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State Shifting Graphite enters different states of matter in ultrafast experiment

Graphite enters different states of matter in ultrafast experiment

For the first time, scientists have seen an X-ray-irradiated mineral go to two different states of matter in about 40 femtoseconds (a femtosecond is one quadrillionth of a second).

Using the Linac Coherent Light Source (LCLS) X-ray Free-Electron Laser (XFEL) at SLAC National Accelerator Laboratory at Stanford, Stefan Hau-Riege of Lawrence Livermore National Laboratory and colleagues heated graphite to induce a transition from solid to liquid and to warm-dense plasma.

Ultrafast phase transitions from solid to liquid and plasma states are important in the development of new material-synthesis techniques, in ultrafast imaging, and high-energy density science.

By using different pulse lengths and calculating different spectra, the team was able to extract the time dependence of plasma parameters, such as electron and ion temperatures and ionization states.

“We found that the heating and disintegration of the ion lattice occurs much faster than anticipated,” Hau-Riege said.

The research provides new insights into the behavior of matter irradiated by intense hard X-rays. Though the study ultimately serves as a breakthrough in plasma physics and ultrafast materials science, it also affects other fields such as single molecule biological imaging and X-ray optics.

For single-molecule bioimaging, the team found that in certain cases it may be substantially more difficult than anticipated because energy transfer is surprisingly fast. In X-ray optics, they found that the damage threshold is lower than anticipated.

This is the first XFEL high-energy density science experiment that used inelastic X-ray scattering as a plasma diagnostic.

In addition to SLAC National Accelerator Laboratory, participating institutions include Universitat Duisburg-Essen; Max Planck Advanced Study Group, Center for Free Electron Laser Science; Max Planck Institut fur medizinische Forschung; and Max Planck Institut fur Kernphysik, all of Germany.

Ref.: Forthcoming in May 21 edition of Physical Review Letters.

In Solar Cells, Tweaking the Tiniest of Parts -Quantum dots Yields Big Jump in Efficiency

Company led by university researchers employs charged quantum dots to increase the efficiency of solar cell technology

-- Researchers from the University at Buffalo, Army Research Laboratory and Air Force Office of Scientific Research have developed a new, nanomaterials-based technology that has the potential to increase the efficiency of photovoltaic cells up to 45 percent.

-- Specifically, the researchers have shown that embedding charged quantum dots into solar cells can improve electrical output by enabling the cells to harvest infrared light, and by increasing the lifetime of photoelectrons. The technology can be applied to many different photovoltaic structures.

-- A new company the researchers founded, OPtoElectronic Nanodevices LLC. (OPEN LLC), is commercializing this technology.

BUFFALO, N.Y. -- By tweaking the smallest of parts, a trio of University at Buffalo engineers is hoping to dramatically increase the amount of sunlight that solar cells convert into electricity.

With military colleagues, the UB researchers have shown that embedding charged quantum dots into photovoltaic cells can improve electrical output by enabling the cells to harvest infrared light, and by increasing the lifetime of photoelectrons.

The research appeared online last May in the journal Nano Letters. The research team included Vladimir Mitin, Andrei Sergeev and Nizami Vagidov, faculty members in UB's electrical engineering department; Kitt Reinhardt of the Air Force Office of Scientific Research; and John Little and advanced nanofabrication expert Kimberly Sablon of the U.S. Army Research Laboratory.

Mitin, Sergeev and Vagidov have founded a company, OPtoElectronic Nanodevices LLC. (OPEN LLC.), to bring the innovation to the market.

The idea of embedding quantum dots into solar panels is not new: According to Mitin, scientists had proposed about a decade ago that this technique could improve efficiency by allowing panels to harvest invisible, infrared light in addition to visible light. However, intensive efforts in this direction have previously met with limited success.

The UB researchers and their colleagues have not only successfully used embedded quantum dots to harvest infrared light; they have taken the technology a step further, employing selective doping so that quantum dots within the solar cell have a significant built-in charge.

This built-in charge is beneficial because it repels electrons, forcing them to travel around the quantum dots. Otherwise, the quantum dots create a channel of recombination for electrons, in essence "capturing" moving electrons and preventing them from contributing to electric current.

The technology has the potential to increase the efficiency of solar cells up to 45 percent, said Mitin, a SUNY Distinguished Professor. Through UB's Office of Science, Technology Transfer and Economic Outreach (STOR), he and his colleagues have filed provisional patent applications to protect their technology.

"Clean technology will really benefit the region, the state, the country," Mitin said. "With high-efficiency solar cells, consumers can save money and providers can have a smaller solar field that produces more energy."

Mitin and his colleagues have already invested significant amounts of time in developing the quantum dots with a built-in-charge, dubbed "Q-BICs." To further enhance the technology and bring it to the market, OPEN LLC is now seeking funding from private investors and federal programs.

The University at Buffalo is a premier research-intensive public university, a flagship institution in the State University of New York system and its largest and most comprehensive campus. UB's more than 28,000 students pursue their academic interests through more than 300 undergraduate, graduate and professional degree programs. Founded in 1846, the University at Buffalo is a member of the Association of American Universities.

Related Stories:

Vladimir Mitin Among Three UB Faculty Members Named SUNY Distinguished Professors: http://www.buffalo.edu/news/9243

Microscale device made from graphene metamaterials-one atom thick

A whole new light on graphene metamaterials

Berkeley Lab scientists demonstrate a tunable graphene device, the first tool in a kit for putting terahertz light to work

		IMAGE: The graphene microribbon array can be tuned in three ways. Varying the width of the ribbons changes plasmon resonant frequency and absorbs corresponding frequencies of terahertz light. Plasmon response is... Click here for more information.

Long-wavelength terahertz light is invisible – it's at the farthest end of the far infrared – but it's useful for everything from detecting explosives at the airport to designing drugs to diagnosing skin cancer. Now, for the first time, scientists at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley have demonstrated a microscale device made of graphene – the remarkable form of carbon that's only one atom thick – whose strong response to light at terahertz frequencies can be tuned with exquisite precision.

"The heart of our device is an array made of graphene ribbons only millionths of a meter wide," says Feng Wang of Berkeley Lab's Materials Sciences Division, who is also an assistant professor of physics at UC Berkeley, and who led the research team. "By varying the width of the ribbons and the concentration of charge carriers in them, we can control the collective oscillations of electrons in the microribbons."

The name for such collective oscillations of electrons is "plasmons," a word that sounds abstruse but describes effects as familiar as the glowing colors in stained-glass windows.

"Plasmons in high-frequency visible light happen in three-dimensional metal nanostructures," Wang says. The colors of medieval stained glass, for example, result from oscillating collections of electrons on the surfaces of nanoparticles of gold, copper, and other metals, and depend on their size and shape. "But graphene is only one atom thick, and its electrons move in only two dimensions. In 2D systems, plasmons occur at much lower frequencies."

		IMAGE: At a constant carrier density, varying the width of the graphene ribbons -- from 1 micrometer (millionth of a meter) to 4 micrometers -- changes the plasmon resonant frequency from... Click here for more information.

The wavelength of terahertz radiation is measured in hundreds of micrometers (millionths of a meter), yet the width of the graphene ribbons in the experimental device is only one to four micrometers each.

"A material that consists of structures with dimensions much smaller than the relevant wavelength, and which exhibits optical properties distinctly different from the bulk material, is called a metamaterial," says Wang. "So we have not only made the first studies of light and plasmon coupling in graphene, we've also created a prototype for future graphene-based metamaterials in the terahertz range."

The team reports their research in Nature Nanotechnology, available in advanced online publication.

How to push the plasmons

In two-dimensional graphene, electrons have a tiny rest mass and respond quickly to electric fields. A plasmon describes the collective oscillation of many electrons, and its frequency depends on how rapidly waves in this electron sea slosh back and forth between the edges of a graphene microribbon. When light of the same frequency is applied, the result is "resonant excitation," a marked increase in the strength of the oscillation – and simultaneous strong absorption of the light at that frequency. Since the frequency of the oscillations is determined by the width of the ribbons, varying their width can tune the system to absorb different frequencies of light.

The strength of the light-plasmon coupling can also be affected by the concentration of charge carriers – electrons and their positively charged counterparts, holes. One remarkable characteristic of graphene is that the concentration of its charge carriers can easily be increased or decreased simply by applying a strong electric field – so-called electrostatic doping.

The Berkeley device incorporates both these methods for tuning the response to terahertz light. Microribbon arrays were made by depositing an atom-thick layer of carbon on a sheet of copper, then transferring the graphene layer to a silicon-oxide substrate and etching ribbon patterns into it. An ion gel with contact points for varying the voltage was placed on top of the graphene.

The gated graphene microarray was illuminated with terahertz radiation at beamline 1.4 of Berkeley Lab's Advanced Light Source, and transmission measurements were made with the beamline's infrared spectrometer. In this way the research team demonstrated coupling between light and plasmons that were stronger by an order of magnitude than in other 2D systems.

A final method of controlling plasmon strength and terahertz absorption depends on polarization. Light shining in the same direction as the graphene ribbons shows no variations in absorption according to frequency. But light at right angles to the ribbons – the same orientation as the oscillating electron sea – yields sharp absorption peaks. What's more, light absorption in conventional 2D semiconductor systems, such as quantum wells, can only be measured at temperatures near absolute zero. The Berkeley team measured prominent absorption peaks at room temperature.

"Terahertz radiation covers a spectral range that's difficult to work with, because until now there have been no tools," says Wang. "Now we have the beginnings of a toolset for working in this range, potentially leading to a variety of graphene-based terahertz metamaterials."

The Berkeley experimental setup is only a precursor of devices to come, which will be able to control the polarization and modify the intensity of terahertz light and enable other optical and electronic components, in applications from medical imaging to astronomy – all in two dimensions.

 

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"Graphene plasmonics for tunable terahertz metamaterials," by Long Ju, Baisong Geng, Jason Horng, Caglar Girit, Michael Martin, Zhao Hao, Hans A. Bechtel, Xiaogan Liang, Alex Zettl, Y. Ron Shen, and Feng Wang, appears in Nature Nanotechnology, available in advanced online publication at http://www.nature.com/nnano/index.html.

Martin, Hao, and Bechtel are with Berkeley Lab's Advanced Light Source. Hao is also with the Lab's Earth Sciences Division. Liang is with the Lab's Molecular Foundry. Ju, Geng, Horng, Girit, Zettl, Shen, and Wang are with UC Berkeley's Department of Physics. Geng is also with Lanzhou University, China. Zettl, Shen, and Wang are also with Berkeley Lab's Materials Sciences Division. This work was supported by the Office of Naval Research and the U.S. Department of Energy's Office of Science.

The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov.

For more about the Advanced Light Source, visit http://www-als.lbl.gov/.

Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 12 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit www.lbl.gov.

 

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Univ of Toronto researchers build an antenna for light- a novel class of self assembled nano-materials with entirely new properties

TORONTO, ON – University of Toronto researchers have derived inspiration from the photosynthetic apparatus in plants to engineer a new generation of nanomaterials that control and direct the energy absorbed from light.

Their findings are reported in a forthcoming issue of Nature Nanotechnology, which will be released on July 10, 2011.

The U of T researchers, led by Professors Shana Kelley and Ted Sargent, report the construction of what they term "artificial molecules."

"Nanotechnologists have for many years been captivated by quantum dots – particles of semiconductor that can absorb and emit light efficiently, and at custom-chosen wavelengths," explained co-author Kelley, a Professor at the Leslie Dan Faculty of Pharmacy, the Department of Biochemistry in the Faculty of Medicine, and the Department of Chemistry in the Faculty of Arts & Science.

"What the community has lacked – until now – is a strategy to build higher-order structures, or complexes, out of multiple different types of quantum dots. This discovery fills that gap."

The team combined its expertise in DNA and in semiconductors to invent a generalized strategy to bind certain classes of nanoparticles to one another.

"The credit for this remarkable result actually goes to DNA: its high degree of specificity – its willingness to bind only to a complementary sequence – enabled us to build rationally-engineered, designer structures out of nanomaterials," said Sargent, a Professor in The Edward S. Rogers Sr. Department of Electrical & Computer Engineering at the University of Toronto, who is also the Canada Research Chair in Nanotechnology.

"The amazing thing is that our antennas built themselves – we coated different classes of nanoparticles with selected sequences of DNA, combined the different families in one beaker, and nature took its course. The result is a beautiful new set of self-assembled materials with exciting properties."

Traditional antennas increase the amount of an electromagnetic wave – such as a radio frequency – that is absorbed, and then funnel that energy to a circuit. The U of T nanoantennas instead increased the amount of light that is absorbed and funneled it to a single site within their molecule-like complexes. This concept is already used in nature in light harvesting antennas, constituents of leaves that make photosynthesis efficient. "Like the antennas in radios and mobile phones, our complexes captured dispersed energy and concentrated it to a desired location. Like the light harvesting antennas in the leaves of a tree, our complexes do so using wavelengths found in sunlight," explained Sargent.

"Professors Kelley and Sargent have invented a novel class of materials with entirely new properties. Their insight and innovative research demonstrates why the University of Toronto leads in the field of nanotechnology," said Professor Henry Mann, Dean of the Leslie Dan Faculty of Pharmacy.

"This is a terrific piece of work that demonstrates our growing ability to assemble precise structures, to tailor their properties, and to build in the capability to control these properties using external stimuli," noted Paul S. Weiss, Fred Kavli Chair in NanoSystems Sciences at UCLA and Director of the California NanoSystems Institute.

Kelley explained that the concept published in today's Nature Nanotechnology paper is a broad one that goes beyond light antennas alone.

"What this work shows is that our capacity to manipulate materials at the nanoscale is limited only by human imagination. If semiconductor quantum dots are artificial atoms, then we have rationally synthesized artificial molecules from these versatile building blocks."

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Also contributing to the paper were researchers Sjoerd Hoogland and Armin Fischer of The Edward S. Rogers Sr. Department of Electrical & Computer Engineering, and Grigory Tikhomirov and P. E. Lee of the Leslie Dan Faculty of Pharmacy.

The publication was based in part on work supported by the Ontario Research Fund Research Excellence Program, the Natural Sciences and Engineering Research Council of Canada (NSERC), Canada Research Chairs program and the National Institutes of Health (NIH).

To read the published paper in its entirety, please contact Jef Ekins, Manager, Marketing & Communications, Leslie Dan Faculty of Pharmacy, University of Toronto.

Self-assembling electronic nano-components

Karlsruhe Institute of Technology: Self-assembling electronic nano-components

The July issue of Nature Materials describes the function of an innovative tiny component developed by researchers of KIT's Institute of Nanotechnology together with a team of European scientists

Magnetic storage media such as hard drives have revolutionized the handling of information: We are used to dealing with huge quantities of magnetically stored data while relying on highly sensitive electronic components. And hope to further increase data capacities through ever smaller components. Together with experts from Grenoble and Strasbourg, researchers of KIT's Institute of Nanotechnology (INT) have developed a nano-component based on a mechanism observed in nature.

What if the very tininess of a component prevented one from designing the necessary tools for its manufacture? One possibility could be to "teach" the individual parts to self-assemble into the desired product. For fabrication of an electronic nano-device, a team of INT researchers headed by Mario Ruben adopted a trick from nature: Synthetic adhesives were applied to magnetic molecules in such a way that the latter docked on to the proper positions on a nanotube without any intervention. In nature, green leaves grow through a similar self-organizing process without any impetus from subordinate mechanisms. The adoption of such principles to the manufacture of electronic components is a paradigm shift, a novelty.

The nano-switch was developed by a European team of scientists from Centre National de la Recherche Scientifique (CNRS) in Grenoble, Institut de Physique et Chimie des Matériaux at the University of Strasbourg, and KIT's INT. It is one of the invention's particular features that, unlike the conventional electronic components, the new component does not consist of materials such as metals, alloys or oxides but entirely of soft materials such as carbon nanotubes and molecules.

Terbium, the only magnetic metal atom that is used in the device, is embedded in organic material. Terbium reacts highly sensitively to external magnetic fields. Information as to how this atom aligns along such magnetic fields is efficiently passed on to the current flowing through the nanotube. The Grenoble CNRS research group headed by Dr. Wolfgang Wernsdorfer succeeded in electrically reading out the magnetism in the environment of the nano-component. The demonstrated possibility of addressing electrically single magnetic molecules opens a completely new world to spintronics, where memory, logic and possibly quantum logic may be integrated.

The function of the spintronic nano-device is described in the July issue of Nature Materials (DOI number: 10.1038/Nmat3050)for low temperatures of approximately one degree Kelvin, which is -272 degrees Celsius. Efforts are taken by the team of researchers to further increase the component's working temperature in the near future.

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Link Nature Article:http://www.nature.com/nmat/journal/vaop/ncurrent/pdf/nmat3050.pdf

Karlsruhe Institute of Technology (KIT) is a public corporation according to the legislation of the state of Baden-Württemberg. It fulfills the mission of a university and the mission of a national research center of the Helmholtz Association. KIT focuses on a knowledge triangle that links the tasks of research, teaching, and innovation.

Public release date: 20-Jun-2011

Contact: Monika Landgraf
presse@kit.edu
49-072-160-847-414
Helmholtz Association of German Research Centres

Antiviral protein design - Scientists design new anti-flu virus proteins using computational methods

One goal of antiviral protein design is to block molecular mechanisms involved in cell invasion and virus reproduction

A research article May 12 in Science demonstrates the use of computational methods to design new antiviral proteins not found in nature, but capable of targeting specific surfaces of flu virus molecules.

One goal of such protein design would be to block molecular mechanisms involved in cell invasion and virus reproduction.

Computationally designed, surface targeting, antiviral proteins might also have diagnostic and therapeutic potential in identifying and fighting viral infections.

The lead authors of the study are Sarel J. Fleishman and Timothy Whitehead of the University of Washington (UW) Department of Biochemistry, and Damian C. Ekiert from the Department of Molecular Biology and the Skaggs Institute for Chemical Biology at The Scripps Research Institute. The senior authors are Ian Wilson from Scripps and David Baker from the UW and the Howard Hughes Medical Institute.

The researchers note that additional studies are required to see if such designed proteins can help in diagnosing, preventing or treating viral illness. What the study does suggest is the feasibility of using computer design to create new proteins with antiviral properties.

"Influenza presents a serious public health challenge," the researchers noted, "and new therapies are needed to combat viruses that are resistant to existing anti-viral medications or that escape the body's defense systems."

They focused their attention on the section of the flu virus known as the hemagglutinin stem region. They concentrated on trying to disable this part because of its function in invading the cells of the human respiratory tract.

Their approach was somewhat similar to engineering a small space shuttle with the right configuration and construction, as well as recognizance and interlocking mechanisms, to dock with a troublesome space station and upset its mission. Only these scientists attempted their engineering feat at an atomic and molecular level.

Central to their approach is the ability of biological molecules to recognize certain other molecules or their working parts, and to have an affinity for binding to them at pre-determined locations. This recognition has both physical and chemical bases. Protein-protein interactions underlie many biological activities, including those that disarm and deactivate viruses.

In their report, the researchers described their general computational methods for designing new, tiny protein molecules that could bind to a certain spot on large protein molecules. They took apart some protein structures and watched how these disembodied sections interacted with a target surface. They analyzed particular high-affinity interactions, and used this information to further refine computer-generated designs for interfaces.

"Protein surfaces are never flat, but have many crevices and bulges at the atomic scale," lead author Sarel Fleishman explained. "The challenge is to identify amino acid side chains that would fit perfectly into these surfaces. The fit must be precise both in shape and in other chemical properties such as electrostatic charge. This geometrical and biophysical problem can be computationally solved, but requires large computational resources."

The researchers made use of a peer-to-peer computing platform called Rosetta@Home for going through the hundreds of millions of possible interactions of designed proteins and the surface of hemagglutinin to solve this challenge.

Following optimization, the designed proteins bound hemagglutinin very tightly.

Through this method, the researchers created two designs for new proteins that could bind to a surface patch on the stem of the influenza hemagglutinin from the 1918 H1N1 pandemic flu virus.

The shortcomings of the approach, due to approximations, meant that the researchers started out with 73 possibilities of which just two were successful.

One of the disease-causing characteristics of the influenza hemagglutinin stem is that it changes shape by refolding when in an acidic environment. This reconfiguration appears to allow the virus reproduce itself inside of cells.

In this study, one of the newly designed proteins was shown to block a conformational change, not only in H1 influenza hemagglutinin, but also in a similar component in H5 avian influenza.

"This finding suggests that this new protein design may have virus-neutralizing effects against multiple influenza subtypes," the researchers reported.

What was unusual about the workable designs was that they had helical binding modes, roughly shaped like a spiral staircase, rather than the loop binding that naturally occurring antibodies employ.

X-ray crystallography of the proteins complex showed that the actual orientation of the bound proteins was almost identical to the way the binding mode was designed. The modified surface of the main recognition helix on the designed protein was packed into a groove on the desired region of the virus protein.

"Overall, the crystal structure is in excellent agreement with the designed interface," the researchers noted, "with no significant deviations at any of the contact points." The design and the actual formation were nearly identical.

The scientists were encouraged by this finding. Despite their limitations, the design methods, the scientists believe, capture the essential features of the desired protein-protein interaction.

http://www.eurekalert.org/pub_releases/2011-05/uow-sdn051311.php

 

Walter Derzko

Smart Economy

Toronto

Rice University lab creates smart materials -self-strengthening nanocomposite

Researchers at Rice University have created a synthetic material that gets stronger from repeated stress much like the body strengthens bones and muscles after repeated workouts.

Work by the Rice lab of Pulickel Ajayan, professor in mechanical engineering and materials science and of chemistry, shows the potential of stiffening polymer-based nanocomposites with carbon nanotube fillers. The team reported its discovery this month in the journal ACS Nano.

The trick, it seems, lies in the complex, dynamic interface between nanostructures and polymers in carefully engineered nanocomposite materials.

Brent Carey, a graduate student in Ajayan's lab, found the interesting property while testing the high-cycle fatigue properties of a composite he made by infiltrating a forest of vertically aligned, multiwalled nanotubes with polydimethylsiloxane (PDMS), an inert, rubbery polymer. To his great surprise, repeatedly loading the material didn't seem to damage it at all. In fact, the stress made it stiffer.

Carey, whose research is sponsored by a NASA fellowship, used dynamic mechanical analysis (DMA) to test their material. He found that after an astounding 3.5 million compressions (five per second) over about a week's time, the stiffness of the composite had increased by 12 percent and showed the potential for even further improvement.

"It took a bit of tweaking to get the instrument to do this," Carey said. "DMA generally assumes that your material isn't changing in any permanent way. In the early tests, the software kept telling me, 'I've damaged the sample!' as the stiffness increased. I also had to trick it with an unsolvable program loop to achieve the high number of cycles."

Materials scientists know that metals can strain-harden during repeated deformation, a result of the creation and jamming of defects -- known as dislocations -- in their crystalline lattice. Polymers, which are made of long, repeating chains of atoms, don't behave the same way.

The team is not sure precisely why their synthetic material behaves as it does. "We were able to rule out further cross-linking in the polymer as an explanation," Carey said. "The data shows that there's very little chemical interaction, if any, between the polymer and the nanotubes, and it seems that this fluid interface is evolving during stressing."

"The use of nanomaterials as a filler increases this interfacial area tremendously for the same amount of filler material added," Ajayan said. "Hence, the resulting interfacial effects are amplified as compared with conventional composites.

"For engineered materials, people would love to have a composite like this," he said. "This work shows how nanomaterials in composites can be creatively used."

They also found one other truth about this unique phenomenon: Simply compressing the material didn't change its properties; only dynamic stress -- deforming it again and again -- made it stiffer.

Carey drew an analogy between their material and bones. "As long as you're regularly stressing a bone in the body, it will remain strong," he said. "For example, the bones in the racket arm of a tennis player are denser. Essentially, this is an adaptive effect our body uses to withstand the loads applied to it.

"Our material is similar in the sense that a static load on our composite doesn't cause a change. You have to dynamically stress it in order to improve it."

Cartilage may be a better comparison -- and possibly even a future candidate for nanocomposite replacement. "We can envision this response being attractive for developing artificial cartilage that can respond to the forces being applied to it but remains pliable in areas that are not being stressed," Carey said.

Both researchers noted this is the kind of basic research that asks more questions than it answers. While they can easily measure the material's bulk properties, it's an entirely different story to understand how the polymer and nanotubes interact at the nanoscale.

"People have been trying to address the question of how the polymer layer around a nanoparticle behaves," Ajayan said. "It's a very complicated problem. But fundamentally, it's important if you're an engineer of nanocomposites.

"From that perspective, I think this is a beautiful result. It tells us that it's feasible to engineer interfaces that make the material do unconventional things."

 

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Co-authors of the paper are former Rice postdoctoral researcher Lijie Ci; Prabir Patra, assistant professor of mechanical engineering at the University of Bridgeport; and Glaura Goulart Silva, associate professor at the Federal University of Minas Gerais, Brazil.

Rice University and the NASA Graduate Student Researchers Program funded the research.

Read the abstract at http://pubs.acs.org/doi/abs/10.1021/nn103104g

Artwork is available for download at
http://media.rice.edu/images/media/NewsRels/0323_cut_composite2.jpg
http://www.media.rice.edu/images/media/NEWSRELS/0323_carey.jpg

CAPTIONS:

(Material)
A small block of nanocomposite material proved its ability to stiffen under strain at a Rice University laboratory. (Credit Ajayan Lab/Rice University)

(Researcher)
Rice University graduate student Brent Carey positions a piece of nanocomposite material in the dynamic mechanical analysis device. He used the device to compress the material 3.5 million times over about a week, proving that the nanocomposite stiffens under strain. The research is the subject of a new paper in the journal ACS Nano. (Credit Jeff Fitlow/Rice University)

Located on a 285-acre forested campus in Houston, Texas, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is known for its "unconventional wisdom." With 3,485 undergraduates and 2,275 graduate students, Rice's undergraduate student-to-faculty ratio is less than 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice has been ranked No. 1 for best quality of life multiple times by the Princeton Review and No. 4 for "best value" among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://futureowls.rice.edu/images/futureowls/Rice_Brag_Sheet.pdf.

Fullerenes or Buckeyballs -Carbon 60 from Ukraine protect from radiation

Scientists in Ukraine are about to start production of a fullerene or buckeyball C60 drink called Fullerene Water Solution or FWS which has been approved by the Ukrainian Ministry of Health. One of its properties that it offers is radio-protection. I see a brisk extreme medical tourism market to Ukraine for FWS treatment if the situation in Japan worsens. It's the world'd first nanotech health drink.

some recent acadmic papers

G.V Andrievsky, A.A. Tykhomyrov. TOWARD THE MECHANISM OF “STEALTH” ANTIOXIDANT ACTIVITY OF HYDRATED C₆₀ FULLERENE NANOPARTICLES AND PERSPECTIVES OF THEIR BIOMEDICAl APPLICATIONS. Collection of Abstracts of the First International Conference on Nanochemistry and Nanotechnologies, March 23-24, 2010, Tbilisi, Georgia, p. 20-22.

 

A.A. Tykhomyrov, V.S. Nedzvetsky, T.Z. Chachibaia, G.V. Andrievsky. NANODRUGS AGAINST DIABETIC ENCEPHALOPATHY: NEUROPROTECTIVE EFFECTS OF HYDRATED C₆₀ FULLERENE NANOPARTICLES AT STREPTOZOTOCIN-INDUCED DIABETES. Ibid. p. 23-24.

UPDATE: C60 and radiation

FWS C60 and radiation  source:  http://doctorapsley.com/RadiationTherapy.aspx

 

Structured Water: 

J Photochem Photobiol B. 2010 Feb 12;98(2):144-51. Epub 2009 Dec 5.

Defensive effects of fullerene-C60/liposome complex against UVA-induced intracellular reactive oxygen species generation and cell death in human skin keratinocytes HaCaT, associated with intracellular uptake and extracellular excretion of fullerene-C60.

Kato S, Kikuchi R, Aoshima H, Saitoh Y, Miwa N.

Laboratory of Cell-Death Control BioTechnology, Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, 562, Nanatsuka, Shobara, Hiroshima 727-0023, Japan.

Abstract

The UVA-irradiation of 10 J/cm(2) on HaCaT keratinocytes increased 59.1% of the intracellular reactive oxygen species (ROS) by NBT assay and the cell viability decreased to 31.5% by WST-1 assay, comparing to the non-irradiated control. In the presence of fullerene-C60 (C60) incorporated in phospholipid membrane vehicle (LiposomeFullerene: Lpsm-Flln) of 250-500 ppm, they were restored to -9.1% to +2.3% of the ROS and 83.0-84.8% of the cell viability, but scarcely restored by the liposome without C60 (Lpsm). In HaCaT cells administered with Lpsm-Flln (150 ppm), C60 was ingested at the intracellular concentrations of 1.4-21.9 ppm for 4-24 h, and, intracellular C60 was excreted by 80% at 4h after rinsing-out, and decreased to 2-10% after 24-48 h. C60 was predominantly distributed around the outside of nuclear membrane without deterioration of intact cell morphology according to fluorescent immunostain. Thus Lpsm-Flln is found to be an effective antioxidant that could preserve HaCaT keratinocytes against UVA-induced cellular injury. Lpsm-Flln has a potential to serve as a cosmetic material for skin protection against UVA. Copyright 2009 Elsevier B.V. All rights reserved.

PMID: 20060738 [PubMed - in process]

 

 

J Radiat Res (Tokyo). 2008 May;49(3):321-7. Epub 2008 Feb 16.

Fullerenol C60(OH)24 effects on antioxidative enzymes activity in irradiated human erythroleukemia cell line.

Bogdanović V, Stankov K, Icević I, Zikic D, Nikolić A, Solajić S, Djordjević A, Bogdanović G.

Institute of Oncology, Department of Experimental Oncology, Sremska, Kamenica, Serbia.

Abstract

Radiotherapy-induced toxicity is a major dose-limiting factor in anti-cancer treatment. Ionizing radiation leads to the formation of reactive oxygen and nitrogen species (ROS/RNS) that are associated with radiation-induced cell death. Investigations of biological effects of fullerenol have provided evidence for its ROS/RNS scavenger properties in vitro and radioprotective efficiency in vivo. Therefore we were interested to evaluate its radioprotective properties in vitro in the human erythroleukemia cell line. Pre-treatment of irradiated cells by fullerenol exerted statistically significant effects on cell numbers and the response of antioxidative enzymes to X-ray irradiation-induced oxidative stress in cells. Our study provides evidence that the pre-treatment with fullerenol enhanced the enzymatic activity of superoxide dismutase and glutathione peroxidase in irradiated K562 cells. PMID: 18285660 [PubMed - indexed for MEDLINE]

Walter Derzko

Scientists Generate Two Energetic Electronic States from One Photon yielding 35% efficiency boost for solar

Double yield via singlet fission could mean 35% efficiency boost for solar

Researchers from the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) and the University of Colorado, Boulder (UCB), have reported the first designed molecular system that produces two triplet states from an excited singlet state of a molecule, with essentially perfect efficiency.

The breakthrough could lead to a 35 percent increase in light-harvesting yield in cells for photovoltaics and solar fuels.

The experiments, using a process called singlet fission, demonstrated a 200 percent quantum yield for the creation of two triplets of the molecule 1,3-diphenylisobenzofuran (DPIBF) at low temperatures.

In singlet fission, a light-absorbing molecular chromophore shares its energy with a nearby non-excited neighboring molecule to yield a triplet excited state of each. If the two triplets behave independently, two electron-hole pairs can be generated for each photon absorbed in a solar cell. This process could subsequently increase by one third.the conversion efficiency of solar photons into electricity or solar fuels.

The researchers identified DPIBF as a promising candidate while searching for molecular chromophores that have the required ratio of singlet and triplet energy states.

Earlier, NREL and Los Alamos National Laboaratory had demonstrated an analgous two-electrons-from-one photon bonus using semiconductor quantum dots in a process NREL termed Multiple Exciton Generation. The latest advance is the first to demonstrate the electron multiplication phenomenon via  the singlet-fission process in molecules.

Until this most recent advance, singlet fission had been known as a somewhat obscure phenomenon occurring at low efficiency in a small number of molecular systems. In 2004, NREL and UCB revisited singlet fission as a potential way to maximize solar photon conversion efficiency. In 2006, NREL’s Arthur J. Nozik and Mark C. Hanna calculated the gains in thermodynamic efficiencies that were possible with solar cells based on singlet fission. These activities led to a much more extensive search for the best candidate molecules in a collaboration between NREL and the research group at the UCB led by Josef Michl.

The research has been published in the Journal of the American Chemical Society.  Authors are NREL’s Justin C. Johnson and Arthur J. Nozik, and UCB’s Josef Michl.  For a technical summary of this article, please visit http://www.nrel.gov/news/pdfs/technical_summary_20101202_press_release.pdf

NREL is the U.S. Department of Energy's primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for DOE by the Alliance for Sustainable Energy, LLC. 

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New smart nano microscope reveals 3D ultrastructure of cells

New microscope reveals ultrastructure of cells

HZB researchers can take images of small cellular components in their natural environment -- while the cell remains intact

For the first time, there is no need to chemically fix, stain or cut cells in order to study them. Instead, whole living cells are fast-frozen and studied in their natural environment. The new method delivers an immediate 3-D image, thereby closing a gap between conventional microscopic techniques.

The new microscope delivers a high-resolution 3-D image of the entire cell in one step. This is an advantage over electron microscopy, in which a 3-D image is assembled out of many thin sections. This can take up to weeks for just one cell. Also, the cell need not be labelled with dyes, unlike in fluorescence microscopy, where only the labelled structures become visible. The new X-ray microscope instead exploits the natural contrast between organic material and water to form an image of all cell structures. Dr. Gerd Schneider and his microscopy team at the Institute for Soft Matter and Functional Materials have published their development in Nature Methods (DOI:10.1038/nmeth.1533).

With the high resolution achieved by their microscope, the researchers, in cooperation with colleagues of the National Cancer Institute in the USA, have reconstructed mouse adenocarcinoma cells in three dimensions. The smallest of details were visible: the double membrane of the cell nucleus, nuclear pores in the nuclear envelope, membrane channels in the nucleus, numerous inva­ginations of the inner mitochondrial membrane and inclusions in cell organelles such as lysosomes. Such insights will be crucial for shedding light on inner-cellular processes: such as how viruses or nanoparticles penetrate into cells or into the nucleus, for example.

This is the first time the so-called ultrastructure of cells has been imaged with X-rays to such precision, down to 30 nanometres. Ten nanometres are about one ten-thousandth of the width of a human hair. Ultrastructure is the detailed structure of a biological specimen that is too small to be seen with an optical microscope.

Researchers achieved this high 3-D resolution by illuminating the minute structures of the frozen-hydrated object with partially coherent light. This light is generated by BESSY II, the synchrotron source at HZB. Partial coherence is the property of two waves whose relative phase undergoes random fluctuations which are not, however, sufficient to make the wave completely incoherent. Illumination with partial coherent light generates significantly higher contrast for small object details compared to incoherent illumination. Combining this approach with a high-resolution lens, the researchers were able to visualize the ultrastructures of cells at hitherto unattained contrast.

The new X-ray microscope also allows for more space around the sample, which leads to a better spatial view. This space has always been greatly limited by the setup for the sample illumination. The required monochromatic X-ray light was created using a radial grid and then, from this light, a diaphragm would select the desired range of wavelengths. The diaphragm had to be placed so close to the sample that there was almost no space to turn the sample around. The researchers modified this setup: Monochromatic light is collected by a new type of condenser which directly illuminates the object, and the diaphragm is no longer needed. This allows the sample to be turned by up to 158 degrees and observed in three dimensions. These developments provide a new tool in structural biology for the better understanding of the cell structure.

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 Walter Derzko