Dosimetric evaluation of an indigenously developed 10 MeV industrial electron beam irradiator

The high dose rate electron beams are increasingly being used for radiation processing of various products worldwide. A comprehensive dosimetric evaluation of an in-house developed 10 MeV industrial electron beam irradiator was carried out in static as well as in dynamic mode of irradiations. Radiochromic B3 film and graphite calorimeter were used for dosimetric measurements. The dose rate from the electron beam was also calculated using the empirical relation prescribed in the ASTM report E2232-02. The measured electron beam profile indicates the dose rate variation within 8% in the irradiated product boxes. The most probable energy determined from the depth dose distribution in PMMA, Al and water was found in agreement with the intended energy of the electron beam. Measured dose rate using radiochromic film and graphite calorimeter were found in good agreement with each other and also found comparable with the theoretically estimated dose rates. Experimentally measured dose rates were considered for the trial irradiation of medical and industrial products. Dosimetric data obtained through this study confirms the suitability of the irradiator for routine radiation processing of various products.     

Microextraction-Colorimetric Determination of Quaternary Ammonium Compounds in Medicines and Disinfectants

Moscow University Chemistry Bulletin - We propose a method for the determination of quaternary ammonium compounds (QACs) in medicines and disinfectants, based on dispersive liquid–liquid...     

Modification of epoxy-amine compositions on the basis of water-soluble resin

Water-soluble epoxy-amine compositions have been synthesized. The possibility of modification of water-soluble hydantoin-containing epoxy resin marketed under the brand name SEG-6 with such products as medium-molecular-weight epoxy resin under the brand name Epofom-1s and high-molecular-weight polymers, namely, petropolymeric resin under the brand name Quintone C200S and CSPE-MK chlorosulfonated polyethylene, is studied. It is shown that the compositions produced as a result of such modification are water-soluble and exhibit a long lifetime, and the materials obtained on their basis are characterized by high elastic-deformation and adhesive properties in comparison with polymers on the basis of SEG-6 resin.     

Possibility of saving silver in deposition of a multilayer copper-nickel-silver coating

Possibility of making thinner silver coatings on low-current sliding contacts in deposition of multilayer nickel-silver and copper-nickel-silver coatings from various electrolytes was studied.     

Factors affecting the registration and counting of alpha tracks in solid state nuclear track detectors

In view of the fact that the radon progeny contribute the highest to the natural radiation dose to general populations, large scale and long-term measurements of radon and its progeny in the houses have been receiving considerable attention. Solid State Nuclear Track Detector (SSNTD) based systems, being the best suited for large scale passive monitoring, have been widely used for the radon gas (using a cup closed with a semi-permeable membrane) and to a limited extent, for the measurement of radon progeny (using bare mode in conjunction with the cup). These have been employed for radon mapping and indoor radon epidemiological studies with good results. In this technique, alpha tracks recorded on SSNTD films are converted to radon/thoron concentrations using corresponding conversion factors obtained from calibration experiments carried out in controlled environments. The detector response to alpha particles depends mainly on the registration efficiency of the alpha tracks on the detector films and the subsequent counting efficiency. While the former depends on the exposure design, the latter depends on the protocols followed for developing and counting of the tracks. The paper discusses on parameters like etchant temperature, stirring of the etchant and duration of etching and their influence on the etching rates on LR-115 films. Concept of break down thickness of the SSNTD film in spark counting technique is discussed with experimental results. Error estimates on measurement results as a function of background tracks of the films are also discussed in the paper.      

Green's function method for aerosol penetration in channels under laminar flow conditions

A generalized method based on Green's function technique is developed to calculate the penetration fraction of particles by diffusion, formed from a given source in a gas under laminar flow, in cylindrical and rectangular channels. Both the initial value and the formation-in-flight types of problems are brought together in one formal procedure. The task of having to solve the convective-diffusion equation, for a given distribution of source density in the case of formation-in-flight problems, is altogether eliminated. The effect of a first-order reaction, like radioactive decay, is taken into account. Linear approximation for the shift in the eigenvalues due to the reaction term is given for small values of the dimensionless reaction rate constant. Finally, the solution available for an exponentially decreasing source in a cylindrical channel is found to be incorrect and the correct expression is derived using this method.