Abstract Tetrasulfur dinitride was formed by the mild pyrolysis of tetrasulfur tetranitride in the presence of a large amount of sulfur. The stoichiometric correlations of the pyrolytic products indicated a step-by-step degradation of the tetrasulfur tetranitride. Differential scanning calorimetry of an interrupted pyrolysis and determinations of the products gave the enthalpy of the formation of gaseous tetrasulfur dinitride as 351±3 kJ mol−1, which was reasonable judging from the bond enengies calculated by Sanderson’s method and those deduced from known bond energies. The obtained standard enthalpy of the formation of tetrasulfur tetranitride was 469±1 kJ mol−1, which agreed with the value reported by Barker et al.
New five triterpenoid sapogenols, designated abrisapogenols B, E, D, F and G (1-5) were obtained from the hydrolysate of the crude saponin fraction of Abri Herba, the whole plants of Abrus cantoniensis H ance (Lequminosae). Their structures were determined by spectroscopic and X-ray analysis.
The γ-Fe2O3 with a high coercive force was prepared by reducing the acicular γ-FeOOH at 300 °C and by then reoxidizing it at 250 °C. A conversion from γ-FeOOH to γ-Fe2O3 at lower temperatures was effective in obtaining acicular particles without pores because of the large mobilities of ions in the crystal.
Abstract Hydrous gallium(III) oxide was produced as monodispersed spherical particles by forced hydrolysis in the presence of sulfate ions, though they partially dissolved and recrystallized. The rate of the reaction degree was empirically expressed under the given conditions as dα⁄dt=1.60α2⁄3(1−α)0.874, where α is the reaction degree. Polymeric hydroxo complexes were confirmed to act as precursors of the monodispersed spherical particles, judging from the fractional changes of the monomeric and polymeric species during the hydrolysis. The role of sulfate ions in the formation of hydrous gallium(III) oxide particles was discussed.
Abstract Background The repeated-dose liver micronucleus (RDLMN) assay has been well-developed and applied because of its simplicity and the ease of integration into general toxicity studies which is the preferred method from the 3R’s point of view. In this assay, we observed micronucleated hepatocytes which accumulated during a rather long-term dosing period. When considering integration into general toxicity studies, the effects of age of the animals used in the micronucleus assay becomes a major issue. The effect of age on the micronucleus induction rate has been reported in bone marrow micronucleus assays, and it is considered that the decrease in cell proliferation rate due to aging is the cause of the decrease in sensitivity. A decrease in sensitivity due to aging was also reported in a liver micronucleus assay using clofibrate and the cause is considered to be a decrease in hepatocyte proliferation activity due to aging. However, no actual decrease in hepatocyte proliferation rate due to aging has been reported. In addition, there are no reports, so far, on whether similar effects of aging appear when other substances were administered. To investigate the effects of aging in the RDLMN assay, this study focused on the effects of 14-day repeated administration of DEN, a well-known genotoxic hepatocarcinogen with the hepatocyte toxicity which should cause an elevation of cell proliferation rate as a reflective regeneration. Results The liver micronuclei induced by DEN were equivalent between the two age groups (i.e., six and eight weeks of age at the start of dosing). In the histopathological examination for the liver, single cell necrosis, karyomegaly, and increased mitosis were observed in the hepatocytes, and the frequency and severity were increased dose-dependently. Ki-67 immunohistochemical analysis which can detect all cells in the cell cycle other than those in the G0 phase revealed dose-dependent increase of cell proliferation activity, and the difference between ages was not observed. Conclusion The effect of aging on the RDLMN assay could not be recognized when DEN was administered for 14 days in rats. Meanwhile, it was supported by the histopathological examination and Ki-67 immunohistochemical analysis that such an effect of aging was masked by the compensatory hepatocyte proliferation which was induced by the hepatocyte toxicity of DEN.
Cubic particles of colloidal haematite of narrow size distributions were prepared by aging ferric chloride solutions in water + ethanol mixtures. It was shown that α-Fe2O3 formed by phase transformation from β-FeOOH precipitated first. The kinetics of this conversion were followed at different temperatures, pH and chloride concentrations. The role of alcohol in the studied system is discussed and the rate of growth explained in terms of the theory of Burton, Cabrera and Frank.
