Aerospace and Biomedical Engineering
Aerospace and Biomedical Engineering
Morin E.A.,Aerospace and Biomedical Engineering |
He W.,University of Tennessee at Knoxville |
He W.,Dalian University of Technology |
Li Z.,Qingdao University of Science and Technology
ACS Macro Letters | Year: 2017
While lower critical solution temperature (LCST)-type thermosensitive nanogels have been intensively studied, the upper critical solution temperature (UCST)-type versions are much less explored. This communication reports a method for the synthesis of zwitterionic UCST nanogels by reversible addition-fragmentation chain transfer (RAFT) polymerization-induced self-assembly in water-organic solvent mixtures. The nanogels were prepared by RAFT polymerization of 3-dimethyl(methacryloyloxyethyl)ammonium propanesulfonate, whose polymer is known to exhibit UCST behavior in water, conducted in ethanol-water mixtures at 70 °C using poly(poly(ethylene glycol) methyl ether methacrylate) as a macro-chain transfer agent (CTA) and a difunctional monomer as cross-linker. At a sufficiently high ethanol content in reaction media, spherical hairy nanogels with a single size distribution were obtained. These nanogels exhibited reversible heating-induced swelling and cooling-induced shrinking, consistent with the expected UCST behavior. The hydrodynamic size, volume changing ratio, and transition temperature of nanogels can be tuned by varying ethanol content in solvent mixtures, molar ratio of monomer-to-macro-CTA, and amount of cross-linker. Hairy nanogels were also successfully synthesized using a water-THF mixture as medium. The use of water-organic solvent mixtures as reaction media allowed for facile incorporation of a hydrophobic fluorescent monomer to make functional UCST nanogels. © 2017 American Chemical Society.
Coder J.G.,Aerospace and Biomedical Engineering
AIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting | Year: 2017
Improvements to the amplification factor transport transition modeling framework are described. A locally defined, Galilean invariant parameter serves as a local shape factor for estimating the integral boundary layer properties and linear instability growth. New correlations based on this local shape factor are presented, and the resulting Galilean invariant model is a theoretical improvement over the current state of the art in computational fluid dynamics transition modeling. Several validation cases are presented, including a zero-pressure-gradient flat plate, several airfoils, a commercial transport aircraft configuration, and a helicopter rotor in hover. The predictive capabilities of the model, including its behavior in complex flow fields, are discussed. © 2017 by James G. Coder.
Bottlander D.,Aerospace and Biomedical Engineering |
Mucksch C.,University of Kaiserslautern |
Urbassek H.M.,University of Kaiserslautern
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2015
Modern REAX potentials allow to use molecular dynamics simulation to study bond breaking and reformation in biomolecules. We use this technique to simulate the effects of a swift-ion track on a B-DNA fragment in water. We monitor the number of single- and double-strand breaks as a function of the deposited energy. In addition we compare the results of direct DNA heating with the effect of hydrolysis which we model by heating only the water environment. © 2015 Elsevier Inc. All rights reserved.
Kreitzman J.,Aerospace and Biomedical Engineering |
Stewart C.W.,Aerospace and Biomedical Engineering |
Cansler E.,Aerospace and Biomedical Engineering |
Brisby J.,Aerospace and Biomedical Engineering |
And 2 more authors.
Advances in the Astronautical Sciences | Year: 2014
Our group has previously described high-thrust mission opportunities to a number of trans-Neptunian Objects, including Sedna, Eris, Makemake, Haumea, Huya, Ixion, Varuna, Quaoar and others. In the current study, we extend that work to examine the possibility of orbital capture, and compare the merits of high-thrust and low-thrust primary propulsion systems in terms of the overall mission performance and potential orbital capture mass. In all cases, the outbound trajectory includes a Jovian flyby; radiation exposure during the flyby will influence the viability of candidate mission designs. Therefore the Jovian flyby segments are examined in some detail, and radiation dose-depth curves for several trajectories are presented as a means of comparison. For at least four targets, orbital capture of a small satellite (100-380 kg) was found to be feasible, using a high-thrust interplanetary trajectory and a launch on an Atlas V 551 with a Star 48 upper stage. Low thrust trajectories improve overall performance, either by increasing delivered mass or allowing a smaller launch vehicle.
Babu S.S.,Aerospace and Biomedical Engineering |
Vogel S.,Los Alamos National Laboratory |
Garcia-Mateo C.,CSIC - National Center for Metallurgical Research |
Clausen B.,Ohio State University |
And 2 more authors.
Scripta Materialia | Year: 2013
In situ neutron diffraction was used during tensile testing at room temperature to examine the changes in the proportion and texture of both ferrite and austenite in a nanocrystalline bainitic steel transformed at two different temperatures, 200 and 300 C, for different times to achieve the same phase percentages. Both samples showed an inability of austenite to transform to martensite under strain to take full advantage of the transformation-induced plasticity effect. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Mathur T.D.,Pennsylvania State University |
Saribay Z.B.,Power Transmission Systems Design |
Bill R.C.,Pennsylvania State University |
Smith E.C.,Pennsylvania State University |
DeSmidt H.,Aerospace and Biomedical Engineering
56th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference | Year: 2015
A design methodology for a Pericyclic mechanical transmission utilizing straight bevel gears has been presented. By virtue of its very high reduction ratio in a single meshing stage, the pericyclic transmission holds promise for significant transmission weight reduction compared to state-of-the-art concepts. Assembly, gear geometry and kinematics of the drivetrain leading to a high reduction ratio while having a very high contact ratio (~8-10 teeth in contact) has been discussed. Tooth contact behavior has been studied in detail. A load distribution model has been developed that can be easily generalized to any internal-external bevel gear mesh. A rolling/ sliding velocity analysis has also been carried out, taking nutational motion into account. This is further used to determine the elastohydrodynamic lubrication characteristics of the meshing gear pairs. The methodology was applied to a conceptual design, resulting in acceptable levels of predicted contact stress and transmission efficiency. © 2015, American Institute of Aeronautics and Astronautics. All Rights Reserved.
Lenaghan S.C.,Aerospace and Biomedical Engineering |
Burris J.N.,University of Tennessee at Knoxville |
Chourey K.,Organic and Biological Mass Spectrometry Group |
Huang Y.,Aerospace and Biomedical Engineering |
And 10 more authors.
Journal of the Royal Society Interface | Year: 2013
Bio-inspiration for novel adhesive development has drawn increasing interest in recent years with the discovery of the nanoscale morphology of the gecko footpad and mussel adhesive proteins. Similar to these animal systems, it was discovered that English ivy (Hedera helix L.) secretes a high strength adhesive containing uniform nanoparticles. Recent studies have demonstrated that the ivy nanoparticles not only contribute to the high strength of this adhesive, but also have ultraviolet (UV) protective abilities, making them ideal for sunscreen and cosmetic fillers, and may be used as nanocarriers for drug delivery. To make these applications a reality, the chemical nature of the ivy nanoparticles must be elucidated. In the current work, a method was developed to harvest bulk ivy nanoparticles from an adventitious root culture system, and the chemical composition of the nanoparticles was analysed. UV/ visible spectroscopy, inductively coupled plasma mass spectrometry, Fourier transform infrared spectroscopy and electrophoresis were used in this study to identify the chemical nature of the ivy nanoparticles. Based on this analysis, we conclude that the ivy nanoparticles are proteinaceous. © 2013 The Author(s) Published by the Royal Society. All rights reserved.
PubMed | University of Tennessee at Knoxville, National Renewable Energy Laboratory, Oak Ridge National Laboratory and Aerospace and Biomedical Engineering
Type: Journal Article | Journal: Science advances | Year: 2017
Better understanding of true electrochemical reaction behaviors in electrochemical energy devices has long been desired. It has been assumed so far that the reactions occur across the entire catalyst layer (CL), which is designed and fabricated uniformly with catalysts, conductors of protons and electrons, and pathways for reactants and products. By introducing a state-of-the-art characterization system, a thin, highly tunable liquid/gas diffusion layer (LGDL), and an innovative design of electrochemical proton exchange membrane electrolyzer cells (PEMECs), the electrochemical reactions on both microspatial and microtemporal scales are revealed for the first time. Surprisingly, reactions occur only on the CL adjacent to good electrical conductors. On the basis of these findings, new CL fabrications on the novel LGDLs exhibit more than 50 times higher mass activity than conventional catalyst-coated membranes in PEMECs. This discovery presents an opportunity to enhance the multiphase interfacial effects, maximizing the use of the catalysts and significantly reducing the cost of these devices.