N,O-Nucleoside Analogues: Metabolic and Apoptotic Activity

Two new families of N,O-nucleoside analogues containing the anthracene moiety introduced through the nitrosocarbonyl ene reaction with allylic alcohols were prepared. The core structure is an isoxazolidine heterocycle that introduces either atom either a phenyl ring or dimethyl moiety at the C3 carbon. Different heterobases were inserted at the position 5 of the heterocyclic ring. One of the synthesized compounds demonstrated a good capacity to induce cell death and an appreciable nuclear fragmentation was evidenced in treated cells.     

Characterisation of ancient Roman wall-painting fragments using non-destructive IBA and MA-XRF techniques

Scientific investigation is very important in studies addressing issues of archaeological and historical objects. Ion beam analysis (IBA) and macro X-ray fluorescence (MA-XRF) spectroscopy are remarkable tools to obtain information about elemental composition and imaging of historical artefacts with a non-invasive character. These investigation techniques were employed in the framework of a project aimed at supporting the characterization of materials and techniques related with the Roman wall painting. The archaeological excavations at Villa della Piscina in Rome have revealed a luxury building with a large pool (about 50 m long) and thermal baths and numerous fragments of plaster, coming from intentional demolitions referable to two distinct architectural contexts of the Villa during the imperial age, have been found. This work deals with studying the interesting wall pictorial apparatus of great cultural value of the heritage inherited from the Roman age in the area of the ancient city of Rome. The colour palette of the pigments investigated, in particular, by MA-XRF and particle-induced X-ray emission (PIXE) and has revealed Fe, Cu, Pb, Si and Hg as main elements. Traces of other constituents uncover the choice of the different colours chosen by the artists who had embellished the rooms of the Villa.     

The use of nonendcapped C18 columns in the cleanup of clenbuterol and a new adrenergic agonist from bovine liver by gas chromatography-tandem mass spectrometry analysis

More specific official methodology is needed to survey the illegal use of clenbuterol in animal production plus the synthesis of new compounds that currently elude routine analytical methods. The identification of a new adrenergic agonist, N1-(2-(4-amino-3,5-dichlorophenyl)-2-hydroxyethyl)-N1-isopropyl-propanamide (known as compound A) in animal feed has prompted studies to verify if the existing cleanup procedures developed for clenbuterol are really effective. This study considers the ion-exchange mechanism on cyanopropyl (CN), sulfonic cation exchange (SCX), mixed phase (MPH) (C8 + SCX), and nonendcapped C18 (C18NE) solid-phase extraction (SPE) columns. Results indicate that compound A (by contrast with clenbuterol) is not efficiently retained on the CN, SCX, and MPH SPE columns (recovery <10%). This finding thus leads to the development of a gas chromatography-tandem mass spectrometry procedure based on C18NE SPE that is able to purify both agonists from bovine livers spiked at 0.5, 1.0, and 2.0 ppb with a mean recovery of 93% for clenbuterol and 92% for compound A.     

Efficient microwave-assisted synthesis of 4-amino-2-benzazepin-3-ones as conformationally restricted dipeptide mimetics

In this paper, we describe the synthesis of conformationally constrained dipeptide mimetic derivatives. Microwave flash heating was used in several synthetic steps providing the opportunity to perform the reactions in dramatically shortened time as well as to increase the obtained yields. The efficiency of the methodology makes it useful in order to prepare other dipeptides containing the 4-amino-tetrahydro-2-benzazepin-3-one motif.     

Phase transitions in the H+-conducting perovskite ceramics by the quasi-elastic neutron and high-pressure Raman scattering

H⁺-containing lanthanide-doped perovskites A(Ba, Sr etc.)B(Zr, Ce, Ti etc.)O₃ are potential ceramic membranes for fuel cell and medium temperature water electrolysis (300–800 °C). The comparison studies of the hydrated and non-hydrated Yb-doped BaZrO₃ and SrZrO₃ were performed by thermal expansion, medium–high temperature neutron and room-temperature high-pressure Raman scattering. Neutron diffraction and elastic/quasi-elastic studies carried out for BaZrO₃ ceramic show the presence of the protons, their successive diffusion above ∼600 °C, and then their departure above 750 °C (under vacuum). Phase transitions and their modification by proton insertion are discussed. A high-pressure Raman study of SrZrO₃ performed at room temperature in the diamond anvil cell reveals the presence of two pressure-induced phase transitions at about 5 and 22 GPa and confirms that proton insertion modifies the phase transition sequences. Paper presented at the 11th EuroConference on the Science and Technology of Ionics, Batz-sur-Mer, Sept. 9–15, 2007.     

1,3-Cycloaddition of nitrones in ionic liquids catalyzed by Er(III): an easy access to isoxazolidines

1,3-Dipolar cycloadditions of nitrones with alkenes afforded the corresponding isoxazolidines in ionic liquids in the presence of Er(OTf)₃. The ionic liquid and the catalyst are recycled up to five times without any specific treatment or loss of activity. Extension of the procedure to the synthesis of isoxazolidinyl nucleosides has been investigated.     

Study of the C(3P) + OH(X2Pi) --> CO(X1Sigma(g)+) + H(2S) reaction: a fully global ab initio potential energy surface of the X2A' state

The C((3)P) + OH(X (2)Pi) --> CO(X (1)Sigma(g)(+)) + H((2)S) reaction has been investigated by ab initio electronic structure calculations of the X(2)A' state based on the multireference (MR) internally contracted single and double configuration interaction (SDCI) method plus Davidson correction (+Q) using Dunning aug-cc-pVQZ basis sets. In particular, the multireference space is taken to be a complete active space (CAS). Improvement over previously proposed potential energy surfaces for HCO/COH is obtained in the sense that present surface describes also the potential part where the CO interatomic distance is large. A large number of geometries (around 2000) have been calculated and analytically fitted using the reproducing kernel Hilbert space (RKHS) method of Ho and Rabitz both for the two-body and three-body terms following the many-body decomposition of the total electronic energies. Results show that the global reaction is highly exothermic ( approximately 6.4 eV) and barrierless (relative to the reactant channel), while five potential barriers are located on this surface. The three minima and five saddle points observed are characterized and found to be in good agreement with previous work. The three minima correspond to the formation of HCO and COH complexes and to the CO + H products, with the COH complex being a metastable minimum relative to the product channel. The five saddle points correspond to potential barriers for both the dissociation/formation of HCO and COH into/from CO + H, to barriers for the isomerization of HCO into COH and to barriers for the inversion of HCO and COH through their respective linear configuration.