31 research outputs found
DNA-coated Functional Oil Droplets
Many industrial soft materials often include oil-in-water (O/W) emulsions at
the core of their formulations. By using tuneable interface stabilizing agents,
such emulsions can self-assemble into complex structures. DNA has been used for
decades as a thermoresponsive highly specific binding agent between hard and,
recently, soft colloids. Up until now, emulsion droplets functionalized with
DNA had relatively low coating densities and were expensive to scale up. Here a
general O/W DNA-coating method using functional non-ionic amphiphilic block
copolymers, both diblock and triblock, is presented. The hydrophilic
polyethylene glycol ends of the surfactants are functionalized with azides,
allowing for efficient, dense and controlled coupling of dibenzocyclooctane
functionalized DNA to the polymers through a strain-promoted alkyne-azide click
reaction. The protocol is readily scalable due to the triblock's commercial
availability. Different production methods (ultrasonication, microfluidics and
membrane emulsification) are used with different oils (hexadecane and silicone
oil) to produce functional droplets in various size ranges (sub-micron, and ), showcasing the generality of
the protocol. Thermoreversible sub-micron emulsion gels, hierarchical
"raspberry" droplets and controlled droplet release from a flat DNA-coated
surface are demonstrated. The emulsion stability and polydispersity is
evaluated using dynamic light scattering and optical microscopy. The generality
and simplicity of the method opens up new applications in soft matter and
biotechnological research and industrial advances.Comment: 7 pages, 2 figures, 1 tabl
Using single-beam optical tweezers for the passive microrheology of complex fluids
Tesis de maestria de la facultad de ciencia y tecnologia de la Universidad Pedagogica Nacional
A database of the coseismic effects following the 30 October 2016 Norcia earthquake in Central Italy
We provide a database of the coseismic geological surface effects following the Mw 6.5 Norcia earthquake that hit central Italy on 30 October 2016. This was one of the strongest seismic events to occur in Europe in the past thirty years, causing complex surface ruptures over an area of >400 km 2. The database originated from the collaboration of several European teams (Open EMERGEO Working Group; about 130 researchers) coordinated by the Istituto Nazionale di Geofisica e Vulcanologia. The observations were collected by performing detailed field surveys in the epicentral region in order to describe the geometry and kinematics of surface faulting, and subsequently of landslides and other secondary coseismic effects. The resulting database consists of homogeneous georeferenced records identifying 7323 observation points, each of which contains 18 numeric and string fields of relevant information. This database will impact future earthquake studies focused on modelling of the seismic processes in active extensional settings, updating probabilistic estimates of slip distribution, and assessing the hazard of surface faulting
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Controlled Optofluidic Crystallization of Colloids Tethered at Interfaces.
Controlled Optofluidic Crystallization of Colloids Tethered at Interfaces.
We report experiments that show rapid crystallization of colloids tethered to an oil-water interface in response to laser illumination. This light-induced transition is due to a combination of long-ranged thermophoretic pumping and local optical binding. We show that the flow-induced force on the colloids can be described as the gradient of a potential. The nonequilibrium steady state due to local heating thus admits an effective equilibrium description. The optofluidic manipulation explored in this work opens novel ways to manipulate and assemble colloidal particles