Gouvernance et gestion des espaces hydrographiques nationaux et internationaux: I’analyse du cas espagnol et des conflits de l’eau dans le bassin de l’Ebre

"Il existe trois scénarios d’insécurité environnementale en Colombie dans lesquels la relation entre l’état des ressources naturelles en eau, pétrole et biodiversité (pénurie, dégradation, surexploitation, risque d’appropriation et terrorisme écologique) et la situation des rapports de force internes et régionaux (exacerbation des tensions interétatiques, sociétales et insécurité humaine) est évidente. Ce résultat a été démontré lors d’un projet de recherche antérieur (2002-2005) menée par l’auteur de ce document de recherche dans le cadre de la ligne de recherche en sécurité régionale et internationale du Centre d’Etudes Politiques et Internationales -CEPI- des Facultés de Science Politique et Gouvernements et de Relations Internationales de l’Université du Rosario de Bogota..."

Photodynamic Antimicrobial Effects Of Bis-indole Alkaloid Indigo From Indigofera Truxillensis Kunth (leguminosae).

Multidrug-resistant microbial infections represent an exponentially growing problem affecting communities worldwide. Photodynamic therapy is a promising treatment based on the combination of light, oxygen, and a photosensitizer that leads to reactive oxygen species production, such as superoxide (type I mechanism) and singlet oxygen (type II mechanism) that cause massive oxidative damage and consequently the host cell death. Indigofera genus has gained considerable interest due its mutagenic, cytotoxic, and genotoxic activity. Therefore, this study was undertaken to investigate the effect of crude extracts, alkaloidal fraction, and isolated substance derived from Indigofera truxillensis in photodynamic antimicrobial chemotherapy on the viability of bacteria and yeast and evaluation of mechanisms involved. Our results showed that all samples resulted in microbial photoactivation in subinhibitory concentration, with indigo alkaloid presenting a predominant photodynamic action through type I mechanism. The use of CaCl2 and MgCl2 as cell permeabilizing additives also increased gram-negative bacteria susceptibility to indigo.

Estudos de relações estrutura-atividade quantitativas (QSAR) de bis-benzamidinas com atividade antifúngica

This paper describes 2D-QSAR and 3D-QSAR studies against Candida albicans and Cryptococcus neofarmans for a set of 20 bisbenzamidines. In the studies of 2D-QSAR with C. albicans it was obtained a correlation between log MIC-1 and lipolo component-Z (r² = 0.68; Q² = 0.51). In the case of C. neofarmans a correlation between log MIC-1 and lipolo component-Z and of Balaban index (r² = 0.85; Q² = 0.6) was obtained. 3D-QSAR studies using CoMFA showed that the steric fields contributed more to the predicted activities for Candida albicans (94.9%) and Cryptococcus neofarmans (97.9%).

Characterization studies of 1-(4-cyano-2-oxo-1,2-dihydro-1-pyridyl)-3-(4-cyano-1,2-dihydro-1-pyridyl)propane formed from the reaction of hydroxide Ion with 1,3-Bis-(4-cyano pyridinium)propane

The aqueous alkaline reaction of 1,3-bis(4-cyanopyridinium)propane dibromide, a reactant constituted of two pyridinium rings linked by a three-methylene bridge, generates a novel compound,1 -(4-cyano-2-oxo-1,2-dihydro-1-pyridyl)-3-(4-cyano-1,2-dihydro-1-pyridyl)propane. The reaction pathway is attributed to the proximity of the OH- ion inserted between two pyridinium moieties, which occurs only in bis(pyridinium) derivatives connected by short methylene spacers, where charge-conformational effects are important.

Electrocatalytic oxidation of methanol by the [Ru3O(OAc)6(py)2(CH3OH)]3+cluster: improving the metal-ligand electron transfer by accessing the higher oxidation states of a multicentered system

The [Ru3O(Ac)6(py)2(CH3OH)]+ cluster provides an effective electrocatalytic species for the oxidation of methanol under mild conditions. This complex exhibits characteristic electrochemical waves at -1.02, 0.15 and 1.18 V, associated with the Ru3III,II,II/Ru3III,III,II/Ru 3III,III,III /Ru3IV,III,III successive redox couples, respectively. Above 1.7 V, formation of two RuIV centers enhances the 2-electron oxidation of the methanol ligand yielding formaldehyde, in agreement with the theoretical evolution of the HOMO levels as a function of the oxidation states. This work illustrates an important strategy to improve the efficiency of the oxidation catalysis, by using a multicentered redox catalyst and accessing its multiple higher oxidation states.

Spectroscopic characterization and investigation of the dynamic of charge compensation process of supramolecular films derived from tetra-2-pyridyl-1,4-pyrazine ligand

This work describes the infrared spectroscopy characterization and the charge compensation dynamics in supramolecular film FeTPPZFeCN derived from tetra-2-pyridyl-1,4-pyrazine (TPPZ) with hexacyanoferrate, as well as the hybrid film formed by FeTPPZFeCN and polypyrrole (PPy). For supramolecular film, it was found that anion flux is greater in a K+ containing solution than in Li+ solution, which seems to be due to the larger crystalline ionic radius of K+. The electroneutralization process is discussed in terms of electrostatic interactions between cations and metallic centers in the hosting matrix. The nature of the charge compensation process differs from others modified electrodes based on Prussian blue films, where only cations such as K+ participate in the electroneutralization process. In the case of FeTPPZFeCN/PPy hybrid film, the magnitude of the anions’s flux is also dependent on the identity of the anion of the supporting electrolyte.

Bis[(4-methylphenyl)ethynyl] telluride

The tellurium atom in the title bis-ethynyl telluride, Te(C(9)H(7))(2) or C(18)H(14)Te, is located on a crystallographic twofold axis, the C-Te-C angle being 92.23 (15)degrees. The dihedral angle between the rings is 87.27 (7)degrees. In the crystal structure, molecules are connected in chains parallel to the b axis and mediated by C-H center dot center dot center dot pi interactions.

Genetic variability and natural selection at the ligand domain of the Duffy binding protein in brazilian Plasmodium vivax populations

Background: Plasmodium vivax malaria is a major public health challenge in Latin America, Asia and Oceania, with 130-435 million clinical cases per year worldwide. Invasion of host blood cells by P. vivax mainly depends on a type I membrane protein called Duffy binding protein (PvDBP). The erythrocyte-binding motif of PvDBP is a 170 amino-acid stretch located in its cysteine-rich region II (PvDBP(II)), which is the most variable segment of the protein. Methods: To test whether diversifying natural selection has shaped the nucleotide diversity of PvDBP(II) in Brazilian populations, this region was sequenced in 122 isolates from six different geographic areas. A Bayesian method was applied to test for the action of natural selection under a population genetic model that incorporates recombination. The analysis was integrated with a structural model of PvDBP(II), and T-and B-cell epitopes were localized on the 3-D structure. Results: The results suggest that: (i) recombination plays an important role in determining the haplotype structure of PvDBP(II), and (ii) PvDBP(II) appears to contain neutrally evolving codons as well as codons evolving under natural selection. Diversifying selection preferentially acts on sites identified as epitopes, particularly on amino acid residues 417, 419, and 424, which show strong linkage disequilibrium. Conclusions: This study shows that some polymorphisms of PvDBP(II) are present near the erythrocyte-binding domain and might serve to elude antibodies that inhibit cell invasion. Therefore, these polymorphisms should be taken into account when designing vaccines aimed at eliciting antibodies to inhibit erythrocyte invasion.

cis-Bis{1,1-dibenzyl-3-[(furan-2-yl)carbonyl]thioureato-kappa 2 O,S}nickel(II)

In the title compound, [Ni(C(20)H(17)N(2)O(2)S)(2)], the NiII atom is coordinated by the S and O atoms of two 1,1-dibenzyl-3-[(furan-2-yl)carbonyl]thioureate ligands in a distorted square-planar geometry. The two O and two S atoms are mutually cis to each other. The Ni-S and Ni-O bond lengths lie within the range of those found in related structures. The dihedral angle between the planes of the two chelating rings is 20.33 (6)degrees.

Design of 1D and 2D molecule-based magnets with the ligand 4,5-dimethyl-1,2-phenylenebis(oxamato)

Three new bimetallic oxamato-based magnets with the proligand 4,5-dimethyl-1,2-phenylenebis-(oxamato) (dmopba) were synthesized using water or dimethylsulfoxide (DMSO) as solvents. Single crystal X-ray diffraction provided structures for two of them: [MnCu(dmopba)(H(2)O)(3)]n center dot 4nH(2)O (1) and [MnCu(dmopba)(DMSO)(3)](n center dot)nDMSO (2). The crystalline structures for both 1 and 2 consist of linearly ordered oxamato-bridged Mn(II)Cu(II) bimetallic chains. The magnetic characterization revealed a typical behaviour of ferrimagnetic chains for 1 and 2. Least-squares fits of the experimental magnetic data performed in the 300-20 K temperature range led to J(MnCu) = -27.9 cm(-1), g(Cu) = 2.09 and g(Mn) = 1.98 for 1 and J(MnCu) = -30.5 cm(-1), g(Cu) = 2.09 and g(Mn) = 2.02 for 2 (H = -J(MnCu)Sigma S(Mn, i)(S(Cu, i) + S(Cu, i-1))). The two-dimensional ferrimagnetic system [Me(4)N](2n){Co(2)[Cu(dmopba)](3)}center dot 4nDMSO center dot nH(2)O (3) was prepared by reaction of Co(II) ions and an excess of [Cu(dmopba)](2-) in DMSO. The study of the temperature dependence of the magnetic susceptibility as well as the temperature and field dependences of the magnetization revealed a cluster glass-like behaviour for 3.

Bis(tetraphenylphosphonium) tris[N-(methylsulfonyl)dithiocarbimato(2-)-kappa(2)S,S ']stannate(IV)

In the title complex, (C(24)H(20)P)(2)[Sn(C(2)H(3)NO(2)S(3))(3)], the Sn(IV) atom is coordinated by three N-(methylsulfonyl) dithiocarbimate bidentate ligands through the anionic S atoms in a slightly distorted octahedral coordination geometry. There is one half-molecule in the asymmetric unit; the complex is located on a crystallographic twofold rotation axis passing through the cation and bisecting one of the (non-symmetric) ligands, which appears thus disordered over two sites of equal occupancy. In the crystal structure, weak intermolecular C-H center dot center dot center dot O and C-H center dot center dot center dot S interactions contribute to the packing stabilization.

cis-Bis[1,1-dibenzyl-3-(furan-2-ylcarbonyl)thioureato-kappa(2)O,S]copper(II)

In the title compound, [Cu(C(20)H(17)N(2)O(2)S)(2)], the Cu(II) atom is coordinated by the S and O atoms of two 1,1-dibenzyl-3-(furan-2-ylcarbonyl)thioureate ligands in a distorted square-planar geometry. The two O and two S atoms are mutually cis to each other. The Cu-S and Cu-O bond lengths lie within the ranges of those found in related structures. The dihedral angle between the planes of the two chelating rings is 26.15 (6)degrees.

cis-Bis[N-(2-furoyl)-N ',N '-diphenylthioureato-kappa(2)O,S]nickel(II)

In the title compound, [Ni(C(18)H(13)N(2)O(2)S)(2)], the Ni(II) atom is coordinated by the S and O atoms of two N-furoyl-N ',N '-diphenylthioureate ligands in a slightly distorted squareplanar coordination geometry. The two O and two S atoms are cis to each other.

cis-bis(N-benzoyl-N ',N '-dibenzylthio-ureato-kappa O-2,S)nickel(II)

In the title compound, [Ni(C22H19N2OS)(2)], the Ni-II atom is coordinated by the S and O atoms of two N-benzoyl-N',N'-dibenzylthioureate ligands in a slightly distorted square-planar geometry. The two O atoms are cis, as are the two S atoms.

3,3-Bis[(4-chlorophenyl)sulfanyl]-1-methylpiperidin-2-one

The piperidone ring in the title compound, C(18)H(17)Cl(2)NOS(2), has a distorted half-chair conformation. The S-bound benzene rings are approximately perpendicular to and splayed out of the mean plane through the piperidone ring [dihedral angles = 71.86 (13) and 46.94 (11)degrees]. In the crystal, C-H center dot center dot center dot O interactions link the molecules into [010] supramolecular chains with a helical topology. C-H center dot center dot center dot Cl and C-H center dot center dot center dot pi interactions are also present.