2,407,736 research outputs found

    Water/Icy Super-Earths: Giant Impacts and Maximum Water Content

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    Water-rich super-Earth exoplanets are expected to be common. We explore the effect of late giant impacts on the final bulk abundance of water in such planets. We present the results from smoothed particle hydrodynamics simulations of impacts between differentiated water(ice)-rock planets with masses between 0.5 and 5 M_Earth and projectile to target mass ratios from 1:1 to 1:4. We find that giant impacts between bodies of similar composition never decrease the bulk density of the target planet. If the commonly assumed maximum water fraction of 75wt% for bodies forming beyond the snow line is correct, giant impacts between similar composition bodies cannot serve as a mechanism for increasing the water fraction. Target planets either accrete materials in the same proportion, leaving the water fraction unchanged, or lose material from the water mantle, decreasing the water fraction. The criteria for catastrophic disruption of water-rock planets are similar to those found in previous work on super-Earths of terrestrial composition. Changes in bulk composition for giant impacts onto differentiated bodies of any composition (water-rock or rock-iron) are described by the same equations. These general laws can be incorporated into future N-body calculations of planet formation to track changes in composition from giant impacts.Comment: 9 pages, 4 figures, Accepted for publication in ApJ Letter

    Determination of water content using mass spectrometry

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    Mass spectrometer is used to measure small quantities of water present in different materials. System has been applied in measuring water and gases desorbed from microcircuitry insulation, can also be used with foods, polymeric materials, and organic solvents

    Water Content and Superconductivity in Na0.3CoO2*yH2O

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    We report here the correlation between the water content and superconductivity in Na0.3CoO2*yH2O under the influences of elevated temperature and cold compression. The x-ray diffraction of the sample annealed at elevated temperatures indicates that intergrowths exist in the compound at equilibrium when 0.6 < y < 1.4. Its low-temperature diamagnetization varies linearly with y, but is insensitive to the intergrowth, indicative of quasi-2D superconductivity. The Tc-onset, especially, shifts only slightly with y. Our data from cold compressed samples, on the other hand, show that the water-loss non-proportionally suppresses the diamagnetization, which is suggestive of weak links.Comment: 10 pages, 10 figures; submitted to Physica C (August 13, 2003

    Physical characterisation of some honey samples from North-Central Nigeria

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    Some physicochemical properties (water content, sugar content, viscosity, pH and conductivity) were determined for honey samples from North-Central Nigeria to evaluate their global behaviour and comparison with other honey samples. The water content and sugar content varied within the range of (18.22 - 36.82%) and (63.82 - 80.25%)respectively. The pH increased with increase in water content and the conductivities of the samples had correlation with proportion of minor constituents in the honey samples. The relationship among water content (w), temperature (t) and viscosity (η) for different honey samples of may be represented as η = 17.678× 1000 exp (-0.32w - 0.088t). The temperature dependence of viscosity was evaluated with Arrhenius model, the activation energy with value of 70.07 kJ/g is fairly unaffected by moisture content

    Changes in the chloride content of ground water in Pinellas County, Florida between 1947 and 1956

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    In December 1956 the U. S. Geological Survey, in cooperation with the Florida Geological Survey and the Board of County Commissioners of Pinellas County, collected waterlevel and chloride content of water in 94 wells in Pinellas County. First sampled in 1947, resampling and reanalyzing the water from these wells was used to determine the change in the chloride content of the ground water from 1947 to 1956. The chloride content of ground water is generally a reliable indication of the contamination of ground water by sea water, as 90 percent of the dissolved solids of sea water are chloride salts. (PDF contains 15 pages.

    On-sample water content measurement for a complete local monitoring in triaxial testing of unsaturated soils

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    To provide a complete local monitoring of the state of an unsaturated soil sample during triaxial testing, a local water content measurement device was adapted to a triaxial device comprising the measurement of local displacements (Hall effect transducers) and suction (High capacity transducer). Water content was locally monitored by means of a resistivity probe. The water content/resistivity calibration curves of an intact natural unsaturated loess from Northern France extracted by block sampling at two depths (1 and 3.3 m) were carefully determined, showing good accuracy and repeatability. The validity of two models giving the resistivity of unsaturated soils with respect to their water content was examined

    Soil moisture by extraction and gas chromatography

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    To determine moisture content of soils rapidly and conveniently extract moisture with methanol and determine water content of methanol extract by gas chromatography. Moisture content of sample is calculated from weight of water and methanol in aliquot and weight of methanol added to sample

    Remote measurement of the water content of snowpacks

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    Electronic equipment for sensing moisture content of snowpacks is described. Components of electronic test equipment are illustrated and methods of conducting tests are explained. Possibilities for airborne sensing are examined

    Age-related changes in local water and protein content of human eye lenses measured by Raman microspectroscopy

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    The Raman microspectroscopic method was used to determine the local water and protein content in human lenses. In 18 lenses of varying age position-defined water/protein content measurements were carried out along the visual and the equatorial axis.\ud \ud A main characteristic of the human lens is its constant and relatively low protein content. In addition this constant nuclear value is reached within a short distance from the capsular surface. For statistical analysis of age-related changes the data points in individual lenses were piecewise linearized. (1) The mean nuclear water content was calculated from the data points in the inner 80% of the visual axis. (2) The steep drop in water content was linearized using a least-squares linear regression approach. The distance between lenticular surface and the intersection of the regression line with the line representing the nuclear mean was denominated as surface layer width.\ud \ud It proved that: (i) the mean nuclear water content significantly increased with age, (ii) the width of the surface layer was age independent in the anterior and posterior poles of the visual axis, and (iii) in the equatorial axis the surface layer width significantly decreased with age.\ud \ud Seven human lenses with small opaque spots were also investigated. The opaque spots proved to have a normal-for-site water content and some of them were flanked at their capsular side by a zone with a high-for-site water content.\ud \ud The correlation between protein content and refractive index and the observed decrease in nuclear protein content in aging human lenses can be taken as strong evidence that upon aging the refractive index of a major part of the human lens is reduced. The implications of this decrease is discussed with the respect to the problem known as the lens Paradox, i.e. the discrepancy between the theoretically expected age-related loss of far vision due to changes in lens curvature and axial position in the eye and the actually observed loss in near vision upon age
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