Search Results (1,714)

In this study, a novel Bi₂O₃/BiOBr_0.9I_0.1 (BO0.9−BBI0.1) composite photocatalyst was successfully synthesized via a single-pot solvothermal method for the efficient degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under visible light. The structure, morphology, and optical properties of the photocatalyst were characterized through X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra (DRS), Steady-state photoluminescence (PL), and Electrochemical Impedance Spectroscopy (EIS). The composite exhibits a 3D hierarchical morphology with increased specific surface area and optimized pore structure, enhancing pollutant adsorption and providing more active sites. Under visible light irradiation, BO0.9−BBI0.1 achieved a 92.4% removal rate of 2,4-D within 2 h, with a reaction rate constant 5.3 and 4.6 times higher than that of pure BiOBr and BiOI, respectively. Mechanism studies confirm that photogenerated holes (h⁺) and superoxide radicals (·O₂⁻) are the primary active species, and the Z-scheme charge transfer pathway significantly promotes the separation of electron-hole pairs while maintaining strong redox capacity. The catalyst also demonstrated good stability over multiple cycles. This work provides a feasible dual-modification strategy for designing efficient bismuth-based photocatalysts for pesticide wastewater treatment. Full article

The flexible positioning platform is a critical structural component in the ultra-high acceleration macro–micro motion platform, enabling precise positioning across multiple scales. However, under high-frequency start–stop cycles and prolonged multi-condition operation, it is prone to fatigue damage induced by random vibrations, which poses a threat to system reliability. This study proposes a method for evaluating and optimizing the platform’s performance under random vibration based on power spectral density (PSD) analysis. In accordance with the IEC 60068-2-64 standard, representative load spectra from Tables A.8 and A.6 were selected as excitation inputs. Frequency-domain analyses of stress, strain, and displacement were conducted using ANSYS Workbench 2022R1 in conjunction with the nCode platform, incorporating the Gaussian three-sigma probability interval. The results reveal that stress and deformation are highly concentrated in the hinge region, indicating a structural vulnerability. Fatigue life predictions were carried out using the Dirlik method and Miner’s linear damage rule under various PSD loading conditions. The findings demonstrate that hinge stiffness is a key factor influencing vibration resistance and service life. This research provides theoretical support for the design optimization of flexible structures operating in complex random vibration environments. Full article

Running shoe midsoles are designed to attenuate impact forces while maintaining or improving performance. However, the literature is equivocal, likely due to measurement systems, whereas in vitro testing is conclusively favourable. This study investigated three densities of ATPU foam, comparing in vitro mechanical properties with in vivo plantar force spectral characteristics derived from individualised pressure distributions during treadmill running at varied speeds. In vitro results of slab foam and shoes showed strong positive relationships between impact variables normalised to total impact energy and foam density (r² > 0.90), and strong negative relationships for time-domain variables normalised to deformation (mm) as density increased (r² > 0.89). During running, lower midsole density increased ground contact time across speeds (p = 0.041), while spatially resolved high-frequency PSD and peak impact force both decreased (p = 0.043; p = 0.030). However, there were no differences between total vertical force and midsole density (p = 0.232). Relationships between in vitro Peak G and high-frequency PSD were strong across all speeds (r² = 0.63–0.91). Conversely, reducing midsole density increased active peak force across speeds (p = 0.003), which was strongly related to in vitro energy return (r² > 0.89). Therefore, plantar force spectra and spatially resolved analyses demonstrate how foam density properties translate from in vitro to in vivo treadmill running, with lower-density foam improving impact attenuation but elevating propulsive forces. Future work needs to verify this in an outdoor setting. Full article

Plasmonic nanostructures support localized surface plasmon resonances (LSPRs) which exhibit intense light–matter interactions, producing unique optical features such as high near-field enhancements and sharp spectral signatures. Among these, plasmon hybridization (PH) and Fano resonance (FR) are two key phenomena that enable tunable spectral responses, yet their classification is often ambiguous when based only on geometry or extinction spectra. In this study, we systematically investigate four representative nanostructures: a simple nanogap dimer (i-type structure), a dolmen structure, a heptamer nanodisk cluster, and a nanoshell particle. We utilize discrete dipole approximation (DDA) to analyze these structures. By separating scattering and absorption spectra and introducing quantitative spectral metrics together with near-field electric-field vector mapping, we provide a unified procedure to interpret resonance origins beyond intensity-only near-field plots. The results show that PH-like behavior can emerge in a dolmen structure commonly regarded as a Fano resonator, while FR-like characteristics can appear in the i-type structure under specific conditions, underscoring the importance of scattering/absorption decomposition and vector-field symmetry. We further evaluate refractive-index sensitivities and discuss implications for plasmonic sensing design. Full article

Within the scope of the study, the parameters of friction pendulum-type (FPS) isolators used or planned to be used in different projects were evaluated specifically for the project and its location. The evaluations were conducted within a performance-based seismic design framework using displacement, re-centering, and force-based operability criteria, as implemented through the Türkiye Building Earthquake Code (TBDY) 2018. The friction coefficient and radius of curvature were evaluated, along with the lower and upper limit specifications determined according to TBDY 2018. The planned control points were the period of the isolator system, the isolator re-centering control, and the ratio of the base shear force to the structure weight. Within the scope of the study, isolator groups with different axial load values and different spectra were evaluated. A dataset was prepared by using the parameters obtained from the re-centering, period, and shear force analyses to determine the conditions in which the isolator continued to operate and those in which conditions prevented its operation. Machine learning models were developed to identify FPS isolator configurations that do not satisfy the code-based operability criteria, based on isolator properties, spectral acceleration coefficients corresponding to different earthquake levels, mean dead and live loads, and the number of isolators. The resulting Bagging model predicted an isolator’s operability with a high degree of accuracy, reaching 96%. Full article

We present E-CAHORS—a compact mid-infrared open-path diode-laser spectrometer designed for the simultaneous measurement of carbon dioxide, methane, and water vapor concentrations in the near-surface atmospheric layer. These measurements, combined with simultaneous data from a three-dimensional anemometer, can be used to determine fluxes using the eddy-covariance method. The instrument utilizes two interband cascade lasers operating at 2.78 µm and 3.24 µm within a novel four-pass M-shaped optical cell, which provides high signal power and long-term field operation without requiring active air sampling. Two detection techniques—tunable diode laser absorption spectroscopy (TDLAS) and a simplified wavelength modulation spectroscopy (sWMS)—were implemented and evaluated. Laboratory calibration demonstrated linear responses for all gases (R² ≈ 0.999) and detection precisions at 10 Hz of 311 ppb for CO₂, 8.87 ppb for CH₄, and 788 ppb for H₂O. Field tests conducted at a grassland site near Moscow showed strong correlations (R = 0.91 for CO₂ and H₂O, R = 0.74 for CH₄) with commercial LI-COR LI-7200 and LI-7700 analyzers. The TDLAS mode demonstrated lower noise and greater stability under outdoor conditions, while sWMS provided baseline-free spectra but was more sensitive to power fluctuations. E-CAHORS combines high precision, multi-species sensing capability with low power consumption (10 W) and a compact design (4.2 kg). Full article

Phosphorus-31 nuclear magnetic resonance (³¹P NMR) spectroscopy is a powerful analytical physical chemistry experimental technique that is widely used to study the structure and dynamics of phosphorus-containing compounds today. Accurate calculation of ³¹P NMR chemical shifts lies in the basis of the proper assignment of NMR signals, as they can be closely spaced to each other in the NMR spectra of systems that bear nuclei with subtly different electron environments, like complex organophosphorus compounds, nucleic acids, and phosphates, etc. The most advanced quantum chemistry (QC) methods allow us to reach the agreement between theoretical values of ³¹P NMR chemical shifts and experiments within a few ppm, which makes them a useful tool for studying chemical structure, reaction mechanisms, and catalyst design with the aid of the NMR method. This review surveys the application of both density functional and wave function methods of electron structure to the calculation of ³¹P NMR chemical shifts and proposes a thorough discussion of the latest findings related to the factors affecting the final accuracy of the ³¹P NMR chemical shifts prediction, including basis sets, the geometry factor effect, solvent, vibrational, and relativistic corrections. Full article

To address the challenge of effectively extracting early-stage failure features in rolling bearings, this paper proposes a two-stage harmonic optimization-gram method based on spectral amplitude modulation (SAM-TSHOgram). The method first employs amplitude spectra with varying weighting exponents to preprocess the signal, performing nonlinear adjustments to the vibration signal’s spectrum to enhance weak periodic impact characteristics. Subsequently, a two-stage evaluation strategy based on spectral coherence (SCoh) was designed to adaptively identify the optimal frequency band (OFB). The first stage employs the Periodic Harmonic Correlation Strength (PHCS) metric, based on autocorrelation, to coarsely screen candidate bands with strong periodic structures. The second stage utilizes the Sparse Harmonic Significance (SHS) metric, based on spectral negative entropy, to refine the candidate set, selecting bands with the most prominent harmonic features. Finally, SCoh is integrated over the selected OFB to generate an Improved Envelope Spectrum (IES). The proposed method was validated using both simulated and experimental vibration signals from bearings and gearboxes. The results demonstrate that SAM-TSHOgram significantly outperforms conventional approaches such as EES, Fast Kurtogram, and IESFOgram in terms of signal-to-noise ratio (SNR) enhancement, harmonic clarity, and diagnostic robustness. These findings confirm its potential for reliable early fault detection in rolling bearings. Full article

A precise characterization of molecular vibrations and thermodynamic properties is essential for applications in spectroscopy, computational modeling, and chemical process design. In this study, the q-deformed Tietz (qDT) oscillator is applied to examine vibrational energy spectra of diatomic molecules and thermodynamic properties of nonlinear symmetric triatomic molecules. Vibrational energy eigenvalues were obtained analytically using the improved Nikiforov-Uvarov method. The symmetric vibrational mode was described with the qDT oscillator, while asymmetric and bending modes were modeled using the rigid rotor harmonic oscillator (RRHO); translational and rotational contributions were incorporated from standard models. For diatomic molecules (BrF, CO⁺, CrO, ICl, KRb, NaBr), mean absolute percentage errors (MAPE) ranged from 0.53% to 1.73% for vibrational energy eigenvalues and 0.34% to 1.08% for potential fits. Extending the analysis to triatomic molecules, thermodynamic properties of AlCl₂, BF₂, Cl₂O, OF₂, O₃, and SO₂ were calculated with the qDT model, yielding low MAPE benchmarked against NIST-JANAF reference data: entropy 0.203% to 0.614%, enthalpy 1.792% to 5.861%, Gibbs free energy 0.419% to 1.270%, and constant-pressure heat capacity 1.475% to 4.978%. These results demonstrate the versatility and accuracy of the qDT oscillator as an analytical framework connecting molecular potentials, vibrational energies, and thermodynamic functions, providing a practical and tractable approach for modeling both diatomic and symmetric triatomic systems. Full article

Photocatalysis driven by the visible light of solar energy has received considerable attention in the field of environmental remediation and clean energy production. In this work, monomeric sulfonated palladium phthalocyanine (PdPcS) was encapsulated in zeolitic imidazolate frameworks-8 (ZIF-8) crystals (denoted PdPcS@ZIF-8) through electrostatic interaction in the ammonia system, while their photocatalytic activity was well-maintained together with the structural regularity of ZIF-8 crystals. For comparison, a PdPcS/ZIF-8 sample was obtained from the traditional impregnation method. The ¹³C NMR and UV-DRS spectra confirmed the difference between PdPcS@ZIF-8 and PdPcS/ZIF-8 in terms of the chemical environment effect for PdPcS. Under visible light, the optimal PdPcS@ZIF-8 catalyst achieved complete degradation of 0.1 mM bisphenol A in 120 min. It also exhibited excellent stability, retaining 81.5% activity after four cycles, far outperforming the impregnated sample (32.5%) due to effective encapsulation preventing PdPcS leaching. This versatile one-step synthetic strategy is expected to be useful for designing novel macromolecules@MOF composite materials. Full article

Turkey is located on an active seismic belt, making the accurate determination of soil properties and earthquake effects essential for safe and reliable structural design. This study investigates the influence of ground improvement on the dynamic behavior of the soil at the construction site of the 950-bed Aydın City Hospital. Evaluations were carried out in terms of the dominant period, local site class and spectral characteristics to assess the effectiveness of the improvement applications. For this purpose, field tests conducted before the improvement were repeated afterward and the obtained data were compared. Local site classes were determined for both unimproved and improved soil conditions based on the relevant seismic code provisions. Furthermore, using site-specific data, nonlinear time-history analyses were performed and site-specific response spectra were obtained for 11 earthquake records at DD-1 and DD-2 seismic hazard levels (return periods of 475 and 2475 years). These spectra were then compared with the corresponding design spectra. The analyses revealed that ground improvement significantly affects not only the bearing capacity and liquefaction potential but also the dynamic behavior, dominant period and local site class of the soil. Full article

This research proposes the design and implementation of an adaptive optical system (AOS) for monitoring low-orbit satellites (LOSs) to ensure that they do not deviate from their pre-planned path. This is achieved by designing a telescope with an optical system that contains six mirrors in a regular hexagonal shape; the side length of one mirror is 30 cm, and there is also a spectral analyzer system in the middle to separate the spectra emitted by stars from those reflected from low-orbit satellites. A SwinTrack-Tiny (STT) is used, with modifications using temporal information via insertion. The model incorporates a new purpose-built image update template as a third input to the model and combines the attributes of the new image with the attributes of the primary template via an attention block. To maintain the dimensions of the original model and take advantage of its weights, an attention block with four vertices is used. Full article

The ubiquitous presence of tetracycline in water sources due to its prevalent usage in antibiotics poses a potential risk to ecosystems and to human health. There is therefore a dire need for efficient methods of tetracycline removal. To this end, we constructed a series of super-small-sized BiVO₄ composites with different loading amounts of 5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt% on SiO₂ support by a hydrothermal–calcination method for efficient photocatalytic degradation of tetracycline. XRD and SEM results revealed that these composites all exhibited good crystallinity and well-dispersed morphologies. Particularly, the 20 wt% BiVO₄@SiO₂ of this series of composites showed superior photocatalytic performance, with 84.1% efficiency in tetracycline degradation, higher than any of its counterparts. This can be explained by its wide light-absorption range and high charge-separation efficiency, as confirmed by UV-Vis absorption spectra and quenched fluorescence spectra. This work offers a new method for the design and construction of tetracycline degradation photocatalysts. Full article

This study presents a green synthesis of zinc oxide (ZnO) nanoparticles (NPs) capped with Haloxylon (P1) and Calligonum (P2) extracts. The use of plant-derived biomolecules as natural capping agents offers an environmentally friendly strategy to tune surface chemistry and to enhance the photocatalytic behavior of ZnO NPs. ZnO/plant extracts nanocomposites were prepared via a hydrothermal route and systematically characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), UV–Vis spectroscopy, and photoluminescence (PL), followed by evaluation of their photocatalytic performance against methylene blue (MB) under UV irradiation. XRD confirmed a wurtzite structure with crystallite sizes ranging from 8.95 to 10.93 nm, while PL spectra indicated an improved charge carrier separation in extract-capped ZnO. The characteristics and pollutant removal performance of the greenly synthesized ZnO composites were compared with those of a chemically synthesized ZnO nanoparticles reference sample. Adsorption tests under dark conditions revealed a strong difference between the materials: ZnO-P1 removed 48% of MB, whereas ZnO-P2 adsorbed only 7%, demonstrating a much higher affinity of the Haloxylon-derived surface groups toward MB. In comparison, the chemically synthesized ZnO exhibited an adsorption capacity of 54%, confirming that the Haloxylon-mediated surface provides a comparable efficient dye uptake prior to irradiation. After UV irradiation, all samples exhibited a photocatalytic activity with a total MB removal reached ~59% for the reference ZnO sample and ~53% for ZnO-P1 compared to about 13% for the ZnO-P2. Kinetic analysis also confirmed that ZnO-P1 possessed a high degradation rate constant, indicating a better intrinsic photocatalytic efficiency in addition to the strong adsorption contribution. The enhanced performance of plant-capped ZnO is attributed to phytochemical-induced surface defects, which facilitated charge separation and boosted the generation of reactive oxygen species (ROS). Overall, these results demonstrate that Haloxylon and Calligonum extracts are effective and sustainable capping agents, providing a low-cost, eco-friendly approach for designing ZnO nanocatalysts composites with promising applications in wastewater treatment and environmental remediation. Full article

The adulteration of Zanthoxylum bungeanum powder presents a complex challenge, as current near-infrared spectroscopy (NIRS) models are typically designed for specific adulterants and require extensive preprocessing, limiting their practical utility. To overcome these limitations, this study proposes IncepSpect-CBAM, an end-to-end one-dimensional convolutional neural network that integrates multi-scale Inception modules, a Convolutional Block Attention Module (CBAM), and residual connections. The model directly learns features from raw spectra while maintaining robustness across multiple adulteration scenarios, focusing specifically on quantifying Zanthoxylum bungeanum powder content. When evaluated on a dataset containing four common adulterants (corn flour, wheat bran powder, rice bran powder, and Zanthoxylum bungeanum stem powder), the model achieved a Root Mean Square Error of Prediction (RMSEP) of 0.058 and a coefficient of determination for prediction (${{\displaystyle \mathrm{R}}}_{\mathrm{P}}^2$) of 0.980, demonstrating superior performance over traditional methods including Partial Least Squares Regression (PLSR) and Support Vector Regression (SVR), as well as deep learning benchmarks such as 1D-CNN and DeepSpectra. The results establish that the proposed model enables high-precision quantitative analysis of Zanthoxylum bungeanum powder content across diverse adulteration types, providing a robust technical framework for rapid, non-destructive quality assessment of powdered food products using near-infrared spectroscopy. Full article