Hysteresis of the Contact Angle of a Meniscus Inside a Capillary with Smooth, Homogeneous Solid Walls

This paper was accepted for publication in the journal Langmuir: the ACS journal of surfaces and colloids and the definitive published version is available at http://dx.doi.org/10.1021/acs.langmuir.6b00721.A theory of contact angle hysteresis of a meniscus inside thin capillaries with smooth, homogeneous solid walls is developed in terms of surface forces (disjoining/ conjoining pressure isotherm) using a quasi-equilibrium approach. The disjoining /conjoining pressure isotherm includes electrostatic, intermolecular, and structural components. The values of the static receding θr, advancing θa , and equilibrium θe contact angles in thin capillaries were calculated on the basis of the shape of the disjoining/conjoining pressure isotherm. It was shown that both advancing and receding contact angles depend on the capillary radius. The suggested mechanism of the contact angle hysteresis has a direct experimental confirmation: the process of receding is accompanied by the formation of thick β-films on the capillary walls. The effect of the transition from partial to complete wetting in thin capillaries is predicted and analyzed. This effect takes place in very thin capillaries, when the receding contact angle decreases to zero

Experimental setting for measurement and correction of optical distortion of rigid endoscopic systems

Aim: The endoscope armamentarium is a huge part of modern medicine. However, despite their wide applications, endoscopes are not without setbacks, the major one being image distortion caused by the nature of the lenses comprising the system. The aim of the current study is to present a methodology for recording and measuring the optical distortion of several clinically used endoscopes.Materials and methods: A scaffold consisting of a vertical calibration grid two supports and fixating mechanisms was constructed for the aim of the study. Different rigid systems, used in a wide range of medical fields, were aimed at the calibration grid at the respected working angle and images were obtained with an endoscope compatible digital camera. The distortion of the images was later measured and corrected with an established post-procedural correction algorithm to visualize the difference.Results: Comparison between the distortion of the different systems showed the rate at which endoscopists have to be accustomed to their systems, while also demonstrating the ease of image correction. The data also provided the basis for further detailed research on how the distortion rate affects the learning process and practice of the endoscopist not only in otorhinolaryngology, but in other medical fields such as abdominal surgery and orthopedics.Conclusion: The natural optical distortion of any endoscope can be easily recorded and measured with our device, provided the constant conditions. The post-process corrections could at some point be programed into the imaging systems and provide an undistorted live feed endoscopy image.Der Erstautor gibt keinen Interessenkonflikt an

Harmonic scalpel in supraglottoplasty

Introduction: Supraglottoplasty is the gold standard for treatment of severe laryngomalacia. The surgical tools used in this type of intervention range from cold steel and microdebriders to different types of lasers. We propose and outline a surgical protocol for supraglottoplasty in a laryngomalacia type II case, performed using a harmonic scalpel.Materials and methods: An otherwise healthy male infant was referred to the ENT department at "St. Marina" University Hospital - Varna, Bulgaria with a history of stridor since birth. Clinically larygomalacia was diagnosed by means of sleep endoscopy and subsequently corrected with supraglottoplasty at the age of 23 months. General trans-nasal intubational anaesthesia was used for the procedure. The performing surgeon held both the MacIntosh direct laryngoscope and the Harmonic scalpel, while the assistant held a rigid endoscope. Postoperatively the child was transferred to the children's and neonatal intensive care unit for constant monitoring for a period of 24 hours.Results: The described surgical protocol was carried out with ease by a team of two ENT surgeons in a child of this age and rate of development. The Harmonic scalpel allowed for an effective and bloodless division of the aryepiglottic folds with up to two applications. The leading symptoms resolved postoperatively. Three months postoperatively a control sleep endoscopy was performed and showed improved anatomical relations of the laryngeal complex and a widened laryngeal aperture with no signs of scarring at the resected aryepiglottic folds.Conclusions: The use of harmonic scalpel surgery for the treatment of laryngomalacia appears to be a practical, affordable and easily applicable alternative to the already established surgical protocols.Supported by: This research received no specific grants nor funding from any agency, commercial or not-for-profit organizations.Der Erstautor gibt keinen Interessenkonflikt an