In this article, an experimentally validated model is proposed in order to take into account main sources of performance degradation that could be experienced by friction-based devices during a seismic event. Particular attention is dedicated to the degradation of friction characteristics due to repetition of cycles and consequent temperature rise. This effect can be responsible for overestimate of the dissipation capacity of the device. The proposed model of frictional behavior is suitable for immediate implementation in generalized structural analysis codes and provides an important design tool for realistic assessment of the seismic response of structures equipped with friction-based isolators.

M-Wire instruments benefitted primarily through higher material flexibility while still at low deflection levels, compared with conventional NiTi alloy. At fracture, the instruments did not take complete advantage of the enhanced fractural resistance of the M-Wire material, which determines only limited improvements of the torsional performance.

The aim of this study was to investigate and compare, via finite element analysis (FEA), the effects of endodontic access and canal preparation on stress distribution under functional loading of a mandibular molar treated with novel (TRUShape) and conventional (Vortex) rotary root canal preparation instruments. Identical plastic mandibular molars with natural anatomy had all 4 canals shaped with either TRUShape or a conventional rotary, Vortex (#20 and #30, both by Dentsply Tulsa Dental). Finite element analysis was used to evaluate stress distribution in untreated and treated models. Micro-computed tomography (MCT) of the extracted teeth shaped in vitro was used to inform the FEA model regarding the geometry of root canals and external surfaces. Modeling the intact periodontal support and cancellous/cortical bone was based on anatomical data. Profiles of average and maximum von Mises stresses in dentin of the four treated conditions under functional loading were compared to the untreated model. This comparison was performed for each tooth model with and without root canal obturation and composite restoration. On average, the dentin sections with the most changes after preparation were located in the access cavity, with average stress increase up to +5.7, +8.5, +8.9, and +10.2 % for the TRUShape #20, Vortex #20, TRUShape #30 and Vortex #30, respectively, relative to the untreated model. Within the root canal system, the average stress differences were smaller than <5 % with lower values for TRUShape preparation. A reduction of the average stress in the access cavity was observed as an effect of the composite restoration, while about the same von Mises stress' profiles were found into the root canal. In this finite element analysis, preparation of the access cavity resulted in increased von Mises stresses under functional occlusal load. The limited (up to 0.7 %) retained radicular dentin in the TRUShape versus the Vortex cavity proved effective in reducing masticatory stresses. The bonded restoration modeled in this study only partially counterbalance the combined effects of access cavity and root canal preparation.

SUMMARY This paper deals with a procedure for the identification of the damage in bridge structures equipped with isolators and/or energy dissipating devices. The procedure is based on the availability of accelerometric records from any simple sensor network installed on existing bridges. The proposed algorithm provides an assessment of the performance degradation of conventional structural components as well as installed isolators and energy dissipators, obtained from changes in modal characteristic of the structural response. A new index localization and severity index is introduced to be used for ordinary structural elements and anti‐seismic devices. For the validation of the procedure, the algorithm has been applied to a continuous beam as well as to a bridge structure equipped with Friction Pendulum devices. The proposed procedure shows a high level of accuracy in the damage localization and severity assessment also in a complex scenario of damage. The severity index is also interpreted in terms of physical quantities (e.g. friction coefficient) representative of the specific device performance. For this reason the procedure appears feasible for implementation on real structures with the advantage of providing direct indicators of the early stages of degradation of performance parameters. This information can be used to design inspection and maintenance plans. Copyright © 2011 John Wiley & Sons, Ltd.

The epidemiology of valvular heart disease has significantly changed in the past few decades with aging as one of the main contributing factors. The available options for replacement of diseased valves are currently limited to mechanical and bioprosthetic valves, while the tissue engineered ones that are under study are currently far from clinical approval. The main problem with the tissue engineered heart valves is their progressive deterioration that leads to regurgitation and/or leaflet thickening a few months after implantation. The use of bioresorbable scaffolds is speculated to be one factor affecting these valves' failure. We have previously developed a non-degradable superelastic nitinol mesh scaffold concept that can be used for heart valve tissue engineering applications. It is hypothesized that the use of a non-degradable superelastic nitinol mesh may increase the durability of tissue engineered heart valves, avoid their shrinkage, and accordingly prevent regurgitation. The current work aims to study the effects of the design features on mechanical characteristics of this valve scaffold to attain proper function prior to in vivo implantation.