Friday, October 14, 2011

New nanostructure-based process will streamline production of magnetic materials

 Scientists at the University of Massachusetts Amherst report that for the first time they have designed a much simpler method of preparing ordered magnetic materials than ever before, by coupling magnetic properties to nanostructure formation at low temperatures.

The innovative process allows them to create room-temperature ferromagnetic materials that are stable for long periods more effectively and with fewer steps than more complicated existing methods. The approach is outlined by UMass Amherst polymer scientist Gregory Tew and colleagues in the Sept. 27 issue of Nature Communications.

Tew explains that his group's signature improvement is a one-step method to generate ordered magnetic materials based on cobalt nanostructures by encoding a block copolymer with the appropriate chemical information to self-organize into nanoscopic domains. Block copolymers are made up of two or more single-polymer subunits linked by covalent chemical bonds.

The new process delivers magnetic properties to materials upon heating the sample once to a relatively low temperature, about 390 degrees (200 degrees Celsius), which transforms them into room-temperature, fully magnetic materials. Most previous processes required either much higher temperatures or more process steps to achieve the same result, which increases costs, Tew says.

He adds, "The small cobalt particles should not be magnetic at room temperature because they are too small. However, the block copolymer's nanostructure confines them locally which apparently induces stronger magnetic interactions among the particles, yielding room-temperature ferromagnetic materials that have many practical applications."

"Until now, it has not been possible to produce ordered, magnetic materials via block copolymers in a simple process," Tew says. "Current methods require multiple steps just to generate the ordered magnetic materials. They also have limited effectiveness because they may not retain the fidelity of the ordered block copolymer, they can't confine the magnetic materials to one domain of the block copolymer, or they just don't produce strongly magnetic materials. Our process answers all these limitations."

Magnetic materials are used in everything from memory storage devices in our phones and computers to the data strips on debit and credit cards. Tew and colleagues have discovered a way to build block copolymers with the necessary chemical information to self-organize into nanoscopic structures one millionth of a millimeter thin, or about 50,000 times thinner than the average human hair.

Earlier studies have demonstrated that block copolymers can be organized over relatively large areas. What makes the UMass Amherst research group's results so intriguing, Tew says, is the possible coupling of long-range organization with improved magnetic properties. This could translate into lower-cost development of new memory media, giant magneto-resistive devices and futuristic spintronic devices that might include "instant on" computers or computers that require much less power, he points out.

He adds, "Although work remains to be done before new data storage applications are enabled, for example making the magnets harder, our process is highly tunable and therefore amendable to incorporating different types of metal precursors. This result should be interesting to every scientist in nanotechnology because it shows conclusively that nano-confinement leds to completely new properties, in this case room temperature magnetic materials."

"Our work highlights the importance of learning how to control a material's nanostructure. We show that the nanostructure is directly related to an important and practical outcome, that is, the ability to generate room-temperature magnets."

"Our work highlights the importance of learning how to control a material's nanostructure. We show that the nanostructure is directly related to an important and practical outcome, that is, the ability to generate room temperature magnets." As part of this study, the UMass Amherst team also demonstrated that using a block copolymer or nanoscopic material results in a material that is magnetic at room temperature. By contrast, using a homopolymer, or unstructured material, leads only to far less useful non- or partial-magnetic materials.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by University of Massachusetts at Amherst.

Journal Reference:

Zoha M. AL-Badri, Raghavendra R. Maddikeri, Yongping Zha, Hitesh D. Thaker, Priyanka Dobriyal, Raja Shunmugam, Thomas P. Russell, Gregory N. Tew. Room temperature magnetic materials from nanostructured diblock copolymers. Nature Communications, 2011; 2: 482 DOI: 10.1038/ncomms1485

Scientists lay out plans for efficient harvesting of solar energy

 Solar power could be harvested more efficiently and transported over long distances using tiny molecular circuits, according to research inspired by new insights into natural photosynthesis.

Incorporating the latest research into how plants, algae and some bacteria use quantum mechanics to optimise energy production via photosynthesis, scientists have set out how to design molecular "circuitry" that is 10 times smaller than the thinnest electrical wire in computer processors. Published in Nature Chemistry, the report discusses how tiny molecular energy grids could capture, direct, regulate and amplify raw solar energy.

Professor Gregory Scholes, lead author from the University of Toronto said: "Solar fuel production often starts with the energy from light being absorbed by an assembly of molecules. The energy is stored fleetingly as vibrating electrons and then transferred to a suitable reactor.

"It is the same in biological systems. In photosynthesis, for example, antenna complexes composed of chlorophyll capture sunlight and direct the energy to special proteins that help make oxygen and sugars. It is like plugging those proteins (called reaction centres) into a solar power socket."

In natural systems energy from sunlight is captured by 'coloured' molecules called dyes or pigments, but is only stored for a billionth of a second. This leaves little time to route the energy from pigments to the molecular machinery that produces fuel or electricity.

The key to transferring and storing energy very quickly is to harness the collective quantum properties of antennae, which are made up of just a few tens of pigments.

Dr Alexadra Olaya-Castro, co-author of the paper from UCL's department of Physics and Astronomy said: "On a bright sunny day, more than 100 million billion red and blue "coloured" photons strike a leaf each second.

"Under these conditions plants need to be able to both use the energy that is required for growth but also to get rid of excess energy that can be harmful. Transferring energy quickly and in a regulated manner are the two key features of natural light-harvesting systems.

"By assuring that all relevant energy scales involved in the process of energy transfer are more or less similar, natural antennae manage to combine quantum and classical phenomena to guarantee efficient and regulated capture, distribution and storage of the sun's energy."

Summary of lessons from nature about concentrating and distributing solar power with nanoscopic antennae:

The basic components of the antenna are efficient light absorbing molecules. These photo-energy absorbers should be appropriately distributed to guarantee that there is an even probability of converting sun energy into vibrating electrons across the whole antennae.Take advantage of the collective properties of light-absorbing molecules by grouping them close together. This will make them exploit quantum mechanical principles so that the antenna can: i) absorb different colours ii) create energy gradients to favour unidirectional transfer and iii) possibly exploit quantum coherence for energy distribution -several energy transfer pathways can be exploited at once.Make sure that the relevant energy scales involved in the energy transfer process are more or less resonant. This will guarantee that both classical and quantum transfer mechanisms are combined to create regulated and efficient distribution of energy across short and long-range distances when many antennae are connected.An antenna should transfer energy not as fast as possible but as fast as necessary. This means that regulatory mechanisms need to be integrated in the antenna. For instance, if necessary, combine light-absorbing molecules with a few local "sinks" that dissipate excess of damaging energy.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University College London.

Journal Reference:

Gregory D. Scholes, Graham R. Fleming, Alexandra Olaya-Castro, Rienk van Grondelle. Lessons from nature about solar light harvesting. Nature Chemistry, 2011; 3 (10): 763 DOI: 10.1038/nchem.1145

Note: If no author is given, the source is cited instead.

New technique maps twin faces of smallest Janus nanoparticles

 New drug delivery systems, solar cells, industrial catalysts and video displays are among the potential applications of special particles that possess two chemically distinct sides. These particles are named after the two-faced Roman god Janus and their twin chemical faces allow them to form novel structures and new materials.

However, as scientists have reduced the size of Janus particles down to a few nanometers in diameter -- about the size of individual proteins, which has the greatest potential for drug therapy -- their efforts have been hampered because they haven't had a way to accurately map the surfaces of the particles that they produce. This uncertainty has made it difficult to evaluate the effectiveness of these particles for various applications and to improve the methods researchers are using to produce them.

Now, a team of Vanderbilt chemists has overcome this obstacle by developing the first method that can rapidly and accurately map the chemical properties of the smallest of these Janus nanoparticles.

The results, published online this month in the German chemistry journal Angewandte Chemie, address a major obstacle that has slowed the development and application of the smallest Janus nanoparticles.

The fact that Janus particles have two chemically distinct faces makes them potentially more valuable than chemically uniform particles. For example, one face can hold onto drug molecules while the other is coated with linker molecules that bind to the target cells. This advantage is greater when the different surfaces are cleanly separated into hemispheres than when the two types of surfaces are intermixed.

For larger nanoparticles (with sizes above 10 nanometers), researchers can use existing methods, such as scanning electron microscopy, to map their surface composition. This has helped researchers improve their manufacturing methods so they can produce cleanly segregated Janus particles. However, conventional methods do not work at sizes below 10 nanometers.

The Vanderbilt chemists -- Associate Professor David Cliffel, Assistant Professor John McLean, graduate student Kellen Harkness and Lecturer Andrzej Balinski -- took advantage of the capabilities of a state-of-the-art instrument called an ion mobility-mass spectrometer (IM-MS) that can simultaneously identify thousands of individual particles.

The team coated the surfaces of gold nanoparticles ranging in size from two to four nanometers with two different chemical compounds. Then they broke the nanoparticles down into clusters of four gold atoms and ran these fragments through the IM-MS.

Molecules from the two coatings were still attached to the clusters. So, by analyzing the resulting pattern, the chemists showed that they could distinguish between original nanoparticles where the two surface compounds were completely separated, those where they were randomly mixed and those that had an intermediate degree of separation.

"There is no other way to analyze structure at this scale except X-ray crystallography," said Cliffel, "and X-ray crystallography is extremely difficult and can take months to get a single structure."

"IM-MS isn't quite as precise as X-ray crystallography but it is extremely practical," added McLean, who has helped pioneer the new instrument's development. "It can provide structural information in a few seconds. Two years ago a commercial version became available so people who want to use it no longer have to build one for themselves."

The research was funded in part by a grant from the National Institutes of Health.

Story Source:

The above story is reprinted (with editorial adaptations ) from materials provided by Vanderbilt University. The original article was written by David Salisbury.

Journal Reference:

Kellen M. Harkness, Andrzej Balinski, John A. McLean, David E. Cliffel. Nanoscale Phase Segregation of Mixed Thiolates on Gold Nanoparticles. Angewandte Chemie International Edition, 2011; DOI: 10.1002/anie.201102882

Public image of chemistry: Breaking chemistry's bad rap

Breaking Bad, cable channel AMC's popular series chronicling the dark transformation of Walter White from suburban chemistry high school teacher to crystal meth master chef and criminal mastermind, makes chemistry entertaining for the average person through shocking story developments, including White using his chemistry expertise (poison, noxious gas, and acid) to eliminate rival meth slingers.

But the show is not improving chemistry's tarnished public image says Matthew Hartings, assistant professor of chemistry at American University.

"Breaking Bad is an entertaining and truly fantastic show. And, it's amazing how much actual chemistry they weave into each episode. Unfortunately, though, the show plays into our preconceived notions that chemists are mad scientists and that chemicals are bad for you," Hartings said. "This reinforces some people's belief that chemicals are things to be avoided when, in fact, we eat, breathe, sleep, and work in a world of chemicals."

Hartings and Declan Fahy, an assistant professor of communication at AU, coauthored a recent article in the journal Nature Chemistry outlining why, of all the sciences, chemistry has perhaps the worst public image and how chemists can help turn that around through improved communication.

A timely message as 2011, the International Year of Chemistry, has chemists and the chemical industry ramping up their communication efforts to honor chemistry's history and showcase the countless ways chemistry has improved everyday life.


Hartings and Fahy say chemistry's bad rap is a result of "chemophobia," a term coined by chemist and popular science writer Pierre Laszlo referring to the terms most people associate with chemistry: poisons, toxins, chemical warfare, alchemy, sorcery, pollution, and mad scientists.

"One of the reasons that Breaking Bad plays so well is because the public is familiar with the mad scientist/wacky chemist narrative," Hartings said. "What we're not familiar with is all of the other places that chemistry is present in our lives."

Chemophobia is why publishers and television/film production companies avoid using the word "chemistry" in the titles of creative works. They fear that potential consumers will shy away from their products -- some recalling how difficult chemistry might have been in high school and others thinking, "Aren't chemicals bad for you?"

"When Deborah Blum wrote The Poisoner's Handbook, a 2010 book that describes the evolution of forensic science in 1920s America, she suggested the subtitle A True Story of Chemistry, Murder and Jazz Age New York," said Hartings. "But the book's subtitle ended up being Murder and the Birth of Forensic Medicine in Jazz Age New York because the publisher told Blum putting the word 'chemistry' on the book's cover would sink sales."

Five Steps to Improve Chemistry Communication

In their Nature Chemistry article, Hartings and Fahy outline five communication strategies to help chemists increase public engagement with chemistry and improve the field's public image.

Practice research-driven communication. Focus groups, surveys, and interviews can help chemists identify various publics (their attitudes, values, and beliefs) and understand how they get information and form their opinions about chemistry.Understand the audience. Because chemistry is a broad field, it can be relevant to numerous topics (a few examples include pharmaceuticals, renewable energy, and cooking and nutrition) and have numerous audiences.Participate in the new communication landscape. More chemists should use social media, blogs, and online videos to communicate with their peers as well as nonchemists/nonscientists.Tie chemistry to society. Relate chemistry to social issues or broader themes that touch the lives of everyday people.Frame key messages to prompt engagement. Because chemistry is a broad, complex field and can appeal to numerous publics, chemists need to learn frame their messages to encourage public engagement (present a specific issue in a way that shows people the issue's relevancy and application to their lives).

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by American University. The original article was written by Maggie Barrett.

Journal Reference:

Matthew R. Hartings, Declan Fahy. Communicating chemistry for public engagement. Nature Chemistry, 2011; 3 (9): 674 DOI: 10.1038/nchem.1094