Interpenetrating Coordination Polymers from CuI or AgI and Flexible Ligands: 2D Polyrotaxanes and Interpenetrating Grids

The reaction of [Cu(CH₃CN)₄]NO₃ or AgNO₃ with flexible ligands 1,4‐bis(4‐pyridylmethyl)‐2,3,5,6‐tetrafluorobenzene (bpf) or 4,4′‐bis(4‐pyridylmethyl)‐2,2′,3,3′,5,5′,6,6′‐octafluorobiphenyl (bpfb) afforded two types of interpenetrating coordination polymers. The structures of [Cu₂(bpf)₃(NO₃)₂]_n and [Ag₂(bpf)₃‐(NO₃)₂]_n are 2D polyrotaxane networks in which 1D polymeric chains are aligned in a grid. The structure of {[Cu(bpfb)₂]NO₃}_n is a 2D grid polymer with two‐fold parallel interpenetration.     

Oxygen-diffusion characteristics of loosely-sintered polycrystalline MgO

Self-diffusion coefficients of oxygen in well-sintered and in loosely-sintered polycrystalline MgO have been measured at an ambient oxygen pressure of about 35 mm Hg over the temperature range 1020–1450°C. The oxygen diffusion coefficient as a function of temperature of the former specimen is expressed by a single Arrhenius equation with an activation energy of 55.8 kcal/mole, while that of the latter is composed of two intersecting lines (E = 60.2 kcal/mole from 1020–1250°C; E = 102.8 kcal/mole from 1250–1450°C). The diffusivity for single-crystal grain of the well-sintered polycrystals is two orders of magnitude larger than that in the low-temperature portion of the loosely-sintered one. This fact is interpreted in terms of an insufficient dissolution of monovalent cation impurities into the loosely-sintered crystal lattice. Two ways of interpretation are given for the presence of the high-temperature portion characteristic of the loosely-sintered polycrystal.     

Enzymatic hydrolysis of alpha- and beta-oligo(L-aspartic acid)s by poly(aspartic acid) hydrolases-1 and 2 from Sphingomonas sp. KT-1

The enzymatic hydrolysis of alpha- and beta-oligo(L-aspartic acid)s by PAA hydrolase-1 and PAA hydrolase-2 (purified from Sphingomonas sp. KT-1) was performed to elucidate the mechanism of the microbial degradation by Sphingomonas sp. KT-1 of the thermally synthesized alpha,beta-poly(D,L-aspartic acid) (tPAA). GPC analysis of the hydrolyzed products of alpha- and beta-tetra(L-aspartic acid)s by PAA hydrolase-1 has showed that PAA hydrolase-1 is capable of hydrolyzing only the specific amide bonds between beta-aspartic acid units. The RP-HPLC analysis of the enzymatic hydrolysis of beta-oligo(L-aspartic acid)s (4 and 5 mers) by PAA hydrolase-1 has suggested that the enzymatic hydrolysis of beta-oligo(L-aspartic acid)s occurs via an endo-mode cleavage. In contrast, PAA hydrolase-2 hydrolyzed both alpha- and beta-oligo(L-aspartic acid)s via an exo-mode cleavage to yield L-aspartic acid as a final product. A kinetic study on the enzymatic hydrolysis of alpha-oligo(L-aspartic acid)s (3 to 7 mers) by PAA hydrolase-2 has indicated that Km values are almost independent of the number of monomer units in oligomers of 4 to 7 mers, while that Vmax values are markedly dependent on the chain length and show a maximum value at 5 mer.     

Tocopheryl Phosphate Inhibits Rheumatoid Arthritis-Related Gene Expression In Vitro and Ameliorates Arthritic Symptoms in Mice

Anti-rheumatoid arthritis (RA) effects of α-tocopherol (α-T) have been shown in human patients in a double-blind trial. However, the effects of α-T and its derivatives on fibroblast-like synoviocytes (FLS) during the pathogenesis of RA remain unclear. In the present study, we compared the expression levels of genes related to RA progression in FLS treated with α-T, succinic ester of α-T (TS), and phosphate ester of α-T (TP), as determined via RT-PCR. The mRNA levels of interleukin (IL)-6, tumor necrosis factor-α (TNF-α), matrix metalloproteinase (MMP)-3, and MMP-13 were reduced by treatment with TP without cytotoxicity, while α-T and TS did not show such effects. Furthermore, intraperitoneal injection of TP ameliorated the edema of the foot and joint and improved the arthritis score in laminarin-induced RA model mice. Therefore, TP exerted anti-RA effects through by inhibiting RA-related gene expression.     

Determination of the purity of acidimetric standards by constant-current coulometry, and the intercomparison between CRMs

The accuracy and uncertainty of the coulometric measurement results of reference materials for acidimetric titration were examined in this study. The results for amidosulfuric acid and potassium hydrogen phthalate are presented. The uncertainty was investigated by examining the dependency on the sample size and on the electrolysis current. Changes in the titration parameters did not result in any significant effects on the titration results. Acidimetric standards with the certified value linked to the SI were developed. In addition, the intercomparison of acidimetric standards was carried out by gravimetric titration, and the relationship between our coulometric results was determined. Furthermore, due to recent internationalization, not only the traceability to the SI but also the relationship and consistency of their analytical data have gained increasing importance. Our results were validated using certified reference materials (CRMs) obtained from different National Metrology Institutes (NMIs), and their relationships are presented. Presented at -- “BERM-10” -- April 2006, Charleston, SC, USA.     

Assessing the Quality of Burkina Faso Soybeans Based on Fatty Acid Composition and Pesticide Residue Contamination

Soybean is widely used in the food industry because of its high fatty acid and protein content. However, the increased use of pesticides to control pests during cultivation, in addition to being a public health concern, may influence the nutritional quality of soybeans. This study aimed to assess the nutritional quality of soybeans with respect to fatty acid profile and pesticide residue contamination. The levels of fatty acids and pesticides in soybean varieties G196 and G197 were determined by gas chromatography and by the QuEChERS method, respectively. The results showed a significant variation in the quantitative and qualitative fatty acid composition of the two varieties, with 18.03 g/100 g and 4 fatty acids detected for the G196 variety and 21.35 g/100 g and 7 fatty acids for the G197 variety, respectively. In addition, 12 active pesticide compounds were found, and among them, imazalil, quintozene, cyfluthrin and lindane exceeded their maximum limits. The G197 variety had a better nutritional profile compared to G196. The profile of fatty acids and the content of pesticide residues were used as important determinants for soybean utilization in human nutrition.