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Supercomputers reveal strange, stress-induced transformations in world's thinnest materials

Supercomputers reveal strange, stress-induced transformations in world's thinnest materials | Amazing Science | Scoop.it

Interested in an ultra-fast, unbreakable, and flexible smart phone that recharges in a matter of seconds? Monolayer materials may make it possible. These atom-thin sheets—including the famed super material graphene—feature exceptional and untapped mechanical and electronic properties. But to fully exploit these atomically tailored wonder materials, scientists must pry free the secrets of how and why they bend and break under stress.

Fortunately, researchers have now pinpointed the breaking mechanism of several monolayer materials hundreds of times stronger than steel with exotic properties that could revolutionize everything from armor to electronics. A Columbia University team used supercomputers at the U.S. Department of Energy's Brookhaven National Laboratory to simulate and probe quantum mechanical processes that would be extremely difficult to explore experimentally.


They discovered that straining the materials induced a novel phase transition—a restructuring in their near-perfect crystalline structures that leads to instability and failure. Surprisingly, the phenomenon persisted across several different materials with disparate electronic properties, suggesting that monolayers may have intrinsic instabilities to be either overcome or exploited. The results were published in the journal Physical Review B.


"Our calculations exposed these monolayer materials' fundamental shifts in structure and character when stressed," said study coauthor and Columbia University Ph.D. candidate Eric Isaacs. "To see the beautiful patterns exhibited by these materials at their breaking points for the first time was enormously exciting—and important for future applications."

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Metamaterial gives visible light a nearly infinite wavelength

Metamaterial gives visible light a nearly infinite wavelength | Amazing Science | Scoop.it

The new metamaterial is made by stacking silver and silicon nitride nanolayers. It may find applications in novel optical components or circuits and the design of more efficient leds. The work will appear on October 13th in Nature Photonics.


The phase velocity and group velocity of light dictate how light propagates in a material. The phase velocity determines how the peaks and valleys of the wave move in the material, whereas the group velocity describes the transport of energy. According to Einstein’s laws, the transport of energy of light can never be faster than the speed of light. Therefore the group velocity is limited. There are however no physical limitations to the phase velocity. When the phase velocity becomes zero, there is no movement of the peaks and valleys of the wave; when it is infinite the wavelength diverges to very large values. In nature however, no materials with such special properties exist.

Metamaterials
The research team now presents a metamaterial composed of a unit cell structure much smaller than the wavelength of light. By stacking nanoscale layers of silver and silicon nitride a new material is fabricated in which light ‘feels’ the optical properties of both layers. 

The way light travels through matter is dependent on the material permittivity: the resistance of a material against the electric fields of light waves. Because the permittivity of silver is negative and that of silicon nitride is positive, the combined material has a permittivity which is effectively equal to zero. Therefore, it seems that the light experiences zero resistance, and propagates with an infinite phase velocity. The wavelength of the light is nearly infinite.

The researchers fabricated this material using focused ion beam milling, a technique that allows control over the structure of a material on the nanoscale. With a specially built interferometer it was shown that light indeed propagates through the metamaterial with no significant change of phase, corresponding to an almost infinite wavelength. This new material may find applications in novel optical components or circuits and the design of more efficient leds.

Contact
Prof.dr. Albert Polman, +31 (0)20 754 74 00
www.erbium.nl | www.amolf.nl/research/photonic-materials

Reference
Ruben Maas, James Parsons, Nader Engheta and Albert Polman
Experimental realization of an epsilon-near-zero metamaterial at visible wavelengths
Nature Photonics 7, (2013) | DOI: 10.1038/nphoton.2013.256

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New Element 117 Confirmed

New Element 117 Confirmed | Amazing Science | Scoop.it

Nuclear physicists have invested huge effort in creating superheavy elements, which consist of enough neutrons to provide enhanced stability from nuclear decay. For the past 30 years, experiments have been marching towards this “island of stability” with a new elemental discovery every 2 to 3years. Part of the discovery process includes the confirmation by an independent experimental collaboration—it is only at this point that an element obtains its official status.


An international team using an intense 48Ca beam provided by GSI research facility in Darmstadt, Germany, and a target material of radioactive 249Bk supplied by Oak Ridge National Lab in Tennessee has produced two atoms of the superheavy element with atomic number Z=117, confirming the initial observation published in 9 April 2010. In the process, a new isotope 266Lr was discovered from the previously unknown alpha-decay branch of 270Db. With a half-life of 1 hour, 270Db is the longest-lived alpha emitter having an atomic number, Z, greater than 102.


The experiment is a tour de force in superheavy element research and required a detailed reconstruction of a seven-step alpha-decay chain followed by the spontaneous fission of the newly discovered 266Lr. The difficulty stems from the large variation in decay lifetimes along the alpha chain. The discovery was made feasible by the use of TASCA, a gas-filled recoil separator specifically designed for a high selectivity of superheavy or transactinide elements.


Elements beyond atomic number 104 are referred to as superheavy elements. The most long-lived ones are expected to be situated on a so-called 'island of stability', where nuclei with extremely long half-lives should be found. Although superheavy elements have not been found in nature, they can be produced by accelerating beams of nuclei and shooting them at the heaviest possible target nuclei. Fusion of two nuclei – a very rare event – occasionally produces a superheavy element. Those currently accessible generally only exist for a short time. Initial reports about the discovery of an element with atomic number 117 were released in 2010 from a Russia-U.S. collaboration working at the Joint Institute for Nuclear Research in Dubna, Russia.

 

The findings will be published in an upcoming issue of the journal Physical Review Letters.

 

Read about the creation of Element 117 here: http://www.businessinsider.my/experiments-confirm-new-element-117-2014-5/

 
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Towards and island of stability: Superheavy elements

Towards and island of stability: Superheavy elements | Amazing Science | Scoop.it

It's now more or less official: element 117 will have a seat at the periodic table. Earlier this month an international team of scientists that included researchers from Lawrence Berkeley National Lab's Nuclear Science Division found two atoms of superheavy element 117. The experiment, conducted at a particle accelerator at the GSI Helmholtz Center for Heavy Ion Research in Darmstadt, Germany, builds on the previous 117 experiment by a different team working in Dubna, Russia in 2010 that identified six atoms of the superheavy element.


Elements beyond atomic number 104 are referred to as superheavy elements. The most long-lived ones are expected to be situated on a so-called 'island of stability', where nuclei with extremely long half-lives should be found. Although superheavy elements have not been found in nature, they can be produced by accelerating beams of nuclei and shooting them at the heaviest possible target nuclei. Fusion of two nuclei – a very rare event – occasionally produces a superheavy element. Those currently accessible generally only exist for a short time. Initial reports about the discovery of an element with atomic number 117 were released in 2010 from a Russia-U.S. collaboration working at the Joint Institute for Nuclear Research in Dubna, Russia.

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MIT’s fast synthesis system could boost peptide-drug development

MIT’s fast synthesis system could boost peptide-drug development | Amazing Science | Scoop.it

Peptide drugs are expected to become a $25 billion market by 2018, but current archaic manufacturing methods are too slow and cumbersome.


Small protein fragments, also called peptides, are promising as drugs because they can be designed for very specific functions inside living cells, but manufacturing the peptides takes several weeks, making it difficult to obtain large quantities, and to rapidly test their effectiveness.


A team of MIT chemists and chemical engineers has designed a way to manufacture peptides in mere hours. The new system, described in a recent issue of the journal ChemBioChem, could have a major impact on peptide drug development, says Bradley Pentelute, an assistant professor of chemistry and leader of the research team.


“Peptides are ubiquitous. They’re used in therapeutics, they’re found in hydrogels, and they’re used to control drug delivery.  They’re also used as biological probes to image cancer and to study processes inside cells,” Pentelute says. “Because you can get these really fast now, you can start to do things you couldn’t do before.”


Insulin and the HIV drug Fuzeon are some of the earliest successful examples, and peptide drugs are expected to become a $25 billion market by 2018, the researchers say.


Therapeutic peptides usually consist of a chain of 30 to 40 amino acids, the building blocks of proteins. Many universities, including MIT, have facilities to manufacture these peptides, but the process usually takes two to six weeks, using machines developed about 20 years ago. These machines require about an hour to perform the chemical reactions needed to add one amino acid to a chain.


To speed up the process, the MIT team adapted the synthesis reactions so they could be done in a continuous flow system. Using this approach, each amino acid addition takes only a few minutes, and an entire peptide can be assembled in little more than an hour.


In future versions, “we think we’re going to be able to do each step in under 30 seconds,” says Pentelute, who is also an associate member of the Broad Institute. “What that means is you’re really going to be able to do anything you want in short periods of time.”


The new system has storage vessels for each of the 20 naturally occurring amino acids, connected to pumps that pull out the correct one. As the amino acids flow toward the chamber where the reaction takes place, they travel through a coil where they are preheated to 60 degrees Celsius, which helps speed up the synthesis reaction.


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Powdered alcohol to be sold in the US by fall 2014

Powdered alcohol to be sold in the US by fall 2014 | Amazing Science | Scoop.it
The federal government recently rubber-stamped the manufacture and sale of a Palcohol, which turns any liquid into your favorite adult beverage.


If you were looking forward to enjoying Palcohol, a powdered alcohol product, this fall, you may need to wait a bit longer. The Alcohol and Tobacco Tax and Trade Bureau granted Palcohol “label approval” on April 8, but rescinded its approval April 21 after this article was published. A representative with the bureau told the Associated Press that the original approvals were issued in error. Palcohol’s parent company Lipsmark will need to resubmit its labels for approval. [This update was published April 22, 2014]


Instantly turning water into an alcoholic beverage is no longer a feat of biblical proportions. Come fall, it will be legal for Americans to purchase powdered alcohol, which can turn water into rum, vodka or a variety of cocktails.


The product, called Palcohol, is the brainchild of alcohol enthusiast Mark Phillips. He invented the potent powder because he wanted an easy, portable way to enjoy an adult beverage after a day of hiking, biking or kayaking. The federal government recently gave its stamp of approval for the sale and manufacture of the product, and it could be on the shelves of your local liquor store in the fall.


The key to making alcohol powders are simple carbohydrates called cyclodextrins, which bind together to form donut-shaped structures. They can then absorb and encapsulate fluids, like alcohol, within their molecular “donut holes,” which allows the liquid to be handled as a water-soluble powder.


Cyclodextrins are also used to dissolve insoluble medications, odor-fighting sprays, and reduced-fat foods. In the case of Palcohol, each packet weighs about an ounce — enough for one shot — and can fit into a pocket. The creators plan to release six flavors of Palcohol when it debuts later this year.

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Diagnosis by Light: How to Shrink Chemical Labs Onto Optical Fibers

Diagnosis by Light: How to Shrink Chemical Labs Onto Optical Fibers | Amazing Science | Scoop.it

Lab-on-fiber sensors could monitor the environment and hunt for disease inside your body.


Imagine an entire laboratory that fits inside a case the size of a tablet computer. The lab would include an instrument for reading out results and an array of attachable microsize probes for detecting molecules in a fluid sample, such as blood or saliva. Each probe could be used to diagnose one of many different diseases and health conditions and could be replaced for just a few cents.


This scenario is by no means a pipe dream. The key to achieving it will be optical glass fibers—more or less the same as the ones that already span the globe, ferrying voluminous streams of data and voice traffic at unmatchable speeds. Their tiny diameter, dirt-cheap cost, and huge information-carrying capacity make these fibers ideal platforms for inexpensive, high-quality chemical sensors.


We call this technology a lab on fiber. Beyond being an affordable alternative to a traditional laboratory, it could take on tasks not possible now. For instance, it could be snaked inside industrial machines to ensure product quality and test for leaks. It could monitor waterways and waste systems, survey the oceans, or warn against chemical warfare. One day, maybe as soon as a decade from now, it could be injected into humans to look for disease orstudy the metabolism of drugs inside the body.


It will probably be at least five years before lab-on-fiber instruments are ready for commercial use. For example, a remaining major challenge is figuring out how to toughen the surface coating on the probes so that they can be stored for several months without becoming unstable and thereby losing their ability to bind with target molecules.


Nevertheless, lab-on-fiber technology is tantalizingly close to being able to compete in cost and performance with today’s diagnostic tools for many applications. One of the first might very well be a blood test: Imagine turning on your home lab kit, pricking your finger, and blotting the blood on an array of fiber probes. In just a few minutes, the machine would automatically e-mail the results to your doctor, who could get back to you within hours if there was a problem. Meanwhile, you could get on with the rest of your day.

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Searching space dust for minute quantities of life’s ingredients

Searching space dust for minute quantities of life’s ingredients | Amazing Science | Scoop.it

Goddard Astrobiology Analytical Laboratory scientists have applied advanced technology to inspect extremely small meteorite samples for the components of life. “We found amino acids in a 360 microgram sample of the Murchison meteorite,” said Callahan. “This sample size is 1,000 times smaller than the typical sample size used. “We got the same results looking at a very small fragment as we did a much larger fragment from the same meteorite.”


Callahan said these techniques will allow the scientists  to investigate other small-scale extraterrestrial materials such as micrometeorites, interplanetary dust particles, and cometary particles in future studies.

The team used a nanoflow liquid chromatography instrument to sort the molecules in the meteorite sample, then applied nanoelectrospray ionization to give the molecules an electric charge and deliver them to a high-resolution mass spectrometer instrument, which identified the molecules based on their mass. “We are pioneering the application of these techniques for the study of meteoritic organics,” said Callahan.


This technology and the laboratory techniques that the Goddard lab develops to apply it to analyze meteorites will be valuable for future sample-return missions since the amount of sample likely will be limited.


“Missions involving the collection of extraterrestrial material for sample return to Earth usually collect only a very small amount and the samples themselves can be extremely small as well,” said Callahan.

“The traditional techniques used to study these materials usually involve inorganic or elemental composition. Targeting biologically relevant molecules in these samples is not routine yet. We are not there either, but we are getting there.”


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Chemical imaging brings cancer tissue analysis into the digital age

Chemical imaging brings cancer tissue analysis into the digital age | Amazing Science | Scoop.it

Imperial College London researchers have developed a new method for analyzing biological samples based on their chemical makeup that could transform the way medical scientists examine diseased tissue.


When tests are carried out on a patient’s tissue today, such as looking for cancer, the test has to be interpreted by a histology specialist, which can take weeks to get a full result.


Scientists have proposed using mass spectrometry imaging (MSI), which uses technologies that reveal how hundreds or thousands of chemical components are distributed in a tissue sample. But currently proposed MSI workflows are subject to several limitations, including nonoptimized raw data preprocessing, imprecise image coregistration, and limited pattern recognition capabilities.


In PNAS, the Imperial College London researchers have now outlined a comprehensive new strategy for effectively processing MSI data and building a database of tissue types. In MSI, a beam moves across the surface of a sample, producing a pixelated image. Each pixel contains data on thousands of chemicals present in that part of the sample. By analyzing many samples and comparing them to the results of traditional histological analysis, a computer can learn to identify different types of tissue.


A single test taking a few hours can provide much more detailed information than standard histological tests, for example showing not just if a tissue is cancerous, what the type and sub-type of cancer, which can be important for choosing the best treatment. The technology can also be applied in research to offer new insights into cancer biology.


According to Kirill Veselkov, M.D., corresponding author of the study from the Department of Surgery and Cancer at Imperial College London, “MSI is an extremely promising technology, but the analysis required to provide information that doctors or scientists can interpret easily is very complex. This work overcomes some of the obstacles to translating MSI’s potential into the clinic. It’s the first step towards creating the next generation of fully automated histological analysis.”


The technology will also be useful in drug development. To study where a new drug is absorbed in the body, pharmaceutical scientists attach a radioactive label to the drug molecule, then look at where the radiation can be detected in a laboratory animal. If the label is detached when the drug is processed in the body, it is impossible to determine how and where the drug has been metabolized. MSI would allow researchers to look for the drug and any metabolic products in the body, without using radioactive labels.

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MS Imaging differentiation of tissues

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Chemists construct first plastic cell with working organelles

Chemists construct first plastic cell with working organelles | Amazing Science | Scoop.it
For the first time, chemists have successfully produced an artificial cell containing organelles capable of carrying out the various steps of a chemical reaction.


This was done at the Institute for Molecules and Materials (IMM) at Radboud University Nijmegen. The discovery was published in the first 2014 issue of the journal Angewandte Chemie, and was also highlighted by Nature Chemistry.


It is hard for chemists to match the chemistry in living cells in their laboratories. After all, in a cell all kinds of complex reactions are taking place simultaneously in an overfull, small container, in various compartments and incredibly efficiently. This is why chemists attempt to imitate the cell in various ways. In doing so, they also hope to learn more about the origin of life and the transition from chemistry to biology.


Jan van Hest and his PhD candidate Ruud Peters created their organelles by filling tiny spheres with chemicals and placing these inside a water droplet. They then cleverly covered the water droplet with a polymer layer -- the cell wall. Using fluorescence, they were able to show that the planned cascade of reactions did in fact take place. This means that they are the first chemists to create a polymer cell with working organelles. Just like in the cells in our bodies, the chemicals are able to enter the cell plasma following the reaction in the organelles, to be processed elsewhere in the cell.


Creating cell-like structures is currently very popular in the field of chemistry, with various methods being tried at the Institute for Molecules and Materials (IMM). Professor Wilhelm Huck, for example, is making cells from tiny droplets of solutions very similar to cytoplasm, and Van Hest's group is building cells using polymers.


Competing groups are working closer to biology; making cells from fatty acids, for example. We would like to do the same in the future. Another step would be to make cells that produce their own energy supply. We are also working on ways of controlling the movement of chemicals within the cell, towards organelles. By simulating these things, we are able to better understand living cells. One day we will even be able to make something that looks very much like the real thing...'

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Magnetic metamaterial superlens extends range of wireless power transfer

Magnetic metamaterial superlens extends range of wireless power transfer | Amazing Science | Scoop.it

Inventor Nikola Tesla imagined the technology to transmit energy through thin air almost a century ago, but experimental attempts at the feat have so far resulted in cumbersome devices that only work over very small distances. But now, Duke University researchers have demonstrated the feasibility of wireless power transfer using low-frequency magnetic fields over distances much larger than the size of the transmitter and receiver.

The advance comes from a team of researchers in Duke's Pratt School of Engineering, who used metamaterials to create a "superlens" that focuses magnetic fields. The superlens translates the magnetic field emanating from one power coil onto its twin nearly a foot away, inducing an electric current in the receiving coil.


The experiment was the first time such a scheme has successfully sent power through the air with an efficiency many times greater than what could be achieved with the same setup minus the superlens. "For the first time we have demonstrated that the efficiency of magneto-inductive wireless power transfer can be enhanced over distances many times larger than the size of the receiver and transmitter," said Yaroslav Urzhumov, assistant research professor of electrical and computer engineering at Duke University. "This is important because if this technology is to become a part of everyday life, it must conform to the dimensions of today's pocket-sized mobile electronics."


In the experiment, Yaroslav and the joint Duke-Toyota team created a square superlens, which looks like a few dozen giant Rubik's cubes stacked together. Both the exterior and interior walls of the hollow blocks are intricately etched with a spiraling copper wire reminiscent of a microchip. The geometry of the coils and their repetitive nature form a metamaterial that interacts with magnetic fields in such a way that the fields are transmitted and confined into a narrow cone in which the power intensity is much higher.

"If your electromagnet is one inch in diameter, you get almost no power just three inches away," said Urzhumov. "You only get about 0.1 percent of what's inside the coil." But with the superlens in place, he explained, the magnetic field is focused nearly a foot away with enough strength to induce noticeable electric current in an identically sized receiver coil.


Urzhumov noted that metamaterial-enhanced wireless power demonstrations have been made before at a research laboratory of Mitsubishi Electric, but with one important caveat: the distance the power was transmitted was roughly the same as the diameter of the power coils. In such a setup, the coils would have to be quite large to work over any appreciable distance.

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Scientists make new exotic chemicals with high-pressure salt

Scientists make new exotic chemicals with high-pressure salt | Amazing Science | Scoop.it
It's time to rewrite the chemistry textbooks: NaCl isn't the only option.


Everything around you is made of elements that scientists have studied in quite some detail over the last 200 years. But all that understanding breaks down when these elements are subjected to high pressure and temperature. Now, using an advanced theoretical understanding and extreme conditions, researchers have converted table salt into exotic chemicals.


Salt is made from one part sodium (Na) and one part chlorine (Cl). If somehow salt were transported to the center of the Earth, where the pressure is three million times that on the surface, its crystalline structure would change but the ratio of those two elements would remain the same.


Vitali Prakapenka at the University of Chicago and his colleagues wanted to find out what would happen if there were an excess of either sodium or chlorine at such high pressures. Would the ratio between the elements change? “It might,” said Prakapenka, “because chemistry completely changes in such conditions.” If it did, the result would not just be formation of a new compound, but a serious revision of what we think about chemistry.


Elemental behavior changes at such high pressures. For example, molecules of oxygen, which normally contain two atoms, break down at increased pressures, and the element forms an eight-atom box. Raise the pressure some more to about 300,000 atmospheres, and it starts to superconduct. Chemists are trying to develop chemicals that exhibit similar properties but are stable under normal conditions—learning about these exotic compounds can help them achieve that goal.


Sodium chloride (i.e., table salt) is a different beast. It is bound in a one-to-one ratio by very strong ionic bonds. However, calculations done by Prakapenka’s colleague and lead researcher Artem Oganov at the State University of New York in Stony Brook indicated that even sodium chloride could be twisted to produce exotic chemicals. Those calculations, just published in Science, gave them precise pressures at which, in the presence of excess sodium or chlorine, salt could be transformed.


The calculations indicated that NaCl3, Na3Cl, Na2Cl, Na3Cl2, and NaCl7 could all be stable at pressures ranging from 20GPa to 142GPa, where 1GPa is about 10,000 atmospheres of pressure. High pressure physicists have many models to predict behavior of elements under extreme conditions, but rarely do those models agree with experiment.


Remarkably their calculations stood the test of experiment in at least two cases: Na3Cl and NaCl3. To run such an experiment, you need a fancy device called the diamond anvil cell. Chemicals are added between two diamonds, which can be compressed to produce pressures up to 300GPa. This is what Prakapenka’s colleague used to make Na3Cl and NaCl3, structures that were verified by Prakapenka using X-ray analysis.


“Nobody thought this could happen, given how strong the bond is between sodium and chlorine,” said Prakapenka. “What we have shown is that theory can be translated into experiment, which doesn’t happen often in high pressure physics.”


Malcolm McMahon, professor of high pressure physics at the University of Edinburgh, said, “These are surprising results, and they are guided by remarkable theoretical predictions. Without tools like the ones they have built, we would not have been able to think that sodium chloride could be transformed this way.”

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Single-molecule microscopy simultaneously monitors protein structure and function

Single-molecule microscopy simultaneously monitors protein structure and function | Amazing Science | Scoop.it

Proteins accomplish something rather amazing: A protein can have many functions, with a given function being determined by the way they fold into a specific three-dimensional geometry, or conformations. Moreover, the structural transitions form one conformation to another is reversible. However, while these dynamics affect protein conformation and therefore function, and so are critical to a wide range of areas, methods for understanding how proteins behave near surfaces, which is complicated by protein and surface heterogeneities, has remained elusive. Recently, however, scientists at University of Colorado utilized a method known as Single-Molecule Förster Resonance Energy Transfer (SM-FRET) tracking to monitor dynamic changes in protein structure and interfacial behavior on surfaces by single-molecule Förster resonance energy transfer, allowing them to explicate changes in protein structure at the single-molecule level. (SM-FRET describes energy transfer between two chromophores – molecular components that determine its color.) In addition, the researchers state that their approach is suitable for studying virtually any protein, thereby providing a framework for developing surfaces and surface modifications with improved biocompatibility.

 

Prof. Joel L. Kaar discussed the paper he and his co-authors, Dr. Sean Yu McLoughlin, Prof. Mark Kastantin and Prof. Daniel K. Schwartz, recently published in Proceedings of the National Academy of Sciences. "The primary challenges in devising our approach to characterizing changes in protein structure were implementing a site-specific labeling method, which enabled single-molecule resolution, as well as a method to only image molecules at the solution-surface interface," Kaar tells Phys.org. The scientists overcame the former challenge by incorporating unnatural amino acids – that is, those not among the 20 so-called standard amino acids – with unique functional groups for labeling with fluorophores (chemical compounds that can re-emit light upon light excitation); the latter, by using total internal reflection fluorescence microscopy, which only excites molecules in the near-surface environment, thereby minimizing the background fluorescence of molecules free in solution. "Although site-specific labeling methods have been used to monitor changes in protein conformation mainly in bulk solution, such techniques have not previously been exploited to study freely diffusible protein molecules at interfaces," Kaar adds. As such, the researchers are the first to apply site-specific labeling methods to study protein-surface interactions.

 

"The major challenge associated with incorporating unnatural amino acids for labeling was related to the optimization of protein expression," Kaar continues. Specifically, he explains, the expression of the enzyme organophosphorus hydrolase (OPH) – which is notoriously difficult to make in large quantities due to inclusion body formation – with the unnatural amino acid p-azido-L-Phe (AzF) had to be optimized to efficiently incorporate p-azido-L-Phe. (Inclusion body formation refers to the intracellular aggregation of partially folded expressed proteins,) "This process required modification of expression conditions," he adds, "in which bacteria with modified genetic machinery were grown to enable production of soluble enzyme for single-molecule experiments."

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Buckyball boron: First experimental evidence of an all boron fullerene

Buckyball boron: First experimental evidence of an all boron fullerene | Amazing Science | Scoop.it

Distorted 40-boron atom fullerene detected mixed with quasiplanar isomer.


The first experimental evidence for a boron fullerene has been produced by researchers in the US and China.[1] Unlike the football shaped C60 structure of buckminsterfullerene, the boron structure has very different symmetry, with a box-like shape containing both hexagonal and heptagonal holes. The researchers now hope that their findings will enable other boron fullerenes to be produced.


Boron cannot form a direct B60 analogue of buckminsterfullerene because it has only three electrons in its outer shell, so after forming three bonds it has no free electrons remaining to form the delocalised π-network essential to the stability of C60. In 2007, however, Boris Yakobson and colleagues at Rice University, US, proposed that this electron deficiency could be overcome by inserting an extra boron atom into the centre of each hexagon, forming B80.[2] And in June, Chinese scientists calculated that a the boron fullerene B38 would be stable.[3]


The stability of these hollow-cage structures has subsequently been challenged, but now Lai-Sheng Wang at Brown University, US, and colleagues have used two different electronic structure algorithms to calculate the most stable possible structure of B40. Both programs indicate that, by a considerable margin, the most stable isomer is a distorted fullerene with a hexagonal hole on the top and bottom and four heptagonal holes around the waist. They have christened this structure borospherene.


REFERENCES
  1. H-J Zhai et alNat. Chem., 2014, DOI: 10.1038/nchem.1999
  2. N G Szwacki, A Sadrzadeh and B I Yakobson, Phys. Rev. Lett., 2007, 98, 166804 (DOI: 10.1103/physrevlett.98.166804)
  3. J Lv et alNanoscale, 2014, DOI: 10.1039/c4nr01846j
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A first glimpse at room temperature superconductivity

A first glimpse at room temperature superconductivity | Amazing Science | Scoop.it

Scientists of the Max Plank Institute for the Structure and Dynamics of Matter at the Hamburg Center for Free-Electron Laser Science (CFEL) have turned a normal insulator partially into a superconductor at room temperature, using a flash of infrared light. The superconducting state survived only for a couple of picoseconds (trillionths of a second), but the findings may aid the quest for higher temperature superconductors, as the team of scientists including Wanzheng Hu, Daniele Nicoletti, Cassi Hunt and Stefan Kaiser lead by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter at CFEL reports in the scientific journal Nature Materials.


Superconductors are materials that carry electric currents without any resistance. Even good normal conductors like electrical lines lose roughly six per cent of the power they transmit due to resistive losses, so developing a zero resistance material has immediate practical benefit. Various metals are natural superconductors, but only at very low temperatures around minus 270 degrees Celsius. In 1986 it was discovered that certain ceramic compounds become superconducting at somewhat higher temperatures. But even these so-called high-temperature superconductors have to be cooled to below minus 135 degrees Celsius, rendering practical applications difficult.

In their new work, the researchers focussed on a double-layered cuprate, a group of copper oxide based materials with various known high-temperature superconductors. The investigated yttrium barium copper oxide (YBCO) has the chemical formula YBa2Cu3O6.5 and becomes a superconductor below -223 degrees Celsius.

The exact workings of high-temperature superconductors are still a mystery. Generally, superconductivity occurs, because electrons in the crystal lattice team up in so-called Cooper pairs which allows them to travel without resistance through certain materials. Below a characteristic temperature, all the Cooper pairs move together like a herd and can quantum mechanically tunnel through thin insulating layers.

YBa2Cu3O6.5 has a double layered structure, with pairs of CuO2 planes. In the superconducting state, the Cooper pairs can tunnel effortless from one of these bilayers to another, the bilayers are coupled. In the normal state, the Cooper pairs seem to be still there, but confined to their own bilayer, and coupling occurs only within each bilayer.

As the researchers found, a flash of infrared light can clear the way for the Cooper pairs to tunnel from one CuO2 bilayer to another, this effect can be measured for a tiny fraction even at room temperature, and so giving the first hint that superconductivity at room temperature is possible. The infrared light lets certain oxygen atoms between the bilayers (the apical oxygen atoms) vibrate around their equilibrium position. "For cuprates, the distance of the apical oxygen to the CuO2 plane is believed to play an important role for how high the superconducting temperature can be," explains Hu. "Therefore, by modulating the apical oxygen position, we hope we can control the superconducting properties."

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Chemists discover structure of cancer drug candidate

Chemists discover structure of cancer drug candidate | Amazing Science | Scoop.it
Chemists have determined the correct structure of a highly promising anticancer compound approved by the U.S. Food and Drug Administration (FDA) for clinical trials in cancer patients. In the new study, scientists show that TIC10's structure differs subtly from a version published by another group last year, and that the previous structure associated with TIC10 in fact describes a molecule that lacks TIC10's anticancer activity.


TIC10 was first described in a paper in the journalScience Translational Medicine in early 2013. The authors identified the compound, within a library of thousands of molecules maintained by the National Cancer Institute (NCI), for its ability to boost cells' production of a powerful natural antitumor protein, TRAIL. TIC10 means TRAIL-Inducing Compound #10.


As a small molecule, TIC10 would be easier to deliver in a therapy than the TRAIL protein itself. The paper, which drew widespread media coverage, reported that TIC10 was orally active and dramatically shrank a variety of tumors in mice, including notoriously treatment-resistant glioblastomas.

Tumors can develop resistance to TRAIL, but Janda had been studying compounds that defeat this resistance. The news about TIC10 therefore got his attention. "I thought, 'They have this molecule for upregulating TRAIL, and we have these molecules that can overcome tumor cell TRAIL resistance -- the combination could be important,'" he said.


The original publication on TIC10 included a figure showing its predicted structure. "I saw the figure and asked one of my postdocs, Jonathan Lockner, to make some," Janda said.


Although the other team had seemingly confirmed the predicted structure with a basic technique called mass spectrometry, no one had yet published a thorough characterization of the TIC10 molecule. "There were no nuclear magnetic resonance data or X-ray crystallography data, and there was definitely no procedure for the synthesis," Lockner said. "My background was chemistry, though, so I was able to find a way to synthesize it starting from simple compounds."

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Scientists Use Liquid Metal (Gallium-Indium-Selenium Alloy) To Reconnect Severed Nerves

Scientists Use Liquid Metal (Gallium-Indium-Selenium Alloy) To Reconnect Severed Nerves | Amazing Science | Scoop.it
Chinese biomedical engineers have used liquid metal to transmit electrical signals across the gap in severed sciatic nerves. The work raises the prospect of a new treatment for nerve injuries, they say.


When peripheral nerves are severed, the loss of function leads to atrophy of the effected muscles, a dramatic change in quality of life and, in many cases, a shorter life expectancy.


Despite decades of research, nobody has come up with an effective way to reconnect nerves that have been severed. Various techniques exist to sew the ends back together or to graft nerves into the gap that is created between severed ends.


Ultimately, the success of these techniques depends on the ability of the nerve ends to grow back and knit together. But given that nerves grow at the rate of one mm per day, it can take a significant amount of time, sometimes years, to reconnect. And during this time, the muscles can degrade beyond repair, leading to long-term disability.


So neurosurgeons have long hoped for a way to keep muscles active while the nerves regrow. One possibility is to electrically connect the severed ends so that the signals from the brain can still get through. But how to do this effectively?


Today, Jing Liu at Tsinghua University in Beijing and a few pals say they’ve reconnected severed nerves using liquid metal for the first time. And they say that in conducting electrical signals between the severed ends of a nerve, the metal dramatically outperforms the standard saline electrolyte used to preserve the electrical properties of living tissue.


Biomedical engineers have been eyeing the liquid metal alloy gallium-indium-selenium for some time (67 percent Ga, 20.5 percent In and 12.5 percent Sn by volume). This material is liquid at body temperature and is thought to be entirely benign. Consequently, they have been studying various ways of using it inside the body, such as for imaging.

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Molecular Robots: Making molecules that make molecules

Molecular Robots: Making molecules that make molecules | Amazing Science | Scoop.it

Nature builds proteins in complex molecular factories where information from the genetic code is used to program the linking of molecular building blocks in the correct order.1 The most extraordinary of these factories is the ribosome,2 a massive molecular machine found in all living cells that assembles amino acids from transfer RNA (tRNA) building blocks into a peptide chain with an order defined by the sequence of the messenger RNA (mRNA) strand that the molecular machine moves along.


Now Professor David Leigh’s group at the University of Manchester (www.catenane.net) have built an artificial molecular machine that builds chemical structures in a similar way.3 Their molecular machine features a functionalized nanometer-sized ring that moves along a molecular track, picking up building blocks located on the path and connecting them together in a specific order to synthesize the desired new molecule.


The mechanism of operation of the molecular machine is shown in Figure 1 (and is also shown in a video). First the ring is threaded onto a molecular strand using copper ions to direct the assembly process. Then a “reactive arm” is attached and the machine starts to operate. The ring moves up and down the strand until its path is blocked by a bulky group. The reactive arm then detaches the obstruction from the track and transfers it to another site on the machine, regenerating the active site on the arm. The ring is then free to move further along the strand until its path is obstructed by the next building block. This, in turn, is removed and passed to the elongation site on the ring, thus building up a new molecular structure. Once all the building blocks are removed from the track, the ring de-threads and the synthesis is complete.


Today the chemical products of the modern world—plastics, paints, pharmaceuticals, catalysts etc—are made by mixing together successive cocktails of reactive chemicals, in processes that are often laborious, inefficient and require many expensive steps. By contrast, in nature molecules are made by other molecules with exquisite efficiency. Biology has not evolved to do this over 2.5 billion years for no good reason and when scientists learn how to use molecular machines to perform synthesis—positioning substrates and ‘reactive arms’ and controlling the dynamics of responsive centers—it will have the potential to revolutionize the whole approach to functional molecule and materials design.


References

[1] J. M. Berg, J. L. Tymoczko, L. Stryer, Biochemistry (W. H. Freeman, New York, 6th edition, 2006).

[2] A. Yonath, Angew. Chem. Int. Ed. 49, 4340 (2010).

[3] B. Lewandowski, G. De Bo, J. W. Ward, M. Papmeyer, S. Kuschel, M. J. Aldegunde, P. M. E. Gramlich, D. Heckmann, S. M. Goldup, D. M. D’Souza, A. E. Fernandes and D. A. Leigh, Science 339, 189-193 (2013).


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A new self-healing chemistry for plastics

A new self-healing chemistry for plastics | Amazing Science | Scoop.it

Scientists at Karlsruhe Institute of Technology (KIT) andEvonik Industries have developed a self-healing chemistry that allows for rapid healing of a plastic material using mild heating, restoring its initial molecular structure. It is based on a reversible chemical crosslinking reaction.


  • The reaction happens at temperatures from 50°C (122°F) to 120°C (248°F).
  • The material can be restored completely in less than 5 minutes, and is bound even more strongly than before.
  • Flowability is enhanced at higher temperatures, so the material can also be molded.
  • The self-healing properties can be transferred to a variety of plastics, including fiber-reinforced plastics components for automotive vehicles and aircraft.
  • Healing is also possible for material with scratches.


The research results were published in the journal Advanced Materials. Research partners were the Leibniz Institute of Polymer Research, Dresden, and the Australian National University, Canberra.


* The material uses a new low-temperature reversible system based on covalent chemistry, using “hetero Diels–Alder (HDA)” reactions via a new cyanodithioester compound with cyclopentadiene.

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Newly discovered nickel-gallium catalyst could lead to the low-cost, clean production of methanol

Newly discovered nickel-gallium catalyst could lead to the low-cost, clean production of methanol | Amazing Science | Scoop.it

Scientists from Stanford University, SLAC National Accelerator Laboratory and the Technical University of Denmark combined theory and experimentation to identify a new nickel-gallium catalyst that converts hydrogen and carbon dioxide into methanol with fewer side-products than the conventional catalyst. The results are published in the March 2 online edition of the journal Nature Chemistry.


"Methanol is processed in huge factories at very high pressures using hydrogen, carbon dioxide and carbon monoxide from natural gas," said study lead author Felix Studt, a staff scientist at SLAC. "We are looking for materials than can make methanol from clean sources, such as sunshine, under low-pressure conditions, while generating low amounts of carbon monoxide."


"The technique is known as computational materials design," explained Nørskov, the director of the SUNCAT Center for Interface Science and Catalysis at Stanford and SLAC. "You get ideas for new functional materials based entirely on computer calculations. There is no trial-and-error in the lab first. You use your insight and enormous computer power to identify new and interesting materials, which can then be tested experimentally."


While these results show promise, a great deal of work lies ahead. "We'd like to make the catalyst a little more clean," Chorkendorff added. "If it contains just a few nanoparticles of pure nickel, the output drops quite a bit, because pure nickel is lousy at synthesizing methanol. In fact, it makes all sorts of chemical byproducts that you don't want."


Nickel is relatively abundant, and gallium, although more expensive, is widely used in the electronics industry. This suggests that the new catalyst could eventually be scaled up for industrial use, according to the authors. But to make methanol synthesis a truly carbon-neutral process will require overcoming many additional hurdles, they noted.


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Dynamic urea bonds for inexpensive self-healing polymer

Dynamic urea bonds for inexpensive self-healing polymer | Amazing Science | Scoop.it

Stretchy, self-healing paints and other coatings recently took a step closer to common use, thanks to research being conducted at the University of Illinois. Scientists there have used "off-the-shelf" components to create a polymer that melds back together after being cut in half, without the addition of catalysts or other chemicals.


The material is made from a proprietary mixture of inexpensive commercially-available compounds, including a polyurea elastomer – polyurea is commonly found in a wide variety of products such as paints and plastics. The researchers reportedly "tweaked" the structure of its molecules, making the bonds between them longer. As a result, the molecules are easier to pull apart from one another, but they're also better able to bond back together.


When samples of what is being called "dynamic polyurea" are cut and then left for a day with the severed ends touching, they will heal back together with almost the same strength that they had before cutting. The process works at room temperature, although raising the ambient temperature to 37ºC (98.6ºF) will speed it up.


Some other experimental self-healing materials incorporate liquid-filled micro-capsules that break open when the material is cut or cracked. This means that they will only heal as long as there are unruptured capsules present. By contrast, dynamic polyurea can reportedly heal over and over again, as it relies solely on its molecular structure.

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Natural 3D Counterpart to Graphene Discovered

Natural 3D Counterpart to Graphene Discovered | Amazing Science | Scoop.it

The discovery of what is essentially a 3D version of graphene – the 2D sheets of carbon through which electrons race at many times the speed at which they move through silicon – promises exciting new things to come for the high-tech industry, including much faster transistors and far more compact hard drives. A collaboration of researchers at the U.S Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) has discovered that sodium bismuthate can exist as a form of quantum matter called a three-dimensional topological Dirac semi-metal (3DTDS). This is the first experimental confirmation of 3D Dirac fermions in the interior or bulk of a material, a novel state that was only recently proposed by theorists.


“A 3DTDS is a natural three-dimensional counterpart to graphene with similar or even better electron mobility and velocity,” says Yulin Chen, a physicist from the University of Oxford who led this study working with Berkeley Lab’s Advanced Light Source (ALS) . “Because of its 3D Dirac fermions in the bulk, a 3DTDS also features intriguing non-saturating linear magnetoresistance that can be orders of magnitude higher than the materials now used in hard drives, and it opens the door to more efficient optical sensors.”


Chen is the corresponding author of a paper in Science reporting the discovery. The paper is titled “Discovery of a Three-dimensional Topological Dirac Semimetal, Na3Bi.”


Two of the most exciting new materials in the world of high technology today are graphene and topological insulators, crystalline materials that are electrically insulating in the bulk but conducting on the surface. Both feature 2D Dirac fermions (fermions that aren’t their own antiparticle), which give rise to extraordinary and highly coveted physical properties. Topological insulators also possess a unique electronic structure, in which bulk electrons behave like those in an insulator while surface electrons behave like those in graphene.


“The swift development of graphene and topological insulators has raised questions as to whether there are 3D counterparts and other materials with unusual topology in their electronic structure,” says Chen. “Our discovery answers both questions. In the sodium bismuthate we studied, the bulk conduction and valence bands touch only at discrete points and disperse linearly along all three momentum directions to form bulk 3D Dirac fermions. Furthermore, the topology of a 3DTSD electronic structure is also as unique as those of topological insulators.”


The discovery was made at the Advanced Light Source (ALS), a DOE national user facility housed at Berkeley Lab, using beamline 10.0.1, which is optimized for electron structure studies. The collaborating research team first developed a special procedure to properly synthesize and transport the sodium bismuthate, a semi-metal compound identified as a strong 3DTDS candidate by co-authors Fang and Dai, theorists with the Chinese Academy of Sciences.

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Theory Worked Out for Metamaterial That Acts as an Analog Computer

Theory Worked Out for Metamaterial That Acts as an Analog Computer | Amazing Science | Scoop.it

The field of metamaterials has produced structures with unprecedented abilities, including flat lenses, invisibility cloaks and even optical “metatronic” devices that can manipulate light in the way electronic circuitry manipulates the flow of electrons. 


Now, the birthplace of the digital computer, ENIAC, is using this technology in the rebirth of analog computing. A study by researchers at the University of Pennsylvania, The University of Texas at Austin and University of Sannio in Italy, shows that metamaterials can be designed to do “photonic calculus” as a light wave goes through them.


A light wave, when described in terms of space and time, has a profile in space that can be thought of as a curve on a Cartesian plane. The researchers’ theoretical material can perform a specific mathematical operation on that wave’s profile, such as finding its first or second derivative, as the light wave passes through the material. Essentially, shining a light wave on one side of such a material would result in that wave profile’s derivative exiting the other side.


Metamaterials capable of other calculus operations, such as integration and convolution, could also be produced. Viewing and manipulating this type of light wave “profile” is an everyday occurrence for applications like image processing, though it is typically done after the light wave has been converted to electronic signals in the form of digital information. The researchers’ proposed computational metamaterials could almost instantly perform such operations on the original wave, such as the light coming in through the lens of a camera, without conversion to electronic signals. 


The study was led by Nader Engheta, the H. Nedwill Ramsey professor of Electrical and Systems Engineering in Penn’s School of Engineering and Applied Science, and Alexandre Silva, a postdoctoral researcher in Engheta’s research group. They collaborated with Francesco Monticone and Andrea Alù of The University of Texas at Austin and Giuseppe Castaldi and Vincenzo Galdi of the University of Sannio in Italy.

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Researchers create first soluble 2D supramolecular organic frameworks

Researchers create first soluble 2D supramolecular organic frameworks | Amazing Science | Scoop.it

Supramolecular chemistry, aka chemistry beyond the molecule, in which molecules and molecular complexes are held together by non-covalent bonds, is just beginning to come into its own with the emergence of nanotechnology. Metal-organic frameworks (MOFs) are commanding much of the attention because of their appetite for greenhouse gases, but a new player has joined the field – supramolecular organic frameworks (SOFs). Researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) have unveiled the first two-dimensional SOFs that self-assemble in solution, an important breakthrough that holds implications for sensing and separation technologies, energy sciences, and, perhaps most importantly, biomimetics.


"We've demonstrated the first soluble single-layer 2D honeycomb SOF that combines the ordering and porous features of MOFs with the solubility of supramolecular polymers," says Yi Liu, a chemist with Berkeley Lab's Materials Sciences Division. "The results prove that we can exercise precise control of dimensionality within structures through a solution-based supramolecular approach, which paves the way for the assembly of more advanced architectures that can be processed in solution."


Liu, who oversees the supramolecular electronics research group at Berkeley Lab's Molecular Foundry, a DOE national nanoscience user facility, is one of three corresponding authors of a paper describing this research in the Journal of the American Chemical Society (JACS). The paper is titled "Toward a Single-Layer Two-Dimensional Honeycomb Supramolecular Organic Framework in Water." The other corresponding authors are Xin Zhao and Zhan-Ting Li, of China's Shanghai Institute of Organic Chemistry and Fudan University.


Traditional molecular chemistry involves the strong covalent bonds formed by the sharing or exchange of electrons between the atoms that make up a molecular system. Supramolecular chemistry involves systems that are held together by a multitude of weaker, non-covalent connections, such as hydrogen bonds and electrostatic and Van der Waals forces. Nature uses supramolecular chemistry to form the double-helix of DNA or to fold proteins. For nanotechnology, single-layers of 2D structurally ordered materials – along the lines of graphene - could fill a great many needs but the key is to process them in solution.


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Cobalt Oxide Nanoparticles Can Split Water Into Hydrogen and Oxygen Using Natural Sunlight

Cobalt Oxide Nanoparticles Can Split Water Into Hydrogen and Oxygen Using Natural Sunlight | Amazing Science | Scoop.it

Researchers from the University of Houston have found a catalyst that can quickly generate hydrogen from water using sunlight, potentially creating a clean and renewable source of energy. Their research, published in Nature Nanotechnology, involved the use of cobalt oxide nanoparticles to split water into hydrogen and oxygen.


Jiming Bao, lead author of the paper and an assistant professor in the Department of Electrical and Computer Engineering at UH, said the research discovered a new photocatalyst and demonstrated the potential of nanotechnology in engineering a material’s property, although more work remains to be done.


Bao said photocatalytic water-splitting experiments have been tried since the 1970s, but this was the first to use cobalt oxide and the first to use neutral water under visible light at a high energy conversion efficiency without co-catalysts or sacrificial chemicals. The project involved researchers from UH, along with those from Sam Houston State University, the Chinese Academy of Sciences, Texas State University, Carl Zeiss Microscopy LLC, and Sichuan University.


Researchers prepared the nanoparticles in two ways, using femtosecond laser ablation and through mechanical ball milling. Despite some differences, Bao said both worked equally well.

Different sources of light were used, ranging from a laser to white light simulating the solar spectrum. He said he would expect the reaction to work equally well using natural sunlight.


Once the nanoparticles are added and light applied, the water separates into hydrogen and oxygen almost immediately, producing twice as much hydrogen as oxygen, as expected from the 2:1 hydrogen to oxygen ratio in H2O water molecules, Bao said.


The experiment has potential as a source of renewable fuel, but at a solar-to-hydrogen efficiency rate of around 5 percent, the conversion rate is still too low to be commercially viable. Bao suggested a more feasible efficiency rate would be about 10 percent, meaning that 10 percent of the incident solar energy will be converted to hydrogen chemical energy by the process.


Other issues remain to be resolved, as well, including reducing costs and extending the lifespan of cobalt oxide nanoparticles, which the researchers found became deactivated after about an hour of reaction.

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