Thiazolium‐Based Catalysts for the Etherification of Benzylic Alcohols under Solvent‐Free Conditions

Thiazolium and imidazolium hybrid materials were prepared by radical reactions between a mercaptopropyl‐modified SBA‐15 mesoporous silica and bis‐vinylthiazolium or bis‐vinylimidazolium dibromide salts. These hybrid materials were characterized by several techniques and were employed in the etherification reaction of 1‐phenylethanol. Solvent‐free conditions at 160 °C under different gas phases (oxygen, air, nitrogen and argon) were used. The thiazolium‐based material displayed excellent performances. Further studies were carried out using unsupported thiazolium salts, with or without a methyl group at the C‐2 position of the thiazolium moiety. These studies allowed us to propose a reaction mechanism. The supported thiazolium‐based material was successfully used in the etherification reaction of two other benzylic alcohols and also in seven consecutive cycles. This work represents the first use of thiazolium‐based compounds as catalysts for the etherification reaction of alcohols.

     

Influence of the heterogeneity of grape phenolic maturity on wine composition and quality

Nowadays, consumers demand red wines with deep colour, soft tannins and fruit scents, but these wines can only be obtained from grapes with complete phenolic maturity. Diverse methods have been proposed for measuring phenolic maturity. However, all these methods only provide the average value and do not consider any possible heterogeneity. Throughout ripening, grapes were separated according to their density, which revealed the existence of a large heterogeneity. Grapes at harvest were also separated by density in three groups. The higher the density of the grapes the higher ethanol content, pH, colour intensity, total phenolic index and anthocyanin and proanthocyanidin concentrations, and the lower the titratable acidity and bitterness of the wines. When the grapes were denser the wines were also better balanced in flavour and mouthfeel sensation. These results suggest that grape heterogeneity may influence the final wine composition and quality and therefore it should be considered at harvest.     

Microwave-assisted functionalization of single-wall carbon nanotubes through diazonium

Single-wall carbon nanotubes (SWNTs) have been functionalized by a diazonium method through both a classical thermal reaction and a microwave-assisted reaction. The functionalized SWNTs have been characterized by nIR-Vis-UV absorption spectroscopy, Raman spectroscopy, and thermal gravimetric analysis. The results show that SWNTs are covalently functionalized through both reactions and that the microwave-assisted reaction is more rapid. Moreover, optimal choice of the reaction time can prevent the microwave irradiation from the adverse effect of subsequently removing the functional groups on the SWNT surface.     

Paradigmatic De Novo GRIN1 Variants Recapitulate Pathophysiological Mechanisms Underlying GRIN1-Related Disorder Clinical Spectrum

Background: GRIN-related disorders (GRD), the so-called grinpathies, is a group of rare encephalopathies caused by mutations affecting GRIN genes (mostly GRIN1, GRIN2A and GRIN2B genes), which encode for the GluN subunit of the N-methyl D-aspartate (NMDA) type ionotropic glutamate receptors. A growing number of functional studies indicate that GRIN-encoded GluN1 subunit disturbances can be dichotomically classified into gain- and loss-of-function, although intermediate complex scenarios are often present. Methods: In this study, we aimed to delineate the structural and functional alterations of GRIN1 disease-associated variants, and their correlations with clinical symptoms in a Spanish cohort of 15 paediatric encephalopathy patients harbouring these variants. Results: Patients harbouring GRIN1 disease-associated variants have been clinically deeply-phenotyped. Further, using computational and in vitro approaches, we identified different critical checkpoints affecting GluN1 biogenesis (protein stability, subunit assembly and surface trafficking) and/or NMDAR biophysical properties, and their association with GRD clinical symptoms. Conclusions: Our findings show a strong correlation between GRIN1 variants-associated structural and functional outcomes. This structural-functional stratification provides relevant insights of genotype-phenotype association, contributing to future precision medicine of GRIN1-related encephalopathies.     

Multiarm star poly(glycidol)-block-poly(styrene) as modifier of anionically cured diglycidylether of bisphenol A thermosetting coatings

Well-defined multiarm star copolymer poly(glycidol)-b-poly(styrene) (PGOH-b-PS) with an average number of PS arms per molecule of 85 has been prepared. The core first approach has been selected as the methodology using atom transfer radical polymerization (ATRP) of styrene to grow the arms from an activated hyperbranched poly(glycidol) as core. This activated hyperbranched macroinitiator was prepared by esterification of hyperbranched poly(glycidol) (PGOH) with 2-bromoisobutyryl bromide.PGOH-b-PS was used to modify diglycidylether of bisphenol A coatings cured by anionic ring-opening mechanism using 1-methyl imidazole as the initiator. The kinetics of the curing process, studied by dynamic scanning calorimetry (DSC), was not much affected when PGOH-b-PS was added to the formulation. By rheometry the effect of this new polymer topology on the complex viscosity (η^*) of the reactive mixture was analyzed. The phase-separation of the modified coatings was proved by dynamic thermomechanical analysis (DMTA) and electronic microscopy (SEM and TEM) showing nano- or microphase separation as a function of the modifier content. The addition of this star polymer led to increase in the rigidity in terms of Young's modulus and in the microhardness in comparison to neat DGEBA.     

Internal geometry variability of two woven composites and related variability of the stiffness

In this work, the internal geometry measurements of two woven composites are analyzed: cross section of the yarns, fiber volume fraction, crimp, misalignment of the samples, thickness of the plates, nesting value, and so forth. The chosen textile composites are produced using the same resin reinforcement and same architecture, but have different yarn size (3K and 12K). The dispersion of measured geometrical parameters is introduced in a numerical multiscale modeling approach to evaluate the macroscopic stiffness values. A sensitivity analysis is performed for each geometrical parameter and laminate stiffnesses are derived. These are linked to the experimentally obtained elastic properties by tensile tests. Finally, the unit cell size scale effect for measured geometry variability and experimentally obtained elastic properties are evaluated. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Antimicrobial action of synthetic peptides towards wine spoilage yeasts

The antimicrobial action of selected short synthetic peptides against wine spoilage yeasts such as Cryptococcus albidus, Dekkera bruxellensis, Pichia membranifaciens, Saccharomyces cerevisiae, Zygosaccharomyces bailii and Zygosaccharomyces bisporus has been examined. Peptides analyzed include nine sequence-related antifungal hexapeptides (PAFs) previously developed by a combinatorial approach, and two representative lactoferricin B (LfcinB)-derived peptides. Different peptides had distinct activity profiles. In vitro assays identified the peptides PAF26, PAF36, and LfcinB(17-31), as having growth inhibitory properties towards several of the yeasts at low micromolar concentrations. Z. bailii and Z. bisporus were the most sensitive yeasts. In addition to their fungistatic activity, the three peptides showed fungicidal properties towards Z. bailii, Z. bisporus, and S. cerevisiae in laboratory growth medium. Remarkably, only LfcinB(17-31) against Z. bisporus had inhibitory and fungicidal properties in wine at the concentrations assayed, showing that the antimicrobial action of each peptide is dependent on both the food matrix and the target micro-organism. Lack of fungicidal activity of peptides against Z. bailii in wine is related to the presence of salt ions other than divalent cations. On the contrary, fungicidal activity of LfcinB(17-31) towards Z. bisporus was not significantly affected by wine salts. Our data identify a bioactive peptide from natural origin with potential use against the food spoilage yeast Z. bisporus, and indicate that the application of antimicrobial peptides in wine preservation deserves further investigation.