Search Results (303)

It was demonstrated that various defects can be induced in halide crystals by irradiation with swift heavy ions. Here, we irradiated barium fluoride (BaF₂) single crystals with 220 MeV xenon ions at room temperature and performed stepwise thermal annealing up to the temperature of 825 K to study the kinetics of ion-induced defects at different temperatures. Optical spectroscopy was utilized for the measurement of the wide range of absorption spectra from NIR to VUV. A sharp decrease in the F₂ absorption peak was observed for the samples annealed in the temperature range of 400–450 K. This result can be explained by their recombination with anion interstitials during thermal decay of the complex hole centers. The mobile interstitials, those did not recombine with the F₂ centers, increase the absorption peaks in the 9–10 eV region, which can be associated with interstitial aggregates. Full article

Background: The iliotibial band (ITB) is an anatomically complex structure with multiple proximal and distal attachments, making its mechanical behavior difficult to interpret. In the study of iliotibial band syndrome (ITBS), prior research has often considered the underlying lateral femoral epicondyle (LFE) as a fixed reference to describe ITB movement during knee flexion, potentially misrepresenting true tissue dynamics. This proof-of-concept study introduces the musculoskeletal advanced transillumination technique (MATT) to visualize and measure LFE displacement relative to the ITB and the tubercule of the ITB (tITB) on the tibia during passive knee flexion. Methods: Un-embalmed donor knees (n = 8) were dissected to expose the ITB and positioned on a device allowing standardized passive motion from 0° to 30°. A trocar was inserted between the femoral epicondyles, and a 300-watt xenon light source illuminated the LFE. Video was recorded with an iPhone 15, and key frames were analyzed using ImageJ Version 1.54i, and a custom Python (Version 3.12.5) script to quantify LFE displacement relative to the ITB and to the tITB. Results: Median absolute LFE displacement from 0° to 30° was 9.18 mm (IQR 7.23–10.95). Between 0° and 30°, the LFE shifted anteriorly by −1.76 mm (IQR −10.28 to −8.72) relative to the anterior border of the ITB, and by 11.26 mm (IQR 8.27 to 26.33) relative to its posterior border. The LFE-tITB distance increased from 51.98 mm (IQR 49.13–52.36) at 0° to 53.66 mm (IQR 50.08–60.11) at 30°, with a median displacement of 3.92 mm (IQR: 2.48–5.73). Conclusions: Musculoskeletal Advance Transillumination Technique (MATT) is a straightforward and reproducible technique that offers direct visualization of the dynamic relationship between a skeletal landmark and myofascial structures, such as the LFE and the ITB. By challenging the assumption that the LFE is a fixed reference point, MATT opens new perspectives for investigating the biomechanical mechanisms underlying conditions like iliotibial band syndrome. Full article

Very low Earth orbit (VLEO) satellites are confronted with the challenge of orbital decay caused by thin atmospheres, and the volume and power limitations of micro satellites further restrict the application of traditional electric propulsion systems. In response to the above requirements, this study proposes an innovative scheme of radio frequency plasma micro-thrusters based on magnetic nozzle acceleration technology. By optimizing the magnetic nozzle configuration through the system, the plasma confinement efficiency was significantly enhanced. Combined with the mixed working medium (5 sccm Xe + 10 sccm air), the thrust reached 1.7 mN at a power of 130 W. Experiments show that the configuration of the magnetic nozzle directly affects the plasma beam morphology and ionization efficiency, and a multi-magnet layout can form a stable trumpet-shaped plume. The air in the mixed working medium has a linear relationship with the thrust gain (60 μN/sccm), but xenon gas is required as a “seed” to maintain the discharge stability. The optimized magnetic nozzle enables the thruster to achieve both high thrust density (13.1 μN/W) and working medium adaptability at a power level of hundreds of watts. This research provides a low-cost and miniaturized propulsion solution for very low Earth orbit satellites. Its magnetic nozzle-hybrid propellant collaborative mechanism holds significant engineering significance for the development of air-aspirating electric propulsion technology. Full article

Thermal insulation materials used in power and industrial systems must maintain high performance under extreme environmental conditions. Among such materials, aerogel and basalt fiber are widely applied due to their low thermal conductivity and ease of installation. However, over time, these materials are susceptible to degradation, which can significantly impair their insulating efficiency and increase energy losses. Despite their importance, the long-term behavior of these materials under realistic climatic stressors has not been analyzed enough. This study investigates the degradation of thermal insulation performance in aerogel and basalt fiber materials subjected to complex atmospheric stressors, simulating long-term outdoor exposure. Aerogel and basalt fiber mats were tested under accelerated aging conditions using an artificial weather chamber equipped with xenon lamps to replicate full-spectrum solar radiation, high humidity, and elevated temperatures. The results show that the thermal conductivity of aerogel remained stable, indicating excellent durability under environmental stress. In contrast, basalt fiber insulation exhibited a deterioration in thermal performance, with a 9–11% increase in thermal conductivity, corresponding to reduced thermal resistance. Computational modeling using COMSOL Multiphysics confirmed that aerogel insulation outperforms basalt fiber, especially at temperatures exceeding 200 °C, offering better heat retention with thinner layers. These findings suggest aerogel-based materials are more suitable for long-term thermal insulation of high-temperature pipelines and industrial equipment. Full article

It has long been accepted that breathing gases that are physiologically inert include helium (He), neon (Ne), nitrogen (N₂), argon (Ar), krypton (Kr), xenon (Xe), and hydrogen (H₂). The term “inert gas” has been used to describe them due to their unusually high chemical stability. However, as investigations have advanced, many have shown that inert gas can have specific biological impacts when exposed to high pressure or atmospheric pressure. Additionally, different inert gases have different effects on intracellular signal transduction, ion channels, and cell membrane receptors, which are linked to their anesthetic and cell protection effects in normal or pathological processes. Through a selective analysis of the representative literature, this study offers a concise overview of the state of research on the biological impacts of inert gas and their molecular mechanisms. Full article

Accurate evaluation of the thermal conductivity of UO₂ with defects is very significant for optimizing fuel performance and enhancing the safety design of reactors. We employed a method that combines the Boltzmann transport equation with DFT+U to calculate the thermal conductivity of UO₂ containing fission products and irradiation-induced point defects. Our investigation reveals that the thermal conductivity of UO₂ is influenced by defect concentration, defect type, and temperature. Fission products and irradiation defects result in a decrease in thermal conductivity, but they have markedly different impacts on phonon scattering mechanisms. Metal cations tend to scatter low-frequency phonons (less than 5.8 THz), while the fission gas xenon scatters both low-frequency and high-frequency phonons (greater than 5.8 THz), depending on its occupancy at lattice sites. Uranium vacancies scatter low-frequency phonons, while oxygen vacancies scatter high-frequency phonons. When uranium and oxygen vacancies coexist, they scatter phonons across the entire frequency spectrum, which further results in a significant reduction in the thermal conductivity of UO₂. Our calculated results align well with experimental data across a wide temperature range and provide fundamental insights into the heat transfer mechanisms in irradiated UO₂. These findings are essential for establishing a thermal conductivity database for UO₂ under various irradiation conditions and benefit the development of advanced high-performance UO₂ fuel. Full article

The assessment of the efficacy of antiseizure medications (ASMs) in animal models of acute seizures has played a critical role in these drugs’ success in clinical trials for human epilepsy. One of the most widely used animal models for this purpose is the maximal electroshock seizure (MES) model. While there are numerous published reports on the efficacy of conventional ASMs in MES models, there is a need to expand the understanding on the brain concentrations that are needed to achieve optimal levels of efficacy in this model. We assessed the pharmacokinetic/pharmacodynamic (PK/PD) profiles of six ASMs, namely carbamazepine (CBZ), phenytoin (PHT), valproic acid (VPA), lacosamide (LSM), cenobamate (CNB), and retigabine (RTG), using MES models in mice and rats. EC₅₀ values for plasma and the brain were generally higher in mice than rats, with fold differences ranging from 1.3- to 8.6-fold for plasma and from 1.2- to 11.5-fold for brain. Phenytoin showed the largest interspecies divergence. These results suggest that rats may exhibit greater sensitivity to seizure protection in the MES model, likely reflecting species differences in metabolism and brain penetration. These findings highlight the value of considering concentration–response variations and species-specific differences when assessing the efficacy of both conventional ASMs and novel compounds exhibiting anticonvulsant activity. Full article

With the advancement in deep-space exploration, the injection technology using xenon as a working fluid in electric propulsion systems has emerged as a key area of interest. To delve into the gas-liquid dynamics of the liquid xenon injection process and the influence of gravity on this mechanism, this investigation employs a VOF two-phase flow model coupled with the Lee model to elucidate the characteristics of the two-phase flow during microgravity conditions. The findings uncover that in the absence of gravitational forces, gas-liquid stratification does not occur during the filling process. Consequently, this leads to an even distribution of gas and liquid within the tank, which in turn prolongs the filling duration in orbiting scenarios. Full article

The recovery of radiation damage induced by 231-MeV xenon ions with varying fluence (from 5 × 10¹¹ to 2 × 10¹⁴ cm⁻²) in α-Al₂O₃ (corundum) single crystals has been studied by means of isochronal thermal annealing of radiation-induced optical absorption (RIOA). The integral of elementary Gaussians (product of RIOA spectrum decomposition) OK has been considered as a concentration measure of relevant oxygen-related Frenkel defects (neutral and charged interstitial-vacancy pairs, F-H, F⁺-H⁻). The annealing kinetics of these four ion-induced point lattice defects has been modelled in terms of diffusion-controlled bimolecular recombination reactions and compared with those carried out earlier for the case of corundum irradiation by fast neutrons. The changes in the parameters of interstitial (mobile component in the recombination process) annealing kinetics—activation energy E and pre-exponential factor X—in ion-irradiated crystals are considered. Full article

Due to its excellent visible light absorption characteristics, the photocurrent, photodegradation, and proton conductivity of the stable dipyridyl and thiophene-functionalized supramolecular compound [Cu₂(TAA)₄(4,4′-bpy)]_n (Cu^II₂ for short, HTAA = 2-thiopheneacetic acid, 4,4′-bpy = 4,4′-bipyridine) have been studied in detail. The current density of photocurrent of Cu^II₂ is 1.87 μA·cm⁻², and Cu^II₂ degrades methylene blue (MB) with a degradation efficiency of 68.0% under xenon lamp. In addition, Cu^II₂ shows remarkable proton conductivity of 1.79 × 10⁻³ S·cm⁻¹ (at 75 °C and 98% relative humidity), superior to most copper(II)-based coordination polymers (CPs), and is expected to become a potential proton conductor in the future. Full article

To investigate the phenomenon of liquid xenon flashing in a filling pipeline, the two-phase flow in a pipe is calculated and analyzed by using a one-dimensional homogeneous equilibrium model (HEM) and a two-dimensional mixture model. The distribution of xenon two-phase flow parameters along the pipeline is observed by the numerical solution of a one-dimensional HEM and simulation by Fluent. The comparison and analysis of the results of different models show that the one-dimensional HEM can quickly attach the critical mass flux faster than Fluent’s simulation under the given filling conditions, which verifies the rationality and rapidity of the numerical solution in calculating the flash process. The influence of the diameter and length of the pipeline on the flashing process of liquid xenon is analyzed by a one-dimensional theoretical model. The results show that the geometric parameters of the pipeline have a great impact on the mass flow rate and the position of the initial phase transition point, but have little effect on the void fraction at the outlet. An increase in pipe diameter and pipeline length delays the onset of phase transition. Compared with liquid oxygen and liquid nitrogen, liquid xenon is more likely to undergo a phase transition. The phase change kinetics of oxygen and nitrogen are roughly 70% as fast as those of xenon. Full article

Methodologies to measure motion perception are vital for deepening our understanding of the vision system and the factors that influence it. While existing work has primarily focused on the fastest perceivable velocities, less attention has been paid to the lower threshold of motion (LTM; slowest perceivable velocities). In this study, we designed an optical system to measure LTM in a sample of healthy young adults and to assess the influence of retinal location (central vs. peripheral retina) and stimulus composition (broadband vs. mid-wave) on LTM. The system was based on a xenon light source and a fiber-optic cable that created a bright light stimulus that could be moved along a computer-controlled precision translation slide. The stimulus, exposed for one-second intervals at both a central (fovea) and a peripheral (33 deg) location, was moved at varying speeds to determine the slowest detectable speed. In all, 37 healthy young participants (M = 19.32 ± 1.97 years) were tested. We found substantial between-subject variability in LTM and an interaction between stimulus wavelength and retinal location. The measurement of LTM using this novel apparatus and methodology provides insights into the relationship between slow-moving, ecologically valid stimuli and perceptual detection at the slowest speeds. Full article

Ternary g-C₃N₄/CQD/Ag photocatalysts were synthesized via deposition of carbon quantum dots (CQDs) and silver nanoparticles (Ag) onto graphitic carbon nitride (g-C₃N₄) for efficient acetaminophen degradation. The nanocomposites exhibited enhanced photoresponse and broad-spectrum photocatalytic activity under both UV (254 nm, 250 W) and Xenon (>420 nm, 500 W) irradiation. Characterization by XRD, FTIR, SEM, PL, and EDX elucidated the material’s composition, structure, morphology, and optical properties. Optimized photocatalytic degradation of acetaminophen (50 mg/L) was achieved at pH 7 with 0.6 g/L catalyst loading and 60 min irradiation, yielding degradation efficiencies of 87.5% (UV) and 85.3% (Xenon). Radical quenching experiments and GC-MS analysis identified hydroxyl radicals as the primary reactive species and revealed a gradual decrease in intermediate toxicity during mineralization. This study demonstrates the superior photocatalytic performance of the ternary g-C₃N₄/CQD/Ag nanocomposites compared to binary systems for effective acetaminophen removal. Full article

The interaction of microplastics (MPs) with organic micropollutants, such as antibiotics, facilitates their transport in aquatic environments, increasing mobility and toxicological risk. The diverse polymer types, sizes, and shapes in wastewater present a challenge in understanding the fate of persistent organic micropollutants. This study examines ceftazidime adsorption on five polymer types—polyethylene terephthalate (PET), polyethylene (PE), hard and soft polystyrene (PS), hard and soft polyurethane (PU), and tyre wear particles (TWPs, including three passenger tyres and one truck tyre) in various forms (fibres, beads, foam, and fragments) and sizes (10–1000 µm). MPs underwent weathering (alkaline hydrolysis, UVC-activated H₂O₂, and Xenon lamp irradiation) to simulate environmental conditions. Their physical and chemical changes were analysed through mass loss, carbonyl index, scanning electron microscopy, and atomic force microscopy. The adsorption values (mg g⁻¹) for pristine and weathered MPs, respectively, were as follows: PET (0.664 and 1.432), PE (0.210 and 0.234), hard PS (0.17 and 0.24), soft PS (0.53 and 0.48), hard PU (0.19), soft PU (0.17), and passenger TWPs—Bridgestone (0.212), Michelin (0.273), Goodyear (0.288), and Kumho truck TWPs (0.495). The highest and lowest adsorption were observed in weathered PET (1.432 mg g⁻¹) and pristine hard PS/soft PU (0.17 mg g⁻¹), respectively. Sorption kinetics and isothermal models showed that aged MPs exhibited higher sorption due to surface cracks, fragmentation, and increased adsorption sites. These findings enhance scientific knowledge of MP–antibiotic interactions in wastewater and can underpin studies to mitigate MP pollution and their adverse effects on the environment and humans. Full article

Expanded thermoplastic polyurethane (ETPU) is used in a wide range of applications due to its excellent properties, but inevitably, aging deteriorates the material properties and shortens service lifetime. This study conducted aging experiments on ETPU to summarize the deterioration trend and provide reliable data. The ETPU underwent three distinct aging protocols: thermal aging for 28 days in a controlled 80 °C environment; xenon lamp aging under continuous UV irradiation (via xenon lamp) at 80 °C for 28 days; and weathering aging through 671 days of outdoor exposure to real-world weather conditions. After various structural characterization and performance tests on the aged ETPUs, the results showed that thermal aging is not the key factor causing the aging of ETPU; the internal structure of ETPU is damaged and the performance rapidly deteriorates under the combined effect of light, heat, and humidity. The special heterogeneous structure gives the sample different internal aging characteristics, and the bead interface becomes a defective site after aging, affecting the overall mechanical properties of the material. In the natural state, the lifetime of ETPU is about two years. Our work will provide valuable data for the study of the aging properties of ETPU and contribute to the prediction of the lifetime of the material. Full article