A long-standing controversy exists between molecular dynamics simulations and experiments on the twinning propensity of nanocrystalline (NC) face-centered-cubic metals. For example, three-dimensional molecular dynamics simulations rarely observed twins in NC Ni, whereas experiments readily observed them. Here this discrepancy is resolved by experimental observation of an inverse grain-size effe...

BACKGROUND Until now, little was known about the variation in incidence of twin births across developing countries, because national representative data was lacking. This study provides the first comprehensive overview of national twinning rates across the developing world on the basis of reliable survey data. METHODS Data on incidence of twinning was extracted from birth histories of women a...

Owing to its HCP crystallography, deformation mechanisms of magnesium involve both plastic slip and deformation twinning. In order to understand and ultimately to predict the mechanical response of Mg and Mg alloys, any effective continuum model should not only describe the intricate interaction mechanisms between plastic slip and twinning, but also be able to capture the different length scale...

Common knowledge of over a century has it that monozygotic and dizygotic twinning events occur by unrelated mechanisms: monozygotic twinning 'splits' embryos, producing anomalously re-arranged embryogenic asymmetries; dizygotic twinning begins with independent ovulations yielding undisturbed parallel embryogeneses with no expectation of departures from singleton outcomes. The anomalies statisti...

When a strongly textured hexagonal close packed (HCP) metal is loaded under an orientation causing profuse twinning or detwinning, the stress-strain curve is sigmoidal in shape and inflects at some threshold. Authors have largely attributed the dramatic stress increase in the lower-bound vicinity of the inflection point to a combined effect of a Hall-Petch mechanism correlated to grain refineme...

A recently developed crystal based continuum model for twinning and phase transformations is successfully applied to Dauphiné twinning and the α (trigonal) ↔ β (hexagonal) phase transformation in quartz. Both finite element and uniform deformation simulations are performed of quartz polycrystals and several experimentally observed phenomena are qualitatively reproduced. Results are given for me...

Deformation twinning, which is a type of plastic deformation, has been particularly investigated in metal materials. However, only a few examples are found in organic solids. We observed mechanical twinning deformation on a simple ferrocene crystal, which is considered the most representative organometallic compound, and evaluated the crystal structures under the twinning state and the shear de...

Twinning induced plasticity steels are austenitic alloys in which mechanical twinning is a prominent deformation mode, and which exhibit exceptional combinations of ductility, work hardening and ultimate strength. The authors develop in the present paper a crystallographic theory to enable the quantitative investigation of the role of mechanical twinning in enhancing the properties of these all...

Twinning in metals is normally a permanent plastic deformation mechanism. Here we report reversible twinning in high stacking fault energy (SFE) aluminum. Twinning and spontaneous detwinning at the crack tip have been captured in situ during tensile straining under a transmission electron microscope. Both the in situ observation and the molecular dynamics simulations reveal a two-stage detwinni...

We studied twinning and fertility indices in mothers with spontaneous monozygotic (MZ) and dizygotic (DZ) twins and in mothers who conceived their twins after the use of assisted reproduction techniques (ART). Participants in this study consisted of 8,222 and 5,505 women with spontaneous DZ and MZ offspring and 4,164 and 250 women with ART DZ and MZ twin pairs, respectively. Women were compared...