Bottle-necking

Reaction (9) is a bottle-neck in the oxidation of hydrogen bromide. As fast as HOOBr is formed by this slow reaction it is consumed in the rapid reaction (70). But no matter how rapid... 

As is well known, many experimental smdies have been made extensively to search for a possibility of encapsulation of atoms by hollow fullerenes since the discovery of Cgo by Kroto et al. [143]. These methods, however, usually require high tempratures and high pressures, or ion implantation. The yields are also as low as 0.4—10 %. In this sense, the efficiency in our case is much higher and the required conditions are much milder with collison energy of 2 eV. However, the boron substimtion is a bottle neck, although Smalley and co-workers successfully synthesized boron-doped fullerenes [144]. 

At present dedicated TCSPC FLIM boards are commercially available. They are compatible with most LSMS and are easily synchronized with the scanning microscope and pulsed laser. These boards, often plug-in cards for PCs, have a lower deadtime than do the conventional TCSPC electronics intended for use in spectroscopy and the memory bottle neck of the histogram-ming memory has been removed [21, 22], Consequently, these dedicated boards provide higher acquisition speeds. 

For production plants, the loading of the plant with the required amount of ice (which should correspond to a full charge) is time consuming and several tests should be avoided. For a sufficient estimation of the water vapor transport and the bottle necks of it, one test can be carried out as described here ... 

The pores grow in size with exposure time Low tortuosity factors Low pore surface area per total paint volume Few bottle-neck structures... 

Pj, is a projection operator ensuring the proper spatial symmetry of the function. The above method is general and can be applied to any molecule. In practical application this method requires an optimisation of a huge number of nonlinear parameters. For two-electron molecule, for example, there are 5 parameters per basis function which means as many as 5000 nonlinear parameters to be optimised for 1000 term wave function. In the case of three and four-electron molecules each basis function contains 9 and 14 nonlinear parameters respectively (all possible correlation pairs considered). The process of optimisation of nonlinear parameters is very time consuming and it is a bottle neck of the method. 

FIGURE 1.5 Uncontrolled champagne cork popping out of a bottle the cloud of fog forming right above the bottle neck clearly appears ( Jacques Honvault). 

There is another general lesson that we can learn from these experiments. If our proteins are the product of contingency, most probably the pathway to their prebiotic synthesis cannot be reproduced in the laboratory. This is indeed the bottle neck in the bottom-up approach to the origin of life. 

The bottle neck macromolecular sequences Questions for the reader... 

The bottle neck of the bottom-up approach is the difficulty of reproducing on paper and/or in the laboratory those processes which have been moulded by contingency - such as the synthesis of specific macromolecular sequences. 

McBain accounted for hysteresis by assuming that the pores contained a narrow opening and a wide body, the so-called bottle-neck shape. His model asserts that during adsorption the wide inner portion of the pore is filled at high relative pressures but cannot empty until the narrow neck of the pore first empties at lower relative pressures during desorption. Therefore, for bottle-neck pores the adsorption isotherm corresponds to the equilibrium condition. However, the model proposed by McBain ignores the question of how condensation into the wider inner portion of the pore can occur once the narrow neck has been filled at low relative pressures. 

On thermodynamic grounds pore-size distributions are measured using the desorption isotherm, (see equations 8.8 and 8.9). The exception to this are bottle-neck pores exhibiting type E hysteresis. In this case the equilibrium isotherm is that of adsorption because the unstable state is associated with the condition that the wide portion of the pore is unable to evaporate until the narrow neck empties. Regardless of which isotherm is used, however, the mathematical treatment remains the same. 

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