objective: the purpose of the present study was to assess the microleakage of composite restorations with and without a cervical amalgam base and to compare the results of dif-ferent composites and bonding agents. materials and methods: one hundred and twenty mesio-occlusal (mo) and disto-occlusal (do) class ii cavities were prepared on sixty extracted permanent premolar teeth. the teeth were r...

The purpose of this study was to evaluate the antibacterial activity of a modified self-etching primer incorporating chitosan and whether this modification affected the bond strength to radicular dentin. A modified self-etching primer was prepared by adding chitosan solutions at 0.03%, 0.06%, 0.12% and 0.25% (W/W) to RealSeal selfe-tching primer. RealSeal primer without chitosan was used as the...

Synergistic enhancement of the extraction of lanthanoid(III) (Ln) with 2-thenoyltrifluoroacetone (Htta) in benzene has been found by the addition of tris(4-isopropyltropolonato)cobalt(III) (Co(ipt)3). The synergistic effect of Co(ipt)3 was ascribed to the formation of a 1:1 adduct of Ln(tta)3 with Co(ipt)3, i.e., a binuclear complex, in the organic phase. The adduct formation constant (beta s,1...

2 Different Types of Bonds 7 2.1 Covalent Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.2 Ionic Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.2.1 Madelung Sums . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.3 Metallic Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.4 Van der Waals Bonds . . . . . . . . . . . ....

Two-dimensional (2D) halide perovskites are emerging as promising candidates for nanoelectronics and optoelectronics. To realize their full potential, it is important to understand the role of those defects that can strongly impact material properties. In contrast to other popular 2D semiconductors (e.g., transition metal dichalcogenides MX2) for which defects typically induce harmful traps, we...

Presently, resin composites are indispensable for dental restorative treatment because of their favorable esthetic and mechanical properties. In particular, the adhesion of resin composites to dentin has been rapidly improved by progress resin adhesive systems. Of late, resin restorative procedures have been simplified with the development of adhesive systems with fewer processing steps. One of...

The [3 + 2] cycloaddition (32CA) reaction between nitrones and ketenes has been studied within the Molecular Electron Density Theory (MEDT) at the Density Functional Theory (DFT) MPWB1K/6-311G(d,p) computational level. Analysis of the conceptual DFT reactivity indices allows the explanation of the reactivity, and the chemo- and regioselectivity experimentally observed. The particular mechanism ...

The Schiff base ligand in the title compound, [Sn(C(4)H(9))(2)(C(11)H(12)ClNO(4))], chelates to the Sn atom through the two deprotonated O atoms, as well as through the N atom, to confer an overall cis-C(2)SnNO(2) trigonal-bipyramidal geometry at tin [C-Sn-C = 130.3 (1)°]. The hydr-oxy groups engage in O-H⋯O hydrogen bonding with the O atoms of adjacent mol-ecules, generating a chain running al...

In the crystal structure of the title compound, [Co(C(2)H(4)NO(2))(C(9)H(6)NO)(2)]·CH(3)OH, the Co(III) atom is chelated by two quinolin-8-olate and one glycinate anions in a distorted octa-hedral coordination geometry. The five-membered chelating glycinate ring assumes an envelope conformation. The complex mol-ecules are assembled by inter-molecular N-H⋯O hydrogen bonding.