Proceedings

EPJ E Colloquium - European Space Agency experiments on thermodiffusion of fluid mixtures in space

Diffusive processes are ubiquitous in daily life and in natural processes, playing a key role in the transformation and mixing of fluid mixtures, and there is considerable scientific and industrial interest in such mixing processes. One consequence of diffusion is the development of non-equilibrium fluctuations in liquid mixtures, particularly when fluids are exposed to a thermal gradient. This is easier to observe in weightlessness, as gravity dampens this phenomenon on Earth especially for large fluctuations.

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EPJE Topical Review: Lattice Boltzmann methods and active fluids

Active fluids are living matter or biologically inspired systems, consisting of self-propelled units that burn stored or ambient energy and turn it into work, eventually giving rise to systematic movement. In a new Topical Review paper published in EPJE, authors from groups in Bari (University of Bari, INFN, and the Istituto Applicazioni Calcolo, CNR) and the Center for Life Nano Science, La Sapienza, Rome describe the use of Lattice Boltzmann Methods (LBM) in the study of large scale properties of active fluids.

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EPJ E Highlight - No assumptions needed to simulate petroleum reservoirs

Modelling reservoirs: easier than we thought? https://commons.wikimedia.org/wiki/ File:Contour_map_software_screen_ snapshot_of_isopach_map_for_ 8500ft_deep_OIL_reservoir_with_ a_Fault_line.jpg

Hydrocarbons trapped within porous media are easier to model with computer simulations than researchers previously assumed – a discovery that opens up new possibilities for thermodynamics research.

Hidden deep below our feet, petroleum reservoirs are made up of hydrocarbons like oil and natural gas, stored within porous rock. These systems are particularly interesting to physicists, as they clearly show how temperature gradients between different regions affect the gradients of fluid pressures and compositions. However, because these reservoirs are so hard to access, researchers can only model them using data from a few sparse points, meaning many of their properties can only be guessed at. In a new study published in EPJ E, physicists from France and Vietnam, led by Guillaume Galliero at the University of Pau, have found that this guesswork actually isn’t necessary. They show that if the right choices are made when constructing models, no assumptions are needed in order to calculate the impact of temperature gradients on pressure and composition gradients.

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EPJ E Highlight - Dowsing for electric fields in liquid crystals

Following the change in orientation of the molecules in the dowser texture yields a shape that resembles the wooden dowsing rods used in previous centuries to locate groundwater. Left: © Pawel Pieranski, Right: https://en.wikipedia.org/wiki/ Dowsing#/media/File: 18th_century_dowser.jpg

The orientation of the ordered molecules that make up nematic liquid crystals can change under electric fields, and can be used to detect subtle electrical effects.

You may not know it, but you probably spend several hours a day looking at nematic liquid crystals; they are used in virtually every smartphone, computer and TV screen. They are liquids composed of elongated molecules, which in some situations can be oriented in a curious way termed the 'dowser texture', which is sensitive to external conditions. Physicists Pawel Pieranski of the Universite Paris-Sud, Paris, France and Maria Helena Godinho of Universidade Nova de Lisboa, Lisbon, Portugal have now published a paper in EPJ E that shows that the dowser texture responds to electric fields in different ways in different nematic materials.

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EPJ E Highlight - Collagen fibres grow like a sunflower

Phyllotactic pattern with concentric circles.

A new study suggests the pattern of fibres in tissues is similar to the petals of a flower

Collagen fibrils are a major component of the connective tissues found throughout the animal kingdom. The cable-like assemblies of long biological molecules combine to form tissues as varied as skin, corneas, tendons or bones. The development of these complex tissues is the subject of a variety of research efforts, focusing on the steps involved and the respective contributions of genetics and physical chemistry to their development. Now, two researchers at the Universite Paris-sud in Orsay, France, have shed new light on how complex collagen fibrils form. In a new study published in EPJ E, the authors focus on one of the hierarchical steps, in which molecules spontaneously associate in long and dense axisymmetric fibres, known as type I collagen fibrils.

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EPJ E Highlight - How red blood cells behave in crowded vessels

Red blood cells flowing through a blood vessel. https://pixabay.com/illustrations/blood-cells-red-medical-medicine-1813410/

A new model of red blood flowing through narrow capillaries shows that the cells change shape and alignment, allowing plasma to flow down the sides

Blood consists of a suspension of cells and other components in plasma, including red blood cells, which give it its red colour. When blood flows through the narrowest vessels in the body, known as the capillaries, the interactions between the cells become much more important. In a new study published in EPJ E, a team of researchers led by Ignacio Pagonabarraga from the University of Barcelona, Spain, has now developed a mathematical model of how red blood cells flow in narrow, crowded vessels. This could help design more precise methods for intravenous drug delivery, as well as 'microfluidic chips' incorporating artificial capillaries, which could offer faster, simpler and more precise blood-based diagnoses.

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EPJ E Highlight - Liquid jets break up more readily on a substrate

Filaments.

Using computational models to investigate how liquid drops behave on surfaces

Whether we're aware of it or not, in day-to-day life we often witness an intriguing phenomenon: the breakup of jets of liquid into chains of droplets. It happens when it rains, for example, and it is important for inkjet printers. However, little is known about what happens when a liquid jet, also known as a liquid filament, breaks up on top of a substrate. According to a new study, the presence of a nearby surface changes the way the filament breaks up into smaller droplets. In a new paper published by Andrew Dziedzic at the New Jersey Institute of Technology in Newark, New Jersey, USA, and colleagues in EPJ E, computer simulations are used to show that a filament is more likely to break up near a surface.

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EPJ E Topical Review: Gyrotactic phytoplankton in laminar and turbulent flows: A dynamical systems approach

Biological and geophysical fluids host a sea of microorganisms many of which are motile. An often overlooked aspect of the life of such microorganisms is that the fluids where they are suspended are not still but flowing. In this brief review published in EPJ E, the authors aim to describe some of the interesting phenomena that can emerge due to the modification of the microorganisms' swimming direction by velocity gradients, which affect both the individual motion of microorganisms and their spatial distribution in dilute suspensions.

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EPJE Topical Review: how capillarity drives the movement of small objects

Moving around small objects using capillary forces is a phenomenon that has stimulated scientists trying to understand the fundamental mechanisms at play. It is also important for many industrial, technological and analytical processes, for example micro-fluidics, oil and gas displacement, mineral flotation, miniature robot and biomechanics. In this EPJ E topical review article Jianlin Liu and Shanpeng Li present a critical review of capillarity-driven migration in which many examples are presented and explained. The small objects in question are non-deformable objects, such as particles, rods, disks and metal sheets as well as soft objects, such as droplets and bubbles. The authors clarify some misunderstandings on the conventional views on these systems.

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EPJ E Highlight - How ion adsorption affects biological membranes’ functions

Coverage of the lipid bilayer membrane surface with ions, as a function of pH.

A new study presents new models describing how the adsorption of calcium, barium and strontium ions onto biological membranes may affect the functions of cells

Ions with two positive electrical charges, such as calcium ions, play a key role in biological cell membranes. The adsorption of ions in solution onto the membrane surface is so significant that it affects the structural and functional properties of the biological cells. Specifically, ions interact with surface molecules such as a double layer of lipids, or liposomes, formed from phosphatidylcholines (PC). In a new study published in EPJ E, Izabela Dobrzyńska from the University of Białystok, Poland, develops a mathematical model describing the electrical properties of biological membranes when ions such as calcium, barium and strontium adsorb onto them at different pH levels. Her works helps shed light on how ion adsorption reduces the effective surface concentration of add-on molecules with a specific function that can take part in biochemical reactions. These factors need to be taken into account when studying the diverse phenomena that occur at the lipid membrane in living cells, such as ion transport mechanisms.

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This was our first experience of publishing with EPJ Web of Conferences. We contacted the publisher in the middle of September, just one month prior to the Conference, but everything went through smoothly. We have had published MNPS Proceedings with different publishers in the past, and would like to tell that the EPJ Web of Conferences team was probably the best, very quick, helpful and interactive. Typically, we were getting responses from EPJ Web of Conferences team within less than an hour and have had help at every production stage.
We are very thankful to Solange Guenot, Web of Conferences Publishing Editor, and Isabelle Houlbert, Web of Conferences Production Editor, for their support. These ladies are top-level professionals, who made a great contribution to the success of this issue. We are fully satisfied with the publication of the Conference Proceedings and are looking forward to further cooperation. The publication was very fast, easy and of high quality. My colleagues and I strongly recommend EPJ Web of Conferences to anyone, who is interested in quick high-quality publication of conference proceedings.

On behalf of the Organizing and Program Committees and Editorial Team of MNPS-2019, Dr. Alexey B. Nadykto, Moscow State Technological University “STANKIN”, Moscow, Russia. EPJ Web of Conferences vol. 224 (2019)

ISSN: 2100-014X (Electronic Edition)

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