Yet in comets, often considered the most primitive bodies in the solar system, N-2 has not been detected. Here we report the direct in situ measurement of N-2 in the Jupiter family comet 67P/Churyumov-Gerasimenko, made by the Rosetta NCT-501 Orbiter Spectrometer for Ion and Neutral Analysis mass spectrometer aboard the Rosetta spacecraft.
A N-2/CO ratio of (5.70 +/- 0.66) x 10(-3) (2s standard deviation of the sampled mean) corresponds to depletion by a factor of -25.4 +/- 8.9 as compared to the protosolar value. This depletion suggests that cometary grains formed at low-temperature conditions below similar to 30 kelvin.”
“Overgaard-Steensen C, Stodkilde-Jorgensen H, Larsson A, Broch-Lips M, Tonnesen E, Frokiaer J, Ring T. Regional differences in osmotic behavior in brain during acute hyponatremia: an in vivo MRI-study of brain and skeletal muscle in pigs. Am J Physiol Regul Integr Comp Physiol 299: R521-R532, 2010. First published May 5, 2010; doi: 10.1152/ajpregu.00139.2010.-Brain edema is suggested to be the principal mechanism underlying the symptoms in acute hyponatremia. Identification of the mechanisms responsible for global and regional cerebral water homeostasis during hyponatremia is, therefore, of utmost importance. To examine the osmotic behavior of different brain regions and muscles, in vivo-determined water content (WC) was related
to plasma sodium concentration ([Na(+)]) and brain/muscle selleck inhibitor electrolyte content. Acute hyponatremia was induced with desmopressin acetate and infusion of a 2.5% glucose
solution in anesthetized pigs. WC in different CA4P brain regions and skeletal muscle was estimated in vivo from T(1) maps determined by magnetic resonance imaging (MRI). WC, expressed in gram water per 100 g dry weight, increased significantly in slices of the whole brain [342(SD = 14) to 363(SD = 21)] (6%), thalamus [277(SD = 13) to 311(SD = 24)] (12%) and white matter [219(SD = 7) to 225(SD = 5)] (3%). However, the WC increase in the whole brain and white mater WC was less than expected from perfect osmotic behavior, whereas in the thalamus, the water increase was as expected. Brain sodium content was significantly reduced. Muscle WC changed passively with plasma [Na(+)]. WC determined with deuterium dilution and tissue lyophilzation correlated well with MRI-determined WC. In conclusion, acute hyponatremia induces brain and muscle edema. In the brain as a whole and in the thalamus, regulatory volume decrease (RVD) is unlikely to occur. However, RVD may, in part, explain the observed lower WC in white matter. This may play a potential role in osmotic demyelination.”
“The aim of this study was to examine the effect of D-sorbitol on the gelation characteristics of methylcellulose in aqueous solution. The addition of D-sorbitol at concentrations of between 25 and 30010 (w/v) to 1.0-2.