Pumping, modulated

Feed Pump Module Feed Pump Module Feed Pump... 

Sakamoto et al. [143] described an automated, near real-time analysis with microprocessor-controlled syringe pump modules for the determination of... 

Mobile phases employed for the separations are housed in a cartridge and delivered to the LC columns through a set of binary HPLC pumps (Shimadzu Corporation), as shown in Figure 6.2. The pumps provide a flow rate accuracy of 2% or 2 fiL (whichever is greater) in constant flow pumping mode, with a flow rate precision of 0.3%. A degasser (two channels internal volume of 195 /.d. /channel) is also housed in the pump module employed to minimize the occurrence of air bubbles. 

Ketoconazole Efflux pump modulator and/or CYP inhibitor Can be used to demonstrate the impact of intestinally mediated efflux/metabolism on permeability estimates [114]. 

The microreactor system consists of a pumping module (R2+) and a four-channel heated component (R4). Two independently conducted flow streams are mixed in a T-piece and driven through a convection-flow coil (CFC, volume 10 ml) made of poly(fluoroacetate) (PFA). After the CFC, the flow is guided through Omnifit glass columns [41] packed with immobilized scavengers. 

Flow Rate Accuracy. One of the key performance requirements for the pump module is the ability to maintain accurate and consistent flow of the mobile phase. This is necessary to provide stable and repeatable interactions between the analytes and the stationary phase [8,9]. Poor flow rate accuracy will affect the retention time and resolution of the separation. The flow-rate accuracy of the pump can be evaluated simply by calculating the time required to collect a predetermined volume of mobile phase at different flow rate settings. For example, the flow-rate accuracy at 2 mL/min can be verified by using a calibrated stopwatch to measure the time it takes to collect 25 mL of effluent from the pump into a 25-mL volumetric flask. A calibrated flow meter can be used to determine the flow rate as well. The typical acceptance of the flow rate accuracy is listed in Table 11.1. A steady backpressure may be required, depending on the requirement of the system. 

Modifier Addition System. In the case where a continuous supply of modifier was desired, the base system was upgraded to perform continuous modifier addition with the addition of a second syringe pump module and a valving package (Isco SFE System 2200). The valving package consisted of two check-valves, a mixing tee, and the hardware necessary to install them in the system. Both pump modules were... 

TABLE 8.25 Pumping Module Associated Cost Factor Additions, in Percent (Total module cost = base cost x total modular factor.)... 

Pumps. Pump base costs were found in Fig. 8.8. Here pump product of capacity, gpm times the respective head, psi, gives a factor that is used to fix each particular pump base cost. Again, as in all the other equipment module spreadsheets, the associated equipment table factors—including piping, electrical, steel, concrete, and instrumentation—are multipliers to derive the full pump module cost. Of course labor and indirect costs are factored as well in Table 8.25. 

Limited local inhibition of these transporters by using polymeric inhibitors could reduce such systemic risks and side effects. Efflux pump modulating polymers and surfactants mentioned in this review have been distinguished between nonionic, ionic and thiolated polymers. 

Some naturally occurring polymers have been reported to exhibit efflux pump modulating properties. For example, a drug delivery system based on chitosan has been shown to nearly double the oral bioavailability of the P-glycoprotein substrate rhodamine 123 in vivo in rats in comparison with buffer control (Foger et al. 2006c). 

In summary it can be said that there are a lot of possibilities available to overcome the efflux pump-mediated absorption barrier in the intestinal tract. Further, more selective or more potent inhibitors will follow but it has to be carefully decided for each drug or therapy which type or class of inhibitor or efflux pump modulator might be best suited. Also drug delivery systems combining different efflux pump modulating properties have to be investigated in the future. 

Reliasil column (2.0 mm x 250 mm) on a Beckman 126 Pump Module with a Shimadzu (SPD-6A) detector (Figure 1). The column was eluted for 2 min with solvent A (0.1% trifluoroacetic acid in water) and then followed by a discontinuous gradient to solvent B (10% methanol. 10% water, 80% acetonitrile) at a flow rate of 0.15 ml/min at 35°C. The gradient used was as follows ... 

High pressure liquid chromatography (HPLC) was used to identify phenols and separate the products of the reaction. The system included a Dupont 870 pump module, 850 absorbance detector, and a 4.6 mm x 25 cm Zorbax ODS liquid chromatography column (all from DuPont and Co., Wilmington, DE). Analysis of 2-CP was achieved under the following conditions mobile phase 33% MeOH in water at 1.5 mL/min PCP analysis mobile pliase 50% MeOH in water at 1.5 mL/min UV detection for 2-CP and PCP at 254 nm. 

FIGURE 10.42. The dependence of the triplet PA of PFO at 1.43 eY upon the pump modulation frequency for an undoped PFO film (symbols) and one containing 8% PtOEP (solid line). The doped sample is scaled to the undoped sample for comparison. Inset Phosphorescence decay of a PtOEP/PFO blend following excitation. The symbols show experimental results and the solid line a fit to exponential decay. (From Ref. 72.)... 

The first term in (11) is the fV-photon Kerr Hamiltonian [35], giving rise to optical bistability, and % is related to the (2/V — l)-order susceptibility of the medium. The second term in (11) represents coherent pumping modulated by classical function/(f). Similarly, as in the previous section, we assume that the excitation has a constant envelope i.e. /(f) = 1. Applying the procedure analogous to that described in the previous section we get the following equations... 

Figure 10.1. Diagram of the inside of the Waters Alliance 2690 pump module after opening the front panel, showing the two pump heads and various components. Note that while the layout on different manufacturers pumps is not the same, most pumps consist of the same general components and convenience features such as the slide-out tray allowing easy assess for maintenance. Diagram courtesy of Waters Corporation.

These limitations have led to the development of forced flow development systems and to the technique of overpressured thin layer chromatography. The special feature of this method is that the adsorbent layer is in a completely sealed unit and the solvent is delivered under pressure at a controlled oniform flow-rate by a pump module as in HPLC. Thus, overpressured TLC (OPTLC) takes place in the absence of a vapour pressure and the migration of the solvent front is free from both evaporation and adsorption effects. As the eluant is delivered under controlled conditions it is possible to optimise the separation conditions by adjusting the flow-rate of the eluant and also to undertake continuous development proeedures. 

Circulate buffer through the system (buffer vessel pumping module buffer vessel) in order to remove air. 

Connect the column to the chromatography skid (or other type of pumping module). 

Problem pumping module A pumping issue could potentially disturb the obtained elution profile. Stability of the obtained flow rate should be controlled if an online flow meter is available. 

Site C(dd-water pump Warm-water pump Module pump power Total pump power Gross turb/gen power Optimized plant Net power Power output output (nom) (ann.avg) (Investment M )... 

A fiber laser may behave as a driven second-order system by introducing a time-dependent parameter into the laser cavity, such as loss modulation, gain (or pump) modulation, phase modulation, etc. For example, driving the mode locking element in a mode locked fiber laser at slightly below the cavity fundamental frequency has been observed to result in chaotic behavior, characterized by severe amplitude jitter on the optical pulses generated. 

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