approximately 20% of caustic ingestions result in some degree of esophageal injury. alkaline materials are the most frequent corrosive materials ingested.     the physical form and ph of ingested materials play a critical role in the site and type of gastrointestinal injury (ph > 12 or ph < 1.5, crystalline drain cleaners). unlike alkaline solutions, strong acids are bitter, burn on contact and...

Natural cases of dealloying or stress-corrosion cracking in copper alloys normally occur in oxygenated solutions, where the cathodic reactant is O2 or Cu2+. Within cavities or under deposits, the local environment is enriched in cuprous ions (e.g. CuCl2-, Cu (NH3)2+) and the potential is close to the Cu/Cu+ equilibrium. Such conditions can be simulated macroscopically by stirring powdered Cu2O ...

Visual purple from winter frogs shows an intermediate yellow color during bleaching by light; summer extractions do not. This seasonal effect can be duplicated by variations in the hydrogen ion concentration and in the temperature of the solutions. Increasing the pH approximates the summer condition, while decreasing the pH approximates the winter condition. Temperature has no effect on the ble...

This study evaluated color stability, surface roughness and flexural strength of acrylic resin after immersion in alkaline peroxide and alkaline hypochlorite solutions, simulating a five-year-period of use. Sixty disc-shaped (16 x 4 mm) and 60 rectangular specimens (65 x 10 x 3.3 mm) were prepared from heat-polymerized acrylic resin (Lucitone 550) and assigned to 3 groups (n = 20) of immersion ...

Infrared absorption spectra of the precipitated solids separated from aluminiumhydroxide solutions below the pH of minimum solubility of AI(OH)3 demonstrate the slow ageing of polymeric A1 complexes to gibbsite. On comparison with the spectra of natural gibbsites, shifts in absorption frequency during crystal growth are interpreted in terms of changes in hydrogen bonding as a consequence of dep...

Silver staining was introduced more than a decade ago as a sensitive procedure to detect trace amounts of proteins in polyacrylamide gels (1). Since then, silver staining has been perfected and extended to the study of other biological molecules that have been separated by electrophoresis in a variety of supports (2,3). Silver staining follows generally one of two methods. One uses diamine or a...

HE BIURET REACTION has become an important analytic procedure for rapid and accurate determinations of protein concentrations in biologic fluids. Since the initial reports of Riegler (1), Autenrieth and Mink (2), and Autenrieth (3), who showed that proteins react with alkaline copper solutions to yield a violet-blue color, many modifications have appeared to improve the stability of alkaline co...