Static system

Almost everyone has a concept of pressure from weather reports of tlie pressure of the atmosphere around us. In this context, high pressure is a sign of good weather while very low pressures occur at the eyes of cyclones and hurricanes. In elementary discussions of mechanics, hydrostatics of fluids and the gas laws, most scientists leam to compute pressures in static systems as force per unit area, often treated as a scalar quantity. They also leam that unbalanced pressures cause fluids to flow. Winds are the flow of the atmosphere from regions of high to low... 

Molecules should never be treated as static systems which are not able to undergo conformational changes. 

Cool Flames. An intriguing phenomenon known as "cool" flames or oscillations appears to be intimately associated with NTC relationships. A cool flame occurs in static systems at certain compositions of hydrocarbon and oxygen mixtures over certain ranges of temperature and pressure. After an induction period of a few minutes, a pale blue flame may propagate slowly outward from the center of the reaction vessel. Depending on conditions, several such flames may be seen in succession. As many as five have been reported for propane (75) and for methyl ethyl ketone (76) six have been reported for butane (77). As many as 10 cool flames have been reported for some alkanes (60). The relationships of cool flames to other VPO domains are depicted in Figure 6. 

Analytical methods aie utilised by all branches of the chemical iadustry. Sometimes the goal is the quaUtative deterniiaation of elemental and molecular constituents of a selected specimen of matter othertimes the goal is the quantitative measurement of the fractional distribution of those constituents and sometimes it is to monitor a process stream or a static system. Information concerning the various iadividual analytical methods may be found ia separate articles dispersed alphabetically throughout the Eniyclopedia. The articles ate iatroductions to topics each of which is the subject of numerous books and other pubhcations. 

In a static system, the gel-layer thickness rapidly increases and flux drops to uneconomicaHy low values. In equation 6, however, iCis a function of the system hydrodynamics. Typically, high flux is sustained by moving the solution bulk tangentially to the membrane surface. This action decreases the gel thickness and increases the overall hydrauHc permeabiUty. For any given channel dimension, there is an optimum velocity which maximizes productivity (flux per energy input). 

As before, we start with our basic static-system equation... 

Tliiee methods of cooling are in common use, the pressurized cooling Ihiid system, the thermosyphon, and the static system. The static system IS used on smaller compressors and is probably the least common. Cool-... 

Static system The batch-wise employment of ion-exchange resins, wherein (since ion exchange is an equilibrium reaction) a definite endpoint is reached in which a finite quantity of all the ions involved is present. Opposed to a dynamic, column-type operation. 

In this way, a quality system can drive you forward towards world class quality. It is not a static system but a dynamic one, if properly designed and implemented. 

In static systems, the cooling jackets are normally filled with a glycol and water mixture to provide for uniform heat distribution within the cylinder. This system may be used where the AT of the gas is less than 150°F and discharge gas temperature is less than 190°F. 

Even with adequate cleaning procedures it is still necessary to ensure that the inhibitor reaches all parts of the metal surfaces. Care should be taken, particularly when first filling, a system, that all dead ends, pockets, crevice regions, etc., are contacted by the inhibited fluid. This will be encouraged in many systems by movement of the fluid in service but in nominally static systems it will be desirable to establish a flow regime at intervals to provide renewed supply of inhibitor. 

Parameter setup 5.5. (Example) Percolation in static systems... 

Repeat 5.5a-c, only allow the ingredient cells, A, to move freely, using Pra = 1-0, Pb(AA) = 0.4, and J(AA) = 1.0. At each concentration level, 300, 600, 900, and 1200 A cells, average the number of percolating clusters over some constant number of iterations, say 100. Repeat each concentration study 50 times, compute the percentage of percolation at each concentration, and estimate the concentration producing 50% of the time, a percolating system. Compare this value with the result from a static system, as in Example 5.5. 

The reduction procedure described above was carried out in a static system in order to facilitate determination of the extent of reduction in situ. The reduction was monitored gravimetrically using a microbalance (Cl Electronics MK II) and volumetrically by measuring the decrease in hydrogen pressure. Total surface areas were determined by the BET method using nitrogen at 77 K. 

Carbon monoxide chemisorption was used to estimate the surface area of metallic iron after reduction. The quantity of CO chemisorbed was determined [6J by taking the difference between the volumes adsorbed in two isotherms at 195 K where there had been an intervening evacuation for at least 30 min to remove the physical adsorption. Whilst aware of its arbitrariness, we have followed earlier workers [6,10,11] in assuming a stoichiometry of Fe CO = 2.1 to estimate and compare the surface areas of metallic iron in our catalysts. As a second index for this comparison we used reactive N2O adsorption, N20(g) N2(g) + O(ads), the method widely applied for supported copper [12]. However, in view of the greater reactivity of iron, measurements were made at ambient temperature and p = 20 Torr, using a static system. 

On the other hand, for static systems such as UVA IS spectrophotometry, AAS,... 

Adaughterx/weff-daughter and the daughter will be effectively supported by a greater amount of parent than that in secular equilibrium. These dynamical effects will result in greater U-series fractionation than expected in static systems. 

Supercritical fluid extraction can be performed in a static system with the attainment of a steady-state equilibrium or in a continuous leaching mode (dynamic mode) for which equilibrium is unlikely to be obtained (257,260). In most instances the dynamic approach has been preferred, although the selection of the method probably depends just as much on the properties of the matrix as those of the analyte. The potential for saturation of a component with limited solubility in a static solvent pool may hinder complete recovery of the analyte. In a dynamic system, the analyte is continuously exposed to a fresh stream of solvent, increasing the rate of extraction from the matrix. In a static systea... 

Other than possibly for the insensible perspiration they absorb, transdermal patches tend to operate as thermodynamically static systems, meaning as com-positionally fixed systems, from the moment they are applied until their removal. Marketed ethanol-driven estradiol and fentanyl patches are exceptions because they meter out ethanol and drive it into the stratum corneum to propel the absorption process. Compositional steadfastness is still the rule, however, and it is this feature that bestows the zero-order delivery attribute on the ordinary transdermal patch. Drug is present within the patches in reservoir amounts whether or not the reservoir compartment is easily distinguished, for there must be enough drug to sustain delivery over the full course of patch wear. 

The effect of microwave irradiation on the catalytic hydrogenation, dehydrogenation, and hydrogenolysis of cydohexene was studied by Wolf et al. [81]. Optimum conditions for benzene formation were a hydrogen flow, N-CaNi5 catalyst, atmospheric pressure, and 70 s irradiation time. Cydohexane was the main product when the irradiation time was 20 s, or in a batch/static system. 

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