Distinguished EPJ Referees

EPJ E Highlight - Microgels’ behaviour under scrutiny

alt
Set of measured velocity profiles with Carbopol microgel.

A new study explores the counter-intuitive behaviour of a microgel composed of soft polymer blobs

Being a physicist offers many perks. For one, it allows an understanding of the substances ubiquitous in everyday industrial products such as emulsions, gels, granular pastes or foams. These are known for their intermediate behaviour between fluid and solid. Paint, for example, can be picked up on a paintbrush without flowing and spread under the stress of the brush stroke like a fluid. Baudouin Geraud and colleagues from the Light Matter Institute at the University of Lyon, France, have studied the flow of a microgel confined in microchannels. They have shown, in a study just published in EPJ E, that its behaviour under confinement differs from predictions based on standard theories. Indeed, its molecules are not only subjected to local forces, but also to neighbouring forces that affect its flow.

Read more...

EPJ E Call for papers: Thermal non-equilibrium phenomena in multi-component fluids

alt

EPJE is inviting submission for a new topical issue on “Thermal non-equilibrium phenomena in multi-component fluids”. Under thermal non-equilibrium conditions, multi-component fluids generally undergo component separation. This is termed thermodiffusion in molecular liquids, and thermophoresis in colloidal fluids. The precise physical principles underlying these phenomena are still not understood, and it is envisaged that a continuous flow of ideas between theoreticians, experimental scientists and researchers employing numerical methods is needed to achieve a deeper understanding. In order to provide an overview of the more recent advances in this intriguing area, Fabrizio Croccolo and Henri Bataller will guest edit this topical issue on physical systems outside thermal equilibrium. The deadline for submission is 30 June 2014. Read the full call for papers to learn more about the scope and submission details.

EPJ E Highlight - How proteins read meta DNA code

alt
Schematic representation of the model. © A. Fathizadeh et al.

Scientists have accurately calculated the sliding mechanism for deciphering the second genetic code written within the DNA base pair sequence

Three-quarters of the DNA in evolved organisms is wrapped around proteins, forming the basic unit of DNA packaging called nucleosomes, like a thread around a spool. The problem lies in understanding how DNA can then be read by such proteins. Now, Arman Fathizadeh, a physicist at Sharif University of Technology in Tehran, Iran, and colleagues have created a model showing how proteins move along DNA, in a paper just published in EPJ E.

Read more...

EPJ E Call for Papers: Irreversible dynamics

alt
Numerical simulation by Paul Manneville of plane Couette flow showing the coexistence of turbulent and laminar bands.

EPJE is now accepting submissions for a topical issue on “irreversible dynamics”, dedicated to Paul Manneville. The study of classical physics underwent a revolution in the 1970s-1980s thanks to seminal contributions by Ruelle, Takens, Pomeau and Manneville. The concurrent revival and extension of the theory of dynamical systems encompasses spatiotemporal chaos and coupled oscillator arrays. Applications to fluid dynamics range from pattern formation in convection, to the onset of turbulence in shear flows. The concurrent revival and extension of the theory of dynamical systems encompasses spatiotemporal chaos and coupled oscillator arrays. Applications to fluid dynamics range from pattern formation in convection, to the onset of turbulence in shear flows. Laurette Tuckerman or Patrice Le Gal, Guest Editors of this topical issue, extend a warm invitation to all researchers, with a wide interpretation of the field. The deadline for submission is July 1st 2013. The full call for papers can be found here

EPJ E Highlight - Gap geometry grasped

alt
Illustration of the sphere packing in two dimensions. © M. Maiti et al.

A new algorithm could help understand the structure of liquids, and how they flow through porous media

Theoretical physicist Moumita Maiti and colleagues at the Jawaharlal Nehru Centre for Advanced Scientific Research in Bangalore, India, have now implemented an algorithm for analysing void space in sphere packing, where the spheres need not all be the same size. This method, just published in EPJ E, could be applied to analyse the geometry of liquids present between multi-sized spheres that are akin to a model for porous material. This provides a tool for studying the flow of such fluids through porous material. More importantly, it can also be used to study the packing geometry of proteins.

Read more...

EPJ E Highlight - Liquid crystal’s chaotic inner dynamics

alt
Numerically obtained projection of the trajectory of liquid crystal molecules. © W. Jeżewski et al.

Scientists have unearthed a new dynamic process induced by strong electric fields in thin liquid crystal cells

Liquid crystal displays are ubiquitous. Now, Polish physicists have demonstrated that the application of a very strong alternating electric field to thin liquid crystal cells leads to a new distinct dynamic effect in the response of the cells. The theory of spatio-temporal chaos explains this effect. It was elucidated by Wojciech Jeżewski and colleagues from the Institute of Molecular Physics, Polish Academy of Sciences, in Poznań, Poland, and was just published in EPJ E. This effect has implications for the operation of liquid-crystal devices because their operation is based on the electro-optic switching phenomenon, subject to the newly discovered effect.

Read more...

EPJ E Highlight - Adhesion disturbed by noise

alt
Schematic illustrations of the pining and de-pinning events of the fibrils in contact with a rigid sphere. © M. K. Chaudhury and P. S. Goohpattader

A new model could ultimately help robotic fingers, made of a soft surface, manipulate small objects

Imagine a solid ball rolling down a slightly inclined ramp. What could be perceived as child’s play is the focus of serious theoretical research by Manoj Chaudhury and Partho Goohpattader, two physicists from Lehigh University, Bethlehem, Pensylvania, USA. Their study, which has just been published in EPJ E, has one thing in common with childhood behaviour. It introduces a mischievous idea, namely studying the effect of random noise, such as vibrations, on the ball. They found it could lower the energy barrier to set the ball in motion.

Read more...

EPJ E Colloquium - Hidden order in the liquid phase

alt
A snapshot of 2D spin liquid in a supercooled state. (Fig. 3 from the paper)

A two-order parameter model proposed to describe water-like anomalies, liquid-liquid transition, glass transition, crystal nucleation and quasicrystal formation within the same framework.

The liquid state of matter is far from being a perfectly disordered homogeneous state. In a Colloquium paper published in EPJ E, Hajime Tanaka argues that to achieve a better understanding of liquids, it is crucial to recognize that a liquid has a general tendency to exhibit local structural order, and that this order is intrinsic and universal to any liquid. In other words, there is a need for a new order parameter describing a low local free-energy configuration (this is a bond-orientational order parameter in many cases), in addition to a density order parameter.

Read more...

EPJ E Highlight - Enigmatic Nematics

alt
Ordered macroscopic states of active particles. © A. Baskaran, M. C. Marchetti

The law of hydrodynamics governing the way internally driven systems behave could explain their complex structure

Physicists use hydrodynamics to understand the physical mechanism responsible for changes in the long-range order of groups of particles. Particularly, Aparna Baskaran of Brandeis University, Massachusetts, USA, and Cristina Marchetti of Syracuse University, New York, USA, focused on ordered groups of elongated self-propelled particles. They studied the breakdown of long-range order due to fluctuations that render them unstable and give rise to complex structures, in a study just published in EPJ E within the topical issue on Active Matter.

Read more...

EPJ E Highlight - DNA’s double stranded stretch

alt
Understanding how DNA and proteins interact could come from a better grasp of DNA’s behaviour once stretched. © Svilen Milev

Models simulate what happens to DNA strands when stretched to the breaking point

Theoretical physicists like to play with very unconventional toys. Manoel Manghi from Toulouse University in France and his colleagues have adopted a seemingly playful approach to examining what happens to a double stranded molecule of DNA when it is stretched to the breaking point, in a study about to be published in EPJ E. Instead of using optical tweezers to stretch DNA as previously done in experimental settings, the authors focused on using a theoretical model to account for the structural deformations of DNA and determine how its mechanical characteristics could explain certain biological processes.

Read more...

Open calls for papers