IGAA and XRF methods used in oil contamination research

The release of trace metals from oil industry in ecosystems represents a serious hazard for the Biosphere, because of their toxicity. The objective of the study is to identify the source and evaluate the effect of key contaminants and other toxic and non-toxic bioactive elements as well as to provide the basis for improved health for human population by the use of instrumental gamma-activation analysis in combination with the X-ray fluorescence technique.The analytical work consisted in measuring trace concentrations of specific oil industry pollutants in soil and river sediments from the region of oil refinery industry in Ploiesti city, Romania.A highly sensitive photon neutron activation method based on the (γ, n) reactions for determining the concentrations of trace heavy metals in the environmental samples is applied. Additionally, the replicate samples were investigated by the X-ray fluorescence analysis.Further the results were used to develop an approach based on the geostatistical modelling to update the estimates of heavy metal concentrations on the ground in order to quantify their extent in the region in relation with the emission sources.     

Numerical calculation of the terahertz field-induced changes in theoptical absorption in quantum wells

In the presence of a strong terahertz field, the optical (i.e., valence-to-conduction band) transitions in semiconductors occur between states which are altered by the terahertz field. This alteration has a direct impact on the optical absorption. We describe a numerical technique for calculating the optical absorption in this case by solving the Schrodinger equation for the electron-hole envelope function in real space. This technique correctly accounts for the Coulomb interaction between optically created electron-hole pairs and nonperturbative terahertz-field induced alteration of the states. We applied this technique to investigate the optical absorption of quantum wells of finite width in which terahertz/optical mixing can be significant and which cannot be treated analytically     

Influence of mineral components on laser-induced fluorescence spectra of calcified human heart-valve tissues

Laser-induced fluorescence (LIF) spectra of calcified human heart-valve tissue and LIF spectra of macroscopic calcinosis fragments dissected from human heart valves were compared with LIF spectra of pig myocardium tissues. Excitation was provided by an excimer laser with wavelength lambda = 248 nm. Fluorescence bands that were due to mineral and organic tissue components were identified by measurement of LIF spectra of macroscopic fragments of calcified tissues that had been heat treated at 700 degrees C. The studies showed that LIF spectra of calcified tissues include fluorescence emission from tryptophan, collagen, elastin, and a mineral component of tissue, hydroxylapatite. The observed differences in LIF spectra of normal and calcified tissues with different pathologies may result not only from calcification-induced changes in relative collagen and elastin concentrations but also from additional (absent in normal heart tissue) fluorescence of hydroxylapatite. The calcification-induced changes in the LIF spectra of human heart-valve tissues, characterized by a 330/450 nm ratio, were found to be quite appreciable, which suggests that this ratio can be used with LIF measurements to evaluate the degree of heart-tissue calcification.     

Pathological findings in human autoimmune lymphoproliferative syndrome

The defects in lymphocyte apoptosis that underlie the autoimmune lymphoproliferative syndrome (ALPS) are usually attributable to inherited mutations of the CD95 (Fas) gene. In this report, we present the histopathological and immunophenotypic features seen in the lymph nodes (n = 16), peripheral blood (n = 10), bone marrow (n = 2), spleen (n = 3), and liver (n = 2) from 10 patients with ALPS. Lymph nodes showed marked paracortical hyperplasia. Interfollicular areas were expanded and populated by T cell receptor-alphabeta CD3+ CD4-CD8- (double-negative, DN) T cells that were negative for CD45RO. CD45RA+ T cells were increased in all cases studied. The paracortical infiltrate was a result of both reduced apoptosis and increased proliferation, as measured by in situ detection of DNA fragmentation and staining with MIB-1, respectively. The paracortical proliferation may be extensive enough to suggest a diagnosis of malignant lymphoma. Many of the paracortical lymphocytes expressed markers associated with cytotoxicity, such as perforin, TIA-1, and CD57. CD25 was negative. In addition, most lymph nodes exhibited florid follicular hyperplasia, often with focal progressive transformation of germinal centers; in some cases, follicular involution was seen. A polyclonal plasmacytosis also was present. The spleens were markedly enlarged, more than 10 times normal size. There was expansion of both white pulp and red pulp, with increased DN T cells. DN T cells also were observed in liver biopsies exhibiting portal triaditis. In the peripheral blood, the T cells showed increased expression of HLA-DR and CD57 but not CD25. CD45RA+ T cells were increased in the four cases studied. Polyclonal B cell lymphocytosis with expansion of CD5+ B cells was a characteristic finding. Taken together, the histopathological and immunophenotypic findings, particularly in lymph nodes and peripheral blood, are sufficiently distinctive to suggest a diagnosis of ALPS. Of note, two affected family members of one proband developed lymphoma (T-cell-rich B-cell lymphoma and nodular lymphocyte predominance Hodgkin's disease, respectively).     

Apparatus for Investigating the Electrical and Optical Parameters of Pulsed Spark Discharges

A circuit and the structural features of apparatus for the synchronous recording of the electrical and optical characteristics of spark discharges, which occur between two electrodes at low voltages, are described. The parameters are recorded in digital form with a discreteness of 4 sec.