This chapter describes some recent studies and applications of photochemistry in the physical–chemical characterization of two acrylic paint materials based on phthalocyanines and the study of the photodegradation (photobleaching) processes which could occur, caused by exposure to artificial irradiation, similar as in the museum. The studies in this paper has been conducted on phthalocyanines, these compounds being known as organic colorants in painting. Their color depends not only on the chemical nature of the colorant, which play an important role in the kinetics and degree of aging, but also on the compounds added to the paints (TiO2, micas, arylamide yellow). The techniques used in such studies involve UV–Vis spectroscopy, gloss, and colorimetric measurements, comparing our results with similar ones from the literature.
Part of the book: Photochemistry and Photophysics
This chapter describes recent research studies about kohlrabi, a versatile vegetable with important health benefits (e.g. reduces risk of breast and prostate cancer, improves body metabolism, helps in weight loss diets, etc.). The investigations are focused on pale-green kohlrabi giving an accurate and precise description, from a qualitative point of view, of the bioactive compounds found in different parts of the pale-green kohlrabi: core, peel, leaves and equal combinations between these parts. All the active principles from pale-green kohlrabi are extracted following a well-established method, in an aqueous medium at a constant temperature of 4°C for 24 h. The qualitative screening of phytochemicals gives details regarding the presence or absence of chemical compounds using different colour reactions.
Part of the book: Brassica Germplasm
This chapter describes in detail recent research results obtained from the qualitative screening of different phytochemicals found in aqueous extracts of sea buckthorn and gooseberry, fruits with important pharmacological effects due to their high content in vitamin C. Phytochemical investigations reveal the presence of active principles (e.g., saponins, flavonoids, alkaloids, carbohydrates, terpenoids, etc.) in sea buckthorn and gooseberry and are accomplished by using well-established standard methods. All these qualitative determinations rely on the visual color change reaction as a basic response to the presence of a specific phytochemical compound. The active principles from sea buckthorn and gooseberry are extracted according to a well-settled extraction method, which involves infusing the fruits in an aqueous medium, for 24 h, at a constant temperature of 4°C.
Part of the book: Phytochemicals