小学四年级英语单词
A stock of 100% justaboutenough住宿生开学必备物品清单>拓展夏令营>4 6级成绩查询>汽车的维修avertin is prepared by mixing 10 g of 2,2,2-tribromoethyl alcohol (Aldrich T4,840-2) with 10 ml of tert-amyl alcohol (Aldrich 24,048-6). Make sure it is fully dissolved (heat to 50°C; u a microwave oven or magnetic stirrer overnight). (Note: If 2,2,2-tribromoethanol is dark in color, it should be recrystallized before u; e below). To u, dilute 100% stock to 1.2-2.5%, v/v, in water or isotonic saline, stirring vigorously until it is dissolved. Filter-sterilize through 0.2-micron filter (filtering also removes remaining undissolved crystals). Both the 100% stock and working solutions are stored in the dark at 4°C to prevent decomposition to the irritant by-products, dibromoacetic aldehyde and hydrobromic acid (Papaioannou and Fox 1993). The working solution is stable for a couple of months, but some labs prefer to prepare it fresh from stock aliquots immediately prior to the experiment.
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