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1.
Angew Chem Int Ed Engl ; 62(20): e202218955, 2023 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-36919238

RESUMO

Piezocatalysis offers a means to transduce mechanical energy into chemical potential, harnessing physical force to drive redox reactions. Working in the solid state, we show here that piezoelectric BaTiO3 nanoparticles can transduce mechanical load into a flux of reactive radical species capable of initiating solid state free radical polymerization. Activation of a BaTiO3 powder by ball milling, striking with a hammer, or repeated compressive loading generates highly reactive hydroxyl radicals (⋅OH), which readily initiate radical chain growth and crosslinking of solid acrylamide, acrylate, methacrylate and styrenic monomers. Control experiments indicate a critical role for chemisorbed water on the BaTiO3 nanoparticle surface, which is oxidized to ⋅OH via mechanoredox catalysis. The force-induced production of radicals by compressing dry piezoelectric materials represents a promising new route to harness mechanical energy for solid state radical synthesis.

2.
Artigo em Espanhol | LILACS-Express | LILACS | ID: biblio-1010031

RESUMO

Objetivo.El objetivo de este estudio fue conocer y determinar la micro-deformación y distribución de los esfuerzos en el espesor de hueso maxilar anterior regenerado y reha-bilitado con un implante usando el análisis de elementos finitos (MEF). Métodos. Se modeló un espesor del hueso maxilar con regeneración ósea de 1,5 mm por vestibular con un implante dental en posición de un incisivo central superior (hueso esponjoso, cortical, hueso regenerado, implante y componentes protésicos). Las variables incluidas en el mo-delado fueron el módulo de elasticidad, la razón de Poisson para todos los componentes. Se aplicó una carga de 200 N en dirección oblicua en la superficie palatina de la corona para calcular la distribución de los esfuerzos y la micro-deformación sobre el componente implante-hueso. Resultados. Los valores de máximo esfuerzo equivalente von Mises se encontraron en el hueso cortical (44,89 MPa) que rodea el cuello del implante y se con-centraron hasta las primeras cuatro roscas del implante adyacentes al hueso nativo en la zona palatina con hueso cortical mientras en el hueso regenerado en la zona vestibular se concentró hasta la rosca seis, disminuyendo los esfuerzos (2,5 MPa), y la microdeforma-ción ósea fue mayor en el hueso cortical (943 µÎµ) comparado con el hueso nativo (214 µÎµ).Conclusiones. La distribución de los esfuerzos y micro-deformación generados en el modelo se comportaron de manera diferente según el tipo de hueso (cortical, esponjoso, regenerado), donde el hueso cortical resiste los mayores esfuerzos y micro-deformaciones, distribuyendo menos carga al hueso regenerado. Palabras clave: Análisis de elementos finitos; Módulo de elasticidad; Implantes dentales (fuente: DeCS BIREME).


Objetive. The purpose of this study was to know and determine the microstrain and stress distribution in bucal bone, regenerated and rehabilitated with an implant using the finite element analysis (FEA). Methods. The thickness of maxillar bone modeling with bucal bone regeneration was 1.5 mm with a dental implant in position of the central incisor(Cancellous, cortical and regenerated bone, implant and prosthetic components). The variables were the modulus of elasticity and Poisson`s ratio for all the components in the model. A load of 200 N was applied to the palatal surface of the crown in order to calculate the microstrain stress distribution of the bone. Results. The maximum equiva-lent stress values of von Mises were found in the cortical bone (44.89 MPa) surrounding the neck of the implant and concentrated on the first four implant threads adjacent to the native bone in the palatal area, with cortical bone, while in the regenerated bone, in the vestibular area, it was concentrated until thread six, decreasing stress (2.5 MPa), and bone microdeformation was greater in cortical bone (943 µÎµ) compared to native bone (214 µÎµ). Conclusions. The distribution of stresses and microstrain generated on the model, had different behavior depending on the type of bone (Cortical, cancellous, regenerated bone), the rigid cortical bone with bigger modulus of elasticity resisted more efforts and microstrain just like the implant that had a higher modulus of elasticiy and distributed less effort over the regenerated bone. Keywords: Elastic modulus; Dental implants; Finite element analysis (source: MeSH NLM).

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