To develop and externally validate a prediction framework integrating clinical factors, dose‒volume histogram (DVH) parameters, radiomics, dosiomics and deep - learning (DL) features for individualised radiation-induced hypothyroidism (RIHT) risk assessment. This retrospective multicentre study included 396 patients with nasopharyngeal carcinoma (NPC) treated with radiotherapy between January 2020 and December 2024. Patients from Fujian Cancer Hospital were randomly divided into training and internal validation cohorts, whereas patients from the First Affiliated Hospital of University of South China formed an independent external-test cohort. RIHT was treated as a binary endpoint defined by persistent thyroid-stimulating hormone (TSH) elevation above the institutional upper reference limit during follow-up. Clinical factors, thyroid DVH parameters, computed tomography (CT) radiomic features, dose-distribution dosiomic features, and ResNet18-derived DL features were extracted and integrated to develop single-modality and multimodal fusion models. Model performance was evaluated via the area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, specificity, calibration analysis, decision curve analysis (DCA), SHapley Additive exPlanations (SHAP) attribution and gradient-weighted class activation mapping (Grad-CAM) visualisation. Among 396 patients, 150 developed RIHT. In the internal validation cohort, the early-fusion and combined models achieved AUCs of 0.822 and 0.775, respectively; in the external test cohort, the corresponding AUCs were 0.827 and 0.813, with models achieving an accuracy of 0.750 and 0.775, sensitivity of 0.933 and 0.867, and negative predictive value of 0.941 and 0.900. The combined model showed the lowest Brier scores in both validation cohorts, whereas the early fusion model showed stronger discrimination but substantial calibration-slope deviation. Calibration and DCA showed improved agreement and greater clinical net benefit for the fusion models compared with single-modality models. SHAP quantified multimodal feature contributions, and Grad-CAM supported partial anatomical localisation. Multimodal fusion of clinical, DVH, radiomic, dosiomic, and DL features improved the robustness and external generalizability of RIHT prediction after radiotherapy for NPC. The early-fusion and combined model showed the most favorable overall performance, although calibration varied and the external cohort was small. These findings support further prospective multicentre evaluation rather than immediate clinical deployment.

Coherent L12 nanoprecipitate were introduced into a Co-free FeCrNi-based high-entropy alloy (HEA) to develop a precipitation-strengthened FeCrNiAlTi alloy, and their effects on its hydrogen embrittlement (HE) behavior were systematically investigated. The results demonstrate that, despite exhibiting higher hydrogen retention, the FeCrNiAlTi alloy shows superior resistance to HE compared with the FeCrNi alloy. This enhanced resistance is mainly attributed to the formation of a strong-trap population at coherent L12/matrix interfaces, as indicated by the additional high-temperature desorption peak in the TDS spectra. These deep traps are considered to lower the effective mobile hydrogen fraction and thereby reduce the contribution of diffusible hydrogen to hydrogen-assisted cracking. Our work demonstrates that precipitate-interface engineering can enhance the HE resistance of HEAs by coupling hydrogen trapping with the regulation of deformation localization, and provides a viable microstructural design strategy for developing excellent hydrogen-damage-resistant HEAs.

VTiTa refractory multi-principal element alloys (MPEAs) are promising for irradiation environments, yet the role of local chemical order (LCO) in their radiation response remains to be clarified. We simulated collision cascades in VTiTa with random solid solution (RSS) and LCO states using molecular dynamics with a machine-learned potential. At the thermal-spike stage, LCO VTiTa lowers the peak number of Frenkel pairs (FPs) relative to RSS by about 35% at 10 keV, whereas the difference becomes much smaller at 50 keV. At the end of cascade simulation, however, RSS and LCO VTiTa retain comparable numbers of residual FPs, indicating that under single-cascade conditions LCO has only a limited effect on the final surviving point-defect population. Its main influence is instead manifested in defect morphology and clustering behaviors: relative to RSS VTiTa, LCO suppresses vacancy clustering and retains defects in a more dispersed form, and dislocation loop formation is noticeably weaker in both VTiTa structures than in pure V and VTa. These results show that the primary effect of LCO is to modify early-stage defect production and subsequent clustering behavior, and they provide atomistic guidance for the design of radiation-tolerant refractory MPEAs through control of chemical order.

Introduction To develop and evaluate a multi-omics machine-learning model that integrates clinical variables, dose-volume histogram (DVH) metrics, radiomics, and dosiomics from both the rectum and rectal wall regions of interest (ROIs) to improve prediction of acute radiation proctitis (ARP) in cervical cancer patients receiving radiotherapy. Methods In this single-center retrospective cohort, 107 cervical cancer patients were randomly split into a training set (n = 85) and a testing set (n = 22) in an 8:2 ratio. Radiomic were extracted from planning CT, and dosiomic features from 3-D RT-dose distributions, for both rectum and rectal wall ROIs. Features were z-score standardized; redundant features were filtered by Pearson correlation, followed by least absolute shrinkage and selection operator (LASSO) for selection. Support Vector Machine (SVM) and Multilayer Perceptron (MLP) classifiers were trained using stratified five-fold cross-validation within the training set. Model performance was assessed on the held-out test set using receiver operating characteristic (ROC) analysis; clinical utility was evaluated with decision-curve analysis (DCA). The primary endpoint was Common Terminology Criteria for Adverse Events (CTCAE,version 5.0) grade ≥2 ARP. Results Multi-omics fusion outperformed single-modality models across ROIs and classifiers. The rectal-wall multi-omics SVM achieved the best discrimination with AUC 0.867 (95% Confidence Interval [CI]:0.709-1.000) in the test set; performance for the whole-rectum region of interest (ROI) was lower (AUC 0.714). DVH-only models showed limited discrimination, and no DVH feature was retained after penalized selection in the multi-omics pipeline. DCA demonstrated the greatest net clinical benefit for the rectal-wall multi-omics model across threshold probabilities 0.20–0.50. Conclusion A rectal-wall, region-specific multi-omics approach integrating clinical, radiomic, and dose-based descriptors improves prediction of radiotherapy-induced ARP compared with single-modality and whole-rectum analyses. These findings highlight the importance of ROI selection and multi-omics integration for precision toxicity assessment and support future external validation and prospective evaluation.

This study investigates the swelling behavior and defect evolution of FCC AlxCoCrFeNi high entropy alloys (HEAs) under high temperature helium (He) ion irradiation. Helium irradiation resistance improves systematically as the aluminum content increases. The aluminum containing alloys exhibit smaller He bubbles, higher bubble number densities, lower swelling, and more effectively suppressed dislocation growth, especially at high fluence. This improvement is mainly attributed to the enhanced local lattice distortion introduced by aluminum. The increased atomic size mismatch reduces the mobility of vacancies and He related defects, promotes defect recombination, and favors more dispersed bubble nucleation sites. Fine dislocation loops formed in the aluminum containing alloys also act as effective defect sinks, thereby further suppressing defect coarsening. These findings provide new insights into the role of aluminum in regulating He irradiation damage and offer guidance for the design of He irradiation resistant alloys.

Irradiation induced swelling and defect accumulation severely limit the deployment of advanced materials in nuclear environments. Here, we demonstrate that nanotwins can significantly improve the tolerance of a singlephase face-centered cubic FeCoCrNi alloy to irradiation. Cold-rolling induced nanotwinning increased the yield strength from 123.88 MPa to 659.72 MPa, and the ultimate tensile strength from 379.76 MPa to 693.97 MPa. The nano-twinning induced by cold rolling deformation increased the yield strength from 123.88 MPa to 659.72 MPa and its tensile strength from 379.76 MPa to 693.97 MPa. Helium ions with monotonic energy of 20 key were implanted in the samples with and without nanotwins at723 K. The results show that the average size of helium bubble in the nanotwinned alloys decreased by similar to 8% and the density was slightly reduced. Owing to the high density of twin boundaries that act as strong defect sinks and helium capture sites, the swelling rate decreased from 1.77% to 0.71%. Since helium bubble nucleation is influenced by twin boundary density, helium retention in the samples decreased from 53.6% to 38.4% after the introduction of twin boundaries. These findings establish nanotwin engineering as a practical route to mitigate helium damage in multi-principal-element alloys.

As a core component in high-energy physics experiments, the performance of the positron source target directly determines the positron yield and the overall operational stability of the system. This study presents a systematic design of a positron source target tailored for an electron (10 MeV, 10 kW) accelerator. Initially, Monte Carlo simulations using Geant4 were conducted to optimize the target thickness for maximizing positron production. Subsequently, a series of multi-layer water-cooled target models were established. Their temperature distributions under high-power electron beam bombardment were simulated using Finite Element Analysis (FEA) to determine the optimal number of target layers. The transient simulation results indicate that for the 6-layer target operating at 10 kW, the maximum surface temperature of the tungsten plates reaches 370 K, which is well within the safety limits. Furthermore, thermal stress analysis reveals that the maximum stress within the target is 22 MPa, ensuring a sufficient safety margin. The findings of this research confirm the feasibility of the proposed target design and provide valuable technical insights for the engineering development of high-power positron sources.

Hydrogen embrittlement remains a major obstacle to the reliable use of advanced structural alloys in hydrogenrich environment. Here we show that aluminum alloying substantially enhances embrittlement resistance in cobalt-free Ni-Cr-V multi-principal element alloys by reshaping hydrogen-defect interactions across length scales. Experiments combined with first-principles calculations reveal that increasing aluminum content reduces hydrogen uptake by up to 80% and suppresses vacancy formation. Aluminum raises hydrogen dissolution energies through diminished electron transfer from the alloy matrix to hydrogen, while simultaneously strengthening hydrogen trapping and increasing diffusion barriers, thereby shifting hydrogen release to higher temperatures. These effects improve plastic deformation capacity, alleviate local stress concentrations, and delay crack initiation, thereby mitigating macroscopic ductility loss in the presence of hydrogen. Our findings establish aluminum alloying as an effective compositional lever for designing similar metallic materials resilient to hydrogen-rich environments.

The behavior of hydrogen (H) and its interaction with defects in a Fe6Cr1.2Mn0.8Cu1.5Mo0.5 alloy irradiated with 30 keV H ions under various fluence and temperatures was investigated using positron annihilation spectroscopy. Results reveal that significant numbers of vacancy-type defects are formed in samples irradiated at room temperature, where H atoms combine with vacancies to form H-vacancy complexes (HmVn). The irradiation damage profile shows substantial variation with depth. In high-fluence irradiated samples, the formation of HmVn complexes (m > n) suppresses the increase in effective open volume defects. The vacancy concentration gradually decreases with increasing irradiation temperature. Coincidence Doppler Broadening (CDB) spectroscopy demonstrates that vacancies generated in alloys irradiated at 150 degrees C exhibit migration capability, ultimately aggregating into vacancy clusters. Notably, Cu precipitation sites are identified as preferential nucleation points for vacancy cluster formation. Elevated irradiation temperatures lead to a gradual reduction in vacancy cluster size and accelerated recovery processes. At 450 degrees C irradiation temperature, vacancy defects dissociated from Cu precipitates undergo nearly complete recovery. This study establishes positron annihilation spectroscopy as an effective methodology for elucidating H behavior and HmVn complex evolution in multi-principal element alloys.

Carbon/carbon (C/C) composites are critical structural materials for advanced reactors, including molten salt reactors. However, the irradiation mechanisms, particularly the differences in irradiation-induced damage between fibers and matrices, remain inadequately understood. In this study, the irradiation behavior of mesophasepitch-based carbon-fiber-reinforced carbon matrix composites was investigated under 1.8-MeV Ar-ion irradiation at a dose of 3 x 1016 ions/cm2 at room temperature. Following irradiation, both the carbon fiber and matrix underwent amorphization and exhibited significant changes in surface morphology, the matrix exhibiting pronounced volumetric shrinkage compared to the fiber. Additionally, irradiation resulted in the degradation of the ordered graphite layers and closure of the initial cracks within the fiber and matrix. Notably, the matrix contained a greater number of initial cracks and crack closure was more pronounced during irradiation compared to the fiber. The differential shrinkage observed between the fiber and matrix is primarily attributed to the differences in the irradiation-induced closure behavior of the initial cracks in each component. These findings provide insights into enhancing the irradiation performance of C/C composites by adjusting the microstructural composition of the fiber and matrix.

In order to improve the focusing efficiency of the slow positron beam device, it is necessary to provide a wide Voltage amplitude and high slew rate focusing modulation waveform for the focusing device in the device. In this article, a high-voltage fast conversion operational amplifier is used as the core amplification device to design an amplification system to amplify the beam modulation waveform generated by the signal generator. The design principle and implementation method of the entire system are introduced, and the PCB diagram of the amplification circuit is provided. The performance of the amplification circuit built based on the high-voltage fast conversion operational amplifier is tested. The experimental results show that the high-voltage fast conversion operational amplifier can be used as an amplification stage for the beamforming modulation waveform generated by the signal generator. The amplified output of the actual waveform is provided to the collimator for beam compression, which has significant effects.

A high-strength CoCrFeNi-based alloy (HEA1) was prepared by introducing L12 precipitation, and the effect of L12 precipitation on hydrogen (H)-induced damage and the hydrogen embrittlement (HE) sensitivity of HEA1 was studied. Compared with the CoCrFeNi alloy, the strength and ductility of HEA1 were simultaneously enhanced after H charging, and the alloy exhibited stronger HE resistance. Positron annihilation spectroscopy results indicated a higher concentration of vacancy-type defects in HEA1 than in the CoCrFeNi alloy. Hydrogen-induced vacancy clusters were identified as the primary cause of crack initiation. The capture effect of the L12 precipitation/matrix interface can act as an H trap, thereby increasing the solubility of H atoms while reducing their diffusion/migration rate. This mechanism contributes to a reduced tendency for H-induced intergranular cracking, thereby improving resistance to HE. Our work reveals the positive effect of ordered precipitation on H tolerance, providing insights for further microstructure design of medium-and high-entropy alloys used in H-rich environments.

This study examines the irradiation resistance of a novel Ti8V22.5Cr22.5Mn22.5Fe22.5Si2 high-entropy alloy (HEA) through techniques such as scanning/transmission electron microscopy, positron annihilation spectroscopy, and grazing incidence X-ray diffraction. The results highlight an unusual lattice contraction upon irradiation, diverging from typical responses of traditional alloys, with no evidence of irradiation-induced precipitation. Under high-dose irradiation (similar to 188 dpa), the HEA displayed no discernible void swelling, potentially due to abundant precipitate interfaces, high equilibrium vacancy concentration, and the intrinsic properties of HEA. The HEA, exhibiting smaller dislocation loops (similar to 3.2 nm) and a lower irradiation hardening rate (similar to 3.3 %) compared to conventional alloys, demonstrates significant promise as a material for future-generation core components.

This study systematically investigates the evolution of vacancy-type defects and heterogeneous Cu nanoprecipitates in an Fe60Cr12Mn8Cu15Mo3V2 (at%) multi-principal element alloy during thermal processing, utilizing Positron annihilation lifetime spectroscopy (PAS), coincidence Doppler broadening (CDB) spectroscopy, and transmission electron microscopy (TEM). The results show that the alloy exhibited a dual-phase coexistence structure of Body-Centered Cubic (BCC) and Face-Centered Cubic (FCC). The CDB results show that the density of heterogeneous Cu precipitates gradually increases with annealing temperature. Compared to the as-cast alloy, the precipitates annealed at 773 K exhibit a significantly reduced size (approximately 33 nm) with higher density. The PAS results demonstrate that gradual migration and aggregation of monovacancies at 573 K form vacancy clusters, while contraction and dissociation of these clusters dominate at 673 K. Within the temperature range of 773-973 K, the dynamic equilibrium between the aggregation and decomposition of vacancy clusters maintains stable annihilation characteristics with minimal lifetime changes.

Plasma-facing materials used in fusion energy facilities, such as pure tungsten (W) and tungsten-nickel-iron (WNi-Fe) alloys, must withstand helium irradiation, which can lead to nanocrack that eventually develop into surface blistering and large-size crack. The mechanisms behind this phenomenon remain elusive, highlighting the need for a detailed investigation. This study employed positron annihilation spectroscopy (PAS) and transmission electron microscopy (TEM) to analyze the development of nanocracks. The results elucidate that helium irradiation initially engenders vacancy-type defects within the material matrix. As the irradiation dose escalates, implanted helium atoms are captured by these vacancies, leading to the formation of helium-vacancy complexes that subsequently expand into larger aggregates and eventually evolve into helium bubbles. The coalescence of these bubbles results in the generation of high-pressure helium entities, which precipitate nanocrack formation once the internal pressure surpasses the structural limits of the material, ultimately culminating in surface blistering.

Tungsten-nickel-iron (W-Ni-Fe) alloys, commonly known as W heavy alloys (WHAs), exhibit enhanced ductility, thermal conductivity, and mechanical attributes. These properties render WHAs highly suitable as plasma-facing materials in lieu of pure W. This investigation examines the irradiation resistance of two WHAs—97W-2Ni-1Fe and 90W-7Ni-3Fe—by subjecting them to He ion irradiation at doses reaching 5 × 1017 ions/cm2. The study establishes that low-dose irradiation (1 × 1017 ions/cm2) inflicted negligible surface damage on both WHA compositions. Nonetheless, increasing the radiation dose to 5 × 1017 ions/cm2 led to observable surface impairments, albeit at a reduced magnitude when compared to pure W. An array of analytical methods was employed to characterize irradiation-induced microstructures and void swelling, including positron annihilation spectroscopy, thermal desorption spectroscopy, and transmission electron microscopy. These analyses revealed that low-dose irradiated WHAs predominantly generated vacancy-type defects. Moreover, these defects evolved into HemVn and HemVn-NiFe complexes as the irradiation dose increased. Concurrently, He bubble density escalated with rising irradiation dosage. When subjected to an irradiation dose of 1 × 1017 ions/cm2, both alloys manifested desorption levels approximately 6.5 times greater than that observed in pure W. The findings of this investigation offer valuable insights to the understanding of WHA irradiation behavior in nuclear materials.

正电子湮没信号的精准采集与关联符合技术是寿命谱灵敏表征材料微观缺陷的基础.测量环境中放射性射线对正电子湮没信号采集的影响,制约着寿命谱方法在复杂辐射背景中应用,特别是在核结构材料中子辐照损伤研究中,中子活化诱发的放射性核素形成的γ射线本底,将影响正电子寿命谱仪的测量结果.为探究γ本底对正电子湮没寿命测量的影响规律,本文基于60Co、137Cs源设计了辐射背景仿真实验,结果显示:60Co源产生的双高能γ射线是影响寿命谱形状及湮没寿命的主要因素;通过对比高、低两种典型活度比(60Co/22Na为3.3和1.9)下的测量结果,并经活化反应堆压力容器钢样品放射性本底真实情况检验,结果发现:在低活度比下,辐射本底导致的偶然符合概率增大,寿命谱峰谷比显著变差;在高活度比下,除偶然符合外,信号错误符合概率急剧增加,谱形明显畸变且寿命值迅速减小.基于本文辐射背景放射源模拟方法及干扰γ的影响规律,可进一步探索正电子湮没寿命测量中γ本底排除的新技术和新方法.

Radon is a naturally occurring radioactive inert gas that poses a significant threat to the human health. Coconut shell activated carbon has been verified to be the best radon adsorbing material, but its radon adsorption capacity still cannot meet the requirement of industrial applications. Activated carbon modification using liquid nitrogen is an effective method for improving the radon adsorption capacity, but it is necessary to determine the conditions for large-scale production. In this study, the influence of environmental temperature, container geometry, and amount of activated carbon and liquid nitrogen on the modification effect are examined. The results show that the activated carbon has the best modification effect when the container is placed in a water bath at 50 °C. The container geometry and activated carbon mass have a minor influence on the modification effect. Further, the radon adsorption capacity is increased by 36% when 6.5 L of liquid nitrogen is added to 1 kg of activated carbon. The characterization results reveal that the chemical structure and elemental content of the activated carbon do not change after modification, but the number of micropores is significantly increased, especially the micropores with a size of 0.5-0.6 nm, which is related to the radon adsorption capacity of the modified activated carbon. Overall, the liquid-nitrogen-based modification is a simple, environment-friendly, and low-cost method to improve the radon adsorption capacity of activated carbon, which can be used in the large-scale production of highly efficient radon adsorbents.

Determining the distribution of muonic atoms is essential for μ -X ray imaging. In this study, the generation and de-excitation of muonic atoms in multi-elemental targets were simulated using the Monte Carlo software toolkit Geant4. An approach that reconstructs the production sites of muonic atoms from the μ -X ray momentum is proposed. The imaging results indicated a high simulated spatial resolution of 0.1 mm and a significant increase in the detection efficiency compared to that achieved by the 3-mm pinhole imaging technique. In addition, an analysis of the image quality index ( Q ) revealed that a superior image quality can be achieved for elements with high and medium atomic numbers. The proposed method has the potential to be further developed into an accurate and efficient technique for positioning the distribution of elements.

Background:Necroptosis is progressively becoming an important focus of research because of its role in the pathogenesis of cancer and other inflammatory diseases. Our study is designed to anticipate the survival time of kidney renal clear cell carcinoma (KIRC) by constructing a prognostic signature of necroptosis-related genes.Materials:Clinical information and RNA-seq data were acquired from Renal Cell Cancer-European Union (RECA-EU) and The Cancer Genome Atlas- (TCGA-) KIRC, respectively. ConsensusClusterPlus was used to identify molecular subtypes, and the distribution of immune cell infiltration, anticancer drug sensitivity, and somatic gene mutations was studied in these subtypes. Subsequently, LASSO-Cox regression and univariate Cox regression were also carried out to construct a necroptosis-related signature. Cox regression, survival analysis, clinicopathological characteristic correlation analysis, nomogram, cancer stem cell analysis, and receiver operating characteristic (ROC) curve were some tools employed to study the prognostic power of the signature.Results:Based on the expression patterns of 66 survival-related necroptosis genes, we classified the KIRC into three subtypes (C1, C2, and C3) that are associated with necroptosis, which had significantly different tumor stem cell components. Among these, C2 patients had a longer survival time and enhanced immune status and were more sensitive to conventional chemotherapeutic drugs. Moreover, in order to predict the prognosis of KIRC patients, five genes (BMP8A, TLCD1, CLGN, GDF7, and RARB) were used to develop a necroptosis-related prognostic signature, which had an acceptable predictive potency. The results from Cox regression and stratified survival analysis revealed that the signature was an independent prognostic factor, whereas the nomogram and calibration curve demonstrated satisfactory survival time prediction based on the risk score.Conclusions:Three molecular subtypes and five necroptosis-related genes were discovered in KIRC using data from TCGA-KIRC and RECA-EU. Thus, a new biomarker and a potentially effective therapeutic approach for KIRC patients were provided in the current study.