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Silver loaded zeolite (Ag-Z) was previously found to have effective bactericidal activity against Escherichia coli. To understand the mechanisms of bactericidal activity of Ag-Z, role of light irradiation was focused and investigated in this study. In this study, we focused on light irradiation. Antibacterial assay and spectroscopic study revealed that light irradiation enabled Ag-Z to reduce dioxygen to form a reactive oxygen species, which led to bactericidal activity. These results indicate that the onset of bactericidal activity can be controlled by light irradiation.

Potassium salt of α,α′-bis(dithiocarboxyoxy)-p-xylene (abbreviated as K2-XDX) was synthesized as a chelating agent with p-xylene-α,α′-diol, carbon disulfide, and potassium hydroxide. Since a mercury(II)–XDX chelate complex suspension scattered pearl-blue light strongly because of the formation of a colloidal solution, the nephelometric analysis of small amounts of mercury(II) was undertaken. The calibration curve was found to be linear in the two ranges of 0.03–1.00 and 0.50–25.00 μg cm−3 of the mercury(II) ion respectively, but no suitable masking agents for interfering metal ions were found. The mole ratio of mercury(II) to XDX in the complex was found to be 1 to 1. These data for the complex suggested that XDX and mercury(II) combined alternately to form the (–Hg–XDX–)n complex. The molecular weight of this complex could be calculated as about 2×107 from the Zimm plot on the basis of the light-scattering method.

The excretion of essential trace elements, namely, Se, Sr, As, Mn, Co, V, Fe, and Zn into the bile of Se-deficient (SeD) Wistar male rats was studied using the multitracer (MT) technique, and instrumental neutron activation analysis (INAA). Normal and Se-control (SeC) rat groups were used as reference groups to compare the effects of Se levels on the behaviors of the essential trace elements. The excretion (% dose) of Se, Sr, As, Mn, Co, and V increased with Se levels in the liver. The biliary excretion of Mn and As dramatically enhanced for SeC rats compared with SeD rats, while that of V accelerated a little for SeC rats. The radioactivity levels of (59)Fe and (65)Zn in the MT tracer solution were insufficient to measure their excretion into bile. The role of glutathione and bilirubin for biliary excretion of the metals was discussed in relation to Se levels in rat liver.

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