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Accessing radiation damage to biomolecules on the nanoscale by particle-scattering simulations
(2023)
Radiation damage to DNA plays a central role in radiation therapy to cure cancer. The physico-chemical and biological processes involved encompass huge time and spatial scales. To obtain a comprehensive understanding on the nano and the macro scale is a very challenging tasks for experimental techniques alone. Therefore particle-scattering simulations are often applied to complement measurements and aide their interpretation, to help in the planning of experiments, to predict their outcome and to test damage models. In the last years, powerful multipurpose particle-scattering framework based on the Monte-Carlo simulation (MCS) method, such as Geant4 and Geant4-DNA, were extended by user friendly interfaces such as TOPAS and TOPAS-nBio. This shifts their applicability from the realm of dedicated specialists to a broader range of scientists. In the present review we aim to give an overview over MCS based approaches to understand radiation interaction on a broad scale, ranging from cancerous tissue, cells and their organelles including the nucleus, mitochondria and membranes, over radiosensitizer such as metallic nanoparticles, and water with additional radical scavenger, down to isolated biomolecules in the form of DNA, RNA, proteins and DNA-protein complexes. Hereby the degradation of biomolecules by direct damage from inelastic scattering processes during the physical stage, and the indirect damage caused by radicals during the chemical stage as well as some parts of the early biological response is covered. Due to their high abundance the action of hydroxyl radicals (•OH) and secondary low energy electrons (LEE) as well as prehydrated electrons are covered in additional detail. Applications in the prediction of DNA damage, DNA repair processes, cell survival and apoptosis, influence of radiosensitizer on the dose distribution within cells and their organelles, the study of linear energy transfer (LET), the relative biological effectiveness (RBE), ion beam cancer therapy, microbeam radiation therapy (MRT), the FLASH effect, and the radiation induced bystander effect are reviewed.
Heute verfügbare Technik ermöglicht es, die Wärmetransportmechanismen im Brand, an der Bauteiloberfläche und im Bauteil mittels CFD zu koppeln. Die Kopplung von Fluid und Struktur wurde am Beispiel eines 100-MW-Tunnelbrands mit CFD (Computational Fluid Dynamics) untersucht. Die instationären Berechnungen wurden mit dem CFD-Programm ANSYS Fluent durchgeführt. Der infolge eines Lkw-Unfalls verursachte n-Heptan-(C7H16)-Brand wurde mit dem Eddy-Dissipation-Verbrennungsmodell modelliert.
Das Fluid- und Solid-Gebiet wurden durch ein ‚Interface‘ gekoppelt. Die instationäre Wärmeleitung des Bauteils mit einer Höhe von 0,4 m wurde mit der dreidimensionalen Fourier´schen Wärmeleitungsgleichung modelliert und das instationäre thermische Verhalten des quarzhaltigen Betonbauteils analysiert. Temperaturabhängige Stoffkennwerte wurden berücksichtigt.
Amuay refinery disaster (2012) is another recent example of Vapor Cloud Explosion (VCE) and fire accidents preceded by Buncefield (2005), Puerto-Rico (2009) and Jaipur (2009), respectively [9]. The incident has left many safety issues behind which must be repeatedly addressed. Unfortunately, the lessons taught by previous similar events are just not understood carefully. It reveals that the proper safety measures for such facilities were either underestimated or were not accounted seriously. Consequently, the resulting overpressures from explosion and the subsequent thermal radiation from tank fires have once again proved to be disastrous to both mankind and infrastructure. This article highlights the aftermaths of Amuay incident and addresses the challenges put forward by it. Furthermore, a comparative study is performed between such incidents to analyze the similarities and how they could have been avoided.