Simultaneous measurements of the activity coefficients of counter‐ and by‐ions in polyelectrolyte solutions were carried out. Sodium polyvinyl alcohol sulfate was used as the sample of polyelectrolyte and sodium chloride as the extraneous salt. The activity coefficient of sodium counter‐ion was determined by using a sodium amalgam electrode and that of chloride ion was determined by a sliver‐silver chloride elctrode. It was found that the activity coefficient of both counter‐ and by‐ions has little relationship with the volume of polymer coil, and that the additivity of counter‐ion activity found for hydrogen ion by Mock and Marshall holds also for sodium ion. It was also found that there is good agreement between the experimental results and the theory of Katchalsky and Lifson if we use their same theory for calculating the volume of polymer coil, although the volume is too large to be considered reasonable.

A 1.2 × 1.2 m2 muon tracker was moved from Los Alamos to the Toshiba facility at Kawasaki, Japan, where it was used to take ∼4 weeks of data radiographing the Toshiba Critical Assembly Reactor with cosmic ray muons. In this paper, we describe the analysis procedure, show results of this experiment, and compare the results to Monte Carlo predictions. The results validate the concept of using cosmic rays to image the damaged cores of the Fukushima Daiichi reactors.

This paper reports two new methods that are effective to know the accurate values of the electromechanical coupling factor (kt) and the mechanical Q (Qm) for low Q materials. In order to realize the required sensitivity and bandwidth of an ultrasonic probe, it is necessary to know the accurate values of kt and Q of a material. about twice larger than the exact value when applying the usual resonant-antiresonant method to these materials.The fundamental concept or' the new methods is to derive these constants by comparing certain physical values with measured and calculated values.These methods were applied to several ?iezoelectric materials. It has been found that more reasonable values than those from the conventional method can be obtained.However, the value o? kt becomes

No abstract

The level of radiation exposure in children in Belarus caused by the Chernobyl accident was investigated on the basis of whole body 137Cs count. The subjects were 10,062 children (4,762 boys and 5,300 girls) in Mogilev and Gomel, Belarus, who received Chernobyl Sasakawa Health and Medical Cooperation Project health examinations from May 1991 to December 1992 and who were 5-16 y old at the time of examination. The median whole body 137Cs count per body weight varied from 21-48 Bq kg-1 and from 28-126 Bq kg-1 in Mogilev oblast and Gomel oblast, respectively. (The "oblast" is the largest administrative district constituting the country. Belarus consists of 6 oblasts). Corresponding annual effective dose equivalents were all less than the public dose limit of 1 mSv y-1, but the observed levels in the children were considerably higher than the average level of 2.3 Bq kg-1 reported in the past for the former Soviet Union.