Highlights
Nov 29, 2006
Stanford University
Simulations of Polyphenylacetylene (PPA) "Foldamers". Vijay Pande, Stanford University.
What are PPA “foldamers”
nonbiological polymers that fold
model systems for self-assembling nano structures
challenge for simulation: long timescale and complex dynamics
New results
longer chains considerably are more complex: multiple traps and remarkable complexity
new methods used to predicted long timescale behavior: Markovian model and Folding@Home grid computing
Nov 29, 2006
Toxicity of Citrate/Gold Nanoparticles on Human Dermal Fibroblasts
The nanoscale engineering is one of the most dynamic domains at the interface between electronics, physics, biology and medicine. As there is no regulation yet, concern about future health problems is raising. We have investigated the cytotoxicity of Citrate/Gold nanoparticles at different concentrations and times. Major effects on cells appeared as a result of the internalization of nanoparticles, such as disruption of the actin cytoskeleton, loss of spreading and growth, as well as protein synthesis, and reduction of phagocytosis of bacteria.
Nov 29, 2006
Johns Hopkins University
Asymmetrical Nanorings
The vortex state of a magnetic nanoring has special attributes of no magnetic poles nor stray fields. The circulatory magnetization can have two chiralities:, left-handed or right-handed, for storing "0" and "1", as shown in Fig. 1.
Fig. 1: Two chiralities of a magnetic nanorings for storing "1" and "0".
Nov 29, 2006
Research Highlights Summary
Periodically, the MRSEC posts scientific nuggets, i.e. brief one or two page descriptions of important scientific or technological discoveries and innovative new outreach initiatives which have resulted from NSF or other support. Feel free to explore the ones that we have provided here. The nuggets are in .pdf format.
Nov 29, 2006
University of Colorado at Boulder
Halon Liquid Crystals
Center researchers have found liquid crystal phases in systems of circular or spherical particles, a surprise since liquid crystals usually appear in molecules shaped like sticks or plates. The trick is to give hard particles (purple) a soft repulsive "halo" (green) The resulting phase behavior is extraordinarily rich, including "lyotropic" liquid crystal phases and a variety of complex modulated crystal phases.
Nov 20, 2006
Columbia University in the City of New York
Graphitic Carbon Produced at Very Low Temperatures
Graphitic Carbon Produced at Very Low Temperatures during the Synthesis of Iron Oxide NanoparticlesGraphitic carbon - structural forms of the element that are constructed exclusively from carbon atoms having trigonal planar coordination - is ordinarily produced under drastic physical and conditions, typically at temperatures in excess of 500ï‚° C. Columbia MRSEC scientists have uncovered a process by which this form of matter can assemble at temperatures as low as 110ï‚° C. During their development of a low-temperature synthesis of nanocrystals of iron oxides, Drs.
Nov 17, 2006
Harvard University
Sub-Cellular Nanosurgery in Live Cells
A femtosecond laser is used to perform "nano" surgery on a living cell. The actin filaments in the cell have been fluorescently labeled using green fluorescent protein (GFP). When a single filament is cut, it retracts, much like a violin string that has broken. This demonstrates that the actin filaments in the cell are under tension, and hence are being "pulled" apart.
Nov 16, 2006
University of Minnesota - Twin Cities
Children learn about nanotechnology (MNDaily)
On October 20, 2006, the UMN MRSEC hosted 450 participants from the Minnesota FIRST Lego League “Nanoquest” competition. FIRST Lego League is an organization, which “introduces children around the world to the fun and experience of solving real world problems by applying math, science, and technology”*.
Nov 14, 2006
University of Nebraska - Lincoln
Anisotropic Magnetism in Dilute Magnetic Semiconductors
D. J. Sellmyer and R. Skomski Groups
Magnetocrystalline anisotropy is found in many magnetic materials which means that the energy of a magnet depends on the magnetization direction. This keeps our windshield wipers moving and our toy magnets attached to the fridge. However, on changing the direction of the field that aligns the magnetic moments, the aligned magnetization normally remains nearly unchanged. A strikingly different behavior has been found by researchers at the University of Nebraska MRSEC.
Nov 14, 2006
University of Nebraska - Lincoln
Ballistic Anisotropic Magnetoresistance
E. Tsymbal Group
Anisotropic magnetoresistance (AMR) is the difference in the resistivity of ferromagnetic materials in external magnetic field when the field is applied along or perpendicular to the current. In macroscopic materials the conductance is diffusive (the mean free path of the electron is much smaller than the device dimensions) and AMR is due to spin dependent scattering of impurities. Until recently AMR used to be the primary way of detecting magnetic fields (as in hard-drive read heads).
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