Refractory Behavior Research Articles

Petrographic study of the refractory performance of high-fusing dental alloy investments. I. High-fired, phosphate-bonded investments.

Detailed X-ray, optical microscopic, optical emission, and electron probe analyses of a phosphate-bonded investment before and after firing and after casting were made. Complex sintering reactions that involve incipient liquefaction generate bonds in the fired investment. The refractory behavior of this investment, which is reflected by the extent of liquefaction induced by casting, may influence casting roughness, fit, and porosity.

Neuro-hormonal regulation of sexual receptivity in female Aedes aegypti

The terminal abdominal ganglion regulates the copulatory behaviour of female Aedes aegypti. Neither the brain, the suboesophageal ganglion, nor the thoracic ganglionic mass appear to be directly involved. Juvenile hormone initiates sexual receptivity by acting directly on the terminal ganglion, on some site closely associated with the terminal ganglion, or on some site which in turn secretes a second humoral factor. Matrone, the male accessory gland pheromone, induces post-insemination refractory behaviour by acting on the same site.

Behavior of basic refractories in various spalling test conditions using the heat-cycle method

Behavior of basic refractories in various spalling test conditions using the heat-cycle method

REFRACTORY BEHAVIOUR AT SCHOOL IN NORMAL ADOLESCENT MALES IN RELATION TO PSYCHOPATHY AND EARLY EXPERIENCE

Two studies of refractory behaviour in school of adolescent boys are reported. A close association between scores on the Psychopathic Deviant Scale (Pd) of the Minnesota Multiphasic Personality Scale (M.M.P.I.) and teachers' assessments of refractory behaviour suggest that such behaviour could be considered as being on the same continuum as psychopathy and that the Pd Scale might prove a useful index of it. Early adverse experience was also found to be related to refractory behaviour, as in psychopathy.

Acid and alkaline phosphatase activity in the liver of brown and rainbow trout.

THE susceptibility of the rainbow trout to liver cell tumours following the administration of aflatoxin is well documented1–3, as is the refractory behaviour of brown trout4. The different responses of these two closely related species probably indicate variations in basic metabolism. We decided to investigate histochemically some enzyme systems of the livers from brown, and rainbow trout. Although histologically these livers were similar, the activity and distribution of the acid and alkaline phosphatases showed distinct variations. The activity of alkaline phosphatase was greater in the brown than in the rainbow trout (Fig. 1a and b), while acid phosphatase was more active in the rainbow than in the brown trout (Fig. 1c and d). The distribution of the phosphatases varies throughout the fish kingdom5,6, and the significance of the present findings is uncertain. The metabolic differences in these two species may begin to explain the inverse response to the induction of liver cell tumours. A significant loss of alkaline phosphatase from the livers of ducklings fed aflatoxin has already been reported7, as has the elevation of various serum enzyme concentrations, including alkaline phosphate, in the pig8. We are extending histochemical studies on the effect of aflatoxin at various doses on the two species of trout, and hope to elucidate the different effects, if any, on the enzyme systems in the livers with special reference to the phosphatases.

Equipment for studying the behavior of refractory materials at high temperatures

Equipment has been designed and tested which will enable the investigations and experimental work on the behavior of refractories at high temperatures to be extended (determining spalling reistance, heating rate, firing up to 2400°C, investigating iron-oxide diffusion into basic refractories, etc).

Behavior of Chromite Spinel as Related to Microstructure

The microstructure of massive, sugary, and mylonitic varieties of raw chrome ores has been examined with the aid of polished sections and the difference in the surface area and homogeneity of the natural chromite spinels has been noted. The behavior of the chromite spinels on oxidation, reduction, and with and without the additions of magnesia is illustrated in a series of photomicrographs; the complex reactions occurring are discussed briefly and their significance in the behavior of chrome ore‐containing refractories in slag‐free environments is indicated. The usefulness of reflected‐light techniques in studying diffusion phenomena is shown for several solid‐state reactions, including the formation of synthetic spinels, artificial modifications of a natural spinel, and iron oxide bursting.

“Facilitating” Effect of the Prior Member of a Monaural Click Doublet

This experiment delineates a range of intensities and monaural time separation intervals at which the second member of a monaural click doublet is displaced forward in time. (Displacement is the interaural time difference under the null criterion for binaural fusion of the second click of the doublet with a single contralateral click.) It had been found that, in most of the conditions of an earlier experiment, the second click was internally depressed: either it could not be fused or at fusion it was displaced backward in time. This corresponded to known refractory behavior of peripheral (N1) neural latency (increase) and amplitude (decrease) due to presence of a prior click. In a few cases, however. the second click was displaced in the other direction, a phenomenon which would correspond to a neural facilitation that has not yet been found. This experiment indicates that, to effect forward displacement, the prior click must occur largely within 2–10 msec of the second and must be weaker. The most sensitive time separation is 4 msec, and, under certain conditions, a prior-click level of even −6 db SL can be effectual. The measured magnitudes of the induced interaural time shift were up to about 0.2 msec.

DETERMINING THE EFFECTS OF THE RATE OF FIRING AND RAPID AND SLOW COOLING ON THE PHYSICAL PROPERTIES OF FIRECLAY REFRACTORIES*

This investigation determined that the rate of firing, as specified in the standard test for the firing behavior of fireclay refractories, could be reduced without materially affecting the accuracy of the data obtained. The rate of cooling is found to be the cause of variations between test results and laboratory and factory results.

VI.—On a Method of Splitting Ironstone Nodules by means of an Artificial Freezing Mixture

Most geologists who have had anything to do with the ironstone nodules in the Coal-measures have been struck by their perverse and refractory behaviour under the hammer. How one nodule will refuse to break under the most well-directed blows, and another, though breaking easily, will exhibit to the disappointed collector a clean bright surface of clay-ironstone, without a trace of that organism that he hoped, and almost had a right to expect, was there. It seems therefore necessary to find some other and perhaps less violent method of breaking them.