Sequential oscillations

Sequential oscillations in case of ascorbic acid and acetone mixed substrate have been interpreted satisfactorily in terms of FKN mechanism [35]. 

When [G] is fixed and [OA] is varied, the time pause between the sequential oscillations increases with an increase in [OA]. On the other hand, when [OA] is fixed... 

Chemical reaction network is a typical example of complexity, where the reactants can interact in a variety of ways depending on the nature of interaction (chemical as well as non-chemical). Oscillatory reactions involve a number of steps, including positive and negative feedbacks. The complexity leads to periodic as well as aperiodic oscillations (multi-periodic, bursting/intermittency sequential oscillations separated by a time pause, relaxation and chaotic oscillations). The mechanism is usually determined by non-linear kinetics and computer modelling. Once the reaction mechanism has been postulated, the non-linear time-dependent kinetic equation can be formulated in terms of concentrations of different reactants, which would yield a multi-variable equation. Delay differential equations are sometimes used to characterize oscillatory behaviour as in economics (Chapter 14). 

Heilweil et al. [142] reported on sequential oscillations as dominant form of behavior, in mixed-substrate BZ system. They employed manganese sulfate as the catalyst and used three different substrates, MA, AA and EAA. They have monitored the oscillations by measuring the redox potential of the solution in between a platinum electrode and reference electrode as well as bromide concentration with a specific ion electrode, at 31 °C. 

Heilweil, E.J., Henchman, N.J., Epstein, I.R. Sequential oscillations in mixed substrate Belousov-Zhabotinskii systems. J. Ame. Chem. Soc. 101, 3698 (1979)... 

Rastogi, R.P., Mishra, G.P., Das, 1., Sharma, A. Sequential oscillations in bromine hydrolysis controlled oscillators in a closed reactor. J. Phys. Chem. 97, 2571 (1993)... 

Ojha A, Bhathena K (1990) Sequential oscillations with entrainment-type behavior in mixed substrate Belousov-Zhabotinskii (B-Z) system. J Indian Chem Soc 67 806-808... 

The APP technique, recently introduced [50, 51], uses a continuous stirring tank reactor (CSTR) and relies on the sequential perturbation of an oscillating... 

FIG. 1. Phenylephrine (PE)-mediated asynchronous wave-like [Ca2+] oscillations and contraction in the rabbit inferior vena cava. (A) [Ca2+] oscillations recorded in neighbouring smooth muscle cells within the intact vessel are not synchronized between cells as they each display different frequency of oscillations. (B) Individual Ca2+ spike in PE-mediated [Ca2+]j oscillations are wave-like as different regions (1, 2 and 3) in the same ribbon-shaped VSMC experience sequential rise of [Ca2+] in time. (C) The [PE]-dependence in force generation is compared to the [PE]-dependence in the percentage recruitment of cells, the amplitude of the [Ca2+]j oscillations, the frequency of the [Ca2+]j oscillations and the apparent velocity of the recurring Ca2+ waves. (Experimental traces reproduced, with permission from Lee et al 2001.)... 

The periodic recurrence of cell division suggests that globally the cell cycle functions like an autonomous oscillator. An extended model incorporating the sequential activation of the various cyclin-dependent kinases, followed by their inactivation, shows that even in the absence of control by cell mass, this sequence of biochemical events can operate as a limit cycle oscillator [145]. This supports the union of the two views of the cell cycle as dominoes and clock [146]. Because of the existence of checkpoints, however, the cell cycle stops at the end of certain phases before engaging in the next one. Thus the cell cycle looks more like an oscillator that slows down and makes occasional stops. A metaphor for such behavior is provided by the movement of the round plate on the table in a Chinese restaurant, which would rotate continuously under the movement imparted by the participants, were it not for frequent stops. 

Translocation occurs slowly even in the absence of GTP. However, it is greatly enhanced by GTP hydrolysis.3943 402 Even empty ribosome, without tRNAs, but in the presence of GTP and EF-Tu and EF-G, hydrolyze GTP. The ribosome may sequentially bind EF-Tu, then EF-G, oscillating between two differing states.403 Tire movement of mRNA through the ribosome has been plotted using a variety of immunochemical, crosslinking, and chemical footprinting methods.52 404-407... 

SUMMARY We investigate the unsteady motion of mass reservoir formed by the accretion onto the magnetosphere around rotating neutron stars. The unsteady motion of the reservoir induces secondary accretion to neutron star by R-T instability. The nonperiodic or quasiperiodic phenomena of X-ray bursters seems to be related to this property of mass reservoir on the magnetosphere. We classify the typical dynamical state of the reservoir into three types with the parameters which are accretion rate M and angular velocity of neutron star ft. They are nonsequential oscillation sequential periodic (quasi-periodic) oscillation, and chaotic oscillation states. 

These processes can be explained by using a harmonic oscillator-like model (Fig. 13(b)). The energy transfer of an electron excites the molecule to a higher energy level and subsequent energy transfer by other electrons causes further excitation in a sequential process. The molecule dissociates when it exceeds the dissociation barrier. 

If all substrates add to the enzyme before any products are released, the mechanism is defined as sequential. If substrates add in an obligatory order, the mechanism is called sequential ordered. If there is no obligatory order of addition of substrates or release of products, it is called sequential random. When one or more products are released before all the substrates have been added, the enzyme will exist in two or more stable forms between which it oscillates during the reaction this type of mechanism is therefore called Ping Pong. If isomerization of stable, as distinct from transitory (e.g., EAB EPQ in Example 9.5), enzyme forms occurs, the term Iso is added to the designation of the mechanism. 

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