Multiconfigurational quantum chemical calculations on the R-diimines dichromium compound confirm that the Cr-Cr bond, 1.80 A, is among the shortest Cr(I)-Cr(I) bonds. However, the bond between the two Cr atoms is only a quadruple bond rather than a quintuple bond. The reason why the bond is so short has to be attributed to the strain in the NCCN ligand moieties.

We apply the theoretical formalism developed by us earlier @M. Vergeles and G. Szamel, J. Chem. Phys. 110, 6827 ~1999!# to study density, temperature, and bond-length dependence of the dynamic friction on a molecular bond. We show that the theory reproduces all the trends seen in molecular dynamics ~MD! simulations. The theoretical predictions agree reasonably well with the results of MD simula...

R.T. Downs Department of Geological Sciences, University of Arizona, Tucson, AZ 85721, USA Abstract The strength of a bond, defined as p=s/r, where s is the Pauling bond strength and r is the row number of an M cation bonded to an oxide anion, is related to a build-up of electron density along the MO bonds in a relatively large number of oxide and hydroxyacid molecules, three oxide minerals and...

background: the purpose of this study was to evaluate the effect of washing water temperature on the micro‑shear bond strength (μsbs) of composite resin to dentin using a two‑step etch‑and‑rinse system and a two‑step self‑etching system. materials and methods: in this in vitro study , the intact dentins of buccal and lingual surfaces of healthy third molars were exposed. dentin surfaces were ri...

The structure and energetics of the ring isomers of C(4n+2) (n=3-5) carbon clusters were studied by using coupled-cluster singles and doubles excitation theory to overcome the vast differences existing in the literature. The results obtained in the present study clearly indicate that C(14), C(18), and C(22) carbon rings have bond-length and bond-angle alternated acetylenic minimum energy struct...

direct composite resin restorations are widely used and the impact of different storage temperatures on composites is not well understood. the purpose of this study was to evaluate the microtensile bond strength of composite to dentin after different pre-curing temperatures.occlusal surfaces of 44 human molars were ground with diamond burs under water coolant and polished with 600 grit silicon ...

The relationship between the ORR catalytic activity of LaMnO 3+ δ and its Mn–O bond length was examined by replacing La with Sr, it found that shorter length, higher activity.

background: a few studies have investigated the effect of the activation mode of adhesive systems on bond strength of fi ber posts to root canal dentin. this study investigated the push-out bond strengths of a glass fi ber post to different root canal regions with the use of two adhesives with light- and dual-cure polymerization modes. materials and methods: in this in vitro study, 40 maxillary...