176 research outputs found
AIRCRAFT NUCLEAR PROPULSION DEPARTMENT NUCLEAR SAFETY GUIDE
The limitations and operating techniques which were in effect at ANPD for the prevention of criticality accidents are summarized. The standards followed by the atomic industry were followed; however, the safe mass of U/sup 235/ moderated with beryllium oxide and hydrogeneous materials was based upon criticality experiments conducted at ANPD. Although the guide was primarily for the use of the ANPD nuclear safety control organization, it may also be of assistance to designers and operating management in maintaining nuclear safety. (auth
Solar parameters for modeling interplanetary background
The goal of the Fully Online Datacenter of Ultraviolet Emissions (FONDUE)
Working Team of the International Space Science Institute in Bern, Switzerland,
was to establish a common calibration of various UV and EUV heliospheric
observations, both spectroscopic and photometric. Realization of this goal
required an up-to-date model of spatial distribution of neutral interstellar
hydrogen in the heliosphere, and to that end, a credible model of the radiation
pressure and ionization processes was needed. This chapter describes the solar
factors shaping the distribution of neutral interstellar H in the heliosphere.
Presented are the solar Lyman-alpha flux and the solar Lyman-alpha resonant
radiation pressure force acting on neutral H atoms in the heliosphere, solar
EUV radiation and the photoionization of heliospheric hydrogen, and their
evolution in time and the still hypothetical variation with heliolatitude.
Further, solar wind and its evolution with solar activity is presented in the
context of the charge exchange ionization of heliospheric hydrogen, and in the
context of dynamic pressure variations. Also the electron ionization and its
variation with time, heliolatitude, and solar distance is presented. After a
review of all of those topics, we present an interim model of solar wind and
the other solar factors based on up-to-date in situ and remote sensing
observations of solar wind. Results of this effort will further be utilised to
improve on the model of solar wind evolution, which will be an invaluable asset
in all heliospheric measurements, including, among others, the observations of
Energetic Neutral Atoms by the Interstellar Boundary Explorer (IBEX).Comment: Chapter 2 in the planned "Cross-Calibration of Past and Present Far
UV Spectra of Solar System Objects and the Heliosphere", ISSI Scientific
Report No 12, ed. R.M. Bonnet, E. Quemerais, M. Snow, Springe
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AIRCRAFT NUCLEAR PROPULSION DEPARTMENT NUCLEAR SAFETY GUIDE
The limitations and operating techniques which were in effect at ANPD for the prevention of criticality accidents are summarized. The standards followed by the atomic industry were followed; however, the safe mass of U/sup 235/ moderated with beryllium oxide and hydrogeneous materials was based upon criticality experiments conducted at ANPD. Although the guide was primarily for the use of the ANPD nuclear safety control organization, it may also be of assistance to designers and operating management in maintaining nuclear safety. (auth
Sedimentology, petrology, and gas potential of the Brallier Formation: upper Devonian turbidite facies of the Central and Southern Appalachians
The Upper Devonian Brallier Formation of the central and southern Appalachian basin is a regressive sequence of siltstone turbidites interbedded with mudstones, claystones, and shales. It reaches 1000 meters in thickness and overlies basinal mudrocks and underlies deltaic sandstones and mudrocks. Facies and paleocurrent analyses indicate differences between the depositional system of the Brallier Formation and those of modern submarine fans and ancient Alpine flysch-type sequences. The Brallier system is of finer grain size and lower flow intensity. In addition, the stratigraphic transition from turbidites to deltaic sediments is gradual and differs in its facies succession from the deposits of the proximal parts of modern submarine fans. Such features as massive and pebbly sandstones, conglomerates, debris flows, and massive slump structures are absent from this transition. Paleocurrents are uniformly to the west at right angles to basin isopach, which is atypical of ancient turbidite systems. This suggests that turbidity currents had multiple point sources. The petrography and paleocurrents of the Brallier Formation indicate an eastern source of sedimentary and low-grade metasedimentary rocks with modern relief and rainfall. The depositional system of the Brallier Formation is interpreted as a series of small ephemeral turbidite lobes of low flow intensity which coalesced in time to produce a laterally extensive wedge. The lobes were fed by deltas rather than submarine canyons or upper fan channel systems. This study shows that the present-day turbidite facies model, based mainly on modern submarine fans and ancient Alpine flysch-type sequences, does not adequately describe prodeltaic turbidite systems such as the Brallier Formation. Thickly bedded siltstone bundles are common features of the Brallier Formation and are probably its best gas reservoir facies, especially when fracture porosity is well developed
Sedimentology of gas-bearing Devonian shales of the Appalachian Basin
The Eastern Gas Shales Project (1976-1981) of the US DOE has generated a large amount of information on Devonian shale, especially in the western and central parts of the Appalachian Basin (Morgantown Energy Technology Center, 1980). This report summarizes this information, emphasizing the sedimentology of the shales and how it is related to gas, oil, and uranium. This information is reported in a series of statements each followed by a brief summary of supporting evidence or discussion and, where interpretations differ from our own, we include them. We believe this format is the most efficient way to learn about the gas-bearing Devonian shales of the Appalachian Basin and have organized our statements as follows: paleogeography and basin analysis; lithology and internal stratigraphy; paleontology; mineralogy, petrology, and chemistry; and gas, oil, and uranium
EFFECTS OF MELATONIN ON LIPID PEROXIDATION INDUCED BY OXYGEN RADICALS
We here report the activity of the neurohormone melatonin (MLT) as a scavenger of free radicals in two different experimental models: (a) linoleic acid peroxidation initiated by different free radical-generating systems and (b) a multilamellar vesicle system composed of dilinoleoylphosphatidylcholine. In system (a) linoleic acid peroxidation, induced by either the water-soluble initiator 2,2'-azobis (2-amidinopropane) dihydrochloride (ABAP) or Fe2+-EDTA addition to 2.6 mM linoleic acid dispersed in SDS-phosphate buffer, was evaluated as the formation of conjugated dienes, measured spectrophotometrically at 236 nm. MLT did not reduce the rate of peroxidation induced by ABAP, but did reduce, in a concentration-dependent fashion, the rate of the reaction activated by Fe2+-EDTA. In system (b) multilamellar vesicles were used as the substrate for lipid peroxidation, initiated by Fe2+-EDTA and determined by means of malonaldehyde (MDA) and 4-hydroxyalkenal (4-HDA) content. MLT was found to be slightly more effective in system (b) than in the dispersed linoleic acid system (see a). These results show that MLT inhibits lipid damage induced by oxygen free radicals. However, MLT is only about one one-hundredth as effective an antioxidant as vitamin E in the micelles system
The effect of sensitizing dyes for photo as antioxidants on the autoxidation of methyl linoleate
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