Standing wave in evaporating meniscus detected by infrared thermography

A standing wave has been detected in the evaporating meniscus formed on an organic liquid (acetone) inside a horizontally positioned capillary tube of 1mm internal diameter. The standing wave is believed to originate from the interaction between surface tension and gravitational forces. We found that the standing wave ensues only at the upper part of the meniscus interface where gravity and surface tension act in the opposite direction. This experimental observation is similar to standing waves observed in floating zones in microgravity but different from travelling waves reported recently in volatile drops; in both cases the waves are produced by temperature differences along a liquid-vapour interface. By employing InfraRed thermography, we recorded the temperature distribution of the meniscus interface, and we found that the first characteristic frequency of the standing wave is around 0.3Hz.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Goodbye Hartmann trial: a prospective, international, multicenter, observational study on the current use of a surgical procedure developed a century ago

Background: Literature suggests colonic resection and primary anastomosis (RPA) instead of Hartmann's procedure (HP) for the treatment of left-sided colonic emergencies. We aim to evaluate the surgical options globally used to treat patients with acute left-sided colonic emergencies and the factors that leading to the choice of treatment, comparing HP and RPA. Methods: This is a prospective, international, multicenter, observational study registered on ClinicalTrials.gov. A total 1215 patients with left-sided colonic emergencies who required surgery were included from 204 centers during the period of March 1, 2020, to May 31, 2020. with a 1-year follow-up. Results: 564 patients (43.1%) were females. The mean age was 65.9 ± 15.6 years. HP was performed in 697 (57.3%) patients and RPA in 384 (31.6%) cases. Complicated acute diverticulitis was the most common cause of left-sided colonic emergencies (40.2%), followed by colorectal malignancy (36.6%). Severe complications (Clavien-Dindo ≥ 3b) were higher in the HP group (P < 0.001). 30-day mortality was higher in HP patients (13.7%), especially in case of bowel perforation and diffused peritonitis. 1-year follow-up showed no differences on ostomy reversal rate between HP and RPA. (P = 0.127). A backward likelihood logistic regression model showed that RPA was preferred in younger patients, having low ASA score (≤ 3), in case of large bowel obstruction, absence of colonic ischemia, longer time from admission to surgery, operating early at the day working hours, by a surgeon who performed more than 50 colorectal resections. Conclusions: After 100 years since the first Hartmann's procedure, HP remains the most common treatment for left-sided colorectal emergencies. Treatment's choice depends on patient characteristics, the time of surgery and the experience of the surgeon. RPA should be considered as the gold standard for surgery, with HP being an exception

EXPERMENTAL INVESTIGATION OF A TRANSPARENT SINTERED HEAT PIPE

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Three-Dimensional Marangoni cell in self-induced evaporating cooling unveiled by µ-Particle Image Velocimetry and Digital Holographic Microscopy

µ-Particle Image Velocimetry has successfully been used to map the velocity fields on diametrical horizontal and vertical cross sections of a transparent glass circular tube of 900µm diameter filled with ethanol. A Digital Holographic Microscope has been used to trace the trajectory of a tracer particle inside the liquid phase of an evaporating meniscus formed at the mouth of a 1mm square borosilicate tube filled with ethanol. The Marangoni flow cells are due to the self-induced differential evaporating cooling along the meniscus interface that creates gradients of surface tension which drive the convection. The competition between surface tension and gravity forces along the curved meniscus interface disrupts the symmetry due to surface tension alone. This distorts the shape of the toroidal Marangoni vortex. This is clearly seen in the µ-Particle Image Velocimetry velocity maps. Thermocapillary instabilities of the evaporating meniscus are reported in the present work by analysing the trajectories of a tracer particle. It is found that the trajectory of the tracer makes different shaped three-dimensional loops and every four loops it returns to the first loop. By analysing several loops it was found that the characteristic frequency of the periodic oscillatory motion is around 0.125 Hz.info:eu-repo/semantics/publishe

Three-dimensional Marangoni cell in self-induced evaporating cooling unveiled by digital holographic microscopy

info:eu-repo/semantics/publishe