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Physicists at Brookhaven National Laboratory have identified a single layer responsible for one such material’s ability to become superconducting. The technique, described in the Oct. 30, 2009, issue of Science, could be used to engineer ultrathin films with “tunable” superconductivity for higher-efficiency electronic devices.

The thinner the material (and the higher its transition temperature to a superconductor), the greater its potential for applications where the superconductivity can be controlled by an external electric field. “This type of control is difficult to achieve with thicker films, because an electric field does not penetrate into metals more than a nanometer or so,” explains Brookhaven physicist and the group leader Ivan Bozovic.

To explore the limits of thinness, Bozovic’s group synthesized a series of films based on the high-temperature superconducting cuprates — materials that carry current with no energy loss when cooled below a certain transition temperature. Since zinc is known to suppress the superconductivity in these materials, the scientists systematically substituted a small amount of zinc into each of the copper-oxide layers. Any layer where the zinc’s presence had a suppressing effect would be clearly identified as essential to superconductivity in the film.

This discovery opens a path toward the fabrication of electronic devices with modulated, or tunable, superconducting properties which can be controlled by electric or magnetic fields.

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Lawrence Berkley National Lab has been commissioned to beef up the energy efficiency of several federal agencies. A press release from LBNL states that $1.8 million in funding from the American Recovery and Reinvestment Act will be used to implement advanced technologies in lighting, HVAC and control systems.

“This funding will help implement energy efficiency projects across the federal government and will support training programs for energy managers to ensure the equipment is operating as effectively as possible,” says Arun Majumdar, Director of Berkley Lab’s Environmental Energy Technologies Division. “The Recovery Act funding will also go to developing and delivering advanced energy assessment tools that will provide energy managers with the resources and training to launch additional efficiency improvements in their facilities for years to come.”

The mission is to transfer new energy-efficient building technologies from the laboratory to the real world, and to stimulate the use of underutilized, high-performance technologies through innovative deployment programs.

The following projects will receive technical support from Berkeley Lab:

• Improving efficiency in federal data centers;
• Energy efficiency in Department of Agriculture labs;
• Advanced lighting for the National Institutes of Health; and
• Helping the armed forces be “as Energy-Efficient as They Can Be.”

With $663,000 in DOD funding, EETD researchers will cooperate on a project to test a whole-building monitoring system at two DOD sites. The system will continuously measure the energy performance of the HVAC, lighting and water systems, and compare these measurements in real time to a reference simulation model that represents the design intent for each building.

These types of efforts are could go a long way toward addressing a complaint by energy experts that architects are paying too much attention to design but not enough to ongoing assessment standards, methods and tools.

“Identifying the causes of water and energy waste in buildings can be challenging because energy flows and water usage are largely invisible,” says EETD researcher Philip Haves.

The Army’s Fort Detrick in Maryland will receive an assessment of the viability of supplying all or part of the electric load in selected areas with photovoltaic solar panels.

“We look forward to helping these agencies make the progress on energy efficiency and renewable energy that America needs to address global climate change as well as meeting the goals of the Recovery Act by helping to jumpstart the economy,” says Charles Williams, an energy expert in BNL’s Applications Team.

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In its final round of American Recovery and Reinvestment Act-based awards, the DOE says it is going to provide money for science research projects at 10 federal labs and schools. For the record, this latest announcement brings the total amount of ARRA funding coming out of the DOE to $1.6 billion, all that Congress set aside for the agency under this bill. Of the $327 million, DOE is going to earmark about one-third to universities, nonprofit organizations and private firms, and the rest to DOE’s national labs. In particular, $164.7 million has already been set aside for the following projects:

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Peter Johnson from the Brookhaven National lab explains the basics of high temperature superconductivity and why it can make a profound impact on energy usage and transmission. Yes - it ends somewhat abruptly.

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Mother-of-Pearl

Two different approaches to the creation of materials that could be described as artificial nacre - nacre being that super strong substance produced in nature by some mollusks and something of a Holy Grail pursued by materials scientists - have recently been announced.

First some background on why nacre is so strong, courtesy of the Asian Institute of Gemological Sciences:

Under microscope, nacre is astonishingly orderly. Its layers of complexity, from large to small scale, give it what engineers call a hierarchical structure. A microscopic cross-section looks like brickwork, with flat, hexagonal tablets of a crystalline, calcium carbonate mineral stacked in neat layers. Mortaring them is a flexible, protein-rich gum originally secreted by the shellfish.

Paul Podsiadlo, a protege of renowned Univ. of Michigan material scientist Nicholas Kotov, in late November won the Collegiate Inventors Competition and its $15,000 prize for a new ceramic material he calls “plastic steel.”

Paul Podsiadlo

Podsiadlo created transparent sheets of the new material using clay nanotubes and assembling them together in thin sheets. By adding hundreds of layer, Podsiadlo formed a material that resembles seashell in both strength and appearance

Kotov, who pioneered much of the science behind Podsiadlo’s application, said he hopes the plastic steel will be widely used.

“These composites can be applied in biomedical devices, bone replacements for injuries, military applications such as personal protection, microelectromechanical devices and energy generation and storage,” Kotov said.

Along these same lines, the CIC website reported that

Podsiadlo looks forward to the broad impact his innovation could have, especially in the military, aviation, medical, and energy sectors. He envisions his structure being used for anything from body armor to biomedical coatings. In fact, research for the project was initially funded by the U.S. Defense Department and the National Institutes of Health.

Then on Friday, the Dec. 5, 2008 issue of Science published a study by a group of researchers at the Lawrence Berkeley National Lab reporting that they, too, have been able to create a nacre-like material, according to a LBNL release, “may well be the toughest ceramic ever produced.”

The LBNL group, Robert Ritchie, Etienne Munch, Max Launey, Daan Hein Alsem, Eduardo Saiz and Antoni Tomsia, employed controlled freezing of aqueous suspensions alumina and polymethylmethacrylate (PMMA). They claim they were able to produce ceramics “300 times tougher than their constituent components.”

“We have emulated nature’s toughening mechanisms to make ice-templated alumina hybrids that are comparable in specific strength and toughness to aluminum alloys,” says Ritchie. “We believe these model materials can be used to identify key microstructural features that should guide the future synthesis of bio-inspired, yet non-biological, light-weight structural materials with unique strength and toughness.”

The roughness of the alumina/PMMA hybrid ceramic controls the strength of the interfaces, which is critical in determining the material’s overall toughness as it affects the sliding process in the polymeric "mortar" layers.

In the "brick-and-mortar" phase of the alumina/PMMA hybrid, aragonite "bricks" slide past each other to dissipate strain energy while the polymer "mortar" acts as a lubricant.

The group built on earlier work to develop a strong, bone-like material that utilized the properties of freezing of seawater to form a ceramic that was four times stronger than artificial bone. Seawater freezes in small layers and traps impurities (that are expelled during the freezing process) between the layers of ice.

“Since seawater can freeze like a layered material, we allowed nature to guide the process by which we were able to freeze-cast ceramics that mimicked nacre,” said Tomsia.

Ritchie and the others used a similar technique focusing on alumunia and PMMA to recreate the layer microstructure of nacre. The layering in natural nacre allows mother-of-pearl to disapate stress and dimish the effects of small cracks.

“The key to material toughness is the ability to dissipate strain energy. Infiltrating the spaces between the alumina layers with polymer allows the hard alumina layers to slide (by a small amount) over one another when load is applied, thereby dissipating strain energy. The polymer acts as a lubricant, like the oil in an automobile engine,” said Ritchie.

The BNL group’s next step is to ramp up the material’s load-bearing abilities by increasing the content of alumina and using a different polymer with improved characteristics.

“The polymer is only capable of allowing things to slide past one another, not bear any load. Infiltrating the ceramic layers with metals would give us a lubricant that can also bear some of the load. This would improve strength as well as toughness of the composite,” said Ritchie.

Here is a bonus video about the BNL work:

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