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Contact Mode (contact + mode)

Distribution by Scientific Domains

Polymers and Materials Science	83%

Selected Abstracts

Effect of Contact Mode on the Electrical Transport and Field-Emission Performance of Individual Boron Nanowires

ADVANCED FUNCTIONAL MATERIALS, Issue 12 2010
Fei Liu
Abstract Vapor,liquid,solid processing of boron nanowires (BNWs) can be carried out either using a bottom-up or top-down growth mode, which results in different contact modes between the nanowire and the substrate. The contact mode may strongly affect the electrical transport and field-emission performance of the individual boron nanowires grown on a Si substrate. The electrical transport and field-emission characteristics of individual boron nanowires of different contact modes are investigated in situ using a scanning electron microscope. The contact barriers are very distinct for the different contact modes. Moreover, the transition from a "contact-limited" to a "bulk-limited" field-emission (FE) process is demonstrated in nanoemitters for the first time, and the proposed improved metal,insulator,vacuum (MIV) model may better illustrate the nonlinear behavior of the Fowler-Nordheim (FN) plots in these nanoscale systems. Individual BNWs with different contact modes have a discrepancy in their emission stability and vacuum breakdown characteristics though they have similar aspect ratios, which suggests that their electrical transport and field-emission performance are closely related to their contact mode. Boron nanowires grown in the base-up mode have better field-emission performances and are more beneficial than those grown in the top-down mode for various device applications. [source]

Chemical, Mechanical, and Antibacterial Properties of Silver Nanocluster,Silica Composite Coatings Obtained by Sputtering,

ADVANCED ENGINEERING MATERIALS, Issue 7 2010
Monica Ferraris
Abstract Silver nanocluster,silica matrix composite coatings have been deposited by radio frequency (RF) co-sputtering on silica substrates. Field emission scanning electron microscopy and X-ray diffraction spectra of the as deposited and heated samples (150,600,°C) revealed the presence of metal silver nanoclusters, their size depending on the heating treatment. The antibacterial activity of the as deposited and heated samples has been measured in accordance to National Committee for Clinical Laboratory Standards, and it has been demonstrated on samples heated up to 450,°C in contact mode and for samples heated at 600,°C in a liquid environment. Their antibacterial activity was still present after gamma ray and ethylene oxide gas (EtO) sterilization of the samples. Silver leaching tests on the as deposited and heated samples has been measured by graphite furnace atomic absorption spectrometer, revealing an amount ranging from 0.1 to 0.9,µg mm,2, over 28 days. Tape resistance (ASTM D3359-97) and scratch resistance tests have been done on each sample revealing a good adhesion of the coatings on silica. [source]

Effect of Contact Mode on the Electrical Transport and Field-Emission Performance of Individual Boron Nanowires

Comparison of fluoride and sapphire optical fibers for Er: YAG laser lithotripsy

JOURNAL OF BIOPHOTONICS, Issue 5-6 2010
Jinze Qiu
Abstract The long-pulse (200,350 ,s) Holmium: YAG (Ho: YAG) laser (, = 2.12 ,m) is used extensively in urology for laser lithotripsy. The long-pulse Erbium: YAG (Er: YAG) laser (, = 2.94 ,m) fragments urinary calculi up to 5 times more efficiently than the Ho: YAG laser, however, no optical fibers are available to transmit efficiently 2.94 ,m laser light for laser lithotripsy. We report results of a study evaluating a fluoride glass fiber to transmit Er: YAG laser light for laser lithotripsy and compare to a sapphire fiber that provides good transmission of Er: YAG light at low irradiance. The fluoride fiber provides superior light transmission efficiency over the sapphire fiber at an Er: YAG wavelength (2.94 ,m). The sapphire fiber provides a more durable and robust delivery waveguide than the fluoride fiber when ablating urinary calculi in contact mode. Results of our study suggest that further development to improve performance of fluoride fibers for laser lithotripsy is warranted. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

On the Use of the Nanoindentation Unloading Curve to Measure the Young's Modulus of Polymers on a Nanometer Scale

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 22 2005
Davide Tranchida
Abstract Summary: The nanoindentation test is a fundamental tool to assess the link between morphology and mechanical properties. The preliminary results of a more exhaustive study about the applicability to polymers of the most used procedure to determine elastic modulus by indentation are reported in this short communication. A departure of the experimental conditions from the theoretical assumptions and results that give rise to the Oliver and Pharr analysis is shown to occur under a wide range of experimental conditions, with applied loads and penetration depths covering several orders of magnitude and using different indenter geometries. Unloading curves with exponents significantly larger than 2 are observed in disagreement with the contact mechanics approach used by Oliver and Pharr. An AFM image obtained in non contact mode of an indentation induced by a sharp AFM tip with a maximum applied load of ca 1.2 µN on amorphous PET. [source]