scholarly journals QUANTITATIVE STUDIES ON THE PHOTOLETHAL EFFECTS OF QUARTZ ULTRA-VIOLET RADIATION UPON PARAMECIUM

1935 ◽  
Vol 18 (4) ◽  
pp. 557-571 ◽  
Author(s):  
A. C. Giese ◽  
P. A. Leighton
Keyword(s):  
Wave Length ◽  
Ultra Violet ◽  
The Other ◽  
Ultra Violet Radiation ◽  
Quantitative Studies ◽  
Controlled Conditions ◽  
Order Of Magnitude ◽  
Intense Light ◽  
Violet Radiation

Paramecia grown under controlled conditions were irradiated at known intensities of light of wave-lengths 2537, 2654, 2804, 3025, and 3130 A. The approximate absorption of the light by the Parmecia was found to be greatest and of the same order of magnitude at the three shortest wave-lengths, considerably less at 3025, and least at 3130 A. Paramecia did not die when irradiated with high dosages of intense light of wave-length 3130 A. At the other wave-lengths 50 per cent vesiculation occurred when between 1012 and 1013 quanta had been absorbed by a Paramecium. This would indicate that a very large number of molecules in a Paramecium are affected before vesiculation occurs.

Properties of Higher Polymers in Solution. III. The Action of Ultra-Violet Light on Dissolved Rubber

1936 ◽  
Vol 9 (4) ◽  
pp. 570-572 ◽  
Author(s):  
Kurt H. Meyer ◽  
Cesare Ferri
Keyword(s):  
Physical Properties ◽  
Wave Length ◽  
Ultra Violet ◽  
The Other ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Ultra Violet Radiation ◽  
Gutta Percha ◽  
Other Hand ◽  
Violet Radiation

Abstract The action of ultra-violet radiation on rubber has been the object of a long series of investigations. According to van Rossem, rubber is depolymerized under the action of light. Asano on the other hand thinks that ultra-violet light, is able to bring about either polymerization or depolymerization according to its wave-length. More recently Dogadkin and Pantschenkov have carried out experiments in an atmosphere of nitrogen, during the course of which they have found a strong diminution in the viscosity. From this fact they have concluded that light is able to cause depolymerization and micellar degradation. We have undertaken a study of the action of ultra-violet light on rubber in order to prove whether the double cis-linkages of rubber undergo a transposition into trans-linkages, for numerous instances are known where light causes these cis-trans-transpositions. In the case of rubber, one should obtain, therefore, either a hydrocarbon of the gutta-percha type or, if light causes a sort of cis-trans-equilibrium, a hydrocarbon with double cis-linkages distributed irregularly. In our experiments we were extremely careful to exclude oxygen, since some years ago Henri proved that ultra-violet light activates greatly the oxidation of rubber. On the other hand it is known that oxidation causes a diminution in the length of the chains which modifies considerably the physical properties, for example, the viscosity, and which may mask the effect produced by light.

scholarly journals Studies on air-borne virus infections: II. the killing of virus aerosols by ultra-violet radiation

1943 ◽  
Vol 43 (1) ◽  
pp. 11-15 ◽  
Author(s):  
D. G. ff. Edward ◽  
Dora Lush ◽  
R. B. Bourdillon
Keyword(s):  
Influenza Virus ◽  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Wave Length ◽  
Ultra Violet ◽  
Virus Infections ◽  
Ultra Violet Radiation ◽  
Vaccinia Viruses ◽  
Simplex Virus ◽  
Violet Radiation

The experiments show that rapid and effective sterilization of atmospheres containing atomized particles of influenza and vaccinia viruses, and probably also of herpes simplex virus, can be obtained by ultra-violet radiation of wave-length 2537 A. At least 99 % and probably more of an aerosol of influenza virus was killed by exposure for 6 sec. at. a distance of 2 cm. from either a Hanovia lamp or a G.E.C. ‘Sterilamp’. These findings confirm the work of Wells and his associates who first demonstrated the susceptibility of this virus to ultra-violet radiation (Wells & Brown, 1936; Wells & Henle, 1941). At the same distance the ‘Sterilamp’ produced more than a 99 % kill of vaccinia virus with an exposure of 1 sec. and about a 90 % kill in 0·5 sec. The experiments with herpes were less satisfactory but suggested a similar sensitivity. These results support the view that ‘germicidal’ lamps are likely to be useful in reducing the infectivity of air contaminated with particles from persons suffering from virus infections of the respiratory tract.We wish to acknowledge our indebtedness to the late Sir Patrick Laidlaw who, although his name does not appear as author, largely inspired the investigation and took an active part in it until his death.

Studies on the Joule Effect in Rubber. I. The Thermal Effect on Stretched Vulcanized Rubber

1935 ◽  
Vol 8 (2) ◽  
pp. 174-176
Author(s):  
Yoshio Tanaka ◽  
Shū Kambara ◽  
Hironosuke Fujita
Keyword(s):  
Carbon Black ◽  
Thermal Effect ◽  
Ultra Violet ◽  
Sulfur Compounds ◽  
The Other ◽  
Joule Effect ◽  
Ultra Violet Radiation ◽  
Vulcanized Rubber ◽  
High Heating ◽  
Violet Radiation

Abstract The experiments may be summarized as follows: 1. With an increase in the time of cure, the elongation and heating elongation diminish and the Joule effect increases. 2. An increase in the vulcanization coefficient is followed by a decrease in the elongation and heating elongation and an increase in the Joule effect. The increase in the Joule effect, however, has a limit. 3. An organic accelerator reduces the elongation and heating elongation and increases the Joule effect. 4. The greater the degree of mastication the greater the elongation and the heating elongation and the less the Joule effect. 5. By exposure to ultra-violet radiation, the elongation and heating elongation are increased and the Joule effect decreased. 6. A filler increases the heating elongation and decreases the elongation and the Joule effect. Thus samples with relatively high elongations at a definite tension have relatively high heating elongations and low Joule effects. Such specimens seem to have been affected by the disaggregation and depolymerization of the rubber molecules. The effects of the time of cure, mastication, and exposure to ultra-violet radiation prove this fact. Vulcanization increases the Joule effect, but on the other hand, it is accompanied by a disaggregation and depolymerization of the rubber molecules, so the increase in the Joule effect with the progress of vulcanization has a limit. On vulcanization with an accelerator, the combination of sulfur occurs so rapidly that the increase in the Joule effect is predominant. A filler, such as carbon black, behaves only as a diluent of Joule effect. These results lead to the conclusion that the more highly polymerized rubber molecules and their sulfur compounds seem to be the chief factor in the Joule effect of vulcanized rubber.

scholarly journals Certain pathological effects of ultra-violet radiation on mosquito larvæ and pupæ

1932 ◽  
Vol 112 (774) ◽  
pp. 27-38 ◽  
Keyword(s):  
Ovarian Function ◽  
Wave Length ◽  
Ultra Violet ◽  
Mercury Vapour ◽  
Mosquito Larvae ◽  
Wave Band ◽  
Ultra Violet Radiation ◽  
Quartz Mercury ◽  
Mercury Vapour Lamp ◽  
Violet Radiation

In the course of recent work on the possible effect the ultra-violet wave-band may have on the activation of ovarian function in female mosquitoes, it became apparent that mosquito larvae are highly susceptible to a remarkable form of injury by radiations from the unshielded mercury-arc generated by the ordinary Cooper-Hewitt vacuum type of quartz mercury-vapour lamp. This effect upon the larvae has been studied, and an attempt was made (1) to determine the wave-length of the radiations responsible for the injury by means of screens interposed between the lamp and the larvae; and (2) to ascertain the physiological and histological nature of the injury.

scholarly journals Measurements of the sun’s ultra-violet radiation and its absorption in the earth’s atmosphere

1923 ◽  
Vol 104 (725) ◽  
pp. 252-271 ◽  
Keyword(s):  
Wave Length ◽  
Solar Spectrum ◽  
Ultra Violet ◽  
Upper Atmosphere ◽  
Stray Light ◽  
Solar Constant ◽  
Absorption Bands ◽  
Ultra Violet Radiation ◽  
Short Period ◽  
Violet Radiation

1. It is now well known that a connection exists between the variations in solar phenomena and changes in terrestrial weather. Thus the occurrence of an eleven-year cycle in the earth’s temperature, rainfall, etc., which is coincident with the eleven-year period of sunspots has long been recognised. More recently a marked connection has been found between the irregular short -period variations also. In this connection the work of H. H. Clayton, of the Argentine Meteorological Service, may be particularly mentioned. He has found that a very definite connection exists between the variations of the “solar constant,” as measured by the Smithsonian Astrophysical Department, and the temperature and rainfall some few days later in South America. The causes which lead to this connection are at present not known, though various theories have been proposed. For example, it has been suggested that the short wave-length radiation from the sun will produce ozone from oxygen in the upper atmosphere, and owing to the absorption bands of ozone both in the infra-red and ultra-violet, a change in the amount of this gas might change the radiation equilibrium temperature of the upper atmosphere, and so affect the pressure and temperature of the air below. The measurements of ultra-violet radiation made during “solar constant” determinations by the Smithsonian Institute are very uncertain, owing to the relatively small energy in this part of the solar spectrum, and the large errors due to stray light in the spectrometer. Since the measurements here described were started, Fabry and Buisson have published measurements of the amount of ozone in the atmosphere—measured spectroscopically—but only for about a dozen days.

scholarly journals Effects of ultra-violet radiation upon involuntary muscle, and the supposed physiological interference of visible rays

1926 ◽  
Vol 99 (696) ◽  
pp. 221-229 ◽  
Keyword(s):  
Ultra Violet ◽  
The Other ◽  
Pigment Cells ◽  
Mercury Vapour ◽  
Ultra Violet Radiation ◽  
The Earth ◽  
Involuntary Muscle ◽  
Mercury Vapour Lamp ◽  
Violet Radiation ◽  
Exciting Effect

It was shown by Adler (1) that involuntary muscle is excited and its tone increased by radiation with ultra-violet rays. The excised frog’s stomach, the bladder and the uterus of the rabbit, and that of the guinea-pig, were suspended by him, each in a suitable salt solution, and excited by the mercury vapour lamp. With a glass screen interposed no result was obtained, the visible and longer ultra-violet rays, e. g ., those longer than about 3200 A. U., having no exciting effect. There may be recalled the old observation of Lambert (1760) that the excised iris of fish and frogs reacts to light by contraction; the visible rays in this case act through the pigment which absorbs them (Steinach, Hertel). Contraction of the pigment-free ventral band of the earth-worm can be produced by ultra-violet, but not by visible rays. On the other hand, visible rays excite the pigmented ventral band of Sipunculus nucleus (Hertel, 2). Probably the nerve plexus is excited by the conversion of visible rays into heat in the pigment cells which absorb these rays.

scholarly journals The action of ultra-violet radiation on barium and strontium azides

1939 ◽  
Vol 172 (950) ◽  
pp. 299-314 ◽  
Keyword(s):  
Induction Period ◽  
Alkaline Earth ◽  
Room Temperature ◽  
Wave Length ◽  
Ultra Violet ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Ultra Violet Radiation ◽  
Pre Treatment ◽  
Violet Radiation

The alkaline earth azides decompose at appreciable rates at temperatures above 100° C, and the reactions which occur are of the accelerating type increasing in speed as the 6th-8th power of the time, there being a marked induction period during which the reaction occurs at a negligible rate (Harvey 1933; Marke 1937; Maggs 1939). The decomposition is accelerated and the length of the induction period shortened when the solid is acted upon by β -rays at room temperature before the heat treatment (Garner and Moon 1933; Maggs 1939). It was, therefore, possible that ultra-violet light would cause an acceleration of these reactions in a similar manner. Muller and Brous (1933) have shown that sodium azide is decomposed by ultra-violet light at a rate which is proportional to the intensity and that the threshold wave-length for the decomposition is around 405 m µ . In the present investigation it is shown that barium and strontium azides are decomposed by ultra-violet light at room temperature and that the thermal decomposition of these substances is accelerated by pre-treatment with this radiation.

Absorption of ultra-violet radiation by the atmospheric gases

1956 ◽  
Vol 236 (1205) ◽  
pp. 216-226 ◽  
Keyword(s):  
Cross Section ◽  
Theoretical Data ◽  
Ultra Violet ◽  
Model Atmosphere ◽  
Atmospheric Gases ◽  
Absorption Bands ◽  
Ultra Violet Radiation ◽  
Order Of Magnitude ◽  
Photo Ionization ◽  
Violet Radiation

The order of magnitude of absorption coefficients for photo-ionization and photo-dissocia­tion continua and their relation to absorption lines and absorption bands are discussed. Measurements and calculations of N 2 , O 2 , N, O and O 3 are summarized and ‘depths of penetration’ into the ‘model atmosphere’ assumed by the Rocket Panel are given. Absorp­tion data for the minor atmospheric constituents are tabulated. The relation of absorption cross-section results to theories of the ionosphere is briefly discussed. Classified references to experimental and theoretical data are given.

scholarly journals The origin of the erythema curve and the pharmacological action of ultra-violet radiation

1938 ◽  
Vol 126 (843) ◽  
pp. 241-256 ◽  
Keyword(s):  
Experimental Data ◽  
Human Skin ◽  
Wave Length ◽  
Ultra Violet ◽  
Pharmacological Action ◽  
Ultra Violet Radiation ◽  
Violet Radiation

The general quantitative features of the dependence on wave-length of the production of erythema in human skin by ultra-violet radiation were established, as is well known, by the classical investigations of Hausser and Vahle (1921, 1927; cf. Hausser 1928, 1934). Subsequent measurements by Luckiesh, Holladay and Taylor (1930), Uhlmann (1930), and Coblentz, Stair and Hogue (1931) have confirmed and extended the results, so that there are now available relatively complete quantitative experimental data in terms of which the pharmacological actions of ultra-violet radiation must be interpreted.

scholarly journals Assay of xylanolytic activity of mutants of Neurospora crassa (Ema 5297) induced with ultra-violet radiation

2018 ◽  
Vol 44 (3) ◽  
pp. 475-478
Author(s):  
Nelofar Yesmin ◽  
Tahsina Haque ◽  
Mozmader Tima ◽  
Suman Mohajan
Keyword(s):  
Neurospora Crassa ◽  
Culture Supernatant ◽  
Wave Length ◽  
Xylanase Activity ◽  
Ultra Violet ◽  
Considerable Effect ◽  
International Unit ◽  
Ultra Violet Radiation ◽  
Xylanolytic Activity ◽  
Violet Radiation

Mutation was induced in Neurospora crassa (Ema 5297) with UV (having the wave length of 254 nm) irradiation. Three groups of biochemical mutants (leucine, tryptophan and arginine) were obtained. Ema and 7 leucine mutants were used to evaluate whether mutation has any considerable effect for the production of such enzyme. Enzymatic activity was expressed as International Unit (IU). It was found that N. crassa mycelia secrete xylanases to the culture supernatant. Mutant Y10 showed highest xylanase activity (1.663 IU) and wild N. crassa (Ema) showed lowest (0.416 IU) activity.

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