Synthesis and analytical characterisation of copper-based nanocoatings for bioactive stone artworks treatment

Biological agents play an important role in the deterioration of cultural heritage causing aesthetic, biogeophysical and biogeochemical damages. Conservation is based on the use of preventive and remedial methods. The former aims at inhibiting biological attack, and the latter aims at eradicating the biological agents responsible for biodeterioration. Here, we propose the preparation and the analytical characterisation of copper-based nanocoating, capable of acting both as a remedy and to prevent microbial proliferation. Core–shell CuNPs are mixed with a silicon-based product, commonly used as a water-repellent/consolidant, to obtain a combined bioactive system to be applied on stone substrates. The resulting coatings exert a marked biological activity over a long period of time due to the continuous and controlled release of copper ions acting as biocides. To the best of our knowledge, this is the first time that a multifunctional material is proposed, combining the antimicrobial properties of nanostructured coatings with those of the formulations applied to the restoration of stone artworks. A complete characterisation based on a multi-technique analytical approach is presented.     

Small molecule correctors of F508del-CFTR discovered by structure-based virtual screening

Folding correctors of F508del-CFTR were discovered by in silico structure-based screening utilizing homology models of CFTR. The intracellular segment of CFTR was modeled and three cavities were identified at inter-domain interfaces: (1) Interface between the two Nucleotide Binding Domains (NBDs); (2) Interface between NBD1 and Intracellular Loop (ICL) 4, in the region of the F508 deletion; (3) multi-domain interface between NBD1:2:ICL1:2:4. We hypothesized that compounds binding at these interfaces may improve the stability of the protein, potentially affecting the folding yield or surface stability. In silico structure-based screening was performed at the putative binding-sites and a total of 496 candidate compounds from all three sites were tested in functional assays. A total of 15 compounds, representing diverse chemotypes, were identified as F508del folding correctors. This corresponds to a 3% hit rate, ~tenfold higher than hit rates obtained in corresponding high-throughput screening campaigns. The same binding sites also yielded potentiators and, most notably, compounds with a dual corrector-potentiator activity (dual-acting). Compounds harboring both activity types may prove to be better leads for the development of CF therapeutics than either pure correctors or pure potentiators. To the best of our knowledge this is the first report of structure-based discovery of CFTR modulators.     

Fulvic acid enrichment in the microlayer of the Gerlache Inlet Sea (Antarctica): preliminary results

The aim of this work was to study the presence of fulvic acids in Antarctic waters, as they appear to be principal film-forming components in the surface microlayer. We obtained a series of samples during two Antarctic Italian Expeditions in 1998/99 and 2000/01 and studied the distribution and the structural differences between fulvic acids extracted from both microlayer and subsurface waters.

Fulvic acids are concentrated in the microlayer and the enrichment factor between microlayer and subsurface water differs between samples. The enrichment factor values for fulvic acids lie between those found for dissolved organic carbon (DOC) and particulate organic carbon (POC) in the literature. Fulvic acids extracted from the microlayer were found to be different in structure from those present in the subsurface layer and enriched in sulphur content. We hypothesised that sulphur-containing compounds are slightly bound and/or occluded in fulvic acid structures. The sulphur-containing compounds analysed in the microlayer could be dimethylsulfide (DMS) and/or its products stemming from photochemical and biological oxidation reactions.     

Hamilton–Jacobi equations constrained on networks

We consider continuous-state and continuous-time control problems where the admissible trajectories of the system are constrained to remain on a network. In our setting, the value function is continuous. We define a notion of constrained viscosity solution of Hamilton–Jacobi equations on the network and we study related comparison principles. Under suitable assumptions, we prove in particular that the value function is the unique constrained viscosity solution of the Hamilton–Jacobi equation on the network.     

Phase transition in saturated porous media: Pore-fluid segregation in consolidation

Consider the consolidation process typical of soils; this phenomenon is expected not to exhibit a unique state of equilibrium, depending on external loading and constitutive parameters. Beyond the standard solution also, pore-fluid segregation can arise. Pore-fluid segregation has been recognized as a phenomenon typical of the short time behavior of a saturated porous slab or a saturated porous sphere, during consolidation. In both circumstances, the Biot three-dimensional model provides time increasing values of the water pressure (and fluid mass density) at the center of the slab (or of the sphere), at early times, if the Lamé constant μ of the skeleton is different from zero. This localized pore-fluid segregation is known in the literature as the Mandel-Cryer effect. In this paper, a nonlinear poromechanical model is formulated. The model is able to describe the occurrence of two states of equilibrium and the switching from one to the other by considering a kind of phase transition. Extending the classical Biot theory, a more than quadratic strain energy potential is postulated, depending on the strain of the porous material and the variation of the fluid mass density (measured with respect to the skeleton reference volume). When the consolidating pressure is strong enough, the existence of two distinct minima is proven.     

Controlled density patterning of tolylterpyridine-tagged oligonucleotides

An efficient surface anchoring strategy of tolylterpyridine-tagged DNA single strands (ssDNA-ttpy) synthesized on gold electrodes is reported. The method is based on exchange reactions between Fe(II)bis-terpyridine complexed SAMs and ssDNA-ttpy, and allows efficient hybrydization of the cDNA strands. Moreover, by using low-current focused ion beam lithography, micropatterned arrays are obtained, homogeneously covered with ssDNA-ttpy. The surface adsorption kinetics of ssDNA-ttpy, as well as its hybridization efficiency, was monitored by in situ quartz crystal microbalance with dissipation monitoring (QCM-D) technique. The effective confinement of the ssDNA-ttpy at the micrometer level has been monitored by time of flight secondary ion mass spectrometry (ToF-SIMS) and ellipsometric surface imaging experiments, providing laterally resolved chemical and topographic mapping.     

A new approach to 4,6-disubstituted-3,4-dihydropyran-2-ones by Domino Michael addition-cyclization reaction under PTC conditions

Domino Michael addition-cyclization reactions of α,β-unsaturated carbonyl compounds with activated 1,3-dithiane-2-carbothioate esters under solid-liquid phase transfer catalysis conditions provide 4,6-disubstituted-3,4-dihydropyran-2-one-3,3-dithioacetals in good chemical yield. Desulfurization proceeds chemoselectively under mild conditions affording 3,4-dihydropyran-2-ones in high yields.     

Morphology and Fine Structure of Membranes upon Osmotic Upshifts

Lipid bilayers are impermeable to most polar molecules. Osmoregulated transporters are responsible for controlling the intracellular osmolarity and protecting the cell against changes in osmolality in the environment. The mechanisms by which membranes regulate the activity of these transporters are still largely unknown. In this paper we investigate the response to hyperosmotic stress in artificial, chemically well-defined membrane models called Giant Unilamellar Vesicles (GUV). The lipid compositions analysed are relevant for the activity of an ABC-transport system that is controlled by the physicochemical properties of the membrane bilayer. Morphology changes are monitored by phase-contrast optical microscopy, and fine structural details related to domain formation are investigated by fluorescence confocal optical microscopy.     

Synthesis and Properties of Aromatic Poly(Ether Sulfone)s and Poly(Etherketone)s Containing Naphthalene or Quinoline Units,and Methyl-Substituted Biphenyl-4,4′-Diols

Abstract

A series of poly(ether sulfone)s and poly(ether ketone)s were synthesized from combinations of 1,5- and 2,6-bis(4-fluorosulfonyl)naphthalene, 2,6-bis(4-fluorobenzoyl)naphthalene, and 2,6-bis(4-fluorobenzoyl)quinoline with 3,3′,5,5′-tetramethylbiphenyl-4,4′-diol and 2,2′,3,3′,5,5′-hexamethylbiphenyl-4,4′-diol. The polycondensations proceeded quantitatively in diphenylsulfone in the presence of anhydrous potassium carbonate to afford polymers with inherent viscosities between 0.40 and 1.28 dL/g measured in N-methyl-2-pyrrolidone or concentrated sulfuric acid. The tetramethyl- and hexamethyl-substituted aromatic polyethers exhibited good thermal stability, did not decompose below 330°C in both air and nitrogen atmospheres, and had higher glass transition temperatures than the corresponding unsubstituted polymers. The methylsubstituted poly(ether sulfone)s and poly(ether ketone)s showed good solubility in such common organic solvents as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, tetrahydrofuran, chloroform, and 1,4-dioxane.     

Rough surfaces for orientation control in reverse mode polymer dispersed liquid crystal films

Reverse mode operation shutters have been achieved with polymer dispersed liquid crystals by means of polymerization-induced phase separation of nematic mixtures consisting of a low molecular mass liquid crystal and a liquid crystalline monomer. Fluid mixtures were homeotropically aligned by rough surfaces and transparent films were obtained after polymerization. Transmittance in the OFF state can be larger than 80% and decreases to less than 1% when an electric field of about 2 V μm^-1 at 1 kHz is applied (ON state). Both rise and decay times can be lower than 10 ms and the drop in the OFF state normal transmittance is drastically reduced with respect to conventional polymer dispersed liquid crystals since samples exhibit a reverse morphology. The role played by surface roughness is also discussed.