Biomedical subjects
Publications and source records attributed to R A Sanchez.
Variations in phytochrome status in grasses were provoked by end of day red and far-red treatments and above canopy irradiations. Lolium perenne L. and Lolium multiflorum Lam. plants developed more tillers when illuminated with higher red/far-red ratios. These results show that branching of grasses is controlled by phytochrome activity in a way similar to that in dicotyledon plants.
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Nicotinonitrile, 2-cyanopyridine, and 4-cyanopyridine can be synthesized under primitive earth conditions by the action of electric discharges on ethylene and ammonia. The electric discharge first synthesizes pyridine and hydrogen cyanide, which react in the discharge to form the cyanopyridines. Nicotinonitrile would have hydrolyzed in the primitive ocean to nicotinamide and nicotinic acid.
We have identified propiololdehyde as a product of the action of an electric discharge on mixtures of methane and water or methane, nitrogen, and water. The aldehyde reacts with cyanoacetaldehyde and ammonia (other "prebiological molecules") to yield nicotinonitrile. This substance can be hydrolyzed to nicotinamide and nicotinic acid.
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Cyanoacetylene is a major nitrogen-containing product of the action of an electric discharge on a mixture of methane and nitrogen. It reacts with simple inorganic substances in aqueous solution to give products including asparticacid, asparagine, and cytosine.
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Interchangeability of a semiadjustable articulator could be of significant convenience and economic benefit to the restorative dentist. The manufacturer of the Whip-Mix Model 2240 articulator claims such interchangeability. This study evaluated the accuracy of the cross-mounting capability of eight such articulators, then compared the measured results with those obtained from eight semiadjustable instruments for which the manufacturer makes no such promise of interchangeability. It was determined that the Model 2240 articular did possess accuracy when a measuring device was transferred between the eight materials tested.