Autochthonous white grape pomaces as bioactive source for functional jams

Seeds and skins from grape pomaces of Pecorello and Mantonico cv underwent extraction (ultrasound–assisted or maceration), in order to obtain added-value ingredients for the production of a functional pear jam. The antioxidant features of the extracts were tested by in vitro colorimetric assays. Among seeds, Mantonico by maceration (MSC) showed the best results, as well as Mantonico by ultrasound-assisted extraction (MBs) among skin extracts. The selected extracts were fully characterised by NMR and MS techniques, confirming the presence of many polyphenols, flavonoids and tannins among others. Pectin was then derivatised by the grafting procedure with the active molecules of MBs and MSC. The latter produced the best antioxidant polymer also without toxicity evaluated using Caco-2 cells and was used for the jam preparation. The functional pear jam showed improved antioxidant performances in comparison with its non-functional counterparts as well as its maintenance over time (15 days).     

DNA-directed immobilization of horseradish peroxidase onto porous SiO2optical transducers

ABSTRACT: Multifunctional porous Si nanostructure is designed to optically monitor enzymatic activity of Horseradish Peroxidase. First, an oxidized PSi optical nanostructure, a Fabry-Perot thin film, is synthesized and is used as the optical transducer element. Immobilization of the enzyme onto the nanostructure is performed through DNA-Directed Immobilization. Preliminary studies demonstrate high enzymatic activity levels of the immobilized Horseradish Peroxidase, while maintaining its specificity. The catalytic activity of the enzymes immobilized within the porous nanostructure is monitored in real time by reflective interferometric Fourier transform spectroscopy. We show that we can easily regenerate the surface for consecutive biosensing analysis by mild de-hybridization conditions.     

Synthesis and characterization of polysiloxanes with pendant bicyclic fragments

Transparent poly vinyl alcohol (PVA) based coatings with antimicrobial activity against a wide range of microorganisms have been prepared. The films have been prepared by spincoating a mixture of PVA, ammonium dichromate and metal (zinc or silver) precursor from water solutions, and then rendered insoluble by crosslinking under UV illumination. Antimicrobial activity has been tested against different bacteria and fungi, such as Bacillus atrophaeus, Bacillus megaterium, Staphylococcus aureus, Enterococcus faecium, Pseudomonas aeruginosa, Salmonella enterica, Escherichia coli, Neurospora crassa, and Saccharomyces cerevisiae. It was found that combining the zinc and silver precursors resulted in films which had excellent antimicrobial activity and at the same time exhibited superior environmental stability compared to films containing prepared with single metal precursor. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Point Charges and Polygonal Linkages

We investigate the critical points of Coulomb potential of point charges placed at the vertices of a planar polygonal linkage. It is shown that, for a collection of positive charges on a pentagonal linkage, there is a unique critical point in the set of convex configurations which is the point of absolute minimum. This enables us to prove that two controlling charges are sufficient to navigate between any two convex configurations of a pentagonal linkage.     

Characterization of a High Capacity Multi-User Optical Access Network Using 1 Gb/s 16 QAM Subcarrier Multiplexing

Error free operation assuming common FEC techniques is experimentally demonstrated for a multi-user optical access network based on 40 channel DWDM-PON infrastructure and Gigabit Ethernet 16 QAM subcarrier multiplexing transmission. Such a system would support 400 users with symmetrical 1.25 Gb/s connections and media independent final connectivity. To replicate actual working conditions, the experimental setup relied only on commercially available components and was tested with realistic distance reach and high sub-channel load.     

Corrosion Mechanisms of Steel and Cast Iron by Molten Aluminum

The corrosion mechanisms by liquid aluminum of three industrial materials have been studied: unalloyed steel (UAS), and ferritic and modified pearlitic cast irons (FCI and PCI, respectively). The behavior of these materials when in contact with liquid aluminum is different. Aluminum diffuses deep into the UAS and forms intermetallic compounds with iron at the surface and in the steel matrix. At the surface, only Fe₂Al₅ and FeAl₃ are found. In the matrix, FeAl₂ also is formed in agreement with the equilibrium Fe-Al diagram. From the matrix to FeAl₂, the Al content in the ferrite increases progressively until Al saturation is reached. At this step, black elongated precipitates (Al₄C₃ and/or graphite) appear. Graphite lamellas present in both FCI and PCI constitute an efficient barrier to the Al diffusion. The high silicon content of the FCI leads to the formation of a phase free from Al and saturated in Si. For the PCI, a thin layer rich in Al and Si, which is formed between the matrix and Fe₂Al₅, limits the diffusion of atoms. The effects of Cr and P added in the PCI also are discussed.     

Modeling and biological investigations of an unusual behavior of novel synthesized acridine-based polyamine ligands in the binding of double helix and G-quadruplex DNA

Three novel 2,7-substituted acridine derivatives were designed and synthesized to investigate the effect of this functionalization on their interaction with double-stranded and G-quadruplex DNA. Detailed investigations of their ability to bind both forms of DNA were carried out by using spectrophotometric, electrophoretic, and computational approaches. The ligands in this study are characterized by an open-chain (L1) or a macrocyclic (L2, L3) framework. The aliphatic amine groups in the macrocycles are joined by ethylene (L2) or propylene chains (L3). L1 behaved similarly to the lead compound m-AMSA, efficiently intercalating into dsDNA, but stabilizing G-quadruplex structures poorly, probably due to the modest stabilization effect exerted by its protonated polyamine chains. L2 and L3, containing small polyamine macrocyclic frameworks, are known to adopt a rather bent and rigid conformation; thus they are generally expected to be sterically impeded from recognizing dsDNA according to an intercalative binding mode. This was confirmed to be true for L3. Nevertheless, we show that L2 can give rise to efficient π-π and H-bonding interactions with dsDNA. Additionally, stacking interactions allowed L2 to stabilize the G-quadruplex structure: using the human telomeric sequence, we observed the preferential induction of tetrameric G-quadruplex forms. Thus, the presence of short ethylene spacers seems to be essential for obtaining a correct match between the binding sites of L2 and the nucleobases on both DNA forms investigated. Furthermore, current modeling methodologies, including docking and MD simulations and free energy calculations, provide structural evidence of an interaction mode for L2 that is different from that of L3; this could explain the unusual stabilizing ability of the ligands (L2>L3>L1) toward G-quadruplex that was observed in this study.     

Design of high fastness acid dyes for silk: a chemometric approach

A chemometric strategy tor the design of acid dyes for silk is reported. A small set of representative dyes was selected by the technique of fractional factorial design, using the principal properties of the substituents as design variables. The selected dyes were synthesised and fastness properties on silk were measured. Wash fastness and light fastness values were related to the chemical structure by the partial least squares (PLS) method. The models were used to predict the fastness of new dyes of the same class and to optimise the structure.     

Synthesis of thermoreactive polysiloxanes with cyclic fragments in the side chain

The synthesis of polysiloxanes with pendant unsaturated cyclic fragments have been successfully performed by hydrosilylation reactions of polymethylhydrosiloxane with 4‐vinyl‐1‐cyclohexene in the presence of platinum hydrochloric acid (0.1 M solution in THF), Karstedt's catalyst (Pt₂[(VinSiMe₂)₂O]₃) and platinum on the charcoal (5%). Reactions were carried out at various temperatures with different ratios of initial compounds. It was shown, that not all active ≡Si? H groups take part in the hydrosilylation reaction. Some kinetic parameters of reactions were studied. The synthesized oligomers were characterized by FTIR, ¹H, ¹³C, H,H‐COSY, and C,H‐correlation NMR spectroscopy. Calculations using the quantum‐chemical semi empirical AM1 method for modeling reactions between methyldimethoxysilane [Me(MeO)₂SiH] and 4‐vinyl‐1‐cyclohexene were performed to evaluate possible reaction paths. Synthesized oligomers were characterized by gel‐permeation chromatography, differential scanning calorimetric, thermogravimetric, and wide‐angle X‐ray analyses. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009