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EPJ ST Highlight - Elastic nozzles could create more stable liquid jets
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- Published on 27 September 2022
New experiments show that nozzles which deform as liquid flows through them could help to improve the stability of liquid jets in many different scenarios
When a liquid jet is squirted through a nozzle, it will eventually break up into a string of droplets. Through previous studies, researchers determined that the distance from the nozzle where this breakup occurs depends on a wide range of factors: including the nozzle’s shape, and the movement of air surrounding the jet. So far, however, little attention has been paid to elastic nozzles, which can deform as liquids pass through them. Through new research published in EPJ ST, a team led by Andrew Dickerson at the University of Tennessee, USA, introduces the concept of passively-deforming nozzles, and shows that softer nozzle materials can produce more stable jets across a wide range of flow rates.
Johan Åkerman joins the EPJ Scientific Advisory Committee (SAC)
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- Published on 22 September 2022
The Scientific Advisory Committee of EPJ is delighted to welcome Dr. Johan Åkerman as the new representative for the Swedish Physical Society.
Johan Åkerman is the head of the Applied Spintronics Group at the Physics Department of University of Gothenburg. His expertise is in spintronic devices, such as magnetic tunnel junctions and MRAM, and more recently with spin torque and spin Hall nano-oscillators for microwave and spin wave signal generation, neuromorphic computing, and Ising Machines. He is one of the founding members of the Global Young Academy and the Swedish Young Academy, a fellow of the American Physical Society, and a member of the Royal Swedish Academy of Engineering Sciences.
EPJ H Highlight - Fermi’s ground-breaking figure
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- Published on 22 September 2022
How the radial wave function transformed physics
One way to better understand an atom is to shoot a particle at it and infer the atom’s properties based on how the particle bounces off it. In the mid-1930s, the physicist Enrico Fermi showed that one measurable number – the scattering length – illuminated everything that could be known about an electron scattering off an atom, or a neutron scattering off a nucleus. In a new paper in EPJ H: Historical Perspectives on Contemporary Physics, Chris Gould from North Carolina State University in Raleigh, USA, explains how Fermi’s simple sketch of a radial wave function laid the groundwork for a better understanding of low energy scattering phenomena, and led in turn to the concept of the pseudopotential, widely used in many areas of physics, including ultracold atom research and studies of qubits in realisations of quantum computers.
EPJ ST Highlight - Tiny animal hairs could act as sensitive compass needles
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- Published on 20 September 2022
Statistical mechanics shows that some animals may be able to perceive Earth’s magnetic field with bundles of microscopic hairs in their inner ears.
The exact mechanisms animals use to sense the direction of Earth’s magnetic field have long remained a mystery. One leading theory suggests that this ability is tied to bundles of microscopic hair cells in the inner ears. Through new research published in EPJ ST, Kirill Kavokin at St Petersburg State University, Russia, uses statistical analysis to show that just around 100 of these hair cells could act as effective biological compass needles, allowing animals to accurately sense the magnetic field surrounding them.
EPJ Plus Highlight - Modelling the use of Beta Radiation in cancer treatment
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- Published on 20 September 2022
New research pits the simulation of beta radiation doses in tumour treatment against an analytical method.
Treating superficial skin tumours especially when they are located above cartilage or bone with beta radiation can help protect sensitive structures during the delivery of treatment.
The use of short-range beta radiation in cancer treatment is not without its disadvantages, however, especially when it comes to the measurement of radiation exposure — dosimetry. When experimental dosimetry is not feasible, researchers use simulations and calculations to study the interaction of the ionizing radiation with matter and estimate the radiation dose delivered to a target organ.
A new paper published in EPJ Plus and authored by Eduardo De Paiva, from the Division of Medical Physics at the Institute of Radiation Protection and Dosimetry, Rio de Janeiro, Brazil, and his colleagues, pits the gold standard of simulation techniques — Monte Carlo (MC) simulation — against an alternative analytic method, the Loevinger formula.
EPJ E Colloquium - Thermophoresis and thermal orientation of Janus nanoparticles in thermal fields
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- Published on 02 September 2022
Thermal gradients induce thermodiffusion in aqueous solutions and liquid mixtures and thermophoretic forces that drive the motion of colloids towards hot or cold regions. The Soret coefficient quantifies the strength of the thermophoretic force and varies with temperature, colloid mass and diameter, and colloid-solvent interactions. Janus colloids (JCs ) are nanoparticles with heterogeneous compositions and two contrasting properties, or "two faces" like the Roman god Janus. For example, in spherical JCs, one hemisphere might be hydrophilic and the other hydrophobic. The interest in JCs has grown steadily given their applicability in materials science. While the behaviour of JCs under equilibrium conditions has been explored, their response to thermal gradients is still not fully understood. Explaining the behaviour of JCs in a thermal field might expand their use in materials science and biomedical applications.
EPJ D Colloquium - Overview of photo-neutralization techniques for negative ion-based neutral beam injectors in future fusion reactors
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- Published on 16 August 2022
The need for safe, carbon-free and abundant sources of energy is becoming more and more pressing. While still under development, nuclear fusion can play a key role in a medium term, decarbonized energy scenario. However, in order for fusion to be commercially competitive, many sub-systems constituting the current experimental reactors need to be optimized in terms of their efficiency: in particular, DEMO and future fusion energy plants will require a substantial increase in the energy performances of the plasma heating systems.
EPJ E Highlight - Considering how friction is maximised when liquids flow on nanoscales
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- Published on 15 August 2022
By simulating a liquid confined by a nanoscale structure, researchers discovered the role molecular clogging plays in friction.
The dynamics of how liquids behave when confined in a nanoscale-sized space such as nanochannels, nanotubes or nanopores, is key to understanding a wealth of processes including lubrication, filtration and even energy storage.
The dynamics of liquids at nanoscales are different to behaviour in confinement at macroscales, however. One of the key differences that a reduction in scale creates is friction and shear between the liquid and its solid container. And further complications arise in systems with solid-to-solid contact with features like wear, micro-pitting and scuffing created.
A new paper published in EPJ E and authored by Shan Chen, from the State Key Laboratory of Organic-Inorganic Composites at Beijing University of Chemical Technology, China, uses simulations of molecular dynamics to look at the friction-induced nano-confined liquids.
EPJ B Highlight - Assessing the effect of hydraulic fracturing on microearthquakes
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- Published on 15 August 2022
New research examines mining sites with hydraulic fracturing comparing it to those without to determine the practice’s effect on seismic hazards.
The analysis of low-intensity human-caused microearthquakes, including their magnitude and frequency, has become an important factor in mining. This is a consideration not only for the safety of mining staff, but also for extraction rates and mine stability that can have major impacts on business performance. Increasingly, the practice of hydraulic fracturing is used to precondition mines and diminish the magnitude of induced tremors as well as reduce the number of rock fragments extracted.
A new paper published in EPJ B assesses the impact of hydraulic fracturing on seismic hazards like microearthquakes, an important issue for the safety of workers and the continuation of mining operations. The paper is authored by Erick de la Barra, Pedro Vega-Jorquera and Héctor Torres from the University of La Serena, Chile, alongside Sérgio Luiz E. F. da Silva from Politecnico di Torino, Department of Applied Science and Technology, Turin, Italy.
EPJ H Highlight - A step towards quantum gravity
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- Published on 11 August 2022
Resolving the problem of time
In Einstein’s theory of general relativity, gravity arises when a massive object distorts the fabric of spacetime the way a ball sinks into a piece of stretched cloth. Solving Einstein’s equations by using quantities that apply across all space and time coordinates could enable physicists to eventually find their ‘white whale’: a quantum theory of gravity. In a new article in EPJ H: Historical Perspectives on Contemporary Physics, Donald Salisbury from Austin College in Sherman, USA, explains how Peter Bergmann and Arthur Komar first proposed a way to get one step closer to this goal by using Hamilton-Jacobi techniques. These arose in the study of particle motion in order to obtain the complete set of solutions from a single function of particle position and constants of the motion.
