Search Results (1,393)

The formation of surface morphology under ion irradiation has been widely studied in various metals and metal surfaces. Nanoscale roughening or smoothing of the surface leads to changes in the thermal, electronic, and even antibacterial properties of metallic materials. In this study, first-principles calculations were used to gain insight into the modification of surface dipole moment due to changes in surface roughness for the case of tungsten (W). The physical nature of the change in work function (WF) due to surface roughness was found. For the W(100) surface, it was shown that the negative dipole layer formed on the surface prevents the outflow of electrons from the base metal, which leads to an increase in the WF from 3.92 eV to 4.17 eV with increasing surface roughness. The opposite was observed on the W(110) surface, where the decrease in the WF from 4.76 eV to 4.58 eV is due to a small dipole layer blocking electrons on the surface due to charge redistribution within the base metal. This study evaluates the changes in the electronic properties of W due to its surface modification under the ion beam irradiation, which can be applied in future experiments. Full article

Vitamin D comprises a group of fat-soluble secosteroids traditionally associated with animal physiology, calcium-phosphate homeostasis, and skeletal metabolism. However, vitamin D and related compounds have also been reported in taxonomically distinct non-animal systems, including fungi, microalgae, other algae, phytoplankton, and higher plants, although the strength of evidence differs substantially among these groups. This review synthesizes current knowledge on the occurrence, structural chemistry, UV-B-driven photochemical mechanisms, environmental determinants, analytical challenges, and biofortification potential of vitamin D formation in photosynthetic organisms and fungi. Vitamin D synthesis is initiated by UV-B radiation, primarily within the 290–315 nm range, which converts sterol precursors such as 7-dehydrocholesterol and ergosterol into previtamin D intermediates and is followed by thermal isomerization to the corresponding vitamin D forms. Continued irradiation may additionally generate lumisterol, tachysterol, and other photoproducts, thereby limiting net vitamin D accumulation. This non-enzymatic mechanism supports the interpretation that vitamin D formation can occur outside vertebrates when an appropriate 5,7-diene sterol precursor is accessible to a sufficient UV-B dose. In photosynthetic organisms and fungal matrices, net vitamin D accumulation is constrained by the spectral dose of UV-B, environmental exposure, tissue architecture, sterol localization, oxygen availability, antioxidant capacity, and ROS-mediated degradation. Studies of microalgae and phytoplankton, including reports concerning Emiliania huxleyi, suggest the occurrence or UV-B-dependent formation of both vitamin D₂ and vitamin D₃. However, these findings require evaluation according to the analytical method, use of authentic standards, experimental conditions, and confidence of compound identification. In fungi, the UV-B-induced conversion of abundant ergosterol to vitamin D₂ is well established. Microalgae represent a developing source of vitamin D₂ and vitamin D₃, whereas evidence for nutritionally relevant vitamin D accumulation in higher plants remains limited and heterogeneous. Although higher plants contain diverse phytosterols, the formation of vitamin D₄, vitamin D₅, or related analogues requires appropriate photoreactive 5,7-diene precursors and should not be inferred directly from the presence of common phytosterols such as β-sitosterol. Analytical detection remains challenging because of low concentrations, complex lipophilic matrices, and structural similarity among secosteroids and photoproducts; therefore, reliable identification requires validated analytical procedures. LC-MS/MS provides high sensitivity and selectivity but should be supported by authentic standards, preferably isotope-labelled internal standards, retention-time agreement, quantitative and qualifying ions, matrix-recovery assessment, limits of detection and quantification, and evaluation of ion suppression. Structurally similar analogues and photoproducts may additionally require orthogonal confirmation. Nutritionally, post-harvest UV-B enrichment of edible mushrooms is currently the best-validated strategy for increasing non-animal vitamin D₂ content. Microalgae constitute a developing platform for vitamin D₂ and vitamin D₃ production, whereas biofortification of higher plants remains experimental. Full article

The rapid development of Generation IV nuclear reactors has imposed stringent requirements on structural materials, demanding excellent irradiation resistance to withstand long-term exposure to complex radiation environments, including neutron and ion irradiation. Under irradiation, a large number of defects are generated inside materials via displacement cascades, and the dynamic evolution of these defects gradually leads to macroscopic property deterioration, potentially triggering major accidents such as equipment failure and even posing system safety hazards. Thus, understanding the law of defect evolution in materials under irradiation and exploring the microscopic mechanism of irradiation damage are core prerequisites for material service life prediction, radiation resistance optimization, and safety risk assessment. In recent years, computational simulation, leveraging its unique advantages in multiscale and multiphysics coupling research, has yielded numerous innovative achievements in the irradiation field. This review overviews the progress of computational simulation studies on irradiation damage in nuclear structural materials over the past few decades, focuses on summarizing the “generation-evolution-annihilation” process of irradiation defects, and further discusses the impact of irradiation on the macroscopic mechanical properties of materials. The content and outlook of this review can advance the microscopic-level comprehension of irradiation damage mechanisms in structural materials and provide guidance for the development of a new generation of materials with excellent irradiation resistance. Full article

The photocatalytic degradation of the 2,5-diphenyl-1,3-oxazole (PPO) and 2-(4-biphenyl)-5-phenyl-1,3,4-oxadiazole (PBD), which are laser dyes and scintillator compounds, was investigated under ultraviolet (UV) light irradiation using pure and rare-earth (Sm³⁺, Eu³⁺, and Gd³⁺)-modified zinc oxide (ZnO) hierarchical flower-like microstructures. The synthesized photocatalysts (powder) were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD), confirming the formation of flower-like ZnO structures and successful modification by the oxides Sm₂O₃, Eu₂O₃, and Gd₂O₃. Residual concentrations of Zn²⁺, Gd³⁺, Sm³⁺, and Eu³⁺ in the treated aqueous solutions were determined by ICP-MS to evaluate catalyst stability, while chemical oxygen demand (COD) analysis was used to assess mineralization efficiency. For both PPO and PBD, the photocatalytic activity followed the order ZnO < ZnO/Gd₂O₃ < ZnO/Sm₂O₃ < ZnO/Eu₂O₃, which can be attributed to the enhanced charge separation and reduced electron–hole recombination caused by rare-earth ions, with Eu³⁺ providing the most effective electron trapping. PPO showed faster degradation than PBD, mainly due to the structure of the PBD molecule, which is more rigid and conjugated, owing to its higher resistance to oxidative degradation. Full article

Radiation-induced defect engineering is an effective approach for modifying the vortex-pinning landscape in high-temperature superconductors, particularly REBCO-coated conductors and Bi-based cuprates. This review critically summarizes the relationship between irradiation parameters, defect morphology, and superconducting performance. The discussion covers point defects, defect clusters, columnar tracks, planar defects, and displacement cascades generated by electrons, gamma rays, light ions, heavy ions, and neutrons. Special attention is given to the dual role of irradiation: moderate defect concentrations can enhance the critical current density by introducing artificial pinning centers, whereas excessive disorder suppresses the superconducting transition temperature and degrades current transport. The review also discusses the relevance of irradiation effects for fusion magnets, space technologies, accelerator systems, and high-field applications. Finally, the review identifies key challenges for future HTS radiation engineering, including cryogenic in situ irradiation, coupled radiation–strain–field experiments, damage metrics beyond dpa, and multi-scale models capable of linking atomic defect production, oxygen disorder, vortex pinning, and macroscopic J_c/T_c degradation. Full article

Deploying retired lithium-ion batteries in photovoltaic energy storage systems is a promising second-life application, but heterogeneous aging and internal inconsistencies can induce the barrel effect, reducing available capacity and accelerating pack degradation. Existing equalization methods mainly rely on internal battery states and often neglect external irradiance fluctuations. To address this issue, this study proposes an irradiance-aware adaptive fuzzy active equalization strategy based on a multichannel bidirectional flyback converter. A second-order RC equivalent circuit model with a fifth-order OCV–SOC mapping is established to describe the dynamic behavior of retired cells. Then, solar irradiance and its rate of change are introduced into a dual-input fuzzy controller to adaptively regulate the equalization duty cycle according to both SOC inconsistency and PV input fluctuation. A saturation function constrains the active duty cycle below 0.5 to maintain discontinuous conduction mode operation and avoid transformer core saturation. Simulation results under rapid cloud occlusion, stable high irradiance, and persistent weak light show that the proposed strategy reduces equalization time by 13.8%, 4.4%, and 8.4%, respectively, compared with SOC-only fuzzy control. Under a publicly measured irradiance condition, the proposed strategy achieves the shortest equalization time of 3267.4 s, reducing the time by 24.2%, 27.7%, 29.0%, and 32.9% compared with traditional threshold-based, SOC-only fuzzy, maximum–minimum SOC, and PID-based strategies, respectively. Full article

This study addresses the need for dark-current control and stable current response in planar high-purity germanium (HPGe) detectors for low-energy X-ray detection. A device fabrication strategy based on the coupled optimization of near-surface treatment, N/P junction formation, and guard-ring electrode design is proposed. Unlike previous studies that mainly focused on contact-layer fabrication, segmented electrode structures, low-noise readout, or response simulation, this work investigates low-damage near-surface construction, N-type and P-type contact-layer formation, and edge-related leakage-current regulation as an interconnected processing route. The relationship among the near-surface state, junction quality, electrode configuration, and edge-related leakage current is emphasized. Chemical mechanical polishing (CMP) reduced the surface roughness Sa of the HPGe crystal to 6.68 nm, providing a low-damage near-surface foundation for subsequent junction fabrication. On this basis, the optimized Li thermal diffusion process, namely 0.5 Å s⁻¹, 325 °C, and 5 min, formed an N-type contact layer with preserved lattice ordering and favorable electrical properties. B ion implantation combined with rapid thermal processing (RTP) achieved acceptor activation and implantation-damage recovery, and the condition with Rp = 198.1 nm showed relatively better structural recovery and electrical characteristics. After introducing the guard-ring electrode, the dark current of the device at −20 V decreased from 6.5 × 10⁻⁹ A to 2.03 × 10⁻⁹ A, and a stable switching current response was obtained under 12 keV monochromatic synchrotron X-ray irradiation. Geant4 simulations were further used as an auxiliary analysis to evaluate the effect of the guard-ring structure on the simulated response spectra and full-energy peak efficiency (FEPE) for low-energy X-rays. Overall, this study provides experimental evidence for process optimization of planar HPGe detectors with low dark current and stable low-energy current response. Full article

As a typical representative of antibiotic contaminants, tetracycline (TC) remains persistent in surface water and wastewater. Coordination polymers have been confirmed to represent a highly efficient strategy for pollutant removal. In this study, a novel U(VI)-containing polymer, [UO₂(Htci)]·7.5H₂O, was obtained hydrothermally using uranyl nitrate hexahydrate and tris(2-carboxyethyl) isocyanurate (H₃tci). Structural characterization by single-crystal X-ray diffraction indicated a 2D layered crystalline architecture. The compound is interconnected by 3-connected Htci²⁻ anions to afford a characteristic (6, 3) honeycomb topological network. The ligand displayed a special cis-cis-trans conformation, and all carboxylic acid groups were bis-chelating. In addition, the compound was characterized by elemental analysis, FT-IR spectroscopy, powder X-ray diffraction (PXRD), thermal analysis, and photoluminescence spectroscopy. The photodegradation efficiency of TC reached 93.2% after 120 min under irradiation with UV light. At the same time, metal ion sensing of the compound revealed selectivity in recognition of Fe³⁺, with a detection limit of 0.77 mg·L⁻¹ being achieved. Full article

ZnS is one of the most promising wide-bandgap semiconductors for optoelectronic and sensing applications owing to its efficient ultraviolet–blue emission, high exciton binding energy, and chemical stability. However, the synthesis of ZnS nanocrystals in silicon-compatible porous matrices remains largely unexplored. In this work, ordered arrays of ZnS nanocrystals were synthesized for the first time in SiO₂/Si track templates fabricated by swift heavy ion irradiation followed by selective chemical etching. ZnS nanocrystals were deposited by electrochemical deposition from aqueous solutions containing ZnCl₂ and thiourea precursors. The structural, optical, and electrical properties of the resulting ZnS/SiO₂/Si nanocomposites were investigated using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, photoluminescence spectroscopy, and electrical measurements. The fabricated templates contained vertically aligned pores with a density of approximately 10⁸ cm⁻² and an average diameter of about 500 nm. Electrochemical deposition resulted in a pore filling efficiency of approximately 88%. X-ray diffraction analysis confirmed the formation of crystalline ZnS with a cubic zinc blende structure. The nanocomposites exhibit intense ultraviolet–blue photoluminescence in the 335–477 nm range, with pronounced emission peaks at 372 and 400 nm characteristic of ZnS nanocrystals. Current–voltage measurements indicate predominantly electronic conductivity, with a conductivity of 1.54 × 10⁻⁶ Ohm⁻¹·cm⁻¹, comparable to values reported for polycrystalline ZnS films. To support the experimental observations, the electronic structure of ZnS was analyzed using density functional theory within the LCAO framework. The calculated bandgap of 3.4 eV is consistent with previously reported theoretical and experimental data. The obtained results demonstrate that SiO₂/Si track templates provide a promising platform for the fabrication of ordered ZnS nanoarrays with potential applications in silicon-compatible optoelectronic and sensing devices. Full article

A novel composite catalyst for photothermal CO₂ cycloaddition was developed by integrating the ionic liquid 1-ethylpyridinium bromide (EPB) with a copper-based metal–organic framework (HKUST-1). HKUST-1 was synthesized via a hydrothermal method and functionalized with EPB through a wet impregnation strategy to enhance its catalytic performance. Under xenon lamp irradiation and optimized conditions (80 °C, 1 MPa CO₂ pressure, 12 h, and 0.07% mol of TBAB bromide as a co-catalyst), the HK@EPB composite exhibited outstanding performance in catalyzing the conversion of CO₂ and various epoxides into cyclic carbonates. The exceptional catalytic activity arises from a synergistic multicomponent mechanism: the incorporation of EPB not only enhances CO₂ adsorption capacity but also provides photothermal energy for the reaction; simultaneously, EPB dissociates bromide ions to effectively initiate epoxide ring-opening. In particular, propylene oxide achieved a selectivity of 95% for the desired cyclic carbonate, surpassing most previously reported MOF-based catalysts. This system enables efficient catalysis under mild conditions through the synergistic contributions of the high CO₂ adsorption capacity and Cu²⁺/Cu⁺ redox-mediated electron transfer of HKUST-1, the provision of nucleophilic Br-species from EPB to promote epoxide ring-opening, and the cooperative effect of TBAB. This study demonstrates that ionic-liquid-functionalized MOF composites can serve as sustainable and versatile catalytic platforms, offering an environmentally friendly pathway for large-scale CO₂ utilization. Full article

The long-term stability of biodegradable polymer coatings deposited by matrix-assisted pulsed laser evaporation (MAPLE) remains insufficiently understood, particularly under ultraviolet irradiation conditions where photochemical effects may accompany material transfer. In this work, thin films of poly(lactide-co-caprolactone)-block-poly(ethyleneglycol)-block-poly(lactide-co-caprolactone), also known as PLCL-PEG-PLCL, are deposited from chloroform solutions by UV-MAPLE using a nanosecond Nd:YAG laser operating at 266 nm over a wide laser fluence range (0.25–0.9 J/cm²). The effect of laser fluence on the morphological, structural, and chemical evolution of the coatings is investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), focused ion beam scanning electron microscopy (FIB-SEM), and X-ray diffraction (XRD). At low laser fluence, relatively homogeneous coatings are obtained while largely preserving the characteristic functional groups of the triblock copolymer. Increasing the laser fluence progressively induces surface restructuring phenomena, including droplets, wrinkles, and the appearance of highly symmetric faceted structures. These entities develop preferentially in samples deposited at elevated fluence and frequently appear only after prolonged aging under ambient conditions, revealing delayed recrystallization behaviour associated with metastable species generated during the deposition process. EDS analyses reveal localized chlorine enrichment within the faceted structures, while FIB-SEM investigations show porous internal morphologies. XRD confirms that the polymer matrix remains predominantly amorphous. The combined observations suggest that UV-MAPLE deposition from chloroform involves not only physical material transfer but also photochemical processes that promote decomposition, recombination, and delayed crystallization phenomena. A phenomenological model describing the successive stages of surface evolution, aging, and recrystallization is proposed. These results provide new insight into the long-term evolution of laser-deposited biodegradable polymer coatings and highlight the importance of solvent selection and processing conditions in determining their stability. Full article

Three-year atmospheric field-exposure tests were conducted on 304 austenitic stainless steel at the Great Wall and Zhongshan Stations in Antarctica to evaluate its corrosion behavior under severe polar conditions. The exposed specimens were dominated by localized corrosion with pronounced pitting characteristics at both sites. Corrosion was more severe at Zhongshan Station, and the mean corrosion rates at Great Wall and Zhongshan Stations were 1.428 and 1.643 μm y⁻¹, respectively. The mean/maximum pit depths were 4.16/5.51 μm at Great Wall Station and 5.85/8.24 μm at Zhongshan Station. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), grazing-incidence X-ray diffraction (GIXRD), and focused ion beam-transmission electron microscopy (FIB-TEM) showed that the corrosion products consisted mainly of β-FeOOH, α-FeOOH, and γ-Fe₂O₃, and the Antarctic exposure substantially altered the thickness, structure, and electrochemical response of the passive film. Compared with the unexposed specimen, the exposed specimens exhibited markedly lower charge-transfer resistance and higher donor density, indicating degradation of the protective passive film. Combined with the site-specific environmental features, the lower temperature, more intense freeze–thaw cycling, freezing-induced concentration of electrolytes, and stronger irradiation at Zhongshan Station are inferred to promote Cl⁻ enrichment in localized surface liquid films and destabilization of the passive film, thereby accelerating pit initiation and growth. These findings provide a mechanistic basis for material selection and corrosion-protection design for 304 stainless steel in polar engineering environments. Full article

Mo–Re alloys serve as critical structural components for high-temperature nuclear reactors, and their irradiation degradation is closely related to the evolution of vacancy-type defects. In this study, heavy-ion and He-ion irradiations were performed under RT to introduce an average displacement damage of 3.5 dpa within the 1 μm-thick surface layer of Mo–Re alloys with Re content up to 47 wt.%. PALS, SPB-DBS and CDB techniques were employed to characterize the size, concentration, depth distribution and local chemical environment of irradiation-induced vacancy-type defects. The results demonstrate that the longer lifetime component of irradiated Mo–Re alloys ranged from 262 to 280 ps, corresponding to medium-sized vacancy clusters. The S parameter of all specimens increased significantly from approximately 0.42 to 0.50, with negligible differences (<0.01) among various Mo–Re alloys. No distinct characteristic peak of Re was observed near 17 × 10⁻³ m₀c at the vacancy sites, which was inconsistent with simulation predictions. Mo–Re alloys exhibit similar vacancy-type defect features to pure Mo, implying weak interactions between Re solute atoms and vacancy-type defects under RT irradiation. Full article

Monolayer and few-layer MoS₂ are promising two-dimensional electronic materials, but proton irradiation can trigger ultrafast electronic excitation and charge transfer before defect formation. Here, real-time time-dependent density functional theory (RT-TDDFT) is used to investigate proton-induced electronic stopping and localized charge capture in monolayer and bilayer MoS₂ under normal incidence. Four impact positions are examined in monolayer MoS₂, namely, the hollow channel, the Mo–S bond center, and two trajectories close to Mo and S atoms. Under hollow channel incidence, the stopping power shows a non-monotonic dependence on proton velocity. When comparing the different trajectories, the hollow channel path gives the lowest stopping power, whereas the Mo–S bond center path gives the highest values, indicating strong sensitivity to the in-plane valence charge distribution. By contrast, the time-averaged localized captured charge decreases with increasing velocity and is generally largest for the close to Mo trajectory. Under the same hollow channel condition, the monolayer stopping power exceeds the bilayer value in the main stopping region, whereas the bilayer generally shows slightly enhanced localized charge capture. These results show that electronic stopping and localized charge capture are distinct but coupled microscopic components of proton-induced electronic response in MoS₂ and provide first-principles insight relevant to ion-beam processing and radiation-tolerant two-dimensional devices. Full article

Organic–inorganic hybrid metal halides (OIMHs), especially zero-dimensional (0D) ones, have been recognized as an excellent class of luminescent materials due to their structural diversity and tunable emission properties. In this work, using the environmentally friendly Zn(II) ion as the central metal and 1,4,7,10-tetraazacyclododecane (Cyclen) as the organic component, we successfully synthesized a novel OIMH, (H₃Cyclen)(ZnBr₄)·Br·H₂O. Single-crystal X-ray diffraction analysis reveals that (H₃Cyclen)(ZnBr₄)·Br·H₂O possesses a 0D structure, in which the [ZnBr₄]²⁻ tetrahedra are uniformly separated by the organic amine cations. This structural feature is expected to enhance the material’s stability and optimize its optoelectronic properties. Under UV lamp irradiation, (H₃Cyclen)(ZnBr₄)·Br·H₂O emits bright blue-green light. Therefore, we systematically investigated its luminescence properties. The emission mechanism was further elucidated using UV–vis absorption spectroscopy and DFT calculations. Finally, (H₃Cyclen)(ZnBr₄)·Br·H₂O was employed as a luminescent material to fabricate a white light-emitting diode (WLED), demonstrating its potential as an excellent phosphor material. Full article