Prototype of single ion heat engine created

Scientists at Johannes Gutenberg University Mainz (JGU) and the University of Erlangen-Nuremberg are working on a heat engine that consists of just a single ion. Such a nano-heat engine could be far more efficient than, for example, a car engine or a coal-fired power plant. A usual heat engine transforms heat into utilizable mechanical energy with the corresponding efficiency of an Otto engine amounting to only about 25 percent, for instance. The proposed nano-heat engine consisting of a single calcium ion would be much more efficient. The main aim of the research being conducted is to better understand how thermodynamics works on very small scales. A pilot prototype of such a single-ion heat engine is currently being constructed at Mainz University.As the physicists explain in an article recently published in the journal Physical Review Letters, the efficiency of heat engines powered by thermal heat reservoirs is determined by the second law of thermodynamics, one of the fundamental concepts in physics. It was as far back as 1824 that Frenchman Nicolas Carnot calculated the maximum possible efficiency limit of such engines, now known as the Carnot limit. In the case of the newly proposed nano-heat engine, the scientists have been theoretically able to exceed the classic Carnot limit by manipulating the heat baths and exploiting nonequlibrium states.Calculations and simulations made about a year ago showed for the first time that the thermo-dynamic flow in an internal combustion engine could be reproduced using individual ions. The idea was to use a calcium 40 ion, which has a diameter a million times smaller than that of a human hair, for this purpose. “Individual ions can basically act as the piston and drive shaft or, in other words, represent the entire engine,” explained Johannes Ronagel of the Quantum, Atomic, and Neutron Physics (QUANTUM) work group of the JGU Institute of Physics. …

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Greenland ice is melting — even from below: Heat flow from the mantle contributes to the ice melt

Aug. 11, 2013 — The Greenland ice sheet is melting from below, caused by a high heat flow from the mantle into the lithosphere. This influence is very variable spatially and has its origin in an exceptionally thin lithosphere. Consequently, there is an increased heat flow from the mantle and a complex interplay between this geothermal heating and the Greenland ice sheet. The international research initiative IceGeoHeat led by the GFZ German Research Centre for Geosciences establishes in the current online issue of Nature Geoscience that this effect cannot be neglected when modeling the ice sheet as part of a climate study.Share This:The continental ice sheets play a central role in climate. Interactions and feedback processes between ice and temperature rise are complex and still a current research topic. The Greenland ice sheet loses about 227 gigatonnes of ice per year and contributes about 0.7 millimeters to the currently observed mean sea level change of about 3 mm per year. Existing model calculations, however, were based on a consideration of the ice cap and considered the effect of the lithosphere, i.e. Earth’s crust and upper mantle, too simplistic and primarily mechanical: the ice presses the crust down due to its weight. GFZ scientists Alexey Petrunin and Irina Rogozhina have now coupled an ice/climate model with a thermo-mechanical model for the Greenland lithosphere. …

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It’s not just the heat, it’s the ozone: Hidden heat wave dangers exposed

July 19, 2013 — During heat waves — when ozone production rises — plants’ ozone absorption is curtailed, leaving more pollution in the air.This resulted in the loss of an estimated 460 lives in the UK in the hot summer of 2006.Vegetation plays a crucial role in reducing air pollution, but new research by the Stockholm Environment Institute (SEI) at the University of York shows that they may not protect us when we need it most: during extreme heat, when ozone formation from traffic fumes, industrial processes and other sources is at its worst.The reason, explained lead author Dr Lisa Emberson, is that during heat waves — when the ground is especially dry — plants become stressed and shut their stomata (small pores on their leaves) to conserve water. This natural protective mechanism makes them more resilient to extreme heat and high ozone levels, but it also stops them from absorbing ozone and other pollutants.”Vegetation can absorb as much as 20 per cent of the global atmospheric ozone production, so the potential impact on air quality is substantial,” says Dr Emberson, a senior lecturer in the Environment Department at the University of York and director of SEI’s York Centre. “What we set out to do in this study was to quantify that impact in terms of increased ozone levels and the toll on human life.”The research team, which also included scientists at King’s College, London, focused on the summer of 2006, when a heat wave and drought occurred across the UK and much of Europe. They combined two models used for human health and ecosystem risk assessment to compare two scenarios, one with perfect ozone uptake by plants, and one with minimal ozone absorption.The difference between perfect and minimal uptake was equivalent to 16 days of ozone levels above the threshold for human safety across the entire UK — and as many as 20 days in the East Midlands and eastern UK. Using these same scenarios, the team also estimated that 970 premature deaths due to ozone would have occurred under minimal plant ozone uptake conditions over the June to July period; of these 460 could have been avoided if plants had been absorbing ozone at full capacity. All estimated premature deaths are in addition to human health and mortality impacts from the heat itself.”The most vulnerable people to ozone pollution are those with existing respiratory and cardiovascular diseases,” explains Dr Emberson. “For example, ground-level ozone can lead to lung inflammation, decreased lung function, and an increase in asthma attacks. That is why, during high ozone episodes, especially in urban areas, people are generally advised not to do physical activity.”The study findings were published this week in the peer-reviewed journal Atmospheric Chemistry and Physics. The research was financed by the UK Department for Environment, Food and Rural Affairs (Defra).The timing of the publication coincides with yet another major heat wave in the UK, and Dr Emberson says it is likely that ozone uptake by vegetation is once again curtailed. The extent of the problem, however, will depend on how dry the soil is, since it is the combination of heat and drought that stresses plants the most.Dr Emberson says the study highlights the importance of understanding the frequency with which such heat waves and droughts will occur in the future as well as how ozone uptake by vegetation is affected by droughts, extreme heat, and interaction with other pollutants.”The more we know, the better we will be able to judge how successful our emission reduction efforts have been so far, and whether we need additional efforts — in the UK, across Europe and beyond, since we know that pollutants such as ozone and its precursors can carried around the globe,” she says.The research can also inform public-health responses, Dr Emberson says. …

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