Induction time-dependent

The investigation on the influence of the temperature on the hydrolysis rate of the ortho-bromophenol into the catecholate shows that the induction time depends strongly on the temperature from about 5 hours at 135°C to 1 hour at 165°C and 1/2 hour at 180°C (Fig. 17). 

This reaction results in the precipitation of nearly the entire amount of the product if apolar, non-protic solvents are chosen [53], This particle formation, however, needs a certain induction time, dependent on solvent and temperature. 

As we saw in section 2.2, suitably sensitive experiments penetrate the induction period and reveal the time constant In other experiments the time interval between shock wave heating and some detected manifestation of the accelerating reaction measures an induction time, ti. To a good approximation, is inversely proportional to cf). However, the detailed interpretation of this induction time depends upon the initiation rate and also upon the sensitivity of the experiment and whether or not the strict exponential growth has continued to the time... 

Induction time depends on the type of polymer (molecular structure, morphology). Table 1.9, while the rate of oxygen absorption is proportional to the mass of the polymer and not to its surface. It decreases with increasing film thickness [52]. 

There is little evidence for the operation in reactions of the inducto-meric effect, the time-dependent analogue of the inductive effect. This may be so because the electrons of the delocalized system, and are thus not so susceptible to the demands of the reagent. 

The maximum rates of crystallisation of the more common crystalline copolymers occur at 80—120°C. In many cases, these copolymers have broad composition distributions containing both fractions of high VDC content that crystallise rapidly and other fractions that do not crystallise at all. Poly(vinyhdene chloride) probably crystallises at a maximum rate at 140—150°C, but the process is difficult to foUow because of severe polymer degradation. The copolymers may remain amorphous for a considerable period of time if quenched to room temperature. The induction time before the onset of crystallisation depends on both the type and amount of comonomer PVDC crystallises within minutes at 25°C. 

The reaction time depends on the quality of the potassium hydroxide employed. An induction period is often observed when older potassium hydroxide samples are used, possibly because surface formation of carbonates reduces the solubility of the salt in acetonitrile. An attempt was made to monitor the cinnamonitrile reaction by GLC, following loss of starting... 

Digraph Model and evaluation of components or systems Quantitative, time-dependent multiphased inductive complexity incrc.iM.- rapidly practical only tor simple systems... 

A further complication arises with Ingold s suggestion" that both the inductive and resonance effects are composed of initial state equilibrium displacements that reveal themselves in equilibrium properties like dipole moments and equilibrium constants and of time-dependent displacements produced during reaction by the approach of an attacking reagent, observed rate effects being resultants of both types of electronic effects. Hammett, however, claims that it is not necessary or possible to make this distinction. 

Fig. 21 Annealing time dependence of the integrated DPLS intensity for iPS in the induction period of crystallization at 135 °C [15]...

Nickel chloride has been reported to induce DNA strand breaks in CHO cells [435] in a concentration, which did not significantly injure normal cellular division, and DNA-protein cross-links, which were concentration- and time-dependent and preferentially occurred in cells in the late S phase of the cell cycle [436], The nickel cross-linked proteins included nonhistone chromatin proteins, nonhistone DNA-binding proteins and a 30 kDa protein that comigrated electrophoretically with histone HI. Moreover, blocking of cell growth in S phase [249] and induction of DNA repair synthesis in CHO cells [437] and reduction in the fidelity of DNA synthesis [438, 439], have been reported. 

S02 is a very stable oxide and its thermal decomposition is only measurable at the very high temperatures attained in a shock tube. A study357 of the time-dependence of light emission from shock-heated S02/Ar mixtures in the region of 3000 °K has shown that S02 is removed in accordance with a sigmoid-shaped concentration-time curve typical of a chain or autoaccelerated reaction. The induction period observed357 prior to the onset of detectable decomposition corresponded closely with the time for the formation of a fixed concentration of O (or SO) calculated from the rate expression (Table 24) for the unimolecular decomposition... 

The pressure dependence, as before, is derived not only from the perfect gas law for p, but from the density-pressure relationship in Z as well. Also, the effect of the stoichiometry of a reacting gas mixture would be in Z. But the mole fraction terms would be in the logarithm, and therefore have only a mild effect on the induction time. For hydrocarbon-air mixtures, the overall order is approximately 2, so Eq. (7.46) becomes... 

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