Comminution approach

Phosphate in combination with NaCl has a beneficial effect on the waterbinding capacity of processed meat products for a detailed description, see Schmidt.227 The effect of phosphates is suggested to be alterations in pH or ionic strength, sequestration of metal ions, dissociation of actomyosin and depolymerisation of myosin.103,104,228,229 However, before action, added phosphates must be hydrolysed by muscle phosphatases or non-enzymatically. Belton et al.230 studied the hydrolysis of pyrophosphate and tripolyphosphate in comminuted chicken meat using 31P NMR spectroscopy, and found that the rate of hydrolysis was dependent on the length of ageing period of the muscle as well as the presence of NaCl. Li et al.231 studied the hydrolysis of various types of phosphates in intact chicken muscle with a similar approach by 31P NMR spectroscopy and thereby demonstrated differences in rate of hydrolysis of various phosphates. The findings of these studies... 

The approach chosen goes back to the work of Rumpf [9], Krekel and Polke [10] and Peukert and Vogel [11]. Rumpf was the first who analyzed comminution processes by distinguishing between machine and material parameters. He stated that the main parameters affecting the comminution result are stress mode, stress intensity and number of stress events as well as particle size and shape and material composition. This approach in which a mill is not regarded as a... 

Unlike fracturing, this approach should cause only moderate disruption of the coal matrix and might not lead to complete comminution, but this method could be envisioned as a prelude to coal grinding. Removal of material from structural boundaries would yield a more friable, "soft" coal structure. The leaching of fine mineral particles from the coal matrix results in a more porous structure and should also improve the coal s grindability. The prior removal of some mineral matter would also reduce the coal s abrasiveness. 

There are a large number of methods (Table 2) to prepare nanoparticulate systems. These depend to a large extent on the material (polymer, protein, metal, ceramic) that will form the basis of the carrier. One can, in essence, consider three approaches to their production (0 by comminution (in the case of solids, milling, and in the case of liquids, high pressure emulsification) (ii) molecular self-assembly, such as that occurs with polymeric surfactants to form polymeric micelles or with dendrons to form dendrimeric aggregates and (iii) precipitation from a good solvent as shown in Figure 6. 

To assess the impact of IDR on enzyme kinetics, the value of intrinsic kinetics (V" and K) and mass transfer (Deff) parameters must be evaluated. Several strategies have been proposed to approximate the value of the intrinsic kinetic parameters. A reliable experimental procedure is the one proposed by Benaiges et al. (1986) which is basically based on comminuting the support to obtain particles so small than IDR becomes negligible (very low Osp see Eq. 4.54). Kinetic parameters can be determined then with that comminuted biocatalyst to have an estimate on the intrinsic values. Effectiveness factor can be approached then to the ratio of initial rates for the intact and comminuted biocatalyst (Kobayashi and Laidler 1973). An obvious drawback of this approach is that not always a biocatalyst particle small enough can be obtained to be free of IDR (effectiveness factor = 1). If a smooth correlation exists between effectiveness factor and particle size, extrapolation to size zero could give an approximate value and intrinsic kinetic parameters can be... 

The fabrication of encapsulation systems may be carried through mechanical processes, in general based on a top-down approach to the disruption of larger systems into homogeneously sized particles or droplets with desired properties, or by physicochemical processes, based on a bottom-up approach to the assembling of molecular building blocks into structured systems (i.e., micelles, microemulsions, and some biopolymeric nanoparticles), as well as by a mixed approach, where molecular assembly and comminution processes are combined together (i.e., liposomes, multilayer emulsions, and some biopolymeric nanoparticles). 

The top-down approaches to the production of sub-micrometric particulate systems are mainly based on comminution by mechanical size reduction techniques, which require minimal use of... 

Because ball milling reaches a limit, it is impossible to make very fine particles by this method. Therefore, growing particles from vapor or solution phases has been the preferred approach to making fine dispersions. This growth method is also attractive because the particles can be controlled in shape, and can also be grown to the same size, which is useful in many applications. For example, sintering of particles is eased if the particles are nearly equal in diameter. Such fine, equal particles cannot be produced by comminution. In this section we discuss the several processes which have been developed for growing particles. 

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