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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 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

Comparison of Interstitial Fluid pH, PCO2, PO2 with Venous Blood Values During Repetitive Handgrip Exercise

We evaluated the use of a small, fiber optic sensor to measure pH, PCO2 and PO2 from forearm muscle interstitial fluid (IF) during handgrip dynamometry. PURPOSE: Compare pH, PCO2 and PO2 values obtained from venous blood with those from the IF of the flexor digitorum superficialis (FDS) during three levels of exercise intensity. METHODS: Six subjects (5M/1F), average age 29+/-5 yrs, participated in the study. A venous catheter was placed in the retrograde direction in the antecubital space and a fiber optic sensor (Paratrend, Diametrics Medical, Inc.) was placed through a 22 G catheter into the FDS muscle under ultrasound guidance. After a 45 min rest period, subjects performed three 5-min bouts of repetitive handgrip exercise (2s contraction/1 s relaxation) at attempted levels of 15%, 30% and 45% of maximal voluntary contraction. The order of the exercise bouts was random with the second and third bouts started after blood lactate had returned to baseline. Venous blood was sampled every minute during exercise and analyzed with an I-Stat CG-4+ cartridge, while IF fiber optic sensor measurements were obtained every 2 s. Change from pre-exercise baseline to end of exercise was computed for pH, PCO2 and PO2. Blood and IF values were compared with a paired t-test. RESULTS: Baseline values for pH, PCO2 and PO2 were 7.37+/-0.02, 46+/-4 mm Hg, and 36+/-6 mm Hg respectively in blood and 7.39+/-0.02, 44+/-6 mm Hg, and 35+/-14 mm Hg in IF. Average changes over all exercise levels are noted in the Table below. For each parameter the exercise-induced change was at least twice as great in IF as in blood. In blood and IF, pH and PCO2 increases were directly related to exercise intensity. Change in venous PO2 was unrelated to exercise intensity, while IF PO2 decreased with increases in exercise intensity. CONCLUSIONS: Measurement of IF pH, PCO2 and PO2 is more sensitive to exercise intensity than measurement of the same parameters in venous blood and provides continuous assessment during and after exercise.

Hagan, Ronald Donald↗
NASA NTRS2016

Carbon Monoxide Accumulation in the Extravehicular Mobility Unit

Introduction: Life support technology in large closed systems like submarines and space stations catalyzes carbon monoxide (CO) to carbon dioxide, which is easily removed. However, in a small system like the Extravehicular Mobility Unit (EMU), spacesuit, CO from exogenous (contaminated oxygen (O (sub 2) supply) and endogenous (human metabolism) sources will accumulate in the free suit volume. The free volume becomes a sink for CO that is rebreathed by the astronaut. The accumulation through time depends on many variables: the amount absorbed by the astronaut, the amount produced by the astronaut (between 0.28 and 0.34 moles per hour per kilogram)[1], the amount that enters the suit from contaminated O (sub 2), the amount removed through suit leak, the free volume of the suit, and the O (sub 2) partial pressure[2], just to list a few. Contamination of the EMU O (sub 2) supply with no greater than 1 part per million CO was the motivation for empirical measurements from CO pulse oximetry (SpCO) as well as mathematical modeling of the EMU as a rebreather for CO. Methods: We developed a first-order differential mixing equation as well as an iterative method to compute CO accumulation in the EMU. Pre-post measurements of SpCO (Rad-57, Masimo Corporation) from EMU ground training and on-orbit extravehicular activities (EVAs) were collected. Results: Initial modeling without consideration of the astronaut as a sink but only the source of CO showed that after 8 hours breathing 100 percent O (sub 2) with a 10 milliliter per minute (760 millimeters Hg at 21 degrees Centigrade standard) suit leak, an endogenous production rate of 0.23 moles per hour per kilogram for a 70 kilogram person with 42 liters (1.5 cubic feet) free suit volume resulted in a peak CO partial pressure (pCO) of 0.047 millimeters Hg at 4.3 pounds per square inch absolute (222 millimeters Hg). Preliminary results based on a 2008 model[3] with consideration of the astronaut as a sink and source of CO suggests that most of the rebreathed CO stays bound to hemoglobin and myoglobin and; therefore, pCO only increased to 0.002 millimeters Hg in the EMU. Hemoglobin saturation after 8 hours was an insignificant 0.4 percent compared to about 4 percent for cigarette smokers in the general population. This preliminary modeling result supplements 11 pre-post index finger SpCO measurements from EMU ground training (mean 0.5 percent versus 1 percent, probability equal to 0.41 from paired t-test) and 10 on-orbit pre-post EVAs (mean 1.5 percent versus 1.1 percent, probability equal to 0.17 from paired t-test) that showed no consistent increase, at least no increase outside the accuracy of the oximeter (1 percent display resolution with plus or minus 3 percent Standard Deviation). Discussion: Simulations continue, but a preliminary conclusion is that rebreathing endogenous CO accumulating in the EMU is not a serious medical issue during EVA. The absence of CO poisoning signs or symptoms following hundreds of EVAs is also good empirical evidence that corroborates the limited SpCO measurements and preliminary modeling results.

Conkin, J.↗
NASA NTRS2017

Effects of Acute Exposures to Carbon Dioxide upon Cognitive Functions

Carbon dioxide (CO2) originates from human metabolism and typically remains about 10-fold higher in concentration on the International Space Station (ISS) than at the earth's surface. There have been recurring complaints by crew members of episodes of "mental viscosity" adversely affecting their performance, and there is evidence from the ISS that associates CO2 levels with reports of headaches by crewmembers. Consequently, flight rules have been employed to control CO2 below 3 mm Hg, which is well below the existing Spacecraft Maximum Allowable Concentration (SMAC) of 10 mm Hg for 24-hour exposures, and 5.3 mm Hg for exposures of 7 to 180 days. Headaches, while sometime debilitating themselves, are also symptoms that can provide evidence that physiological defense mechanisms have been breached, and there is evidence that CO2 has effects at levels below the threshold for headaches. This concern appears to be substantiated in reports that CO2 at concentrations below 2 mm Hg substantially reduced some cognitive functions that are associated with the ability to make complex decisions in conditions that are characterized by volatility, uncertainty, complexity, ambiguity, and delayed feedback. These are conditions that could be encountered by crews in off-nominal situations or during the first missions beyond low earth orbit. Therefore, we set out to determine if decision-making under volatile, uncertain, confusing and ambiguous circumstances, where feedback is delayed or absent, is correlated with low levels of CO2 during acute exposures (several hours) in crew-like subjects and to determine if additional cognitive domains are sensitive to concentrations of CO2 at, or below, current ISS levels by using a test battery that is currently available onboard ISS. We enrolled 22 volunteers (8 females, 14 males) between the ages of 30-55 (38.8 +/- 7.0) years whose training and professional experience reflect that of the astronaut corps. Subjects were divided among 4 study groups. Exposures occurred in the 20-foot environmental chamber in Bldg 7 at JSC. Each group was exposed to each of four concentrations of CO2 (600, 1200, 2500, and 5000 ppm), and the exposure order was balanced across the groups which were randomly assigned to 4 possible complete exposure orders. Study participants and investigators were blinded to the exposure order. Each exposure lasted 4 hours and occurred on the same day each week for 4 consecutive weeks. Testing included the Strategic Management Simulation (SMS) methodology and the Cognition battery of psychometric measures that are being utilized aboard the ISS. Subjects participated in a familiarization session one week prior to the start of exposure sessions. Each exposure session followed the schedule noted in Figure 1 below. On the morning of each exposure, subjects completed the Cognition battery in a conference room at indoor ambient CO2 levels. Subjects then entered the exposure chamber and were acclimated to the environment for 15 minutes before completing another round of the Cognition battery. After a 20 minute rest, subject completed the approx.80 minute SMS. Subjects were allowed another 20 minute rest period before completing the final Cognition test battery in the exposure chamber. Subjects then returned to the conference room where they completed one final round of Cognition. Data from both testing methodologies are currently being analyzed and will be presented. Study investigators have not yet been unblinded to the coded exposure concentrations, but preliminary results suggest differences.

Ryder, V. E.↗
DOE OSTI2022

Wave energy converter buoy with variable geometry

A nonlinear control design technique capitalizes on a wave energy converter comprising a shaped buoy having a variable geometry wave energy. For example, the shaped buoy can have an hourglass (HG) geometry having a variable cone or steepness angle. The HG buoy is assumed to operate in the heave motion of the wave. The unique interaction between the HG buoy and the wave creates a nonlinear cubic storage effect that produces actual energy storage or reactive power during operation. A multi-frequency Bretschneider spectrum wave excitation input was simulated for the HG design both with constant and varying steepness angle profiles which demonstrated further increased power generation with changing sea states for the variable design.

Wilson, David G.↗
DOE OSTI2020

Materials Data on NiHg by Materials Project

HgNi is Tetraauricupride structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Ni is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Ni–Hg bond lengths are 2.73 Å. Hg is bonded in a body-centered cubic geometry to eight equivalent Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoHg by Materials Project

HoHg is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Ho is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Ho–Hg bond lengths are 3.22 Å. Hg is bonded in a body-centered cubic geometry to eight equivalent Ho atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2Hg3(GeS4)2 by Materials Project

K2Hg3(GeS4)2 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. K1+ is bonded in a 7-coordinate geometry to seven S2- atoms. There are a spread of K–S bond distances ranging from 3.27–3.56 Å. There are three inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded in a distorted linear geometry to four S2- atoms. There are two shorter (2.38 Å) and two longer (3.32 Å) Hg–S bond lengths. In the second Hg2+ site, Hg2+ is bonded in a see-saw-like geometry to four S2- atoms. There are two shorter (2.47 Å) and two longer (2.90 Å) Hg–S bond lengths. In the third Hg2+ site, Hg2+ is bonded in a distorted see-saw-like geometry to four S2- atoms. There are two shorter (2.47 Å) and two longer (2.88 Å) Hg–S bond lengths. Ge4+ is bonded in a tetrahedral geometry to four S2- atoms. There are a spread of Ge–S bond distances ranging from 2.19–2.28 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to two equivalent K1+, one Hg2+, and one Ge4+ atom. In the second S2- site, S2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Hg2+, and one Ge4+ atom. In the third S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent K1+, two Hg2+, and one Ge4+ atom. In the fourth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+, two Hg2+, and one Ge4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaHg by Materials Project

CaHg is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Ca is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Ca–Hg bond lengths are 3.30 Å. Hg is bonded in a body-centered cubic geometry to eight equivalent Ca atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cd2Hg by Materials Project

HgCd2 is Titanium Disilicide-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Hg is bonded in a distorted q6 geometry to ten equivalent Cd atoms. There are two shorter (2.95 Å) and eight longer (3.22 Å) Hg–Cd bond lengths. Cd is bonded in a 10-coordinate geometry to five equivalent Hg and five equivalent Cd atoms. There are one shorter (2.95 Å) and four longer (3.22 Å) Cd–Cd bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GdHg by Materials Project

GdHg is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Gd is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Gd–Hg bond lengths are 3.26 Å. Hg is bonded in a body-centered cubic geometry to eight equivalent Gd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NdHg by Materials Project

NdHg is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Nd is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Nd–Hg bond lengths are 3.33 Å. Hg is bonded in a body-centered cubic geometry to eight equivalent Nd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrHg by Materials Project

PrHg is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Pr is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Pr–Hg bond lengths are 3.35 Å. Hg is bonded in a body-centered cubic geometry to eight equivalent Pr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ScHg by Materials Project

ScHg is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Sc is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Sc–Hg bond lengths are 3.06 Å. Hg is bonded in a body-centered cubic geometry to eight equivalent Sc atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TlHg3 by Materials Project

Hg3Tl is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Hg is bonded in a square co-planar geometry to four equivalent Tl atoms. All Hg–Tl bond lengths are 3.45 Å. Tl is bonded to twelve equivalent Hg atoms to form a mixture of corner and face-sharing TlHg12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TmHg by Materials Project

TmHg is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Tm is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Tm–Hg bond lengths are 3.19 Å. Hg is bonded in a body-centered cubic geometry to eight equivalent Tm atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hg2Rh by Materials Project

RhHg2 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Rh is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Rh–Hg bond lengths are 2.79 Å. Hg is bonded in a 4-coordinate geometry to four equivalent Rh atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hg3(PO4)2 by Materials Project

Hg3(PO4)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded to five O2- atoms to form distorted HgO5 square pyramids that share corners with five PO4 tetrahedra and edges with two equivalent HgO5 square pyramids. There are a spread of Hg–O bond distances ranging from 2.16–2.61 Å. In the second Hg2+ site, Hg2+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Hg–O bond distances ranging from 2.10–2.62 Å. In the third Hg2+ site, Hg2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Hg–O bond distances ranging from 2.13–2.99 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent HgO5 square pyramids. There are a spread of P–O bond distances ranging from 1.53–1.58 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent HgO5 square pyramids. There are a spread of P–O bond distances ranging from 1.54–1.58 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Hg2+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Hg2+ and one P5+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Hg2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two Hg2+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to two Hg2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to two Hg2+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Hg2+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Hg2+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgHg by Materials Project

MgHg is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Mg is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Mg–Hg bond lengths are 3.03 Å. Hg is bonded in a body-centered cubic geometry to eight equivalent Mg atoms.

36 MATERIALS SCIENCE↗