- Published on 21 July 2014
The seminal 1914 experiment of James Franck and Gustav Hertz provided a graphic demonstration of the quantisation properties of atoms, and thereby laid the foundations of modern atomic physics. This EPJ D colloquium revisits the experiment on the occasion of its Centenary and compares the traditional and modern interpretations, as well as highlighting the link between microscopic processes, which are governed by the laws of quantum mechanics, and macroscopic phenomena, as observed in the laboratory.
- Published on 17 July 2014
In this EPJ D topical review, the authors present a systematic study of gas breakdown potentials. An analysis of the key elementary processes involved in low-current low-pressure discharges is given, with the aim of illustrating how such discharges are used to determine swarm parameters and how such data may be applied to the modeling of discharges.
- Published on 30 June 2014
New study provides proof of the validity of a filtering device for ultra-cold neutral atoms based on tunnelling
Techniques for controlling ultra-cold atoms travelling in ring traps currently represent an important research area in physics. A new study published in EPJ D gives a proof of principle, confirmed by numerical simulations, of the applicability to ultra-cold atoms of a very efficient and robust transport technique called spatial adiabatic passage (SAP). Yu Loiko from the University of Barcelona, Spain, and colleagues have, for the first time, applied SAP to inject, extract, and filter the velocity of neutral atoms from and into a ring trap. Such traps are key to improving our understanding of phenomena involving ultra-cold atoms, which are relevant to high-precision applications such as atom optics, quantum metrology, quantum computation, and quantum simulation.
- Published on 30 June 2014
A new study relevant for cancer radiation therapy shows that DNA building blocks are susceptible to fragmentation on contact with the full range of ions from alkaline element species
Scientists now have a better understanding of how short DNA strands decompose in microseconds. A European team found new fragmentation pathways that occur universally when DNA strands are exposed to metal ions from a family of alkaline and alkaline earth elements. These ions tend to replace protons in the DNA backbone and at the same time induce a reactive conformation leading more readily to fragmentation. These finding have been published by Andreas Piekarczyk, from the University of Iceland, and colleagues in a study in EPJ D. They could contribute to optimising cancerous tumour therapy through a greater understanding of how radiation and its by-products, reactive intermediate particles, interact with complex DNA structures.
- Published on 19 June 2014
Physicists have published a new theoretical foundation explaining the mechanism of protein folding and unfolding in water
Investigating the structure and dynamics of so-called Meso-Bio-Nano (MBN) systems—micron-sized biological or nanotechnology entities—is a rapidly expanding field of science. Now, scientists Alexander Yakubovich and Andrey Solov'yov from MBN Research Centre in Frankfurt, Germany, have produced a new theoretical study of a protein macromolecules changing from a coil structural conformation to a globular one. Their statistic mechanics model, just published in EPJ D, describes the thermodynamic properties of real proteins in an aqueous environment, using a minimal number of free physical parameters.
- Published on 11 March 2014
Inducing biological tissue damage with an atmospheric pressure plasma source could open the door to many applications in medicine
Plasma medicine is a new and rapidly developing area of medical technology. Specifically, understanding the interaction of so-called atmospheric pressure plasma jets with biological tissues could help use them in medical practice. Under the supervision of Sylwia Ptasinska from the University of Notre Dame, in Indiana, USA, Xu Han and colleagues conducted a quantitative and qualitative study of the different types of DNA damage induced by atmospheric pressure plasma exposure, in a paper published in EPJ D as part of a special issue on nanoscale insights into Ion Beam Cancer Therapy. This approach, they hope, could ultimately lead to devising alternative tools for cancer therapy as well as applications in hospital hygiene, dental care, skin diseases, antifungal care, chronic wounds and cosmetics treatments.
- Published on 26 February 2014
The effect of spatial ordering of molecules on surfaces is commonly utilised to deposit ultra-thin films, where the film thickness is only a few nanometres. In this EPJ D review paper, several methods are discussed that are distinguished from other thin film deposition processes by exactly these effects, leading to self-assembling and self-limiting layer growth and, eventually, to coatings with unique and fascinating properties, and applications in micro-electronics, optics, chemistry, and biology.
- Published on 26 February 2014
A new study represents a step forward in our understanding of the nature of exchange interactions between identical particles, which only occur at the quantum level
Two-particle interference has been the focus of many studies, specifically in quantum optics with photons. However, interference between two massive, identical particles is not so well understood. In a study published in EPJ D, Pedro Sancho from the CLPU—Centre for Pulsed Lasers—in Salamanca, Spain, uncovers a counterintuitive result whereby particles called bosons do not behave as expected—they are overlapping, and not interfering—due to the combination of interference and so-called exchange interaction. The latter is a quantum mechanical effect that alters their symmetry when identical particles are exchanged.
- Published on 16 December 2013
A new study focused on electric discharge behaviour under intense gravitational forces shows that its dynamic changes as gravity increases
Arc discharges are common in everyday conditions like welding or in lightning storms. But in altered gravity, not as much is known about the behaviour of electric discharges. For the first time, Jiří Šperka from Masaryk University, Czech Republic, and his Dutch colleagues studied the behaviour of a special type of arc discharge, so-called glide arc, in varying hypergravity conditions, up to 18 G. In a paper just published in EPJ D, they demonstrate how the plasma channel of this glide arc discharge moves due to external forces of buoyancy in varying gravity conditions. These results could have implications for improved safety precautions in manned space flights, and in the design of ion thrusters used for spacecraft propulsion.
- Published on 11 December 2013
A new protocol, exploiting the quantum properties of materials, makes it possible to improve the accuracy of photolithography by addressing its physical limitations due to diffraction
Photolithography uses light beams to design thin geometric patterns on the substrates of semiconductors used in microelectronic devices. This is achieved using a chemical reaction on a light-sensitive chemical, called photoresist. The trouble is that the phenomenon of light diffraction does not permit highly accurate patterns. Often, the edges of stripes have low contrast, the distances between the stripes and the stripes’ width are limited by what is referred to as Rayleigh’s diffraction limit. Now, a scientist from Russia has developed a quantum lithography protocol designed to improve the resolution of this technology. The findings of George Miroshnichenko, a physicist at Saint-Petersburg National Research University of Information Technologies, Mechanics and Optics, in Russia, have just been published in EPJ D.