Szegö quadrature formulas for certain Jacobi-type weight functions

In this paper we are concerned with the estimation of integrals on the unit circle of the form by means of the so-called Szegö quadrature formulas, i.e., formulas of the type with distinct nodes on the unit circle, exactly integrating Laurent polynomials in subspaces of dimension as high as possible. When considering certain weight functions related to the Jacobi functions for the interval nodes and weights in Szegö quadrature formulas are explicitly deduced. Illustrative numerical examples are also given.

     

Dielectric relaxation studies of some linear crosslinked and branched polymers

Dielectric loss measurements are reported for polystyrene, crosslinked polystyrene, polyacrylamide, branched polyacrylamide, and poly(methyl methacrylate) at 1 and 10 kHz f over the temperature range ?85 to +100°C. Crosslinking and branching have a pronounced effect on the dielectric relaxation spectra of polymers. The methods of preparation of these polymers and their viscosity molecular weight data are also reported.     

Synthesis and antimicrobial activity evaluation of new dithiocarbamate derivatives bearing thiazole/benzothiazole rings

The synthesis of 2-(substituted phenyl)-2-oxoethyl 4-(pyrimidin-2-yl)piperazin-1-carbodithiodate (A1-A24) derivatives and 2-(4-substituted thiazol-2-ylamino)-2-oxoethyl 4-(pyrimidin-2-yl)piperazin-1-carbodithiodate (B1-B14) derivatives was undertaken starting from the potassium salt of 4-(2-pyrimidinyl)piperazine dithiocarbamate. The structures of the obtained compounds were elucidated by ¹H NMR, ¹³C NMR, MS spectral data, and elemental analysis. The antimicrobial activity of the thirty eight newly synthesized compounds were tested against 12 microorganism strains using the microdilution technique. Compounds 2-(4-ethoxycarbonylthiazol-2-ylamino)-2-oxoethyl 4-(pyrimidin-2-yl)piperazin-1-carbodithiodate (B12), 2-(3-fluorophenyl)-2-oxoethyl 4-(pyrimidin-2-yl)piperazin-1-carbodithiodate (A18) and 2-(3,4-difluorophenyl)-2-oxoethyl 4-(pyrimidin-2-yl)piperazin-1-carbodithiodate (A21) were determined to possess high antimicrobial activity.     

Sonochemical synthesis of a new nano-scale 1D copper organic coordination polymer; thermal and spectroscopic characterizations

Single crystal of a new one-dimensional copper organic coordination polymer, 1D-CuOCP, [Cu(HL)NO₃]_n (1) Miyasaka, H., Saitoh, A., Abe, S. (2007) Coord. Chem. Rev., 251(21): 2622–2664.[Crossref], [Web of Science ®] , [Google Scholar] (H₂L = [2-[1-(2-hydroxy-propylimino)-ethyl]-phenol]) and its nanostructure, have been synthesized by slow evaporation of methanol solution of compound (1) Miyasaka, H., Saitoh, A., Abe, S. (2007) Coord. Chem. Rev., 251(21): 2622–2664.[Crossref], [Web of Science ®] , [Google Scholar] and sonochemical process respectively. Nanostructure of the complex was characterized by X-ray powder diffraction (XRD), FT-IR spectroscopy and scanning electron microscopy (SEM) and the structure of compound 1 was determined by single-crystal X-ray diffraction. Thermal stability of compound 1 in its nanosize form has also been studied by thermal gravimetric analysis (TGA). The effect of concentration of initial reagents on size and morphology of nanostructured compound 1 has been examined. The brightness of this study is to use the nanostructure of 1D-CuOCP as precursor to prepare single phase CuO nanoparticles via a solid-state decomposition procedure. Characterization methods confirmed that CuO nanoparticles with an average diameter of 40 nm were obtained from direct calcination of the precursor at 500°C under air.     

Phosphorus–nitrogen compounds part 33: in vitro cytotoxic and antimicrobial activities,DNA interactions,syntheses, and structural investigations of new mono(4-nitrobenzyl)spirocyclotriphosphazenes

The condensation reactions of hexachlorocyclotriphosphazene, N₃P₃Cl₆, with N-alkyl-N′-mono(4-nitrobenzyl)diamines (1–3), NO₂PhCH₂NH(CH₂) _n NHR₁ (R₁ = CH₃ or C₂H₅), led to the formation of the mono(4-nitrobenzyl)spirocyclotriphosphazenes (4–6). The tetra-pyrrolidino (4a–6a), piperidino (4b–6b), and 1,4-dioxa-8-azaspiro[4,5]decaphosphazenes (4c–6c) were prepared from(for) the reactions of partly substituted compounds (4, 5, and 6) with excess pyrrolidine, piperidine, and 1,4-dioxa-8-azaspiro[4,5]decane (DASD), respectively. The partly substituted geminal (4d and 5d) and cis-morpholino (6d) phosphazenes were isolated from the reactions of excess morpholine in boiling THF and o-xylene, but the expected fully substituted compounds were not obtained. The structures of all the phosphazene derivatives were determined by elemental analyses, MS, FTIR, ¹H, ¹³C{¹H}, ³¹P{¹H} NMR, HSQC, and HMBC techniques. The crystal structures of 4, 6, 4a, and 5a were verified by X-ray diffraction analysis. In addition, in vitro cytotoxic activities of fully substituted phosphazenes (4a–6c) against HeLa cervical cancer cell lines (ATCC CCL-2) and the compounds 4a and 4c against breast cancer cell lines (MDA-MB-231) and L929 fibroblast cells were evaluated, respectively. Apoptosis effect was determined by MDA-MB-231 cancer cell lines and fibroblast cells. The MIC values of the compounds were in the ranges of 9.8–19.5 µM. The compounds 6, 5a, 6a, 5b, and 6d have greater MIC activity against bacterial and yeast strain. The investigation of DNA binding with the phosphazenes was studied using plasmid DNA. The phosphazene derivatives inhibit the restriction endonuclease cleavage of plasmid DNA by BamHI and HindIII enzymes. BamHI and HindIII digestion results demonstrate that the compounds bind with G/G and A/A nucleotides.     

Scandium trifluoromethanesulfonate as a recyclable catalyst for efficient methoxymethylation of alcohols

Scandium triflate [Sc(OTf)₃] has been found to be a recyclable catalyst for mild highly efficient methoxymethylation of a variety of alcohols using formaldehyde dimethyl acetal (FDMA).     

Binding of serotonin to the human serotonin transporter. Molecular modeling and experimental validation

Molecular modeling and structure-activity relationship studies were performed to propose a model for binding of the neurotransmitter serotonin (5-HT) to the human serotonin transporter (hSERT). Homology models were constructed using the crystal structure of a bacterial homologue, the leucine transporter from Aquifex aeolicus, as the template and three slightly different sequence alignments. Induced fit docking of 5-HT into hSERT homology models resulted in two different binding modes. Both show a salt bridge between Asp98 and the charged primary amine of 5-HT, and both have the 5-HT C6 position of the indole ring pointing toward Ala173. The difference between the two orientations of 5-HT is an enantiofacial discrimination of the indole ring, resulting in the 5-hydroxyl group of 5-HT being vicinal to either Ser438/Thr439 or Ala169/Ile172/Ala173. To assess the binding experimentally, binding affinities for 5-HT and 17 analogues toward wild type and 13 single point mutants of hSERT were measured using an approach termed paired mutant-ligand analogue complementation (PaMLAC). The proposed ligand-protein interaction was systematically examined by disrupting it through site-directed mutagenesis and re-establishing another interaction via a ligand analogue matching the mutated residue, thereby minimizing the risk of identifying indirect effects. The interactions between Asp98 and the primary amine of 5-HT and the interaction between the C6-position of 5-HT and hSERT position 173 was confirmed using PaMLAC. The measured binding affinities of various mutants and 5-HT analogues allowed for a distinction between the two proposed binding modes of 5-HT and biochemically support the model for 5-HT binding in hSERT where the 5-hydroxyl group is in close proximity to Thr439.     

Unoccupied electronic states in graphite oxides

Unoccupied electronic states of graphite oxides with different oxidation times have been investigated using X-ray absorption spectroscopy (XAS) in total electron yield (TEY) and total fluorescence yield (TFY) modes. The graphite oxides exhibit graphite-like sp² states with additional electronic states originating from functional groups. The intensity of the π^* state decreases as the atomic ratio O:C increases. The intensity ratio of carboxyl to π^* states in XAS TEY mode corresponds to the area ratio of carboxyl to sp² carbon in X-ray photoelectron spectroscopy. In addition, the two modes in XAS can identify electronic states of functional groups originating from surface or bulk regions.     

Spectroscopic and crystal structure analysis of diamminebis(2,4,6‐triiodophenolato‐O) copper(II)

The crystal structure of [Cu(C₆H₂I₃O)₂(NH₃)₂] (CCDC 238896) has been determined by x‐ray diffraction. This monomeric centrosymmetric Cu(II) complex crystallizes in the monoclinic system. The CuO₂N₂ coordination sphere is trans ‐planar, [Cu–O: 1.943(5) Å and Cu‐N: 1.972(7)] with the fifth and sixth coordination sites occupied by I atoms from the phenoxide ions [Cu–I₁: 3.3552(8) Å] to form a tetragonally elongated octahedral structure for CuO₂N₂I₂ coordination. The complex molecules hold together in a one dimensional chain true [100] direction by intermolecular hydrogen bonds. Differantial scanning calorimeter, FTIR and magnetic susceptibility measurements were also performed in order to identify the title complex. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Evaluation of the Antioxidant and Antiradical Properties of Some Phyto and Mammalian Lignans

In this study, the antioxidant and antiradical properties of some phyto lignans (nordihydroguaiaretic acid, secoisolariciresinol, secoisolariciresinol diglycoside, and α-(-)-conidendrin) and mammalian lignans (enterodiol and enterolactone) were examined by different antioxidant assays. For this purpose, radical scavenging activities of phyto and mammalian lignans were realized by 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) radical (ABTS^•+) scavenging assay and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging assay. Additionally, the reducing ability of phyto and mammalian lignans were evaluated by cupric ions (Cu²⁺) reducing (CUPRAC) ability, and ferric ions (Fe³⁺) and [Fe³⁺-(TPTZ)2]³⁺ complex reducing (FRAP) abilities. Also, half maximal inhibitory concentration (IC₅₀) values were determined and reported for DPPH^• and ABTS^•+ scavenging influences of all of the lignan molecules. The absorbances of the lignans were found in the range of 0.150–2.320 for Fe³⁺ reducing, in the range of 0.040–2.090 for Cu²⁺ reducing, and in the range of 0.360–1.810 for the FRAP assay. On the other hand, the IC₅₀ values of phyto and mammalian lignans were determined in the ranges of 6.601–932.167 µg/mL for DPPH^• scavenging and 13.007–27.829 µg/mL for ABTS^•+ scavenging. In all of the used bioanalytical methods, phyto lignans, as secondary metabolites in plants, demonstrated considerably higher antioxidant activity compared to that of mammalian lignans. In addition, it was observed that enterodiol and enterolactone exhibited relatively weaker antioxidant activities when compared to phyto lignans or standard antioxidants, including butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), Trolox, and α-tocopherol.