Human parvovirus B19 infection in adults shows some clinical features similar to those found in autoimmune connective tissue diseases. To better clarify the relationship between viral infection and autoimmunity, we have evaluated the ability of anti-parvovirus antibodies to specifically recognize autoantigens in ten patients with chronic symmetric arthritis resembling rheumatoid arthritis or with recurrent episodes of arthritis and cutaneous manifestations and persistence of specific IgM antibodies against B19 parvovirus. We synthetized a 24-amino acid immunodominant peptide corresponding to a part of the virus protein 1 and virus protein 2 overlapping region. The peptide has been used to test patients' sera at different time points with an enzyme-linked immunosorbent assay (ELISA) and to purify antivirus antibodies by affinity chromatography on a peptide-Sepharose column. Eluted immunoglobulins recognized the B19 peptide in both direct and competitive ELISA. Affinitypurified anti-parvovirus antibodies were then tested on a panel of autoantigens including human keratin, collagen type II, thyreoglobulin, single-strand (ss)DNA, cardiolipin and ribonucleoprotein antigen Sm. Eluted antibodies specifically recognized keratin, collagen type II, ssDNA and cardiolipin. Autoantibody activity was not detected in the immunoglobulin fraction after complete removal of anti-peptide antibodies and in antibodies eluted from normal donors. Epstein-Barr virus-transformed cell clones obtained from two subjects produced antibodies which simultaneously recognize the viral peptide and several autoantigens. To further confirm the role of the virus in inducing an autoantibody response, eight BALB/c mice were immunized with the viral peptide coupled to a carrier protein. Autoantibody activity against keratin, collagen II, cardiolipin and ssDNA was detected in six of the eight mice which developed a strong anti-virus response. Together, these data indicate that B19 parvovirus may be linked to the induction of an autoimmune response.
In this paper are presented data on the preparation and characterization of different oxide electrodes. RuO2–TiO2, IrO2–TiO2, and SnO2–Sb2O5 mixed-oxide films have been taken as model systems. For the first, the traditional preparation method based on the pyrolysis of precursor salt deposits was adopted. For the SnO2-based films, the spray pyrolysis preparation has been used. The characterization of RuO2–TiO2 films confirms the existence of a solid solution between the two component oxides over a wide composition range. Rutherford backscattering spectrometry confirms the occurrence of segregation of titanium oxide species in the outermost part of the films. Nuclear reaction analysis indicates that large amounts of carbon and hydrogen impurities are trapped in the oxide films. SnO2-based films were found to be less porous and chemically more simple. The differences between the two systems have been discussed in terms of the preparation method and the differences in chemical properties of the precursors. Keywords: oxide film electrodes, mixed-oxide films, Rutherford backscattering spectrometry, nuclear reaction analysis.
Ruthenium dioxide films were prepared by radio-frequency magnetron sputtering onto Si and Ti substrates. Films of different thicknesses (100-500 nm) were synthesized at substrate temperatures of 40, 350, and 450 °C. Their composition has been studied by Rutherford backscattering spectrometry, elastic recoil detection, and ion beam nuclear reaction analysis. Scanning electron microscopy and wide-angle X-ray scattering have been used for studying the surface texture of the samples and for their microstructural characterization, respectively. The electrochemical characterization by cyclic voltammetry has shown that, despite the high physical density of the films, compared with that obtained by the thermochemical methods, they exhibit large charge-storage capacities. For the materials synthesized at 350-450 °C, an explanation of these results has been sought in specific features of the RuO 2 rutile-type cell and columnar texture of the oxide film. The much higher capacity of the films synthesized at 40 °C would be rather due to a poor sintering of the oxide phase. Study of the chlorine evolution reaction in the samples prepared at 350 and 450 °C points to a Volmer-Tafel mechanism, with a chemical desorption rate-determining step, and significant radical intermediate coverage. Films deposited at 40 °C exhibited an unsatisfactory wear resistance under the anodic polarization required for the chlorine evolution reaction investigation.
In this study, the Majorana equation for particles with arbitrary spin is solved for a halfinteger spin free particle. The solution for the fundamental state, corresponding to the reference frame in which the particle is at rest, is compared with that obtained using the Dirac equation, especially as regards the approximation in the relativistic limit, in which the speed of the particle is close to that of light. Furthermore, the solutions that Majorana defines unphysical, proving that their occupation probability increases with the particle velocity, are taken into consideration. The anomalous behavior exhibited by these states suggests that for high-energy particles with small mass, transitions from a bradyonic state to a tachyonic state could become possible.
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