Convenient method for preparation of tert-butyl glycinate

Conclusions A convenient method was proposed for the preparation of tert-butyl glycinate by reacting N-trifluoro-acetylglycine with isobutylene and subsequent removal of the trifluoroacetyl group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, p. 1444, June, 1977.     

New method of synthesizing 1,2,5-trisubstituted piperidine derivatives by reaction of 1,3-dienes with urotropin in the presence of palladium complexes

Conclusions It has been shown for the first time that 1-(2,7-octadienyl)-2,5-divinyl- and 1-(2,7-dimethyl-2,7-octadienyl)-2, 5-diisopropenylpiperidine can be prepared by reacting urotropin with butadiene or isoprene in the presence of a Pd(acac)₂-PR₃-A1(C₂H₅)₃-H₂SO₄ catalyst (1321.5).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1359–1363, June, 1977.     

Magnetic field effect on the susceptibility of a Heisenberg ferromagnet CuK2Cl4.2H2O near the critical point

The results on the investigation of the susceptibility for the Heisenberg ferromagnet CuK₂Cl₄.2H₂O in the magnetic field are reported. The susceptibility divergence at the critical temperature in the magnetic field is shown to transform into susceptibility anomalies of two types, their shifts being approximated by the power functions with indices ω = 2.6 and ? = 0.58. The experimental data support the assumption about the complex critical temperature. The regions for the existence of phases with uniform and non-uniform magnetizations are determined.     

Study of ultrathin iron silicide films grown by solid phase epitaxy on the Si(001) surface

Ultrathin films of iron silicide have been grown by high-temperature annealing of 0.14-to O.5O-nm-thick Fe films deposited on the Si(001) surface at room temperature. It has been found that annealing leads to the formation of nanoislands of iron silicide on the surface, so that their type depends on the thickness of the Fe film. High-energy electron diffraction and atomic force microscopy measurements have revealed that the deposition of Fe films less than 0.32 nm thick on the Si(001) surface stimulates epitaxial growth of both three-dimensional β-FeSi₂ and two-dimensional γ-FeSi₂ islands. It has been found that, for Fe coverages of more than 0.32 nm thick, a complete transition to solide phase epitaxy is observed only for two-dimensional β-FeSi₂ islands. The effect of prolonged annealing at 850°C on the morphology of the surface of the iron silicide film has been investigated.     

On the sensitivity of the spatial-angular distribution of the Cherenkov light in extensive air showers to the mass composition of primary cosmic rays with energies of 10<Superscript>15</Superscript>–10<Superscript>16</Superscript> eV

This paper analyses the possibility of separating distinct groups of nuclei of primary cosmic rays with energies of 10¹⁵–10¹⁶ eV from the data on the spatial-angular distribution of Cherenkov light in extensive air showers. The paper shows that using an array of a few (3–4) telescopes with a moderately sized angular cell ∼0.5° placed at a distance ∼100 m from one another, one can achieve almost complete separation of the showers initiated by these nuclei (the Bayesian classification error is a few percentage points for the case of separating primary protons and nitrogen nuclei). The authors propose new parameters of the angular Cherenkov image that can greatly enhance the separability of the shower classes as compared to the approach based on the traditional parameters.     

Migration of CrSi2 nanocrystals through nanopipes in the silicon cap

CrSi₂ nanocrystals (NC¹) were grown by reactive deposition epitaxy of Cr at 550 °C. After deposition the Cr is localized in about 20-30 nm dots on the Si surface. The NCs were covered by silicon cap grown by molecular beam epitaxy at 700 °C. The redistribution of NCs in the silicon cap was investigated by transmission electron microscopy and atomic force microscopy. The NCs are partly localized at the deposition depth, and partly migrate near the surface. A new migration mechanism of the CrSi₂ NCs is observed, they are transferred from the bulk toward the surface through nanopipes formed in the silicon cap. The redistribution of CrSi₂ NCs strongly depends on Cr deposition rate and on the cap growth temperature.