Anthropogenic plutonium radioisotopes in the ecosystem components of Sevastopol Bay (the Black Sea)

Modern levels (2010-2020) of 239+240Pu activity concentration in Sevastopol Bay (Black Sea) surface waters, 0-5 cm layer of bottom sediments and hydrobionts were determined by multistage radiochemical technique. The 239+240Pu activity concentrations in Sevastopol Bay surface water were on relatively low level: 1.08±0.09 - 1.54±0.17 mBqnr3. The maximum value of 239+240Pu activity concentration in the bottom sediments surface layer was observed in Sevastopol Bay mouth (993±90 mBqkg1) and it decreased with distance from the bay entrance to its tail end down to the minimum value - 276±53 mBqkg1. Based on these results as well as on published data the 239+240Pu deposition density distribution in the bay boxes and their inventory in 0-5 cm layer of bottom sediments were estimated in every boxes. Total 239+240Pu inventory in the bottom sediments surface layer was estimated at 121 MBq, with the highest deposition density value determined in the mouth part of the bay. Among studied hydrobiont species the highest 239+240Pu content was determined for mollusks (for their shells) Mytilus galloprovincialis (Lamarck, 1819) while the lowest - for fish Scorpaena poreus (Linnaeus, 1758). Accumulation ability of studied ecosystem components of Sevastopol Bay against 239+240Pu was characterized by evaluating concentration factors (Cf). It was shown that the bottom sediments of the bay were the main depot for plutonium anthropogenic radionucludes (Cf (239+240Pu) = n-105). The Cf (239+240Pu) were from two to three orders of magnitude lower for the hydrobionts of the bay: n-103 for brown algae and mollusks and n-102 for green algae and fish.

Deposition velocities of some natural radionuclides from the atmosphere at Ninh Thuan and Dong Nai of Vietnam

The deposition velocities of Be-7, K-40, Th-232, U-238 and Pb-210 radionuclides from the atmosphere at Ninh Thuan and Dong Nai monitoring stations of Vietnam were investigated. The deposition velocity was calculated based on it’s specific radioactivity in aerosols and deposition density in fallout samples. The data of the deposition velocities of radionuclides from the atmosphere are needed as input data for the models to simulate atmospheric radioactive dispersion and assess the public dose around nuclear facilities. The radioactivity of Be-7, K-40, Th-232, U-238 and Pb-210 nuclides in aerosols and fallout samples were analyzed by using a low level background gamma spectrometer equipped with HPGe detector of high resolution. The results show that the deposition velocities of Be-7, K-40, Th-232, U-238 and Pb-210 nuclides from the air are in ranges of 0.04÷1.71; 1.84÷27.46; 1.46÷23.63; 0.80÷26.13 and 0.06÷1.53 (cm/s), with average values of 0.55; 13.81; 8.22; 8.12 and 0.58 (cm/s), respectively. The deposition velocities of the radionuclides in the survey areas are comparable with those found in tropical and subtropical regions and these results could be served as the database of the World radioactive transport parameters.

A Bias Gantry Profiling Boom Sprayer for Orchard Protection

An air-assisted sprayer sends liquid medicine to a canopy of orchard plants for protection. However, the inherent drift in this method lowers the pesticide utilization. To meet the gardening requirements of a short-anvil densely planted apple orchard, a profiling boom sprayer was designed, and the operation requirements and prototype operation parameters of plant protection were determined. The droplet depositions in the upper, middle, and lower layers of the targets and in the inner, middle and outer rings were analyzed in field experiments. The standard deviations of the droplet deposition coverage rates on free, slender, and high spindles at different heights were 4.43, 2.82, and 5.29, respectively, and those of the droplet deposition densities were 5.97, 4.98, and 6.15, respectively. All p-values exceeded 0.05, indicating that droplets from the outer ring were uniformly distributed at different canopy heights. The average droplet deposition density exceeded 150 grains·cm-2 in the outer and center rings of the three tree-shaped targets, and reached 100.60 grains·cm-2 in the inner ring. The droplet deposition coverage rates on the free, slender, and high spindles in the inner ring were 37.41%, 36.69%, and 35.47%, respectively, indicating that the droplet penetration ability of the profiling boom sprayer meets the requirements of plant protection. The developed profiling boom sprayer has improved the inherent serious drift problem of the air blower sprayer, and has provided inspiration for the research and development of orchard plant protection machinery.Materials and Methods: water-sensitive paper produced by Liuliu Shanxia Plant Protection Technology Co., Ltd. (China); the profiling boom sprayer; a tractor; a wind-speed measuring instrument (AS856S, Shanghai Xima Technology (Group) Co., Ltd., Shanghai, China); a temperature and humidity measuring instrument (RC-4, Jiangsu Jingchuang Electric Co., Ltd., Jiangsu, China);, double-sided tape; a box ruler; a stopwatch and a scanner. The water-sensitive paper was cut into 3 cm × 2 cm rectangular units, and its back side was pasted to the apple trees of the test target with a small amount of double-sided tape. Facing the east, south, west, and north directions, papers sprayed by the inner, middle and outer rings were pasted on the top, middle and bottom layers of the fruit tree canopy (Dong et al., 2018, Fig.5a). To avoid disturbance from spray drift, six fruit trees were selected as the test targets at intervals of their tree shapes, and 648 water-sensitive papers in total were pasted.Results: After averaging over height, the standard deviations of the droplet deposition coverage rates of the free, slender, and high spindles were 4.43, 2.82, and 5.29 respectively, and those of the droplet deposition density were 5.97, 4.98, and 6.15 respectively. All p-values exceeded 0.05. The average droplet deposition densities of the three tree-shaped targets exceeded 150 grains·cm-2 in the center and outer rings. The average droplet deposition density in the inner ring was 100.60 grains·cm-2, and the droplet deposition coverage rates of the free, slender, and high spindles were 37.41%, 36.69%, and 35.47%, respectively. Averaged over the four directions, the coverage rate in the outer ring was 41.46% higher than in the center ring, and 90.87% higher than in the inner ring. Meanwhile, the average coverage rate was 34.93% higher in the center ring than in the inner ring.Discussion: The outer ring of the profiling boom sprayer evenly distributed the droplets at different heights. The growths of the droplet deposition coverage rates were similar, and the droplet penetrations in different rings were consistent. Although the droplet penetration of the inner ring was poorer in the horizontal than center and outer ring in the vertical direction, the blades of the inner ring were sprayed sufficiently to meet both the quality assessment of plant protection operations and the design operating requirements of the profiling boom sprayer.

Electrodeposition of Bi-Te Thin Films on Silicon Wafer and Micro-Column Arrays on Microporous Glass Template

Electrodeposition is an important method for preparing bismuth telluride (Bi2Te3)-based thermoelectric (TE) thin films and micro-column arrays. When the concentrations of Bi:Te in electrolytes were 3 mM:4 mM, the TE films satisfied the Bi2Te3 stoichiometry and had no dependence on deposition potential. With increasing over-potential, crystal grains changed from lamellar structures with uniform growth directions to large clusters with staggered dendrites, causing a decrease in the deposition density. Meanwhile, the preferred (110) orientation was diminished. The TE film deposited at −35 mV had an optimum conductivity of 2003.6 S/cm and a power factor of 2015.64 μW/mK2 at room temperature due to the (110)-preferred orientation. The electrodeposition of TE micro-columns in the template was recently used to fabricate high-power micro-thermoelectric generators (micro-TEG). Here, microporous glass templates were excellent templates for micro-TEG fabrication because of their low thermal conductivity, high insulation, and easy processing. A three-step pulsed-voltage deposition method was used for the fabrication of micro-columns with large aspect ratios, high filling rates, and high density. The resistance of a single TE micro-column with a 60 μm diameter and a 200 μm height was 6.22 Ω. This work laid the foundation for micro-TEG fabrication and improved performance.

Модификация пористого углеродного материала полимерным комплексом кобальта с основанием Шиффа саленового типа для электродов электрохимических суперконденсаторов

Effect of the modification of a porous carbon material used in supercapacitors by a polymeric complex of cobalt with a Salen-type Schiff base ligand on the material capacity have been studied. Conjunction of multielectron redox processes in the polymer with the proposed effective modification technology makes it possible to increase the electrode capacity by 2.4 times in comparison with unmodified carbon electrodes. Specific capacity of the polymer poly-[Co(CH3OSaltmen)] at a polymer deposition density of 1.3 mg•cm-2 was 170 mA•h•g-1.

Prompt Mapping of Radioactively Contaminated Areas

The paper presents a methodology for prompt mapping of radioactively contaminated areas. The efficiency of obtaining cartographic information is achieved by using correlation dependences between the characteristics of radioactive contamination obtained during various radiological surveys of contaminated areas. The method of spatial interpolation based on regression-kriging is used to formalize the data on radioactive contamination. This method allows combining the information resulting from direct measurements of density of territory contamination by radionuclides we are interested in with the information contained in other characteristics of radioactive contamination received at the surveyed area (for example, ER). Such an approach allows more accurate mapping of 137Cs deposition density and concentration of its activity in the root layer of soil, as well as significant reduction of the time and cost to survey the mapped area (sampling, sample preparation and measurement of samples). This, in turn, accelerates and reduces the cost for mapping of radioactively contaminated territories (fields, lands, sites). The methodology has been tested on the fields contaminated by radionuclides resulting from the Chornobyl accident in the Narodychi, Polissia and Ivanivka Districts and has proved its performance and efficiency. Comparison and analysis of the obtained maps of radioactive contamination of the territory show that in the conditions of limited amount of data on direct measurements and time limit, the use of correlation dependences between the characteristics of radioactive contamination of soil is often the only possible way to increase the information content and accuracy of the obtained cartographic information.