Application of neutron activation analysis to bone samples

Summary Neutron activation analysis technique, using Au as flux monitor, was applied to determine element concentrations of Ca, K, Na, Mg, Mn and Sr in certified reference material (NIST 1400 Bone Ash). The results were compared with those using comparative INAA and they were compatible. The same results were obtained using the recommended k₀ factors, in order to obtain the activation cross section as input in concentration for the same reference material. Some applications in the health area aiming clinical evaluation in bone samples of medium and small-sized animals were performed and the viability of using this methodology was discussed.     

Purification of soluble fulvic acid low concentrations by a diafiltration technique

The purification of soluble fulvic acids (FA) based on a diafiltration technique is carried out on antarctic water and snow samples, characterised by low humic compound content (0.1-0.8 mg/l). Results are compared with those of FA purified with the dialysis technique that, together with ion-exchange resins, performs an often used purification process. With the adopted procedure it is possible to minimise the high content of inorganic salts deriving in part from the isolation method XAD-8 adopted, as shown by FTIR, elemental and thermogravimetric analysis.     

Sedimentary process inferences from Humic substances analysis and deposition rates (Western Ross Sea,Antarctica)

The first 40?cm of sediment of three basins in the Ross Sea were sampled using a box corer. Site Y1 was located close to the coast in Terra Nova Bay; the sediment of site Y3 was collected in a more distal basin in the central sector of the Ross Sea; finally site Y5 was sampled in the deepest zone of the Joides Basin.

Sediment cores were sliced and analysed with a depth resolution of 2–4.5?cm. The distribution of humic substances and their structural features along the cores were determined and related to the pattern of Total Organic Carbon (TOC) and sedimentological data. The grain size distribution and the ²¹⁰Pb inventories allow the sediment of the study sites to be characterised.

The humic substance content in the sediment decreases, with a change in slope between 23 and 26?cm at Y1, between 12 and 15?cm at Y3 and constant values with further depth. At Y5 the depth profile of humic substance content shows constant values in the upper 17?cm and values decrease with further depth. The pattern of humic substance yield is similar to that found for TOC. The analysis of the elemental composition of the humic acids extracted from different sediment depths shows an increasing C/N atomic ratio at sites Y1 and Y3 and constant values along the Y5 core. The depth profile of the C/N atomic ratio is confirmed by the changes observed in the structural characterisation and indicates a shift from the freshly deposited organic matter on the sediment surface to more humified material (humin). The results obtained highlight a different sedimentation rate at the three sites as deduced from sedimentological analysis.     

Determination of elements in kidney,serum and urine of Wistar rats with Acute Renal Insufficiency using NAA

In this investigation ions in serum, urine and kidney of Wistar rats (control group) and Wistar with Acute Renal Insufficiency (ARI) were quantified using instrumental neutron activation analysis. The measurements in serum and urine were performed before, during and after ischemia-induced ARI. The measurements in kidney were performed for the control and ARI groups. Also, a comparative analysis between the concentration ratios before, during and after ARI was performed in urine and serum samples for both groups. The variations results for Cu in serum and I in urine, before and after ischemia-induced ARI, suggest that these elements must be also investigated in renal dysfunction.     

Ca and Mg determination from inhabitants of Brazil using neutron activation analysis

In this study the neutron activation analysis (NAA) technique was applied to determine Ca and Mg in whole blood from inhabitants of Brazil for the purpose of establishing concentration ranges indicative of sex and age. The initiative to perform these measurements is related to the increase in heart disease. According to recent statistics from WHO, the average is one death due to heart attack in Brazil, every five minutes. The measures were performed considering lifestyle factors (non-smokers, non-drinkers and no history of toxicological exposure) of Brazilian inhabitants. A healthy group constituted of male (n = 94) and female (n = 84) blood donors, ages between 18 and 70 years and above 50 kg, was selected from the blood banks and hematological laboratories of Brazil. The influence of sex was also investigated considering several age ranges (18–29, 30–40, 41–50, >50 years). The results show significant differences when a comparison is made by sex and age and may be useful to identify or prevent clinical diseases. These results emphasize the need to perform periodic evaluation of Ca and Mg in blood.     

Applications of ligand-exchange-III Preparation and properties of phenol-formaldehyde-based resin in the iron(III) form

A number of resins containing ethylenediamine acetic acid groups have been prepared, and these intermediates (resin-EDTA) converted into the iron(III) form. The capacities of these exchangers in the formation of iron(III)-phenol complexes have been studied and compared with those of the Chelex-iron(III) resin. The character of the exchanger matrix is very important in connection with the retention of phenols and with the elution order. The modified Amberlite CG 4B in the iron(III) form can be used for the quantitative separation of phenolic compounds, a separation that is not possible with the Chelex-iron(III) resin.     

Harnack inequality and smoothness for quasilinear degenerate elliptic equations

We prove local and global regularity for the positive solutions of a quasilinear variational degenerate equation, assuming minimal hypothesis on the coefficients of the lower order terms. As an application we obtain Hölder continuity for the gradient of solutions to nonvariational quasilinear equations.     

Circle Maps,Measured Laminations,and Free Group Actions on IR-trees

This paper explores the connection between homeomorphisms of the unit circle, codimension-1 measured laminations on closed surfaces, and free actions of surface groups on IR-trees.     

Use of thermal neutrons to perform clinical analyses in blood and urine samples

Summary In this study we show that the NAA technique can be used to perform clinical analyses of blood and urine, with many advantages towards the conventional methods. From the knowledge of the neutron flux and the induced activity, the concentration ofelements were obtained. In comparison to the conventional techniques, this methodology uses smaller quantities of biological material and allows the simultaneous evaluation of the concentrations of several elements in biological samples at once, something not always possible in the conventional clinical analysis. Another important advantage is that it eliminates the use of standard materials, thus making the analyzing process practical and economic.