Influence Of High Energy Radiation Research Articles

Effect of the sol-gel condition on photostability and optical properties of alkoxy-substituted zinc phthalocyanine in the hybrid glass matrix

The series of sol-gel synthesis was prepared using different organic and inorganic acids and bases, and with different polarity of solvents, and with various concentration of the luminophore to immobilize zinc phthalocyanine to the matrix. Immobilization was achieved by coordination of zinc phthalocyanine in the axial position with isonicotinamide substituted by alkoxysilane. By using siloxane precursors, matrices of variable hydrophilicity were obtained by the sol-gel method in order to select the optimal environment for phthalocyanine immobilization. The optical properties of phthalocyanine (fluorescence and thermoluminescence) of hybrid materials were investigated. Finally, tests of material photostability under the influence of high-energy radiation were carried out with emission measurement in the ultraviolet and visible range. The aim of this study was to optimize the conditions for obtaining hybrid material containing phthalocyanine for potential application in optoelectronic systems, such as, photodiodes.

Radiation effects on phosphate glasses: Review

AbstractGlass and its properties are subject to a variety of changes under the influence of high energy radiation. Therefore, radiation‐induced defects in glasses requires high attention due to the wide application of glasses in optics on board space craft, in image guides for reactor inspection, in optical fiber waveguide and in mobilization of high level radioactive waste, for example . In this paper, we present a mini review on radiation effects on phosphate glasses. We review the influence of various irradiation sources on the response of phosphate glasses, focusing on the advances over the past decades.

Geochemical Cycle of Radon and its Bioremediation Opportunity from Water Environment: A Review.

The waterborne or airborne radon causes carcinogenesis in the human bodies due to the continuous decay of α- and β- particles. The health risks related to radioactive radon instigate to develop an advanced technology for its removal from the environment. There are two standard techniques, such as aeration and activated carbon filtration, available for its removal. However, both of them face different technological drawbacks resulting in the processes either inefficient or inappropriate for the purpose. There are several technologies utilizing either algae or microorganisms that could be useful in the bioremediation of radon. Some of the algae and microorganisms are examined and found to be tolerated and decontaminated various ionization radiations like α-, β-, and γ- radiations. In a US patent, the microalgae Coccomyxa actinabiotis isolated from a nuclear facility showed the properties of bioremediation towards radionuclides. They overcome the physiological stress in the extreme environment for their growth due to the evolution under the prolonged influence of high energy radiation. Further, they are stimulated by the process of cloning, genetic transformations and adaptations for the purpose of enhancing the tolerance and decontamination power. Therefore, biotechnological researches have lots of prospects to remove radon from the water environment using algae and microorganisms.

Surface properties of poly(lactic acid)/polyacrylate semi-interpenetrating networks – Effect of UVC radiation

Poly(lactic acid), PLA, was blended with multifunctional acrylate monomer (dipentaerythritol pentaacrylate) in various weight ratios (1:1 and 9:1). The reaction of photopolymerization of the acrylate monomer in poly(lactic acid) matrix was conducted to obtain semi-interpenetrating networks in the form of films dedicated for use in the packaging industry. Next, the PLA/polyacrylate films were exposed to UVC radiation in order to examine their photostability under the influence of high energy radiation, which can be used as sterilizing factor. In these studies, the following methods have been applied: contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). These methods made it possible to determine the influence of sample composition on the surface properties and photochemical resistance. It was found that PLA was the most susceptible to UVC-irradiation among the studied samples. In PLA/polyacrylate films UV light induced a slight increase in surface roughness and only negligible changes in surface polarity and chemical composition. The mechanism of photodegradation in the tested specimens was also discussed.

Radiation-induced explosive initiation

A model for explosive initiation under the influence of high energy radiation has been developed. The possibility for comparing explosive initiation conditions under the influence of radiation pulse and shock wave loads of microsecond duration has been shown and the initiation conditions as a function of the radiolysis constants have been determined.

高エネルギー放射線のペースメーカへの影響

高エネルギー放射線のペースメーカへの影響

High energy proton beam bombardment of polyaniline

Irradiation effects of 35 MeV proton beam bombardment on polyaniline (PAn) have been studied. PAn was made by standard MacDiarmid method, and the irradiation was performed at ambient temperature lower than 20°C. A 511 keV γ photon was detected by γ spectrum analysis, and a nuclear reaction 14N(p,α) 11C in collaboration of 12C(p,pn) 11C took place. By means of chemical ionization, mass spectra of samples before and after ion bombardment were recorded. Experimental results showed that products such as ▪ and cyclic compounds like ▪ and ▪ were produced. IR spectra and SEM micrographs gave results of vibrational frequency shifts and morphology consistent with mass spectrometry. Finally we conclude that high energy proton beam bombardment resulted in main-chain scission and carbonization of PAn. Although the electrical conductivity reduced from 0.72 to 0.62 S cm -1, it retained at the same level. This implies that PAn might be used under the influence of high energy radiation.

Radiation effects in glasses

Glass was produced by man about 4000 years ago. The scientific exploration of glass is very young and closely connected with Jena. Fraunhofer, Goethe, DobEreiner, Abbe, Zeiss and Schott are famous names on this field.Both crystals and glasses are solids. However, there are fundamental differences in their properties and behavior. Glass is a thermodynamically unstable state and has a defect structure compared to the crystal. Glass and its properties arc subject to a variety of changes under the influence of high energy radiation. In general, effects extend from the reduction of specific ions to the collapse of the entire network. Ultraviolet and X-ray radiation effects on UV-transmitting glasses will be discussed.

Radiation sterilization of polymeric implant materials.

High-energy irradiation sterilization of medical devices and implants composed of polymeric biomaterials that are in contact with tissue and/or blood, may adversely affect their long-term mechanical and/or biological performance (tissue and/or blood compatibility). Since many polymeric implants may contain trace quantities of catalysts and/or other additives, the effect of high-energy radiation on these additives, and possible synergistic effects with the polymer chains under the influence of high-energy radiation, must be considered. It is essential to indicate whether polymeric implants are used in short-term (acute) or long-term (chronic) applications. Relatively small changes in their physicochemical, mechanical, and biological properties may be tolerable in the short term, whereas similar changes may lead to catastrophic failures in long-term applications. Therefore, polymeric implants which are to be sterilized by high-energy irradiation should be carefully evaluated for long-term property changes which may be induced by the radiation.

Radiation curing of epoxies

The literature on radiation polymerization of epoxy compounds has been reviewed to assess the potential use of radiation for curing these industrially important monomers. Chemical curing of epoxies may proceed by either cationic or anionic mechanisms depending on the nature of the curing agent, but most epoxies polymerize by cationic mechanisms under the influence of high-energy radiation. Radiation-induced cationic polymerization of epoxy compounds is inhibited by trace quantities of water because of proton transfer from the chain-propagating epoxy cation to water. Several different methods with potential for obtaining high molecular weight polymers by curing epoxies with high-energy radiation have been studied. Polymeric products with epoxy-like properties have been produced by radiation curing of epoxy oligomers with terminal acrylate groups and mixtures of epoxies with vinyl monomers. Both of these types of resin have good potential for industrial-scale curing by radiation treatment.

High energy solar radiation and the origin of life.

Recent satellite observations of young, sun-like stars allow an estimation of the ultraviolet and X-ray radiation environment of the primitive Earth. Energy from these sources is found to be much higher than previously believed. We suggest that the influence of high energy radiation on the early development of life be reexamined.

Influence of high energy radiation on the glasstransition of poly(methyl methacrylate)

Chemical changes produced by irradiation of crystalline polymers can be monitored quantitatively by DTA measurements of the melting point. The purpose of the present work is to investigate whether or not similar information can be obtained for a non-crystalline polymer by measurements of the glass transition temperature ( T g). Atactic poly(methyl methacrylate) (PMMA) was exposed to 137Cs γ-rays. After degassing and heat treatment, samples were scanned using a DuPont 990 Thermal Analyzer. By either the conventional or a tangent data analysis technique, T g measurements not only agreed with previously reported data up to a dose of 75 Mrad but also were extended up to 500 Mrad. Moreover, the empirical plot of T g vs. M −1 n agreed with data obtained by free-radical polymerization and was judged to be a suitable calibration curve for estimating the radiation damage from DTA measurements. For samples of PMMA prepared both by irradiation and by free-radical polymerization, the dependence of T g on molecular weight best fitted the theoretical expression of Gibbs. Using a reduced variables plot, the present results for irradiated PMMA compared well with synthesized vinyl polymers, substantiating the dominance of simple chain fracture.

Anionic Polymerization of β-Nitrostyrene under the Influence of High Energy Radiation

Abstract β-Nitrostyrene (βNS) was polymerized in aprotic solvents. The rate of polymerization increased in the series dimethyl sulfoxide ≈ dimethylformamide < N-methylpyrrolidone < hexamethylphosphoric triamide (HMPT). From copolymerization experiments with α-methylstyrene and methacrylonitrile, evidence for an ionic mechanism was obtained. Electron scavengers inhibited the polymerization. Thus it was concluded that in dilute solution the initiation comprises the thermaliza-tion of electrons which become solvated and react with β NS to form the radical anion βNS. Pulse radiolysis experiments were carried out in HMPT. The spectrum of an intermediate (presumably -βNS−) was recorded. By measuring the rates of the formation of -βNS− and of the decay of solvated electrons the rate constant k e (9 ± 3) × 109 liter/mole-sec was determined. At higher monomer concentrations the polymerization was autoinhibited which is probable due to the fact that direct absorption of radiation by the monomer becomes important.

Internal stresses in cold-drawn and irradiated polyethylene

The influence of high-energy radiation on the internal stress level in cold-drawn, high- and low-density polyethylene, with and without subsequent annealing, has been determined using a stress relaxation method described earlier. The internal stress level (σ i) is found to increase substantially with the radiation dose for doses below 40 Mrad, while the increase at higher doses is only moderate. It is suggested that the initial increase is due to a preferred cross-linking of the amorphous phase or the fold surface of the lamellae. An exception to this behaviour was observed for cold-drawn low-density polyethylene, where the internal stress decreased as the radiation dose was raised.

The effect of methanol on the polymerization of acrylamide in aqueous solution

T~E polymerization of acrylamide has previously been studied mainly in solution in water [1-12], in which the monomer and polymer are readily soluble, and also in the solid state under the influence of high energy radiation [13]. Some isolated experiments on polymerization of acrylamide in methanol, which precipitates the polymer, in water and in water-alcohol mixtures [14] have shown that increase in the water content of the water-alcohol mixture leads to increase in the specific viscosity of the polymer. The rate of polymerization in dilute aqueous solution is approximately an order of magnitude higher than in methanol. The present work is devoted to a more detailed examination of the effect of methanol on the polymerization of acrylamide.

The Influence of High Energy Radiation on Cotton

Sliver lap, yarn, and fabric made of the same raw cotton of known composition were irradiated with cathode rays under various conditions. Changes in the chemical and physical properties were investigated. Some yarns also were irradiated with gamma rays. The changes that occurred in these samples were found to be the same as those in samples irradiated with cathode rays. Data for the copper number, the methylene blue number, and the intrinsic viscosity indicated that degradation of the cathode ray irradiated yarn had taken place. A new absorption maximum was found in infrared spectrograms of the cotton irradiated at high dose levels. Direct-dye affinity of the irradiated fabric was similar to oxycellulose. The tensile strength of the yarn decreased with the amount of dose it received. However, at low levels the tensile strength was found to increase to a maximum before it started to decrease; a "natural curve" of tensile strength and a "natural curve" of toughness were defined. Microbiological tests showed that both yarn and fabric were sterilized by a dome of one megarep. A general increase in mildew resistance was noted in irradiated samples compared with unirradiated samples. '

Effect of additives on the radiation induced polymerization of Isobutene

The polymerization of certain monomers under the influence of high energy radiation is believed to proceed by an ionic mechanism. The yield is found to be greatly increased in the presence of fine powders of some metallic oxides, such as zinc oxide and silica. It is reduced by the presence of polyethylene powder, in which radicals are produced by radiation. Data on the effect of zinc oxide concentration, dose and radiation intensity are given. The increased yield is due to an increased initiation rate.

Influence of high energy radiation on the oxidation of oleic acid and methyl oleate. II. Sites of oxygen attack

Summary The hydroperoxides formed by the γ‐irradiated autoxidations of methyl oleate at 7.5°C. and 56°C. have been characterized. The mono‐ and dicarboxylic acids produced by γ‐irradiated autoxidation at 56°C. and by cobalt‐catalyzed γ‐irradiated autoxidation at 73°C. have also been examined. The hydroperoxides were found to be a mixture of the 8‐, 9‐, 10‐, and 11‐hydroperoxidoöleates in both samples. They were present in the order 10&gt;11&gt; 9&gt;8. Evidence is presented for the presence of octanoic, nonanoic, octandioic, and nonandioic acids in the 56°C. autoxidation. Octanoic and nonanoic acids were also present in the cobalt‐catalyzed autoxidation. No significant departure from non‐irradiated autoxidations was found.

Influence of high energy radiation on oxidation of oleic acid and methyl oleate

Summary Gamma radiation from Cobalt 60 influences the oxidation of oleic acid and methyl oleate even at low temperatures. Determination of peroxide values, carbonyl values, and the E1cm1%. values at 224 mµ revealed that high peroxide values could be obtained but that secondary products are formed in appreciable quantities. The products causing absorption at 224 mµ may be α,β‐unsaturated ketones. The level of these substances can be increased by irradiation‐oxidation in the presence of metal soaps such as cobalt stearate. Irradiation‐oxidation of methyl oleate through a series of temperature ranges from 7.5°C. to 55°C. reveals a marked thermal activation effect. Peroxide values of 2000 me/kg or greater are obtained in 100 hrs. of reaction time.