The survival ratio of Aspergillus spores exposed to ultraviolet radiation has been measured as a function of total incident energy for wave lengths of 2537 A, 3022 A, 3129 A, and 3650 A. The effect of humidity on killing of Aspergillus spores by ultraviolet radiation has been found to be negligible. A delay in germination as a result of irradiation has been found. The Bunsen-Roscoe reciprocity ...

It has been reported in a preliminary communication (1) that under certain conditions, at room temperature, perchloric acid converts tryptophan to a yellowish green fluorescent compound. Fluorescence was found to be particularly strong in ultraviolet light. It has now been found that a small amount of bichromate very considerably increases the sensitivity of this reaction and that the test may ...

The discovery by Farquhar et al. (1) of mass-independent isotope fractionation of S and S in rocks formed more than ;2 billion years ago (Ga), but not in younger rocks, has boosted the theory postulating a dramatic change from an anoxic to an oxygen-rich atmosphere about 2 Ga. That is because the only known natural process that may cause mass-independent fractionation of both S and S involves a...

Fourteen lipase low-producing (Lip-) mutants of Yarrowia lipolytica were obtained by UV mutagenesis. Complementation studies showed that ten of these mutants belonged to one complementation group. Two other mutants, Lip-132 and 223, complemented those of the first group. Lip-1123 complemented mutants of the first and second groups. Lip-1351 did not complement Lip-742, 417, 529 and 1133, which b...

A current threat to the marine ecosystem is the high level of solar ultraviolet radiation (UV). Large whales have recently been shown to suffer sun-induced skin damage from continuous UV exposure. Genotoxic consequences of such exposure remain unknown for these long-lived marine species, as does their capacity to counteract UV-induced insults. We show that UV exposure induces mitochondrial DNA ...

Being an atomically thin material, graphene is known to be extremely susceptible to its environment, including defects and phonons in the substrate on which it is placed as well as gas molecules that surround it. Thus, any device design using graphene has to take into consideration all surrounding components, and device performance needs to be evaluated in terms of environmental influence. Howe...

1. An unidentified unit in the mechanism of the photosynthesis of Chlorella pyrenoidosa is rendered inactive by the absorption of one quantum of ultraviolet light (2537 A wave length). 2. The same irradiation has no effect on the normal respiration of Chlorella pyrenoidosa. Experiments have not yet been made on the respiration inhibitable by HCN. 3. No chemical change was detected in the chloro...

Regarding the influence of ultraviolet irradiation on the growth of bacteria, numerous studies have been accomplished and it has been known that there exists a relation of exponential function between the bactericidal effect and the amount of ultraviolet ray irradiated. The methods employed in those studies,1),2),3),4) a,b, however, are mostly so called plate method in which the irradiation is ...

In many chemical reactions, an activation barrier must be overcome before a chemical transformation can occur. As such, understanding the behaviour of molecules in energetically excited states is critical to understanding the chemical changes that these molecules undergo. Among the most prominent reactions for mankind to understand are chemical changes that occur in our own biological molecules...