Graphene has become an all-purpose wonder mate- rial, spurring armies of researchers to explore new possibilities for this two-dimensional lattice of pure carbon. But new research at MIT has found addi- tional potential for the material by uncovering unex- pected features that show up under some extreme conditions—features that could render graphene suitable for exotic uses such as quantum computing.
The research is published this week in the jour- nal Nature, in a paper by professors Pablo Jarillo- Herrero and Ray Ashoori, postdocs Andrea Young and Ben Hunt, graduate student Javier Sanchez- Yamaguchi, and three others. Under an extremely powerful magnetic field and at extremely low tem- perature, the researchers found, graphene can effec- tively filter electrons according to the direction of their spin, something that cannot be done by any conventional electronic system.
Under typical conditions, sheets of graphene behave as normal conductors: Apply a voltage, and current flows throughout the two-dimensional flake. If you turn on a magnetic field perpendicular to the gra- phene flake, however, the behavior changes: Cur- rent flows only along the edge, while the bulk re- mains insulating. Moreover, this current flows only in one direction—clockwise or counterclockwise, depending on the orientation of the magnetic field—in a phenomenon known as the quantum
Graphene can host exotic new quantum electronic states at its edges
Ben Harris, a telecommunications and GPS satellite expert with the University of Texas has made a surprising announcement during his presentation at this year's gath- ering for the American Geophysi- cal Union. He reported that using GPS data to calculate the mass of the Earth, gives a slightly bigger number than is accepted by the International Astronomical Union.
The difference, he suggests, may be due to a disc of dark matter
that exists over the equator.
Dark matter is of course the mysterious stuff that physicists have come to believe exists all throughout the universe. We can't see it, but researchers have managed to sense its presence in a variety of ways (such as meas- uring its gravitational impact on stars, other planets, etc.). In so doing, most in the field have come to believe that it makes up approximately 80 percent of all
matter. Unfortunately (mainly be- cause it doesn't appear to absorb or emit light or electromagnetic radia- tion) none of the studies done so far have been able to prove that dark matter truly exists—thus, the search goes on for some new kind of method to prove that dark matter isn't just a theory, or alterna- tively, for some other explanation of what has been observed.
Among other studies, back in 2009, it was noted ...Read more...
Telecommunications expert suggests Earth may have dark matter disc
Department of Physics—United Arab Emirates University
Jan. 04, 2014 Volume 4, Issue 1Credit: NASA
Hall effect.
In the new work, the researchers found that if they applied a second powerful magnetic field—this time in the same plane as the graphene flake—the materi- al's behavior changes yet again: Electrons can move around the conducting edge in ...Read more….
On a piece of graphene (the horizontal surface with a hexagonal pattern of carbon atoms), in a strong magnetic field, electrons can move only along the edges, and are blocked from moving in the interior. In addi- tion, only electrons with one direction of spin can move in only one direction along the edges (indicated by the blue arrows), while electrons with the opposite spin are blocked (as shown by the red arrows). Credit:
MIT
Weekly news from around the world compiled by Dr. Ilias Fernini
Astronomy and Physics News
Graphene can host exotic new quantum electronic states at its
edges 1
Telecommunications expert sug- gests Earth may have dark matter 1 Vapor nanobubbles rapidly detect malaria through the skin 2
NASA's Hubble Sees Cloudy Super-Worlds With Chance for More Clouds
2
Ensuring accuracy of weights and
measurements 2
X-ray laser at SLAC maps important drug target 3
First Asteroid Discovered in 2014 Has Little Impact 3 Researchers find simple, cheap way to increase solar cell efficiency 3 Lovejoy in the New Year 4 New Studies Give Strong Boost to Binary-Star Formation Theory 4 Inside this issue:
Rice Univ. researchers have developed a non- invasive technology that accurately detects low levels of malaria infection through the skin in seconds with a laser scanner. The
“vapor nanobubble” technology requires no dyes or diagnostic chemicals, and there is no need to draw blood.
A preclinical study published in
the Proceedings of the National Academy of Sciences shows that Rice’s technology detect- ed even a single malaria-infected cell among a million normal cells with zero false-positive readings.
The new diagnostic technology uses a low- powered laser that creates tiny vapor
“nanobubbles” inside malaria-infected cells.
The bursting bubbles have a unique acoustic
signature that allows for an extremely sensitive diagnosis.
“Ours is the first through-the-skin meth- od that’s been shown to rapidly and accurately detect malaria in seconds without the use of blood sampling or reagents,” said lead investigator Dmitri Lapotko, a Rice scientist who invented the vapor nanobubble technology. The diagnosis and screening will be support- ed by a low-cost, battery-powered porta- ble device that can be operated by nonmedical personnel. One device should be able to screen up to 200,000 people per year, with the cost of diagnosis estimated to be below 50 cents, he said. Read more...
by weights and measures officials when testing measuring instru- ments.
Training and evaluating those personnel is the year-round re- sponsibility of PML's Office of Weights and Measures (OWM), and nationwide the demonstrated abilities of lab staff are trending upward. OWM has just compiled its summary training and profi- ciency-test data for 2013, which show the highest overall success rate on proficiency testing since Americans rely on many measure-
ments of mass and volume in their daily lives, from weighing broccoli at the grocery store to putting gas in the family car. In order to ensure both consumer confidence and uniformity in commerce, the accuracy of the devices used in those measurements must be tested at regular intervals.
The degree of accuracy achieved, in turn, ultimately depends on the com- petence of the metrologists who calibrate over 350,000 measurement standards per year that are then used
the program began collecting data in 2006: 98.97 % now, versus 92.76 % seven years ago.
That improvement is directly tied to OWM's recent efforts. "All persons who work in a standards lab must be able to demonstrate proficiency in order for their labs to be recognized by NIST," says Georgia Harris of OWM's Laboratory Metrology Pro- gram. "Each of the 45 or 46 active labs is recognized with a certificate of measurement traceability to sup- port their state legal requirements;
they may also be … Read more...
Vapor nanobubbles rapidly detect malaria through the skin
P a g e 2 V o lu m e 4 , I s s u e 1
Ensuring accuracy of weights and measurements
NASA's Hubble Sees Cloudy Super-Worlds With Chance for More Clouds
Scientists using NASA's Hubble Space Tele- scope have characterized the atmospheres of two of the most common type of planets in the Milky Way galaxy and found both may be blanketed with clouds.
The planets are GJ 436b, located 36 light- years from Earth in the constellation Leo, and GJ 1214b, 40 light-years away in the constellation Ophiuchus. Despite numerous efforts, the nature of the atmospheres sur- rounding these planets had eluded definitive characterization until now.
The researchers described their work as an important milestone on the road to character- izing potentially habitable, Earth-like worlds beyond the solar system. Their findings ap-
Val Miller demonstrates a volume gauge.
This graphic shows how a laser pulse creates a vapor nanobubble in a malaria-infected cell and is used to noninvasively diagnose malaria rapidly and with high sensitivity. Image: E. Lukianova-Hleb/Rice Univ.
pear in separate papers in the Jan. 2 issue of the journal Nature.
The two planets fall in the middle range in mass, between smaller, rockier planets such as Earth and larger gas giants such as Jupiter.
GJ 436b is categorized as a "warm Neptune"
because it is much closer to its star than frigid Neptune is to the sun.
GJ 1214b is known as a "super-Earth" be- cause of its size. Both GJ 436b and GJ 1214b can be observed transiting, or passing in front of, their parent stars. This provides an oppor- tunity to study these planets in more detail as starlight filters through their atmospheres.
Read more….
Illustration only.
X-ray laser at SLAC maps important drug target
Researchers have used one of the brightest X-ray sources on the planet to map the 3-D structure of an important cellular gatekeeper known as a G protein-coupled receptor, or GPCR, in a more natural state than possible before.
The new technique is a major advance in exploring GPCRs, a vast, hard-to-study family of pro- teins that plays a key role in hu- man health and is targeted by an estimated 40 percent of modern medicines.
The research, performed at the Linac Coherent Light Source (LCLS) X-ray laser at the Depart- ment of Energy's (DOE's) SLAC National Accelerator Laboratory,
is also a leap forward for structural biology experiments at LCLS, which has opened up many new avenues for exploring the molecu- lar world since its launch in 2009.
"For the first time we have a room -temperature, high-resolution structure of one of the most diffi- cult to study but medically im- portant families of membrane proteins," said Vadim Cherezov, a pioneer in GPCR research at The Scripps Research Institute who led the experiment. "And we have validated this new method so that it can be confidently used for solving new structures."
In the experiment, published in the Dec. 20 issue of Science, re- searchers examined the human serotonin receptor, which plays a role in learning, mood and sleep and is the target of drugs that combat obesity, depression and migraines. The scientists prepared crystallized samples of the recep- tor in a fatty gel that mimics its environment in the cell. With a newly designed injection system, they streamed the gel into the path of the LCLS X-ray pulses, which hit the crystals and pro- duced patterns used to recon- struct ...Read more...
hit the Earth's atmosphere last night sometime between 2 pm Wednesday and 9 am Thursday EST.
Using the only available observations, three inde- pendent projections of the possible orbit by the independent orbit analyst Bill Gray, the Minor Planet Center in Cambridge, MA, and Steve Chesley at the NASA NEO Program Office at the Jet Propulsion Laboratory are in agreement that it would hit Earths atmosphere.
According to Chesley, because of the orbit uncer- tainty the potential impact locations are widely distributed, falling along an arc ...Read more….
Early Wednesday morning January 1st, while New Year's 2014 celebrations were still underway in the United States, the Catalina Sky Survey near Tucson, AZ, collected a single track of observations with an immedi- ate follow-up on what was possibly a very small asteroid 2-3 meters in size on a poten- tial impact trajectory with the Earth.
Designated 2014 AA, which would make it the first asteroid discovery of 2014, the track of observations on the object allowed only an uncertain orbit to be calculated.
However if this was a very small asteroid on an Earth impacting trajectory, it most likely
energy source, excitons must be able to travel quickly to the inter- face of the donor and acceptor domains and retain as much of the light's energy as possible.
One way to increase solar cell efficiency is to adjust the differ- ence between the highest occupied molecular orbit (HOMO) of the acceptor and lowest unoccupied molecular orbit (LUMO) levels of the polymer so that the exciton can be harvested with minimal loss. One of the most common ways to accomplish this is by add- ing a fluorine atom to the Researchers from North Carolina
State University and the Chinese Academy of Sciences have found an easy way to modify the molecu- lar structure of a polymer com- monly used in solar cells. Their modification can increase solar cell efficiency by more than 30 per- cent.
Polymer-based solar cells have two domains, consisting of an electron acceptor and an electron donor material. Excitons are the energy particles created by solar cells when light is absorbed. In order to be harnessed effectively as an
polymer's molecular backbone, a difficult, multi-step process that can increase the solar cell's perfor- mance, but has considerable material fabrication costs.
A team of chemists led by Jianhui Hou from the Chinese Academy of Sciences created a polymer known as PBT-OP from two commercially availa- ble monomers and one easily synthesized monomer. Wei Ma, a post-doctoral physics researcher from NC State and cor- responding author on a paper de- scribing the ….Read more...
P a g e 3 V o lu m e 4 , I s s u e 1
First Asteroid Discovered in 2014 Has Little Impact
File image.
Researchers find simple, cheap way to increase solar cell efficiency
This illustration shows a man suffering from a migraine, overlain with a rendering of the human serotonin receptor bound to ergotamine, an anti-migraine drug. Also shown is a render- ing of a neuron network. Scientists used SLAC's Linac Coherent Light Source X-ray laser to explore crystallized samples of the serotonin receptor,….
College of Science - United Arab Emirates University POB 15551
Al-Ain
United Arab Emirates
http://fos.uaeu.ac.ae/department/physics
along with jet-like outflows rapidly propelling material in narrow beams perpendicular to the disk.
When Tobin and an international team of astronomers studied gas-enshrouded young stars roughly 1,000 light-years from Earth, they found that two had previously-unseen com- panions in the plane where their disks would be expected, perpendicular to the direction of the outflows from the systems.
One of the systems also clearly had a disk sur- rounding both young stars.
"This fits the theoretical model of companions forming from fragmentation in the disk," Tobin said. "This configuration would not be required by alternative explanations," he added.
The new observations add to a growing body of evidence supporting the disk-fragmentation idea. In 2006, a different VLA observing team found an orbiting pair of young stars, each of which was surrounded by a disk of material.
The two disks, they found, were aligned with each other in the same plane. Last year, Tobin and his colleagues found a large circumstellar disk forming around a protostar in the initial Using the new capabilities of the upgraded
Karl G. Jansky Very Large Array (VLA), scientists have discovered previously-unseen binary companions to a pair of very young protostars. The discovery gives strong sup- port for one of the competing explanations for how double-star systems form.
Astronomers know that about half of all Sun-like stars are members of double or multiple-star systems, but have debated over how such systems are formed.
"The only way to resolve the debate is to observe very young stellar systems and catch them in the act of formation," said John Tobin, of the National Radio Astrono- my Observatory (NRAO). "That's what we've done with the stars we observed, and we got valuable new clues from them," he added.
Their new clues support the idea that dou- ble-star systems form when a disk of gas and dust whirling around one young star fragments, forming another new star in orbit with the first.
Young stars that still are gathering matter from their surroundings form such disks,
phases of star formation.
This showed that disks are present early in the star formation process, a necessity for binary pairs to form through disk fragmentation.
Read more….
New Studies Give Strong Boost to Binary-Star Formation
Phone: 00-971-3-7136336 Fax: 00-971-3-767-1291 E-mail: [email protected]
Physics Department
Lovejoy in the New Year Image Credit & Copyright: Damian Peach
Explanation: A rival to vanquished Comet ISON in 2013, Comet Lovejoy (C/2013 R1) still sweeps through early morning skies, captured in this starry scene on New Year's day. The frame stretches some 3.5 degrees (about 7 full moons) across a background of faint stars in the constellation Hercules. Only just visible to the naked eye from dark sites before dawn, Lovejoy remains a good target for the northern hemisphere's binocular equipped skygazers. But this
deep exposure shows off Lovejoy's beautiful tails and tantalizing greenish coma better than binocular views. Not a sungrazer, this Comet Lovejoy made its clos-
est approach to the Sun around December 22, looping high above the ecliptic plane. Now headed for the outer Solar System, Lovejoy began the new year
about 6.7 light-minutes from planet Earth.
Binary star formation through disk fragmentation starts (left) with a young star surrounded by a rotating disk of gas and dust. The disk fragments under its own gravity, with a second star forming within the disk (center), surrounded by its own disk. At right, the two stars form an orbiting pair. 100 Astronomical Units (AU) is roughly the diameter of our Solar System. CREDIT: Bill Saxton, NRAO/AUI/NSF. Technical data
