Stable pattern analysis

Stable isotope analysis of earth, moon and meteorite samples has provided important information concerning the origin of the solar system. Lunar samples returned to earth during the Apollo missions show 8170 and 8lsO enrichment patterns which are virtually identical to those of earth-bound rocks and minerals. On 3-isotope plots like those in Figs. 9.5 and 14.3, a uniform isotope reservoir is represented by a single... 

Soignard et al. [565] have smdied the stability of the two spinels in the system Si3N4-Ge3N4, at pressures up to 20 GPa and temperatures > 2000°C. The x-ray patterns analysis shows that the two new spinel nitrides remain essentially stable over the range of conditions examined. 

Stable Isotope Pattern Analysis by Nuclear Magnetic Resonance Measurements... 

Even in well documented archaeological excavations, however, the context and dating of archaeobotanical specimens may be problematic 14), and the identification of small numbers and certain forms of maize phytoliths has also been argued by some to be unreliable 15-16). In any event, even after its initial domestication, there was most likely considerable temporal and spatial variability in the incorporation of maize into existing subsistence patterns, and it is extremely difficult to measure its importance relative to other food resources since there is no way to balance the uneven representation and preservation of botanical and faunal remains in the archaeological record. The consumption of maize can, however, be quantified through stable isotope analysis of human skeletal remains 17-20). 

These nitridooxophosphates are stable in water and 1 N HC1, which is useful to extract eventual by-products. Their composition has been undoubtedly established by a complete chemical analysis. The XRD powder patterns can be indexed with hexagonal parameters (Z = 6) as illustrated for the potassium compounds ... 

Price, T.D., Grupe, G. and Schroter, P. (1994). Reconstruction of migration patterns in the Bell Beaker period by stable strontium isotope analysis. Applied Geochemistry 9 413-417. 

A different pattern of dissolution was seen with a Zn-Sn alloy containing 26% zinc. In this case the stable dissolution situation established after ca. 90 min showed a ratio of EC to CMT measurements of 1 4. As seen in Fig. 3, this remained fairly constant, though the corrosion potential increased by more than 50 mV. Only selective zinc dissolution took place, and analysis by atomic absorption spectroscopy of the amount of dissolved zinc agreed within 10% with the value according to the titration. This pattern is still difficult to understand. The ratio of ca. 1 4 between EC and CMT measurements could be interpreted in terms of formation of the low-valent zinc species ZnJ, which seems unlikely, or in terms of dissolution of divalent zinc ions accompanied by loss of chunks consisting of precisely three zinc atoms, each time a zinc ion is dissolved. The latter alternative seems to require a more discrete mechanism of dissolution than... 

Because of the inherently non-equilibrium nature of the production route, the first question which needed to be answered was whether the phases present in the alloy were in fact stable, so that equilibrium calculations could actually be used to design these alloys. To this end CALPHAD calculations were combined with a detailed experimental characterisation of a Fe7oCrigMo2B o alloy (Kim et al. 1990, Pan 1992). The TEM and XRD results confirmed earlier work (Xu et al. 1985) which stated that an orthorhombic boride M2B was present and its composition was Cr-rich. However, they also showed that a proportion of the borides ( 10%) were Mo-rich and that the Fe-based matrix was martensitic. The latter result was particularly surprising because of the high level (20at%) of a-ferrite stabilisers Cr and Mo. Furthermore, initial analysis of difiiaction patterns from the TEM work indicated that the shuctuie of the Mo-rich boride was a tetragonal type whose structure had not been reported in previous literature (Kim and Cantor 1988). 

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