Public release date: 20-Jun-2010
Contact: Jennifer Hirsch
jfhirsch@mit.edu
617-253-1682
Massachusetts Institute of Technology
Using carbon nanotubes in lithium batteries can dramatically improve energy capacity
New method produced up to ten fold increase in power
CAMBRIDGE, Mass. -- Batteries might gain a boost in power capacity as a result of a new finding from researchers at MIT. They found that using carbon nanotubes for one of the battery's electrodes produced a significant increase — up to tenfold — in the amount of power it could deliver from a given weight of material, compared to a conventional lithium-ion battery. Such electrodes might find applications in small portable devices, and with further research might also lead to improved batteries for larger, more power-hungry applications.
To produce the powerful new electrode material, the team used a layer-by-layer fabrication method, in which a base material is alternately dipped in solutions containing carbon nanotubes that have been treated with simple organic compounds that give them either a positive or negative net charge. When these layers are alternated on a surface, they bond tightly together because of the complementary charges, making a stable and durable film.
The findings, by a team led by Associate Professor of Mechanical Engineering and Materials Science and Engineering Yang Shao-Horn, in collaboration with Bayer Chair Professor of Chemical Engineering Paula Hammond, are reported in a paper published June 20 in the journal Nature Nanotechnology. The lead authors are chemical engineering student Seung Woo Lee PhD '10 and postdoctoral researcher Naoaki Yabuuchi.
Batteries, such as the lithium-ion batteries widely used in portable electronics, are made up of three basic components: two electrodes (called the anode, or negative electrode, and the cathode, or positive electrode) separated by an electrolyte, an electrically conductive material through which charged particles, or ions, can move easily. When these batteries are in use, positively charged lithium ions travel across the electrolyte to the cathode, producing an electric current; when they are recharged, an external current causes these ions to move the opposite way, so they become embedded in the spaces in the porous material of the anode.
In the new battery electrode, carbon nanotubes — a form of pure carbon in which sheets of carbon atoms are rolled up into tiny tubes — "self-assemble" into a tightly bound structure that is porous at the nanometer scale (billionths of a meter). In addition, the carbon nanotubes have many oxygen groups on their surfaces, which can store a large number of lithium ions; this enables carbon nanotubes for the first time to serve as the positive electrode in lithium batteries, instead of just the negative electrode.
This "electrostatic self-assembly" process is important, Hammond explains, because ordinarily carbon nanotubes on a surface tend to clump together in bundles, leaving fewer exposed surfaces to undergo reactions. By incorporating organic molecules on the nanotubes, they assemble in a way that "has a high degree of porosity while having a great number of nanotubes present," she says.
Lithium batteries with the new material demonstrate some of the advantages of both capacitors, which can produce very high power outputs in short bursts, and lithium batteries, which can provide lower power steadily for long periods, Lee says. The energy output for a given weight of this new electrode material was shown to be five times greater than for conventional capacitors, and the total power delivery rate was 10 times that of lithium-ion batteries, the team says. This performance can be attributed to good conduction of ions and electrons in the electrode, and efficient lithium storage on the surface of the nanotubes.
In addition to their high power output, the carbon nanotube electrodes showed very good stability over time. After 1,000 cycles of charging and discharging a test battery, there was no detectable change in the material's performance.
The electrodes the team produced had thicknesses up to a few microns, and the improvements in energy delivery only were seen at high-power output levels. In future work, the team aims to produce thicker electrodes and extend the improved performance to low-power outputs as well, they say. In its present form, the material might have applications for small, portable electronic devices, says Shao-Horn, but if the reported high power capability were demonstrated in a much thicker form — with thicknesses of hundreds of microns rather than just a few — it might eventually be suitable for other applications such as hybrid cars.
While the electrode material was produced by alternately dipping a substrate into two different solutions — a relatively time-consuming process — Hammond suggests that the process could be modified by instead spraying the alternate layers onto a moving ribbon of material, a technique now being developed in her lab. This could eventually open the possibility of a continuous manufacturing process that could be scaled up to high volumes for commercial production, and could also be used to produce thicker electrodes with a greater power capacity. "There isn't a real limit" on the potential thickness, Hammond says. "The only limit is the time it takes to make the layers," and the spraying technique can be up to 100 times faster than dipping, she says.
Lee says that while carbon nanotubes have been produced in limited quantities so far, a number of companies are currently gearing up for mass production of the material, which could help to make it a viable material for large-scale battery manufacturing.
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Source: "High-power lithium batteries from functionalized carbon nanotube electrodes." Seung Woo Lee, Naoaki Yabuuchi, Betar M. Gallant, Shuo Chen, Byeong-Su Kim, Paula T. Hammond, & Yang Shao-Horn. Nature Nanotechnology. 19 June 2010.
Monday, June 21, 2010
Saturday, June 19, 2010
Stem cell charlatans
In the latest British Medical Journal, Bob Roehr quoted Irving Weissman, the Stanford University researcher and president of the International Society for Stem Cell Research society as saying that the society launched a patient education website "to smoke out the charlatans" who prey upon desperately ill people and their families(BMJ 2010;340:c3271. This is a step in the right direction.
Dr Weissman, clarified that probably no other society has ever done this before. He was addressing the opening of their annual meeting on 16 June, in San Francisco.
Deveoloping countries are the preferred havens for the charlatans to prey on the gullible patients.
Bob Roehr argued that the problem is large and growing. He revealed that a recent web search identified more than 200 practitioners or clinics making claims for stem cell cures;, they thrive in developing countries obviously because regulatory oversight is weak in such countries. It is unbelievable that a clinic in China claimed to have treated over 8000 people, generating over $200m (£137m; 165m) in revenue.
It is difficult to arrest these activities. The scoiety felt that basic education about stem cells may help.The society’s new website, www.closerlookatstemcells.org, offers such material. According to the website a reputable clinical trial will have a body of scientific literature behind it; will be scrutinised by an independent review board; and will have the approval of the relevant national regulatory authorities. And it will not charge for participating in the trial.
The website allows a person to submit the name of a clinic for review. The society will then ask the clinic for documentation on ethical and regulatory review of the proposed treatment. That information will form a publicly available online database. It is not clear why a crook who is cashing on the misery of a victim should cooperate for such a review.
Bob Roehr quotes the case of a farmer who spent $80,000 for a stem cell "cure" for multiple sclerosis. An instance Dr Weissman found out while he gave a lecture in his home town, Great Falls, Montana, his hometown with a population of a little over 50 000. It is a pity that people mortgage their homes desperately seeking a cure where there is none.
The service offered by the society is laudable.Jeanne F Loring from the Scripps Research Institute a speker at th emeeting highlighted other issues. She pointed ouyt that patient testimonials are a hallmark of these operations. You will not see is any scientific evidence. There will be no guarantee that you will be helped by that treatment. Lastly,there are no guarantees that you won’t be harmed.
Clinics may use inappropriate treatment. According to the researcher, these clinics often use cord blood or placental cells, which may not be appropriate for the intended use. They may use cells derived from animals, or inject cell solutions that are tainted with other products.
Dr Loring suggested that if patients could procure a sample of the cells that are going to be injected, freeze them, and send them to her, she will analyse it for free and tell you what those stem cells are. This is indeed a generous offer.She can be contacted at jloring@scripps.edu
Regrettably, reporters of some popular newspapers in India unwittingly publicize the magic cures. They do not know the damage they are doing. They must resist the temptation; publish only those cures only if they appear in peer reviewed literature.
Dr Weissman, clarified that probably no other society has ever done this before. He was addressing the opening of their annual meeting on 16 June, in San Francisco.
Deveoloping countries are the preferred havens for the charlatans to prey on the gullible patients.
Bob Roehr argued that the problem is large and growing. He revealed that a recent web search identified more than 200 practitioners or clinics making claims for stem cell cures;, they thrive in developing countries obviously because regulatory oversight is weak in such countries. It is unbelievable that a clinic in China claimed to have treated over 8000 people, generating over $200m (£137m; 165m) in revenue.
It is difficult to arrest these activities. The scoiety felt that basic education about stem cells may help.The society’s new website, www.closerlookatstemcells.org, offers such material. According to the website a reputable clinical trial will have a body of scientific literature behind it; will be scrutinised by an independent review board; and will have the approval of the relevant national regulatory authorities. And it will not charge for participating in the trial.
The website allows a person to submit the name of a clinic for review. The society will then ask the clinic for documentation on ethical and regulatory review of the proposed treatment. That information will form a publicly available online database. It is not clear why a crook who is cashing on the misery of a victim should cooperate for such a review.
Bob Roehr quotes the case of a farmer who spent $80,000 for a stem cell "cure" for multiple sclerosis. An instance Dr Weissman found out while he gave a lecture in his home town, Great Falls, Montana, his hometown with a population of a little over 50 000. It is a pity that people mortgage their homes desperately seeking a cure where there is none.
The service offered by the society is laudable.Jeanne F Loring from the Scripps Research Institute a speker at th emeeting highlighted other issues. She pointed ouyt that patient testimonials are a hallmark of these operations. You will not see is any scientific evidence. There will be no guarantee that you will be helped by that treatment. Lastly,there are no guarantees that you won’t be harmed.
Clinics may use inappropriate treatment. According to the researcher, these clinics often use cord blood or placental cells, which may not be appropriate for the intended use. They may use cells derived from animals, or inject cell solutions that are tainted with other products.
Dr Loring suggested that if patients could procure a sample of the cells that are going to be injected, freeze them, and send them to her, she will analyse it for free and tell you what those stem cells are. This is indeed a generous offer.She can be contacted at jloring@scripps.edu
Regrettably, reporters of some popular newspapers in India unwittingly publicize the magic cures. They do not know the damage they are doing. They must resist the temptation; publish only those cures only if they appear in peer reviewed literature.
Friday, June 18, 2010
Highly efficient solar cells could result from quantum dot research
Researchers from the University of Texas at Austin feel that they can enhance the limit of efficiency of currently available solar cells from 3o percent to 60 percent by converting the splar heat lost in the cells by a suitable design modification. They are confident that "there is no reason that we cannot be using solar energy 100 percent within 50 years."
The concept appears to be simple and straightforward; lot more work to advance the chemistry of semiconductor is needed to achieve the objective
K.S.Parthasarathy
EurekAlert! Public release date: 17-Jun-2010
Contact: Dr. Xiaoyang Zhu
zhu@cm.utexas.edu
512-471-9914
University of Texas at Austin
Highly efficient solar cells could result from quantum dot research
IMAGE: Xiaoyang Zhu and colleagues discovered that hot electrons can be transferred from photo-excited lead selenide nanocrystals to an electron conductor made of titanium dioxide. Their discovery points the way toward...
Click here for more information.
AUSTIN, Texas—Conventional solar cell efficiency could be increased from the current limit of 30 percent to more than 60 percent, suggests new research on semiconductor nanocrystals, or quantum dots, led by chemist Xiaoyang Zhu at The University of Texas at Austin.
Zhu and his colleagues report their results in this week's Science.
The scientists have discovered a method to capture the higher energy sunlight that is lost as heat in conventional solar cells.
The maximum efficiency of the silicon solar cell in use today is about 31 percent. That's because much of the energy from sunlight hitting a solar cell is too high to be turned into usable electricity. That energy, in the form of so-called "hot electrons," is lost as heat.
If the higher energy sunlight, or more specifically the hot electrons, could be captured, solar-to-electric power conversion efficiency could be increased theoretically to as high as 66 percent.
"There are a few steps needed to create what I call this 'ultimate solar cell,'" says Zhu, professor of chemistry and director of the Center for Materials Chemistry. "First, the cooling rate of hot electrons needs to be slowed down. Second, we need to be able to grab those hot electrons and use them quickly before they lose all of their energy."
Zhu says that semiconductor nanocrystals, or quantum dots, are promising for these purposes.
As for the first problem, a number of research groups have suggested that cooling of hot electrons can be slowed down in semiconductor nanocrystals. In a 2008 paper in Science, a research group from the University of Chicago showed this to be true unambiguously for colloidal semiconductor nanocrystals.
Zhu's team has now figured out the next critical step: how to take those electrons out.
They discovered that hot electrons can be transferred from photo-excited lead selenide nanocrystals to an electron conductor made of widely used titanium dioxide.
"If we take the hot electrons out, we can do work with them," says Zhu. "The demonstration of this hot electron transfer establishes that a highly efficient hot carrier solar cell is not just a theoretical concept, but an experimental possibility."
The researchers used quantum dots made of lead selenide, but Zhu says that their methods will work for quantum dots made of other materials, too.
He cautions that this is just one scientific step, and that more science and a lot of engineering need to be done before the world sees a 66 percent efficient solar cell.
In particular, there's a third piece of the science puzzle that Zhu is working on: connecting to an electrical conducting wire.
"If we take out electrons from the solar cell that are this fast, or hot, we also lose energy in the wire as heat," says Zhu. "Our next goal is to adjust the chemistry at the interface to the conducting wire so that we can minimize this additional energy loss. We want to capture most of the energy of sunlight. That's the ultimate solar cell.
"Fossil fuels come at a great environmental cost," says Zhu. "There is no reason that we cannot be using solar energy 100 percent within 50 years."
###
Funding for this research was provided by the U.S. Department of Energy. Coauthors include William Tisdale, Brooke Timp, David Norris and Eray Aydil from the University of Minnesota, and Kenrick Williams from The University of Texas at Austin.
Media contact: Lee Clippard, public affairs, 512-232-0675, lclippard@mail.utexas.edu
EurekAlert! ]
The concept appears to be simple and straightforward; lot more work to advance the chemistry of semiconductor is needed to achieve the objective
K.S.Parthasarathy
EurekAlert! Public release date: 17-Jun-2010
Contact: Dr. Xiaoyang Zhu
zhu@cm.utexas.edu
512-471-9914
University of Texas at Austin
Highly efficient solar cells could result from quantum dot research
IMAGE: Xiaoyang Zhu and colleagues discovered that hot electrons can be transferred from photo-excited lead selenide nanocrystals to an electron conductor made of titanium dioxide. Their discovery points the way toward...
Click here for more information.
AUSTIN, Texas—Conventional solar cell efficiency could be increased from the current limit of 30 percent to more than 60 percent, suggests new research on semiconductor nanocrystals, or quantum dots, led by chemist Xiaoyang Zhu at The University of Texas at Austin.
Zhu and his colleagues report their results in this week's Science.
The scientists have discovered a method to capture the higher energy sunlight that is lost as heat in conventional solar cells.
The maximum efficiency of the silicon solar cell in use today is about 31 percent. That's because much of the energy from sunlight hitting a solar cell is too high to be turned into usable electricity. That energy, in the form of so-called "hot electrons," is lost as heat.
If the higher energy sunlight, or more specifically the hot electrons, could be captured, solar-to-electric power conversion efficiency could be increased theoretically to as high as 66 percent.
"There are a few steps needed to create what I call this 'ultimate solar cell,'" says Zhu, professor of chemistry and director of the Center for Materials Chemistry. "First, the cooling rate of hot electrons needs to be slowed down. Second, we need to be able to grab those hot electrons and use them quickly before they lose all of their energy."
Zhu says that semiconductor nanocrystals, or quantum dots, are promising for these purposes.
As for the first problem, a number of research groups have suggested that cooling of hot electrons can be slowed down in semiconductor nanocrystals. In a 2008 paper in Science, a research group from the University of Chicago showed this to be true unambiguously for colloidal semiconductor nanocrystals.
Zhu's team has now figured out the next critical step: how to take those electrons out.
They discovered that hot electrons can be transferred from photo-excited lead selenide nanocrystals to an electron conductor made of widely used titanium dioxide.
"If we take the hot electrons out, we can do work with them," says Zhu. "The demonstration of this hot electron transfer establishes that a highly efficient hot carrier solar cell is not just a theoretical concept, but an experimental possibility."
The researchers used quantum dots made of lead selenide, but Zhu says that their methods will work for quantum dots made of other materials, too.
He cautions that this is just one scientific step, and that more science and a lot of engineering need to be done before the world sees a 66 percent efficient solar cell.
In particular, there's a third piece of the science puzzle that Zhu is working on: connecting to an electrical conducting wire.
"If we take out electrons from the solar cell that are this fast, or hot, we also lose energy in the wire as heat," says Zhu. "Our next goal is to adjust the chemistry at the interface to the conducting wire so that we can minimize this additional energy loss. We want to capture most of the energy of sunlight. That's the ultimate solar cell.
"Fossil fuels come at a great environmental cost," says Zhu. "There is no reason that we cannot be using solar energy 100 percent within 50 years."
###
Funding for this research was provided by the U.S. Department of Energy. Coauthors include William Tisdale, Brooke Timp, David Norris and Eray Aydil from the University of Minnesota, and Kenrick Williams from The University of Texas at Austin.
Media contact: Lee Clippard, public affairs, 512-232-0675, lclippard@mail.utexas.edu
EurekAlert! ]
Wednesday, June 2, 2010
Nottingham research leads to blood test for early detection of cancer
Public release date: 1-Jun-2010
Contact: Lindsay Brooke
lindsay.brooke@nottingham.ac.uk
44-115-951-5751
University of Nottingham
Nottingham research leads to blood test for early detection of cancer
The University of Nottingham spin-out company, Oncimmune Ltd, has developed a ground breaking blood test which will aid the detection of cancer as much as five years earlier than current testing methods such as mammography and CT scans. Physicians will know the result of their patient's test within one week of sending in a blood sample to Oncimmune.
Oncimmune has developed a new technique which replicates the cancer proteins that trigger the body's response to the disease and robotic technology to measure this response. This new technology (immuno-biomarkers) provides a significant advance in how early a cancer may be detected and is likely to change the current paradigm of diagnosis and treatment for most solid cancers such as lung, breast, ovarian, colon and prostate.
Based on the early work of John Robertson, a world renowned breast cancer specialist and Professor of Surgery in The University of Nottingham's Faculty of Medicine and Health Sciences, Oncimmune has successfully transferred this science into a reproducible commercial test. The test for lung cancer, EarlyCDT-Lung™ will be launched nationally in the USA this month followed by a launch in the UK early next year.
Geoffrey Hamilton-Fairley, Executive Chairman of Oncimmune, said: "We believe this test, along with the others we will launch in the next few years, will lead to a better prognosis for a significant number of cancer sufferers."
Initial research results were derived using blood samples from patients with breast cancer and a group of high risk women attending for annual mammography — which Professor Robertson had prospectively collected in Nottingham. All samples were obtained with fully informed consent as part of a study which had received approval from the appropriate ethics committee. In addition to identifying the signal in the blood of a percentage of women when they developed breast cancer the results also showed that the signal could be detected in some of the high-risk patients who had given blood samples for a number of years during their annual check up and before they were subsequently diagnosed with cancer. When these samples were run retrospectively by Professor Robertson he showed that the prototype assay test could have detected over half of these cancers up to four years before they were actually diagnosed. The work on lung cancer followed through a European Union grant which involved both The University of Nottingham and Oncimmune in a collaboration with a number of European partners.
Professor John Robertson said "I am very pleased that the initial exciting research data that we produced in the laboratories at The University of Nottingham a number of years ago have been translated by Oncimmune to the first of many tests that will help us identify cancer early. The support of the University at all levels, including past and present Vice-Chancellors, Deans of the Faculty of Medicine and Heads of School along with the University's Management Board has been essential. Some of the initial research work was supported by charitable funds and donations from patient groups. In the commercialisation of the technology there have been a number of individuals who have continued to believe in and financially support the goal of developing a blood test for the early detection of cancer without whom this technology would not have reached this milestone. It has been a long and at times very hard road in creating a robust commercial test and those involved have worked with exceptional diligence and tenacity and have given their unremitting support to achieve this."
A study involving researchers at the Mayo Clinic in the USA recorded similar results using blood samples from a study of CT scans to screen for lung cancer where antibodies were detected up to five years before the lung cancers were diagnosed. A number of other academic centres have reported similar results.
Oncimmune LTD was founded in 2003 to commercialise the technology developed in the laboratories of Professor Robertson. In 2006 the company set up a North American operation to validate and scale-up the test — trialling it on more than eight million assay "wells" from 80,000 patient samples.
The first early cancer detection test (EarlyCDT™) to launch will be the test for lung cancer (EarlyCDT-Lung) which has the potential to detect the early stages of lung cancer possibly up to five years before a tumour appears. The target population for this test are high-risk individuals such as long-term smokers and ex-smokers between the ages of 40 and 75. Additionally the test would be appropriate for people who have been exposed to other risk factors associated with the disease, for instance, environmental exposures such as radon, asbestos and extensive exposure to secondary smoke.
Under the guidance of Professor Robertson, The University of Nottingham has become a world leader in the field of autoimmunity in cancer. Using the technology developed by Oncimmune there is, for the first time, a reliable platform available for testing the autoimmune response to cancer and further research will allow validation of the test in other tumour areas such as lung, colon and ovarian cancer.
To support this, the University is to establish a Centre of Excellence for Autoimmunity in Cancer (CEAC) with Professor Robertson as the Director of Research. The new centre will foster collaborative research to: speed up the delivery of an autoantibody blood test for different types of cancer for clinical use; encourage other research in the area of autoimmunity in cancer; and continue the search for support technologies that have the potential to enhance the medical prognosis following a positive test result.
Professor David Greenaway, Vice-Chancellor of The University of Nottingham said: "The establishment of CEAC will provide state-of-the-art technologies to continue world leading research and development in the early detection of cancer using autoantibodies. The new centre will house a multi disciplinary research team working in partnership with international collaborators and Oncimmune. The research will provide additional test systems for the early diagnosis of a wide range of cancers which will have considerable impact within clinical medicine. The group's discovery science which has led to a novel set of biomarkers is providing new insights into the biology of cancer. Their basic, translational and clinical research is likely to contribute to a positive paradigm shift in our understanding of the early phases of cancer cell development as well as enhancement of the medical management of a wide range of cancer types."
Initially the test will be offered via primary care physicians and pulmonologists in the USA for high risk asymptomatic patients as well as patients who have indeterminate lung nodules. Oncimmune will bill private insurance companies as well as government-run Medicare Part B carriers on behalf of the patient.
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More information can be found at: www.oncimmune.co.uk or www.oncimmune.com
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