RESUMO
A new kind of imitation of turquoise named "Violet" and "White buffalo" which is a type of associated mineral of turquoise have appeared on the market recently and are becoming increasingly popular. Conventional instruments, X-ray fluorescence spectrometer, Infrared spectrometer, X-ray powder diffraction, Scanning electronic microscope, UV-Vis have been employed to discuss the gemmological characteristics of this kind of imitation of turquoise in this paper, to study their chemical composition, mineral composition, microstructure, spectral characteristics and color emerging mechanism. The X-ray fluorescence spectrum shows that the chemical composition of the sample is complicated. The basic elements of different-colour samples are basically identical which contains of Ca, Al, P, Cu, Si, K, Fe, Ba. It can be deduced from the intensity of infrared absorption bend that the major anion group of this kind of imitation of tuequoise is PO3-4. The analysis for X-ray powder diffraction data indicated that the major mineral of the sample is crandallite and woodhouseite. Meanwhile, the scanning electron microscopy showed that the structure of the dense sample is determined by numerous of scaly, leaf-shaped and irregular granular aggregates. With the study of absorption spectrum, the conclusion is drawn that Fe3+ electronic transitions are the main factor for coloring of the sample and color varies with the content of Fe3+.
RESUMO
OBJECTIVE: To observe the effect of chronic lead contaminant on protein expression of protein kinase (PKC) and calmodulin (CaM) in hippocampus of baby-rats. METHODS: The Wistar pregnant rats were randomly divided into 3 groups fed with distilled water and lead-contained water (0.2% and 1.0% lead acetate) respectively. The lead exposure period ranged from the 0 day of pregnancy to the offspring weaned. Then the baby-rats were fed with lead water the same as their mothers. Pups were killed at postnatal day 8 and 50 respectively. Atomic absorption spectrometry was used to determine lead content of rats' brain. Western-blotting was used to observe protein expression of PKC and CaM in hippocampus of baby-rats. RESULTS: The brain lead content of test groups was much higher than that of the control group in the same growth period (P < 0.01). The content of brain lead in rats of postnatal day 50 was significantly higher than that of rats of postnatal day 8 (P < 0.01). Compared with control group, PKC and CaM protein expressions of chronic lead exposure baby-rats in the hippocampus were down trend (P < 0.05). CONCLUSION: The decrease of PKC and CaM protein expression level in hippocampus might be one of the molecular mechanisms of lead induced impairment of learning and memory.