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Different Cations (different + cation)
Selected AbstractsThe effect of surface,solute interactions on the transport of solutes through porous materialsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2009D. A. Rose Summary We have investigated the effect of differences in surface charge, valency of ion, solute concentration, solution flux and physical structure on the leaching and uptake of individual ions from simple solutions flowing through porous materials. We studied the miscible displacement of solutions of four salts (KBr, K2SO4, CaBr2 and CaSO4) having different cation : anion ratios separately through three inert materials (ballotini, pumice and ceramic) and two sizes of a reactive material (sepiolite) over several ranges of concentration (c) and at many pore-water velocities (v) under steady vertical saturated flow. Breakthrough curves of individual effluent ions (K+, Br,, Ca2+ and SO42,) were analysed by CXTFIT 2.0 to optimize transport parameters (retardation factor, R; dispersion coefficient, K) assuming that transport was governed by the convective,dispersion equation. In the inert materials, R did not differ significantly from 1 irrespective of c. In sepiolite, R was < 1 for anions and > 1 for cations, and became more extreme as c decreased. R varied with the valency of the anions, as predicted by diffuse double layer theory, and with that of the cations by a simple charge balance. Freundlich isotherms, reconstructed from R values, described the sorption of the cations and exclusion of the anions. For the inert materials, K did not depend on the ion or c and increased monotonically with v. For sepiolite, K also increased with v and with small but non-significant differences between ions and concentrations. The K(v) functions were consistent with Passioura's theory of dispersion in aggregated media, and the transport was reversible as R and K values did not depend on whether the media were being leached or resalinized. The effective dispersion coefficient of an ion is K* = K/R so, although K(v) appears to be unaffected by ion or concentration of solute in sepiolite, K*(v) will be affected. Thus, the controlling factor of these surface,solute interactions is R. [source] Two polymeric nickel(II) complexes with aromatic benzene-1,2,4,5-tetracarboxylate and pyridine-2,5-dicarboxylate linkersACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2009Ana María Atria (,-Benzene-1,2,4,5-tetracarboxylato-,2O1:O4)bis[aquabis(2,2-methylpropane-1,3-diamine-,2N,N,)nickel(II)] methanol disolvate tetrahydrate, [Ni2(C10H2O8)(C5H14N2)4(H2O)2]·2CH4O·4H2O, (I), is dinuclear, with elemental units built up around an inversion centre halving the benzene-1,2,4,5-tetracarboxylate (btc) anion, which bridges two symmetry-related NiII cations. The octahedral Ni polyhedron is completed by two chelating 2,2-methylpropane-1,3-diamine (dmpda) groups and a terminal aqua ligand. Two methanol and four water solvent molecules are involved in a number of N,H...O and O,H...O hydrogen bonds which define a strongly bound two-dimensional supramolecular structure. The structure of catena -poly[[[bis(2,2-methylpropane-1,3-diamine-,2N,N,)nickel(II)]-,-pyridine-2,5-dicarboxylato-,3O5:N,O2 -[(2,2-methylpropane-1,3-diamine-,2N,N,)nickel(II)]-,-pyridine-2,5-dicarboxylato-,3N,O2:O5] octahydrate], {[Ni2(C7H3NO4)2(C5H14N2)3]·8H2O}n, (II), is polymeric, forming twisted chains around three independent Ni centres, two of which lie on inversion centres and the third in a general position. There are three chelating dmpda ligands (one disordered over two equally populated positions), which are each attached to a different cation, and two pyridine-2,5-dicarboxylate (pdc) anions, both chelating the Ni centre in general positions through an ,O,C,C,N, loop, while acting as bridges to the remaining two centrosymmetric Ni atoms. There are, in addition, eight noncoordinated water molecules in the structure, some of which are disordered. [source] Synthesis and transport abilities of new membrane materials incorporating bipyrazolic tripodsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Fouad Malek Abstract Membrane materials were obtained by photopolymerization reaction of formulation spread over a polyacrylonitrile (PAN) support. The formulation contains the active bipyrazolic tripods monomers, the styrene, and the photostart. The facilitated transport and the extraction power of Cd(II), Pb(II), and Hg(II) through the synthesized membranes were reported. We have determined both the diffusion flux F of different cations and the selectivity S of the prepared membranes towards each cations. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104, 3967,3972, 2007 [source] Influence of differently ionized species on fragmentation pathways and energetics of a potential adenosine receptor antagonist using a triple quadrupole and a multistage LTQ-OrbitrapÔ FTMS instrumentJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2009Wendy Zhong A systematic study was conducted to investigate the influence of differently ionized species on the fragmentation pathways and energetics of a piperazine-containing adenosine by using different cations or anions. Very different fragmentation mechanisms were observed in protonated- versus sodiated-molecules, which indicated that the proton is mobilized to promote the charge-direct fragmentation, whereas Na+ cation was fixed at the heterotricyclic ring structure provoking charge-remote fragment ions. This finding was also supported by the results observed in the fragmentation behaviors in the deprotonated-molecule. The energetics of these fragment ions were also explored by using the breakdown curves obtained from the triple quadrupole and LTQ-OrbitrapÔ instrument. The data indicated that the lowest energy pathways in the protonated-molecule [M+H]+ involve breaking a CN bond connecting an ethylene bridge and heterotricyclic ring structure. The lowest energy pathway is the cleavage of a CO bond connecting the methoxy ethyl group and phenolic oxygen to form a distonic radical ion for a sodiated-molecule [M+Na+]and a deprotonated-molecule [M-H],. The data suggest that by choosing the differently ionized species, one can probe different fragmentation channels that can provide additional structure information for an unknown impurity and possibly degradation product identification. In addition, by comparing the data obtained from triple quadrupole and LTQ-Orbitrap instruments, one can develop further understanding of the differences in the fragmentation behaviors due to the variations in the collision activation-dissociation process. From the side-by-side comparison with the breakdown curves obtained for both instruments, the difference in fragmentation behaviors caused by the difference in dissociation processes that occur in these two types of instruments can be probed. J. Heterocyclic Chem., (2009). [source] Poly[bis(,4 -benzene-1,2-dicarboxylato)di-,3 -isonicotinato-dilanthanum(III)]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2009Guo-Ming Wang In the title compound, [La2(C8H4O4)2(C6H4NO2)2]n, there are two crystallographically independent La centres, both nine-coordinated in tricapped trigonal prismatic coordination geometries by eight carboxylate O atoms and one pyridyl N atom. The La centres are linked by the carboxylate groups of isonicotinate (IN,) and benzene-1,2-dicarboxylate (BDC2,) ligands to form La,carboxylate chains, which are further expanded into a three-dimensional framework with nanometre-sized channels by La,N bonds. In the construction of the resultant architecture, in tricapped trigonal prismatic coordination geometries by eight carboxylate O atoms and one pyridyl N atom, while the BDC ligands link to four different cations each, displaying penta- and heptadentate chelating,bridging modes, respectively. [source] Coulombic interactions, hydrogen bonding and supramolecular chirality in pyridinium trifluoromethanesulfonateACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2009Israel Goldberg The title compound, C5H6N+·CF3SO3,, was serendipitously crystallized in the chiral space group P43212. The component entities associate into hydrogen-bonded helical chains, which propagate along the a and b axes of the crystal, with an alternating disposition of the cations and anions along the chain. N,H...O charge-assisted hydrogen bonds, from each pyridinium cation to two adjacent trifluoromethanesulfonate anions and from every anion to two different cations, direct the formation of the supramolecular chiral arrays. The crystal packing exhibits nonconventional C,H...O and C,H...F hydrogen bonds between the components. The observed structure demonstrates induction of supramolecular chirality by a combination of Coulombic attractions and intermolecular hydrogen bonds. [source] Monovalent cations affect the free solution mobility of DNA by perturbing the hydrogen-bonded structure of water,BIOPOLYMERS, Issue 2 2005Earle Stellwagen Abstract The free solution mobilities of single- and double-stranded DNA molecules of various molecular weights have been measured by capillary electrophoresis in solutions of constant ionic strength containing a common anion and fifteen different monovalent cations. In solutions with the same ionic composition, the mobilities of different DNA molecules can vary by up to 20%, depending on molecular weight, the number of strands, and the presence or absence of A-tracts, runs of four or more contiguous adenine residues. Importantly, the mobilities observed for the same DNA sample can vary by up to 40% in solutions containing different cations. The mobility differences observed for the same DNA in solutions containing different cations cannot be rationalized by differences in the anhydrous radii or intrinsic conductivities of the various cations, or by the sequence-dependent binding of certain cations to A-tracts. Instead, the observed mobilities are linearly correlated with the average number of water,water hydrogen bonds that are present in solutions containing different cations. The mobilities are also correlated with the viscosity B coefficients of the various cations and with the rotational correlation times frictional coefficients observed for water molecules in solutions containing different cations. Hence, monovalent cations modify the free solution mobility of DNA primarily by perturbing the hydrogen-bonded structure of water, affecting the friction experienced by the migrating DNA molecules during electrophoresis. © 2005 Wiley Periodicals, Inc. Biopolymers 78: 62,68, 2005 [source] | ||||||||||