Hierarchical architecture

Pouget E, Dujardin E, Cavalier A et al (2007) Hierarchical architectures by synergy between dynamical template self- assembly and biomineralization. Nat Mater 6 434-439... 

The concentration of all automation functions within a single computer (Section 7.19.1) may be possible for a very simple plant, but this type of configuration is inefficient for more complex processes for which there could be many thousands of connections between plant and computer. Currently, small industrial processes are controlled by a hierarchical architecture consisting of a central computer (usually a minicomputer), which is used to solve central automation problems, together with a series of peripheral computers (generally microprocessors which are called front-end computers) which control different sections of the plant (Fig. 7.104a). This type of architecture is termed a decentralised computer system. 

Natural and man-made porous media usually possess formidably complex microstructure, often hierarchical. In this paper we shall not discuss hierarchical microstructures revealed, for instance by fractured porous media and biological tissues like bone and soft tissue. However, recently developed stochastic reiterated homogenisation enables one to determine macroscopic properties of random porous media with hierarchical architecture, cf. [11],... 

A number of experimental chemical process synthesis procedures have been developed with a hierarchical architecture based on both the hierarchical structure of the chemical innovation process and the physical property hierarchy. Examples include PIP (Kirkwood et al, 1988) and BALTAZAR (Mahalec and Motard, 1977). This hierarchical approach is also evident in the Pinch Technology Onion Diagram (Linnhoff and Ahmad, 1983). The hierarchical approach is also the foundation for the two early textbooks on process synthesis methodology (Rudd et al, 1973 Douglas, 1988). 

Figure 3.2 Schematics of the hierarchical architecture of cortical bone. (A) Longitudinal section of femur. (B) Enlarged cross section of cortical bone showing cylindrical osteons. (C) Enlargement of an osteon showing the central Haversian canal with a blood vessel, the concentric lamellae and the radial canaliculi (see also J). A more detailed view of an osteon is shown in the inset in the bottom right. (D) Collagen fibre composed of hundreds of fibrils. The evenly spaced dark spirals are...

Ex. Guided assembling, 3D networking and new hierarchical architectures, robotics, evolutionary... 

Considering the serious difficulties involved in the creation of hierarchical architectures from synthetic polymers, the present system can open up new paths to accelerate development of the polymer assembly systems and can extend the frontier of polysaccharide-based functional nanomaterials. 

Polymeric cylinders prepared via the self-assembly approach represent a versatile and powerful soft template for the fabrication of 1-D hybrid or inorganic nanomaterials with hierarchical architectures and complex functionaHties. 

Zhang J, Qiu C, Ma H et al (2008) Facile fabrication and unexpected electrocatalytic activity of palladium thin films with hierarchical architectures. J Phys Chem C 112 13970-13975... 

It is important to emphasize that many natural tissues are essentially composed of nanoscale biopolymers or biocomposites with hierarchical architectures. Therefore, by mimicking the structure and property of their natural counterparts, synthetic nanopoiymers and nanocomposites are very likely to enhance/regulate the functions of specific cells or tissues. This principle has been demonstrated by the success of bioinspired polymers and composites in both clinical practice and in laboratory research. In particular, bone is the hierarchical tissue that has inspired a myriad of biomimetic materials, devices, and systems for decades. This chapter focuses on this well-developed area of biomimetic or bioinspired nanopoiymers and nanocomposites for bone substitution and regeneration, especially those with high potentials for clinical applications in the near future. 

Block copolymers represent a kind of versatile and powerftil toolbox for the fabrication of polymer cylinders with hierarchic architecture and complex functionality. When chemically dis-tina polymer chains are immiscible and confined in a single chain, the block copolymers will phase-separate in solution or in the bulk. By means of self-assembly, block copolymers with suitable volume fractions can undergo miaophase segregation in the bulk and form regular arrays of cylindrical or tubular morphologies. Due to the unlike physical and chemical properties, the compartments can be individually addressed. Via aoss-linking of cylindrical domain in the self-assembled stmc-tures, polymeric cylinders with side chains tethered to a fixed linear core can be achieved. 

Wang Z, Li F, Eigang NS, Stein A (2006) Effects of hierarchical architecture on electronic and mechanical properties of nanocast monolithic porous carbons and carbon—carbon nanocomposites. Chem Mater 18 5543-5553... 

Liang Y, Liang F, Wu D, Li Z, Xu F, Fu R (2011) Construction of a hierarchical architecture in a wormhole-fike mesostructure for enhanced mass transport. Phys Chem Chem Phys 13 8852-8856... 

Poiyamide dendrimers Three polyamides with the same internal hierarchical architectures but with either acidic, neutral or basic terminal functionality 5 generations, 972 terminal groups in 5th gen. the polymers shrink or swell upon pH change ( smart behavior ). [259]... 

Kazakeviciute-Makovska R, Steeb H (2013) Hierarchical architecture and modeling of bio-inspired mechanically adaptive polymer nanocomposites. In Altenbach H, Forest S, Krivtsov A (eds) Generalized continua as models for materials. Advanced structured materials, vol 22. Springer, Berlin, pp 199-215... 

Most commonly used layered silicate is montmorillonite clay, which is composed of micron-sized particles. The particles are constructed of platelets with thickness of lnm and width of 100-200 nm. Platelets have permanent negative charge and they are held together by charge balancing cations such as Na" or Ca [2-i] ions. The significant disruption of individual silicate layers in polymer matrix with nanoscopic dimensions (exfoHated structure) leads to improvements of the nanocomposite properties. However, in many cases, the isolated silicate layers are not completely dispersed throughout the polymer matrix, instead, the clay particles in polymer matrix maintain the hierarchical architecture, and an interlayer expansion occurs (intercalated structure). 

Hierarchical architecture This model is a hybrid of the preceding three architectures. 

The rate and direction of the movement correspond to those of the fiber production. The fibers were reported to produee at a rate of 2 nm/min at 25°C (Brown, Jr. et al. 1976). However, A. xylinum produeed the fiber faster on NOC templates at a rate of 4.5nm/min at 24 °C. This gap was considered due to difference of the strength of the interaetion between the biosynthesized fiber and the NOC surface. This also indicated that the NOC surface promoted the secretion rate of the fibers. More to importanee, the regulated movement of the bacteria due to the ordered surface of NOC may trigger the development a 3D structure of hierarchical architecture from the nano to the microlevels. Therefore, we have been attempting to regulate the 3D architecture of materials using the nanofibers secreted by A. xylinum as a building block. 

Xu, L. Lu, C. Zhang, Z. Yang, X. Hou, W. (2010). Various self-assembled three-dimensional hierarchical architectures of La2(Mo04)3 controlled synthesis, growth mechanisms, luminescence properties and adsorption activities. Nanoscale, 2., (May 2010) 995-1005, ISSN 2040-3364. 

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