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2 0 1 2 / 2 0 1 3 S o f t m a tt e r w o r l d . o r g

• SEM image of large-scale biaxial bimetallic nanopetals • Ajay Gopinathan, University of California, Merced.

September | 2012 | #44

Complex Materials Laboratory at Trondheim University

Prof. Jon Otto Fossum’s lab spe-cializes in soft and complex matter with an emphasis on understanding nanolayered silicates, i.e. clays. Clays are an inexpensive, abundant class of materials that demonstrate fascinating complex physical phenomena. The Fossum lab focuses on gaining new understanding of the basic physical properties and processes in soft ma-terials. Their work ranges from self-as-sembly on the nano-scale, looking at the liquid crystalline properties of clay particles, clay-based nano-capsules for drug delivery, and CO2 capture, and the interaction of clay particles with fluid droplets, to more macro-scopic systems including porous me-dia, pattern formation in gels and ava-lanches in clays.

The lab employs a wide variety of experimental characterization tech-niques in their experimental work, including thermal gravimetric analy-sis, differential scanning calorimetry, electrorheology, magnetorheology, in-situ small angle light scattering rhe-ometry, atomic force microscopy, and x-ray scattering.

Recent highlights from the group’s work include new papers on the “Guided self assembly of nanostruc-tured titanium dioxide” in the jour-nal Nanotechnology, a publication in Langmuir on “X-ray studies of Carbon Dioxide Intercalation in a Clay at Near-Ambient Conditions“, and a report on the “Swelling transition of a clay in-duced by heating” published in Scien-tific reports.

Prof Fossum has lectured widely on the physical properties of clays, their structures and flow properties and is the leader of NORDSOFT, a new soft matter research network in Norway and across Scandinavia. The labora-tory is also an integrated part of a Co-ordinated Research Team in Norway (COMPLEX) which involves people and labs located at NTNU as well as at University of Oslo (UiO) and at Insti-tute for Energy Technology (Ife) near Oslo.

The group has an excellent web-site where you can learn more about this group’s work and the group team members.

Dear Soft Matter Colleagues.

Welcome to the September issue of Soft Matter World. This month's feature article reports on research in clay-based materials from Prof. Jon Otto Fossum's lab at the Norwegian University of Science and Technology. We also present a simulation of the behavior of responsive micro-swimmers and a study characterizing the structure of ice-cream, an inter-esting multi-phase system.

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Designing maneuverable micro-swimmers actuated by responsive gel Hassan Masoud , Ben jamin I . B ingham and A lexander A lexeev. Sof t Matter, 2012,8 , 8944-8951. DOI : 10 .1039/C2SM25898F. 23 Ju l 2012

Controllable micro-swimmers are devices that can potentially navigate through viscous environments carry-ing a payload. Although such a device may have the potential to transform lab-on-a-chip devices, drug delivery, and microsurgery their design and development is a challenge. In this paper, researchers from the Georgia Institute of Technology have used a hybrid computational approach to model the swimmer, integrating a lat-tice Boltzmann model and a lattice spring model to simulate the motion of a micro-swimmer in a low-Reynolds number environment.

The simulated micro-swimmer con-sists of a gel cube with two rigid pro-pulsive flaps on the opposite faces of the cube and a pliable steering flap attached to the middle of the front

face. The gel body and propulsive flaps swell or contract periodically in response to an external stimulus, such as a magnetic field, light source or a change in temperature, and propel the swimmer forward. The steering flap is designed to bend in response to an external stimulus.

Results show the swimmer’s speed and efficiency depends on the pro-pulsive flap aspect ratio and body stiffness. The forward power gener-ated by the swimmer is a function of the deflection angle of the flaps, which depends on the change in size of the swimmer’s body. A design with a short, elastic steering flap generated the fastest swimmer turning due to an op-timal combination of sidewise hydro-dynamic and asymmetric drag forces.

Read the full paper in Soft Matter.

3D-characterization of three-phase systems using X-ray tomography: tracking the microstructural evolution in ice creamB . R . P inzer, A . Medebach , H. J . L imbach , C . Dubo is , M. Stampanon i and M. Schneebe l i . Sof t Matter, 2012, 8 , 4584

Food science is a rich area of study for soft matter scientists with many foodstuffs exhibiting complicated phase behavior and microstructure. In the food industry there is great inter-est in the effects of freezing on food microstructure as this will ultimately affect texture and sensorial percep-tion.

In this paper the authors have used an x-ray tomography technique to probe the microstructure of ice-cream. Ice cream consists of four dif-ferent phases, unfrozen material, air bubbles, ice crystals and fat particles. The experimenters used iodine as a contrast agent to measure the three dimensional distribution of the air, ice and unfrozen fractions with 6μm reso-lution.

The material’s structure was charac-terized as the temperature was cycled between lower and higher tempera-

tures designed to mimic the condi-tions of freezing and thawing (a heat shock protocol). When the experi-menters tracked air bubbles and ice crystals in the material, they observed dramatic coarsening and ice crystal growth to be the dominant mecha-nisms for structural change.

To read more visit Soft Matter at RSC Publishing.

Representative 3D tomography images from the paper show-ing contrast between the different phases.

Snapshots illustrating swimmer motion during one period of the gel body oscillations. The colors represent the material strain ε. Green cones represent velocity vectors in the x plane through the middle of the swimmer body.

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submission requested

2013 Calendar softmatterworld Competition

This is the second call to submit your research images for the 2013 Soft Matter World Calendar Competition. This December, 12 winners will be selected and have their im-ages printed on a custom Soft Matter World Calendar. We will not consider any images without your permission so if you were previously a featured group please submit im-ages and get involved! Imagine your own artistic Soft Mat-ter images in a 2013 calender.

Please include a short description, date and due author-ship for each image. The images should be 300+ pixels/inch and emailed to: gallery@softmatterworld.org

If you are an avid reader of the newsletter, please submit an image and also consider contributing to the soft matter world gallery. Click here to see some of our current im-ages.

________________________________ Biointerface 2012

The Surfaces in Biomaterials Foundation organizes the BioIn-terface conference annually. This is the leading applied technical conference focused on innova-tive biomaterial science and en-gineering applications. The up-coming BioInterface Workshop and Symposium will be hosted at University College Dublin, in Dublin, Ireland, October 23 – 25, 2012.

Please plan to attend and to contribute to the confer-ence by submitting a poster now, the deadline for students is Friday, September 14, 2012.

Visit the website to read more.

ConferenceListings dates and deadlnes

Biophysical Society 57th Annual Meeting

� Abstract Submission - October 1st

APS 4-Corners Regional Meeting � Abstract Submission - September 21s

� Online Registration - October 15th JCNS Workshop 2012

� Payment - September 10th Biointerface 2012

� Student Poster Submission - September 14th

New book:"Fundamentals of Soft Matter Science"

"Fundamentals of Soft Matter Sci-ence" by Linda S. Hirst is a new under-graduate-level book aimed at intro-ducing a wide audience of students and scientists to the field of soft mat-ter.

The book covers a broad range of topics including liquid crystals, sur-factants, colloids, polymers and soft biomaterials with an emphasis on modern experimental techniques.

The book will be available for purchase in early No-vember from Taylor and Francis (CRC Press).

We hope you enjoy browsing softmatterworld.org and come back soon

Linda S. Hirst and Adam Ossowski.

SoftMatterWorld.org