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Poly (methyl methacrylate) (PMMA), is an acrylic polymer substance that is mostly used for denture base applications. The purpose of this laboratory study was to investigate the effect of adding 0.05 wt.% Ag-doped carbon nanotubes (CNT) to PMMA-based (PMMA and MMA) denture base material on the impact strength, microhardness, and antimicrobial activity. A total of 60 heat-cured acrylic resin specimens were prepared. The specimens were randomly divided into two main groups (n = 30/group), according to the powder used: (a) control group, using heat-cured PMMA; (b) treatment group, using a powder prepared by blending 0.05 wt.% silver-doped CNT nanoparticles with heat-cured PMMA. The impact strength, microhardness and anticandidal activity for each group were assessed via the Charpy, Vickers and agar diffusion tests, respectively (n = 10/test for each subgroup). Data were analyzed using independent-sample t-tests (p ≤ 0.05). The results of the impact strength test revealed that the treated heat-cured PMMA-MMA with Ag-doped CNT (2.2 kJ/mm2) was significantly higher than that of the control heat-cured PMMA (1.6 kJ/mm2). Similarly, the Vickers microhardness of the treatment group (52.7 VHN) was significantly higher than that of the control group (19.4 VHN). Regarding the agar diffusion test, after 24 h of incubation, the treated heat-cured PMMA with the Ag-doped CNT exhibited significantly higher anticandidal activity than that of the control group. Therefore, Ag-doped carbon nanotubes could be considered as promising fillers for the dental heat-cured acrylic resin to improve the resistance of the resultant denture against sudden fractures, scratching, and candida invasion. [ABSTRACT FROM AUTHOR]

The charge-transfer (CT) interactions between the electron donor sulfasalazine (SS) and the acceptors 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), p-chloranil (CHL), picric acid (PA) and iodine have been studied spectrophotometrically in CHCl or CHOH solutions. The formed solid CT complexes were also isolated and characterized through infrared, H-NMR, mass spectra as well as elemental and thermal analysis. The CT complexes were discussed in terms of formation constant (K), molar extinction coefficient (ε), standard free energy (ΔG°), oscillator strength ( f), transition dipole moment (µ), resonance energy (R) and ionization potential (I). The stoichiometry of these complexes was found to be 1:1 molar ratio and having the formulae [(SS)(DDQ)], [(SS)(CHL)], [(SS)(PA)] and [(SS)I]· I, respectively. The charge transfer interaction was successfully applied to the determination of SS drug using mentioned σ and π-acceptors also, the results obtained herein are satisfactory for estimation of SS compound in the pharmaceutical form. Copyright © 2010 John Wiley & Sons, Ltd. The charge-transfer (CT) interactions between the electron donor sulfasalazine (SS) and the acceptors 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), p-chloranil (CHL), picric acid (PA) and iodine have been studied spectrophotometrically in CHCl or CHOH solutions. The formed solid charge-transfer complexes were also isolated and characterized through infrared, H-NMR, mass spectra as well as elemental and thermal analysis. The CT complexes were discussed in terms of formation constant (K), molar extinction coefficient (ε), standard free energy (ΔG°), oscillator strength ( f), transition dipole moment (µ), resonance energy (R) and ionization potential (I). The stoichiometry of these complexes was found to be 1:1 molar ratio and having the formulae [(SS)(DDQ)], [(SS)(CHL)], [(SS)(PA)] and [(SS)I]· I, respectively. The charge transfer interaction was successfully applied to the determination of SS drug using mentioned σ and π-acceptors also, the results obtained herein are satisfactory for estimation of SS compound in the pharmaceutical form. [ABSTRACT FROM AUTHOR]

Abstract: A convenient method for the preparation of complexes of the Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Zn2+, ZrO2+, UO2 2+, Zr4+ and Th4+ ions with caproic acid (Hcap) is reported and this has enabled 10 complexes of caproate anion to be formulated: [Cr(cap)3]·5H2O, [Mn(cap)2(H2O)2], [Fe(cap)3]·12H2O, [Co(cap)2(H2O)2]·4H2O, [Ni(cap)2(H2O)2]·3H2O, [Zn(cap)2], [ZrO(cap)2]·3H2O, [UO2(cap)(NO3)], [Zr(cap)2(Cl)2] and [Th(cap)4]. These new complexes were synthesized and characterized by elemental analysis, molar conductivity, magnetic measurements, spectral methods (mid infrared, 1H NMR and UV–vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. It has been found from the elemental analysis as well as thermal studies that the caproate ligand behaves as bidentate ligand and forming chelates with 1:1 (metal:ligand) stoichiometry for UO2 2+, 1:2 for (Mn2+, Co2+, Ni2+, Zn2+, ZrO2+ and Zr4+), 1:3 stoichiometry for (Cr3+ and Fe3+) and 1:4 for Th4+ caproate complexes, respectively, as bidentate chelating. The molar conductance measurements proved that the caproate complexes are non-electrolytes. The kinetic thermodynamic parameters such as: E*, ΔH*, ΔS* and ΔG* are estimated from the DTG curves. The antibacterial activity of the caproic acid and their complexes was evaluated against some gram positive/negative bacteria. [Copyright &y& Elsevier]