Search Results

You are looking at 1 - 10 of 15 items for

  • Author or Editor: E. Rőth x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

The work leading to the discovery of naturally sustained chain reactions at Oklo (Gabonnaise Republic) is described. Conditions for this occurrence are discussed. Information derived from analytical studies in detailed, particularly age of the deposit, duration of the chain sustained reactions, total power evolved. Typical values are respectively 2 109 years, 106 years, one hundred billion kWh. Migration of fission products and transuranian elements can be studied. Rare earths stay mostly with uranium. No indication of plutonium migration is found. Finally operation of the reactor are discussed.

Restricted access

The effect of organic growing was studied on the storability of apple cv. Jonica, Liberty, Mutsuand Pinova. Fruits from integrated and organic orchards were stored at 2-4 °C, 95-99% relative humidity for 6 months. Firmness, activity of b-galactosidase and polygalacturonase enzymes were examined. There was no difference in the activity of β-galactosidase and polygalacturonase enzymes at harvest between the organic and integrated apples, but a significant difference was noted between the cultivars except for Mutsu and Pinova. The activity of b-galactosidase enzyme increased significantly during storage except for cv. Pinova and that of polygalacturonase enzyme also increased significantly. The difference in the activity of polygalacturonase became significant between the cultivars during storage except for cv. Jonica and Pinova. The firmness decreased significantly during storage, with the least change in case of cv. Liberty. It can be established that there is, in general, neither a considerable difference between the growing systems nor between varieties at harvest. The differences became higher during storage. It can be stated that the effect of cultivar on the storability is much more considerable than the effect of growing system.

Restricted access

Abstract  

A method is described which can be used to investigate the interaction of dissolved metals with particulate material. Low level concentrations (10–9M) of rare earth radiotracers were used to investigate their sorption onto synthetic mineral oxide surfaces. The preparation of rare earth radiotracers by neutron activation is discussed in detail. A kinetic approach was employed to investigate the interaction of dissolved metals and suspended mineral oxides. Amorphous iron oxyhyroxide, a phase commonly found in nature, was used in sorption experiments carried out in seawater at pH 7.8 and 2°C. Results of this study indicate a high affinity of the rare earth elements (REE) for the iron oxide surface (evidenced by fast uptake and high partition coefficients) and reveal a fraction between light and heavy REE.

Restricted access

Abstract  

Urinary excretion of232Th was assessed, in occupationally non-exposed persons by means of inductively coupled plasma-mass spectrometry (ICP-MS). Measurements were performed in 55 healthy subjects. Mean daily232Th excretion was 47±26 Bq·d–1 (range 17–121 Bq·d–1). Results obtained showed no statistically significant correlation with age and no differences were found between males and females. The impact on the assessment of intakes by workers is discussed.

Restricted access

Volatile flavour substances were isolated from the minced pulp of half ripe and full ripe fruits of guava (Psidium guajava L.) cv. Lucknow-49 by simultaneous steam distillation extraction (SDE) with diethyl ether as extracting solvent. The concentrate was analysed by GC-MS. Acetic, butyric and hexanoic acids were the predominant acids, trans-2-hexenal and hexanal the predominant aldehydes and ethyl propanoate, methyl butyrate, ethyl butyrate, methyl hexanoate, ethyl hexanoate, cis-3-hexen-1-yl acetate, hexyl acetate, methyl benzoate, methyl octanoate, ethyl benzoate, phenylpropyl acetate and cinnamyl acetate, the esters responsible for the characteristic guava flavour were also present. The amount of total volatile substances was about 20% higher in full ripe fruits. The concentration of acids and most esters increased and that of C6 aldehydes decreased during ripening. The enzyme analysis showed that the polygalacturonase (PG) activity was lower in the ripe fruit, than in the half ripe one, while the β -galactosidase activity was not influenced by maturity stage. The surface and the cell walls of full ripe guava became wrinkled, and parenchyma cells were empty (SEM).

Restricted access

Colour (L*, a*, b*, h o and chroma), β-galactosidase, polygalacturonase (PG) activity, pectin content, ultrastructure and volatile compounds were determined, in mature green and in yellow ber fruits ( Zizyphus mauritiana Lamk. cv. Umran).The L* did not, but a*, b* and h o significantly differed between mature green and yellow ber fruit. The pectin content and its solubilization (soluble pectin and neutral sugars), the activity of PG was higher in yellow ber fruits and in the outer part of fruits. Activity of β-galactosidase was higher in mature green ber fruits. The cell walls of mature green fruits were usually homogeneous, the density of the middle lamellae decreased in yellow bers, and at the same time, the structure of chloroplastids disintegrated. The aroma of yellow ber is characterized by the presence of even carbon number of ethyl esters from C4 to C14.

Restricted access

Abstract  

In order to estimate gut absorption by determining tracer concentration in plasma, a technique based on the administration of two stable isotopes of the same element was combined with proton activation analysis. The optimization for the determination of Zr isotopes in biological samples is presented together with the results of a preliminary study on Zr biokinetics in animals. (p,n) reactions on90Zr and96Zr resulted the most convenient. The obtained minimum detectable quantities are 3 and 2 ng/ml plasma, respectively, for90Zr and96Zr. Zr plasma clearance and Zr response to a simple oral test were studied separately in different subjects by using the natural Zr solution. The data analysis was performed measuring the concentration of90Zr to obtain indication on the time behavior and fractional level of Zr appearance in plasma depending on the administration routes. Two rabbits were intravenously injected 50 g90Zr and a third rabbit was orally given 2.5 mg of90Zr. Concentration in plasma samples of intravenously and orally given Zr isotopes are reported, as a function of time after administration. The injected tracer concentration relative to the first two rabbits were fitted simultaneously to obtain clearance parameters. Zr intestinal absorption is evaluated to be less than 0.2%. The work confirms that proton activation is a powerful tool for biokinetic studies with stable isotopes.

Restricted access

Abstract  

The iodination and separation of various diagnostically and/or experimentally important peptides including (Tyr1)-somatostatin-14, rat Tyr-a-calcitonin gene-related peptide (23-37), motilin and vasoactive intestinal peptide, furthermore bovine serum albumin are described. All species were iodinated by the iodogen method. The 125I-labeled peptide products were separated by reversed-phase HPLC, the specific activities of mono-iodinated forms are near identical with the theoretical value. The labeled bovine serum albumin was separated by Sephadex G-100 gel filtration.

Restricted access

Summary  

Resection and subsequent end-to-end anastomosis of the windpipe is a tried-and-tested acceptable method for the surgical treatment of segmental defects. There are a variety of different techniques for tracheal end-to-end anastomosis, but controversial reports highlight the fact that the suturing technique of the anastomosis is still subject of debate. We aimed to show the postoperative effects of the continuous and simple interrupted suturing technique respectively on the tracheal cartilage using differential scanning calorimetry. Transsection and subsequent reanastomosis of the cervical trachea was performed in 14 adult beagle dogs. The trachea was anastomized with continuous or simple interrupted sutures respectively depict no change in microcirculation after the resection of the trachea, but significant decrease following the completion the anastomosis with continuous sutures. Conventional histological analysis did not show any marked postoperative change in the tracheal cartilage but our DSC scans clearly demonstrated the differences between the intact cartilages and the ones involved in the anastomosis.

Restricted access

Abstract  

Inductively coupled plasma mass spectrometry (ICP-MS) has been applied to the assessment of urinary uranium excretion in non-exposed subjects. The sensitivity of the method is high enough to determine238U concentration in unprocessed urine in any subject. Data obtained so far show a significant increase of238U excretion with age and no differences between males and females.

Restricted access