**3.1 Significance of results for clinical practice**

Metabolic processes during the HA synthesis are very dynamic. The chondrocytes in AC actively synthesize and catabolise HA so that its optimal "usability" is achieved (in a relatively short time). The HA synthesis is usually in equilibrium with catabolic processes. These processes result in the achievement of the optimum HA concentration. The studies of metabolic processes (Schurz et al., 1987) implied that the half-life of the functional existence of HA molecules are mere 2-3 weeks. The solved project makes it evident that the "short lifecycle" of HA is dominantly caused by dynamic (biomechanical) effects. During leg movements, long snakelike NaHA/HA macromolecules are exposed to fast changes in shape accompanied by permanently arising and vanishing physical (non-covalent) bonds. To avoid the shortage of HA/NaHA, old polymer chains are replaced with new chains. The disturbance of HA new formation processes may lead to initiations of pathological processes. Mechanical effects during movements continuously initiate new groupings of HA macromolecules and newly arising (and vanishing) bonds among them. Frequented variations of kinetic energy transfers into HA molecular structures contribute to HA fragmentations in the biophysical perspective. These fragmentations may also be biochemically accelerated by hyaluronisades (Saari et al., 1993). HA fragments may initiate the formation of macrophages and extensive inflammations of AC.

The above examples of the interrelated nature of the causes of some AC defects show the key role of the rheological properties of non-Newtonian synovial fluid.

#### **4. Acknowledgment**

The contents presented in this chapter was supported by the Research Grant from MSMT No.6840770012.

#### **5. References**

Akizuki, S.; Mow, V.C.; Muller, F.; Pita, J.C; Howell, D.S. & Manicourt, D.H. (1986). Tensile properties of human knee joint cartilage: I. Influence of ionic conditions, weight bearing, and fibrillation on the tensile modulus, *J. of orthopaedic research*, Vol. 4, No. 4, pp. 379-392

this way, the hydrodynamic biomechanism quickly presupplements the surface localities with lubrication material. Shortly after unloading, the strain rate is high. During strain relaxation, it slows down. This is the way how the articular cartilage tissue attempts to retain the lubrication material between the articular plateaus of synovial joints as long as

Analogically to the low and the middle zone of AC where an incompressible zone arises under high loads whose dominant function is to bear high loads and protect chondrocytes with the intercellular matrix from destruction, in the peripheral zone as well a partial incompressible zone arises whose function is to bear high loads and protect the peripheral tissue from mechanical failure. The appearance of the incompressible tissue in all zones is synchronized aiming at the creation of a single (integrated) *incompressible cushion*. The existence of an incompressible zone secures the protection of chondrocytes and extracellular

Metabolic processes during the HA synthesis are very dynamic. The chondrocytes in AC actively synthesize and catabolise HA so that its optimal "usability" is achieved (in a relatively short time). The HA synthesis is usually in equilibrium with catabolic processes. These processes result in the achievement of the optimum HA concentration. The studies of metabolic processes (Schurz et al., 1987) implied that the half-life of the functional existence of HA molecules are mere 2-3 weeks. The solved project makes it evident that the "short lifecycle" of HA is dominantly caused by dynamic (biomechanical) effects. During leg movements, long snakelike NaHA/HA macromolecules are exposed to fast changes in shape accompanied by permanently arising and vanishing physical (non-covalent) bonds. To avoid the shortage of HA/NaHA, old polymer chains are replaced with new chains. The disturbance of HA new formation processes may lead to initiations of pathological processes. Mechanical effects during movements continuously initiate new groupings of HA macromolecules and newly arising (and vanishing) bonds among them. Frequented variations of kinetic energy transfers into HA molecular structures contribute to HA fragmentations in the biophysical perspective. These fragmentations may also be biochemically accelerated by hyaluronisades (Saari et al., 1993). HA fragments may initiate

The above examples of the interrelated nature of the causes of some AC defects show the

The contents presented in this chapter was supported by the Research Grant from MSMT

Akizuki, S.; Mow, V.C.; Muller, F.; Pita, J.C; Howell, D.S. & Manicourt, D.H. (1986). Tensile

properties of human knee joint cartilage: I. Influence of ionic conditions, weight bearing, and fibrillation on the tensile modulus, *J. of orthopaedic research*, Vol. 4, No.

possible during cyclic loading.

material from potential destruction.

**4. Acknowledgment** 

4, pp. 379-392

No.6840770012.

**5. References** 

**3.1 Significance of results for clinical practice** 

the formation of macrophages and extensive inflammations of AC.

key role of the rheological properties of non-Newtonian synovial fluid.


**11** 

*1Kenya 2Germany* 

**Charge Transport and Electrical Switching** 

Polymers are long chain macromolecules made up of many repeating units called monomers. They are found in nature and can also be made synthetically. Natural/bio polymers are considered to be environmental benign materials as opposed to synthetic polymers. Research geared toward producing innocuous products from biopolymers has intensified. Improved understanding of properties of biopolymers allows for the design of new eco-friendly materials that have enhanced physical properties and that make more efficient use of resources. Biopolymers also have the advantage of being biodegradable and biocompatible. They are therefore of interest for application in advanced biomedical materials, for instance tissue engineering, artificial bones or gene therapy (Eduardo et al., 2005). Other possible fields of applications are related to electrical properties, making this class of materials attractive for potential uses in electronic switches, gates, storage devices, biosensors and biological transistors (Finkenstadt & Willett 2004). Plant biopolymers constitute the largest pool of living organic matter most of which can be attributed to four distinct classes of organic compounds; lignin, cellulose, hemicellulose and cuticles. Cuticles are mainly made up of polymethylenic biopolymers which include cutin and suberin. Cutincontaining layers are found on the surfaces of all primary parts of aerial plants, such as stems, petioles, leaves, flower parts, fruits and some seed coats. In addition, cutin may be found on some internal parts of plants such as the juice-sacs of citrus fruits (Heredia, 2003). Composition, structure and biophysical data of plant cuticles have recently been reviewed (Jeffree, 2003; Pollard et al. 2008; and Dom ́nguez et al., 2011) and will only be mentioned briefly. The main constituents of cutin are esterified fatty acids hydroxylated and epoxy hydroxylated with chain lengths mostly of 16 and 18 carbon atoms. It also contains some

Several biopolymers have well documented properties as organic semiconductors (Eley et al., 1977; Leszek et al., 2002; Radha & Rosen, 2003; Mallick & Sakar, 2000; Lewis & Bowen, 2007; Ashutosh & Singh 2008). DNA-based biopolymer material possesses unique optical and electromagnetic properties, including low and tunable electrical resistivity, ultralow

**1. Introduction** 

fraction of phenolic and fluvanoid compounds.

**2. Charge transfer mechanism in biopolymers** 

*1Physics Department, Pwani University College, P.O. Box 195 Kilifi, 2Institute of Experimental Physics I, University of Leipzig, 04103 Leipzig,* 

 **in Composite Biopolymers** 

Gabriel Katana1 and Wycliffe Kipnusu2

