Calcium sulphate pellets

Calcium sulphate pellets impregnated with tobramycin are now available in a ready prepared pack and can be used with deep, severely infected ulcers in combination with systemic antibiotic treatment. The Osteoset T (Wright Medical) is a prefabricated plaster of parts pellet impregnated with tobramycin and the Bone Void Filler is available as a mixing kit allowing fabrication of pellets of various sizes and strengths. Following application the pellets remain in place and are reabsorbed over a 2-3-month period. 

Armstrong DG, Findlow AH, Cybil SC, Boulton AJM. Absorbable antibiotic-impregnated calcium sulphate pellets in the management of diabetic foot infections. Diabet. Med. 2001 18 937-948. 

To obtain a maximum yield of the acid it is necessary to hydrolyse the by-product, iaoamyl iaovalerate this is most economically effected with methyl alcoholic sodium hydroxide. Place a mixture of 20 g. of sodium hydroxide pellets, 25 ml. of water and 225 ml. of methyl alcohol in a 500 ml. round-bottomed flask fitted with a reflux (double surface) condenser, warm until the sodium hydroxide dissolves, add the ester layer and reflux the mixture for a period of 15 minutes. Rearrange the flask for distillation (Fig. II, 13, 3) and distil off the methyl alcohol until the residue becomes pasty. Then add about 200 ml. of water and continue the distfllation until the temperature reaches 98-100°. Pour the residue in the flask, consisting of an aqueous solution of sodium iaovalerate, into a 600 ml. beaker and add sufficient water to dissolve any solid which separates. Add slowly, with stirring, a solution of 15 ml. of concentrated sulphuric acid in 50 ml. of water, and extract the hberated acid with 25 ml. of carbon tetrachloride. Combine this extract with extract (A), dry with a httle anhydrous magnesium or calcium sulphate, and distil off the carbon tetrachloride (Fig. II, 13, 4 150 ml. distiUing or Claisen flask), and then distil the residue. Collect the wovaleric acid 172-176°. The yield is 56 g. 

Calcium sulphate in phosphoric acid (wet process for phosphoric acid) Petroleum sulphonate surfactants/hydrocarbon liquid Conditioned in mixer, pellets formed by tumbling... 

In a 250 ml. distilling flask (1) place 122 g. (119 ml.) of p-phenylethyl alcohol and 40 g. of sodium hydroxide pellets (or 56 g. of potassium hydroxide). Heat is evolved. Warm gently until bubbles commence to form and the mixtiu separates into two sharply-defined layers. Distil slowly water, etc. passes over first accompamed by the gradual disappearance of the upper phase. Finally the st n ene passes over at 140 160° (mainly 150°) collect this separately in a receiver containing about 0 1 g. of hydroquinone. Dry the distillate with a Uttle anhydrous calcium chloride or magnesium sulphate, and then distil under reduced pressure (2). Collect the pme stjTene at 42-43°/18 mm. The yield is 80 g. Add about 0-2 g. of hydroquinone (anti-oxidant) if it is desired to keep the phenylethylene. 

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