3,919 research outputs found
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
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