Open Access. Powered by Scholars. Published by Universities.®
- Institution
- Publication
- Publication Type
Articles 1 - 15 of 15
Full-Text Articles in Engineering
Regulating Factors In Anthocyanin Biosynthesis, Gregory Keith Bartley Jr.
Regulating Factors In Anthocyanin Biosynthesis, Gregory Keith Bartley Jr.
Gregory Keith Bartley Jr.
No abstract provided.
Organic Chemistry , Yu Zhu
Nano Letters , Yu Zhu
Nature , Yu Zhu
Contact Angle Hysteresis: A Different View And A Trivial Recipe For Low Hysteresis Hydrophobic Surfaces, Joseph W. Krumpfer, Thomas J. Mccarthy
Contact Angle Hysteresis: A Different View And A Trivial Recipe For Low Hysteresis Hydrophobic Surfaces, Joseph W. Krumpfer, Thomas J. Mccarthy
Thomas J. McCarthy
Contact angle hysteresis is addressed from two perspectives. The first is an analysis of the events that occur during motion of droplets on superhydrophobic surfaces. Hysteresis is discussed in terms of receding contact line pinning and the tensile failure of capillary bridges. The sign of the curvature of the solid surface is implicated as playing a key role. The second is the report of a new method to prepare smooth low hysteresis surfaces. The thermal treatment of oxygen plasma-cleaned silicon wafers with trimethylsilyl-terminated linear poly(dimethylsiloxane) (PDMS - commercial silicone oils) in disposable glass vessels is described. This treatment renders silicon/silica …
Multi-Scale Simulation Of Linear, Short-Chain Polyethylene Liquids Under Flow Conditions, Jun Mo Kim
Multi-Scale Simulation Of Linear, Short-Chain Polyethylene Liquids Under Flow Conditions, Jun Mo Kim
Doctoral Dissertations
The rheological and structural properties of polymeric liquids cannot be condensed within a single numerical model. They should be described within hierarchical, multi-level numerical models in which each sub-model is responsible for different time and length scales; atomistic, mesoscopic, and continuum. In this study, the rheological and structural properties of linear, short-chain polyethylene liquids were investigated from the classical atomistic level to the mesoscopic and continuum levels of description. At the atomistic level of description, nonequilibrium molecular dynamics (NEMD) simulations of linear, short-chain polyethylene liquids spanning from C16H24 to C128H256 were performed to advance our knowledge of fundamental characteristic of …
Effect Of Surface Freezing On Meniscus Relaxation In Side Chain Comb Polymers, Shishir Prasad, Zhang Jiang, Michael Sprung, Sunil K. Sinha, Ali Dhinojwala
Effect Of Surface Freezing On Meniscus Relaxation In Side Chain Comb Polymers, Shishir Prasad, Zhang Jiang, Michael Sprung, Sunil K. Sinha, Ali Dhinojwala
College of Polymer Science and Polymer Engineering
We have observed a sharp slowing down of the relaxation of the liquid meniscus for polydn-alkyl acrylate) at temperatures where there are no abrupt changes in bulk viscosity or surface tension. This slowing down is due to the formation of a surface-ordered monolayer above the bulk melting temperatures. X-ray photon correlation spectroscopy measurements reveal that the surface capillary fluctuations are also significantly slower due to the formation of the ordered monolayer for film thicknesses comparable to that of the precursor films. The slowing down of the precursor film dynamics is responsible for slower meniscus relaxation below the surface ordering transition …
Selective Recursive Kernel Learning For Online Identification Of Nonlinear Systems With Narx Form, Yi Liu, Haiqing Wang, Jiang Yu, Ping Li
Selective Recursive Kernel Learning For Online Identification Of Nonlinear Systems With Narx Form, Yi Liu, Haiqing Wang, Jiang Yu, Ping Li
Dr. Yi Liu
Online identification of nonlinear systems is still an important while difficult task in practice. A general and simple online identification method, namely Selective Recursive Kernel Learning (SRKL), is proposed for multi-input–multi-output (MIMO) systems with the nonlinear autoregressive with exogenous input form. A two-stage RKL online identification framework is first formulated, where the information contained by a sample (i.e., the new arriving or old useless one) can be introduced into and/or deleted from the model, recursively. Then, a sparsification strategy to restrict the model complexity is developed to guarantee all the output channels of the MIMO model accurate simultaneously. Specially, a …
Analysis Of Non-Covalent Interactions Between The Nanoparticulate Fillers And The Matrix Polymer As Applied To Shape Memory Performance, I. Sedat Gunes, Cesar Perez-Bolivar, Feina Cao, Guillermo A. Jimenez, Pavel Anzenbacher, Sadhan C. Jana
Analysis Of Non-Covalent Interactions Between The Nanoparticulate Fillers And The Matrix Polymer As Applied To Shape Memory Performance, I. Sedat Gunes, Cesar Perez-Bolivar, Feina Cao, Guillermo A. Jimenez, Pavel Anzenbacher, Sadhan C. Jana
Sadhan C Jana
Non-covalent interactions between filler particles and polyurethanes were investigated using fluorescence emission spectroscopy. The results were used in the analysis of shape memory (SM) performance of polyurethanes. Composites of shape memory polyurethane (SMPU) and carbon nanofiber (CNF), oxidized carbon nanofiber (ox-CNF), organoclay, silicon carbide, and carbon black were prepared from diphenylmethane diisocyanate, 1,4-butanediol, and poly(caprolactone) diol. It was revealed by fluorescence emission spectroscopy that primarily the urethane groups located in the hard segments of SMPU interacted with the polar functional groups on filler particles. A close correlation between the extent of non-covalent filler-matrix interactions, soft segment crystallinity, and SM properties …
Apolar Ortho-Phenylene Ethynylene Oligomers: Conformational Ordering Without Intermolecular Aggregation, Jing Jiang, Morris M. Slutsky, Ticora V. Jones, Gregory N. Tew
Apolar Ortho-Phenylene Ethynylene Oligomers: Conformational Ordering Without Intermolecular Aggregation, Jing Jiang, Morris M. Slutsky, Ticora V. Jones, Gregory N. Tew
Gregory N. Tew
This paper describes the characterization of solvent induced folding behavior for non-polar (NP) alkoxy substituted ortho-phenylene ethynylene (o-PE) oligomers. Oligomers of lengths up to nine units have been shown to adopt helical conformations in heptane by NMR and CD spectroscopy, while chloroform promotes extended conformations. Surprisingly, the molar ellipticity values found in heptane for these oligomers are very small compared to other literature values of meta-phenylene ethynylene (m-PE) folded systems; however, comparable molar ellipticity values were found for a closed macrocyclic o-PE suggesting the weak ellipticity is a molecular-feature rather than a quality of folding indicator.
Dynamics Of Individual Molecules Of Linear Polyethylene Liquids Under Shear: Atomistic Simulation And Comparison With A Free-Draining Bead-Rod Chain, David Keffer, J. M. Kim, B. J. Edwards, B. Khomami
Dynamics Of Individual Molecules Of Linear Polyethylene Liquids Under Shear: Atomistic Simulation And Comparison With A Free-Draining Bead-Rod Chain, David Keffer, J. M. Kim, B. J. Edwards, B. Khomami
David Keffer
Nonequilibrium molecular dynamics (NEMD) simulations of a dense liquid composed of linear polyethylene chains were performed to investigate the chain dynamics under shear. Brownian dynamics (BD) simulations of a freely jointed chain with equivalent contour length were also performed in the case of a dilute solution. This allowed for a close comparison of the chain dynamics of similar molecules for two very different types of liquids. Both simulations exhibited a distribution of the end-to-end vector, |Rete|, with Gaussian behavior at low Weissenberg number (Wi). At high Wi, the NEMD distribution was bimodal, with two peaks …
Evolution Of Block-Copolymer Order Through A Moving Thermal Zone, Kevin G. Yager, Nathaniel J. Fredin, Xiaohua Zhang, Brian C. Berry, Alamgir Karim, Ronald L. Jones
Evolution Of Block-Copolymer Order Through A Moving Thermal Zone, Kevin G. Yager, Nathaniel J. Fredin, Xiaohua Zhang, Brian C. Berry, Alamgir Karim, Ronald L. Jones
Alamgir Karim
We investigate block-copolymer (BCP) thin film ordering kinetics during annealing across a moving in-plane temperature gradient. We operate in the so-called cold zone annealing (CZA) regime, where ordering temperatures are above the glass-transition, but well below the order-disorder transition. By measuring the order through the in-plane gradient, using atomic force microscopy and grazing-incidence small-angle X-ray scattering (GISAXS), we confirm that CZA greatly enhances ordering kinetics, as compared to uniform oven annealing. The maximal ordering occurs over a narrow range of the heating-up phase, and not during the subsequent cooling phase. The large grain sizes obtained using CZA are due to …
Observation Of A Characteristic Length Scale In The Healing Of Glassy Polymer Interfaces, Guangcui Yuan, Clive Li, Sushil K. Satija, Alamgir Karim, Jack F. Douglas, Charles C. Han
Observation Of A Characteristic Length Scale In The Healing Of Glassy Polymer Interfaces, Guangcui Yuan, Clive Li, Sushil K. Satija, Alamgir Karim, Jack F. Douglas, Charles C. Han
Alamgir Karim
We examine the evolution (‘healing’) of the interface between two polymer films at various temperatures below the glass transition temperature, Tg. Specifically, neutron reflectometry is used to study the relaxation of the interface between both unentangled and entangled deuterated polystyrene (d-PS) and hydrogenated polystyrene (h-PS) films in the glass state where these bilayer films are supported on silicon substrates. We find that the initially sharp interface between the glassy polymer layers broadens with time (t), but the average interfacial thickness Δσ(t) between these layers then saturates after long time to a thickness (ξp) in a range between 1 nm and …
Spr Imaging Study Of Dna Wrapped Single Wall Carbon Nanotube (Ssdna-Swcnt) Adsorption On A Model Biological (Collagen) Substrate, Jung Jin Park, Jeffrey A. Fagan, Ji Yeon Huh, Kalman B. Migler, Alamgit Karim, Dharmaraj Raghaven
Spr Imaging Study Of Dna Wrapped Single Wall Carbon Nanotube (Ssdna-Swcnt) Adsorption On A Model Biological (Collagen) Substrate, Jung Jin Park, Jeffrey A. Fagan, Ji Yeon Huh, Kalman B. Migler, Alamgit Karim, Dharmaraj Raghaven
Alamgir Karim
The adsorption kinetics of single stranded-DNA dispersed single wall carbon nanotubes (ssDNA-SWCNTs) onto an immobilized collagen layer in a microfluidic channel was probed using surface plasmon resonance imaging (SPRi). The adsorption was measured for a range of both nanotube and solution parameters including the nanotube concentration, nanotube length, solution pH, and the type of medium (buffer and river water). The kinetic adsorption data suggests that the adsorption of the nanotubes to the collagen layer is irreversible in HEPES buffer, pH ≈ 7.4, at room temperature, with the nanotube adsorption displaying two different kinetic adsorption regimes for different concentration ranges. A …
Poly(Beta-Alanoid-Block-Beta-Alanine)S: Synthesis Via Cobalt-Catalyzed Carbonylative Polymerization And Self-Assembly, Shaohui Lin, Xinfei Yu, Yinfeng Tu, Hongyu Xu, Stephen Z. D. Cheng, Li Jia
Poly(Beta-Alanoid-Block-Beta-Alanine)S: Synthesis Via Cobalt-Catalyzed Carbonylative Polymerization And Self-Assembly, Shaohui Lin, Xinfei Yu, Yinfeng Tu, Hongyu Xu, Stephen Z. D. Cheng, Li Jia
Li Jia
The titled diblock copolymers are synthesized via cobalt-catalyzed living carbonylative polymerization of N-alkylaziridines under moderate pressures followed by a deprotection step. The poly(beta-alanine) block is solubilized by the poly(beta-alanoid) block in chloroform and remains fully hydrogen-bonded in the form of a sheet-like assembly.