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Figure 1: A comparison of electron beams with parallel (top) and antiparallel (bottom) spin and vortex orientation. The plot shows the density (grey) and current distributions (arrows) for electrons in the x and y direction, with either ‘up’ (+) or ‘down’ (-) spin, respectively. For electrons in the center of the beam, the distribution is predicted to be different for both cases. Photo Credit: 2011 American Physical Society

Researchers at the RIKEN Advanced Science Institute (ASI) have developed a theory that provides an understanding of relativistic electron vortex beams. Through the combined consideration of quantum and relativistic properties of the electrons in the beam, the researchers found that spin–orb Vending Computer  it interaction results in a diffe distribution power line monitoring  rent behavior for vortex beams made of electrons with spins pointing up or down, respectively.

Whether a car or a ball, the forces acting on a body moving in a straight line are very different to those acting on one moving in tight curves. This maxim also holds true at microscopic scales. As such, a beam of electrons that moves forward linearly has different properties to one with vortex-like properties. Since vortex beams show properties in magnetic fields that could lead to nove industrial m2m  l applications, a RIKEN-led research team has developed a theory that provides an understanding of these properties1.

“Ours is the first comprehensive theory of relativistic electron vortex beams and adds significantly to their understanding,” comments team member Konstantin Bliokh from the RIKEN Advanced Science Institute (ASI).

Like any particle, electrons can exhibit wave-like characteristics; and, understanding this behavior is critical to understanding the behavior of vortex beams so they can be harnessed in future applications. Unlike the broad front of an ocean wave hitting a beach, however, the oscillations of electron waves are out of sync along the beam: the slight shifts in their timing gives the waves a corkscrew character.

A vortex beam shows unique and potentially exploitable quantum effects arising from the interplay between the so-called ‘orbital angular momentum’ of its electrons and their intrinsic property called spin. The potential of these beams became apparent only recently, when they were demonstrated for the first time by Masaya Uchida and Akira Tonomura from ASI2.

The complex mixture of electron spin, beam vortex properties and the relativistic properties of the electrons has complicated the theoretical understanding of the beams, says team leader Franco Nori also from ASI. He explains that their fundamental theoretical description was possible only through the combined consideration of quantum and relativistic properties of the electrons in the beam. This provided new insights into the interaction between the electrons’ spin and the vortex property of the beam. In particular, the researchers found that this so-called spin–orbit interaction results in a different behavior for vortex beams made of electrons with spins pointing up or down, respectively—an effect that should be observable (Fig. 1).

Beyond providing these fundamental insights, the new theory also has sound practical implications, as the beams are very sensitive to magnetic fields, according to Nori. “The theoretical understanding that we have reached will eventually contribute to the development of enhanced electron microscopes that can image magnetic materials with atomic resolution,” he says.

Image: RIKEN Advanced Science Institute/2011 American Physical Society

The corresponding author for this highlight is based at the Digital Materials Team, RIKEN Advanced Science Institute

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Elemental mapping of the location of iron atoms (blue) in the magnetic nanoparticles and cadmium (red) in the fluorescent quantum dots provide a clear visualization of the way the two kinds of particles naturally separate themselves into a core-and-shell structure.

A team of researchers has developed particles that can glow with color-coded light and be manipulated with magnets, improving the likelihood of tracking the position of the nanoparticles as they move within the body or inside a cell.

A long-sought goal of creating particles that can emit a colorful fluorescent glow in a biological environment, and that could be precisely manipulated into position within living cells, has been achieved by a team of researchers at MIT and several other institutions. The finding is reported this week in the journal Nature Communications.

The new technology could make it possible to track the position of the nanoparticles as they move within the body or inside a cell. At the same time, the nanoparticles could be manipulated precisely by applying a magn 3g router etic field to pull them along. And finally, the particles could have a coating of a bioreactive substance that could seek out and bind with particular molecules within the body, such as markers for tumor cells or other disease agents.

“It’s been a dream of mine for many years to have a nanomaterial that incorporates both fluorescence and magnetism in a single compact object,” says Moungi Bawendi, the Lester Wolfe Professor of Chemistry at MIT and senior author of the new paper. While other groups have achieved some combination of these two properties, Bawendi says that he “was never very satisfied” with results previously achieved by his own team or others.

For one thing, he says, such particles have been too large to make practical probes of living tissue: “They’ve tended to have a lot of wasted volume,” Bawendi says. “Compactness is critical for biological and a lot of other applications.”

In addition, previous efforts were unable to produce particles of uniform and predictable size, which could also be an essential property for diagnostic or therapeutic applications.

Moreover, Bawendi says, “We wanted to be able to manipulate these structures inside the cells with magnetic fields, but also know exactly what it is we’re moving.” All of these goals are achieved by the new nanoparticles, which can be identified with great precision by the wavelength of their fluorescent emissions.

The new method produces the combination of desired properties “in as small a package as possible,” Bawendi says — which could help pave the way for particles with other useful properties, such as the ability to bind with a specific type of bioreceptor, or another molecule of interest.

In the technique developed by Bawend cloud platform  i’s team, led by lead author and postdoc Ou Chen, the nanoparticles crystallize such that they self-assemble in exactly the way that leads to the most useful outcome: The magnetic particles cluster at the center, while fluorescent particles form a uniform coating around them. That puts the fluorescent molecules in the most visible location for allowing the nanoparticles to be tracked optically through a microscope.

“These are beautiful structures, they’re so clean,” Bawendi says. That uniformity arises, in part, because the starting material, fluorescent nanoparticles that Bawendi and his group have been perfecting for years, are themselves perfectly uniform in size. “You have to use very uniform material to produce such a uniform construction,” Chen says.

Initially, at least, the particles might be used to probe basic biological functions within cells, Bawendi suggests. As the work continues, later experiments may add additional materials to the particles’ coating so that they interact in specific ways with  Industrial IoT Manufacturer  molecules or structures within the cell, either for diagnosis or treatment.

Watch how supernanoparticles are made to glow and manipulated with magnets inside a cancer cell. Video: Melanie Gonick/MIT

The ability to manipulate the particles with electromagnets is key to using them in biological research, Bawendi explains: The tiny particles could otherwise get lost in the jumble of molecules circulating within a cell. “Without a magnetic ‘handle,’ it’s like a needle in a haystack,” he says. “But with the magnetism, you can find it easily.”

A silica coating on the particles allows additional molecules to attach, causing the particles to bind with specific structures within the cell. “Silica makes it completely flexible; it’s a well developed material that can bind to almost anything,” Bawendi says.

For example, the coating could have a molecule that binds to a specific type of tumor cells; then, “You could use them to enhance the contrast of an MRI, so you could see the spatial macroscopic outlines of a tumor,” he says.

The next step for the team is to test the new nanoparticles in a variety of biological settings. “We’ve made the material,” Chen says. “Now we’ve got to use it, and we’re working with a number of groups around the world for a variety of applications.”

Christopher Murray, a professor of chemistry and materials science and engineering at the University of Pennsylvania who was not connected with this research, says, “This work exemplifies the power of using nanocrystals as building blocks for multiscale and multifunctional structures. We often use the term ‘artificial atoms’ in the community to describe how we are exploiting a new periodic table of fundamental building blocks to design materials, and this is a very elegant example.”

The study included researchers at MIT; Massachusetts General Hospital; Institut Curie in Paris; the Heinrich-Pette Institute and the Bernhard-Nocht Institute for Tropical Medicine in Hamburg, Germany; Children’s Hospital Boston; and Cornell University. The work was supported by the National Institutes of Health, the Army Research Office through MIT’s Institute for Soldier Nanotechnologies, and the Department of Energy.

Publication: Ou Chen, et al., “Magneto-fluorescent core-shell supernanoparticles,” Nature Communications 5, Article number: 5093; doi:10.1038/ncomms6093

Image: Courtesy of the researchers

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These images compare a view of Beta Pictoris in scattered light as seen by the Hubble Space Telescope (top) with a similar view constructed from data in the SMACK simulation (red overlay, bottom). The X pattern in the Hubble image forms as a result of a faint secondary dust disk inclined to the main debris disk. Previous simulations were unable to reproduce this feature, but the SMACK model replicates the overall pattern because it captures the three-dimensional distribution of the collisions responsible for making the dust.

Astrophysicists have created a new supercomputer simulation of the planet and debris disk around the Beta Pictoris. The new supercomputer model reveals that the planet’s motion drives spiral waves throughout the disk, a phenomenon that causes collisions among the orbiting debris. Patterns in the collisions and the resulting dust appear to account for many observed features that previous research has been unable to fully explain.

“We essentially created a virtual Beta Pictoris in the computer and watched it evolve over millions of years,” said Erika Nesvold, an astrophysicist at the University of Maryland, Baltimore County, who co-developed the simulation. “This is the first full 3-D model of a debris disk where we can watch the development of asymmetric features formed by planets, like warps and eccentric rings, and also track collisions among the particles at the same time.”

In 1984, Beta Pictoris became the second star known to be surrounded by a bright disk of dust and debris. Located only 63 light-years away, Beta Pictoris is an estimated 21 million years old, or less than 1 percent the age of our solar system. It offers astronomers a front-row seat to the evolution of a young planetary system and it remains one of the closest, youngest and bes Industrial IoT Products  t-studied examples today. The disk, which we see edge on, contains rock and ice fragments ranging in size from objects larger than houses to grains as small as smoke particles. It’s a younger version of the Kuiper belt at the fringes of our own planetary system.

Nesvold and her colleague Marc Kuchner, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, presented the findings Thursday during the “In the Spirit of Lyot 2015” conference in Montreal, which focuses on the direct detection of planets and disks around distant stars. A paper describing the res M2M IoT gateway  earch has been submitted to The Astrophysical Journal.

Erika Nesvold and Marc Kuchner discuss how their new supercomputer simulation helps astronomers understand Beta Pictoris. Credits: NASA’s Goddard Space Flight Center

In 2009, astronomers confirmed the existence of Beta Pictoris b, a planet with an estimated mass of about nine times Jupiter’s, in the debris disk around Beta Pictoris. Traveling along a tilted and slightly elongated 20-year orbit, the planet stays about as far away from its star as Saturn does from our sun.

Astronomers have struggled to explain various features seen in the disk, including a warp apparent at submillimeter wavelengths, an X-shaped pattern visible in scattered light, and vast clumps of carbon monoxide gas. A common ingredient in comets, carbon monoxide molecules are destroyed by ultraviolet starlight in a few hundred years. To explain why the gas is clumped, previous researchers suggested the clumps could be evidence of icy debris being corralled by a second as-yet-unseen planet, resulting in an unusually high number of collisions that produce carbon monoxide. Or perhaps the gas was the aftermath of an extraordinary crash of icy worlds as large as Mars.

“Our simulation suggests many of these features can be readily explained by a pair of colliding spiral waves excited in the disk by the motion and gravity of Beta Pictoris b,” Kuchner said. “Much like someone doing a cannonball in a swimming pool, the planet drove huge changes in the debris disk once it reached its present orbit.”

Keeping tabs on thousands of fragmenting particles over millions of years is a computationally difficult task. Existing models either weren’t stable over a sufficiently long time or contained approximations that could mask some of the structure Nesvold and Kuchner were looking for.

Working with Margaret Pan and Hanno Rein, both now at the University of Toronto, they developed a method where each particle in the simulation represents a cluster of bodies with a range of sizes and similar motions. By tracking how these “superparticles” interact, they could see how collisions among trillions of fragments produce dust and, combined with other forces in the disk, shape it into the kinds of patterns seen by telescopes. The technique, called the Superparticle-Method Algorithm for Collisions in Kuiper belts (SMACK), also greatly reduces the time required to run such a complex computation.

Using the Discover supercomputer operated by the NASA Center for Climate Simulation at Goddard, the SMACK-driven Beta Pictoris model ran for 11 days and tracked the evolution of 100,000 superparticles over the lifetime of the disk.

As the planet moves along its tilted path, it passes vertically through the disk twice each orbit. Its gravity excites a vertical spiral wave in the disk. Debris concentrates in the crests and troughs of the waves and collides most often there, whedge gatewayich explains the X-shaped pattern seen in the dust and may help explain the carbon monoxide clumps.

The planet’s orbit also is slightly eccentric, which means its distance from the star varies a little every orbit. This motion stirs up the debris and drives a second spiral wave across the face of the disk. This wave increases collisions in the inner regions of the disk, which removes larger fragments by grinding them away. In the real disk, astronomers report a similar clearing out of large debris close to the star.

“One of the nagging questions about Beta Pictoris is how the planet ended up in such an odd orbit,” Nesvold explained. “Our simulation suggests it arrived there about 10 million years ago, possibly after interacting with other planets orbiting the star that we haven’t detected yet.”

Image: NASA/ESA and D. Golimowski (Johns Hopkins Univ.); bottom, NASA Goddard/E. Nesvold and M. Kuchner

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It appears that college studeoverhead line sensornts, and the general public, have one less sexually transmitted health issue to worry about. A Bloomberg news  Distribution Power Line Monitoring System  article is reporting that pubic lice, the crab-shaped insects that have dwell in the human groin area, is on the decline. Scientists have noted that the recent trend in pubic hair removal, such as Brazilian bikini waxing, may play a major role in this decline.

Citing surveys and research by other scholars, scientists at Kenyon College in Gambier, Ohio, reported in a 2011 study that a majority of college men and women in the U.S. and Australia remove all or part of their pubic hair. Other research from the U.K. shows that 99 percent of women older than 16 years remove som Industrial IoT Manufacturer  e hair from the under arms, legs and pubic area. And Sydney Australia’s main sexual health clinic hasn’t seen a woman with pubic lice since 2008 and male cases have fallen 80 percent from about 100 a decade ago.

To read the full article, go to Bloomberg News.

Pubic Louse (Phthirus pubis). Photographer: David Scharf/Science Faction/Getty Images