This study describes a method of utilizing unaveraged dipolar effects to characterize and compute collagen fiber tracks using magnetic resonance imaging. The technique yields information about fiber structure with some similarities to what can be obtained in brain using diffusion tensor imaging, but relies on a completely different physical mechanism, namely, unaveraged homonuclear dipolar inte...

The title compound, C(22)H(17)N(3)O(4), was prepared through 1,3-dipolar cyclo-addition: the dihedral angle between the benzimidazole and benzene rings is 80.93 (6)°. The crystal structure is stabilized by weak π-π inter-actions between the planar pyrrolobenzimidazole rings (r.m.s. deviation = 0.0293 Å) of neighbouring mol-ecules, forming chains along the c axis. The perpendicular distance is 3...

In the presence of 1 mol% of a copper(II) catalyst and air, a readily available N-acetyl-N-thioacylguanidine undergoes a one-pot benzylic oxidation–oxidative heterocyclization sequence to give the 3-amino5-acyl-1,2,4-thiadiazole core of polycarpathiamines A (2) and B (3) and thus facilitating the first synthesis of both natural products. This methodology offers a straightforward alternative to ...

We use Ramsey spectroscopy to experimentally probe the quantum dynamics of disordered dipolar-interacting ultracold molecules in a partially filled optical lattice, and we compare the results to theory. We report the capability to control the dipolar interaction strength. We find excellent agreement between our measurements of the spin dynamics and theoretical calculations with no fitting param...

the catalytic highly regio-, diastereo-, and enantioselective synthesis of a small library of spiropyrrolizidineoxindolesvia a four-component 1,3-dipolar cycloaddition reactionof azomethineylides, derived from isatin, with electron-deficient dipolarophilewas described. the process occurs at room temperature in aqueous ethanol as a green solvent and in the presence of a bidendatebis(imine)–cu(ii...

MANY STUDIES have rather clearly demonstrated the inadequacy of the simple dipolar concept to account for the total elec-trocardiographic information available on the body surface.'-6 For example, Okada, Langner, and Briller have attempted extraction of the dipolar component from the precordial leads by cancellation with synthetic dipolar leads derived from vectorcardiograms. An unac-counted-fo...

Various motionally averaged 31P-1H, 13C-1H, 1H-1H, and 31P-13C dipolar couplings were measured for natural-abundance and unoriented phosphocholine in the L alpha phase. The couplings were obtained and assigned by a variety of advanced and partly novel two-dimensional solid-state NMR experiments. Whereas 31P-1H and 31P-13C dipolar couplings provide long-range structural constraints, geminal 1H-1...

In weakly orienting media such as poly-c-benzyl-L-glutamate (PBLG) a polymer that forms a chiral liquid crystal in organic solvents, the spectral resolution for embedded molecules is usually poor because of numerous H, H dipolar couplings that generally broaden proton spectra. Therefore H, C dipolar couplings are difficult or impossible to measure. Here, we incorporate Flip-Flop decoupling duri...