Browse Articles

MALDI-TOF mass spectrometry imaging of sulfatide lipid expression in the CNS of mice with experimental autoimmune encephalomyelitis

Mechanics of pore array collapse and interaction in shock-compressed polymethyl methacrylate (PMMA)

Recent studies on dynamic pore collapse have revealed significant development of shear localization, which can lead to material failure in porous structures and hot spot generation in energetic materials. These findings have dramatically improved the understanding of failure mechanisms during pore collapse but also prompt further investigation of realistic porous materials. In particular, porous media consist of many pores and porous networks. Even in low-porosity materials, pores can form in close proximity during the manufacturing process, leading to the critical question of pore–pore interaction during collapse under dynamic loading conditions. This study investigates, via plate impact experiments coupled with high-speed internal digital image correlation and shadowgraphy techniques, the collapse of two pores in shock-compressed PMMA at stresses between 0.4 and 1 GPa. The results of these experiments provide new insights into shear localization in pore collapse, in addition to distinct interactions between pores. Shadowgraphy measurements reveal novel, direct visualization of shear band development and crack evolution from pore surfaces. Spacing between adiabatic shear bands is measured over a range of impact stresses and is predicted accurately by the Grady–Kipp model. Pore interactions are found to effect a transition in the impact stress threshold at which different failure mechanisms initiate and are also found to possibly influence preferential sites for shear cracking. Throughout the study, numerical and theoretical models are leveraged to understand shear localization behavior. The role of baroclinicity and wave interactions between the pores is used to elucidate interaction mechanisms between pores.

Computation of sentence similarity score through hybrid deep learning with a special focus on negation sentence

Length-dependent electron–phonon nonequilibrium thermal resistance in metal–insulator superlattices

When heat flows across a metal–insulator interface, it must be transferred between electrons and phonons at a certain length scale that depends on the electron–phonon coupling characteristics. This nonequilibrium between electrons and phonons gives rise to thermal resistance, in addition to the native resistance owing to interface scattering. The electron–phonon nonequilibrium effect on heat conduction can become particularly significant in nanostructures with distances between metal and insulator interfaces smaller than or comparable to the nonequilibrium length scale. A metal–insulator superlattice is an ideal structure for magnifying and investigating the electron–phonon nonequilibrium effect because the interface distance can be tuned at the nanoscale. In this study, the thermal conductivities of metal–MgO superlattices were measured using the time-domain thermoreflectance (TDTR) method and analyzed using a two-temperature model (TTM). Two types of superlattices with different metals, gold silicon (AuSi) and tantalum (Ta), with relatively weak and strong electron–phonon coupling, respectively, were adopted, and the metal layer thickness was varied from 3 to 15 nm while maintaining a constant total interface density. Consequently, the thermal conductivity of the AuSi–MgO superlattice significantly decreased with increasing metal layer thickness, whereas that of Ta–MgO remained invariant, reflecting the stronger electron–phonon nonequilibrium effect in the former weaker coupling case. Fitting the measurement results with the TTM quantifies the thermal resistance owing to the electron–phonon nonequilibrium effect and its length scale.

A BIM-simulated annealing approach to optimize cost, size, and environmental impact of building water networks

Enabling the growth of thick, relaxed AlGaN films on bulk GaN substrates

Epitaxial growth of thick, relaxed, homogeneous, and crack-free AlGaN films was demonstrated on single-crystalline GaN substrates. A maskless heteroepitaxial facet-controlled epitaxial lateral overgrowth (FACELO) scheme was developed to relax the lattice mismatch-induced tensile stress via the generation and glide of misfit dislocations at the pyramidal heterointerfaces. Up to 10 μm-thick AlGaN films were demonstrated, which was more than three orders of magnitude beyond the critical thickness for cracking. The expected relaxation mechanism was confirmed by the observation of misfit dislocations at the heterointerfaces via transmission electron microscopy. The developed growth scheme is amenable to the growth of thick, homogeneous, relaxed AlGaN films of any composition on native substrates.

Research on dynamic stiffness match form of indirect fastener based on rail high-frequency wear characteristics

Atomistic mechanisms of helium–dislocation loop interactions in molybdenum: Insights from a machine-learning moment tensor potential

Molybdenum (Mo) is a key structural material for advanced nuclear systems, yet under irradiation, the formation of helium (He) bubbles and dislocation loops leads to severe degradation. Understanding He–dislocation loop interactions at the atomic scale is essential for predicting long-term performance. In this work, we develop a machine-learning Moment Tensor Potential and perform molecular dynamics simulations to systematically study the interactions between He atoms and the primary interstitial-type dislocation loops (1/2 ⟨111⟩ and ⟨100⟩) in BCC Mo. Our results show that dislocation loops act as strong trapping sites for He, modifying its spatial distribution and promoting heterogeneous nucleation of He clusters, with the ⟨100⟩ loop having a stronger effect. Conversely, He enhances loop growth by absorbing self-interstitial atoms, a process that intensifies with He concentration. A pronounced pinning effect of He on loop glide is observed, effectively immobilizing loops at 600 and 1200 K, though thermal activation at 1800 K partially releases this pinning. This study elucidates the mutual enhancement mechanism between He and dislocation loops, offering fundamental insights for designing radiation-resistant Mo alloys.

Ecosystem structure influences human health outcomes as the basis for green prescriptions

Thermodynamic and structural evolution of lithium–oxygen–deuterium systems across fusion-relevant temperature and composition ranges

We have investigated the thermodynamic, structural, and transport properties of lithium–oxygen (Li–O) and lithium–oxygen–deuterium (Li–O–D) systems using molecular dynamics over a temperature range of 100–1500 K. Rapid quenching yields glassy and amorphous phases, enabling comparisons with liquid and crystalline states. Deuterium addition suppresses crystallization and enhances hydrogen mobility, especially in non-stoichiometric regimes. For the Li2O stoichiometry, structural metrics and diffusivity trends are benchmarked against available ab initio and experimental data. For other Li–O compositions, no ab initio molecular dynamics or experimental data exist for amorphous or molten states; the only exception is the binary Li–D system, which serves as a limiting case of the ternary Li–O–D mixture. These results provide insight into hydrogen isotope behavior, structural frustration, and phase stability in fusion-relevant lithium-based materials.

Effectiveness of endovenous ablation techniques and surgery for great saphenous vein incompetence: a comprehensive meta-analysis of randomized controlled trials

Unintentional doping and native defects in the AlGaAsSb barrier of <i>nBn</i> photodetectors and their effect on detector dark current

The unintentional p-type doping concentration in the AlGaAsSb barrier of typical mid-wave infrared nBn detectors is predicted by TCAD simulations to generate substantial depletion volume, and consequently, depletion current magnitudes exceeding the diffusion current component. However, diffusion-limited performance of conventional, barrier-on-absorber nBn detectors is routinely achieved. In contrast, investigation into an inverted, absorber-on-barrier nBn structure reveals depletion currents in line with TCAD expectations. To further investigate this phenomenon, devices from an ostensibly fully symmetric nBn structure with equal absorber thicknesses on either side of the barrier are grown, fabricated, and characterized with dark current and capacitance measurements to probe both volumes from the same device. The symmetric nBn, when biased such that carrier collection occurs across the barrier-on-absorber interface (as is the case in the conventional device structure), exhibits diffusion-limited dark current. Similarly, when biased such that carrier collection occurs across the absorber-on-barrier interface (as is the case in the inverted device structure), the device exhibits depletion-limited dark current. Capacitance voltage profiles provide experimental validation of the equivalent doping of each absorber volume; however, a peak capacitance occurring at negative bias similarly reflects the asymmetry in the structure. Secondary ion mass spectrometry and scanning transmission electron microscopy are used to investigate the physical origins of this barrier asymmetry, in which a high O concentration is found at the upper barrier interface while a layer of AlAs-like material is seen at the bottom interface. The implementation of these interface defects into TCAD simulations enables accurate modeling of the observed electrical behavior.

Whole exome sequencing and 12-SNP LDL polygenic score in South Indian patients with familial hypercholesterolemia

Extrinsic and intrinsic nonradiative recombination channels in deep ultraviolet ( <i>λ</i>  &amp;lt; 230 nm) light emitting heterostructures made of group III element nitrides

The optical performance of nitride-based heterostructures that spontaneously emit light in the deep-ultraviolet range (wavelengths below 230 nm) is limited by various previously elucidated phenomena related to the details of the valence band structure, the need to resolve various technological issues with a view to improving electrical injection, and the need to address light extraction issues. In this article, we compare the light–matter interaction strategy in high-quality multiple quantum wells developed by both molecular beam epitaxy and organometallic vapor phase epitaxy, using temperature-dependent photoluminescence measurements performed in the range 8–300 K. The deterioration of light emission between 8 and 300 K is governed by two recombination mechanisms operating at low temperatures (below approximately 100 K) and at higher temperatures, respectively. The efficiency of the non-radiative recombination channel at low temperatures is extrinsic in origin; it is mediated by impurities and by the density of defects in the crystal. The second process is intrinsic in nature and is related to the thermal ionization of excitons at higher temperatures. We believe that the ultimate solution to partially reduce these phenomena could be homoepitaxy on high-quality AlN substrates.

Pyrogallol B-ring enhances catechin binding to the SARS-CoV-2 spike receptor-binding domain to inhibit interaction with ACE2

Abstract Severe acute respiratory syndrome coronavirus 2 infects host cells through binding of the spike protein receptor-binding domain (RBD) to the human angiotensin-converting enzyme 2 receptor. In this study, the antiviral activity of 14 catechin derivatives was evaluated using a pseudovirus assay that emulates spike-mediated cell fusion. Of these, gallocatechin gallate, epigallocatechin gallate, epigallocatechin 3-(3″-O-methyl) gallate, and epigallocatechin exhibit strong inhibitory effects on infection. A structural comparison of the compounds revealed that catechins with a pyrogallol-type B-ring configuration exhibited greater inhibitory effects than their catechol-type counterparts. Docking simulations demonstrated that the hydroxyl group at the 5-position of the B-ring forms a hydrogen bond with Gln493 on the spike RBD, thereby facilitating additional stabilizing interactions with adjacent residues, such as Tyr453. Although catechin bioavailability is low, the results of this study suggest that regular consumption or gargling may offer localized antiviral activity at mucosal surfaces, such as those found in the oral or nasal cavity, because the catechin concentrations used in the cell assays are similar to those observed in green tea (100 µM). This study underscores the potential of pyrogallol-type catechins to act as antiviral agents.

An analytic decomposition approach to modeling evanescent transient plane waves with an illustrative application to acoustics at a fluid–fluid interface

This work introduces an analytic decomposition approach for transient plane waves, broadly applicable to their interaction with layered media in linear physics. The time-domain signal, assumed to be analytic, is extended into the complex plane and then analytically decomposed into two parts, in a manner reminiscent of the Wiener–Hopf technique. The method directly provides the Hilbert transform of the signal and the expressions of the complex fields without resorting to Fourier transforms or the calculation of singular integrals. It applies to a wide class of functions capable of simulating most realistic signals, such as multi-frequency oscillatory signals of limited duration, and is particularly relevant whenever certain fields become evanescent. An illustrative application to acoustics at a fluid–fluid interface offers deeper physical insight than previously available, particularly regarding the processes that generate precursor and successor phenomena in the reflected and transmitted fields, taking advantage of both the simplicity and the effectiveness of the method.

A bio-polymeric strategy for enhancing the strength, durability of concrete and shrinkage reduction

Cu–Au alloy Schottky junction photodetectors on silicon for sub-bandgap near-infrared detection

Internal photoemission-based plasmonic Schottky diodes fabricated on silicon are promising candidates for near-infrared (NIR) photodetection, particularly for detecting sub-bandgap light beyond silicon’s 1.1 eV threshold. Copper (Cu) offers a cost-effective option but is limited by weak plasmonic performance and susceptibility to oxidation. This study examined the characteristics of CuXAu1−X thin films and investigated the CuXAu1−X/n-Si/Al Schottky photodiodes to enhance Cu NIR detection capabilities. Sequential pulsed laser deposition was employed to prepare alloy films, and x-ray photoelectron spectroscopy and energy-dispersive x-ray spectroscopy were used to analyze the film composition. The efficiency of hot-electron production was greatly enhanced by Au alloying, while pure Cu films showed substantial NIR absorption but poor plasmonic quality parameters. The Schottky barrier height of 0.65 eV for Cu/n-Si and 0.73 eV for Au/n-Si junctions was calculated using the dark I–V measurement. The highest responsivity values recorded were 42.31 mA/W at 1300 nm and 3.65 mA/W at 1550 nm, which surpasses previously reported values for similar devices. A maximum specific detectivity of 6.45 × 1011 Jones was achieved, showing potential for weak light detection. These results show that Cu–Au alloying can improve the optical and electrical properties of Cu in a cost-effective manner. This work presents a new direction to make advanced, low-cost NIR photodetectors.

A comprehensive nationwide registry study of noncommunicable disease comorbidities and death in cancer patients in Norway—the NCDNOR project

Abstract Noncommunicable disease (NCD) comorbidities are common in cancer patients due to shared risk factors, but few studies have mapped their occurrence across cancer types using detailed national data. In this nationwide cohort study, we used data from Norwegian mandatory health registries to comprehensively describe NCD comorbidities at and after cancer diagnosis of 19 cancers. We included 269,956 adults registered with a first cancer in the Cancer Registry of Norway 2009–2019. Comorbidities included second cancers, cardiovascular diseases (CVDs), chronic obstructive pulmonary disease, diabetes and mental health disorders (MDs). We used intersection diagrams to examine NCD comorbidity patterns at first cancer diagnosis, and multi-state models to estimate five-year post-cancer probabilities of NCD comorbidities and death. We also provide a publicly available online application [ https://ncdapp.onrender.com/ ] with additional results and details. Comorbidity prevalence at cancer diagnosis ranged from 35% (skin cancer) to 83% (lung cancer). CVD was most prevalent, usually co-occurring with MDs or diabetes. Lowest prevalences were found for younger patients and women. Conditioning on surviving five years, comorbidity probability exceeded 50% in all sites. Our findings show substantial comorbidity burden in cancer patients, varying by cancer site, age, and sex. Knowledge of these patterns could improve NCD prevention, treatment and surveillance.

Tutorial: Membrane phononic integrated circuits

Phononic circuits constructed from high tensile stress membranes offer a range of desirable features such as high acoustic confinement, controllable nonlinearities, low mass, compact footprint, and ease of fabrication. This Tutorial presents a systematic approach to modelling and designing phononic integrated circuits on this platform, beginning with acoustic confinement, wave propagation and dispersion, mechanical and actuation nonlinearities, as well as resonator dynamics. By adapting coupled mode theory from optoelectronics to suspended membranes and validating this theory with several numerical techniques (finite element modelling, finite difference time domain simulations, and the transfer matrix method), we provide a comprehensive framework to engineer a broad variety of phononic circuit building blocks. As illustrative examples, we describe the implementation of several acoustic circuit elements including resonant and non-resonant variable-ratio power splitters, mode converters, mode (de)multiplexers, and in-line Fabry–Pérot cavities based on evanescent tunnel barriers. These building blocks lay the foundation for phononic integrated circuits with applications in sensing, acoustic signal processing, and power-efficient and radiation-hard computing.