Multiscale approach predictions for biological outcomes in ion-beam cancer therapy

10 págs.; 4 figs. 1 tab. ; Open Access funded by Creative Commons Atribution Licence 4.0Ion-beam therapy provides advances in cancer treatment, offering the possibility of excellent dose localization and thus maximising cell-killing within the tumour. The full potential of such therapy can only be realised if the fundamental mechanisms leading to lethal cell damage under ion irradiation are well understood. The key question is whether it is possible to quantitatively predict macroscopic biological effects caused by ion radiation on the basis of physical and chemical effects related to the ion-medium interactions on a nanometre scale. We demonstrate that the phenomenon-based MultiScale Approach to the assessment of radiation damage with ions gives a positive answer to this question. We apply this approach to numerous experiments where survival curves were obtained for different cell lines and conditions. Contrary to other, in essence empirical methods for evaluation of macroscopic effects of ionising radiation, the MultiScale Approach predicts the biodamage based on the physical effects related to ionisation of the medium, transport of secondary particles, chemical interactions, thermo-mechanical pathways of biodamage, and heuristic biological criteria for cell survival. We anticipate this method to give great impetus to the practical improvement of ion-beam cancer therapy and the development of more efficient treatment protocols.We acknowledge the financial support received from the European Union Seventh Framework Programme (PEOPLE2013-ITN-ARGENT project) under grant agreement no. 608163.Peer Reviewe

Create modular hpf boards for educational research with installation NI ELVIS II

Настоящая статья посвящена разработке модульных плат фильтров верхних частот и исследованию их характеристик. Создание модульных плат проводилось в несколько этапов: расчет элементов, моделирование ФВЧ, подбор радиоэлементов в соответствии с расчетами и монтаж фильтров на печатные платы. Для создания модульных плат был выбран ФВЧ Чебышева, поскольку отличительной особенностью этих фильтров является более крутой спад амплитудно-частотной характеристики (АЧХ) и существенные пульсации амплитудно-частотной характеристики на частотах полос пропускания и подавления, чем у фильтров других типов. Создание модульных плат свелось к решению поставленных задач, а именно произвести расчет элементов, смоделировать фильтры в ПО Multisim, подобрать радиоэлементы в соответствии с расчетами и произвести монтаж фильтров на печатные платы. Таким образом было создано восемь модульных плат ФВЧ с разными частотами среза. По итогу работы модульные платы были проверены на учебной установке NI ELVIS II путем снятия АЧХ фильтров. Снятые характеристики соответствовали теоретическим расчетам.This article is devoted to the development of modular circuit boards of high pass filters and study their characteristics. Creating a modular boards conducted in several stages: the calculation of the elements, modeling HPF, selection of radio in accordance with the calculations and installation of filters on printed circuit boards. To create a modular boards Chebyshev HPF has been selected as a distinctive feature of these filters is a steeper decline in the amplitude-frequency characteristic (AFC) and substantial ripple frequency response at the frequencies and bandwidths suppression than the other types of filters. Creating a modular boards reduced to the solution of tasks, namely to calculate the elements, to simulate filters in the software Multisim, pick up the radioactive elements in accordance with the calculations and produce the installation of filters on printed circuit boards. Thus was created the HPF eight modular boards with different cutoff frequencies. The outcome of modular boards was tested for learning installing NI ELVIS II by removing the filter frequency response. Previous theoretical calculations matched characteristics

Irradiation driven molecular dynamics: A review

This paper reviews Irradiation Driven Molecular Dynamics (IDMD) - a novel computational methodology for atomistic simulations of the irradiation driven transformations of complex molecular systems implemented in the MBN Explorer software package. Within the IDMD framework, various quantum processes occurring in irradiated systems are treated as random, fast and local transformations incorporated into the classical MD framework in a stochastic manner with the probabilities elaborated on the basis of quantum mechanics. Major transformations of irradiated molecular systems (such as topological changes, redistribution of atomic partial charges, alteration of interatomic interactions) and possible paths of their further reactive transformations can be simulated by means of MD with reactive force fields, in particular with the reactive CHARMM (rCHARMM) force field implemented in MBN Explorer. This paper reviews the general concept of the IDMD methodology and the rCHARMM force field and provides several exemplary case studies illustrating the utilization of these methods.Comment: 12 pages, 8 figures. Review paper to be published in Eur. Phys. J.

Interplay of the volume and surface plasmons in the electron energy loss spectra of C60_{60}

The results of a joint experimental and theoretical investigation of the C60 collective excitations in the process of inelastic scattering of electrons are presented. The shape of the electron energy loss spectrum is observed to vary when the scattering angle increases. This variation arising due to the electron diffraction of the fullerene shell is described by a new theoretical model which treats the fullerene as a spherical shell of a finite width and accounts for the two modes of the surface plasmon and for the volume plasmon as well. It is shown that at small angles, the inelastic scattering cross section is determined mostly by the symmetric mode of the surface plasmon, while at larger angles, the contributions of the antisymmetric surface plasmon and the volume plasmon become prominent.Comment: 11 pages, 3 figure

New process to describe radiation damage at the molecular level. Application to I-125 seeds in water

ICPEAC 2015, Toledo, Spain on 22 –28 July 2015; http://www.icpeac2015.com/We present the first step of a general study on induced damage by 125I in water at the molecular level. Requirements for such a study are introduced and preliminary results on the emission spectra of 125I seeds are presented.This work was supported by MINECO (FIS2012-31230) and FCT/MEC, RaBBiT, PD-F,PD/00193/2012); UID/Multi/04378/2013 (UCIBIO); UID/FIS/00068/2013 (CEFITEC); and grant number SFRH/BD/52536/2014.Peer Reviewe

Hybridization-related correction to the jellium model for fullerenes

We introduce a new type of correction for a more accurate description of fullerenes within the spherically symmetric jellium model. This correction represents a pseudopotential which originates from the comparison between an accurate ab initio calculation and the jellium model calculation. It is shown that such a correction to the jellium model allows one to account, at least partly, for the sp2-hybridization of carbon atomic orbitals. Therefore, it may be considered as a more physically meaningful correction as compared with a structureless square-well pseudopotential which has been widely used earlier.Comment: 16 pages, 10 figure

Modeling secondary particle tracks generated by high-energy protons in water

ICPEAC 2015, Toledo, Spain on 22 –28 July 2015; http://www.icpeac2015.com/We present interaction probability data of low-energy secondary electrons and positrons produced due to the proton impact. The probability distribution functions serve as input data for the Low Energy Particle Track Simulation (LEPTS) approach which allows one to include the effect of low-energy species in medical applications of radiation and in ion-beam cancer therapy, in particular.his work has been supported by the Spanish Ministry of Economía y Productividad (Project FIS2012-31320). We also acknowledge partial funding from the Portuguese Foundation for Science and Technology (FCT-MCTES), research grant PEstOE/FIS/UI0068/2011,the EU/ESF COST Actions Nano-IBCT - MP1002 and CELINA CM- 1301, and from the FP7 Multi-ITN Project ”Advanced Radiotherapy, Generated by Exploiting Nanoprocesses and Technologies” (ARGENT) (Grant Agreement n◦608163).Peer Reviewe

Formalism of collective electron excitations in fullerenes

We present a detailed formalism for the description of collective electron excitations in fullerenes in the process of the electron inelastic scattering. Considering the system as a spherical shell of a finite width, we show that the differential cross section is defined by three plasmon excitations, namely two coupled modes of the surface plasmon and the volume plasmon. The interplay of the three plasmons appears due to the electron diffraction of the fullerene shell. Plasmon modes of different angular momenta provide dominating contributions to the differential cross section depending on the transferred momentum.Comment: 11 pages, 2 figures; submitted to the special issue "Atomic Cluster Collisions: Structure and Dynamics from the Nuclear to the Biological Scale" of Eur. Phys. J.

Surface softening in metal-ceramic sliding contacts: An experimental and numerical investigation

This study investigates the tribolayer properties at the interface of ceramic/metal (i.e., WC/W) sliding contacts using various experimental approaches and classical atomistic simulations. Experimentally, nanoindentation and micropillar compression tests, as well as adhesion mapping by means of atomic force microscopy, are used to evaluate the strength of tungsten?carbon tribolayers. To capture the influence of environmental conditions, a detailed chemical and structural analysis is performed on the worn surfaces by means of XPS mapping and depth profiling along with transmission electron microscopy of the debris particles. Experimentally, the results indicate a decrease in hardness and modulus of the worn surface compared to the unworn one. Atomistic simulations of nanoindentation on deformed and undeformed specimens are used to probe the strength of the WC tribolayer and despite the fact that the simulations do not include oxygen, the simulations correlate well with the experiments on deformed and undeformed surfaces, where the difference in behavior is attributed to the bonding and structural differences of amorphous and crystalline W-C. Adhesion mapping indicates a decrease in surface adhesion, which based on chemical analysis is attributed to surface passivation