Influence of stearic acid coating of the NaCl surface on the reactivity with NO2 under humidity.

In the atmosphere, sea salt aerosols, containing mainly NaCl, can accumulate fatty acids and undergo heterogeneous chemistry with atmospheric nitrogen oxides. The effect of stearic acid (SA) coating on the reactivity of the NaCl(100) surface with NO2 under humidity was studied by atomic force microscopy (AFM), Raman mapping and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to highlight processes occurring on NaCl surfaces. The vapor-deposition of SA on the NaCl surface generates heterogeneous coating with discontinuous monolayer islands. The SA molecules with all-trans conformation stick to the NaCl surface through -CO2H groups and are organized in parallel between them and nearly perpendicularly to the surface. The SA coating does not prevent the NaNO3 particle formation when the sample is exposed to NO2 under low humidity conditions. The initial abilities of the NaCl surface coated with SA to pick up NO2 from the gas phase are correlated with the fraction of bare NaCl area evidencing the spatially heterogeneous reactivity of the surface. The role of H2O in the NO2 uptake and the catalytic conversion of NaCl to NaNO3 is shown. Under humidity (RH = 50%), the H2O uptake by NaNO3 particles on the coated-NaCl surface is significantly more important than that adsorbed under analogous conditions without the presence of NaNO3 particles. This unusual water absorption initiates transitions (i) from solid NaNO3 particles to NaNO3 aqueous solution and (ii) from the SA monolayer with well-ordered all trans alkyl chains to the SA gel with completely disordered conformation. This mixed SA/NaNO3 layer on the particle surface may have significant consequences on the hygroscopic properties and reactivity of the sea salt aerosols in the atmosphere.

Particle-particle chemistry between micrometer-sized PbSO4 and CaCO3 particles in turbulent flow initiated by liquid water.

A mixture of natural and anthropogenic particles is ubiquitous in the troposphere and exerts an important influence on air quality. This work reports the study of mixing and heterogeneous chemistry of particles of natural-like mineral dust (CaCO(3)) and anthropogenic-like microparticle (PbSO(4)) in turbulent air flow under varying relative humidity. Sparse monolayers of laboratory-generated particles were collected on substrates using impaction. The grain size distribution and chemistry of micrometer-sized particles were determined as CaCO(3)-PbSO(4) internal and external mixtures by Raman imaging, scanning electron microscopy, and time-of-flight static secondary ionization mass spectrometry. The condensation of a thin water layer on mixed aggregates initiates the formation of complex internal mixtures of Pb(3)(CO(3))(2)(OH)(2), PbCO(3), CaSO(4)·2H(2)O, CaCO(3), and PbSO(4) fine particles. These heterogeneous chemistry processes which may occur in ambient air can increase dramatically the amounts of hazardous breathable particles.

Spontaneous charge separation induced by phenothiazine sorption within acidic H(n)ZSM-5.

In situ diffuse reflectance UV-visible, Raman scattering and EPR experiments, carried out as a function of time after phenothiazine (PTZ) direct exposure to thermally activated acid H(n)ZSM-5 zeolite without any solvent, provide evidence of phenothiazine sorption and simultaneous spontaneous ionization. For comparison, phenothiazine behavior was investigated within non acidic zeolite and showed that most of the phenothiazine molecules were occluded as intact molecules and that ionization was very weak. The multivariate curve resolution analysis of the diffuse reflectance UV-visible spectra set recorded during the sorption process resolve the absorption spectra and respective concentrations of individual species involved in the sorption course. When PTZ entered through the acidic zeolite channels, PTZ (+)@H(n)ZSM-5 (-) radical pair is generated by the polarization energy. Subsequent PTZ(2+) formation was fast but only partial. After months, equilibrium including PTZ (+), PTZ(2+) and occluded PTZ was reached within acid H(n)ZSM-5 but depends on the Si/Al ratio: the higher the Al content, the easier the spontaneous ionization. The close match between PTZ and the pore size of zeolites combined with efficient polarizing effect of proton and aluminium electron trapping sites appear to be the most important factors responsible for the stabilization of PTZ (+) and PTZ(2+) and hinder efficiently the charge recombination. No evidence of Brønsted acid sites of H(n)ZSM-5 was found during the sorption of phenothiazine through generation of protonated species.

Conformation and protonation of 2,2'-bipyridine and 4,4'-bipyridine in acidic aqueous media and acidic ZSM-5 zeolites: a Raman scattering study.

In situ FT-Raman scattering spectroscopy was used to monitor the sorption kinetics of 2,2'- and 4,4'-bipyridine in acidic ZSM-5 zeolites. The data processing of all the Raman spectra was applied to extract the characteristic Raman spectra of occluded species and respective Raman contribution generated from many spectral data which resolves spectrum of mixture into pure component spectra without any prior information. The assignment of the extracted spectra was performed according to careful comparison with corresponding spectra extracted from a set of Raman spectra recorded during the protonation of 2,2'- or 4,4'-bipyridine (bpy) in hydrochloric acid aqueous solutions. The data processing of the Raman spectra recorded during the slow sorption of 4,4'-bpy in acidic H(n)ZSM-5 (n = 3, 6) zeolites provides specific Raman spectrum of N,N'-diprotonated dication 4,4'-bpyH(2)(2+) as unique species generated in the void space of acidic ZSM-5 zeolites. No evidence of Lewis acid sites was found during the sorption of 4,4'-bpy by Raman scattering spectroscopy. The data processing of the Raman spectra recorded during the slow sorption of 2,2'-bpy in acidic H(n)ZSM-5 (n = 3, 6) zeolites provides specific Raman spectrum of trans-N-monoprotonated cation 2,2'-bpyH+ as major species generated in the void space of acidic ZSM-5 zeolites at loading corresponding to 1 mol per unit cell. The trans/cis interconversion occurs at higher loading even after the complete uptake of the sorbate and indicates some rearrangement in the void space over a long time. The cations were found to be located in straight channels in the vicinity of the intersection with the zigzag channel of the porous materials with the expected conformations deduced from ab initio calculations. However, the motions of occluded species within the channel of ZSM-5 are hindered but remain in the range of the isotropic limit of a liquid at room temperature.

A familial occurrence of natural killer cell--T-lymphocyte proliferation disease in two children.

Several reports describe the association of hyperlymphocytosis with neutropenia. This syndrome, named lymphoproliferative disease, is characterized by a chronic indolent clinical course, bone marrow lymphocyte infiltration, and granulopenia of central origin. The proliferating lymphocytes share large granular lymphocyte natural killer cell and T-lymphocyte characteristics. They are either of monoclonal or polyclonal origin. In this report the familial occurrence of a similar syndrome observed in two children is described. Lymphocyte morphologic abnormalities including nuclear pockets, were noted, a feature usually present in leukemic cells. Lymphocyte proliferation was distinct in each case as shown by the presence of a predominant CD4+ cell population in one and a predominant CD8+ population in the other. Monoclonal gene rearrangements of T-cell receptor beta-chain gene were found although clonal variations occurred with time in one patient. The cause of this unique familial occurrence of monoclonal lymphoproliferation associated with neutropenia is unknown.

Serum IgG subclass levels in patients with primary immunodeficiency syndromes or abnormal susceptibility to infections.

Serum IgG subclass levels were measured using an indirect competitive immunoenzymatic assay with monoclonal antibodies in 221 patients affected with definite immunodeficiency (ID) syndromes and 229 patients presenting with infection patterns suggestive of ID, but with normal immunoglobulin class levels and no clear evidence of ID. In common variable ID and IgG-IgA deficiency with normal or high IgM, subclass imbalance (mostly IgG1-IgG3 or IgG2-IgG4 deficiency) was the rule, with a higher incidence of severe infections in IgG2-IgG4 defects. One-fifth of patients with IgA deficiency, especially those with autoimmune cytopenia, had subclass deficiencies with no significant correlation with the occurrence of infections. Subclass (mostly IgG2-IgG4) deficiencies were also observed in severe combined ID, defective expression of HLA class II antigens, chronic mucocutaneous candidiasis, and IgM deficiency. Subclass levels were normal in all but one (who was IgG3 deficient) patient with the Wiskott-Aldrich syndrome and in the Buckley's syndrome, except for an unusual patient who presented with low IgG and IgA levels. Subclass (mainly IgG2) deficiency occurred in 24% of infected patients without known ID.

[Aspergillus infection and chronic septic granulomatosis]. / Infection aspergillaire et granulomatose septique chronique.

Chronic granulomatous disease of childhood is a hereditary abnormality of phagocytic cells, frequently associated with Aspergillus infections. From 1969 to 1984, 14 of 37 children with chronic granulomatous disease have presented with pulmonary (13 cases) and/or osteo-articular (1 case) aspergillosis. The paucity of symptoms was a characteristic of these infections. Lung lesions extending to the thoracic chest wall carried the bad prognosis. Neither the Aspergillus skin test nor the Aspergillus serology could definitely confirm the diagnosis. Only broncho-alveolar lavage and biopsy with isolation of Aspergillus could confirm the diagnosis. Long-term therapy with amphotericin B alone or associated with other antifungal agents is necessary. For the past 3 years, ketoconazole prophylaxis has been used in 23 children and none of these children has developed aspergillosis.