On The Banks Of The Old River Lee

https://digitalcommons.library.umaine.edu/mmb-vp/3335/thumbnail.jp

Effects of Microstructure Formation on the Stability of Vapor Deposited Glasses

Glasses formed by physical vapor deposition (PVD) are an interesting new class of materials, exhibiting properties thought to be equivalent to those of glasses aged for thousands of years. Exerting control over the structure and properties of PVD glasses formed with different types of glass-forming molecules is now an emerging challenge. In this work, we study coarse grained models of organic glass formers containing fluorocarbon tails of increasing length, corresponding to an increased tendency to form microstructures. We use simulated PVD to examine how the presence of the microphase separated domains in the supercooled liquid influences the ability to form stable glasses. This model suggests that increasing molecule tail length results in decreased thermodynamic and kinetic stability of the molecules in PVD films. The reduced stability is further linked to the reduced ability of these molecules to equilibrate at the free surface during PVD. We find that as the tail length is increased, the relaxation time near the surface of the supercooled equilibrium liquid films of these molecules are slowed and become essentially bulk-like, due to the segregation of the fluorocarbon tails to the free surface. Surface diffusion is also markedly reduced due to clustering of the molecules at the surface. Based on these results, we propose a trapping mechanism where tails are unable to move between local phase separated domains on the relevant deposition time scales

Patrick J. Walsh Correspondence

Entries include brief biographical information, a typed introductory letter to Walsh concerning the Maine Author Collection and publication notice of his book in an upcoming issue of the Maine Library Bulletin, a handwritten biographical letter of presentation from Walsh on Northern Novelty Company, Monticello, Maine, stationery, and a typed letter on receipt of his book Humor: Informative, Soothing, and Ticklish for the Maine Author Collection from the Maine State Library

A Physics-Aware Dead Reckoning Technique for Entity State Updates in Distributed Interactive Applications

This paper proposes a novel entity state update technique for physics-rich environments in peer-to-peer Distributed Interactive Applications. The proposed technique consists of a dynamic authority scheme for shared objects and a physics-aware dead reckoning model with an adaptive error threshold. The former is employed to place a bound on the overall inconsistency present in shared objects, while the latter is implemented to minimise the instantaneous inconsistency during users’ interactions with shared objects. The performance of the proposed entity state update mechanism is validated using a simulated application

An inactive pool of GSK-3 at the leading edge of growth cones is implicated in Semaphorin 3A signaling

Glycogen synthase kinase (GSK)-3 is a serine/threonine kinase that has been implicated in several aspects in embryonic development and several growth factor signaling cascades. We now report that an inactive phosphorylated pool of the enzyme colocalizes with F-actin in both neuronal and nonneuronal cells. Semaphorin 3A (Sema 3A), a molecule that inhibits axonal growth, activates GSK-3 at the leading edge of neuronal growth cones and in Sema 3A–responsive human breast cancer cells, suggesting that GSK-3 activity might play a role in coupling Sema 3A signaling to changes in cell motility. We show that three different GSK-3 antagonists (LiCl, SB-216763, and SB-415286) can inhibit the growth cone collapse response induced by Sema 3A. These studies reveal a novel compartmentalization of inactive GSK-3 in cells and demonstrate for the first time a requirement for GSK-3 activity in the Sema 3A signal transduction pathway

The Role of Dynamic Ligand Exchange in the Oxidation Chemistry of Cerium(III)

The CeIII/IV couple is useful for many applications in organic, inorganic, and materials chemistry. However, attaining a general method to access both oxidations states through reversible solution redox chemistry remains challenging. Herein we report the synthesis, characterization, and oxidation chemistry of the novel Ce/Li REMB heterochiral diastereomer, 1-Ce(het). The solution exchange processes of 1-RE(het) (RE ¼ Ce and Yb) were investigated to estimate rates of ligand and cation exchange relevant in homochiral and heterochiral frameworks. A detailed mechanistic investigation following the solution dynamics of 1-Ce(het) revealed reactivity controlled both by ligand reorganization and redistribution processes. Ligand reorganization was responsible for the kinetics associated with the chemical oxidation reaction, whereas ligand redistribution and exchange dictated the isolated product