Use of micropatterned adhesive surfaces for control of cell behavior
No abstract available
Non-NASA Center↗
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Results for “cell behavior”
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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Cell behavior in simulated microgravity: a comparison of results obtained with RWV and RPM
No abstract available
Bioreactors↗
Size distribution of retrovirally marked lineages matches prediction from population measurements of cell cycle behavior
Mechanisms that regulate neuron production in the developing mouse neocortex were examined by using a retroviral lineage marking method to determine the sizes of the lineages remaining in the proliferating population of the ventricular zone during the period of neuron production. The distribution of clade sizes obtained experimentally in four different injection-survival paradigms (E11-E13, E11-E14, E11-E15, and E12-E15) from a total of over 500 labeled lineages was compared with that obtained from three models in which the average behavior of the proliferating population [i.e., the proportion of cells remaining in the proliferative population (P) vs. that exiting the proliferative population (Q)] was quantitatively related to lineage size distribution. In model 1, different proportions of asymmetric, symmetric terminal, and symmetric nonterminal cell divisions coexisted during the entire developmental period. In model 2, the developmental period was divided into two epochs: During the first, asymmetric and symmetric nonterminal cell divisions occurred, but, during the second, asymmetric and symmetric terminal cell divisions occurred. In model 3, the shifts in P and Q are accounted for by changes in the proportions of the two types of symmetric cell divisions without the inclusion of any asymmetric cell divisions. The results obtained from the retroviral experiments were well accounted for by model 1 but not by model 2 or 3. These findings demonstrate that: 1) asymmetric and both types of symmetric cell divisions coexist during the entire period of neurogenesis in the mouse, 2) neuron production is regulated in the proliferative population by the independent decisions of the two daughter cells to reenter S phase, and 3) neurons are produced by both asymmetric and symmetric terminal cell divisions. In addition, the findings mean that cell death and/or tangential movements of cells in the proliferative population occur at only a low rate and that there are no proliferating lineages "reserved" to make particular laminae or cell types. Copyright 2002 Wiley-Liss, Inc.
NASA Discipline Developmental Biology↗
Cell and defect behavior in lithium-counterdoped solar cells
Some n(+)/p cells in which lithium is introduced as a counterdopant, by ion-implantation, into the cell's boron-doped p-region were studied. To determine if the cells radiation resistance could be significantly improved by lithium counterdoping. Defect behavior was related to cell performance using deep level transient spectroscopy. Results indicate a significantly increased radiation resistance for the lithium counterdoped cells when compared to the boron doped 1 ohm-cm control cell. The increased radiation resistance of the lithium counterdoped cells is due to the complexing of lithium with divacancies and boron. It is speculated that complexing with oxygen and single vacancies also contributes to the increased radiation resistance. Counterdoping silicon with lithium results in a different set of defects.
Weinberg, I.↗
An analysis of the elastic behavior of a capacitance load cell.
Elastic behavior of load cell operating on variable capacitance principle designed to fit spaces restricted in one dimension
LOAD DISTRIBUTION↗
Development of Low Cost Contacts to Silicon Solar Cells
Commercial electroless Cu solutions were used. Satisfactory adhesion (and fairly good cell performance) resulted from the use of thin layers of barrier metals such as Au, Cr or Pd. In these tests, photoresist masks were used to contact silicon P-type slices with diffused N+ and alloyed P+ surfaces; and electrolytic Cu solution was used to build up the contact thickness to provide good cell behavior. In addition some cells with evaporated Cr-Cu contacts were also made (along with evaporated Ti-Pd-Ag contacts as controls), with the intention of subjecting cells to gradually increasing heat-treatments, to determine whether Cu causes the cells to be inherently unstable.
Iles, P. A.↗
Mathematical modeling of solid oxide fuel cells
Development of predictive techniques, with regard to cell behavior, under various operating conditions is needed to improve cell performance, increase energy density, reduce manufacturing cost, and to broaden utilization of various fuels. Such technology would be especially beneficial for the solid oxide fuel cells (SOFC) at it early demonstration stage. The development of computer models to calculate the temperature, CD, reactant distributions in the tubular and monolithic SOFCs. Results indicate that problems of nonuniform heat generation and fuel gas depletion in the tubular cell module, and of size limitions in the monolithic (MOD 0) design may be encountered during FC operation.
Lu, Cheng-Yi↗
Modeling of high efficiency solar cells under laser pulse for power beaming applications
Solar cells have been used to convert sunlight to electrical energy for many years and also offer great potential for non-solar energy conversion applications. Their greatly improved performance under monochromatic light compared to sunlight, makes them suitable as photovoltaic (PV) receivers in laser power beaming applications. Laser beamed power to a PV array receiver could provide power to satellites, an orbital transfer vehicle, or a lunar base. Gallium arsenide (GaAs) and indium phosphide (InP) solar cells have calculated efficiencies of more than 50 percent under continuous illumination at the optimum wavelength. Currently high power free-electron lasers are being developed which operate in pulsed conditions. Understanding cell behavior under a laser pulse is important in the selection of the solar cell material and the laser. An experiment by NAsA lewis and JPL at the AVLIS laser facility in Livermore, CA presented experimental data on cell performance under pulsed laser illumination. Reference 5 contains an overview of technical issues concerning the use of solar cells for laser power conversion, written before the experiments were performed. As the experimental results showed, the actual effects of pulsed operation are more complicated. Reference 6 discusses simulations of the output of GaAs concentrator solar cells under pulsed laser illumination. The present paper continues this work, and compares the output of Si and GaAs solar cells.
Jain, Raj K.↗
An accelerated test design for use with synchronous orbit
The Naval Weapons Support Center at Crane, Indiana has conducted a large scale accelerated test of 6.0 Ah Ni-Cd cells. Data from the Crane test have been used to develop an equation for the description of Ni-Cd cell behavior in geosynchronous orbit. This equation relates the anticipated time to failure for a cell in synchronous orbit to temperature and overcharge rate sustained by the cell during the light period. A test design is suggested which uses this equation for setting test parameters for future accelerated testing.
Mcdermott, P. P.↗
Spectral response measurements with white light bias
The spectral response of solar cells such as the CdS/Cu2S cell is non-linear with distinct quenching and enhancement bands. One possible technique to produce standardized solar efficiencies is to fold in spectral response with a standard solar spectrum. The spectral response of a cell was measured in a way which matched cell behavior under white light illumination. A technique was developed to measure the response of a cell to low intensity chopped monochromatic light while the cell is also illuminated with a white light bias corresponding to AMI.
Devaney, W.↗
Superoxide Dismutase Protects Osteoprogenitors from Irradiation with Low-LET but Not High-LET Species
Ionizing radiation-induced bone loss appears to be a two-stage process: first an early increase in pro-resorption cytokines and increased bone resorption by osteoclasts, followed by a decrease in bone formation by osteoblasts. This results in a net loss of mass in mineralized bone tissue. The molecular mechanisms underlying the imbalance in bone remodeling caused by exposure to radiation are not fully understood. We hypothesized that the radiation-induced rise in reactive oxygen species (ROS) damages osteoblast progenitors, leading to a decrease in number and activity of differentiated progeny. We have shown that a diet high in antioxidant capacity prevents radiation-induced bone loss in adult mice (Schreurs et al. 2016) by reducing the early increase in pro-resotption cytokines. Here, we investigated the damaging effects of radiation exposure on cells in the osteoblast lineage, testing if addition of the exogenous antioxidant enzyme, superoxide dismutase (SOD) can mitigate radiation damage. Osteoprogenitors were grown in vitro from the marrow of 16wk old, male C57Bl/6 mice. Cells were irradiated 3 days after plating (day 0) with either gamma (Cs-137, 0.1-5Gy) or iron (Fe-56, 600 MeV/n, 0.5-2Gy), and then grown until day 10. SOD or vehicle was added 2 hours before irradiation (SOD at 200U/ml), twice a day and up to day 5, for a total of 2 days treatment. Cell behavior was assessed by: (a) colony number (counted on day 7), (b) DNA content (surrogate for cell number) to assess cell growth (percent change between day 3 and day 10) and (c) alkaline phosphatase activity (osteoblast differentiation marker). Results show that SOD protected cells from the adverse effects of low-LET ionizing radiation, but not high-LET radiation. These novel results provide an interesting platform to explore further diverse effects and damages caused by low-LET and high-LET, pointing toward different mechanisms and possible intervention strategies for radiation-induced bone loss.
superoxide dismutase↗
Superoxide Dismutase Protects Osteoprogenitors from Irradiation with Low-LET but Not High-LET Species
Ionizing radiation-induced bone loss appears to be a two-stage process: first an early increase in pro-resorption cytokines and increased bone resorption by osteoclasts, followed by a decrease in bone formation by osteoblasts. This results in a net loss of mass in mineralized bone tissue. The molecular mechanisms underlying the imbalance in bone remodeling caused by exposure to radiation are not fully understood. We hypothesized that the radiation-induced rise in reactive oxygen species (ROS) damages osteoblast progenitors, leading to a decrease in number and activity of differentiated progeny. We have shown that a diet high in antioxidant capacity prevents radiation-induced bone loss in adult mice (Schreurs et al. 2016) by reducing the early increase in pro-resotption cytokines. Here, we investigated the damaging effects of radiation exposure on cells in the osteoblast lineage, testing if addition of the exogenous antioxidant enzyme, superoxide dismutase (SOD) can mitigate radiation damage. Osteoprogenitors were grown in vitro from the marrow of 16-week-old, male C57Bl6 mice. Cells were irradiated 3 days after plating (day 0) with either gamma (137Cs, 0.1-5Gy) or iron (56Fe, 600 MeVn, 0.5-2Gy), and then grown until day 10. SOD or vehicle was added 2 hours before irradiation (SOD at 200Uml), twice a day and up to day 5, for a total of 2 days treatment. Cell behavior was assessed by: (a) colony number (counted on day 7), (b) DNA content (surrogate for cell number) to assess cell growth (percent change between day 3 and day 10) and (c) alkaline phosphatase activity (osteoblast differentiation marker). Results show that SOD protected cells from the adverse effects of low-LET(Linear Energy Transfer) ionizing radiation, but not high-LET radiation. These novel results provide an interesting platform to explore further diverse effects and damages caused by low-LET and high-LET, pointing toward different mechanisms and possible intervention strategies for radiation-induced bone loss.
osteoblasts↗
Electrolyte management considerations in modern nickel hydrogen and nickel cadmium cell and battery designs
In the early 1980's the NASA Lewis group addressed the topic of designing nickel hydrogen cells for LEO applications. As published in 1984, the design addressed the topics of gas management, liquid management, plate expansion, and the recombination of oxygen during overcharge. This design effort followed principles set forth in an earlier Lewis paper that addressed the topic of pore size engineering. At about that same time, the beneficial effect on cycle life of lower electrolyte concentrations was verified by Hughes Aircraft as part of a Lewis funded study. A succession of life cycle tests of these concepts have been carried out that essentially verified all of this earlier work. During these past two decades, some of the mysteries involved in the active material of the nickel electrode have been resolved by careful research efforts carried out at several laboratories. At The Aerospace Corporation, Dr. Zimmerman has been developing a sophisticated model of an operating nickel hydrogen cell which will be used to model certain mechanisms that have contributed to premature failures in nickel hydrogen and nickel cadmium cells. During the course of trying to understand and model abnormal nickel hydrogen cell behaviors, we have noted that not enough attention has been paid to the potassium ion content in these cells, and more recently batteries. Several of these phenomenon have been well known in the area of alkaline fuel cells, but only recently have they been examined as they might impact alkaline cell designs. This paper will review three general areas where the potassium ion content can impact the performance and life of nickel hydrogen and nickel cadmium devices, Once these phenomenon are understood conceptually, the impact of potassium content on a potential cell design can be evaluated with the aid of an accurate model of an operating cell or battery. All three of these areas are directly related to the volume tolerance and pore size engineering aspects of the components used in the cell or battery design: (1) The gamma phase uptake of potassium ion can result in a lowering of the electrolyte concentration. This leads to a higher electrolyte resistance as well as electrolyte diffusional limitations on the discharge rate. This phenomenon will also impact the response of the cell to a reconditioning cycle. (2) The impact of low level shunt currents in multi-cell con figurations will result in the movement of potassium ion from one part of the battery to another. This will impact the electrolyte volume/vapor pressure relationships within the cell or battery. (3) The transport of water vapor from place to place under the driving force of a tempetature gradient has already impacted cells for the case where water vapor is condensed on a colder cell wall. The paper will explore the convective and diffusive movement of gases saturated with water vapor from a warmer plate pack to a cooler one - both with and without liquid communication.
Thaller, L. H.↗
Biomedical Science and Technology on the International Space Station - Benefits for Humanity (Ciencia Y Tecnologia Biomedica En La Estacion Espacial Internacional - Beneficios Para La Humanidad)
The International Space Station is a unique laboratory for performing investigations that affect human health both in space and on Earth. During its time in orbit, the space station has enabled research that is providing a better understanding of many aspects of human health including aging, trauma, disease and environmental impacts. Driven by the need to support astronaut health, several biological and human physiological investigations have yielded important results that we on Earth can also benefit from. These results include new ways to mitigate bone loss, insights into bacterial behavior, and innovative wound-healing techniques. Advances in telemedicine, disease models, psychological stress response systems, nutrition and cell behavior are just a few more examples of the benefits that have been gained from applying studies in orbit to human health back on Earth.
Love, John E.↗
Density and fluence dependence of lithium cell damage and recovery characteristics
Experimental results on lithium-containing solar cells point toward the lithium donor density gradient dN sub L/dw as being the crucial parameter in the prediction of cell behavior after irradiation by electrons. Recovery measurements on a large number of oxygen-rich and oxygen-lean lithium cells have confirmed that cell recovery speed is directly proportional to the value of the lithium gradient for electron fluences. Gradient measurements have also been correlated with lithium diffusion schedules. Results have shown that long diffusion times (25 h) with a paint-on source result in large cell-to-cell variations in gradient, probably due to a loss of the lithium source with time.
Faith, T. J.↗
Mechanical behavior in living cells consistent with the tensegrity model
Alternative models of cell mechanics depict the living cell as a simple mechanical continuum, porous filament gel, tensed cortical membrane, or tensegrity network that maintains a stabilizing prestress through incorporation of discrete structural elements that bear compression. Real-time microscopic analysis of cells containing GFP-labeled microtubules and associated mitochondria revealed that living cells behave like discrete structures composed of an interconnected network of actin microfilaments and microtubules when mechanical stresses are applied to cell surface integrin receptors. Quantitation of cell tractional forces and cellular prestress by using traction force microscopy confirmed that microtubules bear compression and are responsible for a significant portion of the cytoskeletal prestress that determines cell shape stability under conditions in which myosin light chain phosphorylation and intracellular calcium remained unchanged. Quantitative measurements of both static and dynamic mechanical behaviors in cells also were consistent with specific a priori predictions of the tensegrity model. These findings suggest that tensegrity represents a unified model of cell mechanics that may help to explain how mechanical behaviors emerge through collective interactions among different cytoskeletal filaments and extracellular adhesions in living cells.
NASA Discipline Cell Biology↗
PV Technology for Low Intensity, Low Temperature (LILT) Applications
As a result of the recent NASA emphasis on smaller, lower cost space missions, PV is now being considered for a number of missions operating at solar distances of 3 AU or greater. In the past, many of these missions would utilize an RTG (radioisotope thermoelectric generator). Historically, silicon solar cell behavior at these distances has been compromised by a number of mechanisms including shunting, nonohmic back contacts, and the 'broken knee' curve shape. The former two can usually be neglected for modern silicon cells, but the latter has not been eliminated. This problem has been identified with localized diffusion at the top contact/silicon interface which leads to structural changes at the local junction. This is believed to create a resistive metal-semiconductor-like (MSL) interface in parallel with the junction which results in the characteristic forms of the LILT (low intensity, low temperature) 'broken knee'. This paper discusses a TaSiN contact barrier that will prevent the MSL structure in the junction.
spacecraft power LILT low temperature low intensit↗
(abstract) PV Technology for Low Intensity, Low Temperature (LILT) Applications
As a result of the recent NASA emphasis on smaller, lower cost space missions, PV is now being considered for a number of missions operating at solar distances of 3 AU or greater. In the past, many of these missions would utilize an RTG (radioisotope thermoelectric generator). Historically, silicon solar cell behavior at these distances has been compromised by a number of mechanisms including shunting, nonohmic back contacts, and the 'broken knee' curve shape. The former two can usually be neglected for modern silicon cells, but the latter has not been eliminated. This problem has been identified with localized diffusion at the top contact/silicon interface which leads to structural changes at the local junction. This is believed to create a resistive metal-semiconductor-like (MSL) interface in parallel with the junction which results in the characteristic forms of the LILT (low intensity, low temperature) 'broken knee'. This paper discusses a TaSiN contact barrier that will prevent the MSL structure in the junction.
spacecraft power LILT low temperature low intensit↗