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- Author or Editor: E. Schmidt x
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Summary
In this paper, a description is made of the survey that was undertaken, for the first time, about the situation of radiochemistry activities in the Region of Latin America, comprising twenty countries from South America, Central America and the Caribbean. It became clear from this study that very strong differences exist between the countries and that most of the nuclear facilities in operation, such as nuclear reactors, hot cells, radiochemical laboratories and cyclotrons are concentrated in seven countries, accompanied by research and educational activities. A detailed study of the situation and trends in the Latin American countries is presented, as regards teaching and other activities related to Radiochemistry, as well as a series of suggestions for preservation of knowledge in the field.
Abstract
In the course of our work within the framework of an interdisciplinary project dealing with the absolute dating of fossil bones from Austrian caves by means of the U-series method we became interested in possible U-concentration gradients in the bone samples. A successful attempt is reported to make the U-distribution in bones directly visible by irradiating the samples with thermal neutrons and detecting the emitted fission products of235U in a plastic foil using the track etch method. This turns out to be possible also for relatively small U-concentrations of the order of 1 ppm. The uranium seems to concentrate near the surfaces which is in qualitative agreement with earlier results from the literature obtained by means of neutron activation analysis.
The control and optimization of the glass-making process is a serious problem in glass production. An EGD procedure involving high-temperature vacuum extraction and total pressure measurement allows determination of the fining state (Läuterzustand) and fining behaviour (Läuterverhalten). The fining state is characterized by the contents of CO2, N2 and other gases from the batch reactions, and gas inclusions. Oxygen evolved in a second step is characteristic for the fining behaviour.
Über die Gamma-Bestrahlung von Cycliten
III. Bestrahlung von Myo-inosit in Wässriger Lösung unter Stickstoff
Abstract
Irradiating myo-inosite of 1% solution under N2 atmosphere, it was established that the oxidation goes only up to monoketone (myo-inose-2) and a desoxy derivative 1,3,5/2,4-cyclohexapentite (scyllo-quercite) occurs. A new polymer was also observed which did not take place during irradiation under O2 atmosphere.
Radiopharmaceuticals
VIII. Preparation of 6-123I-nicotinic acid diethylamide for potential brain studies
Abstract
By nucleophilic isotope exchange, 6-123I-nicotinic acid diethylamide (6-123I-NADA) was synthesized in a solution of the starting compound and catalytic amounts of CuCl in acetic acid. After purification by high pressure liquid chromatography radiochemical yields up to 97% could be obtained within 10 minutes. In mice the radioactivity was rapidly accumulated in the brain reaching the maximum (4.16%/g) 0.5 minutes after i.v. injection and eliminated by a fast and a slow phase. At the maximum of accumulation the brain/blood ratio was 1.21, decreasing to less than 0.15 already after one hour.
Über die Gamma-Bestrahlung von Cycliten
I. Möglichkeiten zur Dc-Trennung des Wässrigen Reaktionsgemisches: Qualitative Bestimmung der Spaltprodukte
Abstract
With different TLC-methods the Rf-values of myo-inosite, myo-inosose (2), (I) epi-inosose, tetrahydroxy-p-chinon, d, 1-myo-inosose-2-phenylosazon, d,1-xylo-4,5,6-trihydroxy-2-oxo-1,3 bis(phenylhydrazono)-cyclohexan are qualitative determined.
Über die Gamma-Bestrahlung von Cycliten
II. Bestrahlung von Myo-Inosit in Wässriger Lösung Unter Sauerstoff
Abstract
After irradiation of an aqueous 1% myo-inosite solution in presence of oxygen, following radiolysis products are qualitative demonstrable: 2,3,5/4,6-pentahydroxycyclohexanon, d,1-3,5/4,6-tetrahydroxycyclohexandion, d,1-xylo-4,5,6-trihydroxycyclohexan-1,2,3-trion, tetrahydroxy-p-benzochinon, glyoxylic acid, formic acid and carbon dioxide. The increase in the concentration of the radiolysis products is followed by a loss of myo-inosite. In dependence of radiation dosis the above mentioned radiolysis products are quantitative determined.
From Y- to Siamese-twin shaped glycolipids
Influence on the thermotropic phase behaviour
A set of Y-shaped and Siamese-twin shaped carbohydrate based glycolipids was investigated using polarising microscopy. The structure was changed from the normal type (1 head, two chains) to complex inverted structures (2 heads outside 1 to 3 chains in the middle part). The carbohydrate headgroup was changed from mono- to disaccharide; also the alkyl chain length was varied systematically. The compounds displayed different thermotropic mesophases (Smectic A phases, columnar phases and cubic phases) depending on the type of carbohydrate headgroup and the alkyl chain length.
