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MRS Meeting Scene
Day 5 - Thursday, November 29, 2006
Daily dispatch from Boston. Bringing you the very best of MRS.
The 2006 MRS Fall Meeting reached its penultimate day on Thursday. This was again a full day of talks, the fourth day of posters and the final day of the exhibit. One of the highlights of the day was the first MRS scientific film festival.
Symposium X - Frontiers of Materials Research
MRS Scientific Film Festival
The Materials Research Society inaugural materials film festival announced winners of the top three films in two categories: amateur and professional. Voting was done during the week of the meeting by meeting attendees. The announcements and viewing of the winning films were held as part of Symposium X on Thursday, November 30.
Amateur Category
1st place:
"Gecko — On Shape and Function of Gecko Foot-Hair", by Jose Berengueres, Tokyo Institute of Technology
2nd place:
"Muscular Thin Films: Biohybrid Materials for Soft Robotics" by Adam Walter Feinberg, Harvard University
3rd place:
"Material Combat", by Jonathan Lee Hollander, University of Cambridge
Professional Category
1st place:
"Get Perpendicular" by Zvonimir Bandic, Hitachi Research
2nd place:
"When Things Get Small" by Ivan Kohn Schuller, University of California, San Diego
3rd place:
"Stretchable Silicon", by Alex Jerez, Beckman Institute, University of Illinois
Poster Awards
D15.17
Far-Field Arrangement of Proteins in a Zero-mode Waveguide for Single Molecule Imaging
Takashi Tanii1, Hironori Sonobe1, Rena Akahori1, Takeo Miyake1, Taro Ueno2, Takashi Funatsu2, Naonobu Shimamoto1 and Iwao Ohdomari1; 1School of Sci. & Eng., Waseda University, Tokyo, Japan; 2Graduate School of Parmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
K10.1
Ferromagnetic Ordering at Room Temperature in Co:ZnO Nanoparticles
Sujeet Chaudhary , Kanwalpreet Bhatti, Shankhamala Kundu, Subhash C Kashyap and Dinesh K Pandya; Thin Film Laboratory, Department of Physics, Indian Institute of Technology, New Delhi 110 016, India.
Technical Presentations - A Sampling
Symposium KK
Imaging Magnetic Nanocrystals in Bacteria using Electron Holography and Tomography
Magnetotactic bacteria are aquatic bacterial species that orient and migrate along geomagnetic field lines. This behavior has been traced to the presence of intracellular ferrimagnetic nanosized mineral grains of magnetite (Fe3O4, Iron Oxide) or greigite (Fe3S4, iron sulfide). Different strains of bacteria have different crystal sizes, shapes and arrangements. In his presentation in symposium KK (9.3), Rafal Dunin-Borkowski of the University of Cambridge, United Kingdom, presented a study of the magnetic microstructures, chemical compositions, and three-dimensional morphologies and positions of iron oxide and iron sulfide crystals in air-dried cells of magnetotactic bacteria. The researchers used electron holography and tomography primarily along with other transmission electron microscopy techniques including energy-filtered imaging, selected-area electron diffraction, and high-resolution imaging to characterize the specimens.
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Magnetic induction map recorded using off-axis electron holography from two pairs of magnetite chains from a bacterial cell collected in Veszprém, Hungary. The contours show the strength and direction of the in-plane component of the magnetic induction in the specimen integrated in the electron beam direction. The contour spacing is 0.25 radians.Acknowledgments: Ed Simpson, Takeshi Kasama, Mihaly Posfai, Peter Buseck, Richard Harrison, Rafal Dunin-Borkowski
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Various Parameters such as magnetic moments and coercive fields for individual magnetosomes and entire magnetosome chains could be obtained using these techniques. In the greigite containing bacteria for example, individual 30-40 nm crystals could be easily and cleanly imaged. The study overall resulted in a better understanding of the function of magnetotaxis in bacteria. Dunin-Borkowski also mentioned a related interesting application of the methods used in this study, showing that magnetite can be measured in higher organisms as well. In neuro-diseases such as Alzheimers in humans, magnetite builds up in the brain cells as plaque core material. The methods used in this study can be qualitatively and quantitatively used to determined this buildup of magnetite leading to better diagnosis of the disease.
Symposium D
Electric Field Induced Attachment of Proteins Monitored by Surface Plasmon Resonance
David Mckenzie and his colleagues at the University of Sydney are attempting to increase the functional activity of proteins bound to surfaces by applying electric fields to increase the density of bound proteins and optimize their orientation. Their goal is to produce improved bisosensor surfaces, which typically use an attached protein, antibody, or enzyme to bond with a target analyte in solution. Another possible application is surfaces for biofuel cells. Ideally, researchers would like to be able to bind a protein, antibody, or enzyme in high density at a chosen location on a surface and with the desired orientation. They want to be able to quantify the degree of such surface attachments, and would like the attached molecules to remain functional for a long time. Strong covalent bonds to the surface are preferred.
McKenzie used a surface plasmon resonance (SPR) cell for adsorption studies of horseradish peroxidase in an electric filed. By applying an electric field below the level at which electrophoresis would occur, he was able to increase the concentration of horseradish peroxidase near the substrate to a small extent. Further experiments using ellipsometric SPR (ESPR), which provides data on both the amplitude and phase of light reflected from the substrate surface, proved to be more successful. The researchers were able to monitor the kinetics of adsorption of soybean peroxidase by cycling the applied voltage between -2V and +2V. Successive cycles produced quantitative increases in soybean peroxidase attachment along with selective orientation of the molecule on the surface. This could suggest a pathway to better biosensors with higher concentrations of detector molecules on the electrode surface.
DNA, Proteins, and Neurons Coupled to Electronic Devices
Bioelectronics involves the melding of biology with micro- and nano-electronics. Such devices might be used for biological sensing, the development of biological algorithms for information processing systems, and possibly for therapeutic devices. Andreas Offenhausser demonstrated the effectiveness of coupling DNA with a field effect transistor (FET) to detect single nucleotide polymorphisms (SNPs) in DNA. An SNP is a variation in a single nucleotide of a DNA chain that may be responsible for some disease states. But detection of a deviant single nucleotide is not easy. A probe DNA strand with a known nucleotide sequence was covalently bonded to the electrode surface, followed by a target DNA strand to be analyzed. Using an FET in impedimetric mode, Offenhausser's group was able to differentiate between a target strand that was a perfect match for the probe strand, a target strand with one nucleotide mismatch, and a target strand with two nucleotide mismatches. Thus, the impedimetric FET system can act as a sensitive detector of polymorphisms in DNA strands.
The researchers also attempted to build neuroelectronic hybrid systems to connect neurons to electronic devices. The challenges involved transferring signal from the electronic system to the neurons and back again along a suitable wiring path. They placed neurons on top of metal electrode arrays and applied a voltage to the array, which resulted in stimulation of the neurons. The task of transferring a signal from the neurons back to the gate of an FET in the electronic system depends on how the neuron is sitting on the site—the ratio of free neuron membrane to attached neuron membrane is important. The transfer function of a transistor showed a clear difference depending upon whether or not a neuron was sitting on it. Fluctuations in the transfer function output with time even showed how the neuron moved; the changing ratio of free-to-attached neuron membrane as the neuron bent and stretched caused the signal to fluctuate. Furthermore, neuron cells in solution on a nanopatterned microelectrode exhibited measurable electronic signals as calcium transferred in an out of the cell membrane. This preliminary success with interfacing neurons and microelectronic devices is a hopeful sign for the future of this important endeavor.
Symposium I
Characterization of Strain, Tilt, and Dislocations in Nitride Thin Films
Carol Trager-Cowan of Strathclyde University, Scotland, in her talk on Wednesday, described the use of Electron Backscatter Diffraction (EBSD) as a tool for measuring tilt and rotation in thin films of gallium nitride layers grown on various substrates (SiC, MgO, ZnO, LiAlO2, LiGaO2, MgAl2O4, NiAl, GaP, and Si) with a precision of 2E-4. The technique can also reveal the nature of dislocations in nitride thin films, estimate their density, and reveal atomic steps in nitride thin films. Dislocation densities as a function of thickness can also be determined. Orientation changes of the order of 0.1 degrees can be resolved. For the future, she would like to use electron channeling contrast imaging to identify all the dislocations in nitride thin films and, with cathodoluminescence, to study quenching effects on luminescence in nitrides.
Symposium J
Low Effective Work Function of Nitrogen-Doped Diamond Films
Bob Nemanich (previously at North Carolina State University and now at Arizona State University) described how diamond could be used as a device to directly convert heat into electricity. Using hydrogen treatment of the diamond surface a low work function of 1.4eV has been achieved and this decreases with temperature. A thermionic conversion device has been fabricated that operates up to 600 degrees centigrade with an open circuit voltage of 0.4 volts which is sufficiently high to allow combination of the devices without expensive interconnection techniques. Validation of the UV photo- and thermionic-emission spectroscopy was achieved by showing the similarity between the diamond device and dysprosium metal with a similar (2.4eV) work function.
Symposium V
Technology Development and Integration Challenges with Pb-Free Solder Interconnects
In his talk in symposium V on Wednesday, Ravi Mahajan, of Intel, reported how lead-free techniques for packaging have had a significant effect on both technical and business issues. Lead free technology combined with copper interconnects and low K dielectric makes silicon circuit fabrication and package and board integration more complex. Integration requires a reduction in the inner layer stress to avoid die, passivation, substrate, underfill, and dielectric cracking, and interconnect solder fatigue. Risk areas for lead-free technology include brittle fracture, solder fatigue, creep, vibration, brittle fracture, and pad cratering. These risks are different for mobile and handheld, desktop, and servers. Reliability drives a need for alternative alloys, and reducing the amount of silver in the alloy can improve the interface toughness by increasing the bulk compliance and increasing the plastic energy dissipation.
Symposium DD
Bio-inspired Design of Functionally Graded Dental Multilayers
Dentists report that 80% of all crowns fail by subsurface cracking as opposed to surface cone cracking. This is not true for real teeth. The difference may be that real teeth have a dentin-enamel junction (DEJ) that has a linear stiffness gradient throughout its depth, whereas a crown is held on by an epoxy layer with no gradient in stiffness. Indentation tests performed by Nima Rahbar at Princeton University showed that the maximum principal stress on a crown was in the epoxy layer. He modeled a functionally graded material (FGM) made of epoxy and zirconia in layers designed to produce a stiffness gradation similar to that of the DEJ, and found that an exponential gradation of stiffness reduced the principal stress on the FGM epoxy layer. In trying to test the model experimentally, Rahbar had to use epoxy, zirconia, and alumina to produce the desired gradation. With further work, such bio-inspired interface layers may help to reduce the incidence of subsurface cracking in dental crowns.
Symposium QQ
Hydrogen Storage in Microporous Coordination Solids with Exposed Metal Sites
Future hydrogen-powered automobiles will need to store 5 kilograms of hydrogen to be able to travel distances comparable to gasoline-powered cars. The DOE has set a target for 2010 of storage of hydrogen at a gravimetric capacity of 6 wt.%. Jeffrey Long and his colleagues at the University of California, Berkeley, looked to metal-organic framework materials, which have surface areas as high as 8,000 m2/ g, for a hydrogen storage solution. Their work was based on previous research done by Yaghi et al. in synthesizing the metal-organic material Zn4O(1, 4-benzenedicarboxylate)3, also known as Zn4O(BDC)3. While this material is capable of adsorbing only 1 wt.% of hydrogen at 1 atmosphere pressure, they thought that substitution of other transition metals for Zn with greater hydrogen affinity might lead to an increase in storage capacity. Theoretical analysis showed that substitution of Mg2+ for Zn2+ could lead to a storage capacity as high as 9 wt.% hydrogen. But synthesis and testing of an Mg tetrazole transition metal framework with a formula of Mg4O(ptrz)6 showed that most of the Mg ions in the structure were solvated and therefore unavailable for hydrogen adsorption. Attempts to desolvate the Mg ions through solvate substitution and heating in a vacuum freed up a fraction of the Mg ions for hydrogen adsorption, but not enough to make this a practical solution. The researchers are now looking at sodalite-type frameworks and other transition metals with a lower solvation tendency as possible hydrogen storage materials.
Hydrogen Fuel Cell Model Car Challenge
The winning teams of the hydrogen fuel cell model car challenge held on Monday are:
US Department of Energy Session
Informal Session for Early-Career Investigators
At the Department of Energy (DOE) session for early-career investigators, program director Bonnie Gersten gave a quick overview on how the grant proposal process works. She went through the steps of the submission  process, then the review process. While DOE has a rolling submission process, Gersten said that the best time to submit is between June through November. Interested researchers can sign up for email alerts and proposal solicitations. Following the quick overview, six program directors within the Materials Sciences and Engineering Division of the DOE Office of Basic Energy Sciences led break-out sessions so that attendees could discuss in more detail the grant opportunities in their specific area of research. Gersten is the program director of synthesis and processing science; Tim Fitzsimmons covered the programs of composition and structure and of x-ray and neutron scattering; John Vetrano and Yok Chen covered mechanical behavior and radiation effect; Arvind Kini, materials chemistry and biomolecular materials; and Refik Kortan, physical behavior of materials and experimental condensed matter physics. Harriet Kung, director of the Materials Sciences and Engineering Division, introduced the session.
Funding Opportunities
Immediately following the DOE session for early-career investigators was a seminar in  which Kung described the overall mission and materials funding opportunities in her division. The Office of Basic Energy Sciences has been holding workshops to determine grand challenge research areas. Key areas of research include, for example, materials under extreme environments, and superconductivity, and materials design, synthesis, and discovery. DOE's research interests also include the development of new science-based tools and techniques. Kung's division supports idea-driven research in which researchers focus on fundamental new understanding of materials systems that may be only peripheral or unconnected to current energy needs. Funding is also available for “use-inspired research,” supporting fundamental new understanding of materials and systems to overcome short-term technology showstoppers. With a significant increase in funding requested for FY2007, Kung's division wants an increase both in proposals received and projects funded.
Materials Research Support at the Department of Defense
Representatives of the materials science research funding divisions of the United States Army, Navy and Air Force detailed their research needs in a lively, and sometimes surprising, series of presentations. They were introduced by Alan Hurd of Los Alamos National Laboratories, the next President of the MRS.
Joan Fuller of the Air Force Office of Scientific Research (AFOSR) started the session by stating, “If it has structure and rises above the ground” then it's our responsibility. The agency has a current budget of $22 million for structural materials research. Time-critical missions are driving trends in aerospace hardware, according to Fuller. “The Air Force wants to go fast—Mach 6,” Fuller said. That's fast enough to get from “ Kansas to Kosovo in six hours.” The agency's main need is for high temperature refractory materials to handle the temperature generated at such high speeds, and it also would like those materials to be lightweight, if possible—a challenge for any materials researcher. Fuller also mentioned the need for high temperature piezoelectric ceramics, just to pick an example from a long wish list. The AFOSR relies on its Broad Agency Announcements (BAA) to let researchers know when it is looking for proposals; a BAA on “Thermal Transport Phenomena and Scaling Laws” will be issued soon. More details can be found at www.afosr.af.mil.
Next, David M. Stepp of the Army Research Office (ARO) surprised the audience by saying that the ARO is looking for “unprecedented material properties,” not just incremental improvements in existing systems. As examples, he noted direct-write 3D photonic crystals, artificial frustrated magnets, and reversible electric field dependent adhesion, all of which have been achieved by researchers supported by ARO. Stepp emphasized that he is interested in basic, not applied research; his goal is to provide for the soldier of 2031, so that leaves time for today's basic research to make into the field on schedule. One new funding program in the agency's arsenal is the Short Term Innovation Research (STIR) program, which provides funds of up to $50,000 over nine months to give a researcher a chance to explore whether or not an intriguing idea has real merit. Stepp finished with five pieces of advice for prospective principal investigators:
- Talking to a program manager at the ARO is essential.
- White papers are considered to be working documents. They don't have to be perfect the first time around—a program manager will work with you to refine your ideas if they are of interest.
- Unprecedented material properties are his mission.
- Nanotechnology is not his mission. Big is good. The word “nano” in a white paper or proposal raises a warning flag in his mind.
- “Shotgunning” your proposal to multiple agencies is never your best strategy.
Point 4 in this list was the most surprising statement in Stepp's presentation. More information can be found at www.aro.army.mil .
Finally, Airan J. Perez of the Office of Naval Research (ONR) said the agency has a budget of $30 million for materials science research. The Navy's number one maintenance problem is corrosion, which costs $4.4 billion per year to combat, so mitigating corrosion is high on their research list. They also need faster, more maneuverable ships with extended operating cycles and reduced maintenance requirements. This means lightweight materials (for better maneuverability) with high strength and durability. Materials that contribute to improving a ship's structural survivability, such as a rapid cure, single coating system for enhanced corrosion control, are what the ONR is looking for, according to Perez. Advanced steels, Ti, Al alloys, cellular materials, advanced composites, and new high strain actuators and sensors are just some of the research areas of interest.. And “nano” is OK with the Navy. Visit their website at www.onr.navy.mil for more details.
Erratum
In the "NSF Funding Opportunities in Materials Research" report in the Meeting Scene e-mail sent on Wednesday, November 29, a few corrections are in order. There were over 150 attendees present at the session. DMR funding in 1997 was $185M and the FY07 request is $257.4M. If the FY07 request is allocated, then this would represent a 39% increase over 10 years. The American Competitiveness Initiative articulates the urgent need to do better, and proposes a doubling of the (combined) budgets for NSF, DOE and NIST over the next 10 years.
- Compiled and Edited by Gopal Rao, MRS Web Science Editor with contributions from Tim Palucka, Mike Driver, Judy Meiksin and Betsy Fleischer.
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