventional PI controller using a reduced dc-link active-front-end (AFE) rectifier as an example.

14 SOLAR ENERGY↗
DOE OSTI2017

Application of the SHARP Toolkit to Sodium-Cooled Fast Reactor Challenge Problems

The Simulation-based High-efficiency Advanced Reactor Prototyping (SHARP) toolkit is under development by the Nuclear Energy Advanced Modeling and Simulation (NEAMS) Campaign of the U.S. Department of Energy, Office of Nuclear Energy. To better understand and exploit the benefits of advanced modeling simulations, the NEAMS Campaign initiated the “Sodium-Cooled Fast Reactor (SFR) Challenge Problems” task, which include the assessment of hot channel factors (HCFs) and the demonstration of zooming capability using the SHARP toolkit. If both challenge problems are resolved through advanced modeling and simulation using the SHARP toolkit, the economic competitiveness of a SFR can be significantly improved. The efforts in the first year of this project focused on the development of computational models, meshes, and coupling procedures for multi-physics calculations using the neutronics (PROTEUS) and thermal-hydraulic (Nek5000) components of the SHARP toolkit, as well as demonstration of the HCF calculation capability for the 100 MWe Advanced Fast Reactor (AFR-100) design. Testing the feasibility of the SHARP zooming capability is planned in FY 2018. The HCFs developed for the earlier SFRs (FFTF, CRBR, and EBR-II) were reviewed, and a subset of these were identified as potential candidates for reduction or elimination through high-fidelity simulations. A one-way offline coupling method was used to evaluate the HCFs where the neutronics solver PROTEUS computes the power profile based on an assumed temperature, and the computational fluid dynamics solver Nek5000 evaluates the peak temperatures using the neutronics power profile. If the initial temperature profile used in the neutronics calculation is reasonably accurate, the one-way offline method is valid because the neutronics power profile has weak dependence on small temperature variation. In order to get more precise results, the proper temperature profile for initial neutronics calculations was obtained from the STAR-CCM+ calculations. The HCFs of the peak temperatures at cladding outer surface, cladding inner wall surface, and fuel centerline induced by cladding manufacturing tolerance and uncertainties on the cladding, coolant, and fuel properties were evaluated for the AFR-100. Some assessment on the effect of wire wrap configuration and size of the bundle shows that it is practical to use the 7-pin bare rod bundle to calculate the HCFs. The resulting HCFs obtained from the high-fidelity SHARP calculations are generally smaller than those developed for the earlier SFRs because the most uncertainties involved in the modeling and simulations were disappeared. For completeness, additional investigations are planned in FY 2018, which will use random sampling techniques.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2023

Mechanical behavior analysis using small-size graphite disc compression testing with digital image correlation methods

The ASTM International Standard Test Method for Tensile Stress-Strain of Carbon and Graphite (ASTM C749) requires dog-bone shaped specimens. Unfortunately, specimen sizes required in ASTM C749 are much too large for irradiation within a test reactor and are incompatible with irradiation capsule volumes, molten salt degradation facilities, or oxidation apparatus. The ASTM International Standard Test Method for Tensile Strength Estimate by Disc Compression of Manufactured Graphite (ASTM D8289) was developed as an alternative that provides a means for testing tensile properties using smaller specimens when geometric constraints are present. However, the important stress–strain relation throughout the test loading history that could be recorded using ASTM C749 is lost by using ASTM D8289 because of the difficulties involved with using traditional strain gauges or extensometers on such a small specimen. In this work, a digital image correlation (DIC) method, which uses a full-field noncontact surface displacement measurement technique, was applied along with the ASTM D8289 splitting tensile test on eight small samples of graphite grade Mersen 2114 to track their deformation during compressive loading. Initial results showed that the DIC technique can measure the surface displacement/strain on these small (Ø6 × 3 mm) graphite specimens with high accuracy and good repeatability, indicating that the DIC technique, combined with the small-disc splitting tensile test in ASTM D8289, can capture the strain evolution in the test. In conclusion, further comparison of measured strains with analytical and numerical simulation results provides additional understanding of the mechanical behaviour of this nuclear graphite material in complex stress states.

36 MATERIALS SCIENCE↗
DOE OSTI2018

ZnO polymer composite based visible blind UV photo detector

Highlights: • The spherically shaped ZnO NPs with uniform size (∼40 nm) were synthesized. • Optical and the UV detection properties of polymer composites were measured. • ZnO-PVP sample has the potential as a material for visible blind photo detector. • Dielectric medium perturbs electron-phonon interaction and UV detection mechanism. - Abstract: Spherical ZnO nanoparticles with average diameter ∼50 nm are synthesized by hydrothermal method. Composites of the nanoparticles with different polymers have been prepared and UV detection properties are measured. The dielectric medium perturbs electron-phonon interaction as well as the optoelectronic properties. Moreover, the luminescence properties of the materials effected due to composite formation. In case of NP-polymer composite NPs are capped and there is negligible further adsorption and desorption of O{sub 2} molecules occurred on the surface. This increases the photocurrent as well as photosensitivity. For ZnO based photo detector, there is a small but not negligible photo response near 620 nm. The photo response in this particular wavelength is not observed in case of ZnO-PVP composite and it can be used as visible blind UV detector.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

A 2 TiO 5 (A = Dy, Gd, Er, Yb) at High Pressure

Here, the structural evolution of lanthanide A 2 TiO 5 (A = Dy, Gd, Yb, and Er) at high pressure is investigated using synchrotron X-ray diffraction. The effects of A-site cation size and of the initial structure are systematically examined by varying the composition of the isostructural lanthanide titanates, and the structure of dysprosium titanate polymorphs (orthorhombic, hexagonal and cubic), respectively. All samples undergo irreversible high pressure phase transformations, but with different onset pressures depending on the initial structure. While individual phase exhibits different phase transformation histories, all samples commonly experience a sluggish transformation to a defect cotunnite-like ( Pnma ) phase for a certain pressure range. Orthorhombic Dy 2 TiO 5 and Gd 2 TiO 5 form P2 1 am at pressures below 9 GPa and Pnma above 13 GPa. Pyrochlore-type Dy 2 TiO 5 and Er 2 TiO 5 as well as defect-fluorite-type Yb 2 TiO 5 form Pnma at ~ 21 GPa, followed by Im3¯m . Hexagonal Dy 2 TiO 5 forms Pnma directly, although a small amount of remnants of hexagonal Dy 2 TiO 5 is observed even at the highest pressure (~ 55 GPa) reached, indicating a kinetic limitations in the hexagonal Dy 2 TiO 5 phase transformations at high pressure. Decompression of these materials leads to different metastable phases. Most interestingly, a high pressure cubic X-type phase ( Im3¯m ) is confirmed using highresolution transmission electron microscopy on recovered pyrochlore-type Er 2 TiO 5 . The kinetic constraints on this metastable phase yield a mixture of both the X-type phase and amorphous domains upon pressure release. This is the first observation of an X-type phase for an A 2 BO 5 composition at high pressure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Canister Centerline Cooling Experiments for DPF5-336 Reference Material Made with ERV3b Salt Simulant

This report provides experimental details and results on the elemental distributions (compositions), crystalline/amorphous phase distribution, and microstructures for DPF5-336 reference materials made with ERV3b salt that were subjected to the canister centerline cooling (CCC) heat treatment process. To fabricate these materials, ammonium dihydrogen phosphate was mixed with ERV3b salt simulant and a dechlorination procedure was run in the generation-2 dechlorinator at the Pacific Northwest National Laboratory up to 600°C in an alumina crucible. After the dechlorination process, the product was removed from the crucible, lightly crushed, loaded into a new alumina crucible, Fe 2 O 3 was added, and this was vitrified at 1100°C for 1 hour and quenched. The quenched material was mostly amorphous but showed some small diffraction peaks attributed to Li 3 Fe 2 (PO 4 ) 3 . This quenched material was ground to a fine particle size in a milling chamber, and this was subjected to the CCC cooling profile in duplicate within alumina and fused quartz crucibles. The CCC experiment is designed to simulate the slowest cooling profile (the vertical centerline) of a 0.61-m diameter canister where the slower cooling profile often results in the production of a variety of different crystalline phases upon formation of which result in a residual glass of unknown composition and properties. The information gleaned from these types of experiments will lead to improved composition-property predictions for materials with similar compositions. The results of the alumina and fused quartz experiments show different microstructures but similar diffraction patterns providing evidence of similar crystalline phases being present in each sample. Both samples had monazite [i.e., (Ce,Nd)PO 4 ] and mixtures of phases containing P, Fe, and alkali metal elements. This report completes the milestone M4FT-23PN030104042 with details provided in Appendix B.

36 MATERIALS SCIENCE↗
NASA NTRS2006

Microspheres in Plasma Display Panels

Filling small bubbles of molten glass with gases is just as difficult as it sounds, but the technical staff at NASA is not known to shy away from a difficult task. When Microsphere Systems, Inc. (MSI), of Ypsilanti, Michigan, and Imaging Systems Technology, Inc. (IST), of Toledo, Ohio, were trying to push the limits of plasma displays but were having difficulty with the designs, NASA s Glenn Garrett Morgan Commercialization Initiative (GMCI) assembled key personnel at Glenn Research Center and Ohio State University for a brainstorming session to come up with a solution for the companies. They needed a system that could produce hollow, glass micro-sized spheres (microspheres) that could be filled with a variety of gasses. But the extremely high temperature required to force the micro-sized glass bubbles to form at the tip of a metal nozzle resulted in severe discoloration of the microspheres. After countless experiments on various glass-metal combinations, they had turned to the GMCI for help. NASA experts in advanced metals, ceramics, and glass concluded that a new design approach was necessary. The team determined that what was needed was a phosphate glass composition that would remain transparent, and they went to work on a solution. Six weeks later, using the design tips from the NASA team, Tim Henderson, president of MSI, had designed a new system in which all surfaces in contact with the molten glass would be ceramic instead of metal. Meanwhile, IST was able to complete a Phase I Small Business Innovation Research (SBIR) grant supported by the National Science Foundation (NSF) and supply a potential customer with samples of the microspheres for evaluation as filler materials for high-performance insulations.

Source record↗
NASA NTRS2010

Rapid Active Sampling Package

A field-deployable, battery-powered Rapid Active Sampling Package (RASP), originally designed for sampling strong materials during lunar and planetary missions, shows strong utility for terrestrial geological use. The technology is proving to be simple and effective for sampling and processing materials of strength. Although this originally was intended for planetary and lunar applications, the RASP is very useful as a powered hand tool for geologists and the mining industry to quickly sample and process rocks in the field on Earth. The RASP allows geologists to surgically acquire samples of rock for later laboratory analysis. This tool, roughly the size of a wrench, allows the user to cut away swaths of weathering rinds, revealing pristine rock surfaces for observation and subsequent sampling with the same tool. RASPing deeper (.3.5 cm) exposes single rock strata in-situ. Where a geologist fs hammer can only expose unweathered layers of rock, the RASP can do the same, and then has the added ability to capture and process samples into powder with particle sizes less than 150 microns, making it easier for XRD/XRF (x-ray diffraction/x-ray fluorescence). The tool uses a rotating rasp bit (or two counter-rotating bits) that resides inside or above the catch container. The container has an open slot to allow the bit to extend outside the container and to allow cuttings to enter and be caught. When the slot and rasp bit are in contact with a substrate, the bit is plunged into it in a matter of seconds to reach pristine rock. A user in the field may sample a rock multiple times at multiple depths in minutes, instead of having to cut out huge, heavy rock samples for transport back to a lab for analysis. Because of the speed and accuracy of the RASP, hundreds of samples can be taken in one day. RASP-acquired samples are small and easily carried. A user can characterize more area in less time than by using conventional methods. The field-deployable RASP used a Ni/Cad rechargeable battery. Power usage was less than 1 Wh/ cm3 even when sampling strong basalts, so many samples could be taken on a single battery charge.

Peters, Gregory↗
NASA NTRS2014

The New NASA Orbital Debris Engineering Model ORDEM 3.0

The NASA Orbital Debris Program Office (ODPO) has released its latest Orbital Debris Engineering Model, ORDEM 3.0. It supersedes ORDEM 2000, now referred to as ORDEM 2.0. This newer model encompasses the Earth satellite and debris flux environment from altitudes of low Earth orbit (LEO) through geosynchronous orbit (GEO). Debris sizes of 10 micron through larger than 1 m in non-GEO and 10 cm through larger than 1 m in GEO are available. The inclusive years are 2010 through 2035. The ORDEM model series has always been data driven. ORDEM 3.0 has the benefit of many more hours of data from existing sources and from new sources than past ORDEM versions. The object data range in size from 10 μm to larger than 1 m, and include in situ and remote measurements. The in situ data reveals material characteristics of small particles. Mass densities are grouped in ORDEM 3.0 in terms of 'high-density', represented by 7.9 g/cc, 'medium-density' represented by 2.8 g/cc and 'low-density' represented by 1.4 g/cc. Supporting models have also advanced significantly. The LEO-to-GEO ENvironment Debris model (LEGEND) includes an historical and a future projection component with yearly populations that include launched and maneuvered intact spacecraft and rocket bodies, mission related debris, and explosion and collision event fragments. LEGEND propagates objects with ephemerides and physical characteristics down to 1 mm in size. The full LEGEND yearly population acts as an a priori condition for a Bayesian statistical model. Specific populations are added from sodium potassium droplet releases, recent major accidental and deliberate collisions, and known anomalous debris events. This paper elaborates on the upgrades of this model over previous versions. Sample validation results with remote and in situ measurements are shown, and the consequences of including material density are discussed as it relates to heightened risks to crewed and robotic spacecraft

Krisko, P. H.↗
NASA NTRS2021

A Visual Tour of Carbon Export by Sinking Particles

To better quantify the ocean's biological carbon pump, we resolved the diversity of sinking particles that transport carbon into the ocean's interior, their contribution to carbon export, and their attenuation with depth. Sinking particles collected in sediment trap gel layers from four distinct ocean ecosystems were imaged, measured, and classified. The size and identity of particles was used to model their contribution to particulate organic carbon (POC) flux. Measured POC fluxes were reasonably predicted by particle images. Nine particle types were identified, and most of the compositional variability was driven by the relative contribution of aggregates, long cylindrical fecal pellets, and salp fecal pellets. While particle composition varied across locations and seasons, the entire range of compositions was measured at a single well-observed location in the subarctic North Pacific over one month, across 500 m of depth. The magnitude of POC flux was not consistently associated with a dominant particle class, but particle classes did influence flux attenuation. Long fecal pellets attenuated most rapidly with depth whereas certain other classes attenuated little or not at all with depth. Small particles (<100 m) consistently contributed ~5% to total POC flux in samples with higher magnitude fluxes. The relative importance of these small particle classes (spherical mini pellets, short oval fecal pellets, and dense detritus) increased in low flux environments (up to 46% of total POC flux). Imaging approaches that resolve large variations in particle composition across ocean basins, depth, and time will help to better parameterize biological carbon pump models

Carbon flux↗
DOE OSTI2017

Treatment-Related Toxicity in Patients With Early-Stage Non-Small Cell Lung Cancer and Coexisting Interstitial Lung Disease: A Systematic Review

Purpose: Definitive treatment for patients with early-stage non-small cell lung cancer (ES-NSCLC) is usually well tolerated. Patients with ES-NSCLC and coexisting interstitial lung disease (ILD) are at increased risk of severe treatment-related toxicity after definitive therapy. The main objective of this systematic review is to provide a pooled estimation of treatment-related mortality and ILD-specific toxicity in this population of patients and to identify trends for further study. Methods and Materials: The MEDLINE and Embase databases were queried from respective dates of inception to January 2016. Studies that included patients who underwent definitive treatment for ES-NSCLC not combined with other treatments were included. Patients with oligometastases who were treated with aggressive palliation were included if it did not constitute the majority of patients in a specific study. The results were summarized with weighted proportions according to the sample size of individual studies. Results: Overall, 3056 records were reviewed and 50 journal articles were included in the abstraction. The weighted proportion of treatment-related mortality (and ILD-specific toxicity) in primarily medically inoperable patients was as follows: stereotactic ablative radiation therapy (SABR) 15.6% (25%), particle beam therapy 4.3% (18.2%) and radiofrequency ablation (RFA) 8.7% (25%). The data for medically operable patients who underwent surgery were extracted for reference. Treatment-related mortality and ILD-specific toxicity were 2.2% and 12%, respectively, in the surgical population. On analysis of reported SABR dose parameters, V20 ≤ 6.5% and mean lung dose ≤4.5 Gy were found to be metrics associated with reduced mortality. Conclusion: A consistently high level of treatment-related mortality and ILD-specific toxicity was observed in primarily medically inoperable patients treated with SABR, particle beam therapy, and RFA. For these patients, curative treatment should be considered in the context of the high toxicity rates and overall poor prognosis. Stringent radiation dosimetric parameters may result in reduced toxicity.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Isolation of stem-like cells from spontaneous feline mammary carcinomas: Phenotypic characterization and tumorigenic potential

Current carcinogenesis theory states that only a small subset of tumor cells, the cancer stem cells or tumor initiating cells (TICs), are responsible for tumor formation and progression. Human breast cancer-initiating cells have been identified as CD44-expressing cells, which retain tumorigenic activity and display stem cell-like properties. Spontaneous feline mammary carcinoma (FMC) is an aggressive cancer, which shows biological similarities to the human tumor counterpart. We report the isolation and phenotypic characterization of FMC-derived stem/progenitor cells, showing in vitro self-renewal, long-lasting proliferation and in vivo tumorigenicity. Twenty-one FMC samples were collected, histologically classified and characterized for the expression of Ki67, EGFR, ER-{alpha} and CD44, by immunohistochemistry. By culture in stem cell permissive conditions, we isolated, from 13 FMCs, a CD44-positive subpopulation able to survive and proliferate in vitro as mammospheres of different sizes and morphologies. When injected in NOD/SCID mice, FMC stem-like cells initiate tumors, generating cell heterogeneity and recapitulating the original histotype. In serum-containing medium, spheroid cells showed differentiation properties as shown by morphological changes, the loss of CD44 expression and tumorigenic potential. These data show that stem-defined culture of FMC enriches for TICs and validate the use of these cells as a suitable model for comparative oncology studies of mammary biology and testing therapeutic strategies aimed at eradicating TICs. -- Highlights: Black-Right-Pointing-Pointer Feline mammary carcinoma contain a sub-population of stem-like cells expressing CD44 Black-Right-Pointing-Pointer These grow as spheres in serum-free medium and self-renew Black-Right-Pointing-Pointer Isolated stem-like cancer cells initiate tumor in immunodeficient mice Black-Right-Pointing-Pointer Xenografted tumors are phenotypically similar to the original tumor Black-Right-Pointing-Pointer Upon differentiation, cells grow as monolayers, loosing the tumorigenic potential.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

The PAU Survey: narrow-band photometric redshifts using Gaussian processes

Here, we study the performance of the hybrid template machine learning photometric redshift (photo- z ) algorithm delight , which uses Gaussian processes, on a subset of the early data release of the Physics of the Accelerating Universe Survey (PAUS). We calibrate the fluxes of the 40 PAUS narrow bands with six broad-band fluxes ( uBVriz ) in the Cosmic Evolution Survey (COSMOS) field using three different methods, including a new method that utilizes the correlation between the apparent size and overall flux of the galaxy. We use a rich set of empirically derived galaxy spectral templates as guides to train the Gaussian process, and we show that our results are competitive with other standard photometric redshift algorithms. delight achieves a photo- z 68th percentile error of σ 68 = 0.0081(1 + z ) without any quality cut for galaxies with i auto < 22.5 as compared to 0.0089(1 + z ) and 0.0202(1 + z ) for the bpz and annz 2 codes, respectively. delight is also shown to produce more accurate probability distribution functions for individual redshift estimates than bpz and annz 2. Common photo- z outliers of delight and bcnz 2 (previously applied to PAUS) are found to be primarily caused by outliers in the narrow-band fluxes, with a small number of cases potentially indicating spectroscopic redshift failures in the reference sample. In the process, we introduce performance metrics derived from the results of bcnz 2 and delight , allowing us to achieve a photo- z quality of σ 68 < 0.0035(1 + z ) at a magnitude of i auto < 22.5 while keeping 50 per cent objects of the galaxy sample.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

A Replacement Cold Neutron Guide System for HFIR (Conceptual Design Report)

The design of a replacement cold neutron guide system for the High Flux Isotope Reactor (HFIR) is presented. The proposed six-channel design uses the latest technologies and is optimally designed to account for operational and site constraints. These include the design of the cold source and the beam tube, the size and shape of the penetrations in the reactor confinement boundary, and the shape and orientation of the guide hall. The existing user instruments are a macromolecular diffractometer (IMAGINE), an IMAGING station, two small-angle neutron scattering (SANS) instruments (Bio-SANS and GP-SANS), and a cold triple-axis spectrometer (C-TAX). These instruments will all be reinstalled at end-of-guide positions with improved performance, and a position for a new high-performance neutron spin echo instrument will be created. The proposed guide design requires an extension to the guide hall toward the south. The calculated flux gain for a typical experiment is between a factor of 1.3 and 3 for all instruments, with the exception of the C-TAX instrument, which stands to gain a factor of >30 in flux at the sample. The new guide system will also offer additional performance gains, such as an increase in Q-range on Bio-SANS. The stated performance gains do not take into account any potential performance gains resulting from renewal and realignment of the guide system. The design of the guide system in the common sections up to about 25 m from the source is considered to be complete and ready for engineering design, while the designs of the instrument-specific guides are in some cases still a work in progress. The present report describes the current status of those designs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗