Information derived from a study of 'isolated' CH stretching frequencies, measured in partially deuterated organic and organemetallic compounds, is reviewed. This includes CH bond lengths . and dissociation energies, and HCH angles in methyl groups, Excellent agreement is found between CH bond length differences predicted from VCH's values and those calculated by ab initio methods. V'sCH data a...

A copper complex has proven to be a potent catalyst for forming a C-B bond via diborylation of arynes and alkynes, affording vic-diborylarenes and vic-diborylalkenes with high efficiency. A boryl-substituted organocopper species, which is intermediately generated in the diborylation, has been found to be captured by a tin or a carbon electrophile, leading to three-component borylstannylation or...

The molecular geometry of orotic acid was fully optimized using the gradient minimization technique. The computed geometrical parameters at the B3LYP/6-311G** level correspond well to those determined experimentally by X-ray diffraction. The relative stability of both the syn and anti conformations was investigated at the B3LYP/6-311G** level, where the syn-form was shown to be slightly more st...

The evolution of oxygenic photosynthesis in cyanobacteria nearly three billion years ago provided abundant reducing power and facilitated the elaboration of numerous oxygen-dependent reactions in our biosphere. Cyanobacteria contain an internal thylakoid membrane system, the site of photosynthesis, and a typical Gram-negative envelope membrane system. Like other organisms, the extracytoplasmic ...

This study was conducted to enhance the tensile bond strengths of resin cements to zirconia ceramics. Fifty-six zirconia ceramic specimens (Cercon Base) and twenty-eight silica-based ceramic specimens (GN-1, GN-1 Ceramic Block) were air-abraded using alumina. Thereafter, the zirconia ceramic specimens were divided into two subgroups of 28 each according to the surface pretreatment; no pretreatm...

We show that a simple noniterative tight-binding model can provide reliable estimates of energetics and geometries of molecules with C-C and C-H bonds. The mean absolute error in heats of formation, ∼4.6 kcal/mol, is essentially smaller than those found in previous tight-binding schemes. The internal consistency of the calculated heats of formation enables the reliable prediction of bond dissoc...

The objective of this study was to mimic the microstructure of MCrAlY coatings sprayed using HVOF (High Velocity Oxy-Fuel) processes by using an Air Plasma Spray (APS) process in order to improve oxidation and spallation life of MCrAlY APS coatings. Figure 1 shows the typical microstructures obtained when spraying bond coats using the (a) HVOF process, and (b) the APS process. The microstructur...

Neutrophil arrest and migration on inflamed endothelium is dependent upon a conformational shift in CD11a/CD18 (LFA-1) from a low to high affinity and clustered state which determines the strength and lifetime of bond formation with intracellular adhesion molecule 1 (ICAM-1). Cytoskeletal adaptor proteins kindlin-3 and talin-1 anchor clustered LFA-1 to the cytoskeleton and support the transitio...

Weak bonds are ubiquitous in biological structures. They often act as adhesive contacts within an extended structure, for example, the internal bonds in a folded protein or a DNA/RNA loop. They also act as linkers between two structures, for example, a protein grafted in a cell membrane or a protein linking the cell membranes of two neighboring cells. Typically, the breakage of a bond depends o...

A general rhodium-catalyzed oxidative coupling reaction between internal alkynes and aryl aldimines is described. This process affords 3,4-disubstituted isoquinolines in good yield and high regioselectivity. Preliminary mechanistic studies suggest that the C-N bond formation arises from the reductive elimination of a rhodium(III) species.