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Dense and porous Ti, Ti-alloy, and stainless steel specimens were implanted in canine trabecular bone. After 6 and 12 months the specimens were retrieved together with bone tissue immediately adjacent. The trace metal content in the tissue samples was determined using neutron activation analysis, differential pulse polarography, graphite furnace atomic-absorption spectrophotometry, electron microprobe analysis, and laser microprobe analysis. The results are discussed in view of (i) the release of Ti ions, which is larger for porous than for bulk specimens, (ii) the various artifacts arising in electron microprobe (EMP) and laser microprobe mass analysis (LAMMA) determination of compositional gradients of trace metal-ion content in bone tissue, (iii) the absence of measurable quantities of V in bone tissue, and (iv) the difference in local tissue accumulation between Ti, released from Ti specimens, and Ni, released from stainless steel specimens.

Raman spectra were obtained from the (001), (010), and (100) faces of a St. Claire dickite specimen of known orientation. Raman spectra collected from the (010) and (100) faces of dickite are reported for the first time and reveal vibrational features significantly different from the (001) spectra. Variations in intensities of the (⌷⌯) bands in polarized spectra were used to confirm previous band assignments, to determine the shape and orientation of the local Raman tensors for the OH1 and OH3 groups. The most striking polarization effect observed in the (⌷⌯) region of dickite was the behavior of the a(cЈcЈ)ā spectrum relative to Raman and IR spectra of other orientations. Unlike previously reported spectra, the dominant feature in this spectrum was the 3643 cm Ϫ1 band. This large increase in intensity of the 3643 cm Ϫ1 band in comparison with the other (⌷⌯) bands was related to the fact that Raman spectra were recorded from the edge faces of dickite with the electric vector of the incident laser polarized along the c axis. This permitted observation of vibrational modes polarized along the c axis. Raman frequencies of the (⌷⌯) bands assigned to the OH2 and OH4 groups differ from their IR counterparts by 12 cm Ϫ1 , suggesting that these groups may be related by a center of symmetry. For comparison, Raman spectra in the (⌷⌯) region were also obtained from individual micro-crystals of kaolinite that were approximately 5 m across the (001) face.

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At room temperature both Fe(III)-exchanged montmoriUonite and Fe(III)-hectorite gave similar M6ssbaner spectra, each consisting of a single doublet with parameters characteristic of ferric iron. At 77 K the Fe(III)-hectorite gave a spectrum similar to that observed at room temperature, but with the montmorillonite an additional distinct doublet, with relatively large values of both isomer shift and quadrupole splitting, was observed. The Fe(II)-exchanged samples behaved very differently at room temperature and 77 K. At 77 K well-defined doublets were produced; these had quadrupole splittings similar to those shown by the Fe~ + ion and appreciably greater than those observed for Fe(II) in the structural sites in layer-silicates. At room temperature, however, there was no absorption corresponding to ferrous ions in either of the specimens, because the recoil-free fraction was low as a result of the loose association between the Fe~q + ion and the mineral lattice.