Abstract. The physical properties of Shape Memory Alloys (SMA), useful in damping effects of scarce events as quakes, are studied for Cu-based alloys (CuAlBe) and partially for NiTi in the appropriate time scale. The evaluation ofthe deibrmation (s) in the hysteresis cycle and in their internai loops, against the thermodynamic forces, i. e. the external stress (o) and température (T) is performed. The main goal for the applicability of the alloys centers in reliable behavior after several years of inactivity. The alloy require a minimal transformation temperature change and, also, within a reduced transient time to ensure that the material always remain inside the thermoelastic window (full parent phase recovery at zero stress and without permanent deformation at maximal stress). The macroscopic behavior associated with the Clausius-Clapeyron equation, the material fatigue and the local temperature changes, produced by latent heat and by frictional contributions, are critically visualized. The microscopic phenomena related with the transient after quenched effect, the evolution in the region of phase coexistence and the long time seasonal actions in parent phase are, also, evaluated.

Objective: The objective of this study was to evaluate in vitro the shear bond strength of two types of MIM (Metal Injection Molding) technology brackets, one with conventional mesh base and the other with rail-shaped mesh base. Materials and Methods: Forty human premolars received the bonding of 2 types of brackets: Group 1- 20 Synergy metal brackets (Rocky Mountain) with conventional mesh base and Group 2-20 H4 brackets (OrthoClassic) with rail-shaped mesh base. Both brackets were bonded with Resilience photopolymerizable resin (OrthoTechnology). The specimens were coupled to a Tinius Olsen universal test machine where the shear test was performed using a chisel. In addition, the amount of remaining resin in tooth crown with the ImageJ program was evaluated and the Adhesive Remnant Index (ARI). Intergroup comparison was performed by the independent t test and Chi-square test. Results: There was no statistically significant difference between the groups for any of the measures evaluated indicating that the mesh type of the brackets’ base with MIM technology did not influence the shear bond strength of the brackets (shear bond strength, p=0.191; maximum load registered, p=0.244). There was also no difference between the percentage (p=0.602) and area of remaining resin in the teeth (p=0.805) and IRA (p=0.625) between the Synergy and H4 groups. Conclusion: Shear bond strength was similar in the two types of brackets with MIM technology evaluated. In addition, the remaining resin in the dental enamel of two types of brackets were also similar.

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<p> The building of more sustainable structures is becoming a mandatory requirement. Different alternative are followed, as the use of blended cements to diminish the CO2 emissions and energy saving, as of new reinforcement, as hot-dip galvanized, to increase the service life of reinforced concrete structures. But the effects of these changes on the technical performance of concrete structures are not determined yet. Mineral additions in high content decrease concrete mechanical strength at early ages, while the interaction between concrete and galvanized steel is different to that of carbon steel, what questions its bond strength. The present paper studies the bond developing stress of conventional and hot-dip galvanized steel reinforcement embedded in concrete made with ordinary Portland cement (OPC) and with a type of ternary blended cement containing 36% filler plus blast furnace slag. A detailed analysis of the rebars superficial geometry and pull-out tests have been carried out. Results indicate that the ribs of a hot-dip galvanized rebar are lightly wider and rounder than the ones of a conventional rebar and they present a smaller height because of the galvanized coating heterogeneity. Maximum bond stress measured for galvanized steel is similar to that of conventional reinforcement. Furthermore, greater stresses are developed when OPC concrete is used.</p>

Introduction: Brackets bonded to enamel surface depend on the adhesion material and the quality of the bracket base. Objective: The aim of this study was to compare the shear bond strength of metallic brackets with Metal Injection Molding (MIM) technology base or welded base. Materials and Methods: Forty mandibular extracted premolars mounted in acrylic resin blocks were divided randomly into two groups, both bonded with Transbond XT. In Group 1, brackets with MIM technology bases (Masel) were used, and in group 2, brackets with a welded base (Morelli) were used. After 24 hours, all brackets were tested for shear bond strength in a universal testing machine. Intergroup comparison was performed with an independent t test. Results: MIM base brackets showed a mean maximum load registered of 107.55 N, a mean shear bond strength of 9.58 MPa with a standard deviation of 5.80 MPa and the welded base brackets showed a mean maximum load of 167.37 N, a mean shear bond strength of 13.28 MPa with a standard deviation of 2.58 MPa. The difference between the two groups was statistically significant, indicating a higher shear bond strength of the welded base brackets. Conclusion: It was concluded that the brackets with welded bases presented a significantly higher shear bond strength than the brackets with MIM bases.