Influence of opacity on the color stability of a nanocomposite.

Objective: The aim of this study was to evaluate the color stability in relation to the opacity of the nanocomposite Filtek Ultimate (3M ESPE), by immersing the specimens in different types of natural and artificial staining solutions.

Material And Methods: Eighty disks of the shades A1 body (A1B), A1 dentine (A1D), A1 enamel (A1E), and white enamel (WE) (n = 4) of the nanocomposite Filtek Ultimate (3M ESPE) were immersed in staining solutions Orange II, Amaranth, coffee, tea, and artificial saliva. Color coordinates Commission Internationale de l'éclairage (CIE) L*a*b* were collected before and after immersion at 4, 6, 12, 24 h and 7 days.

Determination of the floral origin of some Romanian honeys on the basis of physical and biochemical properties.

The aim of this study was to determine the physical and biochemical properties of some Romanian honeys in order to discriminate between their floral origins. The evaluated properties were total phenolic content, total protein content, total free amino acids content, color intensity (ABS(450)), pH, ash content, antioxidant activity. Twenty-six commercial honeys from six types of flowers (acacia, sunflower, forest, polyfloral, lime and Sea Buckthorn) were investigated.

Simultaneous determination of methylxanthines in different types of tea by a newly developed and validated TLC method.

The aim of this paper is to develop a new simple, fast and economical method for simultaneous quantitative determination of methylxanthine compounds based on TLC combined with image analysis. To obtain certain results, both extraction and chromatographic separation were optimized. The optimum extraction conditions were maceration in ethanol-water 8:2, v/v.