RESUMEN
The discovery of a new FeII oxalate framework of composition K2Fe[(C2O4)2(H2O)2]·0.18H2O is reported. Its crystal structure was solved by means of single crystal and powder X-ray diffraction. The new organic-inorganic hybrid compound crystallizes in the orthorhombic space group Pca21 with unit-cell parameters: a = 12.0351 (4)â Å, b = 15.1265 (5)â Å, c = 10.5562 (4)â Å. This crystal structure, containing eight chemical formula, consists of a succession of FeO4(H2O)2 octahedra and K+ cations growing along b direction. Magnetization measurements indicate that the title compound is paramagnetic over the investigated temperature range (2-300â K). Both magnetization and 57Fe Mössbauer data indicate that Fe2+ is in a high-spin state.
RESUMEN
INTRODUCTION: Does the new adhesive-coated APC™ Flash-Free bracket from the 3M Unitek® group simplify the bonding protocol without compromising precision? OBJECTIVES: The aim of this study was to compare the morphology of the adhesive joint between the classic APC™ PLUS adhesive-coated brackets and APC™ Flash-Free brackets. MATERIALS AND METHODS: In vitro bonding of esthetic brackets in the CLARITY™ ADVANCED range was performed to compare the morphology of the excess flash between APC™ PLUS and APC™ Flash-Free brackets. RESULTS: No statistically significant difference was found concerning the morphology of the excess flash between APC™ PLUS and APC™ Flash-Free brackets. A statistically significant difference was found regarding the thickness of the adhesive between the two types of bracket. The adhesive used for the APC™ Flash-Free brackets was significantly thicker than for the APC™ PLUS brackets (P=0.0001). Adhesive thickness was also more homogeneous on the APC™ Flash-Free brackets (P=0.001 for the relative difference). CONCLUSION: The adhesive is thicker but adhesive homogeneity is greater with APC™ Flash-Free brackets than with APC™ PLUS brackets.
