Subject silica removal from water

The dried powder is placed in a mold and subjected to a gradually increasing pressure of 25 t.s.i. over a period of three minutes and the pressure then gradually reduced over a period of one minute. The coherent, molded bar is further dried in air at 50°C and then placed in an electrically heated muffle and heated to 800°C, while supported on a fused silica plate. Another electric muffle, adjacent to the first, is heated to a temperature of 1050°C. The silica bar, not yet sintered at 800°C is quickly transferred to the muffle at 1050°C and left for 15 min. It is observed that the specimen shrinks perceptibly in dimensions, and becomes more translucent. As soon as this change occurs, which requires 15 min at 1050°C, the specimen is removed from the furnace and cooled by dropping it into water. 

Tuber slices (338 kg) (1.5-2,0 mm thickness) of Ri cultivar Rishiri were inoculated with a zoospore suspension (250000-500000 zoospores/ml) of incompatible race of Phytophthora infestans (Mont.) de Bary, race 0 and incubated at 18-20°C for two days. The inoculated slices were stored in an ice-box (-30°C) for a week and then immersed in methanol (250 1) for a week. The supernatant was separated by decantation and the process was repeated twice with methanol (2 x 150 ml). The methanol extracts were combined and concentrated under reduced pressure below 30°C. The concentrate was extracted with chloroform and evaporated to yield oily residue from which a solid material was precipitated on treatment with acetone and was then removed by filtration. The filtrate w as c oncentrated to yield an o ily residue which w as treated with hexane. The hexane solution was concentrated, extracted with ether and washed with aqueous sodium carbonate (10%) and hydrochloric acid (0.1 M) to remove acidic and basic components. The ether extract was washed with water, dried and evaporated. The residue, which contained many c ompounds (by tlc) w as subjected toehromatographic p urification over silicic acid (Mallinckrodt, AR-100) and celite. Benzene ether (1 1 and 1 2) afforded crude rishitin which showed an almost single spot on tic. This was chromatographed over silica gel (Merck). Ether eluted pure rishitin (40) (3.9 g, from 338 Kg tuber slices), m.p. 65-67°C, [ai]-35.1°, max s, 3060,1640 and 890 cm 1 1HNMR 51.12 (3H, d, J=6 Hz), 3.12 (1H, t, J=9Hz),3.55 (lH,br,do,d, J=9and7 Hz), 4.18 (2H, br, s, 2 OH) C,3NMR 148.9 (Cn), 129.0 (C5), 124.9 (C10), 10.9 (C12), 79.2 (C8), 71.5 (C2), 41.6 (C7), 40.4 (C4), 38.3 (C8), 31.1 (C6), 29.7 (C9), 26.5 (C,), 21.0 (C13), 16.4 (Cm).22... 

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