Tangential apparatus

Seventy grams (0.25 mole) of oleic acid (Note 1) is placed in the dropping funnel H of the tangential apparatus (Fig. 2 Note 2). The thionyl chloride distillation is started and regulated (Note 2) the upper part of the column should be filled with the vapor, and reflux should be constant and steady. The acid is dropped in at the top of the column over a period of 35 minutes (120 g. per hour). The product that collects in the receiver I contains about 25-27% of thionyl chloride (Note 2) if the heated lower leg K is employed. The product in... 

Tangential apparatus, 37, 67 Tartaric acid, 35, 50 Tartaric anhydride, diacetate oe d-, 35, 49... 

The surface force apparatus (SFA) is a device that detects the variations of normal and tangential forces resulting from the molecule interactions, as a function of normal distance between two curved surfaces in relative motion. SFA has been successfully used over the past years for investigating various surface phenomena, such as adhesion, rheology of confined liquid and polymers, colloid stability, and boundary friction. The first SFA was invented in 1969 by Tabor and Winterton [23] and was further developed in 1972 by Israela-chivili and Tabor [24]. The device was employed for direct measurement of the van der Waals forces in the air or vacuum between molecularly smooth mica surfaces in the distance range of 1.5-130 nm. The results confirmed the prediction of the Lifshitz theory on van der Waals interactions down to the separations as small as 1.5 nm. 

The Grace-Davison jet-cup attrition test is often used to test the friability of catalysts (e g., Weeks and Dumbill, 1990 Dessalces et al., 1994). The respective jet-cup apparatus is sketched in Fig. 5. The catalyst sample is confined to a small cup, into which air is tangentially added at a high velocity (about 150 m/s). Some authors (e.g., Dessalces et al., 1994)... 

FIGURE 1-6 A portion of a Golgi apparatus. The smooth-mem-braned cisternae appear beaded. The many circular profiles represent tangentially sectioned fenestrations and alveolate vesicles (primary lysosomes). Two of the latter can be seen budding from Golgi saccules (arrows). Mitochondria and a dense body (secondary lysosomes) are also present. x60,000. 

The simplest and most commonly used convection apparatus consists of a disc electrode rotating with a constant angular velocity u [1-5]. The disc sucks the solution toward its surface, much in the way a propeller would as the solution approaches the disc, it is swept away radially and tangentially (see Fig. 14.1). The transport of the reacting species to the disc occurs both by convection and diffusion. Though the mathematics are complicated, the rate of transport can be calculated exactly for an infinite disc. A particularly nice feature of this setup is the fact that the transport is uniform so that the surface concentration of any reacting species is constant over the surface of the electrode. 

Figure 12.7b is a sketch of an apparatus that may be used to measure streaming potential. As was the case with electroosmosis, the capillary can be replaced by a plug of powdered material between perforated electrodes. An applied pressure difference p across the capillary causes the solution to flow through the capillary, thereby tangentially displacing the part of the double layer in the mobile phase from the stationary part. 

Figure 6.1 shows the optical alignment of the apparatus used by the present author (204). Two projections of this aligment are given in this figure. The sectional plane of Fig. 6.1a is defined by the axis of the rotor unit (coaxial cylinder apparatus) and a radial direction. The sectional plane of Fig. 6.1b, however, is tangential to the surface of the internal cylinder. 

At the entrance to the annular gap the light-beam is confined in the radial direction by the edges of the cylinders (gap width 0.25 mms in the described apparatus) and by the rim of the circular hole D (0 = 2 mms) in the tangential direction. Two millimeters along the circumference of... 

Fig. 4 Schematic of a fluidized bed coating apparatus (A) bottom spray with Wurster column insert (B) top spray technique (C) tangential spray technique. (From Ref...

Dynamic crystallization under precise control of shear and temperature was studied in a prototype apparatus specially developed. The whole cell, similar to a Couette viscometer, was made out of glass. The inner cylinder rotated at a controlled speed, CO, while the outer wall was fixed. A double-mantel with a circulation of water allowed precise control of the temperature. Temperature of cocoa butter in the cell was measured with a chromel-alumel thermocouple. Measures were recorded with a data acquisition system. Shear rate imposed to cocoa butter in the system could be estimated from the rotation speed of the inner cylinder, assuming that the fluid is Newtonian and incompressible. There is no normal speed, only tangential speed. The shear rate, y> in the specimen is a single function of the radiu. In the rest of this work, shear in the cell was characterized by its average value, y, calculated by integration over the cell thickness (7). 

Byram and Martin [97] used external vertical cylinders with tangential slots oriented to produce rotating flow about a fire source. They examined two sets of equipment of diameters and heights, 33 and 183 cm, or 66 and 335 cm, respectively. Burning alcohol pools within their apparatus, they reported visible fire whirls up to 300 cm tall with inner fire tube columns 2 cm in diameter. They observed horizontal velocities at the surface of the inner column of about 9 m/sec ( 6000 rpm) and vertical velocities to 18 m/sec. 

This brief overview describes some experiences using tangential-flow and dead-end ultrafiltration techniques for concentration of eukaryotic cells, proteins and virus. The data and conclusions presented here have been drawn from process development work employing available apparatus and should be considered preliminary, rather than definitive or exhaustive. Previous ultrafiltration systems have been described (1-14) for both bench and pilot scale separations of proteins and virus. This paper primarily summarizes work on cartridge and sheet filter systems and their application to processes requiring sterilizable and contained systems. 

The American Society of Lubrication Engineers has issued a compilation of friction and wear devices [2] which describes 234 different pieces of apparatus. However, the measurement of friction is governed by only a few basic principles, and consequently an appreciation of the practical techniques employed is not difficult to acquire. To quote Bowden and Tabor [3] Any method which will give at the same time a measure of the normal load between surfaces and of the tangential force necessary to cause sliding can be used to determine the coefficient of friction."... 

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