Piezoelectric performance doubles up

25 Apr 2019 Belle Dumé


Piezoelectric materials are widely employed as transducers and sensors in a variety of applications, including ultrasound medical imaging systems. Researchers have now nearly doubled the performance of a class of piezoelectrics, known as relaxor ferroelectrics, which were discovered 20 years ago, by adding trace amounts of the element samarium (Sm) to them. The rare-earth doping technique, which appears to increase local structural heterogeneity in the crystals, could be a general strategy for enhancing the piezoelectricity of these materials. Lead author of the story, Fei Li. Courtesy: Fei Li

The discovery of relaxor ferroelectric single crystals, such as Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) and Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT), was a milestone achievement in ferroelectric research, explain the researchers of Xi’an Jiaotong University in China, Pennsylvania State University in the US and the University of Wollongong in Australia. These materials, which have been optimized over time, have very high piezoelectric coefficients (the amount of charge generated for each unit of force) of 1200 to 2500 picocoulombs per newton.

Exotic nuclear decay observed in dark-matter detector

24 Apr 2019 Hamish Johnston


 

 

 Rare event: the XENON1T time projection chamber after assembly. (Courtesy: XENON Collaboration)

 

 An exotic and extremely rare nuclear decay that involves the simultaneous capture of two atomic electrons by a xenon-124 nucleus has been observed in a dark-matter detector. Physicists in the XENON Collaboration have measured the half-life of the two-neutrino double electron capture process to be about 1022 years, which is about one trillion times the age of the universe. Studying this rare decay could shed light on a related process called neutrinoless double electron capture, which if observed, would reveal important information about the nature of the neutrino that goes beyond Standard Model of particle physics.

Electron capture is a common mode of nuclear decay that occurs when an atomic electron interacts with a proton in the nucleus to create a neutron and an electron neutrino. Two-neutrino double electron capture occurs when two electrons are captured at once and is a much rarer process.

Acoustic tracking shows thresher sharks are early birds

25 Apr 2019
Pelagic thresher shark, Alopias pelagicus, at Monad Shoal near Malupascua island in the Philippines. The sharks visit this seamount where bluestreak cleaner wrasse, Labroides dimidiatus, remove parasites from their skin, gills and cloacal region. (Image courtesy: Louise Murray)

Pelagic thresher sharks visit the Monad Shoal seamount in the Philippines so that cleaner wrasse eat the parasites that infest their skin and gills. In turn, the sharks attract scuba divers from around the world. The local economy near Malupascua Island receives 80% of its income from dive tourism and local people have taken measures to protect the sharks – the Bantay Dagat community–based organisation guards the area against illegal fishing day and night.

 

 Simon Oliver, diving on a rebreather, watches as a freediver tags a thresher shark with an acoustic tag behind the dorsal fin. Neither a freediver or a scuba rebreather emits bubbles, allowing a closer approach to the shark for tagging. (Courtesy: Thresher Shark Research Project)

 

 

 

 

 

When they venture further afield, these sharks, which are found in the Indian and Pacific Oceans, are at risk from fishing lines set for smaller fish, and from capture for their meat, fins, skin, and liver oil. Combined with the animals’ slow reproduction, these pressures mean that numbers of pelagic thresher sharks are declining. The species is listed as vulnerable by the International Union for the Conservation of Nature.

Until recently, however, scientists had little idea how far individuals that visit the seamount roam. With that in mind, Simon Oliver of the University of Chester, UK, and his colleagues tagged pelagic thresher sharks and tracked their whereabouts acoustically.

“We decided that we needed to understand how these animals use this part of the Indo-Pacific Ocean in order to better protect them,” said Oliver, who has studied threshers for 15 years and was the first to explain why these sharks frequent the seamount.

Huge Chinese cosmic-ray observatory begins operation

26 Apr 2019 Michael Banks

 

Eye on the sky: the Large High Altitude Air Shower Observatory in Sichuan Province in southwest China will attempt to understand the origins of high-energy cosmic rays. (Courtesy: IHEP/LHAASO Collaboration)
 

 

One of the world’s largest and most sensitive cosmic-ray facilities has begun operation with its first set of detectors. Located about 4410 m above sea level in the Haizi Mountain in Sichuan Province in southwest China, the 1.2 billion yuan ($180m) Large High Altitude Air Shower Observatory (LHAASO) will attempt to understand the origins of high-energy cosmic rays.

Cosmic rays are particles that originate in outer space and are accelerated to energies higher than those that can be achieved in even the largest man-made particle accelerators.

Did the Romans build seismic invisibility cloaks?

23 Apr 2019 Ancient metamaterials: the Colosseum in Rome could be protected from earthquake damage by a seismic invisibility cloak. (Courtesy: Bengt Nyman/CC BY 2.0)

Ancient Romans may have built structures that acted like invisibility cloaks long before physicists had any idea about metamaterials or transformation optics. That is the surprising claim from researchers in France, who found that the pattern of foundations in some Roman theatres and amphitheatres very closely resembles the features of electromagnetic cloaking devices. They say that these “archaeological metamaterials” could have indirectly provided protection against earthquakes, by bending seismic waves around the arenas.

Supersolid behaviour spotted in dipolar quantum gases

20 Apr 2019

 

 

 Super state: three independent groups have caught sight of supersolidity. (Courtesy: iStock/3quarks)

 

 

Atomic systems that behave very much like supersolids have been created independently by teams of physicists in Italy, Germany have Austria. The teams have shown that dipolar quantum gases trapped by magnetic fields can spontaneously separate into arrays of coherent droplets, providing a system closer to the original conception of a supersolid.

The supersolid phase is a counterintuitive quantum state of matter that has both crystalline order and frictionless flow at very low temperatures. The phenomenon is related to superfluidity and was predicted 50 years ago by Soviet physicists Alexander Andreev and Ilya Lifschitz. However, supersolidity has proved frustratingly difficult to observe.

Negative order appears in liquid crystals

18 Apr 2019 Belle Dumé

The image sequence shows the reversible shape transformation of an LCE sphere; where the folded shape similar to spherical pancakes at 20°C turns into a smooth sphere at 60°C and vice versa. The characteristic colours on the sphere resemble the anti-ordered microscale arrangement of molecules. Credit: University of Luxembourg

Researchers have observed spontaneous negative orientational order in a liquid crystal material for the first time. The result, obtained quite by chance, could help in the development of applications such as artificial muscles for soft robotics.

Liquid crystals are non-solid materials in which molecules arrange themselves in an ordered way. “This order, which is described by a scalar parameter is a very central concept in liquid crystal physics, but the negative range is frequently forgotten,” explains research team leader Jan Lagerwall of the University of Luxembourg. “Although the equation describing the parameter ranges from -1/2 to +1, it is often said that it goes from 0 for fully disordered to 1 for fully ordered.

Light can behave like a magnet

01 Apr 2019 Belle Dumé

A simple sketch of the theoretical simulator. Courtesy: R Rota, EPFL

Photons can behave like magnetic dipoles at absolute zero temperatures. This is the new result from a quantum simulator put forward by physicists at the EPFL in Switzerland and Paris Diderot University in France. The theoretical study proves that simple photonics devices can be used to mimic the behaviour of complex materials under extreme conditions – experiments that are difficult to actually do in the laboratory.

Condensed matter systems, such as magnetic materials, containing many interacting particles show complex behaviour that is challenging to model even using the most sophisticated computer programmes.

As real as it gets

16 Apr 2019

Taken from the April 2019 issue of Physics World. Members of the Institute of Physics can enjoy the full issue via the Physics World app.

Philip Ball reviews Einstein’s Unfinished Revolution: the Search for What Lies Beyond the Quantum by Lee Smolin

Crazy but true? US theorist Lee Smolin presents his own “realist” formulation of quantum mechanics. (Courtesy: Nicolle Rager Fuller, National Science Foundation/Science Photo Library)

Theoretical physicist and author Lee Smolinonce presented an early form of his theory on quantum mechanics to Richard Feynman. While the famous physicist listened to him respectfully, Feynman ultimately told Smolin that his theory was unlikely to work out because it wasn’t crazy enough. Smolin interpreted that as an indication that his ideas didn’t go deep enough, but he seems at any rate to have taken the advice to heart, as his latest book Einstein’s Unfinished Revolution: the Search for What Lies Beyond the Quantum attests.

Smolin, 63, has gained something of a reputation for coming up with ideas that some find stimulating and provocative, while others would happily call them crazy. It’s a tradition particularly apparent in quantum mechanics, which has more than its share of mavericks: David Bohm, Hugh Everett, John Wheeler and Roger Penrose spring to mind. That’s how it should be though – quantum physics can look crazy, and it positively needs bold and even outrageous ideas, if only to shock us out of complacent acceptance of the innocent-looking mathematical formalism. So the flood of current books about quantum theory (and there are more are on the way) should not stop you finding room for this one.

Physicists spot the signatures of nuclear fusion in a table-top device

16 Apr 2019

Image by kai kalhh from Pixabay

Neutrons characteristic of nuclear fusion have been produced sustainably inside a device that is small enough to fit on a tabletop. Yue Zhang at the University of Washington and colleagues observed the neutrons following efforts to stabilize the accelerated plasma contained within a Z-pinch, a device that for decades has been used by astronomers to recreate the hot plasmas typical of a stellar interior. The new work offers a potential route towards compact fusion-energy generators, as an alternative to large-scale, tokamak-based devices.

A Z-pinch device works by running a strong current along a tube of accelerated plasma, inducing a Lorentz force that generates a strong magnetic field within the plasma. This field “pinches” the plasma by bringing particles closer together – increasing its pressure, and therefore, its temperature.

Seven rules for nanotech innovation

12 Apr 2019

This article first appeared in the 2019 Physics World Focus on Nanotechnology & Nanomaterials

Serial entrepreneur Tim Harper shares lessons from 20 years of good, bad and (occasionally) ugly experiences of starting and running nanotech businessesCarbon dreams: “Space elevators” were an early proposed application of carbon nanotubes. (Courtesy: Shutterstock/Tschub)

Back in 2000, the field of nanotechnology was just starting to shift from something that involved tiny robots and molecular gearwheels to real, tangible science with potential applications. In October that year, I organized the first Trends in Nanotechnology (TNT) conference in Toledo, Spain, and as with all conferences, the real work happened in the hotel bar.

The atmosphere inside the Hotel Maria Cristina was febrile. The US National Science Foundation was predicting a trillion-dollar nanotechnology market by 2015. Huge national and European nanotechnology projects were taking shape, and there we were, the cream of the nanoscience community, poised and ready to change the world. New sensors, new ways of delivering drugs, molecular memories – even carbon nanotube-based space elevators to the stars – all seemed within reach. Surely, within a decade, we’d have changed all manufacturing from “top down” to “bottom up”, solving the interlinked problems of clean energy, climate change and human happiness at a stroke.

The Big Bang Theory

   



The Big Bang Theory



12/4/2019

Ionic scissors cut out phosphorene nanoribbons

11 Apr 2019 Belle Dumé

High-speed atomic force microscopy topography of phosphorene nanoribbons with varying heights from one (left) to five layer (right) thicknesses. Credit: Oliver Payton

Researchers have succeeded in making the first nanoribbons from phosphorene – graphene’s 2D phosphorus cousin. The materials, which can be just one atom thick and under a 100 atoms wide, and made from pure crystalline phosphorus, are theoretically predicted to have a wide range of technologically useful and even exotic properties. The high-quality ribbons produced means that these properties can now be measured and the materials tested in various real-world applications.

Phosphorene, which is also known as few-layer black phosphorus, can be obtained by mechanically cleaving black phosphorus crystals (in the same way that graphene layers are mechanically exfoliated from bulk graphite). Although bulk black phosphorus has been known about for over a century, it is only in the last decade that researchers have tried to isolate single layers of the material.

Missing methane magnifies Mars mystery

11 Apr 2019

An artist’s depiction of the ExoMars Trace Gas Orbiter over the red planet. (Courtesy: ESA/D Ducros)

A mysterious mechanism acting on, or near, the surface of Mars is removing methane from the planet’s atmosphere, according to new results from the ExoMars Trace Gas Orbiter (TGO). The joint European–Russian mission has released interim results covering the period of April to August 2018, revealing that it did not detect methane in the red planet’s atmosphere during that time.

This seems surprising, since NASA’s Curiosity rover, situated in Gale Crater, has detected a constant average background level of 0.4 ppbv (parts per billion by volume) of methane in the atmosphere for the last three Martian years, punctuated by occasional spikes in intensity of up to 7 ppbv.

First images of a black hole unveiled by astronomers in landmark discovery

10 Apr 2019 Michael Banks

Main event: the image of the black hole at the centre of the Messier 87 galaxy shows the effect of the accretion disc as well as the black hole's "shadow" in the centre. (Courtesy: Akiyama et al and ApJL)

The first direct visual evidence of a black hole and its “shadow” has been revealed today by astronomers working on the Event Horizon Telescope (EHT). The image is of the supermassive black hole that lies at the centre of the huge Messier 87 galaxy, in the Virgo galaxy cluster. Located 55 million light-years from Earth, the black hole has been determined to have a mass 6.5-billion times that of the Sun, with an uncertainty of 0.7 billion solar masses. Although black holes are inherently invisible because of their extreme density and gravitational field, the researchers have managed to obtain images near the point where matter and energy can no longer escape – the so-called event horizon.

“We are giving humanity its first view of a black hole — a one-way door out of our universe,” says Sheperd Doeleman of the Haystack Observatory at the Massachusetts Institute of Technology (MIT) who is the EHT’s lead astronomer.

Ep.1 Candida auris: A Resistant Fungal Infection | Medscape TV

             





Ep.1 Candida auris: A Resistant Fungal Infection | Medscape TV



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Brian Greene on the first-ever image of a black hole from the Event Hori...

             



Brian Greene on the first-ever image of a black hole from the Event Hori...



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Candida auris | What You Need to Know About Candida Auris | News

           

Candida auris | What You Need to Know About Candida Auris | News



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Candidal Infections - causes, symptoms, diagnosis, treatment, pathology

           



Candidal Infections - causes, symptoms, diagnosis, treatment, pathology



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Candida Auris: The Drug Resistant Fungus & What We Need To Know

                 



Candida Auris: The Drug Resistant Fungus & What We Need To Know





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In Depth: The Deadly Fungus - Candida Auris

               



In Depth: The Deadly Fungus - Candida Auris



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Shear forces help make stretchable hydrogel

08 Apr 2019 Belle Dumé

Left: The gelation mechanism through metal coordination to the pseudopolyrotaxanes; the metal ions are shown as yellow spheres. In the lower panel, which represents the hydrogel, the pseudorotaxanes are shown as blue lines. Right: Stimuli-responsive properties of the Cu(II)-based hydrogel, showing that the gel reverts to a sol overnight, and can be converted into a gel again under shear force. Courtesy: W Jiang, Southern University of Science and Technology in China

Shear forces can convert a sol into a gel. This surprising new behaviour, observed in an aqueous solution of a pseudopolyrotaxane with copper ions added to it, is similar to that in dissipative, far-from-equilibrium, biological systems capable of self-healing.

“Usually supramolecular hydrogels, like the ones we studied in this work, are destroyed by shear forces and convert into a sol,” says Wei Jiang of the Southern University of Science and Technology in China, who led this research effort. “This makes our result surprising and exciting.”