Sideways propelled bimetallic rods at the water/oil interface.

The motion of self-propelling microswimmers is significantly affected by confinement, which can enhance or reduce their mobility and also steer the direction of their propulsion. While their interactions with solid boundaries have already received considerable attention, many aspects of the influence of liquid-liquid interfaces (LLI) on active particle propulsion still remain unexplored. In this work, we studied the adsorption and motion of bimetallic Janus sideways propelled rods dispersed at the interface between an aqueous solution of hydrogen peroxide and oil.

Generation and Observation of Long-Lasting and Self-Sustaining Marangoni Flow.

When solute molecules in a liquid evaporate at the surface, concentration gradients can lead to surface tension gradients and provoke fluid convection at the interface, a phenomenon commonly known as the Marangoni effect. Here, we demonstrate that minute quantities of ethanol in concentrated sodium hydroxide solution can induce pronounced and long-lasting Marangoni flow upon evaporation at room temperature. By employing particle image velocimetry and gravimetric analysis, we show that the mean interfacial speed of the evaporating solution sensitively increases with the evaporation rate for ethanol concentrations lower than 0.

Nucleation of Porous Crystals from Ion-Paired Prenucleation Clusters.

Current nucleation models propose manifold options for the formation of crystalline materials. Exploring and distinguishing between different crystallization pathways on the molecular level however remain a challenge, especially for complex porous materials. These usually consist of large unit cells with an ordered framework and pore components and often nucleate in complex, multiphasic synthesis media, restricting in-depth characterization.

A zeolite crystallisation model confirmed by observation.

Probing nucleation and growth of porous crystals at a molecular level remains a cumbersome experimental endeavour due to the complexity of the synthesis media involved. In particular, the study of zeolite formation is hindered as these typically form in multiphasic synthesis media, which restricts experimental access to crystallisation processes. Zeolite formation from single phasic hydrated silicate ionic liquids (HSiL) opens new possibilities.

'Sweeping rods': cargo transport by self-propelled bimetallic microrods moving perpendicular to their long axis.

A possible application of self-propelling particles is the transport of microscopic cargo. Maximizing the collection and transport efficiency of particulate matter requires the area swept by the moving particle to be as large as possible. One such particle geometry are rods propelled perpendicular to their long axis, that act as "sweepers" for collecting particles.

Moving Electrode Impedance Spectroscopy for Accurate Conductivity Measurements of Corrosive Ionic Media.

A measurement cell for the use of accurate conductivity measurements of corrosive ionic media is presented. Based on the concept of moving electrode electrochemical impedance spectroscopy, exceptional measurement accuracy is achieved in a large conductivity range. Extensive testing with corrosive ionic media demonstrated the robust operation of the cell under harsh chemical conditions, up to temperatures of 130 °C.

Does Solution Viscosity Scale the Rate of Aggregation of Folded Proteins?

Viscosity effects on the kinetics of complex solution processes have proven hard to predict. To test the viscosity effects on protein aggregation, we use the crystallization of the protein glucose isomerase (gluci) as a model and employ scanning confocal and atomic force microscopies at molecular resolution, dynamic and static light scattering, and rheometry. We add glycerol to vary solvent viscosity and demonstrate that glycerol effects on the activation barrier for attachment of molecules to the crystal growth sites are minimal.

Miniaturized sensors for the viscosity and density of liquids--performance and issues.

This paper reviews our recent work on vibrating sensors for the physical properties of fluids, particularly viscosity and density. Several device designs and the associated properties, specifically with respect to the sensed rheological domain and the onset of non-Newtonian behavior, are discussed.

Viscosity sensing in heated alkaline zeolite synthesis media.

A quartz disc resonator operating in thickness shear mode was used for the in situ monitoring of the viscosity during zeolite crystal formation.