grains – Shamskm: A site to exchange knowledge and solutions

Nanocrystals Not Small Enough to Avoid Defects

By Guest PostDecember 15, 2012Scienceals, berkeley lab, bin chen, computer simulation, crystal, defect, dislocation, gas turbine, grains, high pressure, jet engine, jialin lei, jinyuan yan, katie lutker, mechanical properties, metal, nanocrystal, nanocrystalline nickel, nanometer, nickel, non metal, plastic deformation, protective coating, resistance, selva vennila raju, stress, ultraviolet light, waruntorn kanitpanyacharoen

Berkeley Lab Scientists at Advanced Light Source Show Dislocations Can Be Induced by Pressure in Ultrafine Nanocrystals

Nanocrystals as protective coatings for advanced gas turbine and jet engines are receiving a lot of attention for their many advantageous mechanical properties, including their resistance to stress. However, contrary to computer simulations, the tiny size of nanocrystals apparently does not safeguard them from defects.

In a study by researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab)and collaborators from multiple institutions, nanocrystals of nickel subjected to high pressure continued to suffer dislocation-mediated plastic deformation even when the crystals were only three nanometers in size. These experimental findings, which were carried out at Berkeley Lab’s Advanced Light Source (ALS), a premier source of X-rays and ultraviolet light for scientific research, show that dislocations can form in the finest of nanocrystals when stress is applied. (more…)

Ancient Popcorn Discovered in Peru

By Guest PostJanuary 26, 2012Scienceacademia nacional de la historia, andean region, ceramic pottery, coast of peru, corn microfossils, corncobs, dolores piperno, duccio bonavia, grains, huaca prieta, human welfare, husks, kernels, maize, male flowers, Mexico, panama, panama city, paredones, phytoliths, popcorn, smithsonian tropical research institute, south america, stalks, tassels, teosinte, tom dillehay, tropical ecosystem, tropical forests, tropical nature, vanderbilt university, wild grass

People living along the coast of Peru were eating popcorn 2,000 years earlier than previously reported and before ceramic pottery was used there, according to a new paper in the Proceedings of the National Academy of Sciences co-authored by Dolores Piperno, curator of New World archaeology at the Smithsonian’s National Museum of Natural History and emeritus staff scientist at the Smithsonian Tropical Research Institute.

Some of the oldest known corncobs, husks, stalks and tassels (male flowers), dating from 6,700 to 3,000 years ago were found at Paredones and Huaca Prieta, two mound sites on Peru’s arid northern coast. The research group, led by Tom Dillehay from Vanderbilt University and Duccio Bonavia from Peru’s Academia Nacional de la Historia, also found corn microfossils: starch grains and phytoliths. Characteristics of the cobs—the earliest ever discovered in South America—indicate that the sites’ ancient inhabitants ate corn several ways, including popcorn and flour corn. However, corn was still not an important part of their diet. (more…)

Tag Archives: grains

Nanocrystals Not Small Enough to Avoid Defects

Ancient Popcorn Discovered in Peru