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1.
Bioeng Transl Med ; 2(2): 222-232, 2017 06.
Article in English | MEDLINE | ID: mdl-28932820

ABSTRACT

Arteries for bypass grafting are harvested either with neighboring tissue attached or as skeletonized vessels that are free of surrounding tissue. There are significant benefits to skeletonization, but reports suggest that skeletonized vessels may develop structural defects and are at risk for atherosclerosis. We investigated the specific short-term effects of skeletonization on carotid artery biomechanics and microanatomy in a rabbit model. Six carotid arteries were surgically skeletonized. To support healing, three of these received polyethylene glycol hydrogel injected along their exterior surfaces. M-mode ultrasonography was used to track circumferential cyclic strain in the skeletonized, hydrogel-treated, and contralateral vessels. On day 21, the arteries were harvested, and vessel structure was assessed by histology, immunofluorescence microscopy, two-photon elastin autofluorescence, and second harmonic generation (SHG) microscopy. Intimal-medial thickness appeared unaffected by skeletonization, but the SHG signals indicated significant changes in collagen turnover in the adventitia. Skeletonized arteries also exhibited significantly decreased radial compliance (circumferential cyclic strain dropped ∼30%) and decreased numbers of elastic laminae (9.1 ± 2.0 to 2.3 ± 1.4). Hydrogel treatment protected against these effects with treated vessels maintaining normal mechanical properties. These results indicate that arterial skeletonization triggers immediate effects on vessel remodeling and reduced vessel compliance resulting in specific tissue alterations within 21 days, but that these effects can be attenuated by the placement of hydrogel on the exterior surface of the skeletonized vessel.

2.
Opt Express ; 25(6): 6954-6962, 2017 Mar 20.
Article in English | MEDLINE | ID: mdl-28381037

ABSTRACT

The fluorescence spectra of titanium doped sapphire (Ti:Sapphire) crystals were measured for temperature ranging from 300K to 77K. The resulting gain cross-section line shapes were calculated and used in a three-dimensional amplification model to illustrate the importance of the precise knowledge of these fluorescence spectra for the design of cryogenic cooled Ti:Sapphire based chirped-pulse laser amplifiers.

3.
Appl Opt ; 48(11): 2067-77, 2009 Apr 10.
Article in English | MEDLINE | ID: mdl-19363544

ABSTRACT

High-resolution mosaic imaging is performed for the first time to our knowledge with a multifocal, multiphoton, photon-counting imaging system. We present a novel design consisting of a home-built femtosecond Yb-doped KGdWO(4) laser with an optical multiplexer, which is coupled with a commercial Olympus IX-71 microscope frame. Photon counting is performed using single-element detectors and an inexpensive electronic demultiplexer and counters.


Subject(s)
Lasers , Microscopy/methods , Photons
4.
Opt Express ; 16(23): 18557-64, 2008 Nov 10.
Article in English | MEDLINE | ID: mdl-19581941

ABSTRACT

The transient thermal lensing in a liquid-nitrogren cooled kilohertz multipass amplifier is quantitatively measured with spatially-resolved Fourier transform spectral interferometry. A pump-probe arrangement allows the observation of a polarization-dependent non-thermal component following the fluorescence timescale: additional cooling would not suppress this residual lensing. We also observe a time-dependent thermal component that has a timescale sufficiently fast to indicate that there is cooling between shots even at a repetition rate of 1 kHz. The value of pump-induced lensing would be underestimated when performing time-averaged measurements of pump-induced phase shifts.


Subject(s)
Amplifiers, Electronic , Lasers , Lenses , Cold Temperature , Energy Transfer , Equipment Design , Equipment Failure Analysis , Reproducibility of Results , Sensitivity and Specificity
5.
Opt Lett ; 32(17): 2568-70, 2007 Sep 01.
Article in English | MEDLINE | ID: mdl-17767307

ABSTRACT

Two-photon absorption fluorescence is employed within a microfluidic device to create a three-dimensional chemical concentration map for mixing uniformity characterization. This multiphoton technique images fluorescence intensity directly and provides a simple, rapid, and readily employed route to composition characterization within microfluidic systems.

6.
J Chem Phys ; 126(3): 034511, 2007 Jan 21.
Article in English | MEDLINE | ID: mdl-17249888

ABSTRACT

Experimental observation and time relaxation measurement of the hydrated proton Eigen form [H(3)O(+)(H(2)O)(3)] are presented here. Vibrational time-resolved spectroscopy is used with an original method of investigating the proton excess in water. The anharmonicity of the time-resolved spectra is characteristic of the Eigen-type proton geometry. Proton relaxation occurs in less than 200 fs. A calculation of the potential energy confirms the experimental result and the Eigen cation lifetime is in good agreement with previous molecular dynamics simulations.


Subject(s)
Chemistry, Physical/methods , Spectrum Analysis/methods , Cations , Models, Statistical , Molecular Conformation , Normal Distribution , Oxygen/chemistry , Protons , Solvents , Spectrophotometry, Infrared , Time Factors , Water/chemistry
7.
Opt Commun ; 278(2): 368-376, 2007 Oct 15.
Article in English | MEDLINE | ID: mdl-19562096

ABSTRACT

We demonstrate pulse shaping via arbitrary phase modulation with a reflective, 1×4096 element, liquid crystal spatial light modulator (SLM). The unique construction of this device provides a very high efficiency when the device is used for phase modulation only in a prism based pulse shaper, namely 85%. We also present a single shot characterization of the SLM in the spatial domain and a single shot characterization of the pulse shaper in the spectral domain. These characterization methods provide a detailed picture of how the SLM modifies the spectral phase of an ultrashort pulse.

8.
J Chem Phys ; 121(16): 7908-13, 2004 Oct 22.
Article in English | MEDLINE | ID: mdl-15485253

ABSTRACT

We developed an experimental approach to study pure liquid water in the infrared and avoid thermal effects. This technique is based on libration induced stretching excitation of water molecules. A direct correspondence between frequencies within the libration and OH stretching bands is demonstrated. Energy diffusion is studied in pure liquid water by measuring wave packet dynamics of OH stretching vibrator with infrared femtosecond spectroscopy. Wave packet dynamics reveals ultrafast energy dynamics and reflects 130 fs intermolecular energy transfer between water vibrators. Energy diffusion is almost two orders of magnitude faster than self diffusion in water.


Subject(s)
Models, Chemical , Water/chemistry , Energy Transfer , Spectrum Analysis
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