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| 42. |
- Meier, M. M. M., et al.
(författare)
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Noble gases in individual L chondritic micrometeorites preserved in an Ordovician limestone
- 2010
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Ingår i: Earth and Planetary Science Letters. - : Elsevier BV. - 1385-013X .- 0012-821X. ; 290:1-2, s. 54-63
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the He and Ne concentrations and isotopic ratios of individual sediment-dispersed extraterrestrial chromite grains (63-180 mu m in diameter) from an Ordovician limestone in southern Sweden. In the same sediment, many fossil meteorites were found and have been attributed to the L chondrite parent body breakup event similar to 470 Ma ago. In this analysis of 37 individual extraterrestrial chromite grains of L chondritic major element composition, at least 35 (similar to 95%) contain surface-implanted helium and neon of fractionated solar wind composition, implying that these grains are (relict parts of) fossil micrometeorites of asteroidal origin. Similar to what has been observed in recent micrometeorites collected in the polar regions. significant amounts of cosmogenic Ne-21 were found in several grains, resulting in cosmic ray exposure (CRE) ages of up to similar to 77 Myr. These ages exceed both dynamical lifetimes for asteroidal micrometeorites of this size as well as CRE ages observed in chromites from fossil meteorites from the same sediment beds. Significant contributions from terrestrial sources, like nucleogenic and cosmic-ray muon induced Ne-21 can be excluded in the extraterrestrial chromites, since 11 terrestrial chrome spinel grains from the same sediment beds did not contain any measurable Ne-21 excesses. Having found micrometeorites of undisputed asteroidal origin with cosmic ray exposure ages of several 10(7) years implies that high cosmic ray exposure ages alone are not a good indicator of cometary origin, in opposition to what has been suggested for recent micrometeorites and IDPs. We propose instead that these grains collected their cosmogenic Ne-21 while residing in the regolith layer of their parent body. (C) 2009 Elsevier B.V. All rights reserved.
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| 43. |
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| 45. |
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| 46. |
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| 47. |
- Engelmann, U, et al.
(författare)
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Experiences with the German teleradiology system MEDICUS
- 1997
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Ingår i: COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE. - 0169-2607. ; 54:1-2, s. 131-139
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This paper introduces the teleradiology system, MEDICUS, which has been developed at the Deutsches Krebsforschungszentrum (German Cancer Research Center) in Heidelberg, Germany. The system is designed to work on ISDN lines as well as in a local area netwo
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| 48. |
- Engelmann U. Schröter A, Baur U, Werner O, Göransson B, Borälv E, Schwab M, Müller H, Bahner M, Meinzer HP.
(författare)
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Experiences with the German teleradiology system MEDICUS
- 1998
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Ingår i: Yearbook of Medical Informatics '98 - Health Informatics and the Internet. - : Stuttgart: Schattauer. ; , s. 199-207
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 49. |
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| 50. |
- Minakshi, M., et al.
(författare)
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Phase evolution in calcium molybdate nanoparticles as a function of synthesis temperature and its electrochemical effect on energy storage
- 2019
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Ingår i: Nanoscale Advances. - : Royal Society of Chemistry. - 2516-0230. ; 1:2, s. 565-580
-
Tidskriftsartikel (refereegranskat)abstract
- The design of a suitable electrode is an essential and fundamental research challenge in the field of electrochemical energy storage because the electronic structures and morphologies determine the surface redox reactions. Calcium molybdate (CaMoO4) was synthesized by a combustion route at 300 °C and 500 °C. We describe new findings on the behaviour of CaMoO4 and evaluate the influence of crystallinity on energy storage performance. A wide range of characterization techniques was used to obtain detailed information about the physical and morphological characteristics of CaMoO4. The characterization results enable the phase evolution as a function of the electrode synthesis temperature to be understood. The crystallinity of the materials was found to increase with increasing temperature but with no second phases observed. Molecular dynamics simulation of electronic structures correlated well with the experimental findings. These results show that to enable faster energy storage and release for a given surface area, amorphous CaMoO4 is required, while larger energy storage can be obtained by using crystalline CaMoO4. CaMoO4 has been evaluated as a cathode material in classical lithium-ion batteries recently. However, determining the surface properties in a sodium-ion system experimentally, combined with computational modelling to understand the results has not been reported. The superior electrochemical properties of crystalline CaMoO4 are attributed to its morphology providing enhanced Na+ ion diffusivity and electron transport. However, the presence of carbon in amorphous CaMoO4 resulted in excellent rate capability, suitable for supercapacitor applications.
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