Theory explains how new material could improve electronic shelf life

ScienceDaily (Jan. 9, 2012) — Research by UT Dallas engineers could lead to more-efficient cooling of electronics, producing quieter and longer-lasting computers, and cellphones and other devices.

Much of modern technology is based on silicon's use as a semiconductor material, but research recently published in the journal Nature Materials shows that graphene conducts heat about 20 times faster than silicon.

"Heat is generated every time a device computes," said "Dr. Kyeongjae "KJ" Cho, associate professor of materials science and engineering and physics at UT Dallas and one of the paper's authors. "For example a laptop fan pumps heat out of the system, but heat removal starts with a chip on the inside. Engineered graphene could be used to remove heat -- fast."

It was demonstrated in 2004 that graphite could be changed into a sheet of bonded carbon atoms called graphene, which is believed to be the strongest material ever measured. Although much research has focused on the strength and electronics of the material, Cho has been studying its thermal conductivity.

As electronics become more complex and decrease in size, the challenge to remove heat from the core becomes more difficult, he said. Desktop and laptop computers have fans.

Smaller electronic devices such as cellphones have other thermoelectric cooling devices.

"The performance of an electronic device degrades as it heats up, and if it continues the device fails," said Cho, also a visiting professor at Seoul National University in South Korea.

"The faster heat is removed, the more efficient the device runs and the longer it lasts."

Research assistant Hengji Zhang of UT Dallas is also an author of the paper. Cho and Zhang have published prior papers in the Journal of Nanomaterials and Physical Review B about graphene's thermal conductivity. For the Nature Materials paper, researchers at UT Austin conducted an experiment about graphene's heat transfer. They used a laser beam to heat the center of a portion of graphene, then measured the temperature difference from the middle of the graphene to the edge. Cho's theory helped explain their findings.

"We refined our modeling work taking into account their experimental conditions and found we have quantitative agreement," Cho said. "By understanding how heat transfers through a two-dimensional graphene system, we can further manipulate its use in semiconductor devices used in everyday life." For this purpose, Cho and Zhang are preparing a follow-up article on how to control the thermal conductivity in graphene.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted from materials provided by University of Texas, Dallas, via Newswise.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Theory explains how new material could improve electronic shelf life

ScienceDaily (Jan. 9, 2012) — Research by UT Dallas engineers could lead to more-efficient cooling of electronics, producing quieter and longer-lasting computers, and cellphones and other devices.

Much of modern technology is based on silicon's use as a semiconductor material, but research recently published in the journal Nature Materials shows that graphene conducts heat about 20 times faster than silicon.

"Heat is generated every time a device computes," said "Dr. Kyeongjae "KJ" Cho, associate professor of materials science and engineering and physics at UT Dallas and one of the paper's authors. "For example a laptop fan pumps heat out of the system, but heat removal starts with a chip on the inside. Engineered graphene could be used to remove heat -- fast."

It was demonstrated in 2004 that graphite could be changed into a sheet of bonded carbon atoms called graphene, which is believed to be the strongest material ever measured. Although much research has focused on the strength and electronics of the material, Cho has been studying its thermal conductivity.

As electronics become more complex and decrease in size, the challenge to remove heat from the core becomes more difficult, he said. Desktop and laptop computers have fans.

Smaller electronic devices such as cellphones have other thermoelectric cooling devices.

"The performance of an electronic device degrades as it heats up, and if it continues the device fails," said Cho, also a visiting professor at Seoul National University in South Korea.

"The faster heat is removed, the more efficient the device runs and the longer it lasts."

Research assistant Hengji Zhang of UT Dallas is also an author of the paper. Cho and Zhang have published prior papers in the Journal of Nanomaterials and Physical Review B about graphene's thermal conductivity. For the Nature Materials paper, researchers at UT Austin conducted an experiment about graphene's heat transfer. They used a laser beam to heat the center of a portion of graphene, then measured the temperature difference from the middle of the graphene to the edge. Cho's theory helped explain their findings.

"We refined our modeling work taking into account their experimental conditions and found we have quantitative agreement," Cho said. "By understanding how heat transfers through a two-dimensional graphene system, we can further manipulate its use in semiconductor devices used in everyday life." For this purpose, Cho and Zhang are preparing a follow-up article on how to control the thermal conductivity in graphene.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted from materials provided by University of Texas, Dallas, via Newswise.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Nano research could impact flexible electronic devices

ScienceDaily (Jan. 12, 2012) — A discovery by a research team at North Dakota State University, Fargo, and the National Institute of Standards and Technology (NIST), shows that the flexibility and durability of carbon nanotube films and coatings are intimately linked to their electronic properties. The research could one day impact flexible electronic devices such as solar cells and wearable sensors. The research also provided a promising young high school student the chance to work in the lab with world-class scientists, jumpstarting her potential scientific career.

The NDSU/NIST research team, led by Erik Hobbie, Ph.D., is working to determine why thin films made from metallic single-wall carbon nanotubes are superior for potential applications that demand both electronic performance and mechanical durability. "One simple reason is that the metallic nanotubes tend to transport charge more easily when they touch each other," said Hobbie. "But another less obvious reason has to do with how much the films can flex without changing their structure at very small scales."

Results from the study are published in ACS Nano.

The team includes NDSU graduate student John M. Harris; postdoctoral researcher Ganjigunte R. Swathi Iyer; Anna K. Bernhardt, North Dakota Governor's School attendee; and NIST researchers Ji Yeon Huh, Steven D. Hudson and Jeffrey A. Fagan.

There is great interest in using carbon nanotube films and coatings as flexible transparent electrodes in electronic devices such as solar cells. "Our research demonstrates that the flexibility and durability of these films are intimately linked to their electronic properties," said Hobbie. "This is a very new idea, so hopefully, it will generate a new series of studies and questions focused on the exact origins and consequences of this effect."

Such research could potentially result in material that reduces solar cell costs, and leads to the ability to use them in clothing or foldable electronics. Electronic devices currently on the market that require transparent electrodes, like touch screens and solar cells, typically use indium tin oxide, an increasingly expensive material. "It is also very brittle," said Hobbie, "implying that it cannot be used in devices that require mechanical flexibility like wearable or foldable electronics."

Single-wall carbon nanotubes show significant promise as transparent conductive coatings with outstanding electronic, mechanical and optical properties. "A particularly attractive feature of these films is that the physical properties can be tuned through the addition or subtraction of a relatively small number of nanotubes," said Hobbie. "Thin films made from such materials hold tremendous potential for flexible electronics applications, including the replacement of indium tin oxide in liquid crystal displays and photovoltaic devices."

Thin films made from metallic single-wall carbon nanotubes show better durability as flexible transparent conductive coatings, which the researchers attribute to a combination of superior mechanical performance and higher interfacial conductivity. The research team found significant differences in the electronic manifestations of thin-film wrinkling, depending on the electronic type of the nanotubes, and examined the underlying mechanisms.

The results of this study suggest that the metallic films make better flexible transparent conductive coatings; they have higher conductivity and are more durable. "Our results are relevant to a number of ongoing efforts in transparent conducting films and flexible electronic devices," said Hobbie.

The research was supported by the National Science Foundation through CMMI-0969155 and the U.S. Department of Energy through DE-FB36-08GO88160.

The opportunity to work on such research was new to Anna Bernhardt, a high school junior from a town of 1,000 people in western North Dakota. She was among 66 of the most academically driven high school sophomores and juniors who attended a six-week intensive summer residential program on the NDSU campus for scholastically motivated students in the state.

Students receive concentrated instruction from 40 NDSU faculty through discussion groups, labs, field trips and other activities. The state of North Dakota funds the cost of participation for North Dakota students who are accepted into the program. It's available free to public school students, while private and homeschool students selected for the program can make arrangements to attend for free through their local public school district.

While it is unusual for a young student to be involved in nanotechnology research at this level, it presented an opportunity for everyone involved. Bernhardt prepared single-wall carbon nanotube samples and participated in testing of the samples. "The experience of working in a research setting has helped me to decide that I would love to do more research in the future," said the young scientist. "The biggest benefit of working in the lab was getting a taste of the true research experience. Without North Dakota's Governor's School, I would never have been able to have this experience and surely wouldn't be so certain that I would like to do more research in the future."

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted from materials provided by North Dakota State University, via Newswise.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

John M. Harris, Ganjigunte R. Swathi Iyer, Anna K. Bernhardt, Ji Yeon Huh, Steven D. Hudson, Jeffrey A. Fagan, Erik K. Hobbie. Electronic Durability of Flexible Transparent Films from Type-Specific Single-Wall Carbon Nanotubes. ACS Nano, 2011; 111220100417004 DOI: 10.1021/nn204383t

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Subtle electronic effect in magnetite discovered: Long-standing puzzle in study of magnetism finally solved

ScienceDaily (Dec. 21, 2011) — A fundamental problem that has long puzzled scientists has been solved after more than 70 years. An international team of researchers has discovered a subtle electronic effect in magnetite, the most magnetic of all naturally occurring minerals. The effect causes a dramatic change to how this material conducts electricity at very low temperatures.

The discovery gives new insight into the mineral in which magnetism was discovered, and it may enable magnetite and similar materials to be exploited in new ways.

Ancient knowledge

Magnetite's properties have been known for more than 2000 years and gave rise to the original concepts of magnets and magnetism. The mineral has formed the basis for decades of research into magnetic recording and information storage materials.

The research was led by the University in collaboration with the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, where the experiments were conducted. Their results were published in Nature.

Unexplained behaviour

In 1939, Dutch scientist Evert Verwey discovered that the electrical conductivity of magnetite decreases abruptly and dramatically at low temperatures. At about 125 Kelvin, or minus 150 degrees Celsius, the metallic mineral turns into an insulator.

Despite many efforts, until now the reason for this transition has been debated and remained controversial.

X-ray experiment

The team of scientists fired an intense X-ray beam at a tiny crystal of magnetite at very low temperatures. Their results enabled them to understand a subtle rearrangement of the mineral's chemical structure. Electrons are trapped within groups of three iron atoms, where they can no longer transport an electrical current.

"We have solved a fundamental problem in understanding the original magnetic material, upon which everything we know about magnetism is built," said Professor Paul Attfield, Centre for Science at Extreme Conditions. "This vital insight into how magnetite is constructed and how it behaves will help in the development of future electronic and magnetic technologies."

The research was funded by the Science and Technology Facilities Council, the Engineering and Physical Sciences Research Council, and the Leverhulme Trust.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted from materials provided by University of Edinburgh.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal References:

Mark S. Senn, Jon P. Wright, J. Paul Attfield. Charge order and three-site distortions in the Verwey structure of magnetite. Nature, 2011; DOI: 10.1038/nature10704J. Paul Attfield. Condensed-matter physics: A fresh twist on shrinking materials. Nature, 2011; 480 (7378): 465 DOI: 10.1038/480465a

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

One of the world's smallest electronic circuits created

A team of scientists, led by Guillaume Gervais from McGill's Physics Department and Mike Lilly from Sandia National Laboratories, has engineered one of the world's smallest electronic circuits. It is formed by two wires separated by only about 150 atoms or 15 nanometers (nm). This discovery, published in the journal Nature Nanotechnology, could have a significant effect on the speed and power of the ever smaller integrated circuits of the future in everything from smartphones to desktop computers, televisions and GPS systems.

This is the first time that anyone has studied how the wires in an electronic circuit interact with one another when packed so tightly together. Surprisingly, the authors found that the effect of one wire on the other can be either positive or negative. This means that a current in one wire can produce a current in the other one that is either in the same or the opposite direction. This discovery, based on the principles of quantum physics, suggests a need to revise our understanding of how even the simplest electronic circuits behave at the nanoscale

In addition to the effect on the speed and efficiency of future electronic circuits, this discovery could also help to solve one of the major challenges facing future computer design. This is managing the ever-increasing amount of heat produced by integrated circuits. Well-known theorist Markus Büttiker speculates that it may be possible to harness the energy lost as heat in one wire by using other wires nearby. Moreover, Buttiker believes that these findings will have an impact on the future of both fundamental and applied research in nanoelectronics.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted from materials provided by McGill University.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

D. Laroche, G. Gervais, M. P. Lilly, J. L. Reno. Positive and negative Coulomb drag in vertically integrated one-dimensional quantum wires. Nature Nanotechnology, 2011; 6 (12): 793 DOI: 10.1038/nnano.2011.182

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

'Graphene earns its stripes': New nanoscale electronic state discovered on graphene sheets

Researchers from the London Centre for Nanotechnology (LCN) have discovered electronic stripes, called 'charge density waves', on the surface of the graphene sheets that make up a graphitic superconductor. This is the first time these stripes have been seen on graphene, and the finding is likely to have profound implications for the exploitation of this recently discovered material, which scientists believe will play a key role in the future of nanotechnology. The discovery is reported in Nature Communications, 29th November.

Graphene is a material made up of a single sheet of carbon atoms just one atom thick, and is found in the marks made by a graphite pencil. Graphene has remarkable physical properties and therefore has great technological potential, for example, in transparent electrodes for flat screen TVs, in fast energy-efficient transistors, and in ultra-strong composite materials. Scientists are now devoting huge efforts to understand and control the properties of this material.

The LCN team donated extra electrons to a graphene surface by sliding calcium metal atoms underneath it. One would normally expect these additional electrons to spread out evenly on the graphene surface, just as oil spreads out on water. But by using an instrument known as a scanning tunneling microscope, which can image individual atoms, the researchers have found that the extra electrons arrange themselves spontaneously into nanometer-scale stripes. This unexpected behavior demonstrates that the electrons can have a life of their own which is not connected directly to the underlying atoms. The results inspire many new directions for both science and technology. For example, they suggest a new method for manipulating and encoding information, where binary zeros and ones correspond to stripes running from north to south and running from east to west respectively.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted from materials provided by University College London - UCL, via AlphaGalileo.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

K.C. Rahnejat, C.A. Howard, N.E. Shuttleworth, S.R. Schofield, K. Iwaya, C.F. Hirjibehedin, Ch. Renner, G. Aeppli, M. Ellerby. Charge density waves in the graphene sheets of the superconductor CaC6. Nature Communications, 2011; 2: 558 DOI: 10.1038/ncomms1574

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Electronic Devices In 3D

There are so many different kinds of electronic devices, it seems like every time you turn around there is something that is a new, must have device. The worst offender of them all are the cell phone manufacturers and cell phone providers. It is like they just want you to have to buy their new model phone every time your contract is up. Nobody just puts all of the good ideas into one phone and then stops; they are always looking for the next thing to cram into the tiny device.

At least the trend of making phones smaller and smaller is over. Grown men can use the devices without fear of dropping them or not being able to use them because they were getting so tiny. They were getting so small, mine kept getting lost in my pocket. But the bigger point is that technology doesn't ever stop and every year there are so many innovations and improvements, it can be difficult for a non technophile to keep up with it all.

One of the newest craze that the providers are trying to push on us is 3D. You see 3D at the movies and on your televisions at home and even on your gaming systems. Now there is 3D on your phone. You read that correctly, 3D on your phone. It may not have seemed necessary, and maybe it isn't, but was 3D on your television really needed? Was a triple-decker cheeseburger really necessary? Are giant tire on a 4x4 so that it can crush other, smaller cars necessary? Of course not, but along with a triple cheeseburger and monster trucks, a 3D phone is just plain awesome.

Why have 3D phones? Because you can, that's why. Not only can you watch certain 3D enabled video, you can take 3D photos as well. Imagine going on your family vacation and being able to whip out your phone and take cool 3D pictures for your digital scrapbook. Imagine being at the beach and getting that perfect shot of the kids playing in the water-IN 3D!

Imagine taking a photo of your girlfriend riding an awesome roller coaster-IN 3D! The point is that it literally adds another dimension to you photos and video that you can watch on your phone without the need for special 3D glasses. The technology is evolving so quickly, and 3D might be a fad, but you have to admit-it is pretty awesome.

If you are looking for for HDMI cables you can find some of the best quality and prices by logging onto Selby acoustic at selbyacoustics.com.au.

View the original article here

New X-ray technique for electronic structures: Ability to probe deep below material surfaces should be boon for nanoscale devices

ScienceDaily (Aug. 26, 2011) — The expression "beauty's only skin-deep" has often been applied to the chemistry of materials because so much action takes place at the surface. However, for many of the materials in today's high technologies, such as semiconductors and superconductors, once a device is fabricated it is the electronic structures below the surface, in the bulk of the material or in buried layers, that determine its effectiveness. For the past 30 years, one of the most valuable and widely used techniques for studying electronic structures has been ARPES -- Angle-Resolved PhotoEmission Spectroscopy. However, this technique primarily looks at surfaces.

Now, for the first time, bulk electronic structures have been opened to comparable scrutiny through a new variation of this standard called HARPES -- Hard x-ray Angle-Resolved PhotoEmission Spectroscopy -- whose development was led by researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab).

"HARPES should enable us to study the electronic structure of any new material in the bulk, with minimum effects of surface reactions or contamination," says physicist Charles Fadley who led the development of HARPES. "Our technique should also allow us to probe the buried layers and interfaces that are ubiquitous in nanoscale devices, and are key to smaller logic elements in electronics, novel memory architectures in spintronics, and more efficient energy conversion in such technologies as photovoltaic cells."

Fadley is a physicist who holds joint appointments with Berkeley Lab's Materials Sciences Division and the University of California (UC) Davis where he is a Distinguished Professor of Physics. He is also one of the world's foremost practitioners of photoelectron spectroscopy, a technique based on the photoelectric effect described in 1905 by Albert Einstein. When a beam of photons -- particles of light such as x-rays -- is flashed on a sample, energy is transferred from the photons to electrons, causing them to be emitted from the sample. By measuring the kinetic energy of these emitted photoelectrons and the angles at which they are ejected, scientists can learn much about the sample's electronic structure.

The successful demonstration of the HARPES technique has been reported in the journal Nature Materials in a paper titled "Probing bulk electronic structure with hard X-ray angle-resolved photoemission." Fadley was the senior author of this paper. The lead and corresponding author was Alexander Gray, a member of Fadley's UC Davis research group and also an affiliate with Berkeley Lab's Materials Sciences Division.

"The key to probing the bulk electronic structure is using hard x-rays, which are x-rays with sufficiently high photon energies to eject photoelectrons from deep beneath the surface of a solid material," Gray says. "High-energy photons impart high kinetic energies to the ejected photoelectrons, enabling them to travel longer distances within the solid. The result is that more of the signal originating from the bulk will be detected by the analyzer."

Whereas the typical ARPES experiment, using low energy or "soft" x-rays (10~100 eV photons), probes to a depth of less than 10 angstroms (a few layers of atoms), with their HARPES technique Fadley and Gray and their colleagues on this project were able to probe as deep as 60 Angstroms into the bulk of single crystals of tungsten and gallium-arsenide. Their achievement was made possible by a combination of third generation light sources capable of producing intense beams of hard x-rays, and an advanced electron spectrometer to measure energies and angles.

"While high-energy photons are needed to penetrate into the bulk, at high energies the photoemission intensity that carries information about the electronic band structure is drastically reduced by various factors, such as phonon effects and small photoelectric cross sections of the valence-band electron orbitals," Gray says. "However, HARPES measurements become possible with the advent of the third-generation synchrotron light sources and the development of hard x-ray monochromators and optics capable of focusing a highly intense x-ray beam into a very small measurement spot."

To demonstrate the capabilities of their HARPES technique, Fadley and Gray used a high intensity undulator beamline at the SPring8 synchrotron radiation facility in Hyogo, Japan, which is operated by the Japanese National Institute for Materials Sciences. The samples they worked with, tungsten and gallium arsenide, contain relatively heavy elements that have relatively small phonon effects (atomic vibrations) but to further reduce these effects the samples were cryo-cooled. By combining room temperature and cryo data, the researchers were able to correct for the influence of indirect transitions and photoelectron diffraction in their results.

"Having sufficient photons from the beamline was critical as was having a high energy resolution that required an undulator source and a special monochromator and a photoelectron spectrometer with both high throughput for intensity and a lens with angle-resolving capability," Fadley says.

Adds Gray, "Our HARPES technique not only provided us with information about the energies of the emitted photoelectrons, but also with information about the crystal momentum of electrons within the bulk solid. This extra dimension carries a vast amount of information regarding electronic, magnetic and structural properties of materials, and can be used for in-depth studies of such novel phenomena as high-temperature superconductivity and so-called Mott transitions from insulating to conducting states that might be used for logic switching in the future."

In the future, Fadley and Gray will be able to carry out HARPES experiments much closer to home. At Berkeley Lab's Advanced Light Source (ALS), the first of the world's third generation synchrotron radiation facilities, a new experimental chamber for beamline 9.3.1 is scheduled to open this fall that will provide unique hard x-ray angle-resolved photoemission capabilities.

Says Zahid Hussain, who manages the ALS Scientific Support group, "An additional hard x-ray photoemission spectroscopy chamber at beamline 9.3.1 will feature an ambient pressure high energy photoemission capability that will allow the study of energy related problems, such as batteries, fuel cells, and catalysis under in-situ and in-operando conditions. It will also enable depth-sensitive studies and make it possible to probe not only solid, but also gas and liquid interfaces. This will be the first such experimental facility in the world."

Co-authoring the Nature Materials paper with Fadley and Gray were Christian Papp, Shigenori Ueda, Benjamin Balke, Yoshiyuki Yamashita, Lukasz Plucinski, Jan Minár, Juergen Braun, Erik Ylvisaker, Claus Schneider, Warren Pickett, Hubert Ebert and Keisuke Kobayashi.

This research was supported in part by the DOE Office of Science.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by DOE/Lawrence Berkeley National Laboratory.

Journal Reference:

A. X. Gray, C. Papp, S. Ueda, B. Balke, Y. Yamashita, L. Plucinski, J. Minár, J. Braun, E. R. Ylvisaker, C. M. Schneider, W. E. Pickett, H. Ebert, K. Kobayashi, C. S. Fadley. Probing bulk electronic structure with hard X-ray angle-resolved photoemission. Nature Materials, 2011; DOI: 10.1038/nmat3089

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

'Smelling' heart failure: Evaluation of an electronic nose

ScienceDaily (Aug. 29, 2011) — A German team has developed a completely new non-invasive method to identify heart failure. It consists of an "electronic nose" which could make the "smelling" of heart failure possible.

The project was presented at the European Society of Cardiology Congress 2011.

"The early detection of chronic heart failure (CHF) through periodical screening facilitates early treatment application," said investigator Vasileios Kechagias from the University Hospital Jena.

Heart failure is a common, costly, disabling and potentially deadly condition. In developed countries, around 2% of adults suffer from heart failure, but in those over the age of 65, this increases to 6-10%. Mostly due to costs of hospitalisation, it is associated with high health expenditure. Heart failure is associated with significantly reduced physical and mental health, resulting in a markedly decreased quality of life. Although some people survive many years, progressive disease is associated with an overall increased mortality and morbidity.

"We conducted a daily screening of patients with different degrees of heart failure. For the study, eligible patients were enrolled after informed consent, and the collected data was anonymous. Measurements were made in collaboration with the University of Applied Sciences, Jena. The participating physicians of the Department of Internal Medicine I, University Hospital of Jena, were responsible for patient recruitment and analysis of clinical data," explained Kechagias.

In particular, the relevant laboratory parameters for heart failure (BNP, minerals, creatinine, blood gas analysis) were collected and a clinical assessment of heart failure based on the available parameters (clinical history, laboratory, echocardiography, and exercise stress test) was performed. In 2010, the researchers screened a total of 250 patients and included 126 in the clinical study. In the course of the study, testing was optimized through a standardized skin preparation.

The assignment of patients to the different groups (no heart failure vs. moderate heart failure vs. decompensated heart failure) was performed by physicians blinded for the measured values through the electronic nose.

Two groups were formed with CHF patients: one with decompensated (n=27) heart failure and one with compensated (n=25) heart failure. For the clinical manifestation of the decompensated heart failure, investigators evaluated the marked limitation of any activity where the patient is comfortable only at rest (Class III) or the state in which any physical activity brings on discomfort and symptoms occur at rest (Class IV). Furthermore, they screened a control group of patients without heart failure symptoms (n=28). Then the measurement with the "electronic nose" randomly took place, from 10 cycles of 3 minutes each and a subsequent offline data analysis.

The "electronic nose" system consists of an array of three thick-film metal oxide based gas sensors with heater elements. Each of the sensors had a slightly different sensitivity to various odorant molecular types. Interactions between molecules and the sensor were caused by reactions with oxygen on the heated sensor surface leading to a change of the free charge carrier concentrations and thus to a change in conductivity in the metal oxide layer. The odour components were divided by a statistical analysis into two principal components.

In all patients, data acquisition was possible. The patients with decompensated heart failure could be divided from compensated heart failure with 89% sensitivity and 88% specificity. Cardiovascular drug use was not different in these groups. On the other hand, patients without heart failure (control group) were different from the patients with heart failure in the principal-component analysis (89% sensitivity and 84% specificity).

Further work is in progress to identify the responsible components.

The researchers' primary objective is to create and establish a minimal invasive method, which will help to rapidly screen, diagnose, group and monitor the CHF.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by European Society of Cardiology, via EurekAlert!, a service of AAAS.

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Sketching with superconductors: Breakthrough in controlling defects could lead to new generation of electronic devices

ScienceDaily (Aug. 22, 2011) — Reporting in the journal Nature Materials, researchers from the London Centre for Nanotechnology and the Physics Department of Sapienza University of Rome have discovered a technique to 'draw' superconducting shapes using an X-ray beam. This ability to create and control tiny superconducting structures has implications for a completely new generation of electronic devices.

Superconductivity is a special state where a material conducts electricity with no resistance, meaning absolutely zero energy is wasted.

The research group has shown that they can manipulate regions of high temperature superconductivity, in a particular material which combines oxygen, copper and a heavier, 'rare earth' element called lanthanum. Illuminating with X-rays causes a small scale re-arrangement of the oxygen atoms in the material, resulting in high temperature superconductivity, of the type originally discovered for such materials 25 years ago by IBM scientists. The X-ray beam is then used like a pen to draw shapes in two dimensions.

A well as being able to write superconductors with dimensions much smaller than the width of a human hair, the group is able to erase those structures by applying heat treatments. They now have the tools to write and erase with high precision, using just a few simple steps and without the chemicals ordinarily used in device fabrication. This ability to re-arrange the underlying structure of a material has wider applications to similar compounds containing metal atoms and oxygen, ranging from fuel cells to catalysts.

Prof. Aeppli, Director of the London Centre for Nanotechnology and the UCL investigator on the project, said: "Our validation of a one-step, chemical-free technique to generate superconductors opens up exciting new possibilities for electronic devices, particularly in re-writing superconducting logic circuits. Of profound importance is the key to solving the notorious 'travelling salesman problem', which underlies many of the world's great computational challenges. We want to create computers on demand to solve this problem, with applications from genetics to logistics. A discovery like this means a paradigm shift in computing technology is one step closer."

Prof Bianconi, the leader of the team from Sapienza, added: "It is amazing that in a few simple steps, we can now add superconducting 'intelligence' directly to a material consisting mainly of the common elements copper and oxygen."

The X-ray experiments were performed at the Elettra (Trieste) synchrotron radiation facility. The work is published in Nature Materials , 21 August 2011 (doi:1038/nmat3088) and follows on from previous discovery of fractal-like structures in superconductors (doi:10.1038/nature09260).

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University College London.

Journal References:

Nicola Poccia, Michela Fratini, Alessandro Ricci, Gaetano Campi, Luisa Barba, Alessandra Vittorini-Orgeas, Ginestra Bianconi, Gabriel Aeppli, Antonio Bianconi. Evolution and control of oxygen order in a cuprate superconductor. Nature Materials, 2011; DOI: 10.1038/nmat3088Michela Fratini, Nicola Poccia, Alessandro Ricci, Gaetano Campi, Manfred Burghammer, Gabriel Aeppli, Antonio Bianconi. Scale-free structural organization of oxygen interstitials in La2CuO4+y. Nature, 2010; 466 (7308): 841 DOI: 10.1038/nature09260

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Understanding next-generation electronic devices: Smallest atomic displacements ever

ScienceDaily (Sep. 3, 2011) — An international team of scientists has developed a novel X-ray technique for imaging atomic displacements in materials with unprecedented accuracy. They have applied their technique to determine how a recently discovered class of exotic materials -- multiferroics -- can be simultaneously both magnetically and electrically ordered. Multiferroics are also candidate materials for new classes of electronic devices.

The discovery, a major breakthrough in understanding multiferroics, is published in Science dated 2 September 2011.

The authors comprise scientists from the European Synchrotron Radiation Facility (ESRF) in Grenoble (France), the University of Oxford and the University College London (both UK). Helen Walker from the ESRF is the main author of the publication.

Everybody is familiar with the idea that magnets are polarized with a north and a south pole, which is understood to arise from the alignment of magnet moments carried by atoms in magnetic materials. Certain other materials, known as ferroelectrics, exhibit a similar effect for electrical polarisation. The exotic "multiferroic" materials combine both magnetic and ferroelectric polarizations, and can exhibit a strong coupling between the two phenomena.

This leads to the strange effect that a magnetic field can electrically polarise the material, and an electric field magnetise it. A class of strong multiferroics was discovered ten years ago and has since led to a new, rapidly growing field of research, also motivated by the promise of their exotic properties for new electronic devices. One example is a new type of electronic memory, in which an electric field writes data into the memory and a magnetic detector is used to read it. This process is faster, and uses less energy than today's hard disk drives.

However, the origin of the electric polarisation in multiferroics remained mostly elusive to date. The team's work unambiguously shows that the polarization in the multiferroic studied proceeds from the relative displacement of charges of different signs, rather than the transfer of charge from one atom to another.

As the displacement involves a high number of electrons, even small distances can lead to significant polarisation. The actual distance of the displacement still came as a surprise: about 20 femtometres, or about 1/100,000th of the distance between the atoms in the material. Measuring such small displacements was actually believed to be impossible.

"I think that everyone involved was surprised, if not staggered, by the result that we can now image the position of atoms with such accuracy. The work is testament to the fantastic facilities available in Grenoble to the UK science community," says Prof. Des McMorrow, Deputy Director of the London Centre for Nanotechnology, leader of the UCL part of the project.

Walker and her colleagues developed a smart new experimental technique exploiting the interference between two competing processes: charge and magnetic scattering of a powerful, polarized X-ray beam. They studied a single crystal of TbMnO3 which shows a strong multiferroic coupling at temperatures below 30K, and were able to measure the displacements of specific atoms within it with an accuracy approaching one femtometre (10-15m). The atoms themselves are spaced apart 100,000 times this distance.

The new interference scattering technique has set a world record for accuracy in absolute measurements of atomic displacements. (It is also the first measurement of magnetostriction in antiferromagnets.) Most significantly the identification of the origin of ferroelectricty in a multiferroic material is a major step forward in the design of multiferroics for practical applications.

"By revealing the driving mechanism behind multiferroics, which offer so many potential applications, it underlines how experiments designed to understand the fundamental physics of materials can have an impact on the wider world," concludes Dr. Helen Walker who led the work at the ESRF.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by European Synchrotron Radiation Facility, via EurekAlert!, a service of AAAS.

Journal Reference:

H. C. Walker, F. Fabrizi, L. Paolasini, F. De Bergevin, J. Herrero-Martin, A. T. Boothroyd, D. Prabhakaran, D. F. Mcmorrow. Femtoscale Magnetically Induced Lattice Distortions in Multiferroic TbMnO3. Science, 2 September 2011: Vol. 333 no. 6047 pp. 1273-1276 DOI: 10.1126/science.1208085

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here