Search Results (1,174)

The Hwange Mining Area, located in the Mid-Zambezi Karoo Basin in northwestern Zimbabwe, is a major centre for coal mining, processing, and thermal power generation. This study evaluates the ecological and public health risks associated with these activities by characterising radionuclide (²²⁶Ra, ²³²Th, ⁴⁰K) activity concentrations in coal and surrounding soils using Hyper-Pure Germanium (HPGe) gamma spectrometry. Samples were collected from four locations, as follows: Hwange Colliery Company (underground and open-cast mines), Zambezi Gas open-cast operations, residential areas, and the Zimbabwe Power Company (ZPC) thermal power station. Radionuclide concentrations were measured using Hyper-Pure Germanium (HPGe) gamma spectrometry. Mean activity concentrations in coal were low at both mining sites (Hwange Colliery: ²²⁶Ra 16 ± 5.3 Bq/kg), ²³²Th 14 ± 5.7 Bq/kg), (⁴⁰K 51 ± 8.8 Bq/kg) and Zambezi Gas (²²⁶Ra 9.80 ± 2.3 Bq/kg), ²³²Th (11 ± 3.3 Bq/kg), ⁴⁰K (43 ± 26 Bq/kg), well below UNSCEAR world coal averages. In contrast, soils from residential areas): ²²⁶Ra (36 ± 15 Bq/kg), ²³²Th (36 ± 12 Bq/kg) and ⁴⁰K (220 ± 80 Bq/kg), and the ZPC power station (²²⁶Ra 47 ± 8.6 Bq/kg, ²³²Th (42 ± 10 Bq/kg), and ⁴⁰K 230 ± 92 Bq/kg, showed markedly elevated concentrations, consistent with the accumulation of coal-combustion by-products such as fly ash. Radiological hazard indices remained within internationally accepted limits at all sites, as follows: radium equivalent (Raeq) ranged from 29 ± 6.7 Bq/kg (Zambezi Gas) to 120 ± 18 Bq/kg (ZPC), well below the 370 Bq/kg safety ceiling, while external and internal hazard indices (H_ex, H_in) remained below unity throughout, peaking at 0.32 and 0.46, respectively, at ZPC. Annual effective dose equivalents (AEDE) ranged from 16 ± 3.8 to 69 ± 10 μSv/year, the latter (ZPC) representing approximately 7% of the ICRP public dose limit of 1 mSv/year. Excess lifetime cancer risk (ELCR) values ranged from 5.56 × 10⁻⁵ (Zambezi Gas) to 2.42 × 10⁻⁴ (ZPC), remaining below the global average outdoor reference of 0.29 × 10⁻³ but reaching approximately 83% of this reference at ZPC and 71% in residential areas. These findings indicate that, while coal mining activities in Hwange contribute minimally to environmental radioactivity, coal combustion at the ZPC thermal power station is the dominant driver of elevated radionuclide concentrations and radiological indices in the surrounding environment, with residential soils reflecting the same enrichment pathway. Although no immediate radiological hazard was identified at any location, the comparatively higher indices at ZPC and in nearby residential areas underscore the need for continuous environmental monitoring, strengthened regulatory control, and targeted radiation protection strategies to safeguard workers and nearby communities. Full article

The incorporation of recycled concrete fines (F), limestone (L), and ground granulated blast-furnace slag (S) as Portland cement constituents in accordance with EN 197-6 requires the determination of naturally occurring radionuclides to ensure radiological safety from a radiation protection standpoint. This study carried out a radiological assessment of eight cement types with varying proportions of L, F, and S additions, including anhydrous cements and mortars cured for 2 and 28 days. The activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K were determined by gamma-ray spectrometry using HPGe detectors and radiochemical separation. In addition, the ²²²Rn emanation fractions were measured by the accumulation method using an AlphaGuard detector. Finally, annual effective doses were calculated using the RESRAD-BUILD software for a standard dwelling of 35 m² occupied by an adult and an infant. Among the individual materials, S exhibited the highest activity in the uranium decay series (113 ± 24 Bq kg⁻¹ of ²³⁸U), while L and F showed comparably lower values. Cements containing S additions (CEM II/C-M, CEM VI (S-L), and CEM VI (S-F)) were higher than the reference average value for building materials of 50 Bq kg⁻¹, although all mortars remained below this value. Principal component analysis revealed significant correlations between S content, SiO₂, Al₂O₃, and ²³²Th. The maximum annual effective dose reached 0.32 mSv for infants (CEM VI (S-L)), with the dose due to ²²²Rn inhalation being predominant. All cements studied are radiologically safe, confirming their suitability for use within the objectives of the circular economy. Full article

Poly(vinylpyrrolidone) hydrogels net(PVP) were synthesized by gamma radiation at a dose rate of 11.8 kGy h⁻¹ and subsequently functionalized with maleic acid (MA) via radiation-induced grafting using the direct method to obtain pH-responsive hydrogels for the loading and controlled release of bioactive compounds. Under the selected conditions, MA grafting reached approximately 18%. The obtained hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR-ATR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and swelling studies. The results confirmed the successful incorporation of MA into the hydrogel network and demonstrated that grafting imparted pH-responsive behavior due to the ionization of carboxylic acid groups, yielding two critical pH values at 4.4 and 6.0. Loading and release studies using naringin and benzalkonium chloride showed that the grafted hydrogels exhibited enhanced loading capacity and sustained release profiles governed by the hydrogel network and by interactions between the loaded compounds and the carboxylic groups from MA. Furthermore, hydrogels loaded with antimicrobial agents effectively inhibited the growth of Escherichia coli and Staphylococcus aureus. These findings demonstrate that gamma radiation-induced MA grafting is an effective strategy for developing pH-responsive PVP hydrogels with potential applications as multifunctional wound dressing materials. Full article

Calibrating the mutagenic dose is the first practical step of any radiation mutation-breeding programme, and it is usually summarised by the median lethal dose (LD50) or the median growth-reduction dose (GR50). We asked whether an accessible, image-based phenotyping pipeline can quantify the early radiation response of cowpea (Vigna unguiculata L. Walp.) seedlings finely enough to estimate GR50 and to rank organ- and pigment-level sensitivities. Seeds of the traditional Paraguayan landrace kumandá pyta’i were exposed to Cobalt-60 gamma rays at 0, 100, 200, 300, 400, 500, 600, and 700 Gy, grown in a greenhouse, and photographed at the early seedling stage. A single calibrated photograph (5.1 px mm⁻¹) of 83 seedlings was segmented in Fiji/ImageJ 1.54p and analysed with Python to extract morphometric traits (total, root, and shoot length, root:shoot ratio, tortuosity, and a two-dimensional biomass proxy) and colorimetric traits (CIE L*a*b*, a normalised greenness index, and colour-class pixel fractions). Because the data departed from normality, dose effects were tested with Kruskal–Wallis, Spearman rank correlation, and Dunn post hoc tests, and GR50 was estimated by regression of each trait expressed as a percentage of the control. Total length, shoot length, and the biomass proxy declined significantly with dose (Spearman ρ = −0.40, −0.51, and −0.47; all p < 0.001), preceded by a low-dose stimulation at 100 Gy. Estimated GR50 values were ≈390 Gy for shoot length, ≈510 Gy for total length, and ≈550 Gy for the biomass proxy, within the range reported for other cowpea genotypes. Shoot elongation was more radiosensitive than root elongation, so the root:shoot ratio did not decline; tortuosity showed no dose response. Among pigment traits, the loss of greenness was the most robust signal (a* increased, ρ = +0.62, p = 5 × 10⁻¹⁰; green pixel fraction fell from 0.32 to near zero by 500 Gy). These results show that single-photograph phenotyping resolves a coherent, statistically supported dose response and yields a GR50 estimate usable for dose calibration. For kumandá pyta’i, doses of roughly 300–400 Gy (below GR50) are the most defensible starting window for mutation induction. The framework is reproducible and low-cost, but it is based on one greenhouse experiment and a single genotype, and should be validated across independent trials and cultivars. Full article

Primordial black holes (PBHs) in the asteroid-mass range, with typical masses ${10}^{17}\mathrm{g}\lesssim M\lesssim {10}^{23}\mathrm{g}$, have drawn significant recent attention as viable dark matter candidates. The peak frequencies of photons emitted via Hawking radiation from asteroid-mass PBHs range from infrared to $\gamma$-ray bands. We calculate expected local transit rates for extended PBH mass distributions that could comprise all dark matter. We evaluate prospects for detecting Hawking-radiated photons from local PBH transits through the inner Solar System and from PBH explosions in the far outer edges of the Solar System. We consider several existing and proposed ground-based and space-based instruments sensitive to photons from the radio band to ultrahigh-energy $\gamma$-rays. We find that the proposed instruments, such as the All-sky Medium Energy Gamma-ray Observatory eXplorer (AMEGO-X) satellite, can reliably detect PBH transits within $\mathcal{O}\left(0.1\mathrm{AU}\right)$ of the Earth, while the High Altitude Water Cherenkov (HAWC) observatory and Large High Altitude Air Shower Observatory (LHAASO) are both sensitive to PBH explosions out to $\mathcal{O}\left(0.1\mathrm{pc}\right)$ and $\mathcal{O}\left(0.5\mathrm{pc}\right)$, respectively. We conclude by specifically considering potential companion electromagnetic signatures in the case of a PBH explosion about ${10}^3\mathrm{AU}$ from Earth, which has been suggested as a potential source for the ∼220 PeV ultrahigh-energy KM3-230213A neutrino event observed by the KM3NeT collaboration in 2023. Whereas we find that the recent KM3NeT event would not have yielded detectable electromagnetic signals—due to its location on the sky, proposed distance from Earth, and the offline status of the HAWC observatory at that time—we demonstrate that future PBH explosions at comparable distances could yield electromagnetic signals measurable from Earth, depending on the alignment of the PBH burst with detector fields of view. Full article

Lead-free polymer nanocomposites have attracted considerable attention as sustainable alternatives for ionizing radiation shielding. In this study, unsaturated polyester resin (UPR) nanocomposites containing hydrothermally synthesized Bi₂WO₆ nanoparticles (2.5–10 wt.%) were fabricated, and their gamma-ray shielding performance was evaluated experimentally and theoretically. The structural and morphological properties of the nanoparticles were characterized by XRD, FTIR, and FESEM. Mass attenuation coefficient (MAC), half-value layer (HVL), and mean free path (MFP) were experimentally determined at photon energies of 81–1332 keV and validated using WinXCom calculations and MCNP6.3 Monte Carlo simulations. In addition, the effective atomic number (Z_eff) and effective electron density (N_eff) were calculated over the energy range of 0.001–100 MeV. Increasing the Bi₂WO₆ content enhanced the MAC, Z_eff, and N_eff values while reducing the HVL and MFP, indicating improved shielding efficiency. The composite containing 10 wt.% Bi₂WO₆ exhibited the highest attenuation performance, achieving an MAC of 0.4638 cm² g⁻¹ at 81 keV. The maximum deviation between experimental, theoretical, and simulation results remained below 2.8%, demonstrating excellent agreement. These findings identify Bi₂WO₆-reinforced UPR nanocomposites as promising lightweight, lead-free materials for gamma-ray shielding applications. Full article

Accurate interpretation of radiation sensor decay data is important for environmental monitoring, site remediation, radiation metrology, detector quality assurance, and nuclear data evaluation. When the original gamma spectrometry records are unavailable, a published decay plot may be the only source that can be reanalyzed independently. This study presents a reproducible reduced-data workflow for testing half-life estimates from a digitized ¹⁹⁸Au decay dataset. A weighted exponential fit to the digitized data points reproduces the published room-temperature half-life, indicating that the main decay scale is retained in the figure-level dataset. The analysis then tests how the fitted result changes under plausible figure-level effects, including baseline-like offsets, time-axis reconstruction, finite-window leverage, and ratio-based robustness checks using pairwise summaries and Steiner’s most frequent value statistics. The no-offset fit is locally well constrained, but small constant offsets can shift the fitted half-life because the normalization, decay constant, and residual baseline are partly degenerate over the limited time window. Toy Monte Carlo diagnostics show that some estimator shifts are expected for finite-window exponential data. This study does not revise recommended nuclear data or replace the original experiment. Instead, it shows how published radiation sensor decay data can be tested for reproducibility, identifiability, and sensitivity to analysis choices when only reduced or figure-level information is available. Full article

Background/Objectives: The optimal radiotherapy modality for World Health Organization (WHO) Grade 1 meningioma remains uncertain. Proton therapy offers dosimetric advantages through reduced radiation exposure to normal brain tissue, but comparative clinical data across contemporary radiotherapy modalities are limited. We performed a systematic review and meta-analysis comparing local control (LC) outcomes among conventionally fractionated proton therapy (CF-PT), conventionally fractionated photon radiotherapy (CF-Photon RT), Linac-based stereotactic radiosurgery/radiotherapy (Linac-based SRS/SRT), and Gamma Knife radiosurgery (GKRS). Methods: A systematic literature search of PubMed (2000–2024) was conducted to identify studies reporting LC for WHO Grade 1 meningioma treated with CF-PT, CF-Photon RT, Linac-based SRS/SRT, or GKRS. Random-effects meta-analyses were performed to estimate pooled 1- to 5-year LC rates. Random-effects meta-regression analyses were conducted using modality, age, sex, and gross tumor volume (GTV) as covariates. Results: Twenty-four studies comprising 4673 patients were included in the meta-analysis. Median GTVs were larger in the CF-PT and CF-Photon RT cohorts than in the Linac-based SRS/SRT and GKRS cohorts. All modalities achieved excellent LC: 5-year LC rates were 95.9% for CF-PT, 93.0% for CF-Photon RT, 95.3% for Linac-based SRS/SRT, and 89.8% for GKRS. Meta-regression showed no significant association between modality or GTV and LC. In the CF-PT cohort, 5-year overall survival was 93.1%. Conclusions: Major radiotherapy modalities achieved excellent and comparable LC. Notably, CF-PT and CF-Photon RT maintained favorable LC despite being used for larger tumors than stereotactic approaches. Future studies are needed to evaluate long-term tumor control and treatment-related toxicity to define optimal treatment strategies. Full article

For many years, our research group has been studying a phenomenon initially discovered in biological models: a solution of a substance subjected to vibration treatment exerts a modifying effect on an intact sample of the same substance, altering its physicochemical and biological properties. This effect also occurs without direct contact, when the vibration-treated and intact substances are kept in separate vials. Since the emergence of this modifying effect requires minimal energy input, we suggest that it is mediated by pre-existing supramolecular mechanisms. During vibration, the molecules deviate from a specific axis of symmetry (a local stationary state), which likely activates an evolutionarily developed supramolecular control over the molecular spatial structure. While testing this hypothesis, we observed that the modifying effect can be detected at a significant distance. This finding indicates that the phenomenon cannot be explained solely by the direct electromagnetic radiation of the vibrating molecules. Instead, the vibration treatment remotely alters the electromagnetic environment of the intact substance, thereby inducing the modifying effect. While non-trivial quantum effects might underlie this process, we favor the assumption that other fundamental interactions influence the electromagnetic field. Full article

A large quantity of irradiated nuclear graphite has been generated worldwide and must be managed as radioactive waste. In Germany, the final disposal of irradiated graphite (i-graphite) remains challenging due to limited knowledge of the radionuclide inventory and strict regulatory constraints. The presence of gamma-emitting radionuclides raises concerns regarding radiation exposure during handling, for example, in reactor decommissioning operations. Decontamination processes are therefore being investigated to enable the selective removal of key radionuclides, with the dual objective of facilitating waste acceptance and enabling the potential reuse of treated graphite in technical applications. This study focuses on the selective removal of volatile gamma-emitting radionuclides using a thermal treatment approach. In this work, a steam-assisted thermal treatment was applied to i-graphite samples from the Forschungsreaktor Jülich 2 (FRJ-2). The influence of key process parameters, including temperature, treatment duration, and relative humidity, was systematically investigated. The results show complete removal of ⁶⁰Co and ¹³⁷Cs, while partial removal of approximately 40% was achieved for ^152,154,155Eu and ²⁴¹Am. No release of ¹³³Ba was observed. These findings demonstrate the potential of high-temperature treatment as an effective method for reducing the radionuclide inventory of irradiated graphite, thereby contributing to improved waste management strategies and safer handling during decommissioning. Full article

Large episodes of solar activity of the 25th cycle, an extreme Forbush decrease event on 19 January 2026, a series of Forbush effects in November 2025, and an event of ground-level enhancement (GLE 77) on 11 November 2025 have left prominent traces in the monitoring data obtained at a height of 3340 m a.s.l. from the detector facilities of the Tien Shan High-Mountain Cosmic Ray Station. The effects these events have caused on the flux of galactic cosmic rays in the several-GeV energy range, as registered with the standard NM64-type neutron supermonitor, are compared here with their influence on the local neutron and gamma radiation background in the high-mountain environment, which was observed in the counting rate records of the thermal neutron and MeV-order-energy gamma radiation detectors also installed at the station. Full article

To assess the environmental impact of uranium mining operations in southern Kazakhstan, the elemental and radionuclide composition of soil samples collected from settlements in the Kyzylorda Region was investigated. The analysis was carried out using X-ray fluorescence (XRF) and gamma-ray spectrometry. Mean concentrations and variation ranges were determined for 28 chemical elements, including uranium, lead, antimony, and gamma-emitting radionuclides such as ¹³⁷Cs, ⁴⁰K, ²³²Th, ²³⁸U, ²²⁶Ra, ²¹⁰Pb, and ²⁴¹Am. The analysis of the specific activities of the artificial radionuclides ¹³⁷Cs and ²⁴¹Am was carried out in order to assess the influence of the Semipalatinsk Test Site on the soils of the study area. Based on the obtained data, heavy metal pollution indices, ecological risk indices, and radiological parameters were calculated to evaluate the potential environmental and human health impacts. Most elements were present at levels below average crustal abundances, suggesting limited anthropogenic influence. Slight exceedances for uranium, lead, and antimony are likely associated with regional geochemical features. Radiological assessment indicated that the radiation environment remains within internationally accepted limits. The lifetime cancer risk values for exposure of humans to natural radionuclides ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs from soil at 1 m above ground level ranged from 0.19 × 10⁻³ to 0.30 × 10⁻³, with an average of 0.24 × 10⁻³. Nearly all sampling points remained below the risk threshold of 0.29 × 10⁻³, indicating minimal radiological hazard. The carcinogenic risk remained within the acceptable regulatory range for both adults (2.0 × 10⁻⁵) and children (4.4 × 10⁻⁵), whereas the non-carcinogenic hazard index for children (1.3) slightly exceeded the screening threshold of 1. This finding identifies children as the most sensitive receptor group under the conservative assumptions of the applied screening methodology. The study demonstrates the applicability of combined chemical and radiometric methods for comprehensive environmental assessments in uranium mining regions. The results are of interest both in terms of methodology and in understanding the local geochemical and radiological landscape. Full article

On 14 February 2025, the outer cladding of the Chornobyl New Safe Confinement (NSC) was damaged by an explosion caused by a one-way attack unmanned aerial vehicle (UAV), creating a hole of about 15 m in diameter and requiring about 300 penetrations to be made in the cladding during firefighting. This created an urgent need to assess radiation dose rates above damaged areas to support repair planning and worker radiation protection. This study presents a UAV-based survey of the equivalent gamma dose rate distribution above the damaged northern side of the NSC outer cladding. The survey used a bespoke system, integrating a multirotor UAV, an AccuRad Personal Radiation Detector (PRD), onboard data acquisition and transmission modules, and ground-based and server-side analytical components. Measurements were performed under real post-incident field conditions, including restricted flight zones, wind-induced turbulence, proximity to large metallic structures, and electronic warfare interference. The dataset was filtered for Global Positioning System (GPS) reliability, transformed into a metric coordinate system, and processed for spatial interpolation and mapping. The resulting distribution showed a spatially non-uniform radiation field: the main damage zone had relatively low equivalent gamma dose rates, whereas the highest values, up to 1092 μSv/h, were recorded over areas of the NSC closest to the Shelter Object. The study demonstrates UAV-based radiation mapping of a damaged large-scale confinement structure and provides data supporting Chornobyl Nuclear Power Plant repair planning. Full article

This study investigates how ionising radiation alters the structure and interfacial role of cellulose nanocrystals (CNCs) in starch–poly(vinyl alcohol) (PVA)–alginate biopolymer films for biodegradable packaging. Films containing alginate (0–15 wt%), CNC (0–2 wt%), glycerol (20–30 wt%), and either corn or wheat starch were prepared by solution casting and exposed to gamma and electron beam irradiation (0–15 kGy). The focus was on how radiation affects CNC-mediated hydrogen bonding, network organisation, and structure–property relationships in the multicomponent polysaccharide matrix. Moderate alginate content (5–10 wt%) combined with 1 wt% CNC promoted a more cohesive network through enhanced intermolecular interactions, improving resistance to radiation-induced structural disruption. Higher CNC or glycerol contents, however, induced phase heterogeneity and weakened interfacial stability. Distinct responses were observed between wheat and corn starch matrices, attributed to differences in amylose content that govern film formation and the effectiveness of CNC reinforcement under irradiation. Dose-dependent effects revealed a balance between chain scission and network rearrangement. At 5–10 kGy, reduced swelling, improved thermal stability, and preserved mechanical performance indicated partial structural preservation facilitated by CNC interfacial reinforcement. At 15 kGy, dominant degradation led to reduced gel fraction and deterioration of film integrity. Optimal performance was achieved for films containing 20 wt% glycerol, 5–10 wt% alginate, and 1 wt% CNC irradiated at 5–10 kGy. These findings highlight the central role of CNC in modulating radiation-driven structural evolution and demonstrate how composition and dose can be tuned to control the stability and functionality of cellulose-reinforced polysaccharide films. Full article

Lead-free polymer composites containing high-atomic-number fillers are promising alternatives to conventional lead shielding for nuclear medicine applications. In this study, Bi₂O₃-, WO₃-, and hybrid Bi₂O₃/WO₃ nanoparticle-filled epoxy resin composites were fabricated and evaluated for attenuation of the 140 keV photons emitted by technetium-99m (Tc-99m). The synthesized Bi₂O₃ and WO₃ nanoparticles exhibited hydrodynamic diameters of 638.2 ± 11.3 and 404.2 ± 3.2 nm, respectively, with polydispersity indices below 0.30 and zeta potentials of −33.73 ± 0.63 and −32.47 ± 0.75 mV, indicating acceptable dispersion characteristics and colloidal stability. SEM–EDX confirmed successful incorporation of Bi- and W-containing phases into the epoxy matrix, while the XRD and FTIR analyses verified retention of the crystalline metal oxide phases and the principal chemical structure of the cured epoxy network. Tensile testing revealed a composition-dependent strength–ductility relationship, with the Bi₂O₃-filled composite exhibiting the highest tensile strength among the developed formulations and the hybrid composite showing the greatest elongation at break. XCOM and Phy-X/PSD simulations demonstrated that increasing high-Z filler content enhanced the mass and linear attenuation coefficients and reduced the half-value layer, tenth-value layer, and mean free path. Experimental shielding performance was evaluated using Hp(10) measurements with optically stimulated luminescence dosimeters positioned on an anthropomorphic thorax phantom under a fixed Tc-99m exposure geometry. The transmitted dose decreased with increasing filler loading, and nanoparticle-filled formulations generally outperformed the corresponding conventional-particle composites. The hybrid 75:25 Bi₂O₃/WO₃ NP composite exhibited the lowest mean Hp(10) value of 0.016 µSv, corresponding to a 50% reduction relative to the lead reference under the investigated geometry. The combined structural, mechanical, computational, and dosimetric results demonstrate that hybrid filler design enables simultaneous optimization of attenuation efficiency and mechanical tolerance. These findings identify the Bi-rich hybrid epoxy composite as a promising lead-free material for customized shielding components, including vial holders, syringe-shield housings, protective panels, and workstation accessories used during Tc-99m handling in nuclear medicine. Full article