- Published on 25 March 2015
Applying the hydrodynamics approach to granular matter helps explain its wide range of behaviour, regardless of whether the material is solid- or fluid-like
Sand, rocks, grains, salt or sugar are what physicists call granular media. A better understanding of granular media is important - particularly when mixed with water and air, as it forms the foundations of houses and off-shore windmills. Until recently, there was no single theory that could account for granular media’s flows at different speeds. Now, a new theory dubbed GSH, which stands for granular solid hydrodynamics, is supplementing previous models of granular material that work only for narrow speed ranges. And Yimin Jiang from Central South University, Changsha, China and Mario Liu from the University of Tübingen, Germany have now applied GSH to different experimental circumstances, for a wide range of flow speeds, in a study published in EPJ E.
- Published on 13 March 2015
EPJE Associate Editors Kari Dalnoki-Veress and James A. Forrest open the journal for submissions of a new type of paper: Tips and Tricks.
Underpinning the scientific enterprise there is often some crucial numerical recipe, a sample cell configuration, a sample preparation method, or experimental design. In some cases more emails were shared describing a trick than citations gathered by the paper where a brief description was provided. Typically such details are only briefly described in the journal literature, passed only from student to student, or simply shared as a ‘personal communication’. Sometimes such enabling techniques are not passed on at all. In all such cases, the scientific community as a whole is missing out, lacking a way to document this knowledge and to build on it. Moreover, while the specific research of some team may not be directly relevant to another, a transformative computational or experimental methodology can form the commonality between researchers working in different fields.
2015 will see the launch of a new section of EPJ E: Tips and Tricks.
- Published on 16 February 2015
A simple physical mechanism that can be assimilated to folding, or buckling, means that an unformed mass of cells can change in a single step into an embryo organized as a typical vertebrate. This is the main conclusion of work by a team involving physicists from the Laboratoire Matière et Systèmes Complexes (CNRS/Université Paris Diderot) and a biologist from the Laboratoire de Biologie du Développement (CNRS/UPMC).
Thanks to microscopic observations and micromechanical experiments, the scientists have discovered that the pattern that guides this folding is present from the early stages of development. The folds that will give a final shape to the animal form along the boundaries between cell territories with different properties. This work has shed light on the mechanism for the formation of vertebrates and thus how they appeared during evolution. These findings have just been published in EPJ E.
- Published on 12 January 2015
A new study of how particles may respond to the mechanical effects of light helps improve optical manipulation and remote sensing of non-spherical particles.
Manipulation of small objects by light has gained in popularity in the past few years. Now, scientists have performed the first systematic analysis of the behaviour of ellipsoidal particles manipulated by laser beams. The work shows that such particles are constantly moving in and out of the reach of an optical beam, creating oscillations. These findings by a team of researchers from the University of Bordeaux, France, have just been published in EPJ E. This work could help understand the unusual behaviour of rod-like particles manipulated by optical tweezers. Ultimately, the theoretical part of this work could contribute numerical models of how complicated shapes and large sizes scatter laser light. Numerous applications exist in fluid engineering and remote sensing methods.
- Published on 19 December 2014
- Published on 02 December 2014
Understanding how a desert beetle harvests water from dew could help to improve drinking water collection in dew condensers mimicking the nanostructure of the beetle’s back
Insects are full of marvels—and this is certainly the case with a beetle from the Tenebrionind family, found in the extreme conditions of the Namib desert. Now, a team of scientists has demonstrated that such insects can collect dew on their backs—and not just fog as previously thought. This is made possible by the wax nanostructure on the surface of the beetle’s elytra. These findings by José Guadarrama-Cetina, then working at ESPCI ParisTech, France—on leave from the University of Navarra, in Spain—and colleagues were recently published in EPJ E. They bring us a step closer to harvesting dew to make drinking water from the humidity in the air. This, the team hopes, can be done by improving the water yield of man-made dew condensers that mimick the nanostructure on the beetle’s back.
- Published on 28 October 2014
New systematic study of the electrical properties of model lipid membranes could improve our understanding of biological cells and opens new possibilities for medical diagnostics
Biological membranes are mainly composed of lipid bilayers. Gaining a better understanding of adsorption of solution ions onto lipid membranes helps clarify functional processes in biological cells. Now, a new study provides a quantitative description of the equilibria between lipid membranes and surrounding solution ions. Joanna Kotyńska and Zbigniew Figaszewski from the University of Bialystok, Poland, are the authors of a study describing these findings, just published in EPJ E. In addition to shedding some light on biological processes, these results could also have implications for, among other things, the future development of medical diagnostics.
- Published on 20 October 2014
Zero gravity experiments on the International Space Station shed some light on thermodiffusion effects, relevant to the oil and gas industry and global warming prevention processes
Thermodiffusion, also called the Soret effect, is a mechanism by which an imposed temperature difference establishes a concentration difference within a mixture. Two studies by Belgian scientists from the Free University of Brussels, recently published in EPJ E, provide a better understanding of such effects. They build on recent experimental results from the IVIDIL—Influence Vibration on Diffusion in Liquids—research project performed on the International Space Station under microgravity to avoid motion in the liquids.
- Published on 22 July 2014
A new study investigates the effects of small but finite inertia on the propulsion of micro and nano-scale swimming machines that could have implications for biomedical applications
Scale plays a major role in locomotion. Swimming microorganisms, such as bacteria and spermatozoa, are subjected to relatively small inertial forces compared to the viscous forces exerted by the surrounding fluid. Such low-level inertia makes self-propulsion a major challenge. Now, scientists have found that the direction of propulsion made possible by such inertia is opposite to that induced by a viscoelastic fluid. These findings have been published in EPJ E by François Nadal from the Alternative Energies and Atomic Energy Commission (CEA), in Le Barp, France, and colleagues. This study could help optimise the design of self-propelled micro- and nanoscale artificial swimming machines to improve their mobility in medical applications.
- Published on 07 July 2014
A new study accounts for species interactions, and adds a layer of complexity to previous minimalists models
Models for the evolution of life are now being developed to try and clarify the long-term dynamics of an evolving system of species. Specifically, a recent model proposed by Petri Kärenlampi from the University of Eastern Finland in Joensuu accounts for species interactions with various degrees of symmetry, connectivity, and species abundance. This is an improvement on previous, simpler models, which apply random fitness levels to species. The findings published in EPJ E demonstrate that the resulting replicator ecosystems do not appear to be a self-organised critical model, unlike the so-called Bak-Sneppen model; a reference in the field. The reasons for this discrepancy are not yet known.