Case study channel

Hancox, J.C. and Mitcheson, J.S. (2006) Combined hERG channel inhibition and disruption of trafficking in drug-induced long QT syndrome by fluoxetine a case-study in cardiac safety pharmacology. British Journal of Pharmacology, 149, 457 159. 

Knowledge of the geometry and mathematical description of a screw Is required to understand the analysis of the functional sections of the screw and the troubleshooting of case studies. In Chapter 1 the geometry and mathematical descriptions are presented. Also In this chapter, the calculation of the rotational flow (also known as drag flow) and pressure flow rates for a metering channel Is Introduced. Simple calculation problems are presented and solved so that the reader can understand the value of the calculations. 

Diagnosing and eliminating a problem that occurs due to an improperly operating extruder can be difficult and time consuming. This section contains several case studies where improperly designed processes created contamination defects in the final articles. The axial pressure profiles of the metering channels for these case studies and other studies in the next chapters were calculated using the method described in Section 9.2.1. The simulated axial pressure profiles are shown with solid lines while the estimated pressure profiles are shown by dashed lines. 

The restriction was mitigated by modifying the screw as outlined in the case study in Section 11.10.1. That is, the depth of the melt channel of the barrier section was increased to that of the solids channel at the entrance, and it was tapered into the depth of the melt channel over 2 diameters. The barrier flight was removed for the first 2 diameters and blended in with the melt channel, the shallower of the two channels in this region. The barrier flight for the next diameter was blended into the original undercut. With this modification the restriction still existed but it was spread over a three-diameter length of the screw instead of over half of a diameter. 

The decompression section in the screw downstream from the blister was where a liquid plasticizing additive was injected into the extruder. The large channel depth in this section was used to accept the additional volume and to control pressure. The sections downstream from the first meter were not the focus of this case study and will not be discussed further. 

As demonstrated in the case study, an optimal channel depth exists where the specific rate is at a maximum. Designing the screw at this maximum specific rate is typically the desire. The parabolic shape of the specific rate curve shown in Fig. 13.10 was caused by the rotational rate increasing iineariy with increasing channel depth see Eq. 7.58. This increase in rotational rate causes the overall rate to increase. The pressure flow increases with the cube of the channel depth, and... 

Figure 13.12 Schematic of the channel depths for the original and modified screws for the PS resin case study...

There have been numerous studies of the effects of gas streams on the thicknesses of liquid films flowing in contact with them. Cases studied in the literature refer mainly to gas/film flow in vertical tubes or channels or horizontal pipes. The latter case will not be considered here. The gas/film flows may be countercurrent, cocurrent upwards, or cocurrent downwards. Only the most important studies can be discussed here. 

For the present case study, a 16-channel laboratory-made parallel reactor was used (Fig. 10.6). Other laboratory-scale reactors were also used with the same libraries to check the specificity of each testing system [13]. 

In this section, single-component diffusion in zeolites [20,87-92], with the help of the case study of the diffusion of p-xylene and o-xylene in H-ZSM-11 and H-SSZ-24 zeolites, is discussed [90], SSZ-24 is a 12-MR zeolite that was first obtained as the silicon counterpart of AlP04-5, and, later, was obtained as a borosilicate (B-SSZ-24), which could be exchanged with A1 to yield the H-SSZ-24 zeolite [111], This zeolite exhibits the AFI framework, which embodies a one-dimensional channel network without cavities, consisting of parallel 12-MR channels with a free-channel diameter, ow = 7.0A [112], Additionally, ZSM-11 encloses an intersecting two-directional 10-MR channel system, where the two-dimensional channel system is characterized by the free-channel diameter, ow = 5.8 A [112],... 

Optimal control theory aims to maximize or minimize certain transition probabilities, called objectives, such as the production of a specified wave function at a specified time tf, given a wave function F(t0) at time f0. The general principles of OCT are best understood via a case study due to Rice and coworkers [104, 119], illustrated in Figure 4.2, in which the objective is to concentrate the wave function in one of the exit channels of a bifurcating chemical reaction ... 

Case studies were reported (170,174) of large-diameter (> 15-ft) towers with sieve trays not reaching the expected efficiency. Maldistribution was cited as the culprit or at least one of the causes. Improving liquid flow patterns, often among other modifications, was the fix. The only other evidence that channeling adversely affects tray efficiency comes from the above-mentioned theoretical models. 

Conversely, in many other cases studied, the stabilization of hydrophobic clathrasils, zeosils and very high silica zeolitic frameworks is induced by neutral guest molecules that only fill the channels and cavities (11, 12). They are thought to form a solid solution on the growing crystals and thereby lower the chemical potential of the framework (13). The energy required to stabilize such a framework mostly derives from weak Van der Waals bonds between the guest molecule and the siliceous framework (12). In that respect, the temptation of ZSM-5 with alcohols (14) or ethers (15) would also have to be interpreted in terms of a pore filling model. 

Lacidipine A Long-Lasting Calcium Channel-Blocking Drug Case Study 187... 

---