New research expands the application of Fullerene
September 18, 2014
Fullerene molecules are similar to diamonds in that they feature a purely carbon structure. Less resilient carbon-based materials, such as sugars or proteins, have other atoms interlinked throughout the crystalline structure, says Decoded Science. The carbon-only structure of fullerene also makes the material harder than diamond, and this property has made the molecule of particular interest to the materials processing industry. Unfortunately, the synthesis process of has been too difficult for industrial-scale manufacturing and this lack of production has held back fullerene applications. New research courtesy of Moscow Institute of Physics and Technology State University may have eliminated this barrier for good.
Harder than diamond
Diamonds are still one of the hardest materials on earth, boasting a hardness of almost 150 GPa. However, the diamond has long been surpassed as the hardest object in the world, says the MIPT. In fact, scientists have already developed the classification "ultrahard" to describe the various materials that feature hardness greater than a diamond. Fullerene is one of these ultrahard materials and samples of the carbon-based molecule can reach hardness of up to 300 GPa.
Currently, the ability to produce ultrahard fullerene tools is limited has been held back means of synthesis. Instead, the molecule has turned out to be very useful for a series of medical applications, being used as in very effective contrast agents for MRI and X-Ray procedures. Fullerene has even seen use in tumor treatment for cancer patients. The molecule is used in conjunction with radiation in increase the speed at which cancerous cells are broken down by the therapy.
Fullerene at industrial scale
The Moscow Institute of Physics and Technology was faced with the very question that had vexed fullerene researchers before: How can one overcome the high pressure requirements necessary to begin synthesis of fullerene? Previous research had shown that the process required at least 13 GPa (130,000 atm) of pressure, and this had proven to be an insurmountable challenge for the industrial sector.
Researchers at MIPT decided to add carbon disulfide to the beginning of the synthesis process, in hopes that the new catalyst would ease conditions necessary to produce fullerene. The experiment proved to be a success, and MIPT researches cited examples of fullerene being produced at pressures as low as 8 GPa. Furthermore, the addition of carbon disulfide to the synthesis process allowed the reaction to occur at room temperature.
These two changes could prove to greatly impact the scale and rate at which fullerene is produced. Conveniently, carbon disulfide itself has already been synthesized at a large scale and has dozens of applications across several industries. Access to sufficient carbon disulfide should be no issues for companies interested in applying the chemical toward the new fullerene synthesis process. Mikhail Popov, a leading nanomaterials scientist, noted that the discovery of this synthesis technique will create an entirely "new research area in materials science."
Strongly correlated oxides offer a plethora of possibilities for new electronics
September 18, 2014
Scientists continue to learn new applications for known materials as the community become more adept at manipulating matter at micro- and nanoscale. This research has produced successes like metamaterials, objects with unique properties that are assembled with molecules that have been coerced into ideal arrangements. Likewise, strongly correlated materials boast useful electronic and magnetic properties because the object's molecules perform special quantum-mechanical interactions. Scientists have recently designed new technology for manipulating strongly correlated oxides, and this breakthrough has huge implications for several material industries.
New doping techniques
Harvard University has recently discovered a technique to successfully dope strongly correlated oxides (specifically samarium nickelate), effectively controlling the rate of electrons flowing freely through the material. The discovery occurred as researchers searched for a way to utilize strongly correlated oxides as a semiconductor. Unfortunately, the unique properties of strongly correlated materials made it impossible to dope the oxide using traditional techniques.
Normally researchers are able to dope materials by introducing additional atoms to the object's crystalline structure. This process causes electrons originally present in the material to move into adjacent orbitals, and ultimately lowers the electrical resistance of the object. However, the same phenomenon does not occur when extra atoms are added to strongly correlated materials.
Samarium nickelate, like other strongly correlated materials, are made up of electrons with very unique behavior. These electrons automatically repel one another in a way that prevents the electrons from moving into adjacent orbitals. If scientists were able to adjust the position of one electron, then every other electron in the system would shift proportionally. This behavior is what makes materials like samarium nickelate so "strongly correlated."
Researchers at Harvard were forced to rethink the conceptual framework of doping. If the addition of atoms was not enough to manipulate the arrangement of correlated oxide, then scientists would have to impact the make-up of the molecule. The Harvard team found that certain dopants are able to change band gap of a material. Widening and narrowing band gaps allows scientist to manipulate energy levels in correlated oxides and discover new properties of the material.
The main benefit of a strongly correlated material is that if scientists manage to manipulate its properties, those changes will affect the entire object. Zheng Gai, researcher at the Department of Energy's Oak Ridge National Laboratory, compared correlated oxides to a material that "has many knobs, and if you turn one, all the properties change." These property changes can be significant, and may be enough to cause a metal object to behave like an insulator and visa versa.
For example, a team from the Harvard School for Engineering and Applied Sciences recently developed a process to control the metal-insulator behavior of vanadium oxide. Manipulating the properties of this strongly correlated oxide produced a device that can absorb over 99 percent of infrared light. There has also been a wide push for adopting strongly correlated oxides into the production of electronics. The Center for Integrated Quantum Materials seeks to use highly correlated oxides to improve signaling and computation processes. Samarium nickelate, for instance, may replace silicon as the standard material for production of computer equipment.
New metamaterials offer exciting and futuristic applications
September 17, 2014
Material scientists have long been forced to work around the natural properties of physical matter. New techniques to develop and manipulate metamaterials have given scientists a way to work around these limitations. Metamaterials are artificially produced in laboratories by arranging materials in certain sequences at microscopic scale. This technique allows scientists to change the physical makeup of natural materials to improve specific properties like durability, flexibility and thermal capacity. Recent studies have shown the near limitless possibilities of metamaterials for creating revolutionary new products.
Materials scientist Julia Greer and her team at the California Institute of Technology debuted a metamaterial ceramic in a September issue of Science. The team produced an aluminum oxide (alumina) ceramic arranged in a hollow-tube structure with walls measuring 5 to 60 nanometer thick and each tube measuring between 450 and 1,380 nanometers in diameter.
After testing the resilience of the alumina metamaterial, Greer and her team discovered that the sample became more flexible as the ratio of wall thickness to tube diameter was lowered. Greer notes that some samples of the alumina ceramic were deformed by up to 85 percent and yet were able to naturally recover their original shapes. This discovery is an astounding breakthrough for the development of flexible ceramics and further proof of the power of metamaterial technology for developing materials with properties that have never been seen in nature.
Ceramic materials have traditionally been brittle, and these properties were based on the natural arrangement of ceramic materials at a microscopic level. This arrangement features small flaws at the nanoscale that make traditional ceramics weak against blunt impacts. The scientists at Caltech were able to remove these flaws by arranging the ceramic materials in stable nanostructures and then linking those nanostructures together to create a stronger, more flexible metamaterial.
Greer and the Caltech researchers constructed their metamaterial by first making a 3D scaffold with the help of laser beams. Second, the scaffold was coated with a tiny layer of the alumina. Finally, the scaffolding was removed by the scientists, leaving a hollow nanomaterial structure formed into a resilient lattice. Caltech's study claims that the technique can be used with any chemicals to create a highly specialized metamaterial, and Greer's team is already working on methods for scaling up the the production method.
Changes to structural properties just scratch the surface of what scientists can do with the help of metamaterials. For example, researchers at the University of Pennsylvania recently reported that they have had success in manipulating a material's optical properties as well. Scientists believe that this discovery may be key to developing fantastical technologies like cloaking shields or stealth suits.
Boris Kuhlmey, an optics professor at the University of Sydney, explained to Phys.org that metamaterials can be designed to interact with light in the same way that atoms interact with photons. However, the ability to tweak this interaction by choice allows researchers to design materials with optical properties "almost arbitrarily."
The team at the University of Pennsylvania have developed a technique to "program" optical properties into certain materials by digitizing the production process. Scientists used a computer program to model 2D arrangements of metamaterials that featured ideal optical properties. Metamaterials were arranged in structures according to a binary model where two materials stood in for each "1" and "0" bit. This approach greatly streamlined the process between modeling and production as scientists could use the 2D model as blueprint for sequencing silver and silica "bits" into a unique metamaterial.
Metamaterials produced in this fashion have the ability to bend and manipulate light in completely new ways. Professor of bionanotechnology Tiffany Walsh told Phys.org that one of these new applications is directly manipulating the permittivity of a material. Science-fiction tools like invisibility cloaks may very well be a possibility as this technology is developed and enhanced. Beyond fantasy clothing, digitized metamaterials will help material scientists to develop new printing techniques that are useable at the nanoscale.
Scientists have long sought a solution to superconductivity. Current materials capable of superconducting materials are only able to reach this state when cryogenically cooled (below -150 Celsius). Next-generation tech like particle accelerators make use of superconducting materials, but the cost of keeping materials at critical temperatures makes these applications unfit for widespread use. Breakthroughs in metamaterial hope to change that, however.
Superconductors are so appealing because these materials feature zero electrical resistance and expel magnetic fields. As a result, these materials could be used to sustain and store a flow of electricity for over 100,000 years. Success in producing a superconductor that can be used in widespread applications would fundamentally advance several manufacturing industries at once. Researchers at the University of Maryland and Naval Research Laboratory are hopeful that metamaterials can be used to develop a room-temperature superconductor, according to Extreme Tech. Recent research was able to raise the critical temperature of tin by a small 0.15 Kelvin, but this success is enough to make scientists very optimistic.
Superconductivity is still, in many ways, a mysterious phenomenon. In fact, the research performed by the University of Maryland was notable because it involved a more active approach to studying superconductors, in contrast to the trial-and-error strategy that dominates most superconductor trials. Every metamaterials application that can be used to manipulate superconductivity will simultaneously help scientists gain a better understanding on the very properties that control and limit superconductivity.
The benefits of room-temperature superconductivity are relevant to the entire world. Mastery of the technology would greatly reduce the infrastructure costs of power grids and make it easy to install low-cost magnetic trains for public transportation.
Along with optics-manipulating cloth and foldable ceramics, room-temperature superconductors are just a sample of what this country can accomplish with metamaterials. Humans are sure to resolve an increasing number of manufacturing challenges as material scientists reach beyond the limits of the natural world.
Scientists develop bacteria to eliminate several types of waste
September 12, 2014
Bacteria is often thought of as microscopic carriers of sickness and disease, but the tiny organisms have been utilized by humans as tools for centuries. Bacteria is often added to cheeses during the curdling process, for example, to transform milk sugars into lactic acid. Some bacteria are quite adept at consuming toxic materials, and many scientists are developing methods to leverage the abilities of bacteria for widespread waste removal.
Nuclear waste removal
Nuclear waste is a problems that faces nations worldwide, but scientists at The University of Manchester have made a discovery that may completely change the nature of nuclear waste removal. The research team from Manchester recently came across a highly-specialized species of waste-eating bacteria living in the soil beneath radioactive waste dumps.
One byproduct of nuclear production, isosaccharinic acid, is likely to become active after nuclear waste materials are buried underground in cement. A chain reaction is expected to arise as ground water soaks through the cement and exposes nuclear waste to water with highly alkaline properties. Such a scenario would lead to the activation of certain materials present in the nuclear waste, such as isosaccharinic acid. These chemicals are made more soluble after exposure to the alkaline solution and are more likely to be carried away into nearby groundwater reservoirs.
Thankfully, a uniquely hardy bacteria discovered by the University of Manchester specializes in the same alkaline-high environments that threaten the environment surrounding nuclear waste dump sites. The same bacteria were actually found to consume isosaccharinic acid in conditions that mimicked the chemical environment present within nuclear waste storage containers.
This discovery is not only significant because of an opportunity to eliminate nuclear waste materials, but also because the breakthrough represents a new approach to utilizing bacteria as a resource. Professor Jonathan Lloyd, a member of the Manchester research team, noted that the waste-eating bacteria "must have evolved to thrive at the alkaline lime-kiln site in only a few decades, it is highly likely that similar bacteria will behave in the same way." The scientific community may make huge gains in reducing the volume of nuclear waste by investing in specialized bacteria able to destroy it completely.
Oil spill solutions
Nuclear byproducts are just one waste issue that researchers aim to resolve through manipulating bacteria. For example, European scientists working for the EU Project "Kill-Spill" are developing several methods to increase the success of oil-eating bacteria residing below the surface, says the European Research Media Center. For example, researchers experimented with additives that increase the division rate for these useful bacterial organisms. The team has also introduced a natural dispersant into sea water that causes oil to separate into a cloud of particulate. These tiny droplets are more likely to be consumed by bacteria and widespread implementation of both techniques could make huge strides in cleaning up the sea.
Researchers at the University of Bologna in nearby Italy are working on a similar project, seeking a bacterial solution to plastic waste floating in the ocean. The team has identified several bacteria that could aid in the degradation of plastic materials coasting across the waves. Once classification efforts are complete, the University of Bologna researches will move on to developing implementation strategies like their peers at the EU Project.
Bacterial power plants
EcoSeed reports that just a year ago Yale University scientists developed a waste-eating bacteria that performs double-duty as electricity generators. The bacteria, known as exoelectrogenic microbes, evolved to survive without oxygen by converting oxide materials into stored energy. The microbes themselves are able to draw plenty of oxide chemicals from sewage waste, and Yale researchers aimed to use the highly productive bacteria to ease the burden on the country's waste systems.
The team also is developed strategies to use the exoelectrogenic microbes as a power source. They constructed a battery using two electrodes, one soaked in waste water containing colonies of the waste-eating microbes. These colonies produced electrons that were collected by the electrode and later collected as the silver battery components are re-oxidized. The Yale University team was only able to collect about a third of the energy produced by waste-eating bacteria, but EcoSeed notes that this efficiency matches that of commercial solar cells.
This technique could eventually pay for its own implementation as the electricity collected by sewage-eating bacteria could be used to offset electricity used by the sewage plant. In addition, the reduction of total waste will help to further minimize resource demands for the entire plant. Like nuclear- and oil-eating bacteria, sewage-eating bacteria represents a natural solution to inorganic forms of pollution. These strategies are notable in that they are able to completely eliminate hazardous waste without creating more.
New developments in x-ray microscopy lead to higher resolutions
September 10, 2014
Although x-rays have been used by the medical and scientific communities for well over 100 years, researchers are still sophisticating the technology. Recently, separate teams of scientists from the Department of Energy's Lawrence Berkeley National Laboratory and Helmholtz-Zentrum Berlin für Materialien und Energie have devised methods for producing significantly higher resolution images using x-ray microscopy.
Fresnel zone plate microscopy
Back in June, a group of German physicists from HZB devised a method of generating improved lenses for x-ray microscopy. These new lenses are able to provide improved resolution and higher throughput. This feat required the fabrication of 3-D x-ray optics, which can be used for volume diffractions that are based off of on-chip stacked Fresnel zone plates. The nanostructures use three-dimensional architecture to focus the x-rays more than conventional methods of microscopy, allowing for resolutions below 10 nanometers.
Before this innovation by the HZB, scientists had been stymied in their efforts to produce higher resolution microscopes because of the limiting effects of light wavelengths. According to the press release, visible light can reveal structures that are as small as a quarter of a micron in size, but they are too broad to detect anything smaller than a micron. X-rays, on the other hand, have a much smaller wavelength than light, so they can perceive objects that are only a few nanometers. Another effect of the shorter wavelengths of x-rays is that they can penetrate deep into the objects onto which they are focused. This allows for examination of tiny internal structures of specimens without disruption.
Although x-rays provide a superior medium of observation, they have thus far proved difficult to focus, unlike light which is fairly easy to manipulate using refractive glass lenses. In order to use x-rays for the task of imaging, scientists need to use Fresnel zone plates - specialized apparatus made from concentric rings of metal like nickel or gold. The metal diffracts x-rays, and the circular shape allows for the x-rays from different zones to be superposed at a focal point, resulting in a concentrated blast of x-ray radiation. Using this technique, scientists had been able to achieve resolutions of approximately 10 nanometers, but the HZB team was able to produce a new device that could focus on structures even smaller.
To solve this problem, HZB researchers had to resolve two issues, one practical, the other theoretical. First, they had to be able to fabricate Fresnel zone plates that were less than 10 nanometers wide and several hundred nanometers tall. This first issue was resolved handily thanks to advances in nanoengineering, but the second issue proved more challenging.
Theoretical models suggested that the focusing effect of the Fresnel zone became diminished as the size of the rings decreased. This would mean that the x-rays would not be concentrated enough to sufficiently capture meaningful images from their target object. Fortunately, the team was able to resolve this issue thanks to the effect of volume diffraction, but to do so, they had to create a zone that simultaneously had increasing tilt angle and declining zone height versus radius - put simply, the model needed to be three-dimensional.
Stephan Werner, a researcher who worked on the project, explained that their novel model meant that "almost 100 percent of the incident light could be utilized for the image."
More recently, a group from the DOE's Lawrence Berkeley National Laboratory were able to build on the work from HZB with soft x-rays, which can be used to image structures that are a mere five nanometers in size - half the resolution of previous iterations of the technology.
The record setting use of x-ray microscopy was accomplished using low energy x-rays, sometimes called soft x-rays in conjunction with a process called ptychography. A coherent diffractive imaging technique, ptychography uses high-performance scanning transmission x-ray microscopy. Ptychography uses multiple coherent diffraction measurements to acquire both two-dimensional and three-dimensional maps of micron-sized structures with higher resolution and sensitivity than could be accomplished with traditional methods of x-ray microscopy.
The soft x-rays used in this process are significantly more sensitive, so they ptychography can image processes that have never before been seen, such as chemical phase transformations and the physical effects caused by those transformations. As a demonstration of its incredible effectiveness, the DOE scientists were able to map the chemical composition of lithium iron phosphate nanocrystals after partial dilithiation.
According to David Shapiro, a physicist with the DOE, "We have developed diffractive imaging methods capable of achieving a spatial resolution that cannot be matched by conventional imaging schemes. We are now entering a stage in which our x-ray microscopes are no longer limited by our optics and we can image at nearly the wavelength of our x-ray light."
This breakthrough was the result of solving limitations previously placed on ptychography. Previously, ptychographic microscopes were inferior to those, like that developed by HZB, because they used hard x-rays, which were captured using a basic pin-hole method of image capturing. This practice required an extremely prolonged exposure time, resulting in lower-quality images as the specimen moved over the course of exposure.
The DOE scientists applied the principles of established ptychography, but they opted to use soft x-rays in conjunction with a specialized algorithm that is able to compensate for interfering background signals. According to their press release, the ptychography measurements were recorded with STXM devices at ALS beamline 11.0.2, which applied an undulator x-ray source, and ALS beamline 184.108.40.206, which employed a bending magnet source. Using a soft x-ray beam, the researchers could focus on a specimen, which was scanned in 40 nanometer increments. The diffraction data could then be recorded with an x-ray charge-coupled device before it was finally reconstructed into an image at record-setting resolutions.
The end result is an incredibly sensitive and high resolution x-ray microscope that is so powerful that it can be used to observe chemical phase shifts. This device will surely open many new avenues to scientists and researchers across a wide range of specializations as it allows for the empirical observation of processes that were previously purely theoretical. Ultimately, this should lead to new breakthroughs in engineering research and development as well as many other fields.
Artificial cells provide new tools for microscopic manipulation
September, 9 2014
Scientists have been consistently perplexed by the challenge of building a dynamic, functioning synthetic cell. A cell in nature have the ability to react to its environment and influence its own movement, and these capabilities have been extremely difficult to duplicate in the lab. However, recent advances at the Technische Universität München and John Hopkins University may open the door for the next generation of artificial cell development.
Perfecting the craft
Professor Andraes Bausch, along with his team at the Technische Universität München, have managed to produce an artificial cell that has the ability to manipulate itself, according to Popular Mechanics. Bausch focused the project around investigating the cytoskeleton, a network of protein fibers that support the inner workings of a cell's cytoplasm.
Researches at TUM worked to simulate the functionality of a cell by designing a vesicle to capture proteins primarily used by cell bodies to power movement: microtubules, kinesin and ATP molecules. Kinesin motors are used to transport nutrients through microtubules and ATP molecules provide the fuel for this microscopic machine. Basuch and his team were then able to directly observe the behaviors of the capture protein within the bounds of their synthetic cell environment. The research collected by Basuch and his team is primarily useful because it provides scientists with a better understanding of how to construct a system that is able to properly function outside of certain equilibrium. The physical interactions between the three proteins may also be used to model movement for microscopic machines.
One key behavior noted by the Bausch team is the tendency of microtubules to contain faults. Inevitably, some microtubules are unable to lay directly against nearby the cell membrane and instead settle into alternative geometric patterns. The movement of kinesin motors through microtubules causes these extra microtubules to move and shift across the membrane of the cell. The sizes of the faults do not impact the general shape of the cell. However, the orientation of faults does have a noticeable impact when water is drained from the cell through osmosis. This phenomenon drastically changes the shape of the molecule, as spiked extensions begin to appear in line with the cell's faults. Bausch and his team have began to outline models for predicting these behaviors to better understand the natural behavior of biological cells.
The inductive approach
Dr. Takanari Inoue and his team at John Hopkins University have taken a different approach to studying and influencing cell behaviors, according to News Medical. The main focus of the research team's study was phagocytes, cell bodies designed to search out and consume molecular waste components. In particular, Dr. Inoue was interested in ways to artificially induce phagocytic activity in regular cells.
Phagocytosis is an important process that removes dangerous waste materials, like DNA-damaging biomolecular enzymes, before they can do damage to the body. However, the process between phagocytosis is exceedingly complex. These specialized white-blood cells must be exposed to dozens of signalling components necessary components before they begin to consuming aging cells. Most cells in the body actually contain the specific components necessary to participate in the phagocytosis process, but lack the necessary catalysts to activate waste-removing behaviors.
Inoue's staff used a novel approach to activating phagocytic behavior in regular cells. Two techniques, Dimerization-Induced Surface Display and membrane deformation, were used to induce normal cells into state of phagocytosis. Inoue and his team developed Dimerization-Induced Surface Display as a technique to recognize and present undesirable microscopic items. The DISplay method was then utilized in conjunction with Rac, a genetically mutated molecule that shapes and deforms cells into new shapes. The techniques also activates phagocytic behavior in cells when implemented simultaneously.
The success of these two projects reflects the growing interest in the medical community for synthetic cells and artificially induced cell processes. Artificial phagocytosis, for example, could be used to help cancer patients avoid dangerous exposure to radiation bombardments. Healthy cells in proximity to cancerous cells, for example, could be induced to consume and remove unhealthy cells from the body. The same technique could be used to remove the plaques that cause Alzheimer's disease as well, says Science Daily.
The science of developing functional, programmable cells is still a ways off. However, the research completed by Bausch and his team hope that their models will provide the foundation for the next generation of cell models. The TUM project's artificial cell is not quite as complex as a real cell, but MIT engineer Bradley Olsen told Popular Mechanics that the man-made viscecle deserves credit for successfully mimicking the behavior of organic cells. Lessons learned by both researchers will go a long way toward helping the scientific community produce even more refined artificial cells. The next generation of synthetic cells will be able to perform multiple chemical functions and better mimic the behavior of biological models.
New discoveries point toward potential for nanocubes
September 8, 2014
Nanoparticles are already utilized widely in medical and mechanical industries, but researchers are still developing methods to arrange nanoparticles into increasingly complex structures. A breakthrough in this field would greatly expand the ability of companies to manufacture high-tech materials that take advantage of unique nanoparticle properties. While the scientific community still lacks a conclusive solution for nanoparticle arraignment, new research from the University of Chicago and U.S. Department of Energy has provided new clues.
Theoretical chemist Petr Kral recently simulated a promising nanoparticle phenomenon for observers at the University of Illinois at Chicago. The demonstration is a simulation of a discovery made by Rafal Klajn at the Weizmann Institute of Science in Israel, related to the behavior of an iron oxide called magnetite. The material naturally self-assembles into nanocrystals within the bodies of certain bacteria, allowing the organism to use the magnetic properties of the nanocrystals as a biological compass. Klajn and his team were interested in determining the conditions that prompt magnetite nanoparticles to form complex structures in nature.
Klajn and his team tested the behavior of magnetite nanoparticles by dissolving the nanocrystals, exposing the solution to the influence of an additional magnetic field and allowing the solution to evaporate. Researchers found that the magnetite nanoparticles had naturally assembled into a helical chain, says Science Daily. Furthermore, these nanoparticle chains were found to be chiral, expressing left- or right-handedness. This observation was the most surprising of all, as chirality was not a property inherent to magnetite nanoparticles.
Kral and his team at the University of Illinois expanded on Klajn's findings by carefully examining the self-assembly process discovered in Israel. They were able to determine that two major factors influenced the helical, chiral self-assembly of magnetite nanoparticles. Not surprisingly, magnetism proved to be one of the primary force acting on magnetite nanoparticles, compelling the particles to collect in corner-to-corner arrangements. Magnetite particles are simultaneously pulled into a side-by-side arrangement by Van der Waals forces. The step-like alignment demonstrated by magnetite nanoparticles in helical formation is the natural compromise between the two forces.
Kral and his team also developed a new Monte Carlo computer algorithm to calculate how magnetite particles react to varying strengths of magnetic fields and other outside factors. The goal of these calculations is to model the relationship between the forces acting on magnetite particles and their subsequent arraignment. The research may also provide a model for how researchers can coax nanoparticles into certain configurations by way of magnetic fields.
Phys.org reports that the Ames Laboratory, backed by the U.S. Department of Energy, has likewise researched solutions for more refined control of nanoparticles and their arraignments. Nanoparticles are already coated in specialized polymers to expand their applications for the industrial and medical sectors. Researchers at the Ames Laboratory aimed to create a systematic model to determine which polymer coatings encourage nanoparticles to self-assemble into useful lattice configurations.
Researchers were already aware that spherical nanoparticles easily assemble regardless of their alignment. Conversely, nanocubes (like the magnetite nanoparticles classified by Kral) feature orientational tendencies and can be packed into ultra-efficient configurations. The Ames Laboratory team hoped to maximize the space-efficient behavioral tendencies of nanocubes by coating them in polymers and DNA strands, then categorizing the behaviors that occurred with the addition of the polymer. Ames Laboratory physicist Alex Travesset told Phys.org that the team had been successful in encoding information directly onto nanoparticles by way of DNA coating.
Two new infinite power supplies for microelectronics
September 5, 2014
Sensors, like the gyroscopes and accelerometers in smartphones, are being used with increasing frequency in a wide variety of purposes. With industrial applications, sensors can be used to gain access to a massive amount of information about the inner workings of machinery. However, they present a design challenge to engineers insofar as these tiny electronic devices need a power supply, albeit small, but they are most effective when they can be built into the least accessible, inner workings of industrial equipment. Fortunately, researchers at the University of Washington and The Agency for Science, Technology and Research have been finding solutions for providing power to tiny electronics.
Power from vibrations
Back in February, A*STAR made the claim that battery replacement may no longer be necessary in the near future. The agency's Institute of Microelectronics had been working on making devices that could be powered by low frequency vibrations, which represent the most common, yet largely untapped, resources in the world. The team of researchers were able to create an energy harvester, which can convert vibrations into electricity. This would mean that small electronics could instead be used indefinitely without ever needing to have their batteries replaced.
In order to make efficient use of low frequency vibrations, the A*STAR team took a novel approach to the problem. In the past, researchers have attempted to make larger energy harvesters, under the notion that a larger device would be able to capture more of vibrations. However, the only successful prototypes of such harvesters proved to be extremely limited in their potential applications due in part to their size but also to the fact that they could only operate on one fixed frequency of vibrations.
Tiny device, big results
The IME researchers were able to completely forgo this model of energy harvester by making theirs smaller thanks to the unique properties of aluminum nitride. According to early reports, their device has a record-high power density of 1.5 x 10-3 W/cm cubed, which is theoretically able to generate the same amount of electricity as three commercially available batteries over the course of a decade.
The press release from A*STAR indicates that the IME energy harvester is also able to make use of a broader spectrum of frequencies than other prototypes. The team announced that they can draw from a range of 10th to 100 hertz, making it much more practical in a wider range of applications.
Explaining their processes, Alex Gu, Technical Director of IME's Sensors and Actuators Microsystems Program, said, "Our design strategy exploits the coupling effect between the Vortex shedding and Helmholtz resonating in order to enhance the Helmholtz resonating and lower the threshold input pressure. By transferring the low frequency input vibrational energy into a pressurized fluid, the fluid synchronizes the random input vibrations into pre-defined resonance frequencies, thus enabling the full utilization of vibrations from the complete low frequency spectrum."
Power from temperature changes
Several months after A*STAR's press release describing their harnessing of low frequency vibrations, the University of Washington announced that affiliated researchers have accomplished a similar feat. Rather than draw power from vibrations, however, the UW team chose to use a centuries-old clock design to create an energy harvester that uses temperature fluctuations to power small devices like sensors.
Based on 17th century clockwork, the new system functions with a complex system of bellows, gases and bladders. In detail, a metallic bellows the size of a melon is filled with temperature-sensitive gas. As the gas heats and cools with external air temperatures, the gas expands and contracts, which powers the bellows. These tiny bellows "exhale" into cantilever motion harvesters, which can convert the kinetic energy from the bellows into small amounts of electrical energy. Fortunately, sensors do not require very much energy to function, and by placing the sensors directly onto the bellows, the electricity does not have to travel very far.
Although A*STAR's design has a significantly higher output, the UW press release indicates that there are applications for sensors that require the tiny electronic devices to be placed in areas that cannot be reached by vibrations, solar energy or even ambient radio frequency waves.
For example, this UW's devices could be installed with sensors deep within the architecture of a bridge to detect the formation of cracks or other structural deficiencies. This is due to the fact that even the tiny change of 0.25 degrees Celsius is enough to create enough power for the sensor to wirelessly send data to powered receivers up to 5 meters away. Essentially, any minute change in temperature will be enough to power the sensor, which means that it will be able to continue to operate without ever needing to have its batteries changed, no matter where it is placed.
Of course, the research team plans on pushing their product further to create a device that could see wider use. Moving forward, the UW engineers want to reduce the size of their invention so it is about the size of a D battery. They also want to create different versions of the device that can use one of four different chemicals that are most effective at different temperature ranges, so it can be used in a wide range of climates.
According to Chen Zhao, lead author on the paper, they have also made plans to recreate the prototype available online.
"We provide a simple design that includes some 3-D printed and off-the-shelf components. With our Web page and source code, others can download and build their own power harvesters."
Both of these innovations from A*STAR and UW represent a significant advance for engineering, and will be able to power devices like sensors and microcomputers that can be used to monitor the impenetrable inner workings of complex equipment and architecture. More importantly, since the batteries will never have to be changed, the devices will require next to zero maintenance, resulting in more data and less work over time.
New methods synthesize propane from E. coli bacteria
September 2, 2014
Biofuels have been made from methane, corn, oil palm and now E. coli. This new development out of Imperial College London means that scientists may soon be able to synthesize a renewable propane with the relatively harmless gut bacteria, which could lead to a sustainable source for the commonly used fossil fuel.
As an alternative to coal and oil propane, has been used with increasing regularity in recent years. With stricter regulations from the federal government, more people and companies are making the switch to propane for heating and even electricity production. In fact, propane has become such a popular commodity in recent years, according to the press release from Imperial College London, it now accounts for the bulk of liquid petroleum gas, which is used for everything from central heating to small motor vehicles and even industrial equipment like forklifts.
As a transitional fuel, propane is a suitable stopgap as researchers and engineers the world over work on refining alternative energy sources such as solar, geothermal and wind. Unfortunately, propane, as a by-product of natural gas, is most commonly extracted from the earth with a process called fracking, which many scientists believe to be extremely damaging to groundwater reserves and the surrounding ecosystems in general. Fortunately, this new research from Imperial College London may mitigate the need for fracking and other potentially damaging forms of natural gas extraction.
According to the source, the British research team worked in tandem with another group from the University of Turku in Finland to create the synthetic propane. Using E.coli bacteria to interrupt the biological processes that turns fatty acids into cell membranes, the scientists were able to reallocate cell functionality artificially. Using specialized enzymes, the researchers were able to redirect the fatty acids into different biological channels, which caused the bacteria to create engine-ready propane instead of cellular membranes.
From digital space to reality
This project comes four years after Desmond Lun, PhD, an associate professor of computer science at Rutgers University-Camden published the first work on using E. coli to produce biodiesel. Back in 2010, Lun first explained his reasoning for wanting to discover a method for using bacteria to produce biofuels.
"It's widely acknowledged that making fuel out of food sources is not very sustainable. it's too expensive and it competes with our food sources."
Although this claim was surely valid four years ago, it is even more so now in light of the extreme droughts that have been desiccating farmland from California to Texas over the past few years.
Rather than work with live bacteria, Lun devised advanced computer models for manipulating virtual E. coli in a safe, digital space. Using his computer engineering information background, this method allowed him to make artificial changes to the bacteria by removing or adding different enzymes to enhance fatty acid production.
Lun's work had not moved from digital space to a laboratory until the team from Imperial College London took up the torch and began putting his theoretical work to real world application.
Patrick Jones, PhD, from Imperial College London's Department of Life Sciences, claimed that "Although this research is at a very early stage, our proof of concept study provides a method for renewable production of a fuel that previously was only accessible from fossil reserves. Although we have only produced tiny amounts so far, the fuel we have produced is ready to be used in an engine straight away. This opens up possibilities for future sustainable production of renewable fuels that at first could complement, and thereafter replace fossil fuels like diesel, petrol, natural gas and jet fuel."
Propane proved to be the perfect test fuel for proving the concept that E. coli could be used to create synthetic fuels. According to the source, propane can easily escape bacterial cells as a gas, and does not require very much energy to transform the gas into a usable liquid, which is easy to transport and store.
According to the source, E. coli bacteria was well suited for the project because it did not need to be genetically modified. Rather, the team was able to interrupt the biological process that the bacteria uses to turn fatty acids into cell membranes. By stopping it at exactly the right moment, the scientists were able to extract butyric acid, which is the unpleasant smelling chemical that is one of the building blocks of propane.
The researchers were able to interrupt the process of turning fatty acids into membrane thanks to a novel enzyme called thioesterase, which targets fatty acids and frees them from their natural processes. Using a second bacterial enzyme, called CAR, the team was then able to convert butyric acid into butyraldehyde. Before now, the process for extracting propane was established up until this point, but with a newly discovered enzyme, called aldehyde-deformylating oxygenase, the researchers were able to finally extract the usable propane.
This marks a significant advancement for scientists studying E. coli's potential for creating biofuels. Previous attempts to use aldehyde-deformylating oxygenase as an enzyme have thus far been unsuccessful. However, the team from Imperial College London discovered that if they stimulated the enzyme with electrons, then it yielded significantly enhanced catalytic capabilities.
In its early stages, the synthetic propane can only be produced in extremely small amounts. In fact, according to the source, the researchers are synthesizing a mere 1/1,000 of what is needed to turn it into a commercial product. The next level of research will focus on refining the process so they can extract more usable propane, reducing the amount of energy going into the product while increasing total yield.
Unlike Lun, the researchers from Imperial College London and the University of Turku are not interested in simply creating biofuel, they want to use their synthesized propane as a vehicle for carrying solar power. At the moment, solar energy is challenging to store and transport, but if it could be transformed into a liquid fuel, then it could easily be dropped in as a proxy for other combustibles like propane, ethanol or petroleum.
A new superconductor may outperform graphene
August 26, 2014
Graphene, the superlight, conductive material of the future, has long been lauded as the next big thing in materials science, but new research from the Department of Energy and Berkeley National Laboratory may eclipse the nanomaterial.
The next generation of superconductive nanomaterial
The next contender is known as MX2, a two-dimensional semiconductor that is making waves in the materials science community. An international joint project led by researchers from the U.S. Department of Energy's Lawrence Berkeley National Laboratory has announced that early observations of the new material have recorded charge transfer times of less than 50 femtoseconds, which is comparable to the world's best organic photovoltaics.
Feng Wang, a condensed matter physicist with Berkeley Lab's Materials Sciences Division and the University of California Berkeley's Physics department spoke about the huge success of this promising new superconductor.
"We've demonstrated, for the first time, efficient charge transfer in MX2 heterostructures through combined photoluminescence mapping and transient absorption measurements. Having quantitatively determined charge transfer time to be less than 50 femtoseconds, our study suggests that MX2 heterostructures, with their remarkable electrical and optical properites and the rapid development of large-area synthesis, hold great promise for future photonic and optoelectronic applications."
The secret to this new material is in monolayers consisting of a single layer of transition metal atoms, like molybdenum or tungsten, which are then sandwiched between two layers of chalcogen atoms, like sulfur. The layers create a heterostructure that is bound by comparatively weak intermolecular attraction that materials scientists refer to as the van der Walls force.
MX2 is a 2D semiconductor that is made from the same hexagonal, honeycomb structure that gives graphene its unique properties. However, unlike graphene, MX2 has natural energy band-gaps. This allows them to be used in transistors and similar electronic devices because their electrical conductance can be turned on or off depending on how it is meant to be used.
According to Wang, "Combining different MX2 layers together allows one to control their physical properties. For example, the combination of MoS2 and WS2 forms of type-II semiconductor that enables fast charge separation. The separation of photoexcited electrons and holes is essential for driving an electrical current in a photodetector or solar cell."
By observing the ultrafast charge separation abilities of atomically thin samples of MoS2/WS2 heterostructures, the Wang and his coresearchers have opened the door to a new chapter in the development of photonics, optoelectronics and photovoltaics.