Initiation and termination of crazes in high impact polystyrene

Initiation and termination of crazes in high impact polystyrene (HIPS) were studied by transmission electron microscope. Instead of the first initiation of crazes in the vicinity of the equator or rubber particles, ribbon-shaped crazes beyond the region were observed on the TEM photos. The starting point and the end point of each ribbon were noticed not to be randomly located on the surface of the cellar particles in HIPS. The spots connecting to the ligaments between the PS rigid inclusions in the cellar particle are found to be the locations where crazes were initiated and terminated preferentially. In addition, the crazes generated at those spots were much thicker and longer. The thoughness of high impact polystyrene was enhanced by the multiple crazes formed in the matrices, through the reduction of the craze stress at room temperature with increasing the volume fraction of polybutadiene at these spots in the dispersed phase. These results conducted that not only the cell structure of the domains in HIPS was not homogeneous but also the polybutadiene ligaments between PS rigid inclusions in the domains were inhomogeneous. Therefore, the responsibility of those polybutadiene ligaments with different thickness to the stresses was different and it forced the crazing initiation and growing preferentially. The crazes were created in some regions in the matrices; On the contrary, rare crazes were formed in the other regions in spite of these regions surrounded around the same dispersed particles. The relation between the spots on the surface and the inner structure of the cellar particle was discussed in this paper.

A taxonomic revision and revalidation of Nycterilampus Montrouzier (Coleoptera: Elateridae, Agrypninae)

Nycterilampus Montrouzier, 1860, from Oceania, is removed from junior synonymy with Tetrigus Candeze, 1857, and is redescribed and revalidated. The genus includes two species, N. lifuanus Montrouzier, 1860, and N. velutinus Fleutiaux, 1891 both from New Caledonia. A comparative study of the morphological characters of males and females, including the reproductive organs of the Nycterilampus species and Tetrigus parallelus Candeze, 1857 (type-species) is presented. A key to Nycterilampus species and their separation from Tetrigus parallelus is given.

The dimer-dimer interaction surface of the replication terminator protein of Bacillus subtilis and termination of DNA replication.

The replication terminator protein (RTP) of Bacillus subtilis causes polar fork arrest at replication termini by sequence-specific interaction of two dimeric proteins with the terminus sequence. The crystal structure of the RTP protein has been solved, and the structure has already provide valuable clues regarding the structural basis of its function. However, it provides little information as to the surface of the protein involved in dimer-dimer interaction. Using site-directed mutagenesis, we have identified three sites on the protein that appear to mediate the dimer-dimer interaction. Crystallographic analysis of one of the mutant proteins (Y88F) showed that its structure is unaltered when compared to the wild-type protein. The locations of the three sites suggested a model for the dimer-dimer interaction that involves an association between two beta-ribbon motifs. This model is supported by a fourth mutation that was predicted to disrupt the interaction and was shown to do so. Biochemical analyses of these mutants provide compelling evidence that cooperative protein-protein interaction between two dimers of RTP is essential to impose polar blocks to the elongation of both DNA and RNA chains.

Revision and codification of the nationality laws of the United States.

Mode of access: Internet.

The history of the progress and termination of the Roman republic.

Mode of access: Internet.

Energy related innovation, the missing link? : a revision and integration of the business cycle theories of Keynes and Schumpeter /

"To be presented at the Sixteenth International Atlantic Economic Conference, Philadelphia, Pennsylvania, October 6-9, 1983."

The history of the progress and termination of the Roman Republic /

Added engraved t.p.

Rules and forms of contracts of the Liverpool cotton association, limited ....

Mode of access: Internet.

Munsell book of color, defining, explaining, and illustrating the fundamental characteristics of color; a revision and extension of "The atlas of the Munsell color system"

Three "Masks" laid in.

Journal of an expedition to explore the course and termination of the Niger : with a narrative of a voyage down that river to its termination ; in two volumes ; illustrated with engravings and maps /

Mode of access: Internet.

Journal of an expedition to explore the course and termination of the Niger : with a narrative of a voyage down that river to its termination /

Folded map wanting in Library of Congress copy.

A geographical and commercial view of northern Central Africa: containing a particular account of the course and termination of the great river Niger in the Atlantic ocean.

"Trade and commerce of northern Central Africa": p. [209]-288.

The history of the progress and termination of the Roman Republic /

Mode of access: Internet.