Coumarins from Seseli devenyense Simonk.: Isolation by Liquid–Liquid Chromatography and Potential Anxiolytic Activity Using an In Vivo Zebrafish Larvae Model

Different types of anxiety disorders have become the number one mental health issue in developed countries. The search for new, safer and effective drug-like molecules among naturally derived substances faces two difficulties: an efficient method of isolation compounds with a high-purity and high-throughput animal model for activity assay. Thus, the aim of the present study was to isolate by liquid–liquid chromatography high-purity rare coumarins from the fruits of Seseli devenyense Simonk. and evaluate their anxiolytic effect (defined as reversed thimotaxis) using a 5-days post-fertilization (dpf) Danio rerio larvae model. Liquid–liquid chromatography enabled the isolation of one simple hydroxycoumarin (devenyol) and four pyranocoumarins (cis-khellactone, d-laserpitin, isolaserpitin and octanoyllomatin). The anxiolytic effect was defined as a decrease in the time spent in the boundaries of the living space (also described as reversed thigmotaxis). Our results show that all isolated courmarins exerted a significant influence on the anxiety behavior (anxiolytic activity) in the zebrafish larvae model. According to our knowledge, this is the first report of anxiolytic activity of pyranocoumarins and devenyol.     

Dielectric,ferroelectric, and energy storage properties in dysprosium doped sodium bismuth titanate ceramics

In this work, Na_0.5(Bi_1-xDy_x)_0.5TiO₃ (0?≤?x?≤?15%) ceramics were prepared via solid state reaction method and were characterized. A stable and pure perovskite phase was revealed by X-ray diffraction analysis for all compositions and a symmetry change from rhombohedral to orthorhombic phase was detected beyond 10% of Dy substitution. The incorporation of Dy³⁺ into Sodium Bismuth Titanate (Na_0.5Bi_0.5TiO₃) matrix allows a substantial decrease of the coercive field, an increase in the resistivity, and leads to a high stability of the dielectric permittivity (??/?_(150?°C) ≤?±?15%) over a wide temperature range. Furthermore, this system was found to exhibit improved energy storage properties at high temperatures with a maximum energy density of 1.2?J/cm³ obtained for 2%Dy composition at 200?°C. The obtained results are very promising for energy storage capacitors operating at high temperatures.     

Analysis of bacterial diversity in river biofilms using 16S rDNA PCR-DGGE: methodological settings and fingerprints interpretation

Reliability of bacterial diversity assessment using polymerase chain reaction (PCR) denaturing gradient gel electrophoresis (DGGE) analysis of 16S rDNA fragments was evaluated for a particular complex microbial assemblage: river epilithic biofilm. By comparing 3 routine protocols on replicates of one river biofilm sample, we found that common DNA extraction procedures gave comparable diversity (from 28.0 to 30.7 bands detected) and community composition (> 75% of homology) despite differences in the total amount of extracted DNA (from 0.9 to 4.2 microg). Therefore methodological improvements only concerned electrophoretic separation of DNA fragments (range of denaturing gradient from 35% to 70% and migration time=18h) and standardisation of DNA amounts used (PCR-template=50 ng, gel loading=700 ng). Using such a standardised methodology we found a good reproducibility of all steps of the procedure. When an Escherichia coli strain was introduced as a contaminant in a biofilm sample, we were able to recover ribotypes from the strain. As concerns fields sampling, a satisfactory repeatability of banding patterns from neighbouring pebbles (sampling point) allowed discriminating between the biofilm intrasite variability (various points from a cross-profile). These trials confirmed that PCR-DGGE is suitable to assess a reliable genetic fingerprint of epilithic biofilms in the river. Phylogenetic analysis of 40 partial sequences of 16S rDNA from DGGE gels of two sets of river biofilms samples proved evidences for the retrieval of DNA fragments related to phototroph Eukarya. However, in both cases plastidial 16S rDNA represented less than 25% of the analysed operational taxonomic units. Taking into account that Cyanobacteria, as members of the Bacteria, were also detected, sequence analysis of relevant bands from the pattern is required to target "bacteria", i.e. the functional group of prokaryotic microorganisms to which one commonly refers as a key component in sustaining the nutrient turnover.     

Impact of Functionalized Polystyrenes as the Electron Injection Layer on Gold and Aluminum Surfaces: A Combined Theoretical and Experimental Study

At metal/organic interfaces, the insertion of an organic monolayer can significantly modify the surface properties of the substrate, especially in terms of charge injection across the interface. Herein, we study the formation of an insulating monolayer of morpholine or amine-functionalized polystyrene on Al(111) and Au(111) surfaces and its impact on surface work-function and charge injection. First-principles calculations based on Density Functional Theory have been carried out and point to a significant decrease in the work-function of modified metal surfaces; this is in very good agreement with ultraviolet photoemission spectroscopy measurements performed on the Au(111) surface. In addition, a bilayer cathode, consisting of a thin film of high-work-function metal, such as Al and Au, and a layer of amine-functionalized polystyrene, was also fabricated and tested in organic light-emitting diodes. Such bilayer structures exhibit substantially enhanced efficiency when compared with controls without the functionalized polymers. Our combined theoretical and experimental investigation gives insight into how a thin layer of a commodity polymer can be used to transform rather high-work-function metals into high-performance cathodes to provide efficient electron injection.     

Solid-Phase Synthesis of Substrate-Based Dipeptides and Heterocyclic Pseudo-dipeptides as Potential NO Synthase Inhibitors

More than 160 arginine analogues modified on the C-terminus via either an amide bond or a heterocyclic moiety (1,2,4-oxadiazole, 1,3,4-oxadiazole and 1,2,4-triazole) were prepared as potential inhibitors of NO synthases (NOS). A methodology involving formation of a thiocitrulline intermediate linked through its side-chain on a solid support followed by modification of its carboxylate group was developed. Finally, the side-chain thiourea group was either let unchanged, S-alkylated (Me, Et) or guanidinylated (Me, Et) to yield respectively after TFA treatment the corresponding thiocitrulline, S-Me/Et-isothiocitrulline and N-Me/Et-arginine substrate analogues. They all were tested against three recombinant NOS isoforms. Several compounds containing a S-Et- or a S-Me-Itc moiety and mainly belonging to both the dipeptide-like and 1,2,4-oxadiazole series were shown to inhibit nNOS and iNOS with IC₅₀ in the 1–50 μM range. Spectral studies confirmed that these new compounds interacted at the heme active site. The more active compounds were found to inhibit intra-cellular iNOS expressed in RAW264.7 and INS-1 cells with similar efficiency than the reference compounds L-NIL and SEIT.     

Editorial: Biodegradable Materials

This Special Issue “Biodegradable Materials” features research and review papers concerning recent advances on the development, synthesis, testing and characterisation of biomaterials. These biomaterials, derived from natural and renewable sources, offer a potential alternative to existing non-biodegradable materials with application to the food and biomedical industries amongst many others. In this Special Issue, the work is expanded to include the combined use of fillers that can enhance the properties of biomaterials prepared as films. The future application of these biomaterials could have an impact not only at the economic level, but also for the improvement of the environment.     

Cytocompatibility of titanium metal injection molding with various anodic oxidation post-treatments

Metal injection molding (MIM) is a near net shape manufacturing method that allows for the production of components of small to moderate size and complex shape. MIM is a cost-effective and flexible manufacturing technique that provides a large innovative potential over existing methods for the industry of implantable devices. Commercially pure titanium (CP-Ti) samples were machined to the same shape as a composite feedstock with titanium and polyoxymethylene, and these metals were injected, debinded and sintered to assess comparative biological properties. Moreover, we treated MIM-Ti parts with BIOCOAT®, BIODIZE® and BIOCER®, three different anodic oxidation techniques that treat titanium using acid, alkaline and anion enriched electrolytes, respectively. Cytocompatibility as well as morphological and chemical features of surfaces was comparatively assessed on each sample, and the results revealed that MIM-Ti compared to CP-Ti demonstrated a specific surface topography with a higher roughness. MIM-Ti and BIOCER® samples significantly enhanced cell proliferation, cell adhesion and cell differentiation compared to CP-Ti. Interestingly, in the anodization post-treatment established in this study, we demonstrated the ability to improve osseointegration through anionic modification treatment. The excellent biological response we observed with MIM parts using the injection molding process represents a promising manufacturing method for the future implantable devices in direct contact with bones.     

Thulium and Ytterbium-Doped Titanium Oxide Thin Films Deposited by Ultrasonic Spray Pyrolysis

Thin films of thulium and ytterbium-doped titanium oxide were grown by metal-organic spray pyrolysis deposition from titanium(IV)oxide bis(acetylacetonate), thulium(III) tris(2,2,6,6-tetramethyl-3,5-heptanedionate) and ytterbium(III) tris(acetylacetonate). Deposition temperatures have been investigated from 300 to 600 °C. Films have been studied regarding their crystallinity and doping quality. Structural and composition characterisations of TiO₂:Tm,Yb were performed by electron microprobe, x-ray diffraction, and Fourier transform infrared spectroscopy. The deposition rate can reach 0.8 μm/h. The anatase phase of TiO₂ was obtained after synthesis at 400 °C or higher. Organic contamination at low deposition temperature is eliminated by annealing treatments.     

3种锆合金的高温氧化行为

对Zr-A和Zr-B锆合金在700-1200℃的O_2中进行了等温氧化实验,观察了合金的氧化动力学行为和基体微观结构演变,并与低Sn的Zr-4合金作了对比.结果表明,700—1200℃氧化时,3种锆合金的动力学曲线基本服从抛物线规律,Zr-B合金在700℃氧化1200 s后速率出现转折;800℃时Zr-A和Zr-B合金的氧化速率出现转折;1000℃时3种合金动力学曲线由抛物线变为近似直线;1100℃以上氧化时,动力学曲线呈抛物线规律,未出现转折.在1100℃以上氧化时,合金成分对3种合金的高温氧化性能影响甚微.依据氧化增重数据得到了3种合金在700—1200℃氧化反应的抛物线速率常数K_p的表达式.     

Assessing the Antimicrobial Activity of Polyisoprene Based Surfaces

There has been an intense research effort in the last decades in the field of biofouling prevention as it concerns many aspects of everyday life and causes problems to devices, the environment, and human health. Many different antifouling and antimicrobial materials have been developed to struggle against bacteria and other micro- and macro-organism attachment to different surfaces. However the “miracle solution” has still to be found. The research presented here concerns the synthesis of bio-based polymeric materials and the biological tests that showed their antifouling and, at the same time, antibacterial activity. The raw material used for the coating synthesis was natural rubber. The polyisoprene chains were fragmented to obtain oligomers, which had reactive chemical groups at their chain ends, therefore they could be modified to insert polymerizable and biocidal groups. Films were obtained by radical photopolymerization of the natural rubber derived oligomers and their structure was altered, in order to understand the mechanism of attachment inhibition and to increase the efficiency of the anti-biofouling action. The adhesion of three species of pathogenic bacteria and six strains of marine bacteria was studied. The coatings were able to inhibit bacterial attachment by contact, as it was verified that no detectable leaching of toxic molecules occurred.