Looping transitions

An attractive hypothesis suggests that the GH loop transition precedes or allows the extemalization of VP4, which would be required for the formation of the uncoating intermediate particles. Remember,... 

Montante G, Lee KC, Brucato A, Yianneskis M. (1999) An experimental smdy of double-to-single-loop transition in stirred vessels. Can. J. Chem. Eng., 77(4) 649-659. 

Figure 7. Three-dimensional representation of one octant of a looping transition. The resonant magnetic field for each angular orientation is plotted in magnetic field-space, where each vector firom the origin to a point is graphed according to the x, y, and z components. Calculation parameters are the same as in Figure 6. The figure is reproduced from Fig. 7 of Gaffney and Silverstone [21], with permission of the publisher.

Figure 8. Intensity of resonances in a looping transition as a function of magnetic field. The intensity factor (j axis) is shown for transitions between levels 2 and 3, using Eq. (4). Calculation parameters were D = 0.27 cm E = 0.0162 cm, and microwave frequency = 9.23 GHz). The figure is reproduced firom Fig. 11 of Gaffney and Silverstone [21], with permission of the publisher.

PUbrow JR, Sinclair GR, Hutton DR, Troup GJ. 1983. Asymmetric lines in field-swept EPR Ci looping transitions in ruby. J Magn Reson 52(3) 386-399. 

Gaffiiey BJ, Silverstone HJ. 1998. Simulation methods for looping transitions. J Magn Reson 134(l) 57-66. 

In the microcanonical ensemble, the signature of a first-order phase transition is the appearance of a van der Waals loop m the equation of state, now written as T(E) or P( ). The P( ) curve switches over from one... 

Figure 31 shows the proposed Longuet-Higgins loop for the cyclopentadienyl cation. It uses the type-VI Ai anchors, with the type-VII B structures as transition states between them. This situation is completely analogous to that of the radical (Fig. 23). Since the loop is phase inverting, a conical intersection should be located at its center—as required by the Jahn-Teller theorem.

Figure 39. Benzene to benzvalene reaction, (a) Assuming that the prebenzvalene structure is a transition state. The two benzvalene isomers are anchors, (b) Assuming that prebenzvalene is an intermediate, A two-anchor loop results, compare Figure 12.

The hydration shell is formed with the increasing of the water content of the sample and the NA transforms from the unordered to A- and then to B form, in the case of DNA and DNA-like polynucleotides and salt concentrations similar to in vivo conditions. The reverse process, dehydration of NA, results in the reverse conformational transitions but they take place at the values of relative humidity (r.h.) less than the forward direction [12]. Thus, there is a conformational hysteresis over the hydration-dehydration loop. The adsorption isotherms of the NAs, i.e. the plots of the number of the adsorbed water molecules versus the r.h. of the sample at constant temperature, also demonstrate the hysteresis phenomena [13]. The hysteresis is i( producible and its value does not decrease for at least a week. 

A variation on the transit time method is the frequency-difference or sing-around method. In this technique, pulses are transmitted between two pairs of diagonally mounted transducers. The receipt of a pulse is used to trigger the next pulse. Alternatively this can be done using one pair of transducers where each acts alternately as transmitter and receiver. The frequency of pulses in each loop is given by... 

A modification of the direct process has recentiy been reported usiag a ckculating reactor of the Buss Loop design (11). In addition to employing lower temperatures, this process is claimed to have lower steam and electricity utihty requirements than a more traditional reactor (12) for the direct carbonylation, although cooling water requirements are higher. The reaction can also be performed ia the presence of an amidine catalyst (13). Related processes have been reported that utilize a mixture of methylamines as the feed, but require transition-metal catalysts (14). 

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