#Beyond LEDS: Brighter new energy saving flat panel lights based on carbon nanotubes Even as the 2014 Nobel prize in Physics has enshrined light emitting diodes (LEDS) as the single most significant and disruptive energy-efficient lighting solution of today scientists
around the world continue unabated to search for the even-better-bulbs of tomorrow. Electronics based on carbon especially carbon nanotubes (CNTS) are emerging as successors to silicon for making semiconductor materials.
And they may enable a new generation of brighter low-power low-cost lighting devices that could challenge the dominance of light-emitting diodes (LEDS) in the future
and help meet society's ever-escalating demand for greener bulbs. Scientists from Tohoku University in Japan have developed a new type of energy-efficient flat light source based on carbon nanotubes with very low power consumption of around 0. 1 Watt for every hour's operation
about a hundred times lower than that of an LED. In the journal Review of Scientific instruments from AIP publishing the researchers detail the fabrication
and optimization of the device which is based on a phosphor screen and single-walled carbon nanotubes as electrodes in a diode structure.
You can think of it as a field of tungsten filaments shrunk to microscopic proportions. They assembled the device from a mixture liquid containing highly crystalline single-walled carbon nanotubes dispersed in an organic solvent mixed with a soap-like chemical known as a surfactant.
Then they painted the mixture onto the positive electrode or cathode and scratched the surface with sandpaper to form a light panel capable of producing a large stable and homogenous emission current with low energy consumption.
Our simple'diode'panel could obtain high brightness efficiency of 60 Lumen per Watt which holds excellent potential for a lighting device with low power consumption said Norihiro Shimoi the lead researcher and an associate professor of environmental studies at the Tohoku University.
Brightness efficiency tells people how much light is being produced by a lighting source when consuming a unit amount of electric power
which is an important index to compare the energy-efficiency of different lighting devices Shimoi said.
For instance LEDS can produce 100s Lumen per Watt and OLEDS (organic LEDS) around 40. Although the device has a diode-like structure its light-emitting system is not based on a diode system
which are made from layers of semiconductors materials that act like a cross between a conductor and an insulator the electrical properties
of which can be controlled with the addition of impurities called dopants. The new devices have luminescence systems that function more like cathode ray tubes with carbon nanotubes acting as cathodes
and a phosphor screen in a vacuum cavity acting as the anode. Under a strong electric field the cathode emits tight high-speed beams of electrons through its sharp nanotube tips a phenomenon called field emission.
The electrons then fly through the vacuum in the cavity and hit the phosphor screen into glowing.
We have found that a cathode with highly crystalline single-walled carbon nanotubes and an anode with the improved phosphor screen in our diode structure obtained no flicker field emission current and good brightness homogeneity Shimoi said.
Field emission electron sources catch scientists'attention due to its ability to provide intense electron beams that are about a thousand times denser than conventional thermionic cathode (like filaments in an incandescent light bulb.
That means field emission sources require much less power to operate and produce a much more directional and easily controllable stream of electrons.
In recent years carbon nanotubes have emerged as a promising material of electron field emitters owing to their nanoscale needle shape and extraordinary properties of chemical stability thermal conductivity and mechanical strength.
Highly crystalline single-walled carbon nanotubes (HCSWCNT) have nearly zero defects in the carbon network on the surface Shimoi explained.
The resistance of cathode electrode with highly crystalline single-walled carbon nanotube is very low. Thus the new flat-panel device has compared smaller energy loss with other current lighting devices
which can be used to make energy-efficient cathodes that with low power consumption. Many researchers have attempted to construct light sources with carbon nanotubes as field emitter Shimoi said.
But nobody has developed an equivalent and simpler lighting device. Considering the major step for device manufacture the wet coating process is a low-cost
but stable process to fabricate large-area and uniformly thin films the flat-plane emission device has the potential to provide a new approach to lighting in people's life style
and reduce carbon dioxide emissions on the earth Shimoi said d
#Physicists set new records for silicon quantum computing Two research teams working in the same laboratories at UNSW Australia have found distinct solutions to a critical challenge that has held back the realisation of super
powerful quantum computers. The teams created two types of quantum bits or qubits the building blocks for quantum computers that each process quantum data with an accuracy above 99%.
%The two findings have been published simultaneously today in the journal Nature Nanotechnology. For quantum computing to become a reality we need to operate the bits with very low error rates says Scientia Professor Andrew Dzurak who is Director of the Australian National Fabrication Facility at UNSW where the devices were made.
We've now come up with two parallel pathways for building a quantum computer in silicon each
of which shows this super accuracy adds Associate professor Andrea Morello from UNSW's School of Electrical engineering and Telecommunications.
The UNSW teams which are affiliated also with the ARC Centre of Excellence for Quantum Computation
& Communication Technology were first in the world to demonstrate single-atom spin qubits in silicon reported in Nature in 2012 and 2013.
Now the team led by Dzurak has discovered a way to create an artificial atom qubit with a device remarkably similar to the silicon transistors used in consumer electronics known as MOSFETS.
Postdoctoral researcher Menno Veldhorst lead author on the paper reporting the artificial atom qubit says It is really amazing that we can make such an accurate qubit using pretty much the same devices as we have in our laptops and phones.
Meanwhile Morello's team has been pushing the natural phosphorus atom qubit to the extremes of performance.
Dr Juha Muhonen a postdoctoral researcher and lead author on the natural atom qubit paper notes:
The phosphorus atom contains in fact two qubits: the electron and the nucleus. With the nucleus in particular we have achieved accuracy close to 99.99%.
%That means only one error for every 10000 quantum operations. Dzurak explains that even though methods to correct errors do exist their effectiveness is guaranteed only
if the errors occur less than 1%of the time. Our experiments are among the first in solid-state
and the first-ever in silicon to fulfill this requirement. The high-accuracy operations for both natural and artificial atom qubits is achieved by placing each inside a thin layer of specially purified silicon containing only the silicon-28 isotope.
The purified silicon was provided through collaboration with Professor Kohei Itoh from Keio University in Japan.
what is modified basically a version of a normal transistor is something that almost nobody believed possible until today Morello says.
Storing quantum information for 30 seconds in a nanoelectronic device Nature Nanotechnology DOI: 10.1038/nnano. 2014.211 An addressable quantum dot qubit with fault-tolerant control-fidelity Nature Nanotechnology DOI:
10.1038/nnano. 2014.21 1
#DNA nanofoundries cast custom-shaped 3-D metal nanoparticles Researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard university have unveiled a new method to form tiny 3d metal nanoparticles
in prescribed shapes and dimensions using DNA Nature's building block as a construction mold. The ability to mold inorganic nanoparticles out of materials such as gold and silver in precisely designed 3-D shapes is a significant breakthrough that has the potential to advance laser technology microscopy solar cells electronics environmental testing
disease detection and more. We built tiny foundries made of stiff DNA to fabricate metal nanoparticles in exact three-dimensional shapes that we digitally planned
and designed said Peng Yin senior author of the paper Wyss core faculty member and Assistant professor of Systems Biology at Harvard Medical school.
The Wyss team's findings described in a paper titled Casting Inorganic Structures with DNA Molds were published today in Science.
The work was done in collaboration with MIT's Laboratory for Computational biology and Biophysics led by Mark Bathe senior co-author of the paper.
The paper's findings describe a significant advance in DNA NANOTECHNOLOGY as well as in inorganic nanoparticle synthesis Yin said.
For the very first time a general strategy to manufacture inorganic nanoparticles with user-specified 3d shapes has been achieved to produce particles as small as 25 nanometers or less with remarkable precision (less than 5 nanometers.
A sheet of paper is approximately 100000 nanometers thick. The 3d inorganic nanoparticles are conceived first and meticulously planned using computer design software.
Using the software the researchers design three-dimensional frameworks of the desired size and shape built from linear DNA sequences
which attract and bind to one another in a predictable manner. Over the years scientists have been very successful at making complex 3d shapes from DNA using diverse strategies said Wei Sun a postdoctoral scholar in the Wyss'Molecular Systems Lab
and the lead author of the paper. For example in 2012 the Wyss team revealed how computer-aided design could be used to construct hundreds of different self-assembling one-two-and three-dimensional DNA nanoshapes with perfect accuracy.
It is this ability to design arbitrary nanostructures using DNA manipulation that inspired the Wyss team to envision using these DNA structures as practical foundries or molds for inorganic substances.
The challenge was to translate this kind of 3d geometrical control into the ability to cast structures in other diverse
and functionally-relevant materials such as gold and silver Sun said. Just as any expanding material can be shaped inside a mold to take on a defined 3d form the Wyss team set out to grow inorganic particles within the confined hollow spaces of stiff DNA nanostructuresthe concept can be likened to the Japanese method of growing watermelons in glass cubes.
By nurturing watermelon seeds to maturity inside cube-shaped glass boxes Japanese farmers create cube-shaped mature melons that allow for densely-packed shipping and storage of the fruit.
The Wyss researchers similarly planted a miniscule gold seed inside the hollow cavity of their carefully designed cube-shaped DNA mold
and then stimulated it to grow. Using an activating chemical solution the gold seed grew
and expanded to fill all existing space within the DNA framework resulting in a cuboid nanoparticle with the same dimensions as its mold. with the length width
Next researchers fabricated varied 3d polygonal shapes spheres and more ambitious structures such as a 3d Y-shaped nanoparticle and another structure comprising a cuboid shape sandwiched between two spheres proving that structurally-diverse
nanoparticles could be shaped using complex DNA mold designs. Given their unthinkably small size it may come as a surprise that stiff DNA molds are proportionally quite robust and strong able to withstand the pressures of expanding inorganic materials.
Although the team selected gold seedlings to cast their nanoparticles there is a wide range of inorganic nanoparticles that can be shaped forcibly through this process of DNA nanocasting.
A very useful property is that once cast these nanoparticles can retain the framework of the DNA mold as an outer coating enabling additional surface modification with impressive nanoscale precision.
These coatings can also help scientists develop highly sensitive multiplex methods of detecting early-stage cancers
and genetic diseases by combining the chemical specificity of the DNA with the signal readout of the metal.
For particles that would better serve their purpose by being as electrically conducive as possible such as in very small nanocomputers
and encode the building blocks of life have been harnessed re-purposed and re-imagined for the nanomanufacturing of inorganic materials said Don Ingber Wyss Institute founding director.
This capability should open up entirely new strategies for fields ranging from computer miniaturization to energy and pathogen detection n
#Nanoparticle research could enhance drug delivery through skin Scientists at the University of Southampton have identified key characteristics that enhance a nanoparticle's ability to penetrate skin in a milestone study which could have major implications for the delivery of drugs.
Nanoparticles are up to 100000 times smaller than the thickness of a human hair and drugs delivered using them as a platform can be concentrated more targeted
and efficient than those delivered through traditional means. Although previous studies have shown that nanoparticles interact with the skin conditions in these experiments have not been controlled sufficiently to establish design rules that enhance penetration.
Now a multidisciplinary team from the University has explored changes in the surface charge shape and functionality (controlled through surrounding molecules) of gold nanoparticles to see how these factors affect skin penetration.
By creating nanoparticles with different physicochemical characteristics and testing them on skin we have shown that positively charged nanorod shaped nanoparticles are two to six times more effective at penetrating skin than others says lead author Dr Antonios Kanaras.
When the nanoparticles are coated with cell penetrating peptides the penetration is enhanced further by up to ten times with many particles making their way into the deeper layers of the skin (such as the dermis.
Establishing which characteristics contribute to penetration is also important in discovering ways to prevent potentially toxic nanoparticles in other materials such as cosmetics from entering the skin.
The research which has been published in the journal Small drew on the medical expertise of Dr Neil Smyth and Dr Michael Ardern-Jones as well as contributions from physicist Professor Otto Muskens.
Phd student Rute Fernandes conducted the experimental work. Our interest is focused now on incorporating these findings into the design of new nanotechnological drugs for transdermal therapy says Dr Kanaras.
We welcome the opportunity to work with external partners in industry and government in order to achieve this s
#Drug-infused nanoparticle is right for sore eyes For the millions of sufferers of dry eye syndrome their only recourse to easing the painful condition is to use drug-laced eye drops three times a day.
Now researchers from the University of Waterloo have developed a topical solution containing nanoparticles that will combat dry eye syndrome with only one application a week.
The eye drops progressively deliver the right amount of drug-infused nanoparticles to the surface of the eyeball over a period of five days before the body absorbs them.
One weekly dose replaces 15 or more to treat the pain and irritation of dry eyes.
The nanoparticles about 1/1000th the width of a human hair stick harmlessly to the eye's surface and use only five per cent of the drug normally required.
You can't tell the difference between these nanoparticle eye drops and water said Shengyan (Sandy) Liu a Phd candidate at Waterloo's Faculty of engineering who led the team of researchers from the Department of Chemical engineering and the Centre for Contact lens Research.
There's no irritation to the eye. Dry eye syndrome is a more common ailment for people over the age of 50
and may eventually lead to eye damage. More than six per cent of people in the U s. have it.
Currently patients must frequently apply the medicine three times a day because of the eye's ability to self-cleanse a process that washes away 95 per cent of the drug.
I knew that if we focused on infusing biocompatible nanoparticles with Cyclosporine A the drug in the eye drops
and make them stick to the eyeball without irritation for longer periods of time it would also save patients time
and reduce the possibility of toxic exposure due to excessive use of eye drops said Liu.
The research team is now focusing on preparing the nanoparticle eye drops for clinical trials with the hope that this nanoparticle therapy could reach the shelves of drugstores within five years.
Liu's research article co-authored by eight others including Professors Frank Gu and Lyndon Jones from Waterloo recently appeared in Nano Research the leading publication on nanotechnology and nanoscience e
#'Endless possibilities'for bionanotechnology Scientists from the University of Leeds have taken a crucial step forward in bionanotechnology,
a field that uses biology to develop new tools for science, technology and medicine. The new study, published in print today in the journal Nano Letters,
demonstrates how stable'lipid membranes'the thin'skin'that surrounds all biological cells can be applied to synthetic surfaces.
Importantly, the new technique can use these lipid membranes to'draw'akin to using them like a biological ink with a resolution of 6 nanometres (6 billionths of a meter),
which is much smaller than scientists had thought previously was possible.""This is smaller than the active elements of the most advanced silicon chips
and promises the ability to position functional biological molecules such as those involved in taste, smell,
and other sensory roles with high precision, to create novel hybrid bioelectronic devices, "said Professor Steve Evans,
from the School of Physics and Astronomy at the University of Leeds and a co-author of the paper.
In the study, the researchers used something called Atomic force microscopy (AFM), which is an imaging process that has a resolution down to only a fraction of a nanometer
and works by scanning an object with a miniscule mechanical probe. AFM however, is more than just an imaging tool
and can be used to manipulate materials in order to create nanostructures and to'draw'substances onto nano-sized regions.
The latter is called'nanolithography 'and was used the technique by Professor Evans and his team in this research.
The ability to controllably'write 'and'position'lipid membrane fragments with such high precision was achieved by Mr George Heath,
a Phd student from the School of Physics and Astronomy at the University of Leeds and the lead author of the research paper.
Mr Heath said:""The method is much like the inking of a pen. However, instead of writing with fluid ink, we allow the lipid molecules the ink to dry on the tip first.
which is the natural environment for lipid membranes. Previously, other research teams have focused on writing with lipids in air
and to aid our understanding of a range of diseases, "explained Professor Evans. Aside from biological applications,
this area of research could revolutionise renewable energy production. Working in collaboration with researchers at the University of Sheffield,
Professor Evans and his team have all of the membrane proteins required to construct a fully working mimic of the way plants capture sunlight.
Eventually the researchers will be able to arbitrarily swap out the biological units and replace them with synthetic components to create a new generation of solar cells.
Professor Evans concludes:""This is part of the emerging field of synthetic biology, whereby engineering principles are being applied to biological parts
whether it is for energy capture, or to create artificial noses for the early detection of disease
or simply to advise you that the milk in your fridge has gone off.""The possibilities are endless. l
#Targeted nanoparticles that combine imaging with two different therapies could attack cancer other conditions Nanosystems that are'theranostic'they combine both therapeutic and diagnostic functions present an exciting new opportunity for delivering drugs
to specific cells and identifying sites of disease. Bin Liu of the A*STAR Institute of Materials Research
and Engineering and colleagues at the National University of Singapore have created nanoparticles with two distinct anticancer functions
and an imaging function all stimulated on demand by a single light source. The nanoparticles also include the cell-targeting property essential for treating
and imaging in the correct locations. The system is built around a polyethylene-glycol-based polymer that carries a small peptide component that allows it to bind preferentially to specific cell types The polymer itself serves as a photosensitizer that can be stimulated by light to release reactive oxygen species (ROS.
It also carries the chemotherapy drug doxorubicin in a prodrug form. The natural fluorescence of the polymer assists with diagnosis and monitoring of therapy as it shows where nanoparticles have accumulated.
The ROS generated by light stimulation have a direct'photodynamic'therapeutic activity which destroys the targeted cells.
The ROS additionally break the link between the polymer and the doxorubicin. Thus cancer cells can be subjected to a two-pronged attack from the ROS therapy
and the chemotherapy drug that is released within them (see image). This is the first nanoplatform that can offer on-demand
and imaging-guided photodynamic therapy and chemotherapy with triggered drug release through one light switch explains Liu emphasizing the significance of the system.
The researchers demonstrated the power of their platform by applying it to a mixture of cultured cancer cells some
of which overexpressed a surface protein that could bind to the targeting peptide on the nanoparticles.
Fluorescence imaging indicated that the nanoparticles were taken up by the target cells and that ROS and doxorubicin were released within these cells all at significantly higher levels than in cells used as controls.
The doxorubicin that was released in the cell cytoplasm readily entered the nucleus its site of activity.
Crucially the combined therapy had a greater cytotoxic effect than any one therapy alone. The white light used in this work does not penetrate tissue sufficiently for in vivo applications Liu explains
but we are now attempting to use near-infrared laser light to improve the tissue penetration and move toward on-demand cancer therapy.
She also suggests that with a few modifications the system may be suitable for the diagnosis and treatment of other pathological processes including inflammation and HIV infection.
Explore further: Introducing the multitasking nanoparticle More information: Yuan Y. Liu J. & Liu B. Conjugated-polyelectrolyte-based polyprodrug:
Targeted and image-guided photodynamic and chemotherapy with on-demand drug release upon irradiation with a single light source.
Angewandte Chemie International Edition 53 7163#7168 (2014. dx. doi. org/10.1002/anie. 20140218 2
#Nanoparticles break the symmetry of light How can a beam of light tell the difference between left and right?
At the Vienna University of Technology (TU Wien) tiny particles have been coupled to a glass fibre. The particles emit light into the fibre in such a way that it does not travel in both directions,
as one would expect. Instead, the light can be directed either to the left or to the right.
This has become possible by employing a remarkable physical effect the spin-orbit coupling of light.
This new kind of optical switch has the potential to revolutionize nanophotonics. The researchers have published now their work in the journal Science.
Gold nanoparticles on Glass fibres When a particle absorbs and emits light, this light is emitted not just into one direction."
"A particle in free space will always emit as much light into one particular direction as it emits into the opposite direction,
"says Professor Arno Rauschenbeutel (TU Wien). His team has succeeded now in breaking this symmetry of emission using gold nanoparticles coupled to ultra-thin glass fibres.
The incident laser light determines whether the light emitted by the particle travels left or right in the glass fibre.
Bicycles and Airplane propellers This is only possible because light has an intrinsic angular momentum, the spin. Similar to a pendulum which can swing in one particular plane
or move in circles, a light wave can have different directions of oscillation. If it has a well-defined vibrational direction,
it is called a"polarized wave"."""A simple plane wave has the same polarization everywhere, "says Arno Rauschenbeutel,
"but when the intensity of the light changes locally, the polarization changes too.""Usually, the light oscillates in a plane perpendicular to its direction of propagation.
This kind of coupling is a direct consequence of the glass fibre geometry and the laws of electrodynamics.
This effect has now been demonstrated using a single gold nanoparticle on a glass fibre. The fibre is 250 times thinner than a human hair;
Such systems may one day replace the electronic circuits we are using today
#Researchers develop green tea-based'missiles'to kill cancer cells more effectively Green tea has long been known for its antioxidant, anticancer, antiaging and antimicrobial properties.
A group of researchers from the Institute of Bioengineering and Nanotechnology (IBN) of A*STAR has taken the health benefits of green tea to the next level by using one of its ingredients to develop a drug delivery system
which kills cancer cells more efficiently. A key ingredient in green tea, epigallocatechin gallate (EGCG), is an antioxidant
which is known to have therapeutic applications in the treatment of many disorders including cancer. Using EGCG IBN researchers have engineered successfully nanocarriers that can deliver drugs
and kill cancer cells more efficiently. Their work was published recently in the leading journal Nature Nanotechnology.
The numerous health benefits of green tea have inspired us to utilize it in drug delivery systems.
This is the first time that green tea has been used as a material to encapsulate and deliver drugs to cancer cells.
Our green tea nanocarrier not only delivered protein drugs more effectively to the cancer cells, the combination of carrier and drug also dramatically reduced tumor growth compared with the drug alone.
This is an exciting breakthrough in nanomedicine said IBN Executive director Professor Jackie Y. Ying. A key challenge in chemotherapy is ensuring that the drugs are delivered only to the tumor
in order to avoid harming the surrounding healthy tissues and organs. To address this researchers have focused their efforts on developing more effective drug carriers.
When injected into the body these carriers act like homing missiles traveling through the body to zoom in on the target cells where they will release the cancer-destroying drugs.
A major stumbling block in designing more effective carriers for drugs has been the drug-to-carrier ratio.
Effective therapy would typically require the administration of substantial amounts of drug-encapsulating vessels into the body.
Unfortunately existing carriers are made of materials that have no therapeutic effect and they may even cause side effects if used in large quantities.
To solve this problem IBN has designed a therapeutic nanocarrier for drug delivery using novel compounds derived from EGCG.
The core of this carrier is made of an oligomer of EGCG (OEGCG) which can encapsulate drugs and proteins such as Herceptin,
and filtered out of the body by the immune system before it reaches the tumor. Micellar nanocomplexes of less than 100 nanometers in dimension are formed from the OEGCG core
and PEG-EGCG shell protecting the protein drug from rapid proteolysis and renal clearance while providing for tumor targeting.
The research team conducted animal studies to evaluate the performance of IBN's green tea-based protein delivery system.
The study revealed that IBN's green tea nanocomplex loaded with Herceptin reduced tumor growth much more effectively
Using the new nanocarrier twice as much drug accumulated in the cancer cells indicating an improved tumor targeting ability.
At the same time the drug accumulation in the other organs was lowered substantially by 70%in the liver and kidney and by 40%in the lungs.
and can boost cancer treatment when used together with the protein drug. Unlike conventional therapy our green tea carrier can eradicate more cancer cells
and accumulate significantly less drugs in vital organs where they could cause adverse side effects. This invention could pave the way for a better drug delivery system to fight cancer,
said Dr Motoichi Kurisawa IBN Principal Research Scientist and Team Leader. IBN has filed a patent on their green tea nanocarrier
and is developing this technology for clinical applications. The green tea-based micellar complexes are also being examined for the delivery of active ingredients in personal care and nutritional products s
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