A serendipitous conversion of enaminolactone nitriles with primary amines: a new synthesis of substituted 2-aminopyridine derivatives

In the course of our studies on Cerpegin analogues synthesis, a serendipitous reactivity of enaminolactone nitrile has been observed. Instead of expecting iminocerpegins, we have gained new class of substituted 2-aminopyridines. The methodology has been applied on a wide range of primary amines, as aliphatic, aromatic, heteroaromatic and also, diamines, hydrazines and chiral amines.     

Bacteria encapsulation in colloidal inorganic matrices: Is it a general method?

Zirconium oxyhydroxide nanoparticles prepared by an aqueous route were evaluated for Escherichia coli bacteria encapsulation. A low viability rate was measured 24 hours after immobilization that could be attributed to nanoparticle cytotoxicity. Moreover, the presence of glycerol, a long-term cell-preserving molecule, hindered gel formation, probably due to its adsorption on the nanoparticle surface. A comparison with boehmite and ferrihydrite gels previously synthesized following a similar aqueous colloidal route suggests that the generalization of this method will rely on a careful control of the nanoparticle surface reactivity and may require surface chemical modification.     

Korrosion

Ohne Zusammenfassung     

Vollständige Lösung der unbestimmten GleichungX 3q+Y3=1 in ganzèn Zahlen

Ohne ZusammenfassungDer detaillierte Beweis des in dieser Note enthaltenen Satzes ist 1915 in russischerDer detaillierte Beweis des in dieser Note enthaltenen Satzes ist 1915 in russischerDer detaillierte Beweis des in dieser Note enthaltenen Satzes ist 1915 in russischerDer detaillierte Beweis des in dieser Note enthaltenen Satzes ist 1915 in russischerDer detaillierte Beweis des in dieser Note enthaltenen Satzes ist 1915 in russischer     

Über die Darstellung der Zahlen durch die binären kubischen Formen von negativer Diskriminante

Ohne Zusammenfassung     

Evaluation of Vanadium(IV) as a Non-radioactive Surrogate for Technetium(IV) by Comparison of Stability Constants for Polyamino Polycarboxylate Ligand Complexation

The stability constants for the Tc(IV) and V(IV) complexation with the polyamino polycarboxylate ligands IDA, NTA, HEDTA and DTPA were determined using liquid–liquid extraction techniques. These stability constants were then used to evaluate the validity of using V(IV) as a chemical analogue for Tc(IV). Results suggest that Tc(IV), as TcOOH⁺, will form β _1?11 complexes with the selected ligands, while V(IV), as VO²⁺, will form β ₁₀₁ complexes. The values for these determined stability constants are (in log₁₀ unit) 10.9 ± 0.1, 11.4 ± 0.1, 14.9 ± 0.1, and 20.1 ± 0.1 for Tc(IV) in 0.5 mol·L^?1 NaCl at 25 °C, for IDA, NTA, HEDTA and DTPA, respectively, they are 9.3 ± 0.1, 11.6 ± 0.2, 15.8 ± 0.1, and 20.8 ± 0.1 for V(IV) in 0.5 mol·L^?1 NaCl at 25 °C, for the same suite of ligands. The incorporation of a hydroxide into the metal ligand complexes formed by Tc(IV) is proposed as the largest factor differentiating the apparent stability constants of Tc(IV) and V(IV). This work shows that V(IV) is a poor analog for Tc(IV); however, despite the differences in complexation mechanism between V(IV) and Tc(IV), V(IV) still appears to have some use for predicting Tc(IV) complexation behavior.     

Dimethylsulfoxide as a kinetic booster for the chemical generation of singlet oxygen in methanol

The kinetic booster effect of dimethylsulfoxide on the chemical generation of singlet oxygen, ¹O₂, from the disproportionation of hydrogen peroxide catalyzed by molybdate ions in methanol has been evidenced by detection of the IR luminescence of ¹O₂ at 1270 nm and by ⁹⁵Mo NMR spectroscopy. DMSO interacts rapidly, through a direct oxygen transfer with the stable tetraperoxomolybdate , leading to DMSO₂ and to the unstable triperoxomolybdate , which releases ¹O₂. The procedure was applied to accelerate the dark singlet oxygenation of β-citronellol and α-terpinene.