Test-tube ends plastic

Sterilization After a suitable culture medium is selected for the cultivation of a specific microorganism, it is poured into a culture vessel. If you use test tubes or flasks as your culture vessel, the ends of test tubes or flasks should be covered with a suitable closure to allow for the exchange of gases with the atmosphere, yet to keep foreign organisms out of the media. Various types of closures are used in the modern laboratory including cotton plugs, plastic foam, screw caps, metal caps, and aluminum foil. 

Preferably in a hood, add 10 mL of toluene to the sample and heat it gently until the solvent boils. Adjust the height of the test tube so it gently boils. Continue the heating for about 5 minutes. If the plastic does not form a homogeneous and transparent solution, it is considered insoluble. Careful if the solvent should catch on fire, do not panic. Simply cover the end of the test tube with a cloth towel to smother the flame, then continue on. Record your results. Make a list of either what it cannot be or what it may be. 

Place this hank in a fold of paper or a test-tube so that a bundle of fibers 2—3 cm long protrudes from the end. Place the paper fold or test-tube flat on the light box so that individual fibers may be teased from the protruding bundle and withdrawn using plastic-tipped forceps (see Note 3). 

In its simplest form, a breath alcohol screening test consists of a sealed glass tube containing a potassium dichromate-sulfuric acid reagent impregnated on silica gel. To administer the test, the ends of the tube are broken off, a mouthpiece is fitted to one end, and the other end is inserted into the neck of a plastic bag. The person being tested then blows into the mouthpiece until the plastic bag is inflated. 

The USP disintegration test is typical of most and is described in detail in a monograph of that volume. Briefly, it consists of an apparatus in which a tablet can be introduced into each of six cylindrical tubes, the lower end of which is covered by a 0.025 in.2 wire mesh. The tubes are then raised and lowered through a distance of 5.3-5.7 cm at a rate of29-32 strokes per minute in a test fluid maintained at 37 2°C. Continuous agitation of the tablets is ensured by this stroking mechanism and by the presence of a specially designed plastic disk, which is free to move up and down in the tubes. 

The central element of the dilatometer is the vitreous silica tube. Vitreous silica is quartz having the coefficient of thermal expansion 100 times less than that of most plastics. The sample is placed into the tube with one end of the sample against a spring loaded push-rod, slide into a cylindrical furnace, which is placed in the -30°C controlled environment, such as liquid bath. The ASTM test describes details of the test. As the sample contracts, the motion is transmitted and detected by a... 

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