Observations of the spontaneous growth of tin whiskers on tin-manganese alloy electrodeposits

The spontaneous growth of tin whiskers on electrodeposited tin-manganese alloy coatings has been observed. This growth is distinct from any previously reported whisker growth on either pure tin or other tin-based alloy electrodeposits. It has an extremely short incubation period of a few hours only, followed by a spectacularly rapid and profuse growth. During the whole period of whisker growth, the tin-manganese electrodeposits were found to be in a tensile residual stress state. This rules out the commonly accepted explanation of a compressive stress as the driving force for tin whisker growth.     

The generation of substituted classical secondary 2-norbornyl cations

All possible stereoisomers of 5-cyano- and 6-cyano-2-norbornyl tosylate have been synthesized (except the endo, endo isomer) and solvolyzed in 97% hexafluoroisopropanol. The rates and products are most easily interpreted in terms of classical ions. An approximate model of substituent effects allows an estimate of anchimeric assistance in the parent norbornyl ion to be a factor of about 540 at 25° and 18 at 125°.     

Aspects of an inventory control study

A case study for the design of a spare parts inventory control system is described. The main emphasis is given to the problems of applying and tailoring forecasting and inventory control theory to suit the needs of a particular problem. In the main, well established methods were used and these are not described in detail. New developments arising in the course of the study have been described elsewhere.     

Very light neutron-rich nuclei studied via the (6Li, 8B) reaction

Results from investigations of the $\text{T}{}_{\mathrm{z}}\text{=}\text{3}\text{2}$ nuclei ⁵H, ⁷He and ⁹Li and of the T = 1 nuclide ⁴H employing the (⁶Li, ⁸B) reaction at 80 and 93 MeV are presented. In ⁹Li the locations of several low-lying Ip shell levels are indicated; in ⁷He and ⁴H the ground states are clearly observed. No evidence is found for the formation of a narrow ⁵H ground state.