Modeling of the glycine tripeptide cyclization in the Ser65Gly/Tyr66Gly mutant of green fluorescent protein

1. Download high-res image (103KB)
2. Download full-size image

     

Organic contamination in clams,Venerupis aurea laeta and Cerastoderma edule glaucum,from Sicily (Italy)

Two species of edible clams Venerupis aurea laeta and Cerastoderma edule glaucum from Ganzirri Lake (Sicily, Italy) were investigated to determine OCP and PCB residues by GC-MS. Thirty-five samples were examined for two years in order to perform: a) their actual contamination; b) the daily dietary exposure of seafood consumers to the pollutants in question. In all the clams analysed in this study, PCB and OCP (4,4′-DDE) residues are always below the limits fixed by law. It seems that there is some seasonality of concentrations observed. In fact the more high concentrations of residues are detected in the hot months, for both species and years. Given the consumption of clams and the values obtained in this study for the two species analysed, it is possible estimate that the average daily dietary intake of NDL-PCB and of 4,4′-DDE for adults is really low.     

Micro-Mesoporous Carbons from Cyclodextrin Nanosponges Enabling High-Capacity Silicon Anodes and Sulfur Cathodes for Lithiated Si-S Batteries

Manufactured globally on industrial scale, cyclodextrins (CD) are cyclic oligosaccharides produced by enzymatic conversion of starch. Their typical structure of truncated cone can host a wide variety of guest molecules to create inclusion complexes; indeed, we daily use CD as unseen components of food, cosmetics, textiles and pharmaceutical excipients. The synthesis of active material composites from CD resources can enable or enlarge the effective utilization of these products in the battery industry with some economical as well as environmental benefits. New and simple strategies are here presented for the synthesis of nanostructured silicon and sulfur composite materials with carbonized hyper cross-linked CD (nanosponges) that show satisfactory performance as high-capacity electrodes. For the sulfur cathode, the mesoporous carbon host limits polysulfide dissolution and shuttle effects and guarantees stable cycling performance. The embedding of silicon nanoparticles into the carbonized nanosponge allows to achieve high capacity and excellent cycling performance. Moreover, due to the high surface area of the silicon composite, the characteristics at the electrode/electrolyte interface dominate the overall electrochemical reversibility, opening a detailed analysis on the behavior of the material in different electrolytes. We show that the use of commercial LP30 electrolyte causes a larger capacity fade, and this is associated with different solid electrolyte interface layer formation and it is also demonstrated that fluoroethylene carbonate addition can significantly increase the capacity retention and the overall performance of our nanostructured Si/C composite in both ether-based and LP30 electrolytes. As a result, an integration of the Si/C and S/C composites is proposed to achieve a complete lithiated Si−S cell.     

Electrodes/Electrolyte Interfaces in the Presence of a Surface‐Modified Photopolymer Electrolyte: Application in Dye‐Sensitized Solar Cells

Since hundreds of studies on photoanodes and cathodes show that the electrode/electrolyte interfaces represent a key aspect at the base of dye‐sensitized solar cell (DSSC) performances, it is reported here that these interfaces can be managed by a smart design of the spatial composition of quasi‐solid electrolytes. By means of a cheap, rapid, and green process of photoinduced polymerization, composition‐tailored polymer electrolyte membranes (PEMs) with siloxane‐enriched surfaces are prepared, and their properties are thoroughly described. When assembled in DSSCs, the interfacial action promoted by the composition‐tailored PEMs enhances the photocurrent and fill factor values, thus increasing the global photovoltaic conversion efficiency with respect to the non‐modified PEMs. Moreover, the presence of the siloxane‐chain‐enriched surface increases the hydrophobicity and reduces the water vapor permeation into the device, thus enhancing the cell′s durability.     

Optical storage of hidden images in ultraviolet-cured polymer dispersed liquid crystals

Among the different methods used to prepare polymer dispersed liquid crystals (PDLCs), polymerization induced phase separation can be successfully exploited to obtain optical recording of high resolution holographic gratings and binary images in these materials. In this paper we report a new method that allows hidden images to be obtained in PDLCs that are not detectable by light in the visible range. The possibility of storing invisible images during the curing process will be described and discussed. The binary images obtained can be detected by illuminating them with low power UV radiation, thus opening the way to interesting applications in the field of optical storage of reserved information.     

Effect of solvation water shells on enzyme active sites in zinc-dependent hydrolases

Structural Chemistry - In this work, we focus on some structural aspects of enzyme catalysis by modeling effects of the electrostatic potential created by the solvation water shells on properties...     

Characterization of foxing stains in early twentieth century photographic and paper materials

Abstract

The subject of this present work is a group of nine historical pictures shot in Palermo by the Sicilian photographer E. Interguglielmi in 1912. They are nine matte-collodion prints mounted on the original cardboard supports and all of them show foxing stains affecting the paper surface. In order to characterise the chemical composition of the supports and investigate foxing spots, non-destructive and micro-destructive analysis were carried out. X-rays fluorescence (XRF) analysis was used to characterise the elemental composition of all the mounting boards, allowing a comparison between the foxing spots and non-affected areas. Laser-Induced Breakdown Spectroscopy was used to investigate the presence of lower atomic number elements, not detectable by XRF, while SEM imaging allowed the investigation of surface appearance and nature of original paper samples from the cardboards.     

Application of synchronous fluorescence to parchment characterization

A nondestructive method for quantitative parchment characterization and sensitive indication of its deterioration stage was developed. Synchronous fluorescence (SF) measurements were applied for the first time to parchment samples. The method provides detailed spectral features, which are useful for parchment characterization. The discrimination of parchment samples into groups (modern, historical, and artificially aged) was successfully performed. The SF spectra could be resolved into specific fluorophores, which were related to the parchment condition. The spectral data indicate a continuous change in the collagen-to-gelatin ratio during the aging process. Depth-resolved synchronous fluorescence spectra were also measured. The data indicate that parchments possess a layered structure, and the dominant fluorophore in the upper layer is different from those in the lower layers. Layer-resolved profiling allows for quantifying the contribution of each fluorophore in each given layer. This way, significant differences between modern, artificially aged, and historical samples can be observed.