Computer Model Reveals Water’s ‘Split Personality’
Seemingly ordinary, water has quite puzzling behavior. Why, for example, does ice float when most liquids crystallize into dense solids that sink?
Using a computer model to explore water as it freezes, a team at Princeton Univ. has found that water’s weird behaviors may arise from a sort of split personality: at very cold temperatures and above a certain pressure, water may spontaneously split into two liquid forms.
Method Could Make Sub-wavelength Images at Radio Frequencies
Imaging and mapping of electric fields at radio frequencies (RF) currently requires the use of metallic structures such as dipoles, probes and reference antennas. To make such measurements efficiently, the size of these structures needs to be on the order of the wavelength of the RF fields to be mapped. This poses practical limitations on the smallest features that can be measured.
New theoretical and experimental work by researchers at the National Institute of Standards and Technology (NIST) and the Univ. of Michigan suggests an innovative method to overcome this limit by using laser light at optical wavelengths to measure and image RF fields. The new technique uses a pair of highly stable lasers and rubidium atoms as tunable resonators to map and potentially image electric fields at resolutions far below their RF wavelengths — though not below the much shorter wavelengths of the lasers.
Scientists at the Department of Energy’s SLAC National Accelerator Laboratory have made the first structural observations of liquid water at temperatures down to -51 F, within an elusive “no man’s land” where water’s strange properties are super-amplified.
The research, made possible by SLAC’s Linac Coherent Light Source (LCLS) X-ray laser and reported in Nature, opens a new window for exploring liquid water in these exotic conditions, and promises to improve our understanding of its unique properties at the more natural temperatures and states that are relevant to global ocean currents, climate and biology.
Clumping Density Discovery May Aid Climate Research
Particles of soot floating through the air and comets hurtling through space have at least one thing in common: 0.36. That, reports a research group at the National Institute of Standards and Technology (NIST), is the measure of how dense they will get under normal conditions, and it’s a value that seems to be constant for similar aggregates across an impressively wide size range from nanometers to tens of meters.
NIST hopes the results will help in the development of future measurement standards to aid climate researchers and others who need to measure and understand the behavior of aerosols like carbon soot in the atmosphere.
Researchers Create Ultra-thin Wires for Quantum Computing
Take a fine strand of silica fiber, attach it at each end to a slow-turning motor, gently torture it over an unflickering flame until it just about reaches its melting point and then pull it apart. The middle will thin out like a piece of taffy until it is less than half a micron across — about 200 times thinner than a human hair.
That, according to researchers at the Joint Quantum Institute at the Univ. of Maryland, is how you fabricate ultra-high transmission optical nanofibers, a potential component for future quantum information devices, which they describe in American Institute of Physics Publishing’s journal AIP Advances.
Using microscopic polymer light resonators that expand in the presence of specific gases, researchers at MIT’s Quantum Photonics Laboratory have developed new optical sensors with predicted detection levels in the parts-per-billion range. Optical sensors are ideal for detecting trace gas concentrations because of their high signal-to-noise ratio, compact, lightweight nature and immunity to electromagnetic interference.
Although other optical gas sensors had been developed before, the MIT team has conceived an extremely sensitive, compact way to detect vanishingly small amounts of target molecules.
The development of a “nanobarrel” that traps and concentrates light onto single molecules could be used as a low-cost and reliable diagnostic test.
Jeremy Baumberg and his 30-strong team of researchers at Cambridge are master manipulators of light. They are specialists in nanophotonics – the control of how light interacts with tiny chunks of matter, at scales as small as a billionth of a meter. It’s a field of physics that 20 years ago was unknown.
Feathers have long been recognized as a classic example of efficient water-shedding — as in the well-known expression “like water off a duck’s back.” A combination of modeling and laboratory tests has now determined how both chemistry — the preening oil that birds use — and the microstructure of feathers, with their barbs and barbules, allow birds to stay dry even after emerging from amazingly deep dives.
The new research, published in the Journal of the Royal Society Interface, studied how cormorants and other diving birds are able to reach depths of some 30 meters without having water permanently wet their protective feathers. The research was carried out by MIT professors Robert Cohen, Michael Rubner and Gareth McKinley; graduate students Siddarth Srinivasan and Shreerang Chhatre; Andrew Parker of London’s Natural History Museum; and two others.
Scientists are using a pioneering method of “caging” and cooling water molecules to study the change in orientation of the magnetic nuclei at the center of each hydrogen atom — a process that transforms the molecule from one form of water to another.
By trapping water molecules in carbon spheres and cooling them, scientists at the universities of Southampton, Nottingham and Columbia Univ., have been able to follow the change in form (or isomer) of the molecules. The results of this work may one day help to enhance the diagnostic power of MRI scans.
A breakthrough has been made in identifying the origin of superconductivity in high-temperature superconductors, which has puzzled researchers for the past three decades.
Harnessing the enormous technological potential of high-temperature superconductors – which could be used in lossless electrical grids, next-generation supercomputers and levitating trains – could be much more straightforward in future, as the origin of superconductivity in these materials has finally been identified.
Exploiting Quantum Entanglement May Improve Atomic Clocks
A proposed network of clocks with synchronized atoms at their hearts could be more accurate and more stable than current timekeepers, scientists say.
The proposed atomic-clock network, detailed in the current issue of Nature Physics, would exploit the curious phenomenon of quantum entanglement, whereby the properties of two or more particles can become linked and instantaneously influence one another no matter how far apart they are.
When concrete shells are constructed, they usually have to be supported by elaborate timber structures. Now a revolutionary technique, developed at the Vienna Univ. of Technology, uses inflatable air cushions instead.
Large shell structures made of concrete or stone are hardly ever built any more. The reason is that their construction requires large, expensive supporting structures. At the Vienna Univ. of Technology, a completely new construction method has been developed, which does not require any timber structures at all: a flat concrete slab hardens on the ground, and then an air cushion below the plate is inflated, bending the concrete and quickly forming a sustainable shell. Even large event halls could be built this way. In Vienna, a first experimental structure has now been built using the new method.
Scientists seeking ways to engineer the assembly of tiny particles measuring just billionths of a meter have achieved a new first — the formation of a single layer of nanoparticles on a liquid surface where the properties of the layer can be easily switched. Understanding the assembly of such nanostructured thin films could lead to the design of new kinds of filters or membranes with a variable mechanical response for a wide range of applications. In addition, because the scientists used tiny synthetic strands of DNA to hold the nanoparticles together, the study also offers insight into the mechanism of interactions of nanoparticles and DNA molecules near a lipid membrane. This understanding could inform the emerging use of nanoparticles as vehicles for delivering genes across cellular membranes.