Drawing liquid bridges from a thin viscous film.

When a particle, such as dust, contacts a thin liquid film covering a surface it is trapped by the liquid. This effect is caused by the formation of a meniscus, resulting in a capillary force that makes the particle adhere to the surface. While capillary adhesion is well-characterised in static situations, the dynamic formation of the liquid bridge after the initial contact is highly intricate. Here, we experimentally study the evolution of a liquid bridge after a glass sphere is gently brought into contact with a thin viscous film. It is found that the contact creates a ripple on the thin film, which influences the growth of the meniscus. Initially, the ripple and the meniscus are coupled and exhibit similar dynamics. This initial regime is well accounted for by a scaling law derived from lubrication theory. At a later stage, the ripple is "detached" from the liquid bridge, leading to a second regime of bridge dynamics. As a result, capillary forces are time-dependent, highlighting the importance of dynamics on adhesion.

Squeezing Drops: Force Measurements of the Cassie-to-Wenzel Transition.

Superhydrophobic surfaces have long been the center of attention of many researchers due to their unique liquid repellency and self-cleaning properties. However, these unique properties rely on the stability of the so-called Cassie state, which is a metastable state with air-filled microstructures. This state tends to transit to the stable Wenzel state, where the inside of the microstructures eventually wets. For potential industrial applications, it is therefore critical to maintain the Cassie state. We investigate the Cassie-to-Wenzel transition on superhydrophobic micropillar surfaces by squeezing a water drop between the surface and a transparent superhydrophobic force probe. The probe's transparency allows the use of top-view optics to monitor the area of the drop as it is squeezed against a micropillared surface. The impalement, or Cassie-to-Wenzel transition, is identified as a sharp decrease in force accompanied by an abrupt change in the drop's contact area. We compare the force measured by the sensor with the capillary pressure force calculated from the observed drop shape and find a good agreement between both quantities. We also study the force and pressure at impalement as a function of the pillar's slenderness ratio. Finally, we compare the impalement pressure with three literature predictions and find that our experimental values are consistently lower than the theoretical values. We find that a possible cause of this earlier Cassie-to-Wenzel transition may be the coalescence of the squeezed drop with microdroplets that nucleate around the base of the micropillars.

HrgS (Avin_34990), a novel histidine-kinase related to GacS, regulates alginate synthesis in Azotobacter vinelandii.

Azotobacter vinelandii is a soil bacterium that produces alginates, a family of polymers of biotechnological interest. In A. vinelandii, alginate production is controlled by the two-component system GacS/GacA. GacS/GacA, in turn, regulates the Rsm post-transcriptional regulatory system establishing a cascade that regulates alginate biosynthesis by controlling the expression of the algD biosynthetic gene. In Pseudomonas aeruginosa, GacS/GacA is influenced by other histidine-kinases constituting a multicomponent signal transduction system. In this study, we explore the presence of GacS-related histidine-kinases in A. vinelandii and discover a novel histidine-kinase (Avin_34990, renamed HrgS). This histidin-kinase acts as a negative regulator of alginate synthesis by controlling the transcription of the sRNAs belonging to the Rsm post-transcriptional regulatory system, for which a functional GacS is required.

Charging of drops impacting onto superhydrophobic surfaces.

When neutral water drops impact and rebound from superhydrophobic surfaces, they acquire a positive electrical charge. To measure the charge, we analyzed the trajectory of rebounding drops in an external electric field by high-speed video imaging. Although this charging phenomenon has been observed in the past, little is known about the controlling parameters for the amount of drop charging. Here we investigate the relative importance of five of these potential variables: impact speed, drop contact area, contact line retraction speed, drop size, and type of surface. We additionally apply our previously reported model for sliding drop electrification to the case of impacting drops, suggesting that the two cases contain the same charge separation mechanism at the contact line. Both our experimental results and our theoretical model indicate that maximum contact area is the dominant control parameter for charge separation.

Impact cratering in sand: comparing solid and liquid intruders.

How does the impact of a deformable droplet on a granular bed differ from that caused by a solid impactor of similar size and density? Here, we experimentally study this question and focus on the effect of intruder deformability on the crater shape. For comparable impact energies, we show that the crater diameter is larger for droplets than for solid intruders but that the impact of the latter results in deeper craters. Interestingly, for initially dense beds of packing fractions larger than 0.58, we find that the resultant excavated crater volume is independent of the intruder deformability, suggesting an impactor-independent dissipation mechanism within the sand for these dense beds.

Rol del personal enfermero para modificar el nivel de información en los adultos mayores diabéticos / The Nursing Staff's Role in Modifying the Level of Information in Diabetic Aged Adults

Introducción: La diabetes mellitus se debe a la secreción anormal de insulina y a grados variables de resistencia periférica a la insulina, que conducen a la aparición de hiperglucemia. Objetivo: Evaluar el papel del personal de enfermería para modificar el nivel de información de los adultos mayores diabéticos. Métodos: Estudio de desarrollo tecnológico, contextualizado en el Policlínico Dr. Rudesindo García del Rijo; del Municipio de Sancti Spíritus, en el período comprendido de enero a septiembre del 2019. Variables de estudio: nivel de información, control de la diabetes mellitus, cuidado, estado de salud y factores de riesgo presentes en los adultos mayores con diabetes mellitus. Se utilizó entrevista estructurada para conocer el nivel de información y el cuidado brindado por el personal de enfermería, para la mejoría del estado de salud, se aplicó la escala de Kaff y Lawton. Después de aplicada las acciones de Enfermería se compararon las proporciones poblacionales mediante Test Wilcoxon. Resultados: Los factores de riesgo que más predominaron fueron los antecedentes familiares (87 por ciento) y los hábitos dietéticos inadecuados (84,9 por ciento). El 73,63 por ciento tenía mal nivel de información al inicio; después de aplicar las acciones se enfermería, 60 por ciento obtuvo un nivel de información bueno. Conclusiones: Las acciones de enfermería para modificar el nivel de información en los adultos mayores diabéticos fueron efectivas, al modificar el nivel de conocimientos de los adultos mayores diabéticos, el cuidado y el estado de salud de los pacientes diabéticos que participaron en el estudio(AU)

Introduction: Diabetes mellitus is provoked by abnormal insulin secretion and variable degrees of peripheral insulin resistance, which lead to the onset of hyperglycemia. Objective: To assess the nursing staff role in modifying the level of information of diabetic aged adults. Methods: Study of technological development, contextualized in Dr. Rudesindo García del Rijo Polyclinic of Sancti Spíritus Municipality, in the period from January to September 2019. The study variables were level of information, control of diabetes mellitus, care, health status, and risk factors present in aged adults with diabetes mellitus. A structured interview was used to know the level of information and care provided by the nursing staff; regarding improvement of health state, the Kaff and Lawton scale was applied. After applying the Nursing actions, the population proportions were compared using the Wilcoxon Test. Results: The most prevalent risk factors were family history (87 por ciento) and inappropriate dietary habits (84.9 por ciento). 73.63 por ciento had a bad level of information at the beginning; After applying the nursing actions, 60 por ciento obtained a good level of information. Conclusions: The nursing actions to modify the level of information of aged adults about diabetic adults were effective, in so far their level of knowledge was modified, together with care and health state of the diabetic patients who participated in the study(AU)

Onset of Elasto-capillary Bundling of Micropillar Arrays: A Direct Visualization.

When a liquid drop gets into contact with a soft array of microstructures, capillary forces at the three-phase contact line can lead to critical deformations. Microstructures may collapse and form bundles or even patterns. So far, viewing the kinetics of bundling at the menisci scale has remained elusive. Here, we use laser scanning confocal microscopy to directly image the menisci between micropillars. We image structural changes in polydimethylsiloxane micropillar arrays during the Cassie-to-Wenzel transitions of a water drop evaporating on top of the array. We demonstrate how the regular pillar array undergoes a spontaneous symmetry breaking as the first step to the formation of pillar bundles. A comparison of the Cassie-to-Wenzel transition in air and FC40 indicates that the local contact angle determines the outcome of the bundling process. Based on these observations, we develop a simple model using the local contact angle, stiffness of the pillars, and interfacial tension of the liquid to predict the onset of the symmetry breaking.

Flow-Induced Long-Term Stable Slippery Surfaces.

Slippery lubricant-infused surfaces allow easy removal of liquid droplets on surfaces. They consist of textured or porous substrates infiltrated with a chemically compatible lubricant. Capillary forces help to keep the lubricant in place. Slippery surfaces hold promising prospects in applications including drag reduction in pipes or food packages, anticorrosion, anti-biofouling, or anti-icing. However, a critical drawback is that shear forces induced by flow lead to depletion of the lubricant. In this work, a way to overcome the shear-induced lubricant depletion by replenishing the lubricant from the flow of emulsions is presented. The addition of small amounts of positively charged surfactant reduces the charge repulsion between the negatively charged oil droplets contained in the emulsion. Attachment and coalescence of oil droplets from the oil-in-water emulsion at the substrate surface fills the structure with the lubricant. Flow-induced lubrication of textured surfaces can be generalized to a broad range of lubricant-solid combinations using minimal amounts of oil.

Morphology of Evaporating Sessile Microdroplets on Lyophilic Elliptical Patches.

The evaporation of droplets occurs in a large variety of natural and technological processes such as medical diagnostics, agriculture, food industry, printing, and catalytic reactions. We study the different droplet morphologies adopted by an evaporating droplet on a surface with an elliptical patch with a different contact angle. We perform experiments to observe these morphologies and use numerical calculations to predict the effects of the patched surfaces. We observe that tuning the geometry of the patches offers control over the shape of the droplet. In the experiments, the drops of various volumes are placed on elliptical chemical patches of different aspect ratios and imaged in 3D using laser scanning confocal microscopy, extracting the droplet's shape. In the corresponding numerical simulations, we minimize the interfacial free energy of the droplet, by employing Surface Evolver. The numerical results are in good qualitative agreement with our experimental data and can be used for the design of micropatterned structures, potentially suggesting or excluding certain morphologies for particular applications. However, the experimental results show the effects of pinning and contact angle hysteresis, which are obviously absent in the numerical energy minimization. The work culminates with a morphology diagram in the aspect ratio vs relative volume parameter space, comparing the predictions with the measurements.

Correlación imagenología-cirugía en 45 pacientes operados de síndrome subacromial / Correlational imaging: surgery in 45 patients operated on from subacromial syndrome

Se realizó un estudio comparativo en 45 pacientes operados en el Servicio de Ortopedia y Traumatología del Instituto Superior de Medicina Militar Dr. Luis Díaz Soto con diagnóstico de síndrome subacromial, a quienes se les había realizado previo a la cirugía vistas radiográficas y ultrasonidos del hombro afectado para corroborar el diagnóstico clínico. Posterior a la cirugía se compararon los diagnósticos imagenológicos con los anatomopatológicos encontrados. La bursitis no fue referida en el ultrasonido en 40 pacientes que si la presentaban. La capsulitis adhesiva se diagnosticó en 16 casos más de los que en realidad la presentaban. La tendinitis de la porción larga del bíceps se presentó en el 100 por ciento de los casos diagnosticados. El manguito rotador se encontró roto totalmente solo en el 10 por ciento de los casos diagnosticados. Las alteraciones óseas diagnosticadas por rayos X se corroboraron en el 100 por ciento de los pacientes. El margen de error en diagnósticos ultrasonogrßficos fue del 55,8 por ciento, mientras que en la radiografía simple fue del 11,1 por ciento.

A comparative study was conducted on 45 patients diagnosed with subacromial syndrome and operated on at the Orthopedics and Trauma Management Service of Dr Luis Díaz Soto Higher Institute of Military Medicine. These patients had been previously tested with X-ray and ultrasound in their affected shoulders in order to confirm the clinical diagnosis. After surgery, the imaging diagnoses were compared with the anatomopathological findings. Bursitis had not been referred in the ultrasound images of 40 patients who did have it. Adhesive capsulitis had been diagnosed in 16 cases more than the real number that did have it. Tendinitis in the longer part of biceps was present in 100 percent of cases. Rotator cuff was indeed totally broken in 10 percent of diagnosed cases. Bone alterations diagnosed with X-rays were verified in 100 percent of patients. Error margin in ultrasonographic diagnoses was 55,8 percent whereas in simple radiography was just 11,1 percent.

Correlación imagenología-cirugía en 45 pacientes operados de síndrome subacromial / Correlational imaging: surgery in 45 patients operated on from subacromial syndrome

Se realizó un estudio comparativo en 45 pacientes operados en el Servicio de Ortopedia y Traumatología del Instituto Superior de Medicina Militar Dr. Luis Díaz Soto con diagnóstico de síndrome subacromial, a quienes se les había realizado previo a la cirugía vistas radiográficas y ultrasonidos del hombro afectado para corroborar el diagnóstico clínico. Posterior a la cirugía se compararon los diagnósticos imagenológicos con los anatomopatológicos encontrados. La bursitis no fue referida en el ultrasonido en 40 pacientes que si la presentaban. La capsulitis adhesiva se diagnosticó en 16 casos más de los que en realidad la presentaban. La tendinitis de la porción larga del bíceps se presentó en el 100 por ciento de los casos diagnosticados. El manguito rotador se encontró roto totalmente solo en el 10 por ciento de los casos diagnosticados. Las alteraciones óseas diagnosticadas por rayos X se corroboraron en el 100 por ciento de los pacientes. El margen de error en diagnósticos ultrasonográficos fue del 55,8 por ciento, mientras que en la radiografía simple fue del 11,1 por ciento(AU)

A comparative study was conducted on 45 patients diagnosed with subacromial syndrome and operated on at the Orthopedics and Trauma Management Service of Dr Luis Díaz Soto Higher Institute of Military Medicine. These patients had been previously tested with X-ray and ultrasound in their affected shoulders in order to confirm the clinical diagnosis. After surgery, the imaging diagnoses were compared with the anatomopathological findings. Bursitis had not been referred in the ultrasound images of 40 patients who did have it. Adhesive capsulitis had been diagnosed in 16 cases more than the real number that did have it. Tendinitis in the longer part of biceps was present in 100 percent of cases. Rotator cuff was indeed totally broken in 10 percent of diagnosed cases. Bone alterations diagnosed with X-rays were verified in 100 percent of patients. Error margin in ultrasonographic diagnoses was 55,8 percent whereas in simple radiography was just 11,1 percent(AU)