The technique conditions of synthesis of hydroxyapatite(HAP) powder were studied by Sol Gel and chemical coprecipitation processes.The FTIR was applied to determine the chemical composition of the prepared product.The Ca/P ratio was determined also and compared with stoichimetric ratio of hydroxyapatite.The cross experiment result indicated that the optimum technique condition to gain high purity HAP powder involves Ca/P 1.67 ,pH 8.0,temperature 950℃,reaction time 3.5h when (C 4H 9O) 3PO and Ca(NO 3) 2 were used as starting materials;Ca/P 1.67 ,temperature 37.5℃,pH 9.0 and Ca/P 1.50,temperature 80℃,pH 11.0 when H 3PO 4 and Ca(OH) 2 were used as starting materials;and Ca/P 1.50,temperature 37.5℃,pH 9.0,Ca/P 1.67,temperature 50℃,pH 9.0 and Ca/P 1.67,temperature 70℃,pH 10.0 when (NH 4) 2HPO 4 and Ca(NO 3) 2 were used as starting materials.
Thirty two aquatic vascular plant communities and their water environments were surveyed in Jiangxi province.The communities were analysed using PCA(principal component analysis) ordination to determine the relationship between the communities and environmental factors,according to pH value,depth of water,COD, DO,NP and HM.The results showed that information in original environmental data of communities was held 71.0% in the first two components of PCA ordination,COD, DO,NP and HM were the principal factors to determine the ecological distribution of aquatic vascular plant..
