Search Results

You are looking at 81 - 90 of 2,214 items for :

  • "absorption" x
  • All content x
Clear All

Abstract  

The supplement effect of Cu, Fe, K, Mg, Mn and Zn chelated with glycine on the absorption of these elements by animals was evaluated. The evaluation was carried out by comparing the mineral concentrations found in hair of the animals before and after 47 days of supplementation with a combination of glycine-mineral chelates. Five horses known to be clinically well were used for this study. Instrumental neutron activation analysis (INAA) was applied to the determination of Cu, Fe, K, Mg, Mn and Zn concentrations in the horse hair samples. It was observed that the supplementation helps the Fe, K and Zn absorption by the animal organism. The data obtained suggest that the hair is a suitable material to investigate Fe, K and Zn in mineral metabolism in the animal organism.

Restricted access

Abstract  

An analytical exercise between two laboratories was performed in order to compare the elemental composition of a water sample. The metal concentration of Cr, Cu, Fe, Mn, Ni, Pb, and Zn in the water sample was analyzed by Total Reflection X-Ray Fluorescence and Atomic Absorption Spectrometry. The analysis by Total Reflection X-Ray Spectrometry was realized by an Ital Structures TX-2000 and the analysis by Atomic Absorption Spectrometry was made by a Perkin Elmer Spectrophotometer Model 3110. Results show a good agreement in the metal concentrations obtained by both techniques. The variation coefficient between the results with both techniques was less than 14%. Therefore, it is possible to conclude that both techniques are reliable and adequate for the determination of these elements in environmental water samples.

Restricted access

This article seeks to assess how the absorption of European the Union funds by the Polish voivodeships reflects two basic types of strategy in their allocation, i.e. the polarising and the equalising model. The analysis embraced 16 regional operational programmes (ROPs) between 2007–2013. The frame of reference adopted in the research was the centre-periphery model. Classes of peripherality were distinguished for each voivodeship, and absorption profiles of EU funds were determined for areas differing in their levels of peripherality. The goal of the article was achieved in a multi-stage research procedure ending in the construction of a synthetic index of the spatial orientation of support within the ROPs. The analysis demonstrated that the features of the polarising model tended to predominate in intra-regional policy. In most cases, however, the distribution of EU support represented a mixed model, with a shift towards the polarising one.

Restricted access

Abstract  

A simple method to determine -ray attenuation coefficients using Ba-133 -rays has been developed and applied to self-absorption correction in routine -ray spectrometry for environmental samples composed of unknown matrix elements. Experimental values of the mass attenuation coefficient obtained by the method agree well with calculated values for samples of known elemental composition which was determined by means of chemical analysis.

Restricted access

High ozone (O3) can cause great damage to plants. However, the effect of high O3 on nitrogen (N) absorption, distribution, and utilization in rice at different growth stages under different planting densities is poorly understood. In the present study, a conventional cultivar (Yangdao 6) and a hybrid cultivar (II You 084) with different planting densities were exposed to an elevated amount of O3 (E-O3; 50% higher than that of the control, C-O3) under a freeair gas concentration enrichment (FACE) system. N absorption, distribution, and utilization of the green leaves, stems, and shoots at tillering, jointing heading, and maturity were investigated. Results showed that E-O3 significantly increased the N content in the shoots of Yangdao 6 by 7.5%, 12.7%, and 19.6%, respectively, at jointing, heading, and maturity. Also, the N content in the shoots of II You 084 increased by 5.4%, 6.5%, and 8.4% at the corresponding growth stage upon E-O3 application. E-O3 significantly decreased N accumulation of II You 084 by 8.3%, 4.9%, 4.7%, and 19.2%, respectively, at tillering, jointing, heading, and maturity. Further, E-O3 had a decreasing effect on the N distribution in green leaves (p ≤ 0.05) of both cultivars, but exerted an increasing effect on that in the stems of both cultivars (p ≤ 0.05). In addition, E-O3 significantly decreased the N use efficiency (NUE) for biomass of the two cultivars in all growth stages. These results revealed that E-O3 could increase the N content in rice plants but decrease the N accumulation and utilization in both cultivars. The effects of E-O3 on N absorption, distribution, and utilization were not affected by planting density.

Restricted access

Abstract  

Twenty six bottom sediment samples were collected from the Cananéia estuary in summer and winter of 2005. Multielemental analysis was carried out by instrumental neutron activation analysis. Total mercury was determined by cold vapor atomic absorption. As, Cr, Hg and Zn concentrations were compared to the Canadian oriented values (TEL and PEL). Sample points 4 and 9 presented higher concentration for most elements and As and Cr exceeded the TEL values. Organic matter (>10%) associated with siltic and clay sediments was observed. Climatic conditions, hydrodynamic and biogeochemical processes promote differences in seasonal concentrations of elements at some points, which contribute to special distributions.

Restricted access

The electrical conductivities and the electronic, IR and NMR spectra were measured for some ethyl cyanoacetate phenylhydrazone derivatives and their lanthanide complexes in the temperature range 20–200‡C. Semiconducting behaviour was detected for these systems (positive dσ/dT). A correlation was established between the electrical properties and the structures of the free ligand molecules and their complexes. The mechanism of the conduction process was evaluated. The electronic absorption spectra in ethanol were measured and are discussed. Elemental analyses were performed and the IR and NMR spectra (of the diamagnetic complexes) were measured to throw more light on the structures of these complexes.

Restricted access

Summary  

A simple, selective and sensitive method was developed based on electrothermal atomic absorption spectrometry using Zeeman correction for quantitation of lead, in 100 ml of whole blood sample, as biological indicator for occupational exposure. Confidence parameters and stability of samples were considered. Ashing and atomization temperatures, considered critical, were 700 °C and 1,700 °C, respectively. The levels found during the validation process showed good sensitivity linearity, recovery, precision and accuracy. The stability results presented levels remaining constant for a 15 months period. The variations were not higher than 15% when comparing concentrations in zero time to those obtained after storage period.

Restricted access

Abstract  

Methods for the determination of manganese in blood by radiochemical neutron activation and flame atomic absorption spectrometry have been developed. Both methods are applicable for routine use in preventive medical checkups of workers who are exposed to manganese. The accuracy and precision of both methods have been tested by analyzing standard freeze-dried blood (A-13) prepared by the International Atomic Energy Agency. The blood manganese contents of 109 non-exposed people living in Bangkok have been analyzed. The concentrations are normally distributed with a mean value of 1.47 g/100 cm3 and a standard deviation of 0.50 g/100 cm3.

Restricted access

Abstract  

A fairly simple radiometric method has been developed for the quantitation of microgram amounts of mercury in lead samples of different purity grades. It is mainly based on 3 steps; (i) the removal of most interfering cations with ferric hydroxide scavenger in the presence of a suitable masking agent, (ii) the separation of mercury as hydrated mercuric oxide from a highly alkaline medium, (iii) its distillation as mercuric chloride followed by precipitation as the sulfide. The method is reproducible and the results which show, in general, a standard deviation of ±4.29% are compared with those obtained by atomic absorption (4.48%) and spectrophotometric (13.13%) techniques.

Restricted access