Performance of Continuous Emission Monitoring Solutions under a Single-Blind Controlled Testing Protocol
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54 ENVIRONMENTAL SCIENCES↗
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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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Assessing the Progress of the Performance of Continuous Monitoring Solutions under a Single-Blind Controlled Testing Protocol
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54 ENVIRONMENTAL SCIENCES↗
Illuminating a blind spot in SARS-CoV-2 immunity
Indigenous populations are disproportionately affected by COVID-19, but are rarely studied. Here an investigation of the immune response of Australian First Nations people to SARS-CoV-2 vaccination and infection shows a major effect of comorbidities.
60 APPLIED LIFE SCIENCES↗
RNA-Puzzles Round V: blind predictions of 23 RNA structures
RNA-Puzzles is a collective endeavor dedicated to the advancement and improvement of RNA three-dimensional structure prediction. With agreement from structural biologists, RNA structures are predicted by modeling groups before publication of the experimental structures. We report a large-scale set of predictions by 18 groups for 23 RNA-Puzzles: 4 RNA elements, 2 Aptamers, 4 Viral elements, 5 Ribozymes and 8 Riboswitches. We describe automatic assessment protocols for comparisons between prediction and experiment. Our analyses reveal some critical steps to be overcome to achieve good accuracy in modeling RNA structures: identification of helix-forming pairs and of non-Watson–Crick modules, correct coaxial stacking between helices and avoidance of entanglements. Three of the top four modeling groups in this round also ranked among the top four in the CASP15 contest.
59 BASIC BIOLOGICAL SCIENCES↗
Oxygen vacancy tuned Ohmic-Schottky conversion for enhanced performance in β-Ga{sub 2}O{sub 3} solar-blind ultraviolet photodetectors
β-Ga{sub 2}O{sub 3} epitaxial thin films were deposited using laser molecular beam epitaxy technique and oxygen atmosphere in situ annealed in order to reduce the oxygen vacancy. Metal/semiconductor/metal structured photodetectors were fabricated using as-grown film and annealed film separately. Au/Ti electrodes were Ohmic contact with the as-grown films and Schottky contact with the annealed films. In compare with the Ohmic-type photodetector, the Schottky-type photodetector takes on lower dark current, higher photoresponse, and shorter switching time, which benefit from Schottky barrier controlling electron transport and the quantity of photogenerated carriers trapped by oxygen vacancy significant decreasing.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Demonstration of solar-blind Al{sub x}Ga{sub 1−x}N-based heterojunction phototransistors
Al{sub 0.4}Ga{sub 0.6}N/Al{sub 0.65}Ga{sub 0.35}N heterojunction phototransistors have been fabricated from the epi-structure grown by low-pressure metal organic chemical vapor deposition on c-plane sapphire substrates. P-type conductivity of the AlGaN base layer was realized by using indium surfactant-assisted Mg-delta doping method. Regrowth technique was used to suppress the Mg memory effect on the n-type emitter. The fabricated devices with a 150-μm-diameter active area exhibited a bandpass spectral response between 235 and 285 nm. Dark current was measured to be less than 10 pA for bias voltages below 2.0 V. A high optical gain of 1.9 × 10{sup 3} was obtained at 6 V bias.
36 MATERIALS SCIENCE↗
High-performing visible-blind photodetectors based on SnO{sub 2}/CuO nanoheterojunctions
We report on the significant performance enhancement of SnO{sub 2} thin film ultraviolet (UV) photodetectors (PDs) through incorporation of CuO/SnO{sub 2} p-n nanoscale heterojunctions. The nanoheterojunctions are self-assembled by sputtering Cu clusters that oxidize in ambient to form CuO. We attribute the performance improvements to enhanced UV absorption, demonstrated both experimentally and using optical simulations, and electron transfer facilitated by the nanoheterojunctions. The peak responsivity of the PDs at a bias of 0.2 V improved from 1.9 A/W in a SnO{sub 2}-only device to 10.3 A/W after CuO deposition. The wavelength-dependent photocurrent-to-dark current ratio was estimated to be ∼592 for the CuO/SnO{sub 2} PD at 290 nm. The morphology, distribution of nanoparticles, and optical properties of the CuO/SnO{sub 2} heterostructured thin films are also investigated.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Measurement and simulation of top- and bottom-illuminated solar-blind AlGaN metal-semiconductor-metal photodetectors with high external quantum efficiencies
A comprehensive study on top- and bottom-illuminated Al{sub 0.5}Ga{sub 0.5}N/AlN metal-semiconductor-metal (MSM) photodetectors having different AlGaN absorber layer thickness is presented. The measured external quantum efficiency (EQE) shows pronounced threshold and saturation behavior as a function of applied bias voltage up to 50 V reaching about 50% for 0.1 μm and 67% for 0.5 μm thick absorber layers under bottom illumination. All experimental findings are in very good accordance with two-dimensional drift-diffusion modeling results. By taking into account macroscopic polarization effects in the hexagonal metal-polar +c-plane AlGaN/AlN heterostructures, new insights into the general device functionality of AlGaN-based MSM photodetectors are obtained. The observed threshold/saturation behavior is caused by a bias-dependent extraction of photoexcited holes from the Al{sub 0.5}Ga{sub 0.5}N/AlN interface. While present under bottom illumination for any AlGaN layer thickness, under top illumination this mechanism influences the EQE-bias characteristics only for thin layers.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Inorganic vacancy-ordered perovskite Cs 2 SnCl 6 :Bi/GaN heterojunction photodiode for narrowband, visible-blind UV detection
In this work, a heterojunction photodiode was fabricated from Bi doped Cs 2 SnCl 6 nanoparticles (Cs 2 SnCl 6 :Bi NPs) spin-coated on an epitaxially grown GaN substrate. With the back illumination configuration, the heterojunction photodiode demonstrated excellent narrow-band UV sensing capability with a full wavelength of half maximum of 18 nm and a maximum detectivity of 1.2 × 10 12 jones, which is promising for biomedical applications. In addition to the excellent narrow band UV sensitivity, the device also demonstrated a large linear dynamic range of 71 decibels (dB) and a fast photoresponse speed (a rise time of 0.75 μs and a fall time of 0.91 μs). The excellent performance is attributed to excellent carrier separation efficiency at the heterojunction interface and improved carrier collection efficiency through the multi-walled carbon nanotube (MWCNT) network. All the above advantages are of great importance for commercial deployment of perovskite-based photodetectors.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Solving the structure of Lgl2, a difficult blind test of unsupervised structure determination
In the companion paper by Ufimtsev and Levitt [Ufimtsev IS, Levitt M (2019) Proc Natl Acad Sci USA , 10.1073/pnas.1821512116], we presented a method for unsupervised solution of protein crystal structures and demonstrated its utility by solving several test cases of known structure in the 2.9- to 3.45-Å resolution range. Here we apply this method to solve the crystal structure of a 966-amino acid construct of human lethal giant larvae protein (Lgl2) that resisted years of structure determination efforts, at 3.2-Å resolution. The structure was determined starting with a molecular replacement (MR) model identified by unsupervised refinement of a pool of 50 candidate MR models. This initial model had 2.8-Å RMSD from the solution. The solved structure was validated by comparison with a model subsequently derived from an alternative crystal form diffracting to higher resolution. This model could phase an anomalous difference Fourier map from an Hg derivative, and a single-wavelength anomalous dispersion phased density map made from these sites aligned with the refined structure.
59 BASIC BIOLOGICAL SCIENCES↗
Blind Benchmark Exercise for Spent Nuclear Fuel Decay Heat
The decay heat rate of five spent nuclear fuel assemblies of the pressurized water reactor type were measured by calorimetry at the interim storage for spent nuclear fuel in Sweden. Calculations of the decay heat rate of the five assemblies were performed by 20 organizations using different codes and nuclear data libraries resulting in 31 results for each assembly, spanning most of the current state-of-the-art practice. The calculations were based on a selected subset of information, such as reactor operating history and fuel assembly properties. The relative difference between the measured and average calculated decay heat rate ranged from 0.6% to 3.3% for the five assemblies. The standard deviation of these relative differences ranged from 1.9% to 2.4%.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
A BLIND METHOD TO DETREND INSTRUMENTAL SYSTEMATICS IN EXOPLANETARY LIGHT CURVES
The study of the atmospheres of transiting exoplanets requires a photometric precision, and repeatability, of one part in ∼10{sup 4}. This is beyond the original calibration plans of current observatories, hence the necessity to disentangle the instrumental systematics from the astrophysical signals in raw data sets. Most methods used in the literature are based on an approximate instrument model. The choice of parameters of the model and their functional forms can sometimes be subjective, causing controversies in the literature. Recently, Morello et al. (2014, 2015) have developed a non-parametric detrending method that gave coherent and repeatable results when applied to Spitzer/IRAC data sets that were debated in the literature. Said method is based on independent component analysis (ICA) of individual pixel time-series, hereafter “pixel-ICA”. The main purpose of this paper is to investigate the limits and advantages of pixel-ICA on a series of simulated data sets with different instrument properties, and a range of jitter timescales and shapes, non-stationarity, sudden change points, etc. The performances of pixel-ICA are compared against the ones of other methods, in particular polynomial centroid division, and pixel-level decorrelation method. We find that in simulated cases pixel-ICA performs as well or better than other methods, and it also guarantees a higher degree of objectivity, because of its purely statistical foundation with no prior information on the instrument systematics. The results of this paper, together with previous analyses of Spitzer/IRAC data sets, suggest that photometric precision and repeatability of one part in 10{sup 4} can be achieved with current infrared space instruments.
79 ASTRONOMY AND ASTROPHYSICS↗
Status of CME Search Before Isobar Collisions and Methods of Blind Analysis From STAR
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73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
The unseen: revealing the blind production procedure and experience for NP data
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73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Blind chemical tagging with DBSCAN: prospects for spectroscopic surveys
Abstract Chemical tagging has great promise as a technique to unveil our Galaxy’s history. Grouping stars based on their similar chemistry can establish details of the star formation and merger history of the Milky Way. With precise measurements of stellar chemistry, chemical tagging may be able to group together stars born from the same gas cloud, regardless of their current positions and kinematics. Successfully tagging these birth clusters requires high-quality chemical space information and a good cluster-finding algorithm. To test the feasibility of chemical tagging on data from current and upcoming spectroscopic surveys, we construct a realistic set of synthetic clusters, creating both observed spectra and derived chemical abundances for each star. We use Density-Based Spatial Clustering of Applications with Noise (DBSCAN) to group stars based on their spectra or abundances; these groups are matched to input clusters and are found to be highly homogeneous and complete. The percentage of clusters with more than 10 members recovered is 40 per cent when tagging on abundances with uncertainties achievable with current techniques. Based on our fiducial model for the Milky Way, we predict recovering over 600 clusters with at least 10 observed members and 70 per cent membership homogeneity in a sample similar to the Apache Point Observatory Galactic Evolution Experiment survey. Tagging larger surveys like the GALAH survey and the future Milky Way Mapper in Sloan Digital Sky Survey V could recover tens of thousands of clusters at high homogeneity. Access to so many unique co-eval clusters will transform how we understand the star formation history and chemical evolution of our Galaxy.
Price-Jones, Natalie↗