We present a computational method for the ab-initio study of the magneto-optical quantities using the augmented plane wave plus local orbitals (APW+lo) method. The calculations are performed within ...the local- density (LDA) approximation. In the present paper, the optical conductivity is the basic quantity for the evaluation of the magneto-optical Kerr effect (MOKE). Thus it is well described and calculated. Considerable work has been performed on the magneto-optical Kerr effect using experiments, however, no experimental or theoretical work has been investigated on rare-earth silicide ErSisub2, in particular using ab-initio method. Our results consist a prediction.
Conducting poly(o-toluidine) (POT)/titanium dioxide (TiO2) nanocomposite have been synthesized by in situ chemical oxidation polymerization of o-toluidine in the presence of TiO2 nanoparticles. The ...various composites were synthesized by changing the percentage load of titanium dioxide nanoparticles in poly-ortho-toluidine matrix. The synthesized nanocomposites were characterized by using Scanning electron microscopy (SEM), X-Rays diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The POT/TiO2 nanocomposites were further employed to evaluate the photocatalytic potential of the composite materials towards reactive violet 1.
The purpose of this study is to further understanding of the structural, electronic, magnetic properties of CdO doped with transition metal (Mn) and non metal element (N). The calculations are ...performed by the developed full-potential augmented plane wave plus local orbitals method within the spin density functional theory. As exchange–correlation potential we used the generalized gradient approximation (GGA) form. Moreover, the electronic structure study for our compounds was performed with and without oxygen deficiency. We treated the ferromagnetic and antiferromagnetic states and we found that all compounds are stable in the ferromagnetic structure, and all doped materials CdO:Mn and CdO:N adopt the half metallic character. In addition, we notice that the oxygen vacancy destroyed the ferromagnetism in N doped CdO, while Mn doped CdO becomes semiconductor.
Freeze-fracture analysis has shown that treatment of cells with phorbol myristate acetate (PMA) results in a loss of intramembranous particles (IMP) associated with the external leaflet of their ...plasma membranes. It has also been demonstrated that phorbol esters markedly enhance the sensitivity of tumor targets to natural killer (NK) cells, although the mechanism underlying this phenomenon has remained unexplained. Since the ability of NK cells to recognize neoplasms appears to be inversely related to the concentration of sialic acid on the target cell surface, it seemed possible that phorbols affect membrane glycoproteins which have terminal carbohydrates bearing sialic acid residues. To investigate whether phorbol treatment could be responsible for the loss of sialic acid, four tumor cell lines were examined before and after exposure to PMA. A reduction in surface sialic acid was established by four different methods: 1) standard thiobarbituric acid analysis of cell hydrolysates, 2) metabolic labelling of cells with 3H-mannosamine followed by treatment with neuraminidase, 3) chromatography of membrane extracts, and 4) freeze-fracture analysis of lectin-labelled intact cells. These observations suggest a mechanism whereby phorbols may facilitate NK-cell-mediated cytolysis. In addition, an entirely novel effect of these tumor-producing agents may have been uncovered.
Because brief exposure to phorbol esters renders normal cells vulnerable to deformation and cytolysis by lymphocytes, it was postulated that these tumor promoters might cause a hitherto unrecognized ...physical alteration in membrane architecture. To investigate this possibility, four tissue culutre cell lines (K-562 erythroleukemia cells, melanoma cells, N1121 adult fibroblasts, and normal fetal fibroblasts) and three blood cell types (lymphocytes, monocytes, and platelets) were subjected to freeze-fracture analysis before and after brief treatment with phorbol myristate acetate. Phorbol myristate acetate caused a 50% reduction of intramembranous particles associated with the external leaflet (E face) of the plasma membrane of every cell except platelets. In contrast, no change in size or number of intramembranous particles associated with the protoplasmic membrane leaflet (P face) was evident. Since the platelet membrane is known to be turned ``inside out,'' as regards the partition coefficient of the intramembranous particles, the disparity between the results obtained with platelets and other cells may serve to determine the nature of intramembranous particles affected by phorbols. Also, since phorbols affect primarily glycolipids and/or glycoproteins anchored in the external membrane leaflet, these findings may provide a useful tool for future exploration of membrane structure.
A simple and efficient methodology for the synthesis of triarylamines from aryl chlorides in a single step has been demonstrated using a novel CuI/tributyl phosphine catalyst system with high ...activity and selectivity (80-87% yield).
Phenazine methosulfate, a cationic electron carrier, inhibits the extracellular growth of promastigotes and the conversion of amastigotes into promastigote forms of Leishmania mexicana amazonensis. ...Growth inhibition and damage of extracellular parasites by PMS was counteracted by superoxide dismutase, a scavenger of the superoxide anion (O2-), and to a lesser extent, by catalase, a scavenger of hydrogen peroxide (H2O2). Inactivated dismutase and catalase were ineffective. Thus, damage of isolated L.m. amazonensis by phenazine methosulfate, involves the participation of O2- and H2O2. The role of the oxygen metabolites in the toxicity of phenazine methosulfate remains unknown. That O2- can damage the parasites is supported by the finding that superoxide dismutase also protected promastigotes from damage induced by oxygen intermediates generated by a xanthine-xanthine oxidase system. Killing of the parasites by crystal violet, a triphenylmethane, or basic blue 24, a phenothiazine, was not inhibited by superoxide dismutase.
It is well recognized that physical contact between natural killer (NK) cells and tumor targets is necessary for cell lyses. Therefore, any modulation of the tumor cell surface that alters ...intercellular contact could affect NK cell cytotoxicity. To examine this hypothesis, a contact inhibitory factor (CIF), which had been shown to restore contact inhibition of growth to several malignant cell lines was tested for its ability to render such cells immune to recognition by NK cells. When three NK‐sensitive melanoma and two NK‐sensitive colon carcinoma targets were cultured with CIF, they did not only change morphologically, but also showed a 70% to 95% reduction in their sensitivity to lysis by NK cells. In addition, K562 cells, which grow in suspension and do not permit a morphologic evaluation of the CIF effect, also became resistant to lysis by NK cells after culture with CIF. CIF did not reduce the viability nor the cytotoxicity of NK cells. GIF did not contain interferon nor did the GIF‐treated targets induce the production of interferon during the cytotoxicity assay. It is concluded that restoration of contact inhibition of growth and resistance to NK cell lysis are cell surface phenomena that may run in parallel.
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