1,206 research outputs found
Goodbye, Mother
https://digitalcommons.library.umaine.edu/mmb-me/1324/thumbnail.jp
Self-Assembly on a Cylinder: A Model System for Understanding the Constraint of Commensurability
A crystal lattice, when confined to the surface of a cylinder, must have a
periodic structure that is commensurate with the cylinder circumference. This
constraint can frustrate the system, leading to oblique crystal lattices or to
structures with a chiral seam known as a "line slip" phase, neither of which
are stable for isotropic particles in equilibrium on flat surfaces. In this
study, we use molecular dynamics simulations to find the steady-state structure
of spherical particles with short-range repulsion and long-range attraction far
below the melting temperature. We vary the range of attraction using the
Lennard-Jones and Morse potentials and find that a shorter-range attraction
favors the line-slip. We develop a simple model based only on geometry and bond
energy to predict when the crystal or line-slip phases should appear, and find
reasonable agreement with the simulations. The simplicity of this model allows
us to understand the influence of the commensurability constraint, an
understanding that might be extended into the more general problem of
self-assembling particles in strongly confined spaces.Comment: 12 pages, 9 figures. Submitted for publication, 201
Determination of the Superconductor-Insulator Phase Diagram for One-Dimensional Wires
We establish the superconductor-insulator phase diagram for quasi-one
dimensional wires by measuring a large set of MoGe nanowires. This diagram is
consistent with the Chakravarty-Schmid-Bulgadaev phase boundary, namely with
the critical resistance being equal to R_Q = h/4e^2. We find that transport
properties of insulating nanowires exhibit a weak Coulomb blockade behavior.Comment: 5 pages, 4 figure
Negishi Coupling of Pteridine-O-sulfonates
Negishi coupling of pteridine-O-sulfonate with Zn-aryls is reported. Hydrolysis of the protecting groups with 1M NH3 gave the 6-subustituted 2,4-diaminopteridine while hydrolysis with 1 M NaOH gave the 6-subsituted pterin.KEYWORDS Pteridine, pterin, Negishi coupling
Back to Childhood\u27s Home and Mother
https://digitalcommons.library.umaine.edu/mmb-vp/4439/thumbnail.jp
Waltz Me Till I\u27m Dreamy
https://digitalcommons.library.umaine.edu/mmb-vp/5557/thumbnail.jp
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