Archive for March, 2012

Hot Paper: Molecular theory of weak polyelectrolyte thin films

Read for free until 25 April>>

The recently developed Molecular Theory of Weak Polyelectrolyte Gels was extended to include hydrogel films in this Hot Paper. The theory was used to study the behaviour of a weak polyelectrolyte gel constrained by a surface, to understand the structure and properties and how they differ when the gel is in contact with a water solution as compared to a hard wall. This information is important as thin hydrogel films are excellent candidates for the development of micro- and nano-sized applications requiring fast and stable stimuli-responsive materials.

Molecular theory of weak polyelectrolyte thin films
Gabriel S. Longo,  Monica Olvera de la Cruz and I. Szleifer
Soft Matter, 2012, 8, 1344-1354
DOI: 10.1039/C1SM06708G

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Congratulations to the Poster Prize winners at Aspen Winter Conference on Growth and Form: Pattern Formation in Biology

Congratulations to Sung Hoon Kang, Saverio Spagnolie and Karen Alim for winning the Soft Matter poster prizes at the 2012 Aspen Winter Conference on Growth and Form: Pattern Formation in Biology.

The titles of the winning posters were:

Sung Hoon Kang (Harvard University):
Pattern formation by self-organization of biologically-inspired fibrous surfaces
 
Saverio Spagnolie (Brown University) 
Helices, Waves, and Kinks: Hydrodynamic optimization of prokaryotic and eukaryotic flagella

Karen Alim (Harvard University), 
Contraction driven flow in the extended vein networks of Physarum polycephalum

 Photograph of the poster prize winners

From left to right: Sung Hoon Kang, Saverio Spagnolie, and Karen Alim

 

The conference was held 2nd – 7th January 2012 at Aspen Center for Physics, Aspen, Colorado, USA.

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Most read Soft Matter Reviews in 2011

Read the most popular Review Articles of 2011 for free today

Self-assembly of amphiphilic peptides
I. W. Hamley
Soft Matter, 2011, 7, 4122-4138
DOI: 10.1039/C0SM01218A

Stimulus responsive core-shell nanoparticles: synthesis and applications of polymer based aqueous systems
Olivier J. Cayre , Nelly Chagneux and Simon Biggs
Soft Matter, 2011, 7, 2211-2234
DOI: 10.1039/C0SM01072C

Cellulose nanowhiskers: promising materials for advanced applications
Stephen J. Eichhorn
Soft Matter, 2011, 7, 303-315
DOI: 10.1039/C0SM00142B

Polylactide (PLA)-based amphiphilic block copolymers: synthesis, self-assembly, and biomedical applications
Jung Kwon Oh
Soft Matter, 2011, 7, 5096-5108
DOI: 10.1039/C0SM01539C

Morphology of polymer-based bulk heterojunction films for organic photovoltaics
Matthias A. Ruderer and Peter Müller-Buschbaum
Soft Matter, 2011, 7, 5482-5493
DOI: 10.1039/C0SM01502D

Stimulus responsive nanogels for drug delivery
Liusheng Zha , Brittany Banik and Frank Alexis
Soft Matter, 2011, 7, 5908-5916
DOI: 10.1039/C0SM01307B

Covalently cross-linked amphiphilic block copolymer micelles
Cornelus F. van Nostrum
Soft Matter, 2011, 7, 3246-3259
DOI: 10.1039/C0SM00999G

PNIPAM microgels for biomedical applications: from dispersed particles to 3D assemblies
Ying Guan and Yongjun Zhang
Soft Matter, 2011, 7, 6375-6384
DOI: 10.1039/C0SM01541E

Nanoparticles with targeting, triggered release, and imaging functionality for cancer applications
Kristin Loomis , Kathleen McNeeley and Ravi V. Bellamkonda
Soft Matter, 2011, 7, 839-856
DOI: 10.1039/C0SM00534G

Hydrophilic and superhydrophilic surfaces and materials
Jaroslaw Drelich , Emil Chibowski , Dennis Desheng Meng and Konrad Terpilowski
Soft Matter, 2011, 7, 9804-9828
DOI: 10.1039/C1SM05849E

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2012 Soft Matter Lectureship: Nominations Closing Soon!

Nominations for the 2012 Soft Matter Lectureship close 31 March

Now is your chance to nominate an early career researcher who has made signficant contributions to the field of soft matter.

This annual Lectureship was established by the journal in 2009, and last year’s winner was Michael J. Solomon, University of Michigan Ann Arbor.

Qualification

To be eligible for the Soft Matter Lectureship, the candidate should be in the earlier stages of their scientific career, typically within 15 years of attaining their doctorate or equivalent degree, and will have made a significant contribution to the field.

Description

The recipient of the Lectureship will be asked to present a lecture three times, one of which will be located in the home country of the recipient. The Soft Matter Editorial Office will provide the sum of £1000 to the recipient for travel and accommodation costs.

The recipient will be presented with the Lectureship at one of the three lectures. They will also be asked to contribute a lead article to the journal and will have their work showcased on the back cover of the issue in which their article is published.

Selection

The recipient of the Lectureship will be selected and endorsed by the Soft Matter Editorial Board.

Nominations

Those wishing to make a nomination should send details of the nominee, including a brief C.V. (no longer than 2 pages A4) together with a letter (no longer than 2 pages A4) supporting the nomination, to the Soft Matter Editorial Office (softmatter-rsc@rsc.org) by 31 March 2012.  Self nomination is not permitted.

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Hot Paper: Stopping bacteria in their tracks

Read the following for free until 9 April:

Scientists from Belgium have worked out a way to study the mechanism of bacterial growth in slime and to control the growth by using a surfactant.

Bacteria multiply in bacterial slime, which is made up of polysaccharides. Attempts to stop this growth have been done in the past, by preventing the bacteria from signalling to each other. Now, the team has stopped growth by controlling the slime instead. They did this by studying the slime’s surface tension gradient and then adding a biosurfactant to provide a counter gradient, which stopped the bacterial spread. The bacterium they studied was Pseudomonas aeruginosa, a major cause of hospital acquired infections.

Graphical abstract: Surface tension gradient control of bacterial swarming in colonies of Pseudomonas aeruginosa

Surface tension gradient control of bacterial swarming in colonies of Pseudomonas aeruginosa
M. Fauvart ,  P. Phillips ,  D. Bachaspatimayum ,  N. Verstraeten ,  J. Fransaer ,  J. Michiels and J. Vermant
Soft Matter, 2012, 8, 70-76
DOI: 10.1039/C1SM06002C

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Embryonic polarisation

Growing up is a stressful process, particularly during embryonic development. The embryo starts out as a single symmetric cell. This cell can be considered as an active fluid bound by the cell membrane. Flow within this fluid leads to the build-up of stresses, the formation of patterns and asymmetries within the cell. Stephan Grill, at the Max-Planck Insitute for the Physics of complex systems and the Max-Planck Institute for Molecular Cell Biology and Genetics, Dresden, is interested in understanding how these flows lead to the polarisation observed in the Caenorhabditis elegans zygote.

Grill has shown that the changes in cell polarity are driven by myosin flow on the surface of the cell. The cortex can be considered as a dynamic self-contracting polymer gel surface, which lies underneath the cell membrane. This polymer gel layer behaves as a thin film of an active fluid. Passive advective transport of molecules – in this case myosin – embedded in the fluid can occur depending on the diffusivity and the flow velocities of the molecules.  In C. elegans the flows are fast enough that advection does play a role, influencing the distribution of the molecules as they diffuse on the cortex. Modelling shows that the passive advective transport by flow of such a mechanically active materials acts as a trigger for the segregation of the proteins, resulting in the polarisation of the zygote.

The movement of myosin across the surface of the cell also results in anisotropies in the cortical tension. These so called active stresses cause isolated sections of the cortex to self-contract. Grill has developed a novel method for locally determining the stresses, by cutting the cortex with a laser and measuring the recoil. The cortical tension is found to be greatest in the direction orthogonal to the flow.

Grill suggests that advective transport in active fluids is a general mechanism for the formation of patterns in developmental biology.

For more information see:

Goehring, N.W. et al., Polarization of PAR Proteins by Advective Triggering of a Pattern-Forming System, Science, 2011.

Bois, S, et al., Pattern Formation in Active Fluids, Phys. Rev. Lett., 2011.

Mayer. M, et al., Anisotropies in cortical tension reveal the physical basis of polarizing cortical flows, Nature, 2010.

The image above is taken from: Cyclodextrin/dextran based drug carriers for a controlled release of hydrophobic drugs in zebrafish embryos, Soft Matter, 2011, and shows C. elegans embryo 30hrs after fertilisation.

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Hot Paper: Enhancing tracer diffusivity by tuning interparticle interactions and coordination shell structure

Read the following for free until 30 March:

The extent to which long-time dynamics of a single tracer particle can be enhanced were tested using a combination of simulations and liquid-state theory in this hot paper. It was found that adding a soft repulsion to interactions with neighbouring particles of a hard-sphere-like tracer particle could significantly enhance the long-time diffusivity.

Graphical abstract: Enhancing tracer diffusivity by tuning interparticle interactions and coordination shell structure

Enhancing tracer diffusivity by tuning interparticle interactions and coordination shell structure
James Carmer ,  Gaurav Goel ,  Mark J. Pond ,  Jeffrey R. Errington and Thomas M. Truskett
Soft Matter, 2012, Advance Article
DOI: 10.1039/C1SM06932B

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