Collision tumor of the cecum and ileocecal valve composed of mucinous adenocarcinoma and neuroendocrine tumor: a case report.

Background: Collision tumors of the gastrointestinal (GI) tract are thought to be uncommon, with those of the colon being rare with very few cases reported in current literature. There are three proposed theories regarding the etiology of collision tumors currently, including the "double primaries", the "biclonal malignant transformation", and the "tumor-to-tumor carcinogenesis" theories. Prognosis of collision tumors remains unclear.

["Two professions for a single task". The introduction of chemical engineering in Spain during the first Francoism].

Through the first half of the 20th century, chemical engineering was established as an academic option in the training of specialists for the North-American and European chemical industry, whereas it was not a special field of study in Spain until the 1990s. The reason for this delay was a battle of interests between chemist and industrial engineers to control this career during the first Francoism. This article will try to show the development and professionalization of specialists for the Spanish chemical industry.