TY - GEN A1 - Bressel, Lena A1 - Herzog, Bernd A1 - Reich, Oliver T1 - Monte-Carlo simulations of light transport in dense materials BT - dependent scattering and influence on sunscreen formulations T2 - Diffuse Optical Spectroscopy and Imaging N2 - Monte-Carlo calculations are carried out to simulate the light transport in dense materials. Focus lies on the calculation of diffuse light transmission through films of scattering and absorbing media considering additionally the effect of dependent scattering. Different influences like interaction type between particles, particle size, composition etc. can be studied by this program. Simulations in this study show major influences on the diffuse transmission. Further simulations are carried out to model a sunscreen film and study best compositions of this film and will be presented. KW - Monte-Carlo simulations KW - dependent scattering KW - sunscreen KW - light scattering KW - high concentrations Y1 - 2019 SN - 978-1-5106-2841-0 SN - 978-1-5106-2842-7 U6 - https://doi.org/10.1117/12.2527076 SN - 0277-786X SN - 1996-756X VL - 11074 PB - SPIE CY - Bellingham ER - TY - JOUR A1 - Röthlein, Christoph A1 - Miettinen, Markus S. A1 - Ignatova, Zoya T1 - A flexible approach to assess fluorescence decay functions in complex energy transfer systems JF - BMC biophysics N2 - Background: Time-correlated Forster resonance energy transfer (FRET) probes molecular distances with greater accuracy than intensity-based calculation of FRET efficiency and provides a powerful tool to study biomolecular structure and dynamics. Moreover, time-correlated photon count measurements bear additional information on the variety of donor surroundings allowing more detailed differentiation between distinct structural geometries which are typically inaccessible to general fitting solutions. Results: Here we develop a new approach based on Monte Carlo simulations of time-correlated FRET events to estimate the time-correlated single photon counts (TCSPC) histograms in complex systems. This simulation solution assesses the full statistics of time-correlated photon counts and distance distributions of fluorescently labeled biomolecules. The simulations are consistent with the theoretical predictions of the dye behavior in FRET systems with defined dye distances and measurements of randomly distributed dye solutions. We validate the simulation results using a highly heterogeneous aggregation system and explore the conditions to use this tool in complex systems. Conclusion: This approach is powerful in distinguishing distance distributions in a wide variety of experimental setups, thus providing a versatile tool to accurately distinguish between different structural assemblies in highly complex systems. KW - Time resolved FRET KW - Monte-Carlo simulations KW - Complex heterogeneous systems KW - Protein aggregation Y1 - 2015 U6 - https://doi.org/10.1186/s13628-015-0020-z SN - 2046-1682 VL - 8 PB - BioMed Central CY - London ER - TY - JOUR A1 - Bressel, Lena A1 - Reich, Oliver T1 - Theoretical and experimental study of the diffuse transmission of light through highly concentrated absorbing and scattering materials Part I: Monte-Carlo simulations JF - Journal of quantitative spectroscopy & radiative transfer N2 - In many technical materials and commercial products like sunscreen or paint high particle and absorber concentrations are present. An important parameter for slabs of these materials is the diffuse transmission of light, which quantifies the total amount of directly and diffusely transmitted light. Due to the high content of scattering particles not only multiple scattering but also additional dependent scattering occurs. Hence, simple analytical models cannot be applied to calculate the diffuse transmission. In this work a Monte-Carlo program for the calculation of the diffuse transmission of light through dispersions in slab-like geometry containing high concentrations of scattering particles and absorbers is presented and discussed in detail. Mie theory is applied for the calculation of the scattering properties of the samples. Additionally, dependent scattering is considered in two different models, the well-known hard sphere model in the Percus-Yevick approximation (HSPYA) and the Yukawa model in the Mean Spherical Approximation (YMSA). Comparative experiments will show the accurateness of the program as well as its applicability to real samples [1]. (C) 2014 Elsevier Ltd. All rights reserved. KW - Monte-Carlo simulations KW - Multiple light scattering KW - Dependent light scattering KW - Hard sphere model in the Percus-Yevick Approximation KW - Yukawa model in the Mean Spherical Approximation KW - Polymer dispersions Y1 - 2014 U6 - https://doi.org/10.1016/j.jqsrt.2014.01.007 SN - 0022-4073 SN - 1879-1352 VL - 146 SP - 190 EP - 198 PB - Elsevier CY - Oxford ER -