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Displaying 1076 - 1100 of 1896

FRACTURE OF TOOTH ENAMEL FROM INCIPIENT MICROSTRUCTURAL DEFECTS

June 14, 2010
Author(s)
H Chai, James J. Lee, Brian R. Lawn
We present definitive evidence for crack growth from internal defects called 'tufts' in human enamel. Side walls of slices sawn from extracted human teeth are observed during loading to 'failure'. 'Longitudinal' and 'transverse' slices (parallel and normal

Effects of fiber gripping methods on single fiber tensile test using Kolsky bar

June 10, 2010
Author(s)
Jae Hyun Kim, Richard L. Rhorer, Haruki Kobayashi, Walter G. McDonough, Gale A. Holmes
Preliminary data by Ming Cheng et al. indicate minimal impact of strain rate on the tensile stress-strain behavior of Kevlar. However, technical issues associated with specimen preparation appear to limit the number of samples and show an undesirable

Observations of Nanobubble Formation on Carbon Nanotubes

May 28, 2010
Author(s)
Andrew J. Slifka, Damian S. Lauria, Gurpreet Singh, Roop L. Mahajan
We used an optical trap and a high-speed camera to image bubble initiation on the surface of multi-walled carbon nanotubes. The laser wavelength was 1064 nm and the average power was 100 mW. This is the first demonstration of bubble formation on individual

Mechanical properties of one-dimensional nanostructures

May 23, 2010
Author(s)
Gheorghe Stan, Robert F. Cook
The elastic mechanical properties of one-dimensional nanostructures are considered, with an emphasis on the use of contact-resonance atomic force microscopy methods to determine elastic moduli. Various methods used to determine elastic moduli of one

Core-shell composite of SiCN and multiwalled carbon nanotubes from Toluene dispersion

May 21, 2010
Author(s)
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

A Graphical Approach for Assessing High Strength Fiber Performance

May 20, 2010
Author(s)
Walter G. McDonough, Gale A. Holmes, Amanda L. Forster, Kirk D. Rice
The design and materials used for bullet resistant body armor have evolved continuously to keep up with the threats. In this paper, a graphical approach is presented that plots the potential strain energy absorption of some common high performance fibers

High Speed Fiber Testing: The Single Fold Test

May 20, 2010
Author(s)
Haruki Kobayashi, Walter G. McDonough, Alexander J. Shapiro, Jae H. Kim, Stefan D. Leigh, Amanda L. Forster, Kirk D. Rice, Gale A. Holmes
The failure of a first responder s body armor has prompted research to assess the long-term durability and effectiveness of current and future soft body armor products. Prior work in this laboratory described a 10 % drop in tensile strength and 15 % drop

GRADED STRUCTURES FOR ALL-CERAMIC RESTORATIONS

May 17, 2010
Author(s)
Yu Zhang, H Chai, Brian R. Lawn
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

Predicting the In-Service Performance of Materials Exposed to Outdoor Weathering

May 12, 2010
Author(s)
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

Gate Dielectrics Year-In-Review

May 3, 2010
Author(s)
Jason P. Campbell
The gate dielectrics year-in-review includes a comprehensive examination of the past year s reports which detail gate stack reliability issues and the corresponding physical mechanisms which limit the performance and lifetimes of advanced devices. The

Novel CaF2 Nanocomposite with High Strength and F Ion Release

May 3, 2010
Author(s)
Hockin D. Xu, Jennifer L. Moreau, Limin Sun, Laurence Chow
Secondary caries and restoration fracture remain the two most common problems. The objectives of this study were to develop stress-bearing, fluoride-releasing nanocomposites. Novel CaF2 nanoparticles (56-nm) were synthesized via spray-drying and

NBTI: Confusion, Frustration, and Promise?

May 2, 2010
Author(s)
Jason P. Campbell
The negative-bias temperature instability (NBTI) is a reliability problem that, in the last ten years, has risen from relative obscurity to become the most important reliability problem in advanced pMOSFET devices. Even though a significant effort has been

Reactive MALDI Mass Spectrometry of Saturated Hydrocarbons: A Theoretical Study

May 1, 2010
Author(s)
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

Tissue Engineered Scaffolds for Screening Nanoparticle - Cell Interactions

April 21, 2010
Author(s)
Kavita M. Jeerage, Elisabeth Mansfield, Tammy L. Oreskovic, Nikki S. Rentz, Timothy P. Quinn
Long-term studies of nanoparticle-cell interactions require an advanced tissue-like environment in which nanoparticles are encapsulated with a population of cells for real-time and end-point analysis. By using soft tissue-mimicking hydrogels, the cells are

Architectural Effects on Reaction-Diffusion Kinetics in Molecular Glass Photoresists

April 20, 2010
Author(s)
Vivek M. Prabhu, Shuhui Kang, Christopher L. Soles, Christopher K. Ober, Jing Sha, Jin-Kyun Lee, Peter V. Bonnesen
Understanding acid reaction-diffusion kinetics is crucial for controlling the lithographic performance of chemically amplified photoresists. In this work, we study how the molecular architectures of positive-tone chemically amplified molecular glass

Assessing and Improving Bonding in Wet Conditions

April 3, 2010
Author(s)
Kar T. Tan, Christopher C. White, Donald L. Hunston, Vogt D. Bryan, Anthony Haag
Water is ubiquitous in any uncontrolled setting and affects world wide commerce by instigating device and structural failures. This can be a result of corrosion, electrical shorting, or adhesive failure. For adhesive failure, the environmental attack of
Displaying 1076 - 1100 of 1896
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