We study the influence of oxygen vacancies on formation charged 180$^\circ$ domain walls in ferroelectric BaTiO$_3$ using first principles calculations. show that it is favorable for to assemble crystallographic planes, and such clustering accompanied by a wall. The wall has negative bound charge, which compensates nominal positive charge leads vanishing density free at This contrast positively...

For more than a century, the common ancestor of flowering plants was thought to have had a seven-celled, eight-nucleate Polygonum-type female gametophyte. It is now evident that not one, but in fact three, patterns of female gametophyte development and mature structure characterize the common ancestors of the four most ancient clades of extant angiosperms: Amborella-type, Nuphar/Schisandra-type...