The aim of this study was to compare the microshear bond strength of different resin cements to CAD/CAM-created lithium disilicate ceramics after 24 hours and after 1 year (10,000 thermocycles). Forty (40) ceramic bars were subjected to pretreatment comprising airborne abrasion with aluminum oxide particles, etching with 10% hydrofluoric acid and Monobond N application. Bars were divided into 4 groups (n = 10), based on cement type: light-cured Variolink Esthetic LC (VLC) and dual-cured Variolink N (VN) at two different times: after 24 hours and after 1 year. Silicone molds were used to prepare cement cylinders on a ceramic surface. The set was stored in distilled water at 37ºC, for 24 hours or subjected to 10,000 thermocycles. The molds were removed and microshear bond strength was tested. Data were submitted to two-way analysis of variance and Tukey's test (α = 0.05). Based on the comparison between cement values at different aging times (p = 0.035), VN after 24 hours (27.10 ± 0.92) and after 1 year (20.62 ± 1.25) presented significantly higher values than VLC after 24 hours (14.79 ± 0.76) and after 1 year (6.61 ± 0.81). Bond strength recorded for both cements after 24 hours (VN: 27.10 ± 0.92 and VLC: 14.79 ± 0.76) was significantly higher than the one recorded after 1 year (VN: 20.62 ± 1.25 and VLC: 6.61 ± 0.81). The thermocycling reduced the values observed for both investigated cements; bond strength was greater for dual-cure resin cement than for light-cured resin cement.
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http://dx.doi.org/10.54589/aol.34/3/226 | DOI Listing |
Int J Biol Macromol
January 2025
College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China. Electronic address:
This study investigated the effects of Chlamydomonas reinhardtii polysaccharides (CRPs) on retarding the retrogradation of japonica rice starch (JS) and glutinous rice starch (GS). Structure characterization revealed that CRPs, with an average molecular weight of 505 kDa, mainly consisted of glucose, mannose, and galactose and featured a triple-helix structure. CRPs could reduce the storage modulus increment of JS during the cooling process by interacting with amylose, thereby inhibiting gel network formation.
View Article and Find Full Text PDFSmall
January 2025
Institute of Materials for Energy and Environment, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, P. R. China.
Construction of core-shell structured electrocatalysts with a thin noble metal shell is an effective strategy for lowering the usage of the noble metal and improving electrocatalytic properties because of the structure-induced geometric and electronic effects. Here, the synthesis of a novel core-shell structured nanocatalyst consisting of a thin amorphous Pd shell and a crystalline PdCu core and its significantly improved electrocatalytic properties for both formic acid oxidation and oxygen reduction reactions are shown. The electrocatalyst exhibits 4.
View Article and Find Full Text PDFMaterials (Basel)
January 2025
Laboratoire d'Energétique et des Transferts Thermique et Massique (LETTM), Faculté des Sciences de Tunis, Université de Tunis El Manar, Campus Universitaire El-Manar, El Manar, Tunis 2092, Tunisia.
The viability of using fibers as reinforcement material for developing lightweight sustainable non-structural construction materials in compliance with the valorization of local by-products has been investigated in this work. This study aims to investigate the effect of the chemical treatment of fibers on the mechanical and hygric properties of bio-sourced clay-sand- fiber composite. This lightweight specimen has been produced from a mixture of 60% natural clay and 40% sand by mass, as a matrix, and reinforced with different amounts of Juncus fibers.
View Article and Find Full Text PDFMaterials (Basel)
December 2024
College of Civil Science and Engineering, Yangzhou University, Yangzhou 225100, China.
Polymers (Basel)
January 2025
State Key Laboratory of Chemical Safety, Qingdao 266000, China.
Polyurea (PUR) has been widely used as a protective coating in recent years. In order to complete the understanding of the relationship between PUR microstructure and its energy absorption capabilities, the mechanical and dynamic performance of PURs containing various macrodiol structural units were compared using material characterization techniques and molecular dynamic simulation. The results showed that the PUR polycarbonate diols formed as energy absorbing materials showed high tensile strength, high toughness, and excellent loss factor distribution based on the comparison of stress-strain tensile curves, glass transition temperatures, phase images, and dynamic storage loss modulus.
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