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21.
Absorption of yeast andE. coli in the infrared and ultraviolet regions and that of diatomaceous soil in the infrared region have been obtained. Electron microscope photographs of aggregates ofE. coli have also been obtained. These results are discussed in relation to the Hoyle-Wickramasinghe hypothesis regarding the nature of interstellar grains.Department of Nuclear Engineering 相似文献
22.
23.
Absorption spectra in the visible to the near ultraviolet were measured on the Belgica chondrite B-7904 in a form of thin solid film made by the vacuum evaporation. The spectra obtained exhibit a sharp peak at 226 nm and a broad bump around 280nm. These features were found arising from the meteorite component FeS (troilite). The peak at 226 nm shows a doublet structure with the band-width considerably narrower than the 217.5 nm feature in the interstellar extinction. The absorption spectra obtained previously with the pulverized chondrites suspended in a liquid were also found reproducible by the pulverized FeS.Sponsored by the Office of Health and Environmental Research, U.S. Department of Energy under contract DE-AC05-840R21400 with Martin Marietta Energy Systems, Inc. 相似文献
24.
S. Yabushita 《Earth, Moon, and Planets》1989,44(1):29-37
Perturbation of the perihelion distance q of long-period comets by the galactic tidal force is calculated using Cowell's method. It is shown that the maximum perturbation is suffered by those with i (inclination) close to 50 ~ 60 and not by those with i close to 90 , contrary to the prediction of the first order perturbation theory. The dependence of the perturbation of q upon i is compared with the distribution of the inclinations of observed long-period comets and it is shown that the later is not consistent with an isotropic cloud of comets perturbed by the galactic tid alone. A close stellar encounter is unlikely to be an external disturbance. It is argued that giant molecular cloud is the most likely mechanism of the external disturbances. 相似文献
25.
S. Yabushita 《Earth, Moon, and Planets》1982,26(2):135-141
The equation of state of the terrestrial material obtained from seismic data is adopted to construct three zone earth models under hypothesis of variable constant of gravityG as proposed by Dirac. Three hypotheses are investigated: variableG without creation, creation such thatm (mass) G
–1, and multiplicative creation,mG
–2. It is shown that, with the currently accepted value of the Hubble constant,
,
and
for each hypothesis. On the multiplicative creation, the Earth radius would have been 5100 km, which is in agreement with estimate by some geophysicists. 相似文献
26.
The suitability of N,N-dimethylformamide (DMF) as an extractant for the standard reverse-phase HPLC method was examined using
algal cultures. Good pigment separations and recovery were achieved with 20% (volume %) addition of an ion-pairing solution
in an injection. While slight amounts of degradation products of chlorophylla, i.e., chlorophyllidea, allomeric and epimeric forms, were produced, adequate attention to filtration and extraction prevents the formation of degradation
products, confining them to an acceptable level. Because of its strong extractability, which expedites the extraction process,
DMF is an efficient solvent for HPLC analysis of phytoplankton pigments. 相似文献
27.
S. Yabushita 《Earth, Moon, and Planets》1994,64(3):207-216
Periodicities in crater formation rate and mass-extinctions are reviewed. The former exhibits a period of 30 million yr, while the latter appear to have a periodicity at 26 myr. Results obtained earlier that small craters better satisfy the adopted criterion for statistical testing is shown due to the fact that there is a strong clustering of small craters in a recent past (<10 myr). On the basis of the dataset of craters compiled by Grieve, it is shown that there are several craters for which no mass extinctions correspond. The difference in the periods of the craters and of mass extinctions and the lack of mass extinctions that correspond to large craters appear to suggest that the two periodicities are not interrelated, and large impacts merely act as triggers for the mass-extinctions; the only exception being theK/T boundary. 相似文献
28.
Shin Yabushita 《Earth, Moon, and Planets》1996,73(3):215-220
Earlier, a study has been made of the transport mechanism of volatile molecules such as N2 and CO through cometary nuclei as they are heated by radioactive elements. Coupled equations of heat and gas transport in the presence of gas sublimation and recondensation, as well as a heat source, were numerically solved. And it was shown that supervolatiles such as N2 and CO are transported through the pores of the nucleus, and consequently the volatile molecules become more abundant near the surface than deep inside the nucleus. Here, the process is investigated for a wider range of paramaters such as porosity and nuclear radius. It is shown that provided the central temperature attains the sublimation point of the super-volatiles, they are transported toward the surface regardless of the values of the parameters. 相似文献
29.
S. Yabushita 《Earth, Moon, and Planets》1990,49(3):239-245
Effect of stellar and supernova radiations on cometary nuclei in the Oort cloud is investigated. Radiation dose received by a comet is calculated and compared with the one which Halley's comet receives by one perihelion passage. Stellar radiation provides 10 to 50% of Halley unit over 4 billion years. Inclusion of sublimation of volatile molecules such as CO or N2 does not allow the temperature to rise to 30 K by irradiation of bright OB stars, contrary to the claim of Stern and Shull. A chance encounter with a SN provides radiation dose which is just sufficient to raise to 30 K the surface layer which is 1 m thick on the assumption that the radiation is wholly communicated to the interior. Thus, the comets remain pristine under the effect of stellar and SN radiations. 相似文献
30.
Absorption ofE. Coli and other micro-organisms are measured by the standard optical spectroscopy and by the photo-accoustic method. The former method does not yield an extinction peak at =220 nm but yields a weak one at =270 nm, while by the latter method absorption peaks at =220 nm and a weaker one at =270 nm have been found for the spore of Bacillus subtilis. The well-known amino-acid, triptophan shows absorption peaks at =220 and 280 nm. It is tentatively concluded that for the micro-organism model of interstellar grains to be viable, they may have to be spores rather than ordinary cells. 相似文献