International Journal of PIXE

Presented are new parameters for the calculation of L subshell ionization cross sections for proton impact using a semiempirical expression. A similar paper was published by our group in early 1993 but the fitting parameters were obtained by using only 2295 experimental L shell cross section data. Since then a large number of experimental data have become available and therefore a new fitting has been performed employing more than 5000 data points. All available data were fitted separately for L1, L2 and L3 subshells. For targets with low atomic numbers (14≤Z≤42), only coefficients for L_tot were obtained. Because of the slight Z dependence of the universal function, data were also devised into five sub-groups according to their atomic numbers and fitted separately within each group for L1, L2 and L3 subshells. To extend the energy range of validity of the new fitting function theoretical values were used in the high energy region where experimental data were lacking. Results are compared with ECPSSR predictions and discussed.

Concentrations of chemical elements in different organs of healthy, of tumor (rhabdomyosarcoma R1H) bearing and of cis-diamminodichloroplatinum (cisDDP) treated rats were analyzed with a 2 MeV proton microprobe. Characteristic concentrations were found in spleen, liver, kidney, muscle and tumor. Bromine concentrations were elevated after three weeks of tumor growth. As a result of cisDDP application, they dropped considerably. These alterations were found not only in tumor tissue but also in organs not directly involved in tumor growth (e.g. liver and spleen). Platinum as a marker for the drug could be detected in all tissues except muscle. The highest concentrations were found in the kidney. With the scanning microprobe, elemental maps in several tissues were investigated. These could be correlated to histological details (e.g. in spleen and tumor).

The study of atmospheric aerosols originating from natural and anthropogenic processes is of basic importance for a detailed understanding of the physics and chemistry of the atmosphere. Particle Induced X-ray Emission (PIXE) technique has been used by the authors for studying regularly the elemental composition of rural, suburban, and urban aerosols collected at six sampling sites in Hungary. Observed data presented in terms of concentrations and regional signature values and evaluated wind sector partition and in transport modelling revealed the natural/anthropogenic contribution to the moderate air pollution here. Dry deposition velocities have been deduced for elements V, Cr, Mn, Co, Ni, Cu, Zn, Cd, and Pb. Model calculations based on annual emission data and observed elemental concentrations resulted in total dry and wet deposition masses of the above elements to the territory of the country. At the same time, deduced budget data for the emission and deposition of the constituents indicated whether the country represents a net source or a sink for the above mentioned elements in the regional aerosol transport between neighbouring countries. Evidences have been found for intrusion events of Saharan aerosol to the atmosphere of Hungary. Part of the data collected recently will be evaluated in the frame-work of an international co-ordinated research programme.

It is found that the ratio of X-ray energies of Kα and K β lines is approximately equal to the ratio of its peak positions in the spectrum. This result can be used for identificaion of peaks in experimental energy-dispersive X-ray spectra.

PIXE analysis was applied to study alteration of mineral composition (Al, P, K, and Cl) of alfalfa root-tip exposed to low pH or aluminum stress. These minerals were detectable using one or two pieces of root-tips. Short-term (within 4 h) decreases in K/P and Cl/P ratios were observed under low pH and aluminum stress conditions. However, degree of the decrease was not same. Differences in toxic effects of low pH and Al on the root-tip of alfalfa are discussed.

Zn-DTPA was injected intraperitoneally into rats (30 µmol/kg) with a single dose or a daily dose for 10 consecutive days. Urine samples were collected for 24 hours after the single injection and tissue samples were excised 20 hours after the final of the consecutive injections. Elements in these samples were analyzed by PIXE. Zn-DTPA raised the urinary concentration of zinc and copper, and their urinary losses caused by Zn-DTPA were estimated to be 1.9 and 0.01 mg/30μmol Zn-DTPA, respectively. The concentration of metals in the liver, kidneys, brain and femurs remained unchanged. These results suggest that almost all of Zn-DTPA is excreted into the urine without replacement with other metals, and so this chelating agent may not induce any deficiencies of essential metals when animals are treated with a dose of 30 µmol/kg per day.