Self-propelled droplet driven by Marangoni flow and its applications

We developed a new class of self-propelled droplet, which is made of water/ethanol dispersed in squalane/monoolein. During the propulsion, a spontaneous phase separation of the droplet occurs due to the release of ethanol and the uptake of monoolein. This phase separation can lead to the formation of a Janus droplet consisting of a water-rich phase and an ethanol-rich phase. The droplet moves as a pusher, which is determined by µPIV, before the phase separation and as a neutral squirmer after it. The time before phase separation can be quantified by a model. Additionally the quantitative analysis of the driving mechanisms before and after the phase separation are presented. Depending on salt concentration, added DNA or RNA can be controlled to accumulate either in the water-rich or in the ethanol-rich phase as a 'cargo'. This 'cargo' can be selectively delivered to a target controlled by hydrodynamic interaction and wettability. The same water/ethanol droplet in an ethanol-saturated squalane shows chemotaxic attraction. In this system, the droplet uptakes ethanol from squalane and droplets are attracted to each other supposably driven by this ethanol gradient, which is created by themselves. Large numbers of droplets can form patterns with different shapes, which is controlled by number density and vertical confinement.Wir haben eine neue Klasse von selbst-angetriebenen Tropfen entwickelt, die aus Wasser / Ethanol bestehen und in Squalan / Monoolein dispergiert sind. Während der Bewegung kommt es zu einer spontanen Phasentrennung des Tropfens aufgrund der Abgabe von Ethanol und der Aufnahme von Monoolein. Diese Phasentrennung kann zur Ausbildung eines Janus-Tropfens führen, der aus einer wasserreichen Phase und einer ethanolreichen Phase besteht. Der Tropfen bewegt sich vor der Phasentrennung als 'Pusher', der durch µPIV bestimmt wird, und danach als neutraler 'Squirmer'. Die Zeit vor der Phasentrennung kann durch ein Modell quantifiziert. Zusätzlich wird die quantitative Analyse der Antriebsmechanismen vor und nach der Phasentrennung vorgestellt. Abhängig von der Salzkonzentration kann die zugesetzte DNA oder RNA so gesteuert werden, dass sie sich entweder in der wasserreichen oder in der ethanolreichen Phase als "Ladung" ansammelt. Diese 'Ladung' kann selektiv an ein Ziel geliefert werden und durch hydrodynamische Wechselwirkung und Benetzbarkeit gesteuert werden. Der gleiche Wasser/Ethanol Tropfen in ethanolgesättigten Squalan zeigt eine chemotaktische Anziehungskraft. In diesem System nehmen die Tropfen Ethanol aus Squalan auf und die Tropfen werden vermutlich durch diesen Ethanolgradienten, der von ihnen selbst erzeugt wird, voneinander angezogen. Die Ansammlung vieler Tropfen können Muster bilden. Das Muster wird von der Tropfendichte und der vertikalen Ausdehnung kontrolliert

Abundance within Scarcity: Food Security in the Favelas of Brazil Menglin

Rapid urbanization has been accompanied by the expansion of unplanned, underserved neighborhoods with large concentrations of poor people, known as informal settlements.” Obtaining stable, fresh, and healthy food sources often requires people to spend more money, which can be a challenge for residents of informal settlements who may struggle to afford it. To create greater food security and decentralized food production, Abundance within Scarcity, Food Security in the Favelas of Brazil explores how urban agriculture can be strategically reintroduced into limited-open-space informal settlements and tap into the abundant potential of this seemingly barren” region. Finally, this project will build a more sustainable and resilient urban food loop system. This research zooms into Favelas, Brazil. The strategies focus on how to integrate urban agriculture with building gaps and rooftops to provide social, economic, and environmental benefits to informal communities by using pipelines to connect fragmented systems, working with gravity to transport resources, and using residual spaces

Loss aversion and the disposition effect around the world

JEL classification code: G11, G23In this article, we study how the performance of mutual fund affects investor’s behavior. I use mutual fund from around the world and analyse cross country differences on a sample of 45 countries. The study focuses on investigating the loss aversion, the disposition effect, and risk-aversion. Empirical results show that investors pay more attention on the fund which attracted larger fund flows previously, and loss aversion, disposition effect is significant among around half countries’ investors. Bigger funds are preferred by investors before financial crisis and this result changed after the crisis. The evidence is weak to conclude that whether the investors prefer older funds.Esta tese estuda como a performance passada dos fundos afecta os fluxos de investimento em fundos em vários países. É usada uma amostra internacional de fundos e são analisadas diferenças entre países em comportamentos tais como “ disposition effect”, aversão às perdas e aversão ao risco. São esperadas diferenças entre os vários países, países desenvolvidos e emergentes, europeus, asiáticos e americanos. Os resultados mostram evidencia de aversão ao risco, “disposition effect’ e aversão às perda na maioria dos países. Os resultados também mostram que os fluxos são autoregressivos e que os investidores preferiam fundos de grande dimensão antes da crise, mas os resultados mudaram depois da crise. A evidencia não é clara sobre se os investidores preferem fundos mais antigos ou mais recentes

The VirS/VirR two-component system regulates the anaerobic cytotoxicity, intestinal pathogenicity, and enterotoxemic lethality of Clostridium perfringens type C isolate CN3685.

Clostridium perfringens vegetative cells cause both histotoxic infections (e.g., gas gangrene) and diseases originating in the intestines (e.g., hemorrhagic necrotizing enteritis or lethal enterotoxemia). Despite their medical and veterinary importance, the molecular pathogenicity of C. perfringens vegetative cells causing diseases of intestinal origin remains poorly understood. However, C. perfringens beta toxin (CPB) was recently shown to be important when vegetative cells of C. perfringens type C strain CN3685 induce hemorrhagic necrotizing enteritis and lethal enterotoxemia. Additionally, the VirS/VirR two-component regulatory system was found to control CPB production by CN3685 vegetative cells during aerobic infection of cultured enterocyte-like Caco-2 cells. Using an isogenic virR null mutant, the current study now reports that the VirS/VirR system also regulates CN3685 cytotoxicity during infection of Caco-2 cells under anaerobic conditions, as found in the intestines. More importantly, the virR mutant lost the ability to cause hemorrhagic necrotic enteritis in rabbit small intestinal loops. Western blot analyses demonstrated that the VirS/VirR system mediates necrotizing enteritis, at least in part, by controlling in vivo CPB production. In addition, vegetative cells of the isogenic virR null mutant were, relative to wild-type vegetative cells, strongly attenuated in their lethality in a mouse enterotoxemia model. Collectively, these results identify the first regulator of in vivo pathogenicity for C. perfringens vegetative cells causing disease originating in the complex intestinal environment. Since VirS/VirR also mediates histotoxic infections, this two-component regulatory system now assumes a global role in regulating a spectrum of infections caused by C. perfringens vegetative cells