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To examine the change of the rate of nitrogen desorption with sulfur concentration and low oxygen concentration change, the rates of nitrogen desorption from molten steel were measured with the blow of CaO powder or argon gas onto the molten steel through a top lance under the reduced pressure. 15 kg of electrolytic iron was melted molten in a MgO crucible by a high frequency induction furnace and the temperature of the melt was held at 1873K. Aluminum, FeS and other alloying elements were added and composition of molten steel was kept at 0.001–0.19%Al, 0.0007–0.0064%S, 0.002–0.006%N, 0.5%Mn and 0.2%Si. CaO powder was blown onto molten steel with argon gas for 20 min under the reduced pressure of about 670 Pa and metal samples were taken during CaO powder blowing in order to clarified the removal rate of sulfur and nitrogen. The rate constant of desulfurization was maintained during CaO powder blowing, however, the apparent rate constant of nitrogen desorption increased gradually. A mathematical model of nitrogen desorption was presented with the consideration of the chemical reaction of aluminum and sulfur in molten steel with CaO flux, respectively. The calculated nitrogen concentration by the model were in good agreement with the experimental values. It was estimated that the apparent rate constant of nitrogen desorption was increased as a result of decrease of oxygen and sulfur concentration in moleten steel by the reaction between aluminum in molten steel and CaO flux.

In order to examine the mechanism of the generation of MgO in CaO–MgO–Al2O3 inclusion during Ca addition, the variations of inclusion composition and molten steel composition were measured during and after FeMg and CaSi addition to 2 kg heats of Al killed molten steel at 1873K. From experimental studies, the equilibrium reaction was discussed by the relationship between Ca concentration in molten steel and MgO concentration in inclusion and apparent equilibrium constant of magnesium deoxidation was obtained.The results obtained are summarized as follows;(1) The addition pattern of calcium and magnesium affected composition variation path, although it had no effects on final composition of inclusion.(2) The boundary condition of formation and disappearance of MgO in Ca–Al–O inclusion was given by Ca concentration and Mg concentration in molten steel.(3) The reaction of MgO formation in Ca–Al–O inclusion was expressed as follows.CaO·Al2O3 in inclusion+Mg=MgO·Al2O3 in inclusion+Ca(4) The apparent equilibrium constant log K′Mg was estimated to be −7.2 by thermodynamic calculation.log K′Mg=aMg·aO=−7.2

Solid–liquid interfacial energy of steel during solidification was measured predicted from the both experimental techniques of unidirectional solidification and thermal analysis applying the dendrite growth model and heterogeneous nucleation model. Solid–liquid interfacial energy changed depending on primary phase during solidification, i.e., that of primary δ phase was larger than that of γ phase. When the primary phase was the same, solid–liquid interfacial energy increased with increasing carbon content. Primary dendrite arm spacing changed depending on solid–liquid interfacial energy. A trace amount of bismuth which had the effect of a decrease in the solid–liquid interfacial energy of steel during solidification decreased primary and secondary dendrite arm spacing, significantly.

The rates of nitrogen desorption from molten steel were measured with the blow of CaO powder or argon gas onto the melts under reduced pressure. 15kg of electrolytic iron was melted in a MgO crucible by a high frequency induction furnace and the temperature of the melt was held at 1873 K. A mathematical model was developed with the consideration of the chemical reaction between sulphur in molten steel and CaO powder and the desorption of nitrogen at gas-metal interface. The calculated results were in good agreement with the measured ones. The apparent rate constant of nitrogen desorption and the rate controlling step were examined.

We developed a 1 MV field-emission transmission electron microscope. This paper reports details and specifications of the instrument. The microscope was designed to obtain a bright and coherent electron beam by using the field emission gun equipped with a pre-accelerating magnetic lens and the high-voltage power supply with high stability (0.5 ppm min(-1)). Using this microscope, the brightness of 1.8 x 10(10) A cm(-2) sr(-1) and the lattice resolution of 49.8 pm were attained.

A major objective of calcium treatment in steelmaking is to improve product performance through inclusion modification. To establish inclusion modification, shape and composition of inclusions were monitored using SEM during and after addition of calcium wire into 2 kg heats of steel under various conditions of Ca consumption and Ca addition pattern. A mathematical model of the kinetics considering the evaporation of calcium and the reaction between inclusions and melt was developed to thoroughly examine these phenomena in calcium treatment. The calculated results were compared with the observed ones which were obtained in experiments.(1) Shape and composition of inclusions changed from a spherical SiO2-MnO system to almost lumpy Al2O3 with the addition of aluminum, and to spherical CaO-Al2O3 including CaS after addition of CaSi.(2) The process and consumption of calcium were found to affect the change of CaO and CaS contents of inclusions.(3) A mathematical model was developed assuming that vaporization rate of calcium from the melt and rate of reaction between melt and inclusions can be described by equations of the first order reaction, and that the size and number of inclusions remain constant during treatment.(4) The calculated [Ca] and CaO, CaS contents of inclusions showed good agreement with observed ones regardless of the conditions of CaSi addition.

The seeds of the gramineous plant Coix lachryma-jobi L. var. ma-yuen Stapf are a traditional Chinese medicine possessing antitumor activity. An acetone extract of the seeds was fractionated by the aqueous alkali method and by silica gel column chromatography in order to identify the antitumor components. Antitumor activity, as assayed by an in vivo growth inhibition test on a transplantable mouse tumor, was attributed to an acidic fraction. Infrared spectroscopy and gas-liquid chromatography showed that this acidic fraction was composed of four free fatty acids: palmitic, stearic, oleic, and linoleic acids.

Various kinds of free fatty acid were examined on their antitumor activity against ascites tumor cells, Survival days of mice after administrations of free fatty acid were observed. From these data I.L.S. (Increase of life-span) was culcurated and used as a parameter of Antitumor activity. Effective fatty acids against Sarcoma-180 were as follows : Pentadecanoic acid in saturated fatty acid series of carbon number 6 to 24, oleic acid in mono-unsaturated fatty acid series, and α-linolenic and docosahexaenoic acids in poly-unsaturated fatty acid series.The most effective fatty acid in our antitumor activity research is (hydroxy phenyl) stearic acid.The mechanism on antitumor activity of free fatty acid is not made clear sufficiently but it was suggested that disorder of membrane caused by fatty acids is responsible for their antitumor effect.

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Ubiquitin gene expression and the ubiquitination of proteins in the posterior silk glands (PSG) of B. mori were analyzed developmentally with respect to fibroin synthesis and degeneration. Two ubiquitin transripts are expressed throughout larval stages, and the level of each transcript is regulated differently. The larger transcript, a polyubiquitin mRNA, was abundant during the molt stage, while levels of the smaller ubiquitin transcript increased immediate after molting. Only a single 65kDa ubiquitinated protein was detected late in the 5th instar, and the amount increased up to spinning stage. This ubiquitinated protein may participate in the PSG degeneration.

Microelectrochemical polarization and silver decoration techniques were performed on the small area with and without MnS inclusions. MnS inclusions were found to be partially dissolved in the potential range from 0.15 to -0.45 V (vs. Ag/AgCl, 3.33 M KCl) in a boric-borate buffer (pH 8.45) with 10 mM NaCl, whereas the entire surface of the inclusions was dissolved below and above this potential range. Silver deposition occurred only on and around MnS inclusions below -0.2 V, which generally corresponded to the stable region of hydrogen sulfide ions. When MnS inclusions partially dissolved, silver deposition occurred only in the dissolved area. The dissolution species from MnS inclusions seems to promote hydrogen absorption reaction.

The posterior silk glands of Bombyx mori are highly differentiated to produce fibroin, the specific cocoon protein. We have now succeeded in isolating the nuclei from the posterior silk gland cells, and a giant arborescent nucleus with a strikingly complicated morphology was observed. Biochemical analysis of the composition of the nuclei confirmed the existence of the four core histones in equimolar quantities and H1 histone. The isolated nuclei obtained here might be prerequisite for the study of the structure of the giant polyploid nucleus and its relation to the tissue-specific fibroin gene expression.

Revistin, a substance that strongly inhibits the reverse transcriptase activity of murine leukemia virus in our screening system, was obtained from a cultured broth of a soil streptomyces which was closely related to Streptomyces filipinensis. The assay method for the activity was based on the inhibition by a test material of the incorporation of 3H-dTMP into DNA synthesized by the reverse transcriptase of an oncogenic RNA virus. Crude revistin was isolated by serial procedures of salting out with ammonium sulfate and precipitation with cetylpyridinium chloride. The crude material showed neither antibacterial nor antifungal activity. It exhibited inhibition against splenomegaly in mice caused by RAUSCHER leukemia virus infection.