14-MeV neutron activation analysis /NAA/ and radiochemical separation technique were used for the determination of Cu in Hungarian minerals. The separation of Cu from other elements is a possibility to avoid the interferences in the 511 keV -line.
Authors:S. Szegedi, M. Váradi, Cs. Buczkó, M. Várnagy, and T. Sztaricskai
Neutron transmission method has been used for the determination of boron in borosilicate glasses. The method is sensitive and rapid to control the spatial homogeneities of glass-product in the melting furnace.
Authors:S. Jonah, A. El-Megrab, M. Váradi, and J. Csikai
An improved experimental setup based on the thermalization and reflection of neutrons has been used for the determination of total H content and (O+C)/H atomic ratio in oil samples. The count rate response function for this setup gives a relative error of about ±1.5% and a detection limit of 0.09 H w% in the case of different hydrogeneous samples of 300–500 cm3 volumes. Results obtained for motor and household oils as well as for crude oil samples from Nigeria and Hungary are presented.
Authors:S. Szegedi, G. Kanalics, M. Váradi, and Gy. Zilizi
Ta impurities in Nb samples have been determined by X-rays in 14 MeV neutron activation analysis. For X-ray detection, (HP) Ge detector with Be-window is used. The sensitivity of the determination has been found to be about 30 g (in Nb).
Authors:N. Adányi, E. E. Szabó, M. Váradi, and J. Szamos
To explore new possibilities of enzyme immobilization, we investigated bioactive layers prepared by a new procedure based on three-phase partitioning (TPP) of proteins. By this method a third phase or midlayer as a protein layer can be developed at the interface of a protein system containing two phases (organic solvent/aqueous salt solution). Proteins of meat origin partitioned together with bioselective material (e.g. an enzyme) after centrifugation resulted in excellent bioactive layers.In the newly developed sensor, glucose oxidase was immobilized in a layer, which was fixed on the surface of a platinum ring electrode. The biosensor was built in a flow injection analyzer (FIA) system, where the hydrogen peroxide generated during the enzymatic reactions was determined by an amperometric cell. The parameters for biochemical and electrochemical reactions (ion concentration and pH of buffer, flow rate) were optimized. The linear range of analysis by the newly developed sensor was from 0.5 to 10 mmol l–1 glucose. The biosensor could be used for more than 300 analysis.
Authors:T. Müller, B. Váradi, P. Horn, and M. Bercsényi
Previously described and alternative methods of the induction of sexual maturation in the European eel were investigated. Weekly administrations of a gonadoliberin agonist (GnRH-A=D-Phe6-GnRH-Ea) did not induce statistically significant effect on the gonads of treated eels in none of the dosages used (0.1 mg and 10 mg/fish). Carp pituitary extract and carp pituitary extract together with a dopamine antagonist caused considerable external changes (increase in eye size) and significant gonadal development in two treatment groups: wild and cultivated stocks. The induction of the ovulation by double amount of CP and gonadoliberin agonist with dopamine antagonist mixture was not successful in a wild stock. Fertilisation of stripped eggs of farm eel was attempted unsuccessfully in, due to low egg quality. An advanced phase of the sexual maturation process could be induced in specimen infected by Anguillicola crassus indicating, that nematode infection is not a limiting factor in the artificial propagation of the European eel.
Authors:S. Szegedi, D. Mosbah, M. Váradi, and I. Szalóki
For a non-destructive determination of the protein content in soya bean samples, 14-MeV neutron activation analysis /NAA/ was applied. To check the method, results obtained by X-ray fluorescence /XRF/ analysis and the Kjeldahl procedure were compared. For pressed pellet samples of about 1 g and choosing 15 min irradiation and 10 min measuring times the accuracy of the protein determination was found to be 15%.
Authors:N. Adányi, M. Váradi, I. Sziklai-László, P. Snyder, R. D. Snyder, and M. Á. Cser
Total daily Se intake was determined by duplicate diet collection, venous blood samples were taken and urine was collected over 24 h in order to measure selenium input and output in healthy, American and Hungarian children aged 8 to 17 living in Budapest. The American children consumed not only locally processed food. Food samples were weighed, mixed, homogenised and the Se content was determined by Instrumental neutron activation analysis (INAA). The Se concentration of blood, plasma and urine samples was determined by atomic absorption spectrometry-hydride generation (AAS-HG) after wet digestion. Se intake calculated for wet weight was 62±18.5 mg/day in American children. In the Hungarian children the mean Se intake was about 35% less than in the Americans. Se concentrations in plasma were 0.84±0.16, in whole blood 1.13±0.17 mmol l-1 in the Americans, higher than those in healthy Hungarian children (0.64±0.10 and 0.83±0.12 mmol l-1, respectively) of similar age and gender. Urinary Se output calculated for creatinin was higher in the children from abroad (27.0±9.5 mg Se/day/g creatinin) compared to Hungarians (11.0±5.0 mg Se/day/g creatinin).
Authors:T. Müller, F. Baska, F. Niklesz, P. Horn, B. Váradi, and M. Bercsényi
The artificial induction of sexual maturation of European eel males was carried out by using weekly hCG administrations. Histological pictures showed that the testis tissues developed and regressed naturally and no pathological changes took place under the conditions of artificial rearing in freshwater. According to light and electron microscopic investigations the morphology and motility of the spermatozoa of males kept in freshwater proved to be similar to those in seawater. The authors suppose that freshwater rearing of males is not a barrier factor in the artificial propagation of European eels.