The demonstration by Martius and Nitz-Litzow (4), and Martius (5), that vitamin K1 may play a functional role in oxidative phosphorylation in animals has led to an increased interest in the participation of vitamin Ki and related quinones in electron transport, oxidative phosphorylation, and photosynthetic phosphorylation. Since vitamin K1 is altered by the action of ultraviolet radiation (6), ...

We consider the general theoretical problem of ultraviolet light from old stellar populations (t∼>2Gyr), and the interpretation of galaxy spectra at short (λ < 3000 Å). The sources believed to be responsible for the observed ‘ultraviolet upturn phenomenon’ (UVX) are Post-AGB (P-AGB), extreme horizontal branch (EHB) and AGB-Manqué (AGBM) stars. All of these have observational counterparts in old...

Six uvr mutants of Saccharomyces cerevisiae with hypersensitivity to ultraviolet (UV) light were isolated after mutagen treatment with ethylmethanesulfonate. UV sensitivity ranges from moderate to extreme, and four of the mutants are also sensitive to nitrous acid. Ranking in terms of UV sensitivity does not parallel ranking in terms of nitrous acid sensitivity. Homozygous diploid mutant strain...

Solar light is the primary source of UV radiation for all living systems. UV photons can mediate damage through two different mechanisms, either by direct absorption of UV via cellular chromophores, resulting in excited states formation and subsequent chemical reaction, or by phosensitization mechanisms, where the UV light is absorbed by endogenous (or exogenous) sensitizers that are excited an...

Regeneration of Blepharisma undulans variety japonicus from which the hypostome has been removed is retarded by dosages of 3000 to 4600 ergs/mm.(2) at wavelength 2654A most strongly when the fragment is exposed soon after cutting. Dosages greater than 4600 ergs/mm.(2) prevent regeneration. Regeneration is also retarded strongly when the Blepharisma are cut soon after irradiation. Starvation ret...

Light as a form of electromagnetic energy has a dual wave particle nature. When describing the effects of light absorbed by a photoreceptor, the behavior of light particles is more important. The portion of the electromagnetic spectrum that interacts with the eye is wider than the portion that is used for phototransduction. It includes wavelengths of ultraviolet light (100-400nm), visible light...

The use of liquid helium and neon as scintillators for neutrino detection is investigated. Several unique properties of these cryogens make them promising candidates for real-time solar neutrino spectroscopy: large ultraviolet scintillation yields from ionizing radiation, transparency to their own scintillation light, and low levels of radioactive impurities. When neutrinos scatter from electro...

An important handicap of electron microscopy has been the inability of electrons to penetrate protoplasm. Thus, most bacteria are opaque when observed with this instrument unless special methods are used such as chemical treatment or growth in special media (Knaysi, 1951). Yeasts have appeared as completely ,opaque. In an earlier paper (Bartholomew and Mittwer, 1952) the authors reported that u...

In order to reveal the origin of enhanced photocatalytic activity of N-doped La2Ti2O7 in both the visible light and ultraviolet light regions, its electronic structure has been studied using spin-polarized conventional density functional theory (DFT) and the Heyd-Scuseria-Ernzerhof (HSE06) hybrid approach. The results show that the deep localized states are formed in the forbidden band when nit...