Unprecedented look at oxide interfaces reveals unexpected structures on atomic scale

August 4, 2010

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A new scanning tunneling microscopy and low energy electron diffraction technique developed at Oak Ridge National Laboratory captured this 50 nm x 50 nm image of an oxide surface. Each bright dot is a single atom of material.

Thin layers of oxide materials and their interfaces have been observed in atomic resolution during growth for the first time by researchers at the Center for Nanophase Materials Sciences at the Department of Energy's Oak Ridge National Laboratory, providing new insight into the complicated link between their structure and properties.

"Imagine you suddenly had the ability to see in color, or in 3-D," said the CNMS's Sergei Kalinin. "That is how close we have been able to look at these very small interfaces."

The paper was published online in ACS Nano with ORNL's Junsoo Shin as lead author.

A component of magnetoelectronics and spintronics, oxide interfaces have the potential to replace silicon-based microelectronic devices and improve the power and memory retention of other electronic technologies.

However, oxide interfaces are difficult to analyze at the atomic scale because once the oxides are removed from their growth chamber they become contaminated. To circumvent this problem, ORNL researchers led by Art Baddorf built a unique system that allows scanning tunneling microscopy and low energy electron diffraction to capture images of the top layer of the oxide while in situ, or still in the vacuum chamber where the materials were grown by powerful laser pulses.

Many studies of similar oxide interfaces utilize a look from the side, typically achieved by aberration corrected scanning transmission electron microscopy (STEM). The ORNL team has used these cross-sectional images to map the oxide organization.

However, like a sandwich, oxide interfaces may be more than what they appear from the side. In order to observe the interactive layer of the top and bottom oxide, the group has used scanning tunneling microscopy to get an atomically resolved view of the surface of the oxide, and observed its evolution during the growth of a second oxide film on top.

"Instead of seeing a perfectly flat, square lattice that scientists thought these interfaces were before, we found a different and very complicated atomic ordering," said Baddorf. "We really need to reassess what we know about these materials."

Oxides can be used in different combinations to produce unique results. For instance, isolated, two oxides may be insulators but together the interface may become conductive. By viewing the atomic structure of one oxide, scientists can more effectively couple oxides to perform optimally in advanced technological applications such as transistors.

Kalinin says the correct application of these interface-based materials may open new pathways for development of computer processors and energy storage and conversion devices, as well as understanding basic physics controlling these materials.

"In the last 10 years, there has been only limited progress in developing beyond-silicon information technologies," Kalinin said. "Silicon has limitations that have been reached, and this has motivated people to explore other options."

Atomic resolution of interface structures during oxide growth will better enable scientists to identify defects of certain popular oxide combinations and could help narrow selections of oxides to spur new or more efficient commercial applications.

Provided by Oak Ridge National Laboratory (news : web)

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World record data density for ferroelectric recording

August 17, 2010 Scientists at Tohoku University in Japan have recorded data at a density of 4 trillion bits per square inch, which is a world record for the experimental "ferroelectric" data storage method. As described the journal Applied Physics Letters, which is published by the American Institute of Physics, this density is about eight times the density of today's most advanced magnetic hard-disk drives.

The data-recording device scans a tiny cantilever tip that rides in contact with the surface of a ferroelectric material. To write data, an electric pulse is sent through the tip, changing the electric polarization and nonlinear dielectric constant of a tiny circular spot in the substrate beneath. To read data, the same tip detects the variations in nonlinear dielectric constant in the altered regions.

"We expect this ferroelectric data storage system to be a candidate to succeed magnetic hard disk drives or flash memory, at least in applications for which extremely high data density and small physical volume is required," said Dr. Yasuo Cho.

In earlier experiments, the researchers had noticed one problem: When the data being written required that several consecutive marks be written next to each other, the written polarized regions expanded the normal diameter and coalesced to the point the bits were not distinct. Cho and Kenkou Tanaka then developed a method for anticipating strings of consecutive marks in the data and reducing the writing-pulse voltage by up to about 10 percent, which resulted in clear and distinct data marks.

While ferroelectric storage has the advantage of using only electric methods -- nothing magnetic or thermal -- to achieve its record-high density, Cho and Tanaka are well aware that many practical improvements would be needed for commercial viability. Such advances would include increasing the speed and accuracy of reading the data and developing a low-cost ferroelectric substrate.

Another risk is that existing data storage technologies continue to improve beyond the ferroelectric's capabilities. Disk drive maker Seagate, for example, has said it can envision achieving a density of 50 trillion bits per square inch.

Provided by American Institute of Physics

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Nanoparticles for cultural heritage conservation

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(PhysOrg.com) -- The conservation of Mayan wall paintings at the archaeological site of Calakmul (Mexico) will be one on the subjects touched upon by Piero Baglioni (based at the University of Florence) in his invited lecture at the 3rd European Chemistry Congress in Nurnberg in September.

In a special issue of Chemistry -- A European Journal, which contains papers by many of the speakers at this conference, he reports on the latest developments on the use of humble calcium and barium hydroxides nanoparticles as a versatile and highly efficient tool to combat the main degradation processes that affect wall paintings.

La Antigua Ciudad Maya de Calakmul is located in the Campeche state (Mexico) and is one of the most important cities of the Classic Maya period (AD 250-800). The excavation of this site (set up in 1993) involves, under the supervision of the archaeologist Ramon Carrasco, archaeologists, architects, engineers, conservators and epigraphists, besides other specialists. Since 2004, the Center for Colloid and Surface Science (CSGI) at the University of Florence (CSGI), and currently directed by Piero Baglioni, has been an active partner, being involved in the study of the painting technique and in the development of nanotechnology for the consolidation and protection of the wall paintings and limestone.

Over the last decades, polymers, mainly acrylic and vinyl resins, have been widely used to consolidate wall paintings and to confer protection and hydrorepellency to the painted layer. However, contrary to the expectations, polymers used for the protection of wall paintings have induced further degradation of the works of art and their chemical modifications, such as cross-linking, strongly hampers their removal. Hence, there has been a need to develop new methods of conservation.

In Florence, Piero Baglioni and his group have pioneered the use of calcium hydroxide nanoparticles to restore wall paintings, the degradation of which is basically due to the transformation of calcium carbonate into gypsum. Nanoparticles of calcium hydroxide efficiently interact with carbon dioxide to reform calcium carbonate and replace the degraded original ligand, leading to the re-cohesion of the paint layer. However, when large amounts of soluble sulfates (i.e., sodium or magnesium sulfates) are present in a wall painting, consolidation with calcium hydroxide nanoparticles might not produce durable results. In fact, sulfate ions can react with calcium hydroxide to give a double-exchange reaction, producing the slightly soluble gypsum (calcium sulfate dihydrate). Barium hydroxide nanoparticles represent a really useful alternative and a complementary tool to hinder this process. Hence, mixed formulations can be used for the pre-consolidation of surfaces largely contaminated by sulfates.

In Calakmul, Mayan paintings have been successfully treated by using a mixture of calcium and barium hydroxide nanoparticles as a dispersion in 1-propanol. The consolidation effect was significant already after one week. The result of the application is that the paintings are now stable and do not show ongoing degradation processes. Thus, nanoscience has opened up enormous potential for Cultural Heritage conservation, due to the unique properties that the reduction in particle size confers to nanomaterials compared to their micrometric counterparts.

Study predicts nanoscience will greatly increase efficiency of next-generation solar cells

As the fastest growing energy technology in the world, solar energy continues to account for more and more of the world?s energy supply. Currently, most commercial photovoltaic power comes from bulk semiconductor materials. But in the past few years, scientists have been investigating how semiconductor nanostructures can increase the efficiency of solar cells and the newer field of solar fuels.

Although there has been some controversy about just how much nanoscience can improve solar cells, a recent overview of this research by Arthur Nozik, a researcher at the National Renewable Energy Laboratory (NREL) and professor at the University of Colorado, shows that semiconductor nanostructures have significant potential for converting solar energy into electricity.

In his overview, which is published in a recent issue of Nano Letters, Nozik has summarized the current status of several approaches to improving photovoltaics with nanoscience. As he explains, the advantages of semiconductor nanostructures arise from the quantum confinement of negative electrons and positive holes into very small regions of space in the nanocrystals. Quantum confinement can occur in one, two or three dimensions; in three dimensions, the semiconductors are called quantum dots. In any regime, the quantum confinement produces quantization effects, resulting in unique optical and electronic properties.

?There are two main theoretical advantages of incorporating quantum dots into solar cells and photovoltaics: higher efficiency and lower cost,? Nozik told PhysOrg.com. ?There is a theoretical possibility based on thermodynamic calculations of increasing the efficiency of present day solar cells by a very significant amount of 50-100%. In addition, quantum dots could lower the capital cost of solar cell production in terms of cost per unit area. The combination of lower cost per unit area and higher conversion efficiency would lower the cost of photovoltaic power expressed as cost per peak watt. Present silicon cells are expensive (about three times the cost of conventional electricity), but quantum dots are based on less expensive low-temperature solution chemistry methods, plus they could produce higher conversion efficiencies. However, there is still a lot of work to be done before quantum dots are commercially available.?

The basic principle of photovoltaic solar cells is to absorb photons from incident solar radiation with energies above the semiconductor band gap, and use the photons to create free electrons and holes (called charge carriers). In order to increase the efficiency of the system, it is important to form as many charge carriers as possible from the absorbed photons. This is where the quantum confinement effects become very useful, as the effects couple photogenerated electrons and holes into bound electron-hole pairs called excitons, and encourage the efficient formation of more than one exciton from a single absorbed photon. In quantum dots. the process is called multiple exciton generation (MEG). Among its advantages, MEG is more efficient and can occur with lower-energy photons in the visible region of the solar spectrum compared to a multiplication process of charge carriers in bulk semiconductors (a process called impact ionization, which is generally restricted to the ultraviolet region where solar photons are absent or scarce).

To generate multiple excitons, the MEG process must compete with the rapid cooling of initial photogenerated high-energy excitons (called ?hot excitons?). The hot excitons are created by the absorption of energetic blue or near-ultraviolet photons. In bulk semiconductors at room temperature and above, the photogenerated electrons and holes are uncoupled and exist as free charge carriers (called ?hot carriers?). The excess energy of hot excitons or hot carriers can quickly lose their excess kinetic energy through electron-phonon interactions and convert it into heat, which accounts for significant loss of conversion efficiency. However, Nozik notes that, despite some controversy, recent studies have shown that the rate of MEG can be much faster than the hot exciton cooling rate, resulting in an overall higher efficiency of electron-hole pair multiplication. But despite early initial reports of quantum yields of 200% in quantum dot photoelectrochemical solar cells, no quantum dot-based photovoltaic device to date has shown an actual enhanced power conversion efficiency due to MEG.

?Generally, the goal is to produce systems that have efficiencies close to the theoretical limit,? Nozik said. ?The theoretical efficiency is about 45%, while the lab efficiency of present quantum dot solar cells is about 3-5%. That?s a big gap; we need to understand what limits the efficiency in these new approaches.?

Despite the controversy about MEG, Nozik concludes that the possibilities for quantum dot solar cells and other nanostructures that use quantum confinement look promising, although much more work still needs to be done. One issue that may help MEG to reach its full potential is to ensure that the additional excitons are being quickly collected, since they decay within about 20-100 picoseconds after formation. Most importantly, Nozik emphasizes that researchers should strive toward reaching the maximum theoretical efficiency of solar cells.

?There?s a certain degree of controversy about these third generation approaches because they?re new and not completely understood,? Nozik said. ?In the past, some results could not be reproduced in different labs. But now more and more people in recent years are reproducing positive results. Los Alamos and NREL are measuring these effects in a new U.S. DOE Energy Frontier Research Center with different techniques, and getting the same answer. So it is a real effect, a positive effect. However, some people are still skeptical and think that we?re never going to reach those values [of theoretical efficiency]. But there is no fundamental reason why we can?t reach those values. It just takes more research, more effort, and more understanding.?

New architectures for nano brushes: Bitty structures can be tailored in many shapes

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An atomic force microscopy topographic image of the nano-brushes. The relative heights of the brushes can be tailored by changing the substrate and initiators.

(PhysOrg.com) -- Just as cilia lining the lungs help keep passages clear by moving particles along the tips of the tiny hair-structures, man-made miniscule bristles known as nano-brushes can help reduce friction along surfaces at the molecular level, among other things.

In their latest series of experiments, Duke University engineers have developed a novel approach to synthesize these nano-brushes, which could improve their versatility in the future. These polymer brushes are currently being used in biologic sensors and microscopic devices, such as microcantilevers, and they will play an important role in the future drive to miniaturization, the researchers said.

Nano-brushes are typically made of polymer molecules grown on flat surfaces with strands of the molecules growing up and out from a surface, much like hairs on a brush. Polymers are large man-made molecules ubiquitous in the manufacture of everyday products.

Like microscopic orchard keepers, the Duke scientists have grafted bundles of polymer ?limbs? on flat surfaces known as substrates, already covered with brush bristles. In their approach, two dissimilar brushes can be joined and patterned on the micro-scale. Because the ?limbs? can be made out of a different substance than the substrate, the scientists believe these nano-structures are able to significantly modify the properties of a given surface.

To make such a nano-brush, scientists add a chemical known as an initiator to the flat surface, which spurs the growth of the strands.

?One of the common ways of growing brushes is much like a dot matrix printer, with an initiator being the ink ?printed? onto an inorganic substrate, such as a silicon wafer or a gold surface, which then causes the brush bristles to grow in specified patterns,? said Stefan Zauscher, Alfred M. Hunt Faculty Scholar and associate professor of mechanical engineering and materials science at Duke?s Pratt School of Engineering.

?In our patterning approach we are now also able to initiate polymer brush growth on existing brush substrates and thus obtain patterned block copolymer brushes, just like grafts, on polymeric substrates,? Zauscher said. ?The ability to create more intricate brush structures provides the potential for using them in biomedical applications as sensors for the detection of proteins or glucose.?

The results of his team?s experiments were published online in the journal Small. The research is supported by the National Science Foundation.

Zauscher said this new approach could be readily expanded to many other types of polymers, and to make either single or double layers of brushes. These nano-brushes, he said, would have many potential uses, and would open up the possibilities for building more complicated polymer architectures, which are much in demand for current and future technologies.

In recent research, published earlier in the journal Advanced Materials, Zauscher showed that stimulus-responsive nano-brushes resemble and act like sea anemones, which have a multitude of arms reaching up from an attached base. In the same fashion as these sea animals, nano-brushes can be used to capture and release micro-particles as they move across a surface.

Caltech researchers design a new nanomesh material

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Top: A scanning electron microscope image shows the grid of tiny holes in the nanomesh material. Bottom: In this drawing, each sphere represents a silicon atom in the nanomesh. The colorful bands show the temperature differences on the material, with red being hotter and blue being cooler.

(PhysOrg.com) -- Computers, light bulbs, and even people generate heat?energy that ends up being wasted. With a thermoelectric device, which converts heat to electricity and vice versa, you can harness that otherwise wasted energy. Thermoelectric devices are touted for use in new and efficient refrigerators, and other cooling or heating machines. But present-day designs are not efficient enough for widespread commercial use or are made from rare materials that are expensive and harmful to the environment.

Researchers at the California Institute of Technology (Caltech) have developed a new type of material?made out of silicon, the second most abundant element in Earth's crust?that could lead to more efficient thermoelectric devices. The material?a type of nanomesh?is composed of a thin film with a grid-like arrangement of tiny holes. This unique design makes it difficult for heat to travel through the material, lowering its thermal conductivity to near silicon's theoretical limit. At the same time, the design allows electricity to flow as well as it does in unmodified silicon.

"In terms of controlling thermal conductivity, these are pretty sophisticated devices," says James Heath, the Elizabeth W. Gilloon Professor and professor of chemistry at Caltech, who led the work. A paper about the research will be published in the October issue of the journal Nature Nanotechnology.

A major strategy for making thermoelectric materials energy efficient is to lower the thermal conductivity without affecting the electrical conductivity, which is how well electricity can travel through the substance. Heath and his colleagues had previously accomplished this using silicon nanowires?wires of silicon that are 10 to 100 times narrower than those currently used in computer microchips. The nanowires work by impeding heat while allowing electrons to flow freely.

In any material, heat travels via phonons?quantized packets of vibration that are akin to photons, which are themselves quantized packets of light waves. As phonons zip along the material, they deliver heat from one point to another. Nanowires, because of their tiny sizes, have a lot of surface area relative to their volume. And since phonons scatter off surfaces and interfaces, it is harder for them to make it through a nanowire without bouncing astray. As a result, a nanowire resists heat flow but remains electrically conductive.

But creating narrower and narrower nanowires is effective only up to a point. If the nanowire is too small, it will have so much relative surface area that even electrons will scatter, causing the electrical conductivity to plummet and negating the thermoelectric benefits of phonon scattering.

To get around this problem, the Caltech team built a nanomesh material from a 22-nanometer-thick sheet of silicon. (One nanometer is a billionth of a meter.) The silicon sheet is converted into a mesh?similar to a tiny window screen?with a highly regular array of 11- or 16-nanometer-wide holes that are spaced just 34 nanometers apart.

Instead of scattering the phonons traveling through it, the nanomesh changes the way those phonons behave, essentially slowing them down. The properties of a particular material determine how fast phonons can go, and it turns out that?in silicon at least?the mesh structure lowers this speed limit. As far as the phonons are concerned, the nanomesh is no longer silicon at all. "The nanomesh no longer behaves in ways typical of silicon," says Slobodan Mitrovic, a postdoctoral scholar in chemistry at Caltech. Mitrovic and Caltech graduate student Jen-Kan Yu are the first authors on the Nature Nanotechnology paper.

When the researchers compared the nanomesh to the nanowires, they found that?despite having a much higher surface-area-to-volume ratio?the nanowires were still twice as thermally conductive as the nanomesh. The researchers suggest that the decrease in thermal conductivity seen in the nanomesh is indeed caused by the slowing down of phonons, and not by phonons scattering off the mesh's surface. The team also compared the nanomesh to a thin film and to a grid-like sheet of silicon with features roughly 100 times larger than the nanomesh; both the film and the grid had thermal conductivities about 10 times higher than that of the nanomesh.

Although the electrical conductivity of the nanomesh remained comparable to regular, bulk silicon, its thermal conductivity was reduced to near the theoretical lower limit for silicon. And the researchers say they can lower it even further. "Now that we've showed that we can slow the phonons down," Heath says, "who's to say we can't slow them down a lot more?"

The researchers are now experimenting with different materials and arrangements of holes in order to optimize their design. "One day, we might be able to engineer a material where you not only can slow the phonons down, but you can exclude the phonons that carry heat altogether," Mitrovic says. "That would be the ultimate goal."

Buried silver nanoparticles improve organic transistors

August 10, 2010 Out of sight is not out of mind for a group of Hong Kong researchers who have demonstrated that burying a layer of silver nanoparticles improves the performance of their organic electronic devices without requiring complex processing. Their findings in a report published in the journal Applied Physics Letters, which is published by the American Institute of Physics (AIP).

A team led by Professors Paddy Chan and Dennis Leung of the Hong Kong Polytechnic University has shown that a simple layer of silver nanoparticles placed between two layers of the organic semiconductor pentacene improves performance just as much as painstakingly placing nanoparticles atop a tiny floating gate region.

Because certain metal nanoparticles trap electric charges very effectively, they are becoming a popular additive for enhancing transistor performance and producing thinner transistors. Sandwiching a layer of nanoparticles is much more compatible with the low-cost, continuous roll-to-roll fabrication techniques used to make organic electronics than the more intricate patterning required to put material just in the transistor gate area.

Moreover, Chan's group showed that the thickness of the nanoparticle layer changes the device performance in predictable ways that can be used to optimize transistor performance to meet application requirements.

Transistors made with a 1-nanometer nanoparticle layer, for example, have stable memory that lasts only about three hours, which would be suitable for memory buffers. Transistors having a 5-nanometer-thick layer are more conventional and retain their charge for a much longer time.

"We believe that organic memory has a very high potential for use in next-generation memory devices -- such as touchscreens and electronic paper -- where their flexibility and low-cost are most important," said Dr. Sumei Wang, a postdoctoral research fellow of the team.

More information: "Nonvolatile organic transistor-memory devices using various thicknesses of silver nanoparticle layers" , Paddy K. L. Chan, Sumei Wang and Chi Wah Leung, http://apl.aip.org … 2/p023511_s1

Provided by American Institute of Physics

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Nanocatalyst is a gas: New formula could make fuel production better, greener

September 20, 2010

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This is an atomic-level image of tungsten oxide nanoparticles (green circles) on zirconia support. The other circles show the less-active forms of tungsten oxide.

A nanoparticle-based catalyst developed at Rice University may give that tiger in your tank a little more roar.

A new paper in the Journal of the American Chemical Society details a process by Rice Professor Michael Wong and his colleagues that should help oil refineries make the process of manufacturing gasoline more efficient and better for the environment.

In addition, Wong said, it could produce higher-octane gasoline and save money for an industry in which a penny here and a penny there add millions to the bottom line.

Wong's team at Rice, in collaboration with labs at Lehigh University, the Centre for Research and Technology Hellas and the DCG Partnership of Texas, reported this month that sub-nanometer clusters of tungsten oxide lying on top of zirconium oxide are a highly efficient catalyst that turns straight-line molecules of n-pentane, one of many hydrocarbons in gasoline, into better-burning branched n-pentane.

While the catalytic capabilities of tungsten oxide have long been known, it takes nanotechnology to maximize their potential, said Wong, a Rice professor of chemical and biomolecular engineering and of chemistry.

After the initial separation of crude oil into its basic components -- including gasoline, kerosene, heating oil, lubricants and other products -- refineries "crack" (by heating) heavier byproducts into molecules with fewer carbon atoms that can also be made into gasoline. Catalysis, a chemical process, further refines these hydrocarbons.

That's where Wong's discovery comes in. Refineries strive to make better catalysts, he said, although "compared with the academic world, industry hasn't done much in terms of new synthesis techniques, new microscopy, new biology, even new physics. But these are things we understand in the context of nanotechnology.

"We have a way to make a better catalyst that will improve the fuels they make right now. At the same time, a lot of existing chemical processes are wasteful in terms of solvents, precursors and energy. Improving a catalyst can also make the chemical process more environmentally friendly. Knock those things out, and they gain efficiencies and save money."

Wong and his team have worked for several years to find the proper mix of active tungsten oxide nanoparticles and inert zirconia. The key is to disperse nanoparticles on the zirconia support structure at the right surface coverage. "It's the Goldilocks theory - not too much, not too little, but just right," he said. "We want to maximize the amount of these nanoparticles on the support without letting them touch.

"If we hit that sweet spot, we can see an increase of about five times in the efficiency of the catalyst. But this was very difficult to do."

No wonder. The team had to find the right chemistry, at the right high temperature, to attach particles a billionth of a meter wide to grains of zirconium oxide powder. With the right mix, the particles react with straight n-pentane molecules, rearranging their five carbon and 12 hydrogen atoms in a process called isomerization.

Now that the catalyst formula is known, making the catalyst should be straightforward for industry. "Because we're not developing a whole new process - just a component of it - refineries should be able to plug this into their systems without much disruption," Wong said.

Maximizing gasoline is important as the world develops new sources of energy, he said. "There's a lot of talk about biofuels as a significant contributor in the future, but we need a bridge to get there. Our discovery could help by stretching current fuel-production capabilities."

The perfect nanocube: Precise control of size, shape and composition

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These electron microscope images show perfect-edged nanocubes produced in a one-step process created at NIST that allows careful control of the cubes? size, shape and composition. Credit: NIST

(PhysOrg.com) -- With growing interest in using nanoparticles for everything from antibacterial socks to medical imaging to electronic devices, the need to understand the environmental, health and safety risks of these particles also grows. Researchers at the National Institute of Standards and Technology have developed a simple process for producing nanocrystals that will enable studies of certain physical and chemical properties that affect how nanoparticles interact with the world around them.

Because nanoparticles behave differently from bulk samples of the same material, new tests to understand how they affect biological systems must be developed. Toxicologists determine the hazards posed by nanoparticles by introducing them to a biological system and monitoring the effects, but they currently lack a set of control particles whose size, shape and composition have been carefully produced and characterized.

In a recent paper published in Angewandte Chemie,* NIST scientists describe a one-step process that allows them to control the size, shape and composition of gold-copper alloy nanocrystals to create perfect-edged nanocubes as small as 3.4 nanometers?just half the thickness of a cell wall and on the same size range as DNA.

The researchers combined and heated gold and copper precursors with other chemicals to produce highly crystalline, homogeneous, perfect nanocubes with abundant yield. To study the formation process, they removed samples at 1 hour, 1.5 hours, 5 hours, and 24 hours and found that just five hours were needed to produce perfectly cubic nanoparticles of uniform size. By adjusting the ratios of the chemicals in the original solution and the reaction time, they were able to precisely control the size, shape and composition of the nanocubes. This process is unique in allowing control of the ratio of copper to gold atoms within the nanocube to either 3:1 or 1:3.

"It's a simple process, and to the best of our knowledge is the first to use synthetic chemistry, or 'bottom up' technology, to produce gold-containing nanocubes below 5 nanometers. Anything less than 10 nanometers has been extremely challenging due to the mobile behavior of the gold atoms," says NIST physicist Angela R. Hight Walker, who wrote the paper with Yonglin Liu, a guest researcher at NIST.

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These electron microscope images show perfect-edged nanocubes produced in a one-step process created at NIST that allows careful control of the cubes' size, shape and composition. Credit: NIST

The NIST-developed process for creating such nanocubes will allow toxicologists to systematically alter one of the nanocubes' characteristics and observe how the change affects the biological response, if at all.

This synthesis and the resulting high-quality nanocubes may have other applications in areas such as solar energy, says Liu. "Typically, we cannot make big batches of high-quality samples for testing; now we can."

The perfect-edged nanocubes are unique from other nanocubes in the literature, says Hight Walker. The sharp edges, as opposed to truncated or rounded edges, will enable different, more reactive chemistry that could be beneficial in applications such as catalysis?in which the nanocubes would be used to initiate or enhance a chemical reaction.

Wax, soap clean up obstacles to better batteries

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These tiny flakes of lithium manganese phosphate can serve as electrodes for batteries. A new method uses wax and soap to form high quality materials. The one-step method will allow battery developers to explore lower-priced alternatives to the rechargeable lithium ion batteries currently on the market.

A little wax and soap can help build electrodes for cheaper lithium ion batteries, according to a study in August 11 issue of Nano Letters. The one-step method will allow battery developers to explore lower-priced alternatives to the lithium ion-metal oxide batteries currently on the market.

"Paraffin provides a medium in which to grow good electrode materials," said material scientist Daiwon Choi of the Department of Energy's Pacific Northwest National Laboratory. "This method will help researchers investigate cathode materials based on cheaper transition metals such as manganese or iron."

Consumers use long-lasting rechargeable lithium ion batteries in everything from cell phones to the latest portable gadget. Some carmakers want to use them in vehicles. Most lithium ion batteries available today are designed with an oxide of metal such as cobalt, nickel, or manganese. Choi and colleagues at PNNL and State University of New York at Binghamton wanted to explore both cheaper metals and the more stable phosphate in place of oxide.

The Recharge Tale

These rechargeable batteries work because lithium is selfish and wants its own electron. Positively charged lithium ions normally hang out in metal oxide, the stable, positive electrode in batteries. Metal oxide generously shares its electrons with the lithium ions.

Charging with electricity pumps electrons into the negative electrode, and when the lithium ions see the free-floating negative charges across the battery, they become attracted to life away from the metal oxide cage. So off the lithium ions go, abandoning the metal oxide and its shared electrons to spend time enjoying their own private ones.

But the affair doesn't last -- using the battery in an electronic device creates a conduit through which the slippery electrons can flow. Losing their electrons, the lithium ions slink back to the ever-waiting metal oxide. Recharging starts the whole sordid process over.

Cheaper, Stabler

While cobalt oxide performs well in lithium batteries, cobalt and nickel are more expensive than manganese or iron. In addition, substituting phosphate for oxide provides a more stable structure for lithium.

Lithium iron phosphate batteries are commercially available in some power tools and solar products, but synthesis of the electrode material is complicated. Choi and colleagues wanted to develop a simple method to turn lithium metal phosphate into a good electrode.

Lithium manganese phosphate -- LMP -- can theoretically store some of the highest amounts of energy of the rechargeable batteries, weighing in at 171 milliAmp hours per gram of material. High storage capacity allows the batteries to be light. But other investigators working with LMP have not even been able to eek out 120 milliAmp hours per gram so far from the material they've synthesized.

Choi reasoned the 30 percent loss in capacity could be due to lithium and electrons having to battle their way through the metal oxide, a property called resistance. The less distance lithium and electrons have to travel out of the cathode, he thought, the less resistance and the more electricity could be stored. A smaller particle would decrease that distance.

But growing smaller particles requires lower temperatures. Unfortunately, lower temperatures means the metal oxide molecules fail to line up well in the crystals. Randomness is unsuitable for cathode materials, so the researchers needed a framework in which the ingredients -- lithium, manganese and phosphate -- could arrange themselves into neat crystals.

Wax On, Wax Off

Paraffin wax is made up of long straight molecules that don't react with much, and the long molecules might help line things up. Soap -- a surfactant called oleic acid -- might help the growing crystals disperse evenly.

So, Choi and colleagues mixed the electrode ingredients with melted paraffin and oleic acid and let the crystals grow as they slowly raised the temperature. By 400 Celsius (four times the temperature of boiling water), crystals had formed and the wax and soap had boiled off. Materials scientists generally strengthen metals by subjecting them to high heat, so the team raised the temperature even more to meld the crystals into a plate.

"This method is a lot simpler than other ways of making lithium manganese phosphate cathodes," said Choi. "Other groups have a complicated, multi-step process. We mix all the components and heat it up."

To measure the size of the miniscule plates, the team used a transmission electron microscope in EMSL, DOE's Environmental Molecular Sciences Laboratory on the PNNL campus. Up close, tiny, thin rectangles poked every which way. The nanoplates measured about 50 nanometers thick -- about a thousand times thinner than a human hair -- and up to 2000 nanometers on a side. Other analyses showed the crystal growth was suitable for electrodes.

To test LMP, the team shook the nanoplates free from one another and added a conductive carbon backing, which serves as the positive electrode. The team tested how much electricity the material could store after charging and discharging fast or slowly.

When the researchers charged the nanoplates slowly over a day and then discharged them just as slowly, the LMP mini battery held a little more than 150 milliAmp hours per gram of material, higher than other researchers had been able to attain. But when the battery was discharged fast -- say, within an hour, that dropped to about 117, comparable to other material.

Its best performance knocked at the theoretical maximum at 168 milliAmp hours per gram, when it was slowly charged and discharged over two days. Charging and discharging in an hour -- a reasonable goal for use in consumer electronics -- allowed it to store a measly 54 milliAmp hours per gram.

Although this version of an LMP battery charges slower than other cathode materials, Choi said the real advantage to this work is that the easy, one-step method will let them explore a wide variety of cheap materials that have traditionally been difficult to work with in developing lithium ion rechargeable batteries.

In the future, the team will change how they incorporate the carbon coating on the LMP nanoplates, which might improve their charge and discharge rates.

Nanotechnology Research: Extending Man’s Horizon

There is hardly any doubt that nanotechnology is very beneficial to man. With all the applications this new frontier of knowledge has seen from the human body to industries and chemicals, thus far, nanotechnology has lived up to its name in enhancing the wealth of knowledge possessed by man.

Despite this gains however, nanotechnology research continues on high gear to discover more truths that will help man in so many ways. Today, nanotechnology research is not only limited to the laboratories of scientific bodies, personnel under the employ of big companies that benefit from nanotechnology are also doing their own nanotechnology researches.

Frontiers of Nanotechnology Application

The following are the various areas where some of the most prominent nanotechnology research are being undertaken:

The field of heavy equipment and industries are some of the busiest areas of nanotechnology research. With the projected benefits nanotechnology promises these industries, there is no wonder why they should busy themselves with furthering the impact of nanotechnology. The main benefit comes in the form of creating machineries that are light yet very durable. When equipments are made lighter, they do not cause much strain on the engine, thus it maximizes the consumption of fuel.The aerospace and aircraft production industries are also bound to benefit from continuing nanotechnology research. This is because with nanotech, aircraft and rocket parts are made lighter, thus minimizing fuel consumption. As a result, companies that are in the air travel business are also benefited from lower fuel consumption from aircrafts that are lighter and speedier.In the field of optical technology, nanotechnology research is used to develop lenses and glasses that are scratch-resistant and tough. It also results to the creation of lenses that do not cause interference with one’s vision, thus giving the wearer clarity of sight sans any inconvenience.

Know the Various Nanotech Companies

Because nanotechnology is one of the hottest scientific products today, consumers and product users need to be familiar with the various nanotechnology companies that can provide them their needs for nanotech and its applications. Companies that specialize in nanotechnology cover almost anything under the sun, although most of these are involved in industries such as in engineering and in automotive applications.

Regulating Nanotech with Nanotechnology Ethics

The promises that nanotechnology brings to mankind is so huge that there are some sectors who fear that if its applications are not properly regulated, it can bring harm to mankind instead of the good it is projected to give everyone. As a result, calls for the setting of regulatory procedures in its applications are supported not only by scientists and the industry that benefits from it but also from various groups representing ordinary people. As such, nanotechnology ethics has come to be seen as something as important as nanotechnology itself. In doing so, the scientific community is only reacting to experiences with epoch-setting technologies in the past. Knowing the possible horrors that can affect mankind, nanotechnology ethics are in place for every disciple of the learning to observe.

Defining the Limits of Nanotechnology

Because the full impact of nanotechnology has not been fully realized, various governments and scientists are afraid that the unrestricted applications of nanotechnology will result to health and environmental problems. Characteristic of something that is not fully regulated in a uniform manner, various nations have their own reactions to nanotechnology applications. For example, some aspects of nanotechnology are allowed in the United States with a wide range of freedom

Safety Concerns with Nanotechnology: Knowing the Risks and Benefits

Nanotechnology is one of the hottest scientific discoveries of the present times. This is because nanotechnology presents a lot of promise that all other treatment methodologies before it were unable to deliver. Moreover, nanotechnology also saw applications in other areas aside from the fields it was intended for. As a result, the fields of applications of nanotechnology are as varied as the possible risks that come with it. As such, safety concerns with nanotechnology aired by ordinary citizens and experts alike must not be ignored because it is one of the ways to make the technology very safe for anyone using them.

Common Concerns with Nanotechnology

The following are some of the most common concerns expressed by people on the use of nanotechnology:

Nanotechnology is a new scientific application. Although this can also mean to be a benefit for mankind, there are safety concerns related to its applications mainly because of the fact that it is something that is not yet fully tested. One of the safety concerns with nanotechnology in this field involves the application of the technology in medical and health fields. Some are afraid that they might trigger harmful effects instead of the intended beneficial effects.

Nanotechnology in Cars: Drive of the Future

Cars are common expressions of how developed a nation is. True to this statement, the most developed nations of the world have their own and stable car manufacturing industries that they export to the rest of the world, earning revenues for the source country. More than that, some nations have become synonymous with the brand and quality of their manufactured cars as the case of Japan, Germany, and the United States. Unsatisfied with this and all the modifications they have created on their cars, they have taken automotive technology a bit further by using nanotechnology for cars.

When nanotechnology was discovered, the automotive industry was not seen as a possible beneficiary from this piece of knowledge. Yet in time, the automotive industry became one of the heaviest users of nanotech. With nanotechnology in cars, vehicles were made more efficient.

The Application of Nanotechnology in Cars

The following are some of the most common examples of the application of nanotechnology in cars:

Engine and transmission systems. In contemporary cars, a large share of the vehicle’s weight is due to the weight of the engine and the transmission system of the vehicle. As a result, cars are fuel-hungry because of the need to push forward such a heavy machine. Nonetheless, with the advent of alloys, engines were made lighter somewhat but not sufficient to make them fuel-efficient. The answer came with the arrival of nanotechnology. With nanotechnology, engines and parts were made a lot lighter, thus eliminating the need to consume more fuel just to power the vehicle forward.

Nanotechnology in Pharmaceutic Manufacturing

Imagine producing essential products such as medicines, fabric, glass, steel, and plastic materials for your home and office in almost in a blink of an eye. Or think about treating chronic and serious health conditions such as cancer, lupus, or even HIV thru a tiny device that can travel inside the human body and destroy the infected cells before they spread and cause debilitating damages to the body. You picture this: a tiny device, even smaller than an atom but can store massive information such as all the information contained in an international library. If you think that is quite impossible, then you probably haven’t heard about nanotechnology yet.

What Is Nanotechnology?

Nanotechnology used to be regarded in the fields of science as a science fiction: impossible and unattainable. But over time, nanotechnology and its uses among different facets of the society such as agriculture, home improvement, industrial, even in areas of environmental protection is already widely accepted and practiced. Nanotechnology in pharmaceutic manufacturing is also being done in big pharmaceutical and health companies. But what is nanotechnology? For people who are not in the fields of sciences and engineering, nanotechnology may be an unfamiliar word.

Nanotechnology is the engineering of functional systems at the molecular scale or thru tiny engineering. In essence, nanotechnology is the probability to build things from the bottom up using scientific techniques and tools that are currently developed today to come up with advanced, complete, and highly usable and essential products.

What Are the Benefits of Nanotechnology?

The basic benefit of nanotechnology is its ability to produce important products in a massive scale with the least or minimum cost. If managed properly, meaning, if the makers of products using nanotechnology would only make products that will provide benefit to mankind with utmost safety precautions in mind, nanotechnology is the next wave of industrial revolution. Nanotechnology will eliminate production costs for materials, labor, and energy because it can produce bigger and better things invented by our forefathers at a staggering speed and amazing precision there is no room for mistakes.

How Can Nanotechnology Be Applied to Pharmaceutic Manufacturing?

Man is exposed to varied health hazards these days due to the advent of science and technology that most often emit hazardous free radicals and pollutants that contribute to the general decline of mankind. Because of this and also because of man’s increasingly sedentary lifestyle, people need more medication for varied diseases. Millions of people are in need of medication and medical maintenance that is why pharmaceutical companies is a booming business.

Conserve Energy with Nanotechnology Solar Panel

With the evident effects of environmental neglect, energy all over the world is becoming more and more depleted. With energy sources becoming scarce, it generally results to a stiff competition to obtain the limited sources for energy resulting to high power charges. There are several sources of energy, and some of them are even natural resources such as wind, solar, and hydro. But even if the sources of energy are natural resources and should be delivered to the people at a lower cost, still, power costs are high due to expenses incurred while generating electricity.

For several years now, scientists and researches has been looking at other means to obtain the following:

minimize generation costs of energyprovide energy to the people without causing any damages to the environmentgenerate renewable and recyclable energy resourcesprovide energy and electricity with the least possible chargesdeliver electricity and energy to the public at the lowest possible cost

Achieving These Goals Using Nanotechnology Solar Panel

Nanotechnology aims to build important things with the use of tiny machines or by producing highly advanced, essential, and quality products using tools and techniques provided by nanotechnology.

Part of the researches being conducted is to come up with a solar panel that would accurately capture solar energy that can be utilized at home, in the office, and even in large-scale industrial areas. Although there are already solar panels available in the market today, these solar panels that are usually made of silicone panels only capture 67.4% light incident or solar energy emitted by the sun. Whereas, with nanotechnology, industrial and electrical manufacturers can now produce a coating for solar panels using nanorods that can capture 96.7 % light incident.

Get Ahead with Nanotechnology Careers

As the world recognizes the importance of nanotechnology, a lot of job opportunities and career advancements are opened to those who do extremely well in science and technology. The demand for skilled workers and scientists has rapidly increased out of increased demand for nanotechnology development.

In What Fields Are Nanotechnology Experts Needed?

Nanotechnology can practically be applied to almost all areas of the society, from the simplest objects to the most complicated structures and functional systems. If you want to get a stable nanotechnology career, you must excel in science and technology to get the following nanotechnology careers:

Nanobioscientists. With nanotechnology, medical experts are considering the possibility of treating serious disease such as diabetes, Parkinson’s disease, and cancer, among others by using nanobots that directly attack the damaged cells and heal them at precise manner without damaging the healthy cells unlike other treatments such as chemotherapy.

An Overview on Nanotechnology Materials

Things used for daily necessities used to be so simple, uncomplicated, and easy to use. But over time, out of man’s effort to improve his living conditions including his total wellness, more and more scientific and technological inventions were formulated and are now used at present time. Nanotechnology is one of the technologies applied for the improvement of several essential tools and equipment and even the simplest products available in the market we thought casual.

Nanotechnology refers to all the researches and studies being conducted in advance scientific laboratories that aim to produce nanotechnology materials to enhance the living conditions of man. Nanotechnology is also known as the science of small things or the development and engineering of functional systems at a molecular scale.

Where Can Nanotechnology Be Applied?

Basically, nanotechnology is used in most of the things we use today. Some of these things are still in the process of development while others are already enhanced and widely used in the fields of science and technology, medicine, electronics, industrial engineering, environment protection, and even in military. Nanotechnology is a complicated aspect of technology coupled with tremendous controversy and peppered with moral questions. But if handled and administered properly, nanotechnology can be very useful most people are even enjoying its research outcomes.

What Are Nanotechnology Materials?

Nanoscience and nanotechnology are basically concerned with new or enhanced functional materials that can be beneficial to man. These materials are called nanotechnology materials or nanomaterials. There are different approaches to construct nanomaterials. These approaches are the following:

Reduction of large materials to small structures or top-down technique. Another way of doing this is the bottom-up technique. This is done by allowing atoms to arrange themselves or self-assemble to come up with functional structures out of their natural properties.Another approach is by using tools to help the molecules move individually. This process has greater construction control but laborious and not applicable for industrial uses.

Learn the Basics of Medical Nanotechnology

Man has gone so far in terms of coming up with ways to preserve human life. Although there are still diseases that remain an enigma to medical science, still, treating illnesses from simple to severe conditions has become a lot easier. Among the most notable medical triumphs of modern-day science is the evolutionary concept and application of medical nanotechnology.

Medical nanotechnology or nanomedicine is the medical aspect or application of nanotechnology using different approaches such as nanoelectronic biosensors, nanomaterials, and a very futuristic but underdeveloped molecular nanotechnology that includes molecular manufacturing. Medical nanotechnology aims to provide cheaper yet quality health and medical equipment, facilities, and treatment strategies through continuous researches and studies. A lot of pharmaceutical and medical companies all over the world have already adhered to medical nanotechnology because of its numerous benefits and practical uses.

Vibrio fischeri and Escherichia coli adhesion tendencies towards photolithographically modified nanosmooth poly (tert-butyl methacrylate) polymer surfaces

Vibrio fischeri and Escherichia coli adhesion tendencies towards photoVibrio fischeri and Escherichia coli adhesion tendencies towards photolithographically modified nanosmooth poly (tert-butyl methacrylate) polymer surfaces Elena P Ivanova1, Natasa Mitik-Dineva1, Radu C Mocanasu1, Sarah Murphy1, James Wang2, Grant van Reissen3, Russell J Crawford11Faculty Life and Social Sciences; 2IRIS, Swinburne University of Technology, Hawthorn, Victoria, Australia; 3Centre for Materials and Surface Science, La Trobe University, Melbourne, Victoria, AustraliaAbstract: This study reports the adhesion behavior of two bacterial species, Vibrio fischeri and Escherichia coli, to the photoresistant poly(tert-butyl methacrylate) (P(tBMA)) polymer surface. The data has demonstrated that ultraviolet irradiation of P(tBMA) was able to provide control over bacterial adhesion tendencies. Following photolithography, several of the surface characteristics of P(tBMA) were found to be altered. Atomic force microscopy analysis indicated that photolithographically modified P(tBMA) (henceforth termed

Specific mutation screening of TP53 gene by low-density DNA microarray

TP53 gene by low-density DNA microarray Angélica Rangel-López1–3, Alfonso Méndez-Tenorio3, Kenneth L Beattie4, Rogelio Maldonado3, Patricia Mendoza1, Guelaguetza Vázquez1, Carlos Pérez-Plasencia5, Martha Sánchez2, Guillermo Navarro6, Mauricio Salcedo11Laboratorio de Oncología Genómica, Unidad de Investigación Médica en Enfermedades Oncológicas, Hospital de Oncología, CMN Siglo XXI-IMSS, Mexico City, Mexico; 2Unidad de Investigación Médica en Enfermedades Nefrológicas, Hospital de Especialidades, CMN Siglo XXI-IMSS, Mexico City; Mexico; 3Laboratorio de Biotecnología y Bioinformática Genómica, Escuela Nacional de Ciencias Biológicas, IPN Mexico City, Mexico; 4Amerigenics, Inc., Crossville, TN, USA; 5Unidad de Investigación Biomédica en Cáncer, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México UNAM, Instituto Nacional de Cancerología INCAN, Mexico City, Mexico; 6Laboratorio de Organometálicos UNAM, Mexico City, MexicoAbstract: TP53 is the most commonly mutated gene in human cancers. Approximately 90% of mutations in this gene are localized between domains encoding exons 5 to 8. The aim of this investigation was to examine the ability of the low density DNA microarray with the assistance of double tandem hybridization platform to characterize TP53 mutational hotspots in exons 5, 7, and 8 of the TP53. Nineteen capture probes specific to each potential mutation site were designed to hybridize to specific site. Virtual hybridization was used to predict the stability of hybridization of each capture probe with the target. Thirty-three DNA samples from different sources were analyzed for mutants in these exons. A total of 32 codon substitutions were found by DNA sequencing. 24 of them a showed a perfect correlation with the hybridization pattern system and DNA sequencing analysis of the regions scanned. Although in this work we directed our attention to some of the most representative mutations of the TP503 gene, the results suggest that this microarray system proved to be a rapid, reliable, and effective method for screening all the mutations in TP53 gene.Keywords: oligonucleotide microarray, TP53 gene, point mutations"/

High-efficient dye-sensitized solar cell based on novel TiO2 nanorod/nanoparticle bilayer electrode

High-efficient dye-sensitized solar cell based on novel TiO2 nanorod/n2 nanorod/nanoparticle bilayer electrode Hoda Hafez1,2, Zhang Lan2, Qinghua Li2, Jihuai Wu21Environmental Studies and Research Institute, Minoufiya University, Sadat City, Egypt, 2Institute of Materials Physical Chemistry, Huaqiao University, Quanzhou, ChinaAbstract: High light-to-energy conversion efficiency was achieved by applying novel TiO2 nanorod/nanoparticle (NR/NP) bilayer electrode in the N719 dye-sensitized solar cells. The short-circuit current density (JSC), the open-circuit voltage (VOC), the fill factor (FF), and the overall efficiency (η) were 14.45 mA/cm2, 0.756 V, 0.65, and 7.1%, respectively. The single-crystalline TiO2 NRs with length 200–500 nm and diameter 30–50 nm were prepared by simple hydrothermal methods. The dye-sensitized solar cells with pure TiO2 NR and pure TiO2 NP electrodes showed only a lower light-to-electricity conversion efficiency of 4.4% and 5.8%, respectively, compared with single-crystalline TiO2 NRs. This can be attributed to the new NR/NP bilayer design that can possess the advantages of both building blocks, ie, the high surface area of NP aggregates and rapid electron transport rate and the light scattering effect of single-crystalline NRs.Keywords: dye-sensitized solar cell, TiO2 nanorod, bilayer electrode"/