Rubber caps

A short piece of Teflon or of rubber tubing (or a rubber cap) fitted tightly over one end of a stirring rod of convenient size gives the so-called policeman it is used for detaching particles of a precipitate adhering to the side of a vessel which cannot be removed by a stream of water from a wash bottle it should not, as a rule, be employed for stirring, nor should it be allowed to remain in a solution. 

Into an intermittent venous access device called a heparin lock (a small IV catheter in the patient s vein connected to a small fluid reservoir with a rubber cap through which the needle is inserted to administer the drug)... 

Fig. 22 shows the one place where joint and nonjoint apparatus meet. There are two parts a rubber cap with a hole in it and a glass body. Think of the... 

The rubber cap fits over the nonjoint end of the glass body. The other end is a ground glass joint and fits only other glass joints. The rubber cap should... 

Great care must be taken that, when no gas is passing through the drying apparatus, its side tube, which leads to the combustion tube, remains closed by means of a rubber cap in order to protect the calcium chloride from atmospheric moisture. When the calcium chloride at the outlet is exhausted—-the sodium hydroxide-asbestos lasts much longer— the stopper is removed and about half of the column is replaced with fresh calcium chloride. 

During the analysis the calcium chloride tube is attached directly to the sodium hydroxide-asbestos tube. When the apparatus is not in use this calcium chloride tube is closed with a rubber cap.-... 

Clean the outside of the tube and transfer its contents with repeated washing with distilled water to a small ordinary type beaker. Remove barium sulphate which adheres obstinately to the wall of the tube with a glass rod (not rubber capped). By alternate washing with a little alcohol and a little water transfer the last traces of the barium sulphate to the beaker. 

The ProteomeLab PA800 instrument was set up to analyze a sequence of five different labeled rMAb samples with a total of 10 duplicate injections. On many occasions, the electrophoretic analysis of approximately 60% of the injections did not take place due to pressure failures in the instrument. Upon closer inspection, some of red rubber caps of the gel matrix-containing vials were missing, electrodes were bent, and capillaries were broken. Additionally, it was observed that the interface block was coated with a sticky film of gel matrix. It was apparent that the build-up of gel buffer was causing the red rubber caps to remain stuck to the interface block and interfere with the contact of vials in subsequent steps. To improve the removal of gel buffer, the interface block and the surrounding areas were carefully flushed with deionized water. Then, cotton swabs were used to wipe the grooves on... 

The apparatus shown in Fig. 3.5 was used, and was filled completely with cement paste. Admixture additions were made by injecting with a hypodermic needle through the rubber cap. Pastes prepared in this way had air contents of less than 0.6% by volume, were free from any premature stiffening tendencies and were homogeneous. 

The absorption train can then be detached, removed to the balance room, wiped carefully with a clean hairless cloth and kept 15—20 minutes to attain constant temperature. The tubes are then weighed without their rubber caps. If the apparatus is in proper working order, and the... 

Fig. 1.31. Heavy-walled centrifuge-tube, rubber cap liner, and cap. ("Pop bottle reactor.) Tubes with volumes ranging from 20 to 250 mL are available from Lab Glass, North West Boulevard, Vineland, NJ 08360.

Together with 0.1 ml. of a 1% aqueous solution of acetone (internal standard), 0.5 ml. of the distillate (dilute aqueous solution of methanol) was placed into a 20-ml. flask and closed with a tight rubber cap. The flask was then kept in a drying chamber for 15 minutes at 60°C. An injection needle tempered at the same temperature was pierced through the rubber cap, and 1 ml. of the vapor phase was sampled and injected into the gas chromatograph. 

Mix well the contents of the Ficoll bottle, wipe the rubber cap with 70% ethanol then inject approx 15 mL air with a 20-mL syringe and needle and withdraw 20 mL of the Ficoll solution. Equally divide the Ficoll solution between two new 50-mL Falcon tubes. 

To overcome the difficulty of separation of the two halves on removal a silicon rubber cap was fitted over the nose of the suppository and the cord was threaded through the base of the device, out through the top, attached to the silicon button then back along the same route. Strain on pulling was then absorbed by the silicon rubber cap and the suppository could be withdrawn intact. 

This entire assembly was used as a rabbit and irradiated in a reactor for 3 minutes. After the irradiation, the rubber cap sealing the recoil chamber was punctured with a double-walled hypodermic needle, and air containing the recoiled krypton fission products was drawn out through the coaxial outer annulus of the needle. The effluent gases were passed through a trap paoked with glass wool, cooled in a dry ice-... 

A typical procedure for Eq. (78) [153] is as follows. In a 100-ml two-necked flask with a reflux condenser, a balloon, and a rubber cap are placed Pd(OAc)2 (0.05 mmol), Cu(OAc)2 H2O (0.05 mmol), and molecular sieves 4 A (400 mg). After the apparatus is evacuated by pumping, nitrogen (750 ml) is introduced. Then the phenol (1 mmol), the alkene (3 mmol), DMF (5 ml), and air (150 ml) are injected into the flask, and the resulting mixture is stirred at 100 °C for 9 h. After cooling, the mixture is extracted with diethyl ether and dried over sodium sulfate. The coupling product is isolated by column chromatography on silica gel using hexane-ethyl acetate (99.5 0.5, v/v) as eluent. 

Disks faced with PTFE should be used in the head-space vials as some solvents may be absorbed by butyl-rubber caps. Contamination of samples with chloroform, usually from the laboratory environment, is common. An artefact eluting with a retention time of 33.2 minutes derives from the gas-chromatograph septa. 

Fig. 12. Design of the galvanic cell with a flat liquid-liquid interface. (A) The four-electrode type of cell with the aqueous (w, w ) and the organic solvent (o) phases, silver/silver chloride reference electrodes (1,4), platinum counter electrodes (2, 3), a glass barrier with a round hole for the liquid-liquid interface (5) and a tube connected to a syringe for adjustment of the interface. (After [158]). (B) The two-electrode type of cell with the aqueous (1,3) and organic solvent (2) phases, water jacket (4), PTFE silicone rubber (5), silicone rubber cap, silver/silver chloride reference electrodes (7,8), glass tube (9) and polarized working (w) or nonpolarized reference (r) interface. (After [42]).

Figure 3-22. Reaction vessel used to perform CO2 generating reactions. The vessel is composed of a 25 or 50 ml Erylenmeyer flask, a serum vial rubber cap, and a plastic center well. (Courtesy of Kontes Glass Co.)...

Preparation of Sephadex G-25 fine minicolumns was performed in the following way The barrels of 2-ml polyethylene syringes (50 x 9 mm) were furnished with a circular filter of Whatman No. 41 paper. After swelling for at least 3 hr in surplus of gelatin buffer Sephadex G-25 fine was packed into the syringes leaving the upper 4 mm of the barrels empty. Rubber caps were placed on the nozzles of the syringes, which were stored at 2° and used within 8 days. 

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