scholarly journals THE KINETICS OF INACTIVATION OF COMPLEMENT BY LIGHT

1920 ◽  
Vol 3 (2) ◽  
pp. 169-183
Author(s):  
S. C. Brooks
Keyword(s):  
Temperature Coefficient ◽  
Molecular Species ◽  
Wave Length ◽  
Ultra Violet ◽  
Limiting Factor ◽  
Monomolecular Reaction ◽  
Rate Of Reaction ◽  
Effective Wave ◽  
Kinetics Of ◽  
Coefficient Of Diffusion

The photoinactivation of complement has been studied with a view to determining if possible how many kinds of molecules disappeared during the reaction. It was found that: 1. The apparent course of photoinactivation is that of a monomolecular reaction. 2. Diffusion is not the limiting factor responsible for this fact, because the temperature coefficient of diffusion is much higher than that of photoinactivation (Q10 = 1.22 to 1.28, and Q10 = 1.10 respectively). 3. There is no change in the transparency of serum solutions during photoinactivation, at least for light of the effective wave-length, which is in the ultra-violet region probably at about 2530 Ångström units. It is pointed out that under these conditions only one interpretation is possible; namely, that during photoinactivation a single disappearing molecular species governs the rate of reaction. This substance must be primarily responsible for the hemolytic power of serum when it is used as complement.

THE PREPARATION OF HEXACHLOROETHANE IN THE LIQUID PHASE BY CHLORINATION OF TETRA—AND PENTACHLOROETHANE

1946 ◽  
Vol 24f (5) ◽  
pp. 369-379 ◽  
Author(s):  
Jesse A. Pearce
Keyword(s):  
Liquid Phase ◽  
Temperature Coefficient ◽  
Slow Rate ◽  
Ultra Violet ◽  
Saturated Liquid ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Rapid Production ◽  
Effective Wave

Preliminary investigations showed a slow rate of production of hexachloroethane from chlorine-saturated liquid tetrachloroethane. The addition of some materials that often accelerate similar reactions was not effective here. However, rapid production was obtained by chlorinating tetrachloroethane in the presence of ultra-violet light. The effective wave-lengths appeared to lie between 3150 Å and 3540 Å, and the temperature coefficient between 75° and 100 °C. was 1.10. The result indicated that production of hexachloroethane from chlorine-saturated liquid tetrachloroethane was feasible. For the same conditions of illumination and temperature hexachloroethane was produced from chlorine-saturated pentachloroethane at a rate two and one-half times as fast as that in chlorine-saturated tetrachloroethane.

scholarly journals The coagulation of protein by sunlight

1922 ◽  
Vol 93 (651) ◽  
pp. 235-248 ◽  
Keyword(s):  
Temperature Coefficient ◽  
Tap Water ◽  
Wave Length ◽  
Ultra Violet ◽  
Protein Molecule ◽  
Mercury Vapour ◽  
Absorption Bands ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Mercury Vapour Lamp

It was first shown by Dreyer and Hanssen (1) in 1917 that ultra-violet light produced a change in protein solutions which appeared to be similar to coagulation by heat. They exposed various solutions in quartz chambers to the light of a Bang lamp with iron and silver electrodes. Vitellin was found most easily coagulated, while globulin, albumin and fibrinogen showed a decreasing sensitivity to ultra-violet rays in the order mentioned. These investigators also discovered that acids markedly increase the rate of precipitation. Soret (2) had shown in 1883 that there are absorption bands in the extreme ultra-violet region of the spectrum of various proteins, e. g. , casein, ovalbumin, mucin and globulin. Tyrosine likewise has this band in the ultra-violet and Soret attributed to this constituent of the protein molecule its power of absorbing ultra-violet rays. In this connection Harris and Hoyt (3) carried out some interesting experiments on the protective power of various substances for paramœcium cultures exposed to ultra-violet radiations. They found that gelatin peptone, amino-benzoic acid, cystine, leucine and especially tyrosine possessed the power of detoxicating ultra-violet rays when placed as a thin layer of aqueous solution over paramœcium cultures under a quartz-mercury lamp. The toxicity of the radiations for paramœcia or protoplasm in general can be understood in the light of the discovery of Dreyer and Hanssen coupled with that of Soret. From a physico- chemical standpoint Bovie (4) has published a study of the coagulation of proteins by ultra-violet light. By exposing solutions of crystalline ovalbumin, both dialysed and containing electrolytes, to the light of a mercury-vapour lamp, he came to the conclusion that there were two reactions involved in the coagulation of ovalbumin by ultra-violet light. The first is a photochemical one with a low temperature coefficient,—denaturation; and the second is one with a higher temperature coefficient of two and is dependent upon the electrolytes present,—coagulation. While using solutions dialysed against tap water Bovie made the observation that the protein appeared to become sensitive to light of longer wave-length, for his control tubes in glass were slowly coagulated.

scholarly journals The quantitative analysis of the photochemical bleaching of visual purple solutions in monochromatic light

1936 ◽  
Vol 156 (887) ◽  
pp. 158-170 ◽  
Keyword(s):  
Quantitative Analysis ◽  
Experimental Error ◽  
Wave Length ◽  
Monochromatic Light ◽  
Scotopic Vision ◽  
Monomolecular Reaction ◽  
The Subject ◽  
Dim Light ◽  
Kinetics Of ◽  
Adsorption Curve

In 1851 Muller noticed that under certain condition the rods of the frog's retina were coloured red. In 1876 Boll found that the retina bleached on exposure to light. This bleaching is now known to be due to the decolouration of a light sensitive pigment, visual purple or rhodopsin. It is generally accepted that this pigment place an important part in scotopic vision, i. e ., vision in dim light. Visual purple can be extracted from dark-adapted retinae by a number of reagents, including solutions of the salts and digitonin. The solutions of the pigments so obtained have been the subject of several spectrophotometric investigations. Trendelenburg in 1904 determined the adsorption curve of rabbits visual purple (maximum 507 mμ .) and also the relative efficiencies of different wave-lengths in bleaching the solutions. He established the similarity between the relative efficiencies and the human scotopic luminosity curve, as determined by him, for the same source of light. The adsorption curve has been determined by a number of other observers who find the maximum of adsorption of visual purple to be at about 500 for mammals, amphibia, etc., and at a variable wave-length for fish. Recently Hecht has studied the bleaching of visual purple solutions in white light. He showed that weak solutions bleach according to the Kinetics of a monomolecular reaction, the velocity constant being proportional to the intensity of the bleaching light and independent of the temperature within experimental error. In the present work the bleaching of visual purple in monochromatic light has been studied and, by means of absolute determinations of the light intensity, it has been found possible to apply fundamental photochemical principles to this reaction.

THE ALKALINE CLEAVAGE OF o-NITROBENZYLTRIMETHYLSILANE SOLVENT EFFECTS IN THE DIOXANE–WATER SYSTEM

1963 ◽  
Vol 41 (6) ◽  
pp. 1525-1530 ◽  
Author(s):  
H. R. Allcock
Keyword(s):  
Transition State ◽  
Solvent Effects ◽  
Water System ◽  
Solvent Polarity ◽  
High Water ◽  
Aqueous Dioxane ◽  
Alkaline Cleavage ◽  
Rate Of Reaction ◽  
Kinetics Of

The kinetics of alkaline cleavage of o-nitrobenzyltrimethylsilane were examined in aqueous dioxane media. At high water concentrations, increases in solvent polarity retard the cleavage, as required by a mechanism involving charge dispersion in the transition state. At high dioxane concentrations, solvent polarity increases are accompanied by increases in the rate of reaction, a result which may reflect association between the solvent components.

A STUDY OF THE MECHANISM AND KINETICS OF THE SULPHITE PROCESS

1939 ◽  
Vol 17b (4) ◽  
pp. 121-132 ◽  
Author(s):  
J. M. Calhoun ◽  
F. H. Yorston ◽  
O. Maass
Keyword(s):  
Temperature Coefficient ◽  
Arrhenius Equation ◽  
Practical Interest ◽  
Effect Of Temperature ◽  
Wood Meal ◽  
Spruce Wood ◽  
Mechanism And Kinetics ◽  
Kinetics Of

The rate of delignification of resin extracted spruce wood-meal has been determined in calcium-base sulphite liquor at temperatures from 130 °C. down to 50 °C. No break was found in the temperature coefficient curve at the lower temperatures, the reaction following the Arrhenius equation closely. Possible mechanisms of the reaction are discussed in the light of existing theories, and the effect of temperature on the yield of pulp is pointed out for its practical interest.

scholarly journals Kinetics of thiamin cleavage by sulphite

1969 ◽  
Vol 113 (4) ◽  
pp. 611-615 ◽  
Author(s):  
J. Leichter ◽  
M. A. Joslyn
Keyword(s):  
Aqueous Solutions ◽  
Rate Constant ◽  
Sulphur Dioxide ◽  
First Order ◽  
Ph Values ◽  
Rate Of Reaction ◽  
Kinetics Of

Results are presented on the rate of thiamin cleavage by sulphite in aqueous solutions as affected by temperature (20–70°), pH(2·5–7·0), and variation of the concentration of either thiamin (1–20μm) or sulphite (10–5000μm as sulphur dioxide). Plots of the logarithm of percentage of residual thiamin against time were found to be linear and cleavage thus was first-order with respect to thiamin. At pH5 the rate was also found to be proportional to the sulphite concentration. In the pH region 2·5–7·0 at 25° the rate constant was 50m−1hr.−1 at pH5·5–6·0, and decreased at higher or lower pH values. The rate of reaction increased between 20° and 70°, indicating a heat of activation of 13·6kcal./mole.

The mechanism of the oxidation of thiocyanate ion by peroxomonosulphate in aqueous solution. II. Kinetics of the reaction

1966 ◽  
Vol 19 (8) ◽  
pp. 1365 ◽  
Author(s):  
RH Smith ◽  
IR Wilson
Keyword(s):  
Aqueous Solution ◽  
Initial Rate ◽  
Stopped Flow ◽  
Thiocyanate Ion ◽  
First Order ◽  
Conductance Method ◽  
Rate Of Reaction ◽  
Kinetics Of

Initial rates of reaction for the above oxidation have been measured by a stopped-flow conductance method. Between pH 2 and 3.6, the initial rate of reaction, R, is given by the expression R{[HSO5-]+[SCN-]} = {kb+kc[H+]}[HSO5-]0[SCN-]20+ka[H+]-1[HSO5]20[SCN-]0 As pH increases, there is a transition to a pH-independent rate, first order in each thiocyanate and peroxomonosulphate concentrations.

Sign in / Sign up

Export Citation Format

Share Document