An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Francesca M. Tavazza, Lyle E. Levine, Anne M. Chaka
Under tensile deformation, Au nanowires (NWs) elongate to form single atom chains via a series of intermediate structural transformations. These intermediate structures are investigated using semistatic density functional theory (DFT), with particular
Derek D. Hass, H. Zhao, Tabbetha A. Dobbins, Andrew J. Allen, Andrew Slifka, H. N. Wadley
A high pressure, electron-beam directed-vapor deposition process has been used to deposit partially stabilized zirconia containing 7 % yttria by mass at deposition pressures of 7.5 Pa to 23 Pa. Anisotropic ultra-small-angle X-ray scattering (USAXS) was
Paul Constantino, James J. Lee, H Chai, Bernhard Zipfel, Charles Ziscovici, Brian R. Lawn, Peter Lucas
Fossil hominin tooth enamel often exhibits antemortem edge chipping (Robinson 1954; Tobias 1967; Wallace 1973). Here we apply a simple fracture equation to estimate peak bite forces from the sizes of such chips. This equation, previously validated by
Xiaohong Gu, Guodong Chen, Minhua Zhao, Stephanie S. Watson, Paul E. Stutzman, Tinh Nguyen, Joannie W. Chin, Jonathan W. Martin
The objective of this study is to investigate the role of ZnO nanoparticles in the life cycle of a waterborne polyurethane (PU) nanocomposite during UV exposure. The effects of loadings and sizes of ZnO nanoparticles on photodegradation of ZnO/PU films
The micromechanics community has developed a large set of tools for measuring the properties of micro- and nano-scaled materials. These new tools have been successfully applied to a range of materials, most often in thin-film form, to determine the
The development of high fidelity simulations of lead-cored bullet impacts on soft body armor, motivated by the need for improved armor designs and performance standards for law enforcement, requires accurate models for both the armor and the deformable
Walter Villanueva, William J. Boettinger, Geoffrey B. McFadden, James A. Warren
A diffuse-interface model of reactive wetting with intermetallic formation is presented. The model incorporates fluid flow, solute diffusion, and phase change that are based on the total molar Gibbs energy of a ternary system with four phases. Numerical
Rick D. Davis, Joannie W. Chin, Chiao-Chi Lin, Sylvain H. Petit
Exposure to simulated ultraviolet sunlight at 50 C and 50 % relative humidity caused a significant deterioration in the mechanical performance of polyaramid and polyaramid/polybenzimidazole based Outer Shell fabrics used in firefighter jacket and pants
Tinh Nguyen, Bastien T. Pellegrin, Coralie Bernard, Xiaohong Gu, Justin M. Gorham, Paul E. Stutzman, Alexander J. Shapiro, Walter E. Byrd, Joannie W. Chin
The release of nanoparticles from nanocomposite coatings during their life cycle potentially has negative effects to the environments and presents a roadblock to their uses. The degradation and nanoparticle release of amine-cured epoxy coatings containing
We present a new experimental method for determining the broadband dielectric permittivity of ferroelectric thin film samples over the broad frequency range 100 Hz - 40 GHz. Such characterization is extremely important for both a fundamental understanding
John H. Lehman, Katherine E. Hurst, Gurpreet Singh, Elisabeth Mansfield, John D. Perkins, Christopher L. Cromer
Carbon nanotubes are known to have high thermal conductivity, and in bulk form, a topology that could constitute the matrix of an inhomogeneous solid. Among the promised applications of carbon nanotubes is a composite material that is practical for thermal
Michael S. Gaither, Frank W. DelRio, Richard S. Gates, Edwin R. Fuller, Robert F. Cook
A new test specimen has been developed for micro-scale tensile strength measurements, allowing direct assessment of surface effects on strength. Specimens were formed by deep reactive ion etching, tested with instrumented indentation, and test results
Xiaohong Gu, Guodong Chen, Minhua Zhao, Stephanie S. Watson, Tinh Nguyen, Joannie W. Chin, Jonathan W. Martin
In this study, the role of the nanoparticle/polymer interface in the long-term UV weathering performance of a nano-ZnO filled polyurethane (PU) coating system was investigated. The effects of the parameters that can influence the particle/polymer
One failure mode of all-ceramic crown restorations is radial cracking at the cementation surface, from occlusally-induced flexure of the stiffer crown layer on the softer dentin underlayer. We hypothesize that such failure may be substantially mitigated by
Andrew J. Allen, Jeffrey Thomas, Hamlin M. Jennings
Relationships between composition, mass density, and atomic packing density for CaO{SiO2{H2O (C{S{H) gel, the main hydration product of ce- ment, and its mineral analogues tobermorite and jennite, are examined. A phase diagram approach is proposed, in
Timofey Frolov, William J. Boettinger, Yuri Mishin
The goal of this paper is to explore mechanisms of hillock and whisker growth in stressed poly-crystalline films by molecular dynamics simulations. Our stress-free model consists of three grains and a triple line aligned perpendicular to a free surface
Christopher C. White, Kar T. Tan, Donald L. Hunston
Test methods were developed to duplicate the failure modes that occur to sealants during exposure in structures. The methods used a systematic approach to identify independent and synergistic effects of various aging factors on the durability of sealants
Ngoc Nguyen, Polly Berseth, Qiyin Lin, Catalin Chiritescu, D.G. Cahill, Anastassios Mavrokefalos, Li Shi, Paul Zschack, Michael D. Anderson, Ian M. Anderson, David C. Johnson
Turbostratically disordered tungsten diselenide (WSe2) thin films with as few as two c-axis-oriented (basal plane) structural units were synthesized from modulated elemental reactants. By varying the number of elemental W-Se bilayers deposited, the
Rick D. Davis, Joannie W. Chin, Chiao-Chi Lin, Sylvain H. Petit
Exposure to simulated ultraviolet sunlight at 50 C and 50% relative humidity caused a significant deterioration in the mechanical performance of polyaramid and polyaramid/polybenzimidazole based outer shell fabrics used in firefighter jacket and pants
Andrew A. Herzing, Weile Yan, Christopher J. Kiely, Wei-xian Zhang
Palladized zero-valent iron nanoparticles have been frequently employed to achieve enhanced treatment of halogenated organic compounds. However no detailed study has been published on their structures, especially the distribution of palladium within the
Joseph C. Woicik, D. Giubertoni, G. Pepponi, S. Gennaro, M. Bersani, M. A. Sahiner, S. P. Kelty, M. Kah, K. J. Kirkby, R. Doherty, M. A. Foad, F. Meirer, C. Streli, P. Pianetta
The use of non-equilibrium annealing approaches can produce a very high level of arsenic electrical activation in Si but subsequent thermal treatments between 500 and 800 C easily deactivate the dopant to a level one order of magnitude below the solid
Shujiang Yang, Mohammed Lach-hab, Estela Blaisten-Barojas, Xiang Li, Vicky L. Karen
Heulandite and clinoptilolite form the most abundant family of natural zeolite crystals. The topology of both of them is characterized by the framework type HEU. Despite many studies on these crystals, the mineral assignment to a zeolite as heulandite or
William E. Wallace, Lewandowski Hans, Meier J. Robert
Recently it has been shown that the cobaltocenium cation, prepared by the laser ablation of a CoCp(CO)2/fullerene matrix, may react with alkanes and polyethylenes in the gas phase via a dehydrogenation reaction to produce [Co(Cp)2(alkadiene)]+ ions without
Daniel A. Fischer, V. J. Lee, Patrick S. Lysaght, Sarbajit Banerjee
Interfacial interactions at graphene/metal and graphene/dielectric interfaces are likely to profoundly influence the electronic structure of graphene. We present here the first angle-resolved near-edge X-ray absorption fine structure (NEXAFS) spectroscopy
Dylan Morris, David Bahr, Ryan Need, Michael Anderson
A strategy to increase the performance of diaphragm-type transducers is to provide an initial curvature to the diaphragm, which converts in-plane strains to motion normal to the diaphragm surface. In this paper, we analyze and measure the actuation