The requirement to distinguish between depleted metallic uranium (DU) and natural metallic uranium (NU) is essential in nuclear forensics, regulatory enforcement, nuclear fuel fabrication and environmental monitoring. Traditional laboratory-based methods offer high accuracy but are impractical for on-site measurement. This research develops a portable gamma spectrometry-based methodology for identifying DU and NU in real-time, non-destructively. The study utilizes a NaI(Tl) based gamma spectrometer to measure characteristic emissions from uranium isotopes and its daughter products. Key gamma peaks, particularly those at 92 keV (234Th) and 186 keV (235U), were analysed to derive isotopic ratios indicative of the material type. Emphasis was given on choosing right gamma peak and adjustment for x-ray contribution in 92 keV peak. Estimated activity ratio of 235U to 234Th of five natural uranium samples was greater than or equal to 0.046 and the activity ratio of five depleted uranium sample found to be less than 0.046, which validated the methodology. The results demonstrate that, with proper calibration, and spectral analysis, portable gamma spectrometry can serve as an effective tool for real-time uranium isotope identification in applications ranging from nuclear safeguards and non-proliferation to environmental monitoring and emergency response.

Acid mine drainage (AMD) affects the mobility of naturally occurring radioactive materials (NORM), but its influence on the distribution of U- and Th-series radionuclides in polymetallic mining districts and downstream estuaries remains poorly understood. Here, we characterize the spatial evolution and isotopic signatures of U- and Th-series radionuclides in the dissolved fraction along the Oraque-Meca-Odiel river-estuary system (SW Spain). This system shows a strong geochemical gradient, from highly acidic AMD headwaters (locally pH < 3; high sulfate and metal concentrations) through weakly acidic reaches (pH ≈ 4.5) to near-neutral estuarine waters (pH ≈ 7). 238U and 232Th activity concentrations were strongly enriched in AMD-impacted headwaters, reaching values in the order of 103 and 102 mBq L-1, respectively, with 238U exceeding global riverine background by more than two orders of magnitude. PHREEQC modeling indicated that modeled aqueous U(VI) was dominated by free uranyl and uranyl-sulfate species under strongly acidic conditions. In contrast, dissolved 232Th decreased more strongly than U as pH increased, producing a clear UTh geochemical decoupling. This pattern is consistent with the generally higher particle reactivity of Th reported in previous studies and suggests transfer from the dissolved phase during downstream evolution. 234U/238U ratios were generally >1, indicating isotopic disequilibrium and preferential 234U mobilization. The 230Th/232Th activity ratios remained close to unity, indicating limited isotopic fractionation within the dissolved Th pool. These results show that the spatial variations of dissolved U and Th across the investigated river-estuary system coincided with hydrochemical gradients and changing source contributions, while the selected confluences showed nominal element-specific departures from the adopted sulfate-based mixing predictions.

[236]U is one of the rarest isotopes of uranium, occurring in ores with an abundance below 1×10[-9]. Due to a wide variety of geological factors, the [236]U content in a given uranium ore body is considered to be a unique "fingerprint" like signature, with applications in nuclear forensics and geophysics. Its low abundance though is only detectable via Accelerator Mass Spectrometry (AMS), capable of measuring [236]U/[238]U ratios below 1×10[-11]. Improvements to the AMS setup at the University of Notre Dame's Nuclear Science Laboratory, have greatly improved its detection limit, enabling measurements across the entire [236]U/[238]U ratio range found in natural ores. A description of the improvements is presented. A survey of the [236]U/[238]U ratio of various ores from North American and African mines was conducted with the improved setup, using in house reference standards to quantify the measurements. A new detection limit of 1×10[-12] was established.

Uranium dioxide (UO2) particles pose an inhalation hazard in occupational and environmental exposure scenarios, yet their cellular interactions and toxicological behavior remain poorly defined. This study investigated the dissolution behavior and colloid-forming potential of UO2 in cell culture media, and compared the cytotoxicity, inflammatory response, and intracellular fate with those from equivalent aqueous uranium (U(aq)) exposures in murine RAW264.7 macrophages and Mlg2908 lung fibroblasts in vitro. In cell culture media, UO2 exhibited low solubility and limited colloid formation (∼5% colloidal), whereas U(aq) showed a higher proportion of colloid species (∼21%). In cellular exposure studies, particulate UO2 was generally more toxic than U(aq) across all concentrations (12-120 μg/mL; 50-500 μM) and exposure durations (6-48 h). A significant inflammatory response was observed only in macrophages exposed to 60 μg/mL of UO2. Uranium was predominantly recovered in the intracellular fraction of cells exposed to UO2 (68-79% of added U), whereas U(aq) exposures remained largely extracellular (∼1% intracellular fraction of added U). TEM showed that UO2 particles were localized within membrane-bound vesicular structures. HR-TEM and elemental analyses showed that internalized UO2 particles largely retained their chemical integrity after 24 h. Overall, these findings demonstrate that particulate UO2 is more toxic than U(aq), and its toxicity in vitro reflects cell-type-specific responses and particle stability following internalization, underscoring the importance of U speciation and physico-chemical form in inhalation health risk assessment.

Rapid determination of U(VI) in uranium mining wastewater is essential for environmental risk assessment and wastewater treatment control. Herein, we developed a compact 3D-printed optofluidic platform that translates uranium colorimetric chemistry into an automated and portable flow detection system. The platform integrates programmable flow injection, a serpentine mixer, a customized optofluidic detection module, fixed optical coupling, and spectral acquisition to enable reproducible mixing and stable optical signal collection. Key optical, fluidic, and reaction parameters were systematically optimized to improve signal stability and quantitative reliability. Under optimized conditions, the platform showed a linear response of 0.05 - 1.00 mg L[-1], with a limit of detection of 0.013 mg L[-1], precision better than 5%, and stable performance during repeated measurements. The platform was further validated using uranium mining wastewater, yielding results consistent with ICP-OES and recoveries of 97.7-105.9%. This work provides a practical route for automated field monitoring of uranium containing wastewater and bridges the gap between laboratory colorimetric assays and deployable analytical hardware.

Radon ([222]Rn), Thoron ([220]Rn) and their progeny activity concentration is measured to estimate the inhalation dose. These measurements are important in indoor as well as in the occupational environments like Uranium mines and Thorium processing industries. Inhalation dose is estimated from the measured activity concentration of Radon, Radon progeny (EECR: Equilibrium equivalent Radon concentration), Thoron concentration, Thoron progeny concentration (EECT: Equilibrium equivalent Thoron concentration). For quick assessment of high Radon/Thoron activity areas, especially for mitigation purpose, active methods are generally used, but for inhalation dose assessment time integrated measurements using passive SSNTDs (Solid state nuclear track detectors) is the most reliable technique. Passive detectors have their extensive suitability for long-term and large-scale monitoring. LR-115 and CR-39 are the most extensively used SSNTDs in the field of radon and neutron dosimetry. In the present work, comparison between LR-115 and CR-39 based Radon, Thoron and Progeny dosimeters is carried out and the experimental results were compared with theoretical calculations.

Experimental reactor needed much more uranium and heavy water than the country could muster.

Current biomarkers of uranium (U) exposure do not distinguish among exposure sources or provide information on uranium accumulation within target organs. This review evaluates two complementary uranium isotope systems developed in geosciences and examines their potential as biomarkers of uranium exposure and biological processing.

Understanding how the uranyl ion (UO2[2+]) exploits native metal-binding sites in human proteins is essential for elucidating uranium transport, accumulation, and toxicity. In this computational study, we investigated how uranyl is accommodated within the protein pockets of human serum transferrin and human serum albumin, and compared these interactions with those in an engineered super uranyl-binding protein (SUP). QM/MM geometry optimizations and harmonic vibrational frequency calculations were performed starting from available X-ray crystal structures. The intrinsic strengths of individual uranyl-protein interactions were quantified using Local Vibrational Mode Analysis (LMA), complementary with Quantum Theory of Atoms in Molecules (QTAIM) and Natural Bond Orbital (NBO) analyses. Histidine residues form the strongest individual U-N interactions, whereas aspartate and glutamate provided equally strong or stronger capture through bidentate U-O coordination. In human serum transferrin, the native carbonate cofactor forms an important component of the uranyl coordination sphere, whereas hydrogen bonds involving the uranyl oxo atoms contributed only weakly to binding. Comparison with the high-affinity SUP revealed that human serum proteins bind uranyl nearly as strongly as the engineered protein, highlighting their potential role in uranium transport and fate following human exposure.

Groundwater uranium (U) prevalence in Punjab potentially threatens human health, with increasing incidence of kidney ailments, and other issues. Different aspects of U contamination have been thoroughly investigated in the region; however, a simple and cost-effective approach for the early detection of U at the local scale is lacking. Consequently, we aim to develop reliable and efficient predictive equations using commonly measured water quality parameters. The Generalized Additive Model (GAM) and Logistic Regression (LR) were adopted to model continuous U levels and categorical U class (for U30: Class 1 (U > 30 µg/L) and Class 0 (U ≤ 30 µg/L), and similarly for U60: Class 1 (U > 60 µg/L) and Class 0 (U ≤ 60 µg/L)), respectively. The adjusted R[2] and deviance explained for multivariate GAM are 0.73 and 75.7%, respectively, with TDS-HCO3¯, TDS-Na[+], and HCO3¯-Na[+] as significant interacting pairs. Groundwater U increased with the increase of HCO3¯ and Na[+] above 400-600 mg/L and TDS at 1000-1500 mg/L. This shows that greater ionic strength, excess desorption from mineral surfaces, and uranyl-carbonate complexation facilitated U enrichment in the region. The stepwise LR performed exceptionally for both U30 and U60, achieving accuracies of 94% and 96%, respectively. The resulting predictive equations are P U 30 = 1 / 1 + e - [ - 32.10 + 6.72 (l o g 10 _ T D S) + 1.20 (l o g 10 _ N a) + 1.57 (l o g 10 _ K) + 1.19 (l o g 10 _ M g) + 1.05 (p H) ] and P U 60 = 1 / 1 + e - [ - 39.42 + 7.32 (l o g 10 _ T D S) + 1.40 (l o g 10 _ N a) + 1.27 (l o g 10 _ N O 3) + 1.99 (p H) ] . The equations were cross-validated using an independent dataset, achieving more than 80% accuracy, indicating their reliability. Thus, it can serve as an efficient tool for determining groundwater U contamination at unmonitored locations in Punjab, thus aiding in groundwater management and attaining SDG 6.

Nitride-based materials present exceptional thermal and structural properties for advanced material applications, however accurate determination of their thermodynamic properties is critical to their deployment. Herein, the standard enthalpies of formation, ΔHf[°], for all LnN compounds (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu; excluding Pm) are determined via high temperature oxide melt calorimetry. These measurements are supported by high temperature oxidation studies of La, Ce, Sm, Eu, Er, Yb bearing LnN compounds using X-ray diffraction and thermogravimetric analysis, and are cross-examined against recent high temperature measurements on other LnN compounds[1]. It was determined that ΔHf[°] systematically correlates with the ionic radius of Ln[3+] cations, with smaller Ln bearing nitrides having more negative values. A discontinuity in ΔHf[°] was further observed between larger and smaller Ln bearing LnN compounds. Using the determined ΔHf[°] values with literature references, Gibbs energies of formation (ΔGf[°]), oxidation (ΔGox[°]) and hydrolysis (ΔGhyd[°]) are calculated and compared against uranium nitride (UN) in the context of UN based nuclear fuel and related spent nuclear fuel (SNF) management. The calculations indicate that the occurrence of LnN phases within UN based SNF should lead to stabilisation of the structure and inhibit its oxidation.

Covalent organic frameworks (COFs) are atomically precise, crystalline platforms for efficient solar-to-chemical energy conversion. However, their net efficiency is fundamentally limited by severe kinetic competition, in which ultra-fast exciton recombination outpaces the slower multi-electron kinetics required for surface photocatalytic reactions. This review provides a comprehensive analysis of fundamental exciton dynamics in COF photocatalysts, tracing the photophysical cascade from initial photon absorption and bound electron-hole pair generation to long-range carrier migration and interfacial transfer. We have systematically discussed the significant role of various advanced time-resolved and operational spectroscopic techniques, which serve as vital toolkits for quantifying excited-state lifetimes and mapping charge-translocation pathways. Building upon these insights, we critique state-of-the-art structural modulation strategies, highlighting different parameters such as linkage engineering, donor-acceptor architectures, polarization effects, and internal dielectric environment tuning that manipulate carrier behaviour to force efficient charge separation. Finally, we explore how matching bulk photophysics with customized interfacial active sites drives diverse, highly demanding photocatalytic applications, including hydrogen evolution, CO2 reduction, organocatalysis, H2O2 generation, nitrate reduction, and uranium extraction. Ultimately, this review underscores that maximizing quantum efficiency requires a deliberate, multi-scale synergy that balances bulk solid-state photophysics with the reaction-specific kinetics of the catalyst-substrate interface.

Seawater uranium extraction is a promising sustainable energy pathway; however, practical application requires advanced adsorbents that combine reversible, high uranium-uptake capacity with the ability to track sorption cycles. Herein, we report self-indicating porous organic polymers (POPs), Sal-POP and Im-POP, containing uranyl (UO2 [2+]) ion-coordinating salphen and o-hydroxy imine cores with UO2 [2+] binding energies up to -71.94 kcal mol[-1] as uranium adsorbents, and demonstrate their reversible, high uranium extraction capacities up to 0.114 g g[-1] h[-1]. Enabled by the extended conjugation of salphen unit and strong UO2 [2+] binding, Sal-POP readily changes color at uranium saturation from yellow to black and allows visual tracking of uranium adsorption/desorption cycles. With a high density of UO2 [2+] binding sites, both Sal-POP and Im-POP demonstrate rapid, reversible, and high uranium uptake capacity, with distribution coefficients (K d) of 1.88 × 10[5] and 2.94 × 10[5] mL g[-1], and removal efficiencies up to 70% and 78%. The uranyl capture is highly reversible, and the POP color changes from black to yellow upon simple elution with Na2CO3, thus acting as a self-indicating POP adsorbent.

Radon-222 is odorless and colorless and is highly soluble in water. Radon-222 cannot be detected by other means except measurements. When taken internally or inhaled through volatilization of water, it may lead to internal irradiation which targets the lungs and gastro-intestinal tract. The current study seeks to find out the radon-222 concentrations in 50 water samples collected from Lagos State University campus, Nigeria in November 14, 2024, using passive LR-115 Type II solid state nuclear track detectors. The results indicated concentrations in the range 3.7 ± 0.3 to 40.7 ± 8.3 Bq/L with an average concentration of 18.4 ± 3.5 Bq/L exceeding the NESREA recommended level of 11.1 Bq/L by 74%. Although the surface geology of the Ojo area is dominated by sedimentary formations of the Dahomey Basin, elevated radon concentrations can still occur due to upward migration of radon from deeper uranium-bearing basement rocks through fractures and faults, as well as from radium adsorbed on clay minerals and organic matter within the sedimentary sequence. The concentrations are up to 3.7 times the standard value. The average annual effective dose is 0.07 mSv/y for adults, 0.03 mSv/y for children and 0.02 mSv/y for infants, below WHO's 0.1 mSv/y standard value. The average lifetime excess cancer risk is 0.193 × 10[-3], which exceeds USEPA's risk limit of 10[-4] in 94% of the samples, signifying high risk of cancer. The risk categorization indicates 26% low risk (≤11.1 Bq/L), 50% medium risk (11.1-22.2 Bq/L) and 24% high-concentration sources (>22.2 Bq/L). It is below WHO's standard value of 100 Bq/L but exceeds the standard in some cases and thus has real health implication on consumers of untreated water in the university campus.