Structure and absolute stereochemistry of novel C15-halogenated acetogenins from the anaspidean mollusc Aplysia dactylomela

Three novel halogenated C₁₅-acetogenins, compounds 1-3, have been isolated, together with known metabolites, from a South China Sea collection of the anaspidean mollusc Aplysia dactylomela. The structures have been suggested by both NMR analysis and comparison with literature data. The structure of 1 was confirmed by a single crystal X-ray study, which also allowed the establishment of its absolute stereochemistry.     

Estensioni semigruppali

Sommario Si da un nuovo metodo per costruire algebre da una data algebra, si studiano le identità che si conservano in questa costruzione e l'operatore ad essa collegato.

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Summary I give a new method for building new algebras from a given algebra, we study identities preserved in this construction and related operator.

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Lavoro eseguito nell'ambito dell'attività dei gruppi di ricerca matematica del C.N.R. contratto n. 115218205174.

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Ringrazio il Prof.R. Magari dell'Università di Ferrara sotto la cui guida è stato eseguito questo lavoro.     

Synthesis of 6-phenanthridinones and their heterocyclic analogues through palladium-catalyzed sequential aryl-aryl and N-aryl coupling

[reaction: see text] 6-Phenanthridinones and their heterocyclic analogues were synthesized through a one-pot procedure based on consecutive Pd-catalyzed aryl-aryl and N-aryl coupling from iodoarenes ortho-substituted by electron-releasing substituents and amides of o-bromoarene- and heteroarenecarboxylic acids.     

Comparing some operational approaches to the limit of detection

The limit of detection is one of the fundamental metrological characteristics of any chemical measurement systems but, even now, it is a highly controversial matter because of the existing differences in terminology, formulations and understanding. Even when limiting the analysis to those operational approaches that, because of their simplicity, are often suggested by the guidelines of some international bodies, the available approaches can return appreciably different estimates. In this paper, the matter is critically reconsidered, and the different approaches compared with the aid of some case studies.     

Patavine, a new arylnaphthalene lignan glycoside from shoot cultures of Haplophyllum patavinum

A new arylnaphthalene lignan glycoside, patavine (1), together with five known lignans, justicidin B (2), diphyllin (3), tuberculatin (4), majidine (5), and arabelline (6) were isolated from shoot cultures of Haplophyllum patavinum. The structure of the new compound was elucidated by extensive one-dimensional (1D) and two-dimensional (2D) NMR experiments and mass spectrometry. The cytotoxicity of compounds 1, and 3-6 against LoVo human colon carcinoma cells was investigated.     

Ammonium N‐acetyl‐l‐threoninate and methyl­ammonium N‐acetyl‐l‐threoninate

Ammonium N‐acetyl‐l ‐threoninate, NH₄⁺·C₆H₁₀NO₄^?, and methyl­ammonium N‐acetyl‐l ‐threoninate, CH₆N⁺·­C₆H₁₀NO₄^?, crystallize in the orthorhombic P2₁2₁2₁ and monoclinic P2₁ space groups, respectively. The two crystals present the same packing features consisting of infinite ribbons of screw‐related N‐acetyl‐l ‐threoninate anions linked together through pairs of hydrogen bonds. The cations interconnect neighbouring ribbons of anions involving all the nitrogen‐H atoms in three‐dimensional networks of hydrogen bonds. The hydrogen‐bond patterns include asymmetric `three‐centred' systems. In both structures, the Thr side chain is in the favoured (g^?g⁺) conformation.     

Analysis on distribution coefficients of Strontium and Cesium for safety assessment studies

The distribution coefficients of strontium and cesium in an Italian nuclear site were studied. Distribution coefficient is a fundamental parameter in safety assessment studies on radionuclide migration into the environment. A sensitivity analysis to identify the main influencing factors on the variation of distribution coefficient in subsoil was carried out. Cation exchange capacity was identified as the main influencing parameter, thus a correlation between cation exchange capacity and distribution coefficient was estimated. In this way, the determination of cation exchange capacity, that is less consuming, makes it possible to easily obtain a preliminary, but reliable distribution coefficient on extensive sites.     

Predicting bank loan recovery rates with a mixed continuous‐discrete model

To represent the high concentration of recovery rates at the boundaries, we propose to consider the recovery rate as a mixed random variable, obtained as the mixture of a Bernoulli random variable and a beta random variable. We suggest to estimate the mixture weights and the Bernoulli parameter by two logistic regression models. For the recovery rates belonging to the interval (0,1), we model, jointly, the mean and the dispersion by using two link functions, so we propose the joint beta regression model that accommodates skewness and heteroscedastic errors. This methodological proposal is applied to a comprehensive survey on loan recovery process of Italian banks. In the regression model, we include some macroeconomic variables because they are relevant to explain the recovery rate and allow to estimate it in downturn conditions, as Basel II requires. Copyright © 2012 John Wiley & Sons, Ltd.     

Hydrorepellent finishing of cotton fabrics by chemically modified TEOS based nanosol

Hydrorepellency was conferred to cotton fabrics by an hybrid organic–inorganic finishing via sol–gel. The nanosol was prepared by co-hydrolysis and condensation of tetraethoxysilane (TEOS) and 1H,1H,2H,2H–fluorooctyltriethoxysilane (FOS), or hexadecyltrimethoxysilane (C₁₆), as precursors in weakly acid medium. The application on cotton was carried out by padding with various impregnation times, followed by drying and thermal treatment, varying the FOS add-on from 5 till 30 % on fabric weight or C₁₆ add-on from 5 to 10 %. Treated samples were tested in terms of contact angles, drop absorption times, washing fastness and characterized by SEM, XPS and FTIR-ATR analyses. In the case of FOS modified nanosol applied with an impregnation time of 24 h or C₁₆ modified nanosol, water contact angles values very close or even higher than 150° were measured, typical of a superhydrophobic surface. The application of the proposed sol–gel process yielded also a satisfactory treatment fastness to domestic washing, in particular for FOS modified nanosol.