Basicities and transformations of pyrylium and pyridinium salts containing p-aminophenyl substituents

On the basis of the measured basicity constants of pyrylium and pyridinium salts containing p-aminophenyl substituents it is shown that the positive charge in the pyrylium cation is considerably higher than in the pyridinium cation. The constants of the pyrylium and pyridinium substituents, which show that the magnitude of the electronic effect of the pyrylium ring is considerably higher than that of the pyrydinium ring, were calculated. The reaction of the indicated pyrylium salts with some electrophilic and nucleophilic reagents was examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1025–1028, August, 1976.     

Heat capacity of the Pb<Subscript>5</Subscript>(Ge<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Si<Subscript>x</Subscript>)<Subscript>3</Subscript>O<Subscript>11</Subscript> ferroelectric system

The temperature dependences of the molar heat capacity at constant pressure, C_p, of Pb₅(Ge_1?xSi_x)₃O₁₁ crystals with x=0, 0.39, and 0.45 in the range 5–300 K, as well as of their permittivity, dielectric losses, and the pyroelectric effect, have been measured. Experimental data on the temperature behavior of the heat capacity are presented in the form of a sum of two Debye and one Einstein terms, C_p(T)=0.405C_D1(Θ_D1=160 K, T)+0.53C_D2(Θ_D2=750 K, T)+0.046C_E(Θ_E=47 K, T). Besides a peak in the region of the ferroelectric Curie point T_c=450 K for crystals with x=0, the temperature dependences of the heat capacity did not reveal any other pronounced anomalies.     

The microlevel size of grains and fragments as a factor determining the density of dislocations and disclinations

The role of the size effect in the formation of defect structures in metallic materials was studied experimentally. The objects of study were ultrafine grain (UFG) copper, nickel, and martensitic steel. The effect of the size of grains and fragments on the scalar density of dislocation and the density of partial disclinations was studied by means of transmission electron microscopy (TEM). Measurements were performed for the 100–500 nm range of grain and fragment sizes. Similarities was found in the behavior of grain and fragmented structures.     

Synthesis and Ritter Reaction of 2-Ethynyladamantan-2-ol

The reaction of adamantan-2-one with lithium acetylide gave 2-ethynyladamantan-2-ol. The latter reacted with acetonitrile in the presence of sulfuric acid through formation of an intermediate classical carbocation, leading to 2-acetylamino-2-ethynyladamantane and 1-acetylamino-2-acetyladamantane at a ratio of 20:1.     

Yurii Pavlovich Popov February 13, 1928–February 24, 2005 (On the 80th anniversary of his birth)

The scientific biography of the distinguished physicist experimentalist and prominent expert in the field of neutron nuclear physics Yurii Pavlovich Popov (13.02.1928–24.02.2005) is presented, including his work at Lebedev Physical Institute, AS USSR and the Joint Institute for Nuclear Research. Yu.P. Popov was a member of the editorial board of the journal Physics of Particles and Nuclei from 1971 to the end of his life.     

Magnetization and specific heat of DyFe3(BO3)4 single crystal

We present thermodynamic and magnetic studies of single crystalline DyFe₃(BO₃)₄. The data indicate an easy axis antiferromagnetic order below T_N~ 38 K which we attribute to the Fe subsystem. The Dy subsystem remains paramagnetic down to the lowest investigated temperatures of 2 K, but it is polarized by the Fe spins due to a f-d interaction. External magnetic field leads to a spin-flop transition in the iron subsystem as well as to superposed magnetization in the Dy subsystem. The repopulation of two low-lying Kramers doublets in Dy³⁺ ions results in well defined Schottky anomalies in specific heat and magnetization.