Top-down process

Figure 1.3 Today s bottom-up (equipment dominance) and sketch of future top-down (process dominance) approaches in process development.

Development projects should change from top-down processes towards bottom-up processes (see Extension method is top down). 

Particles can either be produced by bottom-up processes (e.g. precipitation) or top-down approaches (e.g. wet milling). In these processes particle-particle interactions become relevant when the particle size is below 1 pm. Engineering macroscopic product properties is then only possible through tailored surface and interfacial properties, no matter whether a bottom-up process like precipitation [11] or a top-down process such as milling in stirred media mills [12] is studied. Aggregation is an important aspect in both processes which are studied in the following. 

Engel AK, Fries P, Singer W. 2001. Dynamic predictions Oscillations and synchrony in top-down processing. Nat Rev Neurosci 2 704-716. 

It is attractive to imagine that all we have to do to ensure learning in students is to analyze the task we wish to teach, which is a top-down process, and then teach the various pieces of the hierarchy, which is a bottom-up process. Under this model of instruction, we start with the elements in the lowest boxes at the bottom of the hierarchy, provide instruction on all elements at this level, move up a level and do the same thing, and continue until we reach the top of the tree. 

The elaboration of the Spanish NAP has been mostly a top-down process (from macro to meso and to micro), with several stages and little interdependence between levels. The total amount of allowances was decided very early in the process, when data at the installation level were still incomplete. 

As has already been outlined by Yang et al. [63], the implementation of a top-down process can introduce another level of hierarchy. Various techniques have been developed to structure colloidal crystals on a micrometer length scale. Patterning at these dimensions is crucial for the production of functional materials which might be of technical relevance. Furthermore, the functionality of a specific material can be greatly increased. Various methods that were employed for colloidal crystal patterning will be briefly reviewed here. 

In order to illustrate a top-down process of finding a solution, we rewrite and split Eq. (13.25) into... 

Self-assembly is the autonomous organization of components into patterns or stmctures. Self-assembly of molecular or prepolymeric components by noncovalent interactions offers a simple and cost-effeaive tool to fabricate large periodic structures that may not be accessible or practical by top-down processes. 

The FHA is a top-down process and can be illustrated as in Fig. 3.2. Each step is explained in Sections 3.2.1-3.2.4. Some assessors prefer to have issue a stand-alone FHA (i.e. not part of the SSA). With reference to the safety assessment strategy in Fig. 2.4, this process assumes that the FHA in integrated into the SSA. 

Fabrication of sophisticated structural details through regio-selective functionalizations by using a bottom-up approach onto prefabricated nanoscopic objects, produced via either bottom-up or top-down processes, appears to be the best alternative in the case of mimicking the physical and chemical properties of biological nano-objects. It is expected that significant efforts in the area of templated assembly will continue over the coming decades. 

Block copolymer lithography merging bottom-up with top-down processes. MRS Bull, 30, 952-966. 

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