Effect of ionizing radiation on monument deteriorating microorganisms

The effect of⁶⁰Co -rays and detergents on bacteria isolated from monuments has been studied. Most of the heterotrophic bacteria examined were found to be resistant to radiation, whereas nitrifiers are moderately radio-resistant. The most effective growth supression of microorganisms was observed with the simultaneons application of ionizing radiation and detergents.     

Effect of ionizing radiation on various zirconium phosphate derivatives

Zirconium phosphate (-type), and zirconium phosphate-phosphite, and their silica containing forms were prepared. The products of syntheses and their purities and crystallinities were characterized by XRD diffraction. Thereafter the samples were irradiated with γ-rays (to 3×10⁶ Gy absorbed dose), after which irradiation the samples were again characterized. Comparison of the diffractograms reveals that irradiation does not result in detectable structural changes. Thus, application of these materials as sorbents and as ion exchangers is suggested in processes taking place under irradiation.     

Effect of type of ionizing radiation on radiation crosslinking of polyacrylonitrile fiber hydrolyzate

A comparative study was performed on the effect of different types of ionizing radiation differing by four orders of magnitude in dose rate, namely, γ-rays and electron-beam radiation, on the formation of the network structure in an aqueous salt solution of the industrial hydrolyzate of polyacrylonitrile fiber, as well as on the properties of irradiated solutions and polyelectrolyte gels obtained from these solutions. For the first time, it was shown that the efficiency of radiation-chemical processes induced by electron-beam radiation in macromolecules of the polyacrylonitrile fiber hydrolyzate is two-three times that in the case of γ-irradiation.     

Effect of ionizing radiation on lube oil fractions of heavy bituminous oils

Lube oil fractions of heavy bituminous oil from the Balakhany field in Azerbaijan has been the object of study. The features of radiation-chemical conversion of the lube oil fractions have been investigated. Laboratory studies were carried out in the absorbed dose range of 5–160 kGy at a dose rate of P = 0.27 Gy/s (γ-radiation). The IR spectra, the concentration, and the radiation-chemical yields of product gases at different doses have been measured. The results allow an assessment of the feasibility of manufacturing petrochemicals for various purposes by radiation processing.     

Direct effects of ionizing radiation on macromolecules

In the dry or frozen states, macromolecules are damaged directly by interactions with ionizing radiation. As γ‐rays and high‐energy electrons randomly ionize orbital electrons in their path, larger molecules are more likely to suffer an interaction with these radiations. In each interaction, energy is transferred to the struck molecule, resulting in irreversibly broken covalent bonds. There is an extensive literature describing these radiation modifications in both synthetic and biopolymers. Although many different properties are measured, there emerges a similar picture of the nature of radiation damage that is common to all macromolecules. The techniques used in study of one species may be used to resolve questions raised in the other class of macromolecules. © 2011 Wiley Periodicals, Inc.? J Polym Sci Part B: Polym Phys, 2011     

Effect of ionizing radiation on the quantitative detection of Salmonella using real-time PCR

Food irradiation is an economically viable technology for inactivating foodborne pathogens, but irradiation can mask pathogens in unhygienically prepared food. The aim of this study was to investigate the effect of irradiation treatment on the detection of Salmonella using real-time PCR. Three commercially available kits were tested, of which the InstaGene Matrix procedure was most effective in preparing template DNA from Salmonella exposed to radiation in broth culture. The minimum level of detection by real-time PCR combined with InstaGene Matrix was 3 log units of Salmonella per milliliter. However, when pure cultures of Salmonella were irradiated at 3 and 5 kGy, the cycle threshold (C_T) increased 1–1.5-fold compared to irradiation at 0 and 1 kGy. This indicated that irradiation treatment may result in an underestimation of bacterial counts due to radiation-induced DNA lesions. We also compared C_T values in inoculated chicken homogenates before and after irradiation, which in this model caused a 1.3–3.3-fold underestimation of bacterial counts with respect to irradiation dose.     

Effects of ionizing radiation on linear aromatic polyesters

The influence of chemical structure on the response of aromatic polyesters to high-energy ionizing radiation was studied. Systematic variations of polymers related to poly(ethylene terephthalate) were subjected to γ radiation, and the competitive chain scission and crosslinking reactions were determined by measuring changes in intrinsic viscosity and molecular weights. It was found that an increase in the paraffinic glycol segment of polyterephthalates facilitated crosslinking, while the protective nature of aromatic groups was demonstrated by modifying the dibasic acid segments. The influence of substituents on the terephthalate moiety was mixed: electronegative groups led to chain scission (as evidenced by decreased viscosities), but electropositive substituents exerted a stabilizing effect on polymer viscosity. In almost all cases, number-average molecular weights were decreased by exposure to γ radiation, regardless of viscosity behavior. Crystalline melting temperatures of the polymers generally were decreased by the combined radiation effects of chain scission and crosslinking.     

Wastewater treatment with ionizing radiation

In water treatment by ionizing radiation ^·OH is suggested to initiate the degradation of organics. In these reactions mostly carbon centred radicals form. Here we show that other inorganic radicals also highly contribute to the initiation of degradation. Cl^? and HCO₃ ^? in the treated water reacting with ^·OH transform to Cl ₂ ^·? and CO ₃ ^·? . In their reactions C-centred radicals form, too. The reactions of e _aq ^? and H^· water radiolysis intermediates may also produce carbon centred radicals. The C-centred radicals react readily with dissolved O₂, this is the starting step of the gradual oxidation.     

Degradation of chlorpyrifos by ionizing radiation

Summary A survey was carried out to determine radioactivity concentrations and associated dose rates from the naturally occurring nuclides ²³² Th, ²³⁸U and ⁴⁰K in various surface soil formations of Alhkraje city. Samples were collected from different areas of the study, sieved through a fine mesh, sealed in 0.5-liter plastic Marinelli beaker, and measured in the laboratory for 24 hours each. From the measured g-ray spectra, radioactivity concentrations were determined for ²³² Th ranging from 5.32±2.59 to 16.40±2.04 Bq ^. kg^-1, ²³⁸U (2.87±0.18 to 18.83±0.81 Bq ^. kg^-1), ⁴⁰K (211.33±55.04 to 378.97±36.46 Bq ^. kg^-1) and ¹³⁷Cs (0 to 3.19±1.02 Bq ^. kg^-1). Absorbed dose rates in air doors were calculated to be in the range of 15.29±2.65 to 30.00±3.24 nGy ^. h^-1, the corresponding effective dose rates per person outdoors were estimated to be between 21.00±0.95 to 36.83±2.11 mSν^. y^-1, assuming a 20% occupancy factor.     

National ionizing radiation secondary laboratory system

Over the past ten years, the National Institute of Standards and Technology has, through its Office of Radiation Measurement, developed a national program for Secondary Laboratories. These Secondary Laboratories provide the necessary calibrations and quality assurance testing to support and affirm the caliber of the measurements in the areas they serve. The areas that are in the program include State Radiation Protection, Personnel Dosimetry, Survey Instrument Calibration, High-Level Dosimetry, Radiation Therapy, Bioassay, Survey Instrument Testing, Ionizing Radiation, Environmental Radioactivity, Radioactivity Standards, and Radon.     

Synergism between electricity and ionizing radiation

Weak direct electric currents which produce little (or no) lethal damage to Escherichia coli bacteria are shown to act synergistically with ionizing radiation, both electromagnetic radiation (X-ray) and charged particles (beta radiation). This synergism greatly enhances the lethal effect of ionizing radiation on bacteria. This is possibly due to increased single-strand breaks in DNA, as detected by the alkaline sucrose gradient method. It is also shown that in cells with thymidine-3H incorporated into their DNA and treated with electricity, the radioactivity is released from the acid-insoluble fraction to the acid-soluble fraction, so that the ratio of radioactivity in the soluble fraction to that in the insoluble fraction increases from 0.47 in the non-treated control cells to 3.46 in the cells treated with an electric current of 1.0 mA (3.0 V) for 30 min, which indicates extensive degradation of cellular DNA. No synergism is detected between electricity and 254 nm UV radiation nor between electricity and X-rays, when these two agents are used sequentially in any order. Electricity alone produces lesions in cell membranes, as shown by electron microscopy.     

Vinyl acetate polymerization by ionizing radiation

For this work an irradiation system to be used in the polymerization of the vinyl acetate in methylethylketone and in ethyl alcohol solution using the gamma radiation as initiator was projected and built. The molecular weights of the polymers obtained by irradiation with gamma rays in methylethylketone and in ethyl alcohol solution were 33,000 and 44,000 g/mol, respectively. From the characterization by infrared spectroscopy it was possible to verify that the polymers obtained in two studied cases actually correspond to poly(vinyl acetate).     

Raman spectroelectrochemical study of polyaniline and sulfonated polyaniline in solutions of different pH

Raman spectroelectrochemical study has been done with electrochemically prepared films of polyaniline and a copolymer of polyaniline and metanilic acid using a green laser excitation (532 nm). The experimental variables included solutions of different pH between 0.5 and 9.0, and varying electrode potential between 0.0 and 0.8 V versus Ag/AgCl. Raman bands within the wavenumber limits of 500–1700 cm⁻¹ have been analysed, and their changes, proceeding with varying of electrode potential and solution pH, have been interpreted. It has been stressed that the spectral changes of polymer films proceed continuously rather than stepwise by changing the electrode potential. Considering leucoemeraldine and pernigraniline forms of polyaniline as fully reduced and oxidised structures, respectively, it could be concluded that many different redox forms can exist between these two limiting forms, rather than the only possible emeraldine form.     

Effect of cations on polyaniline morphology

Nanostructured polyanilines of different morphologies were prepared by chemical polymerization of aniline with ammonium peroxodisulfate in aqueous HCl using various inorganic and organic chlorides as additives with the aim to determine the effect of cations of the added electrolyte on the morphology, spectroscopic characteristics, and conductivity of formed polyanilines. Chlorides of basic metals: NaCl and CaCl₂ did not show any significant effect while AlCl₃ and organic electrolytes were found to influence the morphology of polyanilines. The effect of organic-electrolyte additives, which actually are ionic liquids, is explained by the organization of their molecules to micellar structures that act as soft templates for emerging polyaniline nanoparticles. The effect of AlCl₃ is ascribed to the transformation of its molecules to [AlCl₄]^? anions.     

Decontamination of pesticide packing using ionizing radiation

The Brazilian agriculture activities have consumed about 288,000 tons of pesticides per year conditioned in about 107,000,000 packing with weight of approximately 23,000 tons. The discharge of empty plastic packing of pesticides can be an environmental concern causing problems to human health, animals, and plants if done without inspection and monitoring. The objective of this work is to study the ionizing radiation effect in the main pesticides used in Brazil for plastic packing decontamination. Among the commercial pesticides, chlorpyrifos has significant importance because of its wide distribution and extensive use and persistence. The radiation-induced degradation of chlorpyrifos in liquid samples and in polyethylene pack was studied by gamma radiolysis. Packing of high-density polyethylene (HDPE) three layer coextruded, named COEX, contaminated with chlorpyrifos, were irradiated using both a multipurpose Co-60 gamma irradiator and a gamma source with 5000 Ci total activity Gamma cell type. The chemical analysis of the chlorpyrifos was made using a gas chromatography associated to the Mass Spectrometry—GCMS from Shimadzu Model QP 5000. Gamma radiation was efficient for removing chlorpyrifos from the plastic packing, in all studied cases.     

Effect of particle size of mineral fillers on polymer-matrix composite shielding materials against ionizing electromagnetic radiation

Filler particle size is an important particle that effects radiation attenuation performance of a composite shielding material but the effects of it have not been exploited so far. In this study, two mineral (hematite–ilmenite) with different particle sizes were used as fillers in a polymer-matrix composite and effects of particle size on shielding performance was investigated within a widerange of radiation energy (0–2000 keV). The thermal and structural properties of the composites were also examined. The results showed that as the filler particle size decreased the shielding performance increased. The highest shielding performance reached was 23% with particle sizes being between <7 and <74 µm.