Advanced Search
Search within... - - - - - - - - - - 2009 Fall Meeting 2010 Spring Meeting 2009 Spring Meeting Meetings Publications

Inside...

• Materials News Archives
• Research Spotlight
• Features & Commentary
• Literature Scan
• Fun & Newsworthy
• Images Archive
• Materials360 (eMatters)
• MRS Bulletin

• Home
• Materials360 Plus®
• Materials News

Materials News

Current materials-related news gathered from around the Web that is frequently updated. Visit this page regularly to keep in touch with the latest in materials research. Please note that some external websites may require registration for access.

Please login for viewing archives.

You can also suggest a research news item for possible inclusion on this page by contacting the Web Science Editor, Dr. Gopal Rao

Links

• Non-destructive readout of ferroelectric states
  (Nature)

  A general problem in the electronics industry is that the insulating materials used in the continually shrinking capacitors and transistors start to leak charge when they become too thin. This leads to large power consumption and, in the case of memory, to difficulties in storing and retrieving information. In a new report, researchers now show that this generally undesirable leakage current can in fact be very useful. They find that the leakage current flowing through ultrathin (1–3 nanometres) ferroelectric films of barium titanate (BaTiO3) is strongly dependent on their electric polarization states — that is, on whether the net electric dipole of the material is in one or the other of the two possible orientations. The authors' result, which allows direct reading of the polarization state through a simple measurement of the material's electrical resistance, may be just what is needed to put ferroelectric random access memories (FeRAMs) — those based on storing information in the polarization states of ferroelectric materials — back on track in the race for faster and better memory.
  [Giant tunnel electroresistance for non-destructive readout of ferroelectric states, Nature 460, 81-84 (2 July 2009) | doi:10.1038/nature08128]
  (July 2, 2009)

• Microfluidic device measures mechanical properties of bacterial biofilms
  (Eurekalert/University of Michigan)

  
  Credit: Langmuir

  Researchers have devised a microfluidic device or a "lab-on-a-chip" to help them understand the mechanical behavior of biofilms, colonies of bacteria involved in most human infectious diseases. Representing a new application of microfluidics, the device measures biofilms' resistance to pressure. Biofilms experience various kinds of pressure in nature and in the body as they squeeze through capillaries and adhere to the surfaces of medical devices, for example. To understand biofilms and their life cycle, one needs to consider not just their genetics, but also their mechanical properties. Researchers haven't studied these properties yet because there hasn't been a good way to examine biofilms at the appropriate scale. The new microfluidic device provides the right scale. The channel-etched chip, made from a flexible polymer, allows researchers to study minute samples of between 50 and 500 bacterial cells that form biofilms of 10-50 microns in size.
  [Langmuir Cover, July 7, 2009: Vol. 25, Iss. 13]
  [Flexible Microfluidic Device for Mechanical Property Characterization of Soft Viscoelastic Solids Such as Bacterial Biofilms, Langmuir, 2009, 25 (13), pp 7743–7751 DOI: 10.1021/la803413x]
  (July 2, 2009)

• Unexpected long-range effects in advanced magnetic devices
  (Eurekalert/NIST)

  
  Credit: Shapiro, NIST

  A tiny grid pattern has led scientists to an unexpected finding—the surprisingly strong and long-range effects of certain electromagnetic nanostructures used in data storage. They started with a thin ferromagnetic film covering a silicon wafer and then added on top a grid of antiferromagnetic strips about 10 nanometers thick and 10 micrometers wide, separated by gaps of about 100 micrometers. Using an instrument that provided real-time images of the magnetization within grid the structure, the team watched the grid structure as they increased and decreased the magnetic field surrounding it. What they found surprised them. As expected, the ferromagnetic material directly under the grid lines showed the pinning effect, but, quite unexpectedly, so did the uncovered material in regions between the grid lines far removed from the antiferromagnetic material. In fact, the effect was found to extend to regions 50 micrometers away from the closest antiferromagnetic strip, at least 1,000 times further than was previously known to be possible. The ramifications are that engineers planning to build dense arrays of these structures onto a chip for high-performance memory or sensor devices will find interesting new scientific issues for investigation in optimizing how closely they can be packed without interfering with each other.
  [Unexpectedly long-range influence on thin-film magnetization reversal of a ferromagnet by a rectangular array of FeMn pinning films, Physical Review B 79, 144435, 2009. DOI: 10.1103/PhysRevB.79.144435]
  (July 2, 2009)

• Holey nanosheets for wastewater dye removal
  (PhysOrg.com)

  Researchers have discovered that extremely thin sheets of nickel oxide with hexagonally shaped holes can absorb hazardous dyes from wastewater nearly as well as the best traditional methods. Metal oxides like NiO have the main advantage that the absorbed material can be burned off and the NiO can be reused. Additionally, the polar surface of the NiO nanosheets may provide some advantages in adsorbing certain substrates. Methods for the recycling of activated carbon are often expensive and in this way and the carbon and the material it has absorbed must be discarded. They tested the absorption performance of the nanosheets and the NiO powder using three common synthetic dyes: reactive brilliant red X-3B, congo red, and fuchsin red. They found that the nickel oxide nanosheets could remove, on average, two to three times as much dye as the powdered NiO. The nanosheets still do not perform as well as activated carbon - for example, the nanosheets absorbed about 71 percent of the congo red dye while the activated carbon took up 98 percent - but they have the advantage that the absorbed material can be readily burned off and the sheets reused. The sheets are also inexpensive to produce and can be created using “green” methods.
  [NiO(111) nanosheets as efficient and recyclable adsorbents for dye pollutant removal from wastewater, 2009 Nanotechnology 20 275707 (9pp) doi: 10.1088/0957-4484/20/27/275707]
  (July 1, 2009)

• Ultra-thin material absorbs almost 100% light
  (Leiden University)

  
  Credit: Eduard Driessen, Michiel de Dood, Leiden University

  Researchers have demonstrated that 4.5 nanometers thick niobiumnitride (NbN) is ultra-absorbent with respect to light. They have recorded a light absorption of almost 100%, while the best light absorption to date was 50%. This research brings the realization of an ideal light detector a step closer. The most important part of the detector is a lattice of ultra-absorbent NbN filaments. When an s-light particle falls on the lattice, it is absorbed (light has two kinds of polarizations: s and p). A p-particle is reflected. This p-particle can then in turn be collected by a second detector so that all the light is detected. Calculations show that the wavelength (colour) of the light particle has hardly any influence. The detector can therefore also be used for particles with completely different wavelengths, such as detection systems for telecommunications and infra-red equipment.
  [The perfect absorber, Appl. Phys. Lett. 94, 171109 (2009); DOI:10.1063/1.3126062 ]
  (June 30, 2009)

• Microspheres change color instantly in response to external magnetic field
  (University of California, Riverside)

  
  Credit: Yin lab, Univ. Cal. Riverside

  Microscopic polymer beads that change color instantly and reversibly when external magnetic fields acting upon the microspheres change orientation, have been fabricated. The beads or magnetochromatic microspheres have excellent structural stability. They also are highly compatible with various types of dispersion media such as water, alcohol, hexane and even polymer solutions, allowing them to retain magnetically tunable colors in a variety of chemical environments. To fabricate the microspheres, the researchers first mixed magnetic iron oxide particles into a resin, which is initially in liquid phase but later turns solid on exposure to ultraviolet curable resin. They then dispersed the resin solution in oil (mineral oil or silicon oil), whereupon the resin transformed into spherical droplets in the oil. Next, the researchers applied an external magnetic field to organize the iron oxide particles into periodically ordered structures. These structures display a reflective color if viewed along the direction of the magnetic field. Finally, the research team exposed the liquid system to ultraviolet radiation to polymerize the resin droplets and make them solid microspheres.
  [Magnetochromatic Microspheres: Rotating Photonic Crystals, J. Am. Chem. Soc., Article ASAP DOI: 10.1021/ja903626h Publication Date (Web): June 15, 2009]
  (June 30, 2009)

• Box-shaped 3D-DNA origami
  (Royal Society of Chemistry)

  
  Credit: A. Kuzuya and M. Komiyama, Chem. Commun.

  One important area in DNA nanotechnology is DNA origami in which single-stranded DNA is folded to construct arbitrary structures. These can then be used as platforms for nanostructures such as protein arrays, gold nanoparticles and messenger RNA. Until now, the focus has been on 2D origami, but now researchers have shifted their focus to 3D structures. They folded DNA strands into an open-box shape and identified it using atomic force microscopy. For guest encapsulation, the box is designed to fold into an open form first, and can be closed afterwards by adding appropriate DNA strands. The outside and inside of the box can be distinguished throughout the process so it may be possible to place a guest molecule in the face of the open form before closing it. The boxes are similar in size to virus capsids, which are currently gaining interest as nanocontainers, but the faces of the DNA boxes are easier to chemically modify, enabling selective capture of various guest molecules.
  [Design and construction of a box-shaped 3D-DNA origami, Chem. Commun., 2009 DOI: 10.1039/b907800b]
  (June 30, 2009)

• Tiny ratchet could lead to cancer traps
  (Physics World)

  
  Credit: Nature Physics

  Scientists have built a tiny device that can separate some types of cancerous and non-cancerous cells. Resembling a ratchet, the device exploits the fact that different cells use different strategies to squeeze their way through narrow passages. The team believes that similar ratchets could be used to trap "metastatic" cancer cells, which can spread the disease throughout the body. Metastasis is the process by which cancer cells break away from a tumour and move through the body — creating more tumors and often decreasing a patient’s chance of survival. Understanding how these cells move could lead to new medical treatments that stop metastasis — or even the development of “cancer traps” that remove cancer cells from circulation.
  [Directing cell motions on micropatterned ratchets, Nature Physics Published online: 14 June 2009 | doi:10.1038/nphys1306]
  (June 29, 2009)

• CO trapped on a chip
  (Science)

  Microfluidics technology has facilitated remarkable miniaturization of chemical synthesis platforms; through electrically gated solution flow and mixing, molecular reactions can be carried out on chips several centimeters across. However, when it comes to more fundamental dynamics studies, involving probing gas-phase molecules in specific quantum mechanical states, experiments still tend to require much larger interaction areas. Researchers have taken a step toward miniaturization in this latter regime by demonstrating the isolation of a cold gas-phase beam of CO molecules just above a microelectrode-decorated chip. The technique relies on rapidly modulated electric fields that trap and then slow down the incoming molecules through dipole interactions. Once brought to a stop, the molecules can be held on the chip for a discrete period and then released to a detector.
  [Trapping Molecules on a Chip, Science 26 June 2009: Vol. 324. no. 5935, pp. 1699 - 1702 DOI: 10.1126/science.1175975]
  (June 26, 2009)

• Self-assembled tetrahedral container molecule encapsulates white phosphorus
  (Eurekalert/Cambridge University)

  For centuries it has been known for its violent combustion upon contact with air – but this week a team of researchers reveals that it has tamed one of the most hazardous chemical substances, white phosphorous, a feedstock for the preparation of many useful chemicals such as weed killers, insecticides and fertiliser. White phosphorous is also infamous for its propensity to burst into flame. For this reason it is often used in military campaigns to create smokescreens to mask movement from the enemy, as well as an incendiary in bombs, artillery and mortars. The team created a 'container molecule' to stabilise white phosphorous indefinitely. This renders it safe until such time as a signal agent, benzene, is applied to release it.
  [White Phosphorus Is Air-Stable Within a Self-Assembled Tetrahedral Capsule, Science 26 June 2009: Vol. 324. no. 5935, pp. 1697 - 1699 DOI: 10.1126/science.1175313]
  (June 26, 2009)

• Stream of sand behaves like water
  (National Science Foundation/Univ. Chicago)

  
          Credit: Helge F. Gruetjen*, John R. Royer, Scott R. Waitukaitis,
          and Heinrich M. Jaeger, The University of Chicago

  Researchers recently showed that dry granular materials such as sands, seeds and grains have properties similar to liquid, forming water-like droplets when poured from a given source. The finding could be important to a wide range of industries that use "fluidized" dry particles. It was previously thought that dry particles lacked sufficient surface tension to form droplets like ordinary liquids. But, in a first-time accomplishment, the researchers used high-speed photography to measure minute levels of surface tension and detect droplet formation in flows of dry granular materials. They observed falling 100-micrometer-diameter glass beads, or streaming sand, and found that forces as much as 100,000 times smaller than those that produce surface tension in ordinary liquids could cause droplet formation in granular streams and cause these dry streams to behave like an ultra-low-surface-tension liquid. They also directly measured grain-to-grain interactions with an atomic force microscope.
  [High-speed tracking of rupture and clustering in freely falling granular streams, Nature 459, 1110-1113 (25 June 2009) | doi:10.1038/nature08115]
  (June 25, 2009)

• Giant intrinsic electroresistance in conventional ferroelectric films
  (Newswise/Oak Ridge National Lab)

  A new study has for the first time demonstrated giant intrinsic electroresistance in conventional ferroelectric films, where flipping of the spontaneous polarization increased conductance by up to 50,000 percent. The key distinction of ferroelectric memory switches is that they can be tuned through thermodynamic properties of ferroelectrics. Numerous previous works have demonstrated defect-mediated memory, but defects cannot easily be predicted, controlled, analyzed or reduced in size. Ferroelectric switching, however, surpasses all of these limitations and will offer unprecedented functionality. The authors believe that using phase transitions such as ferroelectric switching to implement memory and computing is the real fundamental distinction of future information technologies.
  [Polarization Control of Electron Tunneling into Ferroelectric Surfaces, Science 12 June 2009: Vol. 324. no. 5933, pp. 1421 - 1425 DOI: 10.1126/science.1171200]
  (June 25, 2009)

• Transmitting information using chemistry
  (PhysOrg.com)

  
  Credit: Samuel W. Thomas III, et al. ©2009 PNAS

  Information transmission currently require electrons or photons for transmitting information. Scientists have now demonstrated a third method of transmission: chemical reactions. Based on a flammable “infofuse,” the new system combines information technology and chemistry into a new area the researchers call "infochemistry." The system transmits information in the form of coded pulses of light generated entirely by chemical reactions, without electricity. The system is self-powered, with power being generated by combustion. The power density of the system is higher than that of electrochemical batteries, and has the advantage of not discharging over time. The study demonstrates direct chemical to binary encoding, and transmission of information at a useful bit rate, without batteries. The system consists of a strip or fuse of combustible material (nitrocellulose) about 1 mm long. When ignited, a yellow-orange flame moves along the infofuse. To encode information, the scientists patterned the fuse with various metallic salts, which could be done using a desktop inkjet printer or a micropipettor. With their different emission wavelengths, the salts created distinct emission lines in different regions of the electromagnetic spectrum. By coding letters of the alphabet using patterns of metallic salts, the scientists transmitted the phrase, “LOOK MOM NO ELECTRICITY” on a single infofuse using the new technique.
  [Infochemistry and infofuses for the chemical storage and transmission of coded information, Proceedings of the National Academy of Sciences. vol. 106, no. 23, 9147-9150]
  (June 24, 2009)

• Polymer solar cell with near-perfect internal efficiency
  (PhysOrg.com)

  Researchers have developed a polymer-based solar cell with an ability not yet seen in similar cells: almost every single photon it absorbs is converted into a pair of electric-charge carriers, and every one of those pairs is collected at the cell's electrodes. The overall efficiency of the cell is six percent, excellent for polymer-based solar cells. The cell incorporates an alternating co-polymer in bulk heterojunction composite with a fullerene derivative. The cell exhibits the best performance of any bulk heterojunction system investigated so far, according to the authors.
  [Bulk heterojunction solar cells with internal quantum efficiency approaching 100%, Nature Photonics 3, 297 - 302 (2009) doi:10.1038/nphoton.2009.69]
  (June 24, 2009)

• Elusive forms of water may have been found
  (Nature News)

  In a study done in 1992, computer simulations of water suggested that hydrogen bonds might produce two different types of liquid if water was made very cold and squeezed to high pressures. In one form, the hydrogen bonds create a rather open, sparse network of water molecules, called low-density liquid (LDL) water. In the other, water molecules press closer at the cost of breaking some hydrogen bonds, forming a high-density liquid (HDL). The two types of liquid water changed from one to the other in an abrupt 'phase transition' in the simulations. Now, researchers of a new study report that they have experimentally observed these two phases. They used electron spin resonance to study the mobility of water molecules within tiny pockets of liquid trapped between crystallites of ice at temperatures down to around –183 °C. The researchers don't measure the movement of the water directly: instead, they watch the motions of an organic 'probe' molecule called TEMPOL. However, some researchers in the field remain unconvinced.
  [Proc. Natl Acad. Sci. USA published online. doi:10.1073/pnas.0900734106 (2009)]
  (June 24, 2009)

• Carbon nanotubes wired for pressure sensing
  (NanotechWeb)

  
  Credit: A. Kaul, JPL

  Carbon nanotube (CNT)-based pressure sensors offer the advantages of ultra-low-power operation, wide dynamic range and ease of integration with microcavities for vacuum microelectronics, compared with conventional thermal conductivity gauges such as Pirani or thermocouple devices. The enhanced pressure sensitivity of CNT-based sensors, especially at large bias voltages, was attributed to the one-dimensional nature of electrical transport within the suspended tubes, as well as the contacts. These artifacts in suspended tubes were manifested by the presence of a negative differential conductance (NDC) regime in the device's IV curve. The feature was absent in the profile for unreleased tubes. The presence of the NDC suggests a large optical phonon density in suspended tubes at large biases, which affects tube temperatures and can be exploited to enhance the sensitivity of CNT-based pressure sensors.
  [Gas sensing with long, diffusively contacted single-walled carbon nanotubes, Nanotechnology 20 (2009) 155501]
  (June 23, 2009)

• Spintronics without magnetism
  (Physics)

  
  Credit: Alan Stonebraker, Physics

  At first glance, it seems almost a given that ferromagnetism would be a necessary and integral component of any scheme for semiconductor spintronic devices. For instance, a semiconductor spintronic device generically requires an imbalance between spin “up” and “down” populations of electrons (or holes). We can imagine this imbalance being created by the injection of spin-polarized charge carriers from a ferromagnet, which acts as a spin polarizer. Alternatively, we could build devices from ferromagnetic semiconductors that have an intrinsic spin imbalance. Indeed, important advances have been made in semiconductor spintronics by using these very notions, with a number of interesting proof-of-concept semiconductor spintronic device demonstrations that incorporate ferromagnetic elements for injecting, detecting, and manipulating spins. But, discoveries in recent years have inspired a completely different avenue to semiconductor spintronics—one that does not involve any ferromagnetism whatsoever.
  (June 23, 2009)

• A camera from a sheet of fiber
  (Technology Review)

     
     Credit: Yoel Fink, Fabien Sorin, MIT

  Researchers have integrated a collection of light sensors into polymer fibers, creating a new type of camera. Such a camera would be lightweight, robust, and even foldable. They integrated eight semiconducting light sensors into a polymer cylinder with a diameter of 25 millimeters, controlling the sensor's spacing and angle within the fiber. Once the sensors, made of a type of semiconducting glass, were in position, the polymer cylinder was heated and then stretched so that the diameter shrank the diameter of hundreds of micrometers--a process that is identical to the way in which commercial fiber is made for telecommunication applications--retaining the orientation of the sensors. When light hits the semiconductors, it creates an electrical current. The intensity of this current from the fibers is input into algorithms, running on an attached computer, that create the image of an object placed near the sheet of fiber.
  (June 22, 2009)

• Nanoparticles make self-erasing images
  (Royal Society of Chemistry)

  
  Credit: Angewandte Chemie

  Materials displaying 'self-erasing' color images have been created by researchers, using specific nanoparticles that can assemble and disassemble themselves under different wavelengths of light. The materials are printed with ultraviolet (UV) light and erased with visible light. They are made by coating gold and silver nanoparticles with a single layer of azobenzene molecules, and then embedding the nanoparticles in thin, flexible 'organogel' films. When the films are exposed to UV light, the structural symmetry of the azobenzene molecules flips, and they acquire electric dipoles that make them attract. This attraction causes the nanoparticles to assemble, and thereby take on a new colour. However, in an absence of UV light - or even better, in strong visible light - the particles revert to their original symmetry, and the colour disappears over a period of time.
  [Writing Self-Erasing Images using Metastable Nanoparticle Inks, Angewandte Chemie International Edition, Published Online: 16 Jun 2009]
  (June 22, 2009)

• Pure white light emitting molecule developed
  (Science Daily)

  
  Credit: The American Chemical Society

  Researchers are reporting the first use of a fundamentally new approach in the quest for a pure white light emitting LED. They describe the development of a new, simpler white LED using a single molecule that is the first to achieve stable white light emissions. Their specially engineered molecule combines two light-emitting materials, one orange and one blue, which together produce white light over the entire visible range. In laboratory studies, the scientists showed that light production from an LED using the new molecule was highly efficient and had excellent color stability and reproducibility.
  [A White-Light-Emitting Molecule: Frustrated Energy Transfer between Constituent Emitting Centers, J. Am. Chem. Soc., Article ASAP DOI: 10.1021/ja902533f]
  (June 19, 2009)

• Crustacean shell, polyester mixed-fiber material for nerve repair
  (University of Washington)

  
  Credit: University of Washington

  In the clothing industry it's common to mix natural and synthetic fibers such as cotton and polyester. Researchers have now used the same principle for biomedical applications by mixing an industrial polyester with chitosan, found in the shells of crabs and shrimp, creating a promising new material for the tiny tubes that support repair of a severed nerve, and could serve other medical uses. The hybrid fiber combines the biologically favorable qualities of the natural material with the mechanical strength of the synthetic polymer. The first component of their material, polycaprolactone, is a strong, flexible, biodegradable polyester commonly used in sutures. It is not suitable on its own for use as a nerve guide because water-based cells don't like to grow on the polyester's water-repelling surface. The second component, chitosan, is found in the shells of crustaceans. It's cheap, readily available, biodegradable and biocompatible, meaning that it won't trigger an immune response. Chitosan has a rough surface similar to the surfaces found inside the body that cells can attach to. The problem is chitosan swells in water, making it weak in wet environments. The researchers combined the fibers at the nanometer scale by first using a technique called electrospinning to draw the materials into nanometer-scale fibers, and then weaving the fibers together. The resulting material has a texture similar to that of the nanosized fibers of the connective tissue that surrrounds human cells.
  [Natural-Synthetic Polyblend Nanofibers for Biomedical Applications, Advanced Materials Early View (Articles online in advance of print) Published Online: 7 May 2009]
  (June 19, 2009)

• Molecular metal chalcogenide complexes act as glue for colloidal nanocrystals
  (NanotechWeb)

  Solution-based processes for semiconductor nanocrystals such as spin or dip coating and inkjet printing are cost-effective ways to make large-area solar cells. However, individual nanocrystals in printed arrays made using these techniques communicate poorly with each other. This is because surface ligands, consisting of bulky, insulating organic molecules, block electric charge transfer from one nanocrystal to another. Researchers have now overcome this challenge by developing a new chemistry that allows coupling of individual nanocrystals into arrays of strongly communicating building blocks. The researchers "glued" colloidal nanocrystals together using a class of compounds called molecular metal chalcogenide complexes. The ligands are more stable and robust than the previously employed organic ligands and do not alter the chemistry of the nanocrystals. They also allow efficient charge transfer between the nanocrystals.
  [Colloidal Nanocrystals with Molecular Metal Chalcogenide Surface Ligands, Science 12 June 2009: Vol. 324. no. 5933, pp. 1417 - 1420 DOI: 10.1126/science.1170524]
  (June 19, 2009)

• Double helix is an electric slide for proteins
  (Physics World)

  

  DNA may contain the blueprint for life but it takes proteins to read the plan and build an organism. The mechanism of this vital biological process has remained a mystery but now researchers are proposing a physical model wherein individual proteins can “slide” freely along DNA strands in search of target sequences. The team envision the process involving ‘DNA-binding proteins’ swarming around the iconic double helix on account of electric attraction — proteins have a net positive charge and DNA has a net negative charge. Miraculously, these proteins can then bind to exactly the right section of the long, coiling DNA so they can carry out vital functions such as copying genetic information and translating genes into templates for protein production. This complex biological set-up was reduced into more general physical shapes. Using Monte Carlo computer simulations, DNA was modelled as a long cylinder, and the protein as one of four solids: a sphere; a cylinder; or a cube or cylinder with a groove carved in one side.
  [Nonspecific DNA-Protein Interaction: Why Proteins Can Diffuse along DNA, Phys. Rev. Lett. 102, 228101 (2009)]
  (June 17, 2009)

• Concrete creep slowed to a crawl
  (Massachusetts Institute of Technology / Eurekalert)

  Resesearchers have for the first time identified what causes the most frequently used building material on earth — concrete — to gradually deform, decreasing its durability and shortening the lifespan of infrastructures such as bridges and nuclear waste containment vessels.They suggest that creep in concrete is caused by the rearrangement of particles at the nano-scale. They explain that concrete creep comes about when nanometer-sized C-S-H particles rearrange into altered densities: some looser and others more tightly packed. They also explain that a third, more dense phase of C-S-H can be induced by carefully manipulating the cement mix with other minerals such as silica fumes.
  [To be published in the Proceedings of the National Academy of Sciences]
  (June 17, 2009)

• Wood converted to scaffolds for bone tissue engineering
  (Royal Society of Chemistry)

  

  Inspired by nature's highly organized hierarchial structures, researchers have used wood to make porous hydroxyapatite scaffolds with structures similar to that of real bone. The scaffolds 'pave the way for realising prosthetic devices which could get closer to the extraordinary performance of human tissues'. They heated the wood to decompose the organic parts that make up most of its weight, leaving behind the carbon template. They reacted the template first with calcium, then oxygen and then carbon dioxide to form calcium carbonate. Finally, they converted it to hydroxyapatite using a phosphate donor. The material keeps its original microstructure, exploiting the unique architectural properties of the wood's cellular make-up. This means cells and blood vessels can grow through the structure and incorporate it into the original bone.
  [From wood to bone: multi-step process to convert wood hierarchical structures into biomimetic hydroxyapatite scaffolds for bone tissue engineering, J. Mater. Chem., 2009, DOI: 10.1039/b900333a]
  (June 17, 2009)

• Microtubes follow directions
  (Chemical & Engineering News)

  
  Credit: Leroy Cronin

  Fabricating microfluidic devices is generally a painstaking process that requires a unique mold or mask for each device configuration. Researchers have now taken a step toward a more flexible approach to device fabrication by developing a way to control, in real time, the growth, direction, and diameter of self-fabricating polyoxometalate (POM) microtubes. POMs are oxo-anion clusters of early transition metals. In a previous study, the researchers observed spontaneous growth of micrometer-scale tubes from a tungstate POM crystal upon immersion in an aqueous solution of a polyaromatic organic cation. The interaction of POM anions with organic cations causes a semipermeable membrane to form around the crystal, and osmotic pressure within the membrane drives microtube growth. The microtubes are uniform in diameter and sufficiently robust to allow the flow of liquid, thereby raising the possibility of their use as channels in microfluidic devices. In their latest paper, they report the development of a method to precisely control, in real time, the direction of microtube assembly with the help of an applied electric field.
  [Real-Time Direction Control of Self Fabricating Polyoxometalate-Based Microtubes, J. Am. Chem. Soc., Article ASAP DOI: 10.1021/ja902684b]
  (June 15, 2009)

• Tunable bandgap engineered in bilayer graphene
  (Lawrence Berkeley National Laboratory / Eurekalert)

  
  Credit: Lawrence Berkeley National Laboratory

  Graphene has no bandgap which greatly limits its uses in nanoscale electronics and photonics. If we could achieve a graphene bandgap, very good transistors can be made. Researchers have now been able to engineer a bandgap in bilayer graphene that can be precisely controlled from 0 to 250 meV. The experiment was conducted at room temperature, requiring no refrigeration of the device. Among the applications made possible by this breakthrough are new kinds of nanotransistors and because of its narrow bandgap nano-LEDs and other nanoscale optical devices in the infrared range. The researcheres made two key decisions that led to their successful attempt to introduce and determine a bandgap in bilayer graphene. The first was to build a two-gated bilayer device, which allowed the team to independently adjust the electronic bandgap and the charge doping. The other key decision the researchers made was to get a better grasp of what was really going on in the device as they varied the voltage. Rather than try to measure the bandgap by measuring the device's electrical resistance, or transport, they decided to measure its optical transmission.
  [Direct observation of a widely tunable bandgap in bilayer graphene, Nature 459, 820-823 (11 June 2009) | doi:10.1038/nature08105]
  (June 15, 2009)

• Nanoparticle lung cancer threat blocked
  (BBC)

  

  Scientists have identified how a type of nanoparticle can cause lung cancer - as welll as how to block the process. The research focused on a class of nanoparticles being widely developed in medicine - polyamidoamine dendrimers (PAMAMs). In tests on cells in the lab, the researchers found the particles cause lung damage by triggering a type of programmed cell death known as autophagic cell death. Autophagy plays a normal part in cell growth and renewal, but over-activity can lead to unwanted cell death. However, the researchers also found autophagy could be blocked by using a drug inhibitor. The findings were confirmed in tests on mice. Animals exposed to PAMAMs showed higher levels of lung inflammation, and higher death rates. But those that were first injected with the inhibitor were less badly affected.
  [PAMAM Nanoparticles Promote Acute Lung Injury by Inducing Autophagic Cell Death through the Akt-TSC2-mTOR Signaling Pathway, Journal of Molecular Cell Biology Advance Access published online on June 10, 2009, doi:10.1093/jmcb/mjp002 ]
  (June 15, 2009)

• Future over-the-counter prostate cancer test kit uses gold nanoparticles
  (University of Central Florida)

  Prostate cancer affects one of every six men and is the second-most common cancer among men in the United States, according to the American Cancer Society. Researchers are now developing an effective, inexpensive test to screen for prostate cancer that would be easy enough to use at home or a local pharmacy. The new technique involves gold nanoparticles, which is first mixed in a solution. The nanoparticles are engineered to attach themselves to cancer-producing proteins related to the type of cancer targeted. When a drop of blood is placed in the solution, the gold nanoparticles seek out the protein. If the protein is present, the gold nanoparticles cluster around it. A dynamic light-scattering instrument is used to look for the clusters. If there are no clusters, there is no cancer-causing protein. During a test, if cancer-producing proteins are detected at a significant level, the consumer would be directed to see a doctor.
  (June 10, 2009)

• Porous hybrid silica nanoparticles target cancer cells
  (Nanowerk)

  
  Credit: J.M. Rosenholm et al. ACS Nano

  Researchers have discovered that the stability of functionalised nanoparticles is crucially dependent on all functional groups present on the surface. Using sensitive nanoscale particle sizing and zeta potential measurement capabilities, they showed that poly(ethylene imine) (PEI) functionalised silica particles made promising candidates for bioapplications. This research has led to the development of a selective nanoparticulate system for cancer cell targeting.
  [Targeting of Porous Hybrid Silica Nanoparticles to Cancer Cells, ACS Nano 3 (2009) 197, DOI: 10.1021/nn800781r]
  (June 10, 2009)

• Raman, nanotechnology approach detects, tracks and kills cancer cells
  (BioOptics World)

  Using Raman spectroscopy, researchers have showed that it is possible not only to monitor and detect nanomaterials moving through the circulation, but also to detect single cancer cells tagged with carbon nanotubes. In a recent paper, they describe a method of detecting, tracking, and killing cancer cells in real time. They injected a single human cancer cell containing carbon nanotube material in the tail vein of a test rat. They were able to follow the circulation of the carbon nanotubes in the blood vessels to the rat's ear, tracking the cell through the rat's blood stream, lymphatic system, and tissue with a Raman spectrometer. So far, nobody has been able to fully understand and study in vivo and in real time how these nanoparticles travel through a living system. The work represents a new approach to cancer treatment beyond surgery, radiation, and chemotherapy. This is promising for the detection and identification of a broad spectrum of various nanoparticles with strong Raman scattering properties, such as cells, bacteria, and even viruses. In a separate paper, the researchers discuss how nanoparticles can tag cancer cells. A laser then heats the nanoparticles, killing the cancer cell.
  [In vivo Raman flow cytometry for real-time detection of carbon nanotube kinetics in lymph, blood, and tissues, Journal of Biomedical Optics 14(02), 021006 (2009); Nanophotothermolysis of multiple scattered cancer cells with carbon nanotubes guided by time-resolved infrared thermal imaging, Journal of Biomedical Optics 14(02), 021007 (2009)]
  (June 9, 2009)

• Biodegradable synthetic resin replaces vital body parts
  (PhysOrg.com)

  
  Credit: University of Twente

  Researchers have developed a new type of resin that can be broken down by the body. This new resin makes it possible to replicate important body parts exactly and make them fit precisely. The resin can be given different properties depending on where in the body it is to be used. Cells can be sown and cultured on these models, so that the tissues grown are, in fact, produced by the body itself. A stereolithograph is a 3D replicating machine with a very high resolution. The way it works is based on the local hardening of a liquid resin with computer-driven light. The resins available for stereolithography so far harden into chemical networks that cannot be broken down. Now, for the first time, researchers have developed a biodegradable resin that can be used for this replicating machine.
  [A poly(d,l-lactide) resin for the preparation of tissue engineering scaffolds by stereolithography, Biomaterials, doi:10.1016/j.biomaterials.2009.03.055]
  (June 9, 2009)

• Polymer membrane filters arsenic from water
  (Technology Review)

  
  Credit: Adam Hart-Davis / Photo Researchers, Inc

  Researchers have developed a new polymer emembrane material that resists problems such as fouling or clogging while also screening out arsenic. The material is based on polymers, hexafluoro alcohols, that are used as a patterning material for manufacturing advanced computer chips. The researchers found that these compounds also make good water filters. The key to the membrane's performance is its pH sensitivity. At high pH, arsenic in the water becomes charged, and the fluorine groups on the polymer, which also become charged, then will repel the toxic chemical. Other membranes can't operate in the very basic conditions needed to ionize arsenic. Depending on the water sample, the filter removes 96 to 99 percent of arsenic.
  (June 9, 2009)

• Thinnest superconducting metal created
  (University of Texas / Eurekalert)

  
  Credit: Ken Shih, The University of Texas at Austin

  A superconducting sheet of lead only two atoms thick, the thinnest superconducting metal layer ever created, has been developed by researchers. In superconductors, electrons move through the material together in pairs, called Cooper pairs. One of the innovative properties of the new sheet is that it confines the electrons to move in two dimensions, or one "quantum channel." Uniquely, the lead remains a good superconductor despite the constrained movement of the electrons through the metal. The researchers used advanced materials synthesis techniques to lay the two-atom thick sheet of lead atop a thin silicon surface. The lead sheets are highly uniform with no impurities.
  [Superconductivity at the Two-Dimensional Limit, Science 5 June 2009: Vol. 324. no. 5932, pp. 1314 - 1317 DOI: 10.1126/science.1170775]
  (June 8, 2009)

• Nanocrystal growth process revealed
  (Royal Society of Chemistry)

  
  Credit: Science

  New research has shed light on precisely how nanocrystals grow, providing key information that could help improve fuel cells of the future. The research team studied the behavior of single platinum nanoparticles in solution. They used transmission electron microscopy (TEM) with a liquid cell, which allows liquids to be observed inside a vacuum. It is almost impossible to make uniform nanoparticles, which means it is important to study one particle at a time to get a real understanding of their behavior, rather than relying on an average. The traditional model for nanocrystal growth is that metal-containing monomers bump into and join with the crystals as they move around in the solution. Recent studies, however, have suggested that nanocrystals merging together also play an important role. Using TEM, the researchers were able to 'watch' both of these mechanisms occurring. Through the combination of these two processes, an initially broad size distribution spontaneously narrow into a nearly monodisperse distribution.
  [Observation of Single Colloidal Platinum Nanocrystal Growth Trajectories, Science 5 June 2009: Vol. 324. no. 5932, pp. 1309 - 1312 DOI: 10.1126/science.1172104]
  (June 8, 2009)

• Graphene may have advantages over copper for future IC interconnects
  (Georgia Tech)

  
  Credit: Raghunath Murali, Georgia Tech

  Researchers have experimentally demonstrated the potential for a new graphene application, replacing copper for interconnects in future generations of integrated circuits. They report detailed analysis of resistivity in graphene nanoribbon interconnects as narrow as 18 nanometers. The results suggest that graphene could out-perform copper for use as on-chip interconnects. Graphene nanowire interconnects on the scale of 20 nanometers shows that their performance is comparable to even the most optimistic projections for copper interconnects at that scale. Under real-world conditions, the new graphene interconnects probably already out-perform copper at this size scale, say the researchers. Beyond resistivity improvement, graphene interconnects would offer higher electron mobility, better thermal conductivity, higher mechanical strength and reduced capacitance coupling between adjacent wires.
  [Resistivity of Graphene Nanoribbon Interconnects, Electron Device Letters, IEEE Publication Date: June 2009 Volume: 30, Issue: 6, 611-613, Digital Object Identifier: 10.1109/LED.2009.2020182]
  (June 5, 2009)

• Lipid-based nanoparticle targets atherosclerosis
  (University of California - Santa Barbara / Eurekalert)

  
  Credit: Peter Allen, UCSB College of Engineering

  Atherosclerosis is one of the leading causes of cardiovascular disease in humans. In atherosclerosis, plaque builds up on the walls of arteries and can cause heart attack and stroke. Researchers have now developed a nanoparticle that can attack plaque in arteries. The nanoparticles in this study are lipid-based collections of molecules that form a sphere called a micelle. The micelle has a peptide, a piece of protein, on its surface, and that peptide binds to the surface of the plaque. The team induced atherosclerotic plaques in mice by keeping them on a high-fat diet. They then intravenously injected these mice with the micelles, which were allowed to circulate for three hours. The results showed that the micelles preferentially targeted those places in the plaques that are prone to rupture.
  [Targeting atherosclerosis by using modular, multifunctional micelles, PNAS, Published online before print June 1, 2009, doi: 10.1073/pnas.0903369106, OPEN ACCESS]
  (June 5, 2009)

• Mineral could be evidence of naturally occurring quasicrystal
  (Scientific American)

  
  Credit: Inductiveload at Wikimedia Commons

  A team of researchers says it has found in a Russian mineral sample the first natural example of a quasicrystal. Numerous versions have been cooked up in the laboratory, but a natural example would indicate that nature's products are more diverse than previously thought. They examined substances chemically similar to quasicrystals that had already been synthesized in the lab. That search led them to khatyrkite, a mineral that had reportedly been found in the Koryak Mountains of Russia. Another khatyrkite-bearing sample was also found to contain granules of an alloy of aluminum, copper and iron that fit the quasicrystal bill. But the origin of such would-be minerals is a point of some contention among petrologists, since aluminum alloys do not form easily by natural processes, because the element reacts with oxygen so readily. The possibility that the quasicrystal and its related materials, including khatyrkite, are of man-made origin needs to be weighed very carefully. Aluminum smelting is one human process that might produce such a substance.
  [Natural Quasicrystals, Science 5 June 2009: Vol. 324. no. 5932, pp. 1306 - 1309 DOI: 10.1126/science.1170827]
  (June 5, 2009)

• Biomimetic hierarchical nanostructures help in nanoscale thermal management
  (PhysOrg.com)

  
  Credit: Nano Letters

  Nanoelectromechanical systems (NEMS) devices have the potential to revolutionize the world of sensors: motion, chemical, temperature, etc. However, taking electromechanical devices from the micro scale down to the nano requires finding a means to dissipate the heat output of this tiny gadgetry. A new study suggests that the solution is to build these devices using a thermal material that naturally dissipates heat from the device's center through a hierarchical branched network of carbon nanotubes. The template for this thermal material's design is a living cell, specifically, the hierarchical protein networks that allow a cell's nucleus to communicate with the cell's outermost regions. The structure now used when designing materials with carbon nanotubes resembles spaghetti. The new study shows that a precise arrangement of carbon nanotubes similar to those found in the cytoskeleton of cells will create a thermal material that effectively dissipates heat, which could prevent a NEMS device from failing or melting.
  [Hierarchical Nanostructures Are Crucial To Mitigate Ultrasmall Thermal Point Loads, Nano Lett., 2009, 9 (5), pp 2065–2072 DOI: 10.1021/nl900399b]
  (June 4, 2009)

• Flexible memristor developed using sol-gel technique
  (NIST / Eurekalert)

  Researchers have found a way to build a flexible memory component out of inexpensive, readily available materials.They took polymer sheetsthe sort that transparencies for overhead projectors are made fromand experimented with depositing a thin film of titanium dioxide, an ingredient in sunscreen, on their surfaces. Instead of using expensive equipment to deposit the titanium dioxide as is traditionally done, the material was deposited by a sol gel process, which consists of spinning the material in liquid form and letting it set, like making gelatin. By adding electrical contacts, the team created a flexible memory switch that operates on less than 10 volts, maintains its memory when power is lost, and still functions after being flexed more than 4,000 times. What's more, the switch's performance bears a strong resemblance to that of a memristor, a component theorized in 1971 as a fourth fundamental circuit element (along with the capacitor, resistor and inductor). A memristor is, in essence, a resistor that changes its resistance depending on the amount of current that is sent through itand retains this resistance even after the power is turned off.
  [A Flexible Solution-Processed Memristor, IEEE Electron Device Letters, Digital Object Identifier: 10.1109/LED.2009.2021418]
  (June 3, 2009)

• Viruses count quantum dots for improved cancer imaging
  (Royal Society of Chemistry)

  
  Credit: J. Mater. Chem.

  Measuring quantum dot (QD) concentrations using viruses could lead to improved cancer imaging, according to a new report. Quantum dots have been used in a wide range of biological applications, from tissue imaging to drug delivery. Accurately measuring their concentration is vital for these fields to advance. The researchers used phage display - a method that uses a library of viruses called phages, each with a different peptide exposed on their surface - to measure QDs. They coated QDs with one of three different compounds - mercaptoacetic acid (MAA), mercaptoundecanoic acid or bovine serum albumin - and attached them to gelatin-coated substrates. They exposed the QDs to a phage library and some of the surface peptides bound to the QDs. They then washed away the unbound viruses and used an enzyme-linked immunosorbant assay to analyse the bound ones. They found one peptide sequence that bound only to MAA-coated QDs and showed that they could use it to measure the concentrations of MAA-coated QD solutions ranging from 10 nanomolar to one micromolar.
  [Quantification of quantum dots using phage display screening and assay, J. Mater. Chem., 2009 DOI: 10.1039/b906466d]
  (June 3, 2009)

• A billion-year hard drive?
  (Science)

  
  Credit: A. Zettl, UC Berkeley

  As our technological society has progressed, long term storage and retrieval of data has actually grown more difficult. Magnetic patterns embedded in a computer disk in commonly used magnetic storage degrade steadily over time. Seeking something more permanent, a team of physicists and materials scientists has looked to the nanoscale. They describe a technique of placing a single iron crystal only a few billionths of a meter wide inside a hollow carbon nanotube. Like diamonds, nanotubes are among the most stable structures in existence. Once inserted into the tubes, the iron nanocrystals act as data bits, physically sliding from one end of the tube to the other in response to an electric current and in the process registering either a "1" or a "0" in the binary language of computers.
  [Nanoscale Reversible Mass Transport for Archival Memory, Nano Lett., 2009, 9 (5), pp 18351838]
  (June 1, 2009)

• Incandescent light bulbs made super-efficient using femtosecond laser
  (University of Rochester)

  A femtosecond laser can turn regular incandescent light bulbs into power-sippers, according to a new study. The laser process used on the tungsten filament in the bulb creates a unique array of nano- and micro-scale structures on the surface of the tungsten filament and theses structures make the tungsten become far more effective at radiating light. The process could make a light as bright as a 100-watt bulb consume less electricity than a 60-watt bulb. The process can be used to tune the color of the light as well. The researchers can change the overall radiated spectrum so that the tungsten, which normally radiates a yellowish light, could radiate a more purely white light. They have even been able to make a filament radiate partially polarized light, which until now has been impossible to do without special filters that reduce the bulb's efficiency. By creating nanostructures in tight, parallel rows, some light that emits from the filament becomes polarized.
  [To be published in Physical Review Letters]
  (June 1, 2009)

• Atom trapping by nanoscale plasmons proposed
  (NanotechWeb)

  
  Credit: D Chang, Caltech

  A new way to interface atoms with nanoscale systems has been proposed. The technique, if realized experimentally, could be used to connect trapped atoms with nanophotonic devices. The proposed method allows a single atom to be trapped near a metallic nanotip within a region just a few nanometres in size. This trapped atom can be brought to within tens of nanometres of other surfaces. The technique could allow a trapped atom to be directly coupled to nanosystems, such as micro and nano-photonic devices, or charged or magnetized quantum systems. The atom could also be optically detected or manipulated with high efficiency using optical waves (surface plasmons) guided along the nanotip surface. The method is based on a common trapping technique for atoms that relies on the fact that light causes atoms to polarize or acquire a dipole moment. The energy associated with this atomic polarization is minimized when the atom moves to a region where the light field is weakest or strongest, depending on the conditions. A laser beam is used to illuminate a sharp metallic nanotip that acts as a "lightning rod", which strongly enhances the laser field and causes large field variations near the end of the tip.
  [Trapping and manipulation of isolated atoms using nanoscale plasmonic structures, arXiv:0905.3722v1 [quant-ph]]
  (June 1, 2009)

• Silver nanoparticles prevent blood clots like aspirin
  (Science)

  
  Credit: S. Shrivastava et al., ACS Nano

  Millions of people around the world are prone to dangerous blood clots. Now researchers have had early success with a new way to prevent them--and the strokes, heart attacks, and pulmonary embolisms they cause -- using silver nanoparticles. The nanoparticles were shown to stop platelets from clinging together in laboratory strains of mice. The researchers injected mice with blood that was genetically engineered to be prone to clotting and then administered the nano-silver. The nano-silver particles inhibited the ability of the sticky platelet surface proteins to bind these cells together into aggregates, much like adding sand to adhesive tape reduces its ability to stick. This helps the nano-silver to keep platelets in an inactive state. The nanoparticles were "far more effective" than current therapies. At the same time, the nanoparticles don't interfere with the other proteins in the blood that help form clots, as do conventional anticoagulants, so the danger of uncontrolled bleeding is reduced.
  [Characterization of Antiplatelet Properties of Silver Nanoparticles, ACS Nano, Article ASAP DOI: 10.1021/nn900277t Publication Date (Web): May 4, 2009]
  (May 29, 2009)

• Bright white light from organic LEDs
  (Optics.org)

  Researchers have created the first LED from organic materials that is more efficient than traditional lighting. One promising way of creating white light is to coat an LED with phosphor, which converts monochromatic light into red, green and blue light. The drawback until now has been a lack of efficiency; 80% of the photons generated remain trapped in the LED emission substrate and the surrounding phosphor. Leo and his team have overcome this problem by optimizing the coupling between these phosphor and polymer layers. By integrating blue, green and red phosphor into the heart of the emission layer, they have created a system that allows significantly more photons to escape. The team reports a power efficiency of 90 lm/W, with a potential maximum of 124 lm/W. Until now, most organic LEDs showed an efficiency of just 44 lm/W.
  [White organic light-emitting diodes with fluorescent tube efficiency, Nature 459, 234-238 (14 May 2009) | doi: 0.1038/nature08003]
  (May 29, 2009)

• Gallium-doped germanium exhibits superconductivity
  (Forschungszentrum Dresden-Rossendorf / Science Centric)

  Scientists have been able to produce superconducting germanium for the first time. Germanium samples were doped with about six gallium atoms per 100 germanium atoms. The scientists showed that the doped germanium layer of only sixty nanometres thickness became superconducting. The gallium doped germanium samples became superconducting at about 0.5 Kelvin and exhibit a surprisingly high critical magnetic field with respect to the temperature.
  [Superconducting State in a Gallium-Doped Germanium Layer at Low Temperatures, Phys. Rev. Lett. 102, 217003 (2009)]
  (May 28, 2009)

• Superplastic salt nanowires formed
  (Royal Society of Chemistry)

  
  Credit: Nano Letters

  Common table salt - normally a brittle crystalline material - can be pulled into nanowires that will extend by more than twice their own length without breaking, according to a new report. Researchers were investigating water adsorption onto salt crystals using an interfacial force microscope (IFM) to probe the salt surface when they stumbled upon their discovery. Surprisingly, the salt not only became ductile but the wires were also superplastic. This unusual property is more normally associated with metals and certain ceramics, rather than ionic crystals like salt. The wires can also be compressed back into the crystal, but do tend to bend and buckle.
  [Letter Superplastic Nanowires Pulled from the Surface of Common Salt, Nano Lett., Article ASAP DOI: 10.1021/nl9004805 Publication Date (Web): May 21, 2009]
  (May 28, 2009)

• Electric field acts as a switch in a multiferroic
  (Lawrence Berkeley National Laboratory / Eurekalert)

  
  Credit: Chan-Ho Yang, Berkeley Lab/UC Berkeley

  Multiferroics are potential cornerstones in future magnetic data storage and spintronic devices provided a simple and fast way can be found to turn their electric and magnetic properties on and off. A researcher group working with a prototypical multiferroic have successfully demonstrated just such a switch -- electric fields. Using electric fields, they were able to create, erase and invert pn junctions in a calcium-doped bismuth ferrite film. They first doped bismuth ferrite with calcium acceptor ions, which are known to increase the amount of electric current that materials like bismuth ferrite can carry. The addition of the calcium ions created positively-charged oxygen vacancies. When an electric field was applied to the calcium-doped bismuth ferrite films, the oxygen vacancies became mobile. The electric field "swept" the oxygen vacancies towards the film's top surface, creating an n-type semiconductor in that portion of the film, while the immobile calcium ions created a p-type semiconductor in the bottom portion. Reversing the direction of the electric field inverted the n-type and p-type semiconductor regions, and a moderate field erased them.
  [Electric modulation of conduction in multiferroic Ca-doped BiFeO3 films, Nature Materials 8, 485 - 493 (2009) Published online: 26 April 2009 | doi:10.1038/nmat2432]
  (May 27, 2009)

• Nanofountain probe injects nanodiamonds
  (Royal Society of Chemistry)

  
  Credit: Small

  Nanodiamonds have several unique properties that make them attractive in biomedicine: they have a high surface area for their volume, they are bio-compatible, and they are able to steadily release drugs that have been attached to them. However, scientists have found it challenging to control the placement of nanodiamonds precisely, which is crucial for creating nanodiamond-based devices or for injecting nanodiamonds into cells. A team of researchers has now created a tool that they say offers more control over nanodiamond placement. It consists of the probe of an atomic force microscope that has been modified to house a reservoir filled with an 'ink' of nanodiamonds in solution, 'just like a fountain pen.'
  [Nanofountain-Probe-Based High-Resolution Patterning and Single-Cell Injection of Functionalized Nanodiamonds, Small, Early View (Articles online in advance of print) Published Online: 12 May 2009]
  (May 26, 2009)

• Nanoscale interleukin-12p70 coatings prevent open fracture associated infection
  (Biomaterials)

  Bacterial infections that are resistant to conventional antibiotics are common in hospital and military settings today. Antibiotic resistance and infection caused by Acinetobacter baumannii have been particularly challenging for healthcare providers managing injured U.S. service members evacuated from Iraq and Afghanistan. It is therefore crucial to develop non-antibiotic approaches or novel antibacterial agents for infection prevention. Recently, a new approach, stimulating the body’s natural defense system by developing interleukin-12p70 (IL-12p70) nanocoatings at the implant/tissue interface, has been developed. The IL-12p70 nanocoating, prepared via electrostatic layer-by-layer self-assembly nanotechnology, was found to substantially decrease open fracture associated infections in an osteomyelitis rat model. The developed technology has also been shown to be advantageous over traditional treatments. The developed approach might be a revolutionary step toward preventing open fracture associated infections using a non-antibiotic approach.
  [Multilayer polypeptide nanoscale coatings incorporating IL-12 for the prevention of biomedical device-associated infections, Biomaterials, Volume 30, Issue 13, May 2009, Pages 2552-2558]
  (May 26, 2009)

• Silver boosts magnetic properties of FePt nanoparticles
  (NanotechWeb)

  
  Credit: L. Castaldi

  Iron-platinum nanoparticles are ideal for making high-density recording media, high-performance nanocomposite magnets and in integrated circuits. This is because an ordered phase in the material has a high anisotropy constant, which prevents superparamagnetism at room temperature for particles as small as 3 nm. Researchers have now engineered a silver/iron-platinum system in which the hard magnetic properties of the iron-platinum alloy are enhanced. Improvement is seen at temperatures as high as 500 C, which means that the technique can be used in integrated circuitry technology. The researchers used thermal evaporation. They first deposited silver with a thickness of 1.5 nm onto a silica substrate at 500 C and then co-deposited iron-platinum at the same temperature. A coercivity enhancement of as much as 40% was seen and some samples were annealed to further improve this figure. Thinner samples showed an even higher enhancement of more than 100% with and without annealing.
  [Enhanced magnetic properties of FePt nanoparticles codeposited on Ag nanoislands, J. Appl. Phys. 105, 093914 (2009); DOI:10.1063/1.3116558 ]
  (May 26, 2009)

• Stronger material for filling dental cavities
  (PhysOrg.com)

  
  Credit: NIST

  Dentists increasingly are using white fillings made from plastic, rather than silver dental fillings. Those traditional fillings contain mercury, which has raised health concerns among some consumers and environmental issues in its production. However, many plastic fillings contain controversial ingredients (such as BisGMA) linked to premature cracking of fillings and slowly release bisphenol A, a substance considered as potentially toxic to humans and to the environment. Dcientists have now developed a dental composite that does not contain these ingredients. Instead, it uses bile acids, natural substances produced by the liver and stored in the gallbladder that help digest fats. The researchers showed in laboratory studies that the bile acid-derived resins form a hard, durable plastic that resists cracking better than existing composites.
  [New Dental Composites Containing Multimethacrylate Derivatives of Bile Acids: A Comparative Study with Commercial Monomers, Applied Materials & Interfaces, 2009, 1 (4), pp 824832 DOI: 10.1021/am8002395]
  (May 22, 2009)

• Nanodevice converts photons into mechanical energy
  (Science)

  
  Credit: Science

  Researchers have built a nanoscale device that vibrates when struck by incoming laser light. The contraption is sensitive to the energy of a single photon. They fabricated a pair of planks only a few hundred nanometers wide out of silicon microchip material. Then they chemically etched a series of holes in each of them. The team calls the device a "zipper cavity," because of its resemblance to a zipper. The holes channel and capture a laser beam's energy and the device vibrates. The frequency of the vibrations depends on the intensity of the laser light bombarding it.
  [A picogram- and nanometre-scale photonic-crystal optomechanical cavity, Nature advance online publication 13 May 2009 | doi:10.1038/nature08061]
  (May 21, 2009)

• Gold nanorods boost capacity of next-generation optical disks
  (Nature News)

  
  Credit: Nature

  Traditional DVDs and Blu-ray optical disks store data in two dimensions and there's been a recent push to increase their capacity by creating multi-layered disks that store data across three dimensions. Researchers are now stepping into hyperspace, by encoding information in two new dimensions — the wavelength and polarization of the laser light used to write the data. The key was to find a material for the disk that could store this extra information. The ideal material contains gold, rod-shaped nanoparticles of different sizes and orientations. When polarized light, such as that emitted from a laser, is fired onto this material, it 'melts' only the rods whose orientation matches the direction of polarization, causing them to become spherical. "Polarized light only 'sees' and records on a subset of the nanorods. Change the polarization and you can record on the same volume as though it is a whole new recording medium." The team has demonstrated that using two polarizations and three colours, one can pack 1.6 terabytes of data in one DVD-sized disk. A Blu-ray disk, by comparison, can store around 50 gigabytes. Adding an extra dimension by using another polarization could ramp that up further to 7.2 terabytes.
  [Five-dimensional optical recording mediated by surface plasmons in gold nanorods, Nature 459, 410-413 (21 May 2009) | doi:10.1038/nature08053]
  (May 21, 2009)

• Writing patterns on carbon nanotubes with polymer chains
  (PhysOrg.com)

  
  Credit: Christopher Li, Drexel University

  It has been difficult to create repeating, regular patterns onto individual nanotubes, a task necessary for a key goal of nanoelectronics which is patterning transistors directly onto nanotube surfaces. A research group now has successfully used polymers to create well defined patterns onto single-walled carbon nanotubes. The group chose a block copolymer of polyethylene (PE) and polyethylene oxide (PEO). They deposited a single-walled carbon nanotube solution onto a pre-fabricated carbon-coated grid. The nanotubes lined up on the grid surface and the group decorated the nanotubes with a solution containing the copolymer. The result is a copolymer/nanotube hybrid. The copolymers formed worm-like structures with alternating dark and bright stripes (corresponding to the PEO and PE blocks, respectively). The consistent spatial orientation of the stripes, and the size of the worms, averaging 50 nanometers wide and one micrometer long, indicate that the polymer chains forming the stripes had aligned with the long axes of the nanotubes; the stripes, then, cut across the nanotubes perpendicularly.
  [Alternating patterns on single-walled carbon nanotubes, Nature Nanotechnology Published online: 26 April 2009 | doi:10.1038/nnano.2009.91]
  (May 20, 2009)

• Carbon atomic wires from graphene
  (Physics)

  
  Credit: Alan Stonebraker, Physics

  Researchers show that using a high-energy electron beam, they can transform graphite into graphene, and further into separate strings of carbon atoms. There have been only scarce reports on carbon atom chains, and this new approach adds an avenue to produce new all-carbon electronic nanostructures. To make the structures, they manipulate the electron beam in a transmission electron microscope. They start with a small flake of graphite imaged by means of the electron beam optics. By focusing a high-energy, high-current beam on a spot on the flake, they remove carbon atoms and thin the flake until they expose a single atomic carbon layer. Further irradiation at high energy and intensity produces two neighboring holes in the graphene layer, separated by a graphene nanoribbon, which they can continue to thin with more irradiation. The researchers argue that the energy of the edge states of the ribbon is so much higher than those at the center of the ribbon that the edge atoms will be preferentially removed in the process. At the last stage of narrowing the nanoribbon, when the two edges come together, the ribbon can be seen to break up into two parallel single-atom strands. The observed chains are longer than what has been previously observed, up to 2.1 nm, or 16 carbon atoms in a row.
  [Deriving Carbon Atomic Chains from Graphene, Phys. Rev. Lett. 102, 205501 (2009)]
  (May 19, 2009)

• Hydrogen bonds collapse single polymer chains into nanoparticles
  (Chemical & Engineering News)

  
  Credit: E. W. Meijer et al., JACS

  Borrowing from nature's strategy of using intramolecular interactions to fold and unfold proteins, scientists have created the first examples of single chains of synthetic polymers that use hydrogen bonding to reversibly fold themselves into well-defined nanoparticles. Previously only biopolymers such as proteins and nucleic acids were capable of performing such ordered folding. They fashioned the nanoparticles from poly(norbornene) diblock copolymers in which the minor block has either a urea or urethane pendant group containing an ureidopyrimidinone moiety. When the researchers shine ultraviolet light on dilute solutions of the polymers, a nitrophenyl protecting group drops off the ends of the pendant groups, freeing the ureidopyrimidinones to engage in hydrogen bonding that forms the nanoparticles, which are approximately 20 nm in diameter. Adding a little acid disrupts the hydrogen bonds and permits the polymer chains to expand back to their original random coil form. When the researchers cast films of the nanoparticles, they observed that the nanoparticles can organize into a cross-linked network under the right conditions, just as some proteins can aggregate into large structures such as fibrils. The ability to control the internal structure of the nanoparticles and their aggregation into organized supramolecular structures in thin films without establishing permanent covalent bonds could open up vast new possibilities in materials science and nanotechnology.
  [Metastable Supramolecular Polymer Nanoparticles via Intramolecular Collapse of Single Polymer Chains, J. Am. Chem. Soc., Article ASAP DOI: 10.1021/ja901687d Publication Date (Web): April 30, 2009]
  (May 18, 2009)

• Implantable device offers continuous cancer monitoring
  (MIT)

  
  Credit: Michael Cima, MIT

  Surgical removal of a tissue sample, a biopsy, is now the standard for diagnosing cancer. Biopsies are accurate but only offer a snapshot of the tumor at a single moment in time. Monitoring a tumor for weeks or months after the biopsy, tracking its growth and how it responds to treatment, would be much more valuable. Researchers have now developed the first implantable device that can do just that. Their device successfully tracked a tumor marker in mice for one month. In the study, human tumors were transplanted into mice, and the researchers then used the implants to track levels of human chorionic gonadotropin, a hormone produced by human tumor cells. The cylindrical, 5-millimeter implant contains magnetic nanoparticles coated with antibodies specific to the target molecules. Target molecules enter the implant through a semipermeable membrane, bind to the particles and cause them to clump together. That clumping can be detected by MRI (magnetic resonance imaging). The device is made of polyethylene, commonly used in orthopedic implants. The semipermeable membrane, which allows target molecules to enter but keeps the magnetic nanoparticles trapped inside, is made of polycarbonate.
  [Implantable diagnostic device for cancer monitoring, Biosensors and Bioelectronics, 2009, doi:10.1016/j.bios.2009.04.010]
  (May 15, 2009)

• Holography generates nanoporous photonic crystals
  (Royal Society of Chemistry)

  
  Credit: Hsiao et al.

  A polar solvent is the key to making polymeric photonic crystals that could be used as biological sensors, say scientists involved in a new study using holographic photopatterning to make photonic crystals. They mixed formamide, a highly polar solvent, with a non-polar solution of monomers and surfactant. The formamide formed emulsion droplets within the solution and the mixture was sandwiched between two glass slides. They shone a laser through a prism on to the slides, which created a pattern of incident and reflected beams. In the pattern's bright regions, the monomers polymerised, driving the formamide droplets into the dark regions. After switching off the laser, the team opened the sandwich to evaporate the formamide leaving behind a polymeric film with a periodic structure.
  [Nanoporous polymeric photonic crystals by emulsion holography, J. Mater. Chem., 2009 DOI: 10.1039/b823247d]
  (May 15, 2009)

• Two metals better than one for fuel cell catalysts
  (Royal Society of Chemistry)

  
  Credit: Science

  Proton-exchange membrane (PEM) systems are promising fuel cell technologies, but they require rare metal catalysts. In a new study, scientists have reported a dramatic improvement in the activity of catalytic nanoparticles destined to replace platinum in such fuel cells. They have developed bimetallic 'nanodendrites' are more than twice as effective than current state-of-the-art platinum catalysts and could help make future fuel cells more economically viable. The new catalyst consists of platinum 'arms' anchored to a palladium core. These arms increase the surface area of the precious metal available for the oxygen reduction reaction (ORR) in a fuel cell and thus could substantially reduce the amount of catalyst needed.
  [Pd-Pt Bimetallic Nanodendrites with High Activity for Oxygen Reduction, Science, 2009, DOI: 10.1126/science.1170377]
  (May 15, 2009)

• Core structure suppresses blinking in quantum dots
  (Chemical & Engineering News)

  
  Credit:Ted Palwicki

  A team of scientists has synthesized quantum dots that are "nonblinking," in that they emit light steadily. Blinking is a hallmark of fluorescent single molecules and nanometer-scale crystals; it occurs because the luminescence intermittently turns off even with continuous excitation. Excited quantum dots get rid of their extra energy through radiative processesby emitting lightor nonradiative processes. The team eliminated the blinking by making quantum dots whose compositions gradually change from the center to the shell. They layered ZnSe on top of a CdSe core, annealed the layers, and deposited additional ZnSe around it. The process generated a ternary core with a radial composition gradient that smoothed the particle's potential energy function and made nonradiative processes less efficient. However, the nonblinking comes with unusual spectral behavior. Quantum dots usually have a single, sharp emission peak. The new quantum dots, in contrast, have multiple peaks in their emission spectra.
  [Non-blinking semiconductor nanocrystals, Nature advance online publication 10 May 2009 | doi:10.1038/nature08072]
  (May 14, 2009)

• Smallest incandescent lamp uses single C-nanotube
  (Univ. California, Los Angeles | e! Science News)

  A research team has created the world's smallest incandescent lamp, using a filament made from a single carbon nanotube that is only 100 atoms wide, in an effort to explore the boundary between thermodynamics and quantum mechanics two fundamental yet seemingly incompatible theories of physics. To the unaided eye, the filament is completely invisible when the lamp is off, but it appears as tiny point of light when the lamp is turned on. With less than 20 million atoms, the nanotube filament is both large enough to apply the statistical assumptions of thermodynamics and small enough to be considered as a molecular that is, quantum mechanical system.
  [Probing Planck's Law with Incandescent Light Emission from a Single Carbon Nanotube, Phys. Rev. Lett. 102, 187402 (2009)]
  (May 14, 2009)

• Nitrogen n-dopes graphene
  (NanotechWeb)

  It is relatively easy to p-dope graphene using adsorbates and oxygen groups on edges, but for real-world applications, scientists need to be able to make n-doped material too. This is more difficult because special strategies are needed. A research team has now shown that graphene can be n-doped through high-power electrical joule heating in ammonia gas. The high power causes the material to heat up to hundreds of degrees and the graphene edges/defect sites (which are more reactive) start to react with the ammonia gas to form carbonnitrogen groups. The researchers confirmed the formation of carbonnitrogen species in the thermally annealed graphene using X-ray photoelectron spectroscopy and nanoscale secondary ion mass spectroscopy. They then made an n-type graphene FET that operates at room temperature.
  [N-Doping of Graphene Through Electrothermal Reactions with Ammonia, Science 8 May 2009: Vol. 324. no. 5928, pp. 768 - 771 DOI: 10.1126/science.1170335]
  (May 14, 2009)

• Weak light beam flips magnetization in magnetic semiconductor
  (Physical Review Focus)

  
  Credit: Phys. Rev. Lett..

  A research team has showed that a surprisingly feeble light beam can flip zeros to ones and vice versa, in a special magnetic layer. Although currently limited to very low temperatures, the apparently new effect might one day be extended to improve data storage. They grew a thin, crystalline layer of the common semiconductor gallium arsenide but replaced about one percent of the gallium atoms with the magnetic atom manganese. At temperatures below about 25 Kelvin, this layer acts as a ferromagnet: the magnetic moments on different manganese atoms point in the same direction, either up from the surface or down into it. The magnetization direction persists even when the researchers apply an opposing magnetic field, as long as the field does not exceed the coercive field. But when the team focused the light from a standard red laser on the film, the magnetization in the illuminated spot changed direction to match the magnetic field-- opposite to the rest of the film. The light did not change the strength of the magnetization, the team found, but instead reduced the field strength needed to flip it.
  [Nonthermal Photocoercivity Effect in a Low-Doped (Ga,Mn)As Ferromagnetic Semiconductor, Phys. Rev. Lett. 102, 187401
  (issue of 8 May 2009)]
  (May 12, 2009)

• DNA twisted into boxes
  (Nature News)

  
  Credit: Ebbe Sloth Andersen

  Researchers have created miniscule DNA strongboxes measuring just 30 nanometres on each side. The boxes, which can be unlocked with a gene 'key', could be used for drug delivery or as sensors. The boxes are the latest novelty to emerge from 'DNA origami', the technique by which researchers build structures out of DNA. They use oligonucleotides, short snippets of nucleic acid bearing genetic information, to fold longer strands of DNA into a complex structure. Each box is large enough to hold a single ribosome the cell's machine for making proteins. First, the researchers wrote a computer program that would determine what genetic sequences were needed to make their box. Then, they bought the oligonucleotides from suppliers and mixed them with the long DNA strands. The snippets went to work, weaving each strand into six walls and then stitching the walls together. According to the scientists, it takes only an hour or two for billions of boxes to form by themselves. The computer program used in the study should allow researchers to make nearly any structure they can imagine out of DNA.
  [Self-assembly of a nanoscale DNA box with a controllable lid, Nature 459, 73-76 (7 May 2009) | doi:10.1038/nature07971]
  (May 12, 2009)

• Polymers indicate imminent failure by changing color
  (Chemical & Engineering News)

  
  Credit: D. Davis et al., University of Illinois at Urbana-Champaign

  A new polymer changes color when stressed to the point of mechanical failure. The color change occurs by the addition of spiropyran molecules that undergo electrocyclic ring-opening in response to mechanical force. The resulting ring-opened merocyanine molecules are brightly colored, producing red or purple hues in the polymer, depending upon how the indicator molecule is covalently linked to the polymeric structure. The spiropyran essentially undergoes "a force-induced reaction inside of a solid structural polymer. It's a selective covalent bond cleavage that occurs long before there is any backbone cleavage" of the polymer itself. Force-sensitive molecules, known as mechanophores, have been added to polymers in solution before, but this is the first time they've been incorporated in solid polymers. Such a material could be used as a damage sensor that enables researchers to assess the effects of stress on polymeric materials before they fail.
  [Force-induced activation of covalent bonds in mechanoresponsive polymeric materials, Nature 459, 68-72 (7 May 2009) | doi:10.1038/nature07970]
  (May 12, 2009)

• Iron-arsenic superconductors in class of their own
  (U.S. DOE Ames Laboratory on e! Science News)

  Researchers have experimentally demonstrated that the superconductivity mechanism in the recently-discovered iron-arsenide superconductors is unique compared to all other known classes of superconductors. The research has shown that electron pairing in iron-arsenides is likely to be very different when compared to other types of known superconductors. A weak magnetic field penetrates only a narrow region at a superconductor's surface. The depth of this region is known as the London penetration depth. The variation of the London penetration depth with temperature depends on the superconducting gap structure and is already generally agreed upon in most other known classes of superconductors. In conventional superconductors the class made up of periodic table elements, including lead and niobium this dependence is exponential at low temperatures. In the high-temperature cuprate superconductors, the relationship is linear, and in magnesium-diboride superconductors the dependence is exponential, but requires two distinct superconducting gaps to explain the data in a full temperature range. In contrast, it was found that iron-arsenide superconductors exhibit a power-law almost quadratic temperature variation of penetration depth.
  [Unconventional London Penetration Depth in Single-Crystal Ba(Fe0.93Co0.07)2As2 Superconductors, Phys. Rev. Lett. 102, 127004 (2009); London penetration depth in single crystals of Ba(Fe1−xCox)2As2 spanning underdoped to overdoped compositions, Phys. Rev. B 79, 100506 (2009)]
  (May 1, 2009)

• Chromophore-nanotube hybrid devices detect complete visible spectrum
  (Sandia National Laboratories)

  
  Credit: Sandia National Labs.

  Researchers have created the first carbon nanotube device that can detect the entire visible spectrum of light. Earlier efforts using an individual nanotube were only able to detect light in narrow wavelength ranges at laser intensities. The new study found that their nanodetector was orders of magnitude more sensitive, down to about 40 W/m2—about 3 percent of the density of sunshine reaching the ground. To construct a nanoscale color detector, the researchers took inspiration from the human eye. To construct the device, the group first had to create a transistor made from a single carbon nanotube. They deposited carbon nanotubes on a silicon wafer and then used photolithography to define electrical patterns to make contacts. In the final piece, they synthesized molecules to create three types of chromophores that respond to either the red, green, or orange bands of the visible spectrum. They immersed the wafer in the dye solution and waited a few minutes while the chromophores attached themselves to the nanotubes.
  [Color Detection Using Chromophore-Nanotube Hybrid Devices, Nano Lett., 2009, 9 (3), pp 1028–1033 DOI: 10.1021/nl8032922]
  (May 1, 2009)

• Invisibility cloaks go optical
  (Physics World)

  Two independent groups report having demonstrated invisibility cloaks that operate for light at optical wavelengths. One group describe the first demonstration of a cloak that can disguise objects from light in the near infrared to the far red. In their device, the metamaterial is an array of 50 nm–diameter silicon posts on a silicon–dioxide substrate, and the mirror is a textured pattern known as a distributed Bragg reflector (DBR). The device cloaks at short optical wavelengths, from 1975 nm, which is in the near infrared, to 1025 nm, which borders on the red. The second group described a cloak for just the near infrared. In this device, the metamaterial is an array of 110 nm–diameter holes in silicon dioxide, and the mirror is made from gold.
  [Cloaking at Optical Frequencies, arXiv:0904.3508v1 [physics.optics]; Dielectric Optical Cloak, arXiv:0904.3602v1 [physics.optics]]
  (April 30, 2009)

• Nanowire forests act as self-selective chemical connectors
  (NanotechWeb)

  
  Credit: A Javey, Univ. California, Berkeley

  A new type of chemical connector based on hybrid inorganic/organic nanowire forests has been invented. The connector can be miniaturized to nanoscale dimensions without losing its binding properties – something that is impossible with other such devices. Conventional connectors, such as buttons, Velcro and zips, typically rely on mechanical interactions and mate interlocking to join components together. In contrast, the new nanowire connectors utilize chemical interactions. Not only can these devices be reduced to nanoscale dimensions without losing their sticking power, they also have identical mates, which makes them "unisex". The team employed germanium NW forests measuring around 20–30 nm in diameter and 30 µm in length as the backbone of the chemical connectors to make the nanofibrillar structures. Thanks to their high Young's modulus, the structures do not collapse or aggregate.
  [Hybrid Core−Shell Nanowire Forests as Self-Selective Chemical Connectors, Nano Lett., Article ASAP DOI: 10.1021/nl900343b Publication Date (Web): April 24, 2009]
  (April 30, 2009)

• Metal ions yield threaded molecules
  (Royal Society of Chemistry)

  
  Credit: JACS

  A simple method to synthesise tricky '[3]rotaxane' molecules has been developed for potential applications in intelligent materials and molecular machines. The method, which uses metal ions as a template, should be able to provide high yields of [3]rotaxane and other threaded species. Metal ions were found to make the synthesis of these double-threaded [3]rotaxanes straightforward. The scientists take ring and string molecules and introduce cobalt (II) ions, which bonds to the molecules in such a way that two strings both thread through a single ring. In the next step they perform a 'stoppering reaction' to add large molecular groups to the ends of the strings, thereby making them dumbbell-shaped and preventing the rings from slipping off. In the final step the central metal ions are reacted away, leaving pure, double-threaded [3]rotaxane molecules.
  [Passing Two Strings through the Same Ring Using an Octahedral Metal Center as Template: A New Synthesis of [3]Rotaxanes, J. Am. Chem. Soc., Article ASAP DOI: 10.1021/ja809267z Publication Date (Web): April 22, 2009]
  (April 29, 2009)

• Heat transfer, bond strength of materials linked
  (e! Science News)

  
  Credit: Rahul Godawat
  Rensselaer Polytechnic Inst.

  The speed at which heat moves between two materials touching each other is a potent indicator of how strongly they are bonded to each other, according to a new study. The study also showed that this flow of heat from one material to another, in this case one solid and one liquid, can be dramatically altered by "painting" a thin atomic layer between materials. Changing the interface fundamentally changes the way the materials interact. The researchers used extensive molecular dynamics simulations to measure the heat flow between a variety of solid surfaces and water. They simulated a broad range of surface chemistries and showed that thermal conductance, or how fast heat is transferred between a liquid and a solid, is directly proportional to how strongly the liquid adhered to the solid.
  [How Wetting and Adhesion Affect Thermal Conductance of a Range of Hydrophobic to Hydrophilic Aqueous Interfaces, Phys. Rev. Lett. 102, 156101 (2009)]
  (April 28, 2009)

• Self-healing concrete for safer, more durable infrastructure
  (e! Science News)

  A recently developed concrete material can heal itself when it cracks. No human intervention is necessary---just water and carbon dioxide. A handful of drizzly days would be enough to mend a damaged bridge made of the new substance. Self-healing is possible because the material is designed to bend and crack in narrow hairlines rather than break and split in wide gaps, as traditional concrete behaves. In the lab, self-healed specimens recovered most if not all of their original strength after researchers subjected them to a 3 percent tensile strain. It was found that cracks must be kept below 150 micrometers, and preferably below 50, for full healing. To test the healed concrete, the researchers used resonant frequency measurements to determine the stiffness and strength before and after inducing the cracks.
  [Autogenous healing of engineered cementitious composites under wetdry cycles, Cement and Concrete Research, Volume 39, Issue 5, May 2009, Pages 382-390, doi:10.1016/j.cemconres.2009.01.013]
  (April 28, 2009)

• Bendy, twistable polymer could improve oil refining
  (Royal Society of Chemistry)

  
  Credit: Li et al., Chem. Commun.

  A bendy polymer that can recognise and separate aromatic hydrocarbons from aliphatic mixtures has been developed. Researchers built the porous 3D polymer using a flexible 1D polymer made from metal units bound to salen ligands. The resulting structure bends and twists when its polymer chains stretch, triggered by guest molecules entering or leaving the structure. In this case, the guests are the aromatic compounds. The structure's flexibility and the host-guest interactions within its hydrophobic channel allow it to bind to and separate these compounds from aliphatic mixtures. In the refinery process, separating aromatic hydrocarbons from aliphatic hydrocarbon mixtures is challenging, and this polymer fulfills this need.
  [Selective binding and removal of organic molecules in a flexible polymeric material with stretchable metallosalen chain,Chem. Commun., 2009, 2118 DOI: 10.1039/b901574d]
  (April 27, 2009)

• Nano-mechanical sensors wired by photonics
  (Yale University at Eurekalert)

  
  Credit: Li, Pernice,Tang, Yale University

  Researchers have demonstrated silicon-based nanocantilevers, smaller than the wavelength of light, that operate on photonic principles eliminating the need for electric transducers and expensive laser setups in nanoelectromechanical system (NEMS) devices. In NEMS, cantilevers are the most fundamental mechanical sensors. These tiny structures fixed at one end and free at the other act like nano-scale diving boards that "bend" when molecules "jump" on them and register a change that can be measured and calibrated. This paper demonstrates how NEMS can be improved by using integrated photonics to sense the cantilever motion. The system can detect deflections in the nano-cantilever sensors as little as 0.0001 Angstroms. To detect this tiny motion, the team devised a photonic structure to guide the light wave through a cantilever. After exiting from the free end of the cantilever, the light tunnels through a nanometer gap and is collected on chip. Detecting the lightwave after this evanescent tunneling gives the unprecedented sensitivity.
  [Broadband all-photonic transduction of nanocantilevers, Nature Nanotechnology Published online: 26 April 2009, doi:10.1038/nnano.2009.92]
  (April 27, 2009)

• Universal transduction scheme using dielectric forces for NEMS
  (Ludwig-Maximilians-Universitt Mnchen at Eurekalert)

  Chemical analysts today are expected to track down even single molecules. To do this highly sensitive detective work, nano researchers have developed minute strings that resonate in characteristic fashion. If a molecule docks onto one of the strings, then it becomes heavier, and its oscillations become measurably slower. Until recently, however, such "nano-electromechanical systems", or NEMS, have been short of practical applications. Researchers have now constructed a system of nanostrings made of non-conducting material, where each string can be electrically excited separately. Thousands of these strings can be produced on a small chip. One of the devices that could be created with this system is a highly sensitive "artificial nose" that detects various molecules pollutants for example individually. These new NEMS could also be used in a multitude of other applications acting as tiny pulse generators in mobile phone clocks, for example.
  [Universal transduction scheme for nanomechanical systems based on dielectric forces, Nature 458, 1001-1004 (23 April 2009), doi:10.1038/nature07932]
  (April 24, 2009)

• Spider silk toughness greatly increased by metal infiltration
  (Technology Review)

  
  Credit: Science

  Researchers have used atomic-layer deposition to pulse zinc, titanium, and aluminum ions into spider silk. The resulting materials show greatly enhanced toughness over natural spider silk and could be used to make protective clothing or even new structural materials. To demonstrate that the method is a general one, they also used metal ions to toughen eggshell membranes, which are mostly made up of the protein collagen. The protein-metal composites are tougher than the sum of their parts.
  [Greatly Increased Toughness of Infiltrated Spider Silk, Science 24 April 2009: Vol. 324. no. 5926, pp. 488 - 492 DOI: 10.1126/science.1168162]
  (April 24, 2009)

• Potassium improves photochemical characteristics of titania nanotubes
  (Northeastern University/NIST at Eurekalert)

  
  Credit: Menon et al., Northeastern University

  A research team has discovered, serendipitously, that a residue of a process used to build arrays of titania nanotubesa residue that wasnt even noticed before thisplays an important role in improving the performance of the nanotubes in solar cells that produce hydrogen gas from water. Their results indicate that by controlling the deposition of potassium on the surface of the nanotubes, they can achieve significant energy savings in a promising new alternate energy system. When the research team compared the performance of potassium-bearing nanotubes to similar arrays deliberately prepared without potassium, the former required only about one-third the electrical energy to produce the same amount of hydrogen as an equivalent array of potassium-free nanotubes.
  [Effect of potassium adsorption on the photochemical properties of titania nanotube arrays, J. Mater. Chem., 2009, DOI: 10.1039/b822501]
  (April 23, 2009)

• AFM reveals hidden differences between normal and cancerous cells
  (NanotechWeb)

  
  Credit: Sokolov Group, Clarkson University

  Using an atomic force microscope, researchers have identified an important difference in the surface properties of normal and cancer cells. They found that normal cells have "brushes" of one length on their surface while cancerous cells have two brush lengths that have very different densities to the brushes on normal cells. This important variation means that cancer and normal cells may interact very differently with nanoparticles, something that could be exploited for cancer detection and treatment via drug delivery. The team obtained its results by analysing force measurements taken from the cell surface using an atomic force microscope (AFM). By analysing the deformation curves, the researchers found a two-layer behavior in the cells. They then developed a model to decouple these two layers so that they could study them separately.
  [Atomic force microscopy detects differences in the surface brush of normal and cancerous cells, Nature Nanotechnology Published online: 12 April 2009, doi:10.1038/nnano.2009.77]
  (April 23, 2009)

• Chiral imprinting of palladium for catalysis
  (Royal Society of Chemistry)

  
  Credit: Paul Collignon, Univ. Amsterdam

  Scientists have found a way to induce the chirality usually only found in organic materials in palladium. Usually, a chiral palladium catalyst indicates a palladium atom modified by chiral organic ligands. The present study however has yielded a chiral palladium metal with no organic material whatsoever. The team tested samples of chiral palladium as catalysts for the hydrogenation of isophorone, proving that they could produce modest excesses of left- and right-handed enantiomers. The chiral palladium was created by reducing ordinary palladium in the presence of specific alkaloid enantiomers that become trapped in the metal. Dissolving the alkaloid leaves pure palladium - a black powder - which is somehow imprinted with the enantiomer it has lost.
  [Chiral imprinting of palladium with cinchona alkaloids, Nature Chemistry Published online: 19 April 2009 | doi:10.1038/nchem.180]
  (April 22, 2009)

• Ferroelectric oxide formed directly on silicon
  (Science at Eurekalert)

  
  Credit: Schlom et al., Science

  Researchers have been able to add ferroelectric capability to material used in common computer transistors, a feat scientists tried to achieve for more than half a century. They took strontium titanate, a normally non-ferroelectric variant of the ferroelectric material , and deposited it on silicon in such a way that the silicon squeezed it into a ferroelectric state. They grew coherently strained strontium titanate (SrTiO3) films via oxide molecular beam epitaxy in direct contact with silicon, with no interfacial silicon dioxide. They were able to observe ferroelectricity in these ultrathin SrTiO3 layers by means of piezoresponse force microscopy.
  [A Ferroelectric Oxide Made Directly on Silicon, Science 17 April 2009: Vol. 324. no. 5925, pp. 367 - 370, DOI: 10.1126/science.1169678]
  (April 22, 2009)

• Carbene catalyst converts carbon dioxide from air to methanol
  (Angewandte Chemie International Edition)

  
  Credit: Wiley-VCH

  By using photosynthesis, plants can easily and efficiently fix the carbon dioxide that is so plentiful in air to make biomass, or organic compounds. Researchers have now developed a novel reaction scheme by which CO₂ can be efficiently converted into methanol under very mild conditions. The reaction is based on an N-heterocyclic carbene catalyst and a silane as the reducing agent. The basic framework of an N-heterocyclic carbene is a five-membered ring made of two nitrogen and three carbon atoms. Instead of having the usual four bonds, one of these carbon atoms only has two. The two electrons left over in the form of a lone pair, which makes this species highly reactivereactive enough to attack CO₂. The big advantage of this is that unlike prior reaction mechanisms using metal-containing catalysts, air can be used as the source of the CO₂ because the carbene catalyst is not sensitive to oxygen. The carbene is more efficient than the metal-containing catalysts as well, and the reaction can be carried out under very mild conditions.
  [Conversion of Carbon Dioxide into Methanol with Silanes over N-Heterocyclic Carbene Catalysts, Angewandte Chemie International Edition, Volume 48 Issue 18, Pages 3322 - 3325 Published Online: 31 Mar 2009]
  (April 21, 2009)

• A zippy route to nanoribbons
  (Chemical & Engineering News)

  
  Credit: James Tour, Rice Univ.

  
  Credit: Hongjie Dai, Stanford Univ.

  Two teams of researchers working independently have reported a new strategy for forming graphene nanoribbons, by longitudinally "unzipping" carbon nanotubes. Compared with other procedures for preparing graphene nanoribbons, which are narrow and elongated one-atom-thick strips of carbon, the new routes are simpler, less expensive, and potentially better suited to making bulk quantities of the material. The first team treated the nanotubes with sulfuric acid and potassium permanganate. The process unzips multiwalled and single-walled tubes chemically and forms ribbons measuring up to a few micrometers in length and a few nanometers to hundreds of nanometers in width. The researchers follow the oxidizing procedure with chemical reduction to restore the material's electrical conductivity. The second team partially embedded the nanotubes in a polymer film to hold them in place and then etched them with an argon plasma. They removed the film with solvent vapor and heat. This process also unzips multiwalled and single-walled nanotubes and yields graphene ribbons 10–20 nm wide.
  [Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons, Nature 458, 872-876 (16 April 2009) | doi:10.1038/nature07872
  Narrow graphene nanoribbons from carbon nanotubes, Nature 458, 877-880 (16 April 2009) | doi:10.1038/nature07919]
  (April 21, 2009)

• Superionic conductivity in a Li-fullerene crystal
  (Physical Review Focus)

  
  Credit: M. Riccò/Univ. of Parma, Italy

  Ionic conductivity is essential for batteries, fuel cells, and various other technologies. Providing sufficient space in the molecular structure for the movement of ions usually requires a disordered (non-crystalline) material. A new paper now reports a crystalline compound with very high conductivity. It consists of positively-charged lithium ions flowing through a stacked structure of much larger, negatively-charged C60 molecules. The new compound consists of four lithium ions per C60 molecule. The team measured a conductivity of 0.01 siemens per centimeter at room temperature in 100-milligram pellets of Li4C60, or five times the conductivity of standard, non-crystalline ionic conductors.
  [Superionic Conductivity in the Li4C60 Fulleride Polymer, Phys. Rev. Lett. 102, 145901 (issue of 10 April 2009)]
  (April 21, 2009)

• Carbon nanotubes clean up their act
  (NanotechWeb)

  
  Credit: G Steele, Delft University of Technology

  Researchers have developed a new technology for making ultraclean carbon nanotube devices. The new technique overcomes the disadvantages of previous nanofabrication methods that systematically yield contaminated tubes. In previous work with gated carbon nanotubes, the nanofabrication techniques employed produced contaminated nanotubes that are unsuitable for use in high quality electronic devices. Moreover, scientists cannot control electron confinement in such dirty tubes because it gets trapped in the random potential created by the contamination. It is therefore impossible to reduce the number of electrons in the tubes down to the single-electron regime important for fundamental studies. The researchers got around this problem in their devices by 'flipping' the whole fabrication procedure upside down. All nanofabrication was performed before the nanotubes were grown, and the nanotubes were grown on the chip in the very last step. This approach kept the nanotubes clean and allowed them to consistently trap and control a single electron.
  [Tunable few-electron double quantum dots and Klein tunnelling in ultraclean carbon nanotubes,Nature Nanotechnology Published online: 6 April 2009 | doi:10.1038/nnano.2009.71]
  (April 10, 2009)

• New method yields narrower microchip patterns
  (MIT)

  
      Credit: Science

  Researchers have found a novel method for etching extremely narrow lines on a microchip, using a material that can be switched from transparent to opaque, and vice versa, just by exposing it to certain wavelengths of light. Such materials are not new, but the researchers found a novel way of harnessing that property to create a mask with exceptionally fine lines of transparency. This mask can then be used to create a correspondingly fine line on the underlying material. Producing such fine lines is crucial to many new technologies, from microchip manufacturing that is constantly seeking ways to cram more components onto a single chip, to a whole host of emerging fields based on nano-scale patterns. But these technologies have faced fundamental limits because they tend to rely on light to produce these patterns, and most techniques cannot produce patterns much smaller than the wavelengths of light itself. This method is a way of overcoming that limit.
  [Confining Light to Deep Subwavelength Dimensions to Enable Optical Nanopatterning, Science Published Online April 9, 2009 DOI: 10.1126/science.1167704]
  (April 10, 2009)

• DNA walks the line
  (Physics World)

  
  Credit: Science

  A two-legged molecular motor that "walks" in a single direction instead of wandering about randomly has been unveiled by researchers. The DNA-based device could someday be used to assemble complex molecules, transport drugs within the body, or drive molecular machines of the future. Current molecular walkers try to imitate the cellular motors actin and kinesin, which carry various cargoes from one place to another in biological cells. However, until now, it has not been possible to make these molecules move in one particular direction along a track. This is because it is difficult to coordinate the movement of the motor's legs so that they move in a synchronized way without the legs coming off the track. The new walker is a piece of DNA that contains a head-to-head linkage in the middle. This set-up ensures that the two legs in the device are synchronized. The device moves along a rigid track, also made of DNA, and is powered by two different fuel strands in solution, acting alternately. These fuel strands push the walker along in a ratchet-like motion. The walker forms base pairs of DNA as it moves along the track.
  [A Bipedal DNA Brownian Motor with Coordinated Legs, Science 3 April 2009: Vol. 324. no. 5923, pp. 67 - 71 DOI: 10.1126/science.1170336]
  (April 9, 2009)

• Biocompatible polymers on stents keep the blood flowing
  (Royal Society of Chemistry)

  
  Credit: Dong Lyun Cho et al., Chonnam National University

  Drug-laden polymer coats could make medical implants more biocompatible, according to a new report. Researchers have developed a method of coating stents with a polymer and then attaching drug molecules to the surface. Stents are narrow mesh-like metal tubes that can be inserted into the diseased parts of arteries and then expanded to hold them open and keep the blood flowing. However, being foreign objects, stents can cause abnormal cell growth and artery narrowing (restenosis). The stents can be coated with polymers to avoid this. However, for a successful result, the polymer needs to be both biocompatible and strongly fixed to the metal surface, which is difficult to acheive. The team created a strongly adhesive polymer film on the stent's surface using a two-stage plasma polymerization process. They then used the amino groups on the polymer surface to form amide bonds with-lipoic acid, a drug known to inhibit abnormal cell growth. The new polymer films have high mechanical stability and prevent platelet aggregation in vitro. In addition, when tested on a model cell system, the new stents result in lower restenosis rates.
  [Preparation of a biocompatible stent surface by plasma polymerization followed by chemical grafting of drug compounds,J. Mater. Chem., 2009, DOI: 10.1039/b813357c]
  (April 8, 2009)

• Super rebounding of thermally activated nanoclusters
  (Physical Review Focus)

  
  Credit: H. Kuninaka, Chuo University

  In collisions between two deformable or sticky objects, some or all of the initial energy is usually lost to heat. But computer simulations of nanocluster collisions, as described in a recent report, show that thermal fluctuations in the tiny projectiles can cause them to rebound with more kinetic energy than they started with. This energy boost would seem to violate the second law of thermodynamics, which bans heat from being turned directly into energy of motion. Below a certain threshold of cohesiveness some of the simulated events displayed a coefficient of restitution greater than one and as high as 1.05. The fraction of these anomalous rebounds increased with the cluster temperature. The transfer of energy from random internal motion of the atoms to the movement of the whole cluster creates a decrease in entropy and therefore an apparent violation of the second law of thermodynamics. The researchers believe their work might apply to techniques in nano-device fabrication.
  [Simulation of Cohesive Head on Collisions of Thermally Activated Nanoclusters, Phys. Rev. E 79, 031309]
  (April 8, 2009)

• A molecular ripcord for chemical reactions
  (Eindhoven University of Technology at Eurekalert)

  
  Credit: Rint Sijbesma, Eindhoven University of Technology

  Researchers have developed an entirely new method for starting chemical reactions. For the first time they used mechanical forces to control catalytic activity. This allowed them to initiate chemical reactions with mechanical force. This discovery paves the way to developing materials capable of repairing themselves under the influence of mechanical tension. The study is the first to have demonstrated that a catalyst can be switched from a dormant to an active state by pulling on a polymer chain, a "molecular ripcord." The researchers were able to use this catalyst to initiate a variety of chemical reactions, including polymerizations. This discovery paves the way to creating self-repairing materials that strengthen under the influence of mechanical stress. If a material were to tear, for example, this would simultaneously break the metal complex in half, thereby activating the catalyst, and the material would be instantly repaired.
  [Activating catalysts with mechanical force, Nature Chemistry Published online: 6 April 2009 | doi:10.1038/nchem.167]
  (April 8, 2009)

• Genetically engineered viruses used to fabricate Li ion batteries
  (MIT)

  
  Credit: MIT

  Researchers for the first time have shown they can genetically engineer viruses to build both the positively and negatively charged ends of a lithium-ion battery. The new virus-produced batteries have the same energy capacity and power performance as state-of-the-art rechargeable batteries being considered to power plug-in hybrid cars, and they could also be used to power a range of personal electronic devices. The new batteries could be manufactured with a cheap and environmentally benign process: The synthesis takes place at and below room temperature and requires no harmful organic solvents, and the materials that go into the battery are non-toxic.
  [Fabricating Genetically Engineered High-Power Lithium Ion Batteries Using Multiple Virus Genes, Science, Published Online April 2, 2009, DOI: 10.1126/science.1171541]
  (April 3, 2009)

• Recuperating industrial waste heat
  (Eurekalert)

  Tapping industrial waste heat could reduce fossil fuel demands in the short term and improve efficiency of countless manufacturing processes, according to scientists in a new report. They explain that heat waste from industrial processes, such as combustion and electricity generation is sometimes of low energy and diffuse. Capturing this low-quality heat for re-use elsewhere on an industrial plant is usually not practical. However, given current environmental and economic pressures the recuperation of such heat energy could become viable. The team has investigated three promising technologies for heat recovery: latent heat, reaction heat, and the use of a Thermoelectric Device. The aim of their study was to find a way to capture the heat from industrial furnaces and other systems without the constraints of time and space associated with simply using the heat to produce steam to drive other processes at precisely the same site. They say their approach can "recuperate industrial waste heat beyond time and space."
  [How to recuperate industrial waste heat beyond time and space, International Journal of Exergy 2009 - Vol. 6, No.2 pp. 214 - 227, DOI: 10.1504/IJEX.2009.023999]
  (April 3, 2009)

• Cooking up a smart nanofluid
  (Physical Review Focus)

  
  Credit: D. C. Rapaport, Phys. Rev. E

  Specialized nanoparticles floating in water make a fluid that can be switched between two states with different thermal properties, according to a recent report. If the particles start out evenly distributed throughout the fluid volume, heat transfers more rapidly through the fluid than if they are more concentrated close to the heat source. The flow pattern is not fixed like the steady rolling produced in pure water, which suggests more complicated physics than researchers had previously predicted. But the team hopes some version of their fluid can be used to improve the regulation of heat flow in future devices.
  [Bistable Heat Transfer in a Nanofluid Gea Donzelli, Roberto Cerbino, and Alberto Vailati Phys. Rev. Lett. 102, 104503 (issue of 13 March 2009)]
  (April 3, 2009)

• A route to large pnictide single crystals
  (Physics)

  
  Credit: Physics/APS

  Iron-based superconductors with transition temperatures as high as 55 K have generated a significant tide of interest. Yet considerable sensitivity to synthesis conditions makes the growth of large single crystals for many of these compounds difficult, and this in turn makes crucial experiments either infeasible or hard to interpret. A new paper reports the successful growth of very large single crystals of Fe_1+yTe_xSe_1-x. These compounds are a recent addition to the still expanding family of iron-based superconductors, and they exhibit superconducting transition temperatures as high as 14 K at ambient pressure, and up to 27 K under pressure. They consist of alternating layers of iron and Te/Se, with any excess iron accommodated in the Te/Se layers.
  [Bulk superconductivity at 14 K in single crystals of Fe1+yTexSe1−x, Phys. Rev. B 79, 094521 (Published March 24, 2009)]
  (April 2, 2009)

• Current spike phenomenon in semiconductor materials linked to nanoscale plasticity
  (PhysOrg)

  Plasticity in certain semiconductor materials at the nanoscale is actually linked to phase transformation rather than dislocation nucleation, according to a new study. Plasticity has always been associated with defect movement or initiation, but the research team has proved that plasticity can indeed start from non-dislocation processes, and that this phase transformation occurs in a stressed nano-volume, changing from one crystalline structure to another without affecting defect activity. The phenomenon, named the “Current Spike”, is clearly visible, and its explanation relies heavily on advanced physics.
  [An electric current spike linked to nanoscale plasticity, Nature Nanotechnology Published online: 22 March 2009 | doi:10.1038/nnano.2009.49]
  (April 2, 2009)

• Live video of C atoms undergoing rearrangements along graphene edges
  (Chemical & Engineering News)

  
  Credit: Lawrence Berkeley National Laboratory

  Armed with a state-of-the-art microscope, researchers have recorded the first videos that capture the dynamics of individual carbon atoms in a sheet of graphene. The videos, which catch numerous atoms hopping to and fro as they make and break chemical bonds along the edge of a hole in the sheet, reveal the types of atomic arrangements that are stable near such defects and the mechanisms by which the defects evolve. The study broadens basic understanding of one-atom-thick two-dimensional crystals. The team used an advanced ("aberration corrected") transmission electron microscope (TEM) to follow in real time the rearrangements of atoms along the edge of a hole punched into a film of graphene. The hole was made by ejecting carbon atoms via prolonged exposure to the TEM's high-energy electron beam. As the hole continues to grow under the influence of the beam, carbon atoms near the hole scramble to fill vacancies and find stable bonding configurations.
  [Graphene at the Edge: Stability and Dynamics, Science 27 March 2009: Vol. 323. no. 5922, pp. 1705 - 1708 DOI: 10.1126/science.1166999]
  (April 2, 2009)

• Magnetic nano-shepherds organize living cells
  (Duke University)

  
  Credit: Duke University

  The power of magnetism may address a major problem facing bioengineers as they try to create new tissue -- getting human cells to not only form structures, but to stimulate the growth of blood vessels to nourish that growth. A research team has created an environment where magnetic particles suspended within a specialized solution act like molecular sheep dogs. In response to external magnetic fields, the shepherds nudge free-floating human cells to form chains which could potentially be integrated into approaches for creating human tissues and organs. The cells not only naturally adhere to each other upon contact, the researchers said, but the aligned cellular configurations may promote or accelerate the creation and growth of tiny blood vessels.
  [Formation of Ordered Cellular Structures in Suspension via Label-Free Negative Magnetophoresis, Nano Lett., Article ASAP DOI: 10.1021/nl803757u, Publication Date (Web): March 27, 2009]
  (April 1, 2009)

• Overcoming the poor cyclic fatigue resistance of bulk metallic glasses
  (Lawrence Berkeley National Laboratory)

  
  Credit: Lawrence Berkeley National Laboratory

  Researchers have solved the fundamental problem of poor fatigue resistance in bulk metallic glasses. The results are metallic glass alloys that are not only stronger than high-strength steel and aluminum alloys but more resistant to fatigue as well. A a metallic glass alloy named DH3, made from five elements roughly a third zirconium, a third titanium, and the remainder niobium, copper, and beryllium, was previously developed. In bulk samples of DH3 the researchers induced a second phase of the metal, which took the form of narrow pathways of crystalline metal permeating the metallic glass in dendritic (treelike) patterns; its growth was carefully controlled by processing a partially molten liquid-solid mixture. The resulting dendritic phase acts as a local arrest point to any crack that begins to propagate in the glass. The toughness, ductility, and fatigue resistance all intimately related properties of the DH3 alloy improved to the point that the bulk metallic glass was not only stronger than many structural metal alloys but had a fatigue limit more than 30 percent higher than ultra-high-strength steel and aluminum-lithium alloys.
  [Solution to the problem of the poor cyclic fatigue resistance of bulk metallic glasses, PNAS, Published online before print March 16, 2009, doi: 10.1073/pnas.0900740106]
  (March 31, 2009)

• Flexible, transparent supercapacitors incorporate In2O3 nanowires and carbon nanotubes
  (Univ. Southern California)

  
  Credit: Univ. Southern California

  Researchers have developed a supercapacitor based on indium nanowire / carbon nanotube heterogeneous films. The device stores an energy density of 1.29 Watt-hour/kilogram with a specific capacitance of 64 Farad/gram. By contrast, conventional capacitors usually have an energy density of less than 0.1 Wh/kg and a storage capacitance of several tenth millifarads. The work is based on earlier attempts to produce supercapacitors using just CNTs or graphite. The critical improvement in performance can be attributed to the incorporation of metal oxide nanowires with CNT films. Indium oxide nanowires, with a wide band gap, high aspect ratio, and short diffusion path length, is one of the best candidates for transparent electrochemical capacitors.
  [Flexible and transparent supercapacitor based on In2O3 nanowire/carbon nanotube heterogeneous films, Appl. Phys. Lett. 94, 043113 (2009); DOI:10.1063/1.3069277]
  (March 31, 2009)

• Molecular ball-bearings for artificial joints
  (Royal Society of Chemistry)

  
  Credit: Science

  Scientists have used water to create almost frictionless lubricated surfaces, which stay slippery even under heavy loads. The coating they have developed could shed light on how natural joints are lubricated and provide new ways to protect hip and knee joint implants from friction damage. The group has made polymer 'brushes' by attaching one end of polymer chains to a host surface, leaving the other end sticking out. The polymer chain 'bristles' tend to repel each other and so stand up from the surface to form a brush-like structure. The brushes are made from poly[2-(methacryloyloxy)ethyl phosphorylcholine] (pMPC), which has side chains that are zwitterionic (i.e. they are neutral overall but carry both positively and negatively charged groups). Introducing charges to the brushes yields a hydration layer of water molecules around the charges. These water molecules are tightly bound, in the sense that it's hard to remove them all at once, but individual molecules are able to rapidly exchange with water in the surrounding solvent or the hydration layer of another charge. This gives them the properties of molecular ball-bearings, which gives the excellent lubrication properties.
  [Lubrication at Physiological Pressures by Polyzwitterionic Brushes, Science 27 March 2009: Vol. 323. no. 5922, pp. 1698 - 1701 DOI: 10.1126/science.1169399]
  (March 30, 2009)

• Cellulose-based clear nanofiber paper developed
  (Chemical & Engineering News)

  
  Credit: Adv. Mater., Wiley-ACH

  Researchers have created an optically transparent paper from nanosized cellulose fibers. The renewable material's transparency, strength, and thermal stability give it potential advantages over glass or polymers for use in electronic devices. The nanofiber paper was made with cellulose, the material used to make traditional paper. A wood flour and water slurry was mixed into sheets that were dried and then polished with fine-grit sandpaper. Hydrogen bonding of hydroxyl groups holds the cellulose fibers together. Nanofiber paper appears transparent because the fibers pack densely and create tiny spaces that avoid light scattering. Conventional paper on the other hand is opaque because the interstices between the fibers scatter light.
  [Optically Transparent Nanofiber Paper, Advanced Materials Early View, DOI: 10.1002/adma.200803174]
  (March 30, 2009)

• STM used for hydrogen-bonding-based DNA decoding
  (Physics World)

  
  Credit: Stuart Lindsay et al.

  Quantum physics could come to the aid of medical science thanks to a new technique for identifying DNA that utilizes the quantum effect of tunnelling. The method could enable users to read genetic codes directly by studying DNA with a scanning tunneling microscope (STM). The researchers exploit the fact that each individual base in DNA has a unique effect on the tunnelling current of an STM. Key to this new DNA reading technique is the fact that the strength of the bonds of the bases differ; A-T pairs are held by two hydrogen bonds, whereas C-G pairs by three hydrogen bonds. They attach a particular base to the end of an STM and "dangle" it over a sample of DNA. The tip will only bond to the DNA if it is directly above its complementary base. As a result, the tunneling current fluctuates as the STM tip passes along the sample.
  [Tunnelling readout of hydrogen-bonding-based recognition, Nature Nanotechnology Published online: 22 March 2009 | doi:10.1038/nnano.2009.48]
  (March 27, 2009)

• Smoothing out graphene ribbon edges
  (NanotechWeb)

  
  Credit: X Jia, MIT

  As-processed graphene nanoribbons are limited by their edges. This is because even minute deviations from the ideal edge shapes, "armchair" and "zigzag", can seriously degrade graphene's exceptional properties. Now, researchers have developed a new method to smooth out nanoribbon edges using a heat treatment that makes most of the resulting edges either zigzag or armchair. The new technique is an efficient way to transform defective rough edges in the ribbons into atomically smooth ones using "Joule heating". An electrical current is applied across a suspended graphene nanoribbon inside a high-resolution transmission electron microscope (HRTEM). With enough heat, the carbon atoms at the edges start to move and reposition themselves either into zigzag or armchair configurations.
  [Controlled Formation of Sharp Zigzag and Armchair Edges in Graphitic Nanoribbons, Science 27 March 2009: Vol. 323. no. 5922, pp. 1701 - 1705 DOI: 10.1126/science.1166862]
  (March 27, 2009)

• A coating that heals itself
  (Chemical & Engineering News)

  
  Credit: Adv. Mater.

  The life of underground pipelines, deep-sea oil well platforms, and sea-faring ships could be extended thanks to newly developed self-healing coatings that repair scratches, staving off corrosion. No external stimulus, such as UV light, is needed to initiate the healing process. This makes these coatings particularly attractive for preventing corrosion in hard-to-reach places, where replacing hardware or repairing surfaces is a major undertaking. The new coating's repair mechanism relies on tiny capsulesroughly 90 m in diameterthat hold either a siloxane monomer or a catalyst made from tin or titanium salts. Damage to the coating causes these little balloons to burst, bleeding their contents into the damaged region, where they mix, polymerize, and repair the surface.
  (March 26, 2009)

• Picoscale stability in a room-temperature AFM
  (NIST/University of Colorado)

  
  Credit: G.Kuebler, JILA, University of Colorado

  A research team has shown how to detect and monitor the tiny amount of light reflected directly off the needle point of an atomic force microscope probe, and in so doing has demonstrated a 100-fold improvement in the stability of the instruments measurements under ambient conditions. Their recently reported work potentially affects a broad range of research from nanomanufacturing to biology, where sensitive, atomic-scale measurements must be made at room temperature in liquids. The technique uses two additional laser beams to sense the three-dimensional motion of both the test specimen and the AFM probe. The beams are held stable relative to each other to provide a common reference. To hold the specimen, the team uses a transparent substrate with tiny silicon disksfiducial marksembedded in it at regular intervals. The team was able to control the probes position in three dimensions to better than 40 picometers over 100 seconds. In imaging applications, they showed the long-term drift at room temperature was a mere 5 picometers per minute, a 100-fold improvement over the best previous results under ambient conditions.
  [Ultrastable Atomic Force Microscopy: Atomic-Scale Stability and Registration in Ambient Conditions, Nano Lett., Article ASAP DOI: 10.1021/nl803298q]
  (March 25, 2009)

• Flow sensors based on hair structures of blind cavefish
  (Georgia Tech / e! Science News)

  
  Credit: Michael McConney, Georgia Tech

  A blind fish that has evolved a unique technique for sensing motion may inspire a new generation of sensors that perform better than current active sonar. Although members of the fish species Astyanax fasciatus cannot see, they sense their environment and the movement of water around them with gel-covered hairs that extend from their bodies. Their ability to detect underwater objects and navigate through their lightless environment inspired a group of researchers to mimic the hairs of these blind cavefish in the laboratory. They conducted preliminary experiments with a simple artificial hair cell microsensor made of SU-8, a common epoxy-based polymer capable of solidifying, and built with conventional CMOS microfabrication technology. They found that the cell by itself could not achieve the high sensitivity or long-range detection of hydrodynamic disturbances created by moving or stationary bodies in a flow field. The hair cell needed the gel-like capsule called the cupula to overcome these challenges. The engineered sensors they are developing could have a variety of underwater applications, such as port security, surveillance, early tsunami detection, autonomous oil rig inspection, autonomous underwater vehicle navigation, and marine research.
  (March 25, 2009)

• Omnidirectional printing of silver microelectrodes for flexible electronics
  (Science)

  
  Credit: Science

  Organic polymers are the main components of most flexible electronic devices. These devices rely on the compliant physical properties of organic polymers to maintain electrical continuity when deformed. However, electrical connections within these devices are a point of weakness and have limited the types of materials and processes that can be used. Although inorganic semiconductors and metals have high conductivity, these materials will not commonly sustain repeated bending or stretching. In a new study, researchers show how metal can be added to components within flexible electronic devices, enabling conductivity to be maintained even after repeated deformation. They used inkjet printing to create three-dimensional (3D) metallic connections between functional components of flexible devices. Controlling the deposition of the colloidal silver ink is essential for fabricating freestanding wires that have both 2D and 3D components. The electrical connections demonstrated by the researchers include springs and structures with built-in slack to accommodate the stretching and bending of a flexible device. The ability to form arched features is also essential for avoiding direct contact when one electrical connection crosses over another.
  [Omnidirectional Printing of Flexible, Stretchable, and Spanning Silver Microelectrodes, Science 20 March 2009: Vol. 323. no. 5921, pp. 1590 - 1593 DOI: 10.1126/science.1168375]
  (March 24, 2009)

• Novel type-1.5 superconductivity demonstrated in MgB₂
  (Physics)

  
  Credit: V. V. Moshchalkov

  Superconductors are usually categorized as being either type-I or type-II, depending on their behavior under a magnetic field. Now, researchers have found evidence for a superconducting phase that spans these categories, showing coexisting type-I and type-II behavior. Decoration experiments of the two-gap superconductor MgB₂ showed evidence for long-range attraction between vortices in a superconducting mixed state, which was interpreted as coexisting type-I and type-II superconductivity.
  [Type-1.5 Superconductivity, Phys. Rev. Lett. 102, 117001 (2009)]
  (March 24, 2009)

• Hybrid rotaxanes combine inorganic and organic parts
  (Chemical & Engineering News)

  
  Credit: Nature

  Molecular machines are taking up the fashionable hybrid label, thanks to a new type of interlocked organic-inorganic molecule synthesized recently. Combining two distinct chemistries into one molecule could expand the realm of applications for these systems in areas such as quantum computing. The new hybrid molecules are rotaxanesbead-on-a-string-type structures in which a linear molecule threads through at least one cyclic molecule. Bulky components at each end of the linear molecule act as stoppers to keep the compound from coming apart. The new hybrid rotaxane structures were built from linear secondary amine threads and heterometallic rings. According to the researchers, "this is the first example of a discrete molecule in which wholly organic and essentially inorganic components are linked mechanically at the molecular level."
  [Hybrid organicinorganic rotaxanes and molecular shuttles, Nature 458, 314-318 (19 March 2009) | doi:10.1038/nature07847]
  (March 23, 2009)

• Oblique angle deposition for mass production of metamaterials
  Oblique angle deposition for mass production of metamaterials
  (Physics World)

  
  Credit: Akhlesh Lakhtakia et al.

  Though metamaterials have generated a lot of interest in the last few years, the ones made so far have only worked over a limited range of frequencies and are difficult to produce in large quantities. Taking a different approach, researchers have turned their attention to a more established production technique known as “oblique angle deposition” (OAD) which is widely used in the photonics industry to deposit thin films. It involves depositing vapor at an angle onto a substrate held in a vacuum. The formed film thickness was 240 nm and the angle between the normal to the substrate and the tilt of the nanorods was maintained at 66 degrees. Silver nanorods were grown to about 650 nm long and 80 nm wide. The researchers then determined the optical properties of the film by illuminating it a number of times with light at wavelengths between 300 and 850 nm. They found that light between the wavelengths 532nm and 690 nm was refracted negatively but say that - in theory - almost all visible light (380 to 750 nm) could be negatively refracted.
  [Vapor-deposited thin films with negative refractive index in the visible regime, arXiv:0903.1177v1 [physics.optics]]
  (March 23, 2009)

• Water acts as catalyst in explosives
  (Nature Chemistry / EurekAlert)

  
  Credit: Nature Chemistry

  A new study has shown that water, in hot dense environments, plays an unexpected role in catalyzing complex explosive reactions. Water rarely, if ever, acts as a catalyst under ordinary conditions. Using first-principle atomistic simulations of the detonation of the high explosive PETN (pentaerythritol tetranitrate), the research team discovered that in water, when one hydrogen atom serves as a reducer and the hydroxide (OH) serves as an oxidizer, the atoms act as a dynamic team that transports oxygen between reaction centers. They found that nitrogen loses its oxygen mostly to hydrogen, not to carbon, even after the concentration of water reaches equilibrium. They also found that carbon atoms capture oxygen mostly from hydroxide, rather than directly from nitrogen monoxide (NO) or nitrogen dioxide (NO_). Meanwhile water disassociated and recombines with hydrogen and hydroxide frequently.
  [Catalytic behaviour of dense hot water, Nature Chemistry 1, 57 - 62 (2009), doi:10.1038/nchem.130]
  (March 23, 2009)

• Carbon nanotube aerogel forms superelastic artificial muscle
  (Nature News)

  
  Credit: Science Technology Education Media

  As light as air, yet stronger than steel and bendier than rubber. A new material made from bundles of carbon nanotubes combines all of these characteristics in a substance that twitches like a muscle when a voltage is applied. The 'artificial muscle' is an aerogel drawn into a long ribbon. Applying a voltage across the width of the ribbon electrically charges the nanotubes that thread through the material. This makes them repel one another, and the ribbon can expand sideways by up to three times its original width in an instant. The artificial muscle can expand about 4,000 times faster than human muscle does, and can be switched on and off up to 1,000 times a second with no deterioration. Applying a voltage along the length of the ribbon has a very different effect. It triggers the nanotube structure to contract, making the material more dense and very stiff. This means that along the length of the ribbon, the nanotube aerogel is, weight for weight, stronger than steel.
  [Giant-Stroke, Superelastic Carbon Nanotube Aerogel Muscles, Science 20 March 2009: Vol. 323. no. 5921, pp. 1575 - 1578 DOI: 10.1126/science.1168312; View animation, video]
  (March 20, 2009)

• Graphene makes good microwave switch
  (NanotechWeb)

  
  Credit: J. Appl. Phys.

  A research team has shown that graphene flakes can enable and disable the propagation of high-frequency electromagnetic fields up to 60 GHz when a DC voltage is applied. The switching time is very short at less than 1 ns, which is among the fastest ever observed in such a device. The device is a microwave NEMS switch that comprises a coplanar waveguide and an array of metallic graphene sheets suspended over it. The waveguide is made from three gold metallic strips deposited on a 500 µm thick semi-insulating silicon substrate. The central strip propagates the microwaves while the other two strips act as ground electrodes. The graphene flakes remain suspended over the waveguide thanks to van der Waals forces, but they could also be attached via metallic contacts too, say the researchers. The graphene switch is much simpler and more efficient than switches made from conventional materials, such as silicon. The electromagnetic field in the device switches on and off simply by applying different DC biases.
  [Microwave switches based on graphene, J. Appl. Phys. 105, 054309 (2009); DOI:10.1063/1.3080130]
  (March 20, 2009)

• Precise positioning of organic microwires for flexible electronics
  (Technology Review)

  
  Credit: Stanford University / Samsung

  Organic microwires, which can be used to make flexible electronics, are hard to align as circuits. Now researchers have developed a technique that allows them to precisely position organic microwires on a substrate and build complex circuits with relative ease. The new technique involves putting microwires in a liquid solution and filtering them through paper to form the circuit's transistors. They can maximize the number of microwires in a circuit using the new technique and this allows them to significantly increase the output current from these devices. The organic microwire transistors made using the new technique operate two and a half times faster than previous ones.
  (March 19, 2009)

• TEM images 47 picometer spacing of a Ge crystal
  (Physics World)

  Hailed as the world’s most powerful transmission electron microscope,the instrument has clinched another world first - resolving matter to less than half an angstrom with high contrast. The microscope has been tweaked by researchers to resolve a 47 picometer spacing in a Germanium crystal. The TEM corrects for spherical blurring caused by “aberrations” in the lens. They also turned their attention to the electron probe itself. They realized that the electron source and the geometrical source size are crucial parameters that govern the size of the electron beam. Analysis of a range of different electron sources led to the optimum set up. According to a scientist not involved in the work, "This is the best transmission electron microscope in the world."
  [Atomic-Resolution Imaging with a Sub-50-pm Electron Probe, Phys. Rev. Lett. 102, 096101 (2009)]
  (March 18, 2009)

• Shellfish, inkjet technology yield effective medical adhesive
  (North Carolina State University / Eurekalert)

  
  Credit: North Carolina State Univ.

  Using the natural glue that marine mussels use to stick to rocks, and a variation on the inkjet printer, a team of researchers has devised a new way of making medical adhesives that could replace traditional sutures and result in less scarring, faster recovery times and increased precision for exacting operations such as eye surgery. New research shows that adhesive proteins found in the "glue" produced by marine mussels may be used in place of synthetic adhesives, because they are non-toxic and biodegradable. In addition, the mussel proteins can be placed in solution and applied using inkjet technology to create customized medical adhesives.
  [Inkjet printing of bioadhesives, Journal of Biomedical Materials Research Part B: Applied Biomaterials, Volume 89B Issue 1, Pages 28 - 35]
  (March 18, 2009)

• Device using Si-based memristive system demonstrated
  (University of Michigan / Physorg)

  
  Credit: Nano Letters

  Researchers have developed a chip composed of nanoscale memristors that can store up to 1 kilobit of information. Previously, only a few memristor circuits had been demonstrated, rather than such a large-scale array, due to reliability and reproducibility issues. While 1 kilobit is not a huge amount of information, the researchers consider it a leap that will make it easier to scale the technology so it can store much more data. They demonstrated CMOS-compatible, ultra-high-density memory arrays based on a silicon memristive system. The density of a memristor-based memory chip could be at least an order of magnitude higher than current transistor-based chips. Another benefit of memristor memory is that it's not volatile, as today's DRAM memory is.
  [High-Density Crossbar Arrays Based on a Si Memristive System, Nano Lett., 2009, 9 (2), pp 870–874 DOI: 10.1021/nl8037689]
  (March 18, 2009)

• Liquid-liquid phase transition in silicon confirmed
  (Carnegie Mellon University / Eurekalert)

  Using rigorous computer calculations, researchers have established evidence that supercooled silicon experiences a liquid-liquid phase transition, where at a certain temperature two different states of liquid silicon exist. The two states each have unique properties that could be used to develop new silicon-based materials. Furthermore, the methods developed can be applied to gain a better understanding of other materials. The computations revealed that a liquid-to-liquid phase shift, evidenced by the presence of a van der Waals loop, occurred when silicon was supercooled to 1200 degrees Kelvin; silicon normally freezes at 1700 degrees Kelvin. A van der Waals loop occurs when pressure grows as volume increases, marking a thermodynamically unstable situation. The unstable condition is resolved by transforming into two coexisting states of differing densities in this case two distinct forms of liquid silicon, each having its own unique and dissimilar properties. One was high density and highly coordinated with metallic properties, much like normal liquid silicon, and the other was low density, low-coordinated and semi-metallic, with a structure closer to that of solid silicon.
  [Liquid-Liquid Transition in Supercooled Silicon Determined by First-Principles Simulation, Phys. Rev. Lett. 102, 075701 (2009)]
  (March 17, 2009)

• Polymer coats multi-task in drug delivery
  (Royal Society of Chemistry)

  
  Credit: Chem. Commun.

  Polymer spheres with a sugar coating on the outside and a plastic coating on the inside have been developed. This gives them dual functionality to target and deliver drugs. Researchers made the spheres by dissolving glycosylated polybutadiene-poly(ethylene oxide) block copolymers in water. When dissolved, the copolymers spontaneously formed hollow colloids called vesicles with a glucose coating on the outside and a poly(ethylene oxide) coating on the inside. The polymer vesicles could be used as living cell mimics or drug delivery vessels. Thanks to their adjustable properties - stability, fluidity and dynamics - they could be better models for biomedical research than vesicles made from the phospholipids found in cells. Usually, the coatings on both sides of a vesicle's membrane are the same.
  [Glycopolymer vesicles with an asymmetric membrane, Chem. Commun., 2009, 1478 - 1480, DOI: 10.1039/b820887e]
  (March 17, 2009)

• Polymer coating heals itself
  (The New York Times)

  
  Credit: Science

  Researchers have tried for years to develop self-healing polymer coatings for various uses. Recent efforts have incorporated microspheres containing bonding chemicals. In another approach described in a new study, what breaks is not a sphere, but a ring-shaped chemical, oxetane, that is incorporated in the polyurethane polymer. Another compound in the polymer, chitosan, forms cross-links at the places where the oxetane breaks, healing the scratch. What makes the method potentially very useful is what causes the cross-links to form: exposure to ultraviolet light. That means that a damaged coating could heal itself in a matter of minutes or hours by being exposed to sunlight, which contains plenty of UV rays.
  [Self-Repairing Oxetane-Substituted Chitosan Polyurethane Networks, Science 13 March 2009: Vol. 323. no. 5920, pp. 1458 - 1460 DOI: 10.1126/science.1167391 ]
  (March 16, 2009)

• Nanowhiskers beat stress test
  (Science)

  
  Credit: Brian L. Wardle, MIT

  How do you make the superstrong composites used in airplanes even stronger? Just add carbon. Researchers have discovered that coating the carbon fibers in composites with more carbon--in this case microscopic carbon nanotubes--increases their toughness substantially. If commercialized, the process could render critical aircraft components and other machinery nearly unbreakable. Currently, engineers sandwich alternating layers of carbon fiber and epoxy resin, and this resin becomes the weak link in the overall laminate. Sufficient stress can casue interlaminar fracture, which can be disastrous for an aircraft in flight. Researchers have now developed a chemical process in which carbon fibers, heated to 750 C, sprout nanotube whiskers. They then wove those stubbly fibers into a fabric, which they injected with epoxy. The nanotubes tied the layers together and created a Velcro-like effect.
  (March 13, 2009)

• Re-engineered battery material allows for rapid recharging
  (MIT)

  
  Credit: Gerbrand Ceder, MIT

  Researchers have created a kind of beltway that allows for the rapid transit of electrical energy through lithium battery material, an advance that could usher in smaller, lighter batteries that could recharge in seconds rather than hours. State-of-the-art lithium rechargeable batteries have very high energy densities --they are good at storing large amounts of charge. The tradeoff is that they have relatively slow power rates -- they are sluggish at gaining and discharging that energy. Traditionally, scientists have thought that the lithium ions responsible, along with electrons, for carrying charge across the battery simply move too slowly through the material. Calculations showed that lithium ions can indeed move very quickly into the material but only through tunnels accessed from the surface. The researchers created a new surface structure that does allow the lithium ions to move quickly around the outside of the material, much like a beltway around a city. When an ion traveling along this beltway reaches a tunnel, it is instantly diverted into it. Using their new processing technique, a small battery was developed that could be fully charged or discharged in 10 to 20 seconds (it takes six minutes to fully charge or discharge a cell made from the unprocessed material).
  [Battery materials for ultrafast charging and discharging, Nature 458, 190-193 (12 March 2009) | doi:10.1038/nature07853]
  (March 13, 2009)

• Nano-sized photocatalyst for artificial photosynthesis
  (Lawrence Berkeley National Laboratory)

  
  Credit: Flavio Robles, Berkeley Lab Public Affairs

  A goal of scientists has been to develop an artificial version of photosynthesis that can be used to produce liquid fuels from carbon dioxide and water. Researchers have now taken a critical step towards this goal with the discovery that nano-sized crystals of cobalt oxide can effectively carry out the critical photosynthetic reaction of splitting water molecules. According to the researchers, "Photooxidation of water molecules into oxygen, electrons and protons (hydrogen ions) is one of the two essential half reactions of an artifical photosynthesis system - it provides the electrons needed to reduce carbon dioxide to a fuel. Effective photooxidation requires a catalyst that is both efficient in its use of solar photons and fast enough to keep up with solar flux in order to avoid wasting those photons. Clusters of cobalt oxide nanocrystals are sufficiently efficient and fast, and are also robust (last a long time) and abundant. They perfectly fit the bill."
  [Nanostructured Cobalt Oxide Clusters in Mesoporous Silica as Efficient Oxygen-Evolving Catalysts, Angewandte Chemie International Edition, Volume 48 Issue 10 (2009) 1841 - 1844]
  (March 11, 2009)