Static vacuum

High Vacuum Static Argon Furnace Oxidation Experiments... 

Apart from the sheer complexity of the static stmctures of biomolecules, they are also rather labile. On the one hand this means that especial consideration must be given to the fact (for example in electron microscopy) that samples have to be dried, possibly stained, and then measured in high vacuum, which may introduce artifacts into the observed images [5]. On the other, apart from the vexing question of whether a protein in a crystal has the same stmcture as one freely diffusing in solution, the static stmcture resulting from an x-ray diffraction experiment gives few clues to the molecular motions on which operation of an enzyme depends [6]. 

The dielectric constant is a property of a bulk material, not an individual molecule. It arises from the polarity of molecules (static dipole moment), and the polarizability and orientation of molecules in the bulk medium. Often, it is the relative permitivity 8, that is computed rather than the dielectric constant k, which is the constant of proportionality between the vacuum permitivity so and the relative permitivity. 

The dielectric constant (permittivity) tabulated is the relative dielectric constant, which is the ratio of the actual electric displacement to the electric field strength when an external field is applied to the substance, which is the ratio of the actual dielectric constant to the dielectric constant of a vacuum. The table gives the static dielectric constant e, measured in static fields or at relatively low frequencies where no relaxation effects occur. 

Batch Crystallization Batch crystalhzation has been practiced longer than any other form of ciystaUization in both atmospheric tanks, which are either static or agitated, as well as in vacuum or pressure vessels. It is still widely practiced in the pharmaceutical and fine chemical industry or in those applications where the capacity is veiy small. The integrity of the batch with respect to composition and history can be maintained easily and the inventoiy management is more precise than with continuous processes. Batch ciystalhzers can be left unattended (overnight) if necessary and this is an important advantage for many small producers. 

In the static method the powder is isolated under high vacuum and surface gases driven off by heating the container. The container is next immersed in hquid nitrogen and known amounts of nitrogen vapor are admitted into the container at measured increasing pressures in the relative pressure range 0.05 to 0.35. 

Dust Explosions Static Electricity Hazards of Vacuum Hazards of Inert Gases Gas Dispersion... 

For the gravity discharge case, the height of the fluid at maximum vacuum, which is the point at which air would begin to backflow into the tank, is determined by Eq. (26-54). Equation (26-55) calculates the corresponding vacuum in the tank s headspace at this hquid height. Since the drain nozzle is open to the atmosphere, this solution is a static force balance that is satisfied when the sum of the internal pressure and the remaining fluid head is equal to the atmospheric pressure. 

A major advantage of static SIMS over many other analytical methods is that usually no sample preparation is required. A solid sample is loaded directly into the instrument with the condition that it be compatible with an ultrahigh vacuum (10" —10 torr) environment. Other than this, the only constraint is one of sample size, which naturally varies from system to system. Most SIMS instruments can handle samples up to 1-2 inches in diameter. 

Figure 6. Vacuum mixer for lead paste 1, mixing compartment 2, fast-rotating mixing tools 3, material-deflecting plate 4, discharge opening 5, static, vacuum-sealed enclosure [21J.

Ignition mixts of lower static sensitivity have been prepd from Ti hydride and K perchlorate (Refs 117 123), It was found that the hydride tends to react with the perchlorate at elevated temps and that such a reaction is progressive, particularly with high hydride concns. No data have been found on Zr hydride mixes, but it is expected that the behavior will be similar. It seems, however, that performance variations are common in Zr mixts, but that these can usually be traced to hydride contamination in the Zr, and that such problems can be solved by heating the Zr in vacuum at about 200° (Ref 128)... 

Induced draft fans (ID fans) are located near the end of the flue-gas path and provide a negative static pressure below that of atmospheric pressure (creating a partial vacuum). This induces outside air to infiltrate any openings in the boiler. 

Static Chemisorption. Measurements were made by two procedures. In the first, the catalyst was evacuated at ca. 250°C for at least 8 hrs and cooled to the measurement temperature under vacuum. Hydrogen was then admitted at progressively higher pressures and the amount of gas adsorbed after 15-30 min at each pressure recorded. The sample was then evacuated for 30 min and the dosing procedure repeated so as to obtain a measure of the reversibly adsorbed gas. In the second (saturation) procedure, after reduction and evacuation, the catalyst was cooled to the... 

Maignial, L., Pibrot, P., Bonetti, G., Chaintrau, A., and Marion, J. P. (1992). Simultaneous distillation-extraction under static vacuum Isolation of volatile compounds at room temperature. J. Chromatogr. A 606, 87-94. 

For the chemisorption experiments a weighed catalyst sample (wet) was put in a cell and mounted on the Micromeritics 2010 (static) chemisorption instmment. The sample was heated under vacuum to 150°C where it was exposed to hydrogen (0.7 atm) for 0.5 hour. The sample was then evacuated at room temperature, reexposed to hydrogen for 0.5 hour, then evacuated, and cooled to 30°C under vacuum. 

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