Search Results

You are looking at 1 - 10 of 32 items for :

  • Chemistry and Chemical Engineering x
  • Refine by Access: All Content x
Clear All

Abstract  

The aim of the study reported in this paper was to derive factors describing the translocation of radiocesium from the green plant parts to the crop. Wheat, rye and potatoes were contaminated and harvested at different growth stages to allow the assessment of the contamination of the crop with known date of the radioactive deposition. At harvest, the cesium concentrations in the crop, the green plant parts (i.e., straw without ears) and the roots were measured. The results show that the contamination of the crop depends strongly on the date of134Cs application and on the type of plants. The highest translocation was observed when cesium was applied during flowering.

Restricted access

Abstract  

An extensive investigation of elemental levels in cereals and their cultivation soils has been going on across the main production areas of mainland Portugal, with a view to an eventual biofortification of major cultivars through agronomic practices. Cereals are an obvious choice as primary vehicles for food-supplementation programs, especially in countries where they definitely weigh in the dietary intake (like Portugal), and regions whose geographical and/or pedological features may account for nutrient deficiencies in typical diets. Mature rye plants (Secale cereale L.; roots and grains) and local soils were collected in the summer of 2009 from two regions of northern Portugal, and put through k 0-standardized, instrumental neutron activation analysis (k 0-INAA). Overall, the results (elemental concentrations, enrichment factors, transfer coefficients) seem to confirm an efficient uptake of elements from soil and their translocation to the aerial parts of the plants, notably to the ones that really matter in human nutrition (grains).

Restricted access

M. Rye B. Walczak L. Gidskehaug J.P. Wold

Full access
Journal of Thermal Analysis and Calorimetry
Authors: M. Matthews, I. Atkinson, Lubaina Presswala, O. Najjar, Nadine Gerhardstein, R. Wei, Elizabeth Rye, and A. Riga

Abstract  

Dielectric analysis (DEA), supported by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), powder X-ray diffraction analysis (PXRD) and photomicrography, reveal the chiral difference in the amino acids. The acids are classified as dielectric materials based on their structure, relating chirality to the vector sum of the average dipole moment, composed of the constant optical (electronic) and infra-red (atomic) polarizabilities, as well as dipole orientation. This study encompasses 14 L-and D-amino acid isomers. Physical properties recorded include AC electrical conductivity, charge transfer complexes, melting, recrystallization, amorphous and crystalline phases, and relaxation spectra, activation energies and polarization times for the electrical charging process.

Restricted access

Abstract  

The radioactive content of alfalfa and rye grass was measured in five consecutive harvests covering a period of one and a half years after the contamination of a field caused by the Chernobyl fallout. The measured long-lived isotopes were106Ru,134Cs and137Cs. In the first four harvests alfalfa contained significantly less radioactivity than rye grass, while in the last harvest both plants contained comparable levels of radioactivity. The results from the first harvest, demonstrating the radioactivity obtained in the direct fallout, indicate that the fraction of total initial deposition retained on rye grass is by 55% and 70% greater than alfalfa for Cs and Ru isotopes, respectively. The second, third and fourth harvests demonstrate values of plant to soil concentration ratios /CR/ considerably larger than those observed in the fifth harvest. Only the CR values obtained in the last harvest overlap with commensurate values previously reported in the literature.

Restricted access

Abstract  

The Pb and Br content of plants growing along roads has been determined. It has been stated that the Pb-content of rye grass is proportional to the level of public road traffic. The Pb-content of plants cannot be removed by washing. The Pb, Cu and Zn-concentration of plants grown in the vicinity of smeltery may reach the 10–1000 times value of the normal level.

Restricted access

Summary  

Cereal flours are the major component of the Brazilian diet and are also important exportation products. Radioactivity concentrations of 232 Th, 226Ra, 40K and 137Cs were determined in commercial samples of South-Brazilian cereal flours (soy, wheat, corn, manioc, rye and oat flour) to verify the radiological security of these foodstuffs. The measurements were carried out by gamma-ray spectrometry using a 66% relative efficiency HPGe detector. The 40K flour activities,   at 95% of confidence level were in: soy 474±3 Bq . kg-1; corn 30.0±0.3 Bq . kg-1; rye 94±1 Bq . kg-1; manioc 67±1 Bq . kg-1; oat 76±1 Bq . kg-1 and wheat 36.2±0.4 Bq . kg-1. The lower limit of detection for 40K ranged from 0.54 to 1.43 Bq . kg-1. The 137Cs activities in flour samples were: soy £0.07 Bq . kg-1, corn £0.01 Bq . kg-1, oat £0.03 Bq . kg-1 and in wheat, manioc and rye £0.02 Bq . kg-1. The highest concentrations levels of 232 Th and 226Ra were 0.69±0.04 Bq . kg-1 and 0.44±0.03 Bq . kg-1, respectively, in soy flour.

Restricted access

Abstract  

Distribution coefficients of 14 elements between LIX 70 in toluene and aqueous 1M NaNO3 solution containing varying concentrations of HCl or suitable buffer, respectively, were determined by batch equilibration. It was shown that very selective separation of Cu from other elements can be achieved on columns with LIX 70 supported on Bio-Beads SM-1. Highly accurate and precise method for the determination of trace amounts of Cu in biological materials was devised by combining NAA with extraction chromatography. Results of copper determination in NBS 1570 /Spinach/, IAEA H-4 /Animal muscle/ and IAEA V-8 /Rye flour/ are presented.

Restricted access

Abstract  

In this work the term blank signifies total radiation of the sample analyzed except that the element to be determined (analyte) is absent. On the basis of the evaluation of the blank components (nuclear and spectral interferences, air-nitrogen between grains etc.), a semiempirical formula for calculating the nitrogen content in plant grain samples is proposed. The reliability of the results obtained with the use of this formula has been demonstrated for five sorts of seeds (rye, wheat, barley, broad bean and soybean) which have been analyzed by the Kjeldahl method and 14 MeV neutron activation analysis, respectively.

Restricted access