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By Admin (from 27/05/2011 @ 14:00:12, in en - Science and Society, read 3002 times)

A retina made in a laboratory in Japan could pave the way for treatments for human eye diseases, including some forms of blindness.

Created by coaxing mouse embryonic stem cells into a precise three-dimensional assembly, the 'retina in a dish' is by far and away the most complex biological tissue engineered yet, scientists say.

"There's nothing like it," says Robin Ali, a human molecular geneticist at the Institute of Ophthalmology in London who was not involved in the study. "When I received the manuscript, I was stunned, I really was. I never thought I'd see the day where you have recapitulation of development in a dish."

If the technique, published today in Nature (This article is reproduced with permission from the magazine Nature. The article was first published on April 6, 2011. - TA note), can be adapted to human cells and proved safe for transplantation -- which will take years -- it could offer an unlimited well of tissue to replace damaged retinas. More immediately, the synthetic retinal tissue could help scientists in the study of eye disease and in identifying therapies.

The work may also guide the assembly of other organs and tissues, says Bruce Conklin, a stem-cell biologist at the Gladstone Institute of Cardiovascular Disease in San Francisco, who was not involved in the work. "I think it really reveals a larger discovery that's coming upon all of us: that these cells have instructions that allow them to self-organize."

Cocktail recipe

In hindsight, previous work had suggested that, given the right cues, stem cells could form eye tissue spontaneously, Ali says. A cocktail of genes is enough to induce frog embryos to form form eyes on other parts of their body, and human embryonic stem cells in a Petri dish can be coaxed into making the pigmented cells that support the retina, sheets of cells that resemble lenses and light-sensing retinal cells themselves.

However, the eye structure created by Yoshiki Sasai at the RIKEN Center for Developmental Biology in Kobe and his team is much more complex.

The optic cup is brandy-snifter-shaped organ that has two distinct cell layers. The outer layer -- that nearest to the brain -- is made up of pigmented retinal cells that provide nutrients and support the retina. The inner layer is the retina itself, and contains several types of light-sensitive neuron, ganglion cells that conduct light information to the brain, and supporting glial cells.

To make this organ in a dish, Sasai's team grew mouse embryonic stem cells in a nutrient soup containing proteins that pushed stem cells to transform into retinal cells. The team also added a protein gel to support the cells. "It's a bandage to the tissue. Without that, cells tend to fall apart," Sasai says.

At first, the stem cells formed blobs of early retinal cells. Then, over the next week, the blobs grew and began to form a structure, seen early in eye development, called an optic vesicle. Just as it would in an embryo, the laboratory-made optic vesicle folded in on itself over the next two days to form an optic cup, with its characteristic brandy-snifter shape, double layer and the appropriate cells.

Even though the optic cups look and develop like the real thing, "there may be differences between the synthetic retina and what happens normally," Ali says.

Sasai's team has not yet tested whether the optic cups can sense light or transmit impulses to the mouse brain. "That's what we are now trying," he says. However, previous studies have suggested that embryonic retinas can be transplanted into adult rodents, so Sasai is hopeful.

Sasai, Ali and others expect that human retinas, which develop similarly to those of mice, could eventually be created in the lab. "In terms of regenerative medicine, we have to go beyond mouse cells. We have to make human retinal tissue from human embryonic stem cells and investigation is under way," Sasai says.

The eyes have it

Synthetic human retinas could provide a source of cells to treat conditions such as retinitis pigmentosa, in which the retina's light-sensing cells atrophy, eventually leading to blindness. In 2006, Ali's team found that retinal cells from newborn mice work when transplanted into older mice. Synthetic retinas, he says, "provide a much more attractive, more practical source of cells".

David Gamm, a stem-cell biologist at the University of Wisconsin, Madison, says that transplanting entire layers of eye tissue, rather than individual retinal cells, could help people with widespread retinal damage. But, he adds, diseases such as late-stage glaucoma, in which the wiring between the retina and brain is damaged, will be much tougher to fix.

When and whether such therapies will make it to patients is impossible to predict. However, in the nearer term, synthetic retinas will be useful for unpicking the molecular defects behind eye diseases, and finding treatments for them, Sasai says. Retinas created from reprogrammed stem cells from patients with eye diseases could, for instance, be used to screen drugs or test gene therapies, Ali says.

Robert Lanza, chief scientific officer of the biotechnology company Advanced Cell Technology, based in Santa Monica, California, says the paper has implications far beyond treating and modeling eye diseases. The research shows that embryonic stem cells, given the right physical and chemical surroundings, can spontaneously transform into intricate tissues. "Stem cells are smart," Lanza says. "This is just the tip of the iceberg. Hopefully it's the beginning of an important new phase of stem-cell research."

Source: ScientificAmerican

 

A flexible, controllable trailing edge for wind turbine blades has shown that it can reduce the loads on the turbine and in the end provide cheaper electricity from wind power.

The idea dates back to 2003 when researchers from Risø DTU was inspired by the prey's ability to maneuver in turbulent air currents, while they at the same time remained at a stable point in the air. Now a three-year project, with three industry partners, is launched and is to develop the promising technology forward to a robust and durable trailing edge which can be tested on a full-scale blade.

The fierce gusts and turbulence, such as wind turbines are exposed to constantly, contribute significantly to the cost of producing electricity from wind turbines. The turbines must be designed to resist these influences throughout their lifespan of at least 20 years since repairs are costly, especially when the turbines are located far out at sea and are more than 100 meters high. Therefore, researchers and industry are aimed at finding technical solutions that can alleviate the loads on the turbines.

"We have already had a good start of the project with our first project meeting in early March. The composition of project partners is well suited in order to solve the challenges in the project" says Research Specialist and Project Manager Helge Aagaard Madsen from Risø DTU.

Robust, reliable and durable

The buzz words for the project are to develop a technology that is: robust, reliable and durable. The specific solution that has been under development at Risø since 2006, supported by funds from Region Zealand, is a flexible trailing edge of rubber or plastic. Movement of the trailing edge is achieved by elastic deformations caused by fiber reinforced cavities that run through the rear and can be pressurized with air or hydraulics. It is these controlled movements that counteract the forces from the fierce wind gusts.

"The technology has already been tested under laboratory conditions and in a wind tunnel with promising results. Now the task is to have a prototype produced by the end of project that is ready for testing on a full-scale turbine "explains Research Specialist Helge Aagaard Madsen and continues:

"We want to develop and produce prototypes in 2m-long rubber or plastic in the project, depending on what's most robust and give the best result."

The three industrial partners in the project each contribute specific knowledge in key areas. Eg AVN is already experts in the hydraulic systems that are currently used for turbine pitch systems. Since AVN develops, manufactures and sells these systems for different wind turbine manufacturers they can contribute with a unique understanding of how the new flaps systems can operate together with the pitch system.

"The pitch system is what rotate the blades today so that they are positioned optimal towards the wind, but it costs both loads and energy to turn a 15-ton rotor blade as compared to what it will 'cost' for our small local movements with a flexible blade trailing edge that perhaps only has a weight of 1% of the blade's total weight, "explains Helge Aagaard Madsen.

The other two project partners is Rehau, that among other supplies plastic parts for the car industry and Dansk Gummi Industri which manufactures molded rubber and polyurethane to the industry. Rehau will contribute to develop the new materials that the trailing edge can be manufactured from, and the Dansk Gummi Industri will work on the production side of the trailing edge also called CRTEF (Controllable Rubber Trailing Edge Flap).

No mechanical parts

The flexible trailing edge is entirely without mechanical parts and we hope completely to avoid metal parts. And this part is important. Helge Aagaard Madsen explains:

"It is important that the technologies we develop now are virtually maintenance free. It is of no use to add another component on the turbine that needs a lot of maintenance and can break. This is also why it is very important that we have a good collaboration with the industry from this early stage. In this way we can ensure that the product matches what the industry needs and wants. Both when it comes to the production and the application side. "

From Risø DTU experts in wind turbines contribute, but also the expertise of the material scientists' is in focus, as there is great need for knowledge on fiber reinforcements and composite materials. From DTU Electrical Engineering researchers also contribute with knowledge about lightning, since wind turbines due to their height have an elevated risk of being hit by lightning. This factor must of course also be taken into account when the prototype developed.

Source: physorg

Provided by Technical University of Denmark for ZeitNews.org

 

A little rain or fog may seem like an insignificant threat to a helicopter or airplane. But minor clouds and precipitation can be the cause of canceled flights -- or fatalities.

It's dangerously easy for water droplets to turn to ice and coat an airplane’s wings, unless something could prevent the ice from adhering, lessening or eliminating the problem.

That's what Ed Smith has dedicated his time and research to for the past decade.

"The basic problem is when you fly through an icing cloud, which is about freezing temperature and has water in the cloud, and water of a certain size, [the particles] hit and start forming," Smith, professor of aerospace engineering and director of the Penn State Rotorcraft Center of Excellence, explains. "They call it accreting on the surface of the blades—or the airplane itself—and it ruins the aerodynamic characteristics of the blades."

Smith, along with Jose Palacios, a research associate in aerospace engineering, run an adverse environment rotor test stand lab in Hammond Building. The idea was conceived 10 years ago and built in phases, Smith said.

The lab has two purposes, he says: to take measurements and quantify how ice builds up, in what shape and how fast it accretes; and to test how tightly ice grips to the surface of the blade, something they call "adhesion strength."

With the help of donated equipment from Boeing, Smith and his associates remodeled the lab. It was previously the high temperature testing lab before it was handed over to the Department of Aerospace Engineering.

After installing a motor, drive system and freezer in the lab, researchers spent the last three years completing the complicated process of creating an ice cloud. Smith and his researchers sought the help of NASA's icing center in Cleveland, which provided them with a series of nozzles required to create the cloud.

Besides NASA and Boeing, the lab has numerous sponsors that help fund its research: the Army, Navy and Goodrich, as well as several small companies in State College, including FBS, Inc.

The past year has seen substantial progress not only in verifying that the lab is getting proper icing conditions and proper icing shapes with its equipment, but also with the ice protection system itself—a new system involving ultrasound technology, instead of the existing electrothermal system.

"The current way ice protection is done is with heat. They imbed little heater elements just under the skin of the blade," Smith explains. But these systems are heavy and unreliable, and they use enormous amounts of power. This allows only the largest helicopters to even attempt to use them, meaning most helicopters simply can't fly in any type of icing condition in the winter.

Airplanes, however, have hot engines to help prevent icing. Many planes have a sophisticated system that uses the engines’ hot air to blow over the inlets, melting ice, Smith said -- but the systems are no guarantee.

"You always hear every winter, 'icing results in the crash of an airplane,'" Smith says. "If the ice forms on part of the blade and not the others, you can really have bad vibration problems, so it's a lot of fatalities over the last several decades. Usually either the ice protection system didn’t come on or it didn't work right."

For helicopters, no such hot air or de-icing system exists for its rotor blades. Ice can form, weighing down the rotor and causing blades to shed off. This leads to violent shaking, much like if one would attach a weighted object to a blade on a ceiling fan, Smith says.

Fortunately, he says the new ultrasound system has been very promising over the last eight years, since he and researchers started working on it.

Smith describes the new process as a mechanical stress—the ice forms on the blade and the blade shakes back and forth at high speeds, peeling the ice off.

"It's the same thing you're really doing when you use an ice scraper, hit the ice at an angle and shear it off, that's what it's doing."

Now, Smith says his team is working to develop the technology to make it work in a practical way. In addition to helicopters, it could be relevant to airplanes, engine inlets, wing turbines—anything that is outside and subject to the elements.

Another aspect of the system is a new, efficient way to evaluate the condition of the blades, further improving a helicopter's safety. The technology uses a piece of metal located in the front of each rotor blade intended to balance their center of gravity, Smith says.

The idea is to remove that and replace it with a ceramic material, which has the same density of lead. "We take this mass out and replace it with something that can move at high frequencies ... in this case, we take advantage of the fact that all blades and wings have this mass in the leading edge that don't do anything useful except moving the center of gravity forward," Smith explains. "So now we can make better use out of a heavy material in the nose—we think that is very attractive."

When blades and wings are manufactured, they are inspected using ultrasonic CAT scans to make sure there are no cracks and the bonds are in good shape. But usually, Smith says, they're never inspected again after they leave the factory.

The ceramic masses, however, serve as ultrasonic transducers and can double as vehicles for periodic inspection for damage, in addition to de-icing aids.

So far, Smith says he doesn't have any patents for the technology he's helped develop. Though he has filed several invention disclosures over the last few years, he says the university gets many invention disclosures and can only choose a certain number to pursue a patent. But that doesn't bother him.

"So far, we haven't had our disclosures picked up; a lot of things are in public domain," he says. "I'm personally not motivated by patents—that drives some people nuts. That's not what's driving us; we want to educate the community."

Smith says his lab's new ultrasound system could be useful, but implementing it would be tricky due to the decades-long history with the current, electrothermal system.

"It's kind of like a hybrid car—it takes a long time. You're so used to a gasoline engine, if you want to switch over, there are a lot of questions people have to ask before you can just replace everything," he explains. "We're trying to answer as many of those questions as we can."

Source: physorg

Provided by Pennsylvania State University for ZeitNews.org

 
By Admin (from 03/06/2011 @ 14:00:35, in en - Science and Society, read 1907 times)

People who have strokes are often left with moderate to severe physical impairments. Now, thanks to a glove developed at McGill, stroke patients may be able to recover hand motion by playing video games. The Biomedical Sensor Glove was developed by four final-year McGill Mechanical Engineering undergrads under the supervision of Professor Rosaire Mongrain. It is designed to allow patients to exercise in their own homes with minimal supervision, while at the same time permitting doctors to monitor their progress from a distance, thus cutting down on hospital visits and costs.

Patients can monitor their progress thanks to software which will generate 3D models and display them on the screen, while at the same time sending the information to the treating physician.

The glove was developed by the students in response to a design request from the startup company Jintronix Inc. The students met with company representatives once a week for several months to develop the glove, which can track the movements of the wrist, the palm and the index finger using several Inertial Measurement Units. Although similar gloves currently exist, they cost approximately $30,000.

By using more accurate and less expensive sensors, the students were able to develop a glove that currently costs $1000 to produce.  Jintronix, Inc. has submitted the project to Grand Challenges Canada, which is an independent not-for-profit organization dedicated to improving the health and well-being of people in developing countries, in the hopes that they will receive funding for further development.

Source: physorg

Provided by McGill University for ZeitNews.org

 
By Admin (from 06/06/2011 @ 08:00:58, in en - Science and Society, read 1784 times)

Time to retire the old soldering iron? In the "atomtronic" circuits pictured on the right, it is atoms, not electrons, that flow. Such circuits could form the basis for ultra-sensitive gyroscopes.

Previously, atoms have been made to flow from one point to another. To get them to flow round and round in a circuit, Kevin Wright and colleagues at the National Institute of Standards and Technology in Gaithersburg, Maryland, chilled 100,000 sodium atoms until they became a Bose-Einstein condensate – a blob of floating atoms that behaves as a single, coherent quantum object.


The researchers used a complex array of lasers to trap and shape the blob into a torus. A further pair of lasers, one in a rotating configuration, gave the atoms just enough energy to circulate in unison around the ring, but not so much energy that the condensate decohered.

This "current" of atoms flowed for 40 seconds, four times longer than atoms in previous experiments.

Superfluid gyroscope

Flowing atoms act like frictionless "superfluids"", which are highly sensitive to rotation, so such atomtronic circuits might be used to build ultra-sensitive gyroscopes, says Wright.

His team also pinched off part of the torus with another laser, restricting the flow of atoms, but not stopping them entirely. In electrical circuits, the closest analogy to this is a Josephson junction, a gap over which current flows between two superconductors. These form the basis of superconducting quantum interference devices (SQUIDS), which are used to measure magnetic fields with high sensitivity.

Matthew Davis, a physicist at the University of Queensland in Brisbane, Australia, calls the new work "impressive" and agrees that it could eventually lead to "practical devices that are extremely sensitive for the detection of rotational or gravitational forces".

Source: NewScientist

 

Some 300 exabytes (3 × 1020 bytes) of information were stored in electronic media -- magnetic disks and tapes or optical disks -- throughout the world by 2007. Yet, the demand for electronic storage grows daily, driving an ever-increasing need to pack data into smaller volumes in quicker time. By studying how laser pulses alter the atomic structure of data-storage materials, a research team in Japan has uncovered a fundamental mechanism that could aid in the design of even faster information storage in the future1. The finding was published by Masaki Takata from the RIKEN SPring-8 Center, Harima, Shinji Kohara from the Japan Synchrotron Radiation Research Institute/SPring-8, Noboru Yamada from Panasonic Corporation and a team of scientists from Japan, Germany and Finland.

Atomic-level crystal gazing

Pulses of light alter the atomic bonds (red) in the material AIST, enabling quick storage and deletion of data. Credit: 2011 Masaki Takata

Rewritable memory, such as the random-access memory found in computers or on DVDs, is based on a phase change in specific types of materials in which the atoms change from one stable arrangement to another. Pulses of laser light can induce a phase change, a process known as ‘writing,’ and the material’s phase can be identified by ‘reading’ its signature optical properties.

To provide the first full understanding of the atomic structure of one such phase-change material, AgInSbTe (AIST)—often used in rewritable DVDs—Takata and his colleagues combined state-of-the-art materials-analysis techniques and theoretical modeling. A pulse of light can change AIST from an amorphous state, in which the atoms are disordered, into a crystalline phase in which the atoms are form an ordered-lattice structure. This process of crystallization happens in just a few tens of nanoseconds: the faster the crystallization, the faster data can be written and erased. No-one understood, however, why phase changes in AIST were so fast.

The teams’ analyses and modeling showed that AIST crystallizes in a different way to other commercially available phase-change materials. They found that crystallization of AIST is a simple process: the laser light excites the bonding electrons and causes them to move. A central atom of antimony (Sb) switches between one long (amorphous) and one short (crystalline) bond without any bond breaking (Fig. 1). “We hope to verify this bond-interchange model in the near future,” says Takata. “Crystallization is the storage-rate-limiting process in all phase-change materials, and an atomistic understanding of it is essential.”

The researchers also discovered that the absence of cavities within the crystal structure contributes to the faster writing speeds on AIST. This contrasts starkly with the alternative material germanium antimony telluride in which 10% of lattice sites in are empty.

Source: PhysOrg

 
By Admin (from 09/06/2011 @ 11:00:36, in en - Science and Society, read 1867 times)

It's billed as the wonder material of the 21st century with the power to revolutionise micro-electronics, and won its pioneers the 2010 Nobel Physics Prize.

Professor Jacek Baranowski of the Institute of Electronic Materials Technology (ITME) in Warsaw poses on April 7 [Image], near a laser in the Polish capital. Baranowski 's team says it has discovered a new method to produce entire layers of graphene, a move that should help to propel it out of the lab and into everyday life.

Now Polish scientists say they have discovered a new method to produce entire layers of graphene, a move that should help to propel it out of the lab and into everyday life.

Professor Jacek Baranowski of the Institute of Electronic Materials Technology in Warsaw

Professor Jacek Baranowski of the Institute of Electronic Materials Technology (ITME) in Warsaw poses on April 7, near a laser in the Polish capital. Baranowski 's team says it has discovered a new method to produce entire layers of graphene, a move that should help to propel it out of the lab and into everyday life.

Just one atom thick, the novel form of carbon is the world's thinnest and strongest nano-material, almost transparent and able to conduct electricity and heat.

"This is an important step forward on the path to the production of transistors and then integrated circuits made of graphene," Professor Jacek Baranowski of the Institute of Electronic Materials Technology (ITME) in Warsaw told AFP.

Russian-born, British-based researchers Andre Geim and Konstantin Novoselov were honoured with a Nobel last October for their pioneering work.

Graphene transistors would in theory be able to run at faster speeds and cope with higher temperatures than today's classic silicon computer chips.

That would resolve a fast-growing problem facing chip engineers who want to boost power and shrink semiconductor size but without raising temperatures, the bugbear of computing.

Graphene's transparency also means it could potentially be used in touch screens and even solar cells, and when mixed with plastics would provide light but super-strong composite materials for next-generation satellites, planes and cars.

Electrons can travel relatively huge distances through graphene -- a thousandth of a millimetre is a lot in their world -- without being hampered by impurities which are a problem in the silicon used in 95 percent of electronic devices.

They also pick up speeds of 1,000 kilometres (620 miles) per second in graphene, some 30 times faster than in silicon.

Graphene is also 200 times tougher than steel.

But the catch so far has been a lack of methods to turn out layers of it, and that is where the work of Baranowski's research team come in.

"The new method is based on using the technique of epitaxy on silicon carbide in a gaseous, pressurised environment," said Baranowski, who also works at the University of Warsaw's experimental physics faculty.

Epitaxy is a technique for growing a micro-thin, honeycomb-shaped lattice of the desired material.

While it is currently possible to produce graphene layers, relatively large ones can only be made on a metal base. That hampers graphene's electronics potential.

Without such a base, current techniques only allow for a maximum layer surface of four square inches (25 square centimetres).

Current methods also fail to produce graphene as uniform as that devised by Baranowski's team, he said.

It is precisely that uniformity that would make graphene more readily usable in the hi-tech sector, he added.

The team's discovery was announced in the most recent edition of the US scientific periodical Nano Letters. It is set to be presented at a conference starting Monday in Bilbao, Spain.

ITME's research was carried out under the wing of the European Science Foundation, which groups 78 organisations in 30 nations.

It is part of a wider project aimed at producing a graphene transistor, along with researchers in the Czech Republic, France, Germany, Sweden and Turkey.

Source: PhysOrg

 
By Admin (from 11/06/2011 @ 11:00:40, in en - Science and Society, read 2655 times)

Architect Eugene Tsui is taking the gigantic volcano tower concept to a whole new eco level, by taking design inspiration from the natural world. His new design for the Ultima Tower – a 2-mile high Mt Doom-esque structure – borrows design principles from trees and other living ystem to reduce its energy footprint.

We are always intrigued by architecture that uses biomimicry – the borrowing of principles from nature’s designs – and Tsui’s concept for this towering, ultra-dense urban development has certainly captured our attention with its thought-provoking design.

Population growth rates and rural-urban migration are creating a trend of chaotic urbanization that brings environmental, economic and social challenges. Within the next 7 years, 22 megacities across the globe are expected to have populations that exceed 10 million people, according to the UN. The Ultima Tower is an innovative green design concept proposed to resourcefully use earth’s surface and allow sustainable distribution of resources within a dense urban setting.

Designed to withstand natural calamities, Ultima Tower is highly stable and aerodynamic. Rather than spreading horizontally the structure rises vertically from a base with a 7,000 foot diameter – inspired in part by the termite’s nest structures of Africa, the highest structure created by any living organism.

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Surrounded on all sides by a lake, the building would use building integrated photo-voltaic solar cells to meet most of the electrical energy requirements. The tower would also use Atmospheric Energy Conversion to exploit the differences in atmospheric pressure at the bottom and top of the tower and convert this differential into electrical power. Wind turbine energy would also be used to power the tower.

Taking a cue from the principles of transpiration and cohesion (Joly-Dixon’s cohesion-tension theory) as used by the tree to move water from roots to aerial parts, the designers are working on a method of carrying water from the bottom of the tower to the top utilizing water potential difference between the two points.

Other significant features of the design include bodies of water placed at 12 separate levels, 144 elevators at the periphery of the building, use of vertical propulsion through compressed air, specially designed windows with aerodynamic wind cowls, reflecting mirrors to bring direct sunlight into the building, open garden balconies, electric cars run by propane and hydrogen gas, complete absence of internal combustion engines or toxic pollutants. The whole building is envisioned by Tsui as a large ecosystem teeming with structures that are ‘living and breathing’.

Source: Inhabitat

 

Advances made by researchers at Los Alamos National Laboratory could enhance the ability of scientists to develop advanced nuclear fuels in a safer, simpler manner.

Uranium chemistry research relies heavily on a variety of uranium "starting materials"—solids and solutions—that are precursors to uranium compounds of oxygen, nitrogen, halogen, carbon, fluorine, and other elements, all of which are candidates for advanced nuclear fuels.

Uranium also has been identified as a promising material in developing superconductors, and for use as catalysts—to speed up other chemical reactions.

But uranium starting materials have traditionally been relatively difficult or hazardous to produce.  Now researchers at Los Alamos National Laboratory have developed a method to produce uranium starting materials in a much more benign fashion. The method, recently published in the scientific journal Organometallics, relies on a room-temperature process that reacts uranium metal in a solution of 1,4-dioxane – a liquid organic solvent – and iodine.

Conventional methods of producing uranium starting materials can require toxic chlorine-containing compounds and high temperatures or mercury iodide and low temperatures.  Some of these syntheses are dangerous and generate a fair amount of waste.

“A major barrier to widespread uranium chemistry research has been access to these starting materials,” said Jaqueline Kiplinger, lead scientist on the research.  “Easy access to uranium(III) and -(IV) precursors can change the way people do uranium work because there is less waste, and it’s simpler, cleaner, safer, and faster.”

The synthesis involves placing readily available metal uranium shavings in a liquid bath of 1,4-dioxane and iodine at room temperature and stirring.  The result is either UI3(1,4-dioxane)1.5 or UI4(1,4-dioxane)2, both called uranium iodides.  Both waste little of the original uranium and are highly resistant to degradation.  Further, these starting materials have been used to make many other uranium compounds that are valuable in uranium research.

“It’s my belief that these developments will open doors to a variety of new uranium research areas,” said Kiplinger.”

In a recent edition of the magazine Chemistry World, Stephen Liddle, a uranium chemistry researcher in the United Kingdom, agreed. “Historically this area has lagged behind many others, and one reason is the lack of suitable precursor materials,” he said. ”Hopefully these alternative uranium halides will help open up the area in general by leading to new compounds.”

The research team includes Marisa Monreal, a Seaborg Graduate Student Fellow at Los Alamos, Robert Thomson and Nicholas Travia, both Seaborg Postdoctoral Fellows at Los Alamos, Thibault Cantat, Brian Scott and Jaqueline Kiplinger (all of materials physics & applications division). The research was supported by the DOE Office of Science-Heavy Element Chemistry program, the Los Alamos Laboratory Directed Research and Development program, and through Los Alamos National Laboratory Director’s and G.T. Seaborg Institute for Transactinium Science Postdoctoral Fellowships.

The Chemistry World article is available at HERE.

The Organometallics research paper is available HERE.

Find out more about Los Alamos National Laboratory HERE.

 

In a development that holds intriguing possibilities for the future of industrial catalysis, as well as for such promising clean green energy technologies as artificial photosynthesis, researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) have created bilayered nanocrystals of a metal-metal oxide that are the first to feature multiple catalytic sites on nanocrystal interfaces. These multiple catalytic sites allow for multiple, sequential catalytic reactions to be carried out selectively and in tandem.

Tandem catalysis in nanocrystal interfaces could be boon to green energy

Transmission electron micrograph showing monolayer of a cerium oxide nanocube monolayer on a platinum monolayer in a new bilyaer nanocatalyst. Credit: Image courtesy of Yang group

"The demonstration of rationally designed and assembled nanocrystal bilayers with multiple built-in metal–metal oxide interfaces for tandem catalysis represents a powerful new approach towards designing high-performance, multifunctional nanostructured catalysts for multiple-step chemical reactions," says the leader of this research Peidong Yang, a chemist who holds joint appointments with Berkeley Lab's Materials Sciences Division, and the University of California Berkeley's Chemistry Department and Department of Materials Science and Engineering.

Yang is the corresponding author of a paper describing this research that appears in the journal Nature Chemistry. The paper is titled "Nanocrystal bilayer for tandem catalysis."

Co-authoring the paper were Yusuke Yamada, Chia-Kuang Tsung, Wenyu Huang, Ziyang Huo, Susan Habas, Tetsuro Soejima, Cesar Aliaga and leading authority on catalysis Gabor Somorjai.

Catalysts – substances that speed up the rates of chemical reactions without themselves being chemically changed – are used to initiate virtually every industrial manufacturing process that involves chemistry. Metal catalysts have been the traditional workhorses, but in recent years, with the advent of nano-sized catalysts, metal,oxide and their interface have surged in importance.

"High-performance metal-oxide nanocatalysts are central to the development of new-generation energy conversion and storage technologies," Yang says. "However, to significantly improve our capability of designing better catalysts, new concepts for the rational design and assembly of metal–metal oxide interfaces are needed."

Studies in recent years have shown that for nanocrystals, the size and shape – specifically surface faceting with well-defined atomic arrangements – can have an enormous impact on catalytic properties. This makes it easier to optimize nanocrystal catalysts for activity and selectivity than bulk-sized catalysts. Shape- and size-controlled metal oxide nanocrystal catalysts have shown particular promise.

In a unqiue new bilyaer nanocatalyst system, single layers of metal and metal oxide nanocubes are deposited to create two distinct metal-metal oxide interfaces that allow for multiple, sequential catalytic reactions to be carried out selectively and in tandem. Credit: Image courtesy of Yang grouppress

In a unqiue new bilyaer nanocatalyst system, single layers of metal and metal oxide nanocubes are deposited to create two distinct metal-metal oxide interfaces that allow for multiple, sequential catalytic reactions to be carried out selectively and in tandem. Credit: Image courtesy of Yang group

"It is well-known that catalysis can be modulated by using different metal oxide supports, or metal oxide supports with different crystal surfaces," Yang says. "Precise selection and control of metal-metal oxide interfaces in nanocrystals should therefore yield better activity and selectivity for a desired reaction."

To determine whether the integration of two types of metal oxide interfaces on the surface of a single active metal nanocrystal could yield a novel tandem catalyst for multistep reactions, Yang and his coauthors used the Lamgnuir-Blodgett assembly technique to deposit nanocube monolayers of platinum and cerium oxide on a silica (silicon dioxide) substrate. The nanocube layers were each less than 10 nanometers thick and stacked one on top of the other to create two distinct metal–metal oxide interfaces – platinum-silica and cerium oxide-platinum. These two interfaces were then used to catalyze two separate and sequential reactions. First, the cerium oxide-platinum interface catalyzed methanol to produce carbon monoxide and hydrogen. These products then underwent ethylene hydroformylation through a reaction catalyzed by the platinum-silica interface. The final result of this tandem catalysis was propanal.

"The cubic shape of the nanocrystal layers is ideal for assembling metal–metal oxide interfaces with large contact areas," Yang says. "Integrating binary nanocrystals to form highly ordered superlattices is a new and highly effective way to form multiple interfaces with new functionalities."

Yang says that the concept of tandem catalysis through multiple interface design that he and his co-authors have developed should be especially valuable for applications in which multiple sequential reactions are required to produce chemicals in a highly active and selective manner. A prime example is artificial photosynthesis, the effort to capture energy from the sun and transform it into electricity or chemical fuels. To this end, Yang leads the Berkeley component of the Joint Center for Artificial Photosynthesis, a new Energy Innovation Hub created by the U.S. Department of Energy that partners Berkeley Lab with the California Institute of Technology (Caltech).

"Artificial photosynthesis typically involves multiple chemical reactions in a sequential manner, including, for example, water reduction and oxidation, and carbon dioxide reduction," says Yang. "Our tandem catalysis approach should also be relevant to photoelectrochemical reactions, such as solar water splitting, again where sequential, multiple reaction steps are necessary. For this, however, we will need to explore new metal oxide or other semiconductor supports, such as titanium dioxide, in our catalyst design."

Source: PhysOrg

 
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