OBJECTIVE To evaluate the influence of saliva contamination on the bond strength of metallic brackets bonded to enamel with hydrophilic resin composite. METHODS Eighty premolars were randomly divided into 4 groups (n = 20) according to bonding material and contamination: G1) bonded with Transbond XT with no saliva contamination, G2) bonded with Transbond XT with saliva contamination, G3) bond...

A redetermination of the crystal structure of the title compound, C(6)H(16)N(2) (2+)·2Cl(-), was undertaken. All atomic coordinates including those of the H atoms were refined freely. The cation is located on a centre of symmetry. Important for the crystal structure are wavy hydrogen-bonded layers that are formed by ammonium groups and chloride anions, giving hydrogen-bonded rings.

In the title complex, [Ir(C11H8N)2(C6H5N2O)], the octa-hedrally coordinated Ir(III) atom is bonded to two 2-(pyridin-2-yl)phenyl ligands, through two phenyl C and two pydidine N atoms, and to one pyridine-2-aldoxime ligand through a pyridine N and an oxime N atom. The oxime O atom of the aldoxime unit forms inter-molecular C-H⋯O hydrogen bonds, which result in a two-dimensional hydrogen-bonded ...

The title compound, C(16)H(16)N(2)O(4)·2CH(3)OH, is a hydrazone in an E geometric arrangement, with an inversion centre at the mid-point of the N-N bond. A symmetry-related pair of six-membered hydrogen-bonded rings [graph-set motif S(1) (1)(6)] are present for the terminal vanillin-imine moieties. Two lattice methanol solvent mol-ecules are present per formula unit (Z' = 1/2), which form hydro...

The structure of ethyl 2-amino-4-tert-butyl-1,3-thiazole-5carboxylate, C10H16N2O2S, (I), and the structure of the 1:1 adduct 6-methylimidazo[2,1-b]thiazole±2-amino-1,3-thiazole (1/1), C6H6N2S C3H4N2S, (II), have been determined. The molecules in (I) associate via a hydrogen-bonded R2(8) dimer consisting of NÐH N interactions, with the hydrogenbonding array additionally involving NÐH O interacti...

In the triple helical structure of collagen proposed by RAMACHANDRAN and co-workers1, 2 (see ref. 2 for earlier references), there are two N H . . . 0 hydrogen bonds for every three residues in each chain. In the modification of the RAMACHANDRANKARTHA structure proposed by RICI~ A N D C R I C K a, the three chains are pushed slightly farther apart from their positions in this two-bonded structu...