Experimental Adhesives with Different Hydrophilicity: Microshear Test in after 1, 7, and 90 Days' Storage

Purpose: To assess the microshear bond strength of 3 experimental adhesives with different degrees of hydrophilicity after 1, 7 and 90 days of storage. Materials and Methods: The bonding effectiveness of three experimental two-step etch-and-rinse adhesives (bis-GMA, bis-EMA/bis-GMA, polybutadiene [C6H12]) and one commercial adhesive (Single Bond) to sound hydrated dentin was determined using the nnicroshear test with delimitation of the adhesive area after 1, 7, and 90 days of storage in water at 37 degrees C. Two-way ANOVA was performed at the 0.05 probability level. The fractures were classified as adhesive, cohesive in dentin, cohesive in resin, and mixed. Results: The experimental adhesives showed values in the range of 11.31 to 12.96 MPa, with polybutadiene (PBH) showing the lowest bond strengths, bis-GMA the highest, and bis-EMA/bis-GMA intermediary values. Single Bond yielded bond strengths of approximately 24 MPa. Water storage decreased the bond strength in all adhesives. Adhesive fractures were predominant in experimental adhesives, while mixed fractures were the most frequent type in the Single Bond group. Conclusion: The experimental dentin adhesives of this study were able to form resin tags, but they could not penetrate into the collagen fibers and form hybrid layers. The resulting low bond strength decreased with increasing length of storage.

Direct ethanol fuel cell: Electrochemical performance at 90 degrees C on Pt and PtSn/C electrocatalysts

Carbon-supported Pt-based electrocatalysts were synthesized by Pechini method for the ethanol oxidation (EOR). Physicochemical characterizations were helpful to estimate the diameters of the obtained materials ranging from 2 nm to 5 nm. Main electrochemical experiments were carried out at 90 degrees C i.e. under the working conditions of performing the single 5 cm(2) direct ethanol fuel cell (DEFC). Pt(80)Sn(20)/C was the anode catalyst which has given the highest power density of 37 mW cm(-2). Importantly, the IR spectroscopy measurements associated with the qualitative analysis done at the output of the anodic compartment of the fuel cell have shown that ethanol oxidation on Pt(80)Sn(20)/C was mainly a two-electron sustainable process. (C) 2011 Elsevier B.V. All rights reserved.

Form III-like conformation and Form I-like packing in a chloroform channel solvate of the diuretic drug chlortalidone

Chlortalidone (CTD) is an antihypertensive drug for which only two solid state phases have been structurally elucidated thus far. Here, we have prepared a chloroform solvate thereof, namely, CTD Form IV, and its structure was compared to those of Form I and Form III. Its two conformers exhibit a dual structural feature in relation to the antecedent polymorphs. Both CTD molecules of Form IV adopt a Form III-like conformation, which is featured, if the conformation of CTD Form I is used as a reference, by a rotation of about 90 degrees on the axis of the C-C bond bridging the substituted benzene and isoindolinyl rings. However, CTD Form IV assembles as in the Form I crystal packing despite the different stacking fashion of their centrosymmetric dimers. In contrast to Form I, there is no offset stacking in Form IV, which forces a bend of ca. 24 degrees between the planes passing through the isoindolinyl moieties of two [100]-stacked dimers. Chloroform molecules at a maximum stoichiometry of 0.25 mol per mol of the drug play a stabilizing role in the assembly of Form IV by filling the channels formed on the crystals.