Zinc oxide-decorated multiwalled carbon nanotubes: a selective electrochemical sensor for the detection of Pb(II) ion in aqueous media

Journal of Materials Science: Materials in Electronics - Multiwalled carbon nanotubes, due to high conductivity, stability, and large specific surface area, have a potential ability to promote...     

Effect of substitutents on the composition and dissociation behaviour of some four component phenolic copolymers

Some random four component phenolic copolymers have been prepared by condensing formaldehyde with p-chlorophenol, p-aminophenol, p-toluidine, and p-cresol. The compositions of the copolymers have been determined by electrometric titration in a non-aqueous solvent, and halogen estimation. Several samples of the copolymers have been obtained by changing the feed composition. Composition of the copolymer has been correlated with the reactivity of the four monomeric units. Hyperacidity of some of the functional groups in the copolymer chain is interpreted in terms of intramolecular hydrogen bonding.     

Comparison of the combined cortical thickness of the second metacarpal with Sharp's method for scoring hand microradiographs in rheumatoid arthritis

OBJECTIVE: To compare the correlation and specificity of the combined cortical thickness of the second metacarpal (CCT-MC) with Sharp's method (SM) for scoring joint erosions and joint space narrowing in rheumatoid arthritis (RA) and to compare the degree of interobserver agreement between the 2 methods. METHODS: Hand microradiographs of 22 women with RA, functional classes III and IV, were scored independently by 3 rheumatologists using the CCT-MC and the CCT of the middle phalanx and SM. RESULTS: (1) There was a highly significant correlation between the total SM score and the CCT-MC for the 3 observers (r = 0.61, p = 0.0026), but not between the CCT of the middle phalanx and SM (r = 0.15, p = 0.53). There was a lower degree of agreement between the observers for SM erosion scores compared to the CCT-MC (intraclass correlation 0.88 for the CCT-MC and 0.63 for the SM); (2) Both joint space narrowing and erosion scores correlated highly with the CCT-MC (r = -0.60, p = 0.004; and r = -0.51, p = 0.014, respectively); (3) CCT-MC measurements are more closely related to the inner (d) as opposed to the outer (D) diameter of the 2nd metacarpal; (4) The mean time to obtain the CCT-MC score was 3.43 min (SD = 1.38) versus 9.83 min (SD = 3.20) for SM (p = 0.0001); (5) the derivative, (D2-d2)/D2, was significantly correlated with SM (r = -0.72, p = 0.0002) and its erosion and joint space narrowing components (r = -0.63, p = 0.0019; and r = -0.71, p = 0.0002, respectively). CONCLUSION: The CCT-MC is a rapid, practical method with higher agreement among observers compared to SM and correlates highly with SM scores for joint damage in RA. CCT-MC appears to have a higher degree of specificity than other sites for CCT measurement. The CCT-MC is more closely related to the inner diameter than the outer diameter, which supports the notion that the principal site of accelerated bone loss due to RA in the hand occurs at the endosteal surface. The CCT-MC should be further assessed with respect to monitoring radiological progression in RA.     

Dissociation behaviour of some mixtures of three component condensation polymers in non-aqueous media

Two three component condensation polymers have been prepared by reaction with formaldehyde from the following groups of monomeric units: (I) p-chlorophenol, p-cresol and p-aminophenol; (II) p-toluidine, p-bromoaniline and p-aminobenzoic acid. The relevant available data regarding the composition and degree of polymerization (DP) of the two copolymers have been used to characterize the samples. The two copolymers have been mixed in various stoichiometric proportions, and the amounts of acidic/basic functional groups expected to be present in a given weight of the mixture, have been calculated. Electrometric titration techniques in non-aqueous solvents have been used to determine the amount of acidic/basic functional groups present in the copolymer mixtures. An excellent correlation could be obtained between the observed and calculated values. The nature of the titration curves have been interpreted in terms of intramolecular hydrogen bonding, homoconjugation and ion-association in a medium of low dielectric constant.