Nucleon Instability in a Degenerate Magnetized Nucleon–Electron Gas

In the framework of the model of a degenerate relativistic ideal neutron–proton–electron gas (np ⁺ e ^– gas) in an external superstrong constant and homogeneous magnetic field, we study the effect of the magnetic field on the state of chemical equilibrium of the np ⁺ e ^– gas and on the processes of electronic (^–) and positronic (⁺) nucleon decay taking the effects due to the interaction between the nucleon anomalous magnetic moments and the magnetic field into account. For sufficiently large values of the magnetic induction, the proton density in chemical equilibrium must exceed the neutron density. Including the interaction between the nucleon anomalous magnetic moments M _n,p and the magnetic field results in an insignificant reduction of the proton density, but, as in the case M _n,p=0, the proton density in chemical equilibrium in the presence of the superstrong magnetic field exceeds the neutron density. We show that if the interaction between the nucleon anomalous magnetic moments and the superstrong magnetic field is taken into account, then the positronic decay of a free proton (i.e., a proton not entering the composition of an atomic nucleus) into a neutron, a positron, and a neutrino can become energetically allowed. We discuss the necessary conditions for realizing the phase transition from the nucleon phase to the quark phase of the substance in the central region of a strongly magnetized neutron star.     

Synthesis of bicyclo[2.2.1]hept-5-enyl methyl esters of haloacetic acids

Synthesis of norbornenyl methyl esters of a number of haloacetic acids via [4+2] cycloaddition of cyclopentadiene to allyl esters of these acids was examined. The yield and isomer composition of the synthesized compounds were examined in relation to the reaction conditions, and the best conditions for their preparation were found.     

Two-dimensional electron gas in a strong magnetic field. I

We obtain expressions for the thermodynamic potential, concentration, and magnetic moment of an ideal two-dimensional electron gas in a strong (quantizing the motion) magnetic field at low temperatures. The results are used to explain the integer quantum Hall effect.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 101–106, January, 1990.     

Are there reliable DFT approaches for 13C NMR chemical shift predictions of fullerene C60 derivatives?

The relationships between experimental and theoretical ¹³C NMR chemical shifts of a pristine fullerene C₆₀, monoadducts from [2 + n] cycloaddition (n = 1–3), and one [2 + 1] bis‐adduct are systematically analyzed for the first time by using diverse quantum‐chemical levels of theory. These levels involved B3LYP, B3PW91, B97‐2, mPW1PW91, PBE1PBE, and X3LYP hybrid functionals combined with 3‐21G, 6‐31G, 6‐31G(d), 6‐31G(d,p), 6‐31G(d,2p), LanL2DZ, and SDDAll basis sets. X3LYP/6‐31G approach is determined to have the lowest deviations from the ¹³C NMR experimental data compared to the other methods for all the fullerene compounds (mean absolute error value is 0.856 ppm and root mean squared error value is 1.197 ppm). The highest deviations are characteristic for α (sp² C2/C5/C8/C10) and β (sp² C6/C7/C11/C12) carbon atoms relative to a functionalization site and for those (sp³ C1/C9) directly attached with a side fragment in the [2 + n] monoadducts (n = 1–3). A probable reason of such deviation is that the approaches do not take into account a contribution of paramagnetic ring currents to ¹³C NMR chemical shifts. The results will be useful in design of novel fullerene derivatives and in performing unambiguous ¹³C NMR chemical shift assignments with modern quantum chemistry calculations.     

Synthesis of functionally substituted methanofullerenes and study of their tribological properties

Possibility of synthesizing functionally substituted methanofullerenes by cycloaddition of diazo derivatives of methionine and threonine to C₆₀ fullerene in the presence of a three-component catalytic system Pd(acac)₂-PPh₃-Et₃Al was examined. Tribological characteristics of the resulting compound as an additive to an industrial oil were studied.     

Multicomponent heterocyclization of hydrazine,hydrogen sulfide,and formaldehyde

Multicomponent heterocyclization of hydrazine, hydrogen sulfide, and formaldehyde gave previously unknown bi-, tri-, and tetracyclic nitrogen- and sulfur-containing heterocycles. 3,7-Dithia-1,5-diazabicyclo[3.3.0]octane, 4,9-dithia-1,2,6,7-tetraazatricyclo[5.3.1.1^2,6]dodecane, and 4,9,14-trithia-1,2,6,7,11,12-hexaazatetracyclo[10.3.1.1^2,6.1^7,11]octadecane were obtained selectively, depending on the reaction temperature (0–60 °C).Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1652–1656, August, 2004.     

A quantum chemical study of self-association of HAlBu 2i and ClAlBu 2i

The self-association of di-iso-butylaluminum hydride and di-iso-butylaluminum chloride is studied at the level of density functional theory and second order M?ller-Plesset perturbation theory. Thermodynamic parameters of the monomeric, dimeric, trimeric, and tetrameric forms of HAlBu₂ ⁱ and ClAlBu₂ ⁱ in a range of 203 K to 373 K are calculated. The energy of solvation is taken into account by the COSMO polarized continuum model. Based on the obtained results the equilibrium concentrations of the associated forms of organoaluminum compounds (OACs) are calculated, which agree with the experimental data. So, at room temperature the dimeric or trimeric forms of OACs are dominant in the gas phase and non-polar solvents; the tetrameric form is present, while the concentration of the monomeric form is negligibly low and decreases with decreasing temperature or diluting.     

Effect of chemical modification on oligomerization capacity of alumina support for Pd-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalyst

Effect of modification with an alkali metal on the acid properties of alumina supports and on the oligomerization capacity and working stability of Pd-Al₂O₃ catalysts was studied.