Sn Interactions Research Articles

Laboratory Studies of Galvanic Corrosion I. Two-Metal Couples

Abstract Galvanic interaction of stainless steel 304L, Ni 270, Cu, Ti-6AI-4V, Sn, 4130 steel, Cd, and Zn has been studied in 3.5% NaCl using galvanic current and weight loss measurements in 24-hour tests. Galvanic couples of 4130 steel and one of the Al alloys 1100, 2024, 2213, 6061, and 7075 have also been evaluated in tap water and distilled water. Galvanic current data can be used to assess both the effect of different dissimilar cathode materials as well as the relative susceptibility to galvanic corrosion of anode materials. For 3.5% NaCl, it has been found that the effect of the cathode material decreases in the order Cu > Ni > stainless steel >Ti-6Al-4V, while the relative susceptibility of anode materials decreases in the order Sn > Zn > 4130 steel > Cd. An analysis of data in various electrolytes shows that coupling of 4130 steel to Al alloys leads to cathodic protection of the steel in 3.5% NaCl, but to accelerated corrosion in tap water and distilled water.

Effective ion-ion interactions of group IV elements and the stability of diamond-type structure

Effective ion-ion interactions of Si, Ge, Sn and Pb are calculated in terms of the perturbation theory based on pseudopotentials. Stability of diamond-type structure for Si, Ge and alpha -Sn is given by the extended perturbation theory.

Mitochondrial inclusions in fibroblast culture from a patient with beta-methylcrotonylglycinuria.

Sialoadhesin (Sn) is a sialic acid–binding Ig-like lectin expressed selectively on macrophage subsets. In a model of experimental autoimmune encephalomyelitis, Sn interacted with sialylated ligands expressed selectively on CD4⁺Foxp3⁺ regulatory T cells (Tregs) and inhibited their proliferation. In this study, we examined the induction of Sn ligands (SnL) on all splenic CD4⁺ T cells following in vitro activation. Most CD4⁺ Tregs strongly upregulated SnL, whereas only a small subset of ∼20% CD4⁺Foxp3⁻ T cells (effector T cells [Teffs]) upregulated SnL. SnL⁺ Teffs displayed higher levels of activation markers CD25 and CD69, exhibited increased proliferation, and produced higher amounts of IL-2 and IFN-γ than corresponding SnL⁻ Teffs. Coculture of activated Teffs with Sn⁺ macrophages or Sn⁺ Chinese hamster ovary cells resulted in increased cell death, suggesting a regulatory role for Sn–SnL interactions. The key importance of α2,3-sialylation in SnL expression was demonstrated by increased binding of α2,3-linkage–specific <i>Maackia amurensis</i> lectin, increased expression of α2,3-sialyltransferase ST3GalVI, and loss of SnL following treatment with an α2,3-linkage–specific sialidase. The induction of SnL on activated CD4⁺ T cells was dependent on <i>N</i>-glycan rather than <i>O</i>-glycan biosynthesis and independent of the mucin-like molecules CD43 and P-selectin glycoprotein ligand-1, previously implicated in Sn interactions. Induction of ligands on CD4⁺Foxp3⁻ Teffs was also observed in vivo using the New Zealand Black × New Zealand White F1 murine model of spontaneous lupus and SnL levels on Teffs correlated strongly with the degree of proteinuria. Collectively, these data indicate that SnL is a novel marker of activated CD4⁺ Teffs that are implicated in the pathogenesis of autoimmune diseases.

A spectroscopic investigation of complexes of tin(II) fluoride with strong Lewis acids

SbF5, AsF5, and BF3 all form 1 : 1 adducts with SnF2, and SbF5 also forms a 1 : 2 adduct, SnF2,2SbF5. Tin(II) fluoride also reacts with fluorosulphuric acid to give Sn(SO3F)2. On the basis of their vibrational and 119Sn Mossbauer spectra, the 1 : 1 adducts are formulated as salts of the fluorine-bridged (Sn–F)nn+ cation with the anion SbF6–, AsF6–, or BF4–. The spectral results show that there is appreciable covalent cation–anion interaction in Sn(SO3F)2 and also in SnF2,2SbF5 which is best regarded as Sn(SbF6)2. The latter compound has the highest reported 119Sn Mssboauer isomer shift.

The crystal structure of dimethyltin diisothiocyanate

The crystal structure of Me 2Sn(NCS) 2 has been determined by single crystal X-ray diffraction. The crystals are orthorhombic, Pmmn, a = 9.79(2), b = 7.88(2), c = 5.57(2) Å, Z = 2. The structure consists of rather distorted tetrahedral dimethyltin diisothiocyanate molecules, linked by SSn interactions to form infinite chains along the Z axis with a repeat unit of one molecule. The SnC(H 3) bonds lie in a plane perpendicular to that of the planar Sn(NCS) 2 groups; the NCS units are vitually linear. The principal bond lengths and angles are: SnN 2.139(13), NC 1.174(14), CS 1.571(13), SSn 3.202(7), SnC(H 3) 2.089(14) Å; < SnNC 163.5(1.1), < NCS 177.2(1.2), < CSSn 90.4(0.5), < (H 3)CSnC(H 3) 148.9(0.9)°.