Periodate formation

Completion of the run, after 30-40 hours, is indicated when a few drops of the solution show an alkaline reaction to phenol-phthalein. No harm is done if the electrolysis is carried a few hours beyond this point however, after excessively long periods, formation of polymeric material lowers the yield and renders purification of the product rather troublesome. 

The process of catalyst oxidation and reduction can be treated as a reversible phase transition [136]. It is to this process that the authors of recent investigations [37, 47-49, 85] ascribe critical effects. When studying kinetic self-oscillations in the oxidation of hydrogen over nickel [37] and measuring CPD, the authors established that the reaction performance oscillates between the states in which oxygen is adsorbed either on the reduced or on the oxidized nickel surface. Vayenas et al. [47-49], by using direct measurements of the electrochemical activity of 02 adsorbed on Pt, showed that the isothermal self-oscillations of the ethylene oxidation rate over Pt are due to the periodic formation and decomposition of subsurface Pt oxides. A mathemati-... 

When cimetidine is treated with 3% H202 at room temperature or exposed to oxygen at 50°C for short time periods, formation of sulfoxide is observed. Refer to the following ... 

There is evidence for isomerization of chemisorbed propylene oxide to acrolein on silver and for surface polymer formation on metal oxide catalysts (11,12). Formation of a surface polymeric structure has also been observed during propylene oxidation on silver (13). It appears likely that the rate oscillations are related to the ability of chemisorbed propylene oxide to form relatively stable polymeric structures. Thus chemisorbed monomer could account for the steady state kinetics discussed above whereas the superimposed fluctuations on the rate could originate from periodic formation and combustion of surface polymeric residues. 

Note in the case of multiple publications, only the first publication has been noted here except in the case of republication in book form of texts initially published in periodical format. In the case of texts published in part before appearing in full, only full publications are given here. 

The oscillation process, the theoretical principles of which are described in Experiment 96, leads to the periodic formation of free iodine, which is characterised by the blue color of the starch-iodine complex. ... 

A pyranoside reacts with two molecules of periodate formate is one of the products. A furanoside reacts with only one molecule of periodate formate is not formed. 

In the same year as Wehnelt s first publication on his current-interrupter, E.W. Caldwell [17] and H.Th. Simon invented independenlty a different version of the electrolytic interrupter. Their interrupter used a small hole drilled in a wall separating the cathodic and anodic compartments of an electrolysis cell. As in the Wehnelt interrupter, the periodic formation of a gas film regularly interrupts the current. 

Bowman Jr, R.C., Ryba, E.L. and Freeman, B.D., Characterization of prototype sorption cryo coolers for periodic formation of liquid and solid hydrogen. Advances in Cryogenic Engineering, 1994, 39 p. 1499. 

Ill period from October 1951 to December 1957 The average production of petroleum dropped sharply from 4,200 tons/day, at the beginning of the period, to 200 tons/day, at the end of the period. Formation pressure declined futher, reaching 7.5 kg/cm. Intensive encroachment of the reservoir by formation water took place with water cut rising to 76%. The number of pumping wells decreased from 228 to 132. 

Figure 8.2 shows schematically an example of a perfect lattice matched system in which atomic diameters are identical, and an example of a mismatch in which atomic diameters are drawn differing by 15% and for which a dislocation has formed. In a poorly matched system, atoms across the interface are in poor registry. This leads to high interfacial stress and high interfacial energy. Interfacial stress is relieved by periodic formation of dislocations [49]. In general, a lattice match of better than approximately 15% is required for a coherent interface [49]. 

Ibarrondo, F.J., Torres, M. and Coates, T.D. (1999). Periodic formation of nascent lamellae is driven by changes in the stable F-actin pool of polymorphonuclear neutrophils after stimulation with chemotactic peptide and cross-linking of GDIS or GD61. Cell Motil. Cytoskeleton 44, 234—247. 

Detailed studies of the coadsorption of oxygen and carbon monoxide, hysteresis phenomena, and oscillatory reaction of CO oxidation on Pt(l 0 0) and Pd(l 1 0) single crystals, Pt- and Pd-tip surfaces have been carried out with the MB, FEM, TPR, XPS, and HREELS techniques. It has been found that the Pt(l 0 0) nanoplane under self-osciUation conditions passes reversibly from a catalytically inactive state (hex) into ahighly active state (1 x 1). The occurrence of kinetic oscillations over Pd nanosurfaces is associated with periodic formation and depletion of subsurface oxygen (Osub)- Transient kinetic experiments show that CO does not react chemically with subsurface oxygen to form CO2 below 300 K. It has been found that CO reacts with an atomic Oads/Osub state beginning at temperature 150 K. Analysis of Pd- and Pt-tip surfaces with a local resolution of 20 A shows the availability of a sharp boundary between the mobile COads and Oads fronts. The study of CO oxidation on Pt(l 0 0) and Pd(l 1 0) nanosurfaces by FEM has shown that the surface phase transition and oxygen penetration into the subsurface can lead to critical phenomena such as hysteresis, self-oscillations, and chemical waves. 

Finally, if Eq. (1.13) gives < 0, it does not necessarily mean the absence of the film in the system. The situation is also possible (e.g., very small a or k) when the film is formed however, its positive stationary thickness is impossible. These non-stationary unsteady systems can exist either at partial covering of the surface or in the regime of periodic formation and dissolution of the film (type 3). The behaviour of such systems is somewhat similar to the unsteady electrochemical systems (see Chap. 5). 

In Fig. 10 the sensitized polymerization is demonstrated for a multilayer sample consisting of compound 5a doped with one mole percent of dye III. Spectrum 1 of Fig. 1 a was measured prior to irradiation of the sample and only shows the dye absorption at about 500 nm. Spectra 2-7 were monitored after exposure of the multilayer to the 514 nm line of an argon laser for different time periods. Formation of polymer is indicated by the occsirrance of an additional broad absorption in the visiUe. 

Figure 5.13 shows the electron microphotograph of as-polymerized PTeOX irradiated with 1.0 MGy. The existence of a rippled feature peipoidicular to the fibre axis is observed with a period of ca. 6(K) A, indicating the periodical formation of voids as mentioned m the case of irradiated PTOX. 

Vibration Period Format 9/s Format 10/s Deviation % Format 9/s Format 10/s Deviation %... 

Torsion While the torsional electromechanical response was successfully explained via the deformation of the BriUuoin zone, another possible explanation for the bandgap oscillations may be the periodic formation of Moire patterns due to registry mismatch between the different walls of the multi-waUed tubes, which have a different curvature. In order to rule out this possibility, DFT calculations within the LSDA were used to show that the interlayer coupling is weak and the electronic structure of the individual walls resembles that of single-waUed nanotubes for different intertube orientations (Nagapriya et al. 2008). 

During galvanostatic oxidation of formic acid on a rhodium electrode periodic changes in potential were observed under certain conditions [6, 55]. Periodic effects have also been described in electrochemical oxidation processes [62, 187, 188]. It has been suggested that the potential fluctuations may be due to periodic formation and oxidation of an adsorbed layer of organic substances on the electrode [55]. 

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