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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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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Multipole interaction in spectral line broadening by plasmas

A long-standing ambiguity in spectral line broadening theory related to the electric field divergence in the quadrupole term of the screened Coulomb radiator-plasma interaction is examined. This is accomplished with multipole expansions from a Taylor series as well as a partial wave analysis of the screened Coulomb interaction. Here, it is explicitly shown that the two approaches agree up to the octupole term for an effective radiator size small compared to the plasma screening length. Furthermore, the ambigous corrections are confirmed appearing naturally in both methods. For higher multipoles the agreement is demonstrated numerically with a computer program using exact arithmetic.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Low-Cost Screening of Algae for Extreme Tolerance to pH, Temperature, Salinity, and Light

AbstractBioprospecting algae strains with tolerance to extreme conditions such as pH, temperature, salinity, and light is crucial for advancing biotechnology and environmental applications. However, traditional screening methods often involve significant costs and labor, restricting their accessibility and practical use. In this study, we developed and validated low-cost, high-throughput screening techniques, predominantly employing agar plates and liquid culture assays, to effectively differentiate tolerance levels among various algae strains. The methodologies were optimized using the model microalgaChlamydomonas reinhardtiiand its closely related speciesChlamydomonas incertaand the recently discovered extremophilicChlamydomonas pacifica. We systematically evaluated the algae for tolerance to extremes by establishing precise gradients of pH (acidic to alkaline conditions), salinity (0 to 5 M NaCl), temperature (34–42°C), and light intensity (40 to 2977 μE·m⁻²·s⁻¹). Our results demonstrated that these cost-effective, agar plate-based methods effectively distinguished algae strains exhibiting superior tolerance to extreme environmental conditions. These screening techniques not only provided clear differentiation among the closely related strains but also delivered reproducible outcomes suitable for scaling up to larger bioprospecting efforts. Furthermore, the affordability and simplicity of these methods facilitate their implementation in resource-limited laboratories, thereby broadening participation in algae bioprospecting endeavors. This study highlights the potential of low-cost, accessible screening techniques to significantly enhance the discovery and characterization of algal strains with extreme traits. Ultimately, these methods support the development of robust algae-based resources, driving innovation in diverse industrial processes and environmental solutions.Graphical Abstract

Saucedo, Barbara (ORCID:0009000008860839)↗
NASA NTRS1979

The screen hole plasma sheath of an ion accelerator system

Results of the first probing of the screen hole sheath of an ion accelerator system are presented. The screen hole sheath, represented as a set of equipotential contours, extends over a large distance within the discharge plasma. Under no conditions examined does the sheath enter the screen hole. Edge hole defocusing of multiaperture accelerator systems is due primarily to local plasma density variations rather than adjacent screen hole sheath interactions. The sheath boundary is independent of screen-to-accelerator grid spacing when the grid set is operated at the minimum ion beam divergence condition. Significant ion focusing effects occur in the sheath adjacent to the screen grid webbing leading to increased ion source beam current efficiency with decreasing screen-to-accelerator grid separation and/or screen grid thickness.

Aston, G.↗
DOE OSTI2019

In Recognition of Sandia's SCRM Program, Delivering Over 500 Subcontractor Risk Assessments in 2018

The globalization of modern supply chains has resulted in many new risks to Sandia's NW programs and mission. The potential impact of counterfeit products, tampering, theft, malicious software, poor manufacturing and/or development practices, and the influence of foreign governments has become more obvious as new threats and compromises continuously emerge. The Supply Chain Risk Management (SCRM) team was formed specifically to understand and address these risks. We were able to coalesce around these principles to develop and optimize an effective risk assessment process for critical suppliers, called Subcontractor Risk Assessments (SRAs). These elevated screening techniques are planned and delivered in a cost-effective way for Sandia's programs (no increase to purchasing burden rates) and also demonstrate due diligence to DOE/NNSA as a component of Sandia's overall SCRM strategy. SRAs are communicated in a concise 1-page format complete with recommendations as well as links to reference materials for those who require additional details about the SRA process and results.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
NASA NTRS2016

MOPITT Mechanisms 16 Years In-Orbit Operation on TERRA

The 16th anniversary of the launch of NASA's Terra Spacecraft was marked on December 18, 2015, with the Measurements of Pollution in the Troposphere (MOPITT) instrument being a successful contributor to the NASA EOS flagship. MOPITT has been enabled by a large suite of mechanisms, allowing the instrument to perform long-duration monitoring of atmospheric carbon monoxide, providing global measurements of this important greenhouse gas for 16 years. Mechanisms have been successfully employed for scanning, cooling of detectors, and to optically modulate the gas path length within the instrument by means of pressure and gas cell length variation. The instrument utilizes these devices to perform correlation spectroscopy, enabling measurements with vertical resolution from the nadir view, and has thereby furthered understanding of source and global transport effects of carbon monoxide. Given the design requirement for a 5.25-year lifetime, the stability and performance of the majority of mechanisms have far surpassed design goals. With 16 continuously operating mechanisms in service on MOPITT, including 12 rotating mechanisms and 4 with linear drive elements, the instrument was an ambitious undertaking. The long life requirements combined with demands for cleanliness and optical stability made for difficult design choices including that of the selection of new lubrication processes. Observations and lessons learned with regards to many aspects of the mechanisms and associated monitoring devices are discussed here. Mechanism behaviors are described, including anomalies, long-term drive current/power, fill pressure, vibration and cold-tip temperature trends. The effectiveness of particular lubrication formulations and the screening method implemented is discussed in relation to continuous rotating mechanisms and stepper motors, which have exceeded 15 billon rotations and 2.5 billion steps respectively. Aspects of gas cell hermeticity, optical cleanliness, heater problems and SEU effects on accelerometers are also discussed.

Gibson, Andrew S.↗
NASA NTRS1963

Component design, construction and evaluation for satellites

Components for a high-reliability system such as the Telstar project are obtained by: (a) design of the component for the required environment, (b) careful control of manufacturing processes, (c) elimination of potential early failures by screening tests, and (d) selection of the most stable components. For passive components, these methods could be applied by using design parameters, suppliers and screening techniques established in the earlier submarine cable program, with consideration being given to the additional effects of the satellite launch and orbit environments. Semiconductor component designs were selected by qualification tests using accelerated electrical and environmental stress conditions. Screening tests were applied to eliminate early failures, and resulting components were aged from two to six months before selection for the satellite. The recognition of the effect of ionizing radiation on transistors caused the addition of a radiation qualification test, or a screening to assure selection of the least sensitive devices. Tests have shown this screening to be effective for the radiation intensity expected. Experience with the passive components, and evaluation of the accelerated test results and aging data of the semiconductor devices, indicate that the reliability objective was obtained.

TELSTAR SATELLITE↗
DOE OSTI2015

Impact of lateral carrier confinement on electro-optical tuning properties of polariton condensates

Electro-optical measurements on exciton-polaritons below and above the condensation threshold are performed on high quality, pin-doped microcavities with embedded GaAs quantum wells. Applying an external electric field shifts the polariton emission by hundreds of μeV both in the linear and the nonlinear regime. We study three device geometries to investigate the influence of carrier confinement in the plane of the quantum well on the electro-optical tuning properties. In the conventional micropillar geometry, the electric field tuning behavior is dominated by the effects of carrier tunneling and electric field screening that manifest in a blueshift of the polariton emission. In stark contrast, for a planar sample geometry, we can significantly extend the range of electric fields and a redshift is observed. To separate the contributions of quantum confined Stark effect and reduced exciton oscillator strength to the energy shift, we study a third sample where the etching of micropillars is stopped just above the active region. In this semi-planar geometry, exciton and polariton emissions can be measured simultaneously. As for the planar geometry, redshifts of the polariton emission are observed below and above threshold that are well reproduced by theoretical shifts.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

A Comprehensive Machine Learning Model for Metal–Ligand Binding Prediction: Applications in Chemistry and Biology

A machine-learning (ML) model that predicts metal–ligand binding constants was developed using the open-source Chemprop software. The model was trained on over 30,000 experimental log K 1 values, which include both protonation and metal–ligand stability constants, comprising over 3500 ligands and 10 2 metal ions from 73 total elements, thus generalizing beyond existing limited approaches, which focus only on specific metals or ligand families. The best-performing model included a combination of SMILES-based molecular representations along with descriptors for the metal ion and experimental conditions. It had an external test R 2 value of 0.942, and MAE value of 0.834. A “SMILES-only” simpler version also produced accurate predictions and preserved the binding trends, serving as a quick and easily accessible alternative for users without computational expertise. The SMILES-only model performed comparably to density functional theory (DFT) calculations but utilized a fraction of the computational resources. The model was successfully applied across diverse domains, including bioinorganic chemistry, heavy metal remediation, and sensor development and demonstrated its effectiveness as a rapid and reliable screening tool for both academic and industrial uses.

Ligands↗
DOE OSTI2016

Model Lung Surfactant Films: Why Composition Matters

Lung surfactant replacement therapies, Survanta and Infasurf, and two lipid-only systems both containing saturated and unsaturated phospholipids and one containing additional palmitic acid were used to study the impact of buffered saline on the surface activity, morphology, rheology, and structure of Langmuir monolayer model membranes. Isotherms and Brewster angle microscopy show that buffered saline subphases induce a film expansion, except when the cationic protein, SP-B, is present in sufficient quantities to already screen electrostatic repulsion, thus limiting the effect of changing pH and adding counterions. Grazing incidence X-ray diffraction results indicate an expansion not only of the liquid expanded phase but also an expansion of the lattice of the condensed phase. The film expansion corresponded in all cases with a significant reduction in the viscosity and elasticity of the films. The viscoelastic parameters are dominated by liquid expanded phase properties and do not appear to be dependent on the structure of the condensed phase domains in a phase separated film. Here, the results highlight that the choice of subphase and film composition is important for meaningful interpretations of measurements using model systems.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Economics of new molecular targeted personalized radiopharmaceuticals

We report that Nuclear Medicine has come a long way since 2007 when Adrian Nunn pointed out the approval of radiopharmaceuticals was at an all-time low with all the major radiopharmaceutical agents in use having been approved over 10 years ago. Challenges being the prohibitively high cost of drug development and the large number of drugs failing in clinical trials. Proceed to today where Molecular imaging is fast-tracking the drug discovery process by reducing both the time and cost to screen candidates by quantitating the drugs effect on the target and toxicity to normal tissues. Additionally, nuclear medicine is now leading medical practice in personalized medicine using the theragnostic approach. Theragnostics is defined as the use of molecular diagnostic techniques in real-time to stratify patients to guide treatment decisions such as the choice of drug, the dose of administration and the timing of drug delivery for a given patient. Enabling visualization and quantitation of in vivo function of the whole body and thus patient heterogeneity and variability informs the physician on how to treat an individual patient. Recent successes such as the FDA approval of Luta Thera® and NETSPOT™ have resulted in an increasing number of pharmaceutical companies pursing theragnostics further heightened by the purchase of Advanced Accelerator Applications for 3.9 billion by Novartis and Endocyte, Inc for 2.1 billion. Theragnostics are further aiding drug development by showing which agents are most viable and reducing the overall cost of bringing a drug to clinical trials and regulatory approval. This is indeed a renaissance for nuclear medicine in which the acceptance of imaging to inform and monitor therapy has been embraced and even required by the FDA for the clinical evaluation of targeted therapeutic radiopharmaceuticals showing there is indeed a viable business model for targeted theragnostic radiopharmaceuticals and personalized medicine.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

A survey of nuclear pasta in the intermediate-density regime I: Shapes and energies

Nuclear pasta, emerging due to the competition between the long-range Coulomb force and the short-range strong force, is believed to be present in astrophysical scenarios, such as neutron stars and core-collapse supernovae. Its structure can have a high impact e.g. on neutrino transport or the tidal deformability of neutron stars. We study several possible pasta configurations, all of them minimal surface configurations, which are expected to appear in the mid-density regime of nuclear pasta, i.e. around 40% of the nuclear saturation density. In particular we are interested in the energy spectrum for different pasta configurations considered. Employing the density functional theory (DFT) approach, we calculate the binding energy of the different configurations for three values of the proton content X P = 1/10, 1/3 and 1/2, by optimizing their periodic length. We study finite temperature effects and the impact of electron screening. [Results] Nuclear pasta lowers the energy significantly compared to uniform matter, especially for X P ≥ 1/3. However, the different configurations have very similar binding energies. For large proton content, X P ≳ 1/3, the pasta configurations are very stable, for lower proton content temperatures of a few MeV are enough for the transition to uniform matter. Electron screening has a small influence on the binding energy of nuclear pasta, but increases its periodic length. Nuclear pasta in the mid-density regime lowers the energy of the matter for all proton fractions under study. Here, it can survive even large temperatures of several MeV. Since various configurations have very similar energy, it is to expect that many configurations can coexist simultaneously already at small temperatures.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Microsimulation model calibration using incremental mixture approximate Bayesian computation

Microsimulation models (MSMs) are used to inform policy by predicting population-level outcomes under different scenarios. MSMs simulate individual-level event histories that mark the disease process (such as the development of cancer) and the effect of policy actions (such as screening) on these events. MSMs often have many unknown parameters; calibration is the process of searching the parameter space to select parameters that result in accurate MSM prediction of a wide range of targets. We develop Incremental Mixture Approximate Bayesian Computation (IMABC) for MSM calibration which results in a simulated sample from the posterior distribution of model parameters given calibration targets. IMABC begins with a rejection-based ABC step, drawing a sample of points from the prior distribution of model parameters and accepting points that result in simulated targets that are near observed targets. Next, the sample is iteratively updated by drawing additional points from a mixture of multivariate normal distributions and accepting points that result in accurate predictions. Posterior estimates are obtained by weighting the final set of accepted points to account for the adaptive sampling scheme. We demonstrate IMABC by calibrating CRC-SPIN 2.0, an updated version of a MSM for colorectal cancer (CRC) that has been used to inform national CRC screening guidelines.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2023

In Situ Investigation of Upper Airway Occlusion in Sleep Disordered Breathing Using Ultrasonic Transducer Arrays

This work presents a novel application of ultrasound for the real-time, non-invasive investigation of occlusion of the upper airway during events of obstructive sleep apnea/hypopnea syndrome. It is hypothesized that ultrasonic pulses applied to the neck during apneic events produce spectral and temporal features that can detect apnea occurrence. Theoretical models of ultrasound propagation and an in vitro test were conducted to test this hypothesis in both transmission and reflection modes. Complete specifications and technical details of the system design and fabrication, which is mounted on each subject’s neck, are presented, including the methodology. Nine patients (seven male and two female, mean age of 42 years, with a range of 25 to 56 years, and body mass index 37.6 ± 6.6 kg/m2) were recruited for a full night study, which included simultaneous nocturnal polysomnography for the validation of the results. Nine temporal features and four spectral features were extracted from the envelope of the received pulse waveform. These were used to compute 26 metrics to quantify the changes in the ultrasonic waveforms between normal breathing and apneic events. The statistical analysis of the collected ultrasonic data showed that at least two or more of the proposed features could detect apneic events in all subjects. The findings establish the feasibility of the proposed method as a cost-effective and non-invasive OSAHS screening tool.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Best Practices for Body Temperature Measurement with Infrared Thermography: External Factors Affecting Accuracy

Infrared thermographs (IRTs) are commonly used during disease pandemics to screen individuals with elevated body temperature (EBT). To address the limited research on external factors affecting IRT accuracy, we conducted benchtop measurements and computer simulations with two IRTs, with or without an external temperature reference source (ETRS) for temperature compensation. The combination of an IRT and an ETRS forms a screening thermograph (ST). We investigated the effects of viewing angle (θ, 0–75°), ETRS set temperature (T ETRS , 30–40 °C), ambient temperature (T atm , 18–32 °C), relative humidity (RH, 15–80%), and working distance (d, 0.4–2.8 m). We discovered that STs exhibited higher accuracy compared to IRTs alone. Across the tested ranges of T atm and RH, both IRTs exhibited absolute measurement errors of less than 0.97 °C, while both STs maintained absolute measurement errors of less than 0.12 °C. The optimal T ETRS for EBT detection was 36–37 °C. When θ was below 30°, the two STs underestimated calibration source (CS) temperature (T CS ) of less than 0.05 °C. The computer simulations showed absolute temperature differences of up to 0.28 °C and 0.04 °C between estimated and theoretical temperatures for IRTs and STs, respectively, considering d of 0.2–3.0 m, T atm of 15–35 °C, and RH of 5–95%. The results highlight the importance of precise calibration and environmental control for reliable temperature readings and suggest proper ranges for these factors, aiming to enhance current standard documents and best practice guidelines. These insights enhance our understanding of IRT performance and their sensitivity to various factors, thereby facilitating the development of best practices for accurate EBT measurement.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Data for "Propagation of EMIC Waves from Shabansky Orbits in the Dayside Magnetosphere"

Full-wave simulations of electromagnetic ion cyclotron waves in a non-dipole compressed magnetic field have been conducted using the Petra-M simulation code. The manuscript investigates the effect of misalignment of the Faraday screen and electron density in the scrape-off layer on the excitation and propagation of fast helicon and slow mode waves.

Magnetosphere: outer↗
NASA NTRS1975

Fracture control method for composite tanks with load sharing liners

The experimental program was based on the premise that the plastic sizing cycle, which each pressure vessel is subjected to prior to operation, acts as an effective proof test of the liner, screening out all flaws or cracks larger than a critical size. In doing so, flaw growth potential is available for cyclic operation at pressures less than the sizing pressure. Static fracture and cyclic life tests, involving laboratory type specimens and filament overwrapped tanks, were conducted on three liner materials: (1) 2219-T62 aluminum, (2) Inconel X750 STA, and (3) cryoformed 301 stainless steel. Variables included material condition, thickness, flaw size, flaw shape, temperature, sizing stress level, operating stress level and minimum-to-maximum operating stress ratio. From the empirical data base obtained, a procedure was established by which the service life of composite tanks with load sharing liners could be guaranteed with a high degree of confidence.

Bixler, W. D.↗