Thermomechanical effects in uniformly aligned dye-doped nematic liquid crystals

We show theoretically that thermomechanical effects in dye-doped nematic liquid crystals when illuminated by laser beams, can become important and lead to molecular reorientation at intensities substantially lower than that needed for optical Fr\'eedericksz transition. We propose a 1D model that assumes homogenous intensity distribution in the plane of the layer and is capable to describe such a thermally induced threshold lowering. We consider a particular geometry, with a linearly polarized light incident perpendicularly on a layer of homeotropically aligned dye-doped nematics

Insect antimicrobial peptides: potential weapons to counteract the antibiotic resistance

Misuse and overuse of antibiotics have contributed in the last decades to a phenomenon known as antibiotic resistance which is currently considered one of the principal threats to global public health by the World Health Organization. The aim to find alternative drugs has been demonstrated as a real challenge. Thanks to their biodiversity, insects represent the largest class of organisms in the animal kingdom. The humoral immune response includes the production of antimicrobial peptides (AMPs) that are released into the insect hemolymph after microbial infection. In this review, we have focused on insect immune responses, particularly on AMP characteristics, their mechanism of action and applications, especially in the biomedical field. Furthermore, we discuss the Toll, Imd, and JAK-STAT pathways that activate genes encoding for the expression of AMPs. Moreover, we focused on strategies to improve insect peptides stability against proteolytic susceptibility such as D-amino acid substitutions, N-terminus modification, cyclization and dimerization

Every animal matters! Evaluating the selectivity of a Mediterranean bottom trawl fishery from a species community perspective

Bottom trawl fisheries often catch several species simultaneously. However, most studies addressing the catch performance and selectivity of a specific trawl focus on a few commercially important or most vulnerable species requiring management measures. By contrast, the present study considers the multispecies nature of Mediterranean bottom trawl fisheries through a holistic approach that accounts for the full species community in the catches. Specifically, we evaluated and compared the catch performance of the two codends allowed for this fishery, made of 40 mm square (SM40) and 50 mm diamond (DM50) meshes. Results showed that 50 and 80% of the catch in weight and count numbers, respectively, consisted of species without commercial value, demonstrating that large proportions of the catch are not considered when using the existing approach to evaluate the ecological impact of the fishing activity. Significant differences in catch profiles between the two codends were observed, especially for two commercial flatfish species, Arnoglossus laterna and Citharus linguatula, with larger contributions in the SM40. Further, the SM40 codend had a significantly higher retention, compared to DM50 codend, for specific sizes of Merluccius merluccius and Mullus barbatus. The outcomes of the study can be useful for the Mediterranean bottom trawl fisheries management

Insect antimicrobial peptides: potential weapons to counteract the antibiotic resistance

Misuse and overuse of antibiotics have contributed in the last decades to a phenomenon known as antibiotic resistance which is currently considered one of the principal threats to global public health by the World Health Organization. The aim to find alternative drugs has been demonstrated as a real challenge. Thanks to their biodiversity, insects represent the largest class of organisms in the animal kingdom. The humoral immune response includes the production of antimicrobial peptides (AMPs) that are released into the insect hemolymph after microbial infection. In this review, we have focused on insect immune responses, particularly on AMP characteristics, their mechanism of action and applications, especially in the biomedical field. Furthermore, we discuss the Toll, Imd, and JAK-STAT pathways that activate genes encoding for the expression of AMPs. Moreover, we focused on strategies to improve insect peptides stability against proteolytic susceptibility such as D-amino acid substitutions, N-terminus modification, cyclization and dimerization

Surface alignment of ferroelectric nematic liquid crystals

none8The success of nematic liquid crystals in displays and optical applications is due to the combination of their optical uniaxiality, fluidity, elasticity, responsiveness to electric fields and controllable coupling of the molecular orientation at the interface with solid surfaces. The discovery of a polar nematic phase opens new possibilities for liquid crystal-based applications, but also requires a new study of how this phase couples with surfaces. Here we explore the surface alignment of the ferroelectric nematic phase by testing different rubbed and unrubbed substrates that differ in coupling strength and anchoring orientation and find a variety of behaviors - in terms of nematic orientation, topological defects and electric field response - that are specific to the ferroelectric nematic phase and can be understood as a consequence of the polar symmetry breaking. In particular, we show that by using rubbed polymer surfaces it is easy to produce cells with a planar polar preferential alignment and that cell electrostatics (e.g.grounding the electrodes) has a remarkable effect on the overall homogeneity of the ferroelectric ordering.openCaimi F.; Nava G.; Barboza R.; Clark N.A.; Korblova E.; Walba D.M.; Bellini T.; Lucchetti L.Caimi, F.; Nava, G.; Barboza, R.; Clark, N. A.; Korblova, E.; Walba, D. M.; Bellini, T.; Lucchetti, L

Elasticity and Viscosity of DNA Liquid Crystals

Concentrated solutions of blunt-ended DNA oligomer duplexes self-assemble in living polymers and order into lyotropic nematic liquid crystal phase. Using the optical torque provided by three distinct illumination geometries, we induce independent splay, twist, and bend deformations of the DNA nematic and measure the corresponding elastic coefficient

Mineralogical and geochemical characterisation of open-air tailing and waste-rock dumps from the Libiola Fe-Cu sulphide mine (Eastern Liguria, Italy)

Active acid mine drainage (AMD) processes at the Libiola Fe-Cu sulphides mine are mainly triggered by water–rock interaction occurring within open-air tailing and waste-rock dumps. These processes are mainly controlled by exposure to weathering agents, the grain size of the dumped materials, and by the quantity of sulphides, the sulphide types, and their mode of occurrence. Due to these factors, several paragenetic stages of evolution have been recognised at different depths at different sites and within the same site. The dump samples were investigated with mineralogical (reflected- and transmitted-light optical microscopy, XRPD, and SEM-EDS) and geochemical (ICP-AES, Leco) techniques. The AMD evaluation of the tailing and waste-rock samples was performed by calculating the Maximum Potential Acidity, the Acid Neutralising Capacity, (and the Net Acid Producing Potential. The results allowed us to demonstrate that the open-air tailings had already superseded their AMD apex and are now practically inert material composed mainly of stable goethite ± lepidocrocite ± hematite assemblages. On the contrary, the sulphide-rich waste rocks still have a strong potential to produce long term AMD, causing the acidification of circulating waters and the release of several hazardous elements