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Imaging Gene Expression

FWP/Project Description: 

Project Leader(s): Marit Nilsen-Hamilton

Principal Investigators: George Kraus

 

We are developing apatmers to use as cellular receptors for imaging gene expression in a technology termed Gene expression measurement by Revealed Aptamer Based Imaging Technology (GRABIT) that includes two approaches using aptamers to image gene expression:  (i) Intracellular Multiaptamer Genetic tags (IMAGEtags), which are aptamer expressing reporter genes, and (ii) Targeted Reversibly Attenuated Probes (TRAPS), which are allosterically regulated aptamer probes.  These RNA probes are being developed for imaging in plants and bacterial species.  

This research is supported by the U.S. Department of Energy, Office of Biological and Environmental Research through the Ames Laboratory.  The Ames Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract No. DE-AC02-07CH11358

Nanotwinned Materials for Energy Technologies

FWP/Project Description: 
Nanotwinned metals and alloys are emerging as a particular form of nanoscaled material that can exhibit high strength coupled with improved thermal stability, both of which are yet unexplained. We have developed an integrated experimental, modeling and simulation program to examine the underlying mechanisms of plasticity in nanotwinned samples. We employ a range of methods to create systems with differing twin morphologies and microstructures and characterize their structures using a range of techniques, from electron microscopy to synchrotron scattering to the use of an atom probe.  Mechanical testing of these samples is carried out in a novel tensile strain stage that enables accurate measurements of stress-strain behavior with concurrent in situ transmission electron microscopy (TEM) observations of evolving microstructures.  We will also use a temperature-controlled nanoindentor to characterize the thermal dependence of the mechanical properties.   The experiments are coupled with a modeling and simulation program that includes atomistics, dislocation dynamics and polycrystal plasticity simulations. The experiments provide both realistic validation of models and a deeper understanding of fundamental mechanisms, enhancing the development of new understandings of deformation in nanotwinned materials.  This program will not only shed new light on plasticity in nanotwinned materials by bridging the current gap between the experiments and modeling, but it will also greatly enhance our overall understanding of many collective and cooperative mechanisms of plasticity in these materials.

This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

Early Career: Emergent Atomic and Magnetic Structures

FWP/Project Description: 
Determining the nature of the macromolecule-mediated magnetic nanoparticle formation:

Uniform magnetic nanoparticles with large magnetic moment and controlled magnetic anisotropy have important technological applications from data storage and quantum computing to catalysis and drug delivery.  The Emergent Magnetic and Atomic Structures Group works to determine the nature of macromolecule‐mediated magnetic nanoparticle formation: i.e., the mechanism of particle nucleationand growth, the emergence of crystal structures, and the development of ferromagnetism in the individual bio‐templated magnetic nanocrystals. By utilizing advanced electron microscopy techniques, we work towards gaining a better understanding of how the assembly of biomacromolecules dictates nanoparticle formation and functional properties.

Correlative electron microscopy of magnetotactic bacteria in liquid:

Magnetotactic bacteria biomineralize ordered chains of uniform magnetite or greigite magnetosome nanocrystals with nearly perfect crystal structures and species-specific morphologies. As a result, these microorganisms are one of the best model systems for investigating the molecular mechanisms of biomineralization. Using the liquid cell scanning transmission electron microscopy (STEM) holder, we can image biomineralizing microorganisms in their natural environment with nanometer resolution. This correlative fluid cell STEM and fluorescence microscopy technique is a first step in directly observing biomineralization of magnetite in viable magnetotactic bacteria. We expect this technique to be generally applicable for in vivo imaging of a wide range of biomineralizing organisms.

Tuning the bacterial iron biomineralization:

Iron is biomineralized by many different microorganisms, and tweaking this process exerts control over the magnetic properties of biogenic materials. Biomioneralization can be controlled to yield nanocrystals with tunable composition and magnetic properties. Comprehensive characterization of biominerals reveals the key factors affecting bacterial iron biomineralization.

Equipment:

  • Continuous fluid flow Cell Holder Platform, equipped with a turbopumping station (Hummingbird Scientific) and digital camera (Leica)
  • Vapor Delivery system Module for use with the continuous fluid flow liquid cell holder(Hummingbird Scientific)
  • Nano eNabler Molecular Printer (BioForce Nanosciences)
  • Magnetherm V 1.5 AC system (Nanotherics), equipped with a fiber optic thermometer
  • Auxiliary equipment: oven; vacuum oven; stand-alone portable RGA module (Stanford Research); controlled temperature circulation bath; Gatan 626 TEM cryo-holder and fully equipped Cryo-Plunger Vitribot (Gatan); glow discharge unit (Pelco); 2 ozone plasma cleaners (BioForce); Midmark 11autoclave sterilizer (Ritter); Shlenk line, glovebox (Vac. Atm.) equipped with a cold storage box and solvent trap; acrylic glovebox unit for cell assembly under argon flow equipped with Leica camera setup unit; two laminar flow hoods; centrifuge and microcentrifuge; direct Immersion ultrasonic horn apparatus (Sonics and Materials)miscellaneous other devices making researchers’ lives a bit easier.

Replacing Critical Rare Earth Materials in High Energy Density Magnets

FWP/Project Description: 
Project Leader(s):
 
Principal Investigators:
Vladimir Antropov, Karl Gschneidner, Jr., Duane Johnson, Matthew Kramer, R. William McCallum, Vitalij Pecharsky

This project will develop Cerium transition-metal (Ce–TM) based permanent magnets for vehicle and wind energy applications.  The abundance of Ce (~50% of the rare-earth (RE) content of Molycorp Bastnasite concentrate) is three times that of Nd and Pr combined.  Due to an excess of Ce on the market, the development of a Ce–TM permanent magnet would facilitate an increase of the supply of high-energy rare-earth magnets by a factor of 2 to 3 without requiring additional mining or an increase in the amount of separated RE produced.  The feature that sets RE elements apart from other elements is the fact that the 4f electron shell is being filled in the series from 1 electron in Ce to 2 in Pr, and so on to 14 for Lu, the last rare earth element.  This electron shell has unique magnetic and optical properties.  The RE in a permanent magnet plays a key role due to its 4f electrons; unfortunately, in many intermetallic compounds with Fe and Co, Ce atoms lose their local magnetic properties, significantly decreasing the magnetic ordering (Curie) temperature and the saturation magnetization i.e. the strength of the magnet.  This project will avoid such effects by controlling the intrinsic ferromagnetic properties through intelligent materials design. The performance goal is to develop a Ce-TM based permanent magnet with a Curie temperature in excess of 300°C, a remnant magnetization in excess of 10 kG, and coercivity in excess of 10 kOe.  The project is a combined theoretical and experimental effort to study the potential of Ce intermetallic compounds for use in permanent magnets.

Not the "Best RE Magnet but better then any non-RE Magnet! Exploiting the intrinsic ferromagnetic properties Ce-TM based permanent magnets; we will develop a Ce-TM based permanent magnet for use in automotive electric drive motors and wind turbines.  Using a combined experimental and theoretical approach, we will develop an understanding of the role of valence and hybridization in determining the Curie temperature, magnetization, and anisotropy of Ce-TM alloys.  This will allow us to design nanostructured and aligned hard/semi-hard magnetic alloys with properties suitable for permanent magnet applications and to produce magnets based on those alloys.

A critical benefit of the alternative Ce-TM-based materials will be to provide a market for Ce that is currently under utilized.  The development of a high magnetic energy density Ce–TM – based permanent magnet would facilitate an increase of the supply of high-energy rare-earth magnets by a factor of 2 to 3 without requiring additional mining or an increase of RE processing.  The effective utilization of the available Ce will drastically alter the economics of rare earth production by effectively doubling the marketable product without incurring additional costs.

 This project targets proposes to reduce the content of critical rare earth elements in traction motors to <0.33g/kW. The collaborations with General Motors and NovTorque provide the evaluation of the material  for traction motors with a specific power greater than 1.9 kW/Kg. Molycorp, LLC will provide the important materials supply chain and development path for commercialization of these materials.

 

Development of MnBi/Al Based Permanent Magnet with 40 MGOe at 200C

FWP/Project Description: 

Matthew Kramer, Ames Laboratory materials scientist, is teaming with scientists at Pacific Northwest National Laboratory (PNNL) to develop a new material based on manganese as a rare-earth free alternative to rare-earth permanent magnets. These manganese composite magnets hold the potential to double magnetic strength relative to current magnets while using raw 

Kramer says Ames Lab’s part of the project will take advantage of the Lab’s expertise in computational materials science.  As he explains it, one of the major obstacles to coming up with any new alloy is finding a quicker approach to looking at new materials. Kramer hopes to speed up the process of developing new alloys by using computational tools to guide materials selection.  He says the laboratory’s suite of computational tools allows scientists to begin doing “what if” scenarios much more effectively than in the past, both in terms of accuracy and the complexity of the materials being analyzed.  “By using computers to do materials search, we hope to short-circuit the traditional Edisonian process, which consists of going into the lab, trying a couple of ideas, measuring a few things and, if finding that doesn’t work, going back and doing it again,” he says. 

 

In addition to Kramer, two other Ames Lab scientists, Duane Johnson, Chief Research Officer and research scientist, and Vladimir Antropov, research scientist, will be investigating “density function theory codes,” which will allow them to quickly assess the key chemistries and structures in the new alloys. These computer codes will allow scientists to do different substitutions within the element’s structures.  By understanding this, Kramer says “scientists can focus on improvements that can be made to the alloy’s composition that will provide the biggest boost to its magnetic properties, which is critical to the success of the project.”

Other partners in the ARPA-E project include Electron Energy Corp, United Technologies Research Center, the University of Maryland and the University of Texas at Arlington. The partners will be doing things like materials synthesis, combinatorial synthesis and materials processing.  The Ames Laboratory portion of the overall $2.3 million project will be approximately $500,000. 

If successful, the manganese composite magnets could reduce U.S. dependence on expensive rare-earth material imports and reduce the cost and improve the efficiency of green-energy applications, such as wind turbines and electric vehicles.

In 2011, the DOE awarded $156 million to ARPA-E for 60 different high-risk / high reward research project related to renewable power, energy efficiency, and national energy security. The projects focus on acceleration of innovations in clean technology, while increasing competitiveness in areas such as rare-earth alternatives and breakthroughs in biofuels, thermal storage, electric grid control and solar power electronics. Projects selected are in 25 states.

 
 

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