Removable surfaces, vacuum

Liner, chamber (PVD technology) A removable surface in a chamber used to collect vaporized material and prevent it from depositing on non-removable surfaces. See also Non-removable surfaces Vacuum surfaces. 

Non-removable surface (vacuum technology) A surface, such as a chamber wall, that is not easily removed and must be cleaned in place. See also Removable surface. 

Moisture and Water Content. Resins are thoroughly washed with water upon completion of manufacture and conversion (if necessary) to another ionic form. Excess water is removed by vacuum draining or filtration. Nevertheless, a significant quantity of water associated with the functional groups and adhering to the outer surface of the resin particles remains with the resin as it is discharged into shipping containers. No effort is made to dry the resin, except in a few appHcation areas, since the resins are used in aqueous processes in most installations. 

Several works have been reported for macroscopically orientated biological membranes.106-109 The biomembrane alignment can be carried out mechanically or magnetically. The first one relies on the deposition of lipid bilayers on the surface of a rigid support (glass plates) such that the bilayer normal is perpendicular to the surface of the support itself. Small peptides and the lipid bilayers can be dissolved in organic solvents which are successively removed under vacuum.105 The re-hydration of the system in a chamber of an optimized temperature, humidity and time gives rise to the desired orientation. 

Most metal standards dissolve in 6 M HC1 or HN03 or a mixture of the two, possibly with heating. Frothing accompanies dissolution of metals or carbonates in add, so vessels should be loosely covered by a watchglass or Teflon lid to prevent loss of material. Concentrated HN03 (16 M) may passivate some metals, forming an insoluble oxide coat that prevents dissolution. If you have a choice between using a bulk element or a powder as standards, the bulk form is preferred because it has a smaller surface area on which oxides can form and impurities can be adsorbed. After a pure metal to be used as a standard is cut, it should be etched ( pickled ) in a dilute solution of the add in which it will be dissolved to remove surface oxides and contamination from the cutter. The metal is then washed well with water and dried in a vacuum desiccator. 

Expts were conducted to measure heptane content after decanting, after evapn from proplnt surfaces under atm pressure and upon removal under vacuum. In general, it was found that the best conditions for the removal of heptane are (1) high mixing temp, (2) more than one decantation step, and (3) application of a good vacuum for several minutes on proplnt thickness of 0.4cm or less... 

Fig. 2.81. Schematic drawing of a disk dryer, heated disk surface 95 m2. a, Dryer housing b, alternating locks with product storage c, ice condenser d, alternating locks for product removal e, vacuum pumps f, shut-off valve for the condenser g, drive of product wipers ...

The sanded panel is brushed and vacuumed to remove surface dust and debris. Minute wood particles remaining on the surface through subsequent finishing steps will result in defective filling and printing operations. 

Apply a vacuum to the outlet of the column and draw off the solvent until it is a few millimetres above the bed surface. Remove the vacuum line and plug the bottom column outlet. 

Although a surface in an ambient environment may appear clean, in reality the surface is covered with a layer or layers of adsorbed species. These species may be either physically or chemically adsorbed to the surface, but in both instances prevent the study of a truly clean surface. Under a vacuum environment, such surface contaminants can be removed into the gas phase by sputtering the surface with energetic ions. Once the surface contaminants have been removed, ultrahigh vacuum conditions are required to keep the sample clean. For example, at a pressure of 1 X 10 Torr, a sample receives a flux of approximately 5 X 10 " molecules s cm . Assuming a surface density of 10 atoms cm and a sticking probability of 1 for the adsorption of the gas phase species, the sample would be covered by one monolayer of adsorbed species in seconds. Conversely, by working at pressures below 1 x 10 Torr, a sample can be easily maintained free of contaminants for times on the order of hours, the time frame required for most surface science experiments. 

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