Search Results (773)

Size-dependent efficiency degradation remains a major challenge for deeply scaled GaN-based micro-light-emitting diodes (micro-LEDs) because etched sidewalls increasingly influence carrier recombination. Here, square micro-LEDs with lateral dimensions of 5–50 μm were fabricated from the same plasma-assisted molecular-beam-epitaxy-grown wafer containing a five-period InGaN quantum-well/1 nm Al_0.1Ga_0.9N interlayer/InGaN quantum-dot-like (QW–QD) composite active region. Contrary to the conventional size effect, the light output power density and external quantum efficiency (EQE) increased as the mesa size decreased. The peak EQEs were 3.66%, 4.53%, 5.63%, 7.04%, and 7.27% for the 50, 40, 30, 10, and 5 μm devices, respectively, corresponding to an approximately 98.6% increase from 50 to 5 μm. The favorable scaling is consistent with localization-mediated suppression of lateral carrier loss combined with size-dependent light extraction. The present measurements do not quantitatively separate injection, internal efficiency, and extraction contributions. These results demonstrate the potential of ultrathin-interlayer QW–QD active-region engineering for scaled GaN micro-LEDs. Full article

Structural analysis using X-rays and electron beams has long provided the average arrangement of atoms and molecules—that is, “structural information”—with high precision. By contrast, static measurements cannot directly yield dynamic information on how a material changes over time; instead, information on motion is convolved into a single numerical value such as the B-factor (atomic displacement parameter). Taking this limitation as its starting point, this review surveys the recent trend of introducing a time axis into measurements to observe material dynamics directly. First, we outline the technological foundations that have made the transition from static to time-resolved measurement possible. It rests on the dramatic shortening of exposure times, enabled by the increased brilliance of X-ray and electron sources and by advances in detection technology such as direct photon-counting detectors. Next, we survey dynamic measurement techniques, including time-resolved X-ray crystallography, coherent X-ray scattering, neutron scattering, and time-resolved electron microscopy. We also point out the essential limitation that most of them still return ensemble or volume averages. Building on this, we systematically describe diffracted X-ray tracking (DXT), diffracted X-ray blinking (DXB), small-angle X-ray blinking (SAXB), transmitted X-ray blinking (TXB), and electron-beam molecular dynamics (EBMD), which use gold nanocrystals and gold nanoparticles as motion probes. We distinguish throughout between methods that follow individual objects—DXT and EBMD, which yield trajectories of single labeled molecules or single particles—and methods that analyze intensity fluctuations arising from many contributors within one pixel or illuminated volume—DXB, SAXB and TXB. The latter are not single-molecule measurements; rather, they replace a global ensemble average by a spatially localized statistical one, retaining local heterogeneity that a bulk measurement would average away. Finally, we discuss the implementation and prospects of the large-volume data analysis—principal component analysis, Bayesian inference, machine learning, and autonomous measurement—needed to handle the explosively increasing amount of information that the time axis introduces. We close with the outlook that time-resolved measurement incorporating AI and big-data analysis will become established as a new measurement platform that complements and extends conventional static structural analysis. Full article

In multilayer ceramic capacitors, the internal electrodes are fabricated by printing thin layers of nickel paste, which contains a dispersant to prevent the agglomeration of nickel powder particles within the paste. We used molecular dynamics simulations and cryogenic focused ion beam-scanning electron microscopy to investigate the effects of microscopic structures in the adsorbed dispersant layer on the steric stabilization of nickel powder particles. Three dispersants were considered with different molecular structures. The simulation results indicated that stearic acid (SA) resulted in the highest steric stabilization efficiency, followed by lauric acid (LA) and oleic acid (OA). The high crystallinity of the SA and LA layers resulted in compressed molecular chains that induced strong repulsion between nickel powder particles, and the high effective thickness of the SA layer induced a stronger repulsion. The OA layer offered less steric stabilization because the molecular chains exhibited interpenetration rather than compression. The experimental results confirmed that the steric stabilization of nickel paste samples qualitatively aligned with the simulation results. Thus, multicomponent nickel pastes containing a polar solvent require a dispersant that forms a thick and highly crystalline adsorbed layer on nickel powder particles for effective steric stabilization. Full article

Ultraviolet (UV) radiation in high-altitude regions critically accelerates asphalt aging by inducing surface oxidation, molecular chain scission, and loss of low-temperature crack resistance. However, systematic comparisons of the macro-rheological and micro-chemical evolution between base asphalt and SBS-modified asphalt under UV aging remain insufficient. In this study, two types of asphalt (virgin and SBS-modified) were subjected to three aging protocols, namely short-term thermal oxidation (RTFOT), long-term thermal oxidation (PAV), and equivalent UV radiation for 13 h, 26 h, and 37 h. Low-temperature rheological properties were evaluated using the bending beam rheometer (BBR), while atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) characterized the microstructural and chemical changes. The results show that long-term thermal oxidation causes the most severe deterioration of low-temperature rheological performance, whereas short-term thermal oxidation and 13 h UV aging exhibit comparable effects. For SBS-modified asphalt, extending UV exposure from 13 h to 37 h leads to progressive stiffening and loss of relaxation capacity at −12 °C and −18 °C. However, the m-value shows a non-monotonic response at −24 °C, indicating that the temperature dependence of UV aging is more complex at extremely low temperature. For base asphalt, aging promotes the formation and subsequent agglomeration of bee-like structures. For SBS-modified asphalt, the sulfoxide index increases monotonically, while the carbonyl index first increases and then decreases. Although 13 h UV aging and RTFOT produce similar macroscopic outcomes, their mechanisms differ fundamentally, where UV aging is hypothesized to act primarily via photon-induced bond scission, whereas thermal oxidation proceeds through radical chain reactions. Full article

We present a brief review that highlights the importance of III-Nitride semiconductor compounds according to their structural, compositional, morphological, and optical properties, which have significant applications in new semiconductor devices and play a fundamental role in modern electronic and optoelectronic technologies. The importance of sputtering as a viable alternative for obtaining III-Nitride semiconductor compounds is discussed. This is due to its versatility, cost, ease of handling, and advantages provided by the physics of its operation in obtaining thin films compared to techniques such as metal–organic chemical vapor deposition (MOCVD), atomic layer deposition (ALD), and molecular beam epitaxy (MBE). The physics of the sputtering method is briefly and clearly described, including magnetron configurations, plasma generation, energy dependence of sputtering, reactive sputtering, hysteresis effects, target types, and the importance of temperature and working distance between the substrate and target. In addition, the review of the literature on the application of sputtering for obtaining III-Nitride semiconductor compounds is presented. Furthermore, this review also highlights the future of sputtering, which is moving towards high-power pulsation, atomic-level precision, and AI-driven automation due to the miniaturization of electronics, advances in green technology, and innovations in plasma control to increase film density and reduce target material loss. Full article

Theranostics has transformed nuclear medicine from an imaging-focused discipline into a data-rich radiation medicine platform in which target expression, pharmacokinetics, tumor dose, and response can be measured in the same patient. This critical narrative review evaluates patient-specific integration of radiopharmaceutical therapy (RPT) with external-beam radiotherapy (EBRT), with emphasis on quantitative imaging, absorbed-dose estimation, spatial registration, biological interpretation, adaptation thresholds, and reporting. We performed a targeted search of PubMed/MEDLINE, ClinicalTrials.gov, U.S. Food and Drug Administration records, professional-society guidance, and reference lists for English-language evidence available through 31 July 2026, prioritizing guidelines, regulatory documents, randomized and prospective trials, technical validation studies, and clinically informative retrospective series. Established RPT platforms are distinguished from investigational combined-modality applications and emerging or speculative technologies. Liver-directed Y-90 radioembolization combined with focal EBRT remains the most developed model, whereas head and neck, prostate, meningioma, lymphoma, and bone-dominant strategies illustrate distinct clinical geometries and levels of readiness. Across platforms, direct addition of absorbed dose in gray (Gy) is a geometric description, not automatically a biological endpoint; biologically effective dose (BED) and equivalent dose in 2-Gy fractions (EQD2) should be treated as model-based estimates with explicit assumptions. Future theranostic radiation medicine should therefore be built on prospective trials with prespecified dosimetry, uncertainty analysis, adaptation rules, and shared cross-modality reporting standards. Full article

We demonstrate the integration of molecular beam epitaxy (MBE)-grown InAs/InP quantum dots (QDs) on gold thin films, achieving a fivefold enhancement of telecom-wavelength emission compared with QDs grown on distributed Bragg reflectors (DBRs). Micro-photoluminescence (µ-PL) spectroscopy reveals a pronounced increase in PL intensity from the Au-integrated structures, highlighting the enhanced optical response enabled by the metallic mirror effect. Reflectivity measurements exhibit a characteristic dip near the QD emission wavelength, indicating increased optical absorption and reduced reflectance, consistent with improved coupling of incident light into the fabricated structure. Power-dependent measurements demonstrate background-free exciton and biexciton emission from single QDs with resolution-limited linewidths. Polarization-dependent measurements further reveal an ultra-small excitonic fine-structure splitting, reaching values as low as ~2 μeV. Finally, statistical analysis of multiple QDs confirms the reproducibility and robustness of the observed optical properties. Full article

Asphalt serves as the core binder for heavy-load high-modulus pavements, and its viscoelasticity across a wide temperature range directly governs pavement-rutting resistance, low-temperature crack resistance and service life. Virgin asphalt contains abundant light fractions and exhibits insufficient stiffness at high temperatures. Modification with single styrene–butadiene–styrene block copolymer (SBS) fails to meet the anti-deformation requirements under heavy loads, while separate incorporation of nano-silica (nano-SiO₂) aggravates low-temperature brittleness. Existing studies lack comprehensive investigations into the rheological evolution laws and synergistic microscopic mechanisms of asphalt modified by combined SBS and nano-SiO₂. In this paper, virgin asphalt was adopted as raw material to prepare composite modified asphalt with gradient dosages. Integrated macroscopic performance tests and multi-scale microscopic characterizations were conducted for systematic analysis. High-temperature, low-temperature and fatigue performances were evaluated via conventional physical property tests, temperature sweep tests, multiple stress creep recovery (MSCR), linear amplitude sweep (LAS) and bending beam rheometer (BBR) tests. Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC) and thin-layer chromatography–flame ionization detection (TLC-FID) were utilized to analyze variations in functional groups, molecular weight and four fractions, to elaborate the two-phase synergistic modification mechanism. The results demonstrate that the combined incorporation of SBS and nano-SiO₂ synchronously optimizes the comprehensive performances of asphalt. Compared with single-SBS-modified asphalt, the sample with optimal dosages achieves elevated high-temperature modulus and rutting factor, reduced permanent deformation, improved low-temperature stress relaxation capacity and remarkably decelerated fatigue damage accumulation rate. Microscopic characterizations verify that only physical interactions occur during modification without generating new substances. The nano-filler facilitates the aggregation of small molecules and increases the proportion of macromolecules; meanwhile, it physically adsorbs light fractions and induces apparent redistribution of asphalt components, raising the relative proportion of resins and asphaltenes in the organic asphalt phase, realizing moderate heavy-fraction enrichment of the asphalt system. This study clarifies the internal correlation between molecular fraction evolution characteristics and macroscopic rheological performances of asphalt co-modified by nano-SiO₂ and SBS, which can provide theoretical references for formula design and engineering application of modified asphalt materials. Full article

Solid electrolyte interphase (SEI) characterization is needed to interpret the performance, degradation, and lifetime of graphite and Si-containing carbon-based negative electrodes in lithium-ion batteries. However, SEI claims are often difficult to compare because measured signals, inferred assignments, sample history, and electrode architecture are not always clearly separated. This review presents a claim-bounded framework for SEI characterization that distinguishes direct observables from inferred chemical, molecular, structural, morphological, and functional information. Photoelectron spectroscopy methods provide chemical-state and relative-depth-sensitivity constraints; secondary-ion mass spectrometry methods provide fragment and isotope distributions; vibrational spectroscopies support functional-group and local vibrational evidence; nuclear magnetic resonance and molecular mass spectrometry provide molecular or product-level constraints; and microscopy, tomography, and atomic force microscopy provide morphology, architecture, local thickness, topography, and mechanical response. Across these methods, rinsing, drying, sputtering, beam exposure, extraction, and limited sampling can alter the observable and therefore the defensible claim. The review emphasizes the distinction between native electrode-associated SEI features and extracted, soluble, or electrolyte-phase products, and between morphology-only evidence and chemically assigned morphology. It concludes by proposing claim-driven correlative workflows and reporting guidance for reproducible interpretation on graphite, Si/graphite, Si/C, and carbon-coated Si architectures where directly studied or present. Full article

To explore the high-value utilization of liquid recovery products from waste wind turbine blades in road binders, a liquid-rich fraction obtained from subcritical acetic acid degradation and subsequent vacuum distillation of waste wind turbine blade epoxy composites was introduced into styrene–butadiene–styrene (SBS)-modified asphalt to prepare composite-modified asphalt. Conventional property tests, dynamic shear rheological tests, bending beam rheological tests, steady shear tests, master curve analysis, Fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC) were conducted to systematically evaluate the influence of the liquid-rich fraction on the properties and structural characteristics of the composite-modified asphalt. The results showed that, with increasing liquid-rich fraction content, the softening point increased, while penetration and ductility decreased, and the rotational viscosity at 135 °C increased, indicating enhanced overall stiffness and high-temperature flow resistance. High-temperature rheological results showed that the liquid-rich fraction increased the storage modulus, loss modulus, and rutting factor, while decreasing the phase angle improved the high-temperature deformation resistance of the composite-modified asphalt. Low-temperature rheological results indicated that the creep stiffness S increased, the m-value decreased, and the S/m ratio increased, suggesting weakened stress relaxation capacity and reduced cracking resistance at low temperature. Fatigue factor and steady shear results revealed that the liquid-rich fraction enhanced structural stability and flow resistance but also increased fatigue damage sensitivity at intermediate temperature. Master curves, Black diagram, and Cole–Cole plots further demonstrated that the liquid-rich fraction increased the modulus level over a wide frequency domain and strengthened the structural stability of the asphalt system. FTIR and GPC results indicated that the introduction of the liquid-rich fraction increased the relative contents of aromatic structures and polar oxygen-containing groups and promoted molecular association and increased the apparent molecular weight level of the system. Overall, the liquid-rich fraction acted as a structure-enhancing modifier in SBS-modified asphalt, improving its high-temperature performance while causing a certain trade-off in low-temperature and fatigue properties. Therefore, the dosage should be selected by balancing high-temperature stability, low-temperature cracking resistance, and fatigue durability, and the practical sustainability of this recycling route still requires dedicated economic and environmental evaluation. Full article

We demonstrate that dopant inhomogeneity strongly suppresses thermal conductivity in Cd/Eu co-doped, non-polar a-plane-oriented ZnO films grown on r-plane sapphire (Al₂O₃) by plasma-assisted molecular beam epitaxy. X-ray diffraction confirms the a-plane-oriented ZnO without detectable secondary phases. Cross-sectional scanning electron microscopy shows continuous films with well-defined interfaces, and secondary-ion mass spectrometry depth profiling identifies Cd/Eu incorporation through the film thickness and a sharp Zn/O drop at the substrate interface. Cross-plane thermal transport was measured at room temperature using frequency-domain photothermal infrared radiometry (PTR) and analyzed by fitting the complex PTR amplitude and phase with a multilayer heat-diffusion model. The extracted thermal conductivity ($\kappa$) spans ~3.7–6.3 W·m⁻¹·K⁻¹. The lowest $\kappa$ values correlate with increased Eu-distribution inhomogeneity, consistent with enhanced phonon scattering and reduced effective cross-plane heat transport. Full article

Crystalline coatings have emerged as a promising alternative to amorphous mirror coatings for planned upgrades of second-generation detectors such as Advanced Virgo and for future 3G observatories. In this work, we investigate the structural and mechanical properties of epitaxial Cr₂O₃ thin films grown on c-plane sapphire by molecular beam epitaxy, with the objective of evaluating corundum-structured oxides as a new class of crystalline coating materials for gravitational wave interferometers. We report, for the first time, cryogenic mechanical loss measurements of Cr₂O₃ coatings and relate the measured dissipation to their crystalline quality. The structural and mechanical properties of the coatings were evaluated by XRD, RHEED, AFM, and GeNS measurements. Our findings show that the highest-quality chromia layers exhibit mechanical losses at 6 K as low as $(5\pm 1)$ × 10⁻⁶ rad, while poorer crystalline quality is associated with significantly higher losses. These results demonstrate the potential of corundum-structured oxides as mirror coatings for next-generation interferometers. The wide availability of corundum-structured oxides (X₂O₃ with X = Al, Ga, Fe, V, Cr, Ti, …) and their epitaxial compatibility with sapphire, including the possibility of forming solid solutions, further highlights the potential of this largely unexplored materials class. Full article

Stratospheric airship navigation requires accurate wind field measurements at a ~20 km altitude, where low pressure and density limit the effectiveness of conventional wind sensors. To address this, we present a compact direct-detection Rayleigh Doppler wind lidar based on the molecular double-edge technique. The system utilizes a 532 nm fiber-coupled pulsed laser (0.5 W, 5 ns) and a fixed-cavity dual-channel Fabry–Perot etalon as the frequency discriminator. A liquid crystal variable retarder (LCVR) combined with a polarization beam splitter (PBS) enables non-mechanical, high-speed beam switching between two orthogonal line-of-sight (LOS) directions for horizontal wind measurement. Systematic tests are performed in controlled wind fields within Mie-dominated and Rayleigh-dominated regimes. The lidar effectively captures the sharp radial velocity profiles at wind speeds up to 7.6 m/s. Comparative experiments with a reference anemometer show that the system delivers reliable performance at 0.48 m range resolution, with measurement uncertainty below 0.34 m/s. With its compact, lightweight, and high-precision design, the developed lidar demonstrates reliable wind measurement capability under laboratory conditions, indicating its potential for future deployment on stratospheric airships. Full article

This study reports the growth and structural analysis of β-Ga₂O₃ films on 4° off-axis (000±1) Si- and C-face 4H-SiC substrates by plasma-assisted molecular-beam epitaxy (PAMBE). Pre-growth treatments of 4H-SiC substrates were conducted by employing: (I) unintentional oxygen exposure, (II) intentional Ga pre-exposure, (III) a Ga flash-off process followed by Ga pre-exposure, and (IV) intentional oxygen-plasma pre-exposure prior to β-Ga₂O₃ growth, which led to different growth behaviors. The intentional Ga pre-exposure and Ga flash-off followed by Ga pre-exposure treatments modified the initial Si-face surface condition and were consistent with the mitigation of oxygen-induced surface degradation, including possible SiO_x-related effects. In contrast, unintentional oxygen exposure and intentional oxygen-plasma pre-exposure produced RHEED evolution consistent with substantial surface disordering and possible amorphous SiO_x formation on the Si-face 4H-SiC substrate, leading to disordered nucleation and degraded film growth. Growth on the C-face 4H-SiC substrate resulted in more ordered β-Ga₂O₃ films, suggesting that the C-face surface is less susceptible to SiO_x-related degradation under the present oxygen-containing growth environment. The combined in situ RHEED, AFM, and HRXRD results indicate that substrate polarity and pre-growth surface treatments strongly influence the initial nucleation, morphology, and crystalline quality of β-Ga₂O₃ films on 4H-SiC. These findings provide a useful strategy for controlling oxide film growth on easily oxidized substrates under oxygen environments. Full article

Cryo-electron tomography (Cryo-ET) has emerged as a transformative tool for visualizing viral components within their native cellular environment, enabling structural interrogation of viral life cycle events at nanometer resolution without chemical fixation or heavy metal staining. However, a persistent challenge in applying Cryo-ET to virus research is the unambiguous identification of specific viral components within densely crowded tomographic volumes. Electron density encodes mass and shape but not molecular identity, and as the cellular environment grows more complex, the assumption that a given density has no plausible alternative assignment becomes increasingly difficult to defend. This review surveys labeling and localization strategies for in situ Cryo-ET of viral components, encompassing label-free exploitation of native electron density, Cryo-immunogold labeling, genetically encoded and synthetic molecular tags, and correlative Cryo-light/electron microscopy (Cryo-CLEM) combined with Cryo-focused ion beam (Cryo-FIB) milling. We first summarize the landmark structural discoveries that in situ Cryo-ET has delivered across virus families, and then evaluate each labeling strategy against the structural and functional constraints that viral proteins impose, providing a practical framework for matching a labeling approach to a specific viral component and life-cycle stage. Full article