Capsule shape

A retained its compact capsule shape no matter what the initial pH of the dissolution medium. Moreover, the dissolution rate of phenytoin from preparation A was pH-independent. Preparation B, however, broke down into fine particles. When the initial pH was neutral, these particles rapidly dissolved. As the initial pH was lowered, these fine particles precipitated. Since these precipitated particles then dissolved very slowly, it would appear that the precipitate was not the freely soluble sodium phenytoin, but the poorly soluble acid form of phenytoin. Since capsule A did not disintegrate or deaggregate, most of the sodium phenytoin was not exposed to the lower pH media and, as a result, was not converted to its very slowly dissolving acid form. 

Ammonia is a gas that can be readily converted to liquid form and stored as such under pressure. For fertilization, it can be injected directly into the soil from capsule-shaped tanks. I grew up in the Midwest and still spend some time there for family reasons. An ammoiua tank being towed through farmland behind... 

A more recent development in tablet coating involves the use of gelation as the coating material to produce geltabs. If a tablet is compressed as a capsule-shaped unit prior to gelatin coating it is called a gelcap... 

The ORO 5 Push-Stick technology is designed to deliver high doses of poorly water-soluble or slowly dissolving drugs at a controlled rate [50,52], The basic system consists of two layers, typically in a capsule-shaped tablet surrounded by a semipermeable membrane however, the system... 

Calculated from optimum theoretical capsule shape, each part a cylinder with a hemispherical end. 

Intraruminal boluses are cylindrical or elongated capsule-shaped devices that are typically 7- to 16-cm long and 1 to 3 cm in diameter, dependant on the species for which they are intended. They must be designed to provide some mechanism for long-term... 

Capsule-shaped Ir(l) and Rh(l) cationic complexes with a triphosphinocaltx[6]arene as a multidentate ligand were recently synthesized (Figure 33). These organometallic bis-caltxarene complexes showed dynamic behavior with size-selective molecular encapsulation, which was confirmed by variable-temperature P H NMR measurements in the presence of various molecules. X-ray crystal analysis showed that the calix[6]arene moiety adopted the same pinched-cone conformation as the non-coordinated caltxarene. Molecules such as CFlj,Cly or CICH2CH2CI are too small to fit the cavity of the iridium and rhodium bis-calixarene complexes and cannot restrict the dynamic behavior at 25 °C. On the contrary, molecules such as X2CHCHX2 (X = C1 or Br), benzene, toluene, o- or w-xylene just fit in the cavity and show the dynamic behavior. Finally, large molecules (p-xylene, cumene, mesitylene, etc.) could not enter the cavity. 

Capsule shape Of Bmchythecium kind Cylindrical, curved Cyhndrical, ciurved... 

An extended investigation was done to determine relationships between two main hydrodynamic characteristics of capsule flow - capsule/liquid velocity ratio, Vc/ v< hydraulic gradient, ic, and parameters of capsule-liquid-pipe system, e.g. pipe diameter, D, capsule/pipe diameter ratio, d/D, capsule length/diameter ratio, l/d, capsule/carrier liquid density ratio. Pc Ipo, capsule shape, B, concentration of solids, Cv, liquid viscosity, po and liquid mean velocity, v<,. However, majority of the research was focussed on straight horizontal pipe. The knowledge about behaviour of capsules in bend or inclined pipe sections has been up to now insufficient. 

Fig. 3. Effect of capsule shape and pipe curvature on velocity ratio v<.A of heavy cylindrical capsule in train.

For diameter ratio d/D varied from 0.55 to 0.75, it can be approximated by value a 1.07. Effect of pipe curvature on velocity ratio, Vc /Vo, depends on flow velocity, Vo, and capsule shape, B, see Figs. 2 and 3. For low flow velocity the velocity ratio in bend is slightly higher compare to velocity ratio in the straight pipe section, on the contrary it is lower for flow velocities several times higher than threshold velocity, It could be explained by incomplete contact of capsule and pipe bottom in bend and by additional resistance between pipe side wall and c sule ends for higher flow velocities. This explanation is supported by comparison of behaviour of flat ended and bullet-shaped capsules and very low effect of bend on spherical and wheeled capsules. 

Fig. 5. Effect of capsule shape B and pipe curvature on hydraulic gradient ic of heavy capsule train.

The increment of hydraulic gradient due to the pipe curvature is for capsule flow similar to that of liquid alone. It depends on flow velocity and central angle of the bend and, of course, on capsule parameters (see Fig. 4). Effect of capsule shape is illustrated in Fig. 5. 

The cellulose capsules can be manufactured by the dipping and forming method, employed for the manufacture of hard gelatin capsules. Shaped pins are dipped into HPMC solution of which temperature is maintained over room temperature. The pins are picked up from HPMC solution, cooled at room temperature, and dried by a warm air blow. HPMC base adhered to the pins gelled immediately to form the shape of capsule because carrageenan, a gelling agent, was added. 

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