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Results for “Temperature screening”

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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

CO2 response screen in grass Brachypodium reveals the key role of a MAP kinase in CO2-triggered stomatal closure

Abstract Plants respond to increased CO2 concentrations through stomatal closure, which can contribute to increased water use efficiency. Grasses display faster stomatal responses than eudicots due to dumbbell-shaped guard cells flanked by subsidiary cells working in opposition. However, forward genetic screening for stomatal CO2 signal transduction mutants in grasses has yet to be reported. The grass model Brachypodium distachyon is closely related to agronomically important cereal crops, sharing largely collinear genomes. To gain insights into CO2 control mechanisms of stomatal movements in grasses, we developed an unbiased forward genetic screen with an EMS-mutagenized B. distachyon M5 generation population using infrared imaging to identify plants with altered leaf temperatures at elevated CO2. Among isolated mutants, a “chill1” mutant exhibited cooler leaf temperatures than wild-type Bd21-3 parent control plants after exposure to increased CO2. chill1 plants showed strongly impaired high CO2-induced stomatal closure despite retaining a robust abscisic acid-induced stomatal closing response. Through bulked segregant whole-genome sequencing analyses followed by analyses of further backcrossed F4 generation plants and generation and characterization of sodium azide and CRISPR-cas9 mutants, chill1 was mapped to a protein kinase, Mitogen-Activated Protein Kinase 5 (BdMPK5). The chill1 mutation impaired BdMPK5 protein-mediated CO2/HCO3− sensing together with the High Temperature 1 (HT1) Raf-like kinase in vitro. Furthermore, AlphaFold2-directed structural modeling predicted that the identified BdMPK5-D90N chill1 mutant residue is located at the interface of BdMPK5 with the BdHT1 Raf-like kinase. BdMPK5 is a key signaling component that mediates CO2-induced stomatal movements and is proposed to function as a component of the primary CO2 sensor in grasses.

Lopez, Bryn N. K. (ORCID:0009000937288216)↗
DOE OSTI2022

Correcting for digital image correlation speckle inversion at high temperature using color cameras

Digital image correlation (DIC) is a popular, noncontacting technique to measure full-field deformation by using cameras to track the motion of an applied surface pattern. Because it is noncontacting, DIC can be performed for extreme temperature applications (e.g., hot-fire rocket testing of carbon composite rocket nozzles) under harsh conditions during which bonded gauges are damaged. Speckle pattern inversion is a phenomenon that sometimes occurs while performing high-temperature DIC. During speckle pattern inversion, portions of the surface pattern that were initially darker at room temperature (e.g., graphite) may emit more light due to blackbody radiation than the portions that were initially paler, thereby producing images in which the pattern appears inverted at high temperature relative to the initial pattern at room temperature. This phenomenon can prevent the correlation algorithm from being able to resolve the displacements between images. This work compares three methods to mitigate speckle pattern inversion: (A) the subtraction method, a recently-published technique in which two high-temperature images are subtracted to remove unwanted light; (B) the filtering method, a popular technique in which optical bandpass filters screen out unwanted light; and (C) the histogram rescaling method, a proposed new method that pairs a color camera with a blue light source and uses information from the green sensor of the camera to correct against inversion in the blue sensor through postprocessing. The histogram rescaling method is shown to successfully eliminate speckle pattern inversion and has the added advantages that it does not require quasi-static loading to be able to compensate for speckle pattern inversion, nor does it impose thick-glass distortions caused by the optical filter.

Rowley, Lindsey J.↗
NASA NTRS1971

Mathematical modeling of high and low temperature heat pipes

Following a review of heat and mass transfer theory relevant to heat pipe performance, math models are developed for calculating heat-transfer limitations of high-temperature heat pipes and heat-transfer limitations and temperature gradient of low temperature heat pipes. Calculated results are compared with the available experimental data from various sources to increase confidence in the present math models. Complete listings of two computer programs for high- and low-temperature heat pipes respectively are included. These programs enable the performance to be predicted of heat pipes with wrapped-screen, rectangular-groove, or screen-covered rectangular-groove wick.

Chi, S. W.↗
NASA NTRS1973

Development of seal ring carbon-graphite materials (tasks 8, 9, and 10)

A screening study was conducted to develop improved carbon-graphite materials for use in self-acting seals at air temperatures to 1300 F (704 C). Property measurements on materials prepared during this study have shown that: (1) The mechanical properties of a carbon-graphite material were significantly improved by using a fine milled artificial graphite filler material and including intensive mixing, warm molding, and pitch impregnation in the processing; and (2) the oxidation resistance of a carbon-graphite material was improved by including fine milled boron carbide as an oxidation-inhibiting additive. These techniques were employed to develop a material that has 10 times more oxidation resistance than that of a widely used commercial grade and mechanical properties that approach those of the commercial grade.

Fechter, N. J.↗
NASA NTRS1984

The effect of row direction on the microwave emission from vegetation canopies

Experiments were conducted to determine the microwave brighthness temperature of corn and soybean canopies as a function of polarization and azimuth look direction. A strong dependence on row direction and polarization is observed for soybeans. The corn canopy shows a similar dependence, although to a lesser extent. The variation in brightness temperature is shown to be related to the canopy alone, since the underlying soil surface was blocked by reflecting metal screens.

Brunfeldt, D. R.↗
DOE OSTI2022

Analysis of coherent Thomson scattering from a low temperature plasma

In this work, the spectrum of coherent Thomson scattering (CTS) induced by a periodic ponderomotive perturbation in a low-density low temperature plasma is considered. The analysis is performed for the case when the period of the resulting optical lattice is less than the Debye screening length in the plasma by solving an electron Boltzmann equation, where the total force is the sum of the periodic force due to the optical lattice and the electrostatic force due to self-consistent electric field in the plasma. An analogy between the CTS spectra calculated here and coherent Rayleigh scattering spectra in a neutral gas is established. For relatively low intensity for the optical lattice, the calculated CTS spectra are nearly Gaussian with widths slightly wider than the incoherent Thomson widths. We demonstrate that at higher intensities the line shape narrows and saturates to a width approximately half of that found at low lattice intensities. The proportionality of the spectral width to the square root of the electron temperature allows one to extract the electron temperature from the saturated spectra. Possible application of CTS for remote measuring the electron temperature in plasma is discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Multi-omics profiling of the cold tolerant Monoraphidium minutum 26B-AM in response to abiotic stress

Microalgae that are of interest for biofuel production must be able to tolerate environmental changes that occur in outdoor cultivation systems. While algal cultures may experience daily temperature fluctuations and seasonal environmental changes, the underlying mechanisms that control and regulate physiological responses and adaptation to environmental pressures are largely unknown. Systems-level characterization enabled by functional genomics can help identify biochemical pathways that promote stability and productivity of algae in various environmental conditions. Monoraphidium minutum 26B-AM, a freshwater green microalga, was identified as a top performer in biomass production in winter season screens. We sequenced the genome of M. minutum 26B-AM and applied our multi-omics pipeline to profile this high potential strain under high salt and cold temperature perturbations. Through comparative analysis, including other green algae in the class Chlorophyceae, we identified gene families unique to the genus Monoraphidium, including a desaturase that has been linked to cold tolerance in plants. We observed that osmolytes, such as trehalose, proline and betaine, accumulate under salt stress, coinciding with upregulation of genes involved in biosynthesis of these metabolites. From the genome annotation, we reconstructed a metabolic model to provide a detailed map of the metabolic pathways and can be used to simulate growth and reaction fluxes. This multi-omics analysis provides a foundation to explore algal strain potential for biofuel applications, guides strain engineering, and expands our understanding of metabolic and regulatory mechanisms of algae in applied systems.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Novel structured Sm 0.5 Sr 0.5 CoO 3-δ cathode for intermediate and low temperature solid oxide fuel cells

The performance of solid oxide fuel cell (SOFC) can be significantly enhanced using nanostructured cathode obtained by infiltration/impregnation method. However, this method has been limited due to multi-step preparation process and instability of the obtained nanoscale catalyst under long-term operation. We report here a simple, cost-effective and reproducible approach to fabricate nanostructured Sm 0.5 Sr 0.5 CoO 3-δ (SSC) cathode with enhanced performance and stability. The SSC powders were prepared by a freeze-drying method through a combustion route using Pluronic F-127 as the template. The SSC freeze-drying powders have unique morphology and a significant phase change at 750 °C. The oxygen non-stoichiometry (δ) of the SSC powders is 0.18 at room temperature, while the δ values are 0.66, 0.75 and 0.90 at 600 °C, 700 °C and 800 °C, respectively. The novel structured SSC cathode was prepared by screen-printing and one-step sintering process using the freeze-drying SSC powders. Maximum cell power densities of 0.83 and 1.13 W cm -2 are achieved at 550 °C and 600 °C, respectively for single cells with the novel structured SSC cathode. Moreover, single cells show excellent stability at 600 °C under a current density of 600 mA cm -2 over 250 h. This work expands opportunities to exploit nanotechnology in a wide range of intermediate and low temperature energy conversion devices.

25 ENERGY STORAGE↗
DOE OSTI2020

Microscale thermophoresis as a powerful tool for screening glycosyltransferases involved in cell wall biosynthesis

Background: Identification and characterization of key enzymes associated with cell wall biosynthesis and modification is fundamental to gain insights into cell wall dynamics. However, it is a challenge that activity assays of glycosyltransferases are very low throughput and acceptor substrates are generally not available. Results: We optimized and validated microscale thermophoresis (MST) to achieve high throughput screening for glycosyltransferase substrates. MST is a powerful method for the quantitative analysis of protein-ligand interactions with low sample consumption. The technique is based on the motion of molecules along local temperature gradients, measured by fluorescence changes. We expressed glycosyltransferases as YFP-fusion proteins in tobacco and optimized the MST method to allow the determination of substrate binding affinity without purification of the target protein from the cell lysate. The application of this MST method to the β-1,4-galactosyltransferase AtGALS1 validated the capability to screen both nucleotide-sugar donor substrates and acceptor substrates. We also expanded the application to members of glycosyltransferase family GT61 in sorghum for substrate screening and function prediction. Conclusions: This method is rapid and sensitive to allow determination of both donor and acceptor substrates of glycosyltransferases. MST enables high throughput screening of glycosyltransferases for likely substrates, which will narrow down their in vivo function and help to select candidates for further studies. Additionally, this method gives insight into biochemical mechanism of glycosyltransferase function.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

All-Ceramic Passive Wireless Temperature Sensor Realized by Tin-Doped Indium Oxide (ITO) Electrodes for Harsh Environment Applications

In this work, an all-ceramic passive wireless inductor–capacitor (LC) resonator was presented for stable temperature sensing up to 1200 °C in air. Instead of using conventional metallic electrodes, the LC resonators are modeled and fabricated with thermally stable and highly electroconductive ceramic oxide. The LC resonator was modeled in ANSYS HFSS to operate in a low-frequency region (50 MHz) within 50 × 50 mm geometry using the actual material properties of the circuit elements. The LC resonator was composed of a parallel plate capacitor coupled with a planar inductor deposited on an Al2O3 substrate using screen-printing, and the ceramic pattern was sintered at 1250 °C for 4 h in an ambient atmosphere. The sensitivity (average change in resonant frequency with respect to temperature) from 200–1200 °C was ~170 kHz/°C. The temperature-dependent electrical conductivity of the tin-doped indium oxide (ITO, 10% SnO2 doping) on the quality factor showed an increase of Qf from 36 to 43 between 200 °C and 1200 °C. The proposed ITO electrodes displayed improved sensitivity and quality factor at elevated temperatures, proving them to be an excellent candidate for temperature sensing in harsh environments. The microstructural analysis of the co-sintered LC resonator was performed using a scanning electron microscope (SEM) which showed that there are no cross-sectional and topographical defects after several thermal treatments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Enhanced Ion Transport and Molecular Packing Stability in Asymmetric 2D Nanostructured π‐Conjugated Thieno[3,2‐b]Thiophene‐Based Liquid Crystal

Organic semiconductors based on liquid crystal (LC) molecules have attracted increasing interest. Here, in this work, two linear LCs based on 2,5‐bis(thien‐2‐yl)thieno[3,2‐b]thiophene (BTTT) mesogen are designed and synthesized, including BTTT/dEO3 with two symmetrically attached tri(ethylene oxide) groups and BTTT/mEO6 with one asymmetrically attached hexa(ethylene oxide) group. These two molecules have comparable functional‐group compositions but different molecular geometries, leading to their moderately different material performances. Both LCs show smectic mesophases with relatively low transition temperatures as confirmed by differential scanning calorimetry and polarized optical microscopy. A combination of experimental grazing incidence wide‐angle X‐ray scattering and molecular dynamics (MD) simulations reveals a herringbone packing motif of BTTT segments in both LCs while a smaller molecular tilt angle in BTTT/mEO6. Ionic conductivities are measured by doping LCs with different amounts of ionic dopants, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). BTTT/mEO6 shows better smectic phase stability to higher LiTFSI doping ratios. Both LCs exhibit similar ionic conductivities in the smectic phases, but BTTT/mEO6 outperforms BTTT/dEO3 by a factor of three in the amorphous phase at higher temperatures. MD simulations, performed to examine the ion solvation environment, reveal that BTTT/mEO6 is more efficient in coordinating Li‐ions and screening their interactions with TFSI‐ions which further promote ionic transport.

grazing incidence wide-angle X-ray scattering↗
NASA NTRS1976

The effect of changes in the USF/NASA toxicity screening test method on data from some cellular polymers

Rankings of relative toxicity can be markedly affected by changes in test variables. Revision of the USF/NASA toxicity screening test procedure to eliminate the connecting tube and supporting floor and incorporate a 1.0 g sample weight, 200 C starting temperature, and 800 C upper limit temperature for pyrolysis, reversed the rankings of flexible polyurethane and polychloroprene foams, not only in relation to each other, but also in relation to cotton and red oak. Much of the change is attributed to reduction of the distance between the sample and the test animals, and reduction of the sample weight charged. Elimination of the connecting tube increased the relative toxicity of the polyurethane foams. The materials tested were flexible polyurethane foam, without and with fire retardant; rigid polyurethane foam with fire retardant; flexible polychloroprene foam; cotton, Douglas fir, red oak, hemlock, hardboard, particle board, polystyrene, and polymethyl methacrylate.

Hilado, C. J.↗
NASA NTRS1976

An experimental study of a self-confined flow with ring-vorticity distribution

A new form of self-confined flow was investigated in which a recirculation zone forms away from any solid boundary. An inviscid flow analysis indicated that in a purely meridional axisymmetric flow a stationary, spherical, self-confined region should occur in the center of a streamlined divergent-convergent enlargement zone. The spherical confinement region would be at rest and at constant pressure. Experimental investigations were carried out in a specially built test apparatus to establish the desired confined flow. The streamlined divergent-convergent interior shape of the test section was fabricated according to the theoretical calculation for a particular streamline. The required inlet vorticity distribution was generated by producing a velocity profile with a shaped gauze screen in the straight pipe upstream of the test section. Fluid speed and turbulence intensity were measured with a constant-temperature hot-wire anemometer system. The measured results indicated a very orderly and stable flow field.

Lin, K. M.↗
NASA NTRS1977

Experimental investigations on sodium-filled heat pipes

The possibilities of producing heat pipes and, especially, the necessary capillary structures are discussed. Several types of heat pipes were made from stainless steel and tested at temperatures between 400 and 1055 deg C. The thermal power was determined by a calorimeter. Results indicate: bubble-free evaporation of sodium from rectangular open chennels is possible with a heat flux of more than 1,940 W/sq cm at 1055 C. The temperature drop along the tube could be measured only at low temperatures. A subdivided heat pipe worked against the gravitational field. A heat pipe with a capillary structure made of a rolled screen was supported by rings and bars operated at 250 W/sq cm heat flux in the evaporating region.

Dorner, S.↗
NASA NTRS1981

Development of design, qualification, screening, and application requirements for plastic encapsulated solid-state devices for space applications

Test data were collected on 1035 plastic encapsulated devices and 75 hermetically scaled control group devices that were purchased from each of five different manufacturers in the categories of (1) low power Schottsky TTL (bipolar) digital circuits; (2) CMOS digital circuits; (3) operational amplifier linear circuits; and (4) NPN transistors. These parts were subjected to three different initial screening conditions, then to extended life testing, to determine any possible advantages or trends for any particular screen. Several tests were carried out in the areas of flammability testing, humidity testing, high pressure steam (auroclave) testing, and high temperature storage testing. Test results are presented. Procurement and application considerations for use of plastic encapsulated semiconductors are presented and a statistical analysis program written to study the log normal distributions resulting from life testing is concluded.

Source record↗
NASA NTRS1983

Dual laser optical system and method for studying fluid flow

A dual laser optical system and method is disclosed for visualization of phenomena in transport substances which induce refractive index gradients such as fluid flow and pressure and temperature gradients in fluids and gases. Two images representing mutually perpendicular components of refractive index gradients may be viewed simultaneously on screen. Two lasers having wave lengths in the visible range but separated by about 1000 angstroms are utilized to provide beams which are collimated into a beam containing components of the different wave lengths. The collimated beam is passed through a test volume of the transparent substance. The collimated beam is then separated into components of the different wave lengths and focused onto a pair of knife edges arranged mutually perpendicular to produce and project images onto the screen.

Owen, R. B.↗
DOE OSTI2024

Preliminary Screening of Features, Events, and Processes for an Arctic-Focused Climate Intervention Performance Assessment

Geoengineering, the deliberate large-scale intervention in Earth's climate system, holds significant potential in the rapidly warming Arctic, where temperatures currently rise at more than twice the global average, accelerating ice sheet and permafrost melt. This contributes to global sea-level rise and releases methane, a potent greenhouse gas. Strategies like solar radiation management (SRM) and carbon dioxide removal (CDR) could mitigate these effects; for instance, SRM techniques aim to reflect a portion of the sun's energy back into space, potentially slowing ice melt and stabilizing permafrost. However, geoengineering in the Arctic faces challenges, including potential unintended consequences on the fragile ecosystem, disruption of local weather patterns, and impacts on indigenous communities. Effective governance requires robust international cooperation, environmental impact assessments, and regulatory frameworks. Despite these challenges, geoengineering's potential benefits make it a critical research area. This report explores application of the Performance Assessment (PA) methodology to Arctic Climate Intervention, providing an initial screening of relevant features, events, and processes (FEPs). At the core of the PA approach is the identification and evaluation of FEPs that could impact the performance of the intervention scheme. Here we provide an initial screening of FEPs to consider in the application of PA to Arctic Climate Intervention.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

High-Throughput Screening and Accurate Prediction of Ionic Liquid Viscosities Using Interpretable Machine Learning

Ionic liquids (ILs) are a novel group of green solvents with great promise for various industrial applications, including carbon capture and lignocellulosic biomass deconstruction. However, the use of ILs at the industrial scale remains challenging due to their high viscosities at ambient temperatures. To develop ILs with lower viscosities, a systematic study of their quantitative structure–property relationship (QSPR) is desirable. Here, we developed four machine learning (ML) models to predict viscosity at various temperature and pressure ranges, trained over a wide range of ILs consisting of various cationic and anionic families. ML methods including two-factor polynomial regression (two-factor PR), support vector regression (SVR), feed-forward neural networks (FFNN), and categorical boosting (CATBoost) were developed based on features that have proven useful in previous ML studies: COSMO-RS (conductor-like screening model for real solvents)-derived surface screening charge densities (sigma profiles). FFNN and CATBoost were the most accurate in predicting IL viscosities with lower average absolute relative deviation and higher R2 values on the test set. Tanimoto similarity scores were calculated to characterize the chemical space and structural similarity of the investigated ions. Furthermore, SHapley Additive exPlanation (SHAP) analysis was employed to interpret the ML results. Temperature, the polar area of ILs, and the nonpolar regions of ions are key features that influence the viscosity predictions. Importantly, the IL viscosity prediction here is the most accurate reported to date.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗