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In a preliminary study, in vivo skull measurements and in vitro urine measurements of 210 Pb and nat U have been performed to find out the individual, chronic exposure to waterborne natural radionuclides of a small group of Finnish people. For their domestic water, the studied individuals use water from drilled wells containing elevated concentrations of natural uranium and its daughter nuclides ( 234,235,238 U, 222 Rn, 226,228 Ra, 210 Po, 210 Pb). Enhanced 210 Pb and 235 U activities were observed in several people. A positive correlation is observed between the U concentration in urine (μg d -1 ) and the number of counts (cpm) in the gamma ray energy peaks originating from the decay of 235 U and 234 Th respectively. Calibration of the detector setup and the determination of background sources are in progress.

In vivo skull measurements of 210Pb have been performed to assess the individual, chronic exposures of two persons living for 28 years in a house with a distinctly enhanced radon concentration of more than 10,000 Bq/m3. A partial body counter consisting of 4 HPGe detectors, which were placed close to parietal positions of the head, was used in the study. The lower limit of detection of 210Pb activity in the skeleton was found to be 40 Bq. Lead-210 activities of up to 152 Bq were found in the test persons, whereas no activity could be measured in an unexposed control person. The cumulative uptake of 210Pb into the body was assessed for each single test person by using the ICRP respiratory tract and the biokinetic models. A fairly good agreement (within a factor of 2) between in vivo measurements and model was achieved for these two test persons. The technique used in the study may be a useful tool to evaluate assumptions, which have to be made for the reconstruction of individual, cumulative exposures to high radon concentrations.

Cumulative and independent fission product yields of the reaction197Au(d,f) were determined at a beam energy of 80 MeV at the Julich isochronous cyclotron. Off-beamγ-ray measurements applying a catcher foil technique and chemical separation, and in inbeam kinetic energy measurements of fission products were performed. The complete yield distribution of post neutron emission fission fragments is represented by a single function, consisting of the product of two Gaussians. The mass distribution is characterized by the widthσ A =12.5amu. The width of theZ-distribution for eachA-chain is given byσ Z =0.63amu.

Mossbauer absorption experiments on 57 Fe of deoxygenated myoglobin crystals and on K 4 57 Fe(CN) 6 dissolved in the water of metmyoglobin crystals were performed over a large temperature range. At low temperatures the mean square displacements, 〈 x 2 〉, of the iron indicate solid-like behaviour of the whole system, whereas at higher temperatures protein-specific modes of motion contribute to 〈 x 2 >. The protein dynamics are correlated with the mobility of the water within the protein crystals. A Brownian oscillator is used to model the protein-specific modes of motion measured at the 57 Fe nucleus. Three modes are necessary for understanding the Mossbauer spectrum. Two of them correspond to an extremely overdamped Brownian oscillator. The third mode can be understood as quasi-free diffusion. Whereas the protein molecule is frozen in conformational substates in the low temperature regime, it reaches transition states with a finite probability in the high temperature regime. The surface water mediates a possible trigger mechanism that switches on protein dynamics within a narrow temperature interval. Results from Mossbauer spectroscopy and from X-ray structure analysis are compared.

From Mossbauer spectra of the 36.2keV and 69.5keV gamma rays of189Os, isomer shifts and electric quadrupole interactions for a number of chemical compounds of osmium in the oxidation states +8, +6, +4, +3, and +2 were obtained. The results show that the dependence of the isomer shifts on the oxidation state of Os follows the general pattern established for other transition elements like Ru and Ir. A comparison of the isomer shift data with electron densities at the Os nuclei resulting from relativistic self-consistentfield calculations for free Os ions yieldsΔ 〈r2〉 [36 keV]=−2.0 · 10−3 fm2 andΔ 〈r2〉 [69 keV]=−0.13 · 10−3 fm3 for the changes of the mean-square nuclear charge radius of189Os. These values are in qualitative agreement with an interpretation of the low-energy level scheme of189Os in terms of two rotational bands.

Mössbauer spectra of human deoxyhemoglobin and hemochrome frozen solutions, selectively enriched with 57Fe in either the alpha chains or the beta chains, were measured from 4.2 to 250 K. The Lamb-Mössbauer factor, ln f = 4II2 [x2]gamma/lambda 2, was calculated from these spectra and gives the structural dynamics of the iron atom (heme). Large differences in the mean-squared displacement, [x2]gamma, of the heme between hemochrome and deoxyhemoglobin at temperatures above 210 K were observed, demonstrating that when iron is bound to a rigid part of the protein (i.e., distal histidine in hemochrome), motions of the heme are suppressed (i.e., the dynamics are decreased). Comparison of the motions of these two hemoglobins proves that molecular diffusion can be neglected in an analysis of the dynamics below approximately 250 K.