#Nano-policing pollution Pollutants emitted by factories and car exhausts affect humans who breathe in these harmful gases
and also aggravate climate change up in the atmosphere. Being able to detect such emissions is needed a critically measure.
New research by the Nanoparticles By design Unit at the Okinawa Institute of Science and Technology Graduate University (OIST), in collaboration with the Materials Center Leoben Austria and the Austrian Centre for Electron microscopy and Nanoanalysis has developed an efficient
way to improve methods for detecting polluting emissions using a sensor at the nanoscale. The paper was published in Nanotechnology.
The researchers used a copper oxide nanowire decorated with palladium nanoparticles to detect carbon monoxide a common industrial pollutant.
The sensor was tested in conditions similar to ambient air since future devices developed from this method will need to operate in these conditions.
Copper oxide is a semiconductor and scientists use nanowires fabricated from it to search for potential application in the microelectronics industry.
But in gas sensing applications, copper oxide was much less widely investigated compared to other metal oxide materials.
A semiconductor can be made to experience dramatic changes in its electrical properties when a small amount of foreign atoms are made to attach to its surface at high temperatures.
In this case the copper oxide nanowire was made part of an electric circuit. The researchers detected carbon monoxide indirectly, by measuring the change in the resulting circuit electrical resistance in presence of the gas.
They found that copper oxide nanowires decorated with palladium nanoparticles show a significantly greater increase in electrical resistance in the presence of carbon monoxide than the same type of nanowires without the nanoparticles.
The OIST Nanoparticles By design Unit used a sophisticated technique that allowed them to first sift nanoparticles according to size,
then deliver and deposit the palladium nanoparticles onto the surface of the nanowires in an evenly distributed manner.
This even dispersion of size selected nanoparticles and the resulting nanoparticles-nanowire interactions are crucial to get an enhanced electrical response.
The OIST nanoparticle deposition system can be tailored to deposit multiple types of nanoparticles at the same time, segregated on distinct areas of the wafer where the nanowire sits.
In other words, this system can be engineered to be able to detect multiple kinds of gases. The next step is to detect different gases at the same time by using multiple sensor devices,
with each device utilizing a different type of nanoparticle. Compared to other options being explored in gas sensing
which are bulky and difficult to miniaturize, nanowire gas sensors will be cheaper and potentially easier to mass produce.
The main energy cost in operating this kind of a sensor will be the high temperatures necessary to facilitate the chemical reactions for ensuring certain electrical response.
In this study 350 degree centigrade was used. However, different nanowire-nanoparticle material configurations are currently being investigated in order to lower the operating temperature of this system."
"I think nanoparticle-decorated nanowires have a huge potential for practical applications as it is possible to incorporate this type of technology into industrial devices,
said Stephan Steinhauer, a Japan Society for the Promotion of Science (JSPS) postdoctoral research fellow working under the supervision of Prof.
Mukhles Sowwan at the OIST Nanoparticles By design Unit. Image: Palladium nanoparticles were deposited on the entire wafer in an evenly distributed fashion,
as seen in the background. They also attached on the surface of the copper oxide wire in the same evenly distributed manner,
as seen in the foreground. On the upper right is a top view of a single palladium nanoparticle photographed with a transmission electron microscope (TEM)
which can only produce black and white images. The nanoparticle is made up of columns consisting of palladium atoms stacked on top of each other.
This image has been modified from the original to provide a better visualization. Source: http://www. oist. jp/news-center/..
#Nano-policing pollution Pollutants emitted by factories and car exhausts affect humans who breathe in these harmful gases
and also aggravate climate change up in the atmosphere. Being able to detect such emissions is needed a critically measure.
New research by the Nanoparticles By design Unit at the Okinawa Institute of Science and Technology Graduate University (OIST), in collaboration with the Materials Center Leoben Austria and the Austrian Centre for Electron microscopy and Nanoanalysis has developed an efficient
way to improve methods for detecting polluting emissions using a sensor at the nanoscale. The paper was published in Nanotechnology.
The researchers used a copper oxide nanowire decorated with palladium nanoparticles to detect carbon monoxide a common industrial pollutant.
The sensor was tested in conditions similar to ambient air since future devices developed from this method will need to operate in these conditions.
Copper oxide is a semiconductor and scientists use nanowires fabricated from it to search for potential application in the microelectronics industry.
But in gas sensing applications, copper oxide was much less widely investigated compared to other metal oxide materials.
A semiconductor can be made to experience dramatic changes in its electrical properties when a small amount of foreign atoms are made to attach to its surface at high temperatures.
In this case the copper oxide nanowire was made part of an electric circuit. The researchers detected carbon monoxide indirectly, by measuring the change in the resulting circuit electrical resistance in presence of the gas.
They found that copper oxide nanowires decorated with palladium nanoparticles show a significantly greater increase in electrical resistance in the presence of carbon monoxide than the same type of nanowires without the nanoparticles.
The OIST Nanoparticles By design Unit used a sophisticated technique that allowed them to first sift nanoparticles according to size,
then deliver and deposit the palladium nanoparticles onto the surface of the nanowires in an evenly distributed manner.
This even dispersion of size selected nanoparticles and the resulting nanoparticles-nanowire interactions are crucial to get an enhanced electrical response.
The OIST nanoparticle deposition system can be tailored to deposit multiple types of nanoparticles at the same time, segregated on distinct areas of the wafer where the nanowire sits.
In other words, this system can be engineered to be able to detect multiple kinds of gases. The next step is to detect different gases at the same time by using multiple sensor devices,
with each device utilizing a different type of nanoparticle. Compared to other options being explored in gas sensing
which are bulky and difficult to miniaturize, nanowire gas sensors will be cheaper and potentially easier to mass produce.
The main energy cost in operating this kind of a sensor will be the high temperatures necessary to facilitate the chemical reactions for ensuring certain electrical response.
In this study 350 degree centigrade was used. However, different nanowire-nanoparticle material configurations are currently being investigated in order to lower the operating temperature of this system."
"I think nanoparticle-decorated nanowires have a huge potential for practical applications as it is possible to incorporate this type of technology into industrial devices,
said Stephan Steinhauer, a Japan Society for the Promotion of Science (JSPS) postdoctoral research fellow working under the supervision of Prof.
Mukhles Sowwan at the OIST Nanoparticles By design Unit n
#Flicking the switch on spin-driven devices Compressing magnetically and electrically active crystals in one direction unlocks exotic spintronic switching activityby breaking the symmetry of ultiferroiccrystals using a special compression cell,
a team of RIKEN scientists has discovered a simple way to activate the material spin-based polarization.
The finding demonstrates that the stress of crystal deformation can impart a newfound degree of control over magnetic and electrical behavior in spintronic devices and sensors.
Multiferroic materials simultaneously show strong magnetic order, or ferromagnetism, and permanent electric polarization, or ferroelectricity.
Recently, researchers have taken an interest in spin-driven ferroelectricity where polarization effects are initiated at ultralow temperatures by changing the crystal internal symmetry.
This effect, which is achieved usually by applying magnetic fields to a sample, has potent light-controlling
and information-processing applications. Taro Nakajima and colleagues from the RIKEN Center for Emergent Matter Science realized that multiferroic symmetry could also be controlled through a more primitive route.
By applying pressure to the crystal in a direction that corresponds to a specific crystallographic axis,
electron spins can be aligned to generate ferroelectric polarization. Most pressure cells, however, apply stress in all directions equally. he biggest challenge we faced was accurately controlling uniaxial stress at temperatures as low as 3 kelvin,
says Nakajima. The team constructed a unique cell that clamps a multiferroic barium cobalt germanium oxide (Ba2coge2o7) crystal between a pair of zirconium oxide pistons (Fig. 1). They then investigated how the sample electric polarization changed under uniaxial stress.
In typical spin-driven ferroelectric experiments, the magnetic field causes polarization to rise to a single value when the temperature approaches absolute zero.
In contrast, by deforming the Ba2coge2o7 crystal with varying levels of uniaxial stress, the researchers could tune the polarization output in unprecedented ways, from fully on to fully off,
and many stages in between. hese findings are exciting because they show we can control the spin-driven ferroelectricity in this compound by applying uniaxial stress at the low megapascal level,
notes Nakajima. his is compared extremely weak to the gigapascal hydrostatic pressures normally used in condensed-matter physics,
which are needed to control the superconducting transition temperature in materials such as cuprates. ith this direct and effective method of tweaking multiferroic structures,
the researchers anticipate that a variety of spin-driven ferroelectric behaviors will emerge in the future, particularly for crystals with high levels of symmetry. any multiferroic materials have the potential to show stress-induced effects,
and have their ferroelectricity and ferromagnetism switched on or off easily, says Nakajima. his will have a large impact in our field. ource:
http://www. riken. jp/en/research/..
#Nanotechnology developed to help treat heart attack and stroke Australian researchers funded by the National Heart Foundation are a step closer to a safer
and more effective way to treat heart attack and stroke via nanotechnology. The research jointly lead by Professor Christoph Hagemeyer, Head of the Vascular Biotechnology Laboratory at Baker IDI Heart and Diabetes Institute and Professor Frank Caruso,
an ARC Australian Laureate Fellow in the Department of Chemical and Biomolecular engineering at the University of Melbourne, was published today in the leading journal Advanced Materials.
Professor Hagemeyer said this latest step offers a revolutionary difference between the current treatments for blood clots and
what might be possible in the future. This life saving treatment could be administered by paramedics in emergency situations without the need for specialised equipment as is currently the case. ee created a nanocapsule that contains a clot-busting drug.
The drug-loaded nanocapsule is coated with an antibody that specifically targets activated platelets, the cells that form blood clots,
Professor Hagemeyer said. nce located at the site of the blood clot, thrombin (a molecule at the centre of the clotting process) breaks open the outer layer of the nanocapsule,
releasing the clot-busting drug. We are effectively hijacking the blood clotting system to initiate the removal of the blockage in the blood vessel,
he said. Professor Frank Caruso from the Melbourne School of engineering said the targeted drug with its novel delivery method can potentially offer a safer alternative with fewer side effects for people suffering a heart attack
or stroke. p to 55,000 Australians experience a heart attack or suffer a stroke every year. bout half of the people who need a clot-busting drug can use the current treatments
because the risk of serious bleeding is too high, he said i
#Aluminium could give a big boost to capacity and power of lithium-ion batteries One big problem faced by electrodes in rechargeable batteries,
as they go through repeated cycles of charging and discharging, is that they must expand and shrink during each cycle sometimes doubling in volume,
and then shrinking back. This can lead to repeated shedding and reformation of its kinlayer that consumes lithium irreversibly,
degrading the battery performance over time. Now a team of researchers at MIT and Tsinghua University in China has found a novel way around that problem:
creating an electrode made of nanoparticles with a solid shell, and a olkinside that can change size again and again without affecting the shell.
The innovation could drastically improve cycle life, the team says, and provide a dramatic boost in the battery capacity and power.
The new findings, which use aluminum as the key material for the lithium-ion battery negative electrode,
or anode, are reported in the journal Nature Communications, in a paper by MIT professor Ju Li and six others.
The use of nanoparticles with an aluminum yolk and a titanium dioxide shell has proven to be he high-rate champion among high-capacity anodes
the team reports. Most present lithium-ion batteries the most widely used form of rechargeable batteries use anodes made of graphite, a form of carbon.
Graphite has a charge storage capacity of 0. 35 ampere-hours per gram (Ah/g; for many years, researchers have explored other options that would provide greater energy storage for a given weight.
Lithium metal, for example, can store about 10 times as much energy per gram, but is extremely dangerous,
capable of short-circuiting or even catching fire. Silicon and tin have very high capacity,
but the capacity drops at high charging and discharging rates. Aluminum is a low-cost option with theoretical capacity of 2 Ah/g. But aluminum and other high-capacity materials,
Li says, xpand a lot when they get to high capacity, when they absorb lithium. And then they shrink
when releasing lithium. This expansion and contraction of aluminum particles generates great mechanical stress, which can cause electrical contacts to disconnect.
Also, the liquid electrolyte in contact with aluminum will always decompose at the required charge/discharge voltages,
forming a skin called solid electrolyte interphase (SEI) layer, which would be ok if not for the repeated large volume expansion and shrinkage that cause SEI particles to shed.
As a result, previous attempts to develop an aluminum electrode for lithium-ion batteries had failed.
That where the idea of using confined aluminum in the form of a yolk-shell nanoparticle came in.
In the nanotechnology business there is a big difference between what are called ore-shelland olk-shellnanoparticles.
The former have a shell that is bonded directly to the core, but yolk-shell particles feature a void between the two equivalent to where the white of an egg would be.
As a result, the olkmaterial can expand and contract freely, with little effect on the dimensions
and stability of the hell. e made a titanium oxide shell, Li says, hat separates the aluminum from the liquid electrolytebetween the battery two electrodes.
The shell does not expand or shrink much, he says, so the SEI coating on the shell is very stable
and does not fall off, and the aluminum inside is protected from direct contact with the electrolyte.
The team didn originally plan it that way, says Li, the Battelle Energy Alliance Professor in Nuclear Science and Engineering,
who has a joint appointment in MIT Department of Materials science and engineering. e came up with the method serendipitously,
it was a chance discovery, he says. The aluminum particles they used, which are about 50 nanometers in diameter,
naturally have oxidized an layer of alumina (Al2o3). e needed to get rid of it, because it not good for electrical conductivity, Li says.
They ended up converting the alumina layer to titania (Tio2), a better conductor of electrons and lithium ions when it is very thin.
which reacts with titanium oxysulfate to form a solid shell of titanium hydroxide with a thickness of 3 to 4 nanometers.
the aluminum core continuously shrinks to become a 30-nm-across olk, which shows that small ions can get through the shell.
but the inside of the electrode remains clean with no buildup of the SEIS, proving the shell fully encloses the aluminum
The result is an electrode that gives more than three times the capacity of graphite (1. 2 Ah/g) at a normal charging rate
For applications that require a high power-and energy density battery, he says, t probably the best anode material available.
Full cell tests using lithium iron phosphate as cathode have been successful, indicating ATO is quite close to being ready for real applications. hese yolk-shell particles show very impressive performance in lab-scale testing,
says David Lou, an associate professor of chemical and biomolecular engineering at Nanyang Technological University in Singapore, who was involved not in this work. o me,
the most attractive point of this work is that the process appears simple and scalable.
There is much work in the battery field that uses omplicated synthesis with sophisticated facilities, Lou adds,
but such systems re unlikely to have impact for real batteries. Simple things make real impact in the battery field. e
#Narrowing the gap between synthetic and natural graphene Producing graphene in bulk is critical when it comes to the industrial exploitation of this exceptional two-dimensional material.
To that end, Graphene Flagship researchers have developed a novel variant on the chemical vapour deposition process which yields high quality material in a scalable manner.
From sticky tape to chemical synthesis Media-friendly Nobel laureates peeling layers of graphene from bulk graphite with sticky tape may capture the public imagination,
CVD graphene with help from intermolecular forces Flagship-affiliated physicists from RWTH Aachen University and Forschungszentrum Jülich have together with colleagues in Japan devised a method for peeling graphene flakes from a CVD substrate
the first author of which is research student Luca Banszerus. Key to the process is the strong Van der waals interaction that exists between graphene and hexagonal boron nitride, another 2d material within
which it is encapsulated. The Van der waals force is the attractive sum of short-range electric dipole interactions between uncharged molecules.
Thanks to strong Van der waals interactions between graphene and boron nitride, CVD graphene can be separated from the copper
and transferred to an arbitrary substrate. The process allows for reuse of the catalyst copper foil in further growth cycles
Raman spectroscopy and transport measurements on the graphene/boron nitride heterostructures reveals high electron mobilities comparable with those observed in similar assemblies based on exfoliated graphene.
#Graphene nanoribbon finding could lead to faster, more efficient electronics Graphene, an atom-thick material with extraordinary properties, is a promising candidate for the next generation of dramatically faster, more energy-efficient electronics.
However, scientists have struggled to fabricate the material into ultra-narrow strips, called nanoribbons, that could enable the use of graphene in high-performance semiconductor electronics.
Now, University of Wisconsin-Madison engineers have discovered a way to grow graphene nanoribbons with desirable semiconducting properties directly on a conventional germanium semiconductor wafer.
This breakthrough could allow manufacturers to easily use graphene nanoribbons in hybrid integrated circuits which promise to significantly boost the performance of next-generation electronic devices.
This technology could also have specific uses in industrial and military applications, such as sensors that detect specific chemical and biological species
and photonic devices that manipulate light. In a paper published August 10, 2015 in the journal Nature Communications, Michael Arnold, an associate professor of materials science and engineering at UW-Madison, Phd student Robert Jacobberger,
and their collaborators describe their new approach to producing graphene nanoribbons. Importantly, their technique can easily be scaled for mass production
and is compatible with the prevailing infrastructure used in semiconductor processing. raphene nanoribbons that can be grown directly on the surface of a semiconductor like germanium are more compatible with planar processing that used in the semiconductor industry,
and so there would be less of a barrier to integrating these really excellent materials into electronics in the future,
Arnold says. Graphene, a sheet of carbon atoms that is only one atom in thickness, conducts electricity and dissipates heat much more efficiently than silicon,
the material most commonly found in today's computer chips. But to exploit graphene remarkable electronic properties in semiconductor applications where current must be switched on and off,
graphene nanoribbons need to be less than 10 nanometers wide, which is phenomenally narrow. In addition, the nanoribbons must have smooth
well-defined rmchairedges in which the carbon-carbon bonds are parallel to the length of the ribbon.
Researchers have fabricated typically nanoribbons by using lithographic techniques to cut larger sheets of graphene into ribbons.
However, this op-downfabrication approach lacks precision and produces nanoribbons with very rough edges. Another strategy for making nanoribbons is to use a ottom-upapproach such as surface-assisted organic synthesis,
where molecular precursors react on a surface to polymerize nanoribbons. Arnold says surface-assisted synthesis can produce beautiful nanoribbons with precise, smooth edges,
but this method only works on metal substrates and the resulting nanoribbons are thus far too short for use in electronics.
To overcome these hurdles the UW-Madison researchers pioneered a bottom-up technique in which they grow ultra-narrow nanoribbons with smooth,
straight edges directly on germanium wafers using a process called chemical vapor deposition. In this process, the researchers start with methane,
which adsorbs to the germanium surface and decomposes to form various hydrocarbons. These hydrocarbons react with each other on the surface,
where they form graphene. Arnold team made its breakthrough when it explored dramatically slowing the growth rate of the graphene crystals by decreasing the amount of methane in the chemical vapor deposition chamber.
They found that at a very slow growth rate the graphene crystals naturally grow into long nanoribbons on a specific crystal facet of germanium.
By simply controlling the growth rate and growth time, the researchers can easily tune the nanoribbon width be to less than 10 nanometers. hat wee discovered is that
when graphene grows on germanium, it naturally forms nanoribbons with these very smooth, armchair edges,
Arnold says. he widths can be very, very narrow and the lengths of the ribbons can be very long,
so all the desirable features we want in graphene nanoribbons are happening automatically with this technique. he nanoribbons produced with this technique start nucleating,
or growing, at seemingly random spots on the germanium and are oriented in two different directions on the surface.
Arnold says the team future work will include controlling where the ribbons start growing and aligning them all in the same direction.
Image: Progressively zoomed-in images of graphene nanoribbons grown on germanium. The ribbons automatically align perpendicularly
and naturally grow with their edges oriented along the carbon-carbon bond direction, known as the armchair edge configuration a
#Hundredfold improvement in temperature mapping reveals the stresses inside nanoscale transistors New nanoscale thermal imaging technique shows heat building up inside microprocessors,
A team of users and staff working at the Molecular Foundry have created a thermal imaging technique that can eehow temperature changes from point to point inside the smallest electronic circuits.
Fan-cooled heat sink on a microprocessor. Plasmon energy expansion thermometry, inset, uses a beam of electrons to track where heat is produced
and how it dissipates with nanometer accuracy. Image courtesy of The Molecular Foundry) Used in everything from cell phones to supercomputers,
modern microelectronic circuits contain billions of nanometer scale transistors, each generating tiny amounts of heat that collectively can compromise the performance of the device.
Seeing where the heat is generated provides valuable information for circuit designers to probe where failures are occurring
and to realize the next generation microprocessors. Electrons passing through a sample excite collective charge oscillations called plasmons.
Monitoring the energy required to excite the plasmons enables measuring local variations in a sample density,
which are directly related to the local temperature within an integrated circuit or transistor. Based on these principles
the researchers developed a new technique called plasmon energy expansion thermometry, or PEET. It enables measuring local temperature with 3-5 K precision and 5 nm spatial resolution.
The new technique provides 100-fold better resolution than optical pyrometry. The new technique is the only technique that allows correlation of atomically resolved structure to a device thermal characteristics s
#Black phosphorus surges ahead of graphene A Korean team of scientists tune black phosphorus's band gap to form a superior conductor,
allowing for the application to be produced mass for electronic and optoelectronics devices. The research team operating out of Pohang University of Science and Technology (POSTECH),
affiliated with the Institute for Basic Science (IBS) Center for Artificial Low Dimensional Electronic systems (CALDES), reported a tunable band gap in black phosphorus (BP),
effectively modifying the semiconducting material into a unique state of matter with anisotropic dispersion. This research outcome potentially allows for great flexibility in the design and optimization of electronic and optoelectronic devices like solar panels and telecommunication lasers.
The natural successor to Graphene? Credit: Institute for Basic Science To truly understand the significance of the team findings,
it instrumental to understand the nature of two-dimensional (2-D) materials, and for that one must go back to 2010
when the world of 2-D materials was dominated by a simple thin sheet of carbon,
a layered form of carbon atoms constructed to resemble honeycomb, called graphene. Graphene was heralded globally as a wonder-material thanks to the work of two British scientists who won the Nobel prize for Physics for their research on it.
Graphene is extremely thin and has remarkable attributes. It is stronger than steel yet many times lighter
more conductive than copper and more flexible than rubber. All these properties combined make it a tremendous conductor of heat and electricity.
A defectree 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.
For all its dazzling promise there is however a disadvantage; graphene has no band gap. Stepping stones to a Unique State A material band gap is fundamental to determining its electrical conductivity.
Imagine two river crossings, one with tightly-packed stepping-stones, and the other with large gaps between stones.
The former is far easier to traverse because a jump between two tightly-packed stones requires less energy.
A band gap is much the same; the smaller the gap the more efficiently the current can move across the material and the stronger the current.
Graphene has a band gap of zero in its natural state, however, and so acts like a conductor;
the semiconductor potential can be realized because the conductivity can be shut off, even at low temperatures. This obviously dilutes its appeal as a semiconductor,
as shutting off conductivity is a vital part of a semiconductor function. Birth of a Revolution Phosphorus is the fifteenth element in the periodic table
and lends its name to an entire class of compounds. Indeed it could be considered an archetype of chemistry itself.
Black phosphorus is the stable form of white phosphorus and gets its name from its distinctive color.
Like graphene, BP is a semiconductor and also cheap to mass produce. The one big difference between the two is BP natural band gap
allowing the material to switch its electrical current on and off. The research team tested on few layers of BP called phosphorene
an amiable professor stationed at POSTECH speaks in rapid bursts when detailing the experiment, e transferred electrons from the dopant-potassium-to the surface of the black phosphorus,
which is required what we to tune the size of the band gap. This process of transferring electrons is known as doping
which tuned the band gap allowing the valence and conductive bands to move closer together, effectively lowering the band gap
and drastically altering it to a value between 0. 0 0. 6 Electron volt (ev) from its original intrinsic value of 0. 35 ev.
Professor Kim explained, raphene is a Dirac semimetal. It more efficient in its natural state than black phosphorus but it difficult to open its band gap;
therefore we tuned BP band gap to resemble the natural state of graphene, a unique state of matter that is different from conventional semiconductors.
The potential for this new improved form of black phosphorus is beyond anything the Korean team hoped for,
and very soon it could potentially be applied to several sectors including engineering where electrical engineers can adjust the band gap
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