Search Results (241)

Radionuclide-based molecular imaging modalities are active and developing areas of functional and molecular diagnosis. Among the radionuclides used for SPECT imaging in oncology, ^99mTc is a leading candidate for radiolabeling. At present, a sufficient number of complexons for ^99mTc have been described; however, the development of effective delivery systems for this isotope to the area of interest is a complex research task. The use of tumor-targeting molecules as carriers for radioactive tracers is an effective strategy that has enabled the development of many novel radiopharmaceuticals for cancer imaging. Background: To date, a number of studies have shown tumorotropicity of tetrapyrrole compounds to tumor tissues, in particular derivatives of natural chlorophyll A. Methods: Purification was performed using solid-phase extraction. Assessment of radiochemical yield and purity was performed via radio-ITLC. The in vitro tumor cell accumulation was assessed using SKOV-3 and A-431 cell lines. Dose-dependent biodistribution was evaluated in Nu/J mice bearing epidermoid carcinoma (A-431) xenografts. Results: In this work, we obtained complexes with ^99mTc based on water-soluble carboxylate chlorin e₆ derivatives in order to evaluate their potential for use as SPECT radiopharmaceuticals. We performed radiolabelling optimization of a series of the novel chlorins and primary preclinical studies, including an assessment of the effect of their lipophilicity and charge on tumor uptake. Conclusions: Modification of the periphery of the chlorin macrocycle with chelating groups allows for complexing a wide range of metals, including ^99mTc, which can be used for targeted delivery of the radionuclide to the area of interest. Full article

Current tumor diagnostics rely on fluorodeoxyglucose (FDG)-PET imaging, but FDG’s short half-life and high cost limit its widespread use. Infrared (IR) probes are emerging as non-radioactive alternatives to conventional tracers for tissue section and other in vitro imaging applications. Because cells and tissues are relatively free of absorption peaks between 1800 and 2200 cm⁻¹, metal-carbonyl complexes, especially cyclopentadienylrhenium(I) tricarbonyl (Cp[Re(CO)₃]) derivatives, absorb strongly in this window and provide robust platforms for bioconjugation. Furthermore, Cp[Re(CO)₃] fragments can be introduced into organic substrates via an elegant three-component reaction that simultaneously forges the cyclopentadienyl-metal and cyclopentadienyl-substituent bonds. As a result, the functionalized half-sandwich complex is obtained in a single step without any special handling issues. We have therefore properly modified a glucose molecule with that complex and developed a novel glucoconjugated Cp[Re(CO)₃] probe that enables IR-based visualization of diseased cells at 2100 cm⁻¹, offering a non-invasive, non-radioactive histological tool and a promising basis for future medical imaging devices. Full article

The number of structurally investigated cyclopentadienyl (Cp⁻) complexes of technetium is limited in contrast to the situation with its heavier homolog, rhenium. Although this could be attributed to the radioactivity of all isotopes of the radioelement, there are also clear chemical differences to analogous compounds of the other group seven elements, manganese and rhenium. Technetium Cp⁻ compounds are known with the metal in the oxidation states “+1” to “+7”, with a clear dominance of Tc(I) carbonyls and nitrosyls. Corresponding carbonyl complexes also play a significant role in the development of ^99mTc-based radiopharmaceuticals with the aromatic ring as an ideal position for the attachment of biomarkers. In this paper, the present status of the synthetic and structural chemistry of technetium with Cp⁻ ligands is discussed, together with recent developments in the corresponding ^99mTc labeling chemistry. Full article

Whilst subtractive manufacturing has been de-risked significantly over recent decades, the emergence of new unfamiliar materials is proving to be a significant challenge for social sustainability. Given this rapidly evolving landscape, this review serves to outline the current available data on the occupational health implications of various existing and emerging material species, ranging from radioactive metals to composite materials. A structured search of sources up to January 2025 was conducted using databases such as Google Scholar, PubMed and Web of Science in addition to various authoritative occupational health reports, prioritising the literature directly pertaining or analogous to machining-related hazards. Evidence highlights the complexity of the machining environment, with occupational hazards ranging from toxicological factors to fire risks (i.e., due to swarf pyrophoricity). Case studies outline both relatively benign pathologies (e.g., dermatitis and sensitisation) and much more severe health complications (e.g., carcinogenicity, systemic organ damage and death), underscoring the need for continuous assessment and updating of exposure controls, even for materials traditionally regarded as safe. Full article

This study explores, for the first time, the bioaccumulation of americium-241 (²⁴¹Am) by Cupriavidus metallidurans and Ochrobactrum anthropi, two bacterial strains previously investigated mainly for their interactions with other heavy metals and radionuclides. To the best of our knowledge, no prior studies have reported the use of these microorganisms for ²⁴¹Am removal from aqueous solutions. The effects of initial ²⁴¹Am concentration and solution pH on removal performance were evaluated through batch experiments. Kinetic analyses were performed using pseudo-first-order (PFO) and pseudo-second-order (PSO) models, with the PSO model providing a better fit, suggesting chemisorption as the rate-limiting step in the process. Initial ²⁴¹Am concentrations ranged from 75 to 300 Bq mL⁻¹, and both bacterial strains demonstrated comparable maximum bioaccumulation capacities of approximately 1.5 × 10⁻⁸ mmol g⁻¹. However, O. anthropi exhibited superior resistance to ²⁴¹Am, maintaining colony growth at activity levels up to 1200 Bq mL⁻¹, compared to a threshold of 400 Bq mL⁻¹ for C. metallidurans. These findings highlight the robustness and efficiency of these bacterial strains—particularly O. anthropic—in removing ²⁴¹Am from liquid radioactive waste, offering promising implications for bioremediation technologies. Full article

A significant portion of coal mined in Kazakhstan is mainly used for fuel energy and metallurgy. Approximately 60% of electricity is generated by coal-fired power engineering. About 19 million tons of ash and slag waste (ASW) are annually sent to dumps. After coal combustion, in ASW not only are natural radioactive nuclides NRN (U²³⁸, Th²³², K⁴⁰) concentrated, but also rare and rare earth elements (REE). In this regard, ASW that essentially turns into quasi-technogenic deposits of NRN and REE, requires systemic measures for their utilization. The possibilities of extracting REE from coal power-industry waste are estimated based on the analysis of the concentration of REE (Ce, La, Nd, Sm, etc.), NRN (U²³⁸, Th²³² and their decay products, K⁴⁰) and the established significant correlations between rare earth and radioactive elements. The purpose of this paper is to study the natural radioactivity of coals and ash and slag waste as potential raw materials for assessing the quality and extracting rare earth metals. The stated purpose involves solving the following problems: studying the features of the NRN and REE distribution in coals and ash and slag waste; assessing the possibility of using ash and slag waste as a promising source of REE extraction based on nuclear radiometric studies; and studying the spectrometry of natural gamma radiation for assessing the quality of coals. Full article

In the nuclear industry, the decontamination of nuclear metallic structures is an essential process to reduce radiation exposure during maintenance or dismantling. The oxide layer, such as chromium (III) oxide (Cr₂O₃), formed on stainless steel and nickel-based alloys, contributes significantly to surface radioactivity by trapping radioactive contaminants. To address this, permanganic acid (HMnO₄) has proven to be a promising oxidizing agent for dissolving these oxide layers—particularly chromium oxide—on stainless steel and nickel-based alloys. In this study, HMnO₄ was synthesized via ion exchange using AmberLite IRN97 H resin and potassium permanganate (KMnO₄). The optimized process yielded a highly acidic solution (pH~1.6) with potassium concentrations below 0.1 ppm, indicating near-complete exchange efficiency. Dissolution kinetics were investigated at HMnO₄ concentrations ranging from 240 to 1920 ppm and temperatures from 30 °C to 80 °C. At a constant temperature, increasing HMnO₄ concentration significantly improved Cr dissolution, with up to 31% of total chromium solubilized after 33 h. Lower temperatures favored higher dissolution efficiency, likely due to improved thermal stability of HMnO₄. For durations shorter than 4 h, the influence of temperature was limited compared to the effect of acid concentration. To assess post-treatment options, HMnO₄ decomposition was studied using oxalic acid (H₂C₂O₄) at 80 °C. Results showed that a minimum H₂C₂O₄/HMnO₄ molar ratio above 2.75 was necessary to achieve effective reduction while preventing MnO₂ precipitation. However, even under strongly acidic conditions and with a large excess of reductant, Mn²⁺ yields remained below 55%, suggesting that thermal degradation of oxalic acid and possible formation of undetected manganese species limited the reduction process. Full article

Tin slags generated during cassiterite smelting in Brazil contain significant amounts of technologically important metals such as niobium, tantalum, and zirconium. Improper disposal of these materials represents both an environmental concern and the loss of a valuable secondary source of critical elements. This study aimed to characterize a Brazilian tin slag sample to evaluate its composition, morphology, and potential for metal recovery. The material was homogenized and analyzed by laser diffraction (particle size), ICP-OES (chemical composition), X-ray diffraction (mineral phases), differential scanning calorimetry (metallic tin), and scanning electron microscopy with energy-dispersive spectroscopy (morphology). The slag exhibited a heterogeneous particle size distribution (D90 = 0.75 mm, D50 = 0.30 mm, D10 = 0.09 mm) and a complex multiphase structure composed mainly of silica, calcium silicate, and zirconia. The chemical analysis revealed 4.8 wt% Nb and 0.8 wt% Ta, along with high concentrations of Zr (11.1 wt%), confirming the material’s potential as a secondary resource. Thorium (2.7 wt%) and uranium (0.3 wt%) were also detected, indicating the presence of radioactive constituents. The detailed characterization of the slag provides essential insights into its chemical and mineralogical complexity, which directly influence the selection of suitable recovery routes. Understanding the distribution of Nb- and Ta-bearing phases within the refractory silicate–zirconia matrix is fundamental for defining pretreatment and leaching strategies. Therefore, this study establishes a necessary foundation for the design of efficient hydrometallurgical processes aimed at recovering critical metals from Brazilian tin slags. Full article

The remediation of soils contaminated with heavy metals and radionuclides remains a significant environmental challenge. This study evaluated the phytoremediation potential of industrial hemp (Cannabis sativa L.) in soil collected from a historical evaporation dam, characterized by high levels of diverse metals, including Al, Cr, Fe, and radioactive elements (U, Th). Three treatments were applied: a control, a metal-spiked treatment (chelated with citric acid), and an NPK + spike treatment. A separate six-month greenhouse trial compared plants grown with and without NPK nutrients. Results demonstrated that the addition of a chelating agent significantly enhanced the bioavailability and subsequent uptake of key metals, including U, Se, and Pd. NPK fertilization combined with chelation resulted in the greatest plant biomass (≈4.5 g) and height (>18 cm), which correlated with higher total metal accumulation. Bioaccumulation factors (BAF > 1) were highest for B, Sr, Cd, and Bi, with values for Cd and U reaching 1.3 and 2.1, respectively. Foliar analysis revealed that leaves accumulated significantly higher metal concentrations than stems (e.g., Translocation Factor (TF) ~ 2.0 for Cd, Pb, and U), acting as the primary sink. This study concludes that hemp, particularly when assisted with chelating agents and adequate nutrition, is a highly effective candidate for the phytoremediation of multi-metal contaminated soils. The NPK + chelation strategy is the most promising for maximizing both biomass production and metal extraction efficiency. Full article

Groundwater quality is a key factor and a critical determinant of public health, agriculture, and socio-economic development, particularly in regions where private wells and mineral springs constitute the primary water sources. This study presents an integrated hydrochemical, radiological, and toxicological assessment of groundwater in the Sângeorz-Băi area, Romania, a spa region where mineral waters hold both therapeutic and economic significance. Samples from mineral springs, the municipal supply system, and private wells were analyzed to evaluate compliance with national and international standards and to assess their suitability for drinking, therapeutic, and agricultural purposes. The results reveal distinct hydrochemical contrasts between sources. Mineral springs are characterized by elevated salinity, hardness, and Na–HCO₃ facies, whereas the municipal network and private wells are dominated by Ca–HCO₃ facies. More than half of the private wells exceeded permissible limits for NO₃⁻, NO₂⁻, NH₄⁺, Pb, and Fe, with one well posing a significant nitrite-related health risk. Trace metal analysis indicated localized enrichment in Cu, Fe, and Pb. Radon and radium activities generally complied with regulations, although radium occasionally exceeded the more stringent WHO guidelines. Seasonal variation was minimal, reflecting stable groundwater chemistry. Health risk and irrigation assessments suggest that municipal supply water is largely safe for consumption, while private wells require targeted monitoring and mitigation. Despite elevated Na⁺ and Cl⁻, mineral springs retain therapeutic value under controlled use. This study provides a replicable framework for groundwater quality assessment in spa regions and offers critical insights for public health protection, sustainable tourism, and agricultural resilience. Full article

Among the main man-made water pollutants that pose a danger to the environment are oil products, heavy metals, and radionuclides, as well as micro- and nanoplastics. To purify such waters, it is necessary to use advanced methods, with sorption being one of them. The aim of this work is to develop a nano-functionalized composite, comprising magnetically responsive, thermally expanded graphite (TEG) and the natural clay bentonite, and to assess its ability to purify man-made contaminated waters. Throughout the course of the research, the methods of scanning electron microscopy, optical microscopy, dynamic light scattering, radiometry, and atomic absorption spectrophotometry were used. The use of the TEG–bentonite composite for the purification of the model water, simulating radioactively contaminated nuclear power plant (NPP) effluent, reduced the content of organic substances by 10–15 times, and the degree of extraction of cesium, strontium, cobalt, and manganese was between 81.4% and 98.8%. The use of the TEG–bentonite composite for the purification of real radioactively contaminated water obtained from the object “Shelter” (“Ukryttya” in Ukrainian), in the Chernobyl Exclusion Zone, Ukraine, with high activity, containing organic substances, including micro- and nanoplastics, reduced the radioactivity by three orders of magnitude. The use of cesium-selective sorbents for additional purification of the filtrate allowed for further decontamination of radioactively contaminated water with an efficiency of 99.99%. Full article

The BN-350 is the first industrial fast neutron reactor in the history of nuclear energy. It is currently undergoing decommissioning. One of the key challenges of decommissioning is managing the solid radioactive waste that has accumulated throughout the reactor’s operational life. At the moment, the accumulated solid radioactive waste is stored in a storage facility within the BN-350 reactor complex. An analysis showed that more than ~7262 tons with 5.17 × 10¹⁴ Bq activity of various types of solid radioactive waste have been accumulated over the reactor operation. They are mainly represented by materials with low activity. At the same time, the main share of activity is comprised of highly active waste with a total mass of ~170 tons and an activity of 4.73 × 10¹⁴ Bq. A solid radioactive waste management strategy has been developed. It includes all stages from collection and classification to transportation and long-term storage. Modern technologies now offer new possibilities. Some radioactive waste can be processed and reused in other economic sectors. In particular, recycling metals and alloys can reduce the volume of solid radioactive waste. It can also return valuable materials to industrial use. Full article

Radioactive wastewater generated from nuclear energy, medical, and industrial sectors poses persistent ecological and health risks, necessitating the development of safe and sustainable treatment strategies. Compared with conventional physicochemical approaches, bioremediation using radiation-resistant bacteria (RRB) provides distinct advantages, including lower energy requirements, reduced secondary pollution, and superior ecological compatibility. This review synthesizes current knowledge on RRB’s biological characteristics, molecular resistance mechanisms, and applications in radioactive wastewater treatment. Moreover, potential applications in non-radioactive wastewater treatment—such as selective removal of heavy metals, degradation of refractory organics, and mitigation of antibiotic resistance—are discussed. Evidence from existing studies indicates that RRB share fundamental adaptive traits, including extraordinary radiotolerance, unique morphological modifications, and cross-tolerance to multiple stressors, which are underpinned by specialized DNA repair systems, potent antioxidant defenses, and radiation-responsive regulatory networks. These mechanisms collectively confer the ability to withstand and mitigate radiation-induced damage. Future research should responsibly prioritize the genetic engineering of RRB and its integration with complementary technologies, such as microbial fuel cells, to achieve synergistic pollutant removal and energy recovery. This synthesis provides a theoretical basis and technical reference for advancing RRB-enabled bioremediation toward sustainable wastewater management. Full article

Some of nuclear power’s primary detractors are the unique environmental challenges and impacts of radioactive wastes generated during fuel cycle operations. Key benefits of spent fuel reprocessing (SFR) are reductions in primary high active waste (HAW) masses, volumes, and lengths of radiotoxicity at the expense of secondary waste generation and high capital and operational costs. By employing advanced waste management and resource recovery concepts in SFR beyond the existing standard PUREX process, such as minor actinide and fission product partitioning, these challenges could be mitigated, alongside further reductions in HAW volumes, masses, and duration of radiotoxicity. This work assesses various current and proposed SFR and fuel cycle options as base cases, with further options for fission product partitioning of the high heat radionuclides (HHRs), rare earths, and platinum group metals investigated. A focus on primary waste outputs and the additional energy that could be generated by the reprocessing of high-burnup PWR fuel from Gen III(+) reactors using a simple fuel cycle model is used; the effects of 5- and 10-year spent fuel cooling times before reprocessing are explored. We demonstrate that longer cooling times are preferable in all cases except where short-lived isotope recovery may be desired, and that the partitioning of high-heat fission products (Cs and Sr) could allow for the reclassification of traditional raffinates to intermediate level waste. Highly active waste volume reductions approaching 50% vs. PUREX raffinate could be achieved in single-target partitioning of the inactive and low-activity rare earth elements, and the need for geological disposal could potentially be mitigated completely if HHRs are separated and utilised. Full article

Between approximately 725 and 518 Ma, a suite of specialized felsic plutons and granitic stocks were emplaced across the Arabian Shield, many of which are now recognized as highly mineralized prospects enriched in rare earth elements (REEs), rare metals, and radioactive elements bearing mineralizations. The current investigation focused on the radiological and geochemical characterization of naturally occurring radionuclides, specifically ²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K, within three strategically selected granitic prospects, namely, J. Tawlah albite granite (TW), J. Hamra (HM), and J. Abu Al Dod alkali feldspar syenite and granites (AD). Concerning the radioactivity levels of the investigated granitic stocks, specifically the activity concentrations of ²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K, the measured average values demonstrate significant variability across the TW, HM, and AD stocks. The average ²³⁸U concentrations are 195 (SD = 38.7), 88.66 (SD = 25.6), and 214.3 (SD = 140.8) Bq/kg for TW, HM, and AD granitic stocks, respectively. Corresponding ²²⁶Ra levels are recorded at 172.4 (SD = 34.6), 75.62 (SD = 25.9), and 198.4 (SD = 139.5) Bq/kg. For ²³²Th, the concentrations are markedly elevated in TW at 5453.8 (SD = 2182.9) Bq/kg, compared to 77.16 (SD = 27.02) and 160.2 (SD = 103.8) Bq/kg in HM and AD granitic stocks, respectively. Meanwhile, ⁴⁰K levels are reported at 1670 (SD = 535.9), 2846.2 (SD = 249.9), and 3225 (SD = 222.3) Bq/kg for TW, HM, and AD granitic plutons, respectively. Notably, these values exceed the global average background levels, indicating an anomalous enrichment of the studied granitic occurrences. The mean radiological hazard indices for each granitic unit generally exceed global benchmarks, except for AEDE_out in the HM and AD stocks, which remain below international limits. The geochemical disparities observed are indicative of post-magmatic alteration processes, as substantiated by the interpretation of remote sensing datasets. In light of the significant radiological burden presented by these granitic stocks, it is essential to implement a rigorous precautionary framework for any future mining. These materials must be categorically excluded from uses that entail direct human exposure, especially in residential construction or infrastructure projects. Full article