Abstract: We study the confinement of a C-60 molecule encapsulated in a cylindrical nanotube as a function of the tube radius. Drawing the Mercator maps of the potential, we find two distinct molecular orientations; for tubes with small radii, R-T less than or similar to 7 angstrom, a fivefold axis of the molecule coincides with the tube long axis, for larger radii, R-T less than or similar to 8 angstrom, a threefold axis of the molecule coincides with the tube long axis. These different orientations are caused by the relative importance of the repulsive and the attractive parts of the van der Waals potentials of the molecule with the tube wall for small and large tubes respectively. Experimental evidence is provided by the apparent splitting of A(g) modes of the C-60 molecule in resonant Raman scattering.

Abstract: We present full ab initio calculations of the phonon band structure of thin Si nanowires oriented along the [110] direction. Using these phonon dispersion relations we investigate the structural stability of these wires. We found that all studied wires were stable also when doped with either B or P, if the unit cell was taken sufficiently large along the wire axis. The evolution of the phonon dispersion relations and of the sound velocities with respect to the wire diameters is discussed. Softening is observed for acoustic modes and hardening for optical phonon modes with increasing wire diameters.

Abstract: In this theoretical study, the electron emission from a copper surface under ultrashort pulsed laser irradiation is investigated using a one dimensional particle in cell model. Thermionic emission as well as multi-photon photoelectron emission were taken into account. The emitted electrons create a negative space charge above the target, consequently the generated electric field reduces the electron emission by several orders of magnitude. The simulations indicate that the space charge effect should be considered when investigating electron emission related phenomena in materials under ultrashort pulsed laser irradiation of metals.the word abstract, but do replace the rest of this text. ©2010 American Institute of Physics

Abstract: In this work, electronic properties of individual TiOx-pristine nanoribbons (NR) prepared by hydrothermal treatment of anatase TiO(2) micro-particles were studied using the HZB transmission x-ray microscope (TXM) at the BESSY II undulator beamline U41-FSGM. NEXAFS is ideally suited to study TiO(2)-based materials because both the O K-edge and Ti L-edge features are very sensitive to the local bonding environment, providing diagnostic information about the crystal structures and oxidation states of various forms of titanium oxides and sub-oxides. TXM-NEXAFS combines full-field x-ray microscopy with spectroscopy, allowing the study of the electronic structure of individual nanostructures with spatial resolution better than 25 nm and a spectral resolution of up to E/Delta E = 10000. The typical image field in TXM-NEXAFS measurements is about 10 mu m. 10 mu m, which is large compared to the individual nanoparticle. Therefore, one image stack already contains statistically significant data. In addition, the directional electric field vector ((E) over bar) of the x-rays can be used as a “search tool” for the direction of chemical bonds of the atom selected by its absorption edge.

Abstract: Hydrogen-bonded ferroelectrics are modelled by a coupled spin/nonlinear lattice (polarizability) interaction Hamiltonian, where specifically the geometry of the hydrogen bond is included. The model leads to a structural phase transition and describes correctly the isotope effect due to the substitution H/D in hydrogen-bonded systems in terms of bond length changes.

Abstract: We investigate the properties of carriers in graphene-based quantum wires created by potential barriers, by means of analytical and numerical calculations. We obtain expressions for the energy spectrum as a function of barrier height, well width and linear momentum along the wire. The results demonstrate a direction-dependent resonant transmission across the potential well.

Abstract: We describe an experimental distinction between giant vortex and multivortex states in mesoscopic superconducting disks by using two methods: the multiple-small-tunnel-junction method and the temperature dependence of vortex expulsion fields. The experimental results are in good agreement with the theoretical simulations based on the non-linear Ginzburg-Landau theory.

Abstract: The atomic structure of single-wall carbon nanotube bundles produced by three different techniques has been characterized by electron diffraction and microscopy. Small bundles produced by Catalytical Chemical Vapor Deposition (CCVD) exhibit only one or two tube chiralities within a single bundle while bundles produced by arc-discharge or laser-ablation exhibit more chiralities. A detailed analysis of the central line of diffraction is also presented. The CCVD nanotubes present more intense spots around 1.7 Angstrom(-1) < k < 2Angstrom(-1) (k is the momentum transfer) compared to what is observed for nanotubes produced by other methods. Amongst the possible explanation for such an anomaly, we put forward that in this range of momentum transfer, the relative tube orientations and translations are important for what concerns the interpretation of the diffraction peaks intensities.

Abstract: The paper presents the results of the study of atmospheric aerosols in the Siberian region. This research was focused on studying the chemical and biological characteristics of both natural and pollution aerosols in this vast territory of the Asian part of the former Soviet Union (FSU). The data received within the frame of this project formed the basis for the evaluation of the impact of these aerosols on the Arctic region and the global climate. The Asian part of FSU is of scientific interest in the context of environmental chemistry, air pollution and study of atmospheric aerosols, The specific relevance of aerosol research in Siberia is as follows. There are areas that are very remote from industrial or densely populated centres, In these circumstances, aerosol characterization contributes to the definition of global continental “background”) or “baseline” aerosol, i.e, the aerosol which should occur in natural circumstances and on which all pollution is superimposed. Recently, in the context of global and long-term climatic changes, baseline aerosols and long-range transport of particulate air pollutants have become a topic of much debate, This is because it has been thought that aerosols might compensate for the well-known greenhouse effect to a significant. In this context, more and more attention is being paid to long-range effects of continental aerosols on the polar regions. Research in Norway and Alaska showed that Western or Central Siberia may be a very important source of pollutants affecting the air composition in the Arctic region. Cities and regions in south Siberia are enormously polluted by heavy metals, the level of pollution being many times higher than in the Western world, thus the health of local population is seriously affected. In most cases, gigantic point sources are in the area, which is simple from the viewpoint of environmental chemistry and unambiguous results should be obtained easily. Atmospheric deposition is a possible cause of the existence of heavy metals in the southern part of Lake Baikal. in the northern part of the lake, the environment is unpolluted. However in the southern part of the lake is considerably threatened by pollution from Baikalsk wood-pulp mill and industrial enterprises of Irkutsk, Angarsk,

Abstract: Thermal fluctuations play an increasingly important role in micromagnetic research relevant for various biomedical and other technological applications. Until now, it was deemed necessary to use a time stepping algorithm with a fixed time step in order to perform micromagnetic simulations at nonzero temperatures. However, Berkov and Gorn have shown in [D. Berkov and N. Gorn, J. Phys.: Condens. Matter,14, L281, 2002] that the drift term which generally appears when solving stochastic differential equations can only influence the length of the magnetization. This quantity is however fixed in the case of the stochastic Landau-Lifshitz-Gilbert equation. In this paper, we exploit this fact to straightforwardly extend existing high order solvers with an adaptive time stepping algorithm. We implemented the presented methods in the freely available GPU-accelerated micromagnetic software package MuMax3 and used it to extensively validate the presented methods. Next to the advantage of having control over the error tolerance, we report a twenty fold speedup without a loss of accuracy, when using the presented methods as compared to the hereto best practice of using Heun’s solver with a small fixed time step.

Abstract: Major obstacles in current CMOS technology, such as the interconnect bottleneck and thermal heat management, can be overcome by employing subwavelength-scaled light in plasmonic waveguides and devices. In this work, a plasmonic structure that implements the majority (MAJ) gate function is designed and thoroughly studied through simulations. The structure consists of three merging waveguides, serving as the MAJ gate inputs. The information of the logic signals is encoded in the phase of transmitted surface plasmon polaritons (SPP). SPPs are excited at all three inputs and the phase of the output SPP is determined by theMAJof the input phases. The operating dimensions are identified and the functionality is verified for all input combinations. This is the first reported simulation of a plasmonic MAJ gate and thus contributes to the field of optical computing at the nanoscale. (C) 2017 Author(s).

Abstract: Utilizing magnetic tunnel junctions (MTJs) for write/read and fast spin-orbit-torque (SOT)-driven domain-wall (DW) motion for propagation, enables non-volatile logic and majority operations, representing a breakthrough in the implementation of nanoscale DW logic devices. Recently, current-driven DW logic gates have been demonstrated via magnetic imaging, where the Dzyaloshinskii-Moriya interaction (DMI) induces chiral coupling between perpendicular magnetic anisotropy (PMA) regions via an in-plane (IP) oriented region. However, full electrical operation of nanoscale DW logic requires electrical write/read operations and a method to pattern PMA and IP regions compatible with the fabrication of PMA MTJs. Here, we study the use of a Hybrid Free Layer (HFL) concept to combine an MTJ stack with DW motion materials, and He+ ion irradiation to convert the stack from PMA to IP. First, we investigate the free layer thickness dependence of 100-nm diameter HFL-MTJ devices and find an optimal CoFeB thickness, from 7 to 10 angstrom, providing high tunneling magnetoresistance (TMR) readout and efficient spin-transfer torque (STT) writing. We then show that high DMI materials, like Pt/Co, can be integrated into an MTJ stack via interlayer exchange coupling with the CoFeB free layer. In this design, DMI values suitable for SOT-driven DW motion are measured by asymmetric bubble expansion. Finally, we demonstrate that He+ irradiation reliably converts the coupled free layers from PMA to IP. These findings offer a path toward the integration of fully electrically controlled DW logic circuits.

Abstract: A spin wave majority fork-like structure with feature size of 40 nm, is presented and investigated, through micromagnetic simulations. The structure consists of three merging out-of-plane magnetization spin wave buses and four magneto-electric cells serving as three inputs and an output. The information of the logic signals is encoded in the phase of the transmitted spin waves and subsequently stored as direction of magnetization of the magneto-electric cells upon detection. The minimum dimensions of the structure that produce an operational majority gate are identified. For all input combinations, the detection scheme employed manages to capture the majority phase result of the spin wave interference and ignore all reflection effects induced by the geometry of the structure. (C) 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Abstract: It has been acknowledged that power is a fundamental aspect that needs to be considered when performing a value chain analysis. The structure of the value chain is indicative of the power distribution along the chain. By employing systems thinking the structure of the value chain can be further investigated and inferences on market power issues can be made. This novel approach connects value chain research with insights from Industrial Organization (IO) literature. Depending on the case, market power may not be measurable by traditional economic tools. Systems thinking offers an alternative tool, allowing the employment of qualitative and quantitative data, overcoming drawbacks of IO methods and providing more depth to value chain analysis. In this paper the valuable contribution of systems thinking to market power analysis is exemplified by the Belgian sugar beet case. The analysis showed that transportability and perishability of sugar beet are key causes of market failure in the Belgian sugar value chain. Systems thinking can support understanding potential future behavior of the market based on the thorough understanding of the current market structure. We illustrate how to integrate factors determining the market structure into causal loop diagrams. This novel approach allows a comprehensive evaluation and thus opens up market power analysis to interdisciplinary research.