4,821 research outputs found
Anion permselective membrane
The synthesis and fabrication of polymeric anion permselective membranes for redox systems are discussed. Variations of the prime candidate anion membrane formulation to achieve better resistance and/or lower permeability were explored. Processing parameters were evaluated to lower cost and fabricate larger sizes. The processing techniques to produce more membranes per batch were successfully integrated with the fabrication of larger membranes. Membranes of about 107 cm x 51 cm were made in excellent yield. Several measurements were made on the larger sample membranes. Among the data developed were water transport and transference numbers for these prime candidate membranes at 20 C. Other work done on this system included characterization of a number of specimens of candidate membranes which had been returned after service lives of up to sixteen months. Work with new polymer constituents, with new N.P.'s, catalysts and backing fabrics is discussed. Some work was also done to evaluate other proportions of the ingredients of the prime candidate system. The adoption of a flow selectivity test at elevated temperature was explored
Anion permselective membrane
The efforts on the synthesis of polymer anion redox membranes were mainly concentrated in two areas, membrane development and membrane fabrication. Membrane development covered the preparation and evaluation of experimental membranes systems with improved resistance stability and/or lower permeability. Membrane fabrication covered the laboratory scale production of prime candidate membranes in quantities of up to two hundred and sizes up to 18 inches x 18 inches (46 cm x 46 cm). These small (10 in x 11 in) and medium sized membranes were mainly for assembly into multicell units. Improvements in processing procedures and techniques for preparing such membrane sets lifted yields to over 90 percent
Lyman alpha line shapes from electron impact H2 dissociative processes in the Jovian auroral zone
Over the past two years several Lyman alpha line profile spectra of Jupiter were obtained using the International Ultraviolet Explorer (IUE) telescope. Several different regions of the planet were observed including the auroral zone, the low and mid latitudes, and the equatorial region which includes the Lyman alpha bulge region. These results have presented a very interesting picture of atomic hydrogen on Jupiter with explanations that range from ion outflow in the auroral zone to large thermospheric winds at low and mid latitudes. New data are needed to address the outstanding questions. Almost certainly, high resolution spectra from the Hubble Space Telescope will play a role in new observations. Better data also require better models, and better models require new laboratory data as inputs. The purpose of this program is two-fold: (1) to introduce a method by which new laboratory electron impact measurements of H2 dissociation can be used to calculate both the slow and fast H(S-2) and H(P-2) fragments in an H2 atmosphere; and (2) to determine the predicted Lyman alpha line shape that would result from electron impact production of these dissociative fragments in the Jovian auroral zone
First observation of Jupiter by XMM-Newton
We present the first X-ray observation of Jupiter by XMM-Newton. Images taken
with the EPIC cameras show prominent emission, essentially all confined to the
0.2-2.0 keV band, from the planet's auroral spots; their spectra can be
modelled with a combination of unresolved emission lines of highly ionised
oxygen (OVII and OVIII), and a pseudo-continuum which may also be due to the
superposition of many weak lines. A 2.8 sigma enhancement in the RGS spectrum
at 21-22 A (~0.57 keV) is consistent with an OVII identification. Our spectral
analysis supports the hypothesis that Jupiter's auroral emissions originate
from the capture and acceleration of solar wind ions in the planet's
magnetosphere, followed by X-ray production by charge exchange. The X-ray flux
of the North spot is modulated at Jupiter's rotation period. We do not detect
evidence for the ~45 min X-ray oscillations observed by Chandra more than two
years earlier. Emission from the equatorial regions of the planet's disk is
also observed. Its spectrum is consistent with that of scattered solar X-rays.Comment: 7 pages, 9 figures; to be published in Astronomy & Astrophysic
Assessment of bovine uterine artery hemodynamics using Doppler ultrasound and a computer model
Early diagnosis of pregnancy is an important component of efficient management in the cattle breeding industry. Using current techniques there is no practical test which reliably detects pregnancy at less than 30 days after conception. This project was initiated with a general objective to investigate the feasibility of using Doppler ultrasound for early pregnancy diagnosis in cattle (between 15 and 30 days after conception);A suitable probe was designed and developed for collecting Doppler blood velocity waveforms from the bovine uterine artery using rectal palpation. A portable, microcomputer-based, velocity waveform analyzer was constructed which allows for collection and analysis of blood velocity waveforms in the field. To obtain some basic hemodynamic data related to uterine artery blood flow, pulsed Doppler, electromagnetic flowmeter, and continuous wave Doppler data were collected;A computer model of flow in the uterine artery was developed to study, theoretically, the effect of changes in various parameters on the blood velocity waveform;With regard to pregnancy diagnosis, the following points are made: (1) It is feasible to obtain velocity waveforms through rectal palpation using the finger probe which was designed for this study. (2) The data can be processed using the portable, microcomputer-based, velocity waveform analyzer. (3) It may be possible to diagnose pregnancy in cows using Doppler blood velocity waveforms, but due to the fact that several factors, in addition to mean flow, appear to affect the shape of the waveforms, further work is needed to establish suitable criteria
Towards a Theory of Critical Consciousness: A New Direction for the Development of Instructional and Supervisory Leaders
COVID-19 and the demand for racial justice caused the dark underbelly of white supremacy to be laid bare during 2020. These events call for a reexamination of the ontological and epistemological frameworks in academe and specifically within the field of educational leadership. The legacy of white supremacist ideology prevails as the existing and accepted ontological and epistemological perspectives of history offered in PreK-12 through post-secondary education. The political, economic, and social context highlights the need for instructional and supervisory leaders to be culturally responsive school leaders. This requires that programs preparing these leaders must grapple with and problematize the existing narratives purported in PreK-12 and post-secondary education; and recognize that racism, implicit bias, discrimination, and anti-Blackness are foundational issues in the field. Reimagining preparation programs by incorporating critical theories and liberatory praxis to support the development of culturally responsive instructional and supervisory leaders is imperative
Superthermal electron processes in the upper atmosphere of Uranus: Aurora and electroglow
Strong ultraviolet emissions from the upper atmosphere of Uranus suggest that both auroral and electroglow phenomena are of significant aeronomical consequences in the structure of the upper atmosphere. Combined modeling and data analysis were performed to determine the effect of electroglow and auroral phenomena on the global heat and atomic hydrogen budgets in the Uranus upper atmosphere. The results indicate that the auroral and electroglow heat sources are not adequate to explain the high exospheric temperature observed at Uranus, but that the atomic hydrogen supplied by these processes is more than sufficient to explain the observations. The various superthermal electron distributions modeled have significantly different efficiencies for the various processes such as UV emission, heating, ionization, and atomic hydrogen production, and produce quite different H2 band spectra. However, additional information on the UV spectra and global parameters is needed before modeling can be used to distinguish between the possible mechanisms for electroglow
Study of space battery accelerated testing techniques. Phase 1 report. Survey of testing methods applicable to space battery evaluation
Testing methods applicable to space battery evaluation - literature surve
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