Strain-Dependent Resistivity of Granular Manganite Systems: A Simple Quantitative Approach

The effects of an applied strain tensor on the electrical resistivity of a manganite granular system are investigated using a simple approach describing the induced deformation in terms of the tilt angle between adjacent grains. The results obtained assuming the resistivity of each grain as given by a metallic part, coming from the inner grain, and a surface-related tunnel contribution, allow us to estimate appreciable resistivity variations even in the case of small deformation angles.

Strain Dependent Resistivity of Granular Manganite Systems: a Simple Quantitative Approach

The effects of an external strain tensor on the electrical resistivity of a manganite granular system are investigated using a simple approach describing the induced deformation in terms of the tilt angle between adjacent grains. The results obtained assuming the resistivity of each grain as given by a metallic part, coming from the inner grain, and a surface related tunnel contribution, allow to estimate appreciable resistivity variations even in the case of small deformation angles.

Lightweight and reliable metal–composite joints based on harmonization of strength properties of joined parts

One of the key problems of designing composite primary aircraft structures is the problem of development of lightweight and reliable joints for such structures. For conventional bolted joints used for connection of laminated composite primary structure elements, the loads are transferred via the contact of metallic and composite parts having considerably different strength and stiffness parameters. As the local strength properties of composites are defined by polymer resins, having several times less strength as compared to the metallic alloys, the maximal load that can be transferred via the joint is limited by the properties of resins. As a consequence, the metallic parts of such joints are loaded to a very low extent, that causes low weight efficiency. In the presented paper, the approach to development of metal–composite joints based on the principle of harmonization is proposed. The harmonization principle is to minimize the disbalance of strength properties of metallic and composite parts in the local zones of contact. This principle can be realized by two ways: either by removing the resin from the zone of contact to increase local stiffness of composite part (“stiff” joint concept) or by creation of metallic part with porous structure to decrease local stiffness of the metallic part (“soft” joint concept). In this paper, the evaluation of both concepts is given, based on numerical and experimental investigations carried out in this work.

Aesthetics and Survival of Immediately Restored Implants in Partially Edentulous Anterior Maxillary Patients

This retrospective study was undertaken to determine survival rates and aesthetic outcomes of immediate placement of multiple implants at anterior maxilla sites. One hundred and eighteen implants placed in 39 patients (21 women and 18 men; average age 58.3 years) were immediately restored (24–72 h after placement). Aesthetic assessment, radiographic bone loss, and biological and prosthetic complications were evaluated. Data collection between 12 and 84 months (mean 32.2 ± 18) after final prosthetic installation revealed that no implants were lost, and that 106/118 (89.8%) implants had no more than 1.5 mm of bone loss by the end of the first year and an additional 0.2 mm for each successive year. The marginal bone loss was higher for extractions due to periodontitis compared to extractions due to caries (mean mesial loss of 1.37 mm vs. 1.01 mm, respectively, and mean distal loss of 1.37 mm and 0.99 mm, respectively, p = 0.001). The mesial papilla was present in 83/118 implants (70.3%), while the distal papilla was present in 76/118 implants (64.4%). The cervical metallic part of the abutment was exposed in 16/118 (13.5%) implants. There was a higher ratio of recessions and missing papillae in patients in whom the extractions were performed due to periodontal reasons. Within the limitations of the present study, aesthetic and radiographic parameters support immediate restoration of partially edentulous maxillae.

Thermal Cycling Influence on the Transformation Characteristics of a Ni50Ti48Nb2 Shape Memory Alloy

The alloy was chosen in order to obtain a shape memory alloy having a wider hysteresis than equiatomic NiTi, that involves a better thermo-mechanical stability. Two samples investigated by differential scanning calorimetry (DSC) were previously annealed at 800oC/12 h and, respectively, 900 �C/12 h followed by furnace cooling. These were afterwards submitted to thermal cycling. The thermal cycling of a Ni50Ti48Nb2 alloy sample previously annealed at 900 �C/12 h results in lower critical points and higher hysteresis values as compared to those of the sample annealed at 800�C/12h, also submitted to thermal cycling. Thus, annealing a metallic part made of such an alloy at 900� C/12 h followed by thermal cycling prior to putting it into service enhances its reliability.

Corrosion Problems in Incinerators and Biomass-Fuel-Fired Boilers

Incinerators are widely used to burn the municipal waste, biowaste, wood, straw, and biomedical waste. Combustion of these types of waste results in generation of chlorides of sodium and potassium which may attack the metallic part of the incinerator. In biofuel-fired boilers, similar type of highly corrosive environment is present. Attempt has been made to review the corrosion problems and their solutions as per the available literature.