2015 Impact factor 1.208
Atomic, Molecular, Optical and Plasma Physics

EPJ E Colloquium - Quantum effects are hot in supercooled water

The importance of nuclear quantum effects is well known for in solid systems at very low temperatures (T<10K). At higher temperature (above ~20-50K) usually the contribution of these quantum effects to structural relaxation is considered minor. Traditionally, researchers who study the structural relaxation in liquids and the glass transition neglect to consider quantum effects. However, it is becoming increasingly evident when studying light molecules (such as water) at temperature of 100-200K that quantum effects might play an important role in structural dynamics, and provide non-negligible contributions at temperatures as high as ambient.

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EPJE News - Welcome to the new Editor-in-Chief for Biological Physics

© François Graner

We are pleased to announce that François Graner joins Francesco Sciortino as co-Editor-in-Chief of EPJ E. He will lead and oversee the journal activities and editors in biological physics, with the aim to expand and strengthen the connections with the biological physics research community.

This is how Graner describes the benefits offered by the journal and its role in the community: “EPJ E is characterized by the outstanding quality of its editorial process and its panel of reviewers, something I already appreciated as an author. The journal plays an important role in maintaining high standards, as well as reinforcing the interface between soft condensed matter and biophysics. It is the perfect journal where to discuss the physical questions raised by current discoveries in biology and biophysics, and to report the related new physics methods and modeling.”

François Graner is Directeur de recherche at CNRS and Université Paris 7 "Denis Diderot". He is an accomplished expert on soft matter, statistical physics and biophysics.

We take this opportunity also to thank his predecessor Andreas Bausch for his excellent editorial service and dedication through the recent year.

EPJ E News - One year of Tips & Tricks

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It is the tricks that often form the commonality between researchers working in different fields. A little over a year ago the European Physical Journal E published the first papers in a new section called Tips and Tricks (T&T). The goal of this new section was simple: to provide a venue to publish a novel numerical recipe, sample preparation method, or experimental design.

Such details are often only briefly described in the scientific literature, passed only from student to student, or simply shared as a ‘personal communication’ between research groups. Sometimes such enabling techniques are not passed on at all. In all such cases, the scientific community as a whole is not able to use this knowledge to move forward. Moreover, while the research of some team may not be directly relevant to another, a computational method, experimental procedure, or sample cell design has the potential to be broadly transformative. We have found during our careers that various sample cell configurations, experimental designs, or sample preparation techniques were shared amongst our colleagues. In some cases the science became secondary to a particular technique, and more emails were shared describing a trick than citations earned on a paper where only a brief description was provided. The first year of EPJE's T&T has been exciting, with 13 papers that span many different tools and methods, from vesicles-on-a-chip to a three-body potential for molecular dynamics. You will find them all listed below with their respective links.

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EPJ E Highlight - Speed-dependent attraction governs what goes on at the heart of midge swarms

Trajectories of individual midges within a swarm recorded using high-speed cameras.

New study reveals swarm cohesion stems from an adaptive behaviour, where the faster individual midges fly, the stronger the gravitational-like force they experience

Ever wondered what makes the collective behaviour in insect swarms possible? Andy Reynolds from Rothamsted Research, UK, and colleagues at Stanford University, California, USA, modelled the effect of the attraction force, which resembles Newton’s gravity force, acting towards the centre of a midge swarm to give cohesion to their group movement. In a recent study published in EPJ E, their model reveals that the gravity-like attraction towards the heart of the swarm increases with an individual’s flight speed. The authors confirmed the existence of such an attractive force with experimental data.

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EPJ E Highlight - Molecular scale transporter with a twist, powered by liquid crystal defects

Twisting effect, called chirogyral, dictated by the handedness of the fibre in a vertical magnetic field.

Delivery of biochemical substances is now possible using a novel application of liquid crystal defects, forming a loop enclosing the substance travelling alongside twisted fibres

Defects that break the symmetry of otherwise orderly material are called topological defects. In solid crystals, they are called dislocations because they interrupt the regularly structured atom lattice. In contrast, topological defects called disclinations take the form of loops in liquid crystal of the nematic variety, whose elongated molecules look like a shoal of fish. New experiments supported by a theoretical model show how defects forming loops around twisted plastic fibres dipped in liquid crystal could be used for the transport of biochemical substances, when controlled by electric and magnetic fields. Published in EPJ E, these findings - achieved by Mallory Dazza from the Ecole normale supérieure Cachan, France, and colleagues - have potential applications in electro-optical micromechanical and microfluidic systems.

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EPJ E Review - Water and ionic liquids. Two very different solvents, two intriguing behaviours when nanoconfined

Confinement of liquids at the nanoscale gives rise to intriguing new chemical and physical behaviours and structures. Scientists are studying the phenomenon also because of its relevance to molecular biology (permeability of ion channels and protein stability), chemical engineering (nano-fluidic devices and molecular sieves) and geology (transport through porous rocks).

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EPJ E Highlight - Nanoparticles hitchhiking their way along strands of hair

Corrugated hair surface.

Massaging hair can help more quickly deliver nanoparticle-based treatment to the roots

In shampoo ads, hair always looks like a shiny, smooth surface. But for physicists peering into microscopes, the hair surface looks much more rugged, as it is made of saw-tooth, ratchet-like scales. In a new theoretical study published in EPJ E, Matthias Radtke and Roland Netz have demonstrated that massaging hair can help to apply drug treatment - encapsulated in nanoparticles trapped in the channels formed around individual hairs - to the hair roots. This is because the oscillatory movement of the massaging directs the way these particles are transported.

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EPJ E Highlight - How water can split into two liquids below zero

Representation of the diamond lattices formed by the particle studied.

Theoretical possibility of the coexistence of dual liquid states of matter in sub-zero water due to the origami-like stacking behaviour of microscale moleculesy

Did you know that water can still remain liquid below zero degrees Celsius? It is called supercooled water and is present in refrigerators. At even smaller temperatures, supercooled water could exist as a cocktail of two distinct liquids. Unfortunately, the presence of ice often prevents us from observing this phenomenon. So physicists had the idea of replicating the tetrahedral shape of water molecules - using DNA as a scaffold to create tetrahedral molecules - and thus removing the interference of ice formation. This approach allowed Simone Ciarella from the University of Rome, Italy, and his colleagues to confirm that, in theory, a dual liquid phase is possible in sub-zero water and any other liquids made of tetrahedral molecules. These results have been published in EPJ E. It is a great tale of how the underlying microscopic shape determines the overall macroscopic form.

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EPJ E Colloquium: Non-local fluctuation phenomena in liquids

Fluids in non-equilibrium steady states exhibit long-range fluctuations which extend over the entire system. They can be described by non-equilibrium thermodynamics and fluctuating hydrodynamics that assume local equilibrium for the thermophysical properties as a function of space and time.

The experimental evidence for the consistency between this assumption of local equilibrium in the equations and the non-local fluctuation phenomena observed is reviewed in this EPJ E colloquium paper

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EPJ E Highlight - Physicists reveal cocktails with Dr Jekyll and Mr Hyde features

False colour image of the long-range concentration fluctuations arising in a critical binary mixture.

Study explains how long-range effects in two-liquid cocktails have a bearing on the diffusion of their molecules, resulting in the coexistence of different characteristics within the same fluid

Disturbing a mix of two liquids can yield some surprising effects. For example, if one portion of the mixture is brought to a different composition, it starts a process called diffusion, which continues until the liquid mix reverts to the resting point, which physicists refer to as equilibrium. Understanding the underlying physical phenomenon matters because diffusion is ubiquitous in physical and biological processes, such as the transport of nutrients within our cells. Now, an Italian team of physicists has found that two-liquid cocktails display long-range correlations, both at equilibrium and when disturbed. This means that large regions with slightly different physical properties coexist within the same fluid. Outside the equilibrium condition, the authors explain, this is due to the coupling between the difference in concentration between different portions of the liquid and spontaneous fluctuations, which are also observed when the mix is at equilibrium. These findings have been published in EPJ E as part of the Topical Issue "Non-isothermal transport in complex fluids" by Fabio Giavazzi from the University of Milan, Italy, and colleagues. They imply that the long-range effects, observed when the mixture is not at equilibrium, need to be taken into account as an additional contribution to the effects observed when the mixture is at equilibrium, so as to understand the diffusion mechanisms.

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Editors-in-Chief
V. Buzek, H. Kersten and A.V. Solov'yov
It was my pleasure to be given the opportunity of being helpful in the scientific production process of EPJD. I enjoyed the experience as a referee for the journal: it was instructive, and its procedures were clear and simple. You can certainly count on my assistance for future similar appointments.

Luca Argenti

ISSN (Print Edition): 1434-6060
ISSN (Electronic Edition): 1434-6079

© EDP Sciences, Società Italiana di Fisica and Springer-Verlag

Conference announcements

POSMOL 2017

Magnetic Island, Queensland, Australia, 22-24 July 2017