Testing of serum samples of 23 pregnant women who were asymptomatic carriers of hepatitis B surface antigen for e antigen and antibody to e with an immunodiffusion technic identified 10 mothers with e antigen and seven with e antibody. Their babies were tested for hepatitis B surface antigen in serum at intervals for more than 12 months. In all 10 babies born to e-antigen-positive mothers hepatitis B surface antigen developed and persisted through the observation period, and all 10 elder siblings of these newborn babies were found to be asymptomatic carriers. In remarkable contrast, all seven babies born to mothers positive for antibody to e escaped antigenemia, and none of their three elder siblings carried surface antigen. On the basis of these results, e antigen may be used as an indicator of transmission, and antibody to e as that of absence of transmission of hepatitis B virus from carrier mothers to children.

Electrodynamic responses from three-dimensional topological insulators are characterized by the universal magnetoelectric term constituent of the Lagrangian formalism. The quantized magnetoelectric coupling, which is generally referred to as topological magnetoelectric effect, has been predicted to induce exotic phenomena including the universal low-energy magneto-optical effects. Here we report the experimental indication of the topological magnetoelectric effect, which is exemplified by magneto-optical Faraday and Kerr rotations in the quantum anomalous Hall states of magnetic topological insulator surfaces by terahertz magneto-optics. The universal relation composed of the observed Faraday and Kerr rotation angles but not of any material parameters (for example, dielectric constant and magnetic susceptibility) well exhibits the trajectory towards the fine structure constant in the quantized limit.

We achieve the enhancement of circular photogalvanic effect arising from the photo-injection of spins in topological insulator thin films by tuning the Fermi level (E F ). A series of (Bi 1−x Sb x ) 2 Te 3 thin films were tailored so that the Fermi energy ranges above 0.34 eV to below 0.29 eV of the Dirac point, i.e., from the bulk conduction band bottom to the valence band top through the bulk in-gap surface-Dirac cone. The circular photogalvanic current, indicating a flow of spin-polarized surface-Dirac electrons, shows a pronounced peak when the E F is set near the Dirac point and is also correlated with the carrier mobility. Our observation reveals that there are substantial scatterings between the surface-Dirac and bulkstate electrons in the generation process of spinpolarized photocurrent, which can be avoided by designing the electronic structure in topological insulators.