#Chalmers researchers extend the lifetime of atoms using a mirror: In an experiment researchers at Chalmers University of Technology have got an artificial atom to survive ten times longer than normal by positioning the atom in front of a mirror.
The findings were recently publish If one adds energy to an atom-one says that the atom is excited--it normally takes some time before the atom loses energy and returns to its original state.
This time is called the lifetime of the atom. Researchers at Chalmers University of Technology have placed an artificial atom at a specific distance in front of a short circuit that acts as a mirror.
By changing the distance to the mirror they can get the atom to live longer,
up to ten times as long as if the mirror had not been there. The artificial atom is actually a superconducting electrical circuit that the researchers make behave as an atom.
Just like a natural atom, you can charge it with energy; excite the atom; which it then emits in the form of light particles.
In this case, the light has a much lower frequency than ordinary light and in reality is microwaves."
"We have demonstrated how we can control the lifetime of an atom in a very simple way,
"says Per Delsing, Professor of Physics and leader of the research team.""We can vary the lifetime of the atom by changing the distance between the atom and the mirror.
If we place the atom at a certain distance from the mirror the atom's lifetime is extended by such a length that we are not even able to observe the atom.
Consequently, we can hide the atom in front of a mirror, "he continues. The experiment is a collaboration between experimental and theoretical physicists at Chalmers,
the latter have developed the theory for how the atom's lifetime varies depending on the distance to the mirror."
"The reason why the atom"dies",that is it returns to its original ground state, is that it sees the very small variations in the electromagnetic field which must exist due to quantum theory,
known as vacuum fluctuations,"says Göran Johansson, Professor of Theoretical and Applied Quantum physics and leader of the theory group.
When the atom is placed in front of the mirror it interacts with its mirror image, which changes the amount of vacuum fluctuations to
which the atom is exposed. The system that the Chalmers researchers succeeded in building is suited particularly well for measuring the vacuum fluctuations
which otherwise is a very difficult thing to measure r
#Production of Injectable Nanocomposite Paste in Iran Abstract: Iranian researchers from Materials and Energy Research center (MERC) succeeded in the production of a type of biocompatible nanocomposite with the ability to carry drugs,
These starlike excitations are caused by a single magnetic atom put into the layer of superconducting material.
Physicists from France and Russia have discovered that the magnetic atoms in a two-dimensional layered superconductor create electronic disturbances that look like oscillating"nanostars".
and their colleagues from Paris-Saclay University studied the emergence of Yu-Shiba-Rusinov (YSR) states bound around single magnetic atoms embedded in a two-dimensional superconductor.
YSR states around single magnetic atoms of iron.""We have demonstrated that the use of two-dimensional superconductors instead of the three dimensional ones results in an increase in the spatial extension of YSR states for several dozen nanometres,
They suggested that magnetic atoms introduced into a superconductor must create special states of excitation around themselves-electron-hole standing waves named after their discoverers.
they are not negative ions, but rather special excitations in two-dimensional quantum systems in a magnetic field.
metabolites (glucose, lactate and bilirubin) and ions (calcium and potassium), all of which indicate changes in the condition of intensive-care patients."
a postdoctoral researcher in Zia's lab. Cueff started with an emitter made of erbium ions,
This change in reflectivity, in turn, switches how nearby erbium ions emit light. As the VO2 changes phase, the erbium emissions go from being generated mostly by magnetic dipole transitions (the rotational torque push
metabolites (glucose, lactate and bilirubin) and ions (calcium and potassium), all of which indicate changes in the condition of intensive-care patients."
These could be electrical fields when dealing with atoms and ions or magnetic fields in superconducting qubits."
Such shutter speeds enable us to directly observe the truly fundamental motions of atoms and molecules in solids, similar to stroboscopy.
Sharp images of moving atoms Electrons are odd particles: they have both wave and particle properties.
molecules and atoms. For a long time, still images were provided, but for some years now scientists are making tremendous progress in short-pulse technology.
provide us with very sharp images of moving atoms and electrons. Nevertheless, some of the fastest processes still remained blurred.
and its dynamics need a high-speed camera for atoms. In order to sharply capture motions of such particles during a reaction, one needs to work with"shutter speeds"in the range of femtoseconds
but laser light is not able to spatially resolve atoms. Scientists from the Laboratory for Attosecond Physics at LMU and MPQ have succeeded now in producing ultrashort electron pulses with a duration of only 28 femtoseconds.
Due to this short wavelength, it is possible to visualize even single atoms in diffraction experiments. If such electrons meet a molecule or atom,
they are diffracted into specific directions due to their short wavelength. This way they generate an interference pattern at the detector from
#Silk could be new'green'material for next-generation batteries Lithium-ion batteries have enabled many of today electronics, from portable gadgets to electric cars.
Chuanbao Cao and colleagues note that carbon is a key component in commercial Li-ion energy storage devices including batteries and supercapacitors.
showing diamine molecules (containing blue nitrogen atoms) attached to metal (manganese) atoms (green). Carbon dioxide molecules (grey carbon atoms with two red oxygen atoms) bind through a cooperative mechanism akin to a chain reaction along the pore surfaces.
Some H atoms (white) are omitted for clarity. Graphic by Thomas Mcdonald, Jarad Mason, Jeffrey Long/UC Berkeley) Though power plants are required not now to capture carbon dioxide from their emissions,
it will eventually be necessary in order to slow the pace of climate change caused by fossil-fuel burning.
"Long's team found that the diamines bind to the metal atoms of the MOF
charged ions burst through the holes. hen you extract and accelerate these ions, that momentum exchange propels the spacecraft in the opposite direction,
Brikner explains. Accion is on target to launch MAX-1 in July, and plans to start shipping the system to customers by the end of the year.
The team measured the emitted current of the released ions after applying certain levels of voltage.
meaning the atom-by-atom modifications that researchers need to optimize these molecules into therapeutic compounds
But quantum phenomena are only observable in the smallest of objects, such as atoms or molecules,
"Tiny objects like atoms behave according to the laws of quantum physics, "says James Millen (UCL Physics
The largest objects that have been made to behave in a quantum manner are large molecules of about 800 atoms.
We are trying to do the same with glass particles made up of billions of atoms,
when atoms stop vibrating. Widely-used technologies, such as laser cooling, that work for atoms won't work for such large objects,
and a related technique called cavity cooling must be used. During cavity cooling, a particle is suspended by a laser light field contained between two mirrors,
Using this stage inside a state-of-the-art aberration-corrected transmission electron microscope they can take nanoscale-resolution pictures of lithium ions as they are deposited on or dissolve off of an electrode while the battery runs("Observation and Quantification of Nanoscale Processes in Lithium batteries
Methodsmoving beyond the current industry-standard lithium-ion battery has been difficult. In lithium-air and other designs, interactions at the electrode-electrolyte interfaces affect the battery's performance and safety.
Now, a team of experimentalists led by the Department of energy's Oak ridge National Laboratory has demonstrated an energy-efficient desalination technology that uses a porous membrane made of strong, slim graphene--a carbon honeycomb one atom thick.
Salt ions, in contrast, are larger than water molecules and cannot cross the membrane. The porous membrane allows osmosis,
"Graphene to the rescue Graphene is only one-atom thick, yet flexible and strong. Its mechanical and chemical stabilities make it promising in membranes for separations.
The chemical vapor deposited carbon atoms that self-assembled into adjoining hexagons to form a sheet one atom thick.
The membrane allowed rapid transport of water through the membrane and rejected nearly 100 percent of the salt ions, e g.,
, positively charged sodium atoms and negatively charged chloride atoms. To figure out the best pore size for desalination,
allowed for atom-resolution imaging of graphene, which the scientists used to correlate the porosity of the graphene membrane with transport properties.
including irradiation with electrons and ions, but none of them worked. So far, the oxygen plasma approach worked the best,
The results have now been published in Physical Review Letters("Direct Photonic Coupling of a Semiconductor Quantum dot and a Trapped Ion".
In contrast, charged atoms, called ions, have an excellent memory: They can store quantum information for many minutes.
therefore both of these components, qdots and ions, to work together as a team. Experts speak of a hybrid system,
"We used the photon to excite an ion, "explains Prof. Dr. Michael Khl from the Institute of Physics at the University of Bonn."
"Conscientious ions To do so, the researchers connected a thin glass fiber to the qdot. They transported the photon via the fiber to the ion many meters away.
The fiberoptic networks used in telecommunications operate very similarly. To make the transfer of information as efficient as possible,
they had trapped the ion between two mirrors. The mirrors bounced the photon back and forth like a ping pong ball,
until it was absorbed by the ion.""By shooting it with a laser beam, we were able to read out the ion that was excited in this way,
"explains Prof. Khl.""In the process, we were able to measure the direction of polarization of the previously absorbed photon".
"In a sense then, the state of the qdot can be preserved in the ion theoretically this can be done for many minutes.
when a nitrogen atom substitutes for a carbon atom and is adjacent to a vacancy, or missing carbon atom, in the lattice.
In polycrystalline samples, atoms are arranged not in a regular repeating lattice over long distances, thus electrons travel dont travel very far--roughly 10 nanometers or less--before scattering off an obstacle.
and charged atoms (ions) play a key role in the temperature sensitivity of both living plant cells and the dry cyberwood.
and the ions can move about more freely, "explains Di Giacomo. As a result, the material conducts electricity better when temperature increases.
In ongoing work, they are now further developing it such that it functions without plant cells, essentially with only pectin and ions.
Phonons typically move in straight lines in nanowires threads barely a few atoms wide. Previous calculations suggested that if parts of a nanowire contained random arrangements of two different types of atoms,
phonons would be stopped in their tracks. In actual alloy nanowires though, atoms of the same element might cluster together to form short sections composed of the same elements.
Now, Zhun-Yong Ong and Gang Zhang of the A*STAR Institute Of high Performance Computing in Singapore have calculated the effects of such short-range order on the behavior of phonons("Enhancement and reduction of one-dimensional
"Their results suggest that heat conduction in a nanowire does not just depend on the relative concentrations of the alloy atoms and the difference in their masses;
it also depends on how the atoms are distributed. Their model simulated an 88-micrometer-long nanowire containing 160,000 atoms of two different elements.
They found that when the nanowire was ordered more containing clusters of the same elements low-frequency phonons struggled to Move in contrast,
The researchers used their model to study the thermal resistance of a nanowire containing an equal mix of silicon and germanium atoms.
Short-range ordering of the atoms allowed high-frequency phonons to travel freely through the wire giving it a relatively low thermal resistance.
In contrast, a random distribution of alloy atoms resulted in a higher resistance over triple that of the ordered case for a 2. 5-micrometer-long wire.
"This novel material significantly enhanced catalytic activity for the oxygen reduction reaction--the splitting of an O2 molecule into two oxygen ions--that is critical to fuel cells and potentially other electrochemical applications.
"This is an electron wave in a phosphorus atom, distorted by a local electric field. Unlike conventional computers that store data on transistors and hard drives, quantum computers encode data in the quantum states of microscopic objects called qubits.
& Communication Technology, was first in the world to demonstrate single-atom spin qubits in silicon,
like the spin of a single phosphorus atom in isotopically enriched silicon, can be controlled using electric fields,
Associate professor Morello said the method works by distorting the shape of the electron cloud attached to the atom,
Here, the'knob'is applied the voltage to a small electrode placed above the atom.""The findings suggest that it would be possible to locally control individual qubits with electric fields in a large-scale quantum computer using only inexpensive voltage generators, rather than the expensive high-frequency microwave sources.
containing only the silicon-28 isotope.""This isotope is perfectly nonmagnetic and, unlike those in naturally occurring silicon,
does not disturb the quantum bit, "Associate professor Morello said. The purified silicon was provided through collaboration with Professor Kohei Itoh from Keio University in Japan n
which contain a central metal atom bound to several nitrogen-containing rings. Hemoglobin, which carries oxygen in the blood,
is a metalloporphyrin with iron as the central atom. For this sensor, the researchers used a metalloporphyrin with cobalt at its center.
#Quick, easy and early diagnosis with rare earth ions Lack of oxygen in cells is an indicator of diseases as serious as cerebral haemorrhages, stroke and cancer.
The scientists coat gold nanoparticles of a few thousand atoms each with an oil-like organic molecule that holds the gold particles together.
or about six atoms thick, is so tiny it would not normally be measurable. Subramanian Sankaranarayanan and Sanket Deshmukh at CNM used the high-performance computing resources at DOES National Energy Research Scientific Computing Center and the Argonne Leadership Computing Facility (ALCF), both
With their aligned atoms, the graphene-nanotube digital switches could avoid the issues of electron scattering. ou want to control the direction of the electrons,
Its molecular structure is an atomic sandwich made up of one molybdenum atom for every two tellurium atoms HY1.
These atoms form a thin, molecular sandwich with the one metal and two chalcogenides, and depending on their fabrication method can exist in several slightly different shaped atomic arrangements.
As the chips approach single or several atom thickness, (commonly referred to as 2-dimensional),
which was several atoms thick. They directed a 1 m wide laser (a human hair is 17 to 181 m) at the 2h-Mote2
It consists of small clusters of four copper atoms each, supported on a thin film of aluminum oxide.
which limits how many atoms can catch and hold carbon dioxide.""With our catalyst, there is no inside,
"All four copper atoms are participating because with only a few of them in the cluster,
Control voltages that shift oxygen ions and vacancies switch the bits between ones and zeroes.
the researchers found the tantalum oxide gradually loses oxygen ions, changing from an oxygen-rich, nanoporous semiconductor at the top to oxygen-poor at the bottom.
These are"holes"in atomic arrays where oxygen ions should exist, but don't. The voltage-controlled movement of oxygen vacancies shifts the boundary from the tantalum/tantalum oxide interface to the tantalum oxide/graphene interface."
Third, the flow of current draws oxygen ions from the tantalum oxide nanopores and stabilizes them.
These negatively charged ions produce an electric field that effectively serves as a diode to hinder error-causing crosstalk.
A defect-free layer is also impermeable to all atoms and molecules. This amalgamation makes it a terrifically attractive material to apply to scientific developments in a wide variety of fields, such as electronics, aerospace and sports.
Each new combination of atom-thick layers presents new properties and researchers suspect that one, or more, of these new materials will exhibit energy storage
the researchers selectively extract layers of aluminum atoms from a block of MAX phase by etching them out with an acid."
where the titanium atoms are in center and the molybdenum on the outside. The next Frontier Now, with the help of theoretical calculations done by researchers at the FIRST ENERGY Frontier Research center at the Oak ridge National Laboratory,
replacing up to 25 percent of the lanthanum ions in the host material with strontium ions, offers considerable promise.
"Carbon nanotubes are rolled-up arrays of perfect hexagons of atoms; graphene is a rolled out sheet of the same.
the way the atoms are arranged can influence all those properties. ome labs are actively trying to make these materials or measure properties like the strength of single nanotubes and graphene sheets,
or lose atoms to neighboring rings, depending on how they join with their neighbors. By forcing five, seven or even eight-atom rings
they found they could gain a measure of control over the hybrid mechanical properties. Turning the nanotubes in a way that forced wrinkles in the graphene sheets added further flexibility and shear compliance,
with their atoms arranged in a highly organised and regular manner. Metallic glass alloys, however, have disordered a highly structure,
with the atoms arranged in a non-regular way.""There are many types of metallic glass, with the most popular ones based on zirconium, palladium, magnesium, titanium or copper.
Current transistors consist of only a handful of atoms. It is a major challenge to produce chips in
#Physicists determine the three-dimensional positions of individual atoms for the first time Atoms are the building blocks of all matter On earth,
Now, scientists at UCLA have used a powerful microscope to image the three-dimensional positions of individual atoms to a precision of 19 trillionths of a meter,
to infer the macroscopic properties of materials based on their structural arrangements of atoms, which will guide how scientists and engineers build aircraft components, for example.
a UCLA professor of physics and astronomy and a member of UCLA California Nanosystems Institute, is published Sept. 21 in the online edition of the journal Nature Materials("Three-dimensional coordinates of individual atoms
"For more than 100 years, researchers have inferred how atoms are arranged in three-dimensional space using a technique called X-ray crystallography,
However, X-ray crystallography only yields information about the average positions of many billions of atoms in the crystal,
Because X-ray crystallography doesn reveal the structure of a material on a per-atom basis
the technique can identify tiny imperfections in materials such as the absence of a single atom.
and measures how many electrons interact with the atoms at each scan position. The method reveals the atomic structure of materials
because different arrangements of atoms cause electrons to interact in different ways. However scanning transmission electron microscopes only produce two-dimensional images.
the researchers were able to slowly assemble a 3-D model of 3, 769 atoms in the tip of the tungsten sample.
Miao and his team showed that the atoms in the tip of the tungsten sample were arranged in nine layers, the sixth
The researchers believe the defect was either a hole in an otherwise filled layer of atoms
or one or more interloping atoms of a lighter element such as carbon. Regardless of the nature of the point defect, the researchersability to detect its presence is significant,
demonstrating for the first time that the coordinates of individual atoms and point defects can be recorded in three dimensions. e made a big breakthrough,
Miao and his team plan to build on their results by studying how atoms are arranged in materials that possess magnetism or energy storage functions,
Phase change materials that change their optical properties depending on the arrangement of the atoms allow for the storage of several bits in a single cell.
novel materials that change their optical properties depending on the arrangement of the atoms: Within shortest periods of time, they can change between crystalline (regular) and amorphous (irregular) states.
i e. depending on the arrangement of the atoms in the material. This changeability between crystalline (regular) and amorphous (irregular) states allowed the team to store many bits in a single integrated nanoscale optical phase-change cell l
when atoms are brought too close together-to detect a wide array of protein markers that are linked to various diseases.
From spontaneous emission of light by excited atoms e g. in a fluorescent tube to influences on the structure of the universe during the Big Bang:
or ion channels, each of which is a portal for specific ions. Ion channels are typically about 1 nanometer wide;
by maintaining the right balance of ions, they keep cells healthy and stable. Now researchers at MIT have created tiny pores in single sheets of graphene that have an array of preferences and characteristics similar to those of ion channels in living cells.
which scientists have studied ever ion flow. Each is also uniquely selective, preferring to transport certain ions over others through the graphene layer. hat we see is that there is a lot of diversity in the transport properties of these pores,
which means there is a lot of potential to tailor these pores to different applications or selectivities, says Rohit Karnik, an associate professor of mechanical engineering at MIT.
detecting ions of mercury, potassium, or fluoride in solution. Such ion-selective membranes may also be useful in mining:
In the future, it may be possible to make graphene nanopores capable of sifting out trace amounts of gold ions from other metal ions, like silver and aluminum.
Karnik and former graduate student Tarun Jain, along with Benjamin Rasera, Ricardo Guerrero, Michael Boutilier, and Sean Oern from MIT and Juan-carlos Idrobo from Oak ridge National Laboratory, publish their results today in the journal Nature Nanotechnology("Heterogeneous sub-continuum ionic transport in statistically isolated graphene nanopores").
which are slightly smaller than the ions that flow through them. hen nanopores get smaller than the hydrated size of the ion,
In particular, hydrated ions, or ions in solution, are surrounded by a shell of water molecules that stick to the ion,
depending on its electrical charge. Whether a hydrated ion can squeeze through a given ion channel depends on that channel size and configuration at the atomic scale.
Karnik reasoned that graphene would be a suitable material in which to create artificial ion channels:
A sheet of graphene is an ultrathin lattice of carbon atoms that is one atom thick, so pores in graphene are defined at the atomic scale.
The researchers then isolated individual pores by placing each graphene sheet over a layer of silicon nitride that had been punctured by an ion beam
The group reasoned that any ions flowing through the two-layer setup would have passed likely first through a single graphene pore,
The group measured flows of five different salt ions through several graphene sheet setups by applying a voltage and measuring the current flowing through the pores.
and from ion to ion, with some pores remaining stable, while others swung back and forth in conductance an indication that the pores were diverse in their preferences for allowing certain ions through. he picture that emerges is that each pore is different
and that the pores are dynamic, Karnik says. ach pore starts developing its own personality.
which given the single-atom thickness of graphene makes them among the smallest pores through
which scientists have studied ion flow. With the model, the group calculated the effect of various factors on pore behavior,
Knowing this, researchers may one day be able to tailor pores at the nanoscale to create ion-specific membranes for applications such as environmental sensing and trace metal mining. t kind of a new frontier in membrane technologies,
it is only through a fundamental understanding of ion transport that the overall anticipated behaviors of bulk graphene membranes can be drawn.
it is due to the canting between the atomic magnets from one atom to the next (see figure.
by showing that potassium can work with graphite in a potassium-ion battery-a discovery that could pose a challenge and sustainable alternative to the widely-used lithium-ion battery.
Lithium-ion batteries are ubiquitous in devices all over the world, ranging from cell phones to laptop computers and electric cars.
A potassium-ion battery has been shown to be possible. And the last time this possibility was explored was
"The Journal of the American Chemical Society published the findings from this discovery("Carbon Electrodes for K-Ion Batteries),
as the charge carrier whose ions migrate into the graphite and create an electrical current.
Right now, batteries based on this approach don't have performance that equals those of lithium-ion batteries,
"It's safe to say that the energy density of a potassium-ion battery may never exceed that of lithium-ion batteries,
the scientists set out to learn its atom-resolution structure. This involved feedback between experiment and theory.
when it comes to water and ions. These insights are intriguing on their own, but when the scientists examined the structure of the nanosheetsbackbone,
Overtext Web Module V3.0 Alpha
Copyright Semantic-Knowledge, 1994-2011