Search NASA⌕ Search

SEARCH · Search NASA

Results for “cell wall structure”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Design, evaluation, and fabrication of low-cost composite blades for intermediate-size wind turbines

Low cost approaches for production of 60 ft long glass fiber/resin composite rotor blades for the MOD-OA wind turbine were identified and evaluated. The most cost-effective configuration was selected for detailed design. Subelement and subscale specimens were fabricated for testing to confirm physical and mechanical properties of the composite blade materials, to develop and evaluate blade fabrication techniques and processes, and to confirm the structural adequacy of the root end joint. Full-scale blade tooling was constructed and a partial blade for tool and process tryout was built. Then two full scale blades were fabricated and delivered to NASA-LeRC for installation on a MOD-OA wind turbine at Clayton, New Mexico for operational testing. Each blade was 60 ft. long with 4.5 ft. chord at root end and 2575 lbs weight including metal hub adapter. The selected blade configuration was a three cell design constructed using a resin impregnated glass fiber tape winding process that allows rapid wrapping of primarily axially oriented fibers onto a tapered mandrel, with tapered wall thickness. The ring winder/transverse filament tape process combination was used for the first time on this program to produce entire rotor blade structures. This approach permitted the complete blade to be wound on stationary mandrels, an improvement which alleviated some of the tooling and process problems encountered on previous composite blade programs.

Weingart, O.↗
NASA NTRS1978

Foam For Filtering

Like nature's honeycomb, foam is a structure of many-sided cells, apparently solid but actually only three percent material and 97 percent air. Foam is made by a heat-producing chemical reaction which expands a plastic material in a manner somewhat akin to the heat-induced rising of a loaf of bread. The resulting structure of interconnected cells is flexible yet strong and extremely versatile in applicati6n. Foam can, for example, be a sound absorber in one form, while in another it allows sound to pass through it. It can be a very soft powder puff material and at the same time a highly abrasive scrubber. A sampling of foam uses includes stereo speaker grilles, applying postage meter ink, filtering lawnmower carburetor air; deadening noise in trucks and tractors, applying cosmetics, releasing fabric softener and antistatic agents in home clothes dryers, painting, filtering factory heating and ventilating systems, shining shoes, polishing cars, sponge-mopping floors, acting as pre-operative surgical scrubbers-the list is virtually limitless. The process by which foam is made produces "windows," thin plastic membranes connecting the cell walls. Windowed foam is used in many applications but for certain others-filtering, for example-it is desirable to have a completely open network. Scott Paper Company's Foam Division, Chester, Pennsylvania, improved a patented method of "removing the windows," to create an open structure that affords special utility in filtering applications. NASA technology contributed to Scott's improvement.

Source record↗
NASA NTRS1998

Media Compositions for Three-Dimensional Mammalian Tissue Growth under Microgravity Culture Conditions

Normal mammalian tissue and the culturing process has been developed for the three groups of organ, structural and blood tissue.The cells are grown in vitro under microgravity culture conditions and form three dimensional cells aggregates with normal cell function. The microgravity culture conditions may be microgravity or simulated microgravity created in a horizontal rotating wall culture vessel.

Goodwin, Thomas J.↗
NASA NTRS2015

Fracture of Carbon Nanotube - Amorphous Carbon Composites: Molecular Modeling

Carbon nanotubes (CNTs) are promising candidates for use as reinforcements in next generation structural composite materials because of their extremely high specific stiffness and strength. They cannot, however, be viewed as simple replacements for carbon fibers because there are key differences between these materials in areas such as handling, processing, and matrix design. It is impossible to know for certain that CNT composites will represent a significant advance over carbon fiber composites before these various factors have been optimized, which is an extremely costly and time intensive process. This work attempts to place an upper bound on CNT composite mechanical properties by performing molecular dynamics simulations on idealized model systems with a reactive forcefield that permits modeling of both elastic deformations and fracture. Amorphous carbon (AC) was chosen for the matrix material in this work because of its structural simplicity and physical compatibility with the CNT fillers. It is also much stiffer and stronger than typical engineering polymer matrices. Three different arrangements of CNTs in the simulation cell have been investigated: a single-wall nanotube (SWNT) array, a multi-wall nanotube (MWNT) array, and a SWNT bundle system. The SWNT and MWNT array systems are clearly idealizations, but the SWNT bundle system is a step closer to real systems in which individual tubes aggregate into large assemblies. The effect of chemical crosslinking on composite properties is modeled by adding bonds between the CNTs and AC. The balance between weakening the CNTs and improving fiber-matrix load transfer is explored by systematically varying the extent of crosslinking. It is, of course, impossible to capture the full range of deformation and fracture processes that occur in real materials with even the largest atomistic molecular dynamics simulations. With this limitation in mind, the simulation results reported here provide a plausible upper limit on achievable CNT composite properties and yield some insight on the influence of processing conditions on the mechanical properties of CNT composites.

Jensen, Benjamin D.↗
NASA NTRS1972

Effects of spanwise rotation on the structure of two-dimensional fully developed turbulent channel flow.

Experiments on fully developed turbulent flow in a channel which is rotating at a steady rate about a spanwise axis are described. The Coriolis force components in the region of two-dimensional mean flow affect both local and global stability. Three stability-related phenomena were observed or inferred: (1) the reduction (increase) of the rate of wall-layer streak bursting in locally stabilized (destabilized) wall layers; (2) the total suppression of transition to turbulence in a stabilized layer; (3) the development of large-scale roll cells on the destabilized side of the channel by growth of a Taylor-Gortler vortex instability. Local effects of rotational stabilization, such as reduction of the turbulent stress in wall layers, can be related to the local Richardson number in a simple way. This paper not only investigates this effect, but also, by methods of flow visualization, exposes some of the underlying structure changes caused by rotation.-

Johnston, J. P.↗
NASA NTRS1993

Cultured normal mammalian tissue and process

Normal mammalian tissue and the culturing process has been developed for the three groups of organ, structural and blood tissue. The cells are grown in vitro under microgravity culture conditions and form three dimensional cell aggregates with normal cell function. The microgravity culture conditions may be microgravity or simulated microgravity created in a horizontal rotating wall culture vessel.

Goodwin, Thomas J.↗
NASA NTRS1996

Method for Producing Non-Neoplastic, Three Dimensional, Mammalian Tissue and Cell Aggregates Under Microgravity Culture Conditions and the Products Produced Therefrom

Normal mammalian tissue and the culturing process has been developed for the three groups of organ, structural, and blood tissue. The cells are grown in vitro under microgravity culture conditions and form three dimensional cells aggregates with normal cell function. The microgravity culture conditions may be microgravity or simulated microgravity created in a horizontal rotating wall culture vessel.

Goodwin, Thomas J.↗
NASA NTRS1998

Media Compositions for Three Dimensional Mammalian Tissue Growth Under Microgravity Culture Conditions

Normal mammalian tissue and the culturing process has been developed for the three groups of organ, structural and blood tissue. The cells are grown in vitro under microgravity culture conditions and form three dimensional cells aggregates with normal cell function. The microgravity culture conditions may be microgravity or simulated microgravity created in a horizontal rotating wall culture vessel.

Goodwin, Thomas J.↗
NASA NTRS1999

Production of Normal Mammalian Organ Culture Using a Medium Containing Mem-Alpha, Leibovitz L 15, Glucose Galactose Fructose

Normal mammalian tissue and the culturing process has been developed for the three groups of organ, structural and blood tissue. The cells are grown in vitro under micro- gravity culture conditions and form three dimensional cells aggregates with normal cell function. The microgravity culture conditions may be microgravity or simulated microgravity created in a horizontal rotating wall culture vessel. The medium used for culturing the cells, especially a mixture of epithelial and mesenchymal cells contains a mixture of Mem-alpha and Leibovits L15 supplemented with glucose, galactose and fructose.

Goodwin, Thomas J.↗
NASA NTRS2001

Development of Aluminum Composites for a Rocket Engine's Lightweight Thrust Cell

The Aerospike liquid fueled rocket engine for the X-33 aerospace vehicle consists of several thrust cells, which can comprise as much as 25% of the engine weight. The interior wall of the thrust cell chamber is exposed to high temperature combustion products and must be cooled by using liquid hydrogen. Ultimately, reducing engine weight would increase vehicle performance and allow heavier payload capabilities. Currently, the thrust cell's structural jacket and manifolds are made of stainless steel 347, which can potentially be replaced by a lighter material such as an Aluminum (Al) Metal Matrix Composites (MMC). Up to 50% weight reduction can be expected for each of the thrust cell chambers using particulate SiC reinforced Al MMC. Currently, several Al MMC thrust cell structural jackets have been produced, using cost-effective processes such as gravity casting and plasma spray deposition, to demonstrate MMC technology readiness for NASA's advanced propulsion systems.

Lee, Jonathan A.↗
NASA NTRS1974

Surface recrystallization theory of the wear of copper in liquid methane

Copper was subjected to sliding against 440C in liquid methane. The normal load range was from 1/4 to 2 kilograms, and the sliding velocity range was from 3.1 to 25 meters per second. Over this range of experimental parameters, the wear rate of the copper rider was found to be proportional to the sliding velocity squared and to the normal load. Transmission electron microscopy was used to study the dislocation structure in the copper very near the wear scar surface. It was found that near the wear scar surface, the microstructure was characterized by a fine-cell recrystallized zone in which individual dislocations could be distinguished in the cell walls. The interiors of the cells, about 0.5 micrometer in diameter, were nearly dislocation free. Below the recrystallized layer was a zone that was intensely cold worked by the friction process. With increasing depth, this intensely cold worked zone gradually became indistinguishable from the partially cold worked bulk of the copper, representative of the initial condition of the material.

Bill, R. C.↗
NASA NTRS1990

Development of the Statocyst in Aplysia Californica: Observations on Statoconial Development - Part 1

The gravity receptor organs of gastropod molluscs, such as Aplysia californica, are bilateral paired statocysts, which contain dense statoconia within a fluid-filled cyst. Gravitational forces on the statoconia are sensed through their interaction with ciliated mechanoreceptor cells in the wall of the cyst. Larval Aplysia contain a single statolith within each statocyst; when the animals grow to a critical size, they begin producing multiple statoconia, a process that continues throughout life. The number of statoconia is highly correlated with animal weight but poorly correlated with age, indicating that stone production is related to total metabolism. The single statolith has an amorphous internal structure whereas the multiple statoconia have calcification deposited on concentric layers of membrane or matrix protein. The statolith appears to be produced within the cyst lumen but the multiple statoconia are produced within supporting cells between the receptor cells. Large adult animals have statoconia larger than those in early post-metamorphic animals which have just started producing multiple stones. The maximum statocyst diameter at which the receptor-cell cilia can suspend the statolith in the center of the cyst lumen is 45 micrometers; production of multiple stones begins when the cyst reaches this size. The mechanisms by which statoconia production is initiated and controlled are discussed.

Wiederhold, Michael L.↗
NASA NTRS2006

NASA Tech Briefs, June 2006

Topics covered include: Magnetic-Field-Response Measurement-Acquisition System; Platform for Testing Robotic Vehicles on Simulated Terrain; Interferometer for Low-Uncertainty Vector Metrology; Rayleigh Scattering for Measuring Flow in a Nozzle Testing Facility; "Virtual Feel" Capaciflectors; FETs Based on Doped Polyaniline/Polyethylene Oxide Fibers; Miniature Housings for Electronics With Standard Interfaces; Integrated Modeling Environment; Modified Recursive Hierarchical Segmentation of Data; Sizing Structures and Predicting Weight of a Spacecraft; Stress Testing of Data-Communication Networks; Framework for Flexible Security in Group Communications; Software for Collaborative Use of Large Interactive Displays; Microsphere Insulation Panels; Single-Wall Carbon Nanotube Anodes for Lithium Cells; Tantalum-Based Ceramics for Refractory Composites; Integral Flexure Mounts for Metal Mirrors for Cryogenic Use; Templates for Fabricating Nanowire/Nanoconduit- Based Devices; Measuring Vapors To Monitor the State of Cure of a Resin; Partial-Vacuum-Gasketed Electrochemical Corrosion Cell; Theodolite Ring Lights; Integrating Terrain Maps Into a Reactive Navigation Strategy; Reducing Centroid Error Through Model-Based Noise Reduction; Adaptive Modeling Language and Its Derivatives; Stable Satellite Orbits for Global Coverage of the Moon; and Low-Cost Propellant Launch From a Tethered Balloon

Source record↗
NASA NTRS2010

Isolation of Resistance-Bearing Microorganisms

To better exploit the principles of gas transport and mass transport during the processes of cell seeding of 3D scaffolds and in vitro culture of 3D tissue engineered constructs, the oscillatory cell culture bioreactor provides a flow of cell suspensions and culture media directly through a porous 3D scaffold (during cell seeding) and a 3D construct (during subsequent cultivation) within a highly gas-permeable closed-loop tube. This design is simple, modular, and flexible, and its component parts are easy to assemble and operate, and are inexpensive. Chamber volume can be very low, but can be easily scaled up. This innovation is well suited to work with different biological specimens, particularly with cells having high oxygen requirements and/or shear sensitivity, and different scaffold structures and dimensions. The closed-loop changer is highly gas permeable to allow efficient gas exchange during the cell seeding/culturing process. A porous scaffold, which may be seeded with cells, is fixed by means of a scaffold holder to the chamber wall with scaffold/construct orientation with respect to the chamber determined by the geometry of the scaffold holder. A fluid, with/without biological specimens, is added to the chamber such that all, or most, of the air is displaced (i.e., with or without an enclosed air bubble). Motion is applied to the chamber within a controlled environment (e.g., oscillatory motion within a humidified 37 C incubator). Movement of the chamber induces relative motion of the scaffold/construct with respect to the fluid. In case the fluid is a cell suspension, cells will come into contact with the scaffold and eventually adhere to it. Alternatively, cells can be seeded on scaffolds by gel entrapment prior to bioreactor cultivation. Subsequently, the oscillatory cell culture bioreactor will provide efficient gas exchange (i.e., of oxygen and carbon dioxide, as required for viability of metabolically active cells) and controlled levels of fluid dynamic shear (i.e., as required for viability of shear-sensitive cells) to the developing engineered tissue construct. This bioreactor was recently utilized to show independent and interactive effects of a growth factor (IGF-I) and slow bidirectional perfusion on the survival, differentiation, and contractile performance of 3D tissue engineering cardiac constructs. The main application of this system is within the tissue engineering industry. The ideal final application is within the automated mass production of tissue- engineered constructs. Target industries could be both life sciences companies as well as bioreactor device producing companies.

Venkateswaran, Kasthuri, J.↗
NASA NTRS2010

Oscillating Cell Culture Bioreactor

To better exploit the principles of gas transport and mass transport during the processes of cell seeding of 3D scaffolds and in vitro culture of 3D tissue engineered constructs, the oscillatory cell culture bioreactor provides a flow of cell suspensions and culture media directly through a porous 3D scaffold (during cell seeding) and a 3D construct (during subsequent cultivation) within a highly gas-permeable closed-loop tube. This design is simple, modular, and flexible, and its component parts are easy to assemble and operate, and are inexpensive. Chamber volume can be very low, but can be easily scaled up. This innovation is well suited to work with different biological specimens, particularly with cells having high oxygen requirements and/or shear sensitivity, and different scaffold structures and dimensions. The closed-loop changer is highly gas permeable to allow efficient gas exchange during the cell seeding/culturing process. A porous scaffold, which may be seeded with cells, is fixed by means of a scaffold holder to the chamber wall with scaffold/construct orientation with respect to the chamber determined by the geometry of the scaffold holder. A fluid, with/without biological specimens, is added to the chamber such that all, or most, of the air is displaced (i.e., with or without an enclosed air bubble). Motion is applied to the chamber within a controlled environment (e.g., oscillatory motion within a humidified 37 C incubator). Movement of the chamber induces relative motion of the scaffold/construct with respect to the fluid. In case the fluid is a cell suspension, cells will come into contact with the scaffold and eventually adhere to it. Alternatively, cells can be seeded on scaffolds by gel entrapment prior to bioreactor cultivation. Subsequently, the oscillatory cell culture bioreactor will provide efficient gas exchange (i.e., of oxygen and carbon dioxide, as required for viability of metabolically active cells) and controlled levels of fluid dynamic shear (i.e., as required for viability of shear-sensitive cells) to the developing engineered tissue construct. This bioreactor was recently utilized to show independent and interactive effects of a growth factor (IGF-I) and slow bidirectional perfusion on the survival, differentiation, and contractile performance of 3D tissue engineering cardiac constructs. The main application of this system is within the tissue engineering industry. The ideal final application is within the automated mass production of tissue- engineered constructs. Target industries could be both life sciences companies as well as bioreactor device producing companies.

Freed, Lisa E.↗
NASA NTRS2009

Microfossils in Carbonaceous Meteorites

Microfossils of large filamentous trichomic prokaryotes have been detected during in-situ investigations of carbonaceous meteorites. This research has been carried out using the Field Emission Scanning Electron Microscope (FESEM) to examine freshly fractured interior surfaces of the meteorites. The images obtained reveal that many of these remains are embedded in the meteorite rock matrix. Energy Dispersive X-Ray Spectroscopy (EDS) studies establish that the filamentous microstructures have elemental compositions consistent with the meteorite matrix, but are often encased within carbon-rich electron transparent sheath-like structures infilled with magnesium sulfate. This is consistent with the taphonomic modes of fossilization of cyanobacteria and sulphur bacteria, since the life habits and processes of these microorganisms frequently result in distinctive chemical biosignatures associated with the properties of their cell-walls, trichomes, and the extracellular polymeric substances (EPS) of the sheath. In this paper the evidence for biogenicity presented includes detailed morphological and morphometric data consistent with known characteristics of uniseriate and multiseriate cyanobacteria. Evidence for indigeneity includes the embedded nature of the fossils and elemental compositions inconsistent with modern biocontaminants.

Hoover, Richard B.↗
NASA NTRS2006

Immune Response in Microgravity: Genetic Basis and Countermeasure Development Implications

Impairment of the immunity in astronauts and cosmonauts even in shortterm flights is a recognized risk. Longterm orbital space missions and anticipated interplanetary flights increase the concern for more pronounced effects on the immune system with potential clinical consequences. Studies in true and modeled microgravity (MG) have demonstrated that MG directly affects numerous lymphocyte functions. The purpose of this study was to screen for genes involved in lymphocytes response to modeled microgravity (MMG) that could explain the functional and structural changes observed earlier. The microgravity-induced changes in gene expression were analyzed by microarray DNA chip technology. CD3and IL2activated Tcells were cultured in 1g (static) and modeled microgravity (NASA Rotating Wall Vessel bioreactor) conditions for 24 hours. Total RNA was extracted using the RNeasy isolation kit (Qiagen, Valencia, CA). Microarray experiments were performed utilizing Affymetrix Gene Chips (U133A), allowing testing for 18,400 human genes. To decrease the biological variation and aid in detecting microgravity-associated changes, experiments were performed in triplicate using cells obtained from three different donors. Exposure to modeled microgravity resulted in alteration of 89 genes, 10 of which were upregulated and 79 down-regulated. Altered genes were categorized by their function, structural role and by association with metabolic and regulatory pathways. A large proportion was found to be involved in fundamental cellular processes: signal transduction, DNA repair, apoptosis, and multiple metabolic pathways. There was a group of genes directly related to immune and inflammatory responses (IL7R, granulysin, proteasome activator subunit 2, peroxiredoxin 4, HLADRA, lymphocyte antigen 75, IL18R and DOCK2 genes). Among these genes only one (IL7R) was upregulated, the rest were downregulated. The upregulation of the IL7 receptor gene was confirmed by RT PCR. Three genes with altered expression were identified in the apoptosis related group (Granzyme B, APO2 ligand and Beta3endonexin). All of them were downregulated. Gene expression changes in MG might appear pivotal in identifying potential molecular targets for countermeasure development. (Supported by NRA OLMSA02 and NSCORT NAG54072 grants).

Risin, Diana↗
NASA NTRS1976

Study of metabolism and energetics in hypogravity: Degenerative effects of prolonged hypogravity

The role of gravity in the formation of rigid, lignified plant cell walls hence to the development of the erect land plant body is examined. An experiment was proposed with a general hypothesis that a chosen plant, a dwarf marigold, would display degenerative changes in mechanical supportive systems under hypogravity because normal lignin-cellulose wall structure fails to develop. Observational and experimental results are given.

Siegel, S. M.↗