Surface Properties of Colloidal Particles Affect Colloidal Self-Assembly in Evaporating Self-Lubricating Ternary Droplets

[Image: see text] In this work, we unravel the role of surface properties of colloidal particles on the formation of supraparticles (clusters of colloidal particles) in a colloidal Ouzo droplet. Self-lubricating colloidal Ouzo droplets are an efficient and simple approach to form supraparticles, overcoming the challenge of the coffee stain effect in situ. Supraparticles are an efficient route to high-performance materials in various fields, from catalysis to carriers for therapeutics. Yet, the role of the surface of colloidal particles in the formation of supraparticles using Ouzo droplets remains unknown. Therefore, we used silica particles as a model system and compared sterically stabilized versus electrostatically stabilized silica particles—positively and negatively charged. Additionally, we studied the effect of hydration. Hydrated negatively charged silica particles and sterically stabilized silica particles form supraparticles. Conversely, dehydrated negatively charged silica particles and positively charged amine-coated particles form flat film-like deposits. Notably, the assembly process is different for all the four types of particles. The surface modifications alter (a) the contact line motion of the Ouzo droplet and (b) the particle–oil and particle–substrate interactions. These alterations modify the particle accumulation at the various interfaces, which ultimately determines the shape of the final deposit. Thus, by modulating the surface properties of the colloidal particles, we can tune the shape of the final deposit, from a spheroidal supraparticle to a flat deposit. In the future, this approach can be used to tailor the supraparticles for applications such as optics and catalysis, where the shape affects the functionality

Ethics education in pediatrics: Implementation and evaluation of an interactive online course for medical students

Introduction: The COVID-19 pandemic has catalyzed the development of online learning formats in virtually all areas of medical education. In pediatric ethics, online learning may not only substitute but also offer specific advantages over traditional classroom teaching. Many pediatricians rate their ethics education as poor and medical ethics education lacks evaluation, especially regarding the students’ needs. The aim of this project was to implement and evaluate a novel interactive distance learning approach to engage medical students in pediatric ethics education. Methods: An online ethics course was designed and delivered between May and June 2020. Core item of this course was a moderated, written forum discussion spanning several days. Evaluation was mixed methods. We evaluated the effectiveness of the course in terms of quality of the learning environment with a particular focus on relevance to students as well as interactive learning and reflective thinking. The Constructivist On-Line Learning Environment Survey (COLLES) was used to evaluate six different domains of the course. Data are presented as mean (standard deviation [SD]). The respective score range is 1-5, whereby a score of 4 or 5 means that the participants indicated the corresponding item as frequently or almost always present. Results: Responses were available from 104 (78.3%) of the 133 participating students. “Relevance” yielded a score of 4.17 (0.83), “reflective thinking” a score of 4.22 (0.83). “Interactivity” was scored 3.76 (0.99) and “tutor support” 4.72 (0.53). “Peer support” and “interpretation” scored 3.87 (0.98) and 4.49 (0.60), respectively. In qualitative analysis, students particularly valued the structure of the course, the relevance for their professional practice, their active participation and the incentive to reflective thinking. Students also indicated that this was an innovative and exciting format, which fills a current educational gap and should hence be continued beyond the pandemic. Conclusion: In conclusion, students actively engaged in online learning and perceived this ethics course as highly relevant for their professional practice

Super liquid repellent surfaces for anti-foaming and froth management

Wet and dry foams are prevalent in many industries, ranging from the food processing and commercial cosmetic sectors to industries such as chemical and oil-refining. Uncontrolled foaming results in product losses, equipment downtime or damage and cleanup costs. To speed up defoaming or enable anti-foaming, liquid oil or hydrophobic particles are usually added. However, such additives may need to be later separated and removed for environmental reasons and product quality. Here, we show that passive defoaming or active anti-foaming is possible simply by the interaction of foam with chemically or morphologically modified surfaces, of which the superamphiphobic variant exhibits superior performance. They significantly improve retraction of highly stable wet foams and prevention of growing dry foams, as quantified for beer and aqueous soap solution as model systems. Microscopic imaging reveals that amphiphobic nano-protrusions directly destabilize contacting foam bubbles, which can favorably vent through air gaps warranted by a Cassie wetting state. This mode of interfacial destabilization offers untapped potential for developing efficient, low-power and sustainable foam and froth management