We report the existence of a stable twin defect in Fe3O4 thin films. By using aberration corrected scanning transmission electron microscopy and spectroscopy the atomic structure of the twin boundary has been determined. The boundary is confined to the (111) growth plane and it is non-stoichiometric due to a missing Fe octahedral plane. By first principles calculations we show that the local at...

The sidewall defects in high quality selective epitaxial growth ~SEG! of silicon were characterized. Three different SEG diode structures were fabricated and the bulk and perimeter defects were characterized through electrical measurements and transmission electron microscopy ~TEM!. The structures investigated were SEG grown in a 1.2 mm thick wet-etched field oxide, SEG grown in 1.2 mm thick re...

Logistic growth of diffusing reactants on spatial domains with long-range competition is studied. The bifurcations cascade involved in the transition from the homogeneous state to a spatially modulated stable solution is presented, and a distinction is made between a modulated phase, dominated by single or few wave numbers, and the spiky phase, where localized colonies are separated by depleted...

In this study, an extended stress-based forming limit diagram (FLD) for prediction of necking based on the Marciniak and Kucznski (M-K) model is represented and applied in tube hydroforming. The bulge forming of a straight tube is simulated by finite element method and verified with published experimental data. This adaptive simulation technique is based on the ability to detect the onset an...

Homozygous brachymorphic (bm/bm) mice are characterized by disproportionately short stature. Newborn bm/bm epiphyseal cartilages are shorter than normal although the cells in the different zones of growth are relatively well organized. The extracellular matrix reacts poorly with stains specific for sulfated glycosaminoglycans. The ultrastructural appearance of the cartilage matrix indicates nor...

The incorporation of intrinsic point defects into a growing crystal is affected by the presence of impurities that can react with vacancies and self-interstitials. The critical value of the ratio of the growth rate, V , to the axial temperature gradient, G, ~V/G ratio! that separates the interstitial growth mode from the vacancy growth mode, is shifted by impurities, and this effect can be desc...

Growth factors are important molecules mediating both the development as well as adaptive and pathological changes within the cardiovascular system. Growth factors therefore mediate both beneficial and nonbeneficial effects. The beneficial actions include the improvement of endothelial function, stimulation of vascular repair, the formation of new capillaries (angiogenesis), and the growth of c...

introduction : efforts are being made to improve the efficacy of biomaterials used as bone substitutes for bone regeneration in the oral and maxillofacial region. graft materials have been recently produced in iran; however, studies are required to confirm their efficacy. this study aimed to compare the histomorphometric results of using mineralized allografts produced by the hamanandsaz baft k...

supravalvar mitral ring is a rare congenital heart defect of surgical importance. the condition is characterized by an abnormal ridge of the connective tissue on the atrial side of the mitral valve. it often substantially obstructs the mitral valve inflow. we herein introduce a case of a supravalvar mitral ring in a 17-year-old male, who was admitted to our hospital with cardiac syncope. he had...