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A linear empirical correlation was established between Raman stretching wavenumbers of phosphorus-oxygen bonds and their bond lengths in inorganic crystalline phosphates. Although established on samples of inorganic crystalline phosphates, the correlation can be applied to glassy and amorphous phosphate materials (GAMs). Their unpolarized vibrational spectra are often similar because they are determined largely by short-range order. The correlation was used to predict P -O bond length in the a-form of Li 3 PO 4 , which is stable over only a small range of temperatures below the melting-point. It can also be used to estimate the length of P -O single bonds, terminal P -O and O -P -O chain bonds and terminal double bonds in many technologically important amorphous materials containing phosphate groups. This correlation is expected to offer invaluable insight into the structures of phosphate species for which diffraction or other spectroscopic techniques provide incomplete structural information. That would enhance the value of Raman spectroscopy as a complementary technique in structural studies of phosphates.

The conformation of a general puckered ring is defined by a linear combination of normal atomic displacements, according to the irreducible representations of the DNh symmetry group. Each tw.odimensional representation contributes two uniquely defined primitive modes, superimposed on a onedimensional crown form that only exists for N even, adding up to N-3 primitive forms, for any N. The normalized linear coefficients are independent of the amplitude of pucker and of the ring numbering scheme. The formalism applies to any ring type and a quantitative characterization of conformations, intermediate between the conventional classical forms, is possible. It provides the basis for mapping conformations as a function of puckering parameters and a simple algorithm for the identification of the classical forms. The procedure relates general ring conformations to a few simple shapes, familiar to chemists, without losing the advantage of quantitative puckering analysis.

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Towards refining the classification of glass trade beads imported into Southern Africa from the 8th to the 16th century AD

Polyunsaturated fatty acids (PUFAs) have been reported to have an anabolic effect on bone in vivo, but comparative studies to identify inhibitors of osteoclast formation amongst ω3- and ω6-PUFAs are still lacking. Here we assessed the effects of the ω3-PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and the ω6-PUFAs, arachidonic acid (AA) and γ-linolenic acid (GLA) on a RAW264.7 osteoclast differentiation model. The effects of PUFAs on RANKL-induced osteoclast formation were evaluated by counting tartrate resistant acid phosphatase (TRAP)-positive multinucleated cells. PUFAs significantly inhibited RANKL-induced osteoclast formation in a dose-dependent manner with AA- and DHA-mediated inhibition being the strongest. Furthermore, RANKL-induced mRNA- and protein expression of the key osteoclastogenic genes cathepsin K and TRAP were inhibited by AA and more potently by DHA. Owing to the attenuated osteoclastogenesis by DHA and AA, actin ring formation and bone resorptive activity of these cells as evaluated on bone-mimetic plates were severely compromised. Hence, of the tested PUFAs, AA and DHA were found to be the most effective in inhibiting RANKL-induced osteoclast formation with the latter providing the strongest inhibitory effects. Collectively, the data indicates that these PUFAs may play an important role in regulating bone diseases characterized by excessive osteoclast activity.