Matrix problems and stable homotopy types of polyhedra

This is a survey of the results on stable homotopy types of polyhedra of small dimensions, mainly obtained by H.-J. Baues and the author [3, 5, 6]. The proofs are based on the technique of matrix problems (bimodule categories). Dedicated to C. M. Ringel.     

Simultaneous Determination of Zinc and Cadmium with 1-(2-Pyridylazo)-2-Naphthol in Aqueous Micellar Solutions Using Two-Dimensional Absorption Spectra

The simultaneous determination of zinc and cadmium with 1-(2-pyridylazo)-2-naphthol in aqueous micellar solutions using two-dimensional data arrays for the dependence of absorbance on the wavelength and pH was considered. Determination errors were minimized by optimal selection of analytical wavelengths in the spectrum and pH.     

Resistance of Cu(Aβ4–16) to Copper Capture by Metallothionein‐3 Supports a Function for the Aβ4–42 Peptide as a Synaptic CuII Scavenger

Aβ4‐42 is a major species of Aβ peptide in the brains of both healthy individuals and those affected by Alzheimer's disease. It has recently been demonstrated to bind Cu^II with an affinity approximately 3000 times higher than the commonly studied Aβ1‐42 and Aβ1‐40 peptides, which are implicated in the pathogenesis of Alzheimer's disease. Metallothionein‐3, a protein considered to orchestrate copper and zinc metabolism in the brain and provide antioxidant protection, was shown to extract Cu^II from Aβ1‐40 when acting in its native Zn₇MT‐3 form. This reaction is assumed to underlie the neuroprotective effect of Zn₇MT‐3 against Aβ toxicity. In this work, we used the truncated model peptides Aβ1‐16 and Aβ4‐16 to demonstrate that the high‐affinity Cu^II complex of Aβ4‐16 is resistant to Zn₇MT‐3 reactivity. This indicates that the analogous complex of the full‐length peptide Cu(Aβ4‐42) will not yield copper to MT‐3 in the brain, thus supporting the concept of a physiological role for Aβ4‐42 as a Cu^II scavenger in the synaptic cleft.     

EPR investigations of structure of humic acids from compost, soil, peat and soft brown coal upon oxidation and metal uptake

Free radical concentration and theirg-values in humic acids (HA) isolated from various sources were studied by quantitative EPR technique. EPR data for HA formed during composting and natural humification processes occurring in soil, peat and brown coal are given. In more detail the EPR data were analyzed for brown coal HA under carbonization, air oxidation (150°C) as well as metal uptake (Ca(II), Zn(II), Cd(II), Hg(II), Co(II), Ni(II) and Cu(II)) and NO₂ reaction. Two groups of metal complexes were distinguished on the basis of their interaction with free radicals in HA. Ca(II), Zn(II), Cd(II) and Hg(II) ions increase free radical concentration, while Co(II), Ni(II) and Cu(II) ions quench the radicals compared to the raw HA. This phenomenon can be explained either by the strong interaction of the metal ions with active centres responsible for the quinone-hydroquinone-semiquinone equilibria, and/or by the antiferromagnetic interaction between radical spins and metal d orbitals. Gaseous ammonia was found to be a very useful base easily penetrating the solid matrix of HA and strongly influencing the equilibria. β-Diketone groups present in HA react with NO₂ yielding iminoxy radicals. In the HA-metal complexes these structural units are engaged in metal coordination which lowers effectiveness of the iminoxyl synthesis.     

Insertion of zero-valent platinum across sulfur-sulfur bond in trithione molecule

Conclusions Pt(PPh₃)₃ inserts itself across the S-S bond in the 4-methyl-5-phenyl-3H-1,2-dithiol-3-thione molecule.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1624–1626, July, 1981.     

Lattices over Noetherian algebras

An analog of the reduction theorem for modules over an integrally closed integral domain is proved for torsionfree modules over a semiprimary Noetherian algebra. The result is translated into concrete terms for pseudo-Bass and pseudohereditary algebras, and also used to study the structure of genera.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 5, pp. 604–610, May, 1990.