The impact of different nucleation methods with controlled supersaturation on the polymorphism of L-glutamic acid crystals was studied in a 50 dm 3 semi-batch crystallizer, in which 1.5 M H 2 SO 4 was fed into a 1.5 M monosodium glutamate solution. Supersaturation was controlled by a feedback loop based on measured ATR-FTIR spectra and on a thermodynamic model developed in house. Ultrasound-initiated nucleation produced pure a-polymorph (over 99.5 wt %) in the end product crystals at 1 mol/dm 3 supersaturation. Seeded crystallization also produced almost pure a-polymorph crystals (over 93 wt %), whereas spontaneous nucleation produced a polymorph mixture (from 30-70 wt %) under the same operating conditions. This indicates that supersaturation-controlled sonocrystallization can be used to control polymorphism in crystals. The novelty herein is the simplicity of the method directing the generation of a desired polymorph.
S U M M A R YPetrophysical, in particular seismic velocity, measurements of the Outokumpu deep drill core (depth 2.5 km) have been carried out to characterize the geophysical nature of the Paleoproterozoic crustal section of eastern Finland and to find lithological and geophysical interpretations to the distinct crustal reflectors as observed in seismic surveys. The results show that different lithological units can be identified based on the petrophysical data. The density of the samples remained nearly constant throughout the drilled section. Only diopsidetremolite skarns and black schists exhibit higher densities. The samples are dominated by the paramagnetic behaviour with occasional ferromagnetic signature caused by serpentinitic rocks. Large variations in seismic velocities, both at ambient pressure and under in situ crustal conditions are observed. The porosity of the samples, which is extremely low, is either intrinsic by nature or caused by decompaction related to fracturing during the core retrieval. It is noteworthy that these microfractures have dramatically lowered the V P and V S values. From the measured velocities and density data we have calculated the seismic impedances, Young's modulus and Poisson's ratios for the lithological units of the Outokumpu section and from these data the reflection coefficients for the major lithological boundaries, evident in the surveyed section, were determined. The data show that the strong and distinct reflections visible in wide-angle seismic surveys are caused by interfaces between diopside-tremolite skarn and either serpentinites, mica schist or black schist.
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