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Clusters of galaxies are excellent probes of cosmic structure and evolution. X-ray studies of clusters provide some of their
key parameters, viz., temperature of the hot intra-cluster gas, its metallicity, X-ray luminosity and surface brightness giving
mass distribution and mass-flow rate in the case of cooling flows. X-ray measurements for a large sample of clusters have
lead to estimates of the total gravitating mass in them, which can be compared to the virial masses derived from dynamical
considerations and gravitational lensing in some of them. X-ray derived total masses are consistent with masses obtained from
the other methods after the effects due to the presence of cooling flows are taken into account in the analyses. Estimated
virial masses, lack of evolution in X-ray properties, and detection of several very hot clusters at high redshifts indicate
a Universe with a low value (≤ 0.3) for the Ω parameter. 相似文献
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M. Pleissner 《Fresenius' Journal of Analytical Chemistry》1909,48(2):110-111
Ohne Zusammenfassung 相似文献
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Half life for the emission of exotic clusters like 8Be, 12C, 16O, 20Ne, 24Mg and 28Si are computed taking Coulomb and proximity potentials as interacting barrier and many of these are found well within the
present upper limit of measurement. These results lie very close to those values reported by Shanmugam et al using their cubic plus Yukawa plus exponential model (CYEM). It is found that 12C and 16O emissions from 116Ce and 16O from 118Ce are most favorable for measurement (T
1/2<1010 s). Lowest half life time for 16O emission from 116Ce stress the role of doubly magic 100Sn daughter in exotic decay. Geiger-Nuttall plots were studied for different clusters and are found to be linear. Inclusion
of proximity potential will not produce much deviation to linear nature of Geiger-Nuttall plots. It is observed that neutron
excess in the parent nuclei slow down the exotic decay process. These findings support the earlier observations of Gupta and
collaborators using their preformed cluster model (PCM). 相似文献
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M. Pleissner 《Analytical and bioanalytical chemistry》1909,48(2):110-111
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Chemistry made once expensive leisure activities available to public by providing inexpensive materials for fishing rods, golf equipment etc. Nowadays, eco-minded costumers wish the impact of their leisure activities on environment as little as possible, and thus expect materials to be overall sustainable. Particularly, the hospitality sector has to fulfill the expectations of eco-minded tourists who prefer hotels engaged in activities for protecting natural resources and working against waste accumulation. The recent developments in green chemistry and material design can contribute to the sustainability of leisure industry. In this short review research outcomes regarding the development of materials which can be formed, degraded and reformed into new materials are presented. Finally, a business model called “material leasing” based on the principles of “chemical leasing” for the implementation of new materials in the hospitality and leisure sectors is proposed. 相似文献
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