The bactericidal effect of sunilight was demonstrated as early as 1878 by Downes and Blunt who reported that culture media exposed to sunlight for several hours remained sterile, wlrhile corresponding portions of the same media which were allowed to stand in shaded portions of the same room became contaminated. Tizzoni and Cattani (1891) and Wesbrook (1896) reported the killing of Clostridium t...

In a previous paper (Buchbinder and Phelps, 1941) a method was described whereby the survival rates of streptococci in simulated room environments may be determined with the use of a petri plate technic. It was found by this method that the death rates of streptococci in the dark under these simulated room conditions were geometric and that the median survival time (m.s.t.), of the three strain...

Light irradiation plays an important role in the growth of microalgae and their nutrient composition. To elucidate effect different LED lights (red, orange, green, blue, purple, simulated sunlight, white) on main nutritional compositions Isochrysis zhanjiangensis, growth, fatty acid composition, soluble carbohydrate, protein contents were studied. The results show that I. zhanjiangensis grew fa...

The photosynthesis of previtamin D3 from 7-dehydrocholesterol in human skin was determined after exposure to narrow-band radiation or simulated solar radiation. The optimum wavelengths for the production of previtamin D3 were determined to be between 295 and 300 nanometers. When human skin was exposed to 295-nanometer radiation, up to 65 percent of the original 7-dehydrocholesterol content was ...

Sunlight is an important cause of damage to plastics, textiles, paints, and other organic materials. Short wavelength ultraviolet light has long been recognized as being responsible for most of this damage2. Spectroradiometric measurements were made to quantify the wide variations in UV content of sunlight under the following conditions: direct summer sunlight, winter sunlight, sunlight filtere...