nowadays nmr spectroscopy becomes a powerful tool in chemistry because of the nmr chemical shifts. hartree–fock theory and the gauge-including atomic orbital (giao) methods are used in the calculation of 29si nmr chemical shifts of various silicate species in the silicate solution as initial components for zeolite synthesis both in gas and solution phase. calculations have been performed at geo...

today the usage of some compounds as indicator, can be checked changes of the food quality without opening the package. the most important indicators are indicates that show the level of product quality and freshness. freshness and temperature - time reagents reflect on extension of the product quality. indicators show the quality of the product, by physical and chemical changes which will be l...

groundwater contamination is a serious problem facing the countries. because groundwater is vulnerable to contamination from a variety of sources, and, once contaminated, it is very difficult to restore to its original quality. the main objective of this study was evaluation of groundwater quality in shahrekord aquifer and finding the source of the groundwater contamination. some of the chemica...