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May 28th, 2013

Other materials stories that may be of interest

Published on May 28th, 2013 | By: Eileen De Guire

Discovery by U. Arkansas physicists furthers understanding of superconductivity, show Zhang-Rice singlet state in different class of materials

Physicists at the University of Arkansas have collaborated with scientists in the United States and Asia to discover that a crucial ingredient of high-temperature superconductivity could be found in an entirely different class of materials. “The recent finding by the University of Arkansas-led team is important to further understand superconductivity,” says Jak Chakhalian, professor of physics at the UA. Derek Meyers, a doctoral student in physics at UA, found that the way electrons form in superconductive material—known as the Zhang-Rice singlet state—is present in a chemical compound that is very different from conventional superconductors. “There is now a whole different class of materials where you can search for the enigmatic superconductivity. This is completely new because we know that the Zhang-Rice quantum state, which used to be the hallmark of this high-temperature superconductor, could be found in totally different crystal structures. Does it have a potential to become a novel superconductor? We don’t know but it has all the right ingredients. I can make a closed circuit out of the superconducting material, cool it down and attach a battery that starts the flow of the electrons. The current goes around the loop. Then I detach it and leave it. Hypothetically, 1 billion years later the flow of electrons is guaranteed to be exactly the same – with no losses. But the problem is we don’t know if we are even using it right. We have no microscopic understanding of what is behind it,” Chakhalian says.

New filtration material could make petroleum refining cheaper, more efficient

A newly synthesized material might provide a dramatically improved method for separating the highest-octane components of gasoline. Measurements at NIST have clarified why. Created in the laboratory of Jeffrey Long, professor of chemistry at the University of California, Berkeley, the material is a metal-organic framework, or MOF, which can be imagined as a sponge with microscopic holes. The innumerable interior walls of the MOF form triangular channels that selectively trap only the lower-octane components based on their shape, separating them easily from the higher-octane molecules in a way that could prove far less expensive than the industry’s current method. High-octane gasolines, the ultra or premium blends at fueling stations, are more expensive than regular unleaded gasoline due to the difficulty of separating out the right type of molecules from petroleum. Petroleum includes several slightly different versions of the same molecule that have identical molecular formulae but varying shapes-called isomers. Creating premium fuel requires a refinery to boil the mixture at precise temperatures to separate the isomers with the most chemical energy. The trouble is, four of these isomers-two of which are high octane, the other two far lower-have only slightly different boiling points, making the overall process both challenging and costly.

Colorfast pigments made from amorphous arrays of SiO2 and carbon black

It is very annoying when colors fade over time, sometimes simply from exposure to light. In the journal Angewandte Chemie, Japanese scientists have now introduced a new type of colorfast, environmentally friendly pigment. These consist of submicrometer-sized silicon dioxide particles and carbon black and are simply sprayed on to the desire surface. The resulting color is tough and does not fade. Organic dyes fade when exposed to UV light. Inorganic pigments do not fade but are often based on toxic heavy metals such as chromium. In contrast, Yukikazu Takeoka, Shinya Yoshioka and their co-workers at the Universities of Nagoya and Osaka selected silicon dioxide as the basis for their novel pigments. Submicrometer-sized SiO2 particles look white to the human eye, so where does the color come from? Conventional pigments absorb some portion of visible light; the reflected portions then combine to produce a certain color. A different type of color generation, known as structural color, is broadly found in nature, for example among butterflies: Arrays of very small particles can also appear colored without absorption by causing wavelength-dependent optical interference, refraction, and light scattering. The color depends of the particle size.

X-ray techniques to peek into nanoparticle synthesis

The performance of devices in energy and environment systems can be dramatically improved with the implementation of nanotechnology. For that, it is critical to efficiently synthesize nanoparticles. In particular, it is important to understand the changes in the properties of nanoparticles during the synthesis process. The production of nanoparticles of specific shapes doesn’t often allow good control over resulting materials as it is difficult to follow their evolution. Several techniques have attempted to deal with this task in recent years. Synchrotron hard X-rays show strong penetration in ambient environment and solutions, and are promising probes for solution-phase reactions. Authors Yugang Sun and Yang Ren from the Argonne National Laboratory review the advantages and disadvantages of the available X-ray techniques for testing of the synthesis of colloidal nanoparticles in real-time within liquid media. The review points [to] in situ X-ray scattering as the most encouraging palette of probing methods and emphasizes its versatility: how these techniques can also be applied to the study of the nanophase evolution of nanomaterials in diverse energy devices.

Thinking big to think small: US Nanoscale Science Research Centers

A new special issue of Advanced Functional Materials entitled “Scanning Probe Microscopy in US Department of Energy Nanoscale Research Centers: Status, Perspectives, and Opportunities,” is guest-edited by ACerS member Sergei Kalinin of Oak Ridge National Labs. The special issue not only provides an overview of SPM activities at the five centers, but also represents an invaluable contribution to the whole SPM research field. The operational model of the Nanoscale Science Research Centers (NSRCs) generally combines an external user program with an in-house research program and instrument development. This system of give and take allows the retention of skilled staff, the development of new commercially available instruments and dissemination of knowledge into the broader scientific community. Kalinin has assembled feature article contributions from amongst the NSRCs to give an overview of recent developments and the different focuses of the SPM program at the five research centers.

Glove shows its true colors: Textile identifies poisonous substances, and points them out immediately

Employees in chemical production, the semiconductor industry or in laboratories are frequently exposed to harmful substances. The problem: Many of these aggressive substances are imperceptible to human senses, which makes handling them so risky. That’s why there is a broad range of solutions that employers can use to protect their staff from hazardous substances —from highly sensitive measuring equipment to heat imaging cameras. Now, researchers at the Fraunhofer Research Institution for Modular Solid State Technologies EMFT have engineered a glove that recognizes if toxic substances are present in the surrounding air. The protective glove is equipped with custom-made sensor materials and indicates the presence of toxic substances by changing colors. Scientists adapted the materials to the corresponding analytes, and thus, the application. The color change—from colorless (no toxic substance) to blue (toxic substance detected), for example—warns the employee immediately. “By synthesizing the adapted color sensor materials, we can detect gases like carbon monoxide, for example, or hydrogen sulfide. Still, this protective gear represents only one potential area of application. Sensor materials could also be deployed for the quick detection of leaks in gas lines,” explains Sabine Trupp, head of the Fraunhofer EMFT Sensor Materials group.

3D printing: food in space

NASA and a Texas company are exploring the possibility of using a 3D printer on deep space missions in a way where the “D” would stand for dining. NASA has awarded a Small Business Innovation Research Phase I contract to Systems and Materials Research Consultancy of Austin, Texas to study the feasibility of using additive manufacturing, better known as 3D printing, for making food in space. Systems and Materials Research Consultancy will conduct a study for the development of a 3D printed food system for long duration space missions. Phase I SBIR proposals are very early stage concepts that may or may not mature into actual systems. This food printing technology may result in a phase II study, which still will be several years from being tested on an actual space flight. As NASA ventures farther into space, whether redirecting an asteroid or sending astronauts to Mars, the agency will need to make improvements in life support systems, including how to feed the crew during those long deep space missions. NASA’s Advanced Food Technology program is interested in developing methods that will provide food to meet safety, acceptability, variety, and nutritional stability requirements for long exploration missions, while using the least amount of spacecraft resources and crew time. The current food system wouldn’t meet the nutritional needs and five-year shelf life required for a mission to Mars or other long duration missions. Because refrigeration and freezing require significant spacecraft resources, current NASA provisions consist solely of individually prepackaged shelf stable foods, processed with technologies that degrade the micronutrients in the foods.


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