Flow decay curve concentration

Figure 5 shows the flow decay for the cell suspension concentration step of Figure 3. The flow rate decays gradually with time with an average final rate around 700 ml/min. Inlet pressure was 90 psi, and there was a 4.6X reduction in volume in about 15 minutes. The flow decay curve in Figure 5 is typical for an IS. coli concentration with a new 0.45 micron pore size microporous membrane.

Figure 5. Flow decay curve for concentrating E. coli whole cells with a 0.45 pm microporous (Durapore) membrane. Inlet pressure was 90 psi. The initial volume was 22.3 liters the final volume, 4.8 liters.

Figure 8. Protein concentration flow decay curves for two different operating conditions with a 100,000 MWCO UF membrane. Key ...

Stopped-flow experiments of luminol chemiluminescence in the system luminol/pure DMSO/tert.butylate/oxygen 109> with independent variations of the concentrations of reactants confirmed the results obtained previously by E. H. White and coworkers 117> as to pseudo-first-order dependence of the chemiluminescence intensity upon each of the reactants. Moreover, the shapes of the decay curves obtained... 

The flow response of a gas cell is an important parameter for sensing applications as it defines the actual response time of the system. The theoretical aspects of determining the time constants from the decay component of the response curve are straightforward. The time constants of the gas cell are calculated from the concentration decay curves (Fig. 6). For example, the time constants for CO are 1.23 and 12.4 s for the HWG and the multipass gas cell,... 

In addition to the continuous-flow reactors, we developed a stopped-flow apparatus to study slow reactions of the NO3 radical. In this apparatus, a series of solenoid valves is used to divert and isolate a flow of gas that contains the reaction mixture. These valves were designed and fabricated in this laboratory by the PI, and ensure that only glass is in contact with the flow. Concentrations of NO3 are then followed as a function of time after the flow is cut off, the data being captured by computer. Figure 1 shows the apparatus in schematic form, while Fig. 2 illustrates decay curves for [NO3] in the absence and presence of C2H4. 

Figure 4-12. Stopped-flow study of the pyridine-catalyzed hydrolysis of acetic anhydride, showing the formation and decay of the acetylpyridinium ion intermediate. Initial concentrations were 0.087 M pyridine, 2.1 x im M acetic anhydride the pH was 5.5 ionic strength, 1.0 M temperature, 25 C. Five hundred data points tabsorbance at 280 nm) were measured in I s. The smooth curve is a ht to Eq. (3-27). Source Data of D. Khossravi and S.-F. Hsu, University of Wisconsin.

Fig. 8 Kinetics of binding of Flutaxl to microtubules at 35 °C. In the stopped-flow device a 1 pM solution of Flutaxl was mixed with 25 pM pure tubulin assembled into microtubules (concentration of sites 20 pM) (final concentrations of 500 nM Flutax and 10 pM sites) in the absence (a) and presence (b) of 50 pM docetaxel. Curve a is fitted to an exponential decay. Inset residues between the experimental and theoretical curves. Taken from [10]...

The diffusion battery consists of banks of tubes, channels, or screens through which a submicron aerosol passes at a constant flow rale. Particles deposit on the surface of the battery elements, and the decay in total number concentration along the flow path i measured, usually with a condensation particle counter. The equations of convective diffusion (Chapter 3) can be solved for the rate of deposition as a function of the particle diffusion coefficient. Because the diffusion coefficient is a monotonic function of particle size (Chapter 2), the measured and theoretical deposition curves can be compared to detennine the size for a monodisperse aerosol. 

Figure 8.1 Exponential decay of the variance of the concentration fluctuations in an oscillatory reaction mixed by a chaotic flow. The smooth curve shows the decay of the passive scalar variance in the same flow, for comparison (from Kiss et al. (2004)).

When a steady stream of fluid flows through a vessel, different elements of the fluid spend different times within it. The time spent by each fluid element can be identified by an inert tracer experiment, where a pulse or a step input of a tracer is injected into the flow stream, and the concentration of the pulse in the effluent is detected. As the reader may quickly infer, the tracer must leave the PFR undisturbed. On the other hand, a step pulse may give rise to an exponential distribution in a CSTR. In the beginning of this chapter, we already demonstrated that PFR behavior approaches that of a CSTR under infinite recycle. It follows that infinite CSTRs in series behave like a PFR. Thus, we conclude that any nonideal reactor can be represented as a combination of the PFR and MFR to a certain degree. First, let us show a representative pulse response curve for each of the ideal reactors in Figure 3.5. As seen in the figure, the response to a step input of tracer in a PFR is identical to the input function, whereas the response in a CSTR exhibits an exponential decay. The response curves as shown in Figure 3.5 are called washout functions. The input function of the inert tracer concentration [/] can be mathematically expressed as... 

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