Plywood adhesive development.

This thesis is primarily a study of two-step plywood adhesives made with varying amounts of phenol, 1, 3, 5 xylenol, resorcin, and formaldehyde. Each resin was evaluated by using it as the adhesive in making plywood. The plywood was then tested for shear strength and wood failure after a four hour boil. Procedures are given for making and testing various straight phenolic resins and resins modified with 1, 3, 5 xylenol or resorcin, or comibinations of both of these accelerating resins. The straight phenolic resins gave boil-proof bonds, but the curing cycle was too long. Those phenolics modified with 1, 3, 5 xylenol gave relatively short cures, but large quantities of this modifier were necessary. Modification of phenolic resins with resorcin gave very rapid cures, but the pot life of these resins was too short. The best compromise was obtained with a combination of 1, 3, 5 xylenol and resorcin as modifying agents for the phenolic. Some of these three-component resin adhesives had sufficient pot life and produced boil-proof bonds during short curing cycles

The role of zinc in dihydroorotase

Dihydroorotase (4,4—dihydroorotic acid amidolyase, EC 3.5.2.3.) which catalyzes the reversible cyclization of N-carbamyl-L-aspartate to L-dihydroorotate has been purified from orotate-grown Clostridium oroticum. The enzyme is stable in 0.3 M sodium chloride and 10 µ ZnSO4. Sodium dodecyl sulfate gel electrophoresis indicates the enzyme to be composed of two identical subunits each with a molecular weight of 58,000 + 6000. Dihydroorotase is shown to be a zinc-containing metalloenzyme with 2 g atoms of zinc per 58,000 g of protein. The role of zinc in dihydroorotase is discussed

Reactivity changes during startup in large nuclear rockets

Large uranium 235 nuclear rockets - reactivity changes during startup by hydrogen density and core temperature variation

Effects of a shortened daily photoperiod or melatonin treatment on pubertal red deer hinds (Cervus elaphus)

The effects of a shortened daily photoperiod or daily, afternoon injection of melatonin on the the onset of the breeding season and other seasonal changes associated with the transition from summer to winter were examined in pubertal red deer hinds. Eleven pubertal hinds and four non lactating adult hinds were randomly allocated to three treatment groups. Control hinds (Group 1) were maintained under natural photoperiodic conditions. From 8 January until 31 March one group of hinds (Group 2) was subjected to a daily photoperiodic regime of eight hours light to sixteen hours dark (8L:16D) by keeping them in a darkened room from 1600h until 0800h the following day and another group of hinds (Group 3) was given an intramuscular injection of 3 mg melatonin in safflower oil daily at 1600h. Silent ovulations seemed to occur in many of the hinds, but this study did not establish whether the treatments utilised here had any effects on these silent ovulations. Earlier calving may give rise to calves with a body weight advantage over those born later, at least until their first winter. Mating and calving data from the adult hinds was too limited to indicate whether the advancement of these events achieved in the yearlings could readily translated to older animals