With ultrasonic fatigue testing (UFT), it is possible to investigate the damage initiation and accumulation from the weakest link of the composite material in the very high cycle fatigue (VHCF) regime in a shorter time frame than conventional fatigue testing. However, the thermal influence on the mechanical fatigue of composites and the scatter in fatigue data for composites under ultrasonic cyclic three-point bending loading still need to be investigated. In this study, we conducted interrupted constant-amplitude fatigue experiments on a carbon-fiber satin-fabric reinforced in poly-ether-ketone-ketone (CF-PEKK) composite material. These experiments were carried out using a UFT system, which operates at a cyclic frequency of 20 kHz with a pulse-pause sequence. Various parameters, such as the CF-PEKK specimen's surface temperature, acoustic activity, and the ultrasonic generator's input resonance parameters, were measured during cyclic loading. During experiment interruption, stiffness measurement and volumetric damage characterization in the CF-PEKK specimens using 3D X-ray microscopy (XRM) were performed. The locations of damage initiation and accumulation and their influence on the changes in in situ parameters were characterized. Under fixed loading conditions, damage accumulation occurred at different locations, leading to scattering in fatigue life data. Further, the damage population decreased from the surface to the bulk of the composite material.
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http://dx.doi.org/10.3390/polym16060803 | DOI Listing |
Phytochem Anal
December 2024
School of Pharmacy, Anhui University of Chinese Medicine, Hefei, China.
Introduction: Citri Reticulatae Pericarpium (CRP), also known as Chenpi in Chinese, is the dry mature peel of Citrus reticulata Blanco or its cultivated varieties. CRP as the health-care food and dietary supplement has been widely used in various diseases. The quality of CRP can be affected by various factors, which are closely related to the metabolite composition of CRP.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
Institute of Materials Science, Technische Universität Darmstadt, Peter-Grünberg-Str. 2, D-64287, Darmstadt, Germany.
The design of cathode/electrolyte interfaces in high-energy density Li-ion batteries is critical to protect the surface against undesirable oxygen release from the cathodes when batteries are charged to high voltage. However, the involvement of the engineered interface in the cationic and anionic redox reactions associated with (de-)lithiation is often ignored, mostly due to the difficulty to separate these processes from chemical/catalytic reactions at the cathode/electrolyte interface. Here, a new electron energy band diagrams concept is developed that includes the examination of the electrochemical- and ionization- potentials evolution upon batteries cycling.
View Article and Find Full Text PDFVestn Oftalmol
December 2024
AO Meditsina (Academician Roytberg's Clinic), Moscow, Russia.
Purpose: This study was conducted to identify the group at highest risk for autoimmune inflammation through a comparative analysis among patients with chronic post-traumatic uveitis (CPTU).
Material And Methods: The clinical group included 50 patients (aged 18 to 87 years, mean age 41±2.6 years) with CPTU resulting from penetrating injury, contusion, or intraocular surgery.
BMC Oral Health
December 2024
Department of Restorative Dentistry, Faculty of Dentistry, Bolu Abant Izzet Baysal University, Bolu, Turkey.
Objective: To compare the translucency and contrast ratio of 13 different resin based restorative materials and to evaluate the effect of 2 different bleaching methods on the translucency and contrast ratio of these materials.
Methods: In this study, a total of 260 samples were prepared, 20 from each of 13 different dimethacrylate-based restorative materials. Then, each material group was divided into 4 subgroups.
J Nanobiotechnology
December 2024
State Key Laboratory of Organic-Inorganic Composites, Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology, Beijing, 100029, China.
Background: Electrospun nanofiber scaffolds have been widely used in tissue engineering because they can mimic extracellular matrix-like structures and offer advantages including high porosity, large specific surface area, and customizable structure. In this study, we prepared scaffolds composed of aligned and random electrospun polycaprolactone (PCL) nanofibers capable of delivering basic fibroblast growth factor (bFGF) in a sustained manner for repairing damaged tendons.
Results: Aligned and random PCL fiber scaffolds containing bFGF-loaded bovine serum albumin (BSA) nanoparticles (BSA-bFGF NPs, diameter 146 ± 32 nm) were fabricated, respectively.
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