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Bioaccumulation of persistent and hydrophobic organic compounds in the aquatic environment puts secondary consumers, such as fish, at risk. To assess their exposure, monitoring programs with high numbers of individuals have been conducted worldwide over decades that require major efforts and raise ethical issues. This study aimed at testing suspended particulate matter (SPM) as an alternative and accessible abiotic matrix to estimate the internal exposure concentrations of such chemicals in fish and mussels. Muscle tissues of bream (Abramis brama), tissues of zebra mussels (Dreissena polymorpha) and SPM were collected from four major German rivers, Elbe, Danube, Saar and Saale, in 2018 within the national monitoring program of the German Environmental Specimen Bank. We used (i) total solvent extraction for biota samples to quantify the lipid-normalized concentrations of polychlorinated biphenyls, polycyclic aromatic hydrocarbons and hexachlorobenzene and (ii) passive equilibrium sampling of SPM to derive equilibrium partitioning concentrations in lipids and (iii) set these independent data sets into context. Since the ratio of lipid-normalized concentration / equilibrium partitioning concentration in lipids was in most cases < 1.0, SPM may serve as a conservative proxy for the internal concentration of bream and mussels, although bream of high age (i.e., older than 10 years) showed a tendency for this ratio to exceed 1.0. This observation indicates that age-dependent biomagnification can exceed the predictions based on thermodynamic equilibrium relative to SPM., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Bioaccumulation of hydrophobic organic compounds (HOCs) along freshwater food chains is a major environmental concern as top predators in food webs are relevant for human consumption. To characterize and manage the associated risks, considerable numbers of organisms are sampled regularly for monitoring purposes. However, ethical and financial issues call for an alternative, more generic and more robust approach for assessing the internal exposure of fish that circumvents large variability in biota sampling due to interindividual differences. Passive sampling devices (PSDs) offer a fugacity-based approach for pollutant enrichment from different abiotic environmental compartments with a subsequent estimation of bioaccumulation in fish which we explored and compared to HOC concentrations in fish as determined using traditional approaches., Results: In this study, concentrations in silicone-based PSDs applied to the water phase and suspended particulate matter (SPM) of a river polluted with HOCs were used to estimate the concentration in model lipids at thermodynamic equilibrium with either environmental compartment. For comparison, muscle tissue of seven fish species (trophic level 1.8 to 2.8) was extracted using traditional exhaustive solvent extraction, and the lipid-normalized concentrations of HOCs were determined. The PSD-based data from SPM proved to be a more conservative estimator for HOCs accumulated in fish than those from water. Body length of the fish was found to be more suitable to describe increasing accumulation of HOCs than their trophic level as derived from stable isotope analysis and might offer a suitable alternative for future studies., Conclusions: By combining fugacity-based sampling in the abiotic environment, translation into corresponding concentrations in model lipids and body length as an indicator for increasing bioaccumulation in fish, we present a suggestion for a robust approach that may be a meaningful addition to conventional monitoring methods. This approach potentially increases the efficiency of existing monitoring programs without the need to regularly sacrifice vertebrate species., Supplementary Information: The online version contains supplementary material available at 10.1186/s12302-022-00644-w., Competing Interests: Competing interestsThe authors declare that they have no competing interests., (© The Author(s) 2022.)

In the past years, light-emitting diodes (LED) made of GaN and its related ternary compounds with indium and aluminium have become an enabling technology in all areas of lighting. Visible LEDs have yet matured, but research on deep ultraviolet (UV) LEDs is still in progress. The polarisation in the anisotropic wurtzite lattice and the low free hole density in p-doped III-nitride compounds with high aluminium content make the design for high efficiency a critical step. The growth kinetics of the rather thin active quantum wells in III-nitride LEDs makes them prone to inhomogeneous broadening (IHB). Physical modelling of the active region of III-nitride LEDs supports the optimisation by revealing the opaque active region physics. In this work, we analyse the impact of the IHB on the luminescence and carrier transport III-nitride LEDs with multi-quantum well (MQW) active regions by numerical simulations comparing them to experimental results. The IHB is modelled with a statistical model that enables efficient and deterministic simulations. We analyse how the lumped electronic characteristics including the quantum efficiency and the diode ideality factor are related to the IHB and discuss how they can be used in the optimisation process.

Wavelength-dispersive X-ray (WDX) spectroscopy was used to measure silicon atom concentrations in the range 35-100 ppm [corresponding to (3-9) × 1018 cm-3] in doped AlxGa1-xN films using an electron probe microanalyser also equipped with a cathodoluminescence (CL) spectrometer. Doping with Si is the usual way to produce the n-type conducting layers that are critical in GaN- and AlxGa1-xN-based devices such as LEDs and laser diodes. Previously, we have shown excellent agreement for Mg dopant concentrations in p-GaN measured by WDX with values from the more widely used technique of secondary ion mass spectrometry (SIMS). However, a discrepancy between these methods has been reported when quantifying the n-type dopant, silicon. We identify the cause of discrepancy as inherent sample contamination and propose a way to correct this using a calibration relation. This new approach, using a method combining data derived from SIMS measurements on both GaN and AlxGa1-xN samples, provides the means to measure the Si content in these samples with account taken of variations in the ZAF corrections. This method presents a cost-effective and time-saving way to measure the Si doping and can also benefit from simultaneously measuring other signals, such as CL and electron channeling contrast imaging.

Multiresistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) cause serious postoperative infections. A skin tolerant far-UVC (< 240 nm) irradiation system for their inactivation is presented here. It uses UVC LEDs in combination with a spectral filter and provides a peak wavelength of 233 nm, with a full width at half maximum of 12 nm, and an irradiance of 44 µW/cm 2 . MRSA bacteria in different concentrations on blood agar plates were inactivated with irradiation doses in the range of 15-40 mJ/cm 2 . Porcine skin irradiated with a dose of 40 mJ/cm 2 at 233 nm showed only 3.7% CPD and 2.3% 6-4PP DNA damage. Corresponding irradiation at 254 nm caused 15-30 times higher damage. Thus, the skin damage caused by the disinfectant doses is so small that it can be expected to be compensated by the skin's natural repair mechanisms. LED-based far-UVC lamps could therefore soon be used in everyday clinical practice to eradicate multiresistant pathogens directly on humans., (© 2021. The Author(s).)

Biodiversity is under pressure worldwide, with amphibians being particularly threatened. Stressors related to human activity, such as chemicals, are contributing to this decline. It remains, however, unclear whether chemicals exhibiting a fungicidal activity could indirectly affect tadpoles that depend on microbially conditioned leaf litter as food source. The indirect effect of fungicides (sum concentration of a fungicide mixture composed of azoxystrobin, carbendazim, cyprodinil, quinoxyfen, and tebuconazole: 100 µg/L) on tadpoles was assessed relative to leaf litter colonized by microbes in absence of fungicides (control) and a worst-case scenario, that is leached leaf litter without microbial colonization. The quality of leaf litter as food for tadpoles of the European common frog ( Rana temporaria ) was characterized through neutral lipid fatty acid profiles and microbial sum parameters and verified by sublethal responses in tadpoles (i.e., feeding rate, feces production, growth, and fatty acid composition). Fungicides changed the nutritious quality of leaf litter likely through alterations in leaves' neutral lipid fatty acid profiles (i.e., changes in some physiologically important highly unsaturated fatty acids reached more than 200%) in combination with a potential adsorption onto leaves during conditioning. These changes were reflected by differences in the development of tadpoles ultimately resulting in an earlier start of metamorphosis. Our data provide a first indication that fungicides potentially affect tadpole development indirectly through bottom-up effects. This pathway is so far not addressed in fungicide environmental risk assessment and merits further attention., Competing Interests: Several authors are fully or partially involved in the private sectors. We however see no conflict of interest arising from this involvement for the present submission., (© 2021 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

This paper presents the results of the first international comparative study of commonly applied analytical methods for microplastic analysis. Although it was shown that the comparability between previously published studies is highly limited, there are ambitious efforts regarding the standardization of microplastic analysis. This comparative study serves as a first step to assess the suitability of frequently used methods in microplastic research. Furthermore, it highlights obstacles when conducting a comparative study for microplastics. Results from 17 laboratories from eight different countries are compared. Samples comprised of five different types of microplastic reference particles with diameters ranging from 8 µm to 140 μm suspended in ultrapure water. Microscopy, Fourier-transform infrared microspectroscopy (μ-FTIR), Raman microspectroscopy (μ-Raman), thermo-extraction-and-desorption- or pyrolysis- combined with gas chromatography coupled to mass spectrometry (Σ-GC/MS), scanning electron microscopy and particle counter were compared regarding results on total particle number, polymer type, number of particles and/or particle mass for each polymer type. In the scope of this comparative study, for the identification of polymer type μ-Raman and Σ-GC/MS performed best. The quantification of polymer mass for identified polymer types was questionable for Σ-GC/MS, whereas other methods failed to determine the correct polymer mass. Quantification of particle number per identified polymer type was evaluated successful for μ-FTIR and the quantification of total particle numbers was best for microscopy and to a lesser extent for μ-FTIR. Remarkable was the large variance of results between the methods but also within the methods. The latter is likely due to individual interpretations of methods and preparation protocols, in particular in regard to the handling of blank values. Results strongly emphasize the need for standardization and validation of analytical methods in microplastic research both on a global scale as well as in the context of individual laboratories.

Nano-engineering III-nitride semiconductors offers a route to further control the optoelectronic properties, enabling novel functionalities and applications. Although a variety of lithography techniques are currently employed to nano-engineer these materials, the scalability and cost of the fabrication process can be an obstacle for large-scale manufacturing. In this paper, we report on the use of a fast, robust and flexible emerging patterning technique called Displacement Talbot lithography (DTL), to successfully nano-engineer III-nitride materials. DTL, along with its novel and unique combination with a lateral planar displacement (D 2 TL), allow the fabrication of a variety of periodic nanopatterns with a broad range of filling factors such as nanoholes, nanodots, nanorings and nanolines; all these features being achievable from one single mask. To illustrate the enormous possibilities opened by DTL/D 2 TL, dielectric and metal masks with a number of nanopatterns have been generated, allowing for the selective area growth of InGaN/GaN core-shell nanorods, the top-down plasma etching of III-nitride nanostructures, the top-down sublimation of GaN nanostructures, the hybrid top-down/bottom-up growth of AlN nanorods and GaN nanotubes, and the fabrication of nanopatterned sapphire substrates for AlN growth. Compared with their planar counterparts, these 3D nanostructures enable the reduction or filtering of structural defects and/or the enhancement of the light extraction, therefore improving the efficiency of the final device. These results, achieved on a wafer scale via DTL and upscalable to larger surfaces, have the potential to unlock the manufacturing of nano-engineered III-nitride materials., Competing Interests: Conflict of interestThe authors declare that they have no conflict of interest., (© The Author(s) 2019.)

Microplastics are emerging pollutants in water bodies worldwide. The environmental entry areas must be studied to localise their sources and develop preventative and remedial solutions. Rivers are major contributors to the marine microplastics load. Here, we focus on a specific type of plastic microbead (diameter 286-954 μm, predominantly opaque, white-beige) that was repeatedly identified in substantial numbers between kilometres 677 and 944 of the Rhine River, one of Europe's main waterways. Specifically, we aimed (i) to confirm the reported abrupt increase in microbead concentrations between the cities of Leverkusen and Duisburg and (ii) to assess the concentration gradient of these particles along this stretch at higher resolution. Furthermore, we set out (iii) to narrow down the putative entry stretch from 81.3 km, as reported in an earlier study, to less than 20 km according to our research design, and (iv) to identify the chemical composition of the particles and possibly reveal their original purpose. Surface water filtration (mesh: 300 μm, n = 9) at regular intervals along the focal river stretch indicated the concentration of these spherules increased from 0.05 to 8.3 particles m -3 over 20 km. This spot sampling approach was supported by nine suspended solid samples taken between 2014 and 2017, encompassing the river stretch between Leverkusen and Duisburg. Ninety-five percent of microbeads analysed (202/212) were chemically identified as crosslinked polystyrene-divinylbenzene (PS-DVB, 146/212) or polystyrene (PS, 56/212) via Raman or Fourier-transform infrared spectroscopy. Based on interpretation of polymer composition, surface structure, shape, size and colour, the PS(-DVB) microbeads are likely to be used ion-exchange resins, which are commonly applied in water softening and various industrial purification processes. The reported beads contribute considerably to the surface microplastic load of the Rhine River and their potential riverine entry area was geographically narrowed down., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

For the past several years, an increasing number of schools across Europe have been using the Samurai School Program successfully. In 2015, it was also introduced in the United States with great acceptance. The program is aimed at treatment of children on the autistic spectrum, including those with attention-deficit hyperactivity disorder or similar disorders. Given that such children lack social skills and may be prone to violence, treating this disorder is of concern. The objective of the Samurai School Program is to address social and violent tendencies in youth.