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Significance: Current open-source Monte Carlo (MC) method implementations for light propagation modeling are many times tedious to build and require third-party licensed software that can often discourage prospective researchers in the biomedical optics community from fully utilizing the light propagation tools. Furthermore, the same drawback also limits rigorous cross-validation of physical quantities estimated by various MC codes. Aim: Proposal of an open-source tool for light propagation modeling and an easily accessible dataset to encourage fruitful communications amongst researchers and pave the way to a more consistent comparison between the available implementations of the MC method. Approach: The PyXOpto implementation of the MC method for multilayered and voxelated tissues based on the Python programming language and PyOpenCL extension enables massively parallel computation on numerous OpenCL-enabled devices. The proposed implementation is used to compute a large dataset of reflectance, transmittance, energy deposition, and sampling volume for various source, detector, and tissue configurations. Results: The proposed PyXOpto agrees well with the original MC implementation. However, further validation reveals a noticeable bias introduced by the random number generator used in the original MC implementation. Conclusions: Establishing a common dataset is highly important for the validation of existing and development of MC codes for light propagation in turbid media.

Novel low-cost portable spectrophotometers could be an alternative to traditional spectrophotometers and calibrated RGB cameras by offering lower prices and convenient measurements but retaining high colorimetric accuracy. This study evaluated the colorimetric accuracy of low-cost, portable spectrophotometers on the established color calibration target—RAL Design System Plus (RAL+). Four spectrophotometers with a listed price between USD 100–1200 (Nix Spectro 2, Spectro 1 Pro, ColorReader, and Pico) and a smartphone RGB camera were tested on a representative subset of 183 RAL+ colors. Key performance metrics included the devices’ ability to match and measure RAL+ colors in the CIELAB color space using the color difference CIEDE2000 ΔE. The results showed that Nix Spectro 2 had the best performance, matching 99% of RAL+ colors with an estimated ΔE of 0.5–1.05. Spectro 1 Pro and ColorReader matched approximately 85% of colors with ΔE values between 1.07 and 1.39, while Pico and the Asus 8 smartphone matched 54–77% of colors, with ΔE of around 1.85. Our findings showed that low-cost, portable spectrophotometers offered excellent colorimetric measurements. They mostly outperformed existing RGB camera-based colorimetric systems, making them valuable tools in science and industry.

Povzetek. Hiperspektralni slikovni sistem smo uporabili za zajemanje povratno sipane svetlobe in na podlagi zajete informacije dolocili opticne lastnosti sipajocih medijev. V ta namen smo uporabili Monte Carlo simulacije širjenja svetlobe skozi polneskoncen homogen medij in z njihovo pomocjo izdelali iskalne tabele, s katerimi smo dolocili opticne lastnosti. Hiperspektralni slikovni sistem nam omogoca, da povratno sipano svetlobo zajamemo na vec razlicnih razdaljah med virom in tipalom svetlobe, kar pripomore k robustnosti inverznega modela. V študiji smo delovanje inverznega modela najprej ovrednotili s sinteticnimi podatkovnimi nizi, na koncu pa smo metodo ovrednotili še na hiperspektralnih slikah opticnih fantomov, katerih opticne lastnosti lahko izracunamo po analitični poti.

Structurally anisotropic materials are ubiquitous in several application fields, yet their accurate optical characterization remains challenging due to the lack of general models linking their scattering coefficients to the macroscopic transport observables, and the need to combine multiple measurements to retrieve their direction-dependent values. Here, we present an improved method for the experimental determination of light transport tensor coefficients from the diffusive rates measured along all three directions, based on transient transmittance measurements and a generalized Monte Carlo model. We apply our method to the characterization of light transport properties in two common anisotropic materials - polytetrafluoroethylene (PTFE) tape and paper - highlighting the magnitude of systematic deviations that are typically incurred when neglecting anisotropy.

Diffuse reflectance spectroscopy (DRS) is often used to analyze the biological samples. In order to characterize the experimental setup system and the measurement analysis method, the biomedical samples are normally replaced by more accessible and durable optical phantoms comprising different absorbers and scatterers that guarantee similar optical properties between the samples and phantoms. However, durability of the phantoms is still limited, especially due to the molecular dye absorbers (commonly found in the fountain pen inks) which can fade in the sunlight. Therefore, we quantified durability of the ink absorbers in the water phantoms with respect to the sunlight exposure and storage time. The results show that the ink absorbers are differently susceptible to the sunlight. Absorbance of the most durable ink does not change during two months. In contrast, the most sensitive ink exhibits an 80 % absorbance drop under a direct sunlight. What is more, there is a decrease in the absorbance even when the absorbers are not exposed to the light. It is likely that durability of some inks is affected by other environmental factors such as the pH values which can result in conformation changes. Therefore, it is crucial to analyze susceptibility of the ink absorbers to the sunlight and other environmental factors before utilizing them in optical phantoms fabrication.

Diffuse reflectance spectroscopy (DRS) is often used to analyze the biological samples. In order to characterize the experimental setup system and the measurement analysis method, the biomedical samples are normally replaced by more accessible and durable optical phantoms comprising different absorbers and scatterers that guarantee similar optical properties between the samples and phantoms. However, durability of the phantoms is still limited, especially due to the molecular dye absorbers (commonly found in the fountain pen inks) which can fade in the sunlight. Therefore, we quantified durability of the ink absorbers in the water phantoms with respect to the sunlight exposure and storage time. The results show that the ink absorbers are differently susceptible to the sunlight. Absorbance of the most durable ink does not change during two months. In contrast, the most sensitive ink exhibits an 80 % absorbance drop under a direct sunlight. What is more, there is a decrease in the absorbance even when the absorbers are not exposed to the light. It is likely that durability of some inks is affected by other environmental factors such as the pH values which can result in conformation changes. Therefore, it is crucial to analyze susceptibility of the ink absorbers to the sunlight and other environmental factors before utilizing them in optical phantoms fabrication.

Background Recently, mammalian orthoreoviruses (MRVs) were detected for the first time in European bats, and the closely related strain SI-MRV01 was isolated from a child with severe diarrhoea in Slovenia. Genetically similar strains have also been reported from other mammals, which reveals their wide host distribution. The aim of this study was to retrospectively investigate the occurrence and genetic diversity of MRVs in bats in Slovenia, from samples obtained throughout the country in 2008 to 2010, and in 2012 and to investigate the occurrence of the novel SI-MRV01 MRV variant in Slovenian bats. Results The detection of MRVs in bat guano was based on broad-range RT-PCR and specific bat MRV real-time RT-PCR. Subsequently, MRV isolates were obtained from cell culture propagation, with detailed molecular characterisation through whole-genome sequencing. Overall, bat MRVs were detected in 1.9% to 3.8% of bats in 2008, 2009 and 2012. However, in 2010 the prevalence was 33.0%, which defined an outbreak of the single SI-MRV01 strain. Here, we report on the identification of five MRV isolates of different serotypes that are designated as SI-MRV02, SI-MRV03, SI-MRV04, SI-MRV05 and SI-MRV06. There is high genetic variability between these characterised isolates, with evident genome reassortment seen across their genome segments. Conclusions In conclusion, we have confirmed the presence of the SI-MRV01 strain in a Slovenian bat population. Moreover, according to genetic characterisation of S1 genome segment, all three MRV serotypes were present in the bat population. In this study, five independent MRV isolates were obtained and detailed whole genome analysis revealed high diversity between them. This study generates new information about the epidemiology and molecular characteristics of emerging bat MRV variants, and provides important molecular data for further studies of their pathogenesis and evolution.