Periodate reduction

In an attempt to elucidate the reaction sequence by which the cyclohexanepentols are oxidized, we recorded simultaneously the time curves of periodate reduction and of malonaldehyde production during the oxidations. By this procedure, it is, in fact, possible to propose a reaction sequence for (1 d)-1, 2, 5/3, 4-cyclohexanepentol. 

No hypotheses can be advanced for the sequences involved in the oxidation of cyclohexanepentols which react even more slowly with periodate than does (+)-quercitol. For instance, when the all-trans l 3, 5/2, 4-cyclohexanepentol (33) is oxidized (Figure 6), production of malonaldehyde starts very early and the time curve of periodate reduction indicates a very complex reaction. Nor is it possible to analyze satisfactorily the curves obtained with (1 l)-1, 2, 4/3, 5-cyclohexane-pentol (34) or with dl-1, 2, 3, 4/5-cyclohexanepentol (35) [this is the configuration predicted for the (1 D)-entantiomorph (41)]. 

Gy Progressive anemia over 6-week postirradiation period reduction in erythrocyte numbers and weight of spleen 5... 

Hoelscher TJ, Edinger JD. Treatment of sleep-maintenance insomnia in older adults Sleep period reduction, sleep education, and modified stimulus control. Psychol Aging 1988 3 258-263. 

S-shaped current potential curves emerge when a surface phase transition of an organic adsorbate is coupled with a faradaic reaction of some electroactive species. As a representative of such a system, the periodate reduction on Au(lll) single crystal electrodes in the presence of camphor was studied [160], Camphor adsorbed on Au(lll) electrodes exhibits two first-order phase transitions upon variation of the electrode potential [161]. In a cyclic voltammogram, the phase transition manifests itself in a pair of needle-like peaks (Fig. 28 (A)). Between the peak pairs, a condensed, well-ordered camphor film exists. At more negative potentials, the camphor coverage is low, while the state of the adsorbate at positive potentials beyond the second phase transition is not yet known. The small hystereses between the respective anodic and cathodic peaks are caused by the finite nucleation rate of the respective thermodynamically stable phase. 

The theoretical predictions prompted an experimental search for electrochemical Turing structures that was successful shortly after. The first experimentally observed Turing structures are reproduced in Fig. 71. They stem from the periodate reduction on Au in the presence of camphor whose homogeneous dynamics was introduced in Section 3.2.2. The patterns could be made visible with surface plasmon microscopy (cf. Fig. 54). When changing the composition of the electrolyte, the wavelength of the patterns changed, in accordance with the theoretical result that the wavelength depends on the system s parameters, but not on the dimension of the... 

We have also used the periodic reduction method to predict with good accuracy the 3D structure of vibrationally bonded molecules. It should be stressed though, that in principle it is not necessary to use periodic reduction. As shown in Fig. 9 the RPO s of the IHI system are stable also in 3D, one can find bound quasi-periodic orbits and quantize them semiclassically directly without resorting to periodic reduction. 

The appearance of a zinc deficiency as a result of extensive surface erosion or of loss of the A horizon by land leveling operations (29, 30, 127) may partly be ascribed to higher pH values below the surface horizon but principally to a loss of the principal soil reservoir of zinc as well as to a loss of the organic matter, the latter being necessary for the periodic reduction of the hydrous oxides to make the occluded heavy metals available. That the deficiency on these lands is not simply a loss of zinc is shown by the frequent failure of a single zinc fertilization to prevent zinc deficiency on land which has had the surface soil removed by leveling (29, 30, 127) or erosion (J29). 

Given the quasiperiodic orbit embedded in the continuum one can proceed to identify in configuration space the coordinates (u,v,w). In principle then, using classical mechanics one is able to identify also in a coplanar reaction a best set of adiabatic coordinates. It may also happen that the bend and stretch frequencies are similar in magnitude. In such a case the periodic reduction method cannot work. However usually the rotational motion will still be much slower than the stretches and bends and so could still be treated adiabatically. Such a scheme may be termed a quasiperiodic reduction method.It has been applied successfully for adiabatic barriers and wells.However there is a price to pay, it is more tedious. 

One of the theoretical shortcomings of the periodic reduction method is the rather arbitrary definition of the bend angle. Although, as was the case to date, one may a posteriori verify that the adiabatic reduction is justified by comparing bend frequencies with stretch frequencies, it is still desirable to construct a method which a priori does not have this ambiguity. One possibility is using the quasiperiodic reduction method outlined in this section. However, as we shall point out a much simpler method may be based on stability analysis of periodic orbits in 3D. 

Strasburger, E. (1894) The periodic reduction of the number of chromosomes in the life-history of living organisms. Annals of Botany, 8 281-316. 

Dehydration of Silicic Acid by Periodic Reduction of Pressure... 

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