Esophageal pH monitoring developed a dependable external reference electrode. Using this technique to monitor esophageal acid exposure patients for periods up to 24 hours, DeMeester and Johnson were able to identify the most important parameters of esophageal acid exposure, and they developed a composite pH score to quantify gastroesophageal reflux. The initial 24-hour pH studies required hospitalization until the introduction of microcircuits in the 1980s that allowed portable esophageal pH monitoring in an outpatient setting. Gastroesophageal reflux disease (GERD) is a common disease in western countries. In the United States, 7% of the population experiences heartburn daily and 44% at least once a
Alkali manufacture Alkali manufacture Alkali manufacture is the process by which an alkali is made. Typical alkalis, produced commercially, include sodium hydroxide, sodium carbonate, potassium hydroxide and potassium carbonate. A number of processes have been proposed for the manufacture of alkali from various metals, the most common being the Leblanc and ammonia-soda processes. The Leblanc process, which was invented by Nicolas Leblanc around 1790, begins with the decomposition of sodium chloride by sulfuric acid, by which sodium sulfate and hydrochloric acid are produced. The sodium sulfate is afterwards fired with calcium carbonate and coal. Sodium carbonate can be extracted from this mixture