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Results for “Dielectric properties”

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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Cascade Dielectrophoretic Separation for Selective Enrichment of Polyhydroxybutyrate (PHB)-Producing Cyanobacterium Synechocystis sp. PCC 6803

Maintaining favorable biological productivities in photosynthetic biomanufacturing systems, especially when the risk of contamination with competing microbes is high, remains a challenge to achieve while maintaining economic feasibility. This study presents a dielectrophoresis (DEP)-based microfluidic approach for isolating a desired strain within a co-culture. The cyanobacterium Synechocystis sp. PCC 6803 (a strain capable of producing the bioplastic precursor polyhydroxybutyrate, or PHB) was enriched from mixed cultures containing the competing cyanobacterium Synechococcus elongatus PCC 7942 (which does not naturally produce PHB). A DEP cascade electrode system was established to increase purification efficiency through sequential enrichment, which leveraged inherent differences in cell morphology and dielectric properties, to achieve the selective separation of these strains under physiological conditions. A substantial increase in the relative abundance of PHB-producing cells was assessed by optical microscopy and flow cytometry characterization, confirming more than five-fold reduction of the Synechococcus fraction in the refined cell mix. The presented electrokinetic platform offers a scalable and effective approach for selectively enhancing desired microbial components within microbial biomanufacturing systems, leading towards improved product yields.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1969

Dielectric materials for use in thin-film capacitors

Investigation report presents details of dielectric properties of various metals measured at 300 degrees K for thermally evaporated oxides from 300 to 6000 A in thickness. It is relevant to the medium of integrated circuitry.

Carr, H. E.↗
NASA NTRS1971

Development of nonflammable potting compounds for spacecraft

The requirements for nonflammable potting compounds for use in spacecraft electric and electronic equipment are discussed. The development of a suitable nonflammable compound is described. Flammability testing and acceptance criteria for Apollo spacecraft are presented. The dielectric properties of various ceramic materials used as conformal coatings are examined.

Kline, H. F.↗
NASA NTRS1974

High voltage solar array experiments

The interaction between the components of a high voltage solar array and a simulated space plasma is studied to obtain data for the design of a high voltage solar array capable of 15kW at 2 to 16kV. Testing was conducted in a vacuum chamber 1.5-m long by 1.5-m diameter having a plasma source which simulated the plasma conditions existing in earth orbit between 400 nautical miles and synchronous altitude. Test samples included solar array segments pinholes in insulation covering high voltage electrodes, and plain dielectric samples. Quantitative data are presented in the areas of plasma power losses, plasma and high voltage induced damage, and dielectric properties. Limitations of the investigation are described.

Kennerud, K. L.↗
NASA NTRS1973

The 4-8 GHz Microwave Active and Passive Spectrometer (MAPS). Volume 1: Radar section

The performance characteristics of the radar section of the prototype 4-8 GHz Microwave Active and Passive Spectrometer system are reported. Active and passive spectral responses were measured of natural, cultivated, and human-made surfaces over the 4-18 GHz region of frequencies for look angles between zero and 70 degrees and for all possible linear polarization combinations. Soil and plant samples were collected to measure their dielectric properties and moisture content. The FORTRAN program for area calculation is provided.

Ulaby, F. T.↗
NASA NTRS1975

Microwave boundary conditions on the atmosphere and clouds of Venus

The dielectric properties of H2O/H2SO4 mixtures are deduced from the Debye equations and, for a well-mixed atmosphere, the structure of H2O and H2O/H2SO4 clouds is calculated. Various data on the planet together set an upper limit on the mixing ratio by number for H2O of about 0.001 in the lower Venus atmosphere, and for H2SO4 of about 0.00001. The polarization value of the real part of the refractive index of the clouds, the spectroscopic limits on the abundance of water vapor above the clouds, and the microwave data together set corresponding upper limits on H2O of approximately 0.0002 and on H2SO4 of approximately 0.000009. Upper limits on the surface density of total cloud constituents and of cloud liquid water are, respectively, about 0.1 g/sq cm and about 0.01 g/sq cm. The infrared opacities of 90 bars of CO2, together with the derived upper limits to the amounts of water vapor and liquid H2O/H2SO4, may be sufficient to explain the high surface temperatures through the greenhouse effect.

Rossow, W. B.↗
NASA NTRS1976

Thermal analysis of PMR-polyimides by dielectrometry

A preliminary study was conducted to determine the dielectric properties of glass fabric reinforced composites as influenced by the reactions occurring during the preparation of crosslinked polyimides by the PMR process. The variables studied included: formulated molecular weight, staging temperature and time; rate of temperature increase to cure temperature; and cure temperature and time. The changes of capacitance and, particularly, of dissipation factor were found to be strongly dependent on each of the variables studied.

Gluyas, R. E.↗
NASA NTRS1977

A system analysis of the 13.3 GHz scatterometer

The performance of the 13.3 GHz airborne scatterometer system which is used as a microwave remote sensor to detect moisture content of soil is analyzed with respect to its antenna pattern, the signal flow in the receiver data channels, and the errors in the signal outputs. The operational principle and the sensitivity of the system, as well as data handling are also described. The dielectric property of the terrain surface, as far as the scatterometer is concerned, is contained in the assumed forms of the functional dependence of the backscattering coefficient of the incident angle.

Wang, J. R.↗