Use and abuse of psoralens.
The psoralens 1 are furocoumarins to which most people in the United States have been exposed. Celery contains psoralen. Oil of bergamot, widely used in perfumes, contains 5-methoxypsoralen. Thus, there are few persons who have not ingested psoralen and probably no adult woman who has not applied a psoralen to her skin. Plants containing psoralen have been used to produce pigmentation for at least 3,000 years. Recently, oil of bergamot has been used for this purpose. Scientific investigation of the psoralens began when Kuske 2 and, later, Fahmy and his group 3 isolated the active chemicals from a variety of plants. Many physicians in different countries began to study these compounds. Lerner, Denton, and Fitzpatrick 4 and Kelly and Pinkus 5 initiated clinical evaluation in the United States. The chemical alterations in the psoralesn which occur after oral ingestion or topical application to the skin are not known. Exposure of
ULTRAVIOLET LIGHT IN OFFICE PRACTICE.
Ultraviolet light sources have both diagnostic and therapeutic value and are useful adjuncts to the physician's office equipment. The long ultraviolet rays produced by black light or Wood's light are of significant aid in diagnosing ringworm of the scalp, erythrasma and porphyria. Natural sunlight, hot and cold quartz lamps, mercury vapor lamps and fluorescent sun lamps produce the therapeutically active shorter rays. The advantages and disadvantages of these sources of ultraviolet light, the diseases that will respond to them, the general technics for their use, and the value and dangers of actinic exposures are discussed. Patients should be warned of the danger of repeated nontherapeutic sun bathing, which causes significant cutaneous damage that may lead to skin cancer.
Effects of the mineral phase and valence of vanadium on vanadium extraction from stone coal
The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 mol/L H2SO4 at 90°C for 2 h. After the sample is roasted at 900°C for 2 h, the leaching rate of vanadium reaches the maximum, and more than 70% of vanadium can be leached. The crystal of vanadium-bearing mica minerals decomposes and the content of V(V) increases with the rise of roasting temperature from 600 to 900°C, therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals. Some new phases, anorthite for example, form when the roasting temperature reaches 1000°C. A part of vanadium may be enwrapped in the sintered materials and newly formed phases, which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically. The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.