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ABSTRACT Lugdunin is a microbiome-derived antibacterial agent with good activity against Gram-positive pathogens in vitro and in animal models of nose colonization and skin infection. We have previously shown that lugdunin depletes bacterial energy resources by dissipating the membrane potential of Staphylococcus aureus. Here, we explored the mechanism of action of lugdunin in more detail and show that lugdunin quickly depolarizes cytoplasmic membranes of different bacterial species and acidifies the cytoplasm of S. aureus within minutes due to protonophore activity. Varying the salt species and concentrations in buffers revealed that not only protons are transported, and we demonstrate the binding of the monovalent cations K+, Na+, and Li+ to lugdunin. By comparing known ionophores with various ion transport mechanisms, we conclude that the ion selectivity of lugdunin largely resembles that of 15-mer linear peptide gramicidin A. Direct interference with the main bacterial metabolic pathways including DNA, RNA, protein, and cell wall biosyntheses can be excluded. The previously observed synergism of lugdunin with dermcidin-derived peptides such as DCD-1 in killing S. aureus is mechanistically based on potentiated membrane depolarization. We also found that lugdunin was active against certain eukaryotic cells, however strongly depending on the cell line and growth conditions. While adherent lung epithelial cell lines were almost unaffected, more sensitive cells showed dissipation of the mitochondrial membrane potential. Lugdunin seems specifically adapted to its natural environment in the respiratory tract. The ionophore mechanism is refractory to resistance development and benefits from synergy with host-derived antimicrobial peptides.IMPORTANCEThe vast majority of antimicrobial peptides produced by members of the microbiome target the bacterial cell envelope by many different mechanisms. These compounds and their producers have evolved side-by-side with their host and were constantly challenged by the host’s immune system. These molecules are optimized to be well tolerated at their physiological site of production, and their modes of action have proven efficient in vivo. Imbalancing the cellular ion homeostasis is a prominent mechanism among antibacterial natural products. For instance, over 120 naturally occurring polyether ionophores are known to date, and antimicrobial peptides with ionophore activity have also been detected in microbiomes. In this study, we elucidated the mechanism underlying the membrane potential-dissipating activity of the thiazolidine‐containing cycloheptapeptide lugdunin, the first member of the fibupeptides discovered in a commensal bacterium from the human nose, which is a promising future probiotic candidate that is not prone to resistance development.

Abstract Key message The application of material selection principles uncovered eight possible alternative tree species (two deciduous and six coniferous species) to substitute Norway spruce (Picea abies (L.) H. Karst.) and potentially prevent economic loss in European forest. Context Climate change is a major challenge for the Central European forest and timber industry. Increasing biotic (e.g. beetle damage) and abiotic (e.g. drought) calamities have led to major losses in forest value, especially on Norway spruce (Picea abies (L.) H. Karst.) stands. Therefore, a transition to climate change adapted forest management is necessary. Concurrently, neophytes (e.g. tree of heaven (Ailanthus altissima (Mill.) Swingle), Douglas fir (Pseudotsuga menziesii (Mirbel) Franco), grand fir (Abies grandis (Douglas ex D. Don) Lindl.) and Paulownia (Paulownia tomentosa (Thunb.) Steud.)) are increasing their dominance in forest communities and causing additional adaption of the forest ecosystem. Both factors will lead to significant changes in wood species distributions in Central European forests, mainly at the expanse of Norway spruce, over the next decades. Aims Choosing the “right” tree species for afforestation will become ever more complex and will require a holistic approach that combines forestry and technological aspects alike. Therefore, this review presents a selection approach based on available wood material data from literature and the material selection principles proposed by M. Ashby with the aim to identify suitable alternatives for Norway spruce (Picea abies (L.) H. Karst.) and further concisely assess their silvicultural relevance. Methods For this wood species comparison and selection process, dry and raw density, bending strength and modulus of elasticity were chosen as key properties. Beam- and plate-like components subjected to a bending load were chosen as representative use cases. Results European birch (Betula spp.), grand fir (Abies grandis (Douglas ex D. Don) Lindl.) and silver fir (Abies alba Mill.) were identified as suitable alternatives for Norway spruce (Picea abies (L.) H. Karst.) from a technological as well as silvicultural point of view. In addition, Paulownia (Paulownia tomentosa (Thunb.) Steud.), Sitka spruce (Picea sitchensis (Bong.) Carrière), yellow pine (Pinus strobus L.), western red cedar (Thuja plicata Donn ex D. Don in Lambert) and loblolly pine (Pinus taeda L.) offer a technological advantage but currently lack relevance in the forest sector. Conclusion The proposed selection process offers an evaluation of technical performance, and in combination with an assessment of the silvicultural relevance, it will be possible to optimize the wood-supply chain and prevent future economic loss of Central European forests.

In a scenario of increasing alarm about food waste due to rapid urbanization, population growth and lifestyle changes, this study aims to explore the valorization of waste from the retail sector as potential substrates for the biotechnological production of biosurfactants. With a perspective of increasingly contributing to the realization of the circular bioeconomy, a vegetable juice, derived from unsold fruits and vegetables, as a carbon source was used to produce lipopeptides such as surfactin and fengycin. The results from the shake flask cultivations revealed that different concentrations of vegetable juice could effectively serve as carbon sources and that the fed-batch bioreactor cultivation strategy allowed the yields of lipopeptides to be significantly increased. In particular, the product/substrate yield of 0.09 g/g for surfactin and 0.85 mg/g for fengycin was obtained with maximum concentrations of 2.77 g/L and 27.53 mg/L after 16 h, respectively. To conclude, this study provides the successful fed-batch cultivation of B. subtilis using waste product as the carbon source to produce secondary metabolites. Therefore, the consumption of agricultural product wastes might be a promising source for producing valuable metabolites which have promising application potential to be used in several fields of biological controls of fungal diseases.

Hydraulic testing of isolated sapwood from mature tree trunks is time-consuming and prone to errors, whereas the measurement of compression strength is a standardized and rapid wood technological application. In this study, we aimed to analyze if compression stress perpendicular to the grain relates to hydraulic vulnerability of mature Norway spruce (Picea abies) trunk wood with an expected narrow vulnerability range. The sample-set comprised 52 specimens originating from 34 trees harvested in Sweden. Before mechanical testing, the P50, i.e., the water potential resulting in 50 % of hydraulic conductivity loss, was estimated on small sapwood beams employing the air injection method. Compression strength perpendicular to the grain was defined as the first peak of a stress-strain curve (peak stress) when the wood is subjected to radial compression. Peak stress ranged between 1,65 MPa and 5,07 MPa, P50 between -2,98 MPa and -1,98 MPa. We found a good correlation between the peak stress and P50 (r = 0,80; P < 0,0001). This provides further evidence that peak stress in radial compression and P50 are both extremely dependent on the characteristics of the “weakest” wood part, i.e., the highly conductive earlywood. We conclude that the radial compression strength is a good proxy for P50 of mature Norway spruce trunk wood.

Abstract Polycyclic aromatic hydrocarbons, such as pyrenes, are a well‐known material class for non‐covalent modification of carbon surfaces in many applications. In electrochemical energy storage, pyrenes are mostly used in large polymeric structures. This work addresses the use of carboxy‐ and amino‐functionalized pyrenes for graphite electrodes for lithium‐ion batteries (LIBs). Pyrenes are explored as adsorbed species on graphite prior to electrode fabrication and as additives to the electrode composition. Thereby, 1‐pyrenecarboxylic acid, 1‐pyrenebutyric acid, 1‐aminopyrene, and 1‐pyrenebutylamine were under investigation. As additives, pyrenes do not influence the cycling performance of the electrode at low current but deteriorate the performance at high current, regardless of the functional group. However, when the pyrenes are adsorbed to the graphite surface, the influence of the different functional groups becomes clearly visible, revealing that an additional butyl group has a positive impact on the cycling performance and lithium‐ion transport of the electrodes. Electrodes with 1‐pyrenebutyric acid even enhanced the performance compared to the pristine electrode.

For many purposes related to the bonding of wood substrates, one-component polyurethane adhesives (1C-PUR) are of great significance. 1C-PUR adhesives are widely used, especially in the cross laminated timber (CLT) production. One major benefit is their ability to be pressed at room temperature. However, not only pressing temperature but also the pressing time is an important economic aspect for manufacturers. Knowing the minimum possible press time offers an economic advantage, however, there have been only few publications on this topic so far. The aim of this work was to investigate and evaluate various aspects of a 1C-PUR adhesive with regard to the minimum pressing time comparing newly developed knowledge-based approaches. The analysis included the strength development of the advanced curing of the adhesive, the development of the final internal bond strength and the minimum required press time for bonded joints to withstand imposed stress. The influence of the wood moisture content and closed assembly time were also investigated. The present study found that closed assembly time had a favourable influence on the required press time period. With immediate testing of the glued joint it also revealed a quicker strength development with lower strength values at a higher wood moisture content. [ABSTRACT FROM AUTHOR]

Comparative analysis of the chemical and rheological curing kinetics of formaldehyde-based wood adhesives is crucial for assessing their respective performance. Differential scanning calorimetry (DSC) and rheometry are the conventional techniques used for monitoring the curing processes leading to crosslinking polymerization of the adhesives. However, the direct comparison of these techniques is inappropriate due to the intrinsic differences in their underlying procedures. To address this challenge, the two adhesive samples were sequentially cured, firstly with rheometry and followed by DSC. The observed higher curing degree in the subsequent DSC procedure underpins the incomplete curing of the samples during initial rheometry. Furthermore, the comparative assessment of the activation energies, molar ratios, and active groups of the two adhesives highlights the importance of the pre-exponential factor in addition to the activation energies, as it attributes to the probability of active groups coinciding at the appropriate spatial arrangement. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging (MR)-guided online adaptive radiotherapy is a promising technique in the field of radiation oncology providing excellent visualisation of soft-tissues, and allowing for online plan adaptation and tumour tracking. In order to facilitate the accurate dose delivery to the target volume while sparing healthy surrounding normal tissue in the brain or head-and-neck (H&N) region, precise patient immobilisation with good image quality is pertinent. Herein, we present a customised thermoplastic mask holder with an integrated anterior MR receiver coil support system for MR-guided online adaptive radiotherapy in the brain and head-and-neck region. The approved medical product was developed by Innovative Technologie Voelp (IT-V), Innsbruck, Austria. MR image uniformity measurements demonstrated improved image uniformity at the expense of decreased signal-to-noise ratio due to a more defined and larger distance between the anterior receiver coil and the phantom or patient. This integrated coil support system represents a practical solution facilitating stable and reproducible anterior coil placement while maintaining the thermoplastic mask holder functionality, a widely established immobilisation technique.

Abstract Subject to this study is the modification of an experimental two-component polyurethane (2C PUR) as an alternative adhesive for structural hardwood bonding. The 2C PUR has been adapted by calcium carbonate as filler to increase its modulus of elasticity with the aim of increasing the modulus analogue to the ones typically observed for classic amino- and phenol based adhesives. The 2C PUR system was compared with a commercial one-component polyurethane (1C PUR) and a phenol resorcinol formaldehyde (PRF) adhesive. The wetting properties of the adhesives were tested in terms of surface tension, polar and dispersive part and contact angle on European beech wood (Fagus sylvatica L.). In addition, adhesive polymer films of 2C PUR were tested for tensile strength and modulus of elasticity (E-Modulus) following ISO 527-1. The adhesives bond performance on beech wood was determined by lap-joints according to EN 302-1 in various climate conditions. The results show that 2C PUR has proper wettability properties on beech wood. Adding 60% wt filler to the polyol component increased the E-Modulus from 2.3 GPa (0%) to 4.4 GPa. The tensile strength of the modified 2C PUR polymer films was comparable with the industrial 1C PUR. Tensile shear strength and wood failure percentage of 2C PUR lap-joints were increased by adding filler and met requirements in dry and re-dried conditions according to EN 302-1. However, the addition of filler didn’t result in an improvement in wet conditions. The present study shows sufficient performance for bonding hardwood with 2C PUR in dry conditions, while the system still needs to be improvement regarding its performance in humid conditions.

Using a combination of two-photon imaging and single-cell electrophysiology, the authors discover that associative learning induces the emergence of a unique subset of neurons in the auditory cortex, exhibiting high-rate bursting responses to the learned complex sounds but not to any of the constituents.

The work consists of primary and analysed data from rheological measurements of carbohydrate-hydroxymethylfurfural-amine adhesives. The studied adhesives are a bio-based alternative to conventional wood adhesives. The rheological properties were studied at different temperatures in isothermal (80, 90, 95 °C) and non-isothermal (20–120 °C) oscillatory measurements. Non-isothermal rheological measurements were used for the determination of the activation energy based on Vyazovskin's isoconversional method. The viscosity profile of the adhesives, determined from isothermal measurements, was fitted by an empirical model. The viscosity kinetic constant can be obtained from this empirical model and used in further rheokinetic analysis.Data from density and swelling experiments was measured for the characterization of the adhesive network. The determined polymer-solvent interaction parameter is included in the collected data.The provided datasets were used in the investigation of the reactivity and curing reaction of the studied adhesives. A discussion and interpretation of the data can be found in the previous publication [1].

Summary: Glutamatergic neurotransmission is a widespread form of synaptic excitation in the mammalian brain. The development of genetically encoded fluorescent glutamate sensors allows monitoring synaptic signaling in living brain tissue in real time. Here, we describe single- and two-photon imaging of synaptically evoked glutamatergic population signals in acute hippocampal slices expressing the fluorescent glutamate sensor SF-iGluSnFR.A184S in CA1 or CA3 pyramidal neurons. The protocol can be readily used to study defective synaptic glutamate signaling in mouse models of neuropsychiatric disorders, such as Alzheimer disease.For complete details on the use and execution of this protocol, please refer to Zott et al. (2019).