Soft Matter Blog

Inspired by floating flowers, a passive pipetting mechanism allows for water to be grabbed with a flexible solid.

The technique was developed by a team led by Pedro Reis at Massachusetts Institute of Technology, USA, and co-workers in USA and France. The passive pipetting mechanism relies purely on the coupling of the elasticity of thin plates and the hydrodynamic forces at the liquid interface. By developing a theoretical model the team were able to design petal-shaped objects with maximum grabbing capacity.

Interested to know more? Read the full paper here: Pedro M. Reis, Jérémy Hure, Sungwan Jung, John W. M. Bush and Christophe Clanet, Soft Matter, 2010, DOI:10.1039/C0SM00895H

Eran Sharon and Efi Efrati from The Hebrew University of Jerusalem, Israel, discuss the mechanics of non-Euclidean plates in a Tutorial Review. Non-Euclidean plates are “stacks” of identical surfaces whose two-dimensional intrinsic geometry cannot be realized in a flat configuration. They can be generated via different mechanisms, such as plastic deformation, natural growth or differential swelling.

The review covers theoretical and experimental works that focus on shape selection in non-Euclidean plates and provides an overview of the governing principles of this field.

Read the Tutorial Review here:

Understanding gelator–gelator, fibre–fibre and fibre–solvent interactions is important for developing effective models for the dynamic self-assembly of gel-phase materials. A team lead by David Smith at the University of York, UK, have used Kamlet–Taft parameters to shed light on how the choice of solvent can mediate these interactions interactions. Fancy reading more? Download the full article here:

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Protein unfolding can lead to aggregation and is linked to protein conformational disorders. In order to learn more about the effect of hydrodynamic forces on protein unfolding Dave Dunstan and co-workers at University of South Australia and The University of Melbourne, Australia, have studied the unfolding of polypeptide helices under shear flow using real-time circular dichroism.

The extent of unfolding is dependent on the monomer size of the poly-L-lysine chains, as well as shear rate and the duration of its application. The shear-stability of the α-helical poly-L-lysine structure increased with increasing chain-length.

Interested to know more? Read the full article for free here:

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A team led by Hervé Duval at Ecole Centrale Paris, France, has reported the forced penetration of large hydrosoluble polymer chains through pores in a membrane.

The team measured the rejection coefficient Robs from retentate and permeate mean concentrations, and its corrected value R including polymer accumulation at the membrane. The variations of R as a function of solvent flow rate per pore in adimensional units collapse into the same curve well fitted by de Gennes’ “suction model”. This curve, universal for flexible polymers in good solvents, leads to an estimate of the critical penetration flow.

Interested to know more? Read the full article here:

Scientists at the Institute of Food Research, Norwich, UK, examined the growth of polymer mass of polygalacturonic acid-based multilayers using a range of acoustic and optical techniques.

The comparative study showed that the different techniques give quantitatively different results when used to measure what is nominally the same quantity (multilayer hydrated mass and polymer mass).

Interested to know more? Read the full article here: Marta Westwood, Timothy R. Noel and Roger Parker, Soft Matter, 2010, DOI:10.1039/C0SM00331J