Screening of acetogenin-producing plants in Brazilian flora

The acetogenins are strongly bioactive natural compounds present in the bark, roots, leaves, and seeds of manyAnnonaceae plants. They are modified fatty acids and their cytotoxicities have been determined for different biological models including the in vitro growth inhibition of several human cancer cell lines. Very low acetogenin yield (< 0.1 g%) has been found previously in native phytobiomass, and we have now investigated the nonpredatory exploitation of the seeds as acetogenin sources characterizing the seed triacylglycerols (dominant fraction; > 90% of the whole lipid extracts) as potential valuable by-products.     

Etude par Résonance Magnétique Nucléaire de dioxaphosphorinanes-1,3,2 à liaison P?N extracyclique. Exemple de changement d'orientation de la liaison P?N

The ¹H NMR spectra of several 1,3,2-dioxaphosphorinanes bearing an extracyclic P? N bond have been analysed. The ³J(POCH) couplings are strongly dependent upon the orientation of the bond around the phosphorus atom. Depending upon the nature of the bonds attached to the nitrogen atom, the dioxaphosphorinane ring may adopt either a fixed chair conformation with the P? N bond in the axial or equatorial orientation, or it may be in equilibrium between two chair conformations where the P? N bond is alternately axial or equatorial. The equilibrium is fast on the NMR time scale.     

1H, 13C, 31P NMR and conformational study of 7-membered ring organophosphorus compounds. 1,3,2-dioxaphosphepanes

The ¹H, ¹³C and ³¹P NMR data of several 2-R-2-thiono-1,3-dioxa organophosphorus molecules with 7-membered rings [R = Cl, OC₆H₅, C₆H₅, CH₃, N(CH₃)₂] are reported. The conformation of the 7-membered ring is discussed by reference to the ³J(POCH) coupling constants which are compared with those observed in 6-membered 1,3,2-dioxaphosphorinanes. It is shown that caution must be exercised in using the ³J(POCH) angular dependence as a stereochemical tool. The ³¹P spin lattice relaxation times of some of these 7-membered rings have been measured and the values are discussed.     

Radiative processes as a condensation phenomenon and the physical meaning of deformed canonical structures

We study the radiative corrections of QED₃ from the dual point of view and show that this process is the exact dual to the Julia–Toulouse mechanism introduced by Quevedo and Trugenberger [F. Quevedo, C.A. Trugenberger, Nucl. Phys. B 501 (1997) 143] some years ago. We discuss the physics behind this mechanism that involves condensation of topological defects. It is shown that the dual Stuckelberg mechanism is responsible for the “rank-jump” phenomenon that transforms the scalar field (dual to Maxwell in this dimensionality) into the vectorial self-dual field. This phenomenon is studied using the ideas of noncommutative fields theory that examines possible deformations of the canonical structure of some well-known models in (2+1)D$(2+1)\mathrm{D}$. A deformation is constructed linking the massless scalar field theory with the self-dual theory. This is the exact dual of the known deformation connecting the Maxwell theory with the Maxwell–Chern–Simons theory. Duality, radiative corrections, the Julia–Toulouse mechanism and canonical deformations are then used to establish a web of relations between the mentioned theories and to propose a physical picture of the deformation procedure adopted.     

Development and application of electrochemical sensor of boron-doped diamond (BDD) modified by drop casting with tin hexacyanoferrate

Journal of Solid State Electrochemistry - This work presents the development and characterization of an electrochemical sensor of tin hexacyanoferrate (SnHCF), produced from the modification by...     

Sulfites a huit et seize chainons

The cyclisation reaction of 2-mercaptoethyl sulfide (S(CH₂CH₂SH)₂) or 2-hydroxyethyl ether (O(CH₂CH₂OH)₂) with thionyl chloride (OSCl₂) leads in addition to the expected eight-membered ring sulfites to the formation of the corresponding sixteen-membered ring dimers.