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In the process of growth and development, plants not only absorb essential nutritional elements, but also absorb radioactive and non-essential elements from the environment, and their distribution varies in different parts of the plant. In this study, neutron activation analysis and gamma spectrometry were performed on stems, roots, and leaves of vegetables. The results indicate that the accumulation of radionuclides and multi-elements depends on the plant type and plant parts. Activity concentrations of 226Ra and 232Th in plants were accumulated in the following order: Roots > Stems > Leaves. The highest concentrations of 40K and 210Pb were observed in the stems and leaves of plants, respectively. Essential nutrient requirements of plants are in the following order: K > Ca > Mg > Fe > Zn > Mn. Among the non-essential metals, the concentration of Na in the vegetable sample was much greater than those of the other elements. The K/Na ratio in the plant depends on the type of plant and the translocation within the plant.

The subnano free-volume hole features of Nafion-212 and polystyrene sulfonic acid) grafted poly(ethylene-co-tetrafluoroethylene) polymer electrolyte membranes are investigated by using the positron annihilation lifetime spectroscopic analyses with three- and four-component models (i.e., one- and two-ortho-positronium [o-Ps] components). The four-component model provides a more adequate description of free-volume hole features for both membranes, in which the longer o-Ps lifetime is assigned to the larger free volume hole sizes in the mobile side chains, while the shorter o-Ps lifetime is associated with the smaller free volume hole sizes within the backbones (the rigid amorphous fractions and the crystalline-amorphous interfaces) and the interfaces between the main chains and the side chains. The o-Ps annihilation is found to occur primarily in the side chains. The subnano volume hole features revealed by the positron annihilation lifetime (PAL) spectra suggest the primary water uptake and conductance in the side chains and the possible presence of water molecules in the rigid amorphous fractions and the interfaces. Note that the three-component model as usually reported in the literature may underestimate the lifetime and intensity of ortho-positronium annihilation. KEYWORDS free volume hole, fuel cell, ortho-positronium, polymer electrolyte membrane, positron annihilation lifetime spectroscopy, 1 | INTRODUCTION Polymer electrolyte membrane fuel cell (PEMFC) is an electrochemical device that shows several advantages, such as high-performance energy generation capacity, no air pollutant emission, low operating temperature, [...]

Abstract Chemical degradation in the presence of [H.sub.2][O.sub.2] aqueous solution and water states of polystyrene sulfonic acid) (PSSA) grafted poly(ethylene-co-tetrafluoroethylene) polymer electrolyte membranes (ETFE-PEMs) with grafting degree (GD) of 8.8%-21.1% [...]

Identification of clay minerals and depositional environment in soil at Ben Tre Province—South Vietnam was studied in this work by using laboratory HPGe gamma spectrometry through the evaluation of 232Th, 238U, 226Ra and 40K natural radionuclide distributions in soil versus depths. The calculated values of activity concentration ranged from 2.13 ± 0.13 to 6.64 ± 0.40 ppm for 238U, from 1.97 ± 0.12 to 4.95 ± 0.30 ppm for 226Ra, from 8.87 ± 0.53 to 21.30 ± 1.27 ppm for 232Th and from 0.85 ± 0.05 to 2.01 ± 0.12% for 40K. The results showed that clay minerals at the investigated site can be divided into two major groups: montmorillonite (the Th/K ratio from 6.61 to 10.47) and kaolinite (from 12.37 to 19.79) which are in accordant with the previous studies at the investigated area. [ABSTRACT FROM AUTHOR]

In this work, an approach for determining both the outer dead layer thickness of the p-type coaxial HPGe detector and the inner dead layer thickness of the n-type coaxial HPGe detector was proposed by using two full energy peak area count ratios of a X-ray and a gamma ray emitted from the same radioisotope of Cs. Monte Carlo calculations and experimental measurements were conducted to determine these dead layer thicknesses. The results showed that the outer dead layer thickness reached 0.57 ± 0.03 mm on 06 Jan 2017 after nearly 3 years of use for the p-type detector. The inner dead layer thickness reached 1.21 ± 0.24 mm on 01 Aug 2016 after more than 3 years of operation for the n-type detector. Simulation model with the modified dead layer thicknesses was used to estimate full energy peak efficiencies and gamma spectra from seven radioactive sources. The results were in good agreement with the corresponding experimental values in the gamma energy region of interest. [ABSTRACT FROM AUTHOR]

In the present study, natural radioactivity and radon exhalation rates of 55 stony material samples divided into three groups (Gneiss, Granite and Marble) were estimated by means of laboratory tests. The activity concentration range was found: 5.5 ± 1.3–125.5 ± 6.5 Bq.kg−1 for 226Ra, 4.4 ± 0.6–157.4 ± 8.4 Bq.kg−1 for 232Th and 35.0 ± 0.4–1093 ± 15 Bq.kg−1 for 40K. The data were used to evaluate radiation hazard parameters. The radon exhalation rate ranged from 0.17 ± 0.01 to 2.56 ± 0.20 Bq.m−2.h−1. Granite building materials show the highest radon exhalation rates while the marble group shows the lowest exhalation rates. Positive correlation coefficients of radon exhalation rate with radium concentration and porosity of the samples have been observed. This study also presents radon diffusion coefficient values determined for 50 waterproofing materials. A radon-proof ability comparison of waterproofing materials and a conclusion about material groups which can be considered very effective radon barriers were discussed. [ABSTRACT FROM AUTHOR]

Abstract: The essential issue in analyzing the activity of 238U in an HPGe detector based gamma spectrometer via 63.3keV line is relating to the strong self-absorption of this weak gamma ray in sample material. The present work suggests a method of the self-absorption corrections for 63.3keV gamma rays by a combination of experimental measurements and Monte Carlo MCNP5 calculations. The effects of sample chemical composition, density and geometry were calculated in terms of self-attenuation factors. The method, developed for a cylindrical sample geometry, accounted for variable sample heights and densities. The analysis of 238U activity was applied for three main soil types in Vietnam, which are grey, alluvial and red soils. The results obtained with the above outlined method were in good agreement with those derived by other methods. [Copyright &y& Elsevier]