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Chemists devise technology that could transform solar energy storage from microseconds to weeks

Chemists devise technology that could transform solar energy storage from microseconds to weeks | Amazing Science |

A new technology developed by chemists at UCLA is capable of storing solar energy for up to several weeks. 

The materials in most of today’s residential rooftop solar panels can store energy from the sun for only a few microseconds at a time. A new technology developed by chemists at UCLA is capable of storing solar energy for up to several weeks — an advance that could change the way scientists think about designing solar cells.

The findings are published June 19 in the journal Science. The new design is inspired by the way that plants generate energy through photosynthesis.

“Biology does a very good job of creating energy from sunlight,” said Sarah Tolbert, a UCLA professor of chemistry and one of the senior authors of the research. “Plants do this through photosynthesis with extremely high efficiency.”

“In photosynthesis, plants that are exposed to sunlight use carefully organized nanoscale structures within their cells to rapidly separate charges — pulling electrons away from the positively charged molecule that is left behind, and keeping positive and negative charges separated,” Tolbert said. “That separation is the key to making the process so efficient.”

To capture energy from sunlight, conventional rooftop solar cells use silicon, a fairly expensive material.  There is currently a big push to make lower-cost solar cells using plastics, rather than silicon, but today’s plastic solar cells are relatively inefficient, in large part because the separated positive and negative electric charges often recombine before they can become electrical energy.

“Modern plastic solar cells don’t have well-defined structures like plants do because we never knew how to make them before,” Tolbert said. “But this new system pulls charges apart and keeps them separated for days, or even weeks. Once you make the right structure, you can vastly improve the retention of energy.”

The two components that make the UCLA-developed system work are a polymer donor and a nano-scale fullerene acceptor. The polymer donor absorbs sunlight and passes electrons to the fullerene acceptor; the process generates electrical energy.

The plastic materials, called organic photovoltaics, are typically organized like a plate of cooked pasta — a disorganized mass of long, skinny polymer “spaghetti” with random fullerene “meatballs.” But this arrangement makes it difficult to get current out of the cell because the electrons sometimes hop back to the polymer spaghetti and are lost.

The UCLA technology arranges the elements more neatly — like small bundles of uncooked spaghetti with precisely placed meatballs. Some fullerene meatballs are designed to sit inside the spaghetti bundles, but others are forced to stay on the outside.  The fullerenes inside the structure take electrons from the polymers and toss them to the outside fullerene, which can effectively keep the electrons away from the polymer for weeks.

Ra's curator insight, June 23, 5:27 PM

"A new technology developed by chemists at UCLA is capable of storing solar energy for up to several weeks."

changes to solar panel construction that could do away with the need for bulky battery storage or any connection to the grid. Rural camp site looking brighter, although maybe somewhere in the future. 

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Scientists develop catalyst that removes cancer-causing benzene from gasoline

Scientists develop catalyst that removes cancer-causing benzene from gasoline | Amazing Science |

Northwestern University scientists are experimenting with ways to eliminate a cancer-causing agent from gasoline by neutralizing the benzene compound found in gasoline. They developed a catalyst that effectively removed benzene from the other aromatic compounds in gasoline, making it cleaner and more efficient.

An estimated 137 billion gallons of gasoline were consumed in the United States last year, according to the U.S. Energy Information Administration, a daily average of about 375 million gallons. Within each gallon of gas is a chemical compound known as benzene, which has been recognized by the Environmental Protection Agency as a known contributor to cancer. A research team led by Northwestern's Tobin J. Marks has found a way to remove it.

"The gasoline we buy is one-third a mixture of aromatics, and benzene is one of them," said Marks, explaining that aromatics are necessary to improve gas octane numbers and fuel efficiency. "Only benzene is known to be cancer causing, and it's very difficult to remove. Our catalyst opened a whole new way to do that—and probably a very inexpensive way."

Marks is the Vladimir N. Ipatieff Research Professor of Chemistry in the Weinberg College of Arts and Sciences and professor of materials science and engineering in the McCormick School of Engineering and Applied Science.

"We could keep the cost of gasoline down," Marks added, "and a big environmental and health problem would be solved." He describes his team's catalyst as an organometallic molecule, which is not composed of an expensive platinum metal but an affordable, simple metal, which is absorbed onto a particular oxide support. After almost two years of research experimenting with the selective hydrogenation of benzene, the team created a catalyst that removed the benzene from the other aromatics with high selectivity.

"We really know what the catalyst structure looks like," Marks said, "the relative rates of reactions, how the catalyst and aromatics interact with each other and how selective the catalyst is." The research team, which includes scientists from Argonne National Laboratory and Universal Oil Products, released their findings in a paper featured on the cover of the June 3 issue of the Journal of the American Chemical Society.

The cover image depicts their catalyst, with a backdrop of the Chicago River and the architecture that towers over it along Michigan Avenue. "It's eye catching," Marks said. "We tried to blend science with something that looks a little bit different."

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Rapid dynamic reprogramming of matter

Rapid dynamic reprogramming of matter | Amazing Science |

Engineering switchable reconfigurations in DNA-controlled nanoparticle arrays could lead to dynamic energy-harvesting or responsive optical materials

The rapid development of self-assembly approaches has enabled the creation of materials with desired organization of nanoscale components. However, achieving dynamic control, wherein the system can be transformed on demand into multiple entirely different states, is typically absent in atomic and molecular systems and has remained elusive in designed nanoparticle systems. Here, we demonstrate with in situ small-angle X-ray scattering that, by using DNA strands as inputs, the structure of a three-dimensional lattice of DNA-coated nanoparticles can be switched from an initial ‘mother phase into one of multiple ‘daughter phases. The introduction of different types of reprogramming DNA strands modifies the DNA shells of the nanoparticles within the superlattice, thereby shifting interparticle interactions to drive the transformation into a particular daughter phase. Moreover, we mapped quantitatively with free-energy calculations the selective reprogramming of interactions onto the observed daughter phases.

Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have developed the capability of creating dynamic nanomaterials — ones whose structure and associated properties can be switched, on-demand. In a paper appearing in Nature Materials, they describe a way to selectively rearrange nanoparticles in three-dimensional arrays to produce different configurations, or “phases,” from the same nano-components.

“One of the goals in nanoparticle self-assembly has been to create structures by design,” said Oleg Gang, who led the work at Brookhaven’s Center for Functional Nanomaterials (CFN), a DOE Office of Science User Facility. “Until now, most of the structures we’ve built have been static.” KurzweilAI covered that development in a previous article, “Creating complex structures using DNA origami and nanoparticles.”

The new advance in nanoscale engineering builds on that previous work in developing ways to get nanoparticles to self-assemble into complex composite arrays, including linking them together with tethers constructed of complementary strands of synthetic DNA.

“We know that properties of materials built from nanoparticles are strongly dependent on their arrangements,” said Gang. “Previously, we’ve even been able to manipulate optical properties by shortening or lengthening the DNA tethers. But that approach does not permit us to achieve a global reorganization of the entire structure once it’s already built.”

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Study provides new data on chemical gardens, whose formation is a mystery for science

Study provides new data on chemical gardens, whose formation is a mystery for science | Amazing Science |

Recent research which has counted with the participation of the University of Granada Andalusian Institute of Earth Sciences has yielded new data on chemical gardens, mysterious formations produced when certain solid salts (copper sulfate, cobalt chloride) are added to an aqueous solution of sodium silicate.

Self-contained chemical gardens are formed through the self-assembly of mineral precipitates generated during certain chemical reactions, and they produce coloured forms that resemble vegetable structures. The first researcher who watched them was Johann Rudolf Glauber in 1646, and since then their formation has been a veritable mystery for the scientific community.

Besides their popularity in chemistry experiments for massive audiences, self-contained chemical gardens present analogies with a variety of natural systems, such as the ice channels formed underneath sea ice or the hydrothermal chimneys at the bottom of the oceans where it is believed that life on earth could have originated.

Their growth patterns are being studied today fundamentally to produce new self-structuring materials, or to understand their role in the origin of life, thanks to the energy they can store.

To produce a chemical garden in the lab, one typically introduces a metallic salt in an alkaline solution within a container. This leads to the growth of a series of irregular, tubular, multi-coloured structures thanks to the combined action of different physical processes (osmotic pressure, gravity effects, reactions and diffusion). The fact that these different processes interact in a complex way without any sort of control whatsoever provokes the irregularity, and above all the impossibility of reproducing the obtained three-dimensional forms obtained in this process. This precludes detailed understanding of the growth mechanisms of these structures.

In this context, researchers from the Non-linear Physical Chemistry Unity at the Free University of Brussels, and from the University of Granada Andalusian Institute of Earth Sciences have demonstrated that it is possible to obtain an important collection of reproducible structures by having the chemical gardens grow in a confined, almost bi-dimensional environment, by injecting a reagent inside another one between two horizontal plaques. The horizontal confinement of the reactor reduces the effects of gravity, while the injection of one reagent within another reduces the effects of osmotic pressure. Besides, the control of the initial concentrations of the reagents, and of the flow of injection allows for the study of the relative importance of chemical processes and transport within the selection of the shape in the precipitate.

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Exotic, gigantic molecules - predicted since 1970 - fit inside each other like Russian nesting dolls

Exotic, gigantic molecules - predicted since 1970 - fit inside each other like Russian nesting dolls | Amazing Science |

University of Chicago scientists have experimentally observed for the first time a phenomenon in ultracold, three-atom molecules predicted by Russian theoretical physicist Vitaly Efimov in 1970.

In this quantum phenomenon, called geometric scaling, the triatomic molecules fit inside one another like an infinitely large set of Russian nesting dolls. “This is a new rule in chemistry that molecular sizes can follow a geometric series, like 1, 2, 4, 8…,” said Cheng Chin, professor in physics. “In our case, we find three molecular states in this sequence where one molecular state is about 5 times larger than the previous one.”

Chin and four members of his research group published their findings Dec. 9, 2014, in Physical Review Letters.

“Quantum theory makes the existence of these gigantic molecules inevitiable, provided proper—and quite challenging—conditions are created,” said Efimov, now at the University of Washington. The UChicago team observed three molecules in the series, consisting of one lithium atom and two cesium atoms in a vacuum chamber at the ultracold temperature of approximately 200 nanokelvin, a tiny fraction of a degree above absolute zero (minus 459.6 degrees Fahrenheit).

Given an infinitely large universe, the number of increasingly larger molecules in this cesium-lithium system also would extend to infinity. This remarkable idea stems from the exotic nature of quantum mechanics, which conforms to different laws of physics than those that govern the universe on a macroscopic scale.

“These are certainly exotic molecules,” said Shih-Kuang Tung, the postdoctoral scholar, now at Northwestern University, who led the project. Only under strict conditions could Tung and his colleagues see the geometric scaling in their Efimov molecules. It appears that neither two-atom nor four-atom molecules can achieve the Efimov state. “There’s a special case for three atoms,” Chin said.

Efimov’s reaction to the research was twofold: “First, I am amazed by the predictive power of the quantum theory,” he said. “Second, I am amazed by the skill of the experimentalists who managed to create those challenging conditions.”

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Black Phosphorous: The Birth of a New Wonder Material

Black Phosphorous: The Birth of a New Wonder Material | Amazing Science |
Materials scientists have discovered how to make black phosphorous nanosheets in large amounts, heralding a new era of nanoelectronic devices.

In the last few years, two-dimensional crystals have emerged as some of the most exciting new materials to play with. Consequently, materials scientists have been falling over themselves to discover the extraordinary properties of graphene, boron nitride, molybdenum disulphide, and so on. A late-comer to this group is black phosphorus, in which phosphorus atoms join together to form a two-dimensional puckered sheet. Last year, researchers built a field-effect transistor out of black phosphorus and showed that it performed remarkably well. This research suggested that black phosphorous could have a bright future in nanoelectronic devices.

But there is a problem. Black phosphorus is difficult to make in large quantities. Today, Damien Hanlon at Trinity College Dublin in Ireland, and a number of pals, say they have solved this problem. These guys have perfected a way of making large quantities of black phosphorus nanosheets with dimensions that they can control. And they have used this newfound ability to test black phosphorus in a number of new applications, such as a gas sensor, an optical switch, and even to reinforce composite materials to make them stronger.

In bulk form, black phosphorus is made of many layers, like graphite. So one way to separate single sheets is by exfoliation, simply peeling off layers using Scotch tape or other materials. That is a time-consuming task that severely limits potential applications.

So Hanlon and co have been toying with another approach. Their method is to place the black phosphorus lump in a liquid solvent and then bombard it with acoustic waves that shake the material apart.

The result is that the bulk mass separates into a large number of nanosheets that the team filters for size using a centrifuge. That leaves high-quality nanosheets consisting of only a few layers. “Liquid phase exfoliation is a powerful technique to produce nanosheets in very large quantities,” they say.

Reference: : Liquid Exfoliation Of Solvent-Stabilized Black Phosphorus: Applications Beyond Electronics

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Chemists create ‘artificial chemical evolution’ for the first time

Chemists create ‘artificial chemical evolution’ for the first time | Amazing Science |

Scientists have taken an important step towards the possibility of creating synthetic life with the development of a form of artificial evolution in a simple chemistry set without DNA.

A team from the University of Glasgow’s School of Chemistry report in a new paper in the journal Nature Communications today (Monday 8 December) on how they have managed to create an evolving chemical system for the first time. The process uses a robotic ‘aid’ and could be used in the future to ‘evolve’ new chemicals capable of performing specific tasks.

The researchers used a specially-designed open source robot based upon a cheap 3D printer to create and monitor droplets of oil in water-filled Petri dishes in their lab. Each droplet was composed from a slightly different mixture of four chemical compounds.

Droplets of oil move in water like primitive chemical machines, transferring chemical energy to kinetic energy. The researchers’ robot used a video camera to monitor, process and analyse the behaviour of 225 differently-composed droplets, identifying a number of distinct characteristics such as vibration or clustering.

The team picked out three types of droplet behavior – division, movement and vibration – to focus on in the next stage of the research. They used the robot to deposit four droplets of the same composition, then ranked the droplets in order of how closely they fit the criteria of behaviour identified by the researchers. The chemical composition of the ‘fittest’ droplet was then carried over into a second generation of droplets, and the process of robotic selection was begun again.

Over the course of 20 repetitions of the process, the researchers found that the droplets became more stable, mimicking the natural selection of evolution.

The research team was led by Professor Lee Cronin, the University of Glasgow’s Regius Chair of Chemistry. Professor Cronin said: “This is the first time that an evolvable chemical system has existed outside of biology. Biological evolution has given rise to enormously complex and sophisticated forms of life, and our robot-driven form of evolution could have the potential to do something similar for chemical systems.

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Where did all the xenon go?

Where did all the xenon go? | Amazing Science |

The noble gas xenon should be found in terrestrial and Martian atmospheres, but researchers have had a hard time finding it.

The prevailing theory claims that due to xenon’s weight -- it is a heavy gas -- it could be trapped in a planet’s core or in the mantle during the planet’s formation.  Lawrence Livermore scientists and collaborators have discovered that the xenon can be trapped in the subsurface of the Earth, shedding new insights into the long-standing mysteries of the “missing xenon” in earth science.

The discovery of the noble gas xenon (Xe) has led to the synthesis of hundreds of Xe compounds (for example, it is thought that a compound made up of xenon and iron may lie in Earth’s core). Its reactivity also has been estimated to be the cause of its depletion by a factor of 20 relative to the lighter noble gases -- neon, argon and krypton -- in the atmosphere of Earth, Mars and other planetary bodies. Specifically, xenon reacts with hydrogen and ice at high pressures to form stable compounds.

The team used a high pressure diamond anvil cell, which applies extreme pressures on materials, and advanced synchrotron X-ray scattering techniques to show that under high pressure and temperature, a silicate mineral, made up mostly of silver, irreversibly inserts xenon into its micropores and undergoes charge separation. As opposed to other noble gases such as argon and krypton, xenon stays within the pores even after pressure and heat are decreased.

“This is a new chemical reaction that could account for the ‘missing xenon’ observed in terrestrial and Martian atmospheres," said Hyunchae Cynn, one of the LLNL physicists involved in the research. The team found missing xenon from the atmosphere trapped within porous rocks in a planet’s core or mantle.

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Isotope effect produces new type of chemical bond - the vibrational muonium bond

Isotope effect produces new type of chemical bond - the vibrational muonium bond | Amazing Science |

Researchers believe they have confirmed the existence of a new type of chemical bond, first proposed some 30 years ago but never convincingly demonstrated because of the lack of experimental evidence and the relatively poor accuracy of the quantum chemistry methods that prevailed at the time.1 The new work also shows how substituting isotopes can result in fundamental changes in the nature of chemical bonding.

In the early 1980s it was proposed that in certain transition states consisting of a very light atom sandwiched between two heavy ones, the system would be stabilised not by conventional van der Waal’s forces, but by vibrational bonding, with the light atom shuttling between its two neighbours. However, despite several groups searching for such a system none was demonstrated and the hunt fizzled out.

Now, Jörn Manz, of the Free University of Berlin and Shanxi University in China, and colleagues believe they have the theoretical and experimental evidence to demonstrate a stable vibrational bond.

The researchers carried out a series of theoretical experiments looking at the reaction of BrH with Br to create the radical BrHBr, but using different isotopes of hydrogen. By using muons – elementary particles that are similar to an electron but have greater mass – the team added a range of hydrogen isotopes to BrHBr from the relatively hefty muonic helium4H, to the extremely light muonium, Mu, with a mass nearly 40 times smaller than 4H.

The team mapped two key parameters: the potential energy surface of the system – the three-dimensional potential energy ‘landscape’ relating the energy of the surface, with hills and valleys – to the geometry; and a quantum mechanical parameter, the vibrational zero point energy or ZPE.

Classically, a bond will form if there is a net reduction in the potential energy of the system. However, in certain circumstances, if there is a sufficiently large decrease in the vibrational ZPE, this can overcome the need for a decrease in potential energy and the system can be stabilised by a vibrational bond.

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Ultra-fast ‘phase-change materials’ could lead to 1,000-times-faster computers

Ultra-fast ‘phase-change materials’ could lead to 1,000-times-faster computers | Amazing Science |

Replacing silicon, new ultra-fast “phase-change materials” (PCMs) that could eventually enable processing speeds 500 to 1,000 times faster than the average laptop computer today — while using less energy — have been modeled and tested by researchers from the University of Cambridge, the Singapore A*STAR Data-Storage Institute, and the Singapore University of Technology and Design.

PCMs are capable of reversibly switching between two structural phases with different electrical states — one crystalline and conducting and the other glassy and insulating — in billionths of a second, increasing the number of calculations per second.

Also, logic operations and memory are co-located, rather than separated, as they are in silicon-based computers (causing interconnect delays and slowing down computation speed), and PCM devices can function down to about two nanometers (compared to the current smallest logic and memory devices based on silicon, which are about 20 nanometers in size). The researchers have also demonstrated that multiple parallel calculations are possible for PCM logic/memory devices.

Achieving record switching speed

The researchers used a new type of PCM based on a specific chalcogenide glass material that goes further: it can be melted and recrystallized in as little as 900 picoseconds (trillionths of a second) using appropriate voltage pulses.

PCM devices recently demonstrated to perform in-memory logic do have shortcomings: they do not perform calculations at the same speeds as silicon, and they exhibit a lack of stability in the starting amorphous phase.

However, the Cambridge and Singapore researchers found that, by performing the logic-operation process in reverse — starting from the crystalline phase and then melting the PCMs in the cells to perform the logic operations — the materials are both much more stable and capable of performing operations much faster.

The results are published in the journal Proceedings of the National Academy of Sciences.

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Star of David: New star-shaped molecule of interlocking rings is the most complex of its kind ever created

Star of David: New star-shaped molecule of interlocking rings is the most complex of its kind ever created | Amazing Science |

Known as a 'Star of David' molecule, scientists have been trying to create one for over a quarter of a century and the team's findings are published in the 21 September 2014 issue of Nature Chemistry.

Consisting of two molecular triangles, entwined about each other three times into a hexagram, the structure's interlocked molecules are tiny – each triangle is 114 atoms in length around the perimeter. The molecular triangles are threaded around each other at the same time that the triangles are formed, by a process called 'self-assembly', similar to how the DNA double helix is formed in biology.

The molecule was created at The University of Manchester by PhD student Alex Stephens. Professor David Leigh, in Manchester's School of Chemistry, said: "It was a great day when Alex finally got it in the lab. In nature, biology already uses molecular chainmail to make the tough, light shells of certain viruses and now we are on the path towards being able to reproduce its remarkable properties.

"It's the next step on the road to man-made molecular chainmail, which could lead to the development of new materials which are light, flexible and very strong. Just as chainmail was a breakthrough over heavy suits of armour in medieval times, this could be a big step towards materials created using nanotechnology. I hope this will lead to many exciting developments in the future."

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Rethinking basic science of graphene synthesis shows route to industrial-scale production

Rethinking basic science of graphene synthesis shows route to industrial-scale production | Amazing Science |

A new route to making graphene has been discovered that could make the 21st century's wonder material easier to ramp up to industrial scale. Graphene—a tightly bound single layer of carbon atoms with super strength and the ability to conduct heat and electricity better than any other known material—has potential industrial uses that include flexible electronic displays, high-speed computing, stronger wind-turbine blades, and more-efficient solar cells, to name just a few under development.

In the decade since Nobel laureates Konstantin Novoselov and Andre Geim proved the remarkable electronic and mechanical properties of graphene, researchers have been hard at work to develop methods of producing pristine samples of the material on a scale with industrial potential. Now, a team of Penn State scientists has discovered a route to making single-layer graphene that has been overlooked for more than 150 years.

"There are lots of layered materials similar to graphene with interesting properties, but until now we didn't know how to chemically pull the solids apart to make single sheets without damaging the layers," said Thomas E. Mallouk, Evan Pugh Professor of Chemistry, Physics, and Biochemistry and Molecular Biology at Penn State. In a paper first published online on Sept. 9 in the journal Nature Chemistry, Mallouk and colleagues at Penn State and the Research Center for Exotic Nanocarbons at Shinshu University, Japan, describe a method called intercalation, in which guest molecules or ions are inserted between the carbon layers of graphite to pull the single sheets apart.

The intercalation of graphite was achieved in 1841, but always with a strong oxidizing or reducing agent that damaged the desirable properties of the material. One of the most widely used methods to intercalate graphite by oxidation was developed in 1999 by Nina Kovtyukhova, a research associate in Mallouk's lab.

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Tests confirm nickel-78 is a 'doubly magic' isotope

Tests confirm nickel-78 is a 'doubly magic' isotope | Amazing Science |

The stability of atoms can vary considerably from one element to the next, and also between isotopes of the same element (whose nuclei contain the same number of protons but different numbers of neutrons). While many isotopes are unstable and rapidly undergo radioactive decay, certain 'magic' isotopes show exceptional stability. Clarifying the properties of these stable isotopes is essential for understanding how the chemical elements formed in the early Universe. In an important step toward verifying various theoretical models, Shunji Nishimura and colleagues from the RIKEN Nishina Center for Accelerator-Based Science have now verified the magic numbers of an enigmatic 'doubly magic' isotope, nickel-78.

The magic numbers for isotope stability are well established for isotopes with similar numbers of protons and neutrons. The seven most widely recognized magic numbers are 2, 8, 20, 28, 50, 82 and 126; these correspond to the number of particles needed to completely fill proton or neutron 'shells' in the nucleus. The nickel-78 (78Ni) isotope contains 28 protons and 50 neutrons, making it doubly magic according to this series. However, isotopes with such a large excess of neutrons compared to protons are predicted to have different magic numbers, and some theoretical models even suggest that 78Ni is not magic at all. Consequently, much attention has been paid to the magic properties of 78Ni in efforts to verify theoretical models of nuclear physics and the formation of heavy elements.

Settling the issue of the magic stability of 78Ni experimentally, however, has proved challenging. "Many experiments have been carried out to identify systematic trends in nuclear properties near 78Ni," says Nishimura. "Yet there has been no clear evidence on whether 78Ni is a double-magic nuclei due to the extremely low production yield of this isotope."

Fortunately, RIKEN's Radioactive Isotope Beam Factory is capable of generating high yields of exotic and rare isotopes like 78Ni (Fig. 1). Using this facility, in combination with the newly developed WAS3ABi detector, the research team was able to perform measurements of 78Ni decay with unprecedented precision. The experiments confirmed the doubly magic status of 78Ni, providing valuable insights into the behavior of exotic nuclei with large neutron excess. Such neutron-rich nuclei play an important role in the production of elements heavier than the most stable element iron, such as gold and uranium. "We hope to solve one of the biggest mysteries of this century—where and how were the heavy elements created in the Universe?" explains Nishimura.

Reference: Xu, Z. Y., Nishimura, S., Lorusso, G., Browne, F., Doornenbal, P., Gey, G., Jung, H.-S., Li, Z., Niikura, M., Söderström, P.-A. et al. "β-decay half-lives of 76,77Co, 79,80Ni, and 81Cu: Experimental indication of a doubly magic 78Ni." Physical Review Letters 113, 032505 (2014). DOI: 10.1103/PhysRevLett.113.032505

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Transient excitons observed in metals for the first time – the primary response of free electrons to light

Transient excitons observed in metals for the first time – the primary response of free electrons to light | Amazing Science |

Researchers have observed, in metals for the first time, transient excitons – the primary response of free electrons to light. Here, the researchers discovered that the surface electrons of silver crystals can maintain the excitonic state more than 100 times longer than for the bulk metal, enabling the excitons to be experimentally visualized by a newly developed multidimensional coherent spectroscopic technique.

Detecting excitons in metals could provide clues on how light is converted into electrical and chemical energy in solar cells and plants. This research may also provide ways to alter the function of metals in order to develop active elements for technologies such as optical communications by controlling how light is reflected from a metal.

The act of looking in a mirror is an everyday experience, but the quantum mechanical description behind this familiar phenomenon is still unknown. When light reflects from a mirror, the light “shakes” the metal’s free electrons and the resulting acceleration of electrons creates a nearly perfect replica of the incident light – providing a reflection. Excitons, or particles of the light-matter interaction where light photons become temporarily entangled with electrons in molecules and semiconductors, are known to be important to this process and others such as photosynthesis and optical communications.

Unfortunately, studying and proving how excitons function in metals is difficult because they are extremely short-lived, lasting for approximately 100 attoseconds, or less than a 0.1 quadrillionth of a second. For the first time researchers have observed excitons at metallic surfaces that maintain the excitonic state 100 times longer than in the bulk metal, enabling the excitons to be experimentally captured by a newly developed multidimensional multiphoton photoemission spectroscopic technique.

This discovery sheds light on the primary excitonic response of solids which could allow quantum control of electrons in metals, semiconductors, and organic materials. It also potentially allows for the generation of intense femotosecond electron pulses that could increase resolution for time-resolved electron microscopes that follow the motion of individual atoms and molecules as they rearrange themselves during structural transitions or chemical reactions.

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Chemists discover key reaction mechanism behind the highly touted sodium-oxygen battery

Chemists discover key reaction mechanism behind the highly touted sodium-oxygen battery | Amazing Science |

Chemists at the University of Waterloo have discovered the key reaction that takes place in sodium-air batteries that could pave the way for development of the so-called holy grail of electrochemical energy storage. The key lies in Nazar's group discovery of the so-called proton phase transfer catalyst. By isolating its role in the battery's discharge and recharge reactions, Nazar and colleagues were not only able to boost the battery's capacity, they achieved a near-perfect recharge of the cell. When the researchers eliminated the catalyst from the system, they found the battery no longer worked. Unlike the traditional solid-state battery design, a metal-oxygen battery uses a gas cathode that takes oxygen and combines it with a metal such as sodium or lithium to form a metal oxide, storing electrons in the process. Applying an electric current reverses the reaction and reverts the metal to its original form.

Understanding how sodium-oxygen batteries work has implications for developing the more powerful lithium-oxygen battery, which is has been seen as the holy grail of electrochemical energy storage. Their results appear in the journal Nature Chemistry.

"Our new understanding brings together a lot of different, disconnected bits of a puzzle that have allowed us to assemble the full picture," says Nazar, a Chemistry professor in the Faculty of Science.

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Chemists cook up three atom-thick electronic sheets on a transparent silica wafer

Chemists cook up three atom-thick electronic sheets on a transparent silica wafer | Amazing Science |
Making thin films out of semiconducting materials is analogous to how ice grows on a windowpane: When the conditions are just right, the semiconductor grows in flat crystals that slowly fuse together, eventually forming a continuous film.

This process of film deposition is common for traditional semiconductors like silicon or gallium arsenide – the basis of modern electronics – but Cornell scientists are pushing the limits for how thin they can go. They have demonstrated a way to create a new kind of semiconductor thin film that retains its electrical properties even when it is just atoms thick.

Three atom-thick layers of molybdenum disulfide were cooked up in the lab of Jiwoong Park, associate professor of chemistry and chemical biology and member of the Kavli Institute at Cornell for Nanoscale Science. The films were designed and grown by postdoctoral associate Kibum Kang and graduate student Saien Xie. Their work is published online in Nature, April 30.

“The electrical performance of our materials was comparable to that of reported results from single crystals of molybdenum disulfide, but instead of a tiny crystal, here we have a 4-inch wafer,” Park said.

Molybdenum disulfide, which is garnering worldwide interest for its excellent electrical properties, has previously been grown only in disjointed, “archipelago”-like single crystal formations, Park said. But making smooth, flat, ultrathin sheets, like paper, is the ultimate goal, and the bridge to actual devices.

The researchers pulled off the feat by tuning the growth conditions of their films using a technique called metal organic chemical vapor deposition (MOCVD). Already used widely in industry, but with different materials, it starts with a powdery precursor, forms a gas and sprinkles single atoms onto a substrate, one layer at a time.

Park’s group systematically optimized the technique to make the films, tweaking conditions and temperatures not unlike experimenting in the kitchen. They found that their crystals grew perfectly stitched together, but only with a little bit of hydrogen and in completely dry conditions, for example. In addition to advanced optical imaging techniques, researchers led by co-author David Muller, professor of applied and engineering physics and director of Cornell’s Kavli Institute, contributed advanced transmission electron microscopy to test and characterize the quality of the films as they went along.
Alison Winn's curator insight, May 6, 6:32 AM

An exciting development.

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Penta-graphene, a new structural variant of carbon, discovered

Penta-graphene, a new structural variant of carbon, discovered | Amazing Science |
The newly discovered material, called penta-graphene, is a single layer of carbon pentagons that resembles the Cairo tiling, and that appears to be dynamically, thermally and mechanically stable.

"The three last important forms of carbon that have been discovered were fullerene, the nanotube and graphene. Each one of them has unique structure. Penta-graphene will belong in that category," said the paper's senior author, Puru Jena, Ph.D., distinguished professor in the Department of Physics in VCU's College of Humanities and Sciences.

The researchers' paper, "Penta-Graphene: A New Carbon Allotrope," will appear in the journal Proceedings of the National Academy of Sciences, and is based on research that was launched at Peking University and VCU.

Qian Wang, Ph.D., a professor at Peking University and an adjunct professor at VCU, was dining in a restaurant in Beijing with her husband when she noticed artwork on the wall depicting pentagon tiles from the streets of Cairo.

"I told my husband, "Come, see! This is a pattern composed only of pentagons,'" she said. "I took a picture and sent it to one of my students, and said, 'I think we can make this. It might be stable. But you must check it carefully.' He did, and it turned out that this structure is so beautiful yet also very simple."

Most forms of carbon are made of hexagonal building blocks, sometimes interspersed with pentagons. Penta-graphene would be a unique two-dimensional carbon allotrope composed exclusively of pentagons.

Nicolás Dominguez's curator insight, February 5, 1:34 PM

AÑADA su visión ...

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Laser-generated surface structures create extremely hydrophobic metals

Laser-generated surface structures create extremely hydrophobic metals | Amazing Science |
Scientists at the University of Rochester have used lasers to transform metals into extremely water repellent, or super-hydrophobic, materials without the need for temporary coatings.

Super-hydrophobic materials are desirable for a number of applications such as rust prevention, anti-icing, or even in sanitation uses. However, as Rochester's Chunlei Guo explains, most current hydrophobic materials rely on chemical coatings. In a paper published today in the Journal of Applied Physics, Guo and his colleague at the University's Institute of Optics, Anatoliy Vorobyev, describe a powerful and precise laser-patterning technique that creates an intricate pattern of micro- and nanoscale structures to give the metals their new properties. This work builds on earlier research by the team in which they used a similar laser-patterning technique that turned metals black. Guo states that using this technique they can create multifunctional surfaces that are not only super-hydrophobic but also highly-absorbent optically.

Guo adds that one of the big advantages of his team's process is that "the structures created by our laser on the metals are intrinsically part of the material surface." That means they won't rub off. And it is these patterns that make the metals repel water.

"The material is so strongly water-repellent, the water actually gets bounced off. Then it lands on the surface again, gets bounced off again, and then it will just roll off from the surface," said Guo, professor of optics at the University of Rochester. That whole process takes less than a second. As the water bounces off the super-hydrophobic surfaces, it also collects dust particles and takes them along for the ride. To test this self-cleaning property, Guo and his team took ordinary dust from a vacuum cleaner and dumped it onto the treated surface. Roughly half of the dust particles were removed with just three drops of water. It took only a dozen drops to leave the surface spotless. Better yet, it remains completely dry.

Guo is excited by potential applications of super-hydrophobic materials in developing countries. It is this potential that has piqued the interest of the Bill and Melinda Gates Foundation, which has supported the work.

Steve Foster's curator insight, January 22, 4:05 PM

If our future cars are made of this stuff, rust is a goner. Waterslides, sleds, skis, skates... Things made of this stuff would glide so easily! Metal and lasers are the answers to most problems, this just adds another to the list!

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Chemists Fabricate Novel Rewritable Paper Using Color Switching Redox Dyes

Chemists Fabricate Novel Rewritable Paper Using Color Switching Redox Dyes | Amazing Science |

First developed in China in about the year A.D. 150, paper has many uses, the most common being for writing and printing upon.  Indeed, the development and spread of civilization owes much to paper’s use as writing material. According to surveys, 90 percent of all information in businesses used today is retained on paper, even though the bulk of this printed paper is discarded after just one-time use. This is such a waste of paper and ink cartridges — not to mention the accompanying environmental problems such as deforestation and chemical pollution to air, water and land—could be curtailed if the paper were “rewritable,” that is, capable of being written on and erased multiple times.

Chemists at the University of California, Riverside have now fabricated in the lab just such novel rewritable paper, one that is based on the color switching property of commercial chemicals called redox dyes.  The dye forms the imaging layer of the paper.  Printing is achieved by using ultraviolet light to photobleach the dye, except the portions that constitute the text on the paper.  The new rewritable paper can be erased and written on more than 20 times with no significant loss in contrast or resolution.

“This rewritable paper does not require additional inks for printing, making it both economically and environmentally viable,” said Yadong Yin, a professor of chemistry, whose lab led the research. “It represents an attractive alternative to regular paper in meeting the increasing global needs for sustainability and environmental conservation.”

The rewritable paper is essentially rewritable media in the form of glass or plastic film to which letters and patterns can be repeatedly printed, retained for days, and then erased by simple heating.

The paper comes in three primary colors: blue, red and green, produced by using the commercial redox dyes methylene blue, neutral red and acid green, respectively.  Included in the dye are titania nanocrystals (these serve as catalysts) and the thickening agent hydroxyethyl cellulose (HEC).  The combination of the dye, catalysts and HEC lends high reversibility and repeatability to the film.

During the writing phase, ultraviolet light reduces the dye to its colorless state.  During the erasing phase, re-oxidation of the reduced dye recovers the original color; that is, the imaging material recovers its original color by reacting with ambient oxygen.  Heating at 115 C can speed up the reaction so that the erasing process is often completed in less than 10 minutes. “The printed letters remain legible with high resolution at ambient conditions for more than three days – long enough for practical applications such as reading newspapers,” Yin said. “Better still, our rewritable paper is simple to make, has low production cost, low toxicity and low energy consumption.”

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Tissint meteorite shows kerogen-like carbonaceous components, potential signs of past biological activity on Mars

Fallen in Morocco in 2011, the Tissint meteorite has since then been thoroughly studied by scientists. A new study, published 1st December 2014 in Meteoritics and Planetary Sciences, shows that the meteorite contains organic carbon of biogenic origin, and that this carbon infiltrated the Tissint rock on Mars, before an asteroid shock sent it towards the Earth. Philippe Gillet, co-author of the article and head of the Earth and planetary science laboratory at EPFL, explains their findings.

Tissint landed in the desert of Guelmim-Es Semara, Morocco, on July 18, 2011. It was thrown from the surface of Mars by an asteroid collision some 700,000 years ago -- and there is no other meteorite quite like it. The 7-11 kilogram grey rock -- seared glassy black on the outside by the heat of entry, called a fusion crust -- showed evidence of water. It was riddled with tiny fissures, into which water had deposited material.

This material, on analysis, turned out to be an organic carbon compound -- one that was biological in origin. It is not the only meteorite in which organic carbon has been found, but the debate has always centered on whether the carbon was deposited before or after the meteorite in question landed on Earth -- to wit, whether it is terrestrial or extraterrestrial in origin.

A team of researchers now studied the organic carbon found in the fissures of Tissint and determined that it is not of this world. There are several points of evidence put forward by the team. First, there was a relatively short timeframe between when the meteorite was observed falling to Earth and when it was collected. The second is that the microscopic fissures in the rock would have had to have been produced by a sudden high heat -- such as, for example, the heat of atmospheric entry. This shock, and the temperatures required to open the fissures, could not have come from the Moroccan desert. Thirdly, some of the carbon grains inside Tissint had hardened into diamond. There are no known conditions under which this could have occurred on the surface of the Moroccan desert -- and certainly not in the time it took between the meteorite's fall and discovery.

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Seaborgium Hexacarbonyl Sg(CO)6: First Carbonyl Complex of a Superheavy Element

Seaborgium Hexacarbonyl Sg(CO)6: First Carbonyl Complex of a Superheavy Element | Amazing Science |

Atoms with the same number of protons belong to the same element. Atomic nuclei with the same number of protons and different numbers of neutrons are called isotopes. The elements up to uranium (element 92) exist in nature (except for technetium ). The elements heavier than uranium are man-made. All elements are arranged in the periodic table of the elements. Their positions in the periodic table correspond to their proton number; elements in the same column (i.e., in the same group) feature similar and electronic shell structure, which characterizes the chemical behavior of an element. An element's position in the periodic table and thus provides information on its chemical behavior, e.g., as a metal or an inert gas.

If atomic nuclei have too many protons (all of which repel each other) or have an this ratio is unfavorable proton to neutron ratio, the nuclei are not stable but undergo radioactive decay. The elements up to the element fermium (which has atomic number 100) can be produced at research reactors by irradiating a target of a heavy element with neutrons. The target atoms capture a neutrons and subsequently decay through β--emission, thus forming an element with the next higher proton number. This process can be repated, up to fermium.

As there are no isotopes of fermium which decay through β--emission, no elements with higher proton number can be synthesized by this method.

The heavier an atom is, the more protons are contained in its nucleus. With increasing proton number, the repulsive force of these protons will eventually lead to immediate disintegration of the nucleus. The elements with a proton number higher than 103 can only exist due to nuclear shell effects and are called the superheavy elements. A topic of intense research concerns the question of the heaviest possible element. To date, all elements up to element 112 as well as elements 114 and 116 are officially recognized as discovered, and reports about the observation also of element 113,115117, and 118 are also published. It is currently not clear, which element is the heaviest one that can exist.

The production of 265Sg and its separation in GARIS was perfected in preparatory work led by Dr. Hiromitsu Haba from RIKEN Nishina Center (RNC) and his team. In this nuclear reaction, a few Sg atoms per hour can be produced.

Seaborgium hexacarbonyl – Why is it so special?

Carbon monoxide (CO) is known to form complexes with many transition metals. In 1890, Ludwig Mond, Carl Langer and Friedrich Quincke reported of the first synthesis of a carbonyl complex – nickeltetracarbonyl ( Ni(CO)4; see here). In this compound, the nickel (Ni) atom is surrounded by 4 carbon monoxide molecules (CO).

In this type of molecule, coordination bonds (rather than covalent bonds) form between the metal and the carbon monoxide.

The carbon monoxide ligands bind to the metal by forming a so-called σ-donation bond, and a π-backbond from the metal to the carbon monoxide ligand establishes. In the σ-donation bond the highest occupied molecular orbital (HOMO) of the CO donates electron density into the σ-symmetric orbitals of the metal (s or p1/2 or dz2 orbitals). In the π-backbonding, electron density for the π-symmetric d-orbital is donated to the lowest unoccupied molecular orbital (LUMO) of the CO-ligand. The σ-donation bond is the strongest bond, while the π-backbond is slightly weaker.

Synthesis of carbonyl complexes with fusion products directly behind the target in a CO-containing atomosphere is not possible, as the primary beam would pass the gas and create a plasma. This would destroy the CO molecules. Therefore, only our new approach to perform chemical experiments behind a separator like TASCA or GARIS allows the synthesis and study of this compound class.

Chemistry experiments with superheavy elements -  with periodic numbers higher than 104 – are difficult to perform. First, scientists have to produce the element artificially in a particle accelerator. The production rates are really low, usually lower than a few atoms per day. Furthermore, these atoms are very instable, and survive in the best case less than 10 seconds. However, science is still very interested to investigate the characteristics of these superheavy elements, since they allow to test the influence of Einstein's relativity theory on chemistry. The high number of positively charged protons in the atomic nucleus of superheavy elements accelerate the electrons in the different shells to extremely high velocities - close to 80% of the speed of light. Due to the relativistic effects at these speeds, electrons are much heavier than when they are at rest, which in turn should have some influence on the chemical properties of the superheavy atom. These effects will be compared with elements that possess a similar atomic structure but are lighter. Such studies will be of enormous interest to all basic chemists in the world.

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No need for water, enzymes are doing it for themselves even under hydrophobic conditions

No need for water, enzymes are doing it for themselves even under hydrophobic conditions | Amazing Science |
New research by scientists at the University of Bristol has challenged one of the key axioms in biology - that enzymes need water to function. The breakthrough could eventually lead to the development of new industrial catalysts for processing biodiesel.

Enzymes are large biological molecules that catalyse thousands of different chemical reactions that are essential for all life, from converting food into energy, to controlling how our cells replicate DNA.

Throughout this diverse range of biological environments in which enzymes perform their various roles, the only constant is an abundance of water.

However, new findings published today [6 October] in Nature Communications, show that water is not essential for enzymes to fulfil their biological role.

This discovery could pave the way for the development of new thermally robust industrial enzymes that could be utilised in harsh processing conditions, with applications ranging from detergent technologies to alternative energies via biofuel production.

Rowan Edwards's curator insight, October 6, 2014 12:27 PM

yet another reason to re-connect with nature. 

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Scientists synthesize Germanene, a novel two-dimensional germanium allotrope akin to graphene and silicene

Scientists synthesize Germanene, a novel two-dimensional germanium allotrope akin to graphene and silicene | Amazing Science |

After the successful synthesis of silicene in 2012, which was followed by a surge of studies on elemental, novel two-dimensional (2D) materials beyond graphene, a daunting quest was to obtain germanene, the germanium-based analogue of graphene, already predicted to possibly exist in 2009. Although its fully hydrogenated form, germanane, was fabricated using a wet chemistry method in 2013, germanene has remained elusive. Scientists now show compelling experimental and theoretical evidence of its synthesis by dry epitaxial growth on a gold (111) surface.

The discovery of graphene boosted research in nanoscience on 2D materials, especially on elemental ones. In 2012, silicene, graphene's silicon cousin [1], was successfully synthesized on two metallic templates, namely a silver (111) surface [23] and the zirconium diboride (0001) surface of a thin film grown on a silicon (111) substrate [4]. One year later, silicene was also grown on an iridium (111) surface [5]. Germanene, another germanium-based cousin of graphene, along with silicene, had already been predicted to be stable as freestanding novel germanium and silicon 2D allotropes in a low buckled honeycomb geometry by Cahangirov et al in 2009 [6]. In the quest for germanene, its fully hydrogen-terminated partner, germanane (GeH), was first fabricated from the topochemical deintercalation of the layered van der Waals solid calcium digermanide (CaGe2) [7]; next, the stability of germanane was improved by replacing the H atom termination with a methyl group one [8].

Since silicene has, up to now, only been synthesized in dry conditions under ultrahigh vacuum (UHV)—with silver (111) as the favored substrate—trying to synthesize germanene by also growing it on Ag(111) single crystals using germanium molecular beam epitaxy seems tempting. However, this has failed up to now, because (1) the 'magic mismatch' between three lattice constants of silicene and four of the Ag(111) plane is not fulfilled for germanene, and (2) germanium most probably prefers to form an ordered Ag2Ge surface alloy, where Ge atoms, up to a coverage of one-third of a monolayer (1/3 ML), substitute Ag ones at the silver surface. This surface alloy presents a complex '√3 × √3' structure [9], which not only deviates in its geometry but also in its electronic properties [910] from the simple √3 × √3 reconstruction envisaged earlier [11].

Scientists have thus used a gold (111) substrate instead to avoid such a surface alloy formation. Indeed, for silicene synthesis they deposited silicon on silver (111) surfaces because the inverse system, silver grown on Si(111) surfaces, is well-known to form atomically abrupt interfaces, without intermixing [12]. This choice of an Au(111) substrate is based on the same strategy. It turns out that among the four noble metals on elemental semiconductor systems studied, namely, Au, Ag/Ge, Si(111) [12], the most similar in several aspects, especially in the growth mode—the Stranski–Krastanov (or layer-plus-islands) mode characterized by the formation of a √3 × √3 R30° superstructure (or wetting layer) associated with the formation of Au trimers on Ge(111) [13] or Ag ones on Si(111)—appeared to be Si/Ag(111) [14] and Ge/Au(111) [15], a trend confirmed in a recent study of Au/Ge(111) [16].

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Electric Prism Separates Ortho and Para Nuclear Spin States of Water for the First Time

Electric Prism Separates Ortho and Para Nuclear Spin States of Water for the First Time | Amazing Science |

At first glance, water seems to be a simple molecule in which a single oxygen atom is bound to two hydrogen atoms. However, it is more complex when taking into account hydrogen’s nuclear spin – a property reminiscent of a rotation of its nucleus about its own axis. The spin of a single hydrogen can assume two different orientations, symbolized as up and down. Thus, the spins of water’s two hydrogen atoms can either add up, called ortho water, or cancel out, called para water. Ortho and para states are also said to be symmetric and antisymmetric, respectively.

Fundamental symmetry rules prohibit para water from turning into ortho water and vice versa – at least theoretically. “If you had a magic bottle with isolated paraand ortho molecules, they would remain in their spin states at all times,” says DESY scientist Jochen Küpper who led the recent study. “In principle, they are different molecular species, different types of water.” However, in the real world, water molecules are not isolated and frequently collide with other molecules or surfaces in their vicinity, causing nuclear spin orientations to change. “Through these interactions, para and ortho water can actually transform easily into one another,” explains Küpper who is also a professor at the University of Hamburg and a member of the Hamburg Centre for Ultrafast Imaging (CUI). “Therefore, it is very challenging to separate them and produce water that is not a mixture of both.”

Yet, the CFEL researchers have now demonstrated a way of isolating para and ortho water in the lab. To start, the scientists placed a drop of water in a compartment, which they pressurized with neon or argon gas. This mixture was released into vacuum through a pulsed valve. “Due to the large pressure difference, the gas expands quickly into the vacuum when the valve is opened, dragging along water molecules and, at the same time, cooling them down,” says Daniel Horke, the first author of the study.

This expansion produces a narrow beam of ultracold water molecules, which propagate at supersonic speed and are so dilute that individual molecules no longer collide with each other, thereby suppressing the conversion between para and ortho spin states.

The molecular beam then travels through a strong electric field, which deflects the water molecules from their original flight path and acts like a prism for nuclear spin states. “Para andortho water interact with the electric field differently,” Horke explains. “Thus, they also get deflected differently, allowing us to separate them in space and obtain pure para and orthosamples.” Spectroscopy showed that the purity of the para and ortho water was 74 per cent and over 97 per cent, respectively. Especially for para water the purity can be greatly enhanced in the future, as Horke says. Storing the separated water species was not an aim of the study.

The new method could benefit studies of a wide range of phenomena. In astrophysics, for example, it is commonly assumed that the relative amounts of para and ortho species can be linked to the temperature of interstellar ice. This theory is based on the temperature dependence of hydrogen’s ortho-to-para ratio, which is three to one at room temperature and drops with decreasing temperatures. “In fact, certain regions of the universe exhibit ratios that are quite different from what you would expect,” Horke says. “Yet, the specific reasons are unknown and lab-based experiments could provide new insights.”

Back on Earth, the study may also help determine the structures of proteins – biomolecules that are essential to all life. A method known as nuclear magnetic resonance (NMR) spectroscopy reconstructs protein structures from the relative orientation of the nuclear spins of hydrogen and other atoms. “Para hydrogen has successfully been used to enhance the sensitivity of the NMR method,” says Horke. “Thus, enriching para water in a protein’s water shell could become an interesting approach to improve NMR spectroscopy of these biological systems due to an almost natural environment.”

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'Pick 'n' Mix' chemistry to grow cultures of bioactive molecules

'Pick 'n' Mix' chemistry to grow cultures of bioactive molecules | Amazing Science |
Chemists at ETH-Zürich and ITbM, Nagoya University have developed a new method to build large libraries of bioactive molecules – which can be used directly for biological assays – by simply mixing a small number of building blocks in water.

Professor Jeffrey Bode of ETH-Zürich and the Institute of Transformative Bio-Molecules (ITbM) of Nagoya University, and his co-worker have established a new strategy called "synthetic fermentation" to rapidly synthesize a large number of bioactive molecules, which can be directly screened in biological assays simply by mixing a few building blocks in aqueous media. Using a highly selective amide-forming ligation, the reaction proceeds in high efficiency in the absence of organisms, enzymes or reagents. The fermentation products can be screened directly for biological activity without any purification. Synthetic fermentation has enabled the generation of about 6,000 unnatural peptide-like molecules from only 23 building blocks. The practicality of this approach is shown by identifying a bioactive compound for inhibiting an enzyme responsible for the replication of the hepatitis C virus. The study, published online on September 7, 2014 in Nature Chemistry as an Advanced Online Publication, is expected to be a powerful and practical method to allow rapid generation and screening of active molecules useful for drug discovery and other industrial applications as well as for simple biological assays on site.

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