Misconceptions concerning rotation and angie in LOGO

Abstract  Twelve children, aged between 10 and 11 years old were given a 12-hour course in LOGO. The course was taught by a teacher whose knowledge of LOGO was extensive. The emphasis was on the relationship between the turtle rotation and the internal angle in plane figures. The children were tested for their knowledge of angle at the start of the course and when it was finished. In spite of the teacher's attempts to make the children aware that it was the external angles of geometric figures through which the turtle turned, almost all the children focused on the internal angles in the final test. The results suggest using LOGO to draw closed figures may lead to a confusion about angle which is not amenable to conventional teacher intervention in a short course of this nature.     

Comparative rates of formation of fatty acids in the soybean seed during its development

Summary Lincoln soybeans harvested at successive stages of maturity showed continuous increases in amounts present of each of the fatty acids: saturated, oleic, linoleic, and linolenic. The iodine value and linolenic acid percentage of the oil decreased somewhat during the early stages of seed development. The linoleic acid and total oil percentage in the bean increased continuously until the 50th day then remained constant. Oleic and saturated acids fluctuated. No evidence for dehydrogenation of saturated fatty acids was obtained either in the oil analyses or in tests of soybean tissues for dehydrogenase activity. Journal Paper No. 717 of the Purdue Agricultural Experiment Station, Lafayette, Ind.     

The sequence of formation of fatty acids in developing soybean seeds

Summary Excised Lincoln soybean stems bearing pods and leaves were supplied with C¹⁴ labeled-sucrose for brief periods, and the subsequent appearance of radio-activity in the different fatty acids was observed up to 18 days. The individual fatty acids were separated as their 2,4-dinitrobenzenesulfenyl chloride derivatives and the specific activity of the different fractions were determined. Radioactivity appeared in the fatty acids in the following order: oleic, saturated, linoleic, linolenic. Consistent presence of highest specific activity in the oleic acid fraction indicated that oleic may be converted to the other acids, at least to some extent. Journal Paper No. 719 of the Purdue Agricultural Experiment Station, Layfayette, Ind.     

Surface composition of anhydrous tricalcium aluminate and calcium aluminoferrite

Electron spectroscopy and optoacoustic spectroscopy (OAS) have been used to study the surfaces of synthetic tricalcium aluminate, Ca₃Al₂O₆ and calcium aluminoferrite, Ca₂AIFeO₅. The surfaces of these compounds have compositions which differ markedly from those of the bulk. The surface of tricalcium aluminate is depleted in calcium and enriched in aluminium and also carries relatively stable hydroxyl groups, which can be detected by OAS. Calcium aluminoferrite has a surface enriched in aluminium and depleted in calcium and iron. Again, some hydroxyl groups are present on the surface. These differences in surface composition are discussed with particular reference to the early stages of reaction with water.