Radiation Chemical Studies of Protein Reactions: Effect of Irradiation Liquids Containing Aromatic Hydrocarbons and pH on the Breaking of Secondary Bonding in Protein

When protein in various liquids containing aromatic hydrocarbons, such as benzene, naphthalene, and phenanthrene, is irradiated by γ-rays from a ⁶⁰Co source, the breaking of secondary bonding in the protein molecule varies with the irradiation liquids containing aromatic hydrocarbons. Protein irradiated by γ-rays from a ⁶⁰Co source in air showed the effect of pH on the breaking of secondary bonding in the protein molecule. In both cases an empirical equation for the viscosity change was obtained, and the phenomena were explained on the basis of the molecular mechanism.     

Radiation chemical studies of protein reactions: Effect of irradiation liquid containing aromatic hydrocarbons and pH on viscosity

When protein is irradiated by γ-rays from a ⁶⁰Co source in various liquids containing aromatic hydrocarbons, such as benzene, naphthalene, and phenanthrene, the effect of the radiation varies with the irradiation liquids containing aromatic hydrocarbons. An empirical equation for the viscosity change was obtained. Protein irradiated by γ-rays from a ⁶⁰Co source in air showed the effect of pH on protein reactions. An empirical equation for the viscosity change was obtained.     

Radiation Chemical Studies of Protein Reactions: Effect of Post-irradiation on Optical Rotation

When protein was irradiated by γ-rays from a ⁶⁰Co source, a post-irradiation effect of protein reaction was caused. An empirical equation for the optical rotation was obtained, and the phenomena were explained on the basis of the molecular mechanism. The general equation for the optical rotation is given by [α] f= a ? b log t, where [α] f is the final specific rotation of the solution, t is time after γ irradiation, and a and b are adjustable constants.     

Radiation Chemical Studies of Protein Reactions: Effect of Irradiation Atmosphere and Temperature on Optical Rotation

When protein in various atmospheres such as N₂, O₂, H₂, CO₂, and NH₃ is irradiated by γ rays form a ⁶⁰Co source, the changes in the internal relationships of the atoms in the protein molecule vary with the gases composing the irradiation atmosphere. An empirical equation for the optical rotation was obtained. Protein irradiated by γ rays showed the effect of temperature by changes in the internal relationships of the atoms in the protein molecule. An empirical equation for the optical rotation was obtained. The behavior of optical rotation shows a similar dependence on irradiation atmosphere and temperature as shown in earlier viscosity experiments.     

Radiation Chemical Studies of Protein Reactions: Effect of Post-irradiation on the Breaking of Secondary Bonding in Protein

When protein was irradiated by prays from a ⁶⁰Co source, a post-irradiation effect of the breaking of secondary bonding in protein was caused. An empirical equation for the reactivity decay was obtained, and the phenomena were explained on the basis of molecular mechanism.     

Radiochemical ageing of ethylene-propylene-diene elastomers. 4. Evaluation of some anti-oxidants

The preceding papers of this series were devoted to the identification and quantification of the main chemical changes resulting from the radiochemical ageing of EPDM (77.9% ethylene, 21.4% propylene, 0.7% diene) and EPR (76.6% ethylene, 23.4% propylene) films irradiated under oxygen atmosphere using ⁶⁰Co γ-rays. It was shown that two processes are involved in the EPDM radio-oxidation. The random γ-radiolysis of the polymer provides a constant source of macro-alkyl radicals that are likely to initiate a selective oxidation of the polymer through free-radicals reactions involving the abstraction of labile hydrogen atoms. In the present paper, infrared spectroscopy has been used to study the γ-degradation of EPDM cross-linked with dicumyl peroxide and/or stabilised with two types of anti-oxidants (hindered phenol or amine-type). The results show that the anti-oxidants are not efficient in preventing oxidation. To understand the lack of efficiency of the stabilisers, the impacts of the various formulations on the rate of degradation of EPDM against chain oxidation involved in thermal and UV ageing were also studied.     

Radiation Chemical Studies of Protein Reactions: Effect of Chelating Agents on Optical Rotation

Abstract

1,2-Diamine and 1,2-dihydroxy derivatives such as ethylene-diamine, ethylenediaminetetraacetic acid and propylene glycol were found to protect against changes in the internal relationships of the atoms in the protein molecule from radiation damage. The optical rotation behavior closely resembles that found with amino acid as shown by a similar dependence on the concentration.     

Radiation Chemical Studies of Protein Reactions: Effect of Sulfur-Containing Compounds on Optical Rotation

Thiourea, thioglycol, and β, β′-thiodiglycolic acid were found to protect against changes in the internal relationships of the atoms in the protein molecule from radiation damage. The optical rotation behavior closely resembles that of amino acid which shows a similar dependence on concentration.     

Radiation Chemical Studies of Protein Reactions: Effect of Alkaline-Earth Metals on Optical Rotation

Magnesium chloride, calcium chloride, strontium nitrate, and barium chloride were found to protect against changes in the internal relationships of the atoms in the protein molecule from radiation damage. The optical rotation behavior closely resembles that of amino acids by showing a similar dependence on the concentration.     

High-resolution NMR studies on radiolytic reactions in polyethylene

High-resolution NMR spectra was obtained for linear polyethylene powder irradiated by ⁶⁰Co γ-rays in vacuo or in air. For the sample irradiated in vacuo, the spectra consist of two components having different line width. The narrow component was assigned to soluble molecules and the broad one to gel. When samples are irradiated in air, their spectra show no broad component. The GPC curves obtained for the samples irradiated in air shift to high elution counts (low molecular weight) upon increase of the irradiation dose. It is concluded that oxidative degradation is the predominant reaction in the sample irradiated in air.     

Degradation of Erioglaucine Dye Under γ-irradiation

The kinetics and the mechanism degradation of erioglaucine dye in aqueous solution irradiated under γ-rays from ⁶⁰Co are investigated. From the results of the absorption UV-Vis spectra of 0.7 mM erioglaucine solution as function of dose, the concentration of erioglaucine decreases exponentially with increasing the γ-irradiation dose and the plot on a logarithmic scale against the dose shows a clear pseudo first order rate. The apparent pseudofirst order rate constant (kapp= 1.8¥10^-3 min^-1) was calculated. We also found the degradation mechanism as results of mass-spectrum analyses of the degradation products under the γ-irradiated erioglaucine solution. The results show that the principal cleavage is the C-N bond.     

Molecular weight and antioxidant effects on the structure of irradiated linear low density polyethylene

Linear copolymers of ethylene and butene-1 with uniform chemical microstructure and very narrow molecular weight distribution are used to study the effects of ionizing radiation. The well characterized copolymers are irradiated at room temperature with γ-rays from a ⁶⁰Co source. To follow the evolution of the molecular structure with the radiation doses, changes in molecular weight averages M_n and M_w are measured by membrane osmometry, light scattering and GPC.The influence of the original linear polymer molecular weight is examined in the range of 50,000–100,000. The effects of antioxidant are explored irradiating samples with and without additive.     

The investigations on K and L X-ray fluorescence parameters of gold compounds

The study aimed to determine the chemical effects on the K and L X-ray intensity ratios and the K and L X-ray production cross sections for gold compounds. The K shell fluorescence yields and L shell average yields were also investigated. The samples were excited by 59.5 keV γ-rays from an ²⁴¹Am annular radioactive source and 123.6 keV γ-rays from a ⁵⁷Co annular radioactive source. K and L X-rays emitted from samples were counted by an Ultra-LEGe detector with a resolution of 0.150 keV at 5.9 keV. The experimental values were compared with theoretical, the semi-empirical and other experimental values.     

Effect of evolved hydrogen fluoride on radiation-induced crosslinking and dehydrofluorination of poly(vinylidene fluoride)

Poly(vinylidene fluoride) (PVdF) was irradiated by ⁶⁰Co γ-rays with and without potassium hydroxide (KOH) under vacum. KOH tablets were added to absorb completely hydrogen fluoride (HF) which is the main volatile product of radiolysis of PVdF in the irradiation cell. In the presence of HF, the rates of radiation-induced crosslinking and dehydrofluorination of PVdF were lower than those in the absence of HF. The experimental results are discussed from the standpoint of stabilization of alkyl free radicals in PVdF by reaction with hydrogen fluoride.     

The effect of divinylsulfone on the irradiation crosslinking of polypropylene

Polypropylene films were irradiated with ⁶⁰Co γ-rays in divinylsulfone (DVS) or butadiene (BD) gases. The variations of the intrinsic viscosities of the samples irradiated in vacuum or in DVS with dose showed usual patterns but the variation of the latter was somewhat more rapid. The intrinsic viscosity of the sample irradiated in BD could not be measured due to the early appearance of gel. The gel fraction of the sample irradiated in DVS appeared at lower dose than that irradiated in vacuum, but the former did not increase as much as the latter. The gel fraction of the sample irradiated in BD increased remarkably. The concentrations of the two kinds of double bonds increased in the sample irradiated in BD but levelled off gradually with dose. ESR study showed that the polypropylene radical reacted with DVS to form anisotropic radicals. The mechanisms of the effects of both reagents on irradiation of polypropylene were discussed.     

Copper mining and mill analyses by γ-rays from capture of californium-252 neutrons

Copper mill materials from Utah and Nevada and rock cores from a geothermal drill hole at the Valies Grande Caldera in New Mexico were irradiated at the Los Alamos Scientific Laboratory with neutrons from a californium-252 source (about 10¹⁰ n s^-1), and the capture γ-rays were measured. The copper response, based on the 6.89-MeV double escape line, agreed sufficiently well with the known chemical composition of the materials to indicate usefulness of this technique for exploring copper deposits and for monitoring metallurgical extraction processes.     

Direct determination of crosslinking and chain scission in polymers

A direct method has been developed for determining G(crosslinks) for irradiated polymers using the analytical ultracentrifuge. The sedimentation velocity technique is employed to follow changes in the molecular weight of a narrow distribution polystyrene sample irradiated in vacuum with ⁶⁰Co γ-rays. It is shown that G(crosslinks) can be determined at low doses before significant structural changes have occurred in the polymer. At about one-fifth of the gel dose G(crosslinks) was found to be 0.019 compared to a value of 0.040 obtained from gel-sol fraction measurements. It is concluded that G(crosslinks) may increase with dose due to processes such as the addition of radicals to double bonds formed during the irradiation.     

Cations of aldehydes and ketones: an ESR study

Exposure of dilute solutions of acetaldehyde, acetone and cyclohexanone in fluorotrichloromethane to ⁶⁰Co γ-rays at 77 K gave the corresponding radical cations, characterised by ESR spectroscopy.     

Thermal expansion of irradiated polyethylene from 10 to 340 K

The coefficient of thermal expansion of γ-irradiated polyethylene has been measured from 10 to 340 K by using the three-terminal capacitance technique. The samples are irradiated to 500 Mrad in steps of 100 Mrad in air at room temperature with γ-rays from a Co⁶⁰ source at a dose rate of 0.3 Mrad/h. The crystallinity of the sample is measured by x-ray diffraction. The crystallinity is found to decrease with radiation dose. The thermal expansion coefficient is found to be constant with radiation doses from 10 to 110 K and decreases with doses from 110 to 340 K. © Wiley & Sons, Inc.     

Behavior of nitrogenated fungicides upon gamma-irradiation

Three nitrogenated fungicides (Bayfidan, Bayleton and Baycor) were irradiated with -rays from a⁶⁰Co source with the products being analyzed by high resolution gas chromatography (HRGC). Within the dose range studied (5 to 640 kGy), all three compounds were found to be stable.