Evacuation vacuum

Figure 6-48A. Typical performance of high vacuum booster lobe-type high volume draw-down for evacuating vacuum systems before use of higher vacuum (lower absolute pressure) pump. By permission, Roots Division, Dresser Industries, Inc.

An oven-dried. 50-mL, 3-necked flask equipped wilh a pressure-equalizing dropping funnel, reflux condenser, nitrogen inlet, magnetic stirrer, and vacuum takeoff adapter is evacuated (vacuum pump) and refilled three times with nitrogen. 10 mL of THF and 0.735 mL (5.25 mmol) of diisopropylamine are then added via a double-ended needle. The solution is cooled to 0"C and 2.2 mL of a 2.4 M solution of butyllithium (5.25 mmol) in hexane are added. The lithium diisopropylamide is allowed to form at 0 °C for 15 min and is then cooled to — 20 C. 5 mmol of the chiral acyclic ketone iminc in 5 mL of THF are added (5 min) and anion formation allowed to continue for 1 h at 20 C. The anion solution is then heated to reflux for 2 h and cooled to —78 C. A solution of 5.25 mmol of the iodoalkane in 5 mL of THF is then added, and alkylation is allowed to proceed at — 78 °C for 1 h. Workup and hydrolysis, as described for the cyclic ketones (see Section 1.1.1.4.1.2.L), yields the a-alkylatcd acyclic ketones (see Table 4). 

The adsorbate from the gas container is introduced into the manifold, or dose volume, F of the formerly evacuated vacuum system and the resultant pressure, 1, is measured with the transducer subsequently, stopcock 2 is opened resulting in a pressure P2. Then [6]... 

There are studies to develop better and much safer insulating products for the future homes, such as aerogels, powder-filled/evacuated/vacuum insulation panels, and phase change materials. 

The phase-field distribution in the ternary Yb-Li-Ge system at 470 K is characterized by existence of four ternary compounds (fig. 9) (Pavlyuk 1993 and Bodak et al. 1995). No homogeneous ranges were encountered for the ternary compounds. The inuniscibility gap which exists in the Yb-Li binary system, extends in the ternary system to 17 at.% Ge. The alloys were synthesized by arc melting in a purified Ar atmosphere under a pressure of 1.01X10 Pa. The resulting buttons were annealed at 470 K for 500 h in a Ta container which were placed in the evacuated vacuum sealed quartz tube. Finally the alloys were quenched in ice cold water. The purity of the starting materials was Yb 99.82 mass%, Li 98.2mass% and Ge 99.999 mass%. 

Moving charged particles such as protons, electrons (cathode rays) and ions are deflected by electric and magnetic fields in an evacuated vacuum tube. These deflections are shown in Figure 2.12. The deflections of positive ions in a magnetic field is a key feature of the mass spectrometer used to study atoms. 

Preparation of films for sufficiently volatile molecules can also be perfonned by evaporating tire molecules in vacuum (gas-phase deposition) or by tire use of a desiccator which contains tire substrate and tire dilute solution in a vessel separately and which is evacuated to 0.1 mbar and kept under vacuum for several hours ( 24 h). This also results in a vapour-phase-like deposition of tire molecules onto tire substrates. 

The drying agent was filtered off on a sintered-glass funnel and rinsed with some THF. The solution was transferred into a 500-ml wide-necked flask and concentrated in a water-pump vacuum. In order to remove the last traces of THF and some water the flask was connected directly (without a column) to a condenser and a receiver, cooled at -190°. The flask was evacuated by means of a mercury pump (p < 0.1 mmHg) and heated for 1.5 h at 85°C. The greater part of the mono-... 

To a mixture of O.BB mol of anhydrous lithium chloride and 100 ml of OMSO was added a solution of 0.40 mol of the acetylenic tosylate (for a general procedure concerning the preparation of acetylenic tosylates, see Chapter VllI-3, Exp. 3) in IBO ml of DMSO. The flask was equipped for vacuum distillation (see Fig. 5). Between the receiver, which was cooled at -75°C, and the water-pump was placed a tube filled with KOH pellets. The apparatus was evacuated (10-20 mmHg) and the flask gradually heated until DMSO began to reflux in the column. The contents of... 

The beam of tiny drops passes from the exit nozzle across an evacuated space and into another small orifice (skimmer 1). In this evacuated region, about 90% of the originally injected helium and solvent is removed by vacuum pumps to leave a stream of droplets so small that they are called clusters. 

As for the far-infrared, absorption by air in the vacuum-ultraviolet (VUV) necessitates evacuation of the optical path from source to detector. In this region it is oxygen which absorbs, being opaque below 185 nm. 

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