Temperature-sensitive network drives astable multivibrator
Development of a simple circuit using two Zener diodes and five resistors, which provides a temperature-sensitive voltage to drive the astable multivibrator, is described.
Source record↗
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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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Temperature-sensitive mutants of Bacillus subtilis. I - Multiforked replication and sequential transfer of DNA by a temperature- sensitive mutant
Chromosome of temperature-sensitive mutant of bacillus subtilis 168, observing multiforked replication at normal temperature and transfer of DNA
Yoshikawa, H.↗
A comparison of boundary-layer transition data from temperature-sensitive paint and thermocouple techniques
Temperature sensitive paint and thermocouple techniques comparison for boundary layer transition data, considering aerodynamic heating and transition Reynolds numbers
Mateer, G. G.↗
Depletion of the Protein Hydration Shell with Increasing Temperature Observed by Small-Angle X-ray Scattering and Molecular Simulations
The hydration shell is an integral part of proteins since it plays key roles in conformational transitions, molecular recognition, and enzymatic activity. While the dynamics of the hydration shell have been described by spectroscopic techniques, the structure of the hydration shell remains less understood due to the lack of hydration shell-sensitive structural probes with high spatial resolution. We combined temperature-ramp small-angle X-ray scattering (T-ramp SAXS) from 255 to 335 K with molecular simulations to demonstrate that the hydration shells of the IgG-binding domain of Protein G (GB3) and the villin headpiece are remarkably temperature-sensitive. For proteins in the folded state, T-ramp SAXS data and explicit-solvent SAXS predictions consistently demonstrate decays of protein contrasts and radii of gyration with increasing temperature, which are shown to reflect predominantly temperature-sensitive, depleting hydration shells. The depletion is caused not merely by enhanced disorder within the hydration shells but also by partial displacements of surface-coordinated water molecules. Together, T-ramp SAXS and explicit-solvent SAXS calculations provide a novel structural view of the protein hydration shell, which underlies temperature-dependent processes such as cold denaturation, thermophoresis, or biomolecular phase separation.
electron density↗
Design, characterization and shape recovery behavior of 3D/4D printed shape memory polymers (SMPs)
Shape memory polymers (SMPs) represent a paradigm shift in material science, uniquely capable of undergoing reversible shape transformations triggered by external stimuli, positioning them as pivotal in developing next-generation biomedical devices, aerospace components, and adaptive structures. Extensive research has been done on SMPs with a major focus on high-temperature programming methods, which can limit energy efficiency and applicability with temperature-sensitive materials. Additionally, while various SMP blends have demonstrated great potential, limited work has been done on the suitability for 3D printing these materials, particularly under high-strain and ambient temperature programming conditions. In this study, a three-component optimized SMP composition was evaluated by 3D printing via the Material Extrusion (MEX) technique and investigating its ambient temperature-programming behavior at high strains. The SMP formulation studied was a tailored blend of thermoplastic polyurethane (TPU), polycaprolactone (PCL), and an octadecane diol-based copolymer (OBC) that exhibits robust shape memory behavior, high strain tolerance, and efficient force generation. Rigorous thermal, mechanical, and shape recovery analyses, along with optimized printing parameters and consistent shape recovery rates of up to 90%, were achieved under dynamic mechanical analysis (DMA), even under ambient programming conditions. This work demonstrates the SMP composition’s potential for adaptive, self-deployable systems with 4D printing characteristics ideal for bio-inspired structures and artificial muscle fibers.
Sudan, Kavish [University of Louisville, KY]↗
Development of copper thiolate organometallic compound as thermal sensitive coating for energy storage system safety
Safety and reliability are primary concerns for the deployment of lithium-ion batteries, especially in electric vehicles (EV) and larger-scale energy storage systems (ESS). Current technology in battery management systems (BMS) includes cell voltage monitoring and positioning temperature sensors in selected locations. For a system with hundreds to thousands of individual batteries, single-point temperature monitoring is inadequate to detect hot spots and cell overheating, which could lead to thermal runaway. Here, we have developed a temperature-sensitive copper-thiol compound that can be directly coated onto battery pouch foils to enable early detection of thermal runaway. Upon reaching specific temperatures, this compound releases a sulfur-containing detectable gas, which can be identified using chemically specific gas sensors to trigger an early warning signal. Such a signal propagate through air offers broad signal coverage and enables a more comprehensive approach to large-area temperature monitoring. The Cu-ethanethiol coating is designed to release volatile gases when the substrate surface temperature exceeds 70 °C, with continuous outgassing as the temperature increases. The compound is composed of Cu, S, Cl, hydrocarbons and trace amounts of oxygen. Upon heating, the oxidation state of Cu(I) transitions to Cu (II), accompanied by gas release. Thermogravimetric analysis coupled with mass spectrometry correlated well with the onset of gas release temperature and emission of sulfur-containing volatile gases. Additionally, an acrylic overcoat is applied to enhance the adhesion of the thermally sensitive compound film to the battery pouch foil. This coating is expected to offer an additional safety layer for ESS, alerting possible thermal runaway events before a failure occurs, thereby allowing sufficient time to implement a mitigation plan.
Early warning systems↗
Ineffectiveness of formamidine in suppressing ultralow thermal conductivity in cubic hybrid perovskite FAPbI 3
Understanding lattice dynamics and thermal transport mechanisms in cubic hybrid organic–inorganic perovskites remain challenging due to strong anharmonicity and phase transitions. Here, we investigate the thermal transport behavior in benchmark cubic hybrid perovskite FAPbI 3 by coupling first principles-based anharmonic lattice dynamics with a linearized Wigner transport equation. Using the Temperature-Dependent Effective Potential (TDEP) method, we stabilize the negative soft modes, primarily dominated by organic FA + cations. Our calculations predict an ultra-low thermal conductivity of ~$0.63\,{\rm{W}}{{\rm{m}}}^{-1}{{\rm{K}}}^{-1}$ at 300 K, following a temperature dependence of T −0.740 . Contrary to common assumptions, we find that the [PbI 3 ] 1- units, rather than FA + cations, dominate thermal resistance. Furthermore, we demonstrate that anharmonic force constants are highly temperature-sensitive, relying on 0-K force constants significantly underestimates thermal conductivity. Our study not only elucidates the microscopic mechanisms governing thermal transport in FAPbI 3 but also provides a robust framework for modeling heat conduction in hybrid organic-inorganic compounds.
Zheng, Jiongzhi [Dartmouth College, Hanover, NH (U↗
Transforming an ATP-dependent enzyme into a dissipative, self-assembling system
Nucleoside triphosphate (NTP)-dependent protein assemblies such as microtubules and actin filaments have inspired the development of diverse chemically fueled molecular machines and active materials but their functional sophistication has yet to be matched by design. Given this challenge, we asked whether it is possible to transform a natural adenosine 5'-triphosphate (ATP)-dependent enzyme into a dissipative self-assembling system, thereby altering the structural and functional mode in which chemical energy is used. Furthermore we report that FtsH (filamentous temperature-sensitive protease H), a hexameric ATPase involved in membrane protein degradation, can be readily engineered to form one-dimensional helical nanotubes. FtsH nanotubes require constant energy input to maintain their integrity and degrade over time with the concomitant hydrolysis of ATP, analogous to natural NTP-dependent cytoskeletal assemblies. Yet, in contrast to natural dissipative systems, ATP hydrolysis is catalyzed by free FtsH protomers and FtsH nanotubes serve to conserve ATP, leading to transient assemblies whose lifetimes can be tuned from days to minutes through the inclusion of external ATPases in solution.
59 BASIC BIOLOGICAL SCIENCES↗
Low-loss superconducting resonators fabricated from tantalum films grown at room temperature
The use of α-tantalum in superconducting circuits has enabled a considerable improvement in the coherence time of transmon qubits. The standard approach to grow α-tantalum thin films on silicon involves heating the substrate, which takes several hours per deposition and prevents the integration of this material with wafers containing temperature-sensitive components. We report a detailed experimental study of an alternative growth method of α-tantalum on silicon, which is achieved at room temperature through the use of a niobium seed layer. Despite a substantially higher density of oxygen-rich grain boundaries in the films sputtered at room temperature, resonators made from these films are found to have state-of-the-art quality factors, comparable to resonators fabricated from tantalum grown at high temperature. This finding challenges previous assumptions about correlations between material properties and microwave loss of superconducting thin films, and opens a new avenue for the integration of tantalum into fabrication flows with limited thermal budget.
36 MATERIALS SCIENCE↗
Gold L-shell emission spectroscopy as a temperature diagnostic in laser-driven experiments
Measurements of plasma conditions within gold hohlraums are challenging but provide important information about hohlraum energy transport. To date, there are no reliable passive diagnostic approaches that produce information about the hohlraum plasma conditions. Gold L-shell emission spectroscopy is a promising method to measure the electron temperature in multi-keV gold hohlraum plasmas. In this study, we compare time-resolved measurements of gold L-shell spectra against a more conventional electron temperature-sensitive diagnostic, K-shell emission from zinc, a mid-Z dopant. The Au L-shell and Zn K-shell spectra are taken simultaneously. The analysis of both sets of data exhibits good agreement with a singular rad-hydro model, suggesting a similar evolution in the mean electron temperature of the hohlraum plasma. These findings support the use of L-shell spectroscopy of gold as a method to study gold plasma conditions.
Emission spectroscopy↗
Enhanced chloroplast FtsZ-ring constriction by the ARC6–ARC3 module in Arabidopsis
Chloroplast division, a process tightly linked to the energy demands of plants, is initiated by the formation of the stromal filamenting temperature-sensitive Z (FtsZ) ring. The Z ring is highly dynamic, and its constriction provides the essential force for chloroplast division. However, the regulatory mechanisms governing Z-ring dynamics and constriction remain poorly understood. Here, we report that the chloroplast inner envelope membrane (IEM) protein ACCUMULATION AND REPLICATION OF CHLOROPLASTS6 (ARC6) interacts with the chloroplast stromal protein ARC3, and this interaction is negatively regulated by the conserved J-like domain of ARC6. ARC3 is found both distributed throughout the stroma and localized to a ring-like structure at the chloroplast division site. We demonstrate that ARC6 recruits ARC3 to the division site to form a ring-like structure, likely through direct interaction. This ARC6–ARC3 interaction enables ARC3 to bind FtsZs. Furthermore, we show that the ARC6–ARC3 complex significantly promotes the dynamics of chloroplast Z rings reconstituted in a heterologous system. Finally, the constriction of these reconstituted Z rings is markedly enhanced by ARC6–ARC3. Our findings reveal a regulatory mechanism that governs Z-ring dynamics and constriction, shedding light on the molecular mechanisms underlying chloroplast division.
Science & Technology - Other Topics↗
The Surveyor Thermal Switch
The extemal temperatme extremes of the lunar swjace dictated that a means be found to control the two electronic compartments on the Surveyot soft lunar landing vehicle within a narrower temperatme band to assure satisfactory component pmjonnance. Accordingly, thermal switches were developed to conduct heat away from temperature-sensitive components while heat-generating components were operating during the lunar day, and to retain heat at night when the equipment was off. Future equipment required to vary thermal conductivities, should this principle be employed, can benefit greatly from the results of the many problems encountered and studies made.
LUNAR SURFACE↗
Simple, accurate temperature-measuring instrument
Compact instrument, composed of integrated circuits and a temperature-sensitive platinum resistor, measures temperature over a wide dynamic range. Ultimate accuracy is limited by nonlinearity of the platinum resistor. With proper calibration and current regulation to within 0.01 percent, a measurement accuracy of 0.05 percent can be achieved.
Mc Fadin, L. W.↗
Pulse-width-modulated device for precision temperature control
Temperature controller is described which reduces difference between temperature oscillations about control point. Standard temperature-sensitive resistor element is utilized which is highly stable and reproducible. Temperature sensing circuitry is conventional dc bridge with power supplied by battery or highly regulated supply source.
Heyser, R. C.↗
Filament-wound graphite/epoxy rocket motor case
The fabrication procedures are described for a filament-wound rocket motor case, approximately 56 cm long x 71 cm diameter, utilizing high tensile strength graphite fibers. The process utilized Fiberite Hy-E-1330B prepreg tape which consists of Courtaulds HTS fibers in a temperature-sensitive epoxy matrix. This fabrication effort, with resultant design, material and process recommendations, substantiates the manufacturing feasibility of graphite/epoxy rocket motor cases in the 56 cm x 71 cm size range.
Humphrey, W. D.↗
Photographing flow fields and heat-transfer patterns in color simultaneously.
A color-schlieren technique is described that combines the flow-field shock shapes and the phase-change coating to give a very descriptive account of aerodynamic heating. This technique employs, in addition to the conventional schlieren system, a temperature-sensitive material as a thin surface coating that undergoes a visible phase change from opaque solid to clear liquid at a known temperature. The resulting pictures can lead to a better understanding of shock/boundary layer interactions, as shown with the aid of a specific example.
Creel, T. R., Jr.↗
OGO-6 gas-surface energy transfer experiment
The kinetic energy flux of the upper atmosphere was analyzed using OGO-6 data. Energy transfer between 10 microwatts/sq cm and 0.1 W/sq cm was measured by short-term frequency changes of temperature-sensitive quartz crystals used in the energy transfer probe. The condition of the surfaces was continuously monitored by a quartz crystal microbalance to determine the effect surface contamination had on energy accommodation. Results are given on the computer analysis and laboratory tests performed to optimize the operation of the energy transfer probe. Data are also given on the bombardment of OGO-6 surfaces by high energy particles. The thermoelectrically-cooled quartz crystal microbalance is described in terms of its development and applications.
Mckeown, D.↗
The Fluorescent-Oil Film Method and Other Techniques for Boundary-Layer Flow Visualization
A flow-visualization technique, known as the fluorescent-oil film method, has been developed which appears to be generally simpler and to require less experience and development of technique than previously published methods. The method is especially adapted to use in the large high-powered wind tunnels which require considerable time to reach the desired test conditions. The method consists of smearing a film of fluorescent oil over a surface and observing where the thickness is affected by the shearing action of the boundary layer. These films are detected and identified, and their relative thicknesses are determined by use of ultraviolet light. Examples are given of the use of this technique. Other methods that show promise in the study of boundary-layer conditions are described. These methods include the use of a temperature-sensitive fluorescent paint and the use of a radiometer that is sensitive to the heat radiation from a surface. Some attention is also given to methods that can be used with a spray apparatus in front of the test model.
Loving, Donald L.↗