Network structure of 0.7SiO(2)-0.3Na(2)O glass from neutron and x-ray diffraction and RMC modelling.

The structure of 0.7SiO(2)-0.3Na(2)O glass was investigated by means of neutron and high-energy x-ray diffraction. The maximum momentum transfer was 35 and 23.5 Å(-1) for the two experiments. The two datasets were modelled simultaneously by the reverse Monte Carlo simulation technique. By using reasonable constraints it was possible to separate the six partial pair correlation functions. Nearest neighbour distances, coordination numbers and bond angle distributions have been revealed. It was found that 63% of the O atoms are in the bridging position. The Na-O distance is 2.29 Å and the coordination number is 2.5. The Na-Na nearest neighbour distance is 2.6 Å, a value significantly smaller than previously reported. Neighbouring sodium ions tend to be located at the same oxygen atom. The average Si-O ring size is 7.6.

Neutron imaging of Zr-1%Nb fuel cladding material containing hydrogen.

Hydrogen distribution and hydride phases were analyzed in reactor fuel cladding pressure tube Zr-1%Nb material up to 13,300 ppm. From neutron diffraction measurements, formation of cubic delta-ZrH2 and a small amount of tetragonal gamma-ZrH was established. Texture effects were analyzed by imaging plate technique. From neutron radiography images a linear model was set up that adequately described the relationship between gray levels and nominal H-concentrations. The H-distribution was unveiled by 3D intensity histograms and fractal analysis of multilevel-segmented neutron radiography images.

Determination of the basicity of Mannich ketones by capillary electrophoresis.

Capillary electrophoretic (CE) method to characterise Mannich ketones (MKs) containing morpholine moiety was developed. Basicity (pKa,exp) of the MKs was characterised by measured data derived from the electrophoretic mobility values obtained in the CE separation. The MKs were found to be weaker bases than the parent morpholine molecule itself and the experimentally determined basicity values proved to be dependent on the chemical structure of the MKs. Since the basicity of the MKs has an influence on their reactivity and biological activity it seems to be useful to determine experimentally the pKa,exp values of the newly synthesised compounds to support rational drug design or screening of the molecule libraries.

Elevated levels of synovial fluid antibodies reactive with the small proteoglycans biglycan and decorin in patients with rheumatoid arthritis or other joint diseases.

OBJECTIVES: To determine whether patients with rheumatoid arthritis (RA) express humoral immunity to the small proteoglycans biglycan and decorin and to compare the response to that of patients suffering from other joint diseases. METHODS: Serum and synovial fluid IgG and IgM antibody levels were determined by enzyme-linked immunosorbent assay. Antibodies to biglycan and decorin as well as to other known and extensively investigated cartilage matrix components such as type II collagen, aggrecan and fibronectin were investigated. Patients suffering from RA, osteoarthritis (OA), psoriatic arthritis and other seronegative spondylarthropathies were included in the study. Correlation between antibody levels and clinical/laboratory parameters was determined. RESULTS: Patients with RA expressed an increased humoral immunity to biglycan, while patients with seronegative spondylarthropathies displayed elevated decorin-specific synovial antibody levels compared with OA patients. CONCLUSION: These results indicate a significantly higher immunity to small proteoglycans in RA and seronegative spondylarthropathies than in OA suggesting a possible involvement in the pathogenesis of inflammatory rheumatic diseases.