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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Antisense oligodeoxynucleotide inhibition of a swelling-activated cation channel in osteoblast-like osteosarcoma cells

By patch-clamp analysis, we have shown that chronic, intermittent mechanical strain (CMS) increases the activity of stretch-activated cation channels of osteoblast-like UMR-106.01 cells. CMS also produces a swelling-activated whole-cell conductance (Gm) regulated by varying strain levels. We questioned whether the swelling-activated conductance was produced by stretch-activated cation channel activity. We have identified a gene involved in the increase in conductance by using antisense oligodeoxynucleotides (ODN) derived from the alpha 1-subunit genes of calcium channels found in UMR-106.01 cells (alpha1S, alpha1C, and alpha1D). We demonstrate that alpha 1C antisense ODNs abolish the increase in Gm in response to hypotonic swelling following CMS. Antisense ODNs to alpha1S and alpha1D, sense ODNs to alpha1C, and sham permeabilization had no effect on the conductance increase. In addition, during cell-attached patch-clamp studies, antisense ODNs to alpha1c completely blocked the swelling-activated and stretch-activated nonselective cation channel response to strain. Antisense ODNs to alpha1S treatment produced no effect on either swelling-activated or stretch-activated cation channel activity. There were differences in the stretch-activated and swelling-activated cation channel activity, but whether they represent different channels could not be determined from our data. Our data indicate that the alpha1C gene product is involved in the Gm and the activation of the swelling-activated cation channels induced by CMS. The possibility that swelling-activated cation channel genes are members of the calcium channel superfamily exists, but if alpha1c is not the swelling-activated cation channel itself, then its expression is required for induction of swelling-activated cation channel activity by CMS.

NASA Discipline Musculoskeletal↗
NASA NTRS2003

Swell Sleeves for Testing Explosive Devices

A method of testing explosive and pyrotechnic devices involves exploding the devices inside swell sleeves. Swell sleeves have been used previously for measuring forces. In the present method, they are used to obtain quantitative indications of the energy released in explosions of the devices under test. A swell sleeve is basically a thick-walled, hollow metal cylinder threaded at one end to accept a threaded surface on a device to be tested (see Figure 1). Once the device has been tightly threaded in place in the swell sleeve, the device-and-swell-sleeve assembly is placed in a test fixture, then the device is detonated. After the explosion, the assembly is removed from the test fixture and placed in a coordinate-measuring machine for measurement of the diameter of the swell sleeve as a function of axial position. For each axial position, the original diameter of the sleeve is subtracted from the diameter of the sleeve as swollen by the explosion to obtain the diametral swelling as a function of axial position (see Figure 2). The amount of swelling is taken as a measure of the energy released in the explosion. The amount of swelling can be compared to a standard amount of swelling to determine whether the pyrotechnic device functioned as specified.

Hinkel, Todd J.↗
NASA NTRS1994

Analysis and prediction of ocean swell using instrumented buoys

During the period 20-23 September 1990, the remnants of Supertyphoon Flo moved into the central North Pacific Ocean with sustained wind speeds of 28 m/s. The strong wind and large fetch area associated with this storm generated long-period swell that propagated to the west coast of North America. National Data Buoy Center moored-buoy stations, located in a network that ranged from the Gulf of Alaska to the California Bight, provided wave spectral estimates of the swell from this storm. The greatest dominant wave periods measured were approximately 20-25 s, and significant wave heights measured ranged from 3 to 8 m. Wave spectra from an array of three nondirectional buoys are used to find the source of the long-period swell. Directional wave spectra from a heave-pitch-roll buoy are also used to make an independent estimate of the source of the swell. The ridge-line method, using time-frequency contour plots of wave spectral energy density, is used to determine the time of swell generation, which is used with the appropriate surface pressure analysis to infer the swell generation area. The diagnosed sources of the swell are also compared with nowcasts from the Global Spectral Ocean Wave Model of the Fleet Numerical Oceanography Center. A simple method of predicting the propagation of ocean swell, by applying a simple kinematic model of wave propagation to the estimated point and time source, is demonstrated.

Mettlach, Theodore↗
NASA NTRS1985

Sea floor swells and mantle plumes

Most of the intraplate oceanic hot spots are located on the crest of broad topographic swells in the sea floor. These swells have Gaussian shaped profiles, with up to 1.6 km of relief and half widths of 200 to 300 km. Swells are accompanied by positive geoid height anomalies with amplitudes of 6 to 8 m. In the Atlantic and Pacific basins swells cover an area equal to 10% of the Earth's surface. Next to boundary layer contraction, swells are the most important cause of uplift and subsidence in oceanic lithosphere. Calculation of buoyancy supported topography and geoid height were combined with uplift data from laboratory experiments to assess whether sea floor swell can be produced by mantle plumes. The critical constraints are: (1) swell topographic profiles; (2) geoid height/topographic height ratios; and (3) uplift rates, estimated to be 0.2 km/ma.

Olson, P.↗
NASA NTRSDate not supplied

A Study of the Swelling and Bursting of the High Pressure Coupling (HPC) of a Two-Stage Light Gas Gun

• Need for data at muzzle velocities of 7.0 km/s and above to simulate impacts of space debris and naturally occurring meteoroids • The two-stage light gas gun is a well known way of achieving these velocities • There is a danger of significant swelling and even bursting of the HPC (high pressure coupling). • A consistent picture of the swelling and bursting of the HPCs of two Ames two-stage light gas guns is developed, based on the following: 1. Experimental measurements of the swelling and bursting of the HPCs of two two-stage light gas guns. 2. Stress-strain calculations of the swelling and bursting of thick walled steel tubes. 3. Experimental measurements swelling and bursting of thick walled steel tubes. 4. CFD calculations of the maximum pressures in the HPC of a two-stage light gas gun using the code LGGUN. • It is shown that model developed predicts swelling and bursting that agrees reasonably well with measured data. • Hence, it is suggested that the model could be used in the design of a two-stage light gas guns to assess the risk of swelling and bursting and to give maximum suggested operating conditions for an existing gun.

Ballistic Range↗
NASA NTRS1992

In vitro measurement of nucleus pulposus swelling pressure: A new technique for studies of spinal adaptation to gravity

Swelling of the intervertebral disc nucleus pulposus is altered by posture and gravity. We have designed and tested a new osmometer for in vitro determination of nucleus pulposus swelling pressure. The functional principle of the osmometer involves compressing a sample of nucleus pulposus with nitrogen gas until saline pressure gradients across a 0.45 microns Millipore filter are eliminated. Swelling pressure of both pooled dog and pooled pig lumbar disc nucleus pulposus were measured on the new osmometer and compared to swelling pressures determined using the equilibrium dialysis technique. The osmometer measured swelling pressures comparable to those obtained by the dialysis technique. This osmometer provides a rapid, direct, and accurate measurement of swelling pressure of the nucleus pulposus.

Hargens, A. R.↗
NASA NTRS2021

A Study of the Swelling and Bursting of the High Pressure Coupling (HPC) of a Two-Stage Light Gas Gun

A consistent picture of the swelling and bursting of the high pressure couplings (HPC) of two NASA Ames two-stage light gas guns is developed. The following information is used to construct the model. 1. Experimental measurements of the swelling and bursting of the HPCs of two two-stage light gas guns. 2. Stress-strain calculations of the swelling and bursting of thick walled steel tubes. 3. Experimental measurements swelling and bursting of thick walled steel tubes. 4. CFD calculations of the maximum pressures in the HPC of a two-stage light gas gun using the code LGGUN 5. Correlation of maximum HPC pressures and piston energies It is suggested that the techniques described herein could be used to assess the likelihood of swelling and bursting of the HPCs of various different two stage light gas guns.

David W Bogdanoff↗
NASA NTRSDate not supplied

A Study of the Swelling and Bursting of the High Pressure Coupling (HPC) of a Two-Stage Light Gas Gun

A consistent picture of the swelling and bursting of the high pressure couplings (HPC) of two NASA Ames two-stage light gas guns is developed. The following information is used to construct the model. 1. Experimental measurements of the swelling and bursting of the HPCs of two two-stage light gas guns. 2. Stress-strain calculations of the swelling and bursting of thick walled steel tubes. 3. Experimental measurements swelling and bursting of thick walled steel tubes. 4. CFD calculations of the maximum pressures in the HPC of a two-stage light gas gun using the code LGGUN It is suggested that the techniques described herein could be used to assess the likelihood of swelling and bursting of the HPCs of various different two stage light gas guns.

David W Bogdanoff↗
NASA NTRS1973

Theoretical analysis of swelling characteristics of cylindrical uranium dioxide fuel pins with a niobium - 1-percent-zirconium clad

The relations between clad creep strain and fuel volume swelling are shown for cylindrical UO2 fuel pins with a Nb-1Zr clad. These relations were obtained by using the computer code CYGRO-2. These clad-strain - fuel-volume-swelling relations may be used with any fuel-volume-swelling model, provided the fuel volume swelling is isotropic and independent of the clad restraints. The effects of clad temperature (over a range from 118 to 1642 K (2010 to 2960 R)), pin diameter, clad thickness and central hole size in the fuel have been investigated. In all calculations the irradiation time was 500 hours. The burnup rate was varied.

Saltsman, J. F.↗
NASA NTRS1979

On the remote detection of swell by satellite radar altimeter

A technique is developed and discussed which utilizes only significant wave height and wind speed measurements available from the GEOS-3 radar altimeter in real time to locate swell dominated regions of the earth's oceans. It is shown that reasonable agreement exists between the GEOS-3 map of the North Atlantic for 24 February 1976 and a map produced from hindcasted values of sea and swell obtained from the Special Projects Branch of the National Weather Service. Only data presently available from existing satellite radar altimeters are needed to map those areas of the oceans dominated by swell. It is concluded that the example given indicates that the decision boundary developed in this study to distinguish swell-dominated seas is a realistic choice.

Parsons, C. L.↗
NASA NTRS1987

The effect of a shallow low viscosity zone on the apparent compensation of midplate swells

A model for midplate swells is assumed where the swell topography is dynamically maintained by convection beneath a conducting lid. Using an idealized viscosity structure consisting of a low viscosity layer underneath the lid and overlying a constant viscosity region, the effect of the low viscosities, the layer thickness, and the Rayleigh number on the flow and on the inference of a compensation mechanism from the associated gravity, geoid, and topography anomalies is investigated. The calculations show that a simple plume model with stratified viscosity variations of less than two orders of magnitude near the surface can produce the range of depths of compensation seen at midplate swells. Shallow depths of compensation, therefore, cannot be used to argue against dynamic models for the formation of hot spot swells.

Robinson, Elizabeth M.↗
NASA NTRS1973

Unrestrained swelling of uranium-nitride fuel irradiated at temperatures ranging from 1100 to 1400 K (1980 to 2520 R)

Six fuel pins were assembled, encapsulated, and irradiated in the Plum Brook Reactor. The fuel pins employed uranium mononitride (UN) in a stainless steel (type 304L) clad. The pins were irradiated for approximately 4000 hours to burnups of about 2.0 atom percent uranium. The average clad surface temperature during irradiation was about 1100 K (1980 deg R). Since stainless steel has a very low creep strength relative to that of UN at this temperature, these tests simulated unrestrained swelling of UN. The tests indicated that at 1 percent uranium atom burnup the unrestrained diametrical swelling of UN is about 0.5, 0.8, and 1.0 percent at 1223, 1264, and 1306 K (2200, deg 2273 deg, and 2350 deg R), respectively. The tests also indicated that the irradiation induced swelling of unrestrained UN fuel pellets appears to be isotropic.

Rohal, R. G.↗
NASA NTRS1980

Thermal expansion and swelling of cured epoxy resin used in graphite/epoxy composite materials

The paper presents results of experiments in which the thermal expansion and swelling behavior of an epoxy resin system and two graphite/epoxy composite systems exposed to water were measured. It was found that the cured epoxy resin swells by an amount slightly less than the volume of the absorbed water and that the swelling efficiency of the water varies with the moisture content of the polymer. Additionally, the thermal expansion of cured epoxy resin that is saturated with water is observed to be more than twice that of dry resin. Results also indicate that cured resin that is saturated with 7.1% water at 95 C will rapidly increase in moisture content to 8.5% when placed in 1 C water. The mechanism for this phenomenon, termed reverse thermal effect, is described in terms of a slightly modified free-volume theory in conjunction with the theory of polar molecule interaction. Nearly identical behavior was observed in two graphite/epoxy composite systems, thus establishing that this behavior may be common to all cured epoxy resins.

Adamson, M. J.↗
NASA NTRS1988

Effect of a shallow low-viscosity zone on the formation of midplate swells

A finite-element numerical method is used here to analyze the effect of a low-viscosity zone on convection driven by heating from below in the upper mantle, in particular on the formation of midplate swells. The convective temperature and velocity solutions are calculated for different combinations of the viscosity in the top layer, the fluid layer thicknesses, and the Rayleigh number based on the viscosity in the bottom layer. The temperature solutions are used to calculate the geoid, topography, and heat flow anomalies, the elastic plate thickness, the depth of compensation, and an upper bound on the uplift time that result from the flow. The results are compared to data at the Hawaii, Bermuda, Cape Verde, and Marquesas swells. The magnitudes and the trend with age are consistent with theoretical and other estimates of the viscosity variation in the shallow upper mantle. Convective models can therefore explain the uplift and observed anomalies at midplate swells.

Robinson, E. M.↗
NASA NTRS1989

Geoid height versus topography for oceanic plateaus and swells

Gridded geoid height data (Marsh et al.l, 1986) and gridded bathymetry data (Van Wykhouse, 1973) are used to estimate the average compensation depths of 53 oceanic swells and plateaus. The relationship between geoid height and topography is examined using Airy and thermal compensation models. It is shown that geoid height is linearly related to topography between wavelengths of 400 and 4000 m as predicted by isostatic compensation models. The geoid/topography ratio is dependent on the average depth of compensation. The intermediate geoid/topography ratios of most thermal swells are interpreted as a linear combination of the decaying thermal swell signature and that of the persisting Airy-compensated volcanic edifice.

Sandwell, David T.↗
NASA NTRS1990

Evolution of midplate hotspot swells: Numerical solutions

The evolution of midplate hotspot swells on an oceanic plate moving over a hot, upwelling mantle plume is numerically simulated. The plume supplies a Gaussian-shaped thermal perturbation and thermally-induced dynamic support. The lithosphere is treated as a thermal boundary layer with a strongly temperature-dependent viscosity. The two fundamental mechanisms of transferring heat, conduction and convection, during the interaction of the lithosphere with the mantle plume are considered. The transient heat transfer equations, with boundary conditions varying in both time and space, are solved in cylindrical coordinates using the finite difference ADI (alternating direction implicit) method on a 100 x 100 grid. The topography, geoid anomaly, and heat flow anomaly of the Hawaiian swell and the Bermuda rise are used to constrain the models. Results confirm the conclusion of previous works that the Hawaiian swell can not be explained by conductive heating alone, even if extremely high thermal perturbation is allowed. On the other hand, the model of convective thinning predicts successfully the topography, geoid anomaly, and the heat flow anomaly around the Hawaiian islands, as well as the changes in the topography and anomalous heat flow along the Hawaiian volcanic chain.

Liu, Mian↗
NASA NTRS1989

Decreased swelling pressure of rat nucleus pulposus associated with simulated weightlessness

Data are presented on the effects of actual and simulated weightlessness on the swelling pressure of nucleus pulposus in rats exposed to 12.5 days of flight aboard Cosmos 1887 or to seven days of tail suspension, respectively. The flight-exposed rats were adapted to normal gravity for over 50 hrs prior to sacrifice and tissue harvesting. In the experiments with flight-exposed rats, swelling pressures were 690, 675, and 622 mm Hg for flight rats, synchronous controls, and vivarium controls, respectively. In experiments with simulated weightlessness, swelling pressures were 295, 610, and 527 mm Hg for tail-suspended rats, cage controls, and vivarium controls, respectively, suggesting that fluid moves into the disc during seven days of simulated weightlessness.

Hargens, Alan R.↗
NASA NTRS1993

Conceptual design of a device to measure hand swelling in a micro-gravity environment

In the design of pressurized suits for use by astronauts in space, proper fit is an important consideration. One particularly difficult aspect of the suit design is the design of the gloves. If the gloves of the suit do not fit properly, the grip strength of the astronaut can be decreased by as much as fifty percent. These gloves are designed using an iterative process and can cost over 1.5 million dollars. Glove design is further complicated by the way the body behaves in a micro-gravity environment. In a micro-gravity setting, fluid from the lower body tends to move into the upper body. Some of this fluid collects in the hands and causes the hands to swell. Therefore, a pair of gloves that fit well on earth may not fit well when they are used in space. The conceptual design process for a device which can measure the swelling that occurs in the hands in a micro-gravity environment is described. This process involves developing a specifications list and function structure for the device and generating solution variants for each of the sub functions. The solution variants are then filtered, with the variants that violate any of the specifications being discarded. After acceptable solution variants are obtained, they are combined to form design concepts. These design concepts are evaluated against a set of criteria and the design concepts are ranked in order of preference. Through this process, the two most plausible design concepts were an ultrasonic imaging technique and a laser mapping technique. Both of these methods create a three dimensional model of the hand, from which the amount of swelling can be determined. In order to determine which of the two solutions will actually work best, a further analysis will need to be performed.

Hysinger, Christopher L.↗