Short Ultraviolet Wavelengths Research Articles

The Effect of Hydrocortisone on the Mastocytosis Produced in Mice by Short-Wavelength Ultra-Violet Radiation

(1980). The Effect of Hydrocortisone on the Mastocytosis Produced in Mice by Short-Wavelength Ultra-Violet Radiation. Scandinavian Journal of Rheumatology: Vol. 9, No. 1, pp. 41-47.

Photolysis of 5-chlorouracil in natural waters

5-Chlorouracil, a potantially hazardous substance formed during chlorination of natural waters, is subject to photolysis in solution when irradiated by naturally occurring wavelengths of ultraviolet light. The undissociated species of 5-chlorouracil does not degrade in solution even when irradiated by shorter ultraviolet wavelengths than penetrate the earth's atmosphere, but the monoanion, which predominates above pH 8, disappears at a first order rate when irradiated by 290–320 nm light. Variations in pH and temperature have pronounced effects on the rate of photolysis., with higher pH and temperature resulting in more rapid breakdown. The photolytic half-life of 5-chlorouracil could be as low as two days under some conditions of pH, temperature, transparency, depth, and illumination, but in most cases the rate of degradation would be considerably slower.

Sunlight, Skin Cancer, and Sunscreens

THE SOLAR electromagnetic spectrum ranges widely from below the short ultraviolet wavelength through the visible light spectrum and beyond. The ozone in our stratosphere 25 km above the earth effectively protects us from the short-wave, highenergy ultraviolet (UV) light. But UV light that does penetrate the atmosphere contains the erythrogenic spectrum that causes the all-too-familiar sunburn reaction. Redness begins two to eight hours after exposure and usually peaks at 24 hours. When the exposure has been longer than five times the minimum erythema dose (MED) (ie, the amount of energy from a defined light source, like the sun, producing a barely perceptible sunburn or erythema of the skin under stated conditions), blistering, pain, and fever may also occur. Although immediate darkening of pigment may accompany such erythema, due to oxidation of colorless preformed melanin already in the skin, it is transient, fading within a few hours. The socially sought-after, durable

EFFECTS OF SIMULATED SPACE ULTRAVIOLET AND VISIBLE RADIATION UPON DRY CYSTS OF COLPODA INFLATA

Abstract— Dry cysts of Colpoda inflata were irradiated with an argon plasma arc lamp, the output of which simulates space radiation in its wavelength distribution although it is of higher intensity. Rapid evacuation reduced the rate of excystment as well as the percentage excysting; low temperature (near that of liquid nitrogen) had little effect on either measurement. All cysts were therefore irradiated at room temperature in a cell flushed with dry nitrogen. Radiation passed for 1 min through a sapphire filter, with a cutoff at 145 nm, prevented excystment. At smaller doses progressively less damaging effects were observed as judged by both the increase in time required for excystment and the percentage excysted. No dark recovery was observed in dry cysts. Exposure of cysts to radiation passed through a series of filters which progressively remove short ultraviolet wavelengths indicate that it is mainly the quartz‐transmitted wavelengths (cutoff 185 nm) which damage the cysts. The presumption is that most of the vacuum‐ultraviolet wavelengths are superficially absorbed; their lesser effect is also partially attributable to their lower intensity. Inasmuch as 1 min of argon lamp radiation is equivalent to 24 min in space, it is evident that Colpoda cysts would not long survive a journey in space, had they reached there in viable condition.

The action spectrum in polymorphic light eruption.

SUMMARY A Study of fifty-six cases of polymorphic light eruption has shown that the action spectrum frequently lies in both the long ultraviolet wavelengths (320-400 nm) and the short ultraviolet wavelengths below 320 nm.

Studies related to satellite thermal control: Measurements of earth-reflected sunlight and stability of thermal-control coatings

As part of a study of satellite thermal control, data were obtained on earth-reflected solar radiation and on the stability of thermal-control coatings. The intensity distribution of incoming solar radiation to earth was found to be shifted toward the ultraviolet region upon reflection by the atmosphere. As a result of the shift, the intensity of reflected radiation reaches a maximum in the near ultraviolet. At shorter wavelengths in the ultraviolet region, the intensity drops sharply to zero as a result of absorption of incoming radiation by ozone in the upper atmosphere. Comparisons of calculated intensity distributions with measured distributions for two different atmospheric conditions gave good agreement, except at the shorter ultraviolet wavelengths where the calculations did not adequately include the effect of ozone absorption. Measurements of stability of thermal-control coatings showed a lower degradation rate of white paints than was obtained on other flight experiments flown outside of the protective influence of earth's magnetosphere. The differences in degradation rate were much larger than expected, indicating that further study is required in the development of white coatings for spacecraft thermal control.

The Effect of Hydrocortisone on the Mastocytosis Produced in Mice by Short-Wavelength Ultra-Violet Radiation

SummaryThe effect of hydrocortisone on the mastocytosis produced in the skin of mice by short-wavelength ultra-violet radiation was investigated. Two groups of mice were irradiated. The mice in one of the two groups also received hydrocortisone. It was observed that hydrocortisone distinctly reduced the tissue swelling produced by UV-radiation. In the group receiving radiation + hydrocortisone the mast cell counts distinctly decreased to below the control level. On the other hand in the group having mere radiation the mast cell counts clearly increased.

Photoreversal of nuclear and cytoplasmic effects of short ultraviolet radiation on Paramecium caudatum.

1. Irradiation with three short ultraviolet (UV) wave lengths, 226, 233, and 239 mmicro rapidly immobilizes Paramecium caudatum, the dosage required being smaller the shorter the wave length. 85 per cent of paramecia immobilized with wave length 226 mmicro recover completely. Recovery from immobilizing doses is less the longer the wave length. 2. Irradiation continued after immobilization kills the paramecia in a manner which is markedly different for very short (226, 233, and 239 mmicro) and longer (267 mmicro) wave lengths. 3. An action spectrum for immobilization in P. caudatum was determined for the wave lengths 226, 233, 239, 248, and 267 mmicro, and found to resemble the absorption of protein and lipide in the wave length region below 248 mmicro. Addition of these data to those of Giese (1945 b) gives an action spectrum resembling the absorption by albumin-like protein. 4. Division of P. caudatum is delayed by doses of wave lengths 226, 233, and 239 mmicro which cause immobilization, the longest wave length being most effective. 5. Immobilization at any of the wave lengths tested (226, 233, 239, 248, 267 mmicro) is not photoreversible when UV-treated paramecia are concurrently illuminated. 6. Division delay resulting from immobilizing doses of 226, 233, and 239 mmicro is photoreversible by exposure to visible light concurrently with the UV. 7. Division delay induced by exposure to wave length 267 mmicro is reduced by exposure to visible light applied concurrently with UV or immediately afterwards. 8. The data suggest that the shortest UV wave length tested (226 mmicro) affects the cytoplasm selectively, because it is absorbed superficially as indicated by unilateral fluorescence in UV. Consequently it immobilizes paramecia rapidly but has little effect on the division rate because little radiation reaches the nucleus. 9. The data support the view that nuclear effects of UV are readily photoreversed but cytoplasmic effects are not.

MUTANTS PRODUCED BY X-IRRADIATION OF SPORES OF CHAETOMIUM GLOBOSUM AND A COMPARISON WITH THOSE PRODUCED BY ULTRAVIOLET IRRADIATION

1. Mutants produced by x-irradiation of fungal spores of Chaetomium globosum have been compared with those produced by ultraviolet irradiation. 2. The most striking difference between the mutants produced by x-irradiation and ultraviolet irradiation is the absence in x-ray experiments of the K mutant which is produced in large numbers at short ultraviolet wave lengths. 3. A comparison is made of the relation between x-ray dose and numbers of lethal mutants, and the relation between the short ultraviolet wave length 2804 dose and numbers of lethal mutants. Both are compared with theoretical curves for 1, 2, 5, and 8 quantum hits. 4. The production of lethal mutants by x-rays is shown to be consistent with the theoretical curve for five quantum hits on the sensitive spot of the spore, whereas the production of lethal mutants by the ultraviolet wave length 2804 A.u. is consistent with two quantum hits.

SALTANT PRODUCTION BY WAVE LENGTHS OF VISIBLE AND LONG ULTRAVIOLET MONOCHROMATIC IRRADIATION, AND A COMPARISON WITH SALTANTS PRODUCED BY SHORT WAVE LENGTHS OF MONOCHROMATIC ULTRAVIOLET IRRADIATION IN THE FUNGUS CHAETOMIUM GLOBOSUM

1. Saltants have been produced in the fungus Chaetomium globosum by longer wave lengths than previously reported-by 365 mmicro and by a visible line 404 mmicro. 2. Absence at these wave lengths of the K saltant, which is so abundant at short wave lengths, is marked. 3. Ratio of percentage irradiated spores germinating to control spores germinating decreases from 83 per cent at 265 mmicro, a short ultraviolet wave length, to 57 per cent at 404 mmicro, a visible violet wave length.

The Response of Several Fluorescent Materials to Short Wave-Length Ultraviolet Radiations

A quartz monochromator has been used to measure the relative response of several synthetic phosphors in the region of 2200A to 3150A. The deactivating effect of copper and nickel on certain substances is represented graphically. With a vacuum grating spectrograph the response characteristics of zinc silicate and calcium tungstate have been extended to the Schumann ultraviolet region.