Complexation of Ni (II) and Zn(II) ions by 3-(1-naphthyI)-2-mercaptopropenoic acid

The complexation equilibria between Ni(II) and Zn(II) metal ions with 3-(1-naphthyl)-2-mercaptopropenoic acid (H₂NMP) were studied by glass electrode potentiometry, at 25 °C and 1.0 mol·dm^–3 in NaClO₄ as constant ionic medium in 50% (v/v) water-ethanol solutions. Formation constants for the complexes Ni(NMP), Ni(NMP) ₂ ^2– , Zn(NMP) and Zn(NMP) ₂ ^2– , refined by the MINIGLASS program, are reported.     

DNase activity ofMicrococcal endonuclease insolubilized on corn cob

The endonuclease from S. aureus has been immobilized on ground maize cob, previously activated with tosyl chloride. Pretreatment of the support on acid before tosylation yielded the best insoluble enzyme derivatives. The catalytic activity has been evaluated as percent of total hydrolysis attained in a batch reactor using DNA as a model substrate. The derivatives prepared are very resistant to high temperatures under conditions of catalysis (24 h at 45 degrees C). For these long reaction times, the extent of hydrolysis in the presence of small amounts of organic solvent (dimethyl sulfoxide at 2 percent) is larger than in plain buffer (Tris). This type of derivative could be very useful for the removal of nucleic acids from single-cell protein concentrates.     

Study of the ternary system FeCrTe around the composition FeCr2Te4

The system FeCrTe was investigated around the composition FeCr₂Te₄. FeCr₂Te₄ is a metastable compound. Single crystals with Fe_0·93Cr_1·76Te₄ composition were grown by vapor transport or the Bridgman method. These crystals are metallic and anisotropic ferromagnets.     

On approximation by bivariate incomplete polynomials

In this paper we prove that given certain convex domains Δ on the plane, ε>0, andf∈C(Δ) such thatf=0 on θ²Δ={(θ² x,θ² y):(x,y)?Δ} (0<θ<1), a polynomialp(x, y) of the form $$p(x,y) = \sum\limits_{\theta n \leqslant k + l \leqslant n} {a_{kl} x^k y^l }$$ exists such that ∥f?p∥ _C(Δ) ≤ε. The admissible convex domains include triangles and parallelograms with a vertex at the origin and sections of unit disk.     

Formal orthogonal polynomials revisited. Applications

From some results concerning the formal orthogonal polynomials, already proved in [5], we develop new properties of generalized adjacent polynomials which correspond to a change in the weight function. A new structure of the singular blocks is given. These results have a direct application to Lanczos methods, theG and -algorithms.