Optical nanofiber temperature monitoring via double heterodyne detection

Tapered optical fibers (nanofibers) whose diameters are smaller than the optical wavelength are very fragile and can be easily destroyed if excessively heated by energy dissipated from the transmitted light. We present a technique for monitoring the nanofiber temperature using two-stage heterodyne detection. The phase of the heterodyne output signal is determined by that of the transmitted optical field, which, in turn, depends on the temperature through the refractive index. From the phase data, by numerically solving the heat exchange equations, the temperature distribution along the nanofiber is determined. The technique is applied to the controlled heating of the nanofiber by a laser in order to remove rubidium atoms adsorbed on its surface that substantially degrade its transmission. Almost 90% of the nanofiber's original transmission is recovered

Centering Abilities of Two Rotary Niti Systems in Medium Curved Canals

<div> <div> <div> <div> <p>Objectives: The aim of our study was to compare the centering ability of two recently introduced NITI file systems-New One ShapeTM and Protaper NextTM. </p> </div> </div> </div> </div

Comparison of shaping ability of ProTaper Next and 2Shape nickel–titanium files in simulated severe curved canals. Analisi sperimentale della preparazione endodontica in canali artificiali con curvature complesse: ProTaper Next Vs. 2Shape

Aim To evaluate the centering ability of ProTaper Next (PTN) and 2Shape (TS) nickel–titanium (NiTi) instruments in terms of maintaining the original root canal configuration in a simulated tooth with severe curvature. Methodology Twenty standardized simulated curved root canals were prepared to an apical size of 0.25 mm using PTN and TS (n = 10 canal/group) nickel-titanium files. A gig was constructed to enable reproducible image acquisition using a photographic camera. Pre- and post-instrumented images were recorded and superimposed using a computer software. The ability of the instruments to remain centered in the canal was determined by calculating a centering ratio at three independent points of the simulated canal: coronal, middle and apical third of the curvature, using a computer software. Statistical analysis was performed using one-way analysis of variance (ANOVA) followed by independent sample t-test at 5% significance level. Results No significant difference was found between the two systems (p &gt; 0.05). At the apical third, the mean centering ratio was significantly higher than the centering ratio of the coronal and the middle thirds in both TS and PTN (p &lt; 0.05). Conclusions There were no significant differences in the centering ability of the ProTaper Next and 2Shape systems in simulated severe curved canals. Both systems exhibited some degree of transportation, especially in the apical third