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At least 1,801 records · Page 100Linked to original sources
PubMed2006

Experimental study on the effect of SO2 on PCDD/F emissions: determination of the importance of gas-phase versus solid-phase reactions in PCDD/F formation.

Cofiring coal in municipal solid waste incinerators (MSWls) has previously been reported to reduce polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs) emissions due to increasing the flue gas SO2 concentration. The present study was focused on understanding the primary mechanism responsible for the suppressant effect of SO2 on total PCDD/F formation and toxic equivalent (TEQ) emissions. The addition of SO2, simulating the effect of coal addition on the flue gas composition, resulted in significant reductions in the TEQ emissions due to reactions involving SO2 in the postcombustion zone. However, emissions of total PCDDs/Fs, unlike the TEQ value, were dependent upon the Cl2 and SO2 injection temperatures due to increases in non-TEQ correlated isomers. The conversion of metal chlorides in the fly ash to sulfates, thus reducing the sites responsible for chlorination/oxidation reactions, was concluded to be the main suppressant mechanism; proposed reactions for copper and iron are presented. This mechanism was found to be independent of combustion conditions and could have prolonged effects on PCDD/F emissions from deposits formed with high flue gas S/Cl ratios.

Air Pollution↗
PubMed2001

Solid-state coordination chemistry: structural influences of copper-phenanthroline subunits on oxovanadium organophosphonate phases. hydrothermal synthesis and structural characterization of the two-dimensional materials [Cu(phen)(VO)(O3PCH2PO3)(H2O)], [[Cu(phen)]2(V2O5)(O3PCH2CH2PO3)], and [[Cu(phen)]2(V3O5)(O3PCH2CH2CH2PO3)2(H2O)] and the three-dimensional phase [[Cu(phen)]2(V3O5)(O3PCH2PO3)2(H2O)].

The hydrothermal reactions of CuCl2*2H2O, Na3VO4, 1,10-phenanthroline, and the appropriate organodiphosphonate ligand yield [Cu(phen)(VO)(O3PCH2PO3)(H2O)] (1), [[Cu(phen)]2(V2O5)(O3PCH2CH2PO3)] (2), [[Cu(phen)]2(V3O5)(O3PCH2CH2CH2PO3)2 (H2O)] (3), and [[Cu(phen)]2(V3O5)(O3PCH2PO3)2(H2O)] (4). Compounds 1-3 exhibit two-dimensional structures. The structures exhibit distinct vanadium building blocks: square pyramidal, mononuclear V(IV) sites in 1, a binuclear unit of corner-sharing V(V) tetrahedra in 2, and a trinuclear unit of corner-sharing V(V) square pyramids and a V(IV) octahedron in 3. The network structures of 1 and 2 are constructed from one-dimensional oxovanadium-diphosphonate chains linked by Cu(II) square pyramids into two-dimensional layers. In contrast, compound 3 exhibits a two-dimensional oxovanadium-organodiphosphonate network, with Cu(II) sites decorating the surfaces. Compound 4 is unique in exhibiting a framework structure, which may be described as a three-dimensional oxovanadium-organodiphosphonate substructure with [Cu(phen)]2+ subunits covalently attached to the surface of channels running parallel to the a-axis. The magnetic properties of 1-4 are also correlated to the structural characteristics. The magnetic behavior of 2 is thus dominated by antiferromagnetic interactions. The magnetic behavior of 1 and 4 is consistent with the presence of two distinct paramagnetic metal ions, Cu(II) and V(IV). In contrast, 3 does not exhibit ferrimagnetic behavior, but rather weak antiferromagnetic coupling. Crystal data: 1, C13H10N2CuP2VO8, monoclinic P2(1)/c, a = 9.0656(5) A, b = 8.6584(5) A, c = 20.934(1) A, beta = 97.306(1) degrees, Z = 4; 2, C26H20N4Cu2P2V2O11, triclinic P1, a = 10.6096(5) A, b = 11.6951(5) A, c = 13.1796(6) A, alpha = 71.369(1) degrees, beta = 70.790(1) degrees, gamma = 80.738(1) degrees, Z = 2; 3, C30H28N4Cu2P4V3O18, triclinic P1, a = 9.4356(6) A, b = 10.6556(6) A, c = 11.0354(7) A, alpha = 118.187(1) degrees, beta = 91.416(1) degrees, gamma = 107.821(1) degrees, Z = 1; 4, C26H20N4Cu2P4V3O18, monoclinic, P2(1)/c a = 8.3947(3) A, b = 16.8401(7) A, c = 11.9144(5) A, beta = 93.903(1) degrees, Z = 2.

Journal Article↗
PubMed2001

A(3)Tt(5) phases Sr(3)Sn(5), Ba(3)Pb(5), and La(3)Sn(5). Structure and bonding in a series of isotypic metallic compounds with increased electron count and their comparison with the nominal zintl phase La(3)In(5).

A series of compounds that contain square pyramidal Tt(5) polyanions of tin and lead has been obtained in alkaline-earth or rare-earth metal-tetrel systems by direct fusion of the elements at 570 degrees C (Sr(3)Sn(5)), 1000 degrees C (Ba(3)Pb(5)), or 1300 degrees C (La(3)Sn(5)) followed by slow cooling or annealing. The crystal structures for all three have been refined in the Pu(3)Pd(5) structure type (orthorhombic, Cmcm, Z = 4) with cell dimensions of a = 10.644(2), 11.154(7), and 10.352(5) A, b = 8.588(1), 9.049(7), and 8.290(6) A, and c = 10.895(2), 11.370(5), and 10.652(5) A for Sr(3)Sn(5), Ba(3)Pb(5), and La(3)Sn(5), respectively. Square pyramidal clusters of the tetrel elements are weakly interlinked into chains via two types of longer intercluster interactions that are mediated by bridging cations and substantially influenced by cation size and the free electron count. The new compounds are all metallic (rho(295) approximately 10 (Sr(3)Sn(5)) to approximately 25 (La(3)Sn(5)) muOmega.cm), in agreement with simple valence considerations that predict two and five extra electrons per formula unit, respectively, beyond that necessary for closed-shell nido-Tt(5)(4)(-) anions. Extended Hückel tight-binding calculations on the new compounds as well as on La(3)In(5) reveal that bonding in the regions below and around the Fermi energies are dominated by general cation-anion interactions, that is, lattice covalency. Closed-shell bonding features for the classical Sn(5)(4)(-), In(5)(9)(-), etc. ions are also obvious but subsidiary to the heteroatomic interactions with the cations. The intercluster contacts are relatively unimportant in bonding.

Journal Article↗
PubMed2005

Solution-phase and solid-phase syntheses of enzyme inhibitor RK-682 and antibiotic agglomerins.

The enzyme inhibitor RK-682 (5R)-(+)-1 was prepared in solution and on a solid support from (2R)-glycerates in five steps and ca. 40% overall yield. Key steps were a ring-closing tandem addition-Wittig alkenation reaction of the respective protected or immobilized glycerates with the ylide Ph(3)PCCO and the 3-acylation of the tetronic acids thus obtained with palmitic acid. A similar route extended by a mesylation-elimination sequence led to antibiotic agglomerins A-C 2 featuring 3-acyl-5-methylidenetetronic acid structures.

4-Butyrolactone↗
PubMed2004

Core-shell-type resins for solid-phase peptide synthesis: comparison with gel-type resins in solid-phase photolytic cleavage reaction.

[reaction: see text] Novel core-shell-type resins with a rigid core and amino-functionalized flexible shell were prepared with 2,4,6-trichloro-1,3,5-triazine (CNC) and Jeffamine ED-600 starting from 1% cross-linked aminomethyl (AM) polystyrene resins. All of the amino groups were located outside the resin beads, and the loading capacity was 0.2-0.4 mmol/g. The amount of CNC treated was a determining factor in the properties of the final resins. The core-shell-type resins showed superior performances in terms of the initial loading of amino acid and the photocleavage reaction compared to the gel-type resins.

Catalysis↗
PubMedDate not supplied

One-pot glyco-affinity precipitation purification for enhanced proteomics: the flexible alignment of solution-phase capture/release and solid-phase separation.

A one-pot affinity precipitation purification of carbohydrate-binding protein was demonstrated by designing thermally responsive glyco-polypeptide polymers, which were synthesized by selective coupling of pendant carbohydrate groups to a recombinant elastin-like triblock protein copolymer (ELP). The thermally driven inverse transition temperature of the ELP-based triblock polymer is maintained upon incorporation of carbohydrate ligands, which was confirmed by differential scanning calorimetry and (1)H NMR spectroscopy experiments. As a test system, lactose derivatized ELP was used to selectively purify a galactose-specific binding lectin through simple temperature-triggered precipitation in a high level of efficiency. Potential opportunities might be provided for enhanced proteomic, cell isolation as well as pathogen detection applications.

Amino Acid Sequence↗
PubMed1988

A negative phase II trial methylene dimethane sulphonate in advanced ovarian cancer (Cancer Research Campaign Phase I/II Trials Committee).

Methylene dimethane sulphonate (MDMS), the first member of the homologous series of dimethane sulphonic acid esters, was administered to 19 patients with advanced epithelial ovarian cancer. All patients had received prior chemotherapy and in addition 3 had received prior radiotherapy. MDMS was given as an i.v. bolus injection at a dose of 125mg m-2 and repeated in a q35 day schedule. Ten patients received only one course, six two courses, two three courses and one four courses. The major toxicity was thrombocytopenia which was cumulative. Serious neutropenia did not occur and no infective episodes requiring i.v. antibiotics were seen. Seven patients experience hair loss and four nausea and vomiting. Sixteen patients were evaluable for response but no objective remissions were seen although three patients had stable disease lasting at least 8 weeks. MDMS is therefore not recommended for further trial in epithelial ovarian carcinoma.

Adult↗

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