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Archive for the ‘Hot Article’ Category

Hot Article: The mechanics of non-Euclidean plates

18 Oct 2010

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:

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Hot Article: Solvent–gelator interactions—using empirical parameters to better understand the self-assembly of gel-phase materials

15 Oct 2010

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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Hot Article: Alpha-Helix Unfolding in Simple Shear Flow

14 Oct 2010

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.

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Hot Article: Suction of hydrosoluble polymers into nanopores

29 Sep 2010

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:

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Hot Article: The characterisation of polygalacturonic acid-based layer-by-layer deposited films using a quartz crystal microbalance with dissipation monitoring, a dual polarization interferometer and a Fourier-transform infrared spectrometer in attenuated total reflectance mode

28 Sep 2010

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

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Hot Article: Dynamics of a deformable self-propelled particle in three dimensions

24 Sep 2010

Japanese scientists at Kyoto University have studied the dynamics of a self-propelled particle in three dimensions by solving the time-evolution equations for the center of mass and a tensor variable characterizing deformations around a sphere.

There are successive bifurcations in the dynamics caused by changing the parameters. A straight motion becomes unstable and a rotating motion on a plane appears. After this rotating motion becomes unstable, a helical motion occurs. A linear stability analysis of these solutions is carried out to determine the bifurcation thresholds, which is in a good agreement with the numerical results.

Read the full paper: Tetsuya Hiraiwa, Kyohei Shitara and Takao Ohta, Soft Matter, 2011, DOI:10.1039/C0SM00856G

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Hot Article: Cassie–Wenzel and Wenzel–Cassie transitions on immersed superhydrophobic surfaces under hydrostatic pressure

22 Sep 2010

The collapse transition due to water pressure on superhydrophobic surfaces is reversible in the right conditions.

Pontus Forsberg, Fredrik Nikolajeff and Mikael Karlsson from Uppsala University, Sweden, probed the collapse transition on superhydrophobic surfaces completely covered by water, where the air film formed on the surface is closed. The team found that the closed film of trapped air helps stabilise the Cassie state at low pillar densities and that the effect of a small change in pillar sidewall angle can drastically change the collapse behaviour. They also observed the reverse transition, from Wenzel to Cassie state, on densely pillared surfaces at low water pressure.

Read the full article here: Pontus Forsberg, Fredrik Nikolajeff and Mikael Karlsson, Soft Matter, 2010, DOI:10.1039/C0SM00595A

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Hot Article: Heterogeneity of the electrostatic repulsion between colloids at the oil–water interface

21 Sep 2010

Electrostatic interactions are a common and important form of interaction in soft matter. In this paper Bum Jun Park, Jan Vermant and Eric M. Furst measure the interactions between colloids at a decane-water interface using optical tweezers. The team also used Monte Carlo simulations to understand the effect of heterogeneity on the equilibrium suspension structure.

The electrostatic repulsive force has the expected dependence on particle separation for a dipole–dipole interaction but exhibits a distribution of magnitudes in which the force depends on the particle pairs tested and sample preparation method.

Read the full article here: Bum Jun Park, Jan Vermant and Eric M. Furst, Soft Matter, 2010, DOI:10.1039/C0SM00485E

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Hot Article: Lipid bilayers on topochemically structured planar colloidal crystals: a versatile platform for optical recording of membrane-mediated ion transport

17 Sep 2010

A team of US Scientists from the University of California, Davis, have demonstrated how membrane architecture and a functionalized colloidal crystal can be used for optical measurement of transmembrane ionic transport.

The team led by Atul Parikh say their experimental design also opens practical possibilities for parallel measurements that may be useful for the characterization of stochastic transport processes and high-throughput measurements.

Read the full article here:
Adrian M. Brozell, Sean Inaba and Atul N. Parikh, Soft Matter, 2010, DOI:10.1039/C0SM00535E

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Hot Article: Injectable solid hydrogel: mechanism of shear-thinning and immediate recovery of injectable β-hairpin peptide hydrogels

10 Sep 2010

A team led by Darrin Pochan, University of Delaware, Newark, USA, studied hydrogel behavior during and after stress-induced flow to discover the underlying mechanisms of the gel shear-thinning and healing processes.

Hydrogel solids have significant potential for use in injectable therapies as they stay localized at the region of injection but don’t require surgery.

Results of structural analysis during flow were related to bulk rheological behavior and indicated gel network fracture into large (>200 nm) hydrogel domains during flow. After cessation of flow the large hydrogel domains are immediately percolated which immediately reforms the solid hydrogel…

Read the full article here: Congqi Yan, Aysegul Altunbas, Tuna Yucel, Radhika P. Nagarkar, Joel P. Schneider and Darrin J. Pochan, Soft Matter, 2010, DOI: 10.1039/C0SM00642D

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