Manufacture of fiber-epoxy test specimens: Including associated jigs and instrumentation

Experimental work on the manufacture and strength of graphite-epoxy composites is considered. The correct data and thus a true assessment of the strength properties based on a proper and scientifically modeled test specimen with engineered design, construction, and manufacture has led to claims of a very broad spread in optimized values. Such behavior is in the main due to inadequate control during manufacture of test specimen, improper curing, and uneven scatter in the fiber orientation. The graphite fibers are strong but brittle. Even with various epoxy matrices and volume fraction, the fracture toughness is still relatively low. Graphite-epoxy prepreg tape was investigated as a sandwich construction with intermittent interlaminar bonding between the laminates in order to produce high strength, high fracture toughness composites. The quality and control of manufacture of the multilaminate test specimen blanks was emphasized. The dimensions, orientation and cure must be meticulous in order to produce the desired mix

Annihilation Diagrams in Two-Body Nonleptonic Decays of Charmed Mesons

In the pole-dominance model for the two-body nonleptonic decays of charmed mesons $D \rightarrow PV$ and $D \rightarrow VV$, it is shown that the contributions of the intermediate pseudoscalar and the axial-vector meson poles cancel each other in the annihilation diagrams in the chiral limit. In the same limit, the annihilation diagrams for the $D \rightarrow PP$ decays vanish independently.Comment: 9 pages (+ 3 figures available upon request), UR-1316, ER-40685-766, IC/93/21

On the immature stages of Stethorus gilvifrons Mulsant (Coleoptera: Coccinellidae).

Es wird eine eingehende morphologische Untersuchung der frühen Entwicklungsstadien von Stethorus gilvifrons Mulsant gegeben. Die Abbildungen umfassen äußerliche Unterscheidungsmerkmale des Eies, des vierten Larvenstadiums und der Puppe.A detailed morphological study of the immature stages of Stethorus gilvifrons Mulsant is presented. The illustrations include external distinguishing features of the egg, fourth instar larva and the pupa

Heats of Mixing of Binary Mixtures of n-Butylamine with Water, Methanol, Ethanol & n-Butan-I-ol: Effect of the Chain Length on Hydrogen Bond Energy

735-74

Thermodynamic Properties of I-Propanol + n-Butylamine Binary Mixture: Enthalpy of Hydrogen Bonding

371-37