The Role Played by Ga-Pt Nanoparticles in the Aromatization of Lower Alkanes on ZSM-5 Zeolites

The activity and selectivity of Pt-Ga/ZSM-5 zeolites in the aromatization of ethane was studied. The temperature intervals of the stability of gallium oxides on the surface of zeolites were determined by X-ray diffraction. The formation of GaPt clusters was observed after high-temperature treatment of a mixture of platinum-containing zeolites with gallium oxides. Density functional theory was used to study the state of gallium clusters in zeolites by quantum-chemical methods. The interaction of gallium with the H-form of ZSM-5 zeolites was shown to result in the formation of cationic centers containing reduced single-charged gallium cations. The introduction of platinum stabilized alloyed Ga-Pt particles localized in zeolite channels. These particles increase catalyst activity in the aromatization of lower alkanes.     

Reactions of dl-homocystine and 3,3′-dithiodipropionic acid with Pd(II) in aqueous hydrochloric solutions. Part I: coordination model

Stoichiometry of Pd(II) interactions with dl-homocystine and 3,3′-dithiodipropionic acid were investigated spectrophotometrically in strong hydrochloric acidic media. It was established that thiolate and sulfinate complexes are products of a disulfide bond cleavage. It is shown that formation of S,S′-binuclear complexes is necessary for the disproportionation reaction. A multi-spectroscopic (UV-Vis, Raman, NMR, EXAFS) investigation on a disulfide bond state in organic disulfides in complexation processes with Pd(II) was developed. A DFT study on geometry of forming complex species was performed.     

Spectra of Fe ions in powerful SCR events

Large solar cosmic ray (SCR) events are registered by PLATAN equipment in September–October 1989 aboard the MIR orbital station and in October–November 2003 aboard the International Space Station (ISS). The energy spectra of Fe ions in the energy intervals of 5–200 MeV/nucleon (1989) and 25–90 MeV/nucleon (2003) are measured. Spectra for SCR events of 1989 and 2003 are approximated with high accuracy by the power law function of energy. The SCR events of 1989 greatly exceed those of 2003 in the fluence of Fe particles. High enrichment of the elemental composition of the SCR events 2003 with Fe ions is observed.     

Solar activity over last ten thousand years based on the data of <Superscript>10</Superscript>Be and <Superscript>14</Superscript>C cosmogeneous isotopes

The data on the ¹⁰Be accumulation rate in Greenland glacier (GRIP project) are discussed. Spectral analysis of the data over the last 9000 years is carried out. The spectral line intensity in the low-frequency range (periods from 100 to 1000 years) is much higher (approximately by a factor of 20), than in the frequency range of the 11-year solar activity cycle. This fact suggests that the processes responsible for the variations in the ¹⁰Be production rate with a time scale of 100–1000 years significantly differ from those determining the 11-year cyclicity of solar activity.     

Cosmogenic radionuclides <Superscript>14</Superscript>C and <Superscript>10</Superscript>Be: Solar activity and climate

The problem of the use of such cosmogenic nuclides as ¹⁴C and ¹⁰Be in natural archives for reconstruction of both the solar activity and the cosmic-ray intensity is discussed. The climate-dependent processes of the formation, transport, and deposition of these nuclides to Earth’s archives must be taken into account for adequate processing of information derived from such archives.     

The effect of spin fluctuations on phase transitions in magnetic systems

In this paper we study the problem of admitting an exact solution of the effect of spin fluctuations on phase transition when modeling a multiferroic superconducting system in a strong magnetic field. New results are obtained for phase portraits of the system of equations for amplitudes of spin density and temperature waves. The possibility is justified for the transition of the system to a phase in which superconductivity and antiferromagnetic ordering coexist, particularly via slowly fluctuating spin-density waves.     

Low energy heavy nuclei in Lavsan chamber on the salyut-7 space station in 1984–1985

Energy spectra of subiron (Sc---Cr) and iron nuclei in the range 40–210 MeV/n have been measured and subiron to iron abundance ratio was determined from a study of a polyethyleneterephthalate (Lavsan) detector exposed in 1984–1985 during a year on the Salyut-7 space station. The ratio measured is 0.9 in the energy range 170–210 MeV/n that confirms previous data. The value differs from that 0.4-0.5 measured in interplanetary space. The ratio is 0.45 in the range 40–110 MeV/n. The peculiarities observed are discussed.     

Catalytic aromatization of light alkanes

Experimental data on the application of pentasil-type zeolites in the aromatization of lowmolecular-weight alkanes are surveyed. Examples of the transformation of ethane and propane into aromatics over pentasils containing Zn, Ga, or Ga-Pt are given. An important role of Pt in the formation of active and selective Ga-Pt catalysts for light alkane aromatization is shown.