Distinguished EPJ Referees

EPJ E Highlight - Elucidating biological cells’ transport mechanisms

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Image of mitochondria observed by transmission electron microscopy. © K. Hayashi et al.

A new study focuses on the motion of motor proteins in living cells, applying a physicist’s tool called non-equilibrium statistical mechanics

Motion fascinates physicists. It becomes even more intriguing when observed in vivo in biological cells. Using an ingenious setup, Japanese scientists have now calculated the force of molecular motors acting on inner components of biological cells, known as organelles. In this study, the focus is on mitochondria—akin to micrometric range cellular power plants—travelling along microtubules in a cell. Published in EPJ E by Kumiko Hayashi, from Tohoku University, Sendai, Japan, these findings could contribute to elucidating the transport mechanism in biological cells by multiple motors.

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EPJE Colloquium - Electrification of wind-blown sand

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A new Colloquium in EPJE by Xiao-Jing Zheng introduces and reviews the fundamental laws of the electrification of wind-blown sand and their influence, and highlights the challenges in this field.

The electrification of wind-blown sand is a typical complex system characterised by nonlinearity, randomness, multi-field coupling between thermal diffusion, E-fields and sand movements, as well as trans-scale processes with multi-phase media. Owing to the complex mechanism and the influence of the electrification of wind-blown sand [19], a number of issues remain poorly understood. These include: (1) why sand particles get charged during wind-blown sand movements; (2) how many electric charges a sand particle acquires; (3) why the electric polarity of sand particles is related to the particles’ size; (4) what the change law of wind-blown sand E-fields is, and (5) how to predict the intensity and influence of wind-blown sand E-fields.

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EPJ E Highlight - Levitating foam liquid under the spell of magnetic fields

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Image of the surface of the foam chamber under experimental study. © N.Isert et al.

No better solution to studying ever-draining foams than applying a strong magnetic field to keep the liquid in the foam at a standstill by levitating its water molecules

Foams fascinate, partly due to their short lifespan. Foams change as fluid drains out of their structure over time. It is precisely their ephemeral nature which has, until now, prevented scientists from experimentally probing their characteristic dynamics further. Instead, foams have often been studied theoretically. Now, Nathan Isert from the University of Konstanz, Germany and colleagues, have devised a method of keeping foams in shape using a magnet, which allows their dynamics to be investigated experimentally, as recently described in EPJ E.

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EPJ E Highlight - Uncovering liquid foams bubbly acoustics

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Typical image of a bubble raft analysed for bubble-size determination. © J.Pierre et al.

First study to shows specific sounds’ speed and attenuation characteristics in liquid foam, opens the door to new type of sound proofing material

Liquid foams fascinate toddlers singing in a bubble bath. Physicists, too, have an interest in their acoustical properties. Borrowing from both porous material and foam science, Juliette Pierre from the Paris Diderot University, Paris, France and her colleagues studied liquid foams. They used an impedance tube to measure the velocity and attenuation of acoustic waves in liquid foams in a broad frequency range. The study published in EPJ E is a first in the literature. It could help in assessing any liquid foam’s bubble size or in designing the optimal foam structure for sound proofing.

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EPJ E Highlight - Understanding the evolution of lungs through physical principles

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Small bronchia, bronchioles (in white) and pulmonary arteries and veins in the human lung. Courtesy of E. R. Weibel

How fluid dynamics and transport shaped the structure of our lungs in the course of evolution.

Two French physicists, Bernard Sapoval and Marcel Filoche from École Polytechnique in Palaiseau, France, suggest in a study published in EPJ E how evolution has shaped our lungs through successive optimisations of physical parameters such as conservation of energy and speed of delivery.

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EPJ E Highlight - Greater desertification control using sand trap simulations

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Spatial distribution of sand particles in the test straw checkerboard barrier.

A new simulation will help improve artificial sand-control measures designed to help combat desertification by identifying their weaknesses

In the fight against desertification, so-called straw checkerboard barriers (SCB), consisting of half -exposed criss-crossing rows of straw of wheat, rice, reeds, and other plants, play a significant role. The trouble is that our understanding of the laws governing wind-sand movement in SCB and their surrounding area is insufficient. Now, Ning Huang and colleagues from Lanzhou University in China, have performed a numerical simulation of the sand movement inside the SCB, described in a paper just published in EPJ E. Their country is particularly affected by desertification, which affects 18% of its territory. The results will help us to understand sand fixation mechanisms that are relevant for sandstorm and land-desertification control.

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EPJE news: Julia Yeomans awarded the EPJE P.-G. De Gennes lecture prize

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Julia Mary Yeomans.

The 2013 edition of the EPJE Pierre Gilles De Gennes prize has been awarded by the EPJE editors to Professor Julia Yeomans of the University of Oxford, UK. This initiative of the European Physical Journal E - Soft Matter and Biological Physics takes the name from the illustrious Nobel laureate who founded the journal.

Professor Yeomans has been nominated for her profound contribution to the study of the dynamical behaviour of complex and active liquids in confined geometries. She is an expert in theoretical and computational physics, particularly statistical physics, hydrodynamics, soft condensed matter and biological physics. Among her current research interests are microswimmers, active systems, liquid crystals and the interactions of fluids with structured surfaces.

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EPJ E Highlight - Protein surfaces defects as drug targets

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The average mobility of the water molecules. Figure 2 from Ariel Fernandez (2010), Transformative concepts for drug design: Target Wrapping, Springer-Verlag, Berlin.

Drug designers now have a new way of designing drug candidates suitable for dislodging unstable water molecules located in the defects at the surface of target proteins

New research shows a physical characterisation of the interface of the body’s proteins with water. Identifying the locations where is it easiest to remove water from the interface of target proteins could constitute a novel drug design strategy. The candidate drugs would need to be engineered to bind at the site of the protein where interfacial water is most easily dislodged. These findings, based on the work of María Belén Sierra from the National University of the South, in Bahia Blanca, Argentina and colleagues, recently published in EPJ E.

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EPJ E Highlight - Heterogeneous nanoblocks give polymers an edge

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Examples of different nanoscale patterns that block copolymers can adopt.

Study uncovers the effects of size variation in nanoscale blocks used in polymer mixes on their underlying architecture and inherent characteristics

Building structures by mixing lego bricks of two different sizes is child’s play. However, studying polymers endowed with an alternating nanostructure made of heterogeneous blocks is anything but straightforward. Theoretical physicist Mark Matsen, based at the University of Reading, UK, studies polymer mixes consisting of two-fold (AB) and three-fold (BAB) combinations of two types of nanoscale blocks. He has shown, in a study published in EPJ E, that the underlying heterogeneity of the blocks can cause polymers to switch to different nanoscale patterns and therefore display different properties. Numerous applications based on etching patterns on substrates, such as electronics, computer chips, and membranes endowed with a specific function, can benefit from such research.

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EPJ E Highlight - Cells move as concentration shifts

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Schematic representation of a top-view of the cell containing the colony.

Sheets of biological cells move along the organs they cover by altering the external concentrations of specific molecules, thanks to an absorption mechanism on the cells’ surface

What do wound healing, cancer metastasis, and bacteria colonies have in common? They all involve the collective displacement of biological cells. New research sheds some new light on the physical mechanisms provoking the displacement of a sheet of cell, known as an epithelium. It typically covers our organs including the stomach and intestine, as well as our epidermis. In a paper which appeared in EPJ E, Martine Ben Amar from Pierre and Marie Curie University in Paris explains the importance of understanding the displacement of the epithelium as a means of influencing the biological process involved in healing. And, ultimately, of helping to minimise scars.

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