A video camera that powers itself

A video camera based on a self-powered image sensor can run indefinitely without an external power supply.

A research team led by Shree K. Nayar, T.C. Chang Professor of Computer Science at Columbia Engineering, has invented a prototype video camera that is the first to be fully self-powered -- it can produce an image each second, indefinitely, of a well-lit indoor scene. They designed a pixel that can not only measure incident light but also convert the incident light into electric power. The team is presenting its work at the International Conference on Computational Photography at Rice University in Houston, April 24 to 26.

"We are in the middle of a digital imaging revolution," says Nayar, who directs the Computer Vision Laboratory at Columbia Engineering. He notes that in the last year alone, approximately two billion cameras of various types were sold worldwide. "I think we have just seen the tip of the iceberg. Digital imaging is expected to enable many emerging fields including wearable devices, sensor networks, smart environments, personalized medicine, and the Internet of Things. A camera that can function as an untethered device forever -- without any external power supply -- would be incredibly useful."

A leading researcher in computational imaging, Nayar realized that although digital cameras and solar panels have different purposes -- one measures light while the other converts light to power -- both are constructed from essentially the same components. At the heart of any digital camera is an image sensor, a chip with millions of pixels. The key enabling device in a pixel is the photodiode, which produces an electric current when exposed to light. This mechanism enables each pixel to measure the intensity of light falling on it. The same photodiode is also used in solar panels to convert incident light to electric power. The photodiode in a camera pixel is used in the photoconductive mode, while in a solar cell it is used in the photovoltaic model.

Nayar, working with research engineer Daniel Sims BS'14 and consultant Mikhail Fridberg of ADSP Consulting, used off-the-shelf components to fabricate an image sensor with 30x40 pixels. In his prototype camera, which is housed in a 3D printed body, each pixel's photodiode is always operated in the photovoltaic mode.

The pixel design is very simple, and uses just two transistors. During each image capture cycle, the pixels are used first to record and read out the image and then to harvest energy and charge the sensor's power supply -- the image sensor continuously toggles between image capture and power harvesting modes. When the camera is not used to capture images, it can be used to generate power for other devices, such as a phone or a watch.

Nayar notes that the image sensor could use a rechargeable battery and charge it via its harvesting capability: "But we took an extreme approach to demonstrate that the sensor is indeed truly self-powered and used just a capacitor to store the harvested energy."

"A few different designs for image sensors that can harvest energy have been proposed in the past. However, our prototype is the first demonstration of a fully self-powered video camera," he continues. "And, even though we've used off-the-shelf components to demonstrate our design, our sensor architecture easily lends itself to a compact solid-state imaging chip. We believe our results are a significant step forward in developing an entirely new generation of cameras that can function for a very long duration -- ideally, forever -- without being externally powered."

First Paperless Public Library of World BiblioTech opened in USA

First Paperless public Library of the World BiblioTech was opened in the USA State of Texas on 4 February 2014. The traditional libraries have been replaced with high-tech gadgets that cater to both adults and children.

Registered residents of the Texas will be able to access over tens of thousands of titles from e-readers for free.

According to its website, the 1.5 million dollar BiblioTech currently has 600 e-readers, 200 pre-loaded enhanced e-readers for children, and 48 computer stations, 10 laptops and 40 tablets to use on-site.

Paperless technology will also help to manage funds. The team members aren’t tied up re-shelving, filing and categorising.

They spend most of their time providing one-on-one instruction with visitors, teaching people how to use devices and how to source materials. It’s a more interactive library experience.

Replacement costs have also been factored in to the project. Thefts can be easily prevented as devices cannot access the internet once they leave the library.

 Traditional libraries require much larger load-tolerances in construction due to the weight of materials, so are more costly to build. Book collections also require environmental controls that are costly to maintain.

Talking Cars Unveiled: USA may soon made it mandatory by 2017

USA may soon allow the talking cars to be mandatory by 2017. The announcement was made on 4 February 2014 by the National Highway Traffic Safety Administration (NHTSA) of the US.

Talking cars is the communication technology which enables cars to send out location, speed and direction data 10 times a second.

The new vehicle-to-vehicle communication technology cars will be able to communicate with each other. This will help towards preventing tens of thousands of crashes every year.

Approval follows a test project that begun in 2012 in which vehicles equipped with wireless devices were used to warn drivers about specific hazards such as an impending collision at a blind intersection, or a vehicle stopped ahead.

Cars will also be able to communicate with infrastructure like stop signs and traffic lights, and with motorcyclists, bicyclists and even pedestrians with specially equipped smart phones. That data will enable the cars to warn drivers to slow down, brake, turn on their windshield wipers or not to change lanes.

The technology can help avert rear-end, lane change, and intersection crashes. But the systems do not include automatic braking or steering.

The National Highway Traffic Safety Administration and safety advocates have pushed to make cars safer so passengers would be more likely to survive crashes.

Automakers seem largely on board with the technology, which would add about $100 to $300 to the cost of a car.

The full transition from current vehicle fleet to a connected fleet will take at least 10 years.

Scientist discovered Method to curb greenhouse gases

Scientists discovered a new method to convert harmful greenhouse gases into chemicals which can produce synthetic fuels on 2 February 2014.

A team of researchers at the University of Delaware has developed a highly selective catalyst capable of electrochemically converting carbon dioxide (a greenhouse gas) to carbon monoxide with 92 percent efficiency. The carbon monoxide then can be used to develop useful chemicals.

It was found that when a nano-porous silver electrocatalyst was used, it was 3000 times more active than polycrystalline silver, a catalyst commonly used in converting carbon dioxide to useful chemicals.

Silver is considered a promising material for a carbon dioxide reduction catalyst because of it offers high selectivity approximately 81 percent and because it costs much less than other precious metal catalysts. Additionally, because it is inorganic, silver remains more stable under harsh catalytic environments.

The exceptionally high activity is likely due to the UD-developed electrocatalyst’s extremely large and highly curved internal surface, which is approximately 150 times larger and 20 times intrinsically more active than polycrystalline silver.

The active sites on the curved internal surface required a much smaller than expected voltage to overcome the activation energy barrier needed drive the reaction.

To validate whether their findings were unique, the researchers compared the UD-developed nano-porous silver catalyst with other potential carbon dioxide electrocatalysts including polycrystalline silver and other silver nanostructures such as nanoparticles and nanowires.

The research team’s work is supported through funding from the American Chemical Society Petroleum Research Fund and University of Delaware Research Foundation.

Green House gases

A greenhouse gas (sometimes abbreviated GHG) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect.

The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Greenhouse gases greatly affect the temperature of the Earth; without them, Earth's surface would average about 33 °C colder, which is about 59 °F below the present average of 14 °C (57 °F).

Natural 3-D Counterpart to Graphene Discovered: New Form of Quantum Matter

"A 3DTDS is a natural three-dimensional counterpart to graphene with similar or even better electron mobility and velocity," says Yulin Chen, a physicist with Berkeley Lab's Advanced Light Source (ALS) when he initiated the study that led to this discovery, and now with the University of Oxford. "Because of its 3D Dirac fermions in the bulk, a 3DTDS also features intriguing non-saturating linear magnetoresistance that can be orders of magnitude higher than the materials now used in hard drives, and it opens the door to more efficient optical sensors."

Chen is the corresponding author of a paper in Science reporting the discovery. The paper is titled "Discovery of a Three-dimensional Topological Dirac Semimetal, Na3Bi." Co-authors were Zhongkai Liu, Bo Zhou, Yi Zhang, Zhijun Wang, Hongming Weng, Dharmalingam Prabhakaran, Sung-Kwan Mo, Zhi-Xun Shen, Zhong Fang, Xi Dai and Zahid Hussain.

Two of the most exciting new materials in the world of high technology today are graphene and topological insulators, crystalline materials that are electrically insulating in the bulk but conducting on the surface. Both feature 2D Dirac fermions (fermions that aren't their own antiparticle), which give rise to extraordinary and highly coveted physical properties. Topological insulators also possess a unique electronic structure, in which bulk electrons behave like those in an insulator while surface electrons behave like those in graphene.

"The swift development of graphene and topological insulators has raised questions as to whether there are 3D counterparts and other materials with unusual topology in their electronic structure," says Chen. "Our discovery answers both questions. In the sodium bismuthate we studied, the bulk conduction and valence bands touch only at discrete points and disperse linearly along all three momentum directions to form bulk 3D Dirac fermions. Furthermore, the topology of a 3DTSD electronic structure is also as unique as those of topological insulators."

The discovery was made at the Advanced Light Source (ALS), a DOE national user facility housed at Berkeley Lab, using beamline 10.0.1, which is optimized for electron structure studies. The collaborating research team first developed a special procedure to properly synthesize and transport the sodium bismuthate, a semi-metal compound identified as a strong 3DTDS candidate by co-authors Fang and Dai, theorists with the Chinese Academy of Sciences.

At ALS beamline 10.0.1, the collaborators determined the electronic structure of their material using Angle-Resolved Photoemission Spectroscopy (ARPES), in which x-rays striking a material surface or interface cause the photoemission of electrons at angles and kinetic energies that can be measured to obtain a detailed electronic spectrum.

"ALS beamline 10.0.1 is perfect for exploring new materials, as it has a unique capability whereby the analyzer is moved rather than the sample for the ARPES measurement scans," Chen says. "This made our work much easier as the cleaved sample surface of our material sometimes has multiple facets, which makes the rotating-sample measurement schemes typically employed for ARPES measurements difficult to carry out."

Sodium bismuthate is too unstable to be used in devices without proper packaging, but it triggers the exploration for the development of other 3DTDS materials more suitable for everyday devices, a search that is already underway. Sodium bismuthate can also be used to demonstrate potential applications of 3DTDS systems, which offer some distinct advantages over graphene.

"A 3DTDS system could provide a significant improvement in efficiency in many applications over graphene because of its 3D volume," Chen says. "Also, preparing large-size atomically thin single domain graphene films is still a challenge. It could be easier to fabricate graphene-type devices for a wider range of applications from 3DTDS systems."

In addition, Chen says, a 3DTDS system also opens the door to other novel physical properties, such as giant diamagnetism that diverges when energy approaches the 3D Dirac point, quantum magnetoresistance in the bulk, unique Landau level structures under strong magnetic fields, and oscillating quantum spin Hall effects. All of these novel properties can be a boon for future electronic technologies. Future 3DTDS systems can also serve as an ideal platform for applications in spintronics.

This research was supported by the DOE Office of Science and by the National Science Foundation of China.

Researchers Invent 'Sideways' Approach to 2-D Hybrid Materials

The study, published in the journal Science, could enable the use of new types of 2-D hybrid materials in technological applications and fundamental research.

By rethinking a traditional method of growing materials, the researchers combined two compounds -- graphene and boron nitride -- into a single layer only one atom thick. Graphene, which consists of carbon atoms arranged in hexagonal, honeycomb-like rings, has attracted waves of attention because of its high strength and electronic properties.

"People call graphene a wonder material that could revolutionize the landscape of nanotechnology and electronics," ORNL's An-Ping Li said. "Indeed, graphene has a lot of potential, but it has limits. To make use of graphene in applications or devices, we need to integrate graphene with other materials."

One method to combine differing materials into heterostructures is epitaxy, in which one material is grown on top of another such that both have the same crystalline structure. To grow the 2-D materials, the ORNL-UT research team directed the growth process horizontally instead of vertically.

The researchers first grew graphene on a copper foil, etched the graphene to create clean edges, and then grew boron nitride through chemical vapor deposition. Instead of conforming to the structure of the copper base layer as in conventional epitaxy, the boron nitride atoms took on the crystallography of the graphene.

"The graphene piece acted as a seed for the epitaxial growth in two-dimensional space, so that the crystallography of the boron nitride is solely determined by the graphene," UT's Gong Gu said.

Not only did the team's technique combine the two materials, it also produced an atomically sharp boundary, a one-dimensional interface, between the two materials. The ability to carefully control this interface, or "heterojunction," is important from an applied and fundamental perspective, says Gu.

"If we want to harness graphene in an application, we have to make use of the interface properties, since as Nobel laureate Herbert Kroemer once said 'the interface is the device,'" Li said. "By creating this clean, coherent, 1-D interface, our technique provides us with the opportunity to fabricate graphene-based devices for real applications."

The new technique also allows researchers to experimentally investigate the scientifically intriguing graphene-boron nitride boundary for the first time.

"There is a vast body of theoretical literature predicting wonderful physical properties of this peculiar boundary, in absence of any experimental validation so far," said Li, who leads an ORNL effort to study atomic-level structure-transport relationships using the lab's unique four-probe scanning tunneling microscopy facility. "Now we have a platform to explore these properties."

The research team anticipates that its method can be applied to other combinations of 2-D materials, assuming that the different crystalline structures are similar enough to match one another.

Ultra-Thin Flexible Transparent Electronics Can Wrap Around a Hair

Niko Münzenrieder submerges a ficus leaf in water containing pieces of a shiny metallic membrane. Using tweezers, he carefully moves one of these pieces on to the leaf of the houseplant. On lifting the leaf, the film sticks to it like glue. The post-doctoral researcher is demonstrating the special characteristics of this electronic component in the form of an ultra-thin membrane, which he has helped to develop. "These new thin-film transistors adhere to a wide range of surfaces and adapt perfectly," explains the physicist.

In Professor Gerhard Tröster's Electronics Lab, scientists have been researching flexible electronic components, such as transistors and sensors, for some time now. The aim is to weave these types of components into textiles or apply them to the skin in order to make objects 'smart', or develop unobtrusive, comfortable sensors that can monitor various functions of the body.

Supple but functional

The researchers have now taken a big step towards this goal and their work has recently been published in the journal Nature Communications. With this new form of thin-film technology, they have created a very flexible and functional electronics.

Within a year, Münzenrieder, together with Giovanni Salvatore, has developed a procedure to fabricate these thin-film components. The membrane consists of the polymer parylene, which the researchers evaporate layer by layer into a conventional two-inch wafer. The parylene film has a maximum thickness of 0.001 mm, making it 50 times thinner than a human hair. In subsequent steps, they used standardised methods to build transistors and sensors from semiconductor materials, such as indium gallium zinc oxide, and conductors, such as gold. The researchers then released the parylene film with its attached electronic components from the wafer.

An electronic component fabricated in this way is extremely flexible, adaptable and -- depending on the material used for the transistors -- transparent. The researchers confirmed the theoretically determined bending radius of 50 micrometers during experiments in which they placed the electronic membrane on human hair and found that the membrane wrapped itself around the hair with perfect conformability. The transistors, which are less flexible than the substrate due to the ceramic materials used in their construction, still worked perfectly despite the strong bend.

Smart contact lens measures intraocular pressure

Münzenrieder and Salvatore see 'smart' contact lenses as a potential area of application for their flexible electronics. In the initial tests, the researchers attached the thin-film transistors, along with strain gauges, to standard contact lenses. They placed these on an artificial eye and were able to examine whether the membrane, and particularly the electronics, could withstand the bending radius of the eye and continue to function. The tests showed, in fact, that this type of smart contact lens could be used to measure intraocular pressure, a key risk factor in the development of glaucoma.

However, the researchers must still overcome a few technical obstacles before a commercially viable solution can be considered. For instance, the way in which the electronics are attached to the contact lens has to be optimised to take into account the effects of the aqueous ocular environment. In addition, sensors and transistors require energy, albeit only a small amount, which currently has to be provided from an external source. "In the lab, the film can be easily connected to the energy supply under a microscope. However, a different solution would need to be found for a unit attached to the actual eye," says Münzenrieder.

Professor Tröster's laboratory has already attracted attention in the past with some unusual ideas for wearable electronics. For example, the researchers have developed textiles with electronic components woven into them and they have also used sensors to monitor the bodily functions of Swiss ski jumping star Simon Ammann during his jumps.

Shining light through skin to diagnose malaria

Researchers in the U.S. have come up with a way to rapidly diagnose malaria simply by shining brief pulses of light from a laser through the skin.

“This method is distinct from all previous diagnostic approaches, which all rely upon using a needle to obtain blood, require reagents to detect the infection, and are time- and labour-consuming,” noted the scientists in a paper published this week in the Proceedings of the National Academy of Sciences (PNAS).

Rugged and inexpensive microlasers exist that could be modified to create portable devices capable of operating in harsh conditions. Non-medical personnel would be able to operate these devices and obtain a diagnosis in seconds, according to their paper.

Such a device was under development, said Rice University’s Dimtri O. Lapotko, the senior author of the paper, in an email.

When a malaria parasite invades red blood cells, it gorges on the haemoglobin those cells contain. Haemoglobin is the molecule that helps carry oxygen to all parts of the body. The parasite turns the iron-containing haeme component, which can be toxic for the organism, into an insoluble pigment, haemozoin.

The technique developed by Dr. Lapotko and his colleagues relies on detecting the haemozoin in red blood cells. They achieve this by using a narrow band of near-infrared light that is strongly absorbed by haemozoin but not haemoglobin.

A brief pulse of light in this band from a low-power laser heated up the tiny particles of haemozoin, causing a “vapour nanobubble” to form in the fluid around each particle. These bubbles expand explosively and then collapse with a characteristic sound that could be picked up with an ultrasound sensor.

The scientists demonstrated the technique in animal trials using malaria-infected mice.

A probe that carried an optical fibre as well as an ultrasound sensor was clamped to the ear of the mice so that laser light could be shone at a surface blood vessel and the resulting sounds recorded.

The device was able to accurately pick out infected animals, even when only about one in a million red blood cells carried the parasite, their paper reported.

The first trials of the technology in humans was expected to begin in early 2014 at Houston where Rice University is based, according to a University press release quoting Dr. Lapotko.

“It is a fantastic technique” but has an important limitation, observed Vinod Prakash Sharma, who was founder director of the National Institute of Malaria Research in New Delhi.

The method would be unable to distinguish between two species of the parasite, Plasmodium falciparum and Plasmodium vivax, that cause malaria in India. Treatment depended on which parasite was infecting a patient.

The technique described in the PNAS paper would therefore have to be combined with ways of discriminating between the two, Dr. Sharma told this correspondent.

Moreover, haemozoin may persist in the blood even after the parasite has been cleared, remarked V. Arun Nagaraj, Ramanunjan Fellow at the Indian Institute of Science in Bangalore. With this technique, a previously-infected individual who had another bout of fever from some other cause might potentially be misdiagnosed as having malaria.

In 2013, we learned our beloved Milky Way may host billions of stars with Earth-like planets.

Image courtesy NASA/JPL-Caltech

Top 10 Scientific Discoveries of 2013

In November 2013, astronomers made a startling announcement: The Milky Way galaxy hosts at least 8.8 billion stars with planets the size of Earth. Those planets, the researchers said after studying NASA's Kepler data, revolve around their suns in a so-called Goldilocks zone. That zone is where life, as we know it, can exist.
"Just in our Milky Way galaxy alone, that's 8.8 billion throws of the biological dice," said Geoff Marcy, one of the study's authors [source: Borenstein].
The Kepler telescope, which experienced technical problems in summer 2013, was gazing at a thin slice of the Milky Way to see how many Earth-like planets might be out there. The astronomers then did some math homework and extrapolated that figure to the rest of the galaxy. The next step is to see if these Earth-like planets have atmospheres. The right kind of atmosphere is a good indication that life might exist on the planet's surface [source: Borenstein].
That finding is just one of many scientific discoveries that made headlines in 2013. Wait until you hear the other 10.

After announcing the discovery of King Richard III's remains in September 2012, archaeologists were able to confirm in 2013 that they had indeed unearthed the old boy.

© Darren Staples/Reuters/Corbis

10: King Richard III Confirmed

"A horse! A horse! My kingdom for a horse!"
That's our favorite tyrant in Act V, Scene IV of Shakespeare's "The Tragedy of King Richard the Third." He's on the battlefield about to take a tumble. He's in power, but alone.
The end came soon enough for Richard, the reviled (and occasionally revered) English monarch, on Aug. 22, 1485, at the Battle of Bosworth. After the battle, a group of friars buried Richard, naked, and with no marker or any other identifying papers. They jammed his skull into the grave so hard that it sat crooked against the wall of the shallow grave some 20 miles (32 kilometers) or so from the battlefield. Later on, someone built a parking lot over the king [source: Burns].
Thanks to the skeletal evidence, radiocarbon dating and a mitochondrial DNA match, archaeologists concluded in February 2013 that the remains unearthed in the parking lot a year before were those of Richard. Later, the researchers from England's University of Leicester even were able to discern that the king had a bad case of roundworm. The king was 32 when he died at Bosworth, the last battle of the War of the Roses, which ended with Henry the VII taking the throne [source: Ford and Smith Park].

Like that, except the one developed in 2013 by Harvard University scientists can perch on the head of pin.

© Yuya Shino/Reuters/Corbis

9: Minuscule Lithium-ion Battery

In June, Harvard University scientists announced the creation of a seriously tiny lithium-ion battery that could one day power Lilliputian robots or mini medical devices. Created with a 3-D printer, the battery is so small that it can rest on the head of a pin.
Three-dimensional printers, headline makers in their own right in 2013, make objects by piling layer upon layer of material on top of each other. Most 3-D printers manipulate plastic, but the one that fashioned the midget battery relied on a new type of material crammed with lithium-metal-oxide particles.
The petite power source is less than a millimeter in size. It weighs less than 100 micrograms but is able to store as much energy per gram as the larger lithium-ion batteries that power items such as laptops and electric cars [source: Powell].

Was this the year of the bionic eye? Several major developments occurred in the so-called cochlear implant for the vision impaired.

William West/AFP/Getty Images

8: Bionic Eye

Meanwhile, over in Australia, a bunch of engineers and designers unveiled one of the world's first bionic eyes in June. Using a microchip embedded in the skull and a digital camera set on a pair of glasses, the bionic eye has the potential to help 85 percent of people who are legally blind see the outlines of their surroundings [source: Hall].
Here's how this bionic eye works: Mounted on the snazzy glasses is a camera similar to the one on an iPhone. The camera captures an image, and a sensor inside the glasses directs the camera's field of vision as a person turns his or her head. A digital processor modifies the captured images and then sends the signal wirelessly to the chip implanted at the back of the brain. The chip sends electrical signals through tiny electrodes that stimulate the brain's visual center. Over time, the brain interprets these signals as images [source: Hall].

These funny-looking eusocial rodents could wind up teaching humans a lot about cancer.

© Wolfgang_Thieme/dpa/Corbis

7: Cancer-free Naked Mole Rats

Small and hairless, naked mole rats are so ugly that they're cute. Unlike many rodents though, these subterranean creatures have unusually long lives (30 years!) and don't get cancer. In June, researchers at the University of Rochester announced why that is. They said naked mole rats have a natural substance in between their tissues that keeps cancerous tumors away. This substance, known as hyaluronan, may one day lead to cancer treatments in humans.
How did researchers find this out? When they removed the hyaluronan from the tissue of the mole rats, the rats began to grow tumors. Apparently, the naked mole rats have a lot of hyaluronan that keeps tissues flexible, which is essential for burrowing and making sure their skin remains unscathed. Humans produce hyaluronan, too, but in much smaller quantities [source: Chow].

Artist's concept of the wondrous and wide-ranging Voyager spacecraft in flight

Image courtesy NASA/JPL

6: Voyager I Makes It to Interstellar Space

It's going, going, gone.
NASA hit the longest home run of its career when Voyager 1, like the Pioneers 10 and 11 spacecraft, said sayonara to the planets of our solar system and the sun's gravitational influence. Voyager 1 is now streaking through interstellar space sending information back to Earth. Although the craft said bon voyage in August 2012, it wasn't until September 2013 that scientists were sure it actually happened.
It was a remarkable event more than 36 years in the making. Voyager 1 left Earth in 1977 for Jupiter and Saturn and scampered past the so-called heliosphere, the boundary of the solar system where the sun's gravity has little effect. When scientists made the shocking announcement, the craft was 11.7 billion miles (18.8 billion kilometers) from Earth. Voyager 2 also is headed for interstellar space.

Peter Higgs, the British scientist responsible for starting all of this (Higgs) boson business, poses in front of a photo of the Atlas detector in London on Nov. 12, 2013.

© Toby Melville/Reuters/Corbis

5: Higgs Boson Confirmed

Every so often, there's a moment in science where everyone stands and cheers. That happened in March when scientists confirmed after decades of research (and some pretty promising July 2012 results) that they had found the Higgs boson. In 1964, a British physicist named Peter Higgs theorized that the tantalizingly elusive subatomic particle was the reason why matter has mass. Scientists working at an immense particle accelerator in Geneva, Switzerland, announced the discovery.
What does the Higgs boson supposedly do? People have used many metaphors to describe how it works. Some say it acts like molasses, dragging on particles as they move through it. Others compare it to a field of snow. Let's use that metaphor.
Some particles, like electrons, have little mass, while others have more mass. As these particles move through the universe, they interact with a Higgs field full of Higgs bosons, just like a person who moves through a snowy field. Electrons are like downhill skiers. They glide swiftly over the snow. Other particles that have more mass plod through the field like a person schlepping through snow in heavy boots. Still, other particles have no mass, so they don't interact with Higgs bosons at all. The discovery will help scientists explain how our universe works [source: Holmes].

Curiosity has had a busy couple of months on Mars drilling into rocks and discovering some of the key building blocks for life.

Image courtesy NASA/JPL-Caltech/MSSS

4: Mars and Microbes

Seven months after a NASA rover landed on Mars, scientists announced in March that the rover, Curiosity, found evidence the red planet could have been home to living microbes.
Here's how that happened: On Feb. 8, Curiosity drilled into a rock and found some of the key ingredients for life, including sulfur, nitrogen and oxygen. The rock was sitting in a part of Mars called Yellowknife Bay, which scientists say, was at the end of an ancient river system or lake bed. The rock contained minerals usually found in clay [sources: Wall, NASA].

Scientists just can't leave the idea of the invisibility cloak alone, and 2013 saw a few new advancements on the cloak that Harry Potter made famous.

buchachon/iStock/Thinkstock

3: Invisibility Cloak

When Harry Potter didn't want anyone to see him, all he had to do was pull on a magical cloak and -- poof! -- he was invisible. Although invisibility cloaks, which work by bending light around an object have been around since 2006, scientists said in June that they made a major breakthrough by building a broadband device that can hide objects at a wide range of light frequencies [source: MIT]. Of course, there was just one teeny drawback: The device made other parts of the object more noticeable.
Here's how: While a person might not be able to see an object at one point in the light spectrum, it makes another part of the object more visible. For example, the cloak might make an object invisible in the red light spectrum, but if it was illuminated by white light, which contains all colors, that object would become bright blue and stand out like a sore thumb. In other words, it's impossible to become fully invisible. The device could be used in biomedicine and in the military [source: Pocklington].

He may have been gone more for than 40 years, but he's certainly not forgotten, as Barbaturex morrisoni attests.

© Gonzalo Fuentes/Reuters/Corbis

2: Jim Morrison, the Lizard King

Jim Morrison, the inspiration behind the storied '70s rock band The Doors, might be dead (is he?), but he still lives on, and not just in his music. In June, scientists named a new species of lizard for the self-proclaimed, hard-rocking "Lizard King."
Barbaturex morrisoni was a rather large, plant-eating reptile that roamed the planet some 36-40 million years ago. B. morrisoni was as large a Dalmatian [source: Huffington Post]. The king of the lizards lived during a period in Earth's history when temperatures were skyrocketing, and, indeed, scientists think the warm temps contributed to B. morrisoni's unusual success as a big, herbivorous lizard.

A "Divest from climate change" banner is dropped over the Charles River by Boston students who aim to stop climate change by having their schools divest from the fossil fuel industry. Around 150 students from Boston area colleges and universities rallied on Dec. 8, 2013.

© Paul Weiskel/Demotix/Corbis

1: Climate Change Getting Worse

Speaking of rising temps, climate change is worsening, and according to a 2013 draft report from the Intergovernmental Panel on Climate Change, it will have "widespread and consequential" impacts for the entire planet. According to the report, climate change will make human health problems worse in many regions. Temperature increases will affect food crops such as wheat, rice and maize in tropical and temperate regions.
The report also predicts dire political consequences, such as civil war, as climate change diminishes food production, increases poverty and wreaks havoc with the economies of many nations. Moreover, by 2100, sea levels will rise, displacing hundreds of millions of people, particularly for multiple areas of Asia [source: Guillen].

Astronomers Discover Planet That Shouldn't Be There

An international team of astronomers, led by a University of Arizona graduate student, has discovered the most distantly orbiting planet found to date around a single, sun-like star. It is the first exoplanet -- a planet outside of our solar system -- discovered at the UA.

Weighing in at 11 times Jupiter's mass and orbiting its star at 650 times the average Earth-Sun distance, planet HD 106906 b is unlike anything in our own Solar System and throws a wrench in planet formation theories.

"This system is especially fascinating because no model of either planet or star formation fully explains what we see," said Vanessa Bailey, who led the research. Bailey is a fifth-year graduate student in the UA's Department of Astronomy.

It is thought that planets close to their stars, like Earth, coalesce from small asteroid-like bodies born in the primordial disk of dust and gas that surrounds a forming star. However, this process acts too slowly to grow giant planets far from their star. Another proposed mechanism is that giant planets can form from a fast, direct collapse of disk material. However, primordial disks rarely contain enough mass in their outer reaches to allow a planet like HD 106906 b to form. Several alternative hypotheses have been put forward, including formation like a mini binary star system.

"A binary star system can be formed when two adjacent clumps of gas collapse more or less independently to form stars, and these stars are close enough to each other to exert a mutual gravitation attraction and bind them together in an orbit," Bailey explained. "It is possible that in the case of the HD 106906 system the star and planet collapsed independently from clumps of gas, but for some reason the planet's progenitor clump was starved for material and never grew large enough to ignite and become a star."

According to Bailey, one problem with this scenario is that the mass ratio of the two stars in a binary system is typically no more than 10-to-1.

"In our case, the mass ratio is more than 100-to-1," she explained. "This extreme mass ratio is not predicted from binary star formation theories -- just like planet formation theory predicts that we cannot form planets so far from the host star."

This system is also of particular interest because researchers can still detect the remnant "debris disk" of material left over from planet and star formation.

"Systems like this one, where we have additional information about the environment in which the planet resides, have the potential to help us disentangle the various formation models," Bailey added. "Future observations of the planet's orbital motion and the primary star's debris disk may help answer that question."

At only 13 million years old, this young planet still glows from the residual heat of its formation. Because at 2,700 Fahrenheit (about 1,500 degrees Celsius) the planet is much cooler than its host star, it emits most of its energy as infrared rather than visible light. Earth, by comparison, formed 4.5 billion years ago and is thus about 350 times older than HD 106906 b.

Direct imaging observations require exquisitely sharp images, akin to those delivered by the Hubble Space Telescope. To reach this resolution from the ground requires a technology called Adaptive Optics, or AO. The team used the new Magellan Adaptive Optics (MagAO) system and Clio2 thermal infrared camera -- both technologies developed at the UA -- mounted on the 6.5 meter-diameter Magellan telescope in the Atacama Desert in Chile to take the discovery image.

UA astronomy professor and MagAO principal investigator Laird Close said: "MagAO was able to utilize its special Adaptive Secondary Mirror, with 585 actuators, each moving 1,000 times a second, to remove the blurring of the atmosphere. The atmospheric correction enabled the detection of the weak heat emitted from this exotic exoplanet without confusion from the hotter parent star."

"Clio was optimized for thermal infrared wavelengths, where giant planets are brightest compared to their host stars, meaning planets are most easily imaged at these wavelengths," explained UA astronomy professor and Clio principal investigator Philip Hinz, who directs the UA Center for Astronomical Adaptive Optics.

The team was able to confirm that the planet is moving together with its host star by examining Hubble Space Telescope data taken eight years prior for another research program. Using the FIRE spectrograph, also installed at the Magellan telescope, the team confirmed the planetary nature of the companion. "Images tell us an object is there and some information about its properties but only a spectrum gives us detailed information about its nature and composition," explained co-investigator Megan Reiter, a graduate student in the UA Department of Astronomy. "Such detailed information is rarely available for directly imaged exoplanets, making HD 106906 b a valuable target for future study."

"Every new directly detected planet pushes our understanding of how and where planets can form," said co-investigator Tiffany Meshkat, a graduate student at Leiden Observatory in the Netherlands. "This planet discovery is particularly exciting because it is in orbit so far from its parent star. This leads to many intriguing questions about its formation history and composition. Discoveries like HD 106906 b provide us with a deeper understanding of the diversity of other planetary systems."

The research paper, "HD 106906 b: A Planetary-mass Companion Outside a Massive Debris Disk," has been accepted for publication in The Astrophysical Journal Letters and will appear in a future issue.

MagAO's development was funded by the National Science Foundation's Major Research Instrumentation program, and its Telescope System Instrumentation Program and an Advanced Technologies and Instrumentation Award.

The members of the discovery team are Vanessa Bailey (UA), Tiffany Meshkat (Leiden Observatory [LO]), Megan Reiter (UA), Katie Morzinski (UA), Jared Males (UA), Kate Y. L. Su (UA), Philip M. Hinz (UA), Matthew Kenworthy (LO), Daniel Stark (UA), Eric Mamajek (University of Rochester), Runa Briguglio (Arcetri Observatory [AO]), Laird M. Close (UA), Katherine B. Follette (UA), Alfio Puglisi (AO), Timothy Rodigas (UA, Carnegie Institute of Washington [CIW]), Alycia J. Weinberger (CIW), and Marco Xompero (AO).

Oldest Hominin DNA Sequenced: Mitochondrial Genome of a 400,000-Year-Old Hominin from Spain Decoded

Sima de los Huesos, the "bone pit," is a cave site in Northern Spain that has yielded the world's largest assembly of Middle Pleistocene hominin fossils, consisting of at least 28 skeletons, which have been excavated and pieced together over the course of more than two decades by a Spanish team of paleontologists led by Juan-Luis Arsuaga. The fossils are classified as Homo heidelbergensis but also carry traits typical of Neandertals. Until now it had not been possible to study the DNA of these unique hominins.

Matthias Meyer and his team from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have developed new techniques for retrieving and sequencing highly degraded ancient DNA. They then joined forces with Juan-Luis Arsuaga and applied the new techniques to a cave bear from the Sima de los Huesos site. After this success, the researchers sampled two grams of bone powder from a hominin thigh bone from the cave. They extracted its DNA and sequenced the genome of the mitochondria or mtDNA, a small part of the genome that is passed down along the maternal line and occurs in many copies per cell. The researchers then compared this ancient mitochondrial DNA with Neandertals, Denisovans, present-day humans, and apes.

From the missing mutations in the old DNA sequences the researchers calculated that the Sima hominin lived about 400,000 years ago. They also found that it shared a common ancestor with the Denisovans, an extinct archaic group from Asia related to the Neandertals, about 700,000 years ago. "The fact that the mtDNA of the Sima de los Huesos hominin shares a common ancestor with Denisovan rather than Neandertal mtDNAs is unexpected since its skeletal remains carry Neandertal-derived features," says Matthias Meyer. Considering their age and Neandertal-like features, the Sima hominins were likely related to the population ancestral to both Neandertals and Denisovans. Another possibility is that gene flow from yet another group of hominins brought the Denisova-like mtDNA into the Sima hominins or their ancestors.

"Our results show that we can now study DNA from human ancestors that are hundreds of thousands of years old. This opens prospects to study the genes of the ancestors of Neandertals and Denisovans. It is tremendously exciting" says Svante Pääbo, director at the Max Planck Institute for Evolutionary Anthropology.

"This unexpected result points to a complex pattern of evolution in the origin of Neandertals and modern humans. I hope that more research will help clarify the genetic relationships of the hominins from Sima de los Huesos to Neandertals and Denisovans" says Juan-Luis Arsuaga, director of the Center for Research on Human Evolution and Behaviour. The researchers are now pursuing this goal by focusing on retrieving DNA from more individuals from this site and on retrieving also nuclear DNA sequences.

New Effect Couples Electricity and Magnetism in Materials

Major industries such as modern microelectronics are based on the interaction between matter and electromagnetism. Electromagnetic signals can be processed and stored in specially tailored materials. In materials science, electric and magnetic effects have usually been studied separately. There are, however, extraordinary materials called "multiferroics," in which electric and magnetic excitations are closely linked. Scientists at the Vienna University of Technology (TU Wien) have now shown in an experiment that magnetic properties and excitations can be influenced by an electric voltage. This opens up completely new possibilities for electronics at high frequencies.

The Best of Two Worlds

It has been well known for a long time that electricity and magnetism are two sides of the same coin. Waves in free space, such as visible light or mobile phone radiation, always consist of both an electric and a magnetic component. When it comes to material properties, however, electricity and magnetism have been viewed as separate topics. There are materials with magnetic ordering, which react to magnetic fields, and there are materials with electric ordering, which can be influenced by electric fields.

A magnet has a magnetic field, but no electric field. In a piezoelectric crystal, on the other hand, electric fields can be generated, but no magnetic fields. Having both at the same time seemed impossible. "Usually, both effects are created in very different ways," says Professor Andrei Pimenov (TU Vienna). "Magnetic ordering comes from electrons aligning their magnetic moments, electric ordering comes from positive and negative charges moving with respect to one another."

Electromagnons

In 2006, Andrei Pimenov (while working at Augsburg University) found evidence of excitations which are based on both electric and magnetic ordering. These excitations, which have been dubbed "electromagnons," have been hotly debated by materials scientists ever since. Now Pimenov and his team have succeeded in switching such excitations on and off with an electric field in a special material made of dysprosium, manganese and oxygen (DyMnO3). In this material, many electrons align their magnetic moments at low temperatures. Each electron has a magnetic direction which is slightly distorted with respect to the adjoining electron -- therefore the electrons create spiral of magnetic moments. The spiral has two possible orientations -- clockwise or counterclockwise -- and, surprisingly, an external electric field can switch between these two possibilities.

Vibrating Atoms, Wobbling Moments

In magneto-electric materials, the charges and the magnetic moments of the atoms are connected. In dysprosium manganese oxide, this connection is particularly strong: "When the magnetic moments wobble, the electric charges move too," says Andrei Pimenov. In this material, magnetic moments and electric charges simultaneously play a part in the excitation, and therefore both can be influenced by one single external field.

The effect can be demonstrated by sending terahertz radiation through the material: The polarization of the terahertz beam is changed if the multiferroic material exhibits magnetic ordering. If the magnetic spiral in the material can be switched with an electric field, this electric field eventually determines, whether the polarization of the terahertz beam is being rotated.

There are many ideas for future applications: Wherever it is desirable to combine the respective advantages of magnetic and electric effects, the new magneto-electric materials could be used in the future. This could lead to new kinds of amplifiers, transistors or data storage devices. Also, highly sensitive sensors could be built with electromagnon technology.

Solar-Powered Battery Woven Into Fabric Overcomes Hurdle for 'Wearable Electronics'

Taek-Soo Kim, Jung-Yong Lee, Jang Wook Choi and colleagues explain that electronic textiles have the potential to integrate smartphone functions into clothes, eyeglasses, watches and materials worn on the skin. Possibilities range from the practical -- for example, allowing athletes to monitor vital signs -- to the aesthetic, such as lighting up patterns on clothing. The bottleneck slowing progress toward development of a wider range of flexible e-fabrics and materials is the battery technology required to power them. Current wearable electronics, such as smartwatches and Google Glass, still require a charger with a cord, and already-developed textile batteries are costly and impractical. To unlink smart technology from the wall socket, the team had to rethink what materials are best suited for use in a flexible, rechargeable battery that's also inexpensive.

They tested unconventional materials and found that they could coat polyester yarn with nickel and then carbon, and use polyurethane as a binder and separator to produce a flexible battery that kept working, even after being folded and unfolded many times. They also integrated lightweight solar cells to recharge the battery without disassembling it from clothing or requiring the wearer to plug in.

The authors acknowledge funding from the National Research Foundation of Korea.

Scientists build world’s smallest FM radio transmitter

US researchers have used graphene to create the world’s smallest FM radio transmitter — a nano-mechanical system that can create FM signals.

A team of researchers from Columbia University, led by mechanical engineering Professor James Hone and electrical engineering Professor Kenneth Shepard, took advantage of graphene’s special properties — its mechanical strength and electrical conduction — and developed a nano-mechanical system that can create FM signals.

“This work is significant in that it demonstrates an application of graphene that cannot be achieved using conventional materials,” Prof. Hone said.

“And it’s an important first step in advancing wireless signal processing and designing ultrathin, efficient cell phones. Our devices are much smaller than any other sources of radio signals, and can be put on the same chip that’s used for data processing,” Prof. Hone added.

In the new study, the team took advantage of graphene’s mechanical ‘stretchability’ to tune the output frequency of their custom oscillator, creating a nano-mechanical version of an electronic component known as a voltage controlled oscillator (VCO).

With a VCO, explained Prof. Hone, it is easy to generate FM signal, exactly what is used for FM radio broadcasting.

The team built a graphene NEMS whose frequency was about 100 megahertz, which lies right in the middle of the FM radio band (87.7 to 108 MHz).

They used low-frequency musical signals (both pure tones and songs from a smartphone) to modulate the 100 MHz carrier signal from the graphene, and then retrieved the musical signals again using an ordinary FM radio receiver.

“This device is by far the smallest system that can create such FM signals,” said Prof. Hone.

The study is published in the journal Nature Nanotechnology.

Scientists Invent Self-Healing Battery Electrode

They reported the advance in the Nov. 19 issue of Nature Chemistry.

"Self-healing is very important for the survival and long lifetimes of animals and plants," said Chao Wang, a postdoctoral researcher at Stanford and one of two principal authors of the paper. "We want to incorporate this feature into lithium ion batteries so they will have a long lifetime as well."

Chao developed the self-healing polymer in the lab of Stanford Professor Zhenan Bao, whose group has been working on flexible electronic skin for use in robots, sensors, prosthetic limbs and other applications. For the battery project he added tiny nanoparticles of carbon to the polymer so it would conduct electricity.

"We found that silicon electrodes lasted 10 times longer when coated with the self-healing polymer, which repaired any cracks within just a few hours," Bao said.

"Their capacity for storing energy is in the practical range now, but we would certainly like to push that," said Yi Cui, an associate professor at SLAC and Stanford who led the research with Bao. The electrodes worked for about 100 charge-discharge cycles without significantly losing their energy storage capacity. "That's still quite a way from the goal of about 500 cycles for cell phones and 3,000 cycles for an electric vehicle," Cui said, "but the promise is there, and from all our data it looks like it's working."

Researchers worldwide are racing to find ways to store more energy in the negative electrodes of lithium ion batteries to achieve higher performance while reducing weight. One of the most promising electrode materials is silicon; it has a high capacity for soaking up lithium ions from the battery fluid during charging and then releasing them when the battery is put to work.

But this high capacity comes at a price: Silicon electrodes swell to three times normal size and shrink back down again each time the battery charges and discharges, and the brittle material soon cracks and falls apart, degrading battery performance. This is a problem for all electrodes in high-capacity batteries, said Hui Wu, a former Stanford postdoc who is now a faculty member at Tsinghua University in Beijing, the other principal author of the paper.

To make the self-healing coating, scientists deliberately weakened some of the chemical bonds within polymers -- long, chain-like molecules with many identical units. The resulting material breaks easily, but the broken ends are chemically drawn to each other and quickly link up again, mimicking the process that allows biological molecules such as DNA to assemble, rearrange and break down.

Researchers in Cui's lab and elsewhere have tested a number of ways to keep silicon electrodes intact and improve their performance. Some are being explored for commercial uses, but many involve exotic materials and fabrication techniques that are challenging to scale up for production.

The self-healing electrode, which is made from silicon microparticles that are widely used in the semiconductor and solar cell industry, is the first solution that seems to offer a practical road forward, Cui said. The researchers said they think this approach could work for other electrode materials as well, and they will continue to refine the technique to improve the silicon electrode's performance and longevity.

Large Graphene Crystals With Exceptional Electrical Properties Created

The team used surface oxygen to grow centimeter-size single graphene crystals on copper. The crystals were about 10,000 times as large as the largest crystals from only four years ago. Very large single crystals have exceptional electrical properties.

"The game we play is that we want nucleation (the growth of tiny 'crystal seeds') to occur, but we also want to harness and control how many of these tiny nuclei there are, and which will grow larger," said Rodney S. Ruoff, professor in the Cockrell School of Engineering. "Oxygen at the right surface concentration means only a few nuclei grow, and winners can grow into very large crystals."

The team -- led by postdoctoral fellow Yufeng Hao and Ruoff of the Department of Mechanical Engineering and the Materials Science and Engineering Program, along with Luigi Colombo, a material scientist with Texas Instruments -- worked for three years on the graphene growth method. The team's paper, "The Role of Surface Oxygen in the Growth of Large Single-Crystal Graphene on Copper," is featured on the cover of the Nov. 8, 2013, issue of Science.

One of the world's strongest materials, graphene is flexible and has high electrical and thermal conductivity that makes it a promising material for flexible electronics, solar cells, batteries and high-speed transistors. The team's understanding of how graphene growth is influenced by differing amounts of surface oxygen is a major step toward improved high-quality graphene films at industrial scale.

The team's method "is a fundamental breakthrough, which will lead to growth of high-quality and large area graphene film," said Sanjay Banerjee, who heads the Cockrell School's South West Academy of Nanoelectronics (SWAN). "By increasing the single-crystal domain sizes, the electronic transport properties will be dramatically improved and lead to new applications in flexible electronics."

Graphene has always been grown in a polycrystalline form, that is, it is composed of many crystals that are joined together with irregular chemical bonding at the boundaries between crystals ("grain boundaries"), something like a patch-work quilt. Large single-crystal graphene is of great interest because the grain boundaries in polycrystalline material have defects, and eliminating such defects makes for a better material.

By controlling the concentration of surface oxygen, the researchers could increase the crystal size from a millimeter to a centimeter. Rather than hexagon-shaped and smaller crystals, the addition of the right amount of surface oxygen produced much larger single crystals with multibranched edges, similar to a snowflake.

"In the long run it might be possible to achieve meter-length single crystals," Ruoff said. "This has been possible with other materials, such as silicon and quartz. Even a centimeter crystal size -- if the grain boundaries are not too defective -- is extremely significant."

"We can start to think of this material's potential use in airplanes and in other structural applications -- if it proves to be exceptionally strong at length scales like parts of an airplane wing, and so on," he said.

Another major finding by the team was that the "carrier mobility" of electrons (how fast the electrons move) in graphene films grown in the presence of surface oxygen is exceptionally high. This is important because the speed at which the charge carriers move is important for many electronic devices -- the higher the speed, the faster the device can perform.

Yufeng Hao says he thinks the knowledge gained in this study could prove useful to industry.

"The high quality of the graphene grown by our method will likely be developed further by industry, and that will eventually allow devices to be faster and more efficient," Hao said.

Single-crystal films can also be used for the evaluation and development of new types of devices that call for a larger scale than could be achieved before, added Colombo.

"At this time, there are no other reported techniques that can provide high quality transferrable films," Colombo said. "The material we were able to grow will be much more uniform in its properties than a polycrystalline film."

Wireless Device Converts 'Lost' Energy Into Electric Power: Metamaterial Cells Provide Electric Power as Efficiently as Solar Panels

The device wirelessly converts the microwave signal to direct current voltage capable of recharging a cell phone battery or other small electronic device, according to a report appearing in the journal Applied Physics Letters in December 2013.

It operates on a similar principle to solar panels, which convert light energy into electrical current. But this versatile energy harvester could be tuned to harvest the signal from other energy sources, including satellite signals, sound signals or Wi-Fi signals, the researchers say.

The key to the power harvester lies in its application of metamaterials, engineered structures that can capture various forms of wave energy and tune them for useful applications.

Undergraduate engineering student Allen Hawkes, working with graduate student Alexander Katko and lead investigator Steven Cummer, professor of electrical and computer engineering, designed an electrical circuit capable of harvesting microwaves.

They used a series of five fiberglass and copper energy conductors wired together on a circuit board to convert microwaves into 7.3V of electrical energy. By comparison, Universal Serial Bus (USB) chargers for small electronic devices provide about 5V of power.

"We were aiming for the highest energy efficiency we could achieve," said Hawkes. "We had been getting energy efficiency around 6 to 10 percent, but with this design we were able to dramatically improve energy conversion to 37 percent, which is comparable to what is achieved in solar cells."

"It's possible to use this design for a lot of different frequencies and types of energy, including vibration and sound energy harvesting," Katko said. "Until now, a lot of work with metamaterials has been theoretical. We are showing that with a little work, these materials can be useful for consumer applications."

For instance, a metamaterial coating could be applied to the ceiling of a room to redirect and recover a Wi-Fi signal that would otherwise be lost, Katko said. Another application could be to improve the energy efficiency of appliances by wirelessly recovering power that is now lost during use.

"The properties of metamaterials allow for design flexibility not possible with ordinary devices like antennas," said Katko. "When traditional antennas are close to each other in space they talk to each other and interfere with each other's operation. The design process used to create our metamaterial array takes these effects into account, allowing the cells to work together."

With additional modifications, the researchers said the power-harvesting metamaterial could potentially be built into a cell phone, allowing the phone to recharge wirelessly while not in use. This feature could, in principle, allow people living in locations without ready access to a conventional power outlet to harvest energy from a nearby cell phone tower instead.

"Our work demonstrates a simple and inexpensive approach to electromagnetic power harvesting," said Cummer. "The beauty of the design is that the basic building blocks are self-contained and additive. One can simply assemble more blocks to increase the scavenged power."

For example, a series of power-harvesting blocks could be assembled to capture the signal from a known set of satellites passing overhead, the researchers explained. The small amount of energy generated from these signals might power a sensor network in a remote location such as a mountaintop or desert, allowing data collection for a long-term study that takes infrequent measurements.

Diamond Imperfections Pave the Way to Technology Gold

Using two-dimensional electronic spectroscopy on pico- and femto-second time-scales, a research team led by Graham Fleming, Vice Chancellor for Research at UC Berkeley and faculty scientist with Berkeley Lab's Physical Biosciences Division, has recorded unprecedented observations of energy moving through the atom-sized diamond impurities known as nitrogen-vacancy (NV) centers. An NV center is created when two adjacent carbon atoms in a diamond crystal are replaced by a nitrogen atom and an empty gap.

"Our use of 2D electronic spectroscopy allowed us to essentially map the flow of energy through the NV center in real time and observe critical quantum mechanical effects," Fleming says. "The results hold broad implications for magnetometry, quantum information, nanophotonics, sensing and ultrafast spectroscopy."

Fleming is the corresponding author of a paper in Nature Physics that describes this research entitled "Vibrational and electronic dynamics of nitrogen-vacancy centres in diamond revealed by two-dimensional ultrafast spectroscopy." The lead author is Vanessa Huxter, former member of Fleming's research group and now a professor at the University of Arizona. Other co-authors are Thomas Oliver and Dmitry Budker, both of whom holds joint appointments with Berkeley Lab and UC Berkeley.

These 2D electronic spectroscopy measurements have provided us with the first window into the ultrafast dynamics of NV centers in diamond," says Huxter. "We were able to observe previously hidden vibrational and electronic properties of the NV center system, including the discovery of vibrational coherences lasting about two picoseconds, which on a quantum mechanical scale is a surprisingly long time."

Given the ubiquitous presence of weak magnetic fields, a sufficiently sensitive detector could be used in a wide range of applications including medical diagnostic and treatment procedures, chemical analyses, energy exploration and homeland security (to detect explosives). Diamond NV centers are held to be one of the finest magnetic sensors possible on the nanoscale. Diamond NV centers are also highly promising candidates for the creation of qubits -- data encoded through quantum-spin rather than electrical charge that will be the heart and soul of quantum computing. Qubits can store exponentially more data and process it billions of times faster than classical computer bits. However, for these rich promises to be fully met, a much better fundamental understanding is needed of the electronic-state dynamics when an NV center is energized.

Says co-author Budker, a UC Berkeley physics professor with Berkeley Lab's Nuclear Sciences Division and leading authority on NV center physics, "NV centers in diamond are already becoming a workhorse in magnetometry and other sensor fields, but they remain somewhat of a black box in that we still don't know understand some important features of their energy levels and dynamics. Our findings in this study provide a starting point for new insights into such critical electronic-state phenomena as dephasing, spin addressing and relaxation."

This study was made possible by the unique 2D electronic spectroscopy technique, which was first developed by Fleming and his research group to study the quantum mechanical underpinnings of photosynthesis. This ultrafast technique enables researchers to track the transfer of energy between atoms or molecules that are coupled (connected) through their electronic and vibrational states. Tracking is done through both time and space. It is accomplished by sequentially flashing light from three laser beams on a sample while a fourth beam serves as a local oscillator to amplify and phase-match the resulting spectroscopic signals.

"By providing femtosecond temporal resolution and nanometer spatial resolution, 2D electronic spectroscopy allows us to simultaneously follow the dynamics of multiple electronic states," says Fleming, who has compared this technology to the early super-heterodyne radios.

In this new study, the use of 2D electronic spectroscopy revealed that the vibrational modes of NV centers in diamond -- a subject of keen scientific interest because these modes directly affect optical and material properties -- are strongly coupled to the defect.

"We were able to identify a number of individual vibrational modes and found that these modes were almost all local to the defect centers and that they were coherent -- quantum mechanically coupled -- for about two picoseconds," says Huxter.

"Through a combination of theory and observation, researchers had suspected that NV center vibrational modes were primarily local to the defect, but our direct observation of the vibrations and their coupling to the excitation states confirms this idea."

In addition, the researchers also were able to measure non-radiative relaxation in the excited state, a property that must be understood and exploited for the creation of qubits.

"We found that the non-radiative relaxation timescale for NV centers in diamond was around four picoseconds, which was slower than we had expected given the number of vibrational states," Huxter says.

The information acquired from this study should make it possible to tune the properties of NV centers in diamonds and open up new avenues for research.

"For example, by optically pumping the NV centers we could specifically excite phonon modes based on their coupling factors," Fleming says. "This would allow the development of diamonds with NV centers that can be used for quantum storage and information processing based on both phonons and spin."

This research was supported primarily by a grant from the National Science Foundation.

Synaptic Transistor Learns While It Computes

Our brains have upwards of 86 billion neurons, connected by synapses that not only complete myriad logic circuits; they continuously adapt to stimuli, strengthening some connections while weakening others. We call that process learning, and it enables the kind of rapid, highly efficient computational processes that put Siri and Blue Gene to shame.

Materials scientists at the Harvard School of Engineering and Applied Sciences (SEAS) have now created a new type of transistor that mimics the behavior of a synapse. The novel device simultaneously modulates the flow of information in a circuit and physically adapts to changing signals.

Exploiting unusual properties in modern materials, the synaptic transistor could mark the beginning of a new kind of artificial intelligence: one embedded not in smart algorithms but in the very architecture of a computer. The findings appear in Nature Communications.

"There's extraordinary interest in building energy-efficient electronics these days," says principal investigator Shriram Ramanathan, associate professor of materials science at Harvard SEAS. "Historically, people have been focused on speed, but with speed comes the penalty of power dissipation. With electronics becoming more and more powerful and ubiquitous, you could have a huge impact by cutting down the amount of energy they consume."

The human mind, for all its phenomenal computing power, runs on roughly 20 Watts of energy (less than a household light bulb), so it offers a natural model for engineers.

"The transistor we've demonstrated is really an analog to the synapse in our brains," says co-lead author Jian Shi, a postdoctoral fellow at SEAS. "Each time a neuron initiates an action and another neuron reacts, the synapse between them increases the strength of its connection. And the faster the neurons spike each time, the stronger the synaptic connection. Essentially, it memorizes the action between the neurons."

In principle, a system integrating millions of tiny synaptic transistors and neuron terminals could take parallel computing into a new era of ultra-efficient high performance.

While calcium ions and receptors effect a change in a biological synapse, the artificial version achieves the same plasticity with oxygen ions. When a voltage is applied, these ions slip in and out of the crystal lattice of a very thin (80-nanometer) film of samarium nickelate, which acts as the synapse channel between two platinum "axon" and "dendrite" terminals. The varying concentration of ions in the nickelate raises or lowers its conductance -- that is, its ability to carry information on an electrical current -- and, just as in a natural synapse, the strength of the connection depends on the time delay in the electrical signal.

Structurally, the device consists of the nickelate semiconductor sandwiched between two platinum electrodes and adjacent to a small pocket of ionic liquid. An external circuit multiplexer converts the time delay into a magnitude of voltage which it applies to the ionic liquid, creating an electric field that either drives ions into the nickelate or removes them. The entire device, just a few hundred microns long, is embedded in a silicon chip.

The synaptic transistor offers several immediate advantages over traditional silicon transistors. For a start, it is not restricted to the binary system of ones and zeros.

"This system changes its conductance in an analog way, continuously, as the composition of the material changes," explains Shi. "It would be rather challenging to use CMOS, the traditional circuit technology, to imitate a synapse, because real biological synapses have a practically unlimited number of possible states -- not just 'on' or 'off.'"

The synaptic transistor offers another advantage: non-volatile memory, which means even when power is interrupted, the device remembers its state.

Additionally, the new transistor is inherently energy efficient. The nickelate belongs to an unusual class of materials, called correlated electron systems, that can undergo an insulator-metal transition. At a certain temperature -- or, in this case, when exposed to an external field -- the conductance of the material suddenly changes.

"We exploit the extreme sensitivity of this material," says Ramanathan. "A very small excitation allows you to get a large signal, so the input energy required to drive this switching is potentially very small. That could translate into a large boost for energy efficiency."

The nickelate system is also well positioned for seamless integration into existing silicon-based systems.

"In this paper, we demonstrate high-temperature operation, but the beauty of this type of a device is that the 'learning' behavior is more or less temperature insensitive, and that's a big advantage," says Ramanathan. "We can operate this anywhere from about room temperature up to at least 160 degrees Celsius."

For now, the limitations relate to the challenges of synthesizing a relatively unexplored material system, and to the size of the device, which affects its speed.

"In our proof-of-concept device, the time constant is really set by our experimental geometry," says Ramanathan. "In other words, to really make a super-fast device, all you'd have to do is confine the liquid and position the gate electrode closer to it."

In fact, Ramanathan and his research team are already planning, with microfluidics experts at SEAS, to investigate the possibilities and limits for this "ultimate fluidic transistor."

He also has a seed grant from the National Academy of Sciences to explore the integration of synaptic transistors into bioinspired circuits, with L. Mahadevan, Lola England de Valpine Professor of Applied Mathematics, professor of organismic and evolutionary biology, and professor of physics.

"In the SEAS setting it's very exciting; we're able to collaborate easily with people from very diverse interests," Ramanathan says.

For the materials scientist, as much curiosity derives from exploring the capabilities of correlated oxides (like the nickelate used in this study) as from the possible applications.

"You have to build new instrumentation to be able to synthesize these new materials, but once you're able to do that, you really have a completely new material system whose properties are virtually unexplored," Ramanathan says. "It's very exciting to have such materials to work with, where very little is known about them and you have an opportunity to build knowledge from scratch."

"This kind of proof-of-concept demonstration carries that work into the 'applied' world," he adds, "where you can really translate these exotic electronic properties into compelling, state-of-the-art devices."

This research was supported by the National Science Foundation (NSF), the Army Research Office's Multidisciplinary University Research Initiative, and the Air Force Office of Scientific Research. The team also benefited from the facilities at the Harvard Center for Nanoscale Systems, a member of the NSF-supported National Nanotechnology Infrastructure Network. Sieu D. Ha, a postdoctoral fellow at SEAS, was the co-lead author; additional coauthors included graduate student You Zhou and Frank Schoofs, a former postdoctoral fellow.

Super-Thin Membranes Clear the Way for Chip-Sized Pumps

But a super-thin silicon membrane developed at the University of Rochester could now make it possible to drastically shrink the power source, paving the way for diagnostic devices the size of a credit card.

"Up until now, electroosmotic pumps have had to operate at a very high voltage -- about 10 kilovolts," said James McGrath, associate professor of biomedical engineering. "Our device works in the range of one-quarter of a volt, which means it can be integrated into devices and powered with small batteries."

McGrath's research paper is being published this week by the journal Proceedings of the National Academy of Sciences.

McGrath and his team use porous nanocrystalline silicon (pnc-Si) membranes that are microscopically thin -- it takes more than one thousand stacked on top of each other to equal the width of a human hair. And that's what allows for a low-voltage system.

A porous membrane needs to be placed between two electrodes in order to create what's known as electroosmotic flow, which occurs when an electric field interacts with ions on a charged surface, causing fluids to move through channels. The membranes previously used in EOPs have resulted in a significant voltage drop between the electrodes, forcing engineers to begin with bulky, high-voltage power sources. The thin pnc Si membranes allow the electrodes to be placed much closer to each other, creating a much stronger electric field with a much smaller drop in voltage. As a result, a smaller power source is needed.

"Up until now, not everything associated with miniature pumps was miniaturized," said McGrath. "Our device opens the door for a tremendous number of applications."

Along with medical applications, it's been suggested that EOPs could be used to cool electronic devices. As electronic devices get smaller, components are packed more tightly, making it easier for the devices to overheat. With miniature power supplies, it may be possible to use EOPs to help cool laptops and other portable electronic devices.

McGrath said there's one other benefit to the silicon membranes. "Due to scalable fabrication methods, the nanocrystalline silicon membranes are inexpensive to make and can be easily integrated on silicon or silica-based microfluid chips."