The Effect of Surface Polishing on the Flexural Strength of Anorthite-based Porcelainised Stoneware

The effect of surface polishing on the flexural strength of anorthite based porcelainised stoneware was studied. The flexural strength results obtained from both polished and unpolished samples were analysed by using Weibull statistical method. The state of surfaces and microstructures of polished and unpolished samples were also characterised by profilometry and scanning electron microscopy. Typical flexural strength value obtained from anorthite based stoneware body fired at 1210°C was about 100 MPa. The average flexural strength (σ_{m}) and Weibull modulus (m) values for as fired, ground, and ground and polished specimens increased sequentially with polishing degree. The surface roughness measurements and microstructure observations showed that the severity of the surface flaws declined as the polishing process proceeded. The obtainment of better strength behaviour with polishing was attributed to high crystalline to glassy phase ratio of the anorthite based porcelainised stoneware together with the formation of network structure of these anorthite crystals

Origin and spread of human mitochondrial DNA haplogroup U7

Human mitochondrial DNA haplogroup U is among the initial maternal founders in Southwest Asia and Europe and one that best indicates matrilineal genetic continuity between late Pleistocene hunter-gatherer groups and present-day populations of Europe. While most haplogroup U subclades are older than 30 thousand years, the comparatively recent coalescence time of the extant variation of haplogroup U7 (∼16-19 thousand years ago) suggests that its current distribution is the consequence of more recent dispersal events, despite its wide geographical range across Europe, the Near East and South Asia. Here we report 267 new U7 mitogenomes that - analysed alongside 100 published ones - enable us to discern at least two distinct temporal phases of dispersal, both of which most likely emanated from the Near East. The earlier one began prior to the Holocene (∼11.5 thousand years ago) towards South Asia, while the later dispersal took place more recently towards Mediterranean Europe during the Neolithic (∼8 thousand years ago). These findings imply that the carriers of haplogroup U7 spread to South Asia and Europe before the suggested Bronze Age expansion of Indo-European languages from the Pontic-Caspian Steppe region. © The Author(s) 2017