J. Jaworski, T. Trzepieciński: Faculty of Mechanical Engineering and Aeronautics, Rzeszow University of Technology, Rzeszów, Poland This paper presents the results of research on the determination of the coefficient of thermal conductivity and hot hardness of cutters made of selected grades of low-alloy high-speed steels, HS 6-5-2 and HS3-1-2. The investigations of hot hardness and yield stress...

This research characterized the effects of water quality and organism age on the toxicity of nickel (Ni) to fathead minnows (Pimephales promelas) to facilitate the accurate development of site-specific water-quality criteria. Nickel sulfate hexahydrate (NiSO4 x 6H2O) was used as the Ni source for performing acute toxicity tests (median lethal concentration after 96-h exposure [96-h LC50]) with ...

the aim of this study was to analyze the impact of green tea on dentin erosion.twelve extracted sound human premolars were immersed in coca cola with a ph of 2.8 for 5 minutes. the surface microhardness was measured with a knoop diamond under a load of 50gr/10s. the teeth were immersed in green tea (camellia sinensis) solution for one minute. the microhardness values were measured again and com...

the aim of this study was to determine the effects of 40% hydrogen peroxide and 15% carbamide peroxide on microhardness and color change of a silorane-based composite resin in comparison with two methacrylate-based composites.fifty-four disc-shaped specimens (a3 shade) were fabricated of filtek p90 (p90), filtek z350xt enamel (z350) and filtek z250 (z250) (3mespe) (n=18). the samples of each co...

this study aimed to assess the effect of chloroform, eucalyptol and orange oil solvents on the microhardness of human root dentin.sixty-eight single-rooted single-canal extracted human premolar teeth were used. tooth crowns were separated from the roots at the cementoenamel junction (cej). roots were buccolingually sectioned into mesial and distal halves. specimens were randomly divided into 5 ...

background and aim: marital conflicts are unavoidable in family life, especially between a couple employed in a stressful job such as nursing. therefore, identification and improvement of individualistic skills that can affect marital conflicts are important. the aim of the present study was to evaluate the association between resilience, psychological hardiness, and marital conflicts among nur...

The remarkable mechanical performance of biological materials is based on intricate structure-function relationships. Nanoindentation has become the primary tool for characterising biological materials, as it allows to relate structural changes to variations in mechanical properties on small scales. However, the respective theoretical background and associated interpretation of the parameters m...

Nanoindentation tests using the Berkovich indenter tip were performed on 50 and 200 nm thick polycrystalline gold films deposited on hard substrates. Gold film hardness increased with the indentation depth due to the influence of the substrate. A procedure based on the Joslin-Oliver method was introduced to correct for the substrate effect. The method utilizes the fact that the measured elastic...

Different hardness measures as Vickers, Brinell and Meyer hardness are discussed with respect to their physical interpretation. Meyer hardness is found to be best suited as a measure of plastic properties. The outline of a depth sensing nanoindentation experiment is described, and particular emphasis is given to the correct deduction of the contact area from indenter penetration data. Experimen...

This study evaluated the Knoop hardness of Enforce resin cement activated by the either chemical/physical or physical mode, and light cured directly and through ceramic (HeraCeram) or composite resin (Artglass). Light curing were performed with either conventional halogen light (QTH; XL2500) for 40 s or xenon plasma arc (PAC; Apollo 95E) for 3 s. Bovine incisors had their buccal surfaces flatte...