Preferred Fiber Orientation Research Articles

The glucan–chitin complex in Saccharomyces cerevisiae. IV. The electron diffraction of crustacean and yeast cell wall chitin

AbstractCrustacean and yeast cell wall chitin were analyzed by means of transmission electron microscopy and selected‐area diffraction. Single fibrils 8–25 nm wide have been observed in the micrographs of crustacean chitin. Analysis of a series of diffraction patterns obtained from thin crustacean chitin platelets yielded results which were in a better agreement with the theoretical structural model than those measured earlier. In this respect electron diffraction is shown to be superior to the more commonly used x‐ray diffraction. Yeast cell wall chitin had a less perfect structure than the crustacean chitin. Single fibrils were not observed on the micrographs and electron diffraction patterns did not show any preferred fiber orientation. The evaluation of electron‐diffraction patterns of both the primary septum and the adjacent circular zone of scar ring led to the conclusion that α‐chitin is present in both these parts of the mother bud scar.

Boron Nitride Composites By Chemical Vapor Deposition

Composites of boron nitride ( BN) have been made by the chemical vapor deposition ( CVD) of a BN matrix on a BN felt fiber substrate. Reactant gases were boron trifluoride and ammonia. The composites have a relatively high density (1.70 g/cm3), a crystallite size LC = 150 A and an interlayer spacing d002 = 3.35 A. Measurements of elastic modulus and thermal conductivity and expansion showed some anisotropy as a result of the preferred fiber orientation of the substrate.

133. The relationship between preferred orientation and elasticity of carbon fibers

133. The relationship between preferred orientation and elasticity of carbon fibers

Piezoelectric Effect in Blood Vessel Walls

Piezoelectric effect has been observed in various kinds of tissues such as trachea, intestines, ligament, aorta and vena. The anisotropy of piezoelectric modulus indicates the preferred orientation of piezoelectric protein fibers including collagen and elastin. The value of piezoelectric modulus in completely dried state is from 10 -10 to 10 -9 c.g.s.e.s.u.. Temperature variation of the piezoelectric modulus is influenced by the thermal motion of molecules and the moisture absorbed in the specimen. It is estimated that 1 precent oblique cyclic deformation of blood vessel walls at a frequency of about 1 c/s could produce the alternating electric current of approximately 3 pico ampere between the surfaces of the vessel wall.