Darbe apibendrinami duomenys apie cezio-137 kaupimąsi dirvoje ir jo perėjimą į augalus bei gyvulio organizmą. Pateikti šio izoztopo pasiskirstymo ir kaupimosi įvairiuose gyvulių organuose bei audiniuose dėsniai, apžvelgti įvairūs metodai, mažinantys cezio-137 kaupimąsi ir greitinantys jo pasišalinimą iš gyvulių organizmo bei gyvulininkystės produktų. Tirtas pienas, mėsa, bulvės, grūdai ir geriamasis vanduo iš Šakių rajono. Buvo nustatomas 137Cs savitasis aktyvumas ir bendrieji alfa ir beta aktyvumai. Radiometriniai tyrimai atlikti radiacinės saugos centre. / We have summarized the data concerning accumulation of 137Cs in soil and the transition of the radionuclides to plants and animals. The presented survey gives some information about the distribution and accumuliation of 137Cs in different organs and tissues of animals about the possible methods of reducing the amount of radionuclides in the organism of animals and in products of animal origin. There was tested milk, meat, potatoes, grain and drinking water from Šakiai region. There was instituted the specific activity of 137Cs and general alpha and beta activities. The radiometric tests were performed in the Radiation Protection Centre.

A new cryptand, 1,18-bis[(phenylmethoxy)methyl]-3,16,20,23,26,29,32,35-octaoxatetracyclo-[16.9.9,05,10 09,14]hexatriaconta-5,7,9,11,13-pentaene was synthesized from cis-9,19-bis(benzyloxymethyl)-1,4,7,11,14,17-hexaoxacycloeicosane-9,l9-diyldimethanol and l,5-bis(bromomethyl)naphthlene in the presence of t-butoxide base. The overall syntheses involved five steps. The new cryptand compound has a melting point at 164-1650 C, and the yield was 18.5%. The NMR spectra and the crystal structure determination proved the synthesized cryptand the same as that desinged.Fluorescent measurements were performed with this cryptand. The fluorescence was found to be quenched by cesium ion, and the quenching increased with the increasing of cesium ion concentration. The average quenching of the fully complexed (with Cs +) cryptand was estimated as 20 + 2% by a computerized data fitting program. The complexation constant was determined to be 16 ± 5 M-1. A possible explanation for these observations is presented. / Department of Chemistry

We have obtained spectra of 10 vibrational bands of the Cs₂ (2)³∏_u ← ϰ³∑⁺₉ system. The molecules were formed in a supersonic free jet expansion, and were excited by light from a single mode CW dye laser. The total laser induced fluorescence was measured at 90° to the incident light and molecular beam, using a photomultiplier. Using a slit system to image a selected part of the interaction region, we have reduced the Doppler width to about 350MHz. We have been able to resolve the discrepancy between the different vibrational band positions given in two previous papers. Our vibrational bands show broad rotational contours, but we have not been able to resolve individual rotational lines. We have also obtained rotationally resolved spectra of the bandhead region of 22 vibrational bands of the Β¹∏₉ ← X¹∑⁺_u system. We found that the frequencies of the bandheads agreed with the bandhead positions deduced from the Dunham coefficients of a previous work. We have developed a theoretical model of the rotational structure and intensity distribution, taking into account optical pumping and the small solid angle subtended by the detector. By fitting this model to the experimental spectrum of the v' = 3,u∿ = 0 band using least squares optimization, we were able to extract rotational constants and line positions. We found that these line positions were in good agreement with those from the previous work. We have discussed how such spectroscopic data may be used in a determination of the s-wave scattering length of caesium, and we have reviewed the validity of the scattering length and other pararneterisations of low energy Cs-Cs interactions.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 219-226).

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Made available in DSpace on 2014-10-09T12:43:04Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:48Z (GMT). No. of bitstreams: 0 / O césio 137 (137Cs) é um radionuclídeo crítico do ponto de vista radioecológico por apresentar meia-vida física longa (30 anos), um alto rendimento de fissão e ser um análogo químico do sódio e potássio, elementos fiíndamentais para os seres vivos, presentes em grandes concentrações em todas as células. Este trabalho teve como objetivo estudar o acúmulo e eliminação do 137pela alga Gracilária caudata e peixe Abudefduf saxatilis, a partir da água do mar contaminada com esse radionuclídeo e obter as constantes de transferência do 137Cs da água para os respectivos organismos. O Fator de Concentração encontrado para o peixe foi de 5,6 ± 0,2 e para a alga de 13,0 ± 0,6. Com 7 e 22 dias, o peixe e a alga, respectivamente eliminaram a metade da quantidade do radionuclídeo acumulado. Para o peixe, também foi verificada a sua eficiência de ingestão para o 137Cs, a partir do alimento contaminado, sendo que o peixe assimilou apenas 47,6% do 137Cs presente no alimento e, com 4 dias já havia eliminado mais da metade da radioatividade ingerida. Foi proposto um modelo tri-compartimental para explicar a distribuição do 137Cs nos compartimentos (água - alga e água - peixe). Os dados obtidos nos experimentos de acúmulo e eliminação do 137Cs foram aplicados no Programa AnaComp, que permite a análise compartimental, quantificando através das constantes de transferência (k) a distribuição do 137Cs da água do mar para os organismos e vice-versa. O Programa AnaComp também permitiu calcular a dose que o homem receberia com o consumo do peixe contaminado com o referido radionuclídeo. Foram verificados os níveis de 137Cs, proveniente do fenômeno fallout, em amostras ambientais, da região de São Sebastião, litoral norte do Estado de São Paulo, onde está localizado o Centro de Biologia Marinha da Universidade de São Paulo - CEBIMar - USP. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP