Tailoring disadvantages

The stmcture and composition of DLC may vary considerably and, as a result, so do some of its properties. This is not necessarily a disadvantage since it is often possible to control and tailor these properties to fit specific applications (for instance, the index of refraction). Its properties are generally similar to those of diamond, such as high hardness and chemical inertness, but different in some key areas. As opposed to diamond, DLC has a variable index of refraction and variable electrical conductivity, both a function of hydrogen content. 

Apart from butter or butter oil most fats that are used in biscuits are defined in terms of their physical and chemical properties. Fat suppliers are skilled at producing products with controlled physical and chemical properties from a range of raw materials. The baker can either buy fat on a physical and chemical specification, e.g. solid fat index, slip melting point, and not to contain lauric fat, or on an origin basis, e.g. to be coconut oil. The advantage of the botanical specification is that the item is a commodity and can be obtained from numerous sources. The disadvantage of this approach is that the product is tailored for a particular use. 

The pore size of the membrane could also be controlled independently of the porosity by altering the size of the salt particles (Fig. 5a). Membranes with high surface area/volume ratios were produced and the ratio was dependent on both salt weight fraction and particle size (Fig. 5b). In addition, the crystallinity of PLLA membranes can be tailored to that desired for each application. These characteristics are all desirable properties of a scaffold for organ regeneration. The major disadvantage of this technique is that it can only be used to produce thin wafers or membranes (up to 2 mm in thickness). A three-dimensional scaffold cannot be directly constructed. This problem may be circumvented however, by membrane lamination. 

Pretreatment for fillers. When used as a surface treatment for fillers or reinforcing materials, in which the silane is applied to the filler or fibre before incorporation into a resin matrix, the same factors as for pretreatment primers apply. In addition, the particle size and the absence/presence of water are important, and in a sense this application is only a variation on the former. It should be noted that silane treated fillers may have, or impart, different rheological properties to non-treated fillers, particularly particulates. A major disadvantage of this approach is that a general purpose silane may have to be used by a manufacturer rather than one specifically tailored to the use of a particular resin type and less than optimum properties are likely to be achieved in some cases. 

There are different possibilities for performing whole cell biotransformations with several enzymes. Each enzyme can be produced from another strain. To carry out the desired reaction, these strains are combined in different amounts which depend on the particular enzyme activities. Disadvantages of this method are diffusion problems and the membrane barrier [126]. Alternatively, all enzymes can be expressed in one single host strain. This can be reached by means of recombinant DNA techniques in several ways The genes can be expressed under one single promoter or under different promoters. Furthermore, it is possible to express all genes from the same promoter but with different copy numbers. Using these methods it is possible to create tailor-made catalysts for manifold purposes. 

Inorganic chemists investigating reaction mechanisms are often at a disadvantage relative to organic chemists. Many inorganic reactions of interest occur too fast to be accessible by normal techniques. Furthermore, one generally cannot tailor Inorganic complexes to obtain mechanistic parameters. 

Porosity can be an advantage or a disadvantage in ceramic powders, depending upon the processing and final application. Tailoring of the pore size distribution is very important for catalytic substrates, because access to the catalytic sites depends on these diflusional pathways. 

Disadvantage(s) Less adaptable to changes of Tailored to narrow range... 

Once the work has been broken down in activities, relative values must be assigned to each of them in a uniform manner that can be related to simple physical units. The values could be assigned either as work units (W.U. s) related to field labor or as a fraction of the value for the entire work. Each approach has advantages and disadvantages and the Project Manager must have the flexibility and foresight to tailor the monitoring system to the project needs. 

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