A ‘strand’ of DNA as never before

(Nanowerk News) In a carefully designed polymer, researchers at the Institute of Physical Chemistry of the Polish Academy of Sciences have imprinted a sequence of a single strand of DNA. The resulting negative remained chemically active and was capable of binding the appropriate nucleobases forming a genetic code. The polymer matrix – the first of its type in history – thus functioned exactly like a sequence of real DNA Source:…

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Study: Raising Temperature Changes an Element’s Electronic “Topology”

News Writer: Robert Perkins A Fermi surface for FeTi, showing the allowable energy states that can be occupied by electrons.Credit: Courtesy of Fred Yang and Brent FultzMaterials scientists at Caltech have discovered a new way that heat tweaks the physical properties of a material.Experimenting with an alloy of iron and titanium (FeTi), a team led by Caltech’s Brent Fultz found that increasing heat alters the topology of the material’s Fermi surface—an abstract map of the allowable energy states that can be occupied by electrons.Fultz, the Barbara and Stanley R. Rawn, Jr., Professor of Materials Science and Applied Physics in the Division of Engineering and Applied Science, likens a Fermi surface to a planet covered by a smooth ocean and rocky landmasses. The ocean is made up of electrons, while the land represents voids where electrons are not present. Placing an element under extreme pressure—like that in Earth’s core—can cause landforms lurking just below the surface to emerge, in turn altering where electrons are likely to be found. The appearance of these new features in a Fermi surface is called an electronic topological transition (ETT). The concept of an ETT was proposed by the Russian physicist I. M. Lifshitz in 1960, and ETTs have been observed by subjecting metals to pressures on the order of 100,000 atmospheres.Heating causes electrons to slosh around within the Fermi surface, but, as with waves moving on water, the coastlines—the boundaries between electrons and electron-less voids—remain about the same. However, Fultz and his colleagues noticed that because heat also displaces atoms, heating can in some cases reveal landforms hidden below the surface of that metaphorical Fermi sea.In practical terms, altering the topology of the Fermi surface alters the chemical properties of a metal or alloy, which in turn alters its electrical conductivity.The potential value to engineers lies in…

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