Lengthening residence time

Probably inspired by the fact that the Jet Loop Reactor has successfully been applied in industry, Gaddis and Vogelpohl [111] proposed an impinging stream loop reactor, as shown in Fig. 7.4. It seems that their main purpose is to lengthen residence times in the reaction vessel. The principles of the reactor s operation are somewhat similar to those of the Air Left Reactor (ALR). The only difference lies in the fact that... 

In favorable cases, when processing corncobs, the ESCHER WYSS reactor could be operated without sulfuric acid by relying for the catalysis on innate carboxylic acids (mostly acetic acid and formic acid) liberated from the raw material, but this required a lengthened residence time, thus reducing the throughput. 

Even higher shear rates in the extruder cannot prevent laminar flow in the screw flights and therefore resultant unmixed particles being carried over the shearing sections. Lengthening of the residence time in the barrel also has to be restricted to limit unacceptable temperature build-up, which would result in scorched compound. It is thus necessary to have an effective means of... 

Flash photolysis studies with absorption or delayed fluorescence detection were performed to compare the binding of ground and excited state guests with DNA.113,136 The triplet lifetimes for 5 and 6 were shown to be lengthened in the presence of DNA.136 The decays were mono-exponential with the exception of the high excitation flux conditions where the triplet-triplet annihilation process, a bimo-lecular reaction, contributed to the decay. The residence time for the excited guest was estimated to be shorter than for the ground state, but no precise values for the rate constants were reported. However, the estimated equilibrium constants for the... 

The dry-based capacity of the equipment is 1.78 kg s-1, while the recovery efficiency of the particles is 98-99%. It is reported that the conditions of fluid dynamics are very stable and that the equipment can be operated with a very high concentration of dense phase. It is clear that at least one of the researchers major intentions in the design of the dryer is to lengthen the residence time of the particles. 

The dryer shown in Fig. 6.12 can only be operated in batch, and this is its major disadvantage. However, lengthening the residence time by circulating the solid material employed is an effective measure. 

The k(E) vs. E curve obtained for bromobenzene using variable residence time [717] also differed from that for bromobenzene of the earlier study [22]. As before, the rate coefficients based on varying the residence time were lower than those from the earlier study of metastable ions. The critical energy was found to be 2.76 0.02 eV and the transition state was loose . Comparison was made with the corresponding neutral decomposition and it was concluded that the ionic decomposition had a marginally lower frequency factor and the lower critical energy (2.76 eV compared with 3.5 eV). The kinetic shift with the bromobenzene ion was about 0.2 eV on lengthening the residence time from 1.13 ps to 5.03 ps. 

It is evident that increasing the mobility simultaneously raises the EOF, and the relative velocity for each pair of zones is reduced along with the resolution. On the other hand, if the analyte migrates in an opposite direction to the EOF, the resolution increases because the residence time in the capillary is prolonged and the effective migration distance is lengthened, so that even components with very small differences in mobility can be separated from each other. 

With liquid samples, Xhe flow-rate strongly influences the pervaporation process. The lower the flow-rate is, the longer will be the residence time in the donor chamber of a given volume of sample and the closer to equilibrium will be the analyte mass transfer. The flow can be stopped when the sample is in the donor chamber to allow steady-state mass transfer. This situation is not desirable because it lengthens the separation unduly. Instead, a fresh sample can be passed through the donor chamber as often as required provided the volume of sample available is not limited. 

The Br elevation observed in the hair and nails of AD subjects could also result from other causes. It has been shown that treatment with lithium carbonate results in elevated hair Br (Campbell et al., 1986). Perhaps other medications commonly taken by AD patients have similar effects. It has also been shown that Cl depletion greatly lengthens the elimination half life of Br (Raws, 1983). If AD subjects were on salt-restricted diets, the longer residence time of Br in the body could lead to increased Br levels in the hair and nails, and perhaps in the brain (Wance et al., 1990). 

Attempts at lengthening intravascular resident time of the solution and limit third spacing have resulted in the development of hypertonic crystalloid solutions. An example of a hypertonic solution is 3% NaCI ( hypertonic saline ). It has been suggested that the increased electrolyte... 

A pharmacokinetic study in patients with rheumatoid arthritis found that etodolac 600 mg daily did not affect the AUC of methotrexate, but the duration of exposure was lengthened (mean residence time increased from... 

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