Synthesis and crystal structure of the palladium oxides NaPd3O4, Na2PdO3 and K3Pd2O4

NaPd₃O₄, Na₂PdO₃ and K₃Pd₂O₄ have been prepared by solid-state reaction of Na₂O₂ or KO₂ and PdO in sealed silica tubes. Crystal structures of the synthesized phases were refined by the Rietveld method from X-ray powder diffraction data. NaPd₃O₄ (space group Pm3¯n, a=5.64979(6) Å, Z=2) is isostructural to NaPt₃O₄. It consists of NaO₈ cubes and PdO₄ squares, corner linked into a three-dimensional framework where the planes of neighboring PdO₄ squares are perpendicular to each other. Na₂PdO₃ (space group C2/c, a=5.3857(1) Å, b=9.3297(1) Å, c=10.8136(2) Å, β=99.437(2)°, Z=8) belongs to the Li₂RuO₃-structure type, being the layered variant of the NaCl structure, where the layers of octahedral interstices filled with Na⁺ and Pd⁴⁺ cations alternate with Na₃ layers along the c-axis. Na₂PdO₃ exhibits a stacking disorder, detected by electron diffraction and Rietveld refinement. K₃Pd₂O₄, prepared for the first time, crystallizes in the orthorhombic space group Cmcm (a=6.1751(6) Å, b=9.1772(12) Å, c=11.3402(12) Å, Z=4). Its structure is composed of planar PdO₄ units connected via common edges to form parallel staggered PdO₂ strips, where potassium atoms are located between them. Magnetic susceptibility measurements of K₃Pd₂O₄ reveal a Curie-Weiss behavior in the temperature range above 80 K.     

Synthesis and properties of pyrimidinylalkylphosphonic acids

Conclusions Some esters of -(oxodihydro-N-pyrimidinyl)butyl- and -(oxodihydro-N-pyrimidinyi)pentylphosphonic acids, and also some diphenyl -(2,4-dioxo-6-methyl-1,2,3,4-tetrahydro-N-pyrimidinyl)alkyl phosphates, were synthesized.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1397–1401, June, 1975.     

Growth and optical properties of filamentary GaN nanocrystals grown on a hybrid SiC/Si(111) substrate by molecular beam epitaxy

The potential to grow filamentary GaN nanocrystals by molecular beam epitaxy on a silicon substrate with a nanosized buffer layer of silicon carbide has been demonstrated. Morphological and optical properties of the obtained system have been studied. It has been shown that the intensity of the photoluminescence spectrum peak of such structures is higher than that of the best filamentary GaN nanocrystals without the buffer silicon carbide layer by a factor of more than two.     

Reactions of P(III)-Halides with Calix[4]Resorcinarenes

Abstract

Reactions of calix[4]resorcinarenes, bearing aliphatic radicals of different length, with P(III)-halides results in the formation of cyclic chlorophosphites and chlorophosphates.     

Electrophysiological Activity and Survival Rate of Rats Nervous Tissue Cells Depends on D/H Isotopic Composition of Medium

The deuterium content modification in an organism has a neuroprotective effect during the hypoxia model, affecting anxiety, memory and stress resistance. The aim of this work was to elucidate the possible mechanisms of the medium D/H composition modification on nerve cells. We studied the effect of an incubation medium with a 50 ppm deuterium content compared to a medium with 150 ppm on: (1) the activity of Wistar rats’ hippocampus CA1 field neurons, (2) the level of cultured cerebellar neuron death during glucose deprivation and temperature stress, (3) mitochondrial membrane potential (MMP) and the generation of reactive oxygen species in cultures of cerebellar neurons. The results of the analysis showed that the incubation of hippocampal sections in a medium with a 50 ppm deuterium reduced the amplitude of the pop-spike. The restoration of neuron activity was observed when sections were returned to the incubation medium with a 150 ppm deuterium content. An environment with a 50 ppm deuterium did not significantly affect the level of reactive oxygen species in neuron cultures, while MMP decreased by 16–20%. In experiments with glucose deprivation and temperature stress, the medium with 50 ppm increased the death of neurons. Thus, a short exposure of nerve cells in the medium with 50 ppm deuterium acts as an additional stressful factor, which is possibly associated with the violation of the cell energy balance. The decrease in the mitochondrial membrane potential, which is known to be associated with ATP synthesis, indicates that this effect may be associated with the cell energy imbalance. The decrease in the activity of the CA1 field hippocampal neurons may reflect reversible adaptive changes in the operation of fast-reacting ion channels.     

Self-assembling catalytic systems based on new amphiphile containing purine fragment,exhibiting substrate specificity in hydrolysis of phosphorus acids esters

Micellar catalytic systems based on new purine-containing amphiphile for hydrolytic decomposition of organophosphorus toxicants have been prepared. The aggregation threshold of the system has been estimated by means of tensiometry, conductometry, spectrophotometry, and dynamic light scattering. The solubilizing action of the amphiphile towards the hydrophobic dye has been demonstrated. Kinetic studies of hydrolysis of phosphonates differing in the hydrophobicity have disclosed the substrate specificity of the micellar catalysts; inhibition instead of catalysis has been observed in the case of the less hydrophobic substrate.     

Die Zerlegung des Aufwands für Altersversorgungsverpflichtungen aus aktuarieller Sicht

According to the German Accounting Law Modernization Act (BilMoG) it is now mandatory to split the regular pension expense into a finance cost component and an operating cost component. In this article we discuss some possible approaches of how such a decomposition could be accomplished from an actuarial perspective.