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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Shock interference peak heating measurements using phase change coatings

The phase change coating technique is used to obtain peak heating measurements in shock interference flow regions with high surface shear and heating. This technique provides heat transfer coefficients which are determined by measuring the time for a point on the surface to reach the phase change temperature of the thin fusible coating. Measurements were conducted on a 5.08-cm diameter hemisphere-cylinder made of silica based epoxy at Mach 6 for free stream Reynolds numbers of 3.3 to 25.6 million per meter. A sketch of the shock interference pattern produced by a flat plate shock generator is included. Heating data obtained on a 5.08-cm diameter stainless steel hemispherical model instrumented with thermocouples is presented for the purpose of comparing the phase change technique with the thermocouple-calorimeter technique.

Keyes, J. W.↗
NASA NTRS2003

Inhibition of HSP70 and a Collagen-Specific Molecular Chaperone (HSP47) Expression in Rat Osteoblasts by Microgravity

Rat osteoblasts were cultured aboard a space shuttle for 4 or 5 days. Cells were exposed to 1alpha, 25 dihydroxyvitamin D(3) during the last 20 h and then solubilized by guanidine solution. The mRNA levels for molecular chaperones were analyzed by semi-quantitative RT-PCR. ELISA was used to quantify TGF-beta1 in the conditioned medium. The HSP70 mRNA levels in the flight cultures were almost completely suppressed, as compared to the ground (1 x g) controls. The inducible HSP70 is known as the major heat shock protein that prevents stress-induced apoptosis. The mean mRNA levels for the constitutive HSC73 in the flight cultures were reduced to 69%, approximately 60% of the ground controls. HSC73 is reported to prevent the pathological state that is induced by disruption of microtubule network. The mean HSP47 mRNA levels in the flight cultures were decreased to 50% and 19% of the ground controls on the 4th and 5th days. Concomitantly, the concentration of TGF-beta1 in the conditioned medium of the flight cultures was reduced to 37% and 19% of the ground controls on the 4th and 5th days. HSP47 is the collagen-specific molecular chaperone that controls collagen processing and quality and is regulated by TGF-beta1. Microgravity differentially modulated the expression of molecular chaperones in osteoblasts, which might be involved in induction and/or prevention of osteopenia in space.

Animals↗
NASA NTRS1993

Chromospheric heating by acoustic shock waves

Work by Anderson & Athay (1989) suggests that the mechanical energy required to heat the quiet solar chromosphere might be due to the dissipation of weak acoustic shocks. The calculations reported here demonstrate that a simple picture of chromospheric shock heating by acoustic waves propagating upward through a model solar atmosphere, free of both magnetic fields and local inhomogeneities, cannot reproduce their chromospheric model. The primary reason is the tendency for vertically propagating acoustic waves in the range of allowed periods to dissipate too low in the atmosphere, providing insufficient residual energy for the middle chromosphere. The effect of diverging magnetic fields and the corresponding expanding acoustic wavefronts on the mechanical dissipation length is then discussed as a means of preserving a quasi-acoustic heating hypothesis. It is argued that this effect, in a canopy that overlies the low chromosphere, might preserve the acoustic shock hypothesis consistent with the chromospheric radiation losses computed by Anderson & Athay.

Jordan, Stuart D.↗
DOE OSTI2025

Comparing four heat-inducible promoters in stably transformed sugarcane regarding spatial and temporal control of transgene expression reveals candidates to drive stem-preferred transgene expression

Small heat shock protein (sHSP) promoters contain cis-regulatory elements that facilitate transcription in response to heat stress, making them valuable tools for functional studies through controlled gene expression and the precise regulation of gene-editing tools or morphogenic regulators. To evaluate their utility, GUS reporter gene expression driven by four plant-sourced HSP promoters (p GmHSP17.5 , p HvHSP17 , p ZmHSP17.7 , and p ZmHSP26 ) was compared across various tissues of stably transformed sugarcane before and after heat treatment. At 22°C, all promoters showed minimal activity in leaves and roots, although p ZmHSP17.7 and p HvHSP17 displayed moderate expression in stems. Following heat treatment, all promoters exhibited their highest activity in stems, followed by leaves and roots. In stem tissues, p GmHSP17.5 displayed heat-induced uidA expression comparable to the constitutive p ZmUbi promoter. Notably, heat-induced reporter gene activity in stem middle sections of single-copy transgenic lines containing p ZmHSP17.7 , p HvHSP17 , or p ZmHSP26 exceeded p ZmUbi -derived uidA activity by 9.7-fold, 3.8-fold, and 3.0-fold, respectively, with 346- to 3,672-fold induction compared to control conditions. Most promoters showed peak expression in the middle sections of the stem, while p HvHSP17 was the most active in the stem apices. Histochemical analysis revealed that p ZmHSP17.7 and p HvHSP17 were active in both parenchyma cells and vascular bundles within sugarcane stems. Among leaf tissues, mature leaves exhibited greater expression than senescing or immature leaves, while root activity remained consistently minimal across all promoters. Temperature-course experiments identified distinct activation thresholds: 34°C–36°C for p ZmHSP17.7 , 36°C for p ZmHSP26 , 36°C–38°C for p HvHSP17 , and 40°C–42°C for p GmHSP17.5 . Drought stress also induced reporter gene transcription in stems under HSP promoters, although with lower fold induction than heat treatment. These findings provide valuable tools for gene function studies and biotechnology applications, including heat stress tolerance research, controlled transgene expression in metabolic engineering, precision gene editing, and developmental biology studies.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Shock physics and shadowgraphic measurements of laser-produced cerium plasmas

Shadowgraphic measurements are combined with theory on gas-dynamics to investigate the shock physics associated with nanosecond laser ablation of cerium metal targets. Time-resolved shadowgraphic imaging is performed to measure the propagation and attenuation of the laser-induced shockwave through air and argon atmospheres at various background pressures, where stronger shockwaves characterized by higher propagation velocities are observed for higher ablation laser irradiances and lower pressures. The Rankine-Hugoniot relations are also employed to estimate the pressure, temperature, density, and flow velocity of the shock-heated gas located immediately behind the shock front, predicting larger pressure ratios and higher temperatures for stronger laser-induced shockwaves.

42 ENGINEERING↗
NASA NTRS1996

Distinct transcripts are recognized by sense and antisense riboprobes for a member of the murine HSP70 gene family, HSP70.2, in various reproductive tissues

The expression of hsp70.2, an hsp70 gene family member, originally characterized by its high levels of expression in germ cells in the adult mouse testis, was detected in several other reproductive tissues, including epididymis, prostate, and seminal vesicles, as well as in extraembryonic tissues of mid-gestation fetuses. In addition, hybridization with RNA probes transcribed in the sense orientation surprisingly indicated the presence of slightly larger "antisense" transcripts in several tissues. The levels of antisense transcripts varied among the tissues, with the highest signal detected in the prostate and no signal being detectable in the testis. Consistent with these results, in situ hybridization analysis clearly localized the sense-orientation transcripts to pachytene spermatocytes, while no antisense-orientation transcripts were observed in adjacent sections of the same tubules. Our findings have thus shown that although hsp70.2 was expressed abundantly and in a highly stage-specific manner in the male germ line, it was also expressed in other murine tissues. Furthermore, we have made the surprising observation of antisense transcription of the hsp70.2 gene in several mouse tissues, revealing another level of complexity in the regulation and function of heat shock proteins.

Non-NASA Center↗
NASA NTRS1996

Sense and antisense transcripts of the developmentally regulated murine hsp70.2 gene are expressed in distinct and only partially overlapping areas in the adult brain

We have examined the spatial pattern of expression of a member of the hsp70 gene family, hsp70.2, in the mouse central nervous system. Surprisingly, RNA blot analysis and in situ hybridization revealed abundant expression of an 'antisense' hsp70.2 transcript in several areas of adult mouse brain. Two different transcripts recognized by sense and antisense riboprobes for the hsp70.2 gene were expressed in distinct and only partially overlapping neuronal populations. RNA blot analysis revealed low levels of the 2.7 kb transcript of hsp70.2 in several areas of the brain, with highest signal in the hippocampus. Abundant expression of a slightly larger (approximately 2.8 kb) 'antisense' transcript was detected in several brain regions, notably in the brainstem, cerebellum, mesencephalic tectum, thalamus, cortex, and hippocampus. In situ hybridization revealed that the sense and antisense transcripts were both predominantly neuronal and localized to the same cell types in the granular layer of the cerebellum, trapezoid nucleus of the superior olivary complex, locus coeruleus and hippocampus. The hsp70.2 antisense transcripts were particularly abundant in the frontal cortex, dentate gyrus, subthalamic nucleus, zona incerta, superior and inferior colliculi, central gray, brainstem, and cerebellar Purkinje cells. Our findings have revealed a distinct cellular and spatial localization of both sense and antisense transcripts, demonstrating a new level of complexity in the function of the heat shock genes.

NASA Discipline Developmental Biology↗
NASA NTRS2000

Extremophiles in astrobiology: per Ardua ad Astra

As we consider the possibilities of finding life on other planets, it behooves us to evaluate what we know about the limits for life on planet Earth. In our continued exploration of Earth, we are finding microbes in a variety of unexpected habitats. In geothermal hot springs, we have discovered organisms thriving at temperatures near the boiling point of water and at pH values down to 0.5; in the deepest parts of the oceans, those that grow optimally at pressures above 1000 bars and die at pressures below 500 bars; and at the poles, those that grow below the freezing point of water and die at temperatures above 10 degrees C. All of these organisms are living proof that the biochemical "machinery" of life can be adapted to conditions that, from our anthropocentric perspective, appear to be extreme. By studying the molecular adaptations of extremophiles, we begin to identify the critical cellular components that expand the envelope for life. As an example, I will discuss what we have learned about the role of the proteins we call "heat shock proteins" in pushing the upper temperature limit of life and how our studies have provided a new perspective on the function of these proteins.

Chaperonin 60/physiology↗
NASA NTRS1991

Chaos and ion heating in a slow shock

An ion heating mechanism is proposed of slow shocks, which is associated with the chaotic motion of particles in the downstream wave field. For a coherent electromagnetic wave propagating along the downstream magnetic field, corresponding to switch-off shocks, the particle motions are not chaotic. For an oblique wave, the interaction between the particles and the wave field may lead to chaotic particle motions. Such particles may be greatly thermalized within one wavelength after they are incident into the downstream wave field. The results can be used to explain the existence of the critical intermediate Mach number observed in the hybrid simulations.

Lin, Y.↗
NASA NTRS1983

Observations of the extinction and excitation of the molecular hydrogen emission in Orion

Observations have been made of two quadrupole purely rotational transitions of molecular hydrogen, the 0-0 S(7) and S(5) lines, and of several previously unobserved vibration-rotation hydrogen lines in the Orion molecular cloud. The line ratios indicate a 2.1-micron extinction of about 2 mag. A comparison of the populations of three vibrational levels shows a distribution of excitation temperatures between 1000 and 3000 K. These values are consistent with the theory that hydrogen is thermally excited in shock-heated gas which cools after passage of the shock front. The total luminosity of the hot molecular hydrogen is 200 plus or minus 80 solar luminosity, and the mass of the emitting gas is of the order 0.05 solar mass. The mass and cooling times of the hot hydrogen indicate that at least 10 solar mass of the material has been heated over the lifetime of the outflow.

Beckwith, S.↗
NASA NTRS1971

Shuttle ascent and shock impingement aerodynamic heating studies

The collection and analysis of aerodynamic heating data obtained from shock impingement experimental investigation were completed. The data were categorized into four interference areas; fin leading edge, wing/fuselage fin/plate corners, and space shuttle configurations. The effects of shock impingement were found to increase the heating rates 10 to 40 times the undisturbed values. A test program was completed at NASA/Langley Research Center to investigate the magnitudes and surface patterns of the mated shock interference flowfield. A 0.0065 scale thin-skin model of the MDAC 256-20 space shuttle booster mated with a Stycast model of the MDAC Internal tank orbiter was tested in the 20-inch M=6 tunnel, the 31-inch M=10 tunnel, and the 48-inch Unitary Plan Tunnel. The gap region of the ascent configuration was the principal area of interest where both thermocouple and phase-change paint data were obtained. Pressure and heat transfer distributions data on the leeward surface of a 75-degree sweep slab delta wing are presented. The effects of surface roughness on boundary layer transition and aerodynamic heating were investigated.

Lanning, W. D.↗
DOE OSTI2021

HA15 alleviates bone loss in ovariectomy-induced osteoporosis by targeting HSPA5

The imbalance between osteogenesis and adipogenesis in the bone marrow is the main characteristic of osteoporosis (OP). Thus, exploring regulation of the differentiation of bone marrow stromal cells (BMSCs) into osteoblasts and adipocytes is important to identify novel targets for the treatment of OP. In the present study, the master regulator of endoplasmic reticulum (ER) stress, heat shock protein family A (Hsp70) member 5 (HSPA5) was shown to significantly accumulate in osteoblasts and adipocytes, but not in osteoclasts in bone sections from aged and postmenopausal OP mice. In vitro study revealed that HSPA5 negatively modulated osteogenic differentiation and positively promoted adipogenic differentiation, and that targeting HSPA5 with its inhibitor HA15 enhanced osteogenic differentiation and inhibited adipogenic differentiation. Also, HA15 treatment induces ER stress and autophagy, and decreases apoptosis in cells. We constructed a postmenopausal OP model in mice with ovariectomy surgery, and treated the mice with HA15. The results showed that HA15 treatment induced appropriate ER stress, activated autophagy and decreased apoptosis in osteoblasts, thereby alleviating bone loss in vivo. Our results indicated that HSPA5 participated in OP pathogenesis by regulating the differentiation of BMSCs. HSPA5 may serve as a new target for the treatment of OP, and targeting HSPA5 with HA15 prevents the progression of OP and provides a candidate therapeutic molecule for postmenopausal OP.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Simultaneous compression and opacity data from time-series radiography with a Lagrangian marker

Time-resolved radiography can be used to obtain absolute shock Hugoniot states by simultaneously measuring at least two mechanical parameters of the shock, and this technique is particularly suitable for one-dimensional converging shocks where a single experiment probes a range of pressures as the converging shock strengthens. However, at sufficiently high pressures, the shocked material becomes hot enough that the x-ray opacity falls significantly. Additionally, if the system includes a Lagrangian marker such that the mass within the marker is known, this additional information can be used to constrain the opacity as well as the Hugoniot state. In the limit that the opacity changes only on shock heating, and not significantly on subsequent isentropic compression, the opacity of the shocked material can be determined uniquely. More generally, it is necessary to assume the form of the variation of opacity with isentropic compression or to introduce multiple marker layers. Alternatively, assuming either the equation of state or the opacity, the presence of a marker layer in such experiments enables the non-assumed property to be deduced more accurately than from the radiographic density reconstruction alone. An example analysis is shown for measurements of a converging shock wave in polystyrene at the National Ignition Facility.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗