Solution Tube

Fig. 11. (a) Diffeiential centrifugation (pelleting), where time 1 < time 2 < time 3 < time, (b) Rate 2onal separation in a swinging-bucket rotor, where tube 1 represents the density gradient solution, tube 2 the sample plus the gradient, and tube 3 the separation of sample particles under a centrifugal force, where... 

Prepare at least four solution tubes (two for the specimens, two for blanks) as follows ... 

Precondition the solution tubes as follows a) Using 5cm pieces of the rubber tubing, connect the solution tubes to the manifold of the... 

Caution If the air is admitted too rapidly, wads of pyrex wool may be drawn into the solution tubes... 

Clean and remove electrostatic charges from the solution tubes by wiping them with a wet towel and drying them with a clean lint-free cloth (without tubbing). Place the tubes in the wire-screen tray, cover them with a cloth to protect them from dust, and allow them to stand near die balance for at least 30 mins to attain equilibrium with the moisture content of the air... 

Support tbe cubes in wire holders (Fig Et 7) and weigh each solution tube (incl blanks) to within 1 mg, using the counterpoise (Fig Et 8) on the right-hand side of the balance... 

Note The counterpoise approximates the weight, volume, and exterior surface area of a solution tube containing 10 steel balls and 50ml of dibutylphthalate. It should be kept standing near the balance, covered with a cloth to protect it from dust. Do not wipe tbe counterpoise wiping will disturb its equilibrium with the prevailing temperature, pressure, and humidity... 

Caution The solution tubes must be kept tightly corked hereafter to prevent absorption of atmospheric moisture by the very dry dibutylphthalate, except during evacuation in the oven and while being weighed. 

Remove the cork stoppers from two of the prepared solution tubes, and take out the wads of glass wool, using forceps. Add one of the accurately weighed specimens of the propellant to each, using a small metal funnel (9-mm od outlet) to prevent adherence of the propellant to the walls of the tube. Reinsert the wads of glass wool. 

Note Propellants soften and tend to gelatinize when added to dibutylphthalate solution. Therefore, the solution tubes should be rocked as soon as possible after the addition so that the propellant does not adhere to the walls of the tube and prevent the steel balls from moving. 

As soon as all the solution tubes have been placed in the oven (maintained at 85°... 

Close stopcocks B and G, and needle valve E, and open stopcock A. Then turn on the vacuum pump, and evacuate the solution tubes to a pressure of 1 mm of mercury or less. 

When the pressure has stabilized at 1 mm of mercury, turn stopcock F to admit nitrogen slowly to the solution tubes. 

Caution Admit nitrogen slowly so that the glass wool or other foreign matter from the manifold or tubing is not carried into the solution tubes. 

Allow the solution tubes to rock until sample has completely broken up or a maximum of 15 hours at a temperature of 85° 1°C. 

While observing the solution tubes through the glass door of the oven, gradually dose needle valve E to lower the pressure in the vacuum line assembly, being careful not to close the valve so fast that the solution in the tubes boils violently. 

Remove the solution tubes from the oven, and cool them, as described in paragraphs 5.2(f) and 5.2(g). 

Figure 2.3 Scheme of QCISD/DFT hyperfine coupling constant (HCC) calculation for the DTBN molecule in vacuo and in aqueous solution tube represent the model system, balls and sticks represent the rest of the system (see Colour Plate section). 

Set up the reactions described in the table below in 1.5-ml microcentrifuge tubes The extracted lipids that are currently dissolved in chloroform cannot be used directly in this assay, since the chloroform will denature the enzymes that will eventually produce a colored product (see Fig. 13-1). To prepare the lipids in your sample for this assay, add the indicated volume of lipids in CHCf to tubes 4 and 5, dry them under a stream of N2, and resuspend each sample in 10 pi of isopropanol. The standard cholesterol solutions (tubes 1-3) can be used directly in this assay by adding the indicated volumes to the appropriate tubes. (See chart below.)... 

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