John W. Liskowitz

Thermal behavior of some reducing disaccharides

Abstract Thermogravimetry was used to monitor the loss of weight of a series of reducing disaccharides during a heating process. The resulting heating-curves provide a kinetic fingerprint for the individual compounds. It was shown that the configuration of the disaccharides and the nature of the glycosidic bond affect ( a ) the shape of the heating curve, and ( b ) the temperature at which a given disaccharide loses a fixed percentage of its weight. There is also a positive correlation between the thermogravimetric data and the acid-catalyzed hydrolysis of the disaccharides in solution; the disaccharides that lose water at the lowest temperature are those having the largest rate-constants of acid hydrolysis. Examination of the products of heating indicate polymerization and an intramolecular loss of water, followed by cleavage to form 1,6-anhydro-aldohexopyranoses.

Properties of High-Performance Fly Ash Concrete

In this study, two types of fly ash, dry and wet bottom ashes of different particle size distributions, were used. Physical and chemical properties of these fly ashes were tested and compared with the original feed fly ashes received directly from the utility. The effects of these fly ashes on the strength of concrete were studied when used as 15, 25, 35, and 50 percent cement replacement by weight of cement. The results show that fly ash, when proportioned properly, can enhance the properties of concrete. The chemical composition of fly ash of different particle size distributions varies slightly. For fly ash with large particle size distribution, the fly ash concrete reaches only 85 percent of the control concrete strength at the age of 180 days.