ALL the known colorimetric methods for the determination of phosphate are liable to errors arising from (a) slight changes in acidity and concentration of reagents, and (b) the presence of interfering substances (e.g. fluorides, nitrites etc.). The following method is almost entirely independent of these disturbing factors, and possesses the added advantage of being more sensitive than those pr...

A protocol for amide coupling by in situ formation of acyl fluorides and reaction with amines at elevated temperature has been developed and found to be efficient for coupling of sterically hindered substrates and electron deficient amines where standard methods failed.

BHUIYA, A. K. & STANLEY, E. (1963). Acta Cryst. 16, 981. BUSING, W. R., MARTIN, K. O. & LEVY, H. A. (1962). ORFLS: A FORTRAN Crystallographic Least-Squares Program. Oak Ridge National Laboratory, Oak Ridge, Tennessee. CADY, H. H. (1967). Acta Cryst. 23, 601. DANIELSEN, J. (1963). ALGOL Program D45. Univ. of Aarhus, Denmark. FOLTING, K., LrPSCOMB, W. N. & JERSLEV, B. (1964). Acta Cryst. 17, 1263...

The potential energy surfaces of the group 17 XF3 (X = Cl, Br, I, At) fluorides have been investigated for the first time with multiconfigurational wave function theory approaches. In agreement with experiment, bent T-shaped C(2v) structures are computed for ClF3, BrF3, and IF3, while we predict that an average D(3h) structure would be experimentally observed for AtF3. Electron correlation and ...

A growing number of parents are refusing topical fluoride for their children during preventive dental and medical visits. This nascent clinical and public health problem warrants attention from dental professionals and the scientific community. Clinical and community-based strategies are available to improve fluoride-related communications with parents and the public. In terms of future researc...