Homogeneous electron transfer reactions of the Cu(II) complexes of 5,10,15,20-tetraphenylporphyrin (TPP) and 2,3,7,8,12,13,17,18-octaethylporphyrin (OEP) with various oxidizing reagents were spectrophotometrically investigated in acetonitrile. The reaction products were confirmed to be the pi-cation radicals of the corresponding Cu(II)-porphyrin complexes on the basis of the electronic spectra and the redox potentials of the complexes. The rate of the electron transfer reaction between the Cu(II)-porphyrin complex and solvated Cu(2+) was determined as a function of the water concentration under the pseudo first-order conditions where Cu(2+) is in large excess over the Cu(II)-porphyrin complex. The decrease in the pseudo first-order rate constant with increasing the water concentration was attributed to the stepwise displacement of acetonitrile in [Cu(AN)(6)](2+)(AN = acetonitrile) by water, and it was concluded that only the Cu(2+) species fully solvated by acetonitrile, [Cu(AN)(6)](2+), possesses sufficiently high redox potential for the oxidation of Cu(ii)-OEP and Cu(ii)-TPP. The reactions of the Cu(II)-porphyrin complexes with other oxidizing reagents such as [Ni(tacn)(2)](3+)(tacn = 1,4,7-triazacyclononane) and [Ru(bpy)(3)](3+)(bpy = 2,2'-bipyridine) were too fast to be followed by a conventional stopped-flow technique. Marcus cross relation for the outer-sphere electron transfer reaction was used to estimate the rate constants of the electron self-exchange reaction between Cu(II)-porphyrin and its pi-cation radical: log(k/M(-1) s(-1))= 9.5 +/- 0.5 for TPP and log(k/M(-1) s(-1))= 11.1 +/- 0.5 for OEP at 25.0 degrees C. Such large electron self-exchange rate constants are typical for the porphyrin-centered redox reactions for which very small inner- and outer-sphere reorganization energies are required.

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Abstract:Imprint culture from patients with denture stomatitis is a common method used to examine the relationship between localization of yeast colonies to inflammed mucosa area. However, this technique consists of problems such as;1 . negative effect on the growth of Candida due to the temperature of the agar. 2. the need of having to box the denture base. 3. difficultly of applying this technique to partial dentures. Therefore, a modified imprint culture technique was developed to improve these problem. The ability to detect Candida by the modified imprint culture technique was examined in regards to temperature of the agar. Results showed that this technique did not have such an important effect on the growth of Candida.Thus, the modified imprint culture technique was found to have many advantages such as: 1. No influence by the temperature of the agar on the growth of Candida. 2. Easy application of this technique to partial dentures. 3. Easy aseptic handling. 4. No need of a boxing process on a denture base. 5. No reinforcements of the agar. 6. A shortened length in handling time.

Abstract:This investigation dealt with objectively estimating