Assessment of Natural Radioactivity in Rivers Sediment and Soil from the Copper Belt Artisanal Mining Region, Democratic Republic of the Congo

The concentrations and distribution of naturally occurring radionuclides (238U, 235U, 234U, 230Th, 226Ra, 210Pb, 232Th, 228Ra, and 40K) were determined by alpha and gamma spectrometry in soil and sediments collected from Luilu and Dilala rivers located in the mining district of Kolwezi (Lualaba Province) of the Democratic Republic of the Congo. The average concentrations of 238U and 226Ra in the analyzed samples were 5 - 10 times higher than the world average values for soil provided by the United Nations Scientific Committee on the Effects of Atomic Radiation. However, the average concentrations of 232Th were found similar to the world average. In both river basins, artisanal mining activities and mineral washing sites displayed the higher concentration values of radionuclides. The mean values of health risk indices calculated for those sites were found significantly higher compared to world average levels. Radiation protection measures seem needed to ensure the radiation safety of local populations. Graphical Abstract

Synthesis and Stability Studies of 225Actinium Tin Colloid Radiopharmaceutical

Synthesis of novel 225Ac-Sn particles was described for the first time. Detailed experimental and stability studies were successfully exhibited. Treatment of excess amount of SnCl2 with 0.2 mCi 225Ac furnished highly stable 225Ac tin colloid with 90% of radiochemical yield (RCY) at optimized reaction condition. R-TLC analyses indicated 95% of radiochemical purity (RCP). Stability studies showed that colloidal structure also retained free daughter radionuclides formed by the 225Ac decay chain. 225Ac tin colloids could be ideal nanocarriers for localized cell killing due to high linear energy transfer and prevention of free radioisotope daughters.

Cs_(2)TiI_(6):A potential lead-free all-inorganic perovskite material for ultrahigh-performance photovoltaic cells and alpha-particle detection

The lead contamination and long-term stability are the two important problems limiting the commercialization of organic–inorganic lead halide perovskites.In this study,through an innovative multi-scale simulation strategy based on the first-principle calculations coupling with drift-diffusion model and Monte Carlo method,a new discovery is shed on the vacancy-ordered double perovskite Cs_(2)TiI_(6),a potential nontoxic and stable perovskite material for high-performance solar cell andα-particle detection.The excellent photon absorption character and ultrahigh carrier mobility(μn=2.26×10^(4)cm^(2)/Vs,μp=7.38×10^(3)cm^(2)/Vs)of Cs_(2)TiI_(6)induce ultrahigh power conversion efficiency(PCE)for both single-junction solar cell(22.70%)and monolithic all-perovskite tandem solar cell(26.87%).Moreover,the outstanding device performance can be remained even in high energy charge particle detection(α-particle)with excellent charge collection efficiency(CCE=99.2%)and mobility-lifetime product(μτh=1×10^(–3)cm^(2)/V).Furthermore,to our surprise,the solar cell andα-particle detector based on Cs_(2)TiI_(6)material are able to withstand ultrahigh fluence proton beam up to 1013 and 1015 p/cm2 respectively,which strongly suggests that semiconductor devices based on Cs_(2)TiI_(6)material are able to apply in the astrospace.The multi-scale simulation connecting from material to device reveals that Cs_(2)TiI_(6)perovskite has the great potential for photovoltaic cells,α-particle detection and even their space application.