Search Results (6,696)

This work presents a detailed study of the coordination of Eu(III) with tartrate and oxalate ligands in aqueous solutions. The following techniques were employed: potentiometric titrations, 1D ¹H, ¹³C multinuclear NMR spectroscopy, 2D NMR experiments (COSY, HMQC, HMBC), and UV-Vis spectroscopy. Overall (cumulative) formation constants (logβ) were determined at ionic strengths of 0.1, 0.5, and 1.0, M KNO₃ over the temperature range 298–318 K. At 298 K, the oxalate complexes are significantly more stable (logβ = 7.63→15.70 as the ionic strength increases from 0.1 to 1.0 M) than the corresponding tartrate species (logβ = 5.11→8.87). Analysis of the temperature dependence of logβ shows that the Gibbs free energy change comprises both temperature-dependent terms and an approximately temperature-independent covalent contribution, the latter becoming strongly negative values in the tartrate system. The NMR data support a bidentate coordination mode involving deprotonated hydroxyl and carboxylate groups, whereas ¹⁷O NMR monitors the mechanism of water exchange within the Eu(III) hydration sphere. In the UV-Vis domain, a distinct blue shift in the absorption band is observed at 0.1 M KNO₃, while at 1.0 M KNO₃, the band shows a pronounced decrease in intensity, a hypochromic effect. This behavior can be attributed to increased structural distortion and a partial loss of coplanarity within the tartrate coordination environment. By contrast, the oxalate system behaves differently: the spectra, together with the thermodynamic data, support a more covalent Eu–O interaction, consistent with stabilization of Eu(III) by two dicarboxylate ligands adopting distinct coordination modes. Full article

One of the most critical damage modes affecting the structural performance of traditional composite materials, and therefore their durability, is the occurrence of interlaminar cracks (delamination), which are prone to grow under different loading conditions. In this study, the feasibility of repairing carbon fiber reinforced polymer (CFRP) laminates using structural adhesives was experimentally investigated by evaluating the Mode I interlaminar fracture toughness. Two unidirectional AS4 CFRP systems were analyzed, manufactured with epoxy 8552 and epoxy 3501-6 matrix resins. Mode I delamination behavior was characterized using Double Cantilever Beam (DCB) specimens. Three commercial structural adhesives were used in the repair process: two epoxy-based systems, (Loctite^® EA 9460™, manufactured by Henkel adhesives (Düsseldorf, Germany), and Araldite^® 2015 manufactured by Huntsman Advanced Materials (The Woodlands, TX, USA) and one low-odor acrylic adhesive, 3M Scotch-Weld^® DP8810NS manufactured by 3M Company (St. Paul, MN, USA). Adhesive joints were applied to previously fractured specimens, and the results were compared with those obtained from baseline composite specimens. The results indicate that repaired joints based on the 8552 matrix exhibited higher strain energy release rate (G_Ic) values, approaching those of the original material. The 3501-6 system showed increased fiber bridging, contributing to higher apparent fracture toughness. Among the adhesives evaluated, the acrylic-based adhesive provided the highest delamination resistance for both composite systems. Full article

Vector bending sensing is an important research direction in the field of bionic robot design. A vector bending sensor with temperature compensation based on Mach–Zehnder interferometer (MZI) is proposed and experimentally investigated. The MZI is implemented using an off-axis splice between a single-mode fiber (SMF) and a double-cladding fiber (DCF). The proposed sensor is analyzed comprehensively from the perspective of theoretical analysis and experimentally demonstrated. It reaches a high curvature sensitivity as high as −8.311 nm/m⁻¹ and a compact size as small as 3 mm, while keeping the capability of direction sensing and temperature compensation. The proposed vector bending sensor has a good potential for accurate curvature measurement due to its high accuracy, multifunction, low cost and, compact size. Full article

This work presents the design and experimental validation of a 2 × 2 MIMO communication system assisted by a directly modulated analog radio-over-fiber (A-RoF) fronthaul, targeting low-complexity connectivity solutions for underserved/remote regions. The study details the complete end-to-end architecture, including a wireless access segment to complement the 20-km optical fronthaul link. The system is implemented on an software defined radio (SDR) platform using GNU Radio 3.7.11, running on Ubuntu 18.04 with kernel 4.15.0-213-generic. It also employs adaptive modulation driven by real-time signal-to-noise ratio (SNR) estimation to keep bit error rate (BER) close to zero while maximizing throughput. Performance is characterized over 20 km of single-mode fiber (SMF) using coarse wavelength division multiplexing (WDM) and assessed through root mean square error vector magnitude (${\mathrm{EVM}}_{\mathrm{RMS}}$), throughput, and spectral integrity. The results identify an optimum radio-frequency drive region around $-16$ dBm enabling high-order modulation (e.g., 256-QAM), whereas RF input powers above approximately $-10$ dBm increase ${\mathrm{EVM}}_{\mathrm{RMS}}$ due to nonlinearity in the RF front-end/low-noise amplifier (LNA) and direct modulation stage, forcing the adaptive scheme to reduce modulation order and throughput. Over the optical-power sweep, when the incident optical power exceeds approximately $-8$ dBm, the system reaches ∼130 Mbps (24-MHz channel) with ${\mathrm{EVM}}_{\mathrm{RMS}}$ approaching ∼1%, highlighting the need for careful joint tuning of RF drive, optical launch power, and wavelength allocation across transceivers. Finally, the integrated access link employs diplexers for transmitter/receiver separation in a 2 × 2 configuration with 2.8 m antenna separation and low channel correlation, demonstrating a 10 m proof-of-concept range and enabling end-to-end spectrum/EVM/throughput observations across the full communication chain. Full article

Tweeks are ELF/VLF radio signals originating from lightning discharges that exhibit dispersion due to their propagation in the Earth-ionosphere waveguide. Examples of the waveforms of tweeks and their dynamic frequency-time spectra are presented and interpreted. Tweeks observed in the daytime and night-time are compared and contrasted. Tweeks observed during a solar eclipse are also discussed, as are those due to volcanic lightning and those claimed to be recorded some hours or days before a strong earthquake. The variations of tweek occurrence with season and geomagnetic activity, and with variations of solar radiation over the 11-year solar cycle, are reviewed. Wherever possible, geophysical interpretations are discussed. Theoretical models of tweek waveforms and spectra are considered; they vary according to the lightning current model used, the distance from the source (≥1 Mm), the vertical profile of ionospheric D-region ionisation and the specific mode theory used. The simplest interpretation shows that the first-order tweek cut- off frequency ~1.8 kHz is explained as reflection by the ionosphere at a height of ~83 km where the electron density is ~27 × 10⁶ m⁻³. More complex interpretations are also reviewed and compared with electron density observations made by rockets and with profiles given by lower ionospheric models such as the International Reference Ionosphere or the Faraday International Reference Ionosphere. Full article

Bongkrekic acid (BKA), a highly lethal toxin, has been implicated in frequent poisoning incidents in recent years, posing a serious threat to global food safety and creating an urgent need for rapid and sensitive detection methods. This review provides a systematic analysis of the entire BKA detection technologies, covering sample pretreatment techniques, instrumental analysis, immunoassays, and biosensing methods. It assesses the merits of key methods and also explores the strategic cross-application of detection paradigms developed for analogous toxins. This review delivers a comprehensive and critical evaluation of BKA detection technologies. First, it discusses sample pretreatment strategies, notably solid-phase extraction (SPE) and QuEChERS. Subsequently, it analyzes the principles, performance, and applications of core detection methods, including high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS), high-resolution mass spectrometry (HRMS), time-resolved fluorescence immunoassay (TRFIA), dual-mode immunosensors and nanomaterial-based sensors. Instrumental methods (e.g., HRMS) offer unmatched sensitivity [with a limit of detection (LOD) as low as 0.01 μg/kg], yet remain costly and laboratory-dependent. Immunoassay and biosensor approaches (TRFIA and dual-mode sensors) enable rapid on-site detection with high sensitivity (ng/mL to pg/mL), though challenges in stability and specificity remain. Looking forward, the development of next-generation BKA detection could be accelerated by cross-applying cutting-edge strategies proven for toxins—such as Fumonisin B1 (FB1), Ochratoxin A (OTA), and Aflatoxin B1 (AFB1)—including nanobody technology, CRISPR-Cas-mediated signal amplification, and multimodal integrated platforms. To translate this potential into practical tools, future research should prioritize the synthesis of high-specificity recognition elements, innovative signal amplification strategies, and integrated portable devices, aiming to establish end-to-end biosensing systems capable of on-site rapid detection through multitechnology integration. Full article

The thermally efficient and lightweight TRC/CLCi composite panels for functional and smart building envelopes, funded by the iclimabuilt project (Grant Agreement no. 952886), offer innovative solutions to sustainably address common failure risks in facade systems. This work specifically emphasizes strategies for mitigating structural, thermal, and fire-related failures through targeted material selection, advanced design methodologies, and rigorous validation protocols. To effectively mitigate structural failures, high-pressure concrete (HPC) reinforced with carbon fibers is utilized, significantly enhancing tensile strength, reducing susceptibility to cracking, and improving overall durability. To counteract thermal bridging—a critical failure mode compromising energy efficiency and structural integrity—the panels employ specially designed glass-fiber reinforced pins connecting HPC outer layers through the cellular lightweight concrete (CLC) insulation core that has a density of around 70 kg/m³ and a thermal conductivity in the range 35 mW/m∙K comparable to those of expanded polystyrene and Rockwool. These connectors ensure effective load transfer and maintain optimal thermal performance. A central focus of the failure mitigation strategy is robust fire behavior. The developed panels undergo rigorous standardized fire tests, achieving an exceptional reaction to fire classification of A2. This outcome confirms that HPC layers maintain structural stability and integrity even under prolonged fire exposure, effectively preventing catastrophic failures and ensuring occupant safety. In conclusion, this work highlights explicit failure mitigation strategies—reinforced concrete materials for structural stability, specialized glass-fiber connectors to prevent thermal bridging, rigorous fire behavior protocols, and comprehensive thermal performance validation—to produce a facade system that is robust, energy-efficient, fire-safe, and sustainable for modern buildings. Full article

Background/Objectives: Pyrazole carboxamides are widely used as adaptable medicinal-chemistry scaffolds and have been explored as cholinesterase (ChE) inhibitor chemotypes. In this work, we prepared a new series of 4-arylazo-3,5-diamino-N-tosyl-1H-pyrazole-1-carboxamides 5(a–m) and evaluated their inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), supported by structure-based computational analyses. Methods: Thirteen derivatives 5(a–m) were synthesized, fully characterized with analytical techniques (FT-IR, H NMR, and C NMR), and tested in vitro against AChE and BChE, with tacrine (THA) used as the reference inhibitor. Docking calculations were used to examine plausible binding modes. The top-ranked complexes (7XN1–5e and 4BDS–5i) were further examined by 100 ns explicit-solvent molecular dynamics (MD) simulations in Cresset Flare, followed by RMSD/RMSF analysis and contact-persistence profiling. Predicted ADME/Tox. properties were also assessed to identify potential developability issues. Results: The series showed strong ChE inhibition, and several compounds were more potent than THA. Compound 5e (4-nitro) was the most active AChE inhibitor (K_I = 20.86 ± 1.61 nM) compared with THA (K_I = 164.40 ± 20.84 nM). For BChE, the K_I values ranged from 31.21 to 87.07 nM and exceeded the reference compound’s activity. MD trajectories supported stable binding in both systems (10–100 ns mean backbone RMSD: 2.21 ± 0.17 Å for 7XN1–5e; 1.89 ± 0.11 Å for 4BDS–5i). Most fluctuations were confined to flexible regions, while key contacts remained in place, consistent with the docking models. ADME/Tox. predictions suggested moderate lipophilicity but generally low aqueous solubility; all compounds were predicted as non-BBB permeant, and selected liabilities were flagged (e.g., carcinogenicity for 5e/5g/5h/5i; nephrotoxicity for 5f/5g). Conclusions: The 4-arylazo-3,5-diamino-N-tosyl-1H-pyrazole-1-carboxamide scaffold delivers low-nanomolar ChE inhibition, with docking and MD supporting stable binding modes. Future optimization should prioritize solubility improvement and mitigation of predicted toxicities and metabolic liabilities, especially given the predicted lack of BBB permeability for CNS-directed applications. Full article

Mean corpuscular volume ($MCV$) is a routinely measured hematological parameter that influences blood viscosity by altering red blood cell volume and packing density. Although $MCV$ is physiologically linked to hemorheological behavior, to the authors’ knowledge, its direct role in modulating large-artery hemodynamics has not been systematically quantified. This study introduces an $MCV$-driven effective Newtonian viscosity mode to evaluate the first-order impact of $MCV$ variation on carotid bifurcation flow. Rather than employing shear-dependent constitutive laws, blood viscosity was scaled through an $MCV$-based formulation, yielding three Newtonian fluids corresponding to clinically relevant $MCV$ levels of 70, 90, and 110 fL. Pulsatile CFD simulations were performed in four idealized carotid bifurcation geometries (40°, 50°, 65°, and 100°) to assess the combined influence of vascular geometry and $MCV$-dependent viscosity variation. Hemodynamic indices including time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and relative residence time (RRT) were quantified, and a two-way analysis of variance (ANOVA) was employed to distinguish the relative contributions of geometric configuration and $MCV$. Across the investigated $MCV$ range, increasing $MCV$ produced a geometry-dependent modulation of shear-based indices, with TAWSS increasing by up to approximately 11%, while OSI and RRT decreased by about 20–25% and 10%, respectively, particularly in geometries exhibiting pronounced flow separation. Although vascular geometry remained the dominant determinant of overall hemodynamic patterns, $MCV$-induced viscosity scaling significantly modulated low-shear and recirculation regions. These findings suggest that $MCV$-dependent viscosity scaling can complement patient-specific hemodynamic assessments and provide a rational baseline for future shear-dependent and personalized rheological modeling frameworks. Full article

During the high-intensity mining of shallow-buried thick coal seams, the formation of a water-conducting fracture zone within the overburden is a primary cause of damage to the groundwater system. To address the challenge of balancing efficiency and cost in traditional water-retaining mining methods, this study proposes and validates a trapezoidal strip filling mining technology based on the “span reduction effect”. By developing a mechanical model of a four-sided simply supported thin plate representing the key layer, the fundamental mechanism of the filling body was elucidated. This mechanism involves the active adjustment of the support boundary, which effectively reduces the force span of the key layer. Furthermore, leveraging the fourth-power relationship (w ∝ a⁴) between deflection and span, the bending deformation of the overburden rock is exponentially mitigated. This study employs a four-tiered integrated verification system comprising theoretical modeling, physical simulation, numerical simulation, and engineering field testing: First, theoretical calculations indicate that reducing the effective span of the key layer by 40% can decrease its maximum deflection by 87%. Second, large-scale physical similarity simulations predict that implementing this filling method can significantly control the height of the water-conducting fracture zone, reducing it from 94 m under the collapse method to 58 m, which corresponds to a 45.5% reduction in surface settlement. Third, FLAC^3D numerical simulations further elucidated the mechanical mechanism by which the backfill system transforms stress distribution from “coal pillar-dominated bearing capacity” to “synergistic bearing capacity of backfill and coal pillars”. Shear failure in the critical layer was suppressed, and the development height of the plastic zone was restricted to approximately 54 m, showing high consistency with physical simulation results. Finally, actual measurements of water injection through the inverted hole underground provide direct evidence: The heights of the water-conducting fracture zones in the filling working face and the collapse working face are 59 m and 93 m, respectively, reflecting a reduction of 36.6%. Based on the consistency between measured and simulated results, the numerical model employed in this study has been effectively validated. Research indicates that employing trapezoidal strip filling technology based on principal stress dynamics regulation can effectively promote a shift in the failure mode of the overlying critical layer from “fracture–conduction” to “bending–subsidence”. This mechanism provides a clear mechanical explanation and predictable design basis for the green mining of shallow coal seams. Full article

This study introduces a predictive model based on artificial neural networks (ANNs) for estimating the dynamic performance of commercially available sensible thermal energy storage (STES) systems. The model was trained and validated using high-resolution experimental data measured from two vertical cylindrical tanks (0.3 m³ each) including internal heat exchangers and operating under both heating and cooling modes. A comprehensive sensitivity analysis was conducted on 28 ANN architectures by varying the number of hidden neurons and input delays. The optimal configuration, designated as ANN5 (12 neurons, delay = 1), demonstrated superior accuracy in predicting temperature profiles and energy exchange. Validation against an independent dataset confirmed the model’s robustness, achieving normalized root mean square errors (NRMSEs) between 0.0022 and 0.0061 for the hot tank and between 0.0057 and 0.0283 for the cold tank. Energy prediction errors were within −3.87% for charging and 0.09% for discharging in heating mode, and 7.08% for charging and 0.13% discharging in cooling mode, respectively. These results highlight the potential of ANN-based approaches for real-time control, forecasting, and digital twin applications in STES systems. Full article

Sweet potatoes (Ipomoea batatas (L.) Lam.) are known for their anti-inflammatory effects, which are attributed to their phytochemical content. Our previous study revealed that ethanol extracts of sweet potato storage roots (SP-EtOH-Ex) inhibit interleukin-6 (IL-6) production in RAW264.7 cells stimulated with lipopolysaccharide (LPS). However, the causative compounds responsible for the anti-inflammatory effect have not yet been identified. This study aims to identify the compounds responsible for the anti-inflammatory effect of SP-EtOH-Ex using liquid chromatography–quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS). The unknown compounds were measured using the auto MS/MS mode (data-dependent acquisition; DDA) of LC-Q-TOF-MS, and the resulting data were analyzed using MS-DIAL and MS-FINDER and also compared with those of the corresponding reference standards in terms of retention time and fragment ions. As a result, β-sitosterol (2.527–4.850 µg/mL), campesterol (75.74–93.63 ng/mL), and lauroyl diethanolamide (4.568–9.260 ng/mL) were identified and quantified in SP-EtOH-Ex. Moreover, the anti-inflammatory effect of these three compounds against RAW264.7 cells was investigated at varying concentrations of β-sitosterol (1 µg/mL, 5 µg/mL, 10 µg/mL), campesterol (10 ng/mL, 100 ng/mL, 1000 ng/mL), and lauroyl diethanolamide (1 ng/mL, 10 ng/mL, 100 ng/mL). The phytosterols β-sitosterol and campesterol suppressed LPS-induced IL-6 production at concentrations comparable to those present in SP-EtOH-Ex. In contrast, lauroyl diethanolamide did not similarly suppress LPS-induced IL-6 production. These results suggest that β-sitosterol and campesterol in sweet potato storage roots contribute to their anti-inflammatory effects. The lack of activity in lauroyl diethanolamide further supports that phytosterols are the primary anti-inflammatory constituents. The edible portion of sweet potatoes holds promise as a promising raw material with anti-inflammatory properties. Full article

Traditional homogeneous copper foils suffer from a trade-off between strength and ductility, while gradient or heterogeneous structures are mostly based on deformation processing, making it difficult to achieve controllable construction within a thickness of ≤10 μm. This study aims to directly construct a layered structure with a “fine–coarse–fine” (A-B-A) gradient grain distribution, denoted as 3L-ABA in an 8 μm copper foil via direct current electrodeposition, which utilizes composite additives to regulate electrochemical polarization and nucleation modes. Through systematic characterization and mechanical testing, it was found that the 3L-ABA copper foil exhibits a tensile strength of 604 ± 18 MPa, an elongation of 3.6 ± 0.25%, and low surface roughness Rz of 0.46 μm. Microscopic mechanism analysis demonstrates that the gradient structure achieves synergistic strengthening and toughening through surface fine-grain strengthening, intermediate coarse-grain coordinated plastic deformation, combined with dislocation density and twin strengthening. Electrochemical tests confirm that Additive A (containing collagen, bis-(3-sulfopropyl)-disulfide (SPS), thiourea and 2-mercapto-5-benzimidazolesulfonic acid sodium salt (2M5S)) induces strong cathodic polarization, promoting instantaneous nucleation and grain refinement, whereas Additive B (containing collagen and bis-(3-sulfopropyl)-disulfide (SPS) shows weaker polarization and promotes grain growth. This research provides a scalable electrodeposition solution for the microstructural design and performance regulation of ultra-thin copper foils. Full article

Improving sensitivity in short-wave infrared (SWIR) detection is crucial for low-signal applications, such as astronomy and hyperspectral imaging, which demand readout integrated circuits (ROICs) with minimal noise and high density. However, conventional differential pixels with correlated double sampling (CDS) are difficult to integrate due to spatial limitations. In order to tackle this issue, we propose a compact, pixel-level, single-ended charge-domain architecture. It integrates single-ended CDS within each pixel, guaranteeing compatibility with the integrate-while-read (IWR) mode while suppressing reset and 1/f noise. A capacitor reuse technique is also proposed to enable the integration capacitor to function as an auxiliary load, which optimizes the noise–area trade-off. Fabricated in 180 nm CMOS, our 1296 × 256 ROIC attains a noise floor of 0.50 mV (achieving a reduction of approximately 70% compared to conventional architectures under identical conditions), consumes under 200 mW, and operates at frequencies exceeding 200 Hz. It also exhibits great linearity (0.9999) and supports both integrate-then-read (ITR) mode and integrate-while-read (IWR) mode, while also providing a row-level gain selecting function. Validated at 15 μm pitch, this design provides an effective option for high-density SWIR systems. Full article

Photobiomodulation causes an immediate increase in local blood flow. This study aimed to investigate the effect of 890 nm NIR exposure on local skin blood flow in young and middle-aged healthy subjects. In this placebo-controlled clinical trial, 12 young and 12 middle-aged subjects received either continuous or intermittent NIR exposure (890 nm, 5.1 mW/cm², 4.6 J/cm², and 35.9 J total energy) on the skin of the upper lateral arm. The continuous exposure experiment, performed in young subjects only, applied 30 min of continuous NIR light. The intermittent exposure experiment, conducted in both age groups, applied NIR light through 10 cycles of 3 min NIR exposure and 2 min OFF (for recording blood flow), resulting in a total duration of 50 min. Laser Doppler flowmetry and thermal images were used to monitor local blood flow and skin temperature. In young subjects, continuous NIR exposure significantly increased blood flow for the first 20 min post-exposure compared to placebo. Further, in young and middle-aged subjects, intermittent exposure increased blood flow during the whole exposure period and 15 min post-exposure. In young subjects, blood flow after continuous NIR exposure was significantly higher than intermittent NIR exposure only for the first 10 min. Comparing intermittent exposure between the two age groups, the blood flow was significantly higher in middle-aged subjects. We conclude that NIR PBM increases local skin blood flow in young and middle-aged subjects. The mode of NIR irradiation and the subjects’ age influenced the local skin blood flow response. Full article