Synthesis and crystal structures of 4,4′-bipyridinium and 2,2′-bipyridinium pentachloro complexes containing the polynuclear anions [Bi2Cl10]4− and [Bi4Cl20]8−

The compounds 4,4-bipyridinium(2+) pentachloro-bismuthate(III) (1), [4,4-(C₁₀H₈N₂)BiCl₅] and 2,2-bipyridinium(2+) pentachloro-bismuthate(III) (2), [2,2-(C₁₀H₈N₂)Bi₂Cl₁₀] have been obtained by reacting bismuthate oxide and 4,4-bipyridine or 2,2-bipyridine in HCl acid medium. They have been characterized by single crystal X-ray analysis. (1) crystallizes in the triclinic space group with a = 9.776(2), b = 11.009(3),c = 8.346(1) Å, = 101.58(2), = 98.63(2), and = 112.86(2)°. (2) crystallizes in the monoclinic space group P2₁/c with a = 14.239(2), b = 14.226(2), c = 16.275(3) Å, and = 110.15(2)°. The crystal structure of (1) consists of 4,4-bipyridinium(2+) cations interacting through hydrogen bonding with [Bi₂Cl₁₀]^2– dimers giving rise to endless double chains, while that of (2) is formed by 2,2-bipyridinium(2+) cations and [Bi₄Cl₂₀]^8– tetramers extensively interacting through hydrogen bonding. The different polynuclearity of the anions seems related to the different directions along which each cation can form hydrogen bond interactions.     

Direct determination of adsorption heats

Energy changes occurring during adsorption in gas-solid and solution-solid systems are considered in connection with measurement of the adsorption enthalpies. Some experimental apparatuses allowing determination both of heat evolved and adsorbed amounts are described, with special regard to those using heat-flow microcalorimeters. Calibration techniques and experimental data reliability are also discussed.     

Synthesis and Structural Characterization of the Trimeric Furoxan (= Furazan 2-Oxide) System,a New Potent Vasodilating Moiety

The synthesis, structural characterization, and NO donor properties of a series of terfuroxan (= terfurazan trioxide) derivatives 1a–h and 2a–j are reported (Schemes 1 and 2). Structural assignments were confirmed principally by mass and ¹³C- and ¹H-NMR spectroscopy. The extent and the initial rate of NO release in the presence of thiol cofactor was evaluated for each derivative. Vasodilator effects of all the terfuroxan derivatives were evaluated on endothelium-denuded strips of rat aorta precontracted with noradrenaline. Concentration-response curves were also evaluated in the presence of 10 m?M oxyhemoglobin (HbO₂), a well known NO scavenger. The whole series displays high vasodilating potency; the most active terfuroxans ( 1a, b, g and 2i ) are 5–10 times as potent as glyceryl trinitrate taken as reference (see Table 3). The potency decrease observed in the presence of HbO₂ agrees with the involvement of NO in the vasorelaxing action. The 4,3′:4′,4″ connection (series 1 ; furoxan numbering) gives rise to the most potent compounds. The conformational factors seem to play important roles in the activity. No clear relationship between physico-chemical properties of the substituents and potencies of derivative emerges.     

Rapid Resolution Liquid chromatography/High Resolution Tandem Mass Spectrometry to Characterize Metabolic Changes in Subjects Involved in MARS500 Project

A rapid resolution liquid chromatography-tandem mass spectrometry analysis was applied to human urine samples to discover new molecular biomarkers of the alteration of psychophysical well-being due to the environmental, physiological and confinement stress conditions achieved in the MARS500 project. Urine samples of crew members were submitted to metabolomic studies by means of separative techniques coupled with mass spectrometric techniques and data analysis. More than 2,000 metabolite features were found in each comparison, and more than 150 metabolites were identified for every differential analysis. Significant modifications in eight metabolites were shared by the subjects under study.     

Evaluation of different light-curing lamps

The aim of this study has been to evaluate light-curing composites polymerization quality carried out by halogen and new-diode lamps through the thermal analysis (TG?CDTA). Samples have been polymerized at 3?C20?C40?C60?s by halogen lamp and 1?C3?C6?C9?s by new-diode lamp. The TG/DTA analysis shows that different light-curing times affect the degree of conversion of the composite, since by increasing the curing time the quantity of the monomer that has not reacted (residual) decreases. The new-diode lamp, according to the manufacturer, can cure composite restorations in few seconds; but at the conditions used in this study, the samples cured by the halogen lamp at the standard times of exposure, compared to the samples cured in few seconds by the new-diode lamp, show a lower mass loss.     

Variational Convergences of Dual Energy Functionals for Elastic Materials with a ε-Thin Strong Inclusion

We give a new derivation, based on the complementary energy formulation, of a simplified model for a multi-structure made up of two anisotropic hyper-elastic bodies connected by a thin strong material layer. The model is obtained by identifying the Mosco-limit of the stored complementary energy functional when the thickness is of order ?? and the stiffness of order 1/?? where ?? is a positive real adimensional parameter. In order to prove the existence of the displacement associated with the stress we use a suitable weak version of the Saint-Venant compatibility condition also known as Donati??s theorem.     

Component-Mode Synthesis Method Variants in the Dynamics of Coupled Structures

The component-mode synthesis method is usually adopted in order to reduce the number of degrees-of-freedom of structures composed of two or more substructures without loosing the main physical characteristics of the whole structure. Many approaches of this method have been proposed in the literature. These approaches differ from each other for the boundary conditions which are imposed at the interface of the two substructures. In this paper four variants of interface boundary conditions are examined. For each set of conditions a suitable coordinate transformation, compatible with the conditions at the boundary degrees-of-freedom between the two substructures, is presented. Moreover, in the numerical applications a comparison between the four component-mode synthesis variants here proposed with respect to the same variants proposed in the literature is presented. The better accuracy of the proposed approach is shown.     

Cathodic chloride extraction treatment of a late bronze-age artifact affected by bronze disease in room-temperature ionic-liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMI-TFSI)

This paper concentrates on a novel approach to the electrochemical treatment of bronze disease, based on the use of room-temperature ionic liquids (RTIL). In particular, we employed 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as the electrolyte for the galvanostatic cathodic treatment of a late bronze-age artifact that had been exposed to marine environment during its history, dating back to ca. 1100 B.C. After an accurate metallographic and structural analysis of the as-found object—proving, among other findings, that bronze disease is essentially related to the presence of nantokite locked inside subsurface pits of typical equivalent diameter of several hundred micrometers, we subjected it to optimal electrochemical conditions, showing—on the basis of X-ray diffraction—that nantokite could be effectively removed and Cu(I) reduced to metallic Cu. Numerical computations in the full three-dimensional pit geometry, with realistic nonlinear electrochemical boundary conditions, provide the theoretical framework for the choice of RTIL—as opposed to aqueous solutions—and for the quantitative evaluation of Cl⁻ removal rates.