Multiple-pass

Absorption spectroscopy provides a means to study particular details about a monolayer. Transmission spectroscopy is difficult because the film, which is thin, absorbs little. Gaines [1] describes multiple-pass procedures for overcoming this problem. Reflection spectroscopy in the UV-visible range has been reported for lipid monolayers [150,151] and in the IR range for oleic acid [152]. 

In most coatiag operatioas a single layer is coated. Whea more than one layer must be appHed one can make multiple passes, or use tandem coaters where the next layer is appHed at another coatiag statioa ioimediately foUowiag the dryer sectioa for the previous layer, or a multilayer coatiag statioa can be used. Slot, extmsion, sHde, and curtain coaters are used to apply multiple layers simultaneously. SHde and curtain coaters can apply an unlimited number of layers simultaneously, whereas slot and extmsion coaters are limited by the complexity of the die internals. 

On homogenization, the lysate may drastically increase in viscosity due to DNA release. This can be ameliorated to some extent using multiple passes to reduce the viscosity. Alternatively, precipitants or nucleic acid digesting enzymes can be used to remove these viscosity-enhancing contaminants. 

A major disadvantage of this system is the limitation of the single-pass gas-chlorination phase. Unless increased pressure is used, this equipment is unable to achieve higher concentrations of chlorine as an aid to a more complete and controllable reaction with the chlorite ion. The French have developed a variation of this process using a multiple-pass enrichment loop on the chlorinator to achieve a much higher concentration of chlorine and thereby quickly attain the optimum pH for maximum conversion to chlorine dioxide. By using a multiple-pass recirculation system, the chlorine solution concentrates to a level of 5-6 g/1. At this concentration, the pH of the solution reduces to 3.0 and thereby provides the low pH level necessary for efficient chlorine dioxide production. A single pass results in a chlorine concentration in water of about 1 g/1, which produces a pH of 4 to 5. If sodium chlorite solution is added at this pH, only about 60 percent yield of chlorine dioxide is achieved. The remainder is unreacted chlorine (in solution) and... 

Multiple passes of carriage necessary to cover mandrel. Programmed relationship between carriage motion and mandrel rotation necessary. Reversal of carriage must be timed precisely with mandrel rotation. Dwell at each end of... 

Spacing of the plates and their angles is a part of the design using the manufacturers data. Multiple pass designs can result in higher recovery efficiencies. The units can be designed/ins tailed for vertical or horizontal flow. 

In modem, packaged horizontal FT boilers, the furnace is the most important heat-transfer component, typically providing 50 to 60% of the total heat transfer from only 30% or so of the total available heating surfaces. This level of heat transfer, coupled with the additional heat extraction obtained by the various multiple-pass designs (four passes is a practical maximum) provide efficiencies of 80 to 83% GCV. As a result, there generally is little additional benefit to be obtained from the use of economizers or air heaters, especially when using oil-fired boilers, which can operate at up to a 3% or so higher efficiency level compared to gas-fired units. 

There are several techniques available for mechanical thrombolysis. The most common is probing the thrombus with a microguidewire. This technique appears to be useful in facilitating chemical thrombolysis. Alternatively, a snare (e.g., Amplatz Goose-Neck Microsnare, Microvena, White Bear Lake, MN) can be used for multiple passes through the occlusion to disrupt the thrombus. " A snare can also be used for clot retrieval, mostly in simations in which the clot has a firm consistency or contains solid material. ... 

The position of the zone x is measured from the leading edge of the ingot. The distribution for multiple passes can also be emulated from a material balance, but in this case the leading edge of the zone encounters solid corresponding to the composition at the point in question for the previous pass. The multiple-pass distribution has been numerically calculated (Pfann, Zone Melting, 2d ed., Wiley, New York, 1966, p. 285) for many combinations of k, Ul, and n. Typical solute-composition profiles are shown in Fig. 20-6 for various numbers of passes. 

Batch or Fed-Batch Operation This mode of operation is typical of biologicals and juice processing where high solicfs and low fluxes require multiple passes, and batch operation is characteristic of the manufacturing process. Formulas in Table 20-19 can be used to calculate the required volume reduction factor X, diafiltration volumes... 

Continuous Operation This mode of operation is typical of paint recovery, whey processing, and wastewater processing where high solids and low fluxes require multiple passes, and continuous operation is allowed by the manufacturing process. For a feed concentration Cp, a volumetric concentration factor X (= retentate flow/feed flow), and retention R, the outlet retentate concentration is... 

However, they are susceptible to channeling and also fractnring of the beads. Tough cells require multiple passes to achieve a desired yield. 

The choice of plate type (reverse, single pass or multiple pass) will depend on the liquid flow-rate and column diameter. An initial selection can be made using Figure 11.28, which has been adapted from a similar figure given by Huang and Hodson (1958). 

The liquid throw is the horizontal distance travelled by the liquid stream flowing over the downcomer weir. It is only an important consideration in the design of multiple-pass plates. Bolles (1963) gives a method for estimating the liquid throw. 

A pure, saturated, vapour will condense at a fixed temperature, at constant pressure. For an isothermal process such as this, the simple logarithmic mean temperature difference can be used in the equation 12.1 no correction factor for multiple passes is needed. The logarithmic mean temperature difference will be given by ... 

The spray aeration method comprises a grid network of piping and nozzles over a pond or basin. Contaminated water is simply sprayed through the nozzles and into the air to form droplets. Mass transfer of the contaminant takes place across the air-water surface of the droplets. Mass transfer efficiency can be increased by multiple passing of the water through the nozzles. This method has three disadvantages ... 

The velocity on the tube side can be modified by changing the single-pass design to a multiple-pass configuration. In this case Ft = 1 in Equation (b). From formulas in McCabe, Ft depends on t2 (or At2), hence the necessary conditions derived previously would have to be changed. The fluids could be switched (shell vs. tube side) if constraints are violated, but there may well be practical limitations such as one fluid being quite dirty or corrosive so that the fluid must flow in the tube side (to facilitate cleaning or to reduce alloy costs). 

The total rate of electron transfer is calculated by summing over the probability of the transitions for the multiple passes of the system through... 

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