Filter sizing software

One of the expert systems/computational tools for sizing worthwhile highlighting is the filter sizing software - called FILOS - which has been on the market for some years now. It is regularly optimised and it combines the available theoretical basics with a manageable amount of laboratory tests for determination of the key parameters which characterise the filtration process. This system is a very useful additional tool to the conventional lab-scale tests for filter sizing [7]. 

The approach outlined in this chapter points a way to the design of continuous filters, which takes some account of the effects of physical properties and operating conditions. The models used for the calculations and simulations are based on fundamental theories and practical results of varying complexity, all of which are sufficiently well developed to facilitate filter sizing and other process calculations. The simulations, which make use of the Filter Design Software described in Chapter 5, show how the detailed calculation procedures described can be implemented to investigate the influence of process variables on filter cycle performance. 

The X-ray powder diffraction (XRPD) pattern of a sample of atorvastatin calcium, Form-I, was recorded at room temperature on Bruker D8 Advance diffractometer (Karlsruhe, Germany), using nickel-filtered Cu Ka radiation. The sample was mounted in a polymethylmethacrylate sample holder, and analyzed in a continuous mode with a step size of 0.01° and a step time of 1 s over an angular range of 3-40° 26. The XRPD results are found in Fig. 1.18 and in Table 1.3, being evaluated with the DIFFRACplus EVA (version 9.0) diffraction software. 

Lasentec Labtec 1000 is a laboratory instrument that covers the size range from 0.7 to 250 pm in 28 size channels. The data are generated as scanned counts an empirical frequency distribution created from classification of chords from randomly oriented particles. Software can convert these chords to a spherical equivalent distribution on the assumption that the chords were generated from an assembly of spherical particles this software contains a filter system to reject improbable data that would tend to skew the distribution to a coarser size. A discrimination... 

In some cases, a medium sized set of compounds (a hundred up to several thousand) are considered as candidates for lead structures. This set can emerge for example from a screening experiment, from filtering databases with other software tools, or from varying a known inhibitor or lead structure in several ways. Here, the required output is a ranked list of the compounds giving the medicinal chemist a hint which compounds should preferably be investigated further. 

The powder X-ray diffraction patterns of the samples were recorded on a Philips PW 1820 diffractometer using nickel filtered Cu Ka radiation. The crystallinity of the samples was calculated by measuring the area under the (5 3 3) peak taking original NaY sample as reference. The unit cell size (So) of the samples were determined from XRD patterns using PDPll software. 

The size distribution of the liposomes is determined by dynamic light scattering (DLS) with a Dynapro apparatus (http //www.wyatt.com). DLS is a hydrodynamic method by which one determines the rate of diffusion of particles through the solvent. The hydrodynamic radius is defined as the radius of a theoretical hard sphere that diffuses with the same speed as the particle under examination. The measurement is performed at 25° and requires about 2 /ul of the extruded liposome suspension diluted in 18 /ul of liposome buffer (final lipid concentration in the range of 0.1 roM). Ten autocorrelation functions are sequentially measured, from which the size distribution of the liposome is determined using the Dynamics v5 software from Dynapro. A complete measurement takes a few minutes. Figure lA shows typical size distributions of extruded liposomes as determined by DLS. Figure IB shows how the actual hydrodynamic radius of the liposomes varies with the pore size of the polycarbonate filter. 

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