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The effective detection and imaging of near-surface micro defects has been the key problem in the ultrasonic inspection field for a long time. Laser ultrasound has high resolution and sensitivity which is the effective technology to detect micro defects. In this paper, the time and frequency domain characteristics of the picosecond laser ultrasound and the interaction mechanism between micro defects and ultrasonic waves are studied by simulation and experiment. A picosecond pulsed laser is used to excite ultrasonic waves in samples with near-surface micro defects of different depths, and the propagating ultrasonic waves are detected by an optical interferometer. Through the analysis of the experimental results, the near-surface micro defects with diameters of 0.13 mm and depths of 0.3 mm, 0.5 mm, 1 mm and 2 mm can be detected. In addition, a defect imaging algorithm combining principal component subtraction (PCS) and synthetic aperture focusing technique (SAFT) is proposed, which can effectively suppress the detection blind areas and artifacts caused by Rayleigh (R)-wave interference. Compared with the conventional total focusing method (TFM) of water-immersion ultrasound, the average SNR is increased by 25.57 dB. This research is poised to contribute to the resolution of quality assessment challenges in product manufacturing and service processes.
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http://dx.doi.org/10.1016/j.ultras.2025.107672 | DOI Listing |
ACS Appl Mater Interfaces
September 2025
Surface Science Laboratory, Department of Materials and Geosciences, Technical University of Darmstadt, Peter-Grünberg-Straße 4, 64287 Darmstadt, Germany.
The performance of NiO-based electrocatalysts for the oxygen evolution reaction (OER) is strongly influenced by the interface between the metal support (current collector) and the catalyst layer, which modulates electronic properties and electrochemical activity. This study systematically investigates the solid-solid interface behavior of NiO thin films prepared by reactive magnetron sputtering on Pt, Au, and Ni, followed by electrochemical characterization. Stepwise NiO deposition and X-ray photoelectron spectroscopy reveal distinct band alignment and electronic structure differences at the metal-catalyst interface.
View Article and Find Full Text PDFAdv Mater
September 2025
Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education of China, School of Physics and Technology, Wuhan University, Wuhan, 430072, China.
Sequential deposition technique is widely used to fabricate perovskite films with large grain size in perovskite solar cells (PSCs). Residual lead halide (PbI) in the perovskite film tends to be decomposed into metallic lead (Pb) under long-term heating or light soaking. Here, a chiral levetiracetam (LEV) dopant containing α-amide and pyrrolidone groups is introduced into the PbI precursor solution.
View Article and Find Full Text PDFAdv Mater
September 2025
Key Laboratory of In-Fiber Integrated Optics of Ministry of Education, College of Physics and Optoelectronic Engineering, Harbin Engineering University, Harbin, 150001, China.
Recently, joint replacement surgery is facing significant challenges of patient dissatisfaction and the need for revision procedures. In-situ monitoring of stress stability at the site of artificial joint replacement during postoperative evaluation is important. Mechanoluminescence (ML), a novel "force to light" conversion technology, may be used to monitor such bio-stress within tissues.
View Article and Find Full Text PDFNanoscale
September 2025
School of Mechanical Engineering, Shandong University of Technology, Zibo 255000, China.
Metal matrix composites are widely employed in aerospace and marine engineering due to their excellent mechanical properties and chemical stability. However, their surfaces remain vulnerable to corrosion, icing, and mechanical wear, severely compromising long-term reliability in harsh environments. Inspired by natural superhydrophobic surfaces such as lotus leaves, functional interfaces with high water repellency and interfacial stability can be engineered through the synergistic design of hierarchical micro/nanostructures and low-surface-energy chemical modifications.
View Article and Find Full Text PDFJ Clin Periodontol
September 2025
Central Laboratory, Peking University School and Hospital of Stomatology, Beijing, China.
Aim: To investigate the functional significance of mitophagy in age-related osteogenic decline and the underlying mechanisms using in vivo and in vitro models.
Materials And Methods: An alveolar bone defect model in aged mice and a serial passaging-induced ageing model of human periodontal ligament stem cells (PDLSCs) were established. Osteogenic potential in mice was assessed by micro-CT, immunofluorescence, immunohistochemical analyses and histological staining.