− The authors numerically discuss the accuracy of the hardness values of standard hardness blocks by evaluating the uniformity of hardness blocks and the resolution of hardness values according to test method. As a result of reviewing the results of this evaluation and the reasonability of the currently proposed method for evaluating the uncertainty of hardness values, it is revealed that the v...

Objectives: (1) To understand what hardness is, and how it can be used to determine material properties. (2) To conduct typical engineering hardness tests and be able to recognize commonly used hardness scales and numbers. (3) To be able to understand the correlation between hardness numbers and the properties of materials (4) To learn the advantages and limitations of the common hardness test ...

A human can perceive the hardness of an object by tapping its surface. We compared the ranked subjective hardness values and physical properties of objects, including their stiffness, viscosity, density, and Shore hardness, and the frequencies and time constants of the natural vibrations caused by tapping. The stiffness, frequency, and viscosity exhibited a relatively strong positive correlatio...

In a very recent article (Torrent-Sucarrat et al., J Comput Chem 2007, 28, 574), we have shown how to evaluate the global hardness for polyatomic molecules using a hardness kernel approximation. We present here an extension of this previous work by improving the model used to evaluate the hardness kernel and the Fukui function. In addition, the concept of the local hardness is analyzed in detai...

PURPOSE Light units used for polymerization of resin composites are subject to deterioration with age, and frequent maintenance is required to maintain optimal efficacy. This study examined the efficacy of quartz-tungsten-halogen light units in private dental offices in Toronto for polymerization of resin composites. MATERIALS AND METHODS One hundred dental offices met all selection criteria ...

OBJECTIVES To establish if there is an association between ground hardness and injury risk in junior cricket. DESIGN Nested case-series of players who played matches on specific grounds with objective ground hardness measures, within a prospective cohort study of junior community club cricket players. METHODS Monitoring of injuries and playing exposure occurred during 434 matches over the 2...