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Home » Page 1068

Biocompatible piezoelectric generator is made from fish scales

 

Fish scales extracted from food waste have been used to build tiny generators that can convert mechanical energy, such as a touch or sound vibrations, to electrical energy. The work was done by physicists in India, who say that the piezoelectric device could be used to develop environmentally friendly, self-powered electronics with a wide-range of applications.

Piezoelectric materials respond to mechanical stress by separating positive and negative electrical charge, and therefore can be used to convert the mechanical energy of vibrations into electrical energy. Piezoelectric generators that harvest energy from vibrations in the living environment would allow the development of fully independent, battery-free devices. These could be particularly useful for medical devices, such as pacemakers and insulin pumps, and targeted drug-delivery systems that consume little power, but need it continuously.

But, to realize the full potential of such devices, researchers need to develop new environmentally friendly piezoelectric materials. Dipankar Mandal, a physicist at Jadavpur University in Koltata, India, says this is “simply because most of the traditional piezoelectric materials contain toxic elements, such as lead and bismuth”. As well as being useful for biomedical applications, Mandal adds that non-toxic and environmentally friendly piezoelectric materials would also reduce electronic waste and society’s dependence on traditional energy sources, like batteries, which often contain toxic elements.

Tipping the scales

Fish is a popular food in India and one possible source of non-toxic piezoelectric materials in that country is the large quantity of fish scales that are disposed of as waste. The scales are composed of collagen nano-fibrils, which are known to have piezoelectric properties, and this inspired Mandal and colleague Sujoy Ghosh to see if they could use waste scales to produce a cost-effective, piezoelectric nano-generator.

Collagen consists of three polypeptide chains that twist together to form a triple-helical structure. Hydrogen bonds between the polypeptide chains all orientate in the same direction and act as molecular dipoles, resulting in spontaneous electrical polarization and piezoelectric properties.

Within fish scales, collagen nano-fibrils self-assemble and align. “We wanted to explore what happens to the piezoelectric yield when a bunch of collagen nanofibrils are hierarchically well aligned and self-assembled in the fish scales,” Mandal explains. To build their piezoelectric device, the researchers washed and then treated fish scales – collected from a local fish market – with an acidic demineralizing solution to make them transparent and flexible. They then attached gold electrodes to these flexible, transparent scales and laminated them with a polypropylene film to create a robust “bio-piezoelectric nano-generator”.

Tests showed that the device had an intrinsic piezoelectric response of around 5 pC/N. And it was able to harvest energy from various ambient motions, including body movements, machine and sound vibrations, and wind flow.

Green power source

When subjected to a repeated compressive stress of 0.17 MPa the nano-generator produced an output of 4 V with a current of 1.5 μA – or 6 μW of power. The researchers also linked four of the devices together and were able to produce a voltage of 14 V. By gently slapping this device with their hands, they were able to switch on more than 50 LEDs. According to the researchers, this demonstrates that it is “a sustainable green power source”.

Mandal told physicsworld.com: “The piezoelectric output is really promising, particularly if we look at the instantaneous piezoelectric energy-conversion efficiency and similar-sized available biocompatible piezoelectric materials.” He adds that the research could have enormous potential for “tiny electronic gadgets, health-care monitoring, self-powered implantable bio-medical devices, targeted drug delivery, national security and defence applications”.

The researchers now plan to scale up the nano-generator and “test it in different bio-medical and self-powered devices”.

The device is described in Applied Physics Letters.

Conference thoughts

Maitn Durrani speaking at the 50th anniversary meeting of the Brazil Physics Society on 6 September 2016
All-male line-up: Matin Durrani speaking at a round-table on the future of physics at the 50th-anniversary meeting of the Brazil Physics Society.

By Matin Durrani in Natal, Brazil

I rounded off my final full day at the 50th-anniversary meeting of the Brazil Physics Society (SBF) by taking part in a round-table on the development of physics over the next two decades organized by former SBF president Ricardo Galvão,

Alongside me (right to left in the photo above) were Christophe Rossel from IBM’s Zurich lab, who’s current president of the European Physical Society, Roger Falcone from the University of California, Berkeley who’s vice-president of the American Physical Society and will take over as head honcho in 2018, as well as Carlos Pinto de Melo from the Universidade Federal de Pernambuco, who was SBF president from 2009 to 2011. A late entry to the panel was Valentin Areviev from the Joint Institute for Nuclear Research in Dubna, Russia.

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Flash Physics: Imaging single ions, UK’s merging ‘supercouncil’, OMEGA laser sets fusion record

Crisply imaging a single ion

A novel imaging technique that can capture a single atomic ion and its motion with unprecedented nanoscale sensitivity has been unveiled by researchers at the Joint Quantum Institute in the US. This adaptive-optics method uses a combination of high-performance lenses and computer processing to get rid of aberrations and distortions that lead to image inaccuracies. The team says that its imaging system was able to detect ion movements on the scale of a few nanometres and could be used to measure quantum superpositions of two different motional states of a single ion. It may also have applications in other fields that include point-like sources, such as biology and astronomy. The work is published in Nature Photonics.

Coherently coupling spins to a nitrogen vacancy

Researchers have coherently coupled three spins to a nitrogen vacancy and the system could have applications in building quantum sensors and simulations. Normally, physicists try to avoid coupling diamond nitrogen vacancies (NVs) to nearby electron spins because this causes decoherence and makes the NVs unsuitable for storing quantum information. But now, Helena Knowles, Dhiren Kara, and Mete Atatüre of the University of Cambridge have stored and read out quantum information using an NV that is coherently coupled to three nearby spins. Possible applications of the system include measuring extremely small magnetic fields in living organisms and building quantum simulators on a chip. The work is described in Physical Review Letters.

Large Hadron Collider hits luminosity target

Last week, the Large Hadron Collider at the CERN particle-physics lab in Geneva hit a new milestone as the integrated luminosity delivered to its ATLAS and CMS detectors reached 25 fb–1 – the lab’s target for the whole of 2016. LHC researchers have been hard at work all year round to develop new ways to boost the device’s performance and thanks to the improvements, the LHC was routinely operated with peak luminosities 10%–15% above the design value of 1034 cm–2 s–1 in July and August. This success was achieved despite an unexpected animal incident involving a small beech martin in May and a control fault in the cryogenics plant in August that meant that the ATLAS experiment had to ramp down its magnets, requiring five days to get back to normal conditions. The accelerator team is now preparing for the “season finale”, where forward proton–proton physics and proton–lead physics will replace the familiar proton–proton physics.

The OMEGA laser's 20 cm disc amplifiers
Burning bright: the OMEGA laser’s 20 cm disc amplifiers at the University of Rochester’s Laboratory for Laser Energetics. (Photo by Adam Fenster/University of Rochester)

OMEGA laser sets new fusion-yield record

Scientists working on the OMEGA laser at the University of Rochester have created the conditions capable of producing a fusion yield that’s five times higher than the current record – as long as their results can be scaled up to work at the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in California. The OMEGA laser was used to fire 60 laser beams directly at a millimetre-sized fuel pellet. Their results show that if their “direct-drive” method of fusion can be replicated at NIF – which instead uses “indirect-drive”, where the light from 192 laser beams is first converted into X-rays before hitting the fuel capsule – then it would be possible to produce more than 100 kJ of fusion energy, bringing the facility nearer to its “ignition” target.

UK “supercouncil” will boost research and industry collaboration, says science minister

Plans to merge Innovate UK with the UK’s research councils (RCUK) to create a “supercouncil” of UK research and innovation will allow the UK to “exploit the knowledge and expertise we have for the benefit of the whole country”, according to a letter written by science minister Jo Johnson and presented to the House of Lords Science and Technology Committee. According to Johnson, such a merger will remove the barriers between research and businesses. Johnson’s letter was in response to one of his peers on the committee, who had earlier expressed “serious concerns” about the merger plans, which are a part of the higher-education and research bill that is currently passing through the Commons.

 

  • You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics. Tune in to physicsworld.com later today to read today’s extensive news story on creating a piezoelectric generator from fish scales.

First stars and galaxies are not as old as we thought, say Planck astronomers

 

The dark ages of the universe were nearing their end 700 million years after the Big Bang, which is 150 million years later than previous measurements indicated. That is the conclusion according to astronomers who have analysed data from the European Space Agency’s Planck spacecraft. The research provides important information about when the first stars and galaxies formed in the early universe.

The first billion years of cosmic history are shrouded in mystery. This shroud began to lift when ultraviolet light from the first stars and galaxies ionized the fog of neutral hydrogen gas that filled the universe. This time period is known as the epoch of reionization and was more or less complete about 12.9 billion years ago, or about 900 million years after the Big Bang. However, exactly when reionization began has long been a source of debate amongst astronomers.

Polarizing effect

The answer lies in how photons in the cosmic microwave background (CMB) radiation are scattered by the electrons liberated from ionized hydrogen atoms. Electrons scatter the photons in preferential directions, causing the CMB to become polarized. Finding out when this polarization took place provides the answer to when the first stars and galaxies began ionizing the hydrogen in the universe.

“The polarization of the CMB is the best way to constrain reionization almost independently of other cosmological parameters,” explains Jean-Loup Puget of the Institut d’Astrophysique Spatiale in France, who is lead scientist of the High Frequency Instrument (HFI) on board Planck.

With that in mind, a team led by Matthieu Tristram of the Laboratoire de I’Accélérateur Linéaire, also in France, used the HFI to measure the point at which the reionization was half complete. To do this they used polarization data to determine the “Thomson optical depth”, which is a measure of how much scattering occurred at a given redshift (age of the universe). They found that the greatest amount of electron scatterings occurred about 700 million years after the Big Bang (13.1 billion years ago), which suggests that this was the time when reionization began in earnest.

Painstaking analysis

The data from HFI took several years because of the delicate nature of the instrument. HFI’s 52 bolometers measure infrared and millimetre-wave radiation by capturing heat and must be cooled to just 0.1 K to detect the faint CMB. “The result came after several years of painstaking data analysis, since it is very difficult to control spurious instrumental effects at such low brightness,” says Puget.

Earlier attempts to measure the epoch of reionization had given different results. NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) had previously indicated that the reionization process was active just 450 million years after the Big Bang. Last year, Planck’s Low Frequency Instrument, operating at longer wavelengths than HFI, concluded that the reionization process began 550 million years after the Big Bang. Now, HFI has pushed the date even further forward.

The recent findings suggest that the first stars and galaxies received no help in their reionization efforts from quasars, which are active supermassive black holes. Surveys indicate that quasars were relatively few in number 700 million years after the Big Bang, whereas stars and galaxies were more plentiful.

The most distant galaxy ever seen is called GN-z11 and was identified by Hubble earlier this year. It existed 13.4 billion years ago, when the universe was just 400 million years old. Planck’s observations show that the universe was less than 10% ionized at this time, meaning that although stars and galaxies were forming it would take another 300 million years for them to be plentiful enough for reionization to be well underway. NASA’s upcoming James Webb Space Telescope, set to launch in 2018, will be capable of observing this time period as well as going even further back in time to chart the epoch of reionization in full.

The findings are described in Astronomy and Astrophysics.

A paradise for physics in Brazil

Photo of Alvaro Ferraz, director of the International Institute of Physics in Natal on 5 September 2016
Leading light: Alvaro Ferraz, director of the International Institute of Physics in Natal.

By Matin Durrani in Natal, Brazil

I took a break yesterday afternoon from the 50th anniversary meeting of the Brazil Physics Society here in Natal in the north-east of the country to visit the International Institute of Physics (IIP). Located on the campus of the Universidad Federal do Rio Grande do Norte, the IIP was founded in 2010 to carry out cutting-edge research in theoretical physics and help push forward Brazilian science on the international stage. If you’re a theorist, it’s hard to imagine a more pleasant environment for doing physics.

Previously housed in a small, cramped building (albeit with a swimming pool), the IIP moved into a shiny, new three-storey building in March this year. One striking architectural feature is the institute’s central atrium, which is fully open to the outside world. Natal has such a great climate – it’s 25–30 °C all year round and almost always sunny – that there’s no need for stuffy walls and doors. The design also lets the regular, strong breezes that blow into Natal from the Atlantic to add a delightful, cooling touch.

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Flash Physics: Philae lander spotted, Diamond Light Source launches electron-microscopy lab, prizes for cosmology and fusion research

 

Philae lander spotted on comet 67P at long last

Nearly two years after it bounced onto the alien surface of comet 67P/Churyumov–Gerasimenko, Rosetta scientists have managed to locate the “final resting place” of their Philae lander, in images taken by Rosetta’s high-resolution camera. This news could not have come at a better time for the European Space Agency team as the mission is less than a month away from its end. As the picture above shows, Philae is wedged into a dark crack on the comet and the instrument’s orientation clearly reveals why establishing communications was so difficult, following its landing on 12 November 2014. The images were taken on 2 September by the OSIRIS narrow-angle camera, as Rosetta came within 2.7 km of the surface. You can read more about Philae’s tense and exciting first few days on 67P in our previous news stories and blogs.

Scientific, state and film royalty mingle at Kavli Prize ceremony

Winners of the 2016 Kavli Prize in Astrophysics will receive their awards today from Norway’s Crown Prince Haakon in a ceremony in Oslo, Norway. The physics prize was awarded to Ronald Drever, Kip Thorne and Rainer Weiss for the direct detection of gravitational waves. In February, scientists working at the US LIGO detectors in Washington and Louisiana announced they had directly measured gravitational waves for the first time. The US actor Alan Alda and the Norwegian actress Lena Kristin Ellingsen will host the ceremony. The Kavli Prize consists of a $1m prize with the laureates also receiving a gold medal and a scroll.

Diamond Light Source unveils new electron-microscopy facility

A new electron Physical Sciences Imaging Centre (ePSIC) was opened yesterday by the Diamond Light Source in the UK, together with the University of Oxford and the chemicals company Johnson Matthey. Located on the Harwell campus in Oxfordshire, the facility will contain two state-of-the-art electron microscopes that can record information at a rate of up to 200 frames per second, and will allow scientists to actually “see” and analyse individual atoms, within materials, in real time. Andrew Harrison, CEO of the national synchrotron science facility, called this “the most significant day” for Diamond in 10 years, in terms of launching new facilities. Each room in the new facility is carefully isolated from vibrations, is soundproof and has anti-echo walls, and is temperature-controlled to within 0.1 °C, reports Physics World‘s Margaret Harris, who attended the launch. Also of note is that each electron microscope has its own miniature electron accelerator – capable of generating the 100 keV electrons used for imaging – rather than using electrons from the Diamond beamline.

Novel superconductor wins EU SOFT Innovation Prize

The €50,000 EU SOFT Innovation Prize for fusion research has been awarded to researchers at the Karlsruhe Institute of Technology (KIT) and the Swiss Plasma Center (SPC). The prize was awarded yesterday at the 2016 Symposium on Fusion Technology (SOFT) in Prague. KIT researchers designed a new superconducting concept that might be used as a basic element in future high-current cables of fusion power plants, industrial facilities or DC power grids. Sustainable-energy sources and, above all, the reliable distribution of energy are major elements of [Germany’s Energy Transition],” says Holger Hanselka, president of KIT. “The prize reflects KIT’s essential contribution to research, to the transformation of the energy system, and to the viability of our society.”

 

  • You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics. Tune in to physicsworld.com later today to read today’s extensive news story on when the first stars formed in the universe.

Why do physicists want to redefine basic units as fundamental constants?

In 2018 the International System of Units will be redefined in terms of fundamental constants. Why this change is taking place is explained in this short film presented by Stephan Schlamminger of the National Institute of Standards and Technology (NIST).

This means that base units such as the metre, the second and the kilogram will be redefined in terms of fundamental quantities such as the speed of light (c), the Planck constant (h) and the charge of the electron (e). Doing so will bring together two of the grand theories of modern physics: quantum physics and Einstein’s general theory of relativity.

This video is part of our 100 Second Science series, in which researchers give concise presentations covering the spectrum of physics.

Large-scale metamaterials could combat earthquake shocks

 

Future cities could be protected from destructive earthquakes using large-scale metamaterial shields to dampen seismic waves, according to new work done by researchers in Europe. The team used 3D modelling to demonstrate the potential of the shields, which are made of arrays of cavities dug into the ground.

Of all natural hazards, earthquakes are perhaps the most catastrophic – they account for more than half of all disaster-related mortalities and have the potential to cause billions of pounds worth of property damage if they strike major population centres. While buildings and other infrastructure can be individually engineered for earthquake resistance, such measures tend to be less effective against large quakes and difficult to implement post-construction, especially within historic buildings.

Inhibited waves

An alternative approach, however, lies in attenuating seismic waves before they can reach high-risk, built-up areas. The advantage of such an approach lies in how it could potentially be used to protect multiple existing structures, without the need for seismic retrofitting. This might be achieved using metamaterials, which allow waves to be manipulated in a variety of unconventional ways.

One previous study, for example, explored the potential of a metamaterial cloak that could be used to divert seismic energy around a structure.

In the new study, however, paper-author Marco Miniaci of the University of Le Havre, France, and colleagues explored the potential of creating band gaps – which inhibit the propagation of seismic waves within a certain frequency range – using locally resonant metamaterials and phononic crystals. Unlike previous studies exploring this approach, their work used 3D models capable of accounting for both body and surface seismic waves, as well as dissipation effects in layered soils.

Different shapes

The metamaterial configurations in their work were composed of two to three rows of cavities, or boreholes – in different shapes and with different fillings – positioned in a square array around the structure to be shielded. The team tested the effectiveness of three different cavity types: a cross-shaped cavity, a hollow steel- or concrete-lined cylinder, and a rubber-coated steel cylinder.

“The exact dimensions will depend on the soil type and the frequency range of the shield,” explains Miniaci, adding that “for sandy conditions and low-frequency seismic excitations, the width, spacing and depth of the cavities – which should be lined with concrete to prevent the surrounding soil from collapsing – could reach 10 m.”

Shields made of all three cavity types were found to be significantly effective in attenuating both bulk and surface waves – with the cross-shaped cavities most effective at attenuating the destructive surface waves. Alongside earthquake engineering, the researchers also propose that scaled-down versions of their arrays might be used to shield against other forms of vibration at higher frequencies. One such application would be in vibration damping around high-speed railway lines; another in creating improved blast protection.

Strong interplay

Bariş Baykant Alagöz, a physicist at the İnönü University, Turkey, who was not involved in this study, says that “the results look promising for the development of passive seismic shield technologies.” Francisco Meseguer – a physicist at the Universidad Politécnica de Valencia in Spain, who was also not a part of the team – agrees. But he also cautions against the assumption that attenuation strategies should focus on surface waves, however, noting that “there is also a strong interplay between bulk and surface waves when they propagate and also scatter in non-uniform soils composed of materials with different mechanical properties, like density and bulk constants.” Meseguer also comments that, while the shield could indeed be useful for protecting single buildings with a specific resonance response, the wavelength range of seismic movements is much larger than the phononic band gap studied.

With their initial study complete, the next steps towards developing their seismic-shield concept should involve experimental tests using scaled models in seismic and vibration labs, says Miniaci.

The research is described in the open-access New Journal of Physics.

Antimatter comes to Brazil

Photo of some of the delegates at the 50th anniversary meeting of the Brazil Physics Society in Natal, Brazil, 5 September 2016
Great minds – some of the delegates at the 50th anniversary meeting of the Brazil Physics Society.

By Matin Durrani in Natal, Brazil

There can’t be many physics experiments to have been visited by members of not one, but two different rock bands. But then there’s something fundamentally captivating about the work of the ALPHA collaboration at the CERN particle-physics lab near Geneva, which is studying the properties of antimatter.

As Jeffrey Hangst from Aarhus University in Denmark revealed in his plenary talk at the 50th anniversary meeting of the Brazilian Physics Society (SBF) yesterday, the ALPHA collaboration has not only played host to a visit from legendary 1970s rockers David Crosby and Graham Nash, but in July also welcomed members of British alternative “space rock” outfit Muse while they were on a visit to CERN.

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Flash Physics: Producing pristine graphene, SpaceX moves sites, UK’s dark skies, mysterious microcrystals

Producing pristine graphene cheaply

The “wonder material” graphene has held much promise since it was first discovered in 2004. Indeed, the one-atom-thick honeycomb lattice of carbon atoms boasts a number of unique physical, electronic and optical properties – including its strength and electrical conductivity – that lends the material to a host of pioneering applications. But a persistent problem with truly rolling out devices using the 2D material is that of producing low-cost graphene that is, most importantly, defect free, on a large scale. Now, researchers at Friedrich-Alexander-Universiät Erlangen-Nürnberg in Germany say they have successfully synthesized defect-free graphene directly from graphite, for the first time . The graphene – which the team says is of a higher quality than has ever been achieved before – is produced directly from a solution, allowing it to be cut without causing defects. The new method, which is published in the journal Nature Communications, is also low cost and efficient.

SpaceX jumps ship to a new launch site

Following the explosion of a SpaceX rocket on 1 September, the firm says it will shift its flights to a nearly completed second site after damage to its Launch Complex 40 at Cape Canaveral Air Force Station. The private company SpaceX faced a major setback last week when its Falcon 9 rocket exploded ahead of a mission, during a pre-launch “static fire test”. SpaceX will now use launch pad “39A”, which is located a few miles north at NASA’s Kennedy Space Center. Meanwhile, the Federal Aviation Administration is investigating the disaster, which requires the suspension of SpaceX flights pending the results of the probe. Read more about SpaceX’s pioneering founder Elon Musk in our “Once a Physicist” column.

Mysterious microcrystals pave the way to cheaper lasers

Stacks of small, rod-shaped microcrystals, which are easy and cheap to grow, could be used in lasers, thanks to the latest work done by researchers at the National Institute of Standards and Technology in the US and Shandong University in China, which is published in the journal Science Advances. The researchers have discovered a potential way to sidestep longstanding difficulties with making such crystals, which are used to determine a laser’s colour as well as the light’s polarization. While the team says that its microcrystals outperform conventional crystals in some ways, they also challenge conventional scientific theory as to why they perform as they do. “We’ve spoken to a number of experts in different fields worldwide, and none of them can explain it,” says physicist Lu Deng. “Currently, no theory can explain the initial growth mechanism of this exotic crystal. It’s challenging our current understanding in fields from crystallography to condensed-matter physics.”

NASA to gain new InSight in Mars come 2018

NASA has announced that its Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission to Mars will now launch in May 2018, following final approval by the agency’s science-mission directorate. InSight aims to study the deep interior of Mars and was originally scheduled to launch in March, but NASA suspended launch preparations in December 2015 due to a vacuum leak in its main science instrument – the Seismic Experiment for Interior Structure. If the craft successfully launches in May 2018, it is expected to land on Mars by the end of that year.

Dark-sky sites revealed across the UK

Today, the Science and Technologies Facilities Council (STFC) in the UK announced that a host of new stargazing sites perfect for astronomy and free from the dimming effects of urban light pollution have been identified across the country, bringing the total number of Dark Sky Discovery Sites to more than 150. “During the extra hours of darkness this autumn, thousands of people in the UK will be able to experience skies ideal for astronomy, thanks to 17 new Dark Sky Discovery sites” according to the STFC. The Dark Sky Discovery map highlights Dark Sky Discovery Sites and other venues that will be running events through the winter. These locations have been hand-picked to observe the sky on a clear night, offering good public access and great sightlines in all directions.

 

  • You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics. Tune in to physicsworld.com later today to read today’s extensive news story on using large-scale metamaterials as seismic shields.
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