Mesoporous zirconium titanium oxides. Part 1: Porosity modulation and adsorption properties of xerogels

A series of zirconium titanium oxide mesophases containing 33 atom % Zr have been prepared using carboxylic acids of different alkyl chain lengths (Cy ) from y=4-18 through organic-inorganic polymer phase segregation as the gel transition is approached. Thermal treatment of these transparent gels up to 450 degrees C eliminated the organic template, and domain coarsening occurred affording stable worm-hole mesoporous materials of homogeneous composition and pore diameters varying from about 3 to 4 nm in fine increments. With such materials, it was subsequently possible to precisely study the adsorption of vanadium oxo-anions and cations from aqueous solutions and, more particularly, probe the kinetics of intraparticle mass transport as a function of the associated pore dimension. The kinetics of mass transport through the pore systems was investigated using aqueous vanadyl (VO2+) and orthovanadate (VO3(OH)2-) probe species at concentrations ranging from 10 to 200 ppm (0.2 to 4 mmol/L) and pH values of 0 and 10.5, respectively. In the case of both of these vanadium species, the zirconium titanate mesophases displayed relatively slow kinetics, taking in excess of about 500 min to achieve maximum uptake. By using a pseudo-second-order rate law, it was possible to extract the instantaneous and overall rate of the adsorption processes and then relate these to the pore diameters. Both the instantaneous and overall rates of adsorption increased with increasing surface area and pore diameter over the studied pore size range. However, the equilibrium adsorption capacity increased linearly with pore diameter only for the higher concentrations and was independent of pore diameter for the lower concentration. These results have been interpreted using a model in which discrete adsorption occurs at low concentrations and is then followed by multilayer adsorption at higher concentration.     

An integrated method for metabolite detection and identification using a linear ion trap/Orbitrap mass spectrometer and multiple data processing techniques: application to indinavir metabolite detection

A new strategy using a hybrid linear ion trap/Orbitrap mass spectrometer and multiple post-acquisition data mining techniques was evaluated and applied to the detection and characterization of in vitro metabolites of indinavir. Accurate-mass, full-scan MS and MS/MS data sets were acquired with a generic data-dependent method and processed with extracted-ion chromatography (EIC), mass-defect filter (MDF), product-ion filter (PIF), and neutral-loss filter (NLF) techniques. The high-resolution EIC process was shown to be highly effective in the detection of common metabolites with predicted molecular weights. The MDF process, which searched for metabolites based on the similarity of mass defects of metabolites to those of indinavir and its core substructures, was able to find uncommon metabolites not detected by the EIC processing. The high-resolution PIF and NLF processes selectively detected metabolites that underwent fragmentation pathways similar to those of indinavir or its known metabolites. As a result, a total of 15 metabolites including two new indinavir metabolites were detected and characterized in a rat liver S9 incubation sample. Overall, these data mining techniques, which employed distinct metabolite search mechanisms, were complementary and effective in detecting both common and uncommon metabolites. In summary, the results demonstrated that this analytical strategy enables the high-throughput acquisition of accurate-mass LC/MS data sets, comprehensive search of a variety of metabolites through the post-acquisition processes, and effective structural characterization based on elemental compositions of metabolite molecules and their product ions.     

Mizellare Wechselwirkung und ihre katalytische Rolle bei der Polymerisation von Acrylamid, die durch Bisulfit katalysiert wird

Ohne Zusammenfassung     

Isotopenaustausch von molekularem Sauerstoff mit dem Sauerstoff von Ni-Molybdat

Ohne Zusammenfassung     

Inelastic p-He scattering at 141 MeV

Inelastic p-⁴He scattering at 141±2 MeV has been investigated with a high-pressure cloud chamber filled with helium. Results are presented for the total cross sections of each reaction channel and the neutron spectra for the p(⁴He, pn)³He reaction.     

Crystal and molecular structure of polymeric dilithium tetra(propionato)cadmium(II): A layered inorganic ionic-organic molecular structure

The structure of the title compound is made up of a central sheet containing only metal and oxygen atoms with organic moieties outside and between sheets. The Cd(II) is on a crystallographic center of symmetry and is bound to six propionate oxygen atoms to yield a coordination geometry of an approximate octahedron. Each lithium has four oxygen nearest neighbors to form a distorted tetrahedral geometry. The lithium atoms are in pairs via oxygen bridges to form unsymmetrical Li₂O₂ parallelograms with a crystallographic center of symmetry in the middle. Crystal data: Li₂Cd(C₃H₅O₂)₄,M _r =419, triclinic,P¯1,a=7.526(1),b=11.296(2),c=4.925(1) Å,=94.85(2),=98.04(2), =78.97(2)°,V=406(1) ų,Z=1,D _m =1.70(2),D _x =1.71 g cm^–3, T 298K,R=0.028 for 2303 reflections.     

Synthesis and trimerization of fluorinated tertiary cyanates

Monofunctional and bifunctional bis(α,α-trifluoromethyl) cyanates were prepared by reaction of a fluorinated alkoxide with cyanogen bromide or cyanogen chloride. In the synthesis of bifunctional cyanates, the cyanation reaction required sufficient intramolecular separation for independent functional group reactivity. Monofunctional cyanates could be rapidly and quantitatively trimerized to cyclic cyanurates by catalytic quantities of AlCl₃. Polymerization by trimerization of bifunctional cyanates under identical conditions was not successful, apparently, due to encasement of the catalyst by the polymer network.