Optimizing thermal conductivity in functionalized macromolecules using Langevin dynamics and the globalized and bounded Nelder-Mead algorithm.

Nanocomposites with high-aspect ratio fillers attract enormous attention because of the superior physical properties of the composite over the parent matrix. Nanocomposites with functionalized graphene as fillers did not produce the high thermal conductivity expected due to the high interfacial thermal resistance between the functional groups and graphene flakes. We report here a robust and efficient technique that identifies the configuration of the functionalities for improved thermal conductivity.

Mechanisms of biliary stone fragmentation using the Ho:YAG laser.

We have investigated the fragmentation of gallstones using the pulsed Ho:YAG laser, comparing it to lithotripsy using the visible pulsed-dye laser. We find that the physical mechanisms of stone fragmentation appear to be quite different in the two cases. Using high-speed photography, measurement of acoustic transients, time-resolved optical emission spectroscopy, and direct microscopic observation, we have analyzed the interaction of the Ho:YAG laser with both water and gallstones.

Pump wavelength tuning of a near-infrared optical parametric oscillator.

Optical parametric conversion in a potassium titanyl phosphate crystal with a tunable alexandrite laser was investigated as a function of pump wavelengths in the 700-800-nm region. Threshold energies and slope efficiencies for a doubly resonant oscillator configuration were measured for pump wavelengths of 744, 766, and 780 nm. Phase-matching conditions and a theoretical analysis using Sellmeier's equations provide good agreement with experimentally measured values of signal and idler wavelengths as a function of the pump wavelengths.

Comparison of holmium and flashlamp pumped dye lasers for use in lithotripsy of biliary calculi.

The characteristics of laser lithotripsy of biliary calculi are compared for a flashlamp pumped dye laser (lambda = 640 nm) and a Cr:Tm:Ho-YAG laser (lambda = 2.1 microns). Data on fragmentation efficiency with respect to laser power and pulse repetition rate are presented for different types of stones.