Nitrogen and phosphorus are the most important macronutrients among 17 nutrients required for optimal plant growth and reproduction. These elements are always present in cereal crops and play a determining role in the quality of plant products. For this reason, methods for determining their content simultaneously are of immediate interest in connection with monitoring grain quality.Fast neutron activation analysis is the most suitable method for determining nitrogen and phosphorus content in grain, pulse, and other agricultural crops [1,2]. This article presents the results of additional studies of a method for simultaneous determination of nitrogen and phosphorus in grain, pulse, hulled, and kernel crops using the NG-150 neutron generator at the Institute of Nuclear Physics of the Academy of Sciences of the Republic of Uzbekistan [2][3][4].The nuclear reaction 31 P(n, α) 28 Al was used to determine phosphorus content (Table 1). Aluminum is used as a monitor for checking the neutron flux [2]. The nuclear reaction 28 Si(n, p) 28 Al is an interfering reaction when determining phosphorus, and the reaction 29 Si(n, p) 29 Al is used to take account of this interfering effect on the method [5].The neutron activation method was developed to determine the nitrogen and phosphorus content in samples of certain grain, pulse, hulled, and kernel crops -wheat, millet, beans, buckwheat, dried apricots, apricots, pistachios, and peaches. Samples with mass 19-22 g were weighed and packed in 40 mm in diameter, 35 mm high cylindrical polyethylene containers. A polyethylene top tightly sealed a container. A 35-50 mg, 0.1 mm thick aluminum monitor was secured to the top for monitoring the fast-neutron flux. Some nitrogen and phosphorus compounds served as comparison samples. The test procedure for standard nitrogen is described in detail in [2,3]. The phosphorus content in the plants is 0.1-0.6% [6]. For this reason, the comparison samples were prepared from compounds in which the phosphorus mass falls approximately within these limits. The samples were irradiated in identical fast neutron fluxes. The time regimes of irradiation of the samples and measurement of their induced activity were also identical. Figure 1 displays the dependence of the variation of the 28 Al activity (in this case the number of counts recordedthe area of the photo-peak of the γ-ray 1778.8 keV line) versus the phosphorus mass in the comparison samples. This dependence is rectilinear within the limits of the chosen phosphorus concentration range, whence it follows that the method can be used to determine correctly the content of the element in biological materials. It is evident that for some samples the deviation of the data from rectilinearity is substantial (>30%). Such a deviation could be due to possible mass losses as a result of long-term storage of chemical compounds or sorption of water from air. For this reason, compounds which fell on the rectilinear sections of the plot were used as the comparison samples. Thus, the approach for developing a method...
The objective of the present work is to use instrument neutron-activation analysis to study the trace-element composition of the hair of children living in the densely populated Chilanzar district of Tashkent and listed in the clinical register as suffering from iron-deficiency anemia. The objects of investigation were hair samples obtained from four groups of children -31 boys and 24 girls ranging in age from 10 to 176 months: 1 -cured (10 children) and 2, 3, 4 (28, 11, 6 children) -low, medium, and high severity of illness. For analysis, a strand of hair 2-4 cm long from the root was taken from four or five locations on the back of the head, carefully washed in acetone, dried, weighed, packed in marked polyethylene packages, and analyzed using the procedure of [1].The source of neutrons with flux density 6·10 13 sec -1 ·cm -2 was the VVR-SM reactor at the Institute of Nuclear Physics of the Academy of Sciences of the Republic of Uzbekistan. The irradiation and cool-down times, depending on the half-life, for nuclide with short (T 1/2 < 10 min), medium (10 min < T 1/2 < 1 day), and long lives (1 day < T 1/2 < 1 yr) were 15 sec and 10 min, 15 h and 10 days, and 15 h and 30 days, respectively. The induced activity of the samples was measured with a gamma spectrometer equipped with a germanium detector with sensitive volume 120 cm 3 and energy resolution 1.8 keV on the 60 Co 1330 keV γ-line. The GENIE 2000 program was used to process the data.The measurement error for the main elements does not exceed 12%. The detection limit for most elements is much lower than the measured content. Cadmium and iodine were found in a limited number of samples.As Table 1 shows, the distribution range of the content of all elements is wide and is independent of the severity of the iron-deficient anemia and the age of the patients. The difference between the maximum and minimum concentrations of some elements is a factor of 2-3. The data in Table 1 were compared with the data obtained by other authors [2-5] ( Table 2). The data obtained by these authors also confirm the large difference of the trace-element concentrations in human hair. For example, the difference between the minimum and maximum concentrations of individual elements reaches a factor of 20 [3]. Apparently, such differences can be even larger in children's hair, since juveniles characteristically experience intense growth and therefore rapid metabolism. The data obtained by the authors of the present article match the data in the works mentioned above to within the distribution range of the concentrations of Cr, Mn, Zn, Se, Br, Rb, Ag, and Sb.Investigations of iron-deficiency anemia show that the variation of the concentration of individual chemical elements as functions of the severity of the illness in children exhibits regularities. Thus, it was found that the content of Fe, Mn, Sc, Co, K, Ca, Se, Rb, Sb, La, and Au content in children's hair increases in children with a greater severity of iron-deficiency anemia while the concentration of Cu, Zn, As, and U decrease...
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