Institute of Physics

Abstract Tungsten has demonstrated a competitive figure of merit in its application to plasma-facing components (PFCs) of fusion reactors. During service, the material is exposed to high temperatures and high-level displacement damage. A common interest is fostered in the nuclear materials community to address the issue of defect evolution at operating temperatures, and how they recover throughout service. During maintenance, the application of in situ thermal repair technologies is tempting, featuring attractive efficiency in defect removal via an optimal selection of post-irradiation annealing (PIA) parameters. In previous studies, we examined the role of PIA temperature, PIA duration, and initial defect concentration on defect evolution, and redefined the damage recovery stages for tungsten, but this was done from a room-temperature heavy-ion irradiation perspective; see Wang et al (2023 J. Nucl. Mater. 581 154454), Wang et al (2024 Acta Mater. 273 119942). In this study, the scope is expanded to displacement damage saturation induced by heavy-ions at high temperatures, relevant to the service conditions of tungsten-based PFCs. The damage microstructure evolution in response to varied irradiation temperatures ( T Irr ) and PIA temperatures ( T PIA ) was assessed via transmission electron microscopy and Doppler broadening positron annihilation spectroscopy. Irradiation hardening was evaluated via nano-indentation. A scientific framework is proposed to guide thermal healing of displacement damage in tungsten via PIA treatment. It was ineffective when T PIA ⩽ T Irr . An adverse effect of PIA-induced secondary hardening occurred when T PIA (stage III) > T Irr (stage III). The optimal PIA scheme was confirmed when T PIA (stage IV) > T Irr (stages III–IV), eluding PIA-induced secondary hardening and minimizing PIA-enhanced recrystallization.

Abstract Gold nanoparticles (AuNPs) exhibit unique optical properties due to localized surface plasmon resonance (LSPR), making them valuable for applications in nanophotonics, sensing, and biomedicine. This study investigates the formation of ordered AuNP monolayers on Au/Si(100) substrates with controlled roughness prepared by magnetron sputtering and thermal evaporation. We examine how substrate morphology influences nanoparticle organization and analyze collective optical properties using reflection spectroscopy. Ordered AuNP ensembles were formed at the air/water interface and transferred onto Au/Si(100) substrates. Our results demonstrate that substrate roughness significantly affects monolayer packing density and uniformity. Reflection spectra revealed two characteristic resonances: an LSPR peak at ~525 nm and a low-energy resonance at ~800 nm associated with collective particle-substrate interactions. Significantly, encapsulation with cetyltrimethylammonium chloride (CTAC) molecules suppressed the long-wavelength resonance. Comparative analysis with colloidal AuNP dimers suggests charge-mediated interactions in plasmon resonance formation. These findings demonstrate effective control of collective plasmonic modes through substrate morphology tuning and nanoparticle surface functionalization, offering promising avenues for developing advanced optical materials and sensor platforms.

CeTe3 is a 2-dimensional (2D) Van der Waals (VdW) material with incommensurate charge density waves (CDW), extremely high transition temperature (TCDW), and a large momentum-dependent CDW gap that leaves a significant portion of the Fermi surface intact. It is also considered to be a weak Kondo system, a property unexpected for a material with incommensurate CDW, where each atomic site is slightly different. Here, we study the properties of the CDW state in several RTe3 (R is rare earth) materials and examine the hybridization of itinerant states with the localized Ce 4f multiplet in CeTe3 by using angle resolved photoemission spectroscopy. We find that the renormalization of the itinerant states originating from the hybridization with the deeper localized 4f states at −260 meV is k−dependent and extends to the Fermi level. As these localized states are far from the Fermi level, the observed hybridization affects the effective masses only marginally and does not lead to heavy fermions. However, since the same renormalizing mechanism normally leads to the heavy fermion physics when the localized 4f states are near the Fermi level, our observation of its strong k−dependence suggests that this could be the reason for discrepancy between the heavy masses in specific heat and light ones in Shubnikov de Haas oscillations, often observed in heavy fermions.

This paper outlines a simple theoretical argument for the possibility of a quantum linear Voigt effect at low temperatures in certain media in the optical regime. An unlikely starting point for the ensuing argument arises out of a long-established hydrodynamic Lorentz field-modified classical dispersion theory whose Voigt component of the optical conductivity, when subjected to the Uncertainty Principle, results in a modified form in the quantum region. In contrast to its classical, second-order counterpart, this quantum Voigt conductivity is shown to have a (modular) linear field dependence.

Non-invasive oximetry is crucial for the easy and continuous monitoring of blood oxygenation, from routine assessments to critical care in intensive care units (ICU). Studies indicate that pulse oximeter readings may be biased due to the high light absorption of melanin. This study aims to analyse the agreement among three different pulse oximeters and their concordance with arterial blood gas measurements in ICU patients and verify how accuracy varies with age and skin pigmentation. We conducted a prospective cross-sectional observational study with a population of intensive care patients. Blood oxygen saturation was measured simultaneously by pulse oximetry and arterial blood gas analysis. Skin pigmentation was objectively assessed at two anatomical sites using calibrated colorimeters and quantified by the individual typology angle (ITA°). Among 100 ICU patients (SaO2 85%-100%), two of the three oximeters exceeded the 3% accuracy root mean square (ARMS) 2013 FDA threshold, whereas one device remained within limits (2.91%). Agreement with arterial oxygen saturation was weak (CCC = 0.34-0.46) and lower SaO2 was associated with overestimation increase (0.31%-0.54% for every 1% SaO2 decrease). Multivariable models showed no evidence of association between ITA° and SpO2 error (p > 0.05). In contrast, older age predicted greater overestimation (β range = 0.05%-0.06% per year; 95% CI range = 0.02-0.09; all p ≤ 0.05). Although estimates suggested small pigmentation effects, analysis indicated these were indistinguishable from random error. In contrast, physiological factors such as lower SaO2 and older age were consistently associated with greater oximeter error. Substantial clinical variability limits detection of small biases, underscoring the need for improved calibration and validation using objective skin-tone assessment. In intensive care, where continuous monitoring is essential, pulse oximeter error was more strongly related to physiological factors, such as arterial oxygen saturation and age, than to skin tone. These findings support cautious interpretation of SpO2 values and appropriate device selection to ensure accurate assessment across diverse populations.

Abstract We consider a two-dimensional discontinuous piecewise linear homogeneous map in two partitions, belonging to the family of Belykh maps, whose characteristic property is that the Jacobian determinant is the same at any point of the phase plane. The fixed points of the functions defining the map have disjoint stability regions. Three kinds of discontinuity sets separating these partitions are considered. As shown in our previous works, discontinuous piecewise linear homogenous maps can have weird quasiperiodic attractors (WQAs). We prove that there are parameter regions where the existence of WQAs is generic. Owing to the complex shape of a WQA, it may appear similar to a chaotic attractor. However, a WQA does not contain any cycle or other invariant subsets, being the closure of quasiperiodic trajectories. We present examples of contact bifurcations of coexisting WQAs with their basin boundaries leading to a unique WQA, showing that these bifurcations are not associated with homoclinic/heteroclinic trajectories. We discuss also contact bifurcations leading to the divergence that may be accompanied by a long transient following the former attractor. The simplicity of the map allows us to describe the mechanism of the appearance/disappearance of WQAs, always related to the unstable eigenvector of the fixed point.