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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. Priya Rani K. G. Raghu Mangalam S. Nair K. P. Padmakumari 《Applied biochemistry and biotechnology》2014,173(4):946-956
Stereospermum colais (family Bignoniaceae) is a well-known pharmacologically potent medicinal plant reported in traditional systems of medicine. Phytochemical investigation of the roots of S. colais resulted in the isolation of seven compounds, and the metabolites were screened for its α-glucosidase enzyme inhibition and anti-glycation property. The compounds identified were β-sitosterol (1), 2-(4′-hydroxyphenyl) ethyl undecanoate (2), 2-(4′-hydroxyphenyl)ethyl pentadecanoate (3), 5α-ergosta-7,22-dien-3β-ol (4), ursolic acid (5), lapachol (6), and pinoresinol (7). Ursolic acid, lapachol, and pinoresinol possessed IC50 values of 119.01, 130.29, and 125.62 nM, respectively, compared to standard ascorbic acid with an IC50 value of 201.01 nM. The other compounds failed to show the activity. Results of the current study showcased the possible exploration of this medicinal plant for the treatment of type 2 diabetes in line with the development of phytopharmaceutical industry. 相似文献
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The composition and antioxidant activity of the essential oil obtained through hydrodistillation of pimento berry [Pimenta dioica (L.) Merr] samples, namely P1 and P2, sourced from Jamaica, were studied. The chemical composition was analysed by GC and GC-MS methods. The antioxidant activities of the oils were evaluated in terms of their free-radical-scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) radical cation and superoxide anion (?[image omitted]). Total phenolic content, total reducing power and metal-chelating capacity of the oils were also estimated. Forty-five constituents were identified. The major compound identified was eugenol (74.71%, 73.35%), followed by methyl eugenol (4.08%, 9.54%) and caryophyllene (4.90%, 3.30%). The antioxidant assays showed that the oils possess very high radical scavenging activities (DPPH IC(50) 4.82 ± 0.08, 5.14 ± 0.11 μg mL(-1), ABTS IC(50) 2.27 ± 0.16, 2.94 ± 0.03 μg mL(-1), superoxide IC(50) 17.78 ± 1.31, 20.65 ± 0.82 μg mL(-1)). The metal chelating capacities (IC(50) 83.62 ± 2.10, 101.77 ± 1.01 μg mL(-1)) and reducing power were also very high. The results show that the essential oils possess significant antioxidant activity which is comparable to that of pure eugenol. Therefore the oil can be utilised as a natural antioxidant which gives good flavour as well as health benefits. 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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Mahantesha B. K. Ravindrachary V. Padmakumari R. Sahanakumari R. Tegginamata Pratheeka Sanjeev Ganesh Petwal V. C. Verma V. P. 《Journal of Radioanalytical and Nuclear Chemistry》2019,322(1):19-27
Journal of Radioanalytical and Nuclear Chemistry - Effects of 10 MeV electron beam irradiation on KBr/PVA composite films were studied using various experimental methods. The FTIR study... 相似文献
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Shashwati Sen DK Aswal Ajay Singh TV Chandrasekhar Rao KP Muthe JC Vyas LC Gupta SK Gupta VC Sahni 《Pramana》2002,58(5-6):867-870
The MgB2 superconductor, synthesized using solid-state and liquid-phase sintering methods, have been characterized for various properties.
The upper critical field, irreversibility line and critical current density have been determined using magnetization data.
The current-voltage characteristics recorded under an applied magnetic field revealed the existence of vortex glass transition.
The surface analysis using X-ray photoelectron spectroscopy shows that MgB2 is sensitive to atmospheric degradation. 相似文献
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