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There are possibilities that Sargent is affiliated with other companies such as qspw and god knows how involved he is at kaust.
Honestly we have no clue what's goingon. It's a segment with a lot of business who suffered losses. This stock has been holding, but for how long can it stay with non compliance issues and what not.
.
OTC=revenues, be in compliance.
KAUST signs solar tech agreement
by Utilities ME Staff on Oct 11, 2011
KAUST signs solar licence agreement. (Getty Images)
Saudi Arabia's King Abdullah University of Science and Technology (KAUST) has inked a licence agreement with the University of Toronto for rights to a new solar power technology.
Developed by Dr Edward Sargent, Canada research chair in nanotechnology at the University of Toronto, the quantum dot solar cell technology uses quantum dots to convert the sun's power efficiently into electrical energy.
Dr Sargent's work has been funded by KAUST since 2008 as part of its global collaborative research programme, according to a report published by state news agency SPA.
KAUST said the technology has made great strides towards the goal of breaking the present-day constraining paradigm between high efficiency and low cost in solar cells.
Np I've held apple since 85$ been of hell of a ride
Apple Announces Plans to Build America’s Largest End User–Owned Onsite Solar Array
http://inhabitat.com/apple-to-build-americas-largest-end-user%E2%80%93owned-onsite-solar-array/
RECOMMENDED FOR YOU:
bloom energy, apple, maiden north carolina, apple maiden facility, maiden data center, apple data center, apple renewable energy, apple fuel cell, apple renewable energy use, apple renewable energy products, fuel cell, bloom energy fuel cell, fuel cell installation
Bloom Energy Rumored to be Behind Apple’s Massive End-User Fuel Cell Project
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Energy
Tafline Laylin
Apple Announces Plans to Build America’s Largest End User–Owned Onsite Solar Array
by Tafline Laylin, 02/21/12
filed under: clean tech, News, Renewable Energy, Solar Power
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Apple, 2012 environmental report, Maiden, North Carolina, LEED, Platinum, USGBC, Data Center, green design, sustainable design, eco design, cleantech, renewable energy, solar power
As Apple’s social record undergoes continued scrutiny the company just released its 2012 environmental report, which unveils plans to build America’s largest end user-owned onsite solar array at its massive data center in Maiden, North Carolina. The building itself is the world’s only LEED Platinum certified data center, and the 100-acre, 20-megawatt solar farm will supply 42 million kWh of clean, renewable energy annually.
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sustainableliving.mum.edu/welcome/
Apple, 2012 environmental report, Maiden, North Carolina, LEED, Platinum, USGBC, Data Center, green design, sustainable design, eco design, cleantech, renewable energy, solar power
Many people don’t realize it, but processing digital data requires a lot of energy, which is why Apple has committed to such a rigorous renewable program. In addition to the massive solar array, the company plans to build a fuel cell installation later this year. When complete, the 5 megawatt facility will be the largest non-utility fuel cell installation operating anywhere in the country. Located astride the white-roofed data center, it will be powered entirely by biogas and will provide more than 40 million kWh of 24×7 baseload renewable energy every year.
Apple insists that they are “committed to pursuing energy-efficient growth by increasing our renewable energy participation to match the growing needs of our data center—through our own projects as well as partnerships with utilities and renewable energy providers.”
+ Apple
Read more: Apple Announces Plans to Build America's Largest End User–Owned Onsite Solar Array | Inhabitat - Green Design Will Save the World
Apple Announces Plans to Build America’s Largest End User–Owned Onsite Solar Array
http://inhabitat.com/apple-to-build-americas-largest-end-user%E2%80%93owned-onsite-solar-array/
RECOMMENDED FOR YOU:
bloom energy, apple, maiden north carolina, apple maiden facility, maiden data center, apple data center, apple renewable energy, apple fuel cell, apple renewable energy use, apple renewable energy products, fuel cell, bloom energy fuel cell, fuel cell installation
Bloom Energy Rumored to be Behind Apple’s Massive End-User Fuel Cell Project
X
Energy
Tafline Laylin
Apple Announces Plans to Build America’s Largest End User–Owned Onsite Solar Array
by Tafline Laylin, 02/21/12
filed under: clean tech, News, Renewable Energy, Solar Power
Share on Tumblr
Email
Apple, 2012 environmental report, Maiden, North Carolina, LEED, Platinum, USGBC, Data Center, green design, sustainable design, eco design, cleantech, renewable energy, solar power
As Apple’s social record undergoes continued scrutiny the company just released its 2012 environmental report, which unveils plans to build America’s largest end user-owned onsite solar array at its massive data center in Maiden, North Carolina. The building itself is the world’s only LEED Platinum certified data center, and the 100-acre, 20-megawatt solar farm will supply 42 million kWh of clean, renewable energy annually.
Ads by Google
sustainableliving.mum.edu/welcome/
Apple, 2012 environmental report, Maiden, North Carolina, LEED, Platinum, USGBC, Data Center, green design, sustainable design, eco design, cleantech, renewable energy, solar power
Many people don’t realize it, but processing digital data requires a lot of energy, which is why Apple has committed to such a rigorous renewable program. In addition to the massive solar array, the company plans to build a fuel cell installation later this year. When complete, the 5 megawatt facility will be the largest non-utility fuel cell installation operating anywhere in the country. Located astride the white-roofed data center, it will be powered entirely by biogas and will provide more than 40 million kWh of 24×7 baseload renewable energy every year.
Apple insists that they are “committed to pursuing energy-efficient growth by increasing our renewable energy participation to match the growing needs of our data center—through our own projects as well as partnerships with utilities and renewable energy providers.”
+ Apple
Read more: Apple Announces Plans to Build America's Largest End User–Owned Onsite Solar Array | Inhabitat - Green Design Will Save the World
their websites look like the least of their concerns.
this is the link from november 2011
http://drugdiscoverynews.com/index.php?newsarticle=5519
Lets see what happened since.
is that old newS or NEW.
One day I will be able to answer all the questions we had about qmc. Good or Bad.
Have a good weekend all.
Now can I knock on doors and sell the dots in Canada?
Type in google : quantum dot diagnostics
See what pops up, another universe
When/where
http://www.genomecanada.ca/medias/pdf/en/QuantumDotDiagnostics.pdf
Another project brought to you by
Quantum Dot Diagnostics: Simultaneous Genomic and Proteomic Profiling of Multiple Pathogens at Point-of-Care
Status Current
Competition III
Sector Development of New Technologies
Genome Centre Ontario Genomics Institute
Project Leaders Kevin Kain, Michael Greenberg & Warren Chan
Project Description
World wide, infectious diseases cause billions of infections and over 17 million deaths each year. With its well-traveled population and cultural diversity, Canada is at risk of global diseases such as SARS (severe acute respiratory syndrome), malaria and avian influenza (bird flu). But Canada is developing cutting-edge expertise in the rapid and accurate diagnosis of infectious diseases, based on nanotechnology. Dr. Kevin C. Kain, Director of the McLaughlin-Rotman Center for Global Health and Senior Scientist in the division of genomic medicine at the Toronto General Research Institute, and Dr. Michael Greenberg, FIO Corp, are project leaders of Quantum dot diagnostics: simultaneous genomic and proteomic profiling of multiple pathogens at point-of-care. They have assembled a research team that will incorporate advances in nanotechnology with pathogen genomics and proteomics, in order to create a high-throughput diagnostic system capable of detecting multiple global infectious diseases within minutes. The system is based on quantum dots - tiny fluorescent probes that can be used as biomarkers to tag organic molecules and track them during biological processes. The research team plans to develop this diagnostic system specifically for use at point of care, in order to detect or exclude the presence of pathogens related to five major infectious diseases - SARS, HIV/AIDS, malaria, hepatitis B and hepatitis C. The social and economic potential of this innovative system is underscored by the fact that these five diseases account for over 2 billion infections and 5 million deaths world wide each year. The project is organized into a continuous discovery pipeline, making it possible to accelerate discovery of diagnostic tools, commercialize them and translate them into clinical use. According to Dr. Kain, "the ability to definitively detect or exclude multiple pathogens at point of care within minutes would be a breakthrough with impact on our healthcare system, the quality of life of Canadians as well as global communities."
Yes that was a great conference too bad it wasnt in montreal...
And when Will A serious investor believe in qmc's tech help them to grow. 201?
Anyone wanna bet on 323?
Apple joins exclusive $500bn club
http://www.ft.com/cms/s/2/a49cb190-6228-11e1-872e-00144feabdc0.html#axzz1nnqYbEnJ
High quality global journalism requires investment. Please share this article with others using the link below, do not cut & paste the article. See our Ts&Cs and Copyright Policy for more detail. Email ftsales.support@ft.com to buy additional rights. http://www.ft.com/cms/s/2/a49cb190-6228-11e1-872e-00144feabdc0.html#ixzz1nnr36koT
Apple has joined an elite group of companies to reach a $500bn equity valuation amid expectations it is to launch a new version of the iPad next week.
Shares in the iPhone maker rose by nearly 2 per cent to $535.41 on Tuesday, lifting its equity value to $504bn. Apple shares are already up 32 per cent this year, extending gains over the past 10 years to 4,500 per cent.
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AppleClick to enlarge
Apple is the world’s most valuable company – valued at about $90bn more than ExxonMobil – and stock market analysts remain bullish. Of 56 analysts tracking Apple to be surveyed by Bloomberg, 51 rate the stock a “buy” with four maintaining a “hold” stance. Only one has a “sell” rating.
The bout of optimism has been fuelled by expectations that an iPad will be launched at a media event that Apple has called for next Wednesday and by speculation that the company could pay its first dividend. The new iPad is expected to cement Apple’s lead in the new category of touchscreen tablet computers it created, with technical advances that include a higher resolution screen, faster chips and, possibly, a connection to the latest high-speed 4G networks.
Tim Cook, chief executive, told Apple’s annual meeting last week that the board was “thinking very deeply” about what to do with its cash reserves. Apple’s cash topped $97bn at the end of last year and would have surged past $100bn based on rates of cash generation.
Unlike market capitalisation, which is based only on the number of a company’s shares in issue, equity value includes options and other instruments likely to be turned into stock in future, presenting a truer picture of a company’s stock market value.
Apple’s market capitalisation is now $499bn. This is close to the combined value of the last three technology companies that came close to, or surpassed, the $500bn market capitalisation – Microsoft (now $266bn), Intel ($136bn) and Cisco ($109bn). Those three reached their peak valuations in the dotcom boom years of 1999 and 2000, with Microsoft surpassing $600bn in 2000 – a record unmatched. ExxonMobil and General Electric are the only others to pass $500bn.
Apple has added $175bn to its value in the space of a year, but still trades on a price to earnings ratio of 11 based on Wall Street estimates for 2012 fiscal year earnings, says FactSet.
Hello,
Thanks for keeping this board up.
I'm from Montreal. Read about graphene a few years ago. Have a few positions in related graphene stocks.
Exciting times ahead with anything to do with graphene. And the fact that its being mined in my backyard makes it even more interesting to follow !
I'm long term on this one and have some NG also.
GLTA
Reasons to keep an open mind
Man will never reach the moon regardless of all future scientific advances."
Dr. Lee DeForest, "Father of Radio & Grandfather of Television."
"The bomb will never go off. I speak as an expert in explosives."
Admiral William Leahy, US Atomic Bomb Project
"There is no likelihood man can ever tap the power of the atom."
Robert Millikan, Nobel Prize in Physics, 1923
"Computers in the future may weigh no more than 1.5 tons."
Popular Mechanics, forecasting the relentless march of science, 1949
"I think there is a world market for maybe five computers."
Thomas Watson, chairman of IBM, 1943
"I have traveled the length and breadth of this country and talked with the best people, and I can assure you that data processing is a fad that won't last out the year."
The editor in charge of business books for Prentice Hall, 1957
"But what is it good for?"
Engineer at the Advanced Computing Systems Division of IBM, 1968, commenting on the microchip.
"640K ought to be enough for anybody."
Bill Gates, 1981
This 'telephone' has too many shortcomings to be seriously considered as a means of communication. The device is inherently of no value to us."
Western Union internal memo, 1876.
"The wireless music box has no imaginable commercial value. Who would pay for a message sent to nobody in particular?"
David Sarnoff's associates in response to his urgings for investment in the radio in the 1920s.
"The concept is interesting and well-formed, but in order to earn better than a 'C,' the idea must be feasible."
A Yale University management professor in response to Fred Smith's paper proposing reliable overnight delivery service. (Smith went on to found Federal Express Corp.)
"I'm just glad it'll be Clark Gable who's falling on his face and not Gary Cooper,"
Gary Cooper on his decision not to take the leading role in "Gone With The Wind."
"A cookie store is a bad idea. Besides, the market research reports say America likes crispy cookies, not soft and chewy cookies like you make,"
Response to Debbi Fields' idea of starting Mrs. Fields' Cookies.
"We don't like their sound, and guitar music is on the way out."
Decca Recording Co. rejecting the Beatles, 1962.
"Heavier-than-air flying machines are impossible,"
Lord Kelvin, president, Royal Society, 1895.
"If I had thought about it, I wouldn't have done the experiment. The literature was full of examples that said you can't do this."
Spencer Silver on the work that led to the unique adhesives for 3-M "Post-It" Notepads.
"Drill for oil? You mean drill into the ground to try and find oil? You're crazy!"
Response from drillers Edwin L. Drake tried to enlist to his project to drill for oil in 1859.
Stocks have reached what looks like a permanently high plateau."
Irving Fisher, Professor of Economics, Yale University, 1929.
"Airplanes are interesting toys but of no military value."
Marechal Ferdinand Foch, Professor of Strategy, Ecole Superieure de Guerre, France.
"Everything that can be invented has been invented."
Charles H. Duell, Commissioner, US Office of Patents, 1899.
"The super computer is technologically impossible. It would take all of the water that flows over Niagara Falls to cool the heat generated by the number of vacuum tubes required."
Professor of Electrical Engineering, New York University
"I don't know what use any one could find for a machine that would make copies of documents. It certainly couldn't be a feasible business by itself."
The head of IBM, refusing to back the idea, forcing the inventor to found Xerox.
"Louis Pasteur's theory of germs is ridiculous fiction."
Pierre Pachet, Professor of Physiology at Toulouse, 1872
"The abdomen, the chest, and the brain will forever be shut from the intrusion of the wise and humane surgeon,"
Sir John Eric Ericksen, British surgeon, appointed Surgeon-Extraordinary to Queen Victoria 1873.
And last but not least...
"There is no reason anyone would want a computer in their home."
Ken Olson, president, chairman and founder of Digital Equipment Corp., 1977
Any News on Rice ?
It's very frustrating to always seem behind on everything.
Could they be for once on time publicly for a deadline? That would make great PR.
Is it too much to ask?
GLTA
What if they announced they can produce 100k a day!
Judgment day?
Deception...
Stevia corp has www.stevia.co website
Company actually selling product with revenues is www.stevia.com
Look for yourself.
I have no problem giving out my e-mail now b4 it gets too busy...
Yes we can do a group , I'm down for that
http://nanotechweb.org/cws/companies/category/669
Qtmm is listed on here, not sure if this link was ever posted.
I got out at 1:45 saw going it above 2.00 but then the decline with the rumors of pump & dump. Bought at .845 so wasnt bad for me. If it does go back down I'll buy again.
The current partners at Kaust are pretty big players from the list we see... ( I never realized bp had a solar unit...)
If only for now they would be supplying qtmm dots for the big boys listed at kaust.
Lots of people with means that are in the solar panel business. Would be nice if they can get picked up or do business with them.
Unless you think Qtmm is in a position to take these big boys head on?
GLTA
Are those Breast implants stuffed with tetrapod quantum dots?
They do have a technological partnership, own would presume that qmc's dots would be the vehicle for these nanoparticles.
They got an initial first order and just got another order.
I'm sure we will get our turn to.
It's cadmium free type they are using.
Don't know which one will stand out.
Graphene quantom dots also to think about.
Thanks for clarifying that.
Crunch55
Nanoco has 400k revenue per employee with a profit margin of 56%. There stock is at 63$ and going to blow out when they release their their next filing which will come out this week.
I didn't say how great they were I just posted what they are producing.
Nothing personal.
Happy trading.
Nice,
I've been looking for mining companies that mine graphene.
Going to look for other materials that revolve all these quantom dot products...
http://www.nanosysinc.com/what_we_do/led_backlighting/
Display Backlighting
Nanosys is changing the way we see things. Our quantum dot technology creates a visual experience that is truer to reality by enabling LCDs to display 3 times more color than they can today. This means richer, more viscerally alive reds, a deeper palette of greens (the color the human eye sees more intensely than any other color) and vivid blues. Browsing through photos on a tablet is now more like holding a stack of high quality, professional prints. Watching a movie on a big screen in the living room is more akin to attending a private screening at a Hollywood studio.
How does it work?
QDEF™ (Quantum Dot Enhancement Film) is composed of Nanosys’ proprietary, high efficiency quantum dot phosphors. Larger than a water molecule, but smaller than a virus, these tiny phosphors convert blue light from a standard GaN LED into different wavelengths based upon their size. Larger dots emit longer wavelengths (red), while smaller dots emit shorter wavelengths (green). Blending together a mix of dot colors allows Nanosys to engineer a new spectrum of light. This allows LCD manufacturers to accurately match their LED backlight to their LCD color filters to achieve the best possible color and efficiency performance. The result is professional photo and cinema level color performance in the palm of your hand or on your living room wall.
While other advanced display technologies promise good color, most lack sufficient brightness to be used outdoors and are not scalable to high volume or large panel sizes. Smartphone, tablet, notebook computer and television manufacturers can turn to QDEF™ based displays instead – yielding eye-catching products, available today using existing LCD panel manufacturing infrastructure.
Process-ready components like QDEF™ integrate easily and affordably on a mass scale with existing LCD BLU manufacturing processes. Nanosys has formed definitive commercial agreements with cutting edge electronics component manufacturers including LG Innotek (LGIT) and Samsung for the first commercial application of quantum dots in consumer electronics. With the need for brighter, cheaper, better LED displays in everything from HD televisions to tablet PCs, Nanosys materials are unlocking the barriers to an enhanced color experience.
What’s the difference?
QDEF™ The QDEF™ is an optical film component for LED-driven LCD backlight units that can be scaled to any size, from tablets to large format televisions. Designed to replace the functionality of a diffuser sheet while actively converting color, QDEF™ can simply be added to the stack with little change in overall thickness or manufacturing process.
I'm keeping my eyes open to what's out there.
No rants here, just reality check.
I have shares in qtmm trust me I want them to succeed.
Filing was nice, they are still looking for financing to continue in order to execute they might be at a standstill if they can't get funds. IMO
Nothing personal here.
May the Gods give power to them to spit those dots out!
Like lightning striking!
GLTA
If It could be that easy, that would be sweet.
They better get cracking and working around the clock in that case.
April 4, 2011 -- Nanoco Group plc (AIM: NANO), cadmium-free quantum dots manufacturer, produced a 1kg batch of red cadmium-free quantum dots (CFQD) for a major Japanese corporation, which triggers a US$2 million payment to Nanoco by the corporation.
Hi Ripster,
I totally agree.
This takes time, and will the tech be obsolete by the time they get to execution? Makes me feel like buying a bakery wouldnt it be so much easier to sell bread?
Look at link from 2007,
In 2007 rice university.
http://www.media.rice.edu/media/NewsBot.asp?MODE=VIEW&ID=9542
Rice University scientists today revealed a breakthrough method for producing molecular specks of semiconductors called quantum dots, a discovery that could clear the way for better, cheaper solar energy panels.
Research by Michael Wong and scientists at Rice's Center for Biological and Environmental Nanotechnology revealed a breakthrough method for producing molecular specks of semiconductors called quantum dots, a discovery that could clear the way for better, cheaper solar energy panels.
The research, by scientists at Rice's Center for Biological and Environmental Nanotechnology (CBEN), appears this week in the journal Small. It describes a new chemical method for making four-legged cadmium selenide quantum dots, which previous research has shown to be particularly effective at converting sunlight into electrical energy.
"Our work knocks down a big barrier in developing quantum-dot-based photovoltaics as an alternative to the conventional, more expensive silicon-based solar cells," said paper co-author and principal investigator Michael Wong, assistant professor of chemical and biomolecular engineering.
Quantum dots are "megamolecules" of semiconducting materials that are smaller than living cells. They interact with light in unique ways, to give off different-colored light or to create electrons and holes, due partly to their tiny size, partly to their shape and partly to the material they're made of. Scientists have studied quantum dots for more than a decade, with an eye toward using them in medical tests, chemical sensors and other devices.
One way towards cheaper solar cells is to make them out of quantum dots. Prior research by others has shown that four-legged quantum dots, which are called tetrapods, are many times more efficient at converting sunlight into electricity than regular quantum dots. But, Wong said the problem is that there is still no good way of producing tetrapods. Current methods lead to a lot of particles with uneven-length arms, crooked arms, and even missing arms. Even in the best recipe, 30 percent of the prepared particles are not tetrapods, he said.
CBEN's formula, which was developed by Wong and his graduate student Subashini Asokan with CBEN Director Vicki Colvin and graduate student Karl Krueger, produces same-sized particles, in which more than 90 percent are tetrapods. Significantly, these tetrapods are made of cadmium selenide, which have been very difficult to make, until now. The essence of the new recipe is to use cetyltrimethylammonium bromide instead of the standard alkylphosphonic acid compounds. Cetyltrimethylammonium bromide happens to be safer – it's used in some shampoos, for example – and it's much cheaper than alkylphosphonic acids. For producers looking to eventually ramp up tetrapod production, this means cheaper raw materials and less purification steps, Wong said.
"One of the major bottlenecks in developing tetrapod-based solar cell devices has been removed, namely the unavailability of high-quality tetrapods of the cadmium selenide kind," Wong said. "We might be able to make high-quality nanoshapes of other compositions also, using this new synthesis chemistry."
The research was funded by the National Science Foundation, 3M Corp., Advanced Aromatics LP, the Air Force Office of Scientific Research and Rice University.
http://nextbigfuture.com/2012/01/graphene-quantum-dots-made-in-bulk-from.html
JANUARY 12, 2012
Graphene quantum dots made in bulk from carbon fiber
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A Rice University laboratory has found a way to turn common carbon fiber into graphene quantum dots, tiny specks of matter with properties expected to prove useful in electronic, optical and biomedical applications.
The Rice lab of materials scientist Pulickel Ajayan, in collaboration with colleagues in China, India, Japan and the Texas Medical Center, discovered a one-step chemical process that is markedly simpler than established techniques for making graphene quantum dots.
Nanoletters - Graphene Quantum Dots Derived from Carbon Fibers
Graphene quantum dots (GQDs), which are edge-bound nanometer-size graphene pieces, have fascinating optical and electronic properties. These have been synthesized either by nanolithography or from starting materials such as graphene oxide (GO) by the chemical breakdown of their extended planar structure, both of which are multistep tedious processes. Here, we report that during the acid treatment and chemical exfoliation of traditional pitch-based carbon fibers, that are both cheap and commercially available, the stacked graphitic submicrometer domains of the fibers are easily broken down, leading to the creation of GQDs with different size distribution in scalable amounts. The as-produced GQDs, in the size range of 1–4 nm, show two-dimensional morphology, most of which present zigzag edge structure, and are 1–3 atomic layers thick. The photoluminescence of the GQDs can be tailored through varying the size of the GQDs by changing process parameters. Due to the luminescence stability, nanosecond lifetime, biocompatibility, low toxicity, and high water solubility, these GQDs are demonstrated to be excellent probes for high contrast bioimaging and biosensing applications.
"There have been several attempts to make graphene-based quantum dots with specific electronic and luminescent properties using chemical breakdown or e-beam lithography of graphene layers," said Ajayan, Rice's Benjamin M. and Mary Greenwood Anderson Professor of Mechanical Engineering and Materials Science and of chemistry. "We thought that as these nanodomains of graphitized carbons already exist in carbon fibers, which are cheap and plenty, why not use them as the precursor?”
Quantum dots, discovered in the 1980s, are semiconductors that contain a size- and shape-dependent band gap. These have been promising structures for applications that range from computers, LEDs, solar cells and lasers to medical imaging devices. The sub-5 nanometer carbon-based quantum dots produced in bulk through the wet chemical process discovered at Rice are highly soluble, and their size can be controlled via the temperature at which they're created.
The Rice researchers were attempting another experiment when they came across the technique. "We tried to selectively oxidize carbon fiber, and we found that was really hard," said Wei Gao, a Rice graduate student who worked on the project with lead author Juan Peng, a visiting student from Nanjing University who studied in Ajayan's lab last year. "We ended up with a solution and decided to look at a few drops with a transmission electron microscope."
The specks they saw were bits of graphene or, more precisely, oxidized nanodomains of graphene extracted via chemical treatment of carbon fiber. "That was a complete surprise," Gao said. "We call them quantum dots, but they're two-dimensional, so what we really have here are graphene quantum discs." Gao said other techniques are expensive and take weeks to make small batches of graphene quantum dots. "Our starting material is cheap, commercially available carbon fiber. In a one-step treatment, we get a large amount of quantum dots. I think that's the biggest advantage of our work," she said.
Further experimentation revealed interesting bits of information: The size of the dots, and thus their photoluminescent properties, could be controlled through processing at relatively low temperatures, from 80 to 120 degrees Celsius. "At 120, 100 and 80 degrees, we got blue, green and yellow luminescing dots," she said.
They also found the dots' edges tended to prefer the form known as zigzag. The edge of a sheet of graphene -- the single-atom-thick form of carbon -- determines its electrical characteristics, and zigzags are semiconducting.
Their luminescent properties give graphene quantum dots potential for imaging, protein analysis, cell tracking and other biomedical applications, Gao said. Tests at Houston's MD Anderson Cancer Center and Baylor College of Medicine on two human breast cancer lines showed the dots easily found their way into the cytoplasm and did not interfere with the cells' proliferation.
"The green quantum dots yielded a very good image," said co-author Rebeca Romero Aburto, a graduate student in the Ajayan lab who also studies at MD Anderson. "The advantage of graphene dots over fluorophores is that their fluorescence is more stable and they don't photobleach. They don't lose their fluorescence as easily. They have a depth limit, so they may be good for in vitro and in vivo (small animal) studies, but perhaps not optimal for deep tissues in humans.
"But everything has to start in the lab, and these could be an interesting approach to further explore for bioimaging," Romero Alburto said. "In the future, these graphene quantum dots could have high impact because they can be conjugated with other entities for sensing applications, too."