New catalytic systems based on fluorine-containing titanium(iv) alkoxides for the synthesis of ultrahigh-molecular-weight polyethylene and olefin elastomers

The catalytic activity of the systems based on titanium(iv) alkoxides (Ti(OPrⁱ)₄, Ti(OPrⁱ)₂(OCH(CF₃)₂)₂, and Ti(OCH(CF₃)₂)₄) and mixtures of alkylaluminum chlorides (Et₂AlCl or Et₃Al₂Cl₃) with dibutylmagnesium in ethylene polymerization and ethylene copolymerization with propylene and 5-ethylidene-2-norbornene was studied. Ultrahigh-molecular-weight polyethylene with the molecular weight reaching 4.9 · 10⁶ Da was found to be formed in the homopolymerization reaction, whereas copolymerization gives ter-copolymers containing propylene (up to 35 mol.%) and 5-ethylidene-2-norbornene (4.3 mol.%) units.

     

Optical assessment of <Emphasis Type="Italic">Dunaliella salina</Emphasis> microalgae viability upon toxicological testing

A method has been developed for monitoring the dynamics of the number and viability of Dunaliella salina microalgae taking into account the spectral contribution from aggregates of metal particles tested as a toxic agent in a microplate assay system. The method is based on the in vivo determination of the chlorophyll content from the intensity of an absorption peak at 680 nm corrected for the nonselective extinction as calculated using the values of nearest local minima at 640 and 740 nm.     

Thermochemical study of the trans- and cis-isomeric forms of 4-(4-methoxystyryl)pyridine N-oxide

The trans and cis form of 4-(4-methoxystyryl)pyridine N-oxide were studied. The spectral characteristics of cis-4-(4-methoxystyryl)pyridine N-oxide were determined in acetonitrile. The melting and thermal decomposition processes of the trans and cisforms of 4-(4-methoxystyryl)pyridine N-oxide were studied by thermochemical methods. It was establish that the thermal decomposition of 4-(4-methoxystyryl)pyridine N-oxide begins with the cleavage of the bond between the pyridine and benzene rings.

     

Metal‐Ion‐Binding Analogs of Ribonucleosides: Preparation and Formation of Ternary Pd2+ and Hg2+ Complexes with Natural Pyrimidine Nucleosides

Four metal‐ion‐binding nucleosides, viz. 2,6‐bis(1‐methylhydrazinyl)‐9‐(β‐D ‐ribofuranosyl)‐9H‐purine ( 2a ) and its N‐acetylated derivative, 2b , 2,4‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)‐5‐(β‐D ‐ribofuranosyl)pyrimidine ( 3 ), and 2,4‐bis(1‐methylhydrazinyl)‐5‐(β‐D ‐ribofuranosyl)pyrimidine ( 4 ) have been synthesized. The ability of these nucleosides and the previously prepared 2,6‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)‐9‐(β‐D ‐ribofuranosyl)‐9H‐purine to form Pd²⁺‐ and Hg²⁺‐mediated complexes with uridine has been studied by ¹H‐NMR spectroscopy. To obtain additional support for the interpretation of the NMR data, comparative measurements on the ternary‐complex formation between pyridine‐2,6‐dicarboxamide ( 5 ), pyrimidine nucleosides, and K₂PdCl₄ were carried out.     

Measurement of the Cross Section for the Process $${e^{+}e^{-}}{\to}{K}^{{+}}{K}^{{-}}{\pi}^{{0}}$$ with the SND Detector at Collision Energies of $$\sqrt{{s}}{=}{1.3{-}2.0}$$ GeV in the Center-of-Mass Frame

Physics of Atomic Nuclei - In an experiment with the SND detector at the VEPP-2000 $$e^{+}e^{-}$$ collider, the cross sections for the processes $$e^{+}e^{-}\to K^{+}K^{-}\pi^{0}$$ and...     

Study of the Process $${e}^{{+}}{e}^{{-}}{\to}{\eta\pi}^{{0}}{\gamma}$$ in the Cossision-Energy Range of $$\sqrt{{s}}{=}{1.05{-}2.00}$$ GeV

Physics of Atomic Nuclei - The process $$e^{+}e^{-}\to\eta\pi^{0}\gamma$$ is studied in the range of center-of-mass (c.m.) collision energies between 1.05 and 2.00 GeV on the basis of data...     

“Isocyanide-less” Ugi/Intramolecular Diels-Alder reaction of 5-hydroxymethylfurfural

The one-pot, three-step, four-component Ugi-IMDAF reaction with 5-hydroxymethylfurfural provides simple access to hydroxymethyl-substituted epoxyisoindolones in a diastereoselective and stereospecific manner. The protocol avoids the transfer or isolation of isocyanides, and the broad scope was illustrated by the synthesis of 22 different compounds bearing various substituents on the heterocyclic core.     

Data Acquisition and Diagnostic System for Prototype of PANDA Pellet Target

Physics of Atomic Nuclei - In the PANDA experiment of the FAIR project, it is proposed to use internal targets based on the hydrogen isotopes that provide a monodisperse regime of flow generation...     

Monodisperse spherical meso–macroporous silica particles: Synthesis and adsorption of biological macromolecules

Monodispersed spherical silica particles, including large mesopores (over 10 nm) and macropores (up to 100 nm) were obtained by chemical etching in an autoclave. A method for introducing globular protein myoglobin molecules into the pores is developed. The method of filling is based on a high adsorption capacity of the developed internal pore structure of the particles. The structure and adsorption properties of the materials are studied.