Statistics and dynamics of procaryotic cell populations.
Cell population mathematical theory, predicting statistical and dynamic behavior of cells from analysis of cellular and subcellular structure and function
Fredrickson, A. G.↗
SEARCH · Engineering Papers
Results for “cell analysis”
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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Procedure for analysis of nickel-cadmium cell materials
Quality control procedures include analyses on electrolyte, active materials, and separators for nickel cadmium cell materials. Tests range from the visual/mechanical inspection of cells to gas sampling, electrolyte extract, electrochemical tests, and physical measurements.
Halpert, G.↗
Nickel cadmium cell composite reliability model
Ni-Cd battery reliability has become a critical design parameter with the increasing need for longer life and optimally designed secondary battery power systems in space as well as in more mundane applications. It is the purpose of this paper to present a state-of-the-art Ni-Cd cell reliability model as a function of cumulative cyclic operation, cell temperature and cyclic depth-of-discharge. In addition, a simple and convenient cell failure analysis technique will be presented in which the reliability, the distribution, and the distribution parameters can be determined by visual inspection.
Kirsch, W. W.↗
Silicon solar cell process development, fabrication and analysis
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Yoo, H. I.↗
Silicon solar cell process development, fabrication and analysis
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Yoo, H. I.↗
Silicon solar cell process development, fabrication and analysis
For UCP Si, randomly selected wafers and wafers cut from two specific ingots were studied. For the randomly selected wafers, a moderate gettering diffusion had little effect. Moreover, an efficiency up to 14% AMI was achieved with advanced processes. For the two specific UCP ingots, ingot #5848-13C displayed severe impurity effects as shown by lower 3sc in the middle of the ingot and low CFF in the top of the ingot. Also the middle portions of this ingot responded to a series of progressively more severe gettering diffusion. Unexplained was the fact that severely gettered samples of this ingot displayed a negative light biased effect on the minority carrier diffusion length while the nongettered or moderately gettered ones had the more conventional positive light biased effect on diffusion length. On the other hand, ingot C-4-21A did not have the problem of ingot 5848-13C and behaved like to the randomly selected wafers. The top half of the ingot was shown to be slightly superior to the bottom half, but moderate gettering helped to narrow the gap.
Iles, P. A.↗
Failure Analysis of Nickel-hydrogen Cell Subjected to Simulated Low Earth Orbit Cycling
A nickel-hydrogen cell completed 10,080 simulated low earth orbit charge/discharge cycles at depths-of-discharge ranging from 50 to 80 percent prior to failure. The cell is of the Air Force design, rated at 50 ampere-hours, 8.9 cm (3.5 inches) in diameter. Upon disassembly, the end of the polysulfone core supporting the electrode stack was found to have fractured. This allowed the electrode stack to expand. A massive short was found at the inner diameter of the electrodes centered roughly at plate set 34 to 37 from the positive end of the electrode stack. The damaged area extended through approximately one third of the electrode stack, with the effect becoming progressively less with distance from plate set 34 to 37. Measured thicknesses of the positive plates were significantly greater than the initial specification values. The postulated cause of failure is that positive plate growth caused fracture of the shoulder from the end of the polysulfone core on which the electrodes are mounted. The electrode stack relieved and pressure points were created at the area near the inner diameter of the plates at the tab attachment. A short occurred at a pressure point between opposing plates and propagated to other electrode sets due to thermal and mechanical stresses caused by the short.
Mueller, V. C.↗
Relationship between the blue response and open-circuit voltage of high performance silicon solar cells
The relationship between the response at blue wavelengths and the open-circuit voltage of high performance silicon solar cells with a virtually 'transparent' emitter is analyzed. It is shown that a one-dimensional cell model cannot simultaneously model the optical collection properties and operating characteristics of such cells. The analysis highlights the importance of surface conditions and shows that previous conclusions regarding bounds on Auger coefficients imposed by correlating these parameters must be treated with caution.
Green, M. A.↗
Results of Analysis on the Design Variable Cells
Sealed Nickel-Cadmium aerospace cells play a very important role in the mission of the satellite. There has been a constant effort to improve the cycle life, energy density, and reliability of these cells by many manufacturers and users. The Design Variable Cell Program is one systematic approach started by NASA in collaboration with General Electric (GE) towards that goal. Nine important designs were selected for evaluation. Fifty-two nickel-cadmium cells each of 12 Ah nominal capacity manufactured by GE were sent to the Navel weapons Support Center for evaluation of different design variables with which these cells were built.
Vasanth, K. L.↗
Reliability and engineering of thin-film photovoltaic modules
Objectives were to: examine thin-film cell attributes that influence module performance and reliability, explore the lessons and applicability of crystalline-silicon module technology to thin-film modules, review the current status of thin-film module technologies, and identify problem areas and needed research. A major need is to separate the effects and resons for reversible degradatin from nonreversible degradation. Amorphous-silicon (a-Si) reliability investigations are focusing on exploratory research investigations, accelerated Arrhenius-type testing of a-Si cells, real-time outdoor exposure testing of a-Si cells, cell failure analysis, and failure mechanism research. Studies included the reduction in strength of glass by high temperature depositions on glass and laser scribing, encapsulation materials development needs, and the testing of modules. The new materials and processes in thin-film modules will require a delinquent reliability effort, including: establishment of mechanism-specific reliability goals; quantification of mechanism parameter dependencies; prediction of expected long-term degradation; identification of cost-effective solutions; and testing and failure analysis of trial solutions.
Royal, E. L.↗
Objective method for analysis and tracking of convective cells as seen by radar
A special method has been developed for the study of cells that are embedded in convective rain systems. This method consists of a package of computer programs that use pattern recognition techniques on three-dimensional digital radar data to identify the rain cells, track them with time, and calculate their properties. The product of the computations is a comprehensive database of physically meaningful properties of rain cells, which can be used to infer the internal structure and the dynamics of convective rain systems. The cell-tracking method has been applied to the summer convective clouds of south Florida for the following purposes: (1) derivation of the relationship between the echo top height and the precipitation characteristics (e.g., area, water yield, rain intensity and duration of the rain cells); (2) study of the microphysical behaviorof cumulus clouds in relation to their cell properties; (3) evaluation of the effect of seeding on cumulus clouds on the cell scale; and (4) examination of cloud-to-ground lightning discharges in relation to convective cell intensity. The cell-tracking method is also currently being used in rain enhancement projects in Texas, Israel, and South Africa. The cell-tracking method, its products and their use in meteorological research are described in this paper.
Rosenfeld, Daniel↗
Improved defect analysis of Gallium Arsenide solar cells using image enhancement
A new technique has been developed to capture, digitize, and enhance the image of light emission from a forward biased direct bandgap solar cell. Since the forward biased light emission from a direct bandgap solar cell has been shown to display both qualitative and quantitative information about the solar cell's performance and its defects, signal processing techniques can be applied to the light emission images to identify and analyze shunt diodes. Shunt diodes are of particular importance because they have been found to be the type of defect which is likely to cause failure in a GaAs solar cell. The presence of a shunt diode can be detected from the light emission by using a photodetector to measure the quantity of light emitted at various current densities. However, to analyze how the shunt diodes affect the quality of the solar cell the pattern of the light emission must be studied. With the use of image enhancement routines, the light emission can be studied at low light emission levels where shunt diode effects are dominant.
Kilmer, Louis C.↗
Dose rate and repair effects on cell damage in earth orbit
Radiobiology experiments performed in space will encounter continuous exposures to the cosmic rays and fractionated exposures to trapped protons which accumulate to several hundred dose fractions in a few weeks. Using models of track structure and cellular kinetics combined with models of the radiation environment and radiation transport, we consider calculations of damage rates for cell cultures. Analysis of the role of repair mechanisms for space exposures for the endpoints of survival and transformation is emphasized.
Cucinotta, F. A.↗
Illuminating Cell Biology
NASA's Ames Research Center awarded Ciencia, Inc., a Small Business Innovation Research contract to develop the Cell Fluorescence Analysis System (CFAS) to address the size, mass, and power constraints of using fluorescence spectroscopy in the International Space Station's Life Science Research Facility. The system will play an important role in studying biological specimen's long-term adaptation to microgravity. Commercial applications for the technology include diverse markets such as food safety, in situ environmental monitoring, online process analysis, genomics and DNA chips, and non-invasive diagnostics. Ciencia has already sold the system to the private sector for biosensor applications.
Source record↗
Compaction agent clarification of microbial lysates
Recombinant proteins are often purified from microbial lysates containing high concentrations of nucleic acids. Pre-purification steps such as nuclease addition or precipitation with polyethyleneimine or ammonium sulfate are normally required to reduce viscosity and to eliminate competing polyanions before anion exchange chromatography. We report that small polycationic compaction agents such as spermine selectively precipitate nucleic acids during or after Escherichia coli lysis, allowing DNA and RNA to be pelleted with the insoluble cell debris. Analysis by spectrophotometry and protein assay confirmed a significant reduction in the concentration of nucleic acids present, with preservation of protein. Lysate viscosity is greatly reduced, facilitating subsequent processing. We have used 5mM spermine to remove nucleic acids from E. coli lysate in the purification of a hexahistidine-tagged HIV reverse transcriptase.
NASA Discipline Environmental Health↗
Modelling and Analysis of a Regenerative Fuel Cell Propulsion System for a High Altitude Long Endurance UAV
In the search to bridge current gaps in surveillance and communication technologies, a new type of, aircraft is currently undergoing design. The idea of a High Altitude Long Endurance (HALE) aircraft is already a few decades old, but has only recently become realizable. A relay and collector of information at altitudes of 65,000 feet and higher could greatly improve standards of data exchange, homeland security, and research of the air, land and sea. NASA, as a major force in propulsion research, is exploring methods of powering an autonomous aircraft for days, weeks, or even months without refueling. Such a task requires not only high energy density, but also the ability to make use of renewable energy sources to regenerate power. Hydrogen is one of the most energy dense fuels available. Fuel cells make use of hydrogen by harnessing the energy released as it combines with oxygen to produce electricity and water. Fuel cells are envisioned to occupy future propulsion systems in cooperation with solar cells where the photovoltaic arrays harness sunlight into power which can electrolize the water byproduct into reusable hydrogen and oxygen. Modeling this type of system requires adequate assumptions of support hardware and daily transients in operation. The performance of a regenerative fuel cell propulsion system lies in the flight characteristics (altitude, density, temperature, latitude, etc.). Each subsystem is defined by many parameters which can be varied across wide ranges. Statistical and probabilistic analyses bring forward a wealth of information that can be utilized in the design process. This is necessary since the required technologies are relatively young and barely, if yet, capable. Once the modeling is complete, a design space exploration of this highly constrained scenario can be utilized to find the optimal design. The model will become an interactive environment with which experiments and tests can be run. When linked
Simpson, Mike B.↗
Human Adaptation Genetic Response Suites: Toward New Interventions and Countermeasures for Spaceflight
Genetic response suites in human lymphocytes in response to microgravity are important to identify and further study in order to augment human physiological adaptation to novel environments. Emerging technologies, such as DNA micro array profiling, have the potential to identify novel genes that are involved in mediating adaptation to these environments. These genes may prove to be therapeutically valuable as new targets for countermeasures, or as predictive biomarkers of response to these new environments. Human lymphocytes cultured in lg and microgravity analog culture were analyzed for their differential gene expression response. Different groups of genes related to the immune response, cardiovascular system and stress response were then analyzed. Analysis of cells from multiple donors reveals a small shared set that are likely to be essential to adaptation. These three groups focus on human adaptation to new environments. The shared set contains genes related to T cell activation, immune response and stress response to analog microgravity.
Sundaresan, A.↗
Brazing of Stainless Steel to Yttria-Stabilized Zirconia Using Gold-Based Brazes for Solid Oxide Fuel Cell Applications
Two gold-base active metal brazes (gold-ABA and gold-ABA-V) were evaluated for oxidation resistance to 850 C, and used to join yttria-stabilized zirconia (YSZ) to a corrosion-resistant ferritic stainless steel for possible use in solid oxide fuel cells. Thermogravimetric analysis and optical microscopy and scanning electron microscopy coupled with energy-dispersive spectroscopy were used to evaluate the braze oxidation behavior, and microstructure and composition of the YSZ/braze/steel joints. Both gold-ABA and gold-ABA-V exhibited nearly linear oxidation kinetics at 850 C, with gold-ABA-V showing faster oxidation than gold-ABA. Both brazes produced metallurgically sound YSZ/steel joints due to chemical interactions of Ti and V with the YSZ and steel substrates.
Singh, M.↗