Search Results (128)

Background/Objectives: Previous research demonstrates higher sodium retention with increasing levels of dietary salt in some populations. Our objective was to determine whole-body sodium retention and sodium distribution on high and low salt diets using rodent models. Methods: Whole body retention of orally dosed Na-22, a gamma emitter, was measured in female growing and adult Sprague-Dawley rats on high (3.1% by wt. of diet) and low salt (0.13% by wt. of diet) diets. In a second study, whole-body sodium retention was compared between destructive inductively coupled plasma optical emission spectroscopy (ICP-OES) and neutron activation analysis (NAA) in adult male and female C57BL/6 mice. Results: Whole body retention of Na-22 was not different due to the age of rats on a high salt diet, but rats fed the high salt diet excreted Na-22 much more rapidly than rats fed a low salt diet. In mice, neither sodium retention nor tissue distribution was affected by dietary salt. Bland–Altman analysis indicated overall agreement between NAA and ICP-OES measurements, with observed systematic positive bias. Conclusions: Dietary salt had little effect on retention in normotensive rodents and should be studied in hypertensive models. Full article

Osmium is a third-peak neutron-capture element predominantly produced by the rapid (r-) process, and it is a valuable tracer of early Galactic chemical enrichment. However, osmium abundance measurements in Galactic stars remain limited due to observational challenges. We present new osmium abundances for 23 stars at intermediate metallicities ($-2.5\le$ [Fe/H] $\le -1.0$) within the framework of the MINCE (Measuring at Intermediate Metallicity Neutron-Capture Elements) project. A standard abundance analysis was carried out using one-dimensional LTE model atmospheres and the optical Os I line at 479 nm observed in high-quality UVES spectra. The derived [Os/Fe] ratio exhibits an anticorrelation with [Fe/H], supporting efficient r-process enrichment during the early phases of the Milky Way’s evolution. We also investigated Os abundances across different Galactic components, finding that halo and Gaia–Sausage–Enceladus stars are more Os-rich than thick-disk stars. A comparison between Os and europium abundances supports a common r-process origin for these elements at intermediate metallicities. Full article

Atmospheric aerosols modulate Earth’s radiation balance through direct effects and through their role as cloud condensation nuclei (CCN), contributing to variability in near-surface temperature (NST). Galactic cosmic rays (GCRs) further influence aerosol–cloud interactions by enhancing particle formation and growth, but combined aerosol optical depth (AOD)–GCR effects on NST remain poorly constrained across climates. Using satellite and reanalysis data, we examine joint influences on NST anomalies at three neutron-monitoring stations, Oulu, Newark, and Hermanus, during 2000–2022. The sites share similar geomagnetic cutoffs but contrasting climates, enabling separation of ionization from geomagnetic shielding. Multiple linear regression (MLR) captures AOD effects and their modulation by GCR flux. Adding an interaction term (AOD × GCR) improves fit, raising adjusted R² from 0.22→0.31 (Oulu), 0.37→0.52 (Newark), and 0.69→0.78 (Hermanus). ECMWF reanalysis shows hydrophilic organic matter aerosol (OMA) dominates (0.19, 0.29, 0.41 µg kg⁻¹ at Oulu, Newark and Hermanus), with sulphate elevated at Oulu/Newark and coarse sea salt at Hermanus. Elevated OMA and sulphate at Oulu/Newark imply GCR-enhanced fine CCN and cooling, whereas humid, sea-salt-rich Hermanus favors ion-mediated growth of larger hygroscopic particles that increase longwave trapping and warming. Findings provide site-specific evidence that GCR ionization modulates aerosol processes and contributes to regional NST variability, informing improved parameterizations in climate models. Full article

Superheated liquid detectors (SLDs) exhibit strong sensitivity to fast neutrons and intrinsic insensitivity to gamma radiation, making them promising candidates for detecting shielded nuclear materials in security and non-proliferation applications. This work evaluates the feasibility of octafluoropropane-based superheated droplet detectors (SDDs) for identifying neutron-emitting materials concealed behind common attenuators. A combined acoustic and optical readout system was implemented, including a validated pulse-shape analysis method and a machine-learning-based bubble detection algorithm using YOLOv5. The optical system achieved a detection precision of approximately 80% within the defined region of interest. While the acoustic system remains the primary and more mature detection channel, the optical approach demonstrates feasibility but is not yet operationally ready for field deployment. Experiments with an AmBe neutron source and various shielding materials demonstrate that SDDs reliably detect fast neutrons under realistic inspection conditions while remaining insensitive to gamma radiation. These results support the feasibility of SLD-based systems as low-cost, passive tools for detecting shielded nuclear materials in field environments. Full article

Wavelength-shifting (WLS) materials are used in radiation detectors to convert ultraviolet photons into visible light, enabling improved photon detection in systems such as scintillators and optical diagnostics for nuclear fusion devices. However, the long-term performance of these materials under radiation is still a critical issue in high-dose environments. In this work, we investigated the radiation tolerance of three WLS compounds (TPB, NOL1, and SB2001), each deposited on reflective substrates (ESR and E-PTFE), resulting in six distinct WLS/substrate systems. The samples underwent gamma irradiation at absorbed doses of 100 kGy, 500 kGy, and 1000 kGy, as well as fast neutron (14.1 MeV) irradiation up to a fluence of 1.9 × 10¹³ n/cm². Qualitative photoluminescence and reflectance measurements were performed before and after irradiation to assess changes in optical performance. Gamma exposure caused spectral broadening in several samples, particularly those with TPB and SB2001, with variations of the two metrics used to compare the performance of the materials exceeding 10% at the highest doses. Neutron-induced effects were generally weaker and did not exhibit a clear fluence dependence. Reflectance degradation was also observed, with variations depending on both the WLS material and the deposition method. These findings contribute to the understanding of WLS material stability under radiation and support their qualification for use in optical components exposed to harsh nuclear environments. Full article

Environmentally friendly materials with superior structural, physical, optical, and shielding capabilities are of great technological importance and are continually being investigated. In this work, novel multicomponent borate glasses with the composition xTiO₂-10BaO-5Al₂O₃-5WO₃-20Bi₂O₃-(60-x) B₂O₃, where 0 ≤ x ≤ 15 mol%, were produced via the melt-quenching technique. The increase in TiO₂ content results in a decrease in molar volume and a corresponding increase in density, indicating the formation of a compact, rigid, and mechanically hard glass network. Elastic constant measurements further confirmed this behavior. FTIR analysis confirms the transformation of BO₃ to BO₄ units, signifying improved network polymerization and structural stability. The prepared glasses exhibit an optical absorption edge in the visible region, demonstrating their strong ultraviolet light blocking capability. Incorporation of TiO₂ leads to an increase in refractive index, optical basicity, and polarizability, and a decrease in the optical band gap and metallization number; all of these suggest enhanced electron density and polarizability of the glass matrix. Radiation shielding properties were evaluated using Phy-X/PSD software. The outcomes illustrate that the Mass Attenuation Coefficient (MAC), Effective Atomic Number (Z_eff), Linear Attenuation Coefficient (LAC) increase, while Mean Free Path (MFP) and Half Value Layer (HVL) decrease with increasing TiO₂ at the expense of B₂O₃, confirming superior gamma-ray attenuation capability. Additionally, both TiO₂-doped and undoped samples show higher fast neutron removal cross sections (FNRCS) compared to several commercial glasses and concrete materials. Overall, the incorporation of TiO₂ significantly enhances the optical performance and radiation-shielding efficiency of the environmentally friendly glass system, making these potential candidates for advanced photonic devices and radiation-shielding applications. Full article

The increasing demand for sustainable and multifunctional materials in radiation shielding and optical applications has driven research toward utilizing natural and waste-derived reinforcements in polymer matrices. However, achieving effective attenuation performance across different radiation types using eco-friendly fillers remains a significant challenge. In this study, polyvinyl chloride (PVC)/Polystyrene (PSt) blend composites (1:1 weight ratio) were reinforced with powdered snail shell (SSP) as a biogenic additive, aiming to enhance their shielding and optical performance. Composites containing 5%, 10%, 20%, and 30% SSP (w/v) were fabricated and characterized. Key parameters including linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), mean free path (MFP), half-value layer (HVL), and effective atomic number (Zeff) were measured using a variable-energy X-ray source (13.37–59.54 keV) and ULEGe detector. Fast neutron shielding performance and theoretical values for build-up factor (EBF) and macroscopic neutron cross-sections were also calculated. The results showed a marked improvement in X-ray attenuation with increasing SSP content (SSP30 > SSP20 > SSP10 > SSP5), while neutron shielding declined due to the high oxygen content of SSP. Among the tested samples, the SSP30 composite exhibited the highest X-ray attenuation efficiency, whereas the SSP5 composition showed the greatest enhancement in optical reflectance and neutron absorption, indicating optimal performance in these respective tests. Additionally, 5% SSP incorporation improved optical reflectance by 12%, indicating enhanced photon backscattering at the material surface. This behavior contributes to improved gamma shielding efficiency by reducing photon penetration and enhancing surface-level attenuation. These findings highlight the potential of snail shell-based fillers as low-cost, sustainable reinforcements in multifunctional polymer composites. Full article

The discovery of the fifth gravitational wave, GW170817, and its electromagnetic counterpart, resulting from the merger of neutron stars by the LIGO and Virgo teams, marked a major milestone in astronomy. It was the first time that gravitational waves and light from the same cosmic event were observed simultaneously. The LIGO detectors in the United States recorded the signal for 100 s, longer than in previous detections. The merging of neutron stars emits both gravitational and electromagnetic waves across all frequencies—from radio to gamma rays. However, pinpointing the exact source remains difficult, requiring rapid sky scanning to locate it. To address this challenge, the Gravitational-Wave Optical Transient Observer (GOTO) project was established. It is specifically designed to detect optical light from transient events associated with gravitational waves, enabling faster follow-up observations and a deeper study of these short-lived astronomical phenomena, which appear and disappear quickly in the universe. In astrophysics, it has become more important to find astronomical transient events like supernovae, gamma-ray bursts, and stellar flares because they are linked to extreme cosmic processes. However, finding these short-lived events in huge sky survey datasets, like those from the GOTO project, is very hard for traditional analysis methods. This study suggests a deep learning methodology employing Convolutional Neural Networks (CNNs) to enhance transient classification. CNNs are based on how biological vision systems work and how they are structured. They mimic how animal brains hierarchically process visual information, making it possible to automatically find complex spatial patterns in astronomical images. Transfer learning and fine-tuning on pretrained ImageNet models are utilized to emulate adaptive learning observed in biological organisms, enabling swift adaptation to new tasks with minimal data. Data augmentation methods like rotation, flipping, and noise injection mimic changes in the environment to improve model generalization. Dropout and different batch sizes are used to stop overfitting, which is similar to how biological systems use redundancy and noise tolerance. Ensemble learning strategies, such as Soft Voting and Weighted Voting, draw inspiration from collective intelligence in biological systems, integrating multiple CNN models to enhance decision-making robustness. Our findings indicate that this bio-inspired framework substantially improves the precision and dependability of transient detection, providing a scalable solution for real-time applications in extensive sky surveys such as GOTO. Full article

In the optical band, very few pulsars can be directly detected, but some of the pulsar binary companions can be observed. This study leverages high-precision astrometric data from Gaia Data Release 3 (DR3) to identify pulsar companions in binary systems. Cross-matching the Australia Telescope National Facility (ATNF) Pulsar Catalogue with Gaia DR3 yielded 58 astrometric pairs, including 9 newly confirmed companions—primarily in the southern hemisphere—expanding the known pulsar distribution there. Among newly confirmed companions, eight are redback pulsars, offering insights into millisecond pulsar evolution and companion composition. All 58 companions are classified as main-sequence stars, neutron stars, white dwarfs, or ultra-light companion stars, with ∼40% being spider pulsars. Gaia’s exceptional astrometric precision advances pulsar studies, enabling gravitational wave detection via Pulsar Timing Arrays (PTAs) and improved reference frame link. Future multi-wavelength research will benefit from Gaia DR4, International Pulsar Timing Array (IPTA) collaborations (including Five-hundred-meter Aperture Spherical radio Telescope (FAST)), and Very Long Baseline Interferometry (VLBI) networks like the Chinese VLBI Network (CVN). Full article

Fibre Optics Current Sensor (FOCS) will be used at ITER to perform plasma current measurement during quasi-steady state D-T plasma operation. Effects of the tokamak harsh environment on the FOCS performance must be evaluated to predict possible failure modes and relevant mitigation measures. The influence of nuclear radiation with the significant flux of 14 MeV neutrons is of specific concern. This problem was addressed by operating the FOCS during D-T campaign at JET (DTE2). In the present report experimental results are presented and analysed. These results indicate that FOCS will effectively perform current measurements during ITER nuclear operation. Full article

The vibration properties of materials play a role in their conduction of electric charges. Ionic conductors such as electrodes and solid electrolytes are also relevant in this respect. The vibration properties are typically assessed with infrared and Raman spectroscopy, and inelastic neutron scattering, which all allow for the derivation of the phonon density of states (PDOS) in part of a full portion of the Brioullin zone. Nuclear resonant vibration spectroscopy (NRVS) is a novel method that produces the element-specific PDOS from Mössbauer-active isotopes in a compound. We employed NRVS operando on a pouch cell battery containing a Li⁵⁷FePO₄ electrode, and thus could derive the PDOS of the ⁵⁷Fe in the electrode during charging and discharging. The spectra reveal reversible vibrational changes associated with the two-phase conversion between LiFePO₄ and FePO₄, as well as signatures of metastable intermediate states. We demonstrate how the NRVS data can be used to tune the atomistic simulations to accurately reconstruct the full vibration structures of the battery materials in operando conditions. Unlike optical techniques, NRVS provides bulk-sensitive, element-specific access to the full phonon spectrum under realistic operando conditions. These results establish NRVS as a powerful method to probe lattice dynamics in working batteries and to advance the understanding of ion transport and phase transformation mechanisms in electrode materials. Full article

Among the many nanomaterials studied for biomedical uses, silica and gold nanoparticles have gained significant attention because of their unique physical and chemical properties and their compatibility with living tissues. Mesoporous silica nanoparticles (MSNs) have great stability and a large surface area, while gold nanoparticles (AuNPs) display remarkable optical features. Both types of nanoparticles have been widely researched for their individual roles in drug delivery, imaging, biosensing, and therapy. When combined with gadolinium (Gd), a common contrast agent, these nanostructures provide improved imaging due to gadolinium’s strong paramagnetic properties. This study focuses on incorporating gold nanoparticles and gadolinium into a silica matrix to develop a theranostic system. Various analytical techniques were used to characterize the nanocomposites, including infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA), nitrogen adsorption, scanning electron microscopy (SEM), dynamic light scattering (DLS), X-ray fluorescence (XRF), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), and neutron activation analysis (NAA). Techniques like XRF mapping, XANES, nitrogen adsorption, SEM, and VSM were crucial in confirming the presence of gadolinium and gold within the silica network. VSM and EPR analyses confirmed the attenuation of the saturation magnetization for all nanocomposites. This validates their potential for biomedical applications in diagnostics. Moreover, activating gold nanoparticles in a nuclear reactor generated a promising radioisotope for cancer treatment. These results indicate the potential of using a theranostic nanoplatform that employs mesoporous silica as a carrier, gold nanoparticles for radioisotopes, and gadolinium for imaging purposes. Full article

We provide a beam shape characterization of the VESUVIO spectrometer, at the ISIS Neutron and Muon Source, employing CR-39 solid-state nuclear track detectors and combining techniques including optical and electron microscopy, as well as Monte Carlo transport simulations. In particular, we show, through comparison with irradiation with 14 MeV neutrons at the NILE Facility at ISIS, that the majority of defects on the etched surface of the dosimeters irradiated on VESUVIO were induced by neutrons with energies between 100 keV and 10 MeV. Our results were compared to previous characterizations of the VESUVIO beam shape performed in either the thermal or fast energy ranges, and we conclude that the VESUVIO beam has a constant shape from thermal-neutron energies up to 10 MeV, composed of an umbra (intensity above 90% of the maximum) with radius 1.1 cm, and surrounded by a penumbra (intensity above 1% of the maximum) that extends up to 2.5 cm. Full article

The first detection of gravitational waves from the binary black merger GW150914 started the era of gravitational astronomy. The observation of the binary neutron star merger GW170817 and of its associated electromagnetic counterpart GRB 170817A started multi-messenger gravitational astronomy. This short review discusses the discovery of GW170817 and the follow-up of the electromagnetic counterpart, together with the broad range of results in astrophysics and fundamental physics, including the Gamma-Ray Burst field. The GW170817/GRB 170817A observation showed that binary neutron star mergers can explain at least a fraction of short Gamma-Ray Bursts. The optical and infrared evolution of the associated AT 2017gfo transient showed that binary neutron star mergers are sites of r-process nucleo-synthesis. The combination of gravitational and electromagnetic observations has been used to estimate the Hubble parameter, the speed of gravitational waves, and the equation of state of nuclear matter. The increasing sensitivity of interferometric detectors and the forthcoming operation of third generation detectors will lead to an improved statistics of binary neutron star mergers. Full article

Neutron–antineutron oscillation (nnbar-osc) is a baryon number-violating process and a sensitive probe for physics beyond the standard model. Ultra-cold neutrons (UCNs) are attractive for nnbar-osc searches because of their long storage time, but earlier analyses indicated that phase shifts on wall reflection differ for neutrons and antineutrons, leading to severe decoherence and a loss of sensitivity. Herein, we revisit this problem by numerically solving the time-dependent Schrödinger equation for the two-component n/nbar wave function, explicitly including wall interactions. We show that decoherence can be strongly suppressed by selecting a wall material whose neutron and antineutron optical potentials are nearly equal. Using coherent scattering length data and estimates for antineutrons, we identify a Ni–Al alloy composition that matches the potentials within a few percent while providing a high absolute value, enabling long UCN storage. With such a bottle and an improved UCN source, the sensitivity could reach an oscillation period ${\tau }_{nnbar}$ of the order 10¹⁰ s, covering most of the range predicted with certain grand unified models. This approach revives the feasibility of high-sensitivity nnbar-osc searches using stored UCNs and offers a clear path to probe baryon number violation far beyond existing limits. Full article