A method is described to obtain multicollision dissociation threshold (MCDT) values. These values provide relative reaction thresholds for dissociation in the three major gas-phase fragmentation reactions of oligosaccharides complexed to alkali metal ions. The quasimolecular ions are produced using matrix-assisted laser desorption/ionization Fourier transform mass spectrometry. The MCDTs for al...

Misfolding and aggregation of Cu, Zn superoxide dismutase (SOD1) is implicated in neuronal death in amyotrophic lateral sclerosis. Each SOD1 monomer binds to 1 copper and 1 zinc ion and maintains its disulfide bond (Cys-57-Cys-146) in the reducing cytoplasm of cell. Mounting experimental evidence suggests that metal loss and/or disulfide reduction are important for initiating misfolding and agg...

Objective: To evaluate the effect of different metal primers and surface treatment methods on the bond strength of 2 resin cements to yttrium-stabilized tetragonal zirconia (Y-TZP) ceramic material. Methods: 240 cylindrical dentin specimens were cut from extracted human third molars. The same number of zirconia ceramic (Cercon) plates were made and assigned to 24 groups based on combinations of...

A general method for synthesizing a novel class of metalloporphyrin dimers containing unbridged metal-metal bonds is presented. By choosing the appropriate metal, the bond order in these dimers can be varied systematically. The synthesis and characterization of osmium(II) and molybdenum(II) porphyrin dimers containing the respective metal-metal double and quadruple bonds are described. A simple...

in this work, we report results of calculations based on the density functional theory of different species metal-ozone, containing mercury, silver and gold. the chosen species range from small molecules and large transition-metal containing ozone with mercury, silver and gold complexes. a comparative analysis of the description of the metal-oxygen bond obtained by different methodologies is pr...

Bond paths and the bond critical point properties (the electron density (rho) and the Hessian of rho at the bond critical points (bcp's)) have been calculated for the bonded interactions comprising the nickel sulfide minerals millerite, NiS, vaesite, NiS(2), and heazlewoodite, Ni(3)S(2), and Ni metal. The experimental Ni-S bond lengths decrease linearly as the magnitudes of the properties each ...

___Electron transfer is fundamental to chemical reactivity. A prototype example in organometallic chemistry is the attack of an anionic metal center on a metal–metal bond, M + M’–M’, which, by nucleophilic substitution, should lead to M–M’ + M’. Such is not cleanly found, however, the outcome of this mechanistically complex transformation usually being controlled by thermodynamic factors throug...

OBJECTIVES The purpose of this study was to evaluate the effect of hot pressing on the shear bond strength of a Au-Pt-Pd alloy-porcelain composite. METHODS Several metal-porcelain composites specimens were produced by two different routes: conventional porcelain fused to metal (PFM) and hot pressing. In the latter case, porcelain was hot pressed onto a polished surface (PPPS) as well as a rou...

The electronic structure for a representative late-transition-metal-methylene complex, Ru=€H2+, has been studied by ab initio methods (generalized valence bond/configuration interaction). The electronic-state spectrum reveals five states close in energy (spread of 12.9 kcal/mol) that partition into two groups in terms of energy separation and mode of metal-carbon bonding. The ground state has *...

BACKGROUND Recasting the base metal alloys is done as a routine procedure in the dental laboratories whenever there is casting failure or to decrease the unit cost of a fixed partial denture. However, this procedure may affect the metal ceramic bond. Furthermore, it is unclear, as to which test closely predicts the bond strength of metal-ceramic interface. The aim was to compare the bond streng...