Snap evaporation of droplets on smooth topographies

Droplet evaporation on solid surfaces is important in many applications including printing, micro-patterning and cooling. While seemingly simple, the configuration of evaporating droplets on solids is difficult to predict and control. This is because evaporation typically proceeds as a “stick-slip” sequence—a combination of pinning and de-pinning events dominated by static friction or “pinning”, caused by microscopic surface roughness. Here we show how smooth, pinning-free, solid surfaces of non-planar topography promote a different process called snap evaporation. During snap evaporation a droplet follows a reproducible sequence of configurations, consisting of a quasi-static phase-change controlled by mass diffusion interrupted by out-of-equilibrium snaps. Snaps are triggered by bifurcations of the equilibrium droplet shape mediated by the underlying non-planar solid. Because the evolution of droplets during snap evaporation is controlled by a smooth topography, and not by surface roughness, our ideas can inspire programmable surfaces that manage liquids in heat- and mass-transfer applications

Psychiatric disorders and functional disability in outpatients with traumatic brain injuries

Objective: This study examined psychiatric sequelae of traumatic brain injuries in outpa-tients and their relation to functional disability. Method: Fifty consecutive outpatients with traumatic brain injuries who came to a brain injury rehabilitation clinic for initial evaluation were examined for DSM-III-R diagnoses with the use of the National Institute of Mental Health Diagnostic Interview Schedule. The patients completed the Medical Outcomes Study Health Survey to assess functional disability and a questionnaire to assess postconcussion symptoms and self-perceptions ofthe severity oftheir brain injuries and cognitive functioning. Results: Thirteen (26%) of the patients had current major depression, and an additional 14 (28%) reporteda first-onset major depressive episode after the injury that had resolved. Twelve (24%) had current generalized anxiety disorder, and four (8%) reported current substance abuse. The group with depression and/or anxiety was significantly more impaired than the nondepressed/nonanxious patients according to the Medical Outcomes Study Health Survey measures of emotional role functioning, mental health, and general health perceptions. The depressed/anxious group also rated their injuries as significantly more severe and their cogni-tive functioning as significantly worse, despite the lack of significant differences in objectiv

Dielectric spectroscopy of biological cells in microfluidic devices

International audienceThis work is focused in the area of ligandreceptor interaction analysis, working with a wellcharacterized biological model (ligand: lactoferrin, receptors: nucleolin and sulfated proteoglycans). The purpose is to be able to assign, in real time, a specific crossing pathway to a ligand/receptor pair, without the use of molecular labels. The classification is based on changes in the electrical properties of the cells. We propose to follow the various phases of assembly between the ligand and receptors present or not on a set of mutant CHO cell lines, and internalization of the ligands/receptors complexes into the cells. Various BioMEMS have been designed and fabricated in order to characterize the variation of the electrical properties of the biological cells. We are interested in both dielectric (i.e. polarization) and vibrationnal (i.e. absorption) spectroscopy. Several devices are currently tested for low (40GHz) frequency range (LFR & HFR) measurements. In the LFR, we have fabricated coplanar and 3D electrodes sensors for impedance measurements. In the HFR, we have designed and processed coplanar waveguides

Delay in diagnosis of generalized miliary tuberculosis with osseo-articular involvement: a case report

<p>Abstract</p> <p>Introduction</p> <p>Diagnosis of atypical tuberculosis is difficult. Therefore, it is important that physicians are aware of rare presentations of tuberculosis to avoid diagnostic delays.</p> <p>Case presentation</p> <p>We present the case of a 17-year-old Sri Lankan man who presented to our facility with an ill-defined large induration over the skin of his left buttock and thigh. A cause could not be found despite extensive investigations. He also complained of chronic knee pain, but this was not investigated further at the time due to spontaneous resolution. Three years later his knee disease flared up again, with pain, swelling and restriction of movement. A synovial biopsy was suggestive of tuberculosis. He was started on antituberculosis therapy, to which he responded well. Our patient was asymptomatic two months after completion of therapy without any subsequent flare-ups. A chest roentgenogram taken on his second presentation showed evidence of tuberculosis sequelae in his lungs. The most likely diagnosis for the buttock and thigh swelling, when considering the entire clinical picture, is a tuberculous abscess. The constellation of skin and skeletal symptoms and pulmonary tuberculosis is a rare occurrence in an immunocompetent individual, but cases have been reported.</p> <p>Conclusions</p> <p>This case demonstrates the different presentations and the diagnostic difficulties posed by atypical manifestations of tuberculosis. It also demonstrates the value of maintaining a high degree of suspicion in endemic areas, even in the absence of microbiological evidence.</p