Radiation-induced swelling of stainless steel

Significant swelling (1 to 10 percent due to small voids have been found in stainless steel when it is exposed to fast neutron doses less than expected in commercial fast breeder reactors. The main features of this new effect are: (i) the voids are formed by the precipitation of a small fraction of the radiation-produced vacancies; (ii) the voids form primarily in the temperature range 400 degrees to 600 degrees C (750 degrees to 1100 degrees F); and (iii) the volume increases with dose (fluence) at a rate between linear and parabolic. The limited temperature range of void formation can be explained, but the effects of fluence, microstructure, and composition are determined by a competition between several kinetic processes that are not well understood. This swelling does not affect the feasibility or safety of the breeder reactor,but will have a significant impact on the core design and economics of the breeder.Preliminary results indicate that one cannot eliminate the effect,but cold-working,heat treatment, or small changes in composition can reduce the swelling by a factor of 2 or more. Testing is hampered by the fact that several years in EBR-II are required to accumulate the fluence expected in demonstration plants. Heavyion accelerators,which allow damage rates corresponding to much higher fluxes than those found in EBR-II,hold great promise for short-term tests that will indicate the relative effect of the important variables.     

Silk moth eclosion: hormonal triggering of a centrally programmed pattern of behavior

The emergence of the adult cecropia silk moth from the pupal skin involves a stereotyped series of abdominal movements-the pre-eclosion behavior. This behavior, triggered by a neurosecretory hormone, consists of three phases that are characterized by the relative frequency and pattern of movements. Electrical recordings from a nerve cord with severed peripheral nerves demonstrate that the pre-eclosion behavior is prepatterned in the abdominal ganglia. In response to the hormone, the entire 1.25-hour behavioral program can be activated and "read off" in the absence of sensory feedback.     

Strychnine: its action on spinal motoneurons of cats

In cats strychnine does not alter measurably the potential, threshold, after potentials, or refractoriness of the membrane of the spinal motoneurons. Increased reflexes probably result from increase of excitatory impingement upon motoneurons. Spikes recorded during a rapid succession of nerve impulses produced by strychnine ("strychnine burst") suggest that soma membrane resistance is appreciable during stimulation.     

Oral vaccination of sexually mature pigs with Brucella abortus vaccine strain RB51

OBJECTIVE: To develop a novel oral vaccine delivery system for swine, using the rough vaccine strain of Brucella abortus. ANIMALS: 56 crossbred pigs from a brucellosis-free facility. PROCEDURE: In 3 separate experiments, pigs were orally vaccinated with doses of 1 x 10(9) to > 1 x 10(11) CFU of strain RB51 vaccine. The vaccine was placed directly on the normal corn ration, placed inside a whole pecan, or mixed with cracked pecans and corn. RESULTS: Oral vaccination of pigs with vaccine strain RB51 resulted in a humoral immune response to strain RB51 and short-term colonization of the regional lymph nodes. CONCLUSIONS AND CLINICAL RELEVANCE: A viscous liquid such as Karo corn syrup in association with pecans that scarify the oral mucosa are necessary when placing the live vaccine directly onto corn or other food rations. Doses of > 1 x 10(11) CFU of RB51 organisms/pig in this mixture ensures 100% colonization of regional lymph nodes via the oral route. This method may allow an efficient and economical means to vaccinate feral swine for brucellosis.