Peak time

Most flow injection analyses use peak height as the analytical signal. When there is insufficient time for reagents to merge with the sample, the result is a split-peak, or doublet, due to reaction at the sample s leading and trailing edges. This experiment describes how the difference between the peak times can be used for quantitative work. 

To analy2e premixed turbulent flames theoretically, two processes should be considered (/) the effects of combustion on the turbulence, and (2) the effects of turbulence on the average chemical reaction rates. In a turbulent flame, the peak time-averaged reaction rate can be orders of magnitude smaller than the corresponding rates in a laminar flame. The reason for this is the existence of turbulence-induced fluctuations in composition, temperature, density, and heat release rate within the flame, which are caused by large eddy stmctures and wrinkled laminar flame fronts. 

Business and production cycles. Certain types of operations and facilities have predictable production cycles for example, some facilities may have scheduled annual turnarounds or a seasonal production peak. You are likely to get better cooperation and results if you re able to schedule the installation during moderate periods rather than at peak times. 

The nurse should check the patient for hypoglycemia (see Table 49-1) at the peak time of action of the insulin (see Summary Drug Table Insulin Reparations). Hypoglycemia, which can develop suddenly, may indicate a need for an adjustment in the insulin dosage or other changes in treatment, such asa change in diet. Hypoglycemic reactions can occur at any time but are most likely to occur when insulin is at its peak activity. 

This is what we started out to prove, l.e.- AH equals the area of the peak times the total heat flow to the sample. 

There are several examples in the literature of GFC now being utilized for small molecule analysis (17). However, in this case, attempts to obtain monomer concentrations for kinetic modelling were frustrated by irreproducible impurity peak interference with monomer peaks, time varying refractometer responses and insufficient resolution for utilization of a reference peak. This last point meant that injected concentration would have to be extremely reproducible. 

Virus Peak Age Peak Time Duration Transmission Symptoms... 

The time of the peak can also be used to roughly estimate the absorption rate constant. If it is assumed that ka is at least 5 x kei, then it can be assumed that absorption is at least 95% complete at the peak time that is, the peak time represents approximately five absorption half-lives (see Table 1). The absorption half-life can then be calculated by dividing the time of the peak by 5, and the absorption rate constant can be calculated by dividing the absorption half-life into 0.693. 

Example. Inspection of Fig. 10 gives a peak time of about 2.5 hours. The absorption half-life can be estimated to be 0.5 h and the absorption rate constant, to be 1.4h-1. 

This peak time is less as becomes smaller and meaningless when = 1. We can also derive the rise time—time for y(t) to cross or hit the final value for the first time—as ... 

Now, go to the LTI Viewer window and select Import under the File pull-down menu. A dialog box will pop out to help import the transfer function objects. By default, a unit step response will be generated. Click on the axis with the right mouse button to retrieve a popup menu that will provide options for other plot types, for toggling the object to be plotted, and other features. With a step response plot, the Characteristics feature of the pop-up menu can identify the peak time, rise time, and settling time of an underdamped response. 

Coupling with its intravenous pharmacokinetic parameters, the extended CAT model was used to predict the observed plasma concentration-time profiles of cefatrizine at doses of 250, 500, and 1000 mg. The human experimental data from Pfeffer et al. [82] were used for comparison. The predicted peak plasma concentrations and peak times were 4.3, 7.9, and 9.3 qg/mL at 1.6, 1.8, and 2.0 hr, in agreement with the experimental mean peak plasma concentrations of... 

Figure 16.4 A more advanced ICAT design uses an acid-cleavable spacer arm to facilitate elution of labeled peptides from a (strept)avidin affinity column. The use of 14C isotopes instead of deuterium labels permits precise reverse phase separations prior to mass spec that show no elution peak time differences between isotope-labeled and normal atom-labeled peptides.

Tominaga et al. [682,683] studied the effect of ascorbic acid on the response of these metals in seawater obtained by graphite-furnace atomic absorption spectrometry from standpoint of variation of peak times and the sensitivity. Matrix interferences from seawater in the determination of lead, magnesium, vanadium, and molybdenum were suppressed by addition of 10% (w/v) ascorbic acid solution to the sample in the furnace. Matrix effects on the determination of cobalt and copper could not be removed in this way. These workers propose a direct method for the determination of lead, manganese, vanadium, and molybdenum in seawater. 

A typical exothermic profile for HEMA polymerization is shown in Figure 1 which also exemplified the definitions of peak time and stall time. 

Table 2 summarizes the peak times for the photopolymerization of HEMA. Among initiators with structures known, the ranking of more active initiators, in terms of decreasing polymerization rate was ... 

Table II. Peak time of the Photo-DSC of HEMA monomer mix with different of UV initiators. Formulation HEMA/Glycerine/EGDMA/initiator 85/15/0.34/x...

Table II also lists the peak times from these studies. As expected, the rate of polymerization (by peak time) increased as the concentration of initiator was increased until screening effects started to appear (between 0.34 to 0.68 %). In term of rate of polymerization, the relative ranking ofinitiators remained the same and 2,2-dimethoxy-2-phenyl acetophenone was the most active.

Figure 2 further demonstrates the relationship between rate of polymerization (peak times), and the initiator concentration. Although trivial, it is interesting to note that the polymerization rate correlates well with the overlap between the emission... 

Figure 2. The effect of initiator on the peak time in the Photo-DSC for HEMA polymerization.

The Effect of Light Source on Curing Rate. As stated earlier, Sylvania F4T5 was the lamp used in the standard Photo-DSC measurements and this lamp had a broad emission spectrum centered at 350 nm. When an alternate lamp (GE F4T5) with an emission peak at 365 nm was used, the ranking of initiators, in terms of peak time, remained the same. Table III lists representative results from these experiments. The emission spectrum of this GE lamp was also shown in Figure 3. 

Table IV lists the solubility parameters (3) of these diluents (3) and the peak times for polymerizing HEMA monomer mixes with different diluents. The...

Table IV. Peak times in the Photo-DSC of HEMA with different diluents at 5, 15 and 25 % Formulation HEMA/EGDMA/BME/Diluent at 85/0.34/0.17...

The Effect of Crosslinker Concentration on the Rate of Polymerization. Ethylene glycol dimethacrylate is used most frequently as the crosslinker for HEMA formulations useful in contact lens manufacturing. To demonstrate the effect of crosslinker concentration on the curing rate, formulations derived from HEMA/Glycerine/BME at 85/15/0.17, while varying EGDMA (from 0.34 to 0.68), the peak times were about the same (3.73 and 3.61 minutes respectively). This is reasonable due to the similarity in molecular structure of the crosslinker and the monomer, and the low amount of crosslinker used. The possible presence of other crosslinker, such as the dimerization product of HEMA, is even less a factor to be considered in polymerization kinetics, due to low concentration (normally much less than 0.1 %, in-house information). 

The effect of NO exposure time on the time at which the N2 and N2O signals attain a maximum is shown in Fig. 16. It is seen that the model of NO reduction predicts that N2 formation peaks about 0.5 s after the peak in the N2O formation and that the peak times for both products decline by about 0.5 s as the NO exposure time is increased from 5 to 30 s. These trends are in good agreement with the data. It should be noted that since a product analysis could be taken only once every 0.5 s, it was not possible to determine product peak positions with an accuracy of better than 0.5 s. Consequently, both the predicted difference between... 

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