Paving Way for Paper-thin Displays
Researchers from the Korean’s KAIST institute developed a new process to produce graphene quantum dots that are equal in size and highly efficient in emitting light. Quantum Dots potentially can be used to develop emissive flexible displays (similar to OLED displays), and this development may enable those displays to be graphene-based.
The process involves mixing salt, water and graphite and then synthesizing a chemical compound between layers of graphite. All the resulting quantum dots were 5 nanometer in diameter, and these QDs do not contain and heavy metals (like current commercial quantum dots). The process is reportedly easy to scale and should not be expensive.
A Korean research team has successfully developed high-quality graphene quantum dots that are equal in size and highly efficient in emitting light. This technology is expected to be used in developing paper-thin displays or displaying information in flexible materials.
The Korea Advanced Institute of Science and Technology (KAIST) announced on August 28 that a research team led by Jun Suk-woo, professor of the department of materials science and engineering at KAIST, has succeeded in making graphene quantum dots by mixing water and salt into graphite and then synthesizing a chemical compound between layers of graphite, in collaboration with professors Jo Young-hoon and Ryu Seung-hyup. Quantum dots are nanometer-sized round semiconductor nanoparticles that are very efficient at emitting photons very quickly.
They are receiving a lot of attention as a possible next-gen technology in quantum information and communications because of these properties. The diameter of the equally-sized graphene quantum dots was 5 nanometers. Unlike existing quantum dots, new ones are eco-friendly, since they do not require toxic materials like lead and cadmium. Moreover, it is possible to mass-produce newly-developed quantum dots at little cost, because they are made of easily-obtainable materials such as graphite, water, and salt.
In the past, it was difficult to commercialize graphene quantum dots, in that it was not easy to synthesize a large number of equal size. Another factor was low efficiency from the way the particles were put together. The team developed and confirmed the possibility of the commercialization of graphene quantum dot LEDs with more than 1000cd/m2 brightness using graphene quantum dots, which are brighter than displays for cell phones.
Professor Jun remarked, “The new quantum dots are not as efficient as existing LEDs in emitting lights. However, the characteristics of emitting lights can be improved further.” He added, “I hope that it will be possible to make paper-thin displays and exhibit information in soft materials like curtains using this method.” The research findings were first published online on August 20 by Advanced Optical Materials, a scientific journal published by Wiley-VCH.
– See more at: http://www.businesskorea.co.kr/article/6151/quantum-dots-paving-way-paper-thin-displays#sthash.fksItjw8.dpuf
The researchers say that those gQDs could be used to develop LEDs that have a brightness of over 1000cd/m2. This is less efficient than current LEDs, but the researchers hope this technology can be further improved.
Source: Business Korea
12 Sep 2014
|The lectures of Nobel Prize winning physicist Richard Feynman were legendary. They are most famously preserved in The Feynman Lectures. The three-volume set may be the most popular collection of physics books ever written, and now you can access it online, in its entirety, for free.|
|Caltech and The Feynman Lectures Website are presenting this online edition of The Feynman Lectures on Physics. Now, anyone with internet access and a web browser can enjoy reading a high quality up-to-date copy of Feynman’s legendary lectures.
|Richard Feynman talking with a teaching assistant after the lecture on The Dependence of Amplitudes on Time, Robert Leighton and Matthew Sands in background, April 29, 1963. (© California Institute of Technology)|
|Volume 1 – mainly mechanics, radiation and heat|
|Volume 2 – mainly electromagnetism and matter|
|Volume 3 – quantum mechanics|
|Please note that this edition is only free to read online, and the posting on Caltech’s website does not transfer any right to download all or any portion of The Feynman Lectures on Physics for any purpose.|
|This edition has been designed for ease of reading on devices of any size or shape; text, figures and equations can all be zoomed without degradation.|
Graphene electrodes are one of the best prospects for enabling supercapacitors and superbatteries to take up to half of the lithium-ion battery market in 15 years – amounting to tens of billions of dollars yearly.
They may also be key to supercapacitors taking much of the multibillion dollar aluminium electrolytic capacitor business. That would make supercapacitors and supercabatteries (notably in the form of lithium-ion capacitors) one of the largest applications for graphene.
Cambridge, UK | Posted on August 20th, 2014
Heirarchical to exohedral?
Today’s supercapacitor electrodes usually have hierarchical electrode structures with large pores progressing to small pores letting appropriate electrolyte ions into monolithic masses of carbon. In research, this is often giving way to better results from exohedral structures – where the large functional area is created by allotropes of carbon often only one atom thick. Examples are graphene, carbon nanotubes and nano-onions (spheres within spheres). Add to that the newer aerogels with uniform particles a few nanometers across.
It is not simply an area game. The exohedral structure must also be optimally matched to the electrolyte, then the pair assessed not just for specific capacitance (capacitance density) but voltage increase, because that also increases the commercially-important energy density when competing with batteries.
It is not a done deal. Graphene is expensive when good purity and structural integrity are required. Exohedral structures like graphene, with the greatest theoretical area, tend to improve gravimetric but not volumetric energy density. Poor volumetric energy density will cut off many applications unless structural supercapacitors prove feasible. Here the supercapacitor would replace dumb structures like car bodies, taking effectively no volume, regardless of measured volumetric energy density. Some of these formulations increase the already superb power density but that is not very exciting commercially.
Other parameters matter
Of course cost, stability, temperature performance and many other parameters must also be appropriate in all potential applications of graphene in supercapacitors and supercabatteries. Indeed for replacing electrolytic capacitors, working at 120Hz is key. In other applications, increased power density may be valuable when combined with other improvements. Nevertheless, energy density improvement is the big one for sharply increasing the addressable market – probably around 2025 or later.
Highest energy density by leveraging new generation electrolytes
Graphene gives some of the highest energy densities in the laboratory and it is particularly effective in exhibiting high specific capacitance with the new electrolytes. That means aqueous electrolytes with desirably low cost and non-flammability, and ionic electrolytes with desirably simplified manufacturing, high voltage, non-flammability, low toxicity and now exceptional temperature range.
With ionic electrolytes, graphene works despite the high viscosity that makes them ineffective in hierarchical electrode structures. On the other hand, graphene does not exhibit good specific capacitance with the old acetonitrile and propylene carbonate organic solvent electrolytes. It is advantageous that there is no solvent or solute with ionic electrolytes, though sometimes they are added to tailor the ionic supercapacitor to obtain certain performance in experiments.
With aqueous electrolytes, graphene’s accessible area is large and this offsets the low voltage to give good energy density in some experiments. Curved graphene is often used. Under a microscope it looks like crushed paper so further optimisation is possible. In the laboratory, the energy density of lead-acid and nickel cadmium batteries and even lithium-ion batteries has been achieved with various formulations involving graphene so it is likely that one of them will prove commercial in due course.
Recent developments by industrial companies demonstrate that graphene lithium-ion capacitor supercabattery systems can operate up to 3.7 V. They have a very good cycle life and excellent power performance.
AC graphene supercapacitors
Potentially, inverters in electric vehicles can be made smaller, lighter and have lower installed cost thanks to planned graphene supercapacitors replacing their large aluminium electrolytic capacitors. So far, it is only with vertically stacked graphene that the necessary time constant of 200 microseconds has been demonstrated suitable for such 120Hz filtering.
For more see the brand new IDTechEx report Functional Materials for Supercapacitors / Ultracapacitors / EDLC 2015-2025 and also Graphene Markets, Technologies and Opportunities 2014-2024. In addition, attend IDTechEx’s events Supercapacitors LIVE! USA 2014 and Graphene & 2D Materials LIVE! USA 2014 taking place in November.
12 Sep 2014
U of Maryland Researchers Discover New synthesis Method: Could Impact the Futures of Nanostructures, Clean Energy
02 Sep 2014
|Source: University of Maryland|
Researchers at Missouri University of Science and Technology have developed what they call “a simple, one-step method” to grow nanowires of germanium from an aqueous solution. Their process could make it more feasible to use germanium in lithium ion batteries.
The Missouri S&T researchers describe their method in “Electrodeposited Germanium Nanowires,” a paper published today (Thursday, Aug. 28, 2014) on the website of the journal ACS Nano. Their one-step approach could lead to a simpler, less expensive way to grow germanium nanowires.
As a semiconductor material, germanium is superior to silicon, says Dr. Jay A. Switzer, the Donald L. Castleman/Foundation for Chemical Research Professor of Discover at Missouri S&T. Germanium was even used in the first transistors. But it is more expensive to process for widespread use in batteries, solar cells, transistors and other applications, says Switzer, who is the lead researcher on the project.
Switzer and his team have had success growing other materials at the nanometer scale through electrodeposition – a process that Switzer likens to “growing rock candy crystals on a string.” For example, in a 2009 Chemistry of Materials paper, Switzer and his team reported that they had grown zinc oxide “nanospears” – each hundreds of times smaller than the width of a human hair – on a single-crystal silicon wafer placed in a beaker filled with an alkaline solution saturated with zinc ions.
But growing germanium at the nano level is not so simple. In fact, electrodeposition in an aqueous solution such as that used to grow the zinc oxide nanospears “is thermodynamically not feasible,” Switzer and his team explain in their ACS Nano paper, “Electrodeposited Germanium Nanowires.”
So the Missouri S&T researchers took a different approach. They modified an electrodeposition process found to produce germanium nanowires using liquid metal electrodes. That process, developed by University of Michigan researchers led by Dr. Stephen Maldonado and known as the electrochemical liquid-liquid-solid process (ec-LLS), involves the use of a metallic liquid that performs two functions: It acts as an electrode to cause the electrodeposition as well as a solvent to recrystallize nanoparticles.
Switzer and his team applied the ec-LLS process by electrochemically reducing indium-tin oxide (ITO) to produce indium nanoparticles in a solution containing germanium dioxide, or Ge(IV). “The indium nanoparticle in contact with the ITO acts as the electrode for the reduction of Ge(IV) and also dissolves the reduced Ge into the particle,” the Missouri S&T team reports in the ACS Nano paper. The germanium then “starts to crystallize out of the nanoparticle allowing the growth of the nanowire.”
The Missouri S&T researchers tested the effect of temperature for electrodeposition by growing the germanium nanowires at room temperature and at 95 degrees Celsius (203 degrees Fahrenheit). They found no significant difference in the quality of the nanowires, although the nanowires grown at room temperature had smaller diameters. Switzer believes that the ability to produce the nanowires at room temperature through this one-step process could lead to a less expensive way to produce the material.
“The high conductivity (of germanium nanowires) makes them ideal for lithium-ion battery applications,” Switzer says.
More information: “Electrodeposited Germanium Nanowires.” Naveen K. Mahenderkar, Ying-Chau Liu, Jakub A. Koza, and Jay A. Switzer. ACS Nano Article ASAP DOI: 10.1021/nn503784d Tilted
Many common materials exhibit different and potentially useful characteristics when fabricated at extremely small scales—that is, at dimensions near the size of atoms, or a few ten-billionths of a meter. These “atomic scale” or “nanoscale” properties include quantized electrical characteristics, glueless adhesion, rapid temperature changes, and tunable light absorption and scattering that, if available in human-scale products and systems, could offer potentially revolutionary defense and commercial capabilities.
Two as-yet insurmountable technical challenges, however, stand in the way: Lack of knowledge of how to retain nanoscale properties in materials at larger scales, and lack of assembly capabilities for items between nanoscale and 100 microns—slightly wider than a human hair.
DARPA has created the Atoms to Product (A2P) program to help overcome these challenges. The program seeks to develop enhanced technologies for assembling atomic-scale pieces. It also seeks to integrate these components into materials and systems from nanoscale up to product scale in ways that preserve and exploit distinctive nanoscale properties.
“We want to explore new ways of putting incredibly tiny things together, with the goal of developing new miniaturization and assembly methods that would work at scales 100,000 times smaller than current state-of-the-art technology,” said John Main, DARPA program manager. “If successful, A2P could help enable creation of entirely new classes of materials that exhibit nanoscale properties at all scales. It could lead to the ability to miniaturize materials, processes and devices that can’t be miniaturized with current technology, as well as build three-dimensional products and systems at much smaller sizes.”
This degree of scaled assembly is common in nature, Main continued. “Plants and animals, for example, are effectively systems assembled from atomic- and molecular-scale components a million to a billion times smaller than the whole organism. We’re trying to lay a similar foundation for developing future materials and devices.”
To familiarize potential participants with the technical objectives of the A2P program, DARPA has scheduled identical Proposers Day webinars on Tuesday, September 9, 2014, and Thursday, September 11, 2014. Advance registration is required and closes on September 5, 2014, at 5:00 PM Eastern Time. Participants must register through the registration website: http://www.sa-meetings.com/A2PProposersDay.
The DARPA Special Notice announcing the Proposers’ Day webinars is available at http://go.usa.gov/mgKB. This announcement does not constitute a formal solicitation for proposals or abstracts and is issued solely for information and program planning purposes. The Special Notice is not a Request for Information (RFI); therefore, DARPA will accept no submissions against this announcement. DARPA expects to release a Broad Agency Announcement (BAA) with full technical details on A2P soon on the Federal Business Opportunities website (www.fbo.gov).
01 Sep 2014
University of Alberta researcher Dr. John Lewis peers into a microscope that was purpose-built to study how cancer cells form “tentacles” allowing them to spread through the body. His team’s findings were published in the most recent issue of the journal, Cell Reports. Photograph by: Supplied , University of Alberta
EDMONTON – A study led by a University of Alberta research team has pinpointed how cancer cells form “tentacles” to spread from one part of the body to another, a finding that could open up new possibilities for treatment.
The team spent three years observing how micron-sized cancer cells develop tentacles, called invadopodia, that allow them to move from the bloodstream into another organ. Scientists had never before observed the phenomenon in a live model.
“At an airplane terminal, you have all of your paperwork in place and there are guards to check it and make sure you’re secure. The body is the same way,” said Dr. John Lewis, associate professor in the university’s department of oncology.
“The immune system checks cells as they escape and filters them … This process of escape from the bloodstream is an important checkpoint where most of the cancer cells are destroyed. But if they’re able to produce these invadopodia — the right paperwork — they’re able to escape.”
Lewis noted the deadliest aspect of cancer is often its spread to other organs in the body. Ninety per cent of patients who die of cancer have metastasis, or the spread of cancer.
“No man will die of prostate cancer if it stays in his prostate. It becomes dangerous when it spreads … The prostate is not life-threatening if you lose it,” said Lewis, who holds the Frank and Carla Sojonky Chair in Prostate Cancer Research.
That’s why understanding how cancer spreads is so important. The team’s research found doctors could use drugs or genetic means to stop the development of invadopodia.
The drug used by the team is already in clinical cancer trials, which Lewis called “encouraging.” He also noted there is evidence showing that doing a biopsy or surgery on a cancer tumour can sometimes cause cancer to spread, which would make an invadopodia inhibitor particularly important in those cases. The development of an inhibitor that directly attacks invadopodia will likely take five to 10 years, he said.
Lewis and his team used a $500,000 microscope and the protein of a deepsea jelly fish to do their work. The protein glows fluorescent green and clearly shows up in images as the cancer cell against a backdrop of red blood cells. The microscope was purpose-built for this study and is one of only two such microscopes in the world.
The study and the microscope were partially funded by the Alberta Cancer Foundation, which helped bring Lewis from Western University in Ontario to Alberta.
“I don’t have enough to say about John and his team; they’re experts in the field,” said Raja Mita, the foundation’s director of program investments. “He has credibility on the research side and also on taking scientific discoveries from the bench to the bedside.”
The team’s work was published in the most recent issue of the journal Cell Reports. Some of the study work was done by scientists at the Lawson Health Research Institute in Ontario.
01 Sep 2014
Nanotechnology has the potential to radically improve our everyday lives – whether by revolutionising the way we receive life-saving medicines, or by dramatically increasing the speed at which a tumour can be treated.
The origins of nanotechnology, or nanoscience, date back to 1959 when US physicist Richard Feynman gave a talk to the American Physical Society entitled: ’There’s Plenty of Room at the Bottom’.
Though the term ’nanotechnology’ was not coined until a decade after Feynman’s talk, it was the driving force behind much of his work.
Now, more than half a century later, nanotechnology is widely considered the disruptive science that will forcibly eradicate previous, less effective technologies.
In terms of size, a single sheet of newspaper measures roughly 100,000 nanometres thick.
What scientists stress as equally important as its size, however, is the reactive nature of a nanomaterials’ surface.
Nanomaterials such as graphene possess outstanding mechanical, thermal and electrical properties, and boast a density half that of aluminium – making it useful in the construction of some sports equipment (see image).
“You can send electrical signals using graphene far faster than you can with other materials
Senior lecturer David Carey
Senior lecturer in electronic engineering at the University of Surrey David Carey says: “Graphene has mechanical properties that exceed Young’s Modulus which exceeds almost all known materials, making it extremely light.”
For Carey, at the university’s new graphene centre, which forms part of its wider Advanced Technology Institute (ATI), there is a strong interest in the characterisation of high-frequency materials.
“You can send electrical signals using graphene far faster than you can with other materials, and that is why graphene within high-speed electronic equipment is becoming increasingly sought after,” Carey says.
“A really good example of that is within antennas. If you make a mobile phone antenna smaller and smaller, the electrical losses get bigger and bigger. But if you use graphene, those losses do not happen.”
Perhaps most fascinating, however, is the potential to use nanomaterials such as graphene within advanced drug delivery, as an aid to nanomedicine.
Carey says that patients often get extremely sick from chemotherapy drugs because they are powerful medicines that spread throughout the body, rather than being constrained to a more localised area.
“If you can coat your vessel, such as a carbon nanotube, so those drugs only go to a tumour, then the patient has to consume far less medicine and therefore they don’t have such bad side-effects,” Carey says.
“Through this method, patients [can] recover far better and far more quickly.”
For Johnathan Aylott, associate professor in analytical bioscience at the Nottingham Nanotechnology & Nanoscience Centre (NNNC), however, nanomedicine technologies can sometimes fail as they cannot effectively manipulate the intelligent defence mechanisms inherent within our cellular structures.
“If you have a nanoparticle entering a cell, the cell works well to process it and get it contained and out the other side, which is why people talk about [how effective] nanotechnology can be in the delivery of drugs,” Aylott says.
“There are very few good examples of this technology currently on the market, however.”
To combat this, Aylott says researchers are engineering nanoparticles that effectively disguise themselves.
“With stealth nanoparticles, the idea is to trick the body into not realising what this ’thing’ is so it can deliver the drug effectively,” Aylott says.
Though Aylott admits there is huge potential for the use of stealth nanoparticles, knowing how these particles are processed and trafficked in the body unfortunately remains a barrier.
Yet, in developing our understanding of the human body even further, scientists are attempting to reimagine relatively modern processes using advances in nanoscience.
Professor Nicholas Long of Imperial College London’s (ICL) department of chemistry says his research into self-assembling nanoparticles centres on radically increasing the sensitivity of the contrast agents used in imaging applications.
“As long as we can persuade enough people that we have a good idea, we get to push the boundaries of what’s out there
NNNC associate professor Johnathan Aylott
“MRI (Magnetic Resonance Imaging) is brilliant in terms of showing very clearly defined images, but you need to use a lot of contrast agent to give you enough signal, and some of the commonly used agents are very toxic,” Long says.
To counter this, Long, alongside researchers at ICL, has developed a protein-coated iron-oxide nanoparticle designed to aid tumour diagnosis.
“Iron-oxide nanoparticles are attractive because they have some inherent magnetic behaviour. And, as far as we know, they are benign, as opposed to other contrast agents,” he says.
Long says when using iron-oxide nanoparticles, a more powerful signal and a clearer MRI image of the tumours his team attempted to scan was produced.
Looking ahead, the main objective of Long’s research is to adapt the technology for use in human clinical trials.
“That’s the big goal for us. We need to do further animal work before we can move to human trials, but assuming they work well, we can apply for further funding [and start testing in humans],” Long says.
In an ideal world, Long says this treatment could be available within 10 years, depending on the outcome of more rigorous testing.
Fortunately, our understanding and acceptance of nanotechnology is gaining pace, and in the last decade especially, investment in the nano-sciences has benefited from some major monetary boosts.
“As long as we can persuade enough people that we have a good idea, we get to push the boundaries of what’s out there,” says Aylott.
Though nanotechnology deals in the realms of the almost unfathomably small, and can often only make incremental progress, given the right circumstances, and continued support, its potential to radicalise our everyday lives certainly seems mighty.