Biomedical subjects
Publications and source records attributed to S Forberg.
The influence of phytic acid on the properties of zinc phosphate cement was studied by adding 2-13 wt% phytic acid to the liquid. Improved mechanical strength and stability were found for some cements prepared from commercial powders when liquids with increased phytic acid content were used. The results indicate that the formation of increased amounts of zinc phytate has a favorable effect on the properties of zinc phosphate cement.
After the Chernobyl accident in April 1986, considerable deposition of radionuclides occurred regionally in eastern, central and northwestern Sweden. Locally, the fallout of radiocesium exceeded the remainder from atmospheric nuclear weapons tests by several magnitudes. Since the end of the 1960s samples of organs from various plant and animal species, annually collected at different localities, have been preserved in the Swedish Environmental Specimen Bank (ESB). In this work samples from the ESB have been used for retrospective studies of radioactive pollution. The activities of Cs-134 and Cs-137 in muscle tissues from reindeer, Rangifer tarandus, and pike, Esox lucius, preserved in the ESB, were measured. The samples were collected annually; the reindeer at three localities in northern Sweden and the pike at one of them. In material collected prior to the Chernobyl accident, the levels of Cs-137 were 57-180 Bq/kg in reindeer and 14-24 Bq/kg in pike, fresh weight basis. These levels relate to earlier nuclear bomb tests. A significant decrease was found in pike during the pre-Chernobyl period (1971-86). In post-Chernobyl samples the burden of Cs-137 varied from amounts equal to the former levels in the northernmost locality and up to 80 times higher for the maximum values in the southernmost locality. The highest value recorded was 18,425 Bq/kg in reindeer. The geographic variations in reindeer from Chernobyl fallout were in accordance with the pattern of deposition estimated by aircraft surveys performed in May 1986. The ratio between 'new' and 'old' radiocesium burdens in pike, caught in 1987, approached the corresponding ratio for reindeer grazing in the precipitation area of the lake; 33 and 19, respectively.
A number of composites based on titania and calcium phosphates, hydroxyapatite, bone ash or beta-tricalcium phosphate, were sintered by glass-encapsulated hot isostatic pressing at 925 degrees C. The mechanical properties of the titania and titania-calcium phosphate composites--three-point bending strength, fracture toughness and Young's modulus--were 250-450 MPa, 2.5-2.9 MPa m1/2 and 230-270 GPa, respectively. Hardness and density were also measured. The results suggest that these composites have potential applications in medicine as implant materials.
The zeolite group of minerals has been suggested as a means of decreasing the uptake of radio-caesium by humans and domestic animals, and also to accelerate the excretion of radio-caesium which has already been absorbed. Artificial mordenite, one of the zeolites being considered for this purpose, was dispersed in liquid paraffin and administered to goats and lambs fed radio-caesium-contaminated hay. Faeces and urine were collected separately and analyzed by gamma spectrometry on each day of the experimental period. At a dose of 10 g day-1 of mordenite, the amount of radio-caesium excreted was more than double the amount ingested with the fodder, due to extraction of the radio-caesium stored in the body. Initially, the effect/dose ratio was even higher. It is shown conclusively that mordenite can reduce the uptake of radio-caesium by goats and lambs, and also, without changing the fodder, reduce their body burden. A similar, preliminary experiment on man was less successful. In another experiment, boiling reindeer meat with mordenite reduced its radio-caesium content to 8%.
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