Ever since the late 19th century, physicists have known about a counterintuitive property of some electric circuits called negative resistance. Typically, increasing the voltage in a circuit causes the electric current to increase as well. But under some conditions, increasing the voltage can cause the current to decrease instead. This basically means that pushing harder on the electric charges actually slows them down
Their invention looks a lot like a solar panel. A flat metal panel is covered in a sheet of the material—a high-tech film—the trio invented. The material reflects the light and heat of the sun so effectively that the temperature beneath the film can drop 5 to 10-degrees Celsius (9 to 18-degrees Fahrenheit) lower than the air around it. A system of pipes behind the metal panel are exposed to that colder temperature, cooling the fluid inside before it’s sent out to current-day refrigeration systems.
Above a certain temperature, it becomes possible to replace the steam with supercritical carbon dioxide. This works more efficiently, potentially providing a boost of more than 20 percent, but it requires temperatures in excess of 1,000K. That makes things a bit more challenging, given that many metals will melt at such temperatures; others will react with carbon dioxide under these conditions. Finding a material that could work involves balancing a lot of factors, including heat and chemical resistance, ea
The lens is quite unlike the curved disks of glass familiar from cameras and binoculars. Instead, it is made of a thin layer of transparent quartz coated in millions of tiny pillars, each just tens of nanometres across and hundreds high.
Singly, each pillar interacts strongly with light. Their combined effect is to slice up a light beam and remould it as the rays pass through the array
“The quality of our images is actually better than with a state-of-the-art objective lens. I think it is no exaggeration to say that this is potentially revolutionary.”
Previously scientists at IBM and other institutes have successfully demonstrated the ability to store 1 bit per cell in PCM, but today at the IEEE International Memory Workshop in Paris, IBM scientists are presenting, for the first time, successfully storing 3 bits per cell in a 64k-cell array at elevated temperatures and after 1 million endurance cycles.
“Phase change memory is the first instantiation of a universal memory with properties of both DRAM and flash, thus answering one of the grand challenges of our industry,” said Dr. Haris Pozidis, an author of the paper and the manager of non-volatile memory research at IBM Research – Zurich. “Reaching 3 bits per cell is a significant milestone because at this density the cost of PCM will be significantly less than DRAM and closer to flash.”
Diamond, being the world’s hardest substance, has a range of uses in creating cutting and polishing tools across industries from mining to medicine. The challenge is that diamond is expensive to mine and to manufacture, requiring high temperatures and high pressures. But by mixing up the substrates and controlling the rate of cooling, Narayan and his team have discovered they can create tiny diamonds within the Q-carbon.
For decades, metrologists have strived to retire ‘Le Grand K’ — the platinum and iridium cylinder that for 126 years has defined the kilogram from a high-security vault outside Paris. Now it looks as if they at last have the data needed to replace the cylinder with a definition based on mathematical constants.
If they are proved right, in 2018, Le Grand K will join the metre as a museum piece. “We’ll keep it,” says Davis, “but it won’t be defining anything anymore.”
Because these new magnets also have energy efficient characteristics, they can be used to create a new generation of sensors and actuators with vanishingly small heat signatures, said the researchers. These magnets could also find applications in efficient energy harvesting devices; compact micro-actuators for aerospace, automobile, biomedical, space and robotics applications; and ultra-low thermal signature actuators for sonars and defense applications.
Since these new magnets are composed of alloys that are free of rare-earth elements, they could replace existing rare-earth based magnetostriction alloys, which are expensive and feature inferior mechanical properties, said researchers.
In very simple terms, when that happens, material properties such as resistance no longer depend on the length scales involved. So if electrons move without resistance on a tiny scale, they should also move without resistance on much larger scales too. Hence the phenomenon of superconductivity.
“We have described how it is possible for unparticles in strongly correlated matter to mediate superconductivity,” say LeBlanc and Grushin.
Normally, Fang explains, stiffness and strength declines with the density of any material; that’s why when bone density decreases, fractures become more likely. But using the right mathematically determined structures to distribute and direct the loads — the way the arrangement of vertical, horizontal, and diagonal beams do in a structure like the Eiffel Tower — the lighter structure can maintain its strength.