Occurrence of UV filters 4-methylbenzylidene camphor and octocrylene in fish from various Swiss rivers with inputs from wastewater treatment plants

UV filters are widely used compounds in many personal care products and cosmetics, such as sunscreens. After use, UV filters are washed off from skin and clothes and enter the aquatic environment. Recent studies indicate that some lipophilic UV filters do accumulate in biota and act as endocrine disruptors. In this study, concentrations of 4-MBC (4-methylbenzylidene camphor) and OC (octocrylene), two widely used UV filters, were determined in the muscle tissue of fish (brown trout, Salmo trutta fario) from seven small Swiss rivers, all receiving inputs from wastewater treatment plants (WWTPs). Lipid-weight based concentrations of up to 1800 (4-MBC) and 2400 ng g(-1) (OC) were found. These levels were distinctly higher than those previously observed in white fish (Coregonus sp.) and roach (Rutilus rutilus) from Swiss lakes with inputs from WWTPs. This suggests a higher availability of these contaminants for fish in rivers than in lakes and identifies WWTPs as a major source for UV filters in the aquatic environment. As compared to lake fish, individual fish from a river showed much greater variation in 4-MBC and OC concentrations, likely as a result of a wider range of exposure in rivers than in lakes. 4-MBC concentrations correlated reasonably well with concentrations of methyl triclosan, a chemical marker for lipophilic WWTP-derived contaminants. The ratio P/Q of population (P) in a watershed to water throughflow (Q) is considered to be a measure of the domestic burden from WWTPs. A correlation of methyl triclosan with P/Q was previously observed with lake fish. However, such a correlation could not be confirmed with river fish. The higher average concentrations of OC as compared to 4-MBC in river fish, and the fact that OC was mostly absent in lake fish, suggests differences in bioaccumulation and availability of these two UV filters.     

Observer-based control for high order delayed systems with an unstable pole and a pole at the origin

Time delays in dynamical systems are challenging when trying to control them. One of the most common techniques consists in estimating one or more signals of interest before they are delayed, in order to use them in the control stage. In this work, an observer-based control strategy for unstable linear systems with a pole at the origin and delay is suggested. Also, the proposed observer is extended to be used in the case of a high order unstable delayed system. Likewise, the conditions to ensure the existence of the proposed observer-predictor are presented. A methodology is introduced to obtain the observer parameters. The proposed observer scheme makes use of a Proportional-Integral-Derivative control that makes it possible to ensure the tracking of step-type references and the rejection of disturbances of the same type in the closed-loop system.     

Recovery of Hydroxytyrosol from Olive Mill Wastewater Using the Promiscuous Hydrolase/Acyltransferase PestE

Olive mill wastewater (OMWW) is produced annually during olive oil extraction and contains most of the health-promoting 3-hydroxytyrosol of the olive fruit. To facilitate its recovery, enzymatic transesterification of hydroxytyrosol (HT) was directly performed in an aqueous system in the presence of ethyl acetate, yielding a 3-hydroxytyrosol acetate rich extract. For this, the promiscuous acyltransferase from Pyrobaculum calidifontis VA1 (PestE) was engineered by rational design. The best mutant for the acetylation of hydroxytyrosol (PestE_I208A_L209F_N288A) was immobilized on EziG² beads, resulting in hydroxytyrosol conversions between 82 and 89 % in one hour, for at least ten reaction cycles in a buffered hydroxytyrosol solution. Due to inhibition by other phenols in OMWW the conversions of hydroxytyrosol from this source were between 51 and 62 %. In a preparative scale reaction, 13.8 mg (57 %) of 3-hydroxytyrosol acetate was extracted from 60 mL OMWW.     

Additive Manufacturing of Tool Steels

The public funded project “AddSteel” aims to develop functionally adapted steel materials for additive manufacturing (AM). Based on the AM process laser powder bed fusion (LPBF), the holistic process chain, including alloy design, powder atomization, AM, and postheat treatment, is considered to achieve this objective. Tool steels are usually characterized by higher carbon content and limited weldability, leading to limited processability for LPBF. To extend these limitations, different approaches for tool steels are investigated: for high-carbon tool steels, the effects of lower martensite start temperature are investigated using the alloy 1.2842 as an example. A low martensite start temperature seems to be advantageous for crack-free processing with LPBF. In order to avoid a high hardness level after rapid cooling, the use of a hot work steel with a carbon content of 0.2 wt% is investigated. Due to the chemical composition of the material, a moderate preheating temperature <300 °C is required. In addition, very high scanning speeds are possible with an improved shielding gas flow. Finally, the experience along the process chain with the standard steels is used for a modification of the alloy 1.2344. The effects of this modification on AM and heat treatment are investigated.     

Formation of Supramolecular Gels from Host–Guest Interactions between PEGylated Chitosan and α-Cyclodextrin

Chitosan-based hydrogels are prepared via the formation of polypseudorotaxanes (PPR), by selectively threading α-cyclodextrin (α-CD) macrocycles onto polymeric chains, which, through the formation of microcrystalline domains, act as junction points for the network. Specifically, host–guest inclusion complexes are formed between α-CD and PEGylated chitosan (PEG-Ch), resulting in the formation of supramolecular gels. PEG-grafted chitosan is obtained with a reaction yield of 79.8%, a high degree of grafting (50.9% GW) and water solubility (≈16 mg mL⁻¹), as assessed by turbidimetry. A range of compositions for mixtures of PEG-Ch solutions (0.2–0.8% w/w) and α-CD solutions (2−12% w/w, or 0.04–0.2% mol) are studied. Regardless of PEG content, gels are not formed at low α-CD concentrations (<4%). Dynamic rheology measurements reveal stiff gels (G’ above 15k) and a narrow linear viscoelastic region, reflecting their brittleness. The highest elastic modulus is obtained for a hydrogel composition of 0.4% PEG-Ch and 6% α-CD. Steady-state measurements, cycling between low and high shear rates, confirm the thixotropic nature of the gels, demonstrating their capacity to fully recover their mechanical properties after being exposed to high stress, making them good candidates to use as in-situ gel-forming materials for drug delivery to topical or parenteral sites.     

Generation of Cannabigerolic Acid Derivatives and Their Precursors by Using the Promiscuity of the Aromatic Prenyltransferase NphB

NphB is an aromatic prenyltransferase with high promiscuity for phenolics including flavonoids, isoflavonoids, and plant polyketides. It has been demonstrated that cannabigerolic acid is successfully formed by the reaction catalysed by NphB using geranyl diphosphate and olivetolic acid as substrates. In this study, the substrate specificity of NphB was further determined by using olivetolic acid derivatives as potential substrates for the formation of new synthetic cannabinoids. The derivatives differ in the hydrocarbon chain attached to C6 of the core structure. We performed in silico experiments, including docking of olivetolic acid derivatives, to identify differences in their binding modes. Substrate acceptance was predicted. Based on these results, a library of olivetolic acid derivatives was constructed and synthesized by using different organic synthetic routes. Conversion was monitored in in vitro assays with purified NphB versions. For the substrates leading to a high conversion olivetolic acid-C8, olivetolic acid-C2 and 2-benzyl-4,6-dihydroxybenzoic acid, the products were further elucidated and identified as cannbigerolic acid derivatives. Therefore, these substrates show potential to be adapted in cannabinoid biosynthesis.     

The Role of Trp79 in β-Actin on Histidine Methyltransferase SETD3 Catalysis

N^τ-methylation of His73 in actin by histidine methyltransferase SETD3 plays an important role in stabilising actin filaments in eukaryotes. Mutations in actin and overexpression of SETD3 have been related to human diseases, including cancer. Here, we investigated the importance of Trp79 in β-actin on productive human SETD3 catalysis. Substitution of Trp79 in β-actin peptides by its chemically diverse analogues reveals that the hydrophobic Trp79 binding pocket modulates the catalytic activity of SETD3, and that retaining a bulky and hydrophobic amino acid at position 79 is important for efficient His73 methylation by SETD3. Molecular dynamics simulations show that the Trp79 binding pocket of SETD3 is ideally shaped to accommodate large and hydrophobic Trp79, contributing to the favourable release of water molecules upon binding. Our results demonstrate that the distant Trp79 binding site plays an important role in efficient SETD3 catalysis, contributing to the identification of new SETD3 substrates and the development of chemical probes targeting the biomedically important SETD3.