Selective enhancement of scopadulcic acid B production in the cultured tissues of Scoparia dulcis by methyl jasmonate

The effects of methyl jasmonate (MeJA) on isoprenoid production were evaluated in cultured tissues of Scoparia dulcis. It was found that MeJA suppressed the accumulation of chlorophylls, carotenoids, phytol and beta-sitosterol in the tissues. MeJA, however, remarkably enhanced the production of scopadulcic acid B (SDB), with 10 microM being optimal observed concentration for stimulation of SDB production. The maximum concentration of SDB was observed 6 d after MeJA treatment.     

Gel permeation chromatography on polyelectrolytes in aqueous solution

Gel permeation chromatography of water-soluble polymers, with special attention to polyelectrolytes, has been studied. A three-detector system (refractometry, conductimetry, viscometry) is used to characterize the polymers. A single curve is obtained for the calibration of the set of columns taking into account the hydrodynamic volume of the solutes and using a 0.1 N salt solution as the eluent to screen electrostatic forces. The role of the low adsorption of dextran on silica gel is pointed out. The dependence of elution volume on polymer concentration is demonstrated and interpreted in terms of the screening length of the molecules.     

Formation of polyelectrolyte complexes in an organic solvent

The formation of complexes of polyelectrolytes has been investigated with low charged polyelectrolytes soluble in an organic solvent. The degree of complexation has been determined from conductimetric experiments; it is independent of the degree of quaternization of the polycation but decreases as the polymer concentration and the ionic content increase. A change in the conductimetric and in the viscometric curves during addition of polycation to the polyanion (or the reverse) has been found in the range of the ionic stoichiometry. The complex formation corresponds to an electrostatic cross-link the stability of which decreases with the ionic content of the solution.     

Synthesis and characterization of carboxymethylcelluloses (CMC) from non-wood fibers I.Accessibility of cellulose fibers and CMC synthesis

This paper explores the production of carboxymethylcellulose (CMC) fromseveral bleached cellulose pulps obtained from non-wood species. The chemicalcomposition (-cellulose, hemicellulose and lignin content), the degreeofswelling, viscosity, solubility in concentrated NaOH and crystallinity ofsoda/AQ cellulose pulps from abaca, jute, sisal, linen and Miscanthussinensis were determined. The pulps were carboxymethylated by one andtwo successive reaction steps in aqueous medium under identical conditions. Thedegree of substitution (DS) of CMC was found to be dependent upon the source ofthe cellulose pulp, but generally it was close to 1 with one etherificationtreatment and around 2 after the second. The molar mass of CMC was found to bedependent on the initial intrinsic viscosity of the cellulose pulp. The weightaverage molar mass of our CMCs ranged from 1.5×10⁵ to2.8×10⁵. Increasing the DS up to 2 improved the CMC solubility, butviscosity slightly decreased due to a slight degradation of the polymer.     

A Comprehensive Study and Characterization of Colloidal Emeraldine-Base

Soluble emeraldine-base (PANI-EB) was prepared and its structure was characterized using ¹H, ¹³C and 2D (COSY, HMQC and HMBC) NMR. The solubility of the polymer in two solvents (N-methylpyrrolidone (NMP) and dimethyl sulfoxide (DMSO), the structure of the solution (aggregation) and the behavior of polyaniline were studied by viscometry and by dynamic light scattering (DLS) in dilute solution. Viscometric behavior in NMP and Huggins constant determination confirm supramolecular interactions also evidenced by DLS; at end, the molecular weight of the soluble fraction of PANI-EB is determined.     

Preparation and study of new poly-8-hydroxyquinoline chelators for an anti-Alzheimer strategy

Fourteen different ligands have been synthesized with two covalently linked 8-hydroxyquinoline motifs that favor metal complexation. These bis-chelators include different bridges at the C2 positions and different substituents to modulate their physicochemical properties. They can form metal complexes in a ratio of one ligand per metal ion with Cu II and Zn II, two metal ions involved in the formation of amyloid aggregates of the toxic Abeta-peptides in the Alzheimer disease. The apparent affinity of all bis-8-hydroxyquinoline ligands for Cu II and Zn II are similar with logK Cu II approximately 16 and logK Zn II approximately 13 and are 10,000 times more efficient than for the corresponding 8-hydroxyquinoline monomers. Their strong chelating capacities allow them to inhibit more efficiently than the corresponding monomers the precipitation of Abeta-peptides induced by Cu II and Zn II and also to inhibit the toxic formation of H2O2 due to copper complexes of Abeta. The best results were obtained with a one-atom linker between the two quinoline units. X-ray analyses of single-crystals of Cu II, Zn II or Ni II complexes of 2,2'-(2,2-propanediyl)-bis(8-hydroxyquinoline), including a one-atom linker, showed that all heteroatoms of the bis-8-hydroxyquinoline ligand chelate the same metal ion in a distorted square-planar geometry. The Cu II and Zn II complexes include a fifth axial ligand and are pentacoordinated.     

Pore-Scale Simulation of Interphase Multicomponent Mass Transfer for Subsurface Flow

A simulation framework is proposed to simulate multicomponent multiphase flow in porous media at the pore scale. It solves equations for the species concentrations in the framework of the volume-of-fluid approach including thermodynamics equilibrium at the fluid/fluid interface. Particular attention is paid to the derivation of the boundary condition for the concentration at the solid walls. The method is validated by comparison with analytical solutions of simple setups. Then, the approach is used to investigate and upscale mass transfer across interfaces in different configurations, including the drainage of water in a tube by a gas carrying a contaminant, mass transfer in thin films, and mass transfer in complex porous structures under various flow conditions.