Cleavage cracking across twin boundaries in freestanding silicon thin films is investigated in a microtensile fracture experiment. If the twist misorientation is relatively small, the crack front transmission can be quite smooth; otherwise the fracture surface may be either planar or broken down into parallel terrains. In all the cases, the local fracture resistance tends to increase. PACS 62.2...

This paper focuses on the analysis of the partial differential equations arising from a new approach to modeling brittle fracture based on an extension of continuum mechanics to the nanoscale. It is shown that ascribing constant surface tension to the fracture surfaces and using the appropriate crack surface boundary condition given by the jump momentum balance, leads to a sharp crack opening p...

Freeze-fracture techniques have been used to maintain chemical heterogeneity of frozen-hydrated mammalian cells for static TOF-SIMS imaging. The effects the fracture plane has on scanning electron microscopy and dynamic SIMS images of cells have been studied, but the implications this preparation method has on static SIMS have not been addressed to date. Interestingly, the chemical specificity ...

Dynamics of amorphization and fracture in SiSe 2 nanowires are studied using the molecular-dynamics method. We find that fracture is initiated in an amorphous region at the nanowire surface. Local amorphization propagates across the nanowire while multiple cracks start at the boundaries of the amorphous region. Results for the time evolution of amorphization, crack propagation, and fracture are...

AIM This was to evaluate the effect of different thicknesses of cavity walls on fracture strength of pulpotomized primary molar teeth with class II amalgam restorations. METHODS 80 carious extracted human primary molar teeth were selected for pulpotomy preparation. The teeth were divided into four groups. Mesio- or disto-occlusal (20 teeth) and mesio-occluso-distal (20 teeth); cavities were p...

The receptor-rich postsynaptic membrane of the elasmobranch electric organ was fixed by quick-freezing and then viewed by freeze-fracture, deep-etching and rotary-replication. Traditional freeze-fracture revealed a distinct, geometrical pattern of shallow 8.5-nm bumps on the E fracture-face, similar to the lattice which has been seen before in chemically fixed material, but seen less clearly th...

BACKGROUND No clinical data for the relationship of pronator quadratus (PQ) muscle to distal radius had been reported. The aim of this study was to investigate the anatomical features of the PQ muscle related to plate osteosynthesis for distal radius fractures in clinical cases. The feasibility of PQ muscle sparing surgery was investigated as well. METHODS Fifty two distal radius fractures (2...

formation has proved that it is chiefly derived from the bone itself, growing from every surface in the most suitable pabulum, namely blood-clot at the site of fracture ; that one has on several occasions seen compact bone exposed in a compound fracture and apparently necrotic, revitalised by vascular permeation throughout its whole extent; that in the comminuted simple fracture, which almost i...