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Highlights

Highlights

Aug 31, 2011
UPENN Materials Research Science and Engineering Centers

Resistive Switching in Polymer Nanocomposites

Ju Li, Jay Kikkawa and Karen Winey
Aug 31, 2011
UPENN Materials Research Science and Engineering Centers

Colloidal Networks & Lattices at Threshold of Mechanical Stability

Tom Lubensky, Andrea Liu, Arjun Yodh, Shu Yang and Ju Li
An isostatic lattice is one at the threshold of mechanical stability. The square and kagome lattices (see Figure 1a-b) in two dimensions are examples of isostatic lattices. A 2D kagome lattice of N sites has of order N1/2 zero-energy bulk modes under periodic boundary conditions. Theoretical study shows that when neighboring triangles are counter rotated through an arbitrary angle α shown in Figure 1c, the bulk modulus vanishes, making the Poisson's ratio equal to -1, and all of the
Aug 30, 2011
JHU Materials Research Science Engineering Center (2005)

High School Student Research Internships at The Johns Hopkins University
Background: The JHU MRSEC conducts extensive K-12 educational outreach programs aimed at promoting interest in and awareness of the importance of modern materials research. High school students from the greater Baltimore area receive four-week internships each July to conduct research in the laboratories of the JHU MRSEC. The students are mentored by Center faculty, and also work closely
Aug 30, 2011
JHU Materials Research Science Engineering Center (2005)

Dynamics of Magnetic Charges in Spin Ice

P. Mellado, O. Petrova, Y. C. Shen, and O. Tchernyshyov
Background: A bar magnet has two poles, denoted as +1 and -1 magnetic charges.  Patterned structures consist of many magnets (Fig. 1), where the square array (Fig. 1a) does not, whereas the honeycomb (Fig. 1b) has, net magnetic charges (or magnetic monopoles).  Under a magnetic field these local magnetic monopoles will move (Fig. 1c).  This latter structure is called “spin ice”, because it has a large number of nearly degenerate configurations.
Aug 30, 2011
JHU Materials Research Science Engineering Center (2005)

Control of Tetrahedral Coordination in FeSe Superconductors

S. X. Huang, C. L. Chien, V. Thampy, and C. Broholm 
Background: The tetrahedral coordination of Fe surrounded by 4 Se(Te) atoms is of crucial importance for the new high TC Fe pnictides superconductors with lattice parameters c and a. To reveal the essential aspects of the tetrahedron, one needs to vary the lattice parameter c and a in opposite manner, without altering the electronic
Aug 25, 2011
NYU Materials Research Science and Engineering Center (2014)

The Material World

MRSEC faculty investigators: Grier, Kahr, Ward, Chaikin, Kirshenbaum, Braunschweig, and Weck. 
A weeklong materials science workshop series with morning lectures followed by hands-on lab exercises to reinforce concepts for introduction of materials-related content into core science curricula at the home institution Organized and taught by MRSEC faculty investigators Partnership with the Faculty Resource Network at NYU, held during the FRN Network Summer program Content Holographic Video Microscopy Crystals and Light How Stuff Packs Color
Aug 11, 2011

Effective Defects: Strength in Numbers. The surprising strength of highly defective graphene

R. Grantab, V.B. Shenoy and R.S. RuoffBrown University, School of Engineering
Graphene in its pristine form is one of the strongest materials, but defects influence its strenth.  Using atomistic calculations, we find that, counter to standard reasoning, graphene sheets with large-angle tilt boundaries that have a high density of defects are as strong as the pristine material and unexpectedly are much stronger than those with low-angle boundaries having fewer defects.  We show that this trend is not explained by continuum fracture models but can be understood by considering the critical bonds in the strained seven-membered carbon rings that lead to failure; the large-
Aug 11, 2011

Computer-aided design of lightweight allows for future vehicles

William Curtin and Allan Bower, School of Engineering
Replacing steel with lightweight Aluminum alloys could significantly improve fuel economy of vehicles.  Existing lightweight alloys are difficult to use, because they have poor ductility, and tend to tear while they are stamped to form a complex part.  Adding small quantities of additional allying elements to lightweight alloys could improve their ductility.  But at present the only way to identify the correct elements is to make, and test, many possible combinations - an impossible task.
Aug 2, 2011
Genetically Engineered Materials Science and Engineering Center (2005)

Protein-Driven Synthesis of Transition Metal-Doped ZnS Immuno-Quantum Dots

W. Zhou, D. T. Schwartz, & F. Baneyx
Doping semiconductor nanocrystals with transition metals is an efficient route to tune emission color over a broad range of wavelengths. We have developed a simple and environmentally friendly process for protein-aided mineralization of transition metal doped ZnS nanocrystals. Biofabricated ZnS:Mn quantum dots (QDs)
Jul 25, 2011
Cornell Center for Materials Research (2017)

Interacting electron ripples provide clues to superconductivity

A. Mesaros, K. Fujita, H. Eisaki, S. Uchida, J. C. Davis, S. Sachdev, J. Zaanen, M. J. Lawler, E.-A. Kim, Science 333, 426-430 (2011).
  Interacting electron ripples provide clues to superconductivity A theoretical prediction is confirmed by atomic-scale microscopy

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