Search Results (606)

X-band copper resonating cavities are key components of future pulsed GHz normal-conductive multi-TeV accelerators. High electric field gradients are required for emerging applications; however, as gradients increase, components’ lifetime decreases, primarily due to radiofrequency (RF) breakdown. Coating technologies are being investigated in several laboratories to improve RF structure, performance and lifetime. To this end, we investigated the feasibility of fabricating nanometer-periodic Cu/Mo metallic multilayers on three-dimensional (3D) aluminum mandrels designed to replicate X-band copper resonating cavities. These nanometer-period multilayers are proposed to mitigate surface degradation due to electric breakdown at high accelerating gradients by stabilizing inner cavity surfaces against dislocation evolution and roughening caused by thermo-mechanical fatigue. High-Power Impulse Magnetron Sputtering (HiPIMS) in a bias-controlled dual closed-field magnetron configuration was employed to deposit alternating Mo and Cu nano-layers onto the 3D geometries. Given the complexity of HiPIMS technology, plasma pulse evolution was studied by combining time-resolved optical emission spectroscopy with electrical measurements of the pulse discharge. The influence of the process parameters, particularly the applied DC bias, on film growth was studied using non-destructive microprobe α-particle elastic backscattering spectrometry (µEBS) and scanning transmission electron microscopy (STEM). STEM and µEBS analyses confirmed that Mo layers with thicknesses of approximately 5–35 nm were successfully deposited repeatedly on thicker Cu layers (30–150 nm), preserving individual layer properties with minimal interdiffusion and alloying. The layers were deposited inside trenches with an aspect ratio of 5:1 representative of X-band irises. This technology, coupled with the replica process, could be applied to highly engineered nanostructured coatings for X-band cavity treatment in compact particle accelerator prototypes, as it may improve electrical breakdown lifetime under high accelerating fields, at least for degradation processes driven by the high mobility of copper dislocations. Full article

Alpha-ketoglutarate (aKG) is a central intermediate of cerebral energy metabolism and a precursor for glutamate synthesis in the brain. Alterations in aKG metabolism occur in pathological contexts, including isocitrate dehydrogenase (IDH) mutant astrocytomas and oligodendrogliomas, in which mutant IDH converts aKG to the oncometabolite 2-hydroxyglutarate. Given its central role in brain metabolism, non-invasive interrogation of aKG-dependent metabolic flux is needed. Hyperpolarized (HP) ¹³C MR enables real-time visualization of metabolic conversion by transiently enhancing signal intensity by several orders of magnitude. Leveraging this approach, we report the first-in-human feasibility and safety study of HP [1-¹³C]aKG MR spectroscopy in the healthy brain (n = 3). A standard operating procedure (SOP) was developed for sterile [1-¹³C]aKG dose production, achieving reproducible polarization levels averaging 30.5 ± 2.2%. Following intravenous administration, time-resolved ¹³C spectra in healthy volunteers demonstrated the detection of HP aKG resonance and a measurable downstream glutamate signal, consistent across repeat acquisitions, with a delayed temporal profile relative to aKG observed in a representative dataset. Although performed in healthy volunteers, these results establish feasibility for HP [1-¹³C]aKG metabolic imaging to open a new window into normal and pathological brain cellular metabolism. Full article

In this study, electrospun poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) biopapers were produced by annealing electrospun fiber mats from two commercial grades (151C and X131A) and compared with films prepared by the conventional melt-mixing/compression molding method. To obtain continuous biopapers, the fiber mats were subjected to mild thermal post-processing at various temperatures. The selected annealing temperatures were 140 °C (151C) and 130 °C (X131A), where interfiber coalescence occurred within a short annealing time (10 s), yielding continuous fibrous films (biopapers). To elucidate the structural mechanisms underlying interfiber coalescence, time-resolved synchrotron SAXS/WAXS and temperature-dependent FTIR spectroscopy were performed. These analyses showed that coalescence occurred through an interplay between thermally induced local ordering at sub-melting temperatures and premelting/partial melting of thin, ill-defined lamellae, with grade-dependent contributions. The resulting biopapers were evaluated against compression-molded films for optical, mechanical, and barrier properties relevant to packaging. All samples showed similar transparency, although compression-molded films were slightly more opaque. The lower-rigidity grade (151C) exhibited more ductile and tougher behavior than X131A. Biopapers showed slightly lower water and oxygen barrier performance than compression-molded films, attributed to differences in material compactness. Overall, brief mild annealing after electrospinning enabled continuous PHBH biopapers with balanced properties, supporting their potential for sustainable PHBH-based food-packaging applications. Full article

The present work aimed at resolving the mystery accompanying the famous Ko-Kutani Honzenji temple shallow bowl by investigating the main elements associated with the coating composition in the surface decoration. This unique vessel belongs to Honzenji temple, located in the Maeda Domain (today’s Ishikawa Prefecture) and is on display at the Ishikawa Prefecture Kutaniyaki Art Museum in Kaga. The Honzenji temple bowl bears a cryptic figure painted in red enamel on the underside and story has it that the Maeda Lord himself may have painted it in the mid-17th century, thus making the bowl a very relevant piece of the history of the Maeda clan, Ishikawa Prefecture (Maeda fiefdom in the Edo period), and Japanese porcelain as a whole. Yet the identification of the actual firing date of the bowl has proven a daunting task for curators worldwide. On the basis of the previously published studies on the world’s most extensive collection of Ko-Kutani Masterpieces belonging to the Ishikawa Prefectural Museum of Art, and shards excavated at Kaga kiln sites, including the celebrated Hakuji bowl (Ishikawa Archaeological Foundation), both conducted by Energy-Dispersive X-Ray Fluorescence spectroscopy (pED-XRF), and in consideration of the absolute prohibition to sample or even touch the Honzenji bowl, pED-XRF was once again selected as the most suitable technique for the analysis of all the enamels and glazing materials. Analytical evidence, for the first time ever, has proven crucial to resolving the issue by enabling the precise dating of the bowl and unveiling the true story behind its technical features and the cryptic underside decoration. Full article

In vitro cell barrier models have been increasingly integrated into pharmaceutical and academic research pipelines to evaluate drug safety and drug delivery due to a shift towards New Approach Methodologies (NAMs) in research and regulatory safety assessment. Such models require reliable and interpretable functional readouts. Bioimpedance-based monitoring, particularly transepithelial/endothelial electrical resistance (TEER), is a widely adopted readout due to its non-invasive and real-time capabilities. However, substantial variability arises from differences in measurement settings, frequency selection, electrode configuration, impedance measuring techniques, and data analysis strategies. In numerous studies, TEER is approximated from single-frequency impedance magnitude measurements, which do not isolate the resistive component associated with tight junction-mediated paracellular transport but instead reflect the combined response of a coupled electrochemical system. This review clarifies impedance measuring techniques and systematically analyzes impedance-based measurement and analysis strategies for in vitro biological cell barrier integrity. We compare mono-frequency and broadband acquisition approaches, examine the influence of electrode–electrolyte interfaces, electrode geometry, and culture configuration, and evaluate equivalent circuit modeling and phase-resolved electrical impedance spectroscopy (EIS). Based on this comparison, we propose a three-level analytical hierarchy adapted to experimental objectives and instrumentation constraints. We conclude that phase-informed impedance analysis and harmonized reporting are essential to improve measurement reproducibility, inter-platform comparability, and integration of impedance-derived cell barrier assessment within NAMs-oriented research workflows. Full article

²⁰Na is a well-known $\beta$-delayed $\alpha$ emitter, owing to the large decay energy of ²⁰Na above the α + ¹⁶O threshold in the $A=5\alpha$ daughter nucleus ²⁰Ne. In this work, the decay property of ²⁰Na is investigated in detail via the β-γ β-α and β-γ-α coincidence spectroscopy. As the day-one experiment of the Beijing Rare Isotope Facility (BRIF), the intense ²⁰Na beam was produced using the Isotope Separator On Line (ISOL) technique through the 100 MeV proton bombarding a stack of MgO as a thick target. Specific interest was focused on the exotic decay mode of ²⁰Na; the previously reported low-energy α lines at 713 and 846 keV were confirmed, and several weak β-γ-α decay sequences were clearly identified for the first time, thanks to the strong resolving power of α-γ coincidence spectroscopy. The decay properties of ²⁰Na are compared to the shell model calculation, which agree reasonably well with the allowed β transition strengths and subsequent electro-magnetic transitions with the use of the sd shell-model space with the USDB interaction. Full article

Biochemical detection is fundamental to various scientific disciplines, yet conventional methods still face inherent bottlenecks in achieving rapid, ultrasensitive, and simultaneous multi-target analysis. Terahertz (THz) waves, characterized by their unique spectral fingerprinting capabilities and non-destructive properties, have emerged as a compelling platform for advanced biochemical sensing. This review outlines the evolution of THz biochemical sensing over the past two decades, tracing its progression from passive identification toward intelligent perception. We structure this technological trajectory around four core themes: sensitivity enhancement, specific recognition, multi-target visualization, and system intelligence. We first evaluate the fundamental limitations of direct detection techniques, such as THz time-domain spectroscopy (THz-TDS). Building on this, we examine how metamaterial-assisted architectures utilize high-quality-factor resonances to achieve trace-level detection, pushing the limits of detection (LOD) down to the ng/mL or even pg/mL scale, and how surface chemical functionalization provides a molecular lock mechanism for selective targeting in complex samples. Furthermore, we highlight the paradigm shift from single-point spectral measurements to spatially resolved multi-target imaging using pixelated metasurfaces. Finally, the review addresses emerging directions, including dynamically tunable intelligent metasurfaces, multimodal on-chip integration platforms, and the growing integration of artificial intelligence (AI) in inverse design and data interpretation, which achieves classification accuracies exceeding 95% even in complex matrices. By synthesizing these developments, this review provides a comprehensive perspective on the future trajectory of THz sensing technologies. Full article

In an accelerated aging experiment involving a wide range of cumulative UV-B radiant exposures (up to approximately 9.46 × 10³ J cm⁻²), the degradation state of microplastics was assessed using SEM, FTIR, Raman spectroscopy, and DSC, and correlated with the cumulative UV-B dose. Sunlight-induced photooxidation is a significant weathering mechanism for microplastics. In this study, high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polyvinyl chloride (PVC), nylon, and polystyrene (PS) were exposed to UV-B radiation under controlled dry conditions at two irradiance levels (0.06 and 0.6 mW cm⁻²), covering cumulative UV-B radiant exposures of up to approximately 9.47 × 10³ J cm⁻². Degradation was evaluated using SEM, FTIR, Raman spectroscopy, and DSC, and was related to the cumulative UV-B dose (H). The extent and progression of degradation varied significantly among the polymers. Overall, FTIR provided the most sensitive assessment of photooxidative surface changes for HDPE, LDPE, PP, and PS, Raman spectroscopy was most diagnostic for PVC (particularly for dechlorination-related changes), and DSC-derived crystallinity was most informative for nylon. These dose-resolved datasets establish a reproducible reference framework (“degradation library”) to facilitate the comparative assessment of the relative photooxidative aging stage of microplastics under comparable surface UV-driven conditions. Outdoor “sunlight-equivalent” times are reported solely as order-of-magnitude contextualization due to environmental variability. Full article

A spatially resolved investigation of bacterial inactivation using a radiofrequency (13.56 MHz) capacitively coupled plasma (RF CCP) discharge operating in ambient air at 4.0 mbar is presented. The plasma was generated in a parallel-plate reactor without external gas precursors and characterized using Langmuir probe diagnostics and optical emission spectroscopy (OES). Electron densities on the order of 109 cm³ were measured near the powered electrode, exhibiting pronounced axial and radial gradients across the discharge volume. OES revealed strong excitation of oxygen- and nitrogen-containing emitters, including O I (777 nm), N₂ s positive system (337–380 nm), and N₂⁺ first negative system features, with emission intensities increasing monotonically with applied RF power. The bactericidal performance was evaluated using Escherichia coli American Type Culture Collection (ATCC) 11775 exposed at different axial and radial positions within the reactor. At a fixed exposure time of 60 s, the log₁₀ reduction increased nonlinearly with RF power, rising from 0.29 at 20 W to 0.81 at 40 W, followed by a sharp transition to the assay reporting ceiling (≥2.95-log₁₀ under the adopted half-count correction) at 50 W and above. Time-resolved measurements at 50 W demonstrated rapid inactivation kinetics, with measurable reductions occurring within 5–10 s and reaching the reporting ceiling within 60 s. In contrast, samples positioned at the chamber periphery or approximately 20 cm from the discharge center exhibited negligible inactivation, confirming strong spatial localization of the biocidal effect. These results identify a threshold-like operating regime in which increased discharge intensity produces rapid inactivation in the plasma core while remaining strongly position dependent. The findings establish medium pressure, air-based RF CCP as an efficient, gas-free, and spatially controllable platform for localized surface decontamination under non-thermal conditions. Full article

Ultrafast spin dynamics is a core research focus for advancing ultrafast spintronic devices, yet its accurate quantitative probing remains a challenge with conventional time-resolved techniques. Herein, we employ double-pump optical pump–terahertz emission spectroscopy (OPTE) to investigate the ultrafast spin dynamics of a Pt/Gd₁₉(Co_0.8Fe_0.2)₈₁/Ta ferrimagnetic rare-earth–transition-metal heterostructure. Experimental measurements resolve a single-step ultrafast demagnetization process with a characteristic time of ~0.42 ± 0.02 ps, followed by two-stage magnetic recovery involving a fast relaxation and a slow relaxation process. The fast and slow recovery time constants show a distinct positive dependence on the control pump fluence, increasing from 2.49 ± 0.11 ps to 3.28 ± 0.03 ps and 57.36 ± 11.28 ps to 164.96 ± 1.61 ps, respectively, as the pump fluence rises from 0.80 to 1.19 mJ/cm². The ~0.42 ps demagnetization timescale is consistent with that of 3d transition metals, indicating the transient magnetic response of the low-Gd-concentration heterostructure is dominated by the CoFe sublattice. Our findings validate that OPTE is an effective approach for the quantitative characterization of electron–lattice–spin coupling processes in spin-based heterostructures and provide critical experimental insights for controllable manipulation of ultrafast spin dynamics, laying a foundation for the design of ultrafast terahertz spintronic devices. Full article

Zero-valent iron (Fe(0)) nanoparticles have a wide range of applications, including catalysis, energy storage, and even reported roles in human neurochemistry. This study demonstrated that [Fe₃(CO)₁₂] dissolves in N,N-Dimethylformamide (DMF) within a minute to resolve the dissolution problem of this complex. Dodecylamine (DDA) was used to produce DDA-coated Fe(0) at 383 K in 30 s with a microwave reactor. The powder X-ray diffraction (PXRD) of the Fe(0) profile indicated a pure-phase face-centred cubic (FCC) structure with Fm$\overline{3}$m space group. Varying the synthesis time from 30 s to 5 min did not significantly affect the unit cell parameters (3.5276 (±0.0001) and 3.5391 (±0.0001) Å). Microwave use yielded well-dispersed, pure Fe(0) nanoparticles, and the particle size, shape, elemental analysis, and surface oxidation of the Fe(0) nanoparticles were studied using scanning electron microscopy and dispersive X-ray spectroscopy (SEM/EDX). Annular Dark-Field Scanning Transmission Electron Microscopy (ADF-STEM) and Fourier-transform infrared (FT-IR) spectroscopy confirmed the surface coating of Fe(0) nanoparticles with DDA. Thermogravimetric analysis (TGA) was used to demonstrate the surface adsorption of DDA on Fe(0) nanoparticles. In addition, STEM showed that the average nanoparticle size under the stated synthesis conditions was 25.7 nm. This comparatively straightforward procedure offers advantages over existing practical approaches to the synthesis of Fe(0) nanoparticles, including safety, speed and reaction control. Full article

Oxygenic and anoxygenic photosynthesis are initiated through the absorption of light by chlorophyll and bacteriochlorophyll photosynthetic pigments, respectively, which function as light-harvesting (antenna) and redox pigments on the photosynthetic membrane that trap and convert the absorbed optical energy into chemical energy. While several studies have characterized the ultrafast spectra, kinetics, and structures of the light-harvesting and reaction center complexes that contain the photosynthetic pigments, a detailed understanding of how the ultrafast excited-state dynamics vary across different photosynthetic pigments is lacking. Such information is critical in understanding the molecular mechanisms of both artificial and natural photosynthetic systems. In this study, we conducted ultrafast time-resolved absorption spectroscopy on chlorophyll and bacteriochlorophyll photosynthetic pigments at room temperature to directly compare the spectra and kinetics of their transient, excited electronic states formed following photon absorption. The recorded ultrafast spectral and kinetic data, spanning the femtosecond to sub-microsecond timescales, show interesting similarities and differences between these two distinct types of photosynthetic pigments. These experimental results help clarify the relationship between photosynthetic pigment structure and the resultant ultrafast processes in the oxygenic and anoxygenic photosynthetic reaction mechanisms. Full article

In this paper, the Distribution of Relaxation Times (DRT) method is introduced for analyzing aging and failure conditions in lithium-ion (Li-ion) batteries, addressing challenges associated with its implementation. While Electrochemical Impedance Spectroscopy (EIS) and Equivalent Circuit Models (ECMs) are commonly used to monitor battery performance, their interpretation is often complicated by overlapping semicircles in impedance spectra. The DRT technique resolves this issue by deconvolving relaxation times, enabling the separation of individual electrochemical processes and providing a clearer understanding of aging and failure conditions. The peaks of lower frequency components in DRT plots, specifically the charge transfer and diffusion processes, are key indicators of the battery failure point. When these two processes merge, it signals that the battery can no longer function, marking a critical failure point in Li-ion batteries. Identifying failure conditions and aging in Li-ion batteries using DRT offers a more advanced approach compared to ECM, as it delivers greater detail in the electrochemical processes that contribute to performance degradation. The analysis of two kinds of different Lithium-Ion battery cells based on the DRT reveals the specific aging and failure patterns, particularly in later battery life stages. The findings demonstrate the potential of DRT as a real-time indicator to monitor the status and the lifecycle of the battery. Full article

Time-resolved (TR) resonance Raman (RR) spectroscopy with continuous-wave excitation is a fundamental technique that has contributed substantially to the understanding of the structure and dynamics of retinal proteins. However, the underlying principles were developed about fifty years ago for instrumentation that is hardly in use anymore. Thus, the adaptation of the technique to the current state-of-the-art equipment is needed to satisfy the increasing demand for the spectroscopic characterization of novel retinal proteins. In this work, we focus on pump–probe TR RR experiments with a confocal spectrometer using a rotating cell. We define the parameters ensuring fresh-sample condition and the photochemical innocence of the probe beam as a prerequisite for studying retinal proteins that undergo a cyclic photoinduced reaction sequence. For the measurements of intermediate states and reaction kinetics, pump–probe experiments are required in which the two laser beams hit the flowing sample with a defined but variable delay time. An appropriate set-up for such two-beam experiments with a confocal spectrometer is proposed and tested in TR experiments of bacteriorhodopsin. The comparison with the results obtained with classical slit spectrometers using a 90-degree scattering illustrates the advantages and disadvantages of the confocal arrangement. It is shown that modern confocal spectrometers substantially decrease the spectra acquisition time but require a more demanding optical set-up. Furthermore, the extent of photoconversion by the pump beam is lower than for the 90-degree-scattering arrangement, which reduces the accuracy of kinetic measurements. Full article