. AbstrAct Objective. In clinical practice, core material can be exposed after adjustments, which may result in loss of ceramic glaze. The objective of this study is to evaluate the effect of surface roughness on the flexural strength and fracture toughness of In-Ceram zirconia core material. Materials and methods. Forty In-Ceram zirconia specimens were prepared and divided into two main groups...

Mineralized collagen fibrils are composed of tropocollagen molecules and mineral crystals derived from hydroxyapatite to form a composite material that combines optimal properties of both constituents and exhibits incredible strength and toughness. Their complex hierarchical structure allows collagen fibrils to sustain large deformation without breaking. In this study, we report a mesoscale mod...

A graph is t-tough if the number of components of G\S is at most |S|/t for every cutset S ⊆ V (G). A k-walk in a graph is a spanning closed walk using each vertex at most k times. When k = 1, a 1-walk is a hamilton cycle, and a longstanding conjecture by Chvátal is that every sufficiently tough graph has a 1-walk. When k ≥ 3, Jackson and Wormald used a result of Win to show that every sufficien...

Perfect graphene is believed to be the strongest material. However, the useful strength of large-area graphene with engineering relevance is usually determined by its fracture toughness, rather than the intrinsic strength that governs a uniform breaking of atomic bonds in perfect graphene. To date, the fracture toughness of graphene has not been measured. Here we report an in situ tensile testi...

Ferroelectric ceramics are used in applications ranging from actuators and sensors to ultrasonic motors. A significant shortcoming of these materials in structural applications is their inherent brittleness. Specifically, most ferroelectrics have fracture toughness levels on the order of KIc MPa m = 1 . The characteristic of ferroelectric ceramics that makes them useful as smart materials is th...

Let τ(G) and bind(G) be the toughness and binding number, respectively, of a graph G. Woodall observed in 1973 that τ(G) > bind(G) − 1. In this paper we obtain best possible improvements of this inequality except when (1+ √ 5)/2 < bind(G) < 2 and bind(G) has even denominator when expressed in lowest terms.

The indentation method has been widely used to measure the fracture toughness in fragile materials due to its simplicity and that only needs of a small sample. However, it is well known that the fracture toughness values obtained by indentation methods can be substantially different from the values obtained from more rigorous methods which are based on a precise knowledge of all parameters invo...

Microencapsulated dicyclopentadiene (DCPD) healing agent and Grubbs’ Ru catalyst are incorporated into an epoxy matrix to produce a polymer composite capable of self-healing. The fracture toughness and healing efficiency of this composite are measured using a tapered double-cantilever beam (TDCB) specimen. Both the virgin and healed fracture toughness depend strongly on the size and concentrati...

SRI International has investigated the feasibility of measuring representative toughness values for nuclear pressure vessel materials using small cracked round bars (CRBs). We tested a weldment material [Heavy-Section Steel Irradiation (HSSI) Weld 72W with 0.23% copper] at six temperatures (-150%, -800, -500, 00, 230, and 50'C) using CRBs and compared the fracture-toughness results with data ob...

OBJECTIVE Athlete development and management encompass a complex interaction of biological, psychological, and social factors. Within elite sport, multidisciplinary sport science and medicine teams play an important role in achieving an optimal balance between preventing athlete ill-health and optimizing health and performance. The psychological aspects of athlete health and performance have ga...