A detailed understanding of the corneal biomechanical response is an important prerequisite to understanding corneal diseases such as keratoconus and for placing the empirical equations used in refractive surgery on a physical basis. We have assembled a combined nonlinear optical microscopy (NLOM) and optical coherence microscopy (OCM) imaging system to simultaneously capture coregistered volumetric images of corneal morphology and biochemistry. Fudicial markers visible in the OCM volume enabled the calculation of strains for multiple depth layers in rabbit cornea. The results revealed a depth dependent strain distribution, with smaller strains in the anterior stroma and larger strains in the posterior stroma. The stress-strain curves can be grouped readily by depth into three groups: anterior (~20%), transitional mid (~40%), and posterior (~40%). Cross-sectional images of collagen lamellae, visible in NLOM, showed inhomogeneous collagen structure and its response to intraocular pressure along the anterior-posterior direction. The inhomogeneities correlate well with the noted heterogeneous corneal mechanical properties. The combined NLOM-OCM system can measure corneal microstructure and mechanical response uniquely, thus providing a microstructural understanding of corneal response to changes of collagen structure.

Fatigue crack growth in ±-Zirconium phosphate/epoxy nanocomposites was investigated. A new fatigue testing technique was implemented for miniature samples. Two different methods “strength of materials and Rayleigh-Ritz - were used in determining the bending stress. The fatigue stress and fatigue life of different nanocomposite specimens were plotted in a traditional stress-life (S-N) curve. It was inferred from the S-N plot that the values obtained from both the methods compare well. The experimental results showed that fatigue life of filled epoxy nanocomposite is more than that of the unfilled epoxy composite. A model for bending stresses, ultimate strength and the number of cycles to failure was obtained to predict a component service life without conducting elaborate tests. Scanning electron examination of the fractured surfaces revealed that the crack takes a tortuous path during its propagation course, indicating crack blunting and crack deflection roles of ZrP and CSR nanofillers, which consequently improve the fracture resistance. In case of the M-ZrP-epoxy systems, delamination of ZrP platelets from surrounding epoxy matrix was proposed as the reason behind crack growth. The improved fracture resistance of these nanocomposites was attributed to the delamination of ZrP platelets and deflection of crack direction. The superior behavior of CSR-ZrP-epoxy composites was attributed to the cavitation process and void coalescence due to CSR particles delamination.

Made available in DSpace on 2014-10-09T12:29:37Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:05Z (GMT). No. of bitstreams: 1 01267.pdf: 3199013 bytes, checksum: 692a3db754fd7c8754503b33fd7674c6 (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP

Made available in DSpace on 2014-10-09T12:26:39Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:11Z (GMT). No. of bitstreams: 1 13946.pdf: 2363272 bytes, checksum: bc190171e365c8e285decd96ed10e36d (MD5) / Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia) / IPEN/D-MPLO / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP; Faculdade de Odontologia, Universidade de Sao Paulo, Sao Paulo

Made available in DSpace on 2014-10-09T12:47:51Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:33Z (GMT). No. of bitstreams: 1 08319.pdf: 6875638 bytes, checksum: 6b5eeabf820dd27ca2fa6fcb250bcc1b (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:54:06Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:28Z (GMT). No. of bitstreams: 1 12445.pdf: 8811582 bytes, checksum: 756de19a729fb99884390f46e43c9b89 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Fisica, Universidade de Sao Paulo - IF/USP

Made available in DSpace on 2014-10-09T12:32:15Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:39Z (GMT). No. of bitstreams: 1 02531.pdf: 2279289 bytes, checksum: 1edfd4f1c6bed88132ea0c1644f03839 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:29:37Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:05Z (GMT). No. of bitstreams: 1 01267.pdf: 3199013 bytes, checksum: 692a3db754fd7c8754503b33fd7674c6 (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP

Made available in DSpace on 2014-10-09T12:26:39Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:11Z (GMT). No. of bitstreams: 1 13946.pdf: 2363272 bytes, checksum: bc190171e365c8e285decd96ed10e36d (MD5) / Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia) / IPEN/D-MPLO / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP; Faculdade de Odontologia, Universidade de Sao Paulo, Sao Paulo

Made available in DSpace on 2014-10-09T12:47:51Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:33Z (GMT). No. of bitstreams: 1 08319.pdf: 6875638 bytes, checksum: 6b5eeabf820dd27ca2fa6fcb250bcc1b (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP