A primary health concern among residents and evacuees in affected areas immediately after a nuclear accident is the internal exposure of the thyroid to radioiodine, particularly I-131, and subsequent thyroid cancer risk. In Japan, the natural disasters of the earthquake and tsunami in March 2011 destroyed an important function of the Fukushima Daiichi Nuclear Power Plant (F1-NPP) and a large amount of radioactive material was released to the environment. Here we report for the first time extensive measurements of the exposure to I-131 revealing I-131 activity in the thyroid of 46 out of the 62 residents and evacuees measured. The median thyroid equivalent dose was estimated to be 4.2 mSv and 3.5 mSv for children and adults, respectively, much smaller than the mean thyroid dose in the Chernobyl accident (490 mSv in evacuees). Maximum thyroid doses for children and adults were 23 mSv and 33 mSv, respectively.

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A car-borne survey for dose rate in air was carried out in March and April 2011 along an expressway passing northwest of the Fukushima Dai-ichi Nuclear Power Station which released radionuclides starting after the Great East Japan Earthquake on March 11, 2011, and in an area closer to the Fukushima NPS which is known to have been strongly affected. Dose rates along the expressway, i.e. relatively far from the power station were higher after than before March 11, in some places by several orders of magnitude, implying that there were some additional releases from Fukushima NPS. The maximum dose rate in air within the high level contamination area was 36 μGy h−1, and the estimated maximum cumulative external dose for evacuees who came from Namie Town to evacuation sites (e.g. Fukushima, Koriyama and Nihonmatsu Cities) was 68 mSv. The evacuation is justified from the viewpoint of radiation protection.

We have developed a simple system for viscosity measurement in the range of 10-3 to 101 Pa·s. An aluminum sphere revolves in a sample cell under a rotating external magnetic field, and the rotational speed of the sphere gives the sample viscosity. Low viscosities can be measured by using a micro-probe sphere, since the viscous torque applied to the sphere overcomes the frictional force at a sufficiently small sphere radius. The system is free from contamination and can be easily applied to medical and biological studies.

The third-order optical susceptibilities χ1111 (3)(-3ω; ω, ω, ω)s f o r t w o d i f f e r e n t p h a s e s i n v a n a d y l a n d t i t a n y l p h t h a l o c y a n i n e (V O P c a n d T i O P c) v a c u u m-d e p o s i t e d t h i n f i l m s a r e d e t e r m i n e d b y o p t i c a l t h i r d-h a r m o n i c g e n e r a t i o n (T H G) m e a s u r e m e n t s a t w a v e l e n g t h s 1543 n m a n d 1907 n m. T h e r m a l a n n e a l i n g c a u s e s a p h a s e t r a n s i t i o n w h i c h a c c o m p a n i e s a r e d s h i f t i n t h e i r a b s o r p t i o n s p e c t r a a n d a n i n c r e a s e i n t h e χ^(3) v a l u e o f 2-5 t i m e s i n V O P c a n d T i O P c f i l m s. T h e e n h a n c e m e n t o f t h e t h i r d-o r d e r o p t i c a l n o n l i n e a r i t i e s i n t e t r a v a l e n t p h t h a l o c y a n i n e f i l m s i s d i s c u s s e d i n t e r m s o f m o l e c u l a r p a c k i n g.