Melting in two dimensions is characterized by the thermal excitation and proliferation of free topological defects, disclinations and dislocations which destroy the rigidity of the crystal. This freezing/melting process has been well established for flat systems, but on a sphere, topology requires that there must be a net 12 pentagons (1/2 disclinations) i.e., the 12 pentagons on a soccer ball, and energetically it is favorable to screen the pentagons with strings of dislocations (pentagon-heptagon pairs) known as “scars”. We find that freezing on sphere proceeds by the formation of a single, encompassing, crystalline “continent” that forces the defects into 12 isolated “seas” with icosahedral symmetry.
A series of lectures in modern nanostructural polymer science and it's applications. Please note the dates and times of the individual lectures: Lecture 1: November 7, 12:00 PM “Layered and Fibrillar Polymeric Systems by NanoExtrusion - Forced Assembly”; Lecture 2: November 8, 1:30 PM “New Polymeric NanoSystems - Lessons from Nature and Hierarchical Structures”; and Lecture 3: November 9, 3:00 PM “Applications for New Nanolayered Composites and Membrane Filters”.
Many recent studies have been enabled by the Scanning Transmission Electron Microscope, (STEM) that can produce an Angstrom-sized probe of keV electrons to access both bulk, surface and "aloof" excitations within structures ranging from atomic to molecular to nanoscale in size. I will discuss a little history, some surprising results from my involvment in the field, and speculate on the future potential for this technique.